Spherical-like doped cerium dioxide as well as preparation method and application thereof

Abstract

The invention relates to sphere-like doped cerium dioxide and a preparation method and application thereof.The preparation method comprises the following steps that cerium salt, doped metal salt, a solvent, an acid reagent and a precipitator are mixed and then subjected to a hydrothermal reaction, precipitates are obtained, the precipitates are calcined, and the sphere-like doped cerium dioxide is obtained. The doped metal salt comprises praseodymium salt and / or neodymium salt. According to the preparation method, cerium salt and praseodymium salt and / or neodymium salt serving as doped metal salt serve as raw materials, through the mixing process of the raw materials, the acidic reagent and the precipitant and the design of the reaction process, preparation of sphere-like doped type cerium dioxide is achieved, the doped type cerium dioxide of nano-scale particles is obtained, and in addition, the preparation method has the advantages that the preparation process is simple, and the preparation cost is low. In addition, the preparation method adopted by the invention is simple and convenient in process and short in reaction time, and can be used for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of nano rare earth material preparation, and in particular to spherical doped cerium dioxide and a preparation method and application thereof. Background Art

[0002] As a typical rare earth material, cerium dioxide has the advantages of unique crystal structure, excellent redox ability, high melting point, strong chemical activity, safety, environmental friendliness and semiconductor properties. It can be widely used in polishing process, cosmetics and catalysts, especially as a key component in polishing process. It can be used as the main abrasive in chemical mechanical polishing (CMP) process. In addition, due to its moderate hardness and strong chemical activity, it is widely used in semiconductor manufacturing and precision optical processing. In particular, spherical or spherical cerium dioxide can produce better polishing effect due to its smooth surface and micro-abrasive wear mechanism.

[0003] In addition, the morphology and particle size of ceria will affect its performance, especially the application effect of ceria in the chemical mechanical polishing (CMP) process. The irregular morphology and large deviation of particle size of ceria will lead to poor surface flatness of the polishing material obtained after polishing, and it may even be unsuitable for use in the polishing process.

[0004] At present, cerium dioxide is mainly prepared by solid phase method, liquid phase method or gas phase method. Prior art CN109761261A discloses a method for preparing cerium dioxide, which uses a mixed solvent containing amines and alcohols to absorb carbon dioxide, and prepares a precipitant, precipitates cerium salt to prepare basic cerium carbonate (CeCO3OH), and calcines nano cerium dioxide powder at low temperature. This method is energy-saving, green and environmentally friendly. However, the cerium dioxide powder obtained by this method is in the form of flakes, bouquets and rods, and it is impossible to prepare cerium dioxide with a regular spherical structure.

[0005] Prior art CN102765742A discloses a method for preparing cerium dioxide microspheres, which uses a polyelectrolyte as a morphology control agent, uses a gas phase diffusion method to prepare cerium carbonate, and obtains cerium oxide with a high specific surface area after a roasting heat treatment process. The preparation method is complex, and the uniformity of the morphology and particle size of the obtained cerium dioxide needs to be improved.

[0006] Currently, many studies have shown that the introduction of element doping can obtain cerium dioxide with different morphologies. By introducing doping elements into cerium dioxide, the inherently non-fixed morphology can be transformed into a regular specific morphology. However, there is very little research in the prior art on obtaining spherical cerium dioxide materials with excellent performance through element doping combined with preparation methods.

[0007] Therefore, providing a preparation method with simple process to prepare spherical doped cerium dioxide with regular morphology and good particle size uniformity has become an urgent problem to be solved. Summary of the invention

[0008] In order to solve the above technical problems, the purpose of the present invention is to provide a spherical doped cerium dioxide and its preparation method and application. The present invention uses cerium salt and praseodymium salt and / or neodymium salt as doping metal salt as raw materials, and realizes the preparation of spherical doped cerium dioxide through the mixing process with acidic reagent and precipitant and the design of reaction process combined with the selection of preparation process, and obtains nanometer-level particle doped cerium dioxide, and its morphology is regular and the particle size is uniform, and the preparation method adopted by the present invention is simple in process, short in reaction time, and can be used for mass production.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing spherical doped cerium dioxide, the preparation method comprising the following steps:

[0011] The cerium salt, the doping metal salt, the solvent, the acidic reagent and the precipitant are mixed, and then subjected to a hydrothermal reaction to obtain a precipitate, and the precipitate is calcined to obtain the spherical doped cerium dioxide;

[0012] The doping metal salt includes praseodymium salt and / or neodymium salt.

[0013] The present invention uses cerium salt and praseodymium salt and / or neodymium salt as doping metal salt as raw materials, and realizes the preparation of spherical doped cerium dioxide through the design of a mixing process with an acidic reagent and a precipitant and the selection of a preparation process. The method has a simple preparation process, a short reaction time, and can be used for mass production. The prepared doped cerium dioxide is nanometer-level particles, and the morphology is regular and the particle size is uniform, and the cerium dioxide can be widely used in the fields of semiconductor CMP polishing, high-end optical polishing or cosmetics.

