Barium-copper oxide precursor for REBCO superconducting target material and preparation method and application of barium-copper oxide precursor

Abstract

The invention discloses a barium-copper oxide precursor for an REBCO superconducting target material and a preparation method and application thereof, the barium-copper oxide precursor comprises BaxCuyOz and a C impurity, the ratio of x to y is (0.5-0.83): 1, the ratio of (x + y) to z is 1: (0.9-1.1), and the content of the C impurity is less than or equal to 300 ppm. The content of C impurities in the barium-copper oxide precursor is smaller than or equal to 300 ppm, a foundation is laid for obtaining a high-performance and high-purity REBCO superconducting target material, the particle size and the specific surface area are appropriate, the reaction activity is high, the reaction temperature can be reduced to 880-930 DEG C in REBCO synthesis, the reaction temperature is far lower than the reaction temperature of a traditional solid phase method, reaction energy consumption is reduced, and Ba element volatilization is reduced.

Description

Technical Field

[0001] This invention belongs to the field of superconductor technology, specifically relating to a barium copper oxide precursor for REBCO superconducting targets, its preparation method, and its applications. Background Technology

[0002] Rare earth barium copper oxide (REBa2Cu3O) 7-δ REBCO (Reactive Borealis Co., or REBCO) superconducting materials, with their high critical temperature and strong current-carrying capacity, have become a highly commercially viable second-generation high-temperature superconducting material operating in the liquid nitrogen temperature range. REBCO superconducting tapes are commonly prepared using methods such as metal-organic chemical vapor deposition (MOCVD), metal-organic solution deposition (MOD), and pulsed laser deposition (PLD). Their performance largely depends on the purity, stoichiometric accuracy, and sintering activity of the REBCO superconducting powder used. These powders are also key raw materials for preparing high-performance physical vapor deposition (PVD) targets.

[0003] Currently, the mainstream method for preparing REBCO precursor powder in industry is still a solid-phase synthesis process based on oxides / carbonates. This involves repeatedly mixing, sintering, and crushing all the original powders containing the synthesized REBCO to obtain the target powder. This approach has inherent drawbacks: uneven micro-mixing easily induces the formation of impurity phases; the high-temperature, long-cycle process leads to high energy consumption, Ba volatilization, and loss of stoichiometry. Patent CN109678195A uses an improved two-step process, which preferentially prepares barium-copper compound powder through mechanical mixing and sintering, and then adds rare earth compounds in proportion, followed by multiple high-temperature sintering and crushing to obtain superconducting powder. Although this method optimizes the process, it still does not solve the core problem of "micro-scale mixing uniformity" and introduces new problems such as process complexity, high energy consumption, and susceptibility to pollution.

[0004] To improve uniformity, wet chemical methods (such as oxalate coprecipitation) have emerged. Although these methods have made progress in molecular-level mixing, they suffer from problems such as insufficient complexation stability under high concentrations of metal ions, high brittleness after gelation, high carbon residue, and severe powder agglomeration, which seriously limit superconducting performance.

[0005] Therefore, there is an urgent need to develop a REBCO superconducting target precursor powder with low C impurity content, precisely adjustable composition, high reactivity, and low preparation difficulty, so that it can reduce the synthesis temperature, improve purity, and enhance the performance of subsequent target materials when used to synthesize REBCO superconducting powder. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a barium copper oxide precursor for REBCO superconducting targets, its preparation method, and its uses. The barium copper oxide precursor for REBCO superconducting targets described in this application solves the problems of easy formation of impurity phases, difficulty in controlling elemental ratios, and high C impurity content during the preparation of REBCO superconducting targets in the prior art.

[0007] To achieve the above and other related objectives, the present invention is obtained through the following technical solution.

[0008] The first aspect of this invention discloses a barium copper oxide precursor for REBCO superconducting targets, the barium copper oxide precursor comprising: Ba x Cu y O z The content of C impurities is ≤300 ppm, with the ratio of x to y being (0.5~0.83):1 and the ratio of (x+y) to z being 1:(0.9~1.1).

[0009] Preferably, the ratio of x to y is (0.6~0.7):1.

[0010] In one specific implementation, the Ba x Cu y O z It is Ba3Cu5O8.

