Preparation method of high-temperature superconducting REBCO block with artificial groove

Abstract

The invention provides a preparation method of a high-temperature superconducting REBCO block with an artificial groove, and belongs to the technical field of REBCO high-temperature superconducting material preparation, and the preparation method comprises the following steps: manufacturing an auxiliary preparation structure; preparing REBCO raw material powder by adopting a solid-phase sintering method, and uniformly mixing the REBCO raw material powder to obtain a precursor powder combination; based on the manufactured auxiliary preparation structure, precursor powder is combined and pressed to obtain an REBCO buffer layer blank block and an REBCO precursor blank block with a multi-groove structure; selecting a block seed crystal meeting a preset condition, and treating the block seed crystal meeting the preset condition, the REBCO buffer layer and the REBCO precursor blank based on a top seed crystal melt texture method to obtain an REBCO initial block; grinding and polishing the REBCO initial block with the multi-groove structure on the surface, and then performing heat treatment in a flowing oxygen atmosphere to obtain the annealed REBCO high-temperature superconducting block with the artificial grooves. According to the REBCO high-temperature superconducting block with the artificial groove, under the condition of the same size, the surface area of a block sample is increased, and the performance of the block can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of REBCO high-temperature superconducting material preparation technology, and more specifically, to a method for preparing high-temperature superconducting REBCO bulk material with an artificial groove structure. Background Technology

[0002] REBCO high-temperature superconducting bulk materials, due to their high critical temperature, unique self-stabilizing magnetic levitation properties, and stronger magnetic flux trapping ability than ferromagnetic permanent magnets, have shown great application potential in fields such as superconducting flywheel energy storage, magnetic levitation transportation, superconducting bearings, medical imaging, and controlled nuclear fusion. In the REBCO superconducting bulk material preparation process, represented by the top-seed melt texture growth method, the top seed crystal provides a heterogeneous nucleation point to induce crystal epitaxial growth. However, due to the slow cooling growth characteristics of the peritectic reaction process of REBCO superconducting materials, the size of the grown single domains is relatively small.

[0003] Current development and fabrication of high-temperature superconducting bulk materials are limited by the finite area of ​​the textured material guided by seed crystals, hindering the effective increase of surface area. Superconducting bulk materials with larger surface areas exhibit stronger electromagnetic interactions between surface currents and external magnetic fields, possessing greater practical value. To meet the diverse application needs of high-temperature superconductivity, there is an urgent need to develop a method for fabricating high-temperature superconducting REBCO bulk materials with artificial grooves. This would increase the interaction area between the superconducting bulk material and the magnetic field, thereby improving the material's performance under the same bulk material size conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-temperature superconducting REBCO bulk material with artificial grooves, so as to improve the above-mentioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0005] This application provides a method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves, including:

[0006] Auxiliary preparation structures are fabricated based on a pre-defined auxiliary preparation structure fabrication method;

[0007] REBCO raw material powder was prepared by solid-state sintering and homogenized to obtain a precursor powder composition.

[0008] Based on the completed auxiliary preparation structure and the preset REBCO preform preparation method, the precursor powder combination is pressed to obtain REBCO buffer layer preform and artificial multi-groove REBCO precursor preform.

[0009] Select a block seed crystal that meets the preset conditions, and assemble and heat treat the block seed crystal, REBCO buffer layer preform and artificial multi-groove REBCO precursor preform that meet the preset conditions based on the top seed crystal melting texture method to obtain REBCO initial block material with multi-groove structure on the surface.

[0010] The initial REBCO block with a multi-groove structure on the surface was ground and polished, and then sent into a high-temperature tube furnace with a flowing oxygen atmosphere for oxygen infiltration annealing at 450°C for 200 hours, finally obtaining a REBCO high-temperature superconducting block with an artificial multi-groove structure on the surface.

[0011] Preferably, the auxiliary preparation structure is prepared based on a pre-defined auxiliary preparation structure preparation method, including:

[0012] Select a square mold pad with a preset side length, and divide it into four sector areas based on the diagonal of the upper surface of the square mold pad;

[0013] Multiple hemispherical protrusions are evenly arranged in the four sector areas. The radius of each hemispherical protrusion is set to be the same, and the ratio of the radius of each hemispherical protrusion to the length of the preset side is set to 3:80. The ratio of the distance between the centers of two adjacent hemispherical protrusions in each sector area to the length of the preset side is set to 1:8. The square mold pad with multiple hemispherical protrusions is chamfered to obtain the auxiliary preparation structure.

