Target material for growing CuC-1223 superconducting thin film by PLD (Pulsed Laser Deposition) as well as preparation method and application of target material

Abstract

The invention belongs to the technical field of high-temperature superconducting materials, and particularly relates to a target material for growing a CuC-1223 superconducting thin film through PLD and a preparation method and application of the target material. Wherein the molar ratio of the three metal elements of Ba, Ca and Cu is 2: (2-3): (3.5-4.5); and the three metal elements of Ba, Ca and Cu are uniformly distributed under the nanoscale. When the target material provided by the invention is used for PLD deposition, plasma plume with stable components and accurate stoichiometric ratio can be provided, so that an epitaxial film with few impure phases and high crystal quality is grown. According to the thin film, the intrinsic superconducting characteristic of the CuC-1223 phase can be more fully reflected, the higher superconducting critical temperature (Tc) and the more excellent current-carrying performance are obtained, the preparation process is good in reproducibility, the target batch consistency is high, and a solid foundation is provided for reliable and repeated preparation of the high-performance superconducting thin film.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature superconducting materials technology, specifically relating to a target material for PLD growth of CuC-1223 superconducting thin films, its preparation method, and its application. Background Technology

[0002] Copper-based high-temperature superconducting materials, especially (CuC)Ba2Ca2Cu3O y The CuC-1223 system, due to its high irreversible field and critical current density, has attracted widespread attention in high-voltage applications. To realize its application potential, obtaining high-quality epitaxial thin films is crucial. Pulsed laser deposition (PLD) is one of the mainstream methods for preparing such films. Its principle involves using a laser to ablate a target, causing the target's components to be transported and deposited onto the substrate in the form of a plasma plume. Therefore, the quality of the target itself, especially the uniformity of its chemical composition and phase purity, directly determines the stability of the plasma plume, thus having a decisive impact on the final film's crystallinity, phase composition, and superconducting properties.

[0003] Currently, the traditional solid-state reaction method is commonly used to prepare CuC-1223 phase targets in this field. This method typically uses powders such as BaCO3, CaCO3, and CuO as initial raw materials, mechanically mixes them according to a target stoichiometric ratio, ball-mills them, press them into sheets, and then sinter them at high temperatures (usually above 800℃) for a long time. While this method is simple, it has some inherent limitations. Due to the complex thermodynamic properties of the Ba-Ca-Cu-O quaternary system, the diffusion rates of Ba, Ca, Cu, and O differ when they react directly in the solid state, making it difficult to directly form a single, stable CuC-1223 compound. During high-temperature sintering, the system tends to follow local thermodynamic equilibrium, generating multiple thermodynamically more stable intermediate phases, such as BaCuO2, Ca2CuO3, and incompletely reacted CuO.

[0004] These by-reaction products exist in the target material as micron-scale particles, resulting in a final target material that is essentially a mechanical mixture of multiple compounds, rather than a homogeneous single-phase material. When using such a heterogeneous target material for PLD deposition, the plasma plumes ablated from different areas of the target surface by laser spot scanning show fluctuations in elemental composition depending on whether the laser strikes different phases such as BaCuO2, Ca2CuO3, or CuO. This unstable elemental supply interferes with the atomic-scale ordered arrangement at the film growth interface, making the epitaxial growth process complex and difficult to control.

[0005] The direct consequence is that impurity phases that do not match the lattice structure of the main phase are often introduced into the prepared thin films. These impurity phases not only disrupt the continuity of the superconducting phase and form weak connections in current carrying capacity, but also introduce lattice defects and stress fields, becoming magnetic flux pinning centers or scattering centers, thus significantly affecting the superconducting properties of the thin film, especially leading to a decrease in the superconducting critical temperature and an increase in the transition width.

[0006] Although researchers have attempted to improve uniformity by optimizing sintering temperature, time, atmosphere, and employing multiple grinding and sintering processes, the inherent solid-solid reaction mechanism of solid-state reaction methods limits the fundamental problem of uniform mixing of elements at the atomic / molecular scale, making it difficult to effectively solve. Therefore, developing novel target preparation techniques capable of achieving highly uniform distribution of Ba, Ca, and Cu elements is a direction worthy of in-depth exploration for improving the quality and performance consistency of CuC-1223 superconducting thin films. Summary of the Invention

[0007] This application aims to overcome the shortcomings of existing technologies where uneven element distribution and easy generation of impurity phases occur when preparing CuC-1223 superconducting thin films using solid-state reaction methods, resulting in poor superconducting performance of the thin films. Therefore, this application provides a target material for PLD growth of CuC-1223 superconducting thin films, its preparation method, and its application to overcome the above-mentioned deficiencies.

