Batch preparation method of high-purity high-chemical-activity REBCO superconducting powder
The spray drying method for preparing REBCO superconducting powder solves the problems of poor component uniformity and high impurities in the solid-state reaction method, and realizes the preparation of high-purity, low-temperature calcination and short-cycle superconducting powder, thereby improving superconducting performance and powder activity.
Patent Information
- Application Number
- CN202510996088.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-10-31
AI Technical Summary
Existing solid-state reaction methods for preparing REBCO superconducting powders suffer from problems such as poor compositional uniformity, high calcination temperature, high impurity content, increased powder particle size, and low density, resulting in poor superconducting performance.
REBCO superconducting powder was prepared by spray drying. The pH value was adjusted by dissolving high-purity oxygen-free Cu, BaCO3 and Re2O3 in concentrated nitric acid, spray drying into small droplets, low-temperature calcination and ball milling, and controlling the calcination temperature and homogenization treatment to ensure the uniformity and purity of chemical composition.
It improves the uniformity and purity of micro-region chemical composition of REBCO superconducting powder, reduces impurity content and carbon residue, shortens the preparation cycle, and improves powder activity and density, making it suitable for the preparation of high-density targets and bulk materials.
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Figure CN120864876A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-temperature superconducting powder batch preparation technology, and in particular to a method for batch preparation of high-purity, highly chemically active REBCO superconducting powder. Background Technology
[0002] REBCO superconductors have high critical temperatures, high critical current densities (Jc), and irreversible fields (Hirr), making them ideal for manufacturing strong magnets. Currently, the practical REBCO superconducting materials can be broadly categorized into REBCO coated conductors and REBCO single-domain bulk materials. Single-domain bulk materials are still in the small-batch production stage, while the industrialization of superconducting tapes is maturing, with global production capacity expected to reach over 50,000 kilometers by 2026.
[0003] Compared to other REBCO tape superconducting layer preparation processes, pulsed laser deposition (PLD) technology can perfectly replicate the stoichiometry of the target material and achieve more precise control over the microstructure of the superconducting film. It is a method for preparing high-quality superconducting films, and the prepared tapes are particularly suitable for applications at low temperatures and high fields. Therefore, it has been adopted by many leading tape manufacturing companies such as SuperOx, Fujikura, and Shanghai Superconducting Technologies. PLD belongs to PVD technology. In order to improve the quality of the prepared superconducting film, it is necessary to strictly control the phase purity, impurity content, and density of the ceramic target material, which largely depends on the powder used for sintering the target material.
[0004] Techniques for preparing REBCO powder include solid-state reaction, sol-gel / solution, co-precipitation, plasma spraying, freeze-drying, and spray drying. Currently, the most commonly used method for preparing commercial powder is the solid-state reaction method, which involves thoroughly mixing Re₂O₃, BaCO₃, and CuO in a 1:4:6 ratio. The resulting powder is then calcined at 900-940℃ and homogenized. This homogenization and high-temperature calcination process is repeated several times until a pure phase is achieved. However, the solid-state reaction method has the following drawbacks: First, the three initial raw materials have different specific gravities and particle sizes, requiring a long homogenization period. To achieve uniform composition in the micro-area, processing (air jet milling or ball milling) is necessary. Therefore, the preparation process requires multiple calcinations and homogenization treatments, which is time-consuming and prone to introducing impurities during the grinding process. Secondly, the decomposition temperature of BaCO3 is around 1300℃, which exceeds the peritectic reaction temperature. Under conventional calcination temperatures, the decomposition is incomplete, and carbon elements are prone to remain, thus affecting the superconducting performance. Thirdly, the purity of the raw material CuO is generally only 99.5%, and the cost of high-purity CuO is too high, resulting in low overall purity of the prepared superconducting powder. Fourthly, after multiple calcinations, the particle size of the powder increases, the reactivity is poor, and the density of the sintered target material is low.
