Composite nano metal oxide and preparation method and application thereof

Abstract

The invention relates to a preparation method of a composite nano metal oxide and a composite oxide ceramic. An intermetallic compound containing Al / Zn and target multi-metal elements is used as an initial alloy, the initial alloy is subjected to nano fragmentation through a hydrogen evolution Al / Zn removal reaction under certain alkali concentration and temperature conditions, and the multi-component composite nano metal oxide is prepared through further shape and component recombination. The preparation method disclosed by the invention has the characteristics of being short in reaction time, simple in process, easy to operate and low in cost; the method has good application prospects in the fields of composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, color-changing materials, wave-absorbing materials, sewage degradation materials, sterilization materials, coatings, pigments, thermal spraying materials, sensors and the like.

Description

A composite nano-metal oxide and its preparation method and use Technical Field

[0001] The present invention relates to the technical field of nanomaterials, in particular to a preparation method of composite nano metal oxides and composite oxide ceramics. Background Art

[0002] The most common method for preparing nano-metal oxides is to add alkali to a soluble metal salt solution for precipitation. The resulting nanopowder is then filtered, dried, and calcined. However, this method produces a precipitate that is mostly colloidal hydroxide, requiring long filtration times, which significantly increases the production cycle. Furthermore, hydrogen bonds easily form between the precipitates, leading to particle agglomeration and growth during filtration, drying, and high-temperature calcination. This makes it difficult to obtain a powder with uniform particle size, good dispersion, and no hard agglomerates.

[0003] The composite nano metal oxide prepared by conventional methods generally adopts the method for mixing powders to prepare, and different components need at least be carried out separately in the preparation step, and process is loaded down with trivial details. Moreover, after the powder mixing, each component is generally compounded together by the mode of physical adsorption or simple mixing, and this mixing is often difficult to reach sufficiently uniform effect. However, in some application fields, it is necessary to mix uniformly as much as possible between each component, or even need in-situ compounding to realize the special interaction between each component, to obtain special excellent performance. Therefore, it is urgent to develop a novel method for the composite nano metal oxide that can in-situ compound between different oxide components by a preparation process.

[0004] Summary of the Invention

[0005] Based on this, it is necessary to provide a method for preparing composite nano-metal oxides with simple process, mild conditions and suitable for large-scale production to address the above problems, wherein the different components of the prepared product can be in situ embedded in each other. The present invention includes twelve aspects, namely, aspects 1 to 12:

[0006] In one aspect, a method for preparing a composite nano-metal oxide is characterized by comprising the following steps:

[0007] Step 1: providing an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A-type elements. x Ty , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds;

[0008] Step 2: The initial alloy undergoes a hydrogen evolution and de-tantalum reaction with an alkaline solution, and by controlling the temperature T1 and concentration C1 of the alkaline solution, the reaction interface is advanced inward from the surface of the initial alloy at an average rate of not less than 2 μm / min during the reaction;

[0009] When the initial alloy does not contain D-type sub-elements, the initial alloy and the alkaline solution undergo nano-fragmentation through hydrogen evolution and de-Ti reaction, and the shape and composition are reconstructed to generate a solid material containing M and Ti, the size of at least one dimension of which does not exceed 500 nm in the three-dimensional direction;

[0010] When the initial alloy contains a D-type daughter element, the initial alloy and the alkaline solution undergo nano-fragmentation through a hydrogen evolution and de-Ti reaction, and undergo shape and composition reconstruction to generate a solid material containing M or (and) Ti, the shape of which has at least one dimension in the three-dimensional direction not exceeding 500 nm. At the same time, the D-type daughter element is mainly dissolved in the alkaline solution under conditions of an alkali concentration and temperature corresponding to a high reaction rate, or is mainly converted into a solid material containing D through shape and composition reconstruction under conditions of an alkali concentration and temperature corresponding to a relatively low reaction rate.

[0011] Step 3: After the hydrogen evolution and de-T reaction is completed,

[0012] When the initial alloy does not contain D-type sub-elements, the solid matter containing M and Ti in the reaction system is collected to obtain a composite nano-metal oxide intermediate product containing M and Ti, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedded composite; wherein the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can be corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase;

[0013] When the initial alloy contains sub-elements of type D and the sub-elements of type D mainly exist as solid substances containing D, all solid substances in the reaction system are collected, and a composite nano-metal oxide intermediate product composed of an intermediate product containing D and an intermediate product containing M or (and) Ti is obtained. Its shape has at least one dimension not exceeding 500 nm in three-dimensional directions; and the way of composite between the intermediate product containing D, the intermediate product containing M, and the intermediate product containing Ti includes in-situ intergrowth composite; among them, the intermediate product containing D, the intermediate product containing M, and the intermediate product containing Ti can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the intermediate product containing D, the intermediate product containing M, and the intermediate product containing Ti is a phase;

[0014] When the initial alloy contains sub-elements of type D and the sub-elements of type D are mainly dissolved in the alkali solution, the liquid is added to the reaction system described in step two to reduce the concentration of the alkali solution to below the concentration C2 at which solid flocculent hydroxide D can precipitate. The precipitated solid flocculent hydroxide D is mixed with the previously formed solid substance containing M or (and) Ti, and all solid substances are collected, and a composite nano-metal oxide intermediate product composed of nano-hydroxide D and an intermediate product containing M or (and) Ti is obtained. Its shape has at least one dimension not exceeding 500 nm in three-dimensional directions; where C2 < C1, and when the composite nano-metal oxide intermediate product simultaneously includes an intermediate product containing M and an intermediate product containing Ti, the way of composite between the intermediate product containing M and the intermediate product containing Ti includes in-situ intergrowth composite; among them, the intermediate product containing M and the intermediate product containing Ti can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the intermediate product containing M and the intermediate product containing Ti is a phase;

[0015] Step four, heat-treat the composite nano-metal oxide intermediate product described in step three to obtain a composite nano-metal oxide with improved crystallization degree; it contains at least two of the three types of sub-elements: element Ti, sub-elements of type M, and sub-elements of type D; and at least two of the three types of sub-elements: element Ti, sub-elements of type M, and sub-elements of type D are composite of corresponding oxides of different elements at the atomic / atomic cluster scale or the scale of fine phases.

[0016] In the said step one,<s

[0017] Furthermore, M includes at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, Gd;

[0018] Furthermore, T includes Al; furthermore, T includes Zn;[[ID=?]]

[0019] Furthermore, 19 ≤ x ≤ 55%, 45% ≤ y ≤ 81%;

[0020] Furthermore, the composition of the type A elements in the initial alloy includes any one of the following four combinations:

[0021] 1) Ti element, M type sub-element; 2) D type sub-element, M type sub-element;

[0022] 3) D-type sub-element, Ti element; 4) D-type sub-element, Ti element, M-type sub-element;

[0023] Furthermore, among the three types of sub-elements in the A-type elements, namely, the D-type sub-elements, the Ti-type sub-elements, and the M-type sub-elements, the molar percentage of the sub-type element that occupies a dominant position in the A-type elements is less than 99%; for example, when the A-type elements are composed of Nb and Ti, and Nb occupies a dominant position in the content, the molar percentage of Nb in the total content of Nb and Ti needs to be less than 99%;

[0024] Furthermore, the molar percentage of the dominant sub-category element in the A-category elements is less than 95%;

[0025] Furthermore, the molar percentage of the dominant sub-category element in the A-category elements is less than 90%;

[0026] Furthermore, the molar percentage of the dominant sub-category element in the A-category elements is less than 80%;

[0027] Further, the molar percentage of the D-type sub-element in the A-type element is higher than 30%; further, the molar percentage of the D-type sub-element in the A-type element is higher than 60%; further, the molar percentage of the D-type sub-element in the A-type element is higher than 90%;

[0028] Further, the molar percentage of the M-type sub-element in the A-type element is higher than 30%; further, the molar percentage of the M-type sub-element in the A-type element is higher than 60%; further, the molar percentage of the M-type sub-element in the A-type element is higher than 90%;

[0029] Further, the molar percentage of Ti in the A-type elements is higher than 30%; further, the molar percentage of Ti in the A-type elements is higher than 60%; further, the molar percentage of Ti in the A-type elements is higher than 90%;

[0030] Furthermore, the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds; wherein the AT intermetallic compounds are single-phase intermetallic compounds or multi-phase intermetallic compounds; and when the AT intermetallic compounds are multi-phase intermetallic compounds, they include at least two of Ti-T intermetallic compounds, MT intermetallic compounds, DT intermetallic compounds, (MD)-T intermetallic compounds, (Ti-D)-T intermetallic compounds, (Ti-M)-T intermetallic compounds, and (Ti-MD)-T intermetallic compounds;

[0031] When the AT intermetallic compound is a single-phase intermetallic compound, it is one of a (MD)-T intermetallic compound, a (Ti-D)-T intermetallic compound, a (Ti-M)-T intermetallic compound, and a (Ti-MD)-T intermetallic compound;

[0032] Furthermore, in the initial alloy, the specific phase composition of the AT intermetallic compound is not limited, as long as the A-type element is present in the AT intermetallic compound, that is, the A-type element atoms are dispersed in the initial alloy and arranged adjacent to the T-type element atoms; or as long as the initial alloy does not contain an A phase composed of the A-type element (in the A phase, the A-type element atoms are aggregated and arranged in the initial alloy);

[0033] Furthermore, the initial alloy is prepared by solidifying an alloy melt containing T-type elements and A-type elements, and a solidification structure mainly composed of AT intermetallic compounds is formed during the solidification process of the alloy;

[0034] Furthermore, the initial alloy does not contain T phase; the T phase is a phase mainly composed of T elements;

[0035] Furthermore, the solidification rate of the initial alloy melt is 0.01K / s to 10 8 K / s;

[0036] Furthermore, the solidification rate of the initial alloy melt is 1K / s to 10 8 K / s;

[0037] Furthermore, the shape of the initial alloy includes at least one of granular, filamentous, strip, ribbon, and sheet;

[0038] Furthermore, the shape of the initial alloy has an average size in any three-dimensional direction greater than 4 μm;

[0039] Furthermore, the shape of the initial alloy has an average size in any three-dimensional direction greater than 10 μm;

[0040] Furthermore, the shape of the initial alloy has an average size in any three-dimensional direction greater than 15 μm;

[0041] Furthermore, when the initial alloy is in the form of a strip, it can be prepared by a method including a melt stripping method;

[0042] Furthermore, when the initial alloy is in granular form, a larger initial alloy ingot can be prepared by a casting method and then crushed into initial alloy particles.

[0043] In the step 2,

[0044] Further, the alkaline solution comprises at least one of NaOH, KOH, LiOH, RbOH, CsOH, Ba(OH)2, Ca(OH)2, and Sr(OH)2 solutions;

[0045] Furthermore, the solvent in the alkaline solution includes water; preferably, the solvent in the alkaline solution is water;

[0046] Furthermore, the range of C1 is 4 to 30 mol / L; preferably, the range of C1 is 5 to 15 mol / L; preferably, the range of C1 is 7 to 15 mol / L;

[0047] Furthermore, the alkali in the alkali solution reacting with the initial alloy is in excess dosage, and the volume of the alkali solution is more than 5 times the volume of the initial alloy, so that the reaction can be carried out at a higher alkali concentration.

[0048] Furthermore, the volume of the alkaline solution is more than 10 times the volume of the initial alloy;

[0049] Furthermore, the volume of the alkaline solution is more than 20 times the volume of the initial alloy;

[0050] Furthermore, under certain alkali concentration C1 conditions, the temperature of the alkali solution can ensure that the reaction interface advances inward from the initial alloy surface at an average rate of not less than 2 μm / min during the hydrogen evolution de-Ti reaction, and the initial alloy can be nano-fragmented by the hydrogen evolution de-Ti reaction during the reaction. That is, the required temperature T1 of the alkali solution is determined by the hydrogen evolution de-Ti reaction rate or the hydrogen evolution de-Ti reaction time (the reaction rate is determined by the initial alloy size, and the reaction time is determined) and the reaction effect. Therefore, when the reaction conditions are defined by the reaction rate value, the temperature T1 value and concentration value range of the alkali solution are also indirectly defined at the same time, that is, the values ​​of the temperature T1 and the concentration C1 are not specifically limited, but are directly based on the combination of T1 and C1 that satisfies the requirement that the reaction interface advances at an average rate of not less than 2 μm / min during the hydrogen evolution de-Ti reaction.

[0051] Furthermore, the average rate of 2 μm / min is the critical reaction rate at which the initial alloy can undergo nano-fragmentation through hydrogen evolution and de-T reaction during the reaction process;

[0052] Furthermore, the nano-fragmentation refers to the fragmentation of the initial alloy into a single intermediate product or product with a size of less than 500 nm in at least one dimension in the three-dimensional direction through the hydrogen evolution and de-Ti reaction;

[0053] Furthermore, the nano-fragmentation refers to the fragmentation of the initial alloy into a single intermediate product or product with at least one dimension less than 250 nm in three dimensions through the hydrogen evolution and de-Ti reaction;

[0054] Further, the T1 is ≥ 60°C; further, the T1 is ≥ 80°C; further, T1 is > 100°C;

[0055] Furthermore, the reaction of the initial alloy with the alkaline solution is carried out under normal pressure or high pressure;

[0056] Furthermore, the reaction of the initial alloy with the alkaline solution is carried out in a closed container;

[0057] In a closed container, when the pressure inside the container exceeds one atmospheric pressure, it is considered high pressure; at the same time, if the gas produced by the reaction in the container cannot be discharged, additional high pressure can also be formed.

[0058] Furthermore, when the reaction is carried out in a sealed container, the initial alloy and the alkaline solution are first placed separately in the sealed container. When the temperature of the alkaline solution reaches the set reaction temperature, the initial alloy is brought into contact with the alkaline solution to carry out the reaction.

[0059] Furthermore, in a closed container, the temperature of the alkaline solution may exceed its boiling point at normal pressure;

[0060] Furthermore, 100°C <T1≤T f溶液 , the reaction of the initial alloy with the alkaline solution is carried out at normal pressure; wherein, T f溶液 is the boiling point temperature of the alkaline solution involved in the reaction under normal pressure; further, the normal pressure refers to the atmospheric pressure when no closed container is used;

[0061] Furthermore, the reaction is carried out under normal pressure, which generally refers to 1 standard atmosphere. At this time, the boiling point of water is 100°C. When alkali is dissolved in water, the boiling point of the aqueous solution of the alkali under 1 standard atmosphere is higher than 100°C, and the higher the concentration of the alkali, the higher its boiling point. For example, the boiling point of a NaOH solution with a molar concentration of 5 mol / L is T f溶液 About 108℃; NaOH solution with a molar concentration of 7 mol / L, boiling point T f溶液About 112℃; NaOH solution with a molar concentration of 10mol / L, boiling point T f溶液 About 119℃; NaOH solution with a molar concentration of 12mol / L, boiling point T f溶液 About 128℃; NaOH solution with a molar concentration of 15mol / L, boiling point T f溶液 About 140℃; NaOH solution with a molar concentration of 17mol / L, boiling point T f溶液 About 148℃; NaOH solution with a molar concentration of 20mol / L, boiling point T f溶液 About 160℃; NaOH solution with a molar concentration of 25mol / L, boiling point T f溶液 About 180℃; KOH solution with a molar concentration of 10mol / L, boiling point T f溶液 About 125℃; KOH solution with a molar concentration of 12mol / L, boiling point T f溶液 About 136℃; KOH solution with a molar concentration of 15mol / L, boiling point T f溶液 About 150℃;

[0062] Furthermore, 101℃≤T1≤T f溶液 ; Further, 105℃≤T1≤T f溶液 ;

[0063] Furthermore, 101℃≤T f溶液 -5℃≤T1≤T f溶液 ; Further, 101℃≤T f溶液 -2℃≤T1≤T f溶液 ;

[0064] As further preferred, the temperature of the alkaline solution is T f溶液 , that is, T1=T f溶液 ;

[0065] Since the highest temperature to which the reaction solution can be heated under normal pressure is its boiling point (T f溶液 ). Once the temperature reaches this point, further heating will not increase the solution's temperature; it will simply boil. To increase the reaction temperature, the concentration of the alkaline solution can be increased to achieve a higher boiling point. Therefore, controlling the boiling point is the easiest, simplest, and most precise. Furthermore, at the same concentration, reactions at the boiling point require shorter reaction times than reactions at temperatures below the boiling point, resulting in higher product yields and efficiency.

[0066] The T-type element includes at least one of Al and Zn, and Al and Zn are amphoteric metals that can react with alkaline solutions to form salts and thus dissolve in alkaline solutions. Therefore, the T-type element in each intermetallic compound in the initial alloy can be removed by the reaction between the T-type element and the alkaline solution;

[0067] Furthermore, the characteristics of the hydrogen evolution and de-T reaction are as follows: T-type elements in the initial alloy dissolve into the solution, and hydrogen gas is simultaneously evolved.

[0068] Furthermore, the intensity of the hydrogen evolution and de-T reaction is related to the reaction progress rate from the surface of the initial alloy into the interior per unit time. The higher the values of T1 and C1, the faster the reaction progress rate and the more intense the reaction.

[0069] For example, when the NaOH concentration is 10 mol / L, during the reaction of the initial alloy mainly composed of (TiNb)Al3 intermetallic compound with the alkaline solution, the reaction progress rate from the surface of the initial alloy into the interior is as follows:

[0070] When 60°C ≤ T1 ≤ 80°C, the average reaction progress rate of the reaction interface is about 2 μm / min to 7 μm / min;

[0071] When 80°C ≤ T1 ≤ 90°C, the average reaction progress rate of the reaction interface is about 7 μm / min to 15 μm / min;

[0072] When 90°C < T1 ≤ 100°C, the average reaction progress rate of the reaction interface is about 15 μm / min to 30 μm / min;

[0073] When 100°C < T1 ≤ 110°C, the average reaction progress rate of the reaction interface is about 30 μm / min to 50 μm / min;

[0074] When 110°C < T1 < 119°C, the average reaction progress rate of the reaction interface is about 50 μm / min to 120 μm / min;

[0075] T 1＝ T f溶液 When T, the average reaction progress rate of the reaction interface is greater than 120 μm / min;

[0076] Furthermore, during the reaction process, the reaction interface advances from the surface of the initial alloy into the interior at an average rate of not less than 7 μm / min;

[0077] Furthermore, the reaction interface advances from the surface of the initial alloy into the interior at an average rate of not less than 15 μm / min;

[0078] Furthermore, the reaction interface advances from the surface of the initial alloy into the interior at an average rate of not less than 30 μm / min;

[0079] Furthermore, ultrasonic waves are applied during the hydrogen evolution and de-T reaction process to further enhance the nano-fragmentation effect and reaction rate through ultrasonic treatment;

[0080] Furthermore, the frequency of the ultrasound is 20kHz~10 6 kHz;

[0081] Furthermore, under certain alkali concentration C1 conditions, the temperature T1 of the alkali solution only needs to be able to ensure that the reaction interface during the hydrogen evolution de-TiO reaction advances inward from the initial alloy surface at an average rate of not less than 2 μm / min, and that the initial alloy can undergo nano-fragmentation through the hydrogen evolution de-TiO reaction during the reaction. Therefore, under different initial alloy conditions or alkali solution conditions, when the reaction interface during the hydrogen evolution de-TiO reaction proceeds at an average rate of not less than 2 μm / min, the required reaction solution temperature may be lower than 60°C; especially when supplemented with ultrasonic treatment, the required reaction solution temperature may be even lower.

[0082] During the hydrogen evolution and de-Ti reaction of the initial alloy with the alkaline solution, the Ti element, the M-type sub-element, and the D-type sub-element have different intermediate product evolution and formation trends: specifically,

[0083] The Ti element has a tendency to generate a nano titanate intermediate product after the shape and composition are reconstructed and evolved; further, the Ti-containing intermediate product is mainly a nano titanate; further, the shape of the nano titanate is mainly a thin film with a thickness of 0.5nm-5nm, and the average area of ​​the film is greater than 100nm 2 ; Further, the cations in the nano titanate correspond to the cations in the alkaline solution of the reaction system; if the alkaline solution of the reaction system is NaOH, the titanate is sodium titanate;

[0084] After the M-type sub-elements undergo shape and composition reconstruction and evolution, they tend to generate nano-oxidized M intermediate products. Furthermore, the M-containing intermediate products are primarily nano-oxidized M. Furthermore, the nano-oxidized M has a shape that includes at least one of a film, granular, plate-like, strip-like, tubular, or flocculent. The flocculent shape refers to a state in which extremely small, non-angular microstructures are aggregated together. Furthermore, the shape of the nano-oxidized M has at least one dimension in the three-dimensional direction that does not exceed 500 nm.

[0085] Furthermore, the nano-oxide M includes at least one of low-crystallinity nano-oxide M, crystalline nano-oxide M, and hydrated nano-oxide M; the low-crystallinity nano-oxide M includes amorphous nano-oxide M; since nano-oxide M can be regarded as a combination of nano-oxide M and H2O, nano-oxide M can be obtained by heating and dehydrating at a relatively low temperature, the hydrated nano-oxide M is nano-oxide M;

[0086] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0087] D-type sub-elements (Zr and Hf elements) tend to dissolve in the alkaline solution under the conditions of alkaline concentration and temperature corresponding to high reaction rates;

[0088] D-type daughter elements (Zr, Hf elements) tend to generate D-containing solid substances after shape and composition reconstruction and evolution under the conditions of alkali concentration and temperature corresponding to relatively low reaction rates, and this D-containing solid intermediate product includes at least one of solid nano-hydrogen D and solid DO2;

[0089] Furthermore, the high reaction rate is an average reaction rate greater than 15 μm / min;

[0090] Furthermore, the relatively low reaction rate is an average reaction rate of less than 15 μm / min;

[0091] Furthermore, the shape of the D-containing solid intermediate product has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0092] Furthermore, when the reaction is carried out under normal pressure, the alkaline solution is a hot alkaline solution (such as T1>100°C), especially when the boiling point temperature of the hot alkaline solution is T f溶液 When it occurs, the dissolution of type D sub-elements is most obvious.

[0093] The dissolution of the D-type sub-element is that the simple DT intermetallic compound can be dissolved in an alkaline solution of a certain temperature and concentration corresponding to a higher reaction rate to obtain a clear and transparent solution; this is the most unique phenomenon of the D-type element participating in the hydrogen evolution and de-T reaction through the DT intermetallic compound.

[0094] It should be noted that the evolution and formation trends of the above-mentioned intermediate products are the characteristics and trends displayed when the molar percentage content of each type of sub-element in the corresponding A-type elements (Ti element, M-type sub-elements, D-type sub-elements) (see step 1) is dominant; when the molar percentage content of a certain type of sub-element is not dominant, due to the mutual influence of the intermediate products corresponding to each sub-type element during the formation process, it may not show the evolution and formation trend when it is dominant.

[0095] Furthermore, the term "dominant" refers to a situation where the molar percentage of each sub-element in the A-type elements (Ti element, M-type sub-elements, and D-type sub-elements) exceeds 60%. Furthermore, the term "dominant" refers to a situation where the molar percentage of each sub-element in the A-type elements (Ti element, M-type sub-elements, and D-type sub-elements) exceeds 75%.

[0096] For example, if the Ti:Nb ratio in the A-type elements is 90:10, with a Ti molar ratio of 90%, the AT intermetallic compound undergoes a shape and compositional reconfiguration to form two-dimensional thin-film nanotitanates. However, due to the low Nb content, it may not exhibit the evolution and formation trends observed when it was dominant. That is, it may not form independently dispersed nano-M oxides, but instead directly in situ embed within the two-dimensional thin-film nanotitanates. This in situ embedding can occur as atoms or atomic clusters (Ti and M coexist in the nanotitanate, with M considered a solid solution element) or as nano-M oxide particles. When the Ti:Nb ratio is 50:50, neither Ti nor Nb dominates. The intermediate products generated by the AT intermetallic compound's shape and compositional reconfiguration may continue to follow the evolutionary trends observed when each dominated, or, due to the interaction of the high Ti and Nb contents, may no longer follow the evolutionary trends observed when each dominated, but instead exhibit a completely new evolutionary trend.