[0014] In the preparation method provided by the present invention, praseodymium salt and / or neodymium salt are directly mixed with cerium salt to introduce doping elements praseodymium and / or neodymium, so that the doping elements praseodymium and / or neodymium in the prepared product can be evenly dispersed in the crystal cells of cerium dioxide, thereby preparing particles with a quasi-spherical morphology. Secondly, the present invention adds an acidic reagent to the mixed solution, which, on the one hand, can fully dissolve the cerium salt and the doping metal salt in the solution; on the other hand, the addition of the acidic reagent can regulate the pH value in the solution and promote the mixed solution to stably crystallize and form crystal nuclei, which is conducive to the formation of nano-scale particles with regular morphology and uniform particle size. Furthermore, the present invention obtains a precipitate by adding a precipitant to the mixed solution in combination with a hydrothermal reaction, and finally prepares a doped cerium dioxide with a quasi-spherical nanostructure with good morphological identity under the conditions of a calcination process.

[0015] Preferably, the mass ratio of the cerium salt to the solvent is 1:(100-200), for example, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0016] Preferably, in the mixed solution, the molar ratio of the cerium element in the cerium salt to the doping metal element in the doping metal salt is (1000-100000):1; for example, 1000:1, 5000:1, 10000:1, 20000:1, 30000:1, 40000:1, 50000:1, 60000:1, 70000:1, 80000:1, 90000:1 or 100000:1, etc.

[0017] The present invention further regulates the molar ratio of the cerium element in the cerium salt and the doping metal element in the doping metal salt in the mixed solution obtained by mixing, so as to regulate the relative addition amounts of the cerium salt and the doping metal salt. If the molar ratio of the two is too small and the addition amount of the doping metal salt is too large, the metal impurities in the final product will increase, the morphology identity of the nanoparticles will decrease, and the performance will decrease. If the total relative molecular weight ratio of the two is too large and the addition amount of the doping metal salt is too small, the particle morphology will be deformed, which is not conducive to the formation of spherical particles and the identity will decrease.

[0018] Preferably, the cerium salt includes any one of cerium nitrate, cerium chloride, cerium hydroxide or cerium sulfate, or a combination of at least two thereof, preferably cerium nitrate.

[0019] Preferably, the praseodymium salt includes any one of praseodymium nitrate, praseodymium chloride or praseodymium sulfate, or a combination of at least two thereof, preferably praseodymium nitrate.

[0020] Preferably, the neodymium salt includes any one of neodymium nitrate, neodymium chloride or neodymium sulfate, or a combination of at least two thereof, preferably neodymium nitrate.

[0021] The invention introduces doping metal salt into cerium salt, which is beneficial to uniform doping of praseodymium and / or neodymium in cerium dioxide crystal cells, and the selection of salt types in the raw materials will also affect the morphology and yield of the obtained doped cerium dioxide.

[0022] Preferably, the doping metal salt comprises praseodymium salt and neodymium salt.

[0023] Preferably, when the doped metal salt includes praseodymium salt and neodymium salt, the molar ratio of the praseodymium element in the praseodymium salt to the neodymium element in the neodymium salt is (1-100):1, for example, 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1 or 100:1, etc.

[0024] As a preferred technical solution of the present invention, the acidic reagent includes a first acidic reagent and a second acidic reagent.

[0025] In the present invention, two different acidic reagents are further used to mix with cerium salt and praseodymium salt. The first acidic reagent is used to promote the full dissolution of cerium salt and doped metal salt praseodymium salt and / or neodymium salt in the mixed solution, so as to ensure the spherical morphology of the obtained doped cerium dioxide, and avoid the presence of undissolved salt substances leading to the generation of impurities in the subsequent process, affecting the yield of the preparation of spherical cerium dioxide; the introduced second acidic reagent, on the one hand, is used to stabilize the acidity in the mixed solution, further prevent the generation of impurities in the mixed solution, and on the other hand, is used to promote the crystallization of the mixed solution to form a crystal nucleus, so as to obtain a spherical doped cerium dioxide with a regular and uniform morphology and a uniform particle size. The present invention, through the synergistic effect between the first acidic reagent and the second acidic reagent, can effectively improve the morphological identity and particle size uniformity of the obtained doped cerium dioxide while ensuring the successful preparation of spherical doped cerium dioxide.

[0026] Preferably, the first acidic reagent comprises nitric acid.

[0027] Preferably, the second acidic reagent includes any one of acetic anhydride, acetic acid, phosphoric acid, formic acid or n-butyric acid.

[0028] Optionally, the acidic reagents used in the present invention are all commercially available, wherein the nitric acid is commercially available concentrated nitric acid.

[0029] Preferably, the volume ratio of the first acidic reagent to the second acidic reagent is 1:(0.4-0.8), such as 1:0.4, 1:0.5, 1:0.6, 1:0.7 or 1:0.8, etc.

[0030] The present invention regulates the volume ratio of the first acidic reagent and the second acidic reagent. If the volume ratio of the two is too small and the content of the first acidic reagent is low, the cerium salt and the doped metal salt will not be fully dissolved and the reaction will not start normally. If the volume ratio of the two is too large and the content of the second acidic reagent is low, the morphology of the cerium dioxide particles will be deformed, there will be too many impurities, and the reaction will go wrong, thereby affecting the yield of spherical cerium dioxide.

[0031] Preferably, the volume ratio of the first acidic reagent to the solvent is 1:(50-140), for example, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1:110, 1:120, 1:130 or 1:140, etc.