[0008] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a target material for PLD growth of CuC-1223 superconducting thin films. The target material is composed of Ba, Ca, Cu, and O elements; wherein, The molar ratio of the three metallic elements Ba, Ca, and Cu is 2:(2-3):(3.5-4.5); and, The three metallic elements Ba, Ca, and Cu are uniformly distributed at the nanoscale.

[0009] As shown in the background section, in existing technologies, the target material for preparing CuC-1223 thin films mainly relies on solid-state reaction methods. The inherent solid-solid reaction mechanism of this method makes it difficult to uniformly mix Ba, Ca, and Cu elements at the micrometer scale, resulting in a final target material that is a mechanical mixture of various impurity phases such as BaCuO2 and Ca2CuO3. When using such a target for PLD deposition, the plasma plume composition generated by laser ablation is unstable, directly introducing a large number of impurity phases into the epitaxially grown film, severely degrading its superconducting properties. This constitutes the starting point for the problem that this invention aims to solve.

[0010] Faced with this challenge, conventional improvement approaches often involve optimizing within the framework of solid-state methods, such as adjusting the sintering temperature, extending the reaction time, or performing multiple grinding and sintering processes. However, these methods cannot fundamentally solve the problem of uneven mixing at the atomic / molecular scale.

[0011] Compared to existing technologies, this invention abandons the traditional concept of pursuing a single crystalline phase for the target material itself. Instead, it creatively proposes the preparation of an amorphous phase target material with a specific non-stoichiometric ratio and uniform elemental distribution at the nanoscale. Specifically, the molar ratio of Ba, Ca, and Cu in this target material is set to 2:(2-3):(3.5-4.5), a ratio that significantly deviates from the stoichiometric ratio (2:2:3) of the target CuC-1223 superconducting phase. This is because PLD itself is a non-equilibrium process, with preferential volatilization and redistribution of elements occurring during laser ablation, plasma plume transport, and thin film deposition. By ensuring a relative abundance of Ca and Cu in the target material, this invention provides the necessary compositional adjustment space for these kinetic processes, thereby ensuring that the vapor phase composition reaching the substrate surface is closer to the optimal stoichiometric ratio required for the formation of the target superconducting phase. In contrast, if a target material with a fixed stoichiometric ratio is used, it is easily deviated from the stoichiometric ratio due to elemental loss during the complex PLD process, making it difficult to obtain a pure phase.

[0012] More importantly, this invention provides a structural basis for the aforementioned non-stoichiometric design by achieving a uniform mixing distribution of the target material at the nanoscale. The term "nanoscale uniform distribution" means that the three elements Ba, Ca, and Cu are interwoven within the target material with an unprecedented degree of uniformity, far exceeding the capabilities of solid-state methods. This can be seen from… Figure 1 and Figure 2 This is visually demonstrated through stark contrast: Figure 1 The results show that the elemental distribution signals of the target material of the present invention are uniform and continuous, while Figure 2 This clearly demonstrates the severe segregation and granulation of elemental distribution in the solid-state target. This nanoscale uniformity ensures that during laser ablation, regardless of the location of the laser spot on the target, the excited plasma plume maintains a highly consistent and stable elemental ratio, laying a solid foundation for uniform epitaxial growth of the thin film. This amorphous, nanoscale-uniform target structure makes it more like a "homogeneous reservoir" during the PLD process, continuously and stably providing precise film-forming materials, thereby effectively suppressing the root cause of impurity phase growth induced by uneven material distribution.

[0013] Ultimately, this target material resulted in significant improvements in technical performance. The phase purity of the CuC-1223 superconducting thin film prepared using the target material of this invention was greatly improved. For example... Figure 3As shown, compared with films grown using solid-state targets, the characteristic diffraction peaks of the target superconducting phase in its X-ray diffraction pattern are sharper, while the intensity of the diffraction peaks of the impurity phase is significantly suppressed. This directly translates to optimization of superconducting properties; the superconducting critical transition onset temperature of the prepared film is effectively increased, and the superconducting transition range is also narrower, indicating higher crystallinity and phase purity of the film.