[0011] In one specific implementation, the Ba x Cu y O z Ba2Cu3O 5+δ .

[0012] Preferably, the D of the barium copper oxide precursor 50 The range is 0.2~1.5 µm.

[0013] Preferably, the specific surface area of ​​the barium copper oxide precursor is 5.5~15.5 m² / g.

[0014] The particle size and specific surface area within the above range ensure that the barium copper oxide precursor has both good dispersibility and high reactivity.

[0015] A second aspect of this invention discloses a method for preparing a barium copper oxide precursor for REBCO superconducting targets. The preparation method is a wet process and specifically includes the following steps:

[0016] 1) Dissolve the soluble salts of Ba and Cu in water according to the specified ratio and adjust the pH to 5-8 to obtain a mixed solution;

[0017] 2) Add a complexing agent to the mixture and stir to obtain a wet gel;

[0018] 3) Dry the wet gel to obtain a dry gel, then crush it and pre-calcine it. The pre-calcine step includes heating to 300~500℃ and holding at that temperature.

[0019] 4) The pre-calcined product is heat-treated to crystallize, and the barium copper oxide precursor is obtained. During crystallization, the heat treatment includes heating to 750-880°C at a rate of 1-5°C / min and holding at that temperature.

[0020] Preferably, in step 1), the soluble salt is selected from one or more of nitrates, acetates, and chlorides.

[0021] Preferably, in step 1), the soluble salts corresponding to Ba and Cu are barium acetate and copper nitrate, respectively.

[0022] Preferably, in step 1), the Ba in the mixture 2+ and Cu 2+ The sum of the concentrations is 0.1~1 mol / L. If the sum of the concentrations is less than 0.1 mol / L, the solution volume will be too large, increasing the energy consumption of subsequent drying and pre-calcination steps; if it is greater than 1 mol / L, the complexation stability of the metal elements during stirring will decrease, increasing the experimental cost and reducing the accuracy of the experiment.

[0023] Preferably, in step 1), the solution used to adjust the pH is selected from ammonia.

[0024] Preferably, in step 2), the complexing agent is selected from one or more of citric acid, malic acid, succinic acid, aminotriacetic acid, tartaric acid, gluconic acid, ethylenediamine, diethylenetriamine, triethanolamine, ethylenediaminetetraacetic acid, acetylacetone, ethyl acetoacetate, and 8-hydroxyquinoline.

[0025] More preferably, the complexing agent is a compound of citric acid and ethylenediaminetetraacetic acid mixed in a mass ratio of (1~3):1;

[0026] More preferably, the complexing agent is malic acid and glycerol in a mass ratio of (2~5):1.

[0027] Preferably, in step 2), the Ba in the mixture 2+ and Cu 2+ The metal ion is used, and the molar ratio of the metal ion to the complexing agent is 1:(1.5~3).

[0028] Preferably, in step 2), the stirring temperature is 60~90℃.

[0029] Preferably, in step 3), the drying temperature is 80~120℃.

[0030] Preferably, in step 3), the drying time is 12 to 48 hours.

[0031] In one specific embodiment, the dried wet gel is bluish-black.

[0032] Preferably, in step 3), the particle size of the crushed product is less than 1.5 μm.

[0033] Preferably, in step 3), the heat preservation time in the pre-calcination step is 2-4 hours.

[0034] The heat treatment fully crystallizes the product, yielding the final black barium copper oxide precursor powder.

[0035] Preferably, in step 4), the heat preservation time during crystallization is 12 to 24 hours.

[0036] Preferably, in step 4), the heat treatment is carried out in an air or oxygen atmosphere during crystallization.

[0037] More preferably, the air is flowing air.

[0038] Preferably, step 3) is carried out in an air or oxygen atmosphere.

[0039] The third aspect of the present invention discloses the use of the barium copper oxide precursor described above as a raw material for REBCO superconducting powder.

[0040] The fourth aspect of this invention discloses a method for preparing REBCO superconducting powder, the method comprising the following steps: mixing the barium copper oxide precursor as described above with rare earth oxides, barium source and copper source to obtain a mixture and sintering it.

[0041] Preferably, the rare earth element in the rare earth oxide is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y.

[0042] In one specific embodiment, the rare earth oxide is selected from one or more of La2O3, CeO2, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Y2O3, and Sc2O3.

