A method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials

Abstract

The application discloses a preparation method of high-entropy nano artificial pinning center HETiO3 for flux pinning enhancement of superconducting materials, and comprises the following steps: firstly, citric acid is dissolved in deionized water and the pH value is adjusted to obtain a citric acid solution; secondly, a mixed solution of tetrabutyl titanate and acetylacetone is added dropwise into the citric acid solution, and after stirring until the solution is layered, the clear solution A is separated and extracted; thirdly, the clear solution A is added into HE components, and stirring is conducted to obtain the clear solution B; fourthly, ethylene glycol is added into the clear solution B and stirring is conducted until a sol is formed; fifthly, the sol is sequentially subjected to low-temperature calcination and medium-temperature calcination to obtain a powder; and sixthly, the powder is subjected to high-temperature calcination, and HETiO3 is obtained after cooling. According to the preparation method, high-entropy components are introduced, lattice distortion and slow diffusion effect of high-entropy materials are utilized, excellent thermal stability and stronger potential pinning capacity are endowed to the pinning center, and atomic-level uniform mixing of metal ions is realized, and the method is suitable for the field of superconducting materials.

Description

Technical Field

[0001] This invention belongs to the field of superconducting material performance research technology, and in particular relates to a method for preparing high-entropy nano-artificial pinning centers HETiO3 for superconducting material flux pinning enhancement. Background Technology

[0002] Superconductors, as macroscopic quantum materials, exhibit zero resistance, the Meissner effect (perfect diamagnetism), and the Josephson effect (superconducting Cooper pair quantum tunneling). Currently, superconducting materials have disruptive potential in numerous fields, including energy, medicine, transportation, and large-scale scientific facilities, making them a frontier of competition in international strategic emerging industries. In practical applications, flux pinning performance plays a crucial role in the properties of superconductors. The current-carrying capacity of superconducting materials depends on the density, type, and distribution of pinning centers. If the microscopic geometry of the pinning centers matches the coherence length and is uniformly distributed, the stronger the pinning force, the greater the resistance to flux movement, and the higher the current-carrying capacity. Therefore, introducing suitable pinning centers into superconducting materials is key to improving their current-carrying capacity and is also an important scientific issue in the application of superconducting materials.

[0003] In the industrialization research of high-temperature superconducting materials, especially second-generation REBCO (rare-earth barium copper oxide) tapes, the introduction of artificial pinning centers has ensured the high current-carrying capacity of the tapes. By introducing nanoscale defects (such as BaZrO3 nanopillars and Y2O3 nanoparticles), magnetic flux vortices