[0032] Preferably, the precipitant includes a first precipitant and / or a second precipitant.

[0033] Preferably, the precipitant comprises a first precipitant and a second precipitant.

[0034] Preferably, when the precipitant includes a first precipitant and a second precipitant, the precipitant is added by a one-step addition method or a step-by-step addition method.

[0035] Preferably, when the precipitant is added in a one-step method, the hydrothermal reaction is a one-stage hydrothermal reaction.

[0036] Preferably, the specific process of the one-stage hydrothermal reaction includes: mixing a cerium salt, a doped metal salt, a solvent and an acidic reagent to obtain a first mixture, mixing the first mixture with a first precipitant and a second precipitant to obtain a second mixture, and subjecting the second mixture to a hydrothermal reaction to obtain a precipitate.

[0037] Preferably, the temperature of the primary hydrothermal reaction is 100-300°C, for example, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 260°C, 280°C or 300°C, etc.

[0038] Preferably, the time of the primary hydrothermal reaction is 1-12 h, for example, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0039] As a preferred technical solution of the present invention, when the precipitant is added in steps, the hydrothermal reaction is a staged hydrothermal reaction.

[0040] Preferably, the staged hydrothermal reaction includes a first hydrothermal reaction and a second hydrothermal reaction.

[0041] Preferably, the specific process of the first hydrothermal reaction includes: mixing a cerium salt, a doped metal salt, a solvent and an acidic reagent to obtain a first mixture, mixing the first mixture with a first precipitant to obtain a third mixture, and subjecting the third mixture to a first hydrothermal reaction.

[0042] Preferably, the specific process of the second hydrothermal reaction includes: mixing the second precipitant with the product after the first hydrothermal reaction to obtain a fourth mixture, and performing a second hydrothermal reaction on the fourth mixture to obtain the precipitate.

[0043] The present invention further preferably adopts a segmented hydrothermal reaction, that is, the first precipitant and the second precipitant are separately added to the mixed solution and then the hydrothermal reaction is carried out separately. This is because if the first precipitant and the second precipitant are added at the same time, under the conditions of the hydrothermal reaction, the reaction between the substances will be too intense, affecting the morphology and particle size of the obtained doped cerium dioxide, thereby causing the yield of spherical products to decrease and the uniformity of particle size to deteriorate. The present invention adds different types of precipitants to the mixture step by step through a segmented hydrothermal reaction, which can effectively control the reaction process, control the morphology and size of the particles, and further improve the yield of the obtained spherical cerium dioxide and the uniformity of particle size.

[0044] Preferably, the temperatures of the first hydrothermal reaction and the second hydrothermal reaction are independently selected from 100-300°C, such as 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 260°C, 280°C or 300°C, etc.

[0045] Preferably, the time of the first hydrothermal reaction and the second hydrothermal reaction is independently selected from 1-12 h, such as 1 h, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h, etc.

[0046] Preferably, the hydrothermal reaction is followed by a cooling and separation process.

[0047] In the present invention, there is no specific limitation on the separation method, including but not limited to centrifugation, filtration or sedimentation, etc. Those skilled in the art can select according to their needs.

[0048] The first precipitant and the second precipitant are independently selected from any one of urea, ammonia water, ammonium phosphate, ammonium nitrate or ammonium sulfate.

[0049] Preferably, the first precipitating agent comprises urea.

[0050] Preferably, the second precipitant includes any one of ammonia water, ammonium nitrate, ammonium phosphate or ammonium sulfate.

[0051] Preferably, the mass ratio of the solvent in the first mixture to the first precipitant is (50-100):4, such as 50:4, 60:4, 70:4, 80:4, 90:4 or 100:4.

[0052] In the mixed solution of the present invention, if too little of the first precipitant is added, the reaction will be too slow, affecting the yield of spherical nanoparticles; if too much of the first precipitant is added, the identity of the particle morphology and the uniformity of the particle size will be affected.

[0053] Preferably, the concentration of the second precipitant is 1-50wt%, for example 1wt%, 3wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, etc.

[0054] Preferably, the pH of the mixture after adding the precipitant is 7.5-11.0, such as 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5 or 11.0.

[0055] In the present invention, the amount of the second precipitant added is such that the pH of the mixture after the precipitant is added is within the above preferred range, so as to effectively promote the formation of spherical doped cerium dioxide and ensure the uniformity of the morphology and the identity of the particle size of the obtained product.

[0056] In the present invention, if the amount of precipitant added is too small, resulting in the pH of the mixture with the precipitant being too low, the reaction is insufficient and the yield of spherical cerium dioxide is reduced; if the amount of precipitant added is too large, resulting in the pH of the mixed product being too high, the particle morphology and particle size are affected.

[0057] As a preferred technical solution of the present invention, the specific mixing process for preparing the first mixture includes: mixing the cerium salt with a solvent, adding a doping metal salt and continuing to mix, and then sequentially adding a first acidic reagent and a second acidic reagent and mixing to obtain the first mixture.

[0058] In the present invention, there is no specific limitation on the mixing method, including but not limited to stirring, ultrasound or ball milling, etc., and those skilled in the art can select it according to needs.

[0059] The mixed solution of the present invention improves the doping uniformity of the doping elements by designing a specific mixing process, which is conducive to obtaining spherical materials with good morphology, and the distributed mixing can promote the particle size uniformity of the obtained product to obtain nanoparticles of uniform size.