[0043] Preferably, the barium source is selected from one or more of BaCO3, Ba(CH3COO)2, and Ba(NO3)2.

[0044] Preferably, the copper source is selected from one or more of CuO, Cu(CH3COO)2, and Cu(NO3)2.

[0045] Preferably, when the rare earth element is Gd, the molar ratio of the rare earth element to Ba and Cu in the mixture is 1:2:3.

[0046] Preferably, the sintering temperature is 890~930℃.

[0047] Preferably, the sintering time is 10 to 18 hours.

[0048] The fifth aspect of this invention discloses the use of REBCO superconducting powder obtained by the preparation method described above as a raw material for preparing superconducting targets.

[0049] In one specific embodiment, the REBCO superconducting powder is used as a raw material to prepare a superconducting target for physical vapor deposition. The resulting REBCO superconducting material can be used in superconductivity, medical, aerospace, and precision testing fields. More specifically, it can be used in superconducting cables, medical CT scanners, aerospace engines, quantum interferometers, etc.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1) In this application, the ratio of Ba to Cu is precisely controllable through wet chemical method, which improves the microscale mixing uniformity and allows for flexible adjustment of element ratios to synthesize a variety of stable precursors according to actual needs.

[0052] 2) This application will adopt the "pre-calcination" step to effectively remove the complexing agent, so that the C impurity content in the precursor is ≤300ppm, the specific surface area is large, and the reaction driving force is large, laying the foundation for obtaining high-performance and high-purity REBCO superconducting target materials.

[0053] 3) The barium copper oxide precursor described in this application has suitable particle size and specific surface area and high reactivity, which enables it to reduce the reaction temperature to 880~930℃ and shorten the reaction time to 10~18 hours in REBCO synthesis. The overall energy consumption is much lower than that of the traditional solid-phase method, which improves the reaction efficiency and reduces the volatilization of rare earth elements (such as Ba).

[0054] 4) The preparation method of the barium copper oxide precursor described in this application is simple and easy to control, with good reproducibility, and it is easy to repeatedly prepare products with the same quality and performance. The reaction efficiency is high, thus meeting the needs of large-scale stable industrial production. Attached Figure Description

[0055] Figure 1 The image shows the XRD pattern of the GBCO superconducting powder described in Example 1.

[0056] Figure 2 The image shows the XRD pattern of the GBCO superconducting powder described in Example 2.

[0057] Figure 3 The image shows the XRD pattern of the YBCO superconducting powder described in Comparative Example 1.

[0058] Figure 4 The image shows the XRD pattern of the GBCO superconducting powder described in Comparative Example 2. Detailed Implementation

[0059] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0060] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0061] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0062] In this application, the applicant addresses the problems of impurity phase formation, difficulty in controlling elemental ratios, and high C impurity content in the preparation of REBCO superconducting targets using existing technologies. The applicant provides a barium copper oxide precursor for REBCO superconducting targets, its preparation method, and its applications. The barium copper oxide precursor described in this application has a suitable specific surface area and high reactivity, enabling it to reduce the reaction temperature to 880-930℃ and shorten the reaction time to 10-18 hours in REBCO synthesis. The overall energy consumption is significantly lower than that of traditional solid-state methods. It exhibits uniform mixing at the microscale, and a relatively pure product can be achieved in a short time at low temperatures. Furthermore, compared to existing wet preparation methods, it offers higher purity and a suitable particle size.

[0063] The barium copper oxide precursor includes: Ba x Cu y O zThe carbon impurity content is ≤300 ppm, with the x to y ratio being (0.5~0.83):1 and the (x+y) to z ratio being 1:(0.9~1.1). This lays the foundation for obtaining high-performance, high-purity REBCO superconducting targets.

[0064] Specifically, this embodiment of the invention provides a specific barium copper oxide precursor. The barium copper oxide precursor comprises: Ba x Cu y O z The content of C impurities is ≤300 ppm. The ratio of x to y is (0.5~0.83):1, and the ratio of (x+y) to z is 1:(0.9~1.1). The x to y ratio can be (0.5~0.55):1, (0.55~0.6):1, (0.6~0.65):1, (0.65~0.7):1, (0.7~0.75):1, (0.75~0.8):1, or (0.8~0.83):1. The ratio of (x+y) to z can be 1: (0.9~0.92), 1: (0.92~0.94), 1: (0.94~0.96), 1: (0.96~0.98), 1: (0.98~1), 1: (1~1.02), 1: (1.02~1.04), 1: (1.04~1.06), 1: (1.06~1.08), 1: (1.08~1.1).

