A method for preparing BHO-doped ErBCO superconducting target material by plasma jet pyrolysis-gas quenching continuous powdering and flash burning

Abstract

The application discloses a kind of plasma jet pyrolysis-gas quenching continuous powder preparation and flash burning preparation BHO doped ErBCO superconducting target material method, belong to superconducting material technical field.The application first adopts hydrothermal method to prepare the BaHfO3 (BHO) nanocrystal of grain size 10~30 nm, after ultrasonic dispersion, it is added in acetic acid precursor solution;Doped precursor liquid is atomized after atomizer and is sprayed into radio frequency plasma area, and one step is completed simultaneously heat decomposition and melting spheroidization, then gas quenching, obtain spherical degree ≥0.95, average particle size 50~200 nm ErBCO / BHO composite powder;After composite powder is formed into shape, using flash burning technology is densified at 750~950 ℃, electric field intensity 100~500 V / cm condition, finally after oxygen permeation treatment obtains ErBCO / BHO superconducting target material.The application realizes from BHO nanocrystal prefabrication to powder spheroidization again to target material densification whole process integration, the prepared target material relative density ≥98%, grain size ≤8 μm, with good superconducting performance.

Description

Technical Field

[0001] This invention belongs to the field of superconducting materials technology, and specifically relates to a method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching rapid cooling continuous powdering and flash sintering. Background Technology

[0002] ErBa2Cu3O 7-δ ErBCO (0<δ<1) high-temperature superconducting materials possess excellent properties such as high critical temperature (Tc) (approximately 92~94 K), high critical current density, and strong magnetic flux pinning ability, making them one of the core materials for second-generation high-temperature superconducting tapes and thin films. ErBCO superconducting targets are key raw materials for the preparation of ErBCO thin films by magnetron sputtering and pulsed laser deposition (PLD), and their quality directly determines the superconducting properties of the film. However, the preparation of existing ErBCO targets mainly adopts the traditional solid-state reaction method, which requires multiple grinding and long-term high-temperature calcination (>900℃, >24 h). The resulting powder has a wide particle size distribution (usually 1~10 μm) and irregular morphology, resulting in low target density (usually <92%), coarse grains (>10 μm), and is prone to introducing impurities and causing compositional deviations.

[0003] Introducing artificial pinning centers is an effective way to improve the critical current density of superconducting materials under an applied magnetic field. BaHfO3 (BHO) is a perovskite-structured oxide ceramic material with advantages such as a high melting point (approximately 2600℃), high chemical stability, and good lattice matching with the REBCO matrix. It has been proven to form efficient flux pinning centers in YBCO thin films. However, existing BHO doping techniques are all applied to superconducting thin films and have not yet been used in the preparation of superconducting targets. In current target preparation, BHO nanocrystals are usually added by mechanical mixing (e.g., CN114105631A – a method for preparing rare earth barium copper oxide superconducting targets). This method is difficult to achieve uniform dispersion of nanocrystals in micron-sized ErBCO powder and easily destroys the nanoscale effect of BHO. Therefore, how to achieve uniform and stable doping of BHO nanocrystals during target preparation is a technical challenge.

[0004] Powder morphology has a decisive influence on the densification of target materials during sintering. However, the irregular morphology and poor flowability of powders obtained by traditional solid-state methods are one of the main reasons for the low density of target materials (CN119663197A—A High-Density FeSe). 1-x Te x(Patent on the preparation method of superconducting target material). Spray pyrolysis technology can introduce metal salt solution into a high-temperature atmosphere in a micro-mist state, and prepare fine powder through solvent evaporation, thermal decomposition, sintering and other processes. The resulting particles are generally regular spherical, with little agglomeration, and do not require subsequent grinding, which can ensure high purity, high activity and uniform particle size of the product. However, the powder obtained by conventional spray pyrolysis often has hollow or broken structure, and the degree of densification is still not ideal (e.g. CN114974723A - A method for preparing Bi-2212 superconducting powder with controllable second phase).

[0005] Traditional pressureless sintering requires prolonged holding at high temperatures (>950℃) (>24 h), resulting in high energy consumption, low efficiency, and a tendency to cause grain enlargement, Ba and Cu volatilization, and disruption of the stoichiometry of the superconducting phase. While spark plasma sintering (SPS) can shorten sintering time, the equipment is expensive and mold consumption is high, hindering large-scale production (e.g., CN102615280A – A method for preparing iron-based superconductors using SPS technology). Flash sintering is a revolutionary electric field-assisted sintering technique that can achieve densification within seconds to minutes at temperatures below 1000℃, offering significant advantages such as low sintering temperature, high speed, low energy consumption, and grain refinement. However, existing flash sintering techniques are mainly applied to structural ceramics and solid oxide fuel cells (e.g., CN121318430A – A vertical sintering method for improving the compositional uniformity of EuBCO high-temperature superconducting targets), and its application in the preparation of ErBCO / BHO superconducting targets has not yet been reported. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method for preparing BHO-doped ErBCO superconducting targets through plasma jet pyrolysis-gas quenching and flash sintering. The method first uses a hydrothermal method to prepare pre-formed BHO nanocrystals, which are then uniformly dispersed in an acetic acid precursor solution. These nanocrystals are then atomized and sprayed into the radio frequency plasma region via an atomizer. In the high-temperature plasma region, thermal decomposition and melt spheroidization are simultaneously completed in one step, yielding ErBCO / BHO composite powder with high sphericity, nanocrystalline structure, and uniform BHO dispersion. This powder is then subjected to molding and flash sintering for densification, resulting in a highly dense, fine-grained superconducting target.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing BHO-doped ErBCO superconducting targets through plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) BHO (BaHfO3) nanocrystals were prepared by hydrothermal method, and the BHO nanocrystals were ultrasonically dispersed in a dispersion medium to obtain a BHO nanocrystal dispersion. (2) Preparation of ErBCO (ErBa2Cu3O) 7-δ The acetic acid precursor solution with δ=0.3) was prepared by adding the BHO nanocrystal dispersion obtained in step (1) to the acetic acid precursor solution, stirring continuously and sonicating to obtain the BHO doped precursor solution. (3) The BHO doped precursor liquid obtained in step (2) is atomized and the carrier gas carries the atomized droplets into the radio frequency plasma region. The thermal decomposition reaction and melting spheroidization are completed simultaneously in the high temperature region of the plasma. Then, it is quenched in the cooling chamber and collected to obtain ErBCO / BHO composite powder. (4) The ErBCO / BHO composite powder obtained in step (3) is molded to obtain a target blank; (5) Place the target blank obtained in step (4) in a flash furnace and apply an electric field to flash densify it to obtain ErBCO / BHO superconducting target blank; (6) The ErBCO / BHO superconducting target blank obtained in step (5) is subjected to oxygen permeation treatment to obtain BHO-doped ErBCO superconducting target, denoted as ErBCO / BHO superconducting target.