[0097] In particular, when the above-mentioned situation in which the sub-class elements are not dominant occurs, it just reflects the great advantages of the various steps of the present application on one aspect, as well as the subsequent other aspects of preparing composite nano-metal oxides: because the key to the performance of the composite nano-metal oxide lies in the performance of the final prepared product, when the sub-class elements produce a great interaction and influence during the hydrogen evolution and de-T process and change the evolution and formation trend when each is dominant, a uniform compound that cannot be obtained by other methods can be obtained; after this uniform compound state exists in the process described in step 2 on the one hand, it will continue to exist and have an impact in the preparation process corresponding to steps 3 and 4 on the one hand (the third aspect and the fourth aspect will not be repeated); and this uniform compound is not only reflected in the physical mixing uniformity, but also in the chemical uniform compound, such as the generation of a new single-phase composite material, which simultaneously includes two to three sub-class elements and is uniformly distributed at the atomic or atomic cluster scale, such as the newly compounded single-phase nano-Ti / M oxide, which is different from both the single-phase nano-Ti oxide and the single-phase nano-M oxide; this special compound can enable the finally obtained composite nano-metal oxide to obtain extremely excellent performance. Therefore, not only one aspect of this application, but also the subsequent descriptions of the characteristics of the Ti-containing intermediate product, the M-containing intermediate product, and the D-containing intermediate product generated by the hydrogen evolution and T-removal reaction of the AT intermetallic compound are all characteristics when each component is dominant. When each component is not dominant, it may each meet the above trends and characteristics, or it may each not meet the above trends and characteristics. However, when the above trends and characteristics are not met, no matter what the new product generated is or what its morphology is, it just meets the characteristics of a more uniform and thorough composite, which is conducive to obtaining a composite nano-metal oxide and subsequent products with better performance.

[0098] When the initial alloy does not contain D-type sub-elements, the initial alloy and the alkaline solution undergo nano-fragmentation through hydrogen evolution and de-T reaction, and the shape and composition are reconstructed to generate a solid material containing M and Ti, the size of at least one dimension in the three-dimensional direction of which does not exceed 500 nm.

[0099] Furthermore, the solid material containing M and Ti is mainly a composite of nano-oxidized M and nano-titanate; the characteristics of the solid material containing M and Ti are described in detail in the above-mentioned section on the evolution and formation trend of each intermediate product;

[0100] When the initial alloy contains a D-type daughter element, the initial alloy and the alkaline solution undergo a hydrogen evolution and de-T reaction, resulting in nano-fragmentation, and undergoing shape and composition reconstruction to generate a solid material containing M or (and) Ti. Simultaneously, the D-type daughter element primarily dissolves in the alkaline solution under conditions of an alkaline concentration and temperature corresponding to a high reaction rate, or primarily generates a D-containing solid material through shape and composition reconstruction under conditions of an alkaline concentration and temperature corresponding to a relatively low reaction rate. The characteristics of the M-, Ti-, and D-containing solid materials are detailed in the above-mentioned sections on the evolution and formation trends of the respective intermediate products.

[0101] Furthermore, when the solid material containing M or (with) Ti is formed, since the D-type daughter elements, M-type daughter elements, and Ti elements in the original AT intermetallic compound are often uniformly distributed at the atomic scale in the same phase, such as the Al3(TiZr) phase, a small amount of D-type daughter elements are inevitably trapped in the solid material containing M or (with) Ti. As a result, a small amount of D-type daughter elements participate in the complex in the solid material containing M or (with) Ti, while most of the D-type daughter elements are dissolved in the alkaline solution.

[0102] Furthermore, the nano-fragmentation refers to the fragmentation of the initial alloy at the reaction interface through the hydrogen evolution and de-Ti reaction, and the simultaneous reconstruction of shape and composition to generate nano-scale solid substances containing M or (and) Ti; in this process, the hydrogen violently released by the hydrogen evolution and de-Ti reaction promotes the nano-fragmentation of intermediates and products, as well as the diffusion and distribution of the products in the alkaline solution after leaving the reaction interface.

[0103] Furthermore, after the nano-fragmentation, the fragmented solid matter containing M or (and) Ti does not contain a three-dimensional continuous network nanoporous structure or porous skeleton structure;

[0104] Furthermore, the size of the solid matter containing M or (and) Ti is less than 0.25 times the size of the initial alloy before nano-fragmentation;

[0105] Furthermore, the size of the solid matter containing M or (and) Ti is less than 0.05 times the size of the initial alloy before nano-fragmentation;

[0106] Regardless of whether the initial alloy is in strip form or crushed into powder, due to the limitation of technology level, its thickness or particle size is generally at least several microns, such as 5μm or more; while the particle size or thickness of the solid material containing M or (and) Ti does not exceed 500nm, indicating that it has undergone a sufficient nano-fragmentation process.

[0107] Furthermore, the shape reconstruction refers to the nanoscale solid matter containing M or (and) Ti obtained by the hydrogen evolution and de-Ti reaction, which is not a simple physical fragmentation of the nanoporous structure (ligament), but a shape change other than physical fragmentation.

[0108] Generally speaking, in conventional concentrated alkali dealloying reactions occurring near room temperature, the general shape of the product relative to the initial alloy does not change significantly before and after the reaction. For example, if the initial alloy is in the form of angular particles, the conventional dealloying product generally remains in the form of nanoporous particles with the original angular shape. However, the shape of the solid material containing M or (and) Ti described in this application is completely different from that of the initial alloy, and its shape has undergone a significant change.

[0109] Furthermore, the reaction of the initial alloy with the alkaline solution at a certain temperature and concentration, and ensuring a reaction rate of not less than 2 μm / min, is very important for generating a solid material containing M or (with) Ti by nano-fragmentation and shape and composition reconstruction. In Comparative Example 1, under normal pressure, when the initial alloy powder containing the (NbTi)Al3 intermetallic compound reacts with a 10 mol / L NaOH solution at 25°C for 2 hours, the shape of the original initial alloy powder before and after the reaction remains roughly unchanged, and it is still the original crushed and angular powder particles, and its microstructure does not generate a large number of dispersed products such as nanoparticles, nanosheets or nanorods, but instead generates a nanoporous structure, and this nanoporous structure forms an appearance consistent with the shape of the original alloy powder through a three-dimensional network connection. The particle size is still the same size as the initial alloy powder, mainly on the order of several microns or tens of microns. Therefore, the reaction of the initial alloy with the alkaline solution at a lower temperature near room temperature is completely different from the reaction of the present invention at a higher temperature, such as the temperature range of T1>100°C, especially near the boiling point of the alkaline solution, and the product morphology is also completely different.

[0110] In the step three,

[0111] The time required for the completion of the hydrogen evolution and de-TiO reaction can be judged by whether the hydrogen evolution is complete. When no gas produced by the reaction is observed to be released by the naked eye, the hydrogen evolution and de-TiO reaction can be considered to be complete.

[0112] In addition to the alkali concentration and the temperature of the alkali solution, the reaction time required for complete removal of the T-type elements from the initial alloy through the hydrogen evolution-de-T reaction is also related to the shape of the initial alloy: smaller particles or thinner strips of the initial alloy powder shorten the time required for the hydrogen evolution-de-T reaction to complete; conversely, a smaller strip length increases the time required for the hydrogen evolution-de-T reaction to complete. The minimum reaction time t required for the hydrogen evolution-de-T reaction to complete can be calculated based on the average propagation velocity of the reaction interface and the size of the initial alloy. For example, if the initial alloy is in the form of a strip with a thickness of d and the average propagation velocity of the reaction interface is v, t = 0.5 d / v, considering that the reaction interface propagates from both the upper and lower surfaces of the strip. Similarly, if the initial alloy is in the form of particles with a diameter of d and the average propagation velocity of the reaction interface is v, t = 0.5 d / v.

[0113] In one embodiment, an initial alloy strip containing a (NbTi)Al3 intermetallic compound reacts with a 10 mol / L NaOH solution at a boiling point (boiling point of approximately 119°C), and the average rate of advancement of the reaction interface of the initial alloy strip is approximately 120 μm / min. That is, for an initial alloy strip with a thickness of 40 μm, the hydrogen evolution and de-Al reaction can be completed in 10 seconds; for an initial alloy strip with a thickness of 20 μm, the hydrogen evolution and de-Al reaction can be completed in 5 seconds; even for initial alloy coarse particles with a particle size of 5 mm, the hydrogen evolution and de-Al reaction can be completed in 21 minutes; considering the possible unevenness of the strip or powder particle size, the presence of thicker strips or larger particles, the actual reaction process can be slightly extended to ensure that the initial alloy reaction is completed and the next step can be carried out.

[0114] Further, the reaction time of hydrogen evolution and de-T is 10s to 59min; further, the reaction time of hydrogen evolution and de-T is 10s to 29min; further, the reaction time of hydrogen evolution and de-T is 10s to 9.9min; further, the reaction time of hydrogen evolution and de-T is 10s to 4.9min; further, the reaction time of hydrogen evolution and de-T is 10s to 1min; further, the reaction time of hydrogen evolution and de-T is 10s to 30s;

[0115] After the hydrogen evolution and de-Ti reaction is complete, extending the holding time of the reaction system at the original reaction temperature can still ensure that the product is a nanoscale product with particle dispersion. However, if the holding time is long enough, the product morphology may change to some extent. In other words, when the reaction time of the initial alloy and the alkaline solution far exceeds the minimum required hydrogen evolution and de-Ti reaction time t, such as several hours, a solid material containing M or (and) Ti can still be obtained, but its morphology may change to some extent.

[0116] When the initial alloy does not contain D-type sub-elements, the solid material containing M and Ti in the reaction system is collected to obtain a composite nano-metal oxide intermediate product containing M and Ti, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the manner in which the M-containing intermediate product and the Ti-containing intermediate product are combined includes in-situ intercalation; wherein the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can also be corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase. For example, when the M-containing intermediate product is an atom or an atomic cluster, it does not form an M-containing phase, and it exists in the Ti-containing intermediate product phase in the form of atoms or atomic clusters.

[0117] The phase can be a low-crystallinity phase or a high-crystallinity phase, but it must be a solid phase, such as a low-crystallinity Zr hydroxide phase and a high-crystallinity Ta oxide phase; the explanations related to the phase in all aspects of this application are consistent with this.

[0118] Furthermore, the process of collecting the solid matter containing M and Ti in the reaction system includes the separation, collection, cleaning and drying of the solid matter containing M and Ti;

[0119] Furthermore, the separation and collection process of the solid matter containing M and Ti includes any one of the following processes a) or b):

[0120] a) adding a large amount of cold solvent (such as water) to the reaction system to rapidly reduce the temperature of the solid substance containing M and Ti and the alkaline solution in the reaction system described in step 2, while simultaneously reducing the concentration of the alkaline solution in the reaction system, and then separating the diluted and cooled solid and liquid; it is obvious that the alkaline solution with reduced concentration and temperature is safer and also ensures the stability of the product morphology;

[0121] b) filtering and separating the hot alkaline solution and the solid matter containing M and Ti in the reaction system together through a filtering device (such as a filter mesh), thereby reducing the temperature of the solid matter containing M and Ti and achieving solid-liquid separation.

[0122] Furthermore, the cleaning process includes cleaning the solid matter containing M and Ti with a dilute acid solution to a pH of 4-8, wherein the cleaning function includes removing the residual alkali on the solid matter containing M and Ti and adjusting the cations of the nano titanate.

[0123] Preferably, the hydrogen ion concentration in the dilute acid solution is 0.001 mol / L to 0.1 mol / L;

[0124] Furthermore, when the solid material containing M and Ti is washed with dilute acid, the nano titanate in the solid material containing M and Ti is converted into nano titanic acid, that is, the nano titanate undergoes H+ The nano-titanic acid is replaced by titanate cations, but the morphology before and after the transformation remains basically unchanged. Furthermore, the shape of the nano-titanic acid is a two-dimensional film;

[0125] Furthermore, the composition of the composite nano-metal oxide intermediate containing M and Ti includes nano-oxide M and at least one of nano-titanate and nano-titanic acid;

[0126] Furthermore, the thickness of the nano titanate film is 0.25 nm to 7.5 nm; preferably, the thickness of the nano titanate film is 0.25 nm to 5 nm;

[0127] Preferably, the thickness of the nano titanate film is 0.25 nm to 2 nm;

[0128] Furthermore, the average area of ​​the nano titanate film is greater than 100nm 2 ;

[0129] Furthermore, the thickness of the nano titanate film is 0.25 nm to 7.5 nm; preferably, the thickness of the nano titanate film is 0.25 nm to 5 nm;

[0130] Preferably, the thickness of the nano titanate film is 0.25 nm to 2 nm;

[0131] Furthermore, the average area of ​​the nano titanate film is greater than 100nm 2 ;

[0132] Furthermore, the chemical composition of the nano titanate includes H, Ti, and O elements;

[0133] Furthermore, the chemical composition of the nano titanate includes H4TiO4;

[0134] Furthermore, in the composite nano-metal oxide intermediate product containing M and Ti, the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedding composite and physical adsorption composite;

[0135] Among them, the intermediate product containing M is mainly nano-oxidized M, and the intermediate product containing Ti is mainly nano-titanate; if it is pickled, the intermediate product containing Ti is mainly nano-titanic acid;

[0136] Furthermore, the method of compounding the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation compounding;

[0137] The in-situ intercalation refers to a formation mode of in-situ mosaic generation, that is, the Ti-containing intermediate product and the M-containing intermediate product are combined with each other by partial or complete endogenous intercalation, without relying on external addition or external mixing to make them distributed in each other; partial endogenous intercalation refers to the embedded component whose only part of the volume is embedded; it can be understood that when the Ti-containing intermediate product and the M-containing intermediate product are generated at the same time, there must be a situation where the Ti-containing intermediate product and the M-containing intermediate product are partially or completely in-situ embedded in each other;

[0138] This in-situ intercalation is accomplished during the simultaneous formation of Ti-containing intermediates and M-containing intermediates during the hydrogen evolution and de-Ti reaction. The term "in-situ" refers to the simultaneous generation of Ti-containing intermediates and M-containing intermediates.

[0139] This kind of embedding is different from the ordinary adsorption combination reported in other literatures that is dominated by van der Waals physical adsorption (nanoparticles adsorbed by van der Waals forces can move and fall off). It can ensure that the Ti-containing intermediate product and the M-containing intermediate product can be tightly embedded with each other (cannot move or fall off).

[0140] This in-situ intercalation method ensures that the M-containing intermediate product and the Ti-containing intermediate product are fully and evenly dispersed together during preparation, and prevents agglomeration of the M-containing intermediate product and the Ti-containing intermediate product. In comparison, if the M-containing intermediate product and the Ti-containing intermediate product are prepared separately and then mixed, it is difficult to achieve uniform dispersion. Therefore, in-situ intercalation cannot occur when the two components are prepared separately and then mixed.

[0141] Furthermore, regarding the understanding of “the M-containing intermediate product and the Ti-containing intermediate product may be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase”, for example: it means that when the M-containing intermediate product is small enough or small enough, it is not enough to form the phase structure of the M-containing intermediate product, then it does not exist in the form of a certain phase, but exists as M-containing atoms or atomic clusters. Although these M-containing atoms or atomic clusters are also combined with O in some way, their size is not enough to form an oxide phase. However, the composite nano-metal oxide intermediate product exists as a solid state, and it needs at least one phase as a matrix. Therefore, when the M-containing intermediate product exists as M-containing atoms or atomic clusters, the Ti-containing intermediate product must exist as a phase as a matrix; the phase mainly composed of the Ti-containing intermediate product as the matrix can be an amorphous phase, a crystalline phase, or a phase between the two; in another case, the M-containing intermediate product and the Ti-containing intermediate product are both corresponding phases to each other. This situation is easy to understand. Whichever intermediate product has a higher volume percentage is the phase that serves as the matrix.

[0142] This explanation also applies to the two cases when the initial alloy contains D-type sub-elements; and similar expressions are also given in the subsequent aspects 2 to 4, and their meanings will not be repeated in the aspects 2 to 4.

[0143] Furthermore, when the M-containing intermediate product and the Ti-containing intermediate product are in situ intercalated into a structure close to a single structure, such as an M / Ti-containing intermediate product, it also belongs to the case of in situ intercalation. In this case, the M-containing intermediate product and the Ti-containing intermediate product are both M / Ti-containing intermediate products with a certain structure, or even a single phase (in this case, the M-containing intermediate product and the Ti-containing intermediate product are the same M / Ti-containing intermediate product), and M or (with) Ti is in situ intercalated at the atomic scale, which is the most thorough composite. In this case, it can be considered that M is in situ intercalated in the matrix of the M / Ti-containing intermediate product in the form of atoms or atomic clusters; it can also be considered that Ti is in situ intercalated in the matrix of the M / Ti-containing intermediate product in the form of atoms or atomic clusters. Because the matrix of the M / Ti-containing intermediate product is amorphous or low-crystalline, it is impossible to determine whether the matrix is ​​a Ti-containing intermediate product or an M-containing intermediate product, and it can only be considered as an M / Ti-containing intermediate product.

[0144] Furthermore, the M-containing intermediate product is mainly nano-oxidized M;

[0145] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0146] Furthermore, the nano-oxide M includes at least one of low-crystallinity nano-oxide M, crystalline nano-oxide M, and hydrated nano-oxide M;

[0147] Furthermore, the low-crystallinity nano-oxide M includes amorphous nano-oxide M;

[0148] Since nano-oxygen hydride M can be regarded as a combination of nano-oxygen hydride M and H2O, nano-oxygen hydride M can be obtained by heating and dehydrating at a relatively low temperature, so the hydrated nano-oxygen hydride M is nano-oxygen hydride M;

[0149] Furthermore, the nano-oxidation M has particle dispersibility;

[0150] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0151] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 250 nm;

[0152] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 150 nm;

[0153] Furthermore, when the nano-oxidation M is in phase, its shape includes at least one of film, granule, plate, strip, tube and rod, and flocculent shape; the flocculent shape refers to a state in which extremely small microstructures without obvious edges and corners are agglomerated together.

[0154] Furthermore, although the nano-oxide M can be softly agglomerated together, they are not tightly connected together through a three-dimensional continuous rigid network structure and maintain the original initial alloy shape.

[0155] Furthermore, when the nano-oxide M is mainly in the form of a thin film, its thickness is 0.25nm to 30nm; and the average area of ​​the thin film is greater than 100nm. 2 ;

[0156] Furthermore, when the nano-oxidation M is mainly in granular form, its particle size range is 1.5 nm to 500 nm; preferably 1.5 nm to 200 nm; preferably 1.5 nm to 100 nm;

[0157] Furthermore, when the nano-oxidation M is mainly in the form of plates, its thickness ranges from 1.5nm to 100nm, preferably from 5nm to 30nm, and more preferably from 5nm to 20nm; and the average area of ​​the plates is greater than 100nm. 2 ;

[0158] Furthermore, when the nano-oxidation M is mainly in the form of flocs, the size of the floc microstructure is 1 nm to 15 nm;

[0159] Furthermore, when the nano-oxidation M is mainly in the shape of a tube or rod, it includes a tube or rod, and its diameter ranges from 2 nm to 200 nm; more preferably, from 2 nm to 50 nm; and its aspect ratio is greater than 2;

[0160] Note: The characteristics of the above-mentioned intermediate products of each sub-category are the characteristics and trends displayed when the molar percentage content of each sub-element in the corresponding A-category elements (Ti element, M-category sub-elements) is dominant; when the molar percentage content of a certain sub-element is not dominant, due to the mutual influence of the intermediate products corresponding to each sub-category element during the formation process, it may not show the evolution and formation trend when it is dominant.

[0161] When the initial alloy contains D-type sub-elements, and the D-type sub-elements mainly exist in the form of D-containing solid substances, all solid substances in the reaction system are collected to obtain a composite nano-metal oxide intermediate product composed of a D-containing intermediate product and an M-containing or (and) Ti-containing intermediate product, and its shape has at least one dimension in the three-dimensional direction not exceeding 500 nm; and the manner in which the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product are composited with each other includes in-situ embedded composite; wherein the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product is a phase.

[0162] From step 2, it can be seen that D-type daughter elements (Zr, Hf elements) have a tendency to generate D-containing solid substances after shape and composition reconstruction evolution under the conditions of alkali concentration and temperature corresponding to relatively low reaction rates, and this D-containing solid intermediate product includes at least one of solid nano-hydrogen D and solid DO2;

[0163] Furthermore, the shape of the D-containing solid intermediate product has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0164] Furthermore, the Ti-containing intermediate product is mainly nano-titanate; further, when the nano-titanate is in phase, its shape is mainly thin film with a thickness of 0.5nm-5nm, and the average area of ​​the film is greater than 100nm 2 ; Further, the cations in the nano titanate correspond to the cations in the alkaline solution of the reaction system; if the alkaline solution of the reaction system is NaOH, the titanate is sodium titanate;

[0165] Furthermore, the M-containing intermediate product is primarily nano-oxidized M; further, when the nano-oxidized M is in phase, its shape includes at least one of a film, granular, plate-like, strip-like, tubular, rod-like, and flocculent; the flocculent refers to a state in which extremely fine microstructures without distinct edges and corners are aggregated together. Furthermore, the shape of the nano-oxidized M has at least one dimension in the three-dimensional direction that does not exceed 500 nm;

[0166] Furthermore, the situations in which the intermediate products of each subcategory are compounded with each other include any one of the following three types: compounding of a D-containing intermediate product with an M-containing intermediate product; compounding of a D-containing intermediate product with a Ti-containing intermediate product; compounding of a D-containing intermediate product, an M-containing intermediate product, and a Ti-containing intermediate product; and the compounding method in any of the compound combinations includes in-situ embedded compounding;

[0167] Note: The characteristics of the above-mentioned intermediate products of each sub-category are the characteristics and trends displayed when the molar percentage content of each sub-element in the corresponding A-category elements (Ti element, M-category sub-elements, D-category sub-elements) is dominant; when the molar percentage content of a certain sub-element is not dominant, due to the mutual influence of the intermediate products corresponding to each sub-category element during the formation process, it may not show the evolution and formation trend when it is dominant.

[0168] When the initial alloy contains D-type sub-elements, and the D-type sub-elements are mainly dissolved in the alkaline solution, the liquid is added to the reaction system described in step 2 to reduce the concentration of the alkaline solution to a concentration C2 below which solid flocculent hydroxide D can be precipitated, and the precipitated solid flocculent hydroxide D is mixed with the solid material containing M or (with) Ti formed previously, and all solid materials are collected to obtain a composite nano-metal oxide intermediate product composed of nano-metal oxide D and a solid material containing M or (with) Ti, and its shape has at least one dimension in the three-dimensional direction not exceeding 500nm; wherein, when the composite nano-metal oxide intermediate product includes an M-containing intermediate product and a Ti-containing intermediate product, the manner in which the M-containing intermediate product and the Ti-containing intermediate product are composited includes in-situ embedded composite. Wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase.

[0169] Furthermore, since a small amount of D-type daughter elements are necessarily trapped in the solid matter containing M or (with) Ti when it is formed, a small amount of D-type daughter elements are also compounded in the solid matter containing M or (with) Ti that is formed earlier;

[0170] Furthermore, the liquid is a solvent corresponding to the alkaline solution;

[0171] Further, the liquid comprises water;

[0172] Further, the temperature of the liquid is room temperature; further, the temperature of the liquid is 0°C to 40°C;

[0173] Furthermore, the process of adding the liquid is accompanied by sufficient stirring of the alkaline solution of the reaction system to ensure that the precipitated solid flocculent D hydroxide grows as much as possible on the previously formed solid material containing M or (with) Ti by heterogeneous nucleation, thereby achieving uniform mixing of the D hydroxide and the solid material containing M or (with) Ti;

[0174] Furthermore, the concentration of C2 is determined based on the effect, and its value is the concentration that can cause solid flocculent (or colloidal) hydroxide D to precipitate;

[0175] Further, C2≤3mol / L; further, C2≤2mol / L;

[0176] When the reaction is carried out under normal pressure, since the reaction is carried out in an open container, the concentration of the alkaline solution in the reaction system in step 2 can be easily reduced to below C2 by adding a cold liquid (such as water) to the reaction system, and the temperature of the solid substance containing M or (and) Ti and the alkaline solution can be simultaneously reduced;

[0177] Furthermore, when the critical concentration C2 is approached, the precipitation rate of the solid flocculent D hydroxide is controlled by controlling the rate of concentration reduction; the slower the precipitation of D hydroxide, the easier it is to uniformly mix with the solid material containing M or (with) Ti;

[0178] Furthermore, when approaching the critical concentration C2, the rate of concentration decrease does not exceed 0.1 mol / L per second;

[0179] Furthermore, the dilution liquid contains a surfactant or a modifier;

[0180] The purpose of adding a surfactant or modifier to the liquid is to control the particle size of the precipitated nano-D oxide and inhibit its abnormal merging and growth; further, the surfactant or modifier includes at least one of PVP, CTAB, and CTAC;

[0181] Furthermore, the process of collecting all the solid substances includes the process of separating, collecting, washing and drying all the solid substances;

[0182] Furthermore, the cleaning process includes cleaning all solid substances with a dilute acid solution to a pH of 4-8. The cleaning function includes removing the residual alkali on all solid substances and adjusting the cations of the existing nano titanate to convert it into nano titanic acid.