[0065] The C impurity content can be 50~100 ppm, 100~150 ppm, 150~200 ppm, 200~220 ppm, 220~250 ppm, 250~254 ppm, or 254~300 ppm.

[0066] In one specific embodiment, the molar ratio of Ba to Cu is 0.6:1, and the Ba x Cu y O z It is Ba3Cu5O8.

[0067] In one specific embodiment, the molar ratio of Ba to Cu is 2:3, and the Ba x Cu y O z Ba2Cu3O 5+δ .

[0068] During the preparation of the barium copper oxide precursor, due to factors such as oxygen atmosphere control during heat treatment, raw material metering accuracy, and the non-equilibrium state of crystal growth, its chemical composition will exhibit slight non-stoichiometric fluctuations, resulting in elemental content fluctuations within a reasonable range for the final product. In this application, δ refers to the non-stoichiometric fluctuation value, which ranges from 0.02 to 0.1. The value of δ does not affect the intergranular spacing and core performance of Ba2Cu3O. 5+δ It has a basically the same effect as Ba2Cu3O5.

[0069] In one specific embodiment, the D of the barium copper oxide precursor 50 The value is 0.2~1.5 µm. The D of the barium copper oxide precursor as described above... 50 Can be 0.2~0.3 µm, 0.3~0.4 µm, 0.4~0.5 µm, 0.5~0.6 µm, 0.6~0.7 µm, 0.7~0.8 µm, 0.8~0.9 µm, 0.9~1.0 µm, 1.0~1.1 µm, 1.1~1.2 µm, 1.2~1.3 µm, 1.3~1.4 µm, 1.4~1.5 µm.

[0070] In one specific embodiment, the specific surface area of ​​the barium copper oxide precursor is 5.5~15.5 m² / g. The specific surface area of ​​the barium copper oxide precursor can be 5.5~7.5 m² / g, 7.5~8.6 m² / g, 8.6~9.5 m² / g, 9.5~10.5 m² / g, 10.5~11.6 m² / g, 11.6~13.5 m² / g, or 13.5~15.5 m² / g.

[0071] The particle size and specific surface area within the above range ensure that the barium copper oxide precursor has both good dispersibility and high reactivity.

[0072] This invention also provides a specific method for preparing a barium copper oxide precursor, which is a wet process and specifically includes the following steps:

[0073] 1) Dissolve the soluble salts of Ba and Cu in water according to the specified ratio and adjust the pH to 5-8 to obtain a mixed solution;

[0074] 2) Add a complexing agent to the mixture and stir to obtain a wet gel;

[0075] 3) Dry the wet gel to obtain a dry gel, then crush it and pre-calcine it. The pre-calcine step includes heating to 300~500℃ and holding at that temperature.

[0076] 4) The pre-calcined product is heat-treated to crystallize, and the barium copper oxide precursor is obtained. During crystallization, the heat treatment includes heating to 750-880°C at a rate of 1-5°C / min and holding at that temperature.

[0077] As described in step 1), the pH can be 5~5.5, 5.5~6, 6~6.5, 6.5~7, 7~7.5, or 7.5~8.

[0078] As described in step 3), the temperature for heating and holding can be 300~350℃, 350~400℃, 400~450℃, or 450~500℃. If the temperature is too high, the organic components will decompose too quickly and cannot diffuse from the product, resulting in residual C impurities.

[0079] As described in step 4), during crystallization, the heating rate of the heat treatment can be 1~2℃ / min, 2~3℃ / min, 3~4℃ / min, or 4~5℃ / min.

[0080] As described in step 4), during crystallization, the heat treatment holding temperature can be 750~770℃, 770~790℃, 790~800℃, 800~820℃, 820~840℃, 840~860℃, or 860~880℃.

[0081] In one specific embodiment, the pH of 5-8 in step 1) allows the mixture to better crosslink to form a colloid during subsequent gelation.