[0008] This invention employs an "atomization-plasma jet pyrolysis" technology, atomizing the precursor solution and then jetting it into the radio frequency plasma region. Thermal decomposition and melting / spheroidization are simultaneously completed in one step within the high-temperature plasma region, eliminating the need for a separate tubular pyrolysis furnace beforehand. The particles produced by this technology are generally regularly spherical with minimal agglomeration, requiring no subsequent grinding and ensuring high purity, high activity, and uniform particle size. The ErBCO / BHO superconducting target obtained using this method exhibits a relative density ≥98%, an average grain size ≤8 μm (preferably 3.8 μm~7.3 μm), and a zero-resistance temperature (Tc0) ≥90 K.

[0009] Further, in step (1), the steps for preparing BHO nanocrystals by hydrothermal method are as follows: barium acetate and hafnium chloride are dissolved in water at a molar ratio of 1:1, the pH is adjusted to alkaline, and the mixture is stirred to form a uniform precursor solution; the precursor solution is subjected to a hydrothermal reaction, and after the reaction is completed, it is naturally cooled, centrifuged to separate the precipitate, and after washing and drying, BHO nanocrystals are obtained.

[0010] Further, in step (1), the grain size of the BHO nanocrystals is 10~30 nm; the dispersion medium is anhydrous ethanol; the dispersant is polyvinylpyrrolidone; and the concentration of BHO nanocrystals in the BHO nanocrystal dispersion is 0.5~5 mg / mL.

[0011] Further, in step (2), the method for preparing the acetic acid precursor solution of ErBCO is as follows: Erbium acetate, barium acetate and copper acetate are dissolved in a mixed solvent of water and glacial acetic acid according to the molar ratio of Er:Ba:Cu=1:2:3 to prepare a solution with a total metal ion concentration of 0.5~1.5 mol / L, which is the acetic acid precursor solution of ErBCO.

[0012] Further, in step (3), the proportion of BHO nanocrystals in the ErBCO / BHO composite powder is 1.5~10wt%; preferably 1.5~6wt%.

[0013] Further, in step (3), the frequency of atomization is 1.6~2.4 MHz, the average diameter of the atomized droplets is 1~5 μm; the carrier gas is high-purity argon, and the carrier gas flow rate is 2~15 L / min; the radio frequency plasma region uses a radio frequency plasma generator with a power of 20~80 kW, the working gas is argon, the auxiliary gas is oxygen or hydrogen, the auxiliary gas volume fraction is 2%~10%, and the total flow rate of the working gas is 10~50 L / min; the atomized droplets are instantaneously heated to 3000~5000℃ in the plasma region, and solvent evaporation, precursor thermal decomposition, and melting spheroidization occur simultaneously; the gas quenching rate in the cooling chamber is >10 4 ℃ / s; the sphericity of the obtained ErBCO / BHO composite powder is ≥0.95, and the average particle size D 50 The primary grain size of the ErBCO phase in the ErBCO / BHO composite powder is 20-50 nm, ranging from 50 to 200 nm.

[0014] Further, in step (4), before compression molding, the ErBCO / BHO composite powder is mixed with an organic binder and granulated. The amount of organic binder added is 0.5% to 2% of the mass of the ErBCO / BHO composite powder. The compression molding pressure is 30 to 50 MPa, and the holding time is 1 to 12 min. The relative density of the ErBCO / BHO superconducting target blank is 55% to 65%.

[0015] Further, in step (4), the organic binder is polyethylene glycol.

[0016] Further, in step (5), the flash furnace is a tube furnace equipped with an electrode inlet flange and a programmable DC power supply. The DC power supply has a power of 3~20 kW, an adjustable output voltage of 0~1000 V, a stability of ≤1%, and an output voltage that is not 0. The flash densification process includes: raising the furnace temperature to 750~950℃ at a heating rate of 5~20 ℃ / min, applying a constant electric field of 100~500 V / cm to both ends of the sample during the heating and holding process, and setting the current limit to 1~10 A. When the furnace temperature reaches the flash initiation temperature, the conductivity of the sample increases nonlinearly and rapidly, and the current jumps instantaneously to the current limit setting value, triggering the flash phenomenon. Subsequently, the system automatically switches to constant current mode and holds the sample at the current limit for 30~300 s. After the flash is completed, the power is turned off and the sample cools naturally with the furnace.

[0017] Further, in step (6), during the oxygen permeation treatment, the temperature is increased to 450-550℃ at a rate of 1-5℃ / min, and kept at this temperature for 10-20 h in a pure oxygen flow with an oxygen flow rate of 200 mL / min-1 L / min, and then cooled to room temperature at a rate of 0.5-1℃ / min.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: (1) This invention introduces pre-fabricated BHO nanocrystals into the preparation of ErBCO superconducting targets for the first time. BHO nanocrystals and ErBCO can form efficient flux pinning centers, significantly increasing the critical current density of the superconducting target under an applied magnetic field. The pre-fabricated nanocrystal technology enables pre-control of the size and shape of the heterophase, solving the problems of uncontrollable dopant phase size and uneven distribution in traditional elemental doping. By adjusting the size distribution of the pre-fabricated BHO nanocrystals, this invention can effectively control their growth behavior in the superconducting matrix, reduce the coarsening factor, and increase the critical current density by 23%~50% under a magnetic field of 30 K and 1 T.