[0005] Therefore, in response to the problems mentioned above, this invention proposes a method for the batch preparation of high-purity, highly chemically active REBCO superconducting powder. Summary of the Invention
[0006] To overcome the problems of poor component uniformity and high calcination temperature in powders prepared by solid-state reaction methods, this invention proposes a method for the batch preparation of high-purity, highly chemically active REBCO superconducting powders.
[0007] Please see Figure 1 The technical solution of the present invention is: a method for batch preparation of high-purity, highly chemically active REBCO superconducting powder, comprising the following steps:
[0008] S1. Using concentrated nitric acid with a mass concentration of 50%-70%, oxygen-free Cu, BaCO3, and Re2O3 with a purity greater than 99.99% are dissolved in a cation molar ratio of 1:2:3 to obtain a mixed nitrate aqueous solution of Re, Ba, and Cu. The pH of the mixed solution is then adjusted with deionized water and ammonia to 5-7, and the total concentration of metal cations is 0.2-0.5 mol / L.
[0009] S2, a mixture of nitrates of Re, Ba and Cu is prepared from the mixed nitrate aqueous solution in step S1 using a spray drying device. The inlet air temperature of the spray drying device is 100-180℃ and the outlet air temperature is 60-80℃.
[0010] S3, In a large-cavity box furnace with exhaust vents, flowed artificial air was introduced and the nitrate mixture in step S2 was calcined at a low temperature of 500-700℃ for 0.5-10h. After homogenization, intermediate powder with a particle size of 200-300 mesh was obtained.
[0011] S4, the intermediate powder from step S3 is calcined at 800-900℃ for 10-24 hours in flowing artificial air or oxygen. After calcination, the powder is dry-milled in a ball mill for at least 15 hours to reduce the powder density. 50 Reduce the size to 1-2 μm. If necessary, repeat the calcination and homogenization process 2-3 times until no second phase is detected.
[0012] Preferably, in step S1, oxygen-free copper is selected as the raw material, and the purity of the raw material must be above 4N.
[0013] Preferably, in step S1, a slight excess of concentrated nitric acid is used to completely dissolve the raw materials, oxygen-free Cu, BaCO3, and Re2O3, in the nitric acid in sequence, and then the pH value and total concentration of metal cations of the solution are adjusted with deionized water and ammonia.
[0014] Preferably, in step S1, the concentrated nitric acid and ammonia water used are both MOS grade, and the conductivity of the deionized water is no greater than 0.1 μs / cm.
[0015] Preferably, in step S2, the nitrate mixture is REBCO precursor powder.
[0016] Preferably, in step S2, the liquid inlet speed is set according to the equipment specifications. When using a 1.5L / h peristaltic pump, the liquid inlet speed needs to be maintained between 1.5 and 3.5L / h.
[0017] Preferably, in step S3, the homogenization process is manual grinding or mechanical grinding, with a grinding time of 5-20 minutes, and the material is passed through a 200-300 mesh sieve after grinding.
[0018] Preferably, in step S3, the thickness of the powder layer during calcination is no more than 1.5 cm.
[0019] Preferably, in step S3, the calcination and homogenization process can be repeated 1-2 times to completely denitrify the powder.
[0020] Preferably, in step S4, the homogenization process uses an omnidirectional planetary ball mill for dry grinding, with a ball-to-material ratio of 1:3 to 1:5 and a rotation speed of 200 to 400 rpm.
[0021] The beneficial effects of this invention are:
[0022] 1. This invention uses a spray drying process to ultrasonically atomize a mixed nitrate aqueous solution of Re, Ba, and Cu into small droplets, which are then dried to form REBCO precursor powder. Because the elements in the solution are uniformly mixed at the ionic level, the chemical composition of each small droplet formed by spraying is uniform. This ensures that the final REBCO superconducting powder has a high degree of micro-region chemical composition uniformity and a phase purity of over 99%.
[0023] 2. This invention selects oxygen-free Cu sheets / foils with higher purity to replace CuO as raw materials, avoiding the direct use of nitrates containing water of crystallization as raw materials. It selects MOS-grade concentrated nitric acid and ammonia, and controls the metal ion content in deionized water. These measures effectively reduce the trace metal impurity content in the final REBCO superconducting powder, thereby ensuring its stoichiometry and improving its superconducting performance. Furthermore, the blue precursor powder after spray drying is mainly composed of easily decomposable nitrates and is essentially free of carbonate ions, avoiding carbon residue caused by incomplete decomposition of barium carbonate. This effectively reduces carbon residue in the final product and improves superconducting performance.