[0082] In one specific embodiment, in step 2), a complexing agent is added to the mixture and stirred. The solution gradually changes to a sol state, and then to a gel state as stirring continues.

[0083] In one specific embodiment, in step 3), the holding temperature of 300~500℃ completely removes the organic components from the crushed dry gel, avoiding carbon pollution during subsequent high-temperature treatment. If the pre-calcination temperature is below 300℃, the organic complexing agent will not decompose completely, and the carbon residue will often be >0.5%; if it is above 500℃, the precursor particles are prone to sintering and agglomeration, resulting in insufficient phase purity during subsequent crystallization.

[0084] In one specific embodiment, in step 4), the heating rate of 1~5℃ / min ensures that the barium salt in the product is completely decomposed into oxide. If the heating rate is too fast, the barium salt cannot be completely decomposed into oxide; if the heating rate is too slow, energy consumption increases.

[0085] In one specific embodiment, in step 1), the soluble salt is selected from one or more of nitrates, acetates, and chlorides.

[0086] In a more specific embodiment, the soluble salts corresponding to Ba and Cu are barium acetate and copper nitrate, respectively. If both are acetates, the specific surface area is too small, which is not conducive to subsequent reactions; if both are nitrates, the specific surface area is too large, increasing the difficulty of process operation and resulting in higher nitrogen residue.

[0087] In one specific embodiment, in step 1), the Ba in the mixture 2+ and Cu 2+ The sum of the concentrations should be 0.1–1 mol / L. For example, it could be 0.1–0.3 mol / L, 0.3–0.5 mol / L, 0.5–0.7 mol / L, or 0.7–1.0 mol / L. If the sum of the concentrations is below 0.1 mol / L, the solution volume will be too large, increasing the energy consumption of subsequent drying and pre-calcination steps; if it is above 1 mol / L, the residual loss of metal elements during stirring will be significant, increasing experimental costs and decreasing experimental accuracy.

[0088] In one specific embodiment, in step 1), the pH-adjusting solution is selected from ammonia water. The pH-adjusting solution has a low thermal decomposition temperature and is easily removed through a pre-calcination step, reducing the impurity content in the final product.

[0089] In one specific embodiment, in step 2), the complexing agent is selected from one or more of citric acid, malic acid, succinic acid, aminotriacetic acid, tartaric acid, gluconic acid, ethylenediamine, diethylenetriamine, triethanolamine, ethylenediaminetetraacetic acid, acetylacetone, ethyl acetoacetate, and 8-hydroxyquinoline.

[0090] In a more specific embodiment, the complexing agent is a complex of citric acid and ethylenediaminetetraacetic acid, wherein the mass ratio of citric acid to ethylenediaminetetraacetic acid is (1~3):1.

[0091] In a more specific embodiment, the complexing agent is a complex of malic acid and glycerol, wherein the mass ratio of malic acid to glycerol is (2~5):1.

[0092] The aforementioned complexing agent has a low thermal decomposition temperature, making it easy to remove through a pre-calcination step, thereby reducing the C impurity content in the final product and not introducing other impurities such as N.

[0093] In one specific embodiment, in step 2), the Ba in the mixture 2+ and Cu 2+ The metal ion is present, and the molar ratio of the metal ion to the complexing agent is 1:(1.5~3). For example, it can be 1:(1.5~2), 1:(2~2.5), or 1:(2.5~3).

[0094] In one specific embodiment, in step 2), the stirring temperature is 60~90℃.

[0095] In one specific embodiment, in step 3), the drying temperature is 80~120℃.

[0096] In one specific embodiment, in step 3), the drying time is 12 to 48 hours.

[0097] In one specific embodiment, in step 3), the dried wet gel is blue-black.

[0098] In one specific embodiment, in step 3), the particle size of the crushed product is less than 1.5 μm.

[0099] In one specific embodiment, in step 3), the heat preservation time in the pre-calcination step is 2~4h.

[0100] In one specific embodiment, during crystallization, the heat treatment fully crystallizes the product to obtain the final black barium copper oxide precursor powder.

[0101] In one specific embodiment, during step 4), the heat preservation time is 12 to 24 hours during crystallization.

[0102] In one specific embodiment, during step 4), the heat treatment is carried out in an air or oxygen atmosphere during crystallization.

[0103] In a more specific embodiment, the air is flowing air.