[0014] Preferably, the precursor powder assembly is pressed based on the completed auxiliary preparation structure and the preset REBCO preform preparation method:

[0015] According to the molar ratios RE:Ba:Cu = 1:2:3 and 2:1:1, the original drug powders of RE2O3, BaCO3, and CuO were weighed and mixed separately to prepare the original powders of RE123 and RE211.

[0016] The original RE123 powder and the original RE211 powder were purified by solid-phase reaction method to obtain purified original RE123 powder and original RE211 powder.

[0017] The purified RE123 raw powder and RE211 raw powder were weighed and mixed at a molar ratio of 1:0.35 to prepare a precursor powder. 1 wt% CeO2 powder was added to the precursor powder for mixing to obtain a REBCO precursor powder composition.

[0018] Preferably, the original RE123 powder and the original RE211 powder are purified by a solid-phase reaction method, including:

[0019] The original RE123 powder was sintered in air at 920°C for 54 hours to obtain a sintered RE123 crystal block, and the original RE211 powder was sintered in air at 930°C for 54 hours to obtain a sintered RE211 crystal block.

[0020] The sintered RE123 and RE211 crystal blocks were ground and sintered three times to obtain purified RE123 and RE211 powders.

[0021] Preferably, the precursor powder assembly is pressed based on the completed auxiliary preparation structure and a pre-defined REBCO preform preparation method, comprising:

[0022] Weigh a preset mass of REBCO precursor powder and place it into a mold. Then, apply uniaxial pressure based on the preset auxiliary preparation structure to obtain a square REBCO precursor preform with a multi-groove structure on the upper surface.

[0023] The purified RE123 raw powder and RE211 raw powder were mixed in a molar ratio of RE123:RE211 = 1:0.40, and the mixed RE123 raw powder was mixed again with RE211 raw powder and 1 wt% CeO2 powder to obtain a mixed powder.

[0024] Weigh a predetermined amount of mixed powder and place it into a cylindrical mold with a diameter of 6 mm for pressing to obtain a circular REBCO buffer layer preform.

[0025] Preferably, a bulk seed crystal meeting preset conditions is selected, and the bulk seed crystal meeting the preset conditions, the REBCO buffer layer preform, and the artificially multi-groove REBCO precursor preform are assembled and heat-treated based on the top seed crystal melting texture method, including:

[0026] One pre-selected bulk seed crystal with a grain orientation texture greater than a preset threshold and smooth and flat ab crystal plane is selected by microscopy. The bulk seed crystal is a cube with a side length of 2mm.

[0027] The selected bulk seed crystal, REBCO buffer layer preform, and artificial multi-groove REBCO precursor preform are assembled in a top-to-bottom order to form a coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure, wherein the surface of the REBCO precursor preform with the multi-groove structure faces upward, and the bulk seed crystal is centrally located on top of the REBCO buffer layer preform.

[0028] The coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure is placed on an alumina ceramic plate and placed in a high-temperature furnace for textural growth in an air atmosphere under preset conditions to obtain REBCO initial bulk material induced by REBCO seed crystal growth.

[0029] Preferably, the textural growth is carried out in a high-temperature furnace under preset conditions in an air atmosphere, including:

[0030] The temperature in the high-temperature furnace is controlled from room temperature, then increased to 900℃ after 1 hour and held for 3 hours. Then, heating continues for 1 hour, and the temperature in the high-temperature furnace is increased to 1055℃ and held for 1 hour.

[0031] The furnace temperature was reduced to 1005℃ within 30 minutes, and then the furnace temperature was reduced at a rate of 0.2K / h to 0.6K / h, so that the bulk seed crystals selected in the furnace induced the growth of REBCO precursor embryos for 100h.

[0032] After the sample growth was completed, the temperature of the high-temperature furnace was reduced to room temperature within 3 hours to obtain the initial REBCO block material.

[0033] Preferably, the RE in the REBCO is selected from rare earth elements Y, Gd, Sm and Nd.