[0024] 3. The nitrate decomposition temperature of the present invention is significantly lower than that of carbonate. The precursor powder after spray drying has a particle size in the submicron range. After low-temperature decomposition and denitrification, the powder particle size is still relatively small and has good activity. Therefore, the superconducting phase can be completely generated by calcination at a lower temperature than that of general solid-phase reactions, making the powder easier to break and homogenize, thereby improving the powder production efficiency and shortening the entire process cycle. Moreover, the particle size of the generated REBCO superconducting powder is generally below 2μm, which is beneficial for preparing targets and bulk materials with higher density in later applications. Attached Figure Description
[0025] Figure 1 The diagram shown is a schematic representation of the preparation process of this invention;
[0026] Figure 2 The diagram shows an XRD pattern of YBC0 powder prepared by the solid-state method and spray drying method of the present invention.
[0027] Figure 3 The image shown is a SEM diagram illustrating the preparation of precursor powders using the solid-phase method and spray drying method of this invention. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] Please see Figure 1 This invention provides an embodiment: a method for batch preparation of high-purity, highly chemically active REBCO superconducting powder, comprising the following steps:
[0030] S1. Starting from raw material control, oxygen-free Cu, BaCO3, and Re2O3 are selected as raw materials and weighed according to the molar ratio of Re:Ba:Cu = 1:2:3. Oxygen-free Cu, BaCO3, and Re2O3 are dissolved in concentrated nitric acid in sequence to obtain a mixed nitrate aqueous solution of Re, Ba, and Cu. The pH value and total concentration of metal cations of the mixed solution are adjusted with deionized water and ammonia.
[0031] Oxygen-free Cu was chosen instead of CuO as the raw material because the former has higher purity, which can effectively reduce the impurity content in the final product. Excess concentrated nitric acid was used to dissolve the weighed raw materials in the nitric acid in the order of Cu, BaCO3, and Re2O3. This order optimizes the dissolution rate. After complete dissolution, the solution was titrated with ammonia water, and the acidity or alkalinity of the solution was monitored with a pH meter to bring the pH value of the mixed salt solution to 5-7, which tends to be neutral, thus protecting the spray drying equipment and preventing cation contamination. Then, the total concentration of metal cations in the solution was adjusted with deionized water to 0.2-0.5 mol / L, which is beneficial for the operation of the spray drying equipment.
[0032] The purity of all raw materials is above 99.99%. Oxygen-free Cu is made of copper sheets or copper foil to increase the reaction area. The mass concentration of concentrated nitric acid is 50%-70%. In order to minimize the trace metal element content in the prepared REBCO powder, the conductivity of deionized water is not greater than 0.1 μs / cm, and both nitric acid and ammonia water are of MOS grade.
[0033] S2, REBCO precursor powder is prepared by spray drying of mixed nitrate aqueous solution. The inlet air temperature of the spray dryer is 100-180℃ and the outlet air temperature is 60-80℃. The precursor powder is mainly composed of nitrates of three cations.
[0034] Select appropriate equipment specifications based on production requirements, and then set the liquid inlet speed according to the equipment specifications. For laboratory equipment with a capacity of 1.5 kg / h, the liquid inlet speed of the peristaltic pump should be maintained at 1.5-3.5 L / h; for medium-sized equipment with a capacity of 10 kg / h, the liquid inlet speed of the peristaltic pump can be above 10 L / h. The blue precursor powder collected after spray drying is mainly composed of nitrates of three cations, with a particle size between 1-10 μm and soft agglomeration.
