A method for preparing high-crystallinity La-Ni-O system oxide
By combining the melting method with bismuth oxide solvent, the problem that traditional methods are difficult to prepare high-crystallinity La-Ni-O oxide was solved, the preparation of high crystallinity and environmentally friendly production were achieved, and the comprehensive performance of the material was improved.
Patent Information
- Application Number
- CN202410858400.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-06-28
AI Technical Summary
It is difficult to prepare high-crystallinity La-Ni-O system oxides using traditional methods, and the sol-gel method has problems of complex operation and environmental pollution.
A melting method is used with bismuth oxide as a solvent to prepare high-crystallinity La-Ni-O system oxides through mixing, drying, hot pressing, pre-sintering, sintering and other steps. The reaction characteristics of bismuth oxide with lanthanum oxide and nickel oxide are utilized to improve the crystallinity and avoid environmental pollution.
The low-cost and green preparation of high-crystallinity La-Ni-O oxide was achieved, the operation process was simplified, the physical and chemical properties of the material were improved, and it is suitable for applications in multiple fields.
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Figure CN118619328B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of metal oxides, and in particular to a method for preparing a La-Ni-O system oxide with high crystallinity. Background Art
[0002] La-Ni-O system oxides have broad application prospects in multiple fields. They can be used as electrode materials or electrolyte materials in the energy field, as catalyst carriers and photocatalytic materials in the catalysis field, as magnetic materials and transparent conductive films in the electronic device field, and can be used to prepare gas sensors and photocatalytic air purifiers in the environmental field. In the materials field, they can be used as raw materials for multifunctional composite materials and have good electrical conductivity and superconducting properties.
[0003] Crystallinity is the integrity and degree of order of the crystal structure in a material. Specifically, crystallinity describes how regular and consistent the arrangement of atoms, ions or molecules inside a material is. High crystallinity means that the atoms in the material are arranged neatly and orderly, forming a clear lattice structure, while low crystallinity means that the atoms are arranged irregularly, with more defects, grain boundaries or amorphous regions. The crystallinity of La-Ni-O system oxides directly affects their electrical, magnetic, mechanical, chemical, thermal and catalytic properties. Therefore, improving the crystallinity of the material during the preparation process is the key to obtaining high-performance La-Ni-O system oxides. However, traditional solid-phase sintering preparation methods often find it difficult to obtain ideal crystallinity, and although the sol-gel preparation method can obtain products with higher crystallinity, its operation process is complicated and will produce toxic gases and acidic waste, bringing serious environmental pollution problems.
[0004] Therefore, how to overcome the problems existing in the prior art and provide a method for preparing La-Ni-O system oxides with high crystallinity that is simple to operate and pollution-free is one of the technical problems that need to be solved urgently. Summary of the Invention
[0005] To solve the above problems, the present invention provides a method for preparing high-crystallinity La-Ni-O system oxides. Based on the melting method, this method uses bismuth oxide as a solvent to achieve low-cost, green and efficient preparation of high-crystallinity La-Ni-O system oxides.
[0006] The method for preparing the high-crystallinity La-Ni-O system oxide of the present invention comprises the following steps:
[0007] S1. Mix lanthanum, nickel, and bismuth oxide powders in proportion, add appropriate amount of alcohol, and grind and stir thoroughly to form a uniform turbid liquid;
[0008] S2, drying the turbid liquid to obtain a mixed powder;
[0009] S3, hot pressing the mixed powder to obtain sample A;
[0010] S4, pre-calcining the sample A, then heating and sintering it, and then naturally cooling it in the furnace to obtain sample B;
[0011] S5. Mixing the sample B again with an appropriate amount of alcohol and grinding until a uniform turbid liquid is formed, drying, and hot-pressing to obtain a sample C;
[0012] S6. The sample C is subjected to secondary sintering, and then cooled in the furnace to obtain a La-Ni-O system oxide.
[0013] Furthermore, the molar ratio of the lanthanum, nickel oxide and bismuth oxide is 3:(1-2). Preferably, the molar ratio of the lanthanum, nickel oxide and bismuth oxide is 7:3.
[0014] Furthermore, the molar ratio of the lanthanum oxide to the nickel oxide is 2:(1-3). Preferably, the molar ratio of the lanthanum oxide to the nickel oxide is 3:4.
[0015] Furthermore, the drying temperature is 70° C.-75° C., and the drying time is 10-12 hours.
[0016] Furthermore, the hot pressing temperature is 100-200° C., and the pressure is 80-120 MPa. Preferably, the hot pressing pressure is 80-100 MPa.
[0017] Furthermore, the pre-firing temperature is 900° C. and the pre-firing time is 16 hours.
[0018] Furthermore, the sintering temperature is 1100° C., the sintering time is 16 h, and the heating rate is 5° C. / min-10° C. / min.