[0034] The beneficial effects of this invention are as follows:

[0035] This invention utilizes a specially designed multi-protrusion, open-lobed auxiliary fabrication structure to press multiple hemispherical grooves onto the surface of the REBCO precursor preform, ultimately producing a REBCO high-temperature superconducting bulk sample with an artificial groove structure. Compared to existing technologies, this invention employs this ingenious fabrication process, altering the surface microstructure of the bulk material to increase the surface area of ​​the REBCO superconducting bulk material under the same size conditions. This invention effectively increases the surface current and electromagnetic interaction with the external magnetic field of the superconducting bulk material, thereby improving its performance and enhancing the practicality of RE-based copper oxide superconducting materials in engineering applications, while also significantly reducing bulk material production costs.

[0036] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the process for preparing a high-temperature superconducting REBCO bulk material with artificial grooves as described in an embodiment of the present invention;

[0039] Figure 2 This is a top view schematic diagram of the auxiliary preparation structure in the preparation method of the high-temperature superconducting REBCO bulk material with artificial grooves described in the embodiments of the present invention;

[0040] Figure 3 This is a three-dimensional schematic diagram of the auxiliary fabrication structure in the method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves as described in this embodiment of the invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] Example 1:

[0044] This embodiment provides a method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves.

[0045] See Figure 1 , Figure 2 and Figure 3 , Figure 1The diagram shows that the method includes steps S1, S2, S3, S4, and S5.

[0046] Step S1: Fabricate the auxiliary fabrication structure based on the preset auxiliary fabrication structure fabrication method;

[0047] It is understandable that the design of the auxiliary fabrication structure in this step is not arbitrary, but rather a mold spacer precisely calculated and proportionally configured. These spacers are arranged with regularly spaced hemispherical protrusions and divided into four quadrants according to the rapid growth orientation of REBCO single crystals—that is, the diagonal of the square mold. Within each quadrant, the protrusions are evenly distributed and of consistent size. This design not only ensures the formation of artificial grooves on the surface of the precursor preform during pressing, but also solves the demolding problem caused by the increase in microstructure through chamfering and the design of the lobed mold. This structural optimization significantly improves the accuracy and repeatability of pressing, giving the resulting precursor preform ideal template conditions in terms of structure, thus having a profound impact on superconducting performance.

[0048] Meanwhile, the preparation of REBCO precursor powder employs a two-component (e.g., RE123 and RE211) mixture system based on solid-phase reaction, with CeO2 introduced as an additive to refine particle size and suppress coarsening. This is a commonly used but highly sensitive technique in the field of superconducting material preparation. In particular, the three repeated sintering-grinding cycles not only significantly improve the phase purity of RE123 and RE211 but also effectively enhance the nucleation uniformity and texture consistency during subsequent melt texture growth. In this step, step S1 includes steps S11 and S12.

[0049] Step S11: Select a square mold pad with a preset side length, and divide it into four sector areas based on the diagonal of the upper surface of the square mold pad;

[0050] Understandably, in Top Seed Melt Texture Method (TSMG), the growth of REBCO single crystals exhibits strong directional characteristics, particularly with a clear distribution trend of "rapid growth lines" on the top bulk seed crystal guiding surface. These rapid growth lines in REBCO typically unfold along the diagonal direction of the crystal. Therefore, dividing the mold spacer into four sector regions along the diagonal is precisely to align with this natural growth orientation, allowing the artificial structure to work synergistically with the intrinsic texture of the crystal. This partitioning provides "preferred growth paths" or "perturbation-induced centers" for the subsequent uniformly arranged artificial microstructures (such as hemispherical bosses) in each sector region during crystal growth, enhancing the consistency and integrity of the seed-induced domain regions.

[0051] Step S12: A plurality of hemispherical protrusions are evenly arranged in the four sector areas. The radius of each hemispherical protrusion is set to be the same, and the ratio of the radius of each hemispherical protrusion to the length of the preset side is set to 3:80. The ratio of the distance between the centers of two adjacent hemispherical protrusions in each sector area to the length of the preset side is set to 1:8. The square mold pad with the plurality of hemispherical protrusions is chamfered to obtain the auxiliary preparation structure.