[0014] In summary, this invention cleverly utilizes the non-equilibrium characteristics of PLD technology by transforming the target design from "crystalline phase + stoichiometry" to "non-stoichiometry + nanoscale uniformity," thereby synergistically solving two interrelated problems: elemental uniformity and phase formation stoichiometry control. This provides a novel material basis for the reliable preparation of high-performance CuC-1223 superconducting thin films.

[0015] Secondly, the present invention also provides a method for preparing the target material as described above, employing a sol-gel method, comprising the following steps: S1. According to the molar ratio of metal ions Ba:Ca:Cu = 2:(2-3):(3.5-4.5), soluble metal salts containing barium, calcium, and copper are dissolved in a solvent to form a mixed salt solution; S2. Add a complexing agent to the mixed salt solution to form a sol; S3. The sol is converted into a gel and dried to obtain a dried gel precursor; S4. The dried gel precursor is pre-calcined in an oxygen-containing atmosphere to obtain precursor powder; S5. The precursor powder is pressed into shape and sintered to obtain the target material.

[0016] As mentioned above, in existing technologies, traditional solid-state reaction methods, due to their inherent solid-solid reaction mechanism, inevitably form micron-sized impurity particles such as BaCuO2 and Ca2CuO3 in the target material, even after multiple grinding and high-temperature sintering. This inhomogeneity of the initial raw materials creates hidden dangers for subsequent PLD processes, leading to fluctuations in the composition of the plasma plume generated by laser ablation, ultimately introducing impurity phases into the grown film and impairing its superconducting properties.

[0017] The core of the preparation method in this application lies in the sol-gel process constructed in steps S1 to S3. First, a soluble metal salt is used as a raw material, allowing it to completely ionize in a solvent, thus achieving Ba… 2+ Ca 2+ Cu 2+The initial uniform distribution of ions in the solution. More importantly, by adding a complexing agent and forming a sol and gel, the spatial confinement effect of the polymer network structure is used to "freeze" this uniform mixing state at the ion scale. This method eliminates the unavoidable local composition fluctuations in solid-phase mechanical mixing from the source, laying the structural foundation for obtaining nanoscale uniform target materials.

[0018] Furthermore, this method creatively employs a non-stoichiometric ratio of Ba:Ca:Cu = 2:(2-3):(3.5-4.5) in step S1, which is not the stoichiometric ratio of the target superconducting phase. This design reflects a profound understanding of the PLD kinetics. PLD is a complex non-equilibrium process involving ablation, transport, and deposition, with preferential volatilization of elements. Ensuring a relative abundance of Ca and Cu in the target material provides a necessary compositional buffer for the deposition process, ensuring that the final gas phase composition reaching the substrate more precisely meets the requirements for forming a pure CuC-1223 phase. In contrast, using a stoichiometric target material may deviate from the ideal ratio due to losses during transport, making it difficult to obtain high-purity films.

[0019] The beneficial effects of this method have been conclusively verified by the performance of the final product. Experiments show that the target material prepared by this invention exhibits highly uniform distribution signals of Ba, Ca, and Cu elements, in stark contrast to existing solid-state target materials. This high uniformity at the nanoscale directly translates into extreme stability of the plasma plume composition during PLD deposition. Ultimately, the superconducting thin film grown using the target material prepared by this method shows significantly suppressed impurity peaks in its X-ray diffraction pattern, thus substantially increasing the superconducting critical onset temperature.

[0020] In summary, the preparation method provided by this invention, through the ingenious combination of sol-gel technology and non-stoichiometric design, successfully prepared a target material with a unique nano-uniform structure, effectively overcoming the key material bottleneck in the preparation of high-purity CuC-1223 superconducting thin films, and bringing about significant technological progress.

[0021] Preferably, in step S2, the complexing agent is an organic polyacid or its salt.

[0022] Preferably, the organic polyacid is selected from at least one of citric acid, ethylenediaminetetraacetic acid, and tartaric acid.

[0023] Preferably, in step S2, the ratio of the total moles of the complexing agent to the total moles of the metal ions is 1:1 to 3:1.

[0024] Preferably, the barium-containing soluble metal salt is barium nitrate or barium acetate; The calcium-containing soluble metal salt is calcium nitrate or calcium acetate; The copper-containing soluble metal salt is copper nitrate or copper acetate.

[0025] Preferably, in step S4, the pre-firing is carried out in an oxygen-containing atmosphere at a temperature of 300-500°C for 2-5 hours.