[0019] Furthermore, the drying and hot pressing forming processes are the same as S2 and S3.
[0020] Furthermore, the secondary sintering temperature is 1100° C., the sintering time is 40 h, and the heating rate is 5° C. / min-10° C. / min.
[0021] Compared with the prior art, the present invention has the following beneficial technical effects:
[0022] The present invention builds on the method of preparing the La-Ni-O system 327 phase or 4310 phase by sintering a mixture of lanthanum oxide and nickel oxide. Bismuth oxide, which is unreactive with both lanthanum oxide and nickel oxide, is added as a solvent, allowing the lanthanum oxide and nickel oxide to fully mix and react within the molten bismuth oxide. Furthermore, the reaction product, the La-Ni-O system oxide, has poor compatibility with the bismuth oxide, resulting in surface precipitation. Combined with repeated grinding, mixing, and sintering, this method improves the crystallinity of the product, enabling the preparation of a high-crystallinity La-Ni-O system oxide.
[0023] Compared with the traditional sol-gel method and solid-phase grinding and mixing method, the preparation process of the present invention is simple and highly operable, the product has high crystallinity, better physical and chemical properties, and does not produce toxic gases and acidic waste liquids, providing strong support for research and application in related fields such as materials science, chemical engineering, and physics.
[0024] The solvent bismuth oxide of the present invention does not react with most dopable elements. Therefore, on the basis of the current preparation process, a doping process of multiple elements can be carried out to realize the preparation of La-Ni-O system oxides doped with multiple elements. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will be further described below with reference to the accompanying drawings.
[0026] Figure 1 This is the SEM image of the product of Example 1;
[0027] Figure 2 This is the RT diagram of the product of Example 1;
[0028] Figure 3 This is the XRD pattern of the product in Example 1;
[0029] Figure 4 This is the SEM image of the product of Comparative Example 1;
[0030] Figure 5 This is the RT diagram of the product of Comparative Example 1;
[0031] Figure 6 This is the SEM image of the product of Comparative Example 2;
[0032] Figure 7 This is the RT diagram of the product of Comparative Example 2. DETAILED DESCRIPTION
[0033] The present invention provides a method for preparing a high-crystallinity La-Ni-O system oxide, which specifically comprises the following steps:
[0034] S1. Mix lanthanum, nickel, and bismuth oxide powders in proportion, add appropriate amount of alcohol, and grind and stir thoroughly to form a uniform turbid liquid;
[0035] S2, drying the turbid liquid to obtain a mixed powder;
[0036] S3, hot pressing the mixed powder to obtain sample A;
[0037] S4, pre-calcining the sample A, then heating and sintering it, and then naturally cooling it in the furnace to obtain sample B;
[0038] S5. Mixing the sample B again with an appropriate amount of alcohol and grinding until a uniform turbid liquid is formed, drying, and hot-pressing to obtain a sample C;
[0039] S6. The sample C is subjected to secondary sintering, and then cooled in the furnace to obtain a La-Ni-O system oxide.
[0040] In one embodiment, the molar ratio of the lanthanum, nickel and bismuth oxides is 3:(1-2). Preferably, the molar ratio of the lanthanum, nickel and bismuth oxides is 7:3.
[0041] In one embodiment, the molar ratio of lanthanum to nickel oxide is 2:(1-3). Preferably, the molar ratio of lanthanum to nickel oxide is 3:4.
[0042] In the present invention, insufficient addition of bismuth oxide will lead to insufficient reaction, uneven grain size and structure, and ultimately a decrease in the crystallinity of the La-Ni-O system oxide, affecting the overall performance of the material. Excessive addition of bismuth oxide will cause problems such as phase separation and impurity phase generation, and will also reduce the purity and crystallinity of the main phase, affecting the overall performance of the material. Therefore, the amount of bismuth oxide used has a very important impact on the stability of the La-Ni-O system oxide preparation process of the present invention. Furthermore, the present invention strictly limits the amount of solvent bismuth oxide added.
[0043] In one embodiment, the drying temperature is 70° C.-75° C., and the drying time is 10-12 hours. Preferably, the drying temperature is 75° C., and the drying time is 12 hours.
[0044] In one embodiment, the hot pressing temperature is 100° C.-200° C., and the pressure is 80-120 MPa. Preferably, the hot pressing pressure is 80-100 MPa.
[0045] In one embodiment, the pre-firing temperature is 900° C. and the pre-firing time is 16 hours.
[0046] In one embodiment, the sintering temperature is 1100° C., the sintering time is 16 hours, and the heating rate is 5° C. / min-10° C. / min.
[0047] In one embodiment, the drying and hot pressing processes are the same as S2 and S3.