[0060] Preferably, the calcination temperature is 600-1300°C, for example, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C or 1300°C.

[0061] Preferably, the calcination time is 1-24 h, for example, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h, etc.

[0062] As a further preferred technical solution of the present invention, the preparation method comprises the following steps:

[0063] (1) mixing a cerium salt and a solvent in a mass ratio of 1:(100-200), adding a doping metal salt in a molar ratio of the cerium element in the cerium salt to the doping metal element in the doping metal salt in a ratio of (1000-100000):1, mixing until the solution becomes clear and transparent, and then sequentially adding a first acidic reagent and a second acidic reagent and continuing to mix until the solution becomes clear and transparent, to obtain a first mixture;

[0064] Wherein, in the first mixture, the doping metal salt includes praseodymium salt and / or neodymium salt, the volume ratio of the first acidic reagent to the second acidic reagent is 1:(0.4-0.8), and the volume ratio of the first acidic reagent to the solvent is 1:(50-140);

[0065] (2) mixing the first mixture and the first precipitant according to a mass ratio of the solvent in the first mixture to the first precipitant of (50-100):4 to obtain a third mixture, subjecting the third mixture to a first hydrothermal reaction for 1-12 h at a temperature of 100-300° C., then adding a second precipitant at a concentration of 1-50 wt % to the product obtained by the first hydrothermal reaction until the pH of the mixture is 7.5-11.0 to obtain a fourth mixture, subjecting the fourth mixture to a second hydrothermal reaction for 1-12 h at a temperature of 100-300° C., cooling and separating to obtain a precipitate;

[0066] Wherein, the first precipitant includes urea, and the second precipitant includes any one of ammonia water, ammonium nitrate, ammonium phosphate or ammonium sulfate;

[0067] (3) calcining the precipitate at a temperature of 600-1300° C. for 1-24 hours to obtain the spherical doped cerium dioxide.

[0068] In a second aspect, the present invention provides a quasi-spherical doped cerium dioxide, wherein the quasi-spherical doped cerium dioxide is prepared by the preparation method described in the first aspect, and the doping elements in the doped cerium dioxide include praseodymium and / or neodymium.

[0069] The invention provides a method of uniformly distributing doping elements of praseodymium and / or neodymium in the crystal cells of cerium dioxide to obtain spherical doped cerium dioxide with a nanometer-level particle size and the advantages of having a regular and uniform morphology and size.

[0070] The purity of the spherical doped cerium dioxide provided by the present invention can reach above 5N level, and the crystallinity can reach above 95%.

[0071] Preferably, the molar ratio of cerium element to doping element in the doped cerium dioxide is (1000-100000):1.

[0072] Preferably, the average particle size of the doped cerium dioxide is 20-300 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm or 300 nm, etc., preferably 20-100 nm.

[0073] Preferably, the doping elements of the doped cerium dioxide include praseodymium and neodymium.

[0074] Preferably, the molar ratio of the praseodymium to the neodymium is (1-100):1, for example 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1 or 100:1, etc.

[0075] In a third aspect, the present invention provides an application of the quasi-spherical doped cerium dioxide as described in the second aspect, wherein the quasi-spherical doped cerium dioxide is applied in semiconductor polishing, optical polishing or cosmetics.

[0076] The spherical doped cerium dioxide provided by the present invention can be applied to any application field that can be thought of by those skilled in the art.

[0077] Compared with the prior art, the present invention has at least the following beneficial effects:

[0078] (1) The present invention uses cerium salt and praseodymium salt and / or neodymium salt as doping metal salt as raw materials, and realizes the preparation of spherical doped cerium dioxide by mixing with an acidic reagent and a precipitant and designing the reaction process in combination with the selection of the preparation process. The method has a simple preparation process, a short reaction time, and can be used for mass production. The prepared doped cerium dioxide is nano-scale particles, and its morphology is regular and uniform and the particle size is uniform, and it can be widely used in the fields of semiconductor CMP polishing, high-end optical polishing or cosmetics.

[0079] (2) The present invention further preferably adopts a segmented hydrothermal reaction, that is, the first precipitant and the second precipitant are separately added to the mixed solution and then the hydrothermal reaction is carried out separately. This is because if the first precipitant and the second precipitant are added at the same time and under the conditions of the hydrothermal reaction, the reaction between the substances will be too intense, affecting the morphology and particle size of the obtained doped cerium dioxide, thereby causing the yield of quasi-spherical products to decrease and the uniformity of particle size to deteriorate. The present invention adds different types of precipitants to the mixture step by step through a segmented hydrothermal reaction, which can effectively control the reaction process, control the morphology and size of the particles, and further improve the yield of the obtained quasi-spherical cerium dioxide and the uniformity of particle size.

[0080] (3) The present invention provides that the doping elements praseodymium and / or neodymium are uniformly distributed in the crystal cells of ceria to obtain spherical doped ceria with a particle size of nanometer level and the advantages of regular morphology and uniform size. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a scanning electron microscope image of the spherical doped cerium dioxide provided in Example 1. DETAILED DESCRIPTION

[0082] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0083] The concentration of nitric acid used in the following examples is 65wt%; the concentration of acetic acid is 36wt%; and the concentration of phosphoric acid is 85wt%.