[0052] It is understandable that this step involves constructing an auxiliary fabrication structure with a "multi-groove pre-forming function" using multiple hemispherical protrusions. These generated grooves can guide the micro-differences in local melt cooling rates during the texture growth stage, thereby promoting preferred grain orientation growth and playing an auxiliary role in lattice orientation induction. Especially when the seed crystal guidance range is limited, the artificial grooves can further promote ordered growth in areas beyond the seed crystal induction boundary, increasing the effective texture area. The formed groove structure significantly increases the specific surface area of ​​the bulk material, making the surface current path more complex and enhancing the magnetic flux pinning effect. In the actual operation of superconducting bulk materials, this will improve their response to external magnetic fields and magnetic flux trapping performance, which is beneficial to improving magnetic levitation force and current carrying capacity. In addition, by setting the size ratio of the protrusions to 3:80 for the side length and 1:8 for the spacing, not only is the microscopic uniformity of the groove size guaranteed, but the structural density and the feasibility of compression molding are also maximized. This proportional design comes from a large number of previous experimental optimizations, avoiding the problem of powder compression failure or structural collapse due to excessively dense grooves, and also preventing the problem of reduced surface modification efficiency due to excessively sparse grooves.

[0053] Step S2: REBCO raw material powder is prepared by solid-state sintering and homogenized to obtain a precursor powder combination.

[0054] It is understood that in this process, step S2 includes steps S21, S22 and S23.

[0055] Step S21: Weigh RE2O3, BaCO3, and CuO original drug powders according to the molar ratios RE:Ba:Cu = 1:2:3 and 2:1:1, and mix them separately to prepare RE123 original powder and RE211 original powder;

[0056] It is understandable that this step, by mixing RE2O3, BaCO3, and CuO in a molar ratio of 1:2:3, can synthesize a superconducting main phase powder with the target RE123, which is the core component possessing high-temperature superconducting properties. The use of a 2:1:1 ratio to prepare RE211 powder is to introduce non-superconducting particles that can be controllably distributed during the melt texturing process. These RE211 particles act as flux pinning centers in the superconducting bulk material. Through mismatch with the main phase lattice, they create localized stress fields or grain boundary defects, effectively inhibiting magnetic flux movement and increasing the critical current density of the superconductor.

[0057] Step S22: The original RE123 powder and the original RE211 powder are purified by solid-phase reaction method to obtain purified original RE123 powder and original RE211 powder.

[0058] It is understandable that the multiple sintering processes and three repetitions of the solid-state reaction method in this step not only make the transformation reaction of the original powder more thorough, but also reconstruct the particle structure, making it more reactive and sinterable. This cycle of multiple heat treatments and mechanical crushing promotes the rearrangement and crystal plane pairing between grains at the crystal level, thereby improving the consistency and controllability of powder growth during subsequent melting and texturing processes. In this step, step S22 includes steps S221 and S222.

[0059] Step S221: Sinter the original RE123 powder in air at 920°C for 54 hours, and sinter the original RE211 powder in air at 930°C for 54 hours to obtain sintered RE123 and RE211 crystal blocks.

[0060] It is understood that this step, through long-term sintering in a high-temperature air atmosphere (920℃ and 930℃, respectively, for 54 hours), promotes a complete phase transformation reaction of the mixed oxide precursors, thereby generating polycrystalline bulks with the target crystal structure—namely, RE123 and RE211 bulks.

[0061] Step S222: Grind and sinter the sintered RE123 and RE211 crystal blocks, repeating the process three times to obtain purified RE123 and RE211 powders.

[0062] It is understandable that this step, through repeated grinding and sintering, significantly improves the phase purity of RE123 and RE211 powders, essentially eliminating impurities or residual unreacted phases, thus ensuring the subsequent synthesis of a pure REBCO system.

[0063] Step S23: The purified RE123 raw powder and RE211 raw powder are weighed and mixed at a molar ratio of 1:0.35 to prepare a precursor powder. 1 wt% CeO2 powder is added to the precursor powder for mixing to obtain a REBCO precursor powder composition.

[0064] Understandably, after purifying the high-purity RE123 and RE211 raw powders, this step involves mixing them in a specific ratio and introducing CeO2 powder to ultimately prepare REBCO precursor powder with excellent performance. This process is not merely a simple physical mixing, but rather a precise construction of a superconducting precursor system with balanced chemical composition, controllable texture growth, and enhanced magnetic properties through ratio control and functional doping.