[0183] Furthermore, when the Ti-containing solid material is washed with dilute acid, the nano titanate in the Ti-containing solid material is converted into nano titanic acid, that is, the nano titanate undergoes H + Replacement with titanate cations. Further, the nano titanate is in the shape of a two-dimensional film;

[0184] Furthermore, the M-containing intermediate product is mainly nano-M oxide, and the Ti-containing intermediate product is mainly nano-titanate; if it is pickled, the Ti-containing intermediate product is mainly nano-titanic acid;

[0185] Furthermore, the thickness of the nano titanate film is 0.25 nm to 7.5 nm; preferably, the thickness of the nano titanate film is 0.25 nm to 5 nm;

[0186] Preferably, the thickness of the nano titanate film is 0.25 nm to 2 nm;

[0187] Furthermore, the average area of ​​the nano titanate film is greater than 100nm 2 ;

[0188] Furthermore, the thickness of the nano titanate film is 0.25 nm to 7.5 nm; preferably, the thickness of the nano titanate film is 0.25 nm to 5 nm;

[0189] Preferably, the thickness of the nano titanate film is 0.25 nm to 2 nm;

[0190] Furthermore, the average area of ​​the nano titanate film is greater than 500nm 2 ;

[0191] Furthermore, the chemical composition of the nano titanate includes H, Ti, and O elements;

[0192] Furthermore, the chemical composition of the nano titanate includes H4TiO4;

[0193] Furthermore, when the composite nano-metal oxide intermediate product contains both M and Ti, the composition of the composite nano-metal oxide intermediate product containing M and Ti includes nano-oxide M and at least one of nano-titanate and nano-titanic acid;

[0194] Furthermore, when the composite nano-metal oxide intermediate product includes both an M-containing intermediate product and a Ti-containing intermediate product, the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation composite and physical adsorption composite;

[0195] Furthermore, when the composite nano-metal oxide intermediate product includes both an M-containing intermediate product and a Ti-containing intermediate product, the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedded composite.

[0196] Furthermore, the composite method of the nano-oxide M and the nano-titanate film includes in-situ embedding composite;

[0197] Furthermore, the composite method of the nano-oxide M and the nano-titanate film includes in-situ embedding composite;

[0198] Furthermore, the nano-oxide M includes at least one of low-crystallinity nano-oxide M, crystalline nano-oxide M, and hydrated nano-oxide M;

[0199] Furthermore, the low-crystallinity nano-oxide M includes amorphous nano-oxide M;

[0200] Since nano-oxygen hydride M can be regarded as a combination of nano-oxygen hydride M and H2O, nano-oxygen hydride M can be obtained by heating and dehydrating at a relatively low temperature, so the hydrated nano-oxygen hydride M is nano-oxygen hydride M;

[0201] Furthermore, the nano-oxidation M has particle dispersibility;

[0202] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0203] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 250 nm;

[0204] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 150 nm;

[0205] Furthermore, when the nano-oxidation M is in phase, its shape includes at least one of film, granule, plate, strip, tube and rod, and flocculent shape; the flocculent shape refers to a state in which extremely small microstructures without obvious edges and corners are agglomerated together.

[0206] Furthermore, although the nano-oxide M can be softly agglomerated together, they are not tightly connected together through a three-dimensional continuous rigid network structure and maintain the original initial alloy shape.

[0207] Furthermore, when the nano-oxide M is mainly in the form of a thin film, its thickness is 0.25nm to 30nm; and the average area of ​​the thin film is greater than 100nm. 2 ;

[0208] Furthermore, when the nano-oxidation M is mainly in granular form, its particle size range is 1.5 nm to 500 nm; preferably 1.5 nm to 200 nm; preferably 1.5 nm to 100 nm;

[0209] Furthermore, when the nano-oxidation M is mainly in the form of plates, its thickness ranges from 1.5nm to 100nm, preferably from 5nm to 30nm, and more preferably from 5nm to 20nm; and the average area of ​​the plates is greater than 100nm. 2 ;

[0210] Furthermore, when the nano-oxidation M is mainly in the form of flocs, the size of the floc microstructure is 1 nm to 15 nm;

[0211] Furthermore, when the nano-oxidation M is mainly in the shape of a tube or rod, it includes a tube or rod, and its diameter ranges from 2 nm to 200 nm; more preferably, from 2 nm to 50 nm; and its aspect ratio is greater than 2;

[0212] Furthermore, the nano-hydrogen hydride D is mainly nano-hydrogen hydride D with low crystallinity;

[0213] Furthermore, the nano-hydrogen hydride D has a flocculent structure, and the size of the flocculent microstructure ranges from 0.5 nm to 10 nm;

[0214] Note: The flocculent structure can also be called a gel-like structure or a gel-like flocculent structure;

[0215] The nano-sized D hydroxide is mainly compounded with the M-containing intermediate product or (with) the Ti-containing intermediate product by physical adsorption. It can be understood that because the precipitation of the nano-sized D hydroxide from the solution is later than the formation of the M-containing intermediate product or (with) the Ti-containing intermediate product, it is mainly compounded with the M-containing intermediate product or (with) the Ti-containing intermediate product by physical adsorption;

[0216] Furthermore, the nano-hydroxylated D is mainly compounded with the nano-oxidized M or (with) the nano-titanate film by physical adsorption;

[0217] Note: The characteristics of the above-mentioned intermediate products of each sub-category are the characteristics and trends displayed when the molar percentage content of each sub-element in the corresponding A-category elements (Ti element, M-category sub-elements, D-category sub-elements) is dominant; when the molar percentage content of a certain sub-element is not dominant, due to the mutual influence of the intermediate products corresponding to each sub-category element during the formation process, it may not show the evolution and formation trend when it is dominant.

[0218] Furthermore, the thermal stability and / or crystallization temperature of the composite nano-metal oxide intermediate product are higher than those of a corresponding single nano-metal oxide intermediate product prepared by a similar process. This increase in thermal stability and / or crystallization temperature is related to the special combination of different A-type sub-elements (elemental Ti, M-type sub-elements, and D-type sub-elements) in the composite nano-metal oxide intermediate product. This combination that improves thermal stability and / or crystallization temperature includes two types: one is initial in-situ intercalation, including in-situ intercalation at the atomic, atomic cluster, and phase scales; the other is the physical adsorption of nano-sized D hydroxide on other intermediate products with ultrafine and ultra-high dispersion, which induces a sintered intercalation during the subsequent heat treatment process. For example, when ultrafine flocculent hydroxide D precipitates, it is uniformly adsorbed on the previously precipitated nano-oxide M. Although the two are initially physically adsorbed and composited, due to the extremely uniform physical adsorption and extremely small scale, during the subsequent sintering process, heat treatment will induce a state of sintering embedded composite, resulting in smaller atoms or phases being encapsulated by the matrix phase after sintering and growth. The existence of this sintering embedded composite will affect the diffusion and rearrangement of atoms in the main matrix phase, thereby improving its thermal stability or (and) crystallization temperature during the sintering process. In the above two cases, the combination of heterogeneous components at an extremely small scale will affect the diffusion and rearrangement of matrix phase atoms, thereby improving the thermal stability or (and) crystallization temperature of the composite nano-metal oxide intermediate product. For example, the thermal stability or crystallization temperature of the composite nano-metal oxide intermediate product composed of element Ti and M-type sub-elements is higher than the thermal stability or crystallization temperature of the nano-metal oxide intermediate product composed of Ti alone or M-type elements alone.

[0219] Furthermore, the composite nano-metal oxide intermediate product contains at least two of the three sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide intermediate product, at least two of the three sub-elements of element Ti, M-type sub-elements, and D-type sub-elements are compounded with the corresponding oxide intermediate products of different types of elements at the atomic / atomic cluster scale or fine phase (abbreviation of fine phase) scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm;

[0220] Furthermore, in the composite nano-metal oxide intermediate product, at least two of the three types of sub-elements, namely Ti element, M type sub-elements and D type sub-elements, undergo in-situ embedding recombination of heterogeneous elements corresponding to the oxide intermediate product at the atomic / atomic cluster scale or fine phase scale.

[0221] Explanation: Generally speaking, when the initial alloy contains D-type daughter elements, and the D-type daughter elements are primarily soluble in the alkaline solution under the alkaline concentration and temperature conditions corresponding to high reaction rates, after the alkaline solution concentration decreases, the D-type daughter elements are mainly precipitated through hydrogen oxidation of D, and are primarily physically adsorbed and complexed with the previously precipitated M-containing intermediate product or (with) Ti-containing intermediate product. However, when D-type daughter elements are present in the initial alloy along with M or (with) Ti-type daughter elements, during the hydrogen evolution and de-Ti reaction, a small amount of D-containing intermediate product will inevitably be present in the previously precipitated M-containing intermediate product or (with) Ti-containing intermediate product through in situ intercalation and complexation. In this case, a small amount of D-type daughter elements also participate in the in situ intercalation and complexation during the initial precipitation process.

[0222] Furthermore, the method of compounding the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation compounding.

[0223] Furthermore, the average particle size of the intermediate product fine phase is less than 125 nm; further, the average particle size of the intermediate product fine phase is less than 50 nm;

[0224] Furthermore, the average particle size of the intermediate product fine phase is less than 25 nm; further, the average particle size of the intermediate product fine phase is less than 15 nm;

[0225] The atomic / atomic cluster scale is 0.25nm-2.5nm; wherein the atomic scale is 0.25nm-0.5nm, and the atomic cluster scale is 0.5nm-2.5nm; at the 0.25nm-2.5nm scale, it is not enough to form an intermediate product phase and can only be called an atom or an atomic cluster;

[0226] Preferably, in the composite nano-metal oxide intermediate product, the three elements, Ti element, M-type sub-elements and D-type sub-elements, are heterogeneous elements compounded at the atomic / atomic cluster scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm.

[0227] In the step 4,

[0228] Furthermore, the temperature of the heat treatment is 300°C to 2000°C; further, the temperature of the heat treatment is 400°C to 2000°C; further, the temperature of the heat treatment is 500°C to 2000°C;

[0229] Furthermore, the heat treatment time is 1 min to 24 h; further, the heat treatment time is 5 min to 24 h;

[0230] Furthermore, the heat treatment time is 30min to 24h;

[0231] It can be understood that as the heat treatment time is prolonged and the heat treatment temperature is increased, the crystallinity of the heat-treated product is continuously improved until it is completely crystallized.

[0232] Furthermore, in the composite nano-metal oxide with improved crystallinity, the three elements, namely, Ti, M-type sub-elements, and D-type sub-elements, are heterogeneously compounded at the atomic / atomic cluster scale or fine phase (abbreviated as a fine phase) scale; wherein the atomic / atomic cluster scale is 0.25 nm to 2.5 nm; and the average particle size of the fine phase is less than 250 nm.

[0233] Furthermore, the phase corresponding to the Ti element is partially crystallized or fully crystallized nano-TiO2; the phase corresponding to the M-type sub-element is partially crystallized or fully crystallized nano-oxide M, and the phase corresponding to the D-type sub-element is partially crystallized or fully crystallized nano-DO2;

[0234] Furthermore, the average particle size of the fine phase is less than 125 nm; further, the average particle size of the fine phase is less than 50 nm;

[0235] Furthermore, the average particle size of the fine phase is less than 25 nm; further, the average particle size of the fine phase is less than 15 nm;

[0236] The atomic / atomic cluster scale is 0.25nm-2.5nm; the atomic scale is 0.25nm-0.5nm, and the atomic cluster scale is 0.5nm-2.5nm; at the 0.25nm-2.5nm scale, it is not enough to form a phase and can only be called an atom or an atomic cluster;

[0237] Preferably, in the composite nano-metal oxide with improved crystallinity, the three elements, Ti, M-type sub-elements and D-type sub-elements, are heterogeneous elements compounded at the atomic / atomic cluster scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm.

[0238] Furthermore, the degree of crystallization of the phase corresponding to each sub-class element of Class A is related to the heat treatment temperature and time; according to the phase transformation law, when crystallization is incomplete, partially crystallized nano-TiO2 may contain titanic acid components; partially crystallized nano-oxide M may contain hydroxide M components; partially crystallized nano-DO2 may contain hydroxide D components.

[0239] Regarding the understanding that "in the composite nano-metal oxide with an improved degree of crystallization, the three types of elements, namely Ti element, M-type sub-elements, and D-type sub-elements, are heterogeneous elements combined at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; the average particle size of the fine phase is less than 250nm": that is, in the composite nano-metal oxide with an improved degree of crystallization, the components corresponding to the Ti element, M-type sub-elements, and D-type sub-elements are evaluated separately, and the particle size of the smaller components is either the atomic / atomic cluster level (0.25nm-2.5nm) or the fine phase level with an average particle size less than 250nm. For example: If the composite nano-metal oxide with an improved degree of crystallization is (TiCr)O2, which is formed by embedding a small amount of Cr in TiO2 as atoms or atomic clusters, then the Ti element and the Cr element (belonging to the M-type sub-element) are compounded at the atomic / atomic cluster scale. If the composite nano-metal oxide with an improved degree of crystallization is a ZrO2 phase that is a composite of an oxidized Cr phase, then the smaller phase of the two has an average particle size of less than 250nm and greater than 2.5nm at the fine phase level. That is, the expression of a fine phase is a situation where two or more phases appear, and the fine phase is the phase with a smaller average size. (This explanation applies to all aspects of this application, including aspects one to four thereof)

[0240] Furthermore, in the composite nano-metal oxide with improved crystallinity, when the three elements, Ti, M-type sub-elements, and D-type sub-elements, are combined as heterogeneous elements at the fine phase scale, the evolution law and product characteristics of the composite nano-metal oxide during heat treatment include the following characteristics:

[0241] When the initial alloy does not contain D-type sub-element, the composite nano-metal oxide is mainly a composite of nano-oxide M and nano-TiO2; and the composite method of the nano-oxide M and nano-TiO2 includes in-situ embedded composite;

[0242] When the initial alloy contains D-type sub-elements, the composite nano-metal oxide is mainly a composite of nano-DO2 and nano-oxide M or (with) nano-TiO2; and when the composite nano-metal oxide includes both nano-oxide M and nano-TiO2, the composite method of nano-oxide M and nano-TiO2 includes in-situ embedded composite.

[0243] Furthermore, the composite nano-metal oxide intermediate product is washed with dilute acid to a pH of 4-8 before heat treatment to remove residual alkali on the composite nano-metal oxide intermediate product; at the same time, when the composite nano-metal oxide intermediate product contains nano-titanate, the dilute acid washing can convert the nano-titanate into nano-titanic acid;

[0244] Furthermore, the composite of nano-DO2 and nano-oxidation M or (with) nano-TiO2 includes three situations: composite of nano-DO2 and nano-oxidation M; composite of nano-DO2 and nano-TiO2; composite of nano-DO2, nano-oxidation M, and nano-TiO2;

[0245] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0246] a) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano titanic acid in the composite nano metal oxide intermediate product gradually transforms into anatase TiO2 and then further transforms into rutile TiO2;

[0247] b) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano-hydroxylated D in the composite nano-metal oxide intermediate product gradually transforms into crystalline nano-DO2; wherein the crystalline DO2 includes at least one of the three conditions: ZrO2, HfO2, (Zr / Hf)O2;

[0248] c) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano-oxide M in the composite nano-metal oxide intermediate product gradually transforms into crystalline nano-oxide M;

[0249] The degree of transformation of the composite nano-metal oxide intermediate product in the three cases a)-c) above is related to the heat treatment time and temperature. Under certain heat treatment time and temperature conditions, products with any degree of crystallinity (crystallinity ranging from 0-100%) are within the scope of protection of this application; as long as the heat treatment time is long enough and the temperature is high enough, the composite nano-metal oxide intermediate product can completely undergo the transformations described in a)-c).

[0250] Note: The evolution trends and characteristics of the above-mentioned sub-categories of intermediate products during the heat treatment process are the characteristics and trends displayed when the molar percentage content of each sub-element in the corresponding A-category elements (Ti element, M-category sub-elements, D-category sub-elements) is dominant; when the molar percentage content of a certain type of sub-element is not dominant, due to the mutual influence between the evolution trends and characteristics of the intermediate products corresponding to each sub-category element during the heat treatment process, it may not show the evolution trends and characteristics when it is dominant.

[0251] Furthermore, when the composite nano-metal oxide intermediate product is originally in an in-situ embedded state, such as the in-situ embedded composite of nano-oxide M and nano-titanic acid, it is in the best uniform dispersion state before sintering, and the best uniform dispersion state can still be obtained after sintering;

[0252] Furthermore, the particle porosity and / or specific surface area of ​​the composite nano-metal oxide are higher than those of the corresponding single nano-metal oxide prepared by a similar process. The reason for this phenomenon is similar to the reason for the increased thermal stability and / or crystallization temperature of the composite nano-metal oxide intermediate, both of which are related to the initial in-situ intercalation or heat-treatment-induced sintering intercalation.

[0253] Compared with the particle porosity or specific surface area of ​​a single-component nano-metal oxide after heat treatment, when the particle porosity or specific surface area of ​​a composite nano-metal oxide with an increased degree of crystallization is increased, it is easier to obtain finer composite nano-metal oxide particles with an increased degree of crystallization through subsequent sand milling and ball milling. For example, when a single flocculent Zr hydroxide intermediate product is heat-treated to obtain crystalline ZrO2, the crystalline ZrO2 often sinters into extremely dense, blocky large particles with little shrinkage inside, making it difficult to crush them through subsequent sand milling and ball milling processes to obtain finer crystalline ZrO2. However, when the flocculent Zr hydroxide intermediate product is compounded with other components containing Ti and Nb, it not only increases its complete crystallization temperature, but also can obtain loose, high-specific-surface-area composite nano-metal oxide particles through heat treatment. The particles are mainly composed of crystalline ZrO2 and compounded with Ti and Nb components. Particles with this structure can be easily obtained through subsequent sand milling and ball milling to obtain finer composite nano-metal oxide particles, as shown in Example 1 and Comparative Example 2.

[0254] Furthermore, the nano titanate film has a tendency to evolve into flaky crystalline nano TiO2 after heat treatment;

[0255] Furthermore, the thickness of the crystalline nano-TiO2 sheet is 2nm to 20nm; the average area of ​​the crystalline nano-TiO2 sheet is greater than 100nm. 2 ;

[0256] Furthermore, the phase composition of the flaky crystalline nano-TiO2 in the composite nano-metal oxide includes at least one of brookite-type TiO2, nano-anatase-type nano-TiO2, and rutile-type nano-TiO2.

[0257] Furthermore, the flocculent nano-hydroxylated D has a tendency to evolve into granular crystalline nano-DO2 after heat treatment;

[0258] Furthermore, the particle size of the crystalline nano DO2 is 3nm to 500nm;

[0259] Furthermore, the nano-oxide M has a tendency to evolve into crystalline nano-oxide M after heat treatment; its shape includes at least one of a film, a granular shape, a plate shape, a strip shape, a tube rod shape, and a sintered agglomerate shape;

[0260] Furthermore, when the crystalline nano-oxide M is in the form of a thin film, its thickness is 2nm to 20nm; more preferably 3nm to 10nm; and the average area of ​​the thin film is greater than 200nm. 2 ;

[0261] Furthermore, when the crystalline nano-oxide M is in the form of particles, its particle size ranges from 3 nm to 500 nm;

[0262] Furthermore, when the crystalline nano-oxide M is in the form of a plate, its thickness is 6nm to 75nm, and the average area of ​​the plate is greater than 30nm. 2 ;

[0263] Furthermore, when the shape of the crystalline nano-oxide M is an elongated strip, its diameter ranges from 3 nm to 60 nm, and its aspect ratio is greater than 4;

[0264] Furthermore, when the shape of the crystalline nano-oxide M is a tube-rod shape, it includes a tube shape and a rod shape, and its diameter ranges from 3 nm to 200 nm, and its aspect ratio is greater than 2;

[0265] Furthermore, when the shape of the crystalline nano-oxide M is a sintered agglomerate, its particle size increases significantly due to sintering agglomeration, and the particle size ranges from 5 nm to 1 mm;

[0266] Note: The characteristics of the above-mentioned intermediate products of each sub-category are the characteristics and trends displayed when the molar percentage content of each sub-element in the corresponding A-category elements (Ti element, M-category sub-elements, D-category sub-elements) is dominant; when the molar percentage content of a certain sub-element is not dominant, due to the mutual influence of the intermediate products corresponding to each sub-category element during the formation process, it may not show the evolution and formation trend when it is dominant.

[0267] In particular, when the above-mentioned situation in which the sub-class elements are not dominant occurs, it just reflects the great advantages of the various steps of one aspect of the present application, as well as the subsequent other aspects of preparing composite nano-metal oxides: because the key to the performance of the composite nano-metal oxide lies in the performance of the final prepared product, when the sub-class elements produce great interactions in the process of hydrogen evolution and de-T and change their respective evolutionary formation trends when they are dominant, a uniform compound that cannot be obtained by other methods can be obtained; after this uniform compound state appears in step two of one aspect, it will continue to exist in the corresponding processes of step three and step four of one aspect; and this uniform compound is not only reflected in the physical mixing uniformity, but also in the chemical uniform compound, such as the generation of a new single-phase composite material, which can simultaneously include two to three sub-class elements and be uniformly distributed in the atomic state, such as single-phase nano-oxide Ti / M; this special compound can enable the finally obtained composite nano-metal oxide to obtain extremely excellent performance.

[0268] Furthermore, the composite nano-metal oxide with improved crystallinity contains at least two of the three sub-elements of Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide, at least two of the three sub-elements of Ti, M-type sub-elements, and D-type sub-elements are compounded with corresponding oxides of different types of elements at the atomic / atomic cluster scale or fine phase (abbreviation for fine phase) scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm;

[0269] Furthermore, in the composite nano-metal oxide, at least two of the three sub-elements, namely, Ti element, M-type sub-elements, and D-type sub-elements, undergo in-situ embedded recombination of heterogeneous elements with corresponding oxides at the atomic / atomic cluster scale or fine phase scale.

[0270] Explanation: The term "oxides corresponding to heterogeneous elements" refers to the presence of at least two of the three sub-elements: Ti, M-type sub-elements, and D-type sub-elements, in a composite nano-metal oxide. The resulting composite nano-metal oxide is considered to contain at least two of the following: nano-Ti oxide, nano-M oxide, and nano-D oxide. However, due to the chemical interactions that may occur when heterogeneous oxides are combined, nano-Ti oxide phases, nano-M oxide phases, or nano-D oxide phases may not actually be found in the composite nano-metal oxide. This is because one sub-element may dissolve in the oxide of another sub-element, or heterogeneous sub-elements may combine to form a new multi-component oxide. For example, if Ti is dissolved in Zr oxide, and the composite nano-metal oxide only exhibits the crystal structure of Zr oxide, this application still considers the composite nano-metal oxide to be a composite of Ti oxide and Zr oxide. Alternatively, if the composite nano-metal oxide is a single-phase Ti / Nb oxide, which exhibits neither the crystal structure of Ti oxide nor the crystal structure of Nb oxide but instead exhibits a new crystal structure, this application also considers the composite nano-metal oxide to be a composite of Ti oxide and Nb oxide. In both examples, Ti does not exist as a separate Ti oxide phase, so Ti is present at the atomic / atomic cluster scale as a composite of the corresponding oxides of the heterogeneous elements. When these situations occur, the unique composite nanometal oxide prepared in this application is achieved, which has positive significance. (This explanation applies to all aspects of this application, including similar situations in aspects 1 to 4.)