[0026] Preferably, in step S5, the sintering is carried out in an oxygen-containing atmosphere, the sintering temperature is 800-850℃, and the sintering time is 10-30 hours.

[0027] Thirdly, the present invention also provides a target material as described above for preparing (CuC)Ba2Ca2Cu3O by pulsed laser deposition. y Applications in superconducting thin films.

[0028] Preferably, (CuC)Ba2Ca2Cu3O is prepared using the target material via pulsed laser deposition. y The superconducting critical onset temperature of superconducting thin films is higher than 110K.

[0029] Fourthly, the present invention also provides a superconducting device comprising (CuC)Ba2Ca2Cu3O prepared by the method described above. y Superconducting thin films.

[0030] Therefore, the present invention has the following beneficial effects: (1) This invention achieves molecular-level uniform mixing of Ba, Ca, and Cu ions in the liquid phase through the sol-gel method and fixes them to the gel network through complexation, so that the elemental distribution of the final target material reaches the nanoscale uniformity, fundamentally solving the problem of micron-scale impurities caused by elemental segregation in the traditional solid phase method. (2) The present invention effectively inhibits the formation and growth of impurity phases such as BaCuO2 and Ca2CuO3, so that the target material is almost composed of a uniform mixture of Ba, Ca, Cu and O; (3) Using the target material provided by this invention for PLD deposition can provide plasma plume with stable composition and precise stoichiometry, thereby growing epitaxial films with fewer impurities and higher crystal quality. The film can more fully reflect the intrinsic superconducting characteristics of the CuC-1223 phase, and obtain a higher superconducting critical temperature (Tc) and better current carrying capacity; (3) The preparation process has good reproducibility and strong batch consistency of target materials, which provides a solid foundation for the reliable and repeated preparation of high-performance superconducting thin films. Attached Figure Description

[0031] Figure 1 The surface morphology and compositional distribution of Cu, O, Ba, and Cu of the target material prepared by the sol-gel method in Example 1.

[0032] Figure 2 Comparative Example 1: Surface morphology and Cu, O, Ba, and Cu composition distribution of the target material prepared by solid-state sintering.

[0033] Figure 3 XRD and RT images of CuC-1223 phase epitaxial films grown using targets prepared by sol-gel in Example 1 and targets prepared by solid-state sintering in Comparative Example 1. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0035] Example 1 This embodiment provides a target material for PLD growth of CuC-1223 superconducting thin films and its preparation method, which is as follows: S1. Weigh barium nitrate, calcium nitrate tetrahydrate, and copper nitrate trihydrate precisely according to the molar ratio of Ba:Ca:Cu = 2:2.5:4, dissolve them in deionized water, and stir until homogeneous to obtain a mixed salt solution.

[0036] S2. Add citric acid to the above solution to make the molar ratio of citric acid to total metal ions 2:1. Adjust the pH of the solution to approximately 6 using ammonia. Place the solution in an 80°C water bath and heat with stirring. The solution gradually becomes viscous and eventually forms a sol.

[0037] S3. Transfer the sol to an oven and dry at 160°C for 24 hours to obtain a dry, porous gel block.

[0038] S4. After grinding the gel block, place it in a muffle furnace and heat it to 500°C in air at a rate of 5°C / min. Hold the temperature for 2 hours to fully decompose the organic matter and obtain a loose black precursor powder.

[0039] S5. The above powder was pressed into discs with a diameter of 25.4 mm (1 inch) under a pressure of 200 MPa. The discs were placed in a tube furnace and sintered at 800 °C at a rate of 5 °C / min for 20 hours under an oxygen atmosphere. After sintering, a slow cooling process was performed to finally obtain a dense BaCaCuO target.

[0040] Example 2 This embodiment provides a target material for PLD growth of CuC-1223 superconducting thin films and its preparation method, which is as follows: S1. Weigh barium nitrate, calcium nitrate tetrahydrate, and copper nitrate trihydrate precisely according to the molar ratio of Ba:Ca:Cu = 2:2.2:3.8, dissolve them in deionized water, stir well, and obtain a clear mixed salt solution.

[0041] S2. Add analytical grade monohydrate citric acid to the above mixed salt solution, so that the molar ratio of citric acid to total metal ions is approximately 1.5:1. Continue stirring for about 3 hours until the solution gradually turns into a blue transparent sol.