[0035] S3. Dry, flowing artificial air is introduced into a large-cavity box furnace with exhaust vents. The precursor powder is calcined at a low temperature of 500-700℃ for 0.5-10 hours. Note that calcination should be carried out after the furnace temperature reaches the specified temperature. The powder layer thickness during calcination should not exceed 1.5cm. After homogenization, intermediate powder with a particle size of 200-300 mesh is obtained. If necessary, the calcination and homogenization process can be repeated 1-2 times until the powder is completely denitrified.
[0036] The main purpose of low-temperature calcination is to remove nitrate ions (NO3) from the precursor powder. The product after calcination is a mixture of oxides containing Re, Ba, and Cu, which is grayish-black. Calcination is generally carried out in a specially designed large-cavity box furnace with exhaust vents, and dry, flowing artificial air is introduced to ensure that the nitrogen-containing gas generated during calcination can be discharged smoothly, allowing the reaction to proceed smoothly. The discharged gas needs to be properly treated, such as by spraying. The requirement that the powder layer thickness during calcination should not exceed 1.5 cm is also to ensure that the reaction proceeds fully and that the generated gas can be discharged in a timely manner. Calcination should begin after the furnace temperature reaches the specified temperature to prevent the formation of other products.
[0037] Compared to carbonates, nitrates can decompose at lower temperatures and more completely. Weigh the nitrates before and after calcination and compare the weight loss. If necessary, repeat the calcination until there is no more weight loss. At this point, the nitrates can be considered to have decomposed completely. The product after low-temperature calcination is relatively loose. Use hand grinding or simple mechanical grinding for 5-20 minutes to homogenize the powder. After grinding, pass it through a 200-300 mesh sieve.
[0038] S4. The intermediate powder is heated to 800-900℃ at a rate of 5-10℃ / min and calcined for 10-24 hours in artificial air or oxygen atmosphere. Then, it is cooled in the furnace to obtain the REBCO superconducting phase. After calcination, the powder is dry-milled in a ball mill for at least 15 hours at a ball-to-powder ratio of 1:3-1:5 and a speed of 200-400 rpm to achieve the desired powder density. 50 Reduce the size to 1-2 μm. If necessary, repeat the calcination and homogenization process 2-3 times until no second phase is detected.
[0039] The intermediate powder is highly reactive and can react and form phases at lower temperatures. The high-temperature calcination temperature of this method is lower than the phase-forming temperature of general solid-phase reactions, resulting in smaller powder particle sizes. This also facilitates subsequent homogenization treatment and reduces the powder density (d). 50 It can effectively improve the activity and reaction rate of powder, which is beneficial for subsequent use in the preparation of targets and bulk materials with higher density.
[0040] This invention provides REBCO superconducting powder, which is prepared according to the above-described method for batch preparation of REBCO superconducting powder. It also provides applications of REBCO superconducting powder, such as its use as a target material in PVD processes for preparing thin films or tapes, and its application in the top-seeded method for preparing REBCO single-domain bulk materials.
[0041] This invention provides an embodiment:
[0042] YBCO powder was prepared by spray drying for the fabrication of single-domain bulk materials, including the following steps:
[0043] Step 1: Weigh the raw materials according to the ratio of Y:Ba:Cu = 1:2:3. In order to reduce impurities, select Y2O3 with a purity of 99.999%, BaCO3 with a purity of 99.99%, and high-purity oxygen-free Cu flakes with a purity of 99.99%.
[0044] Step 2: Dissolve the weighed raw materials in nitric acid in the order of Cu flakes, BaCO3, and Y2O3, add deionized water to ensure a cation concentration of 0.3-0.5 mol / L, and add ammonia water to adjust the pH value to 5-7.
[0045] Step 3: Prepare precursor powder by spray drying the dissolved solution, with an air inlet temperature of 130℃;
[0046] Step 4: Perform a nitrogen removal treatment on the precursor powder obtained in Step 3 at a temperature of 600℃ for 10 hours.
[0047] Step 5: The powder obtained in Step 4 is subjected to a short-term homogenization treatment, namely manual grinding for 0.5 hours, followed by a secondary nitrogen removal treatment at a temperature range of 630-680℃ for 10 hours.