[0271] In another aspect, a method for preparing a composite nano-metal oxide intermediate product is provided, characterized in that it comprises the following steps:

[0272] Step 1: The process is completely consistent with the process described in step 1 of the first aspect. For details, please refer to the first aspect;

[0273] Step 2: The process is completely consistent with the process described in step 2 of the first aspect. For details, please refer to the first aspect;

[0274] Step 3: The process is completely consistent with the process described in step 3 of the first aspect. For details, please refer to the first aspect;

[0275] Steps 1 to 3 of the second aspect are completely consistent with steps 1 to 3 of the first aspect, including the detailed description of each sub-step. For details, please refer to steps 1 to 3 of the first aspect and will not be repeated here.

[0276] In a third aspect, a method for preparing a composite nano-metal oxide is characterized by comprising the following steps:

[0277] Step (1) provides an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A-type elements. x T y , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds;

[0278] Step (2), mixing the initial alloy with an alkaline solution having a temperature of T1 and a concentration of C1; wherein T s溶液 <T1≤T f溶液 , T f溶液 T is the boiling point of the alkaline solution involved in the reaction under normal pressure; s溶液 is the freezing point temperature of the alkaline solution participating in the reaction under normal pressure;

[0279] Step (3), mixing the solid substance obtained in step (2) with an alkaline solution having a concentration of C2, and then placing the mixture in a sealed container, and then treating it at a temperature T2 higher than normal pressure for a period of time, wherein T2>T f溶液 ;

[0280] Step (4), after cooling and depressurizing,

[0281] When the initial alloy does not contain D-type sub-elements, solid matter in the reaction system is collected to obtain a composite nano-metal oxide intermediate product containing M and Ti, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the manner in which the M-containing intermediate product and the Ti-containing intermediate product are composited includes in-situ embedded composite; wherein the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can be corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase;

[0282] When the initial alloy contains D-type sub-elements, a liquid is added to the reaction system after cooling and depressurizing, such that the concentration C3 of the diluted alkaline solution is < 3 mol / L. All solid substances are collected to obtain a composite nano-metal oxide intermediate product composed of D-containing solid substances and M- or (and) Ti-containing solid substances, and at least one dimension of its shape does not exceed 500 nm in the three-dimensional direction; wherein, C3 < C2; and when the composite nano-metal oxide intermediate product simultaneously includes an M-containing intermediate product and a Ti-containing intermediate product, the composite mode of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intergrowth composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase;

[0283] Step (5): subject the composite nano-metal oxide intermediate product described in step (4) to heat treatment to obtain a composite nano-metal oxide with improved crystallization degree; it contains at least two of the three types of sub-elements: element Ti, M-type sub-elements, and D-type sub-elements; and at least two of the three types of sub-elements of Ti element, M-type sub-elements, and D-type sub-elements are subjected to composite of corresponding oxides of different elements at the atomic / atomic cluster scale or the scale of fine phases.

[0284] The three aspects of step (1) are completely consistent with step one of one aspect, including the specific detailed description part. For details, see step one of one aspect described herein, and will not be elaborated here;

[0285] In the said step (2),

[0286] The alkaline solution contains at least one of the solutions of NaOH, KOH, LiOH, RbOH, CsOH, Ba(OH)2, Ca(OH)2, Sr(OH)2;

[0287] Furthermore, the solvent in the alkaline solution contains water; preferably, the solvent in the alkaline solution is water;

[0288] Furthermore, the concentration C1 of the alkali in the alkaline solution is 0.5 mol / L to 30 mol / L; further, the concentration C1 of the alkali in the alkaline solution is 1 mol / L to 30 mol / L; preferably, the concentration C1 of the alkali in the alkaline solution is 5 mol / L to 15 mol / L; due to the subsequent step (3) including a high-temperature and high-pressure reaction, the lower limit of the concentration C1 range of the alkaline solution can be as low as 0.5 mol / L. At this concentration, combined with high-temperature and high-pressure conditions, the corresponding target reaction can also be achieved.

[0289] Furthermore, the alkali in the alkali solution mixed with the initial alloy is in excess dosage, and the molar number of the alkali is more than 5 times the molar number of the initial alloy; further, the molar number of the alkali is more than 10 times the molar number of the initial alloy; further, the molar number of the alkali is more than 20 times the molar number of the initial alloy;

[0290] It can be understood that when the initial alloy is mixed with the alkaline solution with a temperature of T1 and a concentration of C1, a hydrogen evolution and dehydrogenation reaction will occur; and the higher the temperature of the alkaline solution and the higher the concentration of the alkaline solution, the faster the reaction rate.

[0291] When the initial alloy is mixed with an alkaline solution at a temperature of T1 and a concentration of C1, and the reaction interface during the hydrogen evolution and de-Ti reaction advances inward from the surface of the initial alloy at an average rate of not less than 2 μm / min, this is the situation described in step 2 of the first aspect. For details, see step 2 of the first aspect. In this case, during the reaction, the initial alloy undergoes nano-fragmentation through the hydrogen evolution and de-Ti reaction, and is reconstructed in shape and composition to generate a nano-scale M-containing solid product; therefore, step (2) includes the situation described in step 2 of the first aspect, that is, after the situation described in step 2 of the first aspect, the subsequent step (3) is still within the scope of protection of the third aspect of this application.

[0292] When the subsequent step (3) is present, whether or not nano-fragmentation occurs in step (2), or whether or not the hydrogen evolution and de-tantalum reaction is completed after the initial alloy is mixed with the alkaline solution in step (2), does not fundamentally affect the results of the reaction in step (3). Because the reaction in step (3) is carried out for a longer time, at a higher temperature, and especially at a higher pressure, regardless of the values ​​of the temperature T1 and the concentration C1 in step (2), or regardless of the intermediate product obtained in step (2), the characteristics of the reactants or intermediate products will be covered by the subsequent process, and a new reaction equilibrium will be reached in step (3), and the final product under the equilibrium conditions will be obtained at the same time.

[0293] Therefore, in step (2), when the initial alloy is mixed with an alkaline solution at a temperature of T1 and a concentration of C1, and the reaction interface advances inward from the surface of the initial alloy at an average rate of less than 2 μm / min during the hydrogen evolution and dehydrogenation reaction, it still falls within the scope of the three aspects of protection of this application.

[0294] Furthermore, T s溶液 ≤T1<60℃; further, T s溶液 ≤T1<80℃;

[0295] In the step (3),

[0296] The process of mixing the solid substance obtained in step (2) with an alkali solution having a concentration of C2 and then placing the mixture in a sealed container includes at least one of the following two specific operation processes:

[0297] a) Directly place the mixture of the solid substance obtained in step (2) and the alkali solution having a concentration of C1 in a sealed container; at this time, there is no need to increase or decrease the alkali solution, and C2≈C1. The slight difference in the concentrations of C2 and C1 comes from the small amount of alkali consumed due to the hydrogen evolution and de-T reaction in step (2);

[0298] b) First separate the solid substance obtained in step (2) from the alkali solution having a concentration of C1, and then mix it with the alkali solution having a concentration of C2 and place it in a sealed container; at this time, the concentration and type of the alkali solution having a concentration of C2 can be the same as those of the alkali solution having a concentration of C1, or can be different from the concentration and type of the alkali solution having a concentration of C1;

[0299] Further, the range of C2 is 0.5 mol / L to 30 mol / L; further, the range of C2 is 1 mol / L to 30 mol / L; further, the range of C2 is 5 mol / L to 30 mol / L;

[0300] Further, the pressure is higher than normal pressure but lower than 100 MPa; further, the pressure is higher than normal pressure but lower than 20 MPa;

[0301] Further, T f溶液 <T2≤500 °C; further, T f溶液 <T2≤300 °C;

[0302] Further, the treatment time at a temperature of T2 higher than normal pressure is 1 min to 48 h; further, the treatment time at a temperature of T2 higher than normal pressure is 1 min to 12 h; further, the treatment time at a temperature of T2 higher than normal pressure is 1 min to 2 h; further, the treatment time at a temperature of T2 higher than normal pressure is 1 min to 30 min; further, the treatment time at a temperature of T2 higher than normal pressure is 1 min to 10 min;

[0303] Further, the treatment time at a temperature of T2 higher than normal pressure is related to the concentration of C2, the magnitude of the pressure, and the magnitude of T2; the higher the concentration of C2, the greater the pressure, and the higher T2, the shorter the required reaction time. When the concentration of C2 takes the lower value of its range, such as 0.5 mol / L, and the solvent is water, it is the common condition for hydrothermal reaction, and the low-concentration alkali is the mineralizing agent under hydrothermal reaction conditions;

[0304] Furthermore, when the range of C2 is 7 mol / L to 30 mol / L, the treatment time at the temperature T2 higher than normal pressure is 1 min to 2 h;

[0305] Furthermore, when the range of C2 is 7 mol / L to 30 mol / L, the treatment time at the temperature T2 higher than normal pressure is 1 min to 30 min;

[0306] Furthermore, when the range of C2 is 0.5 mol / L to 7 mol / L, the treatment time at the temperature T2 higher than normal pressure is 30 min to 48 h;

[0307] In the step (4),

[0308] Furthermore, the cooling is to cool down to below 100°C; further, the cooling is to cool down to below 50°C;

[0309] When the initial alloy does not contain D-type sub-elements, solid matter in the reaction system is collected to obtain a composite nano-metal oxide intermediate product containing M and Ti, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the manner in which the M-containing intermediate product and the Ti-containing intermediate product are composited includes in-situ embedded composite; wherein the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can be corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase;

[0310] Furthermore, when the Ti-containing intermediate product is a phase, the shape of the Ti-containing intermediate product includes at least one of a film, a tube, a rod, and a fiber;

[0311] Furthermore, when the Ti-containing intermediate product is a phase, the shape of the Ti-containing intermediate product includes at least one of a tube, a rod, and a fiber;

[0312] Furthermore, the process of collecting the solid matter in the reaction system includes the separation, collection, cleaning and drying of the composite nano-metal oxide intermediate containing M and Ti;

[0313] Furthermore, the cleaning process includes cleaning the composite nano-metal oxide intermediate product containing M and Ti with a dilute acid solution to a pH of 4-8. The cleaning function includes removing the residual alkali on the composite nano-metal oxide intermediate product containing M and Ti and adjusting the cations of the nano-titanate.

[0314] Preferably, the hydrogen ion concentration in the dilute acid solution is 0.001 mol / L to 0.1 mol / L;

[0315] Furthermore, the M-containing intermediate product is mainly nano-oxidized M;

[0316] Furthermore, the Ti-containing intermediate product is mainly nano-titanate;

[0317] Furthermore, when the composite nano-metal oxide intermediate product containing M and Ti is washed with dilute acid, the nano-titanate in the composite nano-metal oxide intermediate product containing M and Ti is converted into nano-titanic acid, that is, the nano-titanate undergoes H + The nano titanate is shaped like at least one of a film, a tube, a rod, and a fiber.

[0318] Furthermore, after pickling, the Ti-containing intermediate product is mainly nano-titanic acid;

[0319] Furthermore, the composition of the composite nano-metal oxide intermediate containing M and Ti includes nano-oxide M and at least one of nano-titanate and nano-titanic acid;

[0320] Furthermore, the shape of the nano titanate includes at least one of a tube, a rod, and a fiber; and the cross-sectional diameter thereof is 2 nm to 20 nm;

[0321] Furthermore, the shape of the nano titanate includes at least one of a tube, a rod, and a fiber; and the cross-sectional diameter thereof is 2nm-20nm;

[0322] Furthermore, the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation composite; the characteristics and explanation of the in-situ intercalation composite have been described in the first aspect, see the first aspect; the only difference here from the first aspect is that the Ti-containing intermediate product in the first aspect is mainly in the form of a film, while the shape of the Ti-containing intermediate product here includes at least one of a film, a tube, a rod, and a fiber;

[0323] Furthermore, the method of compounding the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation compounding;

[0324] Furthermore, the M-containing intermediate product and the Ti-containing intermediate product may be combined in situ by in-situ intercalation. This in-situ intercalation also occurs when the M-containing intermediate product and the Ti-containing intermediate product combine to form a nearly single structure, such as an M / Ti-containing intermediate product. In this case, both the M-containing intermediate product and the Ti-containing intermediate product are M / Ti-containing intermediate products with a certain structure, and the M and Ti are in situ intercalated at the atomic scale, representing the most thorough combination.

[0325] Furthermore, the composite method of the nano-oxide M and the nano-titanate includes in-situ embedded composite;

[0326] Furthermore, the composite method of the nano-oxide M and nano-titanic acid includes in-situ embedding composite;

[0327] Furthermore, the nano-oxide M includes at least one of low-crystallinity nano-oxide M, crystalline nano-oxide M, and hydrated nano-oxide M;

[0328] Furthermore, the low-crystallinity nano-oxide M includes amorphous nano-oxide M;

[0329] Since nano-oxygen hydride M can be regarded as a combination of nano-oxygen hydride M and H2O, nano-oxygen hydride M can be obtained by heating and dehydrating at a relatively low temperature, so the hydrated nano-oxygen hydride M is nano-oxygen hydride M;

[0330] Furthermore, the nano-oxidation M has particle dispersibility;

[0331] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0332] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0333] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 250 nm;

[0334] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 150 nm;

[0335] Furthermore, the shape of the nano-oxide M includes at least one of a film, a particle, a plate, a strip, a tube, a rod, and a flocculent shape; the flocculent shape refers to a state in which extremely small microstructures without obvious edges and corners are agglomerated together.

[0336] Furthermore, although the nano-oxide M can be softly agglomerated together, they are not tightly connected together through a three-dimensional continuous rigid network structure and maintain the original initial alloy shape.

[0337] Furthermore, when the nano-oxide M is mainly in the form of a thin film, its thickness is 0.25nm to 30nm; and the average area of ​​the thin film is greater than 100nm. 2 ;

[0338] Furthermore, when the nano-oxidation M is mainly in granular form, its particle size range is 1.5 nm to 500 nm; preferably 1.5 nm to 200 nm; preferably 1.5 nm to 100 nm;

[0339] Further, when the nano-oxide M is mainly in a plate-like shape, its thickness ranges from 1.5 nm to 100 nm, preferably from 5 nm to 30 nm, and more preferably from 5 nm to 20 nm; and the average area of the plate is greater than 100 nm 2 ;

[0340] Further, when the nano-oxide M is mainly in a flocculent shape, the size of its flocculent microstructure is from 1 nm to 15 nm;

[0341] Further, when the nano-oxide M is mainly in a tubular or rod-like shape, it includes tubular and rod-like shapes, and its diameter ranges from 2 nm to 200 nm; further preferably from 2 nm to 50 nm; and its aspect ratio is greater than 2;

[0342] When the initial alloy contains D-type sub-elements, a liquid is added to the reaction system after cooling and depressurization, such that the concentration C3 of the diluted alkaline solution < 3 mol / L. All solid substances are collected to obtain a composite nano-metal oxide intermediate product composed of solid substances containing D and solid substances containing M or (and) Ti, and the shape of which has at least one dimension not exceeding 500 nm in the three-dimensional direction; wherein, C3 < C2, and when the composite nano-metal oxide intermediate product simultaneously includes an intermediate product containing M and an intermediate product containing Ti, the composite manner of the intermediate product containing M and the intermediate product containing Ti includes in-situ intergrowth composite; wherein, the intermediate product containing M and the intermediate product containing Ti can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the intermediate product containing M and the intermediate product containing Ti is a phase.

[0343] Further, since a small amount of D-type sub-elements are necessarily confined therein when the solid substances containing M or (and) Ti are formed, there is also a composite involving a small amount of D-type sub-elements in the solid substances containing M or (and) Ti formed first.

[0344] Further, when the intermediate product containing Ti is a phase, the shape of the intermediate product containing Ti includes at least one of a thin film shape, a tubular shape, a rod shape, and a fibrous shape;

[0345] Further, the liquid contains water;

[0346] Furthermore, the temperature of the liquid is at room temperature; furthermore, the temperature of the liquid is from 0 °C to 40 °C;

[0347] Further, C3 < 3 mol / L; further, C3 < 2 mol / L,

[0348] That is, the concentration of the alkaline solution is reduced to below C3. When the D-type sub-element has been dissolved in the C2 alkaline solution before dilution, by adjusting the concentration value of C3, the D-type element can be precipitated in the diluted alkaline solution in the form of flocculent D hydroxide; when the D-type element has not dissolved and is already in a solid state before dilution, the precipitation of D hydroxide will not occur at this time.

[0349] Furthermore, before dilution, C2 is in a high value region of its range, such as 7-30 mol / L, and the D-type element dissolves in the alkaline solution; after dilution, the D-type element precipitates in the diluted alkaline solution in the form of flocculent D hydroxide; further, the nano D hydroxide is mainly low-crystallization nano D hydroxide; further, the nano D hydroxide has a flocculent structure, and the size of its flocculent microstructure ranges from 0.5 nm to 10 nm;

[0350] Furthermore, before dilution, C2 is in the lower value area of ​​its range, such as 0.5-3 mol / L. Before dilution, the D-type elements have been converted into solid nano-DO2 through high temperature and high pressure hydrothermal reaction, wherein the lower concentration of alkali acts as a mineralizer; after dilution, solid nano-DO2 is still retained;

[0351] Furthermore, the particle size of the nano DO2 is 3nm to 500nm;

[0352] Furthermore, before dilution, C2 is in the middle of its range, such as 3-7 mol / L, and the evolution law of D-type elements is between the above two; that is, after dilution, the D-containing products obtained include solid nano-DO2 and flocculent D hydroxide;

[0353] Furthermore, the dilution liquid contains a surfactant or a modifier;

[0354] The purpose of adding a surfactant or modifier to the liquid is to control the particle size of the precipitated nano-D oxide and inhibit its abnormal merging and growth; further, the surfactant or modifier includes at least one of PVP, CTAB, and CTAC;

[0355] Furthermore, the process of collecting all the solid substances includes the process of separating, collecting, washing and drying all the solid substances;

[0356] Furthermore, the cleaning process includes cleaning all solid substances with a dilute acid solution to a pH of 4-8. The cleaning function includes removing the residual alkali on all solid substances and adjusting the cations of the existing nano titanate.

[0357] Furthermore, when the Ti-containing solid material is washed with dilute acid, the nano titanate in the Ti-containing solid material is converted into nano titanic acid, that is, the nano titanate undergoes H +Replacement with titanate cations.

[0358] Preferably, the hydrogen ion concentration in the dilute acid solution is 0.0001 mol / L to 0.09 mol / L;

[0359] Furthermore, the M-containing intermediate product is mainly nano-oxidized M;

[0360] Furthermore, the Ti-containing intermediate product is mainly nano-titanate;

[0361] Furthermore, when the composite nano-metal oxide intermediate product containing M and Ti is washed with dilute acid, the nano-titanate in the composite nano-metal oxide intermediate product containing M and Ti is converted into nano-titanic acid, that is, the nano-titanate undergoes H + Replacement with titanate cations. Further, the shape of the nano titanate includes at least one of a film, a tube, a rod, and a fiber; wherein, the higher the C2 concentration, the easier it is for the nano titanate to form a tube, a rod, or a fiber;

[0362] Furthermore, after pickling, the Ti-containing intermediate product is mainly nano-titanic acid;

[0363] Furthermore, the composition of the composite nano-metal oxide intermediate containing M and Ti includes nano-oxide M and at least one of nano-titanate and nano-titanic acid;

[0364] Furthermore, the shape of the nano titanate includes at least one of a film, a tube, a rod, and a fiber; the film thickness is 0.5nm-10nm; the cross-sectional diameter of the tube, rod, or fiber is 2nm-20nm;

[0365] Furthermore, the shape of the nano titanate includes at least one of a film, a tube, a rod, and a fiber; the film thickness is 0.5nm-10nm; the cross-sectional diameter of the tube, rod, or fiber is 2nm-20nm;

[0366] Furthermore, the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intercalation composite; the characteristics and explanation of the in-situ intercalation composite have been described in the first aspect, see the first aspect; the only difference here from the first aspect is that the Ti-containing intermediate product in the first aspect is mainly in the form of a film, while the shape of the Ti-containing intermediate product here includes at least one of a film, a tube, a rod, and a fiber;

[0367] Furthermore, the composite method of the nano-oxide M and the nano-titanate includes in-situ embedded composite;

[0368] Furthermore, the composite method of the nano-oxide M and nano-titanic acid includes in-situ embedding composite;

[0369] Furthermore, the nano-oxide M includes at least one of low-crystallinity nano-oxide M, crystalline nano-oxide M, and hydrated nano-oxide M;

[0370] Furthermore, the low-crystallinity nano-oxide M includes amorphous nano-oxide M;

[0371] Since nano-oxygen hydride M can be regarded as a combination of nano-oxygen hydride M and H2O, nano-oxygen hydride M can be obtained by heating and dehydrating at a relatively low temperature, so the hydrated nano-oxygen hydride M is nano-oxygen hydride M;

[0372] Furthermore, the nano-oxidation M has particle dispersibility;

[0373] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0374] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction not exceeding 500 nm;

[0375] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 250 nm;

[0376] Furthermore, the shape of the nano-oxide M has at least one dimension in the three-dimensional direction that does not exceed 150 nm;

[0377] Furthermore, the shape of the nano-oxide M includes at least one of a film, a particle, a plate, a strip, a tube, a rod, and a flocculent shape; the flocculent shape refers to a state in which extremely small microstructures without obvious edges and corners are agglomerated together.

[0378] Furthermore, although the nano-oxide M can be softly agglomerated together, they are not tightly connected together through a three-dimensional continuous rigid network structure and maintain the original initial alloy shape.

[0379] Furthermore, when the nano-oxide M is mainly in the form of a thin film, its thickness is 0.25nm to 30nm; and the average area of ​​the thin film is greater than 100nm. 2 ;

[0380] Furthermore, when the nano-oxidation M is mainly in granular form, its particle size range is 1.5 nm to 500 nm; preferably 1.5 nm to 200 nm; preferably 1.5 nm to 100 nm;

[0381] Furthermore, when the nano-oxidation M is mainly in the form of plates, its thickness ranges from 1.5nm to 100nm, preferably from 5nm to 30nm, and more preferably from 5nm to 20nm; and the average area of ​​the plates is greater than 100nm.2 ;

[0382] Furthermore, when the nano-oxidation M is mainly in the form of flocs, the size of the floc microstructure is 1 nm to 15 nm;

[0383] Furthermore, when the nano-oxidation M is mainly in the shape of a tube or rod, it includes a tube or rod, and its diameter ranges from 2 nm to 200 nm; more preferably, from 2 nm to 50 nm; and its aspect ratio is greater than 2;

[0384] It should be noted that the morphological characteristics of the nano-oxide M, nano-titanate, nano-hydroxylated D, or DO2 involved in step (4) are all characteristics displayed when the volume of the corresponding component is dominant. When the volume of a certain intermediate product component is not dominant, due to the mutual influence between the various intermediate product components, it may not display the morphological characteristics when its volume is dominant. For example, when the intermediate product component nano-titanate is combined with nano-oxide Nb and the volume percentage exceeds 50%, it can exhibit a tubular state. However, when the volume percentage is less than 20%, it may not display a tubular state due to the influence of nano-oxide Nb (such as being embedded in it).

[0385] Furthermore, the thermal stability or (and) crystallization temperature of the composite nano-metal oxide intermediate product is higher than the thermal stability or (and) crystallization temperature of the corresponding single nano-metal oxide intermediate product prepared by a similar process. This improvement in thermal stability or (and) crystallization temperature is related to the special combination of different A-type sub-elements (element Ti, M-type sub-elements, and D-type sub-elements) in the composite nano-metal oxide intermediate product. This combination that improves thermal stability or (and) crystallization temperature includes two categories: one is the initial in-situ intercalation combination, including in-situ intercalation at the atomic, atomic cluster, and phase scales; the other is the physical adsorption combination involving ultrafine, ultra-highly dispersed flocculent hydroxide D, which will induce sintering intercalation during the later heat treatment process.