[0084] Example 1

[0085] This embodiment provides a method for preparing spherical praseodymium-doped cerium dioxide, and the specific steps are as follows:

[0086] (1) stirring and mixing cerium nitrate and deionized water in a mass ratio of 1:150, then adding praseodymium nitrate in a molar ratio of cerium element in cerium nitrate to praseodymium element in praseodymium nitrate of 10000:1, and continuing to stir until the solution becomes clear and transparent, then, in the stirring process, sequentially adding nitric acid and acetic anhydride, and continuing to stir until the solution becomes clear and transparent again, to obtain a first mixture; wherein the volume ratio of nitric acid and acetic anhydride added to the solution is 1:0.5, and the volume ratio of nitric acid to deionized water is 1:120;

[0087] (2) mixing the first mixture and urea at a mass ratio of deionized water to urea in the first mixture of 20:1 to obtain a second mixture, subjecting the second mixture to a first hydrothermal reaction at 200° C. for 6 h, then adding 25 wt % ammonia water to the product obtained by the first hydrothermal reaction until the pH of the mixture is 9 to obtain a third mixture, subjecting the third mixture to a second hydrothermal reaction at 200° C. for 6 h, then cooling the obtained product to 30° C., centrifuging at 5000 rpm for 2 h, and taking a solid to obtain a precipitate;

[0088] (3) calcining the precipitate obtained in step (2) at 1000° C. for 12 h to obtain spherical praseodymium-doped ceria, wherein the molar ratio of cerium element to praseodymium element in the spherical praseodymium-doped ceria is 10000:1, and the average particle size of the praseodymium-doped ceria is 100 nm.

[0089] Example 2

[0090] This embodiment provides a method for preparing spherical neodymium-doped cerium dioxide, and the specific steps are as follows:

[0091] (1) stirring and mixing cerium nitrate and deionized water in a mass ratio of 1:100, then adding neodymium nitrate in a molar ratio of cerium element in cerium nitrate to neodymium element in neodymium nitrate of 100000:1, and continuing to stir until the solution becomes clear and transparent, and then, in the stirring process, sequentially adding nitric acid and acetic acid and continuing to stir until the solution becomes clear and transparent again, to obtain a first mixture; wherein the volume ratio of nitric acid and acetic acid added to the solution is 1:0.8, and the volume ratio of nitric acid to deionized water is 1:60;

[0092] (2) mixing the first mixture and urea in a mass ratio of deionized water to urea in the first mixture of 15:1 to obtain a second mixture, subjecting the second mixture to a first hydrothermal reaction at 300° C. for 2 h, then adding 10 wt % ammonia water to the product obtained by the first hydrothermal reaction until the pH of the mixture is 8 to obtain a third mixture, subjecting the third mixture to a second hydrothermal reaction at 300° C. for 2 h, then cooling the obtained product to 25° C., centrifuging at 20,000 rpm for 0.5 h, and collecting the solid to obtain a precipitate;

[0093] (3) Calcine the precipitate obtained in step (2) at 1300° C. for 3 h to obtain spherical neodymium-doped cerium dioxide, wherein the molar ratio of cerium element to neodymium element in the spherical neodymium-doped cerium dioxide is 100,000:1, and the average particle size of the neodymium-doped cerium dioxide is 60 nm.

[0094] Example 3

[0095] This embodiment provides a method for preparing spherical cerium dioxide doped with praseodymium and neodymium, and the specific steps are as follows:

[0096] (1) stirring and mixing cerium nitrate and deionized water in a mass ratio of 1:200, then adding praseodymium nitrate and neodymium nitrate in a ratio of 1000:1 of the total molar ratio of the cerium element in the cerium nitrate to the praseodymium element in the praseodymium nitrate and the neodymium element in the neodymium nitrate, the molar ratio of the praseodymium element in the praseodymium nitrate to the neodymium element in the neodymium nitrate being 3:1, and continuing to stir until the solution becomes clear and transparent, and then, in the stirring process, sequentially adding nitric acid and phosphoric acid and continuing to stir until the solution becomes clear and transparent again, to obtain a first mixture; wherein the volume ratio of nitric acid and phosphoric acid added to the solution is 1:0.4, and the volume ratio of nitric acid to deionized water is 1:140;

[0097] (2) mixing the first mixture and urea at a mass ratio of 25:1 between the solvent and urea in the first mixture to obtain a second mixture, subjecting the second mixture to a first hydrothermal reaction at 100° C. for 10 h, then adding 30 wt % ammonia water to the product obtained by the first hydrothermal reaction until the pH of the mixture is 11 to obtain a third mixture, subjecting the third mixture to a second hydrothermal reaction at 100° C. for 2 h, then cooling the obtained product to 25° C., centrifuging at 20,000 rpm for 0.5 h, and collecting the solid to obtain a precipitate;

[0098] (3) Calcinate the precipitate obtained in step (2) at 600° C. for 18 h to obtain quasi-spherical praseodymium-doped and neodymium-doped cerium dioxide, wherein the ratio of the molar amount of cerium element in the quasi-spherical praseodymium-doped and neodymium-doped cerium dioxide to the total molar amount of praseodymium element and neodymium element is 1000:1, the ratio of the molar amount of praseodymium element to neodymium element is 3:1, and the average particle size of the praseodymium-doped and neodymium-doped cerium dioxide is 60 nm.