[0048] Step 6: The powder obtained in Step 5 is subjected to short-term homogenization treatment, i.e., manual grinding for 0.5 hours, and finally high-temperature calcination treatment, with the temperature range set at 880-900℃, the sintering atmosphere being air, and the duration being 24 hours.
[0049] Step 7: The powder from Step 6 is refined at a ratio of 1:5 and ground for 18 hours to obtain the final YBCO powder.
[0050] This invention provides a comparative example:
[0051] The preparation of YBCO powder material using solid-state fermentation for PVD target preparation includes the following steps:
[0052] Step 1: Weigh the raw materials according to the ratio of Y:Ba:Cu = 1:2:3. In order to reduce impurities, select Y2O3 with a purity of 99.999%, BaCO3 with a purity of 99.99%, and high-purity CuO with a purity of 99.95%.
[0053] Step 2: The weighed raw materials are homogenized into powder by wet ball milling with ethanol for 10 hours at a speed of 300 r / min.
[0054] Step 3: Place the mixed powder slurry obtained in Step 2 into a vacuum drying oven for drying at 80℃ for 24 hours;
[0055] Step 4: Sift the precursor powder obtained in Step 3;
[0056] Step 5: The powder obtained in Step 4 is subjected to a calcination treatment at a temperature of 900-920℃ for 24 hours.
[0057] Step 6: Ball mill the powder obtained in Step 5 for 4 hours;
[0058] Step 7: The powder obtained in Step 6 is subjected to a second calcination treatment at a temperature range of 900-920℃ for 24 hours.
[0059] Step 8: Grind and sieve the powder obtained in Step 7.
[0060] Comparative analysis of the embodiments and comparative examples:
[0061] First, the precursor powders obtained by ball milling and spray drying were subjected to ICP atomic ratio testing. The specific data are shown in Table 1. The data show that the atomic ratio stability of Y:Ba:Cu in the comparative example is worse than that in the example. This is mainly because the example achieves ionic-level uniform mixing through solution preparation, while the comparative example uses ball milling to mix the powder. The initial particle size of the powder determines the uniformity of mixing, which can only reach the micron level. Therefore, the atomic ratio stability of the YBCO precursor powder obtained in this example is better.
[0062] Table 1. ICP detection of precursor powders obtained by ball milling and spray drying.
[0063]
[0064] Second, comparing the preparation cycles of the comparative examples and the comparative examples, as shown in Table 2, for the same powder, the spray drying method took 48 hours to prepare YBCO powder, while the ball milling method took 95 hours. The former is approximately twice as efficient as the latter.
[0065] Table 2 Comparison of process times for solid-state and spray-drying methods
[0066]
[0067]
[0068] Third, please refer to Figure 2 and Figure 3 , Figure 2 To compare the XRD patterns of YBCO powder prepared in the examples and comparative examples, the XRD patterns of YBCO powder prepared by spray drying and YBCO powder prepared by ball milling are similar, indicating that the precursor powder prepared by spray drying has higher activity. A relatively pure YBCO phase can be obtained through a single calcination treatment. The reasons are as follows: First, as... Figure 3The microstructures of precursor powders prepared by ball milling and spray drying are compared. The left image shows the SEM image of the precursor powder prepared by the solid-state method, and the right image shows the SEM image of the precursor powder prepared by the spray drying method. The ball-milled powder has an irregular morphology and exhibits local agglomeration, requiring multiple grinding and calcination processes to achieve uniform calcination. In contrast, the spray-dried powder has an approximately spherical morphology, obtained through the evaporation of atomized droplets. Each microsphere has a nearly uniform composition, thus requiring only one calcination process. First, pure YBCO powder is obtained. Second, the decomposition temperature of barium carbonate used in the ball milling method is above 1000℃, so multiple calcinations are required for carbon removal and phase formation. The sintering temperature is 900-930℃, and the number of calcinations is 2-4 times. The decomposition temperature of barium nitrate is 500-600℃. In this embodiment, after two nitrogen removals, the N content was measured to be 0.12%. Therefore, the powder prepared by spray drying can be calcined at 800-900℃ to obtain pure YBCO powder, and the powder has high activity.