[0386] Furthermore, the composite nano-metal oxide intermediate product contains at least two of the three sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide intermediate product, at least two of the three sub-elements of element Ti, M-type sub-elements, and D-type sub-elements are compounded with the corresponding oxide intermediate products of different types of elements at the atomic / atomic cluster scale or fine phase (abbreviation of fine phase) scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm;

[0387] Furthermore, in the composite nano-metal oxide intermediate product, at least two of the three types of sub-elements, namely Ti element, M type sub-elements and D type sub-elements, undergo in-situ embedding recombination of heterogeneous elements corresponding to the oxide intermediate product at the atomic / atomic cluster scale or fine phase scale.

[0388] In the step (5),

[0389] Furthermore, the temperature of the heat treatment is 300°C to 2000°C; further, the temperature of the heat treatment is 400°C to 2000°C; further, the temperature of the heat treatment is 500°C to 2000°C;

[0390] Furthermore, the heat treatment time is 1 min to 24 h; further, the heat treatment time is 5 min to 24 h;

[0391] Furthermore, the heat treatment time is 30min to 24h;

[0392] It can be understood that as the heat treatment time is prolonged and the heat treatment temperature is increased, the crystallinity of the heat-treated product is continuously improved until it is completely crystallized.

[0393] Furthermore, in the composite nano-metal oxide with improved crystallinity, the three elements, namely, Ti, M-type sub-elements, and D-type sub-elements, are heterogeneously compounded at the atomic / atomic cluster scale or fine phase (abbreviated as a fine phase) scale; wherein the atomic / atomic cluster scale is 0.25 nm to 2.5 nm; and the average particle size of the fine phase is less than 250 nm.

[0394] Furthermore, the phase corresponding to the Ti element is partially crystallized or fully crystallized nano-TiO2; the phase corresponding to the M-type sub-element is partially crystallized or fully crystallized nano-oxide M, and the phase corresponding to the D-type sub-element is partially crystallized or fully crystallized nano-DO2;

[0395] Furthermore, the average particle size of the fine phase is less than 125 nm; further, the average particle size of the fine phase is less than 50 nm;

[0396] Furthermore, the average particle size of the fine phase is less than 25 nm; further, the average particle size of the fine phase is less than 15 nm;

[0397] The atomic / atomic cluster scale is 0.25nm-2.5nm; the atomic scale is 0.25nm-0.5nm, and the atomic cluster scale is 0.5nm-2.5nm; at the 0.25nm-2.5nm scale, it is not enough to form a phase and can only be called an atom or an atomic cluster;

[0398] Preferably, in the composite nano-metal oxide with improved crystallinity, the three elements, Ti, M-type sub-elements and D-type sub-elements, are heterogeneous elements compounded at the atomic / atomic cluster scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm.

[0399] Furthermore, the degree of crystallization of the phase corresponding to each sub-class element of Class A is related to the heat treatment temperature and time; according to the phase transformation law, partially crystallized nano-TiO2 may contain titanic acid components; partially crystallized nano-oxide M may contain hydroxide M components; partially crystallized nano-DO2 may contain hydroxide D components.

[0400] Regarding the understanding that "in the composite nano-metal oxide with an improved degree of crystallization, the three types of elements, namely Ti element, M-type sub-elements, and D-type sub-elements, are heterogeneous elements combined at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; the average particle size of the fine phase is less than 250nm": that is, in the composite nano-metal oxide with an improved degree of crystallization, the components corresponding to the Ti element, M-type sub-elements, and D-type sub-elements are evaluated separately, and the particle size of the smaller components is either the atomic / atomic cluster level (0.25nm-2.5nm) or the fine phase level with an average particle size less than 250nm. For example: if the composite nano-metal oxide with an improved degree of crystallization is (TiCr)O2, which is formed by embedding a small amount of Cr in TiO2 in the form of atoms or atomic clusters, then the Ti element and the Cr element (belonging to the M-type sub-elements) are compounded as heterogeneous elements at the atomic / atomic cluster scale; if the composite nano-metal oxide with an improved degree of crystallization is a ZrO2 phase that is a composite of an oxidized Cr phase, then the smaller-scale phase of the two has an average particle size of less than 250nm and greater than 2.5nm, which is a fine phase level, that is, the fine phase is described as a situation where two or more phases appear, and the fine phase is the phase with a smaller average scale.

[0401] Furthermore, in the composite nano-metal oxide with improved crystallinity, when the three elements, Ti, M-type sub-elements, and D-type sub-elements, are combined as heterogeneous elements at the fine phase scale, the evolution law and product characteristics of the composite nano-metal oxide during heat treatment include the following characteristics:

[0402] When the initial alloy does not contain D-type sub-element, the composite nano-metal oxide is mainly a composite of nano-oxide M and nano-TiO2; and the composite method of the nano-oxide M and nano-TiO2 includes in-situ embedded composite;

[0403] When the initial alloy contains D-type sub-elements, the composite nano-metal oxide is mainly a composite of nano-DO2 and nano-oxide M or (with) nano-TiO2; and when the composite nano-metal oxide includes both nano-oxide M and nano-TiO2, the composite method of nano-oxide M and nano-TiO2 includes in-situ embedded composite.

[0404] Furthermore, the composite nano-metal oxide intermediate product is washed with dilute acid to a pH of 4-8 before heat treatment to remove residual alkali on the composite nano-metal oxide intermediate product; at the same time, when the composite nano-metal oxide intermediate product contains nano-titanate, the dilute acid washing can convert the nano-titanate into nano-titanic acid;

[0405] Furthermore, the composite of nano-DO2 and nano-oxidation M or (with) nano-TiO2 includes three situations: composite of nano-DO2 and nano-oxidation M; composite of nano-DO2 and nano-TiO2; composite of nano-DO2, nano-oxidation M, and nano-TiO2;

[0406] a) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano titanic acid in the composite nano metal oxide intermediate product gradually transforms into anatase TiO2 and then further transforms into rutile TiO2;

[0407] b) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano-hydroxylated D in the composite nano-metal oxide intermediate product gradually transforms into crystalline nano-DO2; wherein the crystalline DO2 includes at least one of the three conditions: ZrO2, HfO2, (Zr / Hf)O2;

[0408] c) Further, during the heat treatment process, as the heat treatment temperature increases and the heat treatment time increases, the nano-oxide M in the composite nano-metal oxide intermediate product gradually transforms into crystalline nano-oxide M;

[0409] It is understood that as the heat treatment time increases and the heat treatment temperature rises, the crystallinity of the resulting heat-treated product continues to increase until it is completely crystallized. Therefore, the degree of transformation of the composite nano-metal oxide intermediate product in the above three situations a)-c) is related to the heat treatment time and temperature. Under certain heat treatment time and temperature conditions, products with any degree of crystallinity (crystallinity of 0-100%) are within the scope of protection of this application; as long as the heat treatment time is long enough and the temperature is high enough, the composite nano-metal oxide intermediate product can completely undergo the above-mentioned transformation a)-c).

[0410] Therefore, when the composite nano-metal oxide intermediate product is originally in an in-situ embedded state, such as the in-situ embedded composite of nano-oxide M and nano-titanic acid, it is in the best uniform dispersion state before sintering, and the best uniform dispersion state can still be obtained after sintering;

[0411] Furthermore, the particle porosity or (with) specific surface area of ​​the composite nano-metal oxide is higher than the particle porosity or (with) specific surface area of ​​the corresponding single nano-metal oxide prepared by a similar process. The reason for this phenomenon is similar to the reason for the increase in thermal stability or (with) crystallization temperature of the above-mentioned composite nano-metal oxide intermediate product, both of which are related to the initial in-situ embedded composite or sintered embedded composite induced by heat treatment. For example, after heat treatment, the particle porosity or (with) specific surface area of ​​the composite nano-metal oxide composed of Zr and Ti elements is higher than the particle porosity or (with) specific surface area of ​​the nano-metal oxide composed solely of Zr or solely of Ti elements.

[0412] When the particle porosity or specific surface area of ​​the composite nano-metal oxide with improved crystallinity is increased, it is easier to obtain finer composite nano-metal oxide particles with improved crystallinity through subsequent sand milling and ball milling.

[0413] Furthermore, the phase composition of the flaky crystalline nano-TiO2 in the composite nano-metal oxide includes at least one of brookite-type TiO2, nano-anatase-type nano-TiO2, and rutile-type nano-TiO2; and its diameter is 3nm to 500nm;

[0414] Furthermore, the particle size of the crystalline nano DO2 is 3nm to 500nm;

[0415] Furthermore, the nano-oxide M has a tendency to evolve into crystalline nano-oxide M after heat treatment; its shape includes at least one of a film, a granular shape, a plate shape, a strip shape, a tube rod shape, and a sintered agglomerate shape;

[0416] Furthermore, different valence states of M in the nano-oxidized M correspond to different nano-oxidized M; for example, the oxidized Mn may be MnO or MnO2;

[0417] Furthermore, when the crystalline nano-oxide M is in the form of a thin film, its thickness is 2nm to 20nm; more preferably 3nm to 10nm; and the average area of ​​the thin film is greater than 200nm. 2 ;

[0418] Furthermore, when the crystalline nano-oxide M is in the form of particles, its particle size ranges from 3 nm to 500 nm;

[0419] Furthermore, when the crystalline nano-oxide M is in the form of a plate, its thickness is 6nm to 75nm, and the average area of ​​the plate is greater than 30nm. 2 ;

[0420] Furthermore, when the shape of the crystalline nano-oxide M is an elongated strip, its diameter ranges from 3 nm to 60 nm, and its aspect ratio is greater than 4;

[0421] Furthermore, when the shape of the crystalline nano-oxide M is a tube-rod shape, it includes a tube shape and a rod shape, and its diameter ranges from 3 nm to 200 nm, and its aspect ratio is greater than 2;

[0422] Furthermore, when the shape of the crystalline nano-oxide M is a sintered agglomerate shape, its particle size increases significantly due to sintering and agglomeration, and the particle size ranges from 5 nm to 1 mm.

[0423] Furthermore, the composite nano-metal oxide with improved crystallinity contains at least two of the three sub-elements of Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide, at least two of the three sub-elements of Ti, M-type sub-elements, and D-type sub-elements are compounded with corresponding oxides of different types of elements at the atomic / atomic cluster scale or fine phase (abbreviation for fine phase) scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm;

[0424] Furthermore, in the composite nano-metal oxide, at least two of the three sub-elements, namely, Ti element, M-type sub-elements, and D-type sub-elements, undergo in-situ embedded recombination of heterogeneous elements with corresponding oxides at the atomic / atomic cluster scale or fine phase scale.

[0425] In a fourth aspect, a method for preparing a composite nano-metal oxide intermediate product is characterized by comprising the following steps:

[0426] Step 1), the process is completely consistent with the process described in step (1) of the third aspect, please refer to the description of the third aspect for details;

[0427] Step 2), the process is completely consistent with the process described in step (2) of the third aspect, see the details of the third aspect;

[0428] Step 3), the process is completely consistent with the process described in step (3) of the third aspect, see the details of the third aspect;

[0429] Step 4), the process is completely consistent with the process described in step (4) of the third aspect, see the details of the third aspect;

[0430] In the step 4),

[0431] Furthermore, when the Ti-containing intermediate product is a phase, its shape includes at least one of a film, a tube, a rod, and a fiber.

[0432] Furthermore, when the Ti-containing intermediate product is a phase, its shape includes at least one of a tube, a rod, and a fiber.

[0433] The fourth aspect of steps 1) to 4) is completely consistent with the third aspect of steps (1) to (4), including the detailed description of each sub-step. For details, please refer to the third aspect of steps (1) to (4), which will not be repeated here.

[0434] In its fifth aspect, the present application also relates to a composite nano-metal oxide, characterized in that it is prepared according to the preparation method described in the first aspect, and its preparation process and detailed features are described in steps 1 to 4 of the first aspect, and its detailed features also include:

[0435] The composite nano-metal oxide comprises at least two of the three sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide, at least two of the three sub-elements of Ti, M-type sub-elements, and D-type sub-elements are compounded with corresponding oxides of heterogeneous elements at the atomic / atomic cluster scale or the fine phase (abbreviation of fine phase) scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; the average particle size of the fine phase is less than 250nm; wherein the M-type sub-elements comprise at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements comprise at least one of Zr and Hf.

[0436] Furthermore, in the composite nano-metal oxide, at least two of the three sub-elements, namely, Ti element, M-type sub-elements, and D-type sub-elements, undergo in-situ embedded recombination of heterogeneous elements with corresponding oxides at the atomic / atomic cluster scale or fine phase scale.

[0437] In its sixth aspect, the present application also relates to a composite nano-metal oxide intermediate product, characterized in that it is prepared according to the preparation method described in its second aspect, and its preparation process and detailed features are described in steps 1 to 3 of its second aspect, and its detailed features also include:

[0438] The composite nano-metal oxide intermediate product comprises at least two of three sub-elements: element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide intermediate product, at least two of the three sub-elements: Ti, M-type sub-elements, and D-type sub-elements, are compounded with corresponding oxide intermediate products of different types of elements at the atomic / atomic cluster scale or fine phase (abbreviation for fine phase); wherein the atomic / atomic cluster scale is 0.25 nm to 2.5 nm; and the average particle size of the fine phase is less than 250 nm;

[0439] Furthermore, in the composite nano-metal oxide intermediate product, at least two of the three types of sub-elements, namely Ti element, M type sub-elements and D type sub-elements, undergo in-situ embedding recombination of heterogeneous elements corresponding to the oxide intermediate product at the atomic / atomic cluster scale or fine phase scale.

[0440] In its seventh aspect, the present application also relates to a composite nano-metal oxide, which is characterized in that it is prepared according to the preparation method described in its third aspect, and its preparation process and detailed characteristics are described in its third aspect.

[0441] In its eighth aspect, the present application also relates to a composite nano-metal oxide intermediate product, which is characterized in that it is prepared according to the preparation method described in its fourth aspect, and its preparation process and detailed characteristics are described in its fourth aspect.

[0442] In its ninth aspect, the present application also relates to the application of the product materials prepared by the preparation method described in any one of aspects one to four, or the materials described in aspects five to eight, in composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, color-changing materials, absorbing materials, sewage degradation materials, sterilization materials, coatings, pigments, thermal spray materials, and sensors.

[0443] In a tenth aspect, a method for preparing a composite oxide ceramic is characterized by comprising the following steps:

[0444] Step S1, preparing a uniformly mixed and refined mixed powder, wherein the mixed powder comprises a composite nano-metal oxide or an intermediate product prepared by the preparation method described in any one of aspects one to four, and an added powder; wherein the molar percentage content of the composite nano-metal oxide or the intermediate product in the mixed powder is V1, the molar percentage content of the added powder in the mixed powder is V2, and the added powder comprises at least one of Al2O3, CaO, MgO, SiO2, B2O3, and BeO, and 1%≤V1≤100%, and 0≤V2≤99%;

[0445] Step S2: Pressing the mixed powder into a green body, and calcining it at a high temperature to obtain a composite oxide ceramic material.

[0446] In the step S1,

[0447] Further, 2%≤V1≤100%; 0≤V2≤98%; further, 10%≤V1≤100%; 0≤V2≤90%; further, 50%≤V1≤100%; 0≤V2≤50%;

[0448] When V2=0, no external powder is needed; however, the powder can be further evenly mixed and refined through the mixing process;

[0449] When V2>0, the mixed powder contains, in addition to the composite nano-metal oxide or intermediate product prepared by the preparation method according to any one of the first to fourth aspects, an additional powder component, and therefore the mixed powder needs to be uniformly mixed and refined through a mixing process;

[0450] Furthermore, the process of preparing the uniformly mixed and refined mixed powder includes at least one of ball milling and sand milling; when the mixing process is a wet method, the uniformly mixed and refined mixed powder is obtained by drying after the mixing process is completed; during the mixing process, the powder is crushed and refined at the same time;

[0451] Furthermore, the composite nano-metal oxide or intermediate product prepared by the preparation method of any one of the first to fourth aspects contains D hydroxide or (and) DO2;

[0452] Furthermore, the composite nano-metal oxide or intermediate product prepared by the preparation method of any one of the first to fourth aspects contains DO2 and Y oxide;

[0453] The molar percentage of ZrO2 in the composite nano-metal oxide or intermediate product prepared by the preparation method of any one of the first to fourth aspects is greater than 50%;

[0454] Furthermore, the molar percentage of ZrO2 in the mixed powder is greater than 25%; further, the molar percentage of ZrO2 in the mixed powder is greater than 50%; further, the molar percentage of ZrO2 in the mixed powder is greater than 75%;

[0455] Furthermore, the molar percentage of ZrO2 in the mixed powder is greater than 75%, and the mixed powder includes a composite nano-metal oxide of ZrO2 and Y2O3;

[0456] In the step S2,

[0457] Furthermore, the molding pressure of the compact is 5MPa to 800MPa; further, the molding pressure of the compact is 5MPa to 80MPa;

[0458] Further, the calcination temperature is 500°C to 2000°C; further, the calcination temperature is 500°C to 1500°C;

[0459] Furthermore, the process of pressing the green body and then calcining it at high temperature includes at least one of the following two schemes: pressing and calcining at the same time, and pressing first and then calcining.

[0460] In its eleventh aspect, a composite oxide ceramic is characterized in that it is prepared according to the preparation method described in its tenth aspect, and its detailed characteristics are described in its tenth aspect.

[0461] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0462] First, by using alloys as raw materials, composite nano-metal oxides of multiple components can be prepared at one time. Taking the preparation of composite nano-metal oxides composed of oxidized Nb (Nb2O5), TiO2, and ZrO2 as an example, the traditional method first needs to prepare three nano-metal oxides of Nb2O5, TiO2, and ZrO2 separately, and then mix them evenly to obtain composite nano-metal oxides. Due to the agglomeration problem of the powder material, it is difficult to ensure their uniform mixing, and all mixing is physical mixing. A further improved method can be achieved by separately preparing Nb-T intermetallic compound initial alloy, Ti-T intermetallic compound initial alloy, and Zr-T intermetallic compound initial alloy, and then mixing the three intermetallic compound alloys and then performing a hydrogen evolution and de-T reaction process similar to the present application. Although this method has been improved, there are two disadvantages: it is necessary to prepare three intermetallic compound initial alloys; since Nb and Ti belong to different intermetallic compounds in the initial alloy, it is difficult to ensure the acquisition of in-situ embedded composite Nb-containing intermediate products and Ti-containing intermediate products. In the present application, it is only necessary to select Al as T based on the molar ratio of the A-type elements Nb, Ti, and Zr in the final composite nano-metal oxide, such as the molar ratio Nb:Ti:Zr = 1:1:1. Then, based on the Al-Ti, Al-Nb, and Al-Zr phase diagrams, select the appropriate Al content to ensure that the Nb, Ti, and Zr elements are all present in the intermetallic compound Al-(Nb / Ti / Zr) in the AT intermetallic compound. At this time, it is not necessary to worry about the specific number of intermetallic compound phases in the Al-(Nb / Ti / Zr) intermetallic compound, nor is it necessary to worry about whether the composition of each phase contains one, two, or three of the Nb, Ti, and Zr elements. In this way, the molar ratio of Nb, Ti, and Zr in the composite nano-metal oxide can be designed from a single initial alloy. Furthermore, because the elements in the Al-(Nb / Ti / Zr) intermetallic compound have a high solid solubility with each other, for example, in a TiAl3 intermetallic compound, if 5% of the original 25% Ti is replaced by Nb, and Nb exists in solid solution, the resulting Ti(Nb)Al3 intermetallic compound still has a nearly identical crystal structure to the TiAl3 intermetallic compound. In this case, Nb and Ti coexist in the same intermetallic compound, and the evolution of both occurs simultaneously in situ during the hydrogen evolution and de-TiO2 reaction. This makes it possible for the subsequent in-situ intercalation of Nb2O5 and TiO2. Furthermore, the simultaneous generation of the products ensures the uniformity of the composite components. These characteristics contribute to the superior performance of composite nanometal oxides.

[0463] In particular, when the sub-class elements of Class A are not dominant, the great advantages of preparing composite nano-metal oxides in each step of the present application and subsequent other aspects are reflected: because the key to the performance of the composite nano-metal oxide lies in the performance of the final prepared product, when the sub-class elements have a great interaction and influence in the process of hydrogen evolution and de-T and change the evolution and formation trend when each is dominant, a uniform compound that cannot be obtained by other methods can be obtained; after the process described in step 2 of the first aspect exists, this uniform compound state will continue to exist in the preparation process corresponding to steps 3 and 4 of the first aspect; and this uniform compound is not only reflected in the physical mixing uniformity, but also in the chemical uniform compound, such as the generation of a new single-phase composite material, which simultaneously includes two to three sub-class elements and is uniformly distributed at the scale of atoms or atomic clusters, such as single-phase nano-oxide Ti / M; this special compound can make the finally obtained composite nano-metal oxide obtain extremely excellent performance.

[0464] Secondly, it achieves the short-term and efficient preparation of composite nano-metal oxides. Although the strong alkaline hydrothermal method is currently a relatively mature process for preparing nano-titanates, nano-titanic acids, and nano-TiO2, the reaction requires a high-pressure reaction vessel. Generally, nano-TiO2 and a high-concentration strong base (such as NaOH solution) are used as raw materials. The hydrothermal synthesis is carried out under high temperature conditions for an extremely long time. The reaction produces titanates (such as sodium titanate). After neutralization and acid washing, titanate nanotubes are generally obtained. For example, a literature report in 2001 used industrial anatase TiO2 and 10 mol / L sodium hydroxide solution as raw materials. After a hydrothermal reaction at 130°C for 72 hours in a high-pressure reaction vessel, titanate nanotubes with a tube length of tens to hundreds of nanometers and an inner diameter of 5.3 nm were obtained. Other preparation methods include: weighing NaOH and commercial TiO2 according to a stoichiometric ratio, transferring them into a polytetrafluoroethylene autoclave, mixing them, and maintaining the mixture at 230°C for 48 to 96 hours. After cooling to room temperature, the mixture is removed, washed, and dried to obtain sodium titanate nanotubes, which are then further acid-washed to obtain titanate nanotubes. Thus, the characteristics of the traditional strong alkaline hydrothermal method are: 1) using TiO2 as the titanium source; 2) being carried out in a high-pressure reaction vessel, requiring sealed and high-pressure conditions; 3) being carried out at a relatively high temperature; 4) requiring a very long reaction time to first break the stable O-Ti bonds and then reform them, often taking tens of hours; and 5) the resulting product is generally titanate nanotubes or titanate nanotubes. In contrast, the present application also uses a strong alkaline solution when preparing nanocomposite metal oxides containing nano-titanates, but it is significantly different from the traditional strong alkaline hydrothermal method: 1) a Ti-containing intermetallic compound is used as the titanium source; 2) the reaction can be carried out in an open container and at normal pressure, and does not necessarily require a high-pressure closed container; 3) it is preferably carried out near the boiling point of the alkaline solution, and the upper limit of the temperature is the boiling point of the alkaline solution, which is very easy to accurately control; 4) the reaction can be completed in a few minutes or even tens of seconds. Therefore, the present application cleverly changes the traditional oxide raw material to the intermetallic compound initial alloy raw material, greatly shortening the reaction time and improving efficiency.