[0104] The present invention also provides the use of the barium copper oxide precursor as described above as a raw material for REBCO superconducting powder.

[0105] The present invention also provides a method for preparing REBCO superconducting powder, the method comprising the following steps: mixing the barium copper oxide precursor as described above with rare earth oxides, barium source and copper source to obtain a mixture and sintering it.

[0106] In one specific embodiment, the rare earth element in the rare earth oxide is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y.

[0107] In one specific embodiment, the rare earth oxide is selected from one or more of La2O3, CeO2, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Y2O3, and Sc2O3.

[0108] In one specific embodiment, the barium source is selected from one or more of BaCO3, Ba(CH3COO)2, and Ba(NO3)2.

[0109] In one specific embodiment, the copper source is selected from one or more of CuO, Cu(CH3COO)2, and Cu(NO3)2.

[0110] In one specific embodiment, when the rare earth element is Gd, the molar ratio of the rare earth element to Ba and Cu in the mixture is 1:2:3.

[0111] In one specific embodiment, the sintering temperature is 880~930℃.

[0112] In one specific embodiment, the sintering time is 10 to 18 hours.

[0113] The present invention also provides the use of the REBCO superconducting powder as described above as a raw material for preparing superconducting targets.

[0114] In one specific embodiment, the REBCO superconducting powder is used as a raw material to prepare a superconducting target for physical vapor deposition. The resulting REBCO superconducting material can be used in superconducting, medical, aerospace, and precision testing fields. More specifically, it can be used in superconducting cables, medical CT scanners, aerospace engines, quantum interferometers, etc.

[0115] The following embodiments of this application:

[0116] The D 50 Obtained through testing with a Malvern Mastersizer 3000 instrument.

[0117] The specific surface area was calculated using the BET method, and the testing instrument was an Anton Paconta Autosorb-IQ3.

[0118] The C impurity content was obtained by testing with a Bucker G4 ICARUS HF instrument. It should be noted that the REBCO superconducting target includes REBCO series superconducting materials such as GBCO, YBCO, and SmBCO. The barium copper oxide precursor described in this application is applicable to any REBCO series superconducting material.

[0119] Example 1

[0120] This embodiment provides a barium copper oxide precursor for REBCO superconducting targets and its preparation method. The barium copper oxide precursor is a Ba2Cu3O5 precursor with a C impurity content of 254 ppm and an average particle size (D). 50 The specific surface area of ​​BET is 0.4 µm and 11.6 m² / g.

[0121] The preparation method includes the following steps:

[0122] 1) Dissolve barium acetate and copper nitrate in a 2:3 molar ratio to prepare a 0.5 mol / L solution. Adjust the pH to 6.5 with ammonia water to obtain a mixed solution.

[0123] 2) Add a complexing agent to the solution in the mixed solution at a molar ratio of metal ion: complexing agent = 1:2, stir in an 80°C water bath to form a gray-blue sol, which then turns into a wet gel; the complexing agent is a compound of citric acid and ethylenediaminetetraacetic acid mixed at a mass ratio of 1.5:1.

[0124] 3) The wet gel was dried at 120℃ for 24 hours to obtain a blue-black dry gel. The dry gel was simply pulverized and then ground in a high-energy ball mill for 10 minutes to obtain a matte dark blue-black powder. The powder was then heated to 400℃ at a rate of 2℃ / min and held at that temperature for 2 hours.

[0125] 4) The temperature was increased to 820℃ at a rate of 3℃ / min and held for 3 hours to obtain black Ba2Cu3O. 5+δ Precursor powder.

[0126] According to the above detection method, the barium copper oxide precursor is a Ba2Cu3O5 precursor with a C impurity content of 254 ppm; the average particle size (D) 50 The specific surface area of ​​BET is 0.4 µm and 11.6 m² / g.

[0127] This embodiment also provides a method for preparing REBCO superconducting powder, wherein the REBCO superconducting powder is GBCO, and the preparation method includes the following steps: mixing the above precursor with Gd2O3, BaCO3 and CuO in a total amount of Gd:Ba:Cu=1:2:3, and sintering in an oxygen atmosphere at 900°C for 10 hours.