[0019] (2) This invention employs an integrated "atomization-plasma jet pyrolysis" technology, atomizing the precursor solution and then jetting it into the radio frequency plasma region, simultaneously completing thermal decomposition and melting spheroidization in one step. Compared to traditional solid-state methods or stepwise jet pyrolysis-spheroidization methods, this invention shortens the process flow and avoids contamination and agglomeration of the powder during the transfer process. The precursor uses a simple metal acetate solution, avoiding the potential impact of organic residues on the purity of the superconducting phase. Plasma has the characteristics of high temperature, high enthalpy, high chemical reactivity, a suitable reaction atmosphere, and controllable reaction temperature, making it very suitable for preparing high-purity, small-particle-size spherical powders. Compared with other methods, this invention has a shorter process flow, higher efficiency, and can produce spherical powders in one step.

[0020] (3) By using radio frequency plasma high-temperature instantaneous spheroidization and gas quenching, a composite powder with high sphericity (≥0.95), a grain size of ErBCO phase of 20~50 nm, and a BHO nanocrystal size of 10~30 nm were obtained, forming a nanoscale composite structure, which significantly improved the flowability and sintering activity of the powder. Radio frequency plasma spheroidization technology utilizes the high-temperature characteristics of plasma to rapidly heat and melt irregular powder particles. The molten particles rapidly solidify under surface tension and extremely high temperature gradient to form spherical powder, which is especially suitable for the spheroidization treatment of ceramic powders such as oxides. The spherical powder is uniformly filled during molding, and the green body has high density, which is beneficial for subsequent flash sintering densification.

[0021] (4) This invention applies flash sintering technology to the preparation of BHO-doped ErBCO superconducting targets. Compared with traditional long-term high-temperature sintering (>900℃, >24 h) or spark plasma sintering (SPS), flash sintering has the following unique advantages: 1) Lower sintering temperature (750~950℃) can reduce the volatilization loss of Ba and Cu in ErBCO; 2) The sintering speed is extremely fast (30~300 s), resulting in extremely high production efficiency; 3) Electric field-assisted ion migration is accelerated, enabling high densification at lower temperatures; 4) The extremely short holding time and rapid cooling effectively suppress grain growth. Combined with the grain boundary pinning effect of BHO nanocrystals, the final target grain size can be controlled within 8 μm (preferably 3.8 μm~7.3 μm). 5) The equipment is relatively simple, requiring no complex high-pressure molds, and its cost is lower than that of SPS; 6) Energy is precisely focused on the billet area, resulting in high thermal efficiency and significantly reduced energy consumption.

[0022] (5) This invention achieves multi-level control of the microstructure of the target material through the synergistic effect of pre-fabricated BHO nanocrystal doping and flash calcination process: 1) Atomic scale: The lattice matching of BHO and ErBCO forms a coherent interface, resulting in lattice distortion pinning; 2) Nanoscale: BHO nanocrystals are dispersed to form nanoparticle pinning centers; 3) Grain size: The rapid densification of flash burning and the grain boundary pinning of BHO work together to suppress grain growth and obtain a fine-grained microstructure.

[0023] (6) In this method, ErBCO is used instead of YBCO as the superconducting matrix. ErBCO has a higher critical temperature and critical current density than YBCO under a magnetic field, and its trapping magnetic flux is 2 to 3 times that of YBCO of the same size. Therefore, the ErBCO / BHO superconducting target prepared in this invention has more significant performance advantages under a magnetic field.

[0024] (7) The method of the present invention does not use toxic and harmful solvents, and the waste gas is discharged after being washed with water and filtered, which meets the requirements of green environmental protection. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The present invention provides a flowchart of the preparation process for preparing BHO-doped ErBCO superconducting targets using plasma jet pyrolysis-gas quenching and flash calcination continuous powdering.

[0026] Figure 2 This is a schematic diagram of the integrated continuous powder production system of plasma jet pyrolysis-gas quenching and rapid cooling.

[0027] Figure 3 This is a cross-sectional view of the ErBCO / BHO target material obtained in Example 1. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0032] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0033] This invention provides a method for preparing BHO-doped ErBCO superconducting targets through plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) Preparation of BHO nanocrystals and their dispersion: BHO nanocrystals were prepared by hydrothermal method and ultrasonically dispersed in dispersion medium to obtain BHO nanocrystal dispersion. (2) Preparation of BHO doped precursor solution: Prepare an acetic acid precursor solution of ErBCO, add the BHO nanocrystal dispersion obtained in step (1) to the acetic acid precursor solution, stir continuously and sonicate to obtain BHO doped precursor solution. (3) Plasma jet pyrolysis-gas quenching integrated continuous powder making: The BHO doped precursor liquid obtained in step (2) is atomized by an atomizer, and the carrier gas carries the atomized droplets into the radio frequency plasma region. The thermal decomposition reaction and melting spheroidization are completed simultaneously in the high temperature region of the plasma. Then, it enters the cooling chamber for gas quenching and cooling, and ErBCO / BHO composite powder is collected. (4) Compression molding: The ErBCO / BHO composite powder obtained in step (3) is compression molded to obtain the target blank; (5) Flash densification: The target blank obtained in step (4) is placed in a flash furnace and an electric field is applied to flash densify it to obtain ErBCO / BHO superconducting target blank. (6) Oxygen permeation treatment: Since the superconductivity of ErBCO is strongly dependent on its oxygen content, the target material after flash burning needs to be subjected to oxygen permeation annealing treatment in an oxygen-rich environment to restore the orthogonal superconducting phase structure. The ErBCO / BHO superconducting target material blank obtained in step (5) is subjected to oxygen permeation treatment to obtain BHO-doped ErBCO superconducting target material, denoted as ErBCO / BHO superconducting target material.