[0465] This obvious beneficial effect, in particular, greatly shortens the preparation time of the target product, and is consistent with the initial alloy being heated at a higher temperature, preferably the boiling point of the alkaline solution T f溶液The reaction is closely related to the reaction. When the reaction is under normal pressure and occurs at the boiling point of the alkaline solution, the solution composition of the reaction system has obvious particularity, which is specifically manifested in that: far below the boiling point of the solution, the solvent mainly exists as liquid water; but at the boiling point of the solution or very close to the boiling point, in addition to liquid water and a large amount of highly active gaseous water (gaseous water produced by evaporation at the boiling point), the solvent also contains highly active water that is undergoing a transformation from liquid water to gaseous water. Moreover, under this special environment, the content and state of the atmospheric gases (oxygen, nitrogen) dissolved in the solvent are also extremely special (because the large amount of water vapor and hydrogen changes the saturated partial pressure conditions of the dissolved gases in water). In addition, the large amount of hydrogen generated by the reaction of the AT intermetallic compound with the concentrated alkaline solution, as well as the small amount of salt dissolved in the solution, will change the material composition of the reaction system, all of which provide a very special reaction environment for the reaction. This special reaction environment can greatly shorten the preparation time of the target product. In comparison, for example, the traditional high-pressure hydrothermal method for preparing nano-titanate films uses extremely stable TiO2 as the Ti source. It requires high pressure, high temperature, and long-term reactions to first destroy the Ti-O bond structure of TiO2. Only after the Ti-O bond is destroyed can new intermediate products and final products be further generated. The time required is generally calculated in hours. Moreover, when the concentration of the alkali in the solution is determined, the boiling point temperature that the solution can be heated to under normal pressure is also determined, which means that the pressure and temperature in the reaction conditions are precisely determined. The boiling point of the solution T f溶液 At this temperature, any excess heat added to the solution will be converted into the heat of vaporization of water without increasing the solution temperature. This allows the solution temperature to be kept constant at the boiling point by continuous heating. Even if a large amount of latent heat is generated by the hydrogen evolution and dehydrogenation of the intermetallic compound during the reaction, the temperature of the reaction solution can still be maintained at the boiling point of the solution.

[0466] Third, the present invention has discovered that when an AT intermetallic compound reacts with an alkaline solution at a certain temperature and concentration at a reaction rate exceeding 2 μm / min, particularly preferably at the boiling point of the alkaline solution, the shape of the initial alloy can be rapidly and completely destroyed, achieving nano-fragmentation of the original initial alloy. Simultaneously, through shape and composition reconstruction, a nanoscale solid material containing M or (and) Ti with particle dispersion is generated. In contrast, the products prepared by dealloying at room temperature or lower temperatures are generally nanoporous metal oxides or nanoporous metals, which retain the shape of the original initial alloy particles before the reaction, including their angular shape. For example, in Comparative Example 1, when the (TiNb)Al3 intermetallic compound initial alloy powder was reacted with a 10 mol / L NaOH solution at 25°C for 2 hours under normal pressure (the average propagation rate at the reaction interface was less than 0.5 μm / min), the shape of the original initial alloy powder remained largely unchanged before and after the reaction, remaining the original fragmented and angular powder particles. Furthermore, its microstructure did not produce products with particle dispersion such as nanoparticles, nanosheets, or nanorods, but instead formed a nanoporous structure. And this nanoporous structure forms an appearance consistent with the shape of the original initial alloy powder by a three-dimensional continuous network connection, and its particle size is still the size of the initial alloy powder, mainly a few microns or tens of microns. In the preparation process of the present application, when the average particle size of the initial alloy powder is 10 μm, by regulating the alkali concentration and alkali temperature, after nano-fragmentation at a reaction rate of more than 2 μm / min, the resulting product is a solid material containing M or (with) Ti with particle dispersibility having an average particle size of no more than 500 nm, and the particles do not contain a nanoporous secondary structure, and these solid materials containing M or (with) Ti are also dispersible. Although they can be softly agglomerated together, they are not tightly rigidly connected together by a three-dimensional continuous network structure to maintain the shape of the original initial alloy, including the angular shape of its particles. In other words, by the preparation method of the present application, regardless of the size of the initial alloy shape, a dispersible nanoscale solid material containing M or (with) Ti is obtained by nano-fragmentation during the hydrogen evolution and de-T reaction. Therefore, given that the particle size of the initial alloy is generally large, such as the strip is generally thicker than 10 μm, and the average particle size of the powder particles is generally greater than 5 μm, the reaction of the AT intermetallic compound with the alkaline solution at a relatively low temperature or room temperature generally still produces large-particle nanoporous metal oxides or nanoporous metals in the micron range. These products are not suitable for many occasions where fine particles and dispersion are required. However, the present application realizes the preparation of highly dispersed nanoscale solid materials containing M or (with) Ti, which has obvious positive significance.

[0467] Moreover, shape reconstruction occurs at the same time as nano-fragmentation. The shape reconstruction refers to the nanoscale product obtained by the hydrogen evolution and de-Ti reaction, which is not a simple fragmentation of the nanoporous structure (ligament), but a complete reconstruction. If the low-temperature hydrogen evolution and de-Ti reaction obtains a nanoporous structure, and the product obtained by the high-temperature hydrogen de-Ti reaction simply fragments the nanoporous structure, it can only be called a simple fragmentation, and the product morphology is a fragmented porous ligament (ligament). However, the solution described in the present application does not involve such a simple fragmentation, but also includes shape reconstruction; various morphologies of solid substances containing M or (with) Ti, such as lamellar structures, flocculent structures, and especially film-like structures, cannot be simply obtained by fragmenting nanoporous structure ligaments. Therefore, the present application creatively realizes that the solid substance containing M or (with) Ti is not formed by relying on the formation mechanism of the nanoporous structure and further simply fragmented, but is formed through a special fragmentation and complete reconstruction process.

[0468] Fourth, the researchers achieved in-situ intercalation of M-containing intermediates with Ti-containing intermediates, and even a small number of D-containing intermediates with M-containing intermediates and / or Ti-containing intermediates. This intercalation differs from the conventional van der Waals physical adsorption-based adsorption reported in other literature (where nanoparticles adsorbed by van der Waals forces can move and fall off). This intercalation ensures that the M-containing intermediates, Ti-containing intermediates, and D-containing intermediates are tightly intercalated (preventing them from moving or falling off), resulting in more superior properties.

[0469] Fifth, the present application has found that the D-type elements (Zr and Hf elements) in the initial alloy, when reacting with a hot concentrated alkaline solution, can be dissolved in the hot concentrated alkaline solution, and this solubility is significantly enhanced as the temperature rises. When the reaction is under normal pressure, and preferably at the boiling point of the alkaline solution, this dissolution phenomenon is extremely obvious. The dissolution described here is not the meaning of dissolution in a narrow sense, but specifically refers to the dissolution of metal compounds containing D-type elements in an excess of hot concentrated alkaline solution in a certain manner similar to a complex or other unknown manner after a series of reactions. In particular, this solubility characteristic of the Zr and Hf elements is related to the concentration of the alkaline solution. When the alkali concentration of the intermediate solution in which the Zr and Hf elements are dissolved is reduced, the solid flocculent material containing Zr and Hf, D hydroxide, will precipitate out. This discovery is different from the preparation of metal nanoporous structures by the traditional dealloying method and the preparation of nano metal oxides by the traditional dealloying method. During these traditional dealloying reactions, the reactants, intermediates, and final products remain in solid form, their composition and morphology constantly changing. Since Zr and Hf are soluble in concentrated alkaline solutions, and their precipitation from the reduced alkaline solution is a de novo process, this characteristic can be exploited to obtain extremely fine D hydroxide by subsequently reducing the alkaline solution concentration or adding a surfactant, which has significant positive implications. When the reaction system has already generated a solid substance containing M or (combined with) Ti, lowering the alkaline concentration to induce the precipitation of D hydroxide allows for extremely uniform composite formation of nano-D hydroxide with the M or (combined with) Ti solid. This uniform composite is crucial for the product performance of subsequent material preparation, such as ceramic sintering, and has positive implications.

[0470] Sixth, the preparation of dispersible and refined crystalline composite nano-metal oxides has been achieved. For example, crystalline nano-ZrO2 has always been a key raw material for advanced ceramic materials. The low-cost preparation method of crystalline nano-ZrO2 mainly involves first preparing a zirconium hydroxide precursor (such as by reacting zirconium oxychloride with ammonia water to precipitate zirconium hydroxide flocculent precipitate), then heat-treating and sintering to obtain crystalline ZrO2, and finally dispersing and refining the sintered crystalline ZrO2 through ball milling or sand milling to obtain crystalline nano-ZrO2 powder particles, an important raw material for advanced ceramic products. The finer the powder particles, the better the performance. Currently, the industry has not yet solved the problem that although the colloidal zirconium hydroxide obtained by precipitation is extremely fine, after sintering, it often produces large particles of sintered crystalline nano-ZrO2. These large particles of ZrO2 are very dense (see Figures 25-26 of Comparative Example 2), making it difficult to disperse and refine them to the size of grains through subsequent ball milling or sand milling. In practice, only large particles of ZrO2 consisting of several or dozens of grains can be obtained (see Figures 25-26 of Comparative Example 2). This greatly limits the low-cost preparation and application of crystalline ZrO2. To obtain extremely fine crystalline ZrO2, the industry currently can only use high-temperature and high-pressure hydrothermal methods, which are more expensive, have lower production capacity, and are more complex. The present application solves this problem very well. For example, the present application first prepares a composite nano-metal and oxide intermediate product of zirconium hydroxide and a Ti-containing intermediate product or (with) an M-containing intermediate product, so that during the subsequent high-temperature sintering process, the Ti-containing intermediate product or (with) the M-containing intermediate product obtained by doping and compounding the crystalline ZrO2 has excellent microscopic looseness and dispersion characteristics. It can be well dispersed and refined by subsequent ball milling or sand milling, thereby preparing a dispersed crystalline ZrO2 composed of a single or very few grains through doping and compounding (see Figures 7-8 of Example 1). This technology not only solves the dispersibility and particle size problems of sintered crystalline ZrO2, but also allows the components involved in the compound to be fully and uniformly mixed with the crystalline ZrO2 through in-situ compounding. For example, when the composite component includes Cr2O3 (a raw material for high-end refractory materials, also often used as a high-end green inorganic pigment), it can not only significantly improve the heat resistance temperature of ZrO2-Cr2O3 ceramic products, but also achieve a coloring effect.

[0471] Seventh, composite nano-metal oxide intermediates with improved thermal stability or (with) crystallization temperature, as well as composite nano-metal oxides with improved particle porosity or specific surface area can be prepared.

[0472] Eighth, the composite nano-metal oxides or intermediate products prepared by the preparation method described in any one of aspects one to four of the present application have been fully mixed during the preparation process, especially the in-situ embedding corresponding mixing, which greatly reduces the cost required for uniform mixing between the various components of the composite nano-metal oxides.

[0473] In summary, in the technical solution involved in the present invention, the reaction time is from tens of seconds to several minutes; the reaction conditions can be precisely controlled and the reaction can be terminated quickly. These features greatly simplify the production process, improve production efficiency, and reduce production costs, making low-cost large-scale preparation of corresponding product materials possible. Therefore, the technical solution and preparation method involved in the present invention have the characteristics of simple process, easy control, high efficiency and low cost, and can be used to prepare a variety of composite nano-metal oxides, which are suitable for application in composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, color-changing materials, absorbing materials, sewage degradation materials, sterilization materials, coatings, pigments, thermal spray materials, and sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0474] FIG1 is a low-magnification SEM photograph of the solidified structure of the initial alloy of Example 1;

[0475] FIG2 is a high-magnification SEM photograph of the solidified structure of the initial alloy of Example 1;

[0476] FIG3 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide intermediate product prepared in Example 1;

[0477] FIG4 is a medium-magnification and high-magnification TEM photograph of the composite nano-metal oxide intermediate product prepared in Example 1;

[0478] FIG5 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide prepared in Example 1 after heat treatment at 600° C.;

[0479] FIG6 is a medium and high magnification TEM image of the composite nano-metal oxide prepared in Example 1 after heat treatment at 600° C.;

[0480] FIG7 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide prepared in Example 1 after heat treatment at 900° C.;

[0481] FIG8 is a medium and high magnification TEM image of the composite nano-metal oxide prepared in Example 1 after heat treatment at 900° C.;

[0482] FIG9 is a SEM photograph of the solidified structure of the initial alloy of Example 2;

[0483] FIG10 is an XRD spectrum of the composite nano-metal oxide intermediate product prepared in Example 2, the composite nano-metal oxide heat-treated at 650° C., and the composite nano-metal oxide heat-treated at 900° C.;

[0484] FIG11 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide intermediate product prepared in Example 3;

[0485] FIG12 is a high-magnification TEM photograph of the composite nano-metal oxide intermediate product prepared in Example 3;

[0486] FIG13 is a low-magnification TEM photograph of the composite nano-metal oxide prepared in Example 3 after heat treatment at 900° C.;

[0487] FIG14 is a medium and high magnification TEM photograph of the composite nano-metal oxide prepared in Example 3 after heat treatment at 900° C.;

[0488] FIG15 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide intermediate product prepared in Example 4;

[0489] FIG16 is a high-magnification TEM photograph of the composite nano-metal oxide intermediate product prepared in Example 4;

[0490] FIG17 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide intermediate product prepared in Example 5;

[0491] FIG18 is a medium and high magnification TEM image of the composite nano-metal oxide prepared in Example 5 after heat treatment at 1100° C.;

[0492] FIG19 is a low-magnification TEM photograph and diffraction spectrum of the composite nano-metal oxide intermediate product prepared in Example 6;

[0493] FIG20 is a low-magnification and high-magnification SEM photograph of the product obtained in Comparative Example 1;

[0494] FIG21 is a low-magnification TEM photograph and diffraction spectrum of low-crystallinity nano-zirconium hydroxide prepared in Comparative Example 2;

[0495] FIG22 is a high-magnification TEM photograph of low-crystallinity nano-zirconium hydroxide prepared in Comparative Example 2;

[0496] FIG23 is a low-magnification TEM image and diffraction spectrum of nano-Zr oxide after heat treatment at 600° C. prepared in Comparative Example 2;

[0497] FIG24 is a high-magnification TEM photograph of nano-Zr oxide after heat treatment at 600° C. prepared in Comparative Example 2;

[0498] FIG25 is a low-magnification TEM image and diffraction spectrum of nano-Zr oxide after heat treatment at 900° C. prepared in Comparative Example 2;

[0499] FIG26 is a high-magnification TEM photograph of nano-Zr oxide after heat treatment at 900° C. prepared in Comparative Example 2. DETAILED DESCRIPTION

[0500] The technical solution will be further described below through the following specific embodiments:

[0501] Example 1

[0502] This embodiment provides a method for preparing a composite nano-metal oxide and a composite oxide ceramic containing Zr, Nb and Ti elements, comprising the following steps:

[0503] According to Al 75 Zr 18 The nominal ratio of Ti4Nb3 (atomic percentage) is to weigh the metal Nb, Zr, Ti, and Al raw materials, and smelt them to obtain a composition mainly composed of Al 75 Zr 18 The alloy melt of Ti4Nb3 is then solidified into an alloy ingot, which is then crushed into an initial alloy powder with an average particle size of 100 μm. The solidification microstructure phase is mainly composed of Al 73 Zr 20 Ti3Nb4 and Al 76 Zr 13 Ti 10 Nb1 is composed of two intermetallic compounds with a composition of approximately Al 73 Zr 20 The main metal compound is Ti3Nb4, as shown in the SEM images of the alloy ingot solidification structure in Figure 1 and Figure 2. 73 Zr 20 The intermetallic compound of Ti3Nb4 may be Al3Zr phase with solid solution of Ti and Nb; Al 76 Zr 13 Ti 10 The intermetallic compound of Nb1 may be Al3(Zr-Ti) phase with Nb solid solution;

[0504] At normal pressure, 4g of Al 75 Zr 18 The Ti4Nb3 initial alloy powder reacts with a NaOH aqueous solution and is continuously stirred; wherein the concentration of the NaOH solution is 12 mol / L, the temperature is its boiling point at normal pressure (~128°C), and the volume of the NaOH solution is 300 ml; within 2 minutes, the hydrogen evolution and Al removal reaction is completed, and Al 75 Zr 18 The Ti4Nb3 initial alloy powder undergoes nano-fragmentation through hydrogen evolution and de-Al reaction, and simultaneously undergoes shape and composition reconstruction to form a solid flocculent material containing Ti, Nb, and a small amount of Zr, while most of the Zr is mainly dissolved in the alkaline solution. When the solid flocculent material is formed, it is microscopically composed of a large number of extremely small flocculent microstructures softly agglomerated, with the scale of a single microstructure being much smaller than 20nm.

[0505] 3 minutes after the start of the hydrogen evolution and de-Al reaction, 3000 ml of room temperature water was slowly added to the reaction system over 1 minute under vigorous stirring to reduce the concentration of the alkaline solution to below 2 mol / L and the temperature of the alkaline solution to below 40° C. During the process of reducing the concentration of the alkaline solution, most of the Zr element originally dissolved in the alkaline solution nucleated and precipitated in the form of solid colloidal flocculent Zr hydroxide and uniformly mixed with the solid matter containing Ti and Nb already generated in the reaction system.

[0506] The above solid-liquid separation is carried out, and all solid flocculent substances are collected, washed with dilute acid to a pH of 4-5, and then dried to obtain a composite nano-metal oxide intermediate product which is mainly composed of low-crystalline Zr hydroxide and solid flocculent substances containing Ti and Nb. The low-magnification, medium-magnification and high-magnification TEM morphology and diffraction spectrum are shown in Figures 3-4. As can be seen from Figure 3, the average particle size of the composite nano-metal oxide intermediate product agglomerates is less than 250nm. As can be seen from the high-magnification photo illustration of Figure 4, the composite nano-metal oxide intermediate product agglomerates are composed of finer flocculent microstructures, which are mainly composed of colloidal flocculent Zr hydroxide. Since the agglomerates are amorphous, it is difficult to observe the details of the microstructure. Since the pure Al-Nb intermetallic compound also produces colloidal Nb hydroxide or amorphous Nb oxide under the above reaction conditions, it cannot be distinguished from the colloidal Zr hydroxide by TEM contrast in Figures 3-4; since Ti accounts for a relatively small molar percentage of the total Zr, Ti, and Nb in the initial alloy, and the molar percentages of Nb and Ti are almost equivalent, when the Ti-containing intermediate product and the Nb-containing intermediate product are generated simultaneously during the hydrogen evolution and de-Al reaction, the Ti-containing intermediate product fails to form in the form of a two-dimensional nano-titanate film (the pure Al-Ti intermetallic compound produces a two-dimensional nano-titanate film with a thickness of 0.5nm-4nm under the above reaction conditions, which becomes a two-dimensional nano-titanate film with a thickness of 0.5nm-4nm after acid washing); based on this, it can be judged that the Ti-containing intermediate product and the Nb-containing intermediate product undergo sufficient recombination at the same time as they are generated, and it may exist as a certain colloidal intermediate product containing Ti / Nb, and it is difficult to distinguish it from the colloidal Zr hydroxide by contrast. Among them, Ti-containing intermediates, Nb-containing intermediates, and a small amount of Zr-containing intermediates generated simultaneously and previously occurred in situ embedded recombination at the atomic or atomic cluster scale.

[0507] The above-mentioned composite nano-metal oxide intermediate product is heat-treated at 600°C for 2h to obtain a partially crystallized composite nano-metal oxide; its low-magnification, medium-magnification and high-magnification TEM morphology and diffraction spectrum are shown in Figures 5-6; it can be seen that the average particle size of the partially crystallized composite nano-metal oxide agglomerates is less than 150nm (the flocculent agglomerates have shrunk). Combined with Comparative Example 2, the pure Al3Zr intermetallic compound is first reacted under similar conditions to this embodiment to obtain flocculent nano-zirconium hydroxide (as shown in Figures 21-22), whose morphological boundaries are relatively fuzzy; when the pure flocculent nano-zirconium hydroxide is heat-treated at 600°C for 2h, what is obtained is obviously crystallized nano-zirconium dioxide, as shown in Figure 23, which shows clearer layered diffraction rings, and in Figure 24, the originally fuzzy flocculent morphological boundaries in Figure 22 have become clear white and bright morphological boundaries under the high-magnification morphology. Comparison confirms that the thermal stability and crystallization temperature of the composite nano-metal oxide intermediate product, primarily composed of Zr hydroxide, obtained in this example have been significantly improved. This means that it is more difficult to crystallize than pure colloidal Zr hydroxide prepared under similar conditions. This further demonstrates that chemical interactions have led to in-situ intercalation between the components of the composite nano-metal oxide intermediate product, consisting of the first-precipitated Ti-containing intermediate product, the Nb-containing intermediate product, the small amount of Zr-containing intermediate product, and the subsequent-precipitated nano-Zr hydroxide intermediate product, prior to heat treatment. This in-situ intercalation characteristic is retained in the product after heat treatment at 600°C for 2 hours.

[0508] The composite nano-metal oxide intermediate product was heat-treated at 900°C for 2 hours to obtain a crystalline composite nano-metal oxide mainly composed of nano-zirconium oxide. Its low-, medium-, and high-magnification TEM morphologies and diffraction spectra are shown in Figures 7-8. It can be seen that the average particle size of the crystalline composite nano-metal oxide is less than 100nm (further sintering shrinkage has occurred), and although a certain amount of sintering agglomeration has occurred between these particles, they still maintain a loose sintering agglomeration state, or a structure similar to a nanoporous structure, which is composed of a large number of strip-like structures with a diameter of 20nm-40nm. This structure makes the prepared composite nano-metal oxide have a high particle looseness or specific surface area. In conjunction with Comparative Example 2, a simple Al3Zr intermetallic compound was reacted under similar conditions to this example to obtain a colloid-like nano-zirconium hydroxide (as shown in Figures 21-22). When the simple colloid-like nano-zirconium hydroxide was heat-treated at 900°C for 2 hours, a crystallized nano-zirconium hydroxide was obtained, as shown in Figures 25-26. However, although it is a polycrystalline particle, it is sintered and agglomerated into solid large particles, completely losing the looseness of the particles and also showing a low specific surface area. Due to the high strength of zirconium oxide itself, such solid large particles can hardly be crushed by subsequent sand milling and ball milling. Therefore, it can be confirmed by comparison that the crystalline composite nano-metal oxide containing Ti and Nb elements mainly composed of nano-zirconium oxide obtained in this embodiment has a higher particle looseness or specific surface area, which solves the industrial problem that the simple nano-zirconium oxide obtained by sintering is difficult to further crush and refine. This also further illustrates that the components of the composite nano-metal oxide intermediate product composed of the first precipitated Ti-containing intermediate product, the Nb-containing intermediate product, a small amount of Zr-containing intermediate product, and the later precipitated nano-zirconium hydroxide intermediate product before the heat treatment have undergone in-situ embedded composite related to chemical interaction, and this in-situ embedded composite feature is retained in the product after heat treatment at 900°C for 2 hours.

[0509] By sand grinding, the crystalline composite nano-metal oxide containing Ti and Nb elements and mainly nano-zirconium oxide is crushed into crystalline composite nano-metal oxide powder with a particle size of 20nm-40nm (the particle size is the diameter range of the composite nano-metal oxide strip structure before crushing).

[0510] The obtained crystalline composite nano-metal oxide powders were mixed and pressed into a green body under a pressure of 50 MPa, and then calcined at 1400°C for 2 hours to obtain a composite nano-oxide ceramic mainly composed of zirconium oxide with a molar ratio of Zr:Ti:Nb of about 18:4:3.

[0511] The obtained crystalline composite nano-metal oxide powder and nano-Al2O3 powder are mixed in a molar ratio of 1:3, wet ball milled and dried to obtain a uniformly mixed mixed powder; the mixed powder is pressed into a green body under a pressure of 50 MPa, and calcined at 1400°C for 2 hours to obtain a composite nano-oxide ceramic further compounded with alumina.