[0065] Step S3: Press the precursor powder combination with the completed auxiliary preparation structure and the preset REBCO preform preparation method to obtain REBCO buffer layer preform and artificial multi-groove REBCO precursor preform;

[0066] Understandably, this step first utilizes the pre-existing auxiliary preparation structure—a square mold pad with regular protrusions—to shape the precursor powder into a precursor block through uniaxial pressure. During this process, the protrusions within the mold form corresponding hemispherical grooves on the powder surface under pressure, achieving pre-forming of the precursor's morphology. Because a precursor powder with high purity and optimized particle size distribution is used, this pressing process not only ensures the forming density but also helps control the stability of the melt interface during subsequent heat treatment, preventing microstructure collapse and non-uniform grain growth.

[0067] Concurrently, the process also includes preparing a REBCO buffer layer preform, the purpose of which is to introduce an intermediate layer with superior chemical composition and thermal stability between the seed crystal and the precursor preform. This buffer layer, by altering the molar ratio of RE123 to RE211 (e.g., increasing the RE211 ratio) and using particle suppressants such as CeO2, regulates the initial nucleation rate, component diffusion paths, and liquid phase wettability, thus playing a dual role in nucleation control and energy buffering. The buffer layer preform is typically fabricated into a small, circular shape, which helps to concentrate the thermal field and structural symmetry, improving nucleation efficiency and texture uniformity during texture growth induced by the top seed crystal. In this step, step S3 includes steps S31, S32, and S33.

[0068] Step S31: Weigh a preset mass of REBCO precursor powder and place it into a mold. Then, apply uniaxial pressure based on the preset auxiliary preparation structure to obtain a square REBCO precursor preform with a multi-groove structure on the upper surface.

[0069] Understandably, this step uses uniaxial pressurization to shape the powder into a square precursor block with a multi-grooved surface. This step not only defines the morphology of the superconducting bulk material's surface geometry but also fundamentally influences subsequent texture growth behavior and superconducting properties. The use of uniaxial pressurization offers both simplicity and consistent molding, ensuring high-fidelity replication of the mold morphology while maintaining tight particle packing. By controlling the pressurization rate and pressure, pressure cracks or density gradients can be avoided, ensuring the integrity and uniform thickness of the precursor block structure.

[0070] Step S32: Mix the purified RE123 raw powder and RE211 raw powder in a molar ratio of RE123:RE211 = 1:0.40, and then mix the mixed RE123 raw powder with RE211 raw powder and 1 wt% CeO2 powder again to obtain a mixed powder.

[0071] Understandably, the reintroduction of 1 wt% CeO2 in this step continues its important role in the main precursor powder. In the buffer layer, CeO2 not only continues to function as a RE211 particle refiner and interface activator, but also forms a RE-Ce enrichment region at high temperatures, which helps control component migration in the liquid phase and avoids chemical disturbance at the seed crystal interface. This is crucial to ensuring that the buffer layer does not disturb the seed and the seed-induced stability is maintained in the "seed-buffer layer-embryo" structure.

[0072] Step S33: Weigh a preset mass of mixed powder, place the preset mass of mixed powder into a cylindrical mold with a diameter of 6 mm for pressure pressing to obtain a circular REBCO buffer layer preform.

[0073] It is understandable that the uniaxial pressure applied during the pressing process must be sufficient to compact the powder particles, forming a preform with a certain mechanical strength and structural integrity before sintering, while avoiding excessive pressure that could lead to cracks, overly dense particles, or structural damage. Because the precursor powder has a high RE211 content and slightly poor particle flowability, the pressing parameters must be optimized to ensure that the edges of the discs do not loosen and the center does not collapse after pressing, thus forming disc-shaped REBCO buffer layer preforms with a fixed geometric morphology using precise molds.

[0074] Step S4: Select a block seed crystal that meets the preset conditions, and assemble and heat treat the block seed crystal, REBCO buffer layer preform and artificial multi-groove REBCO precursor preform that meet the preset conditions based on the top seed crystal melting texture method to obtain REBCO initial block material with multi-groove structure on the surface.

[0075] It is understood that this step involves selecting high-quality bulk seed crystals and using a top seed crystal melting and texturing method for heat treatment. This allows the REBCO buffer layer and the multi-groove precursor to undergo directional recrystallization and epitaxial growth, ultimately producing a high-performance REBCO high-temperature superconducting bulk material with a regular artificial groove surface. In this step, step S4 includes steps S41, S42, and S43.