[0034] In a preferred embodiment of the present invention, the steps of preparing BHO nanocrystals by hydrothermal method in step (1) are as follows: barium acetate and hafnium chloride are dissolved in water at a molar ratio of 1:1, the pH is adjusted to alkaline, and a uniform precursor solution is formed by stirring; the precursor solution is subjected to hydrothermal reaction, and after the reaction is completed, it is naturally cooled, centrifuged to separate the precipitate, and after washing and drying, BHO nanocrystals are obtained.

[0035] In a preferred embodiment of the present invention, in the method of preparing BHO nanocrystals by hydrothermal method, the pH is adjusted to alkalinity to 10-12; the hydrothermal reaction temperature is 180℃-240℃, the time is 12-48 hours; and the drying temperature is 60-80℃.

[0036] An exemplary procedure for preparing BHO nanocrystals using a hydrothermal method is as follows: Barium acetate and hafnium chloride are dissolved in deionized water at a molar ratio of 1:1, and sodium hydroxide is added to adjust the pH to 11. The mixture is stirred to form a homogeneous precursor solution. The precursor solution is transferred to a high-pressure reactor and subjected to hydrothermal reaction at 200°C for 24 hours. After the reaction is completed, the mixture is allowed to cool naturally, and the precipitate is separated by centrifugation. The precipitate is washed three times with deionized water and ethanol, and then dried at 70°C to obtain BHO nanocrystals.

[0037] In a preferred embodiment of the present invention, in step (1), the grain size of BHO nanocrystals is 10~30 nm, preferably 10~20 nm; the dispersion medium is anhydrous ethanol; the dispersant is polyvinylpyrrolidone (PVP); the concentration of BHO nanocrystals in the BHO nanocrystal dispersion is 0.5~5 mg / mL, preferably 0.5~2 mg / mL; and the ultrasonic treatment time is 30~120 min.

[0038] In a preferred embodiment of the present invention, in step (2), the method for preparing the acetic acid precursor solution of ErBCO is as follows: Erbium acetate, barium acetate and copper acetate are dissolved in a mixed solvent of water and glacial acetic acid according to the molar ratio of Er:Ba:Cu=1:2:3 to prepare a solution with a total metal ion concentration of 0.5~1.5 mol / L, which is the acetic acid precursor solution of ErBCO.

[0039] For example, in a mixed solvent of water and glacial acetic acid, the volume ratio of water to glacial acetic acid is 4:1.

[0040] In a preferred embodiment of the present invention, in step (3), the proportion of BHO nanocrystals in the ErBCO / BHO composite powder is 1.5~10wt%; preferably 1.5~6wt%.

[0041] In a preferred embodiment of the present invention, in step (3), the frequency of atomization is 1.6~2.4 MHz, the average diameter of the atomized droplets is 1~5 μm; the carrier gas is high-purity argon (purity ≥99.99%), the carrier gas flow rate is 2~15 L / min; the radio frequency plasma zone uses a radio frequency plasma generator with a power of 20~80 kW, the working gas is argon, the auxiliary gas is oxygen or hydrogen, the auxiliary gas volume fraction is 2%~10%, and the total flow rate of the working gas is 10~50 L / min; the atomized droplets are instantaneously heated to 3000~5000℃ in the plasma zone, and in this high-temperature zone, solvent evaporation, precursor thermal decomposition to generate Er-Ba-Cu-O oxide, BHO nanocrystal stability, and spheroidization of molten particles under surface tension occur simultaneously to form a BHO / ErBCO nanocomposite structure; the gas quenching rate in the cooling chamber is >10 4℃ / s; The obtained ErBCO / BHO composite powder is perfectly spherical with a sphericity ≥0.95 and an average particle size D 50 The primary grain size of the ErBCO phase in the ErBCO / BHO composite powder is 20-50 nm, while the BHO nanocrystals (10-30 nm in size) are uniformly distributed inside the ErBCO particles and at the grain boundaries.

[0042] In a preferred embodiment of the present invention, in step (4), before compression molding, the ErBCO / BHO composite powder is mixed evenly with an organic binder and then granulated through an 80-200 mesh sieve. The amount of organic binder added is 0.5%-2% of the mass of the ErBCO / BHO composite powder. The compression molding pressure is 30-50 MPa, and the holding time is 1-12 min. The relative density of the ErBCO / BHO superconducting target blank (target blank) is 55%-65%.

[0043] In a preferred embodiment of the present invention, in step (4), the organic binder is polyethylene glycol.

[0044] In a preferred embodiment of the present invention, in step (5), the flash furnace is a tube furnace with a maximum operating temperature of 1600℃, a rated operating temperature of 800~1600℃, and a temperature control accuracy of ±1℃. It is equipped with an electrode inlet flange and a programmable DC power supply, allowing positive and negative electrode wires to be introduced into the furnace and connected to the sample clamp. The DC power supply has a power of 3~20 kW, an adjustable output voltage of 0~1000V, and a selectable output current of 0~2200 A. The stability of both output voltage and output current is ≤1%, and neither output voltage nor output current is zero. The flash densification process includes: raising the furnace temperature to 750~950℃ at a heating rate of 5~20 ℃ / min; applying a constant electric field of 100~500 V / cm across the sample during the heating and holding process; and setting the current limit to 1~10 A. When the furnace temperature reaches the flash initiation temperature, the sample conductivity increases nonlinearly and sharply, and the current jumps instantaneously to the current limit setting, triggering the flash phenomenon. Subsequently, the system automatically switches to constant current mode and holds the sample at the current limit for 30~300 s. After flash densification is completed, the power is turned off, and the sample cools naturally with the furnace.