[0512] Example 2

[0513] This embodiment provides a method for preparing a composite nano-metal oxide and a composite oxide ceramic containing Zr and Y elements, comprising the following steps:

[0514] According to Al 75 Zr 23.5 Y 1.5 The nominal composition ratio (atomic percentage) of Zr, Y, and Al raw materials were weighed and smelted to obtain a composition mainly composed of Al 75 Zr 23.5 Y 1.5 The alloy melt is then solidified into an alloy ingot, which is then crushed into an initial alloy powder with an average particle size of 50 μm, the phase composition of which is mainly composed of Al3Zr and Al3Y intermetallic compounds, as shown in FIG9 ;

[0515] Under normal pressure, 3g of the initial alloy ribbon prepared above was reacted with 200mL of a 10mol / L NaOH aqueous solution at its boiling point (119°C) with continuous stirring. Within 1.5 minutes, the hydrogen evolution de-Al reaction was complete. The initial alloy and the alkaline solution were nano-fragmented by the intense hydrogen evolution de-Al reaction, and further reconstructed in shape and composition to form a solid material primarily containing Y. Simultaneously, the vast majority of the Zr in the original initial alloy dissolved in the alkaline solution.

[0516] 3 minutes after the start of the hydrogen evolution and de-Al reaction, water at room temperature is slowly added to the reaction system to reduce the concentration of the alkaline solution to below 1 mol / L, and the temperature of the alkaline solution is simultaneously reduced to below 40°C; gel-like Zr hydroxide nucleates and precipitates from the alkaline solution after the concentration is reduced, and uniformly mixes with the Y-containing solid material already formed in the alkaline solution;

[0517] After solid-liquid separation, a mixed colloidal solid material containing Y and Zr is collected, washed with dilute acid, and dried to obtain a composite nano-metal oxide intermediate product composed of nano-yttrium oxide and low-crystallinity colloidal zirconium hydroxide, and the two are uniformly composited together mainly by physical adsorption; wherein, the particle size of the nano-yttrium oxide ranges from 3 nm to 200 nm; the particle size of the flocculent microstructure of the colloidal zirconium hydroxide is from 0.5 nm to 10 nm; the composite nano-metal oxide intermediate product does not contain a three-dimensional continuous network-like nanoporous structure or a porous skeleton structure; the XRD of the composite nano-metal oxide intermediate product is shown in FIG10 , and due to the low content of yttrium oxide, its XRD peak only shows the diffraction information of low-crystallinity zirconium hydroxide.

[0518] The above-mentioned composite nano-metal oxide intermediate product containing Y and Zr was heat-treated at 650°C for 1.5h to obtain a composite nano-metal oxide uniformly composited with crystalline nano-yttrium oxide and partially crystalline nano-zirconium oxide; wherein the particle size of the crystalline nano-yttrium oxide is in the range of 3nm to 200nm; the particle size of the partially crystalline nano-zirconium oxide is in the range of 3nm to 200nm; the XRD of the composite nano-metal oxide is shown in Figure 10. Since the nano-zirconium oxide is not completely crystallized, the peak intensity is not very obvious, and due to the low content of yttrium oxide, its XRD peak is not obvious.

[0519] The above-mentioned composite nano-metal oxide intermediate product containing Y and Zr was heat-treated at 900°C for 1.5 hours to obtain a composite nano-metal oxide containing Y oxide mainly composed of Zr oxide; its particle size was less than 250 nm, and its XRD was shown in Figure 10. It can be seen that zirconium oxide was obviously crystallized and the peak intensity was also obvious. Due to the low content of yttrium oxide, its XRD peak was not obvious.

[0520] The composite nano-metal oxide heat-treated at 900°C for 1.5 hours was pressed into a green body at a pressure of 30 MPa and calcined at 1450°C for 2 hours to obtain a composite nano-oxide ceramic of yttria-stabilized zirconia, wherein the molar ratio of Zr:Y was approximately 23.5:1.5.

[0521] The composite nano-metal oxide heat-treated at 900°C for 1.5 hours was mixed with nano-Al2O3 powder in a molar ratio of 4:1, wet-milled and dried to obtain a uniformly mixed powder; the mixed powder was pressed into a green body under a pressure of 50 MPa, and calcined at 1450°C for 2 hours to obtain a composite nano-oxide ceramic containing alumina, yttrium oxide and zirconium oxide.

[0522] Example 3

[0523] This embodiment provides a method for preparing a composite nano-metal oxide and a composite oxide ceramic containing Hf and Cr elements, comprising the following steps:

[0524] According to Al 75 Hf 20 The nominal ratio of Cr5 (atomic percentage) is to weigh the metal Hf, Cr, and Al raw materials, and smelt them to obtain a composition mainly composed of Al 75 Hf 20 Cr5 alloy melt, and then the alloy melt is prepared into Al2O3 with a thickness of 20μm-30μm by melt stripping method. 75 Hf 20 The phase composition of the Cr5 initial alloy strip is mainly composed of Al3Hf(Cr) intermetallic compounds containing Cr.

[0525] At normal pressure, 1g of Al 75 Hf 20 The Cr5 initial alloy strip reacts with a KOH aqueous solution and is continuously stirred; wherein the concentration of the KOH solution is 10 mol / L, the temperature is its boiling point at normal pressure (~125°C), and the volume of the KOH solution is 100 ml; within 1 minute, the hydrogen evolution and Al removal reaction is completed, and Al 75 Hf 20 The initial Cr5 alloy ribbons were nano-fragmented by hydrogen evolution and de-Al reaction, and simultaneously reconstructed in shape and composition to form a solid flocculent material containing mainly Cr and a small amount of Hf, while most of the Hf was mainly dissolved in the alkaline solution.

[0526] Two minutes after the start of the hydrogen evolution and de-Al reaction, 1000 ml of room-temperature water was slowly added to the reaction system over 1 minute under vigorous stirring to reduce the concentration of the alkaline solution to below 1 mol / L, and simultaneously reduce the temperature of the alkaline solution to below 40° C. During the process of reducing the concentration of the alkaline solution, most of the Hf element originally dissolved in the alkaline solution nucleated and precipitated in the form of solid colloidal flocculent Hf hydroxide, and uniformly mixed with the solid colloidal flocculent material mainly containing Cr that had been generated in the reaction system.

[0527] The solid-liquid separation described above is performed, and all solid matter is collected, washed with dilute acid to a pH of 4-5, and then dried to obtain a composite nano-metal oxide intermediate product uniformly composed primarily of low-crystalline Hf hydroxide and a solid flocculent material primarily containing Cr. Its TEM morphology and diffraction spectrum are shown in Figures 11-12. As can be seen from the figures, the average particle size of the composite nano-metal oxide intermediate product agglomerates is less than 200 nm, and the composite nano-metal oxide intermediate product agglomerates are composed of a finer flocculent microstructure, primarily composed of a colloidal flocculent Zr hydroxide intermediate product and a colloidal flocculent Cr hydroxide or colloidal flocculent Cr oxide intermediate product composited therewith. Since a simple Al-Cr intermetallic compound also produces colloidal flocculent Cr hydroxide or amorphous Cr oxide under the above reaction conditions, it cannot be distinguished from the colloidal Hf hydroxide by TEM contrast in Figures 11-12.

[0528] The composite nanometal oxide intermediate product was heat-treated at 900°C for 2 hours to obtain a crystalline composite nanometal oxide composed primarily of nano-Hf oxide, composited with Cr oxide. Its low-, medium-, and high-magnification TEM images are shown in Figures 13-14. The average particle size of the crystalline composite nanometal oxide is less than 50 nm. While some sintering and agglomeration occurs between the particles, they still maintain a loose, agglomerated state, or a nanoporous structure, consisting of numerous strips with diameters of 15 nm to 40 nm. This structure gives the composite nanometal oxide a high particle porosity or specific surface area. This loose structure solves the industrial problem of further fragmentation of the pure Hf oxide nanoparticles obtained by sintering. The existence of this shrinkage structure indicates that before sintering, the colloidal Zr hydroxide intermediate product and the Cr hydroxide (or Cr oxide) intermediate product underwent uniform compounding at an extremely small scale. This uniform compounding evolved into a sintering-induced in-situ embedded compounding during the sintering process, thereby changing the morphology and sintering characteristics of the sintered product and obtaining a crystalline composite nano-metal oxide with higher particle porosity or specific surface area.

[0529] The crystalline composite nano-metal oxide mainly composed of nano-oxidized Hf and composited by oxidized Cr is crushed into crystalline composite nano-metal oxide powder with a particle size of 15 nm to 40 nm by sand grinding.

[0530] The obtained crystalline composite nano-metal oxide powder is mixed and pressed into a green body under a pressure of 50 MPa, and then calcined at 1250° C. for 2 hours to obtain a composite nano-oxide ceramic mainly composed of oxidized Hf and composited with oxidized Cr with a molar ratio of Hf:Cr of about 5:1.

[0531] Example 4

[0532] This embodiment provides a composite nano-metal oxide containing Ti and Ta elements and a preparation method thereof, comprising the following steps:

[0533] According to Al 75 Ti 22 The nominal ratio of Ta3 (atomic percentage) is to weigh the metal Ti, Ta, and Al raw materials, and smelt them to obtain a composition mainly composed of Al 75 Ti 22 The alloy melt is then prepared into an Al2O3 sheet with a thickness of 20 μm to 30 μm by a melt stripping method. 75 Ti 22 Ta 35 The initial alloy strips are mainly composed of Al3Ti(Ta) intermetallic compounds containing Ta.

[0534] At normal pressure, 0.5g of Al 75 Ti 22 The Ta3 initial alloy strip reacts with a NaOH aqueous solution with constant stirring; wherein the concentration of the NaOH solution is 7 mol / L, the temperature is its boiling point at normal pressure (~112°C), and the volume of the NaOH solution is 100 ml; within 2 minutes, the hydrogen evolution and Al removal reaction is completed, and Al 75 Ti 22 The initial Ta3 alloy strips are nano-fragmented by hydrogen evolution and de-Al reaction, and simultaneously undergo shape and composition reconstruction to form solid flocculent materials containing Ti and Ta.

[0535] 3 minutes after the start of the hydrogen evolution and Al removal reaction, the solid-liquid separation was carried out, and the solid flocculent material was collected to obtain a composite nano-metal oxide intermediate product mainly composed of low-crystallinity nano-sodium titanate in which the Ta element participated in the composite; wherein the Ti-containing intermediate product is a nano-sodium titanate matrix, which is mainly in the shape of a film, and the film thickness is 0.5nm-5nm, and the average area of ​​the film is greater than 200nm 2 The Ta-containing intermediate product is nano-Ta oxide, which is embedded and grown in the nano-sodium titanate film by in-situ embedding composite method, and its particle size is 0.5nm-5nm.

[0536] The composite nano-metal oxide intermediate product mainly composed of low-crystallinity nano-sodium titanate in which the Ta element participates in the compounding is pickled with 0.05 mol / L dilute hydrochloric acid to a pH of 4-5, and then dried to obtain a composite nano-metal oxide intermediate product mainly composed of low-crystallinity nano-titanic acid in which the Ta element participates in the compounding; its TEM morphology and diffraction spectrum are shown in Figures 15-16; it can be seen from the diffraction pattern that the obtained composite nano-metal oxide intermediate product is still in a low-crystallinity state; at this time, the nano-sodium titanate matrix before pickling becomes a nano-titanic acid matrix, and its shape is still mainly a thin film (see Figure 15, especially the ultra-thin film in the lower part of the picture), and the film thickness is 0.5nm-5nm, and the average area of ​​the film is greater than 200nm 2 The Ta-containing intermediate product is still nano-Ta oxide, which is embedded and grown in a slightly thicker nano-titanate film through in-situ embedded composite method (as shown in FIG16 ), and its particle size is 0.5 nm-5 nm.

[0537] The composite nano-metal oxide intermediate product mainly composed of low-crystallinity nano-titanic acid with the participation of Ta element is heat-treated at 900℃ for 2h to obtain a composite nano-metal oxide mainly composed of nano-TiO2 with the participation of oxidized Ta. During the sintering process, the titanic acid film evolves into a thickness of 2nm-20nm and an average area greater than 100nm. 2 flake-like crystalline nano-TiO2; at the same time, nano-Ta oxide is in-situ embedded and composited in the flake-like crystalline nano-TiO2.

[0538] Example 5

[0539] This embodiment provides a composite nano-metal oxide containing Zr, Hf, Ti and Cr elements and a preparation method thereof, comprising the following steps:

[0540] According to Al 61 Cr 34 The nominal ratio of Zr3Hf1Ti1 (atomic percentage) is to weigh the metal Zr, Hf, Ti, Cr, and Al raw materials, and smelt them to obtain a composition mainly composed of Al 61 Cr 34 The alloy melt is then solidified into an Al2O3 layer with a thickness of 100 μm to 200 μm. 61 Cr 34 The phase composition of the Zr3Hf1Ti1 initial alloy rapid solidification sheet is mainly composed of Al8Cr5 intermetallic compounds with solid solution of Zr, Hf and Ti.

[0541] At normal pressure, 3g of Al 61 Cr 34The Zr3Hf1Ti1 alloy initial quick-setting sheet reacts with a NaOH aqueous solution with continuous stirring; wherein the concentration of the NaOH solution is 12 mol / L, the temperature is its boiling point at normal pressure (~128°C), and the volume of the NaOH solution is 300 ml; within 3 minutes, the hydrogen evolution and Al removal reaction is completed, and Al 61 Cr 34 The initial Zr3Hf1Ti1 alloy flakes undergo nano-fragmentation through hydrogen evolution and de-Al reaction, and are simultaneously reconstructed in shape and composition to form a solid flocculent material containing Cr, Ti, Hf, and Zr, with most of the Hf and Zr dissolved in the alkaline solution. Because Hf and Zr account for relatively small molar ratios and are uniformly dispersed with Cr and Ti at the atomic scale in the intermetallic compound, a small amount of Hf and Zr is also in situ embedded in the solid flocculent material containing Cr and Ti as atoms or atomic clusters when it forms.

[0542] 4 minutes after the start of the hydrogen evolution and de-Al reaction, 3000 ml of room temperature water was slowly added to the reaction system over 1 minute under vigorous stirring to reduce the concentration of the alkaline solution to below 1.5 mol / L and the temperature of the alkaline solution to below 40° C. During the process of reducing the concentration of the alkaline solution, most of the Hf and Zr originally dissolved in the alkaline solution nucleated and precipitated in the form of solid colloidal flocculent hydrogenation of Zr / Hf and uniformly mixed with the solid flocculent material containing Cr, Ti, Hf, and Zr already generated in the reaction system.

[0543] The solid-liquid separation described above is performed, and all solid flocculent material is collected, washed with dilute acid to a pH of 4-5, and then dried to obtain a composite nano-metal oxide intermediate product in which Ti, Hf, and Zr are compounded, primarily composed of low-crystalline Cr oxide or Cr hydroxide. Its TEM morphology and diffraction spectrum are shown in Figure 17. It can be seen that it is primarily low-crystalline, and its details are primarily composed of flocculent micro-nodules, with a particle size of 0.5nm-5nm. In this composite nano-metal oxide intermediate product, the Ti intermediate product and a small amount of Hf and Zr intermediate products are compounded with the Cr oxide or Cr hydroxide intermediate product through in situ intercalation. This in situ intercalation includes both atomic or atomic cluster-scale compounding and fine-phase-scale compounding.

[0544] The above-mentioned composite nano-metal oxide intermediate product is heat-treated at 1100°C for 2h to obtain a crystalline composite nano-metal oxide mainly composed of nano-chromium oxide and in which Ti, Hf and Zr oxides participate in the composite; its TEM morphology is shown in Figure 18; it can be seen from the figure that although the heat treatment temperature is as high as 1100°C, a loosely sintered and agglomerated composite nano-metal oxide can still be obtained, and its particle size range is 30nm-150nm; although a certain amount of sintering and agglomeration occurs between the particles, this nanoporous structure can be easily crushed and refined through subsequent ball milling and sand milling processes.

[0545] The crystalline composite nano-metal oxide mainly composed of nano-Cr oxide and compounded with the oxides of Ti, Hf and Zr is crushed into crystalline composite nano-metal oxide powder with a particle size of 30nm-150nm by sand grinding.

[0546] The obtained crystalline composite nano-metal oxide powder is mixed and pressed into a green body under a pressure of 50 MPa, and then calcined at 1400°C for 2 hours to obtain a chromium oxide-based refractory material with a molar ratio of Cr:Zr:Hf:Ti of approximately 34:3:1:1, which is composited with Ti, Hf and Zr oxides.

[0547] Example 6

[0548] This embodiment provides a method for preparing a composite nano-metal oxide containing Ti and Mn elements, comprising the following steps:

[0549] According to Zn 67 Ti 28 The nominal ratio of Mn5 (atomic percentage) is to weigh the metal Ti, Mn, and Zn raw materials, and smelt them to obtain a composition of Zn 67 Ti 28 Mn5 alloy melt, then solidifying the alloy melt into an alloy ingot, and crushing the alloy ingot into an initial alloy powder with an average particle size of 50 μm, the phase composition of which mainly consists of Zn2Ti intermetallic compound and Zn-Mn intermetallic compound;

[0550] Under normal pressure, 0.5 g of the initial alloy strip prepared above was reacted with 50 mL of a 1:1 molar ratio of KOH and NaOH solution at 105-115 ° C, and stirred continuously. - The concentration of the alloy powder is 15 mol / L; within 2 minutes, the initial alloy powder and the alkaline solution undergo a violent hydrogen evolution and Zn removal reaction to cause nano-fragmentation, and further undergo shape and composition reconstruction to form a solid flocculent material containing Mn and Ti;

[0551] Four minutes after the start of the hydrogen evolution and Zn removal reaction, the hot alkaline solution containing the solid flocculent material was poured onto a four-layer copper mesh with pore sizes of 1 mm, 200 μm, 20 μm, and 5 μm, respectively, at a 45-degree angle to the horizontal plane. The solid flocculent material was retained on the four-layer copper mesh, and the alkaline solution was filtered out.

[0552] The solid flocculent material containing Mn and Ti was collected, washed with 0.01 mol / L hydrochloric acid to a pH of 4-5, and dried to obtain a composite nano-metal oxide intermediate product mainly composed of nano-titanic acid in which Mn participated. As shown in FIG19 , the intermediate product is mainly in the form of a low-crystallinity film with a thickness of 0.25 nm to 5 nm, and the average area of ​​a single film is greater than 500 nm. 2 Both pure Zn2Ti intermetallic compounds and pure Zn-Mn intermetallic compounds tend to form thin films under these reaction conditions, making it difficult to distinguish Ti-containing intermediates from Mn-containing intermediates by TEM morphology and contrast. Given that the Ti and Mn-containing intermediates form simultaneously, they must have a certain degree of in situ intercalation between them, including in situ intercalation at the atomic or atomic cluster scale.

[0553] The composite nano-metal oxide intermediate product mainly composed of nano-titanic acid in which Mn participates in the composite is heat-treated at 900°C for 1.5 hours to convert the nano-titanic acid film into nano-TiO2 sheets, thereby obtaining a composite nano-metal oxide composed of crystalline nano-manganese oxide and red stone nano-TiO2 sheets, wherein the thickness of the nano-TiO2 sheets is 3nm to 20nm and the average area is greater than 150nm. 2 The particle size of the crystalline nano-manganese oxide is 3 nm to 20 nm; and the main composite mode of the crystalline nano-manganese oxide and the rutile nano-TiO2 sheet includes in-situ embedded composite.

[0554] Example 7

[0555] This embodiment provides a composite nano-metal oxide containing Cr and Ti elements and a preparation method thereof, comprising the following steps:

[0556] According to Al 61 Cr 35 The nominal formula of Ti4 (atomic percentage) is obtained by smelting Al, Cr and Ti raw materials, with the main component being Al 61 Cr 35 The alloy melt of Ti4 is prepared into a 20μm to 30μm thick alloy by a copper roller strip solidification method. The main components are Al 61 Cr 35 The solidified structure of the initial alloy strip of Ti4 is mainly composed of Al8Cr5(Ti) intermetallic compound with Ti dissolved in it.

[0557] At normal pressure, Al 61 Cr 35 The Ti4 alloy strips were reacted with NaOH aqueous solution and treated with 40kHz ultrasonic wave. The concentration of NaOH solution was 15mol / L, the temperature was 60℃, and the volume of NaOH solution was Al 61 Cr 35 The volume of the Ti4 initial alloy ribbon is about 100 times; Al 61 Cr 35 The reaction rate of the Ti4 initial alloy strips with the NaOH solution was greater than 2 μm / min. Within 8 minutes, the hydrogen evolution de-Al reaction was completed. The initial alloy was nano-fragmented by the hydrogen evolution de-Al reaction and simultaneously reconstructed in shape and composition to form a solid flocculent intermediate product.

[0558] Ten minutes after the start of the hydrogen evolution and Zn removal reaction, the solid gel-like intermediate product is separated from the solution, pickled with 0.01 mol / L hydrochloric acid to a pH of 4-5, and dried to obtain a composite nano-metal oxide intermediate product mainly composed of low-crystalline nano-chromium hydroxide or nano-chromium oxide with Ti participating in the composite. The composite nano-metal oxide intermediate product has a gel-like morphology and a particle size of the flocculent microstructure of 0.5 nm to 10 nm. Since the Ti content in the initial alloy is relatively low compared to the Cr content, the Ti-containing intermediate product does not appear in the form of titanate or titanate film, but is mainly present in the low-crystalline nano-chromium hydroxide or nano-chromium oxide intermediate product through in-situ embedded composite.

[0559] The composite nano-metal oxide intermediate product mainly composed of low-crystalline nano-hydroxylated chromium or nano-oxidized chromium in which Ti participates in the composite is heat-treated at 1000°C for 2 hours, and the low-crystalline nano-hydroxylated chromium or nano-oxidized chromium is converted into crystalline oxidized chromium particles with a particle size of 3nm-150nm; at the same time, the Ti-containing component mainly exists in the crystalline oxidized chromium through in-situ embedded composite.

[0560] Example 8

[0561] This embodiment provides a method for preparing a composite nano-metal oxide containing Ti and Ta elements, comprising the following steps:

[0562] According to Al 74 Ti 21 The nominal ratio of Ta5 (atomic percentage) is to weigh the metal Ti, Ta, and Al raw materials, and smelt them to obtain a composition of Al 74 Ti 21The alloy melt is then prepared into an initial alloy strip with a thickness of 25 μm by a copper roller strip solidification method, and its phase composition is mainly composed of Al3Ti(Ta) intermetallic compound with Ta element solid solution.

[0563] At room temperature and pressure, 0.5 g of the initial alloy strip prepared above was mixed with 50 mL of a 10 mol / L, room-temperature NaOH aqueous solution. The mixed alkaline solution and the solid matter in the alkaline solution were then placed directly into a sealed reactor lined with polytetrafluoroethylene. The temperature of the sealed reactor and its interior was raised to 200°C within 10 minutes and maintained at this temperature for 30 minutes.

[0564] After holding the temperature for 30 minutes, the reactor is cooled to room temperature, the pressure in the reactor is restored to normal pressure, and the solid matter in the reactor is separated from the solution, washed with dilute acid to a pH of 4-5, and then dried to obtain a composite nano-metal oxide intermediate product composed of a Ta-containing intermediate product and a titanate nanotube intermediate product; the composite nano-metal oxide intermediate product is in a partially crystalline state; wherein the outer diameter of the titanate nanotube intermediate product is in a range of 5nm to 15nm and the major diameter is greater than 5; the Ta-containing intermediate product is mainly nano-tantalum oxide with a particle size in a range of 3nm to 50nm; the composite method between the titanate nanotube and the nano-tantalum oxide includes in-situ embedded composite, and the composite nano-metal oxide intermediate product does not contain a three-dimensional continuous network nanoporous structure or a porous skeleton structure;

[0565] The composite nanometal oxide intermediate product composed of the Ta-containing intermediate product and the titanate nanotube intermediate product is heat-treated at 1000°C for 2 hours to obtain a composite nanometal oxide composed of crystalline nanotantalum oxide and rutile crystalline TiO2 rods. The rutile crystalline TiO2 rods have an outer diameter ranging from 6nm to 25nm and a major diameter greater than 3 nm. The crystalline nanotantalum oxide has a particle size ranging from 3nm to 50nm. The composite nanometal oxide is formed by in-situ intercalation of the rutile crystalline TiO2 rods and the nanotantalum oxide.