[0069] In summary, this invention has the following advantages: First, by using a solution method, this invention achieves uniform ion-level mixing, avoiding elemental segregation and improving the phase purity of the superconducting powder. In contrast, the uniformity of mixing in the solid-phase reaction method is limited by the particle size of the raw material powder and the ball milling process, resulting in a mixing particle size at the micrometer level. Second, compared to the barium carbonate raw material used in the solid-phase reaction method, this invention can significantly reduce the C content of the superconducting powder. The powder obtained by spray drying is nitrate, which does not contain C, and its decomposition temperature is much lower than that of barium carbonate. Nitrogen is discharged in gaseous form, and there is no N residue after high-temperature calcination. Third, by selecting oxygen-free copper with a purity of 99.99% instead of CuO with a purity of 99.5%, and using high-purity nitric acid and ammonia, the purity of the raw material is improved, thereby effectively reducing the content of harmful metal impurities (such as Ca, Al, Si, Fe, etc.) in the superconducting powder. Fourth, the powder of this invention has high reactivity and a relatively low calcination temperature, resulting in a short grinding time and a preparation cycle much shorter than that of the solid-phase reaction method, making it suitable for sintering into high-density target materials.
[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.
Claims
1. A method for batch preparation of high-purity, highly chemically active REBCO superconducting powder, characterized in that, It includes the following steps: S1. Using concentrated nitric acid with a mass concentration of 50%-70%, oxygen-free Cu, BaCO3, and Re2O3 with a purity greater than 99.99% are dissolved in a cation molar ratio of 1:2:3 to obtain a mixed nitrate aqueous solution of Re, Ba, and Cu. The pH of the mixed solution is then adjusted with deionized water and ammonia to 5-7, and the total concentration of metal cations is 0.2-0.5 mol / L. S2, a mixture of nitrates of Re, Ba and Cu is prepared from the mixed nitrate aqueous solution in step S1 using a spray drying device. The inlet air temperature of the spray drying device is 100-180℃ and the outlet air temperature is 60-80℃. S3, In a large-cavity box furnace with exhaust vents, flowed artificial air was introduced and the nitrate mixture in step S2 was calcined at a low temperature of 500-700℃ for 0.5-10h. After homogenization, intermediate powder with a particle size of 200-300 mesh was obtained. S4, the intermediate powder from step S3 is calcined at 800-900℃ for 10-24 hours in flowing artificial air or oxygen. After calcination, the powder is dry-milled in a ball mill for at least 15 hours to reduce the powder density. 50 Reduce the size to 1-2 μm. If necessary, repeat the calcination and homogenization process 2-3 times until no second phase is detected.
2. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S1, oxygen-free copper is selected as the raw material, and the purity of the raw material must be above 4N.
3. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S1, a slight excess of concentrated nitric acid is used to completely dissolve the raw materials, oxygen-free Cu, BaCO3, and Re2O3, in the nitric acid in sequence. Then, deionized water and ammonia are used to adjust the pH value and total concentration of metal cations in the solution.
4. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S1, the concentrated nitric acid and ammonia water used are both MOS grade, and the conductivity of the deionized water is no greater than 0.1 μs / cm.
5. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S2, the nitrate mixture is REBCO precursor powder.
6. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S2, the liquid inlet speed is set according to the equipment specifications. When using a 1.5L / h peristaltic pump, the liquid inlet speed needs to be maintained between 1.5 and 3.5L / h.
7. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S3, the homogenization process is performed by manual grinding or mechanical grinding, with a grinding time of 5-20 minutes, and the material is then passed through a 200-300 mesh sieve.
8. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S3, the thickness of the powder layer during calcination is no more than 1.5 cm.
9. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S3, the calcination and homogenization process can be repeated 1-2 times to completely denitrify the powder.
10. The method for batch preparation of high-purity, highly chemically active REBCO superconducting powder according to claim 1, characterized in that: In step S4, the homogenization process uses an all-around planetary ball mill for dry grinding, with a ball-to-material ratio of 1:3 to 1:5 and a rotation speed of 200 to 400 rpm.