[0076] Step S41: Select one pre-defined bulk seed crystal with a grain orientation texture greater than a preset threshold and smooth and flat ab crystal plane using a microscope. The bulk seed crystal is a cube with a side length of 2mm.

[0077] It is understandable that if the grain orientation texture in this step is greater than a preset threshold (e.g., greater than 90%), it means that most grains in the seed crystal are aligned in the ab plane direction, possessing clear and continuous crystal orientation channels. This facilitates the preferential growth of grains in the underlying precursor along the same direction, forming a single-domain structure. Furthermore, the smoothness and flatness of the ab crystal plane means that this plane can closely adhere to the buffer layer and the precursor, ensuring uniform heat conduction and nucleation contact, and reducing local voids or crystal plane interference.

[0078] Step S42: Assemble the selected bulk seed crystal, REBCO buffer layer preform, and artificial multi-groove REBCO precursor preform in a top-to-bottom order to form a coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure, wherein the surface of the REBCO precursor preform with the multi-groove structure faces upward, and the bulk seed crystal is centrally located on top of the REBCO buffer layer preform.

[0079] Understandably, this step intentionally exposes the artificial groove structure directly beneath the nucleation region, allowing the groove boundaries, curvature regions, and concave areas to form perturbation induction sources during crystal growth. This promotes preferential grain growth, enhances texture driving force, and provides local magnetic flux pinning centers. This synergistic upper and lower structure not only strengthens the "macro-induction + micro-control" texture growth mechanism but also lays the foundation for subsequently improving the magnetic properties and mechanical stability of the bulk material.

[0080] Step S43: Place the coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure on an alumina ceramic plate and place it in a high-temperature furnace to perform texture growth in an air atmosphere according to preset conditions to obtain the REBCO initial bulk material induced by REBCO seed crystal growth.

[0081] Understandably, this step involves stimulating the directional crystal growth behavior of the previously constructed structure—namely, the coaxially arranged bulk seed crystals, the REBCO buffer layer, and the multi-groove precursor preform—under specific thermal field conditions, ultimately obtaining a REBCO initial bulk material with a macroscopically ordered texture and an artificial groove surface morphology.

[0082] It is understood that in this step, step S43 includes steps S431, S432 and S433.

[0083] Step S431: Control the temperature in the high-temperature furnace to start from room temperature, raise it to 900℃ after 1 hour, and hold it for 3 hours. Then continue heating for 1 hour, raise the temperature in the high-temperature furnace to 1055℃, and hold it for 1 hour.

[0084] Step S432: Reduce the furnace temperature to 1005℃ within 30 minutes, and then reduce the furnace temperature at a cooling rate of 0.2K / h to 0.6K / h, so that the bulk seed crystals selected in the furnace induce the growth of REBCO precursor embryos for 100h.

[0085] It should be noted that the above procedures are a specific temperature control scheme formulated for the preparation of YBCO high-temperature superconducting bulk materials, in which bulk SmBCO is used as a top seed crystal for induced preparation. The aim is to drive the precursor preform to undergo ordered crystal reconstruction under the induction of the bulk seed crystal through a refined heat treatment process, and ultimately obtain YBCO single-domain superconducting bulk materials with good texture and excellent performance. This temperature control step is not only related to melting behavior and nucleation dynamics, but also fundamental to ensuring crystal orientation consistency, structural stability and phase purity.

[0086] It is understandable that this step achieves the directional induction of YBCO precursor growth by bulk seed crystals through a controlled cooling process, ultimately forming a highly ordered, continuous, single-domain superconducting bulk material. This process is not only the essential stage of crystal epitaxial growth, but also the decisive link that determines the microstructure and macroscopic properties of the material.

[0087] In some other embodiments, if the REBCO high-temperature superconducting bulk material is prepared as GdBCO high-temperature superconducting bulk material, and SmBCO bulk seed crystals are used for induction, the temperature in the high-temperature furnace is controlled to start from room temperature, rise to 900°C after 1 hour, and hold for 3 hours, then continue heating for 1 hour, the temperature in the high-temperature furnace is raised to 1055°C, and held for 1 hour; the furnace temperature is then lowered to 1045°C within 30 minutes, and then the furnace temperature is reduced at a cooling rate of 0.2 K / h to 0.6 K / h, so that the bulk seed crystals selected in the furnace induce the growth of GdBCO precursor preforms for 100 hours;

[0088] Understandably, unlike YBCO's lower peritectic temperature, GdBCO, due to the larger ionic radius and higher thermal stability of Gd ions in its crystal structure, requires a slightly higher peak temperature during growth, resulting in stronger melting point stability and peritectic reaction heat resistance. This step involves customized temperature control based on the thermodynamic characteristics of GdBCO to effectively activate the peritectic reaction without causing structural damage.