[0566] Example 9:

[0567] This embodiment provides a method for preparing a composite nano-metal oxide containing Nb, Zr, Hf, and Ti elements and containing titanate nanotubes, comprising the following steps:

[0568] Zn 75 The nominal ratio of Ti5Hf5Zr5Nb5Mn5 (atomic percentage) is weighed. Gold Zr, Hf, Ti, Nb, Mn, Zn raw materials are smelted to obtain a composition of Zn 75An alloy melt of Ti5Hf5Zr5Nb5Mn5 is prepared, and then the alloy melt is prepared into an initial alloy strip with a thickness of ~25μm by a copper roller strip rapid solidification method, whose phase composition is mainly composed of intermetallic compounds of Zn and Zr, Hf, Ti, Nb, and Mn.

[0569] At room temperature and pressure, 0.5g of the above-prepared Zn 75 The Ti5Hf5Zr5Nb5Mn5 alloy strip was mixed with 50 mL of a 15 mol / L, room-temperature KOH aqueous solution. The mixed alkaline solution and the solid matter in the alkaline solution were then placed in a sealed reactor lined with polytetrafluoroethylene. The temperature of the sealed reactor and its interior was raised to 250°C within 10 minutes and maintained at this temperature for 1 hour.

[0570] After keeping the temperature for 1 hour, the reactor is cooled to room temperature, and the pressure in the reactor is restored to normal pressure. Then, the alkaline solution in the reaction system in the reactor is diluted to less than 1 mol / L by adding water, and the mixture is separated into solid and liquid, washed with dilute acid to a pH of 4-5, and dried to obtain a composite nano-metal oxide intermediate product containing elements such as Zr, Hf, Ti, Nb, and Mn. The intermediate product has an average particle size of less than 200 nm, is partially crystalline, and has an average crystallinity of more than 20%. Among them, the composite method between the Ti-containing intermediate product, the Nb-containing intermediate product, the Mn-containing intermediate product, and a small number of Zr / Hf-containing intermediate products includes in-situ intercalation composite. The composite between the Zr / Hf-containing intermediate product precipitated during the dilution of the alkali solution and the solid intermediate product precipitated earlier is mainly physical adsorption composite.

[0571] The composite nano-metal oxide intermediate product containing elements such as Zr, Hf, Ti, Nb, and Mn is heat-treated at 1000°C for 2h to obtain a completely crystalline composite nano-metal oxide composited by oxides of elements such as Zr, Hf, Ti, Nb, and Mn. The molar ratio between the components corresponding to different metal elements is approximately an equimolar ratio, and the manner in which the components corresponding to different metal elements are composited includes in-situ embedded composite, which includes in-situ embedded composite at the atomic or atomic cluster scale or in-situ embedded composite at the fine phase scale.

[0572] This approach eliminates the need to prepare the oxides of these metal elements separately and then mix them. Instead, the ratios of the individual metals can be determined during alloy design. This ratio allows the calculation of the corresponding oxide content for each metal. Subsequent hydrogen evolution and de-tantalum removal, along with subsequent treatment, yields a partially crystallized composite nanometal oxide intermediate composed of the oxides of elements such as Zr, Hf, Ti, Nb, and Mn. This preparation process involves in-situ intercalation at the atomic / atomic cluster or fine-phase scale. Further heat treatment yields a fully complex multi-component composite nanometal oxide.

[0573] Example 10

[0574] This embodiment provides a composite nano-metal oxide containing Cr and Ti elements and a preparation method thereof, comprising the following steps:

[0575] According to Al 61 Cr 35 The nominal formula of Ti4 (atomic percentage) is obtained by smelting Al, Cr and Ti raw materials, with the main component being Al 61 Cr 35 The alloy melt of Ti4 is prepared into a 20μm to 30μm thick alloy by a copper roller strip solidification method. The main components are Al 61 Cr 35 The solidified structure of the initial alloy strip of Ti4 is mainly composed of Al8Cr5(Ti) intermetallic compound with Ti dissolved in it.

[0576] Under normal pressure, 0.5g of the Al 61 Cr 35 The Ti4 initial alloy strips and 50 ml of 10 mol / L NaOH aqueous solution were placed in a sealed container. Initially, the initial alloy strips were not in contact with the alkaline solution.

[0577] The temperature in the sealed container, as well as the temperature of the initial alloy strip and the alkaline solution, is raised to 150°C. At this time, the sealed container is in a high pressure state. Then, the Al 61 Cr 35 The Ti4 initial alloy strip is mixed with the alkaline solution at this temperature to cause a violent hydrogen evolution and de-T reaction. 61 Cr 35 The Ti4 initial alloy strips are nano-fragmented through violent hydrogen evolution and de-Al reaction during the high temperature and high pressure reaction, and are simultaneously reconstructed in shape and composition to form solid flocculent products.

[0578] The hydrogen evolution and Al removal reaction was completed within 10 seconds. After 10 seconds, the sealed container and the reaction system were placed in cooling water and quickly cooled to near room temperature. At the same time, the pressure in the sealed container was reduced to normal pressure.

[0579] After the temperature of the reaction system is lowered to room temperature and pressure, the solid flocculent product is separated from the alkaline solution, pickled with 0.01 mol / L hydrochloric acid to a pH of 4-5, and dried to obtain a composite nano-metal oxide intermediate product mainly composed of low-crystalline nano-chromium hydroxide or nano-chromium oxide in which Ti participates in the composite. The composite nano-metal oxide intermediate product has a gel-like morphology and a flocculent microstructure with a particle size of 0.5 nm to 25 nm. Since the Ti content in the initial alloy is relatively low relative to the Cr content, the Ti-containing intermediate product does not appear in the form of a titanate or titanate film, but is mainly present in the low-crystalline nano-chromium hydroxide or nano-chromium oxide intermediate product through an in-situ embedded composite method.

[0580] Comparative Example 1

[0581] According to Al 74 Ti 21 The ratio of Nb5 (atomic percentage) is to weigh the metal Ti, Nb, and Al raw materials, and smelt them to obtain Al 74 Ti 21 The alloy melt is solidified into an ingot, and then crushed into an initial alloy powder with an average particle size of about 25 μm, the phase composition of which is mainly composed of (NbTi)Al3 intermetallic compound with Nb element solid dissolved.

[0582] Under normal pressure, 0.5 g of the initial alloy powder prepared above was mixed with 50 mL of a 10 mol / L NaOH aqueous solution at 25° C. and reacted for 2 h. The SEM morphology of the obtained product is shown in FIG20 .

[0583] As can be seen, under these reaction conditions, the shape of the original alloy powder before and after the reaction remains largely unchanged, remaining as the original crushed, angular powder particles. Furthermore, its microstructure undergoes no nano-fragmentation, nor does it produce a large amount of dispersed nano-oxide powder. Instead, it produces coarse powder particles composed of a nanoporous network structure that retains its original angular shape. The particle size remains comparable to that of the original alloy powder, on the order of several microns or tens of microns. Therefore, the reaction between the initial alloy and the alkaline solution at a lower temperature is completely different from the reaction of the present invention at a higher temperature, preferably near the boiling point, and the product morphology is also completely different.

[0584] Comparative Example 2

[0585] This comparative example provides a method for preparing nano ZrO2 powder, comprising the following steps:

[0586] According to Al 75 Zr 25 (atomic percentage) of the nominal ratio of gold Al, Zr raw materials were weighed, and the main components were Al 75 Zr 25The alloy melt is then solidified into an alloy ingot, which is then crushed into initial alloy powder with an average particle size of 100 μm, the solidification microstructure of which is mainly composed of ZrAl3 intermetallic compounds.

[0587] At normal pressure, 4g of Al 75 Zr 25 The initial alloy powder reacts with a NaOH aqueous solution with continuous stirring; wherein the concentration of the NaOH solution is 12 mol / L, the temperature is its boiling point at normal pressure (~128°C), and the volume of the NaOH solution is 300 ml; within 2 minutes, the hydrogen evolution and Al removal reaction is completed, and an almost colorless and transparent intermediate solution is obtained.

[0588] 3 minutes after the start of the hydrogen evolution de-Al reaction, 3000 ml of room temperature water was slowly added to the reaction system over 1 minute under vigorous stirring to reduce the concentration of the alkaline solution to below 2 mol / L and the temperature of the alkaline solution to below 40° C. During the process of reducing the concentration of the alkaline solution, the Zr element originally dissolved in the alkaline solution nucleated and precipitated in the form of solid colloidal flocculent Zr hydroxide.

[0589] The solid flocculent material is separated from the intermediate solution, and the residual alkali adsorbed by the solid flocculent material is neutralized and cleaned with a 0.01 mol / L dilute hydrochloric acid solution to a pH of 4-5. After drying, low-crystallinity nano-zirconium hydroxide is obtained, and its TEM morphology and diffraction spectrum are shown in Figures 21-22; it can be seen that it is mainly in a low-crystalline state, and the morphology is mainly gel-like, and the particle size of the flocculent microstructure is 0.5nm-5nm.

[0590] The above-mentioned low-crystallinity nano-Zr hydroxide was heat-treated at 600°C for 2h to obtain obviously crystallized nano-ZrO2, and its TEM morphology photographs and diffraction spectra are shown in Figures 23-24; it can be seen that Figure 23 shows clearer layered diffraction rings, and the original fuzzy flocculent morphology boundary in Figure 22 under the high-magnification TEM morphology in Figure 24 has become a clear white bright morphology boundary.

[0591] The low-crystallinity nano-zirconium hydroxide was heat-treated at 900°C for 2 hours to obtain crystalline nano-zirconium oxide (ZrO2). The TEM images and diffraction spectra are shown in Figures 25-26. Although the resulting crystalline nano-zirconium oxide (ZrO2) is polycrystalline, it sinters and agglomerates into large, solid particles, completely losing their porosity and exhibiting a low specific surface area. Consequently, this structure is difficult to fragment and refine through subsequent ball and sand milling processes.

[0592] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0593] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing composite nano-metal oxides, characterized in that: The steps include: Step 1: providing an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A-type elements. x T y , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds; Step 2: The initial alloy undergoes a hydrogen evolution and de-tantalum reaction with an alkaline solution, and by controlling the temperature T1 and concentration C1 of the alkaline solution, the reaction interface is advanced inward from the surface of the initial alloy at an average rate of not less than 2 μm / min during the reaction; When the initial alloy does not contain D-type sub-elements, the initial alloy and the alkaline solution undergo nano-fragmentation through hydrogen evolution and de-Ti reaction, and the shape and composition are reconstructed to generate a solid material containing M and Ti, the size of at least one dimension of which does not exceed 500 nm in the three-dimensional direction; When the initial alloy contains a D-type daughter element, the initial alloy and the alkaline solution undergo nano-fragmentation through a hydrogen evolution and de-Ti reaction, and undergo shape and composition reconstruction to generate a solid material containing M or (and) Ti, the shape of which has at least one dimension in the three-dimensional direction not exceeding 500 nm. At the same time, the D-type daughter element is mainly dissolved in the alkaline solution under conditions of an alkali concentration and temperature corresponding to a high reaction rate, or is mainly converted into a solid material containing D through shape and composition reconstruction under conditions of an alkali concentration and temperature corresponding to a relatively low reaction rate. Step 3: After the hydrogen evolution and de-T reaction is completed, When the initial alloy does not contain D-type sub-elements, the solid matter containing M and Ti in the reaction system is collected to obtain a composite nano-metal oxide intermediate product containing M and Ti, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the composite method of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedded composite; wherein the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can be corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements, and the D-type sub-elements are mainly present in the form of D-containing solid substances, all solid substances in the reaction system are collected to obtain a composite nano-metal oxide intermediate product composed of a D-containing intermediate product and an M-containing or (and) Ti-containing intermediate product, wherein the size of at least one dimension in the three-dimensional direction does not exceed 500 nm; and the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product are composited with each other in a manner including in-situ embedded composite; wherein the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or can be corresponding phases, and at least one of the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements and the D-type sub-elements are mainly dissolved in the alkali solution, a liquid is added to the reaction system described in Step 2 to reduce the concentration of the alkali solution to below the concentration C2 at which solid flocculent hydroxide D can precipitate. The precipitated solid flocculent hydroxide D is mixed with the previously formed solid substance containing M or (and) Ti. All solid substances are collected to obtain a composite nano-metal oxide intermediate composed of nano-hydroxide D and an intermediate containing M or (and) Ti, and at least one dimension of its shape does not exceed 500 nm in the three-dimensional direction; wherein, C2 < C1, and when the composite nano-metal oxide intermediate simultaneously includes an intermediate containing M and an intermediate containing Ti, the composite manner of the intermediate containing M and the intermediate containing Ti includes in-situ intergrowth composite; wherein, the intermediate containing M and the intermediate containing Ti can be the corresponding atoms or atomic clusters, or the corresponding phases, and at least one of the intermediate containing M and the intermediate containing Ti is a phase; Step 4, heat-treat the composite nano-metal oxide intermediate described in Step 3 to obtain a composite nano-metal oxide with improved crystallization degree; it contains at least two of the three types of sub-elements: element Ti, M-type sub-elements, and D-type sub-elements; and at least two of the three types of sub-elements of Ti element, M-type sub-elements, and D-type sub-elements are subjected to hetero-element corresponding oxide composite at the atomic / atomic cluster scale or the scale of fine phases.

2. A method for preparing a composite nano-metal oxide intermediate product, characterized in that: It includes the following steps: Step 1, providing an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A x T y , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds; Step 2, perform a hydrogen evolution and T-removal reaction on the initial alloy and the alkali solution. By controlling the temperature T1 and concentration C1 of the alkali solution, the reaction interface advances inward from the surface of the initial alloy at an average rate of not less than 2 μm / min during the reaction process; When the initial alloy does not contain D-type sub-elements, the initial alloy and the alkali solution undergo nano-fragmentation through the hydrogen evolution and T-removal reaction, and are subjected to shape and composition reconstruction to generate a solid substance containing M and Ti with at least one dimension of its shape not exceeding 500 nm in the three-dimensional direction; When the initial alloy contains D-type sub-elements, the initial alloy and the alkali solution undergo nano-fragmentation through the hydrogen evolution and T-removal reaction, and are subjected to shape and composition reconstruction to generate a solid substance containing M or (and) Ti with at least one dimension of its shape not exceeding 500 nm in the three-dimensional direction; meanwhile, the D-type sub-elements are mainly dissolved in the alkali solution under the alkali concentration and temperature corresponding to a high reaction rate, or mainly generate a solid substance containing D through shape and composition reconstruction under the alkali concentration and temperature corresponding to a relatively low reaction rate; Step 3, after the hydrogen evolution and T-removal reaction ends, When the initial alloy does not contain D-type sub-elements, the solid substances containing M and Ti in the reaction system are collected to obtain a composite nano metal oxide intermediate product containing M and Ti, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; and the composite manner of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedding composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements and the D-type sub-elements mainly exist in the form of D-containing solid substances, all the solid substances in the reaction system are collected to obtain a composite nano metal oxide intermediate product composed of a D-containing intermediate product and an M-containing or (and) Ti-containing intermediate product, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; and the composite manner among the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product includes in-situ embedding composite; wherein, the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the D-containing intermediate product, the M-containing intermediate product, and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements and the D-type sub-elements are mainly dissolved in the alkali solution, the liquid is added to the reaction system described in step two to reduce the concentration of the alkali solution to below the concentration C2 at which solid flocculent D hydroxide can precipitate. The precipitated solid flocculent D hydroxide is mixed with the previously formed solid substances containing M or (and) Ti, and all the solid substances are collected to obtain a composite nano metal oxide intermediate product composed of nano D hydroxide and an M-containing or (and) Ti-containing intermediate product, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; wherein, C2 < C1, and when the composite nano metal oxide intermediate product simultaneously includes an M-containing intermediate product and a Ti-containing intermediate product, the composite manner of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedding composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase.

3. A method for preparing composite nano-metal oxides, characterized in that: Comprising the following steps: Step (1) provides an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A-type elements. x T y , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds; Step (2), mixing the initial alloy with an alkaline solution having a temperature of T1 and a concentration of C1; wherein T s溶液 <T1≤T f溶液 , T f溶液 T is the boiling point of the alkaline solution involved in the reaction under normal pressure; s溶液 is the freezing point temperature of the alkaline solution participating in the reaction under normal pressure; Step (3), mixing the solid substance obtained in step (2) with an alkaline solution having a concentration of C2, and then placing the mixture in a sealed container, and then treating it at a temperature T2 higher than normal pressure for a period of time, wherein T2>T f溶液 ; Step (4), after cooling and depressurizing, When the initial alloy does not contain D-type sub-elements, the solid substances in the reaction system are collected to obtain a composite nano metal oxide intermediate product containing M and Ti, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; and the composite manner of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ embedding composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements, a liquid is added to the reaction system after cooling and depressurizing, so that the concentration C3 of the diluted alkali solution is less than 3 mol / L. All solid substances are collected to obtain a composite nano-metal oxide intermediate product composed of D-containing solid substances and M-containing or (and) Ti-containing solid substances, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; wherein, C3 < C2, and when the composite nano-metal oxide intermediate product simultaneously includes an M-containing intermediate product and a Ti-containing intermediate product, the composite mode of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intergrowth composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase; Step (5), heat-treat the composite nano-metal oxide intermediate product described in step (4) to obtain a composite nano-metal oxide with improved crystallization degree; it contains at least two of the three types of sub-elements: element Ti, M-type sub-elements, and D-type sub-elements; and at least two of the three types of sub-elements of Ti element, M-type sub-elements, and D-type sub-elements conduct composite of corresponding oxides of different elements at the atomic / atomic cluster scale or the scale of fine phases.

4. A method for preparing a composite nano-metal oxide intermediate product, characterized in that: It includes the following steps: Step 1) providing an initial alloy, wherein the composition of the initial alloy includes T-type elements and A-type elements, wherein the T-type elements include at least one of Al and Zn; the A-type elements include at least two of the three types of sub-elements of element Ti, M-type sub-elements, and D-type sub-elements; wherein the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf; the composition of the initial alloy is mainly A-type elements. x T y , wherein x, y are the atomic percentage contents of the corresponding elements, and 5≤x≤55%, 45%≤y≤95%; the solidified structure of the initial alloy is mainly composed of AT intermetallic compounds; Step 2), mixing the initial alloy with an alkaline solution having a temperature of T1 and a concentration of C1; wherein T s溶液 <T1≤T f溶液 , T f溶液 T is the boiling point of the alkaline solution involved in the reaction under normal pressure; s溶液 is the freezing point temperature of the alkaline solution participating in the reaction under normal pressure; Step 3), the solid substance obtained in step 2) is mixed with an alkaline solution having a concentration of C2, and the mixture is placed in a sealed container, and then treated at a temperature T2 higher than normal pressure for a period of time, wherein T2>T f溶液 ; Step 4), after cooling and depressurizing, When the initial alloy does not contain D-type sub-elements, collect the solid substances in the reaction system to obtain a composite nano-metal oxide intermediate product containing M and Ti, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; and the composite mode of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intergrowth composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase; When the initial alloy contains D-type sub-elements, a liquid is added to the reaction system after cooling and depressurizing, so that the concentration C3 of the diluted alkali solution is less than 3 mol / L. All solid substances are collected to obtain a composite nano-metal oxide intermediate product composed of D-containing solid substances and M-containing or (and) Ti-containing solid substances, and at least one dimension of its shape in the three-dimensional direction does not exceed 500 nm; wherein, C3 < C2; and when the composite nano-metal oxide intermediate product simultaneously includes an M-containing intermediate product and a Ti-containing intermediate product, the composite mode of the M-containing intermediate product and the Ti-containing intermediate product includes in-situ intergrowth composite; wherein, the M-containing intermediate product and the Ti-containing intermediate product can be corresponding atoms or atomic clusters, or corresponding phases, and at least one of the M-containing intermediate product and the Ti-containing intermediate product is a phase.

5. A composite nano-metal oxide, characterized in that: Prepared according to the preparation method described in claim 1, its preparation process and detailed features are as described in claim 1, and its detailed features also include: The composite nano-metal oxide comprises at least two of three types of sub-elements: Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide, at least two of the three types of sub-elements: Ti, M-type sub-elements, and D-type sub-elements are compounded with corresponding oxides of heterogeneous elements at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm; wherein the M-type sub-elements comprise at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements comprise at least one of Zr and Hf.

6. The composite nano-metal oxide according to claim 5, characterized in that: The particle porosity or (and) specific surface area of ​​the composite nano-metal oxide is higher than the particle porosity or (and) specific surface area of ​​the corresponding single nano-metal oxide prepared by a similar process.

7. A composite nano-metal oxide intermediate product, characterized in that: The preparation method according to claim 2, the preparation process and detailed features are as described in claim 2, and the detailed features also include: The composite nano-metal oxide intermediate product contains at least two of the three types of sub-elements, namely, element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide intermediate product, at least two of the three types of sub-elements, namely, Ti, M-type sub-elements, and D-type sub-elements, are compounded with corresponding oxide intermediate products of different types of elements at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; the average particle size of the fine phase is less than 250nm; wherein, the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf.

8. The composite nano-metal oxide intermediate product according to claim 7, characterized in that: The thermal stability or (and) crystallization temperature of the composite nano-metal oxide intermediate product is higher than the thermal stability or (and) crystallization temperature of the corresponding single nano-metal oxide intermediate product prepared by a similar process.

9. A composite nano-metal oxide, characterized in that: The preparation method according to claim 3, the preparation process and detailed features are as described in claim 3, and the detailed features also include: The composite nano-metal oxide comprises at least two of three types of sub-elements: Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide, at least two of the three types of sub-elements: Ti, M-type sub-elements, and D-type sub-elements are compounded with corresponding oxides of heterogeneous elements at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; and the average particle size of the fine phase is less than 250nm; wherein the M-type sub-elements comprise at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements comprise at least one of Zr and Hf.

10. The composite nano-metal oxide according to claim 9, characterized in that: The particle porosity or (and) specific surface area of ​​the composite nano-metal oxide is higher than the particle porosity or (and) specific surface area of ​​the corresponding single nano-metal oxide prepared by a similar process.

11. A composite nano-metal oxide intermediate product, characterized in that: The method according to claim 4 is used for preparation, and its preparation process and detailed features are as described in claim 4, and its detailed features also include: The composite nano-metal oxide intermediate product contains at least two of the three types of sub-elements, namely, element Ti, M-type sub-elements, and D-type sub-elements; and in the composite nano-metal oxide intermediate product, at least two of the three types of sub-elements, namely, Ti, M-type sub-elements, and D-type sub-elements, are compounded with corresponding oxide intermediate products of different types of elements at the atomic / atomic cluster scale or the fine phase scale; wherein the atomic / atomic cluster scale is 0.25nm-2.5nm; the average particle size of the fine phase is less than 250nm; wherein, the M-type sub-elements include at least one of Cr, V, Nb, Ta, W, Mo, Mn, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and the D-type sub-elements include at least one of Zr and Hf.

12. The composite nano-metal oxide intermediate product according to claim 11, characterized in that: The thermal stability or (and) crystallization temperature of the composite nano-metal oxide intermediate product is higher than the thermal stability or (and) crystallization temperature of the corresponding single nano-metal oxide intermediate product prepared by a similar process.

13. Use of the product material prepared by the preparation method according to any one of claims 1 to 4, or the material according to claims 5 to 12, in composite materials, catalytic materials, ceramic materials, refractory materials, advanced electronic materials, battery materials, color-changing materials, absorbing materials, sewage degradation materials, sterilization materials, coatings, pigments, thermal spray materials, and sensors.

14. A method for preparing a composite oxide ceramic, characterized in that: The steps include: Step S1, preparing a uniformly mixed and refined mixed powder, wherein the mixed powder comprises a composite nano-metal oxide or an intermediate product prepared by the preparation method according to any one of claims 1 to 4, and an added powder; wherein the molar percentage content of the composite nano-metal oxide or the intermediate product in the mixed powder is V1, the molar percentage content of the added powder in the mixed powder is V2, and the added powder comprises at least one of Al2O3, CaO, MgO, SiO2, B2O3, and BeO, and 1%≤V1≤100%, and 0≤V2≤99%; Step S2: Pressing the mixed powder into a green body, and calcining it at a high temperature to obtain a composite oxide ceramic material.

15. A composite oxide ceramic, characterized in that: Prepared according to the preparation method of claim 14, its detailed features are described in claim 14.

Images