[0045] In a preferred embodiment of the present invention, the flash densification process is as follows: the target blank is placed between two electrodes, and conductive silver paste is coated between the electrodes and the sample to ensure good contact. The furnace temperature is raised to the target flash temperature (750~950℃) at a heating rate of 5~20 ℃ / min. During the heating and holding process, a constant electric field is applied to both ends of the sample through a DC power supply, with the electric field strength set to 100~500 V / cm and the current limit set to 1~10 A. The flash burning process consists of three stages: 1) Incubation stage (constant voltage control): When the furnace temperature is lower than the flash ignition temperature, the introduction of BHO nanocrystals reduces the resistivity of ErBCO, but the overall resistivity of the sample is still high, the current in the circuit is extremely small (μA-mA level), and the system is in constant voltage control mode.

[0046] 2) Flash Initiation Stage: When the furnace temperature rises to the flash initiation temperature, the sample conductivity increases nonlinearly and rapidly, and the current jumps instantaneously to the limit current setting value, accompanied by a strong Joule heating effect and luminescence, forming the "flash" process. Due to the introduction of BHO nanocrystals, the resistivity of the ErBCO matrix is ​​reduced, and the flash initiation temperature can be reduced by 50~100℃ compared to pure ErBCO.

[0047] 3) Constant Current Densification Stage: The system automatically switches from constant voltage mode to constant current mode, maintaining a stable current within the set current limit for continuous heating. The constant current holding time is set to 30~300 s (adjusted according to sample size and target density). During this stage, the sample rapidly densifies under strong Joule heating, accompanied by a sharp shrinkage of the sample. After flash firing, the output power is turned off, and the sample cools naturally with the furnace.

[0048] In a preferred embodiment of the present invention, in step (6), the oxygen permeation treatment is carried out in a box furnace, heated to 450-550°C at a rate of 1-5°C / min, kept at a pure oxygen flow for 10-20 h, with an oxygen flow rate of 200 mL / min-1 L / min, and then cooled to room temperature at a rate of 0.5-1°C / min.

[0049] The ErBCO / BHO superconducting target obtained by the method of the present invention has a relative density ≥98%, an average grain size ≤8 μm (preferably 3.8 μm~7.3 μm), and a zero resistance temperature (Tc0) ≥90 K.

[0050] Embodiments of the present invention also provide a plasma jet pyrolysis-gas quenching rapid cooling integrated continuous powder production system for implementing the above method, comprising a precursor liquid supply device, an atomizer, a carrier gas system, a radio frequency plasma generator (including a reaction chamber), a rapid cooling chamber, a cyclone classifier collector, and an exhaust gas treatment unit connected in sequence. Figure 2 As shown; the atomizer frequency is 1.6~2.4 MHz; the power of the radio frequency plasma generator is 20~80 kW; the gas quenching rate of the rapid cooling chamber is >10. 4 ℃ / s.

[0051] In a preferred embodiment of the present invention, the atomizer is a piezoelectric atomizer, which converts the BHO-doped precursor liquid into submicron-sized aerosol droplets with an average droplet diameter of 1~5 μm.

[0052] In a preferred embodiment of the present invention, the carrier gas system provides high-purity oxygen, high-purity argon, or an oxygen-argon mixture as the carrier gas, which carries atomized droplets and injects them into the radio frequency plasma generator.

[0053] In a preferred embodiment of the present invention, the rapid cooling chamber is located downstream of the plasma zone, and the cooling gas is high-purity argon or high-purity nitrogen (purity ≥ 99.99%), with a gas quenching rate > 10. 4 ℃ / s. The molten spheroidized particles are rapidly cooled by gas quenching in a rapid cooling chamber to lock in the high-temperature phase structure and prevent excessive grain growth.

[0054] In a preferred embodiment of the present invention, a cyclone classifier is disposed after the rapid cooling chamber for collecting the gas-quenched powder and classifying it according to particle size, and a tail gas treatment device is used to treat the discharged waste gas.

[0055] This invention first prepares BaHfO3 (BHO) nanocrystals with a grain size of 10-30 nm using a hydrothermal method. These nanocrystals are then ultrasonically dispersed and added to an acetic acid precursor solution. The doped precursor solution is atomized and injected into the radio frequency plasma region, simultaneously completing thermal decomposition and melt spheroidization in one step. Subsequent gas quenching and rapid cooling yield ErBCO / BHO composite powder with a sphericity ≥0.95 and an average particle size of 50-200 nm. The composite powder is then molded and densified using flash sintering at 750-950℃ and an electric field strength of 100-500 V / cm. Finally, oxygen permeation treatment yields the ErBCO / BHO superconducting target. This invention achieves a fully integrated process from BHO nanocrystal prefabrication to powder spheroidization and target densification. The prepared target has a relative density ≥98%, a grain size ≤8 μm, and exhibits excellent superconducting properties.

[0056] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0057] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0058] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0059] The technical solution of the present invention will be further illustrated by the following embodiments.

[0060] Example 1 A method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) Preparation of BaHfO3 (BHO) nanocrystals: Barium acetate (Ba(CH3COO)2) and hafnium chloride (HfCl4) were weighed at a molar ratio of 1:1 and dissolved in 60 mL of deionized water. Sodium hydroxide was added to adjust the pH to 11, and the mixture was stirred to form a uniform precursor solution. The precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200 °C for 24 hours. After the reaction was completed, the mixture was naturally cooled, and the precipitate was separated by centrifugation. The precipitate was washed three times with deionized water and ethanol, and dried at 70 °C to obtain BHO nanocrystals with a crystal size of approximately 15-25 nm. The BHO nanocrystals were ultrasonically dispersed in anhydrous ethanol, and PVP (polyvinylpyrrolidone) was added as a dispersant (the amount of PVP added was 1 wt% of the mass of BHO). The mixture was ultrasonically treated for 60 min to obtain a BHO dispersion of 1 mg / mL. In this embodiment, the feed amounts of barium acetate and hafnium chloride are both 0.01 mol (approximately 2.55 g of barium acetate and approximately 3.21 g of hafnium chloride), dissolved in 60 mL of deionized water. Therefore, the Ba in the precursor solution... 2+ and Hf 4+ The concentrations were all approximately 0.167 mol / L.