[0128] Obtained through XRD testing Figure 1 ,like Figure 1 As shown, the GdBa2Cu3O prepared in this embodiment is pure GdBa2Cu3O 7-δ Phase (G123), without impurity phase peaks.

[0129] Example 2

[0130] This embodiment provides a barium copper oxide precursor for REBCO superconducting targets and its preparation method. The barium copper oxide precursor is a Ba3Cu5O8 precursor with a C impurity content of 220 ppm and an average particle size (D). 50 The specific surface area of ​​BET is 8.6 m² / g, with a diameter of 0.6 µm.

[0131] The preparation method includes the following steps:

[0132] 1) Dissolve barium acetate and copper nitrate in a 3:5 molar ratio to prepare a 0.5 mol / L solution. Adjust the pH to 6.5 with ammonia water to obtain a mixed solution.

[0133] 2) Add a complexing agent to the solution in the mixed solution at a molar ratio of metal ion: complexing agent = 1:2, stir in an 80°C water bath to form a gray-blue sol, which then turns into a wet gel; the complexing agent is a compound of malic acid and glycerol mixed at a mass ratio of 3.5:1.

[0134] 3) The wet gel was dried at 120℃ for 24 hours to obtain a blue-black dry gel. The dry gel was simply pulverized and then ground in a high-energy ball mill for 10 minutes to obtain a matte dark blue-black powder. The powder was then heated to 400℃ at a rate of 2℃ / min and held at that temperature for 2 hours.

[0135] 4) The temperature was increased to 800℃ at 3℃ / min and held for 3 hours to obtain black Ba3Cu5O8 precursor powder.

[0136] According to the above detection method, the barium copper oxide precursor is Ba3Cu5O8 precursor, and the C impurity content is 220ppm; the average particle size (D) 50 The specific surface area of ​​BET is 8.6 m² / g, with a diameter of 0.6 µm.

[0137] This embodiment also provides a method for preparing REBCO superconducting powder, wherein the REBCO superconducting powder is GBCO, and the preparation method includes the following steps: mixing the above precursor with Gd2O3, BaCO3 and CuO in a total amount of Gd:Ba:Cu=1:2:3, and sintering in an oxygen atmosphere at 930°C for 12 hours.

[0138] Obtained through XRD testing Figure 2 .like Figure 2 As shown, the GdBa2Cu3O prepared in this embodiment is pure GdBa2Cu3O 7-δ Phase (G123), without impurity phase peaks.

[0139] Comparative Example 1

[0140] In this comparative example, a barium copper oxide precursor for REBCO superconducting targets and its preparation method are provided. The barium copper oxide precursor is a Ba3Cu5O8 precursor with a C impurity content of 520 ppm and an average particle size (D). 50 The specific surface area of ​​BET is 0.8 µm; the specific surface area of ​​BET is 6.1 m² / g.

[0141] The difference between the preparation method described above and Example 2 is that in step 3), the temperature is increased to 600°C at a rate of 2°C / min.

[0142] This comparative example also provides a method for preparing REBCO superconducting powder, wherein the REBCO superconducting powder is YBCO, and the preparation method includes the following steps: mixing the above precursor with Y2O3, BaCO3 and CuO in a total quantity of Y:Ba:Cu=1:2:3, and sintering in an oxygen atmosphere at 930°C for 16 hours.

[0143] Obtained through XRD testing Figure 3 .like Figure 3 As shown, the superconducting powder prepared in this comparative example contains obvious Y2BaCuO5 (Y211) and BaCuO2 impurity phase peaks.

[0144] Comparative Example 2

[0145] This comparative example provides a method for preparing REBCO superconducting powder, which is a dry chemical method, including the following steps: Gd2O3, BaCO3, and CuO are ground and mixed in a stoichiometric ratio of Gd:Ba:Cu=1:2:3, and sintered in an oxygen atmosphere at 980℃ for 12 hours, and the process is repeated twice.

[0146] Obtained by XRD Figure 4 ,like Figure 4 As shown, the superconducting powder prepared in this comparative example exhibits a distinct Gd2BaCuO5 (G211) impurity phase peak.

[0147] As can be seen, the barium copper oxide precursor obtained by the preparation method of this application has a C impurity content of ≤300 ppm. In the subsequent preparation of REBCO superconducting powder, a significantly higher purity REBCO superconducting powder was obtained compared with comparative examples 1 to 2.