[0089] Similarly, if the REBCO high-temperature superconducting bulk material is prepared as SmBCO high-temperature superconducting bulk material, and NdBCO bulk seed crystals are used for induction, the temperature in the high-temperature furnace is controlled from room temperature, then raised to 900℃ after 1 hour and held for 3 hours, and then heated for another hour, raising the temperature in the high-temperature furnace to 1075℃ and holding for 1 hour; the furnace temperature is then lowered to 1060℃ within 30 minutes, and then the furnace temperature is reduced at a cooling rate of 0.2K / h to 0.6K / h, so that the bulk seed crystals selected in the furnace induce the growth of SmBCO precursor preforms for 100 hours;

[0090] Understandably, SmBCO has higher thermal stability and a higher peritectic point temperature than YBCO and GdBCO, so a higher peak processing temperature (1075℃) needs to be specially set to ensure that RE123 fully melts in its peritectic reaction temperature range and forms a highly reactive and homogeneous liquid phase system.

[0091] Step S433: After the sample growth is completed, reduce the temperature of the high-temperature furnace to room temperature within 3 hours.

[0092] It is understandable that after the crystal growth is completed, this step involves steadily reducing the temperature of the high-temperature furnace to room temperature within 3 hours to protect the seed crystal-induced growth structure from sudden temperature changes and improve the overall structural stability.

[0093] Step S5: The initial REBCO block with a multi-groove structure on the surface is ground and polished, and then sent into a high-temperature tube furnace with a flowing oxygen atmosphere for oxygen infiltration annealing at 450°C for 200 hours, finally obtaining a REBCO high-temperature superconducting block with an artificial multi-groove structure on the surface.

[0094] It is understandable that this step, through two operations of surface polishing and oxygen infiltration annealing, achieves fine repair of the crystal structure of the superconducting bulk material, control of oxygen content, and activation of superconductivity, thereby ultimately transforming the previously completed structural construction and texture growth results into practical high-temperature superconducting materials with excellent functional properties.

[0095] In the REBCO process described above, the RE elements are selected from rare earth elements Y, Gd, Sm, and Nd. This allows for adaptation to different RE systems with varying staged temperature control parameters, precursor ratios, buffer layer structures, and seed crystal induction methods. This ensures that regardless of the RE element chosen, high-quality multi-groove superconducting bulk materials can be stably obtained within a unified process framework. This design highly demonstrates the method's portability, adjustability, and engineering versatility.

[0096] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0097] The above description is merely a specific embodiment 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 technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves, characterized in that, include: Auxiliary preparation structures are fabricated based on a pre-defined auxiliary preparation structure fabrication method; REBCO raw material powder was prepared by solid-state sintering and homogenized to obtain a precursor powder composition. Based on the completed auxiliary preparation structure and the preset REBCO preform preparation method, the precursor powder combination is pressed to obtain REBCO buffer layer preform and artificial multi-groove REBCO precursor preform. Select a block seed crystal that meets the preset conditions, and assemble and heat treat the block seed crystal, REBCO buffer layer preform and artificial multi-groove REBCO precursor preform that meet the preset conditions based on the top seed crystal melting texture method to obtain REBCO initial block material with multi-groove structure on the surface. The initial REBCO block with a multi-groove structure on the surface was ground and polished, and then sent into a high-temperature tube furnace with a flowing oxygen atmosphere for oxygen infiltration annealing at 450°C for 200 hours, finally obtaining a REBCO high-temperature superconducting block with an artificial multi-groove structure on the surface.

2. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 1, characterized in that... The auxiliary preparation structure is prepared based on a pre-defined auxiliary preparation structure preparation method, including: Select a square mold pad with a preset side length, and divide it into four sector areas based on the diagonal of the upper surface of the square mold pad; Multiple hemispherical protrusions are evenly arranged in the four sector areas. The radius of each hemispherical protrusion is set to be the same, and the ratio of the radius of each hemispherical protrusion to the length of the preset side is set to 3:

80. The ratio of the distance between the centers of two adjacent hemispherical protrusions in each sector area to the length of the preset side is set to 1:

8. The square mold pad with multiple hemispherical protrusions is chamfered to obtain the auxiliary preparation structure.

3. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 1, characterized in that... Based on the completed auxiliary preparation structure and the preset REBCO preform preparation method, the precursor powder assembly is pressed, including: According to the molar ratios RE:Ba:Cu = 1:2:3 and 2:1:1, the original drug powders of RE2O3, BaCO3, and CuO were weighed and mixed separately to prepare the original powders of RE123 and RE211. The original RE123 powder and the original RE211 powder were purified by solid-phase reaction method to obtain purified original RE123 powder and original RE211 powder. The purified RE123 raw powder and RE211 raw powder were weighed and mixed at a molar ratio of 1:0.35 to prepare a precursor powder. 1 wt% CeO2 powder was added to the precursor powder for mixing to obtain a REBCO precursor powder composition.

4. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 3, characterized in that... The original RE123 powder and RE211 powder were purified using a solid-phase reaction method, including: The original RE123 powder was sintered in air at 920°C for 54 hours to obtain a sintered RE123 crystal block, and the original RE211 powder was sintered in air at 930°C for 54 hours to obtain a sintered RE211 crystal block. The sintered RE123 and RE211 crystal blocks were ground and sintered three times to obtain purified RE123 and RE211 powders.

5. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 3, characterized in that... Based on the completed auxiliary preparation structure and the preset REBCO preform preparation method, the precursor powder assembly is pressed, including: Weigh a preset mass of REBCO precursor powder and place it into a mold. Then, apply uniaxial pressure based on the preset auxiliary preparation structure to obtain a square REBCO precursor preform with a multi-groove structure on the upper surface. The purified RE123 raw powder and RE211 raw powder were mixed in a molar ratio of RE123:RE211 = 1:0.40, and the mixed RE123 raw powder was mixed again with RE211 raw powder and 1 wt% CeO2 powder to obtain a mixed powder. Weigh a predetermined amount of mixed powder and place it into a cylindrical mold with a diameter of 6 mm for pressing to obtain a circular REBCO buffer layer preform.

6. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 1, characterized in that, Selecting bulk seed crystals that meet preset conditions, and assembling and heat-treating the bulk seed crystals, REBCO buffer layer preforms, and artificially multi-groove REBCO precursor preforms that meet the preset conditions based on the top seed crystal melt texture method, including: One pre-selected bulk seed crystal with a grain orientation texture greater than a preset threshold and smooth and flat ab crystal plane is selected by microscopy. The bulk seed crystal is a cube with a side length of 2mm. The selected bulk seed crystal, REBCO buffer layer preform, and artificial multi-groove REBCO precursor preform are assembled in a top-to-bottom order to form a coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure, wherein the surface of the REBCO precursor preform with the multi-groove structure faces upward, and the bulk seed crystal is centrally located on top of the REBCO buffer layer preform. The coaxial bulk seed crystal-REBCO buffer layer-REBCO precursor structure is placed on an alumina ceramic plate and placed in a high-temperature furnace for textural growth in an air atmosphere under preset conditions to obtain REBCO initial bulk material induced by REBCO seed crystal growth.

7. The method for preparing a high-temperature superconducting REBCO bulk material with artificial grooves according to claim 6, characterized in that, The text describes a process of texturing a material in a high-temperature furnace under pre-defined conditions in an air atmosphere, including: The temperature in the high-temperature furnace is controlled from room temperature, then increased to 900℃ after 1 hour and held for 3 hours. Then, heating continues for 1 hour, and the temperature in the high-temperature furnace is increased to 1055℃ and held for 1 hour. The furnace temperature was reduced to 1005℃ within 30 minutes, and then the furnace temperature was reduced at a rate of 0.2K / h to 0.6K / h, so that the bulk seed crystals selected in the furnace induced the growth of REBCO precursor embryos for 100h. After the sample growth was completed, the temperature of the high-temperature furnace was reduced to room temperature within 3 hours to obtain the initial REBCO block material.

8. The method for preparing REBCO high-temperature superconducting bulk material with artificial groove structure according to claim 1, characterized in that, The RE in REBCO is selected from rare earth elements Y, Gd, Sm, and Nd.

Images