[0061] (2) Preparation of ErBCO acetic acid precursor solution: Weigh erbium acetate (Er(CH3COO)3·4H2O), barium acetate (Ba(CH3COO)2) and copper acetate (Cu(CH3COO)2·H2O) in a molar ratio of Er:Ba:Cu=1:2:3, dissolve them in a mixed solvent of deionized water and glacial acetic acid (volume ratio of 4:1), stir until completely dissolved, and prepare an ErBCO acetic acid precursor solution with a total metal ion concentration of 0.6 mol / L.

[0062] (3) Preparation of BHO doping precursor solution: Based on the calculation that the mass fraction of BHO nanocrystals in the final composite powder is 3%, the BHO dispersion obtained in step (1) is added dropwise to the ErBCO acetic acid precursor solution, and the mixture is continuously stirred and ultrasonically treated for 60 min to obtain the BHO doping precursor solution.

[0063] (4) Integrated Continuous Powdering: The integrated continuous powdering system was turned on, and the piezoelectric atomizer frequency was set to 2.0MHz, the carrier gas (oxygen) flow rate to 8 L / min, the RF plasma generator power to 50 kW, and the working gas to be Ar+5%H2 (i.e., H2 accounts for 5% of the volume of Ar) with a flow rate of 40 L / min. The BHO-doped precursor solution was fed into the atomizer at a rate of 15 mL / min, and the average diameter of the atomized droplets was 2~3 μm. The gas-quenched powder was collected and separated by cyclone separation to obtain ErBCO / 3wt%BHO composite powder. The composite powder was perfectly spherical with a sphericity of 0.96 and a D0. 50=110 nm, BHO nanocrystals are uniformly distributed inside the ErBCO particles and at the grain boundaries. In this embodiment, the temperature of the radio frequency plasma region is calibrated by an infrared thermometer to be approximately 3500~4500℃, which is sufficient to instantly and completely pyrolyze and spheroidize the atomized droplets; high-purity argon gas quenching is used in the rapid cooling chamber, and the gas quenching rate is estimated to be >10. 4 ℃ / s. The ErBCO grain size is approximately 25~40 nm, and BHO nanocrystals (approximately 15~25 nm in size) are uniformly distributed within the ErBCO grains and at the grain boundaries.

[0064] (5) Compression molding: Take the above composite powder, add 1 wt% PVA binder, mix evenly and pass through an 80-mesh sieve. Under a pressure of 40 MPa, perform bidirectional compression molding and hold the pressure for 5 min to obtain a circular blank with a diameter of 50 mm and a thickness of 8 mm. The relative density of the blank is about 63%.

[0065] (6) Flash calcination densification: A tube flash furnace (maximum temperature 1600℃, temperature control accuracy ±1℃) was used. The target blank was placed between two graphite electrodes, and conductive silver paste was coated between the electrodes and the sample to ensure good contact. An electric field was applied to both ends of the sample using a programmable DC power supply (power 5 kW, output voltage adjustable from 50 to 300 V, stability ≤1%). The tube furnace was heated to 850℃ at a heating rate of 10℃ / min. During the heating process, a constant electric field of 250 V / cm was applied to both ends of the sample using the DC power supply, and the initial current limit was set to 6 A. When the furnace temperature reached approximately 850℃, the sample resistivity dropped sharply, and the current jumped instantaneously to the 6 A limit current, triggering the flash calcination phenomenon, accompanied by a strong luminescence. The flash calcination was carried out in constant current mode for 90 s, during which the sample rapidly shrank. After the flash calcination was completed, the power was turned off, and the sample cooled naturally with the furnace.

[0066] (7) Oxygen permeation treatment: The flash-fired target material was heated to 500℃ at 2℃ / min and held in a pure oxygen flow (1 L / min) for 15 h, then cooled to room temperature at 0.5℃ / min to obtain a BHO-doped ErBCO superconducting target material, denoted as ErBCO / BHO target material. The cross-sectional view of the ErBCO / BHO target material obtained in this embodiment is shown below. Figure 3 As shown, the grains inside the target material are elongated and tightly packed with few pores, indicating that the flash firing process can effectively achieve rapid densification of the target material.

[0067] The ErBCO / BHO target material obtained in this embodiment has a relative density of approximately 98.9% and an average grain size of approximately 7.3 μm, as measured by Archimedes' displacement method. The resistance change with temperature was measured using a Power Proportional Measurement System (PPMS), and the zero resistance temperature (Tc0) was approximately 91.5 K.

[0068] Example 2 A method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) Preparation of BHO nanocrystals: Same as in Example 1, but the hydrothermal temperature was changed to 220℃, the hydrothermal reaction time was 24 hours, and the BHO crystal size was about 20~30 nm. The concentration of BHO dispersion was changed to 2 mg / mL.

[0069] (2) Preparation of ErBCO acetic acid precursor solution: Same as in Example 1.

[0070] (3) Preparation of BHO doping precursor solution: Based on the calculation that the mass fraction of BHO nanocrystals in the final composite powder is 6%, the BHO dispersion obtained in step (1) is added dropwise to the ErBCO acetic acid precursor solution, and the mixture is continuously stirred and ultrasonically treated for 60 min to obtain the BHO doping precursor solution.

[0071] (4) Integrated continuous powder production: The plasma power was changed to 60 kW, and other parameters remained the same as in Example 1. The resulting powder had a sphericity of 0.97 and a D0.05. 50 =95 nm, grain size is 20~35 nm, BHO is uniformly distributed; (5) Compression molding: pressure 50 MPa, holding pressure for 12 min, other conditions are the same as in Example 1, the relative density of the blank is about 56%.

[0072] (6) Flash calcination densification: The target furnace temperature for flash calcination is 900℃, the applied electric field strength is 300 V / cm, the current is limited to 7 A, the constant current holding time is 120 s, and other flash calcination parameters are the same as in Example 1.