[0042] S3. Transfer the obtained sol to a forced-air drying oven and dry at 120°C for 12 hours to fully convert it into a dry gel precursor.

[0043] S4. Place the dried gel precursor in an alumina crucible and then into a box-type muffle furnace. Heat to 400°C at a heating rate of 5°C / min under a flowing oxygen atmosphere (flow rate 100 mL / min), and pre-calcine at this temperature for 3 hours. After natural cooling, remove and lightly grind to obtain a fluffy precursor powder.

[0044] S5. Take an appropriate amount of precursor powder and put it into a mold with a diameter of 50 mm. Press it into shape under a pressure of 20 MPa. Place the compacted preform along with the mold into a tube furnace and heat it to 830 °C at a rate of 3 °C / min under an oxygen atmosphere. Sinter at this temperature for 20 hours. Then slowly cool it to room temperature at a rate of 2 °C / min to obtain a dense black circular target material.

[0045] Example 3 This embodiment provides a target material for PLD growth of CuC-1223 superconducting thin films and its preparation method, which is as follows: S1. Weigh barium nitrate, calcium nitrate tetrahydrate, and copper nitrate trihydrate precisely according to the molar ratio of Ba:Ca:Cu = 2:3:3.5, dissolve them in deionized water, and stir until homogeneous to obtain a mixed salt solution.

[0046] S2. Add ethylenediaminetetraacetic acid (EDTA, molar mass 292.24 g / mol) to the above mixed salt solution, so that the molar ratio of EDTA to total metal ions is approximately 1:1. Since EDTA has low solubility in water, add an appropriate amount of ammonia to adjust the pH to neutral to promote its dissolution.

[0047] S3. Slowly evaporate the sol at 80°C to form a gel, then dry it at 100°C for 24 hours to ensure complete removal of the solvent.

[0048] S4. Preheat the dried gel to 300°C in a flowing air atmosphere at a rate of 3°C / min for 5 hours.

[0049] S5. After pressing the pre-calcined powder into tablets, sinter them in an oxygen atmosphere at a temperature of 5°C / min to 800°C for 30 hours to obtain the target material.

[0050] Example 4 This embodiment provides a target material for PLD growth of CuC-1223 superconducting thin films and its preparation method, which is as follows: S1. Weigh out barium acetate, calcium acetate and copper acetate precisely according to the molar ratio of Ba:Ca:Cu = 2:2.5:4.5, dissolve them in deionized water, stir well to obtain a mixed salt solution.

[0051] S2. Add analytical grade monohydrated citric acid to the above mixed salt solution, so that the molar ratio of citric acid to total metal ions is approximately 3:1, and stir at 90°C to form a sol.

[0052] S3. The sol is rapidly dried into a gel at 150°C.

[0053] S4. The dried gel is heated to 500°C at a rate of 10°C / min and preheated for 2 hours in an oxygen atmosphere.

[0054] S5. After pressing the pre-calcined powder into tablets, sinter them in an oxygen atmosphere at a temperature of 2°C / min to 850°C for 10 hours to obtain the target material.

[0055] Comparative Example 1 The target material was prepared using a traditional solid-state method: BaCO3, CaCO3, and CuO powders were weighed according to the same stoichiometric ratio, placed in a ball mill jar, and ball-milled for 24 hours using alcohol as the medium. After drying, the mixed powder was pre-calcined in air at 800-850°C for 20 hours. The pre-calcined powder was then ground, pressed into shape, and sintered in oxygen at 800°C for 20 hours to obtain the reference target material.

[0056] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the stoichiometric ratio of barium nitrate, calcium nitrate tetrahydrate and copper nitrate trihydrate in S1 was changed, and the solution was prepared according to the stoichiometric molar ratio of Ba:Ca:Cu = 2:2:3 in the chemical formula.

[0057] Performance testing: Taking Example 1 and Comparative Example 1 as examples, the compositional distribution of the target materials was analyzed, and the results are as follows: The compositional distribution of the target materials obtained in Example 1 and Comparative Example 1 was tested using EDX in a scanning electron microscope, and the results are as follows. Figure 1 and Figure 2 As shown. Figure 1The results show that the Ba, Ca, Cu, and O components of the target material in Example 1 are evenly distributed. Figure 2 The results show that the target material of Comparative Example 1 is composed of a mechanical mixture of BaCuO2, Ca2CuO, and CuO particles at the micron scale, which cannot form a fully uniform mixture of Ba, Ca, Cu, and O.