[0048] In one embodiment, the secondary sintering temperature is 1100° C., the sintering time is 40 h, and the heating rate is 5° C. / min-10° C. / min.
[0049] The technical solution provided by the present invention is further described below in conjunction with embodiments.
[0050] Example 1 A method for preparing a high-crystallinity La-Ni-O system oxide comprises the following steps:
[0051] S1. Mix La2O3, NiO, and Bi2O3 powders in a molar ratio of 3:4:3 in an agate mortar, add an appropriate amount of alcohol as a grinding agent, and grind and stir thoroughly until a uniform turbid liquid is formed; in order to accurately control the ratio of raw materials, a high-precision balance is used for weighing to ensure the accuracy of the raw material dosage;
[0052] S2, drying the turbid liquid in a vacuum drying oven at 75° C. for 12 h to ensure that the alcohol is completely volatilized, to obtain a mixed powder;
[0053] S3, hot pressing the obtained mixed powder at 200°C and 100 MPa to obtain a dense solid sample A;
[0054] S4. Pre-sintering the sample A in a muffle furnace at 900° C. for 16 h, then heating to 1100° C. at a rate of 10° C. / min and sintering for 16 h, and then naturally cooling in the furnace to obtain sample B;
[0055] S5. Place the sample B in an agate mortar, add an appropriate amount of alcohol, and grind and stir thoroughly until a uniform turbid liquid is formed. Dry the turbid liquid at 75°C for 12 hours, and hot-press at 200°C and 100 MPa to obtain sample C.
[0056] S6. Place the sample C in a muffle furnace, heat it to 1100° C. at a rate of 10° C. / min, sinter it for 40 hours, and then cool it in the furnace to obtain a La-Ni-O system oxide.
[0057] After testing, no reaction raw materials remained in the product. Figure 1 The product is large, with a layered structure and mostly polygonal grains with sharp edges. The grain surfaces are relatively smooth, with distinct crystal faces. A small number of particles adhere to the grain surfaces, and the overall uniformity is good, indicating a high degree of crystallinity. Micro-XRD diffraction characterization confirmed the phase to be La₃Ni₂Oₐ.
[0058] Comparative Example 1
[0059] Same as Example 1, except that Bi2O3 is not added.
[0060] After testing, no reaction raw materials remained in the product. Figure 4 It can be seen that the product of this comparative example is granular grains with irregular grain shape, unclear edges, high grain surface roughness, many pores and gaps between particles, small grain size, uneven size, and low crystallinity. Figure 5 It can be seen that the resistance behavior of the product is consistent with that of typical La3Ni2O7.
[0061] Comparative Example 2
[0062] Same as Example 1, except that the sintering temperature for both times is 1000°C.
[0063] After testing, a small amount of reaction raw materials remained in the product. Figure 6 It can be seen that the particle size of the product of this comparative example is close to that of Example 1, but the grain morphology is more complex, with more irregular shapes, and the crystal surface has a clear layered structure. Some raw material particles are still attached to the grain surface and grain boundaries. Figure 6 It can be seen that the resistance behavior of the product is similar to that of the typical La4Ni3O 10 conform to.
[0064] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.
Claims
1. A method for preparing a high-crystallinity La-Ni-O system oxide, characterized in that: The following steps are involved: S1. Mix lanthanum, nickel, and bismuth oxide powders in proportion, add appropriate amount of alcohol, and grind and stir thoroughly to form a uniform turbid liquid; S2, drying the turbid liquid to obtain a mixed powder; S3, hot pressing the mixed powder to obtain sample A; S4, pre-calcining the sample A, then heating and sintering it, and then naturally cooling it in the furnace to obtain sample B; S5. Mixing the sample B again with an appropriate amount of alcohol and grinding until a uniform turbid liquid is formed, drying, and hot-pressing to obtain a sample C; S6, performing secondary sintering on the sample C, and then cooling it in the furnace to obtain a La-Ni-O system oxide; The molar ratio of the lanthanum, nickel oxide and bismuth oxide is 3:(1-2); the molar ratio of the lanthanum, nickel oxide is 2:(1-3); The pre-firing temperature in step S4 is 900° C. and the pre-firing time is 16 hours; The sintering temperature in step S4 is 1100° C., the sintering time is 16 hours, and the heating rate is 5° C. / min-10° C. / min; The temperature of the secondary sintering in step S6 is 1100° C., the time of the secondary sintering is 40 hours, and the heating rate is 5° C. / min-10° C. / min.
2. The preparation method according to claim 1, characterized in that The drying temperature is 70° C.-75° C., and the drying time is 10-12 hours.
3. The preparation method according to claim 1, characterized in that The temperature of the hot pressing is 100° C.-200° C., and the pressure is 80-120 MPa.