[0073] (7) Oxygen permeation treatment: Same as in Example 1.

[0074] The target material obtained in this embodiment has a relative density of approximately 99.3%, an average grain size of approximately 4.6 μm, and a Tc0 of approximately 91.2 K.

[0075] Example 3 A method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) Preparation of BHO nanocrystals: Same as in Example 1, but the hydrothermal temperature was changed to 180℃, the hydrothermal time was 48 hours, and the BHO crystal size was about 10~15 nm. The concentration of BHO dispersion was changed to 0.5 mg / mL.

[0076] (2) Preparation of ErBCO acetic acid precursor solution: The total metal ion concentration was changed to 1.0 mol / L, and the rest was the same as in Example 1.

[0077] (3) Preparation of BHO doped precursor solution: Based on the calculation that the mass fraction of BHO nanocrystals in the final composite powder is 1.5%, the BHO dispersion obtained in step (1) is added dropwise to the ErBCO acetic acid precursor solution, and the mixture is continuously stirred and ultrasonically treated for 60 min to obtain the BHO doped precursor solution.

[0078] (4) Integrated continuous powder production: The carrier gas flow rate was changed to 6 L / min, the plasma power was 40 kW, and other parameters were the same as in Example 1. The resulting powder D 50 =150 nm, sphericity is 0.95, and grain size is 30~50 nm.

[0079] (5) Compression molding: bidirectional compression molding is adopted, with a pressure of 40 MPa and a holding pressure of 10 min. Other conditions are the same as in Example 1. The relative density of the blank is about 58%.

[0080] (6) Flash calcination densification: The target furnace temperature for flash calcination is 800℃, the applied electric field strength is 400 V / cm, the limiting current is 5A, the constant current holding time is 60 s, and other flash calcination parameters are the same as in Example 1.

[0081] (7) Oxygen permeation treatment: 450℃, 20 h, other conditions are the same as in Example 1.

[0082] The target material obtained in this embodiment has a relative density of approximately 98.2%, an average grain size of approximately 4.9 μm, a Tc0 of approximately 90.8 K, and a Jc (77 K, 1 T) of approximately 1.5 × 10⁻⁶. 5 A / cm 2 .

[0083] Example 4 A method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering, comprising the following steps: (1) Preparation of BHO nanocrystals: Same as in Example 1, but the concentration of BHO dispersion was changed to 5 mg / mL.

[0084] (2) Preparation of ErBCO acetic acid precursor solution: Same as in Example 1.

[0085] (3) Preparation of BHO doped precursor solution: Same as in Example 1.

[0086] (4) Integrated continuous powder making: The carrier gas is changed to Ar+O2 mixed gas (O2 volume fraction is 20%), and the rest is the same as in Example 1.

[0087] (5) Compression molding: Same as in Example 1.

[0088] (6) Flash densification: Same as in Example 1.

[0089] (7) Oxygen permeation treatment: Same as in Example 1.

[0090] The target material obtained in this embodiment has a relative density of approximately 98.7%, an average grain size of approximately 3.8 μm, a Tc0 of approximately 91.3 K, and a Jc (77 K, 1 T) of approximately 1.9 × 10⁻⁶. 5 A / cm 2 .

[0091] Comparative Example 1 (Traditional solid-state method + atmospheric pressure sintering) Weigh Er₂O₃, BaCO₃, and CuO in a molar ratio of Er:Ba:Cu = 1:2:3, ball mill the mixture for 24 h, calcine it in air at 920℃ for 24 h, and ball mill it again to obtain ErBCO powder (D). 50 Approximately 2.8 μm in size and exhibiting an irregular morphology. BHO nanocrystals were mechanically mixed at a ratio of 3 wt% (same as in Example 1), molded at 40 MPa, sintered at 950°C for 24 h in a box furnace under normal pressure and oxygen atmosphere, and then subjected to oxygen permeation treatment (the specific process is the same as in Example 1).

[0092] The target material obtained in this comparative example has a relative density of approximately 91.5%, a grain size of 12~18 μm, and a Tc0 of approximately 89.5 K.

[0093] Comparative Example 2 (No BHO doping + flash burning) ErBCO powder (without BHO added) was prepared according to the method of Example 1, and then densified by flash sintering after molding (the specific process is the same as in Example 1), followed by oxygen infiltration treatment (the specific process is the same as in Example 1).

[0094] The target material obtained in this comparative example has a relative density of approximately 98.2%, an average grain size of approximately 2.5 μm, and a Tc0 of approximately 91.0 K.

[0095] Comparative Example 3 (Conventional jet pyrolysis of ErBCO powder + conventional sintering) ErBCO powder was prepared using a conventional jet pyrolysis method (without plasma spheroidization). An ErBCO acetic acid precursor solution was prepared at a molar ratio of Er:Ba:Cu = 1:2:3 (same as in Example 1). The precursor solution was atomized and fed into a tubular pyrolysis furnace at 600°C using oxygen as the carrier gas. The atomized droplets underwent solvent evaporation and precursor thermal decomposition within the furnace. The collected powder was heat-treated at 550°C and then ground to obtain ErBCO powder. 1 wt% PVA binder was added to the ErBCO powder, and after thorough mixing, it was sieved through an 80-mesh sieve. The mixture was then bidirectionally molded under 40 MPa pressure for 5 min to obtain a circular green body with a diameter of 50 mm and a thickness of 8 mm. The green body had a relative density of approximately 63%. It was sintered in a box furnace at 950°C for 24 h, followed by oxygen infiltration treatment (the specific process was the same as in Example 1).

[0096] The target material obtained in this comparative example has a relative density of approximately 93% and an average grain size of approximately 8~12 μm.

[0097] Comparing Example 1 and Comparative Example 3, it can be seen that the plasma spheroidization + flash calcination process of the present invention significantly improves density and superconducting properties.