[0058] Thin Film Growth and Performance Testing: Under the same PLD process conditions (laser energy, substrate temperature, oxygen pressure, etc.), CuC-1223 thin films were deposited on Hastelloy soft substrates with LMO as the surface buffer layer, using the target materials of Example 1 and Comparative Example 1, respectively. XRD and RT tests were performed on the thin films, and the results are as follows: Figure 3 As shown. Thin films grown on the target material were prepared using the sol-gel method of this invention. XRD revealed a (00l) diffraction peak in the CuC-1223 phase of the epitaxial film, with no obvious impurities. Its superconducting transition onset temperature (T0) was [not specified]. c onset The temperature reaches 115K, with zero resistance (T). c 0 The XRD value is 94K, and the superconducting transition temperature width is narrow. In contrast, the film grown using the solid-state sintered target of Comparative Example 1 shows impurity phase peaks in XRD, exhibits a wider superconducting transition temperature width, and T... c 0 The K value of 68K indicates the presence of compositional inhomogeneity and impurities in the film.

[0059] The superconducting transition onset temperature and zero resistance temperature of the CuC-1223 phase epitaxial films grown using the targets of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 below: Table 1

[0060] The above results demonstrate that the non-stoichiometric BaCaCuO target material prepared by the sol-gel method in this invention exhibits extremely high uniformity of phase element distribution. Its application in PLD technology effectively promotes the growth of pure-phase, high-performance CuC-1223 superconducting thin films, significantly increasing the superconducting critical temperature of the films, and providing an effective material solution to address the impurity phase problem in the preparation of thin films in this system.

[0061] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the inventive concept of the present invention and the content of this specification, or direct / indirect applications in other related technical fields, should be included within the patent protection scope of the present invention.

Claims

1. A target material for PLD growth of CuC-1223 superconducting thin films, characterized in that, The target material is composed of Ba, Ca, Cu, and O elements; wherein, The molar ratio of the three metallic elements Ba, Ca, and Cu is 2:(2-3):(3.5-4.5); and, The three metallic elements Ba, Ca, and Cu are mixed and uniformly distributed at the nanoscale.

2. A method for preparing the target material as described in claim 1, characterized in that, The sol-gel method includes the following steps: S1. According to the molar ratio of metal ions Ba:Ca:Cu = 2:(2-3):(3.5-4.5), soluble metal salts containing barium, calcium, and copper are dissolved in a solvent to form a mixed salt solution; S2. Add a complexing agent to the mixed salt solution to form a sol; S3. The sol is converted into a gel and dried to obtain a dried gel precursor; S4. The dried gel precursor is pre-calcined in an oxygen-containing atmosphere to obtain precursor powder; S5. The precursor powder is pressed into shape and sintered to obtain the target material.

3. The preparation method according to claim 2, characterized in that, In step S2, the complexing agent is an organic polyacid or its salt.

4. The preparation method according to claim 3, characterized in that, The organic polyacid is selected from at least one of citric acid, ethylenediaminetetraacetic acid, and tartaric acid.

5. The preparation method according to any one of claims 2-4, characterized in that, In step S2, the ratio of the total moles of the complexing agent to the total moles of the metal ions is 1:1 to 3:

1.

6. The preparation method according to claim 2, characterized in that, The barium-containing soluble metal salt is barium nitrate or barium acetate; The calcium-containing soluble metal salt is calcium nitrate or calcium acetate; The copper-containing soluble metal salt is copper nitrate or copper acetate.

7. The preparation method according to claim 2, characterized in that, In step S4, the pre-firing is carried out in an oxygen-containing atmosphere at 300-500°C for 2-5 hours. In step S5, the sintering is carried out in an oxygen-containing atmosphere, the sintering temperature is 800-850℃, and the sintering time is 10-30 hours.

8. A target material as described in claim 1 for preparing (CuC) Ba2Ca2Cu3O by pulsed laser deposition. y Applications in superconducting thin films.

9. The application according to claim 9, characterized in that, (CuC)Ba2Ca2Cu3O was prepared using the target material via pulsed laser deposition. y The superconducting critical onset temperature of superconducting thin films is higher than 110K.

10. A superconducting device, characterized in that, (CuC)Ba2Ca2Cu3O prepared by the method of any one of claims 8-9 y Superconducting thin films.

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