[0148] This invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0149] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A barium copper oxide precursor for REBCO superconducting targets, characterized in that, The barium copper oxide precursor includes: Ba x Cu y O z The content of C impurities is ≤300 ppm, with the ratio of x to y being (0.5~0.83):1 and the ratio of (x+y) to z being 1:(0.9~1.1).

2. The barium copper oxide precursor according to claim 1, characterized in that, The barium copper oxide precursor D 50 The range is 0.2~1.5 µm; And / or, the specific surface area of ​​the barium copper oxide precursor is 5.5~15.5 m² / g.

3. A method for preparing the barium copper oxide precursor as described in any one of claims 1 to 2, characterized in that, The preparation method is a wet process, which specifically includes the following steps: 1) Dissolve the soluble salts of Ba and Cu in water according to the specified ratio and adjust the pH to 5-8 to obtain a mixed solution; 2) Add a complexing agent to the mixture and stir to obtain a wet gel; 3) Dry the wet gel to obtain a dry gel, then crush it and pre-calcine it. The pre-calcine step includes heating to 300~500℃ and holding at that temperature. 4) The pre-calcined product is heat-treated to crystallize, and the barium copper oxide precursor is obtained. During crystallization, the heat treatment includes heating to 750-880°C at a rate of 1-5°C / min and holding at that temperature.

4. The preparation method according to claim 3, characterized in that, In step 1), the soluble salt is selected from one or more of nitrates, acetates, and chlorides; And / or, in step 1), the mixture contains Ba 2+ and Cu 2+ The sum of their concentrations is 0.1~1 mol / L; And / or, in step 1), the solution used to adjust the pH is selected from ammonia water; And / or, the complexing agent is selected from one or more of citric acid, malic acid, succinic acid, aminotriacetic acid, tartaric acid, gluconic acid, ethylenediamine, diethylenetriamine, triethanolamine, ethylenediaminetetraacetic acid, acetylacetone, ethyl acetoacetate, and 8-hydroxyquinoline; And / or, in step 2), the Ba in the mixture 2+ and Cu 2+ The metal ion is used, and the molar ratio of the metal ion to the complexing agent is 1:(1.5~3); And / or, in step 2), the stirring temperature is 60~90℃.

5. The preparation method according to claim 4, characterized in that, The soluble salts corresponding to Ba and Cu are barium acetate and copper nitrate, respectively. And / or, the complexing agent is a compound of citric acid and ethylenediaminetetraacetic acid mixed in a mass ratio of (1~3):1; And / or, the complexing agent is malic acid and glycerol in a mass ratio of (2~5):

1.

6. The preparation method according to claim 3, characterized in that, The drying temperature is 80~120℃; And / or, the drying time is 12 to 48 hours; And / or, in step 3), the particle size of the crushed product is less than 1.5 μm; And / or, in step 3), the heat preservation time in the pre-calcination step is 2 to 4 hours; And / or, in step 3), the heating rate of the pre-calcination is 1~3℃ / min; And / or, in step 4), during crystallization, the heat preservation time is 12-24 hours; And / or, in step 4), during crystallization, the heat treatment is carried out in an air or oxygen atmosphere.

7. Use of the barium copper oxide precursor as described in any one of claims 1 to 2 as a raw material for REBCO superconducting powder.

8. A method for preparing REBCO superconducting powder, the method comprising the following steps: mixing the barium copper oxide precursor as described in any one of claims 1 to 2 with rare earth oxides, a barium source, and a copper source to obtain a mixture and sintering it.

9. The preparation method according to claim 8, characterized in that, The barium source is selected from one or more of BaCO3, Ba(CH3COO)2, and Ba(NO3)2; And / or, the copper source is selected from one or more of CuO, Cu(CH3COO)2, and Cu(NO3)2; And / or, the rare earth element in the rare earth oxide is selected from one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y; And / or, the sintering temperature is 880~930℃; And / or, the sintering time is 10 to 18 hours; And / or, when the rare earth element is Gd, the molar ratio of the rare earth element to Ba and Cu in the mixture is 1:2:

3.

10. The use of REBCO superconducting powder obtained by the preparation method according to any one of claims 8 to 9 as a raw material for preparing superconducting targets.

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