[0098] As can be seen from the above embodiments and comparative examples, the ErBCO / BHO composite powder prepared by the plasma jet pyrolysis-gas quenching integrated continuous powder preparation system of the present invention has the characteristics of high sphericity, uniform dispersion of nanocrystals and BHO. Combined with the flash sintering process, densification can be completed in a very short time (60~120 s), significantly improving the target material density (≥98%), reducing the average grain size from 12~18 μm in traditional methods to 3.8~7.3 μm, and improving superconducting performance. Compared with traditional solid-state methods and atmospheric pressure sintering, the method of the present invention has outstanding advantages such as continuous process, low sintering temperature, high speed, low energy consumption, grain refinement, and significant pinning effect, and has significant practical value.

[0099] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering, characterized in that, Includes the following steps: (1) BHO nanocrystals were prepared by hydrothermal method, and the BHO nanocrystals were ultrasonically dispersed in a dispersion medium containing a dispersant to obtain a BHO nanocrystal dispersion. (2) Prepare an acetic acid precursor solution of ErBCO, add the BHO nanocrystal dispersion obtained in step (1) to the acetic acid precursor solution, stir continuously and sonicate to obtain BHO doped precursor solution. (3) The BHO doped precursor liquid obtained in step (2) is atomized and the carrier gas carries the atomized droplets into the radio frequency plasma region. The thermal decomposition reaction and melting spheroidization are completed simultaneously in the high temperature region of the plasma. Then, it is quenched in the cooling chamber and collected to obtain ErBCO / BHO composite powder. (4) The ErBCO / BHO composite powder obtained in step (3) is molded to obtain a target blank; (5) Place the target blank obtained in step (4) in a flash furnace and apply an electric field to flash densify it to obtain ErBCO / BHO superconducting target blank; (6) The ErBCO / BHO superconducting target blank obtained in step (5) is subjected to oxygen permeation treatment to obtain the BHO-doped ErBCO superconducting target.

2. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (1), the steps for preparing BHO nanocrystals by hydrothermal method are as follows: barium acetate and hafnium chloride are dissolved in water at a molar ratio of 1:1, the pH is adjusted to alkaline, and the mixture is stirred to form a uniform precursor solution; the precursor solution is subjected to a hydrothermal reaction, and after the reaction is completed, it is naturally cooled, centrifuged to separate the precipitate, and after washing and drying, BHO nanocrystals are obtained.

3. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (1), the grain size of the BHO nanocrystals is 10~30 nm; the dispersion medium is anhydrous ethanol; the dispersant is polyvinylpyrrolidone; and the concentration of BHO nanocrystals in the BHO nanocrystal dispersion is 0.5~5 mg / mL.

4. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (2), the method for preparing the acetic acid precursor solution of ErBCO is as follows: Erbium acetate, barium acetate and copper acetate are dissolved in a mixed solvent of water and glacial acetic acid according to the molar ratio of Er:Ba:Cu=1:2:3 to prepare a solution with a total metal ion concentration of 0.5~1.5 mol / L, which is the acetic acid precursor solution of ErBCO.

5. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (3), the proportion of BHO nanocrystals in the ErBCO / BHO composite powder is 1.5~10wt%.

6. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (3), the atomization frequency is 1.6~2.4 MHz, and the average diameter of the atomized droplets is 1~5 μm; the carrier gas is selected from argon, oxygen, or a mixture of argon and oxygen, and the carrier gas flow rate is 2~15 L / min; the radio frequency plasma region uses a radio frequency plasma generator with a power of 20~80 kW, the working gas is argon, and the auxiliary gas is selected from oxygen or hydrogen with a volume fraction of 2%~10% and a total working gas flow rate of 10~50 L / min; the atomized droplets are instantaneously heated to 3000~5000℃ in the plasma region, and solvent evaporation, precursor thermal decomposition, and melting spheroidization occur simultaneously; the gas quenching rate in the cooling chamber is >10 4 ℃ / s; the sphericity of the obtained ErBCO / BHO composite powder is ≥0.95, and the average particle size D 50 The primary grain size of the ErBCO phase in the ErBCO / BHO composite powder is 20-50 nm, ranging from 50 to 200 nm.

7. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (4), before compression molding, the ErBCO / BHO composite powder is mixed with an organic binder and granulated. The amount of organic binder added is 0.5% to 2% of the mass of the ErBCO / BHO composite powder. The compression molding pressure is 30 to 50 MPa, and the holding time is 1 to 12 min. The relative density of the ErBCO / BHO superconducting target blank is 55% to 65%.

8. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 7, characterized in that, In step (4), the organic binder is polyethylene glycol.

9. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (5), the flash furnace is a tube furnace equipped with an electrode inlet flange and a programmable DC power supply. The DC power supply has a power of 3~20 kW, an adjustable output voltage of 0~1000 V, a stability of ≤1%, and an output voltage that is not 0. The flash densification process includes: raising the furnace temperature to 750~950℃ at a heating rate of 5~20 ℃ / min; applying a constant electric field of 100~500 V / cm to both ends of the sample during the heating and holding process; and setting the current limit to 1~10 A. When the furnace temperature reaches the flash initiation temperature, the conductivity of the sample increases nonlinearly and rapidly, and the current jumps instantaneously to the current limit setting value, triggering the flash phenomenon. Subsequently, the system automatically switches to constant current mode and holds the sample at the current limit for 30~300 s. After the flash is completed, the power is turned off and the sample is allowed to cool naturally.

10. The method for preparing BHO-doped ErBCO superconducting targets by plasma jet pyrolysis-gas quenching and flash sintering according to claim 1, characterized in that, In step (6), during the oxygen permeation treatment, the temperature is increased to 450-550℃ at a rate of 1-5℃ / min, and kept at this temperature for 10-20 h in a pure oxygen flow at a flow rate of 200 mL / min-1 L / min. Then, the temperature is cooled to room temperature at a rate of 0.5-1℃ / min.

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