[0099] Example 4

[0100] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the cerium nitrate used in step (1) of embodiment 1 is replaced by cerium chloride, and the praseodymium nitrate is replaced by praseodymium chloride. The other process parameters are the same as those of embodiment 1.

[0101] Example 5

[0102] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the cerium nitrate used in step (1) of embodiment 1 is replaced by cerium sulfate, and the praseodymium nitrate is replaced by praseodymium sulfate. The other process parameters are the same as those of embodiment 1.

[0103] Example 6

[0104] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the molar ratio of the cerium element in the cerium nitrate to the praseodymium element in the praseodymium nitrate in step (1) is 900:1, and praseodymium nitrate is added. The other process parameters are the same as those in embodiment 1.

[0105] Example 7

[0106] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the molar ratio of the cerium element in the cerium nitrate to the praseodymium element in the praseodymium nitrate in step (1) is 101000:1, and praseodymium nitrate is added. The other process parameters are the same as those in embodiment 1.

[0107] Example 8

[0108] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid to acetic anhydride in the mixed solution in step (1) is 1:0.3. The other process parameters are the same as those in embodiment 1.

[0109] Example 9

[0110] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid to acetic anhydride in the mixed solution in step (1) is 1:0.9. The other process parameters are the same as those in embodiment 1.

[0111] Example 10

[0112] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the step (1) of adding acetic anhydride to the mixed solution is omitted. The remaining process parameters are the same as those in embodiment 1.

[0113] Embodiment 11

[0114] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, in step (2), the first mixture and urea are mixed according to a mass ratio of deionized water in the first mixture to urea of ​​10:1. The remaining process parameters are the same as those in embodiment 1.

[0115] Example 12

[0116] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the first mixture and urea are mixed in step (2) according to the mass ratio of deionized water in the first mixture to urea of ​​55:2. The other process parameters are the same as those in embodiment 1.

[0117] Example 13

[0118] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the addition of urea is omitted in step (2), that is, step (2) adopts the following preparation process:

[0119] Ammonia water with a concentration of 25 wt% is added to the first mixture obtained in step (1) until the pH of the mixture is 9 to obtain a second mixture. The second mixture is subjected to a second hydrothermal reaction at a temperature of 200° C. for 6 h. The obtained product is then cooled to 30° C. and centrifuged at a rate of 5000 rpm for 2 h. The solid is taken to obtain a precipitate.

[0120] The remaining process parameters are the same as those in Example 1.

[0121] Embodiment 14

[0122] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, in step (2), urea and ammonia water are added in one step, and accordingly, the hydrothermal reaction is a one-stage hydrothermal reaction, that is, step (2) adopts the following preparation process:

[0123] Urea and 25 wt% ammonia water are added to the first mixture obtained in step (1) until the pH of the mixture is 9 to obtain a second mixture, wherein the mass ratio of deionized water to urea in the first mixture is 20:1, and the second mixture is subjected to a second hydrothermal reaction at a temperature of 200° C. for 6 h. Then, the obtained product is cooled to 30° C., centrifuged at a rate of 5000 rpm for 2 h, and the solid is taken to obtain a precipitate.

[0124] The remaining process parameters are the same as those in Example 1.

[0125] Embodiment 15

[0126] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the preparation method of the first mixture in step (1) is replaced by directly mixing and stirring cerium nitrate, deionized water, praseodymium nitrate, nitric acid, acetic anhydride and urea together to obtain the first mixture. The remaining process parameters are the same as those in embodiment 1.

[0127] Comparative Example 1

[0128] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the addition of praseodymium nitrate in the first mixture in step (1) is omitted. The remaining process parameters are the same as those in Example 1.

[0129] Comparative Example 2

[0130] The difference between this comparative example and Example 2 is that in the preparation method provided in this comparative example, the addition of neodymium nitrate in the first mixture in step (1) is omitted. The remaining process parameters are the same as those in Example 2.

[0131] Comparative Example 3

[0132] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the addition of the acidic reagent composed of nitric acid and acetic anhydride in the first mixture in step (1) is omitted. The remaining process parameters are the same as those in Example 1.

[0133] Test method:

[0134] (1) Particle size dispersion: The particle size of the doped cerium dioxide or cerium dioxide particles obtained in the above embodiments and comparative examples was measured by laser diffraction technology using a laser particle size analyzer, and the D10, D50 and D90 of the particles obtained in the above embodiments and comparative examples were calculated. The particle size dispersion was calculated using D10, D50 and D90. The calculation formula was: dispersion = (D90-D10) / D50. The results are shown in Table 1.

[0135] (2) Yield of quasi-spherical doped cerium dioxide: The yield of quasi-spherical doped cerium dioxide obtained in the above-mentioned embodiments and comparative examples was measured, and the calculation formula was: Yield of quasi-spherical doped cerium dioxide = mass of quasi-spherical doped cerium dioxide in the product / mass of the total product. The results are shown in Table 1.

[0136] Table 1

[0137]

[0138] The test results show that:

[0139] (1) It can be seen from Examples 1 to 3 that the present invention uses cerium salt and praseodymium salt and / or neodymium salt as doping metal salt as raw materials, and realizes the preparation of spherical doped cerium dioxide by mixing with an acidic reagent and a precipitant and designing the reaction process in combination with the selection of the preparation process, thereby obtaining nanometer-scale particles of doped cerium dioxide with regular morphology and uniform particle size. In addition, the preparation method adopted by the present invention is simple in process, short in reaction time, and can be used for mass production.

[0140] The specific morphology and structure of the doped cerium dioxide obtained in Example 1 are as follows: Figure 1 As shown in the figure, it can be seen that the doped cerium dioxide obtained by the preparation method designed by the present invention has the same spherical morphology, uniform particle size, and excellent particle size uniformity.

[0141] (2) It can be seen from Examples 1 and 4-5 that if chloride is used as the raw material in the present invention, it is difficult to remove the chlorine element therein, which affects the yield of the obtained material and thus affects the subsequent application of doped cerium dioxide; and if sulfate is used as the raw material, since the solubility of praseodymium sulfate is not as good as that of praseodymium nitrate, the reaction process will be prolonged and the operation difficulty will be increased.

[0142] (3) It can be seen from Example 1 and Examples 6-7 that the present invention further regulates the molar ratio of the cerium element in the cerium salt in the mixed solution to the doped metal element in the doped metal salt to regulate the relative addition amounts of the cerium salt and the doped metal salt. If the molar ratio of the two is too small and the addition amount of the doped metal salt is too large, the metal impurities in the final product will increase, thereby reducing the morphological identity of the nanoparticles and the performance. If the total relative molecular weight ratio of the two is too large and the addition amount of the doped metal salt is too small, the particle morphology will be deformed, which is not conducive to the formation of spherical particles and the particle size identity will be reduced.

[0143] (4) It can be seen from Example 1 and Examples 8-10 that the present invention further regulates the volume ratio of the first acidic reagent and the second acidic reagent. If the volume ratio of the two is too small and the content of the first acidic reagent is low, the cerium salt and the like will not be fully dissolved and the reaction will not start normally. If the volume ratio of the two is too large and the content of the second acidic reagent is low, the morphology of the cerium dioxide particles will be deformed, there will be too many impurities, and the reaction will go wrong, thereby affecting the yield of spherical cerium dioxide. Even when the present application omits the addition of the second acidic reagent, the yield of spherical cerium dioxide will be seriously reduced.

[0144] (5) It can be seen from Example 1 and Examples 11-13 that in the mixed solution of the present invention, if too much of the first precipitant is added, the uniformity of the particle morphology and particle size will be affected; if too little of the first precipitant is added, the reaction will be too slow and the yield will decrease; if the amount of urea added is directly omitted, the particle uniformity and the yield of spherical cerium dioxide particles will decrease, and the controllability of the particle morphology will decrease.

[0145] (6) It can be seen from Example 1 and Example 14 that, compared with adding ammonia water and urea to the mixed solution at the same time and carrying out a one-stage hydrothermal reaction, the present invention further preferably adopts the method of adding urea and ammonia water in stages to carry out a segmented hydrothermal reaction. This can avoid the simultaneous addition of the two and under the conditions of the hydrothermal reaction, which leads to an overly intense reaction between the substances, affects the morphology and particle size of the doped cerium dioxide, and causes a decrease in the yield of spherical products and a deterioration in the uniformity of the particle size.

[0146] (7) It can be seen from Example 1 and Example 15 that, compared with the process of mixing the components of the first mixture together, the present invention further sets a distributed mixing process to obtain the first mixture, which is beneficial to obtaining spherical materials with good morphology, improving the doping uniformity of the doping elements, and is beneficial to obtaining spherical materials with good morphology. In addition, step-by-step mixing can promote the uniformity of the particle size of the obtained product and obtain nanoparticles of uniform size.

[0147] (8) By comparing Example 1 and Comparative Example 1, as well as Example 2 and Comparative Example 2, it can be seen that if the addition of praseodymium nitrate or neodymium nitrate is omitted in the present invention, a spherical cerium dioxide material cannot be formed, and the morphology of the formed cerium dioxide is irregular rod-like or amorphous.

[0148] (9) By comparing Example 1 and Comparative Example 3, it can be seen that if the addition of the acidic reagent is omitted in the present invention, the morphological identity and particle size uniformity of the doped cerium dioxide will deteriorate, the particle size of the structure will increase, and nano-scale spherical particles cannot be obtained.

[0149] In summary, the present invention uses cerium salt and praseodymium salt and / or neodymium salt as doping metal salt as raw materials, and realizes the preparation of spherical doped cerium dioxide by mixing with acidic reagents and precipitants and designing the reaction process in combination with the selection of preparation process. The method has simple preparation process, short reaction time, and can be used for mass production. The prepared doped cerium dioxide is nano-scale particles, and its morphology is regular and the particle size is uniform, and it can be widely used in semiconductor CMP polishing, high-end optical polishing or cosmetics and other fields.

[0150] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing spherical doped cerium dioxide, characterized in that: The preparation method comprises the following steps: The cerium salt, the doping metal salt, the solvent, the acidic reagent and the precipitant are mixed, and then subjected to a hydrothermal reaction to obtain a precipitate, and the precipitate is calcined to obtain the spherical doped cerium dioxide; The doping metal salt includes praseodymium salt and / or neodymium salt.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the cerium salt to the solvent is 1:(100-200); Preferably, in the mixed solution, the molar ratio of the cerium element in the cerium salt to the doping metal element in the doping metal salt is (1000-100000):1; Preferably, the cerium salt comprises any one of cerium nitrate, cerium chloride, cerium hydroxide or cerium sulfate, or a combination of at least two thereof, preferably cerium nitrate; Preferably, the praseodymium salt comprises any one of praseodymium nitrate, praseodymium chloride or praseodymium sulfate, or a combination of at least two thereof, preferably praseodymium nitrate; Preferably, the neodymium salt comprises any one of neodymium nitrate, neodymium chloride or neodymium sulfate, or a combination of at least two thereof, preferably neodymium nitrate; Preferably, the doping metal salt comprises praseodymium salt and neodymium salt; Preferably, when the doping metal salt includes praseodymium salt and neodymium salt, the molar ratio of the praseodymium element in the praseodymium salt to the neodymium element in the neodymium salt is (1-100):

1.

3. The preparation method according to claim 1 or 2, characterized in that: The acidic reagent includes a first acidic reagent and a second acidic reagent; Preferably, the first acidic reagent comprises nitric acid; Preferably, the second acidic reagent comprises any one of acetic anhydride, formic acid, phosphoric acid, acetic acid or n-butyric acid; Preferably, the volume ratio of the first acidic reagent to the second acidic reagent is 1:(0.4-0.8); Preferably, the volume ratio of the first acidic reagent to the solvent is 1:(50-140).

4. The preparation method according to any one of claims 1 to 3, characterized in that The precipitant includes a first precipitant and / or a second precipitant; Preferably, the precipitant comprises a first precipitant and a second precipitant; Preferably, when the precipitant includes a first precipitant and a second precipitant, the precipitant is added by a one-step addition method or a step-by-step addition method; Preferably, when the precipitant is added in one step, the hydrothermal reaction is a one-stage hydrothermal reaction; Preferably, the specific process of the one-stage hydrothermal reaction comprises: mixing a cerium salt, a doping metal salt, a solvent and an acidic reagent to obtain a first mixture, mixing the first mixture with a first precipitant and a second precipitant to obtain a second mixture, and subjecting the second mixture to a one-stage hydrothermal reaction to obtain a precipitate; Preferably, the temperature of the primary hydrothermal reaction is 100-300°C; Preferably, the time of the primary hydrothermal reaction is 1-12 h.

5. The preparation method according to claim 4, characterized in that: When the precipitant is added in steps, the hydrothermal reaction is a staged hydrothermal reaction; Preferably, the segmented hydrothermal reaction includes a first hydrothermal reaction and a second hydrothermal reaction; Preferably, the specific process of the first hydrothermal reaction comprises: mixing a cerium salt, a doping metal salt, a solvent and an acidic reagent to obtain a first mixture, mixing the first mixture with a first precipitant to obtain a third mixture, and subjecting the third mixture to a first hydrothermal reaction; Preferably, the specific process of the second hydrothermal reaction includes: mixing a second precipitant with the product after the first hydrothermal reaction to obtain a fourth mixture, and performing a second hydrothermal reaction on the fourth mixture to obtain the precipitate; Preferably, the temperature of the first hydrothermal reaction and the second hydrothermal reaction are independently selected from 100-300°C; Preferably, the time of the first hydrothermal reaction and the second hydrothermal reaction are independently selected from 1-12h; Preferably, the hydrothermal reaction is followed by a cooling and separation process.

6. The preparation method according to claim 4 or 5, characterized in that: The first precipitant and the second precipitant are independently selected from any one of urea, ammonia water, ammonium nitrate, ammonium phosphate or ammonium sulfate; Preferably, the first precipitating agent comprises urea; Preferably, the second precipitant includes any one of ammonia water, ammonium nitrate, ammonium phosphate or ammonium sulfate; Preferably, the mass ratio of the solvent in the first mixture to the first precipitant is (50-100):4; Preferably, the concentration of the second precipitant is 1-50wt%; Preferably, the pH of the mixture after adding the precipitant is 7.5-11.0; Preferably, the specific mixing process for preparing the first mixture includes: mixing the cerium salt with a solvent, adding a doping metal salt and continuing to mix, and then sequentially adding a first acidic reagent and a second acidic reagent and mixing to obtain the first mixture.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The calcination temperature is 600-1300°C; Preferably, the calcination time is 1-24 hours.

8. A spherical doped cerium dioxide, characterized in that: The spherical doped cerium dioxide is prepared by the preparation method according to any one of claims 1 to 7, and the doping elements in the doped cerium dioxide include praseodymium and / or neodymium.

9. The spherical doped cerium dioxide according to claim 8, characterized in that: The molar ratio of the cerium element to the doping element in the doped cerium dioxide is (1000-100000):1; Preferably, the average particle size of the doped cerium dioxide is 20-300 nm, preferably 20-100 nm; Preferably, the doping elements of the doped cerium dioxide include praseodymium and neodymium; Preferably, the molar ratio of the praseodymium to the neodymium is (1-100):

1.

10. Use of the spherical doped cerium dioxide according to claim 8 or 9, characterized in that: The spherical doped cerium dioxide is applied in semiconductor polishing, optical polishing or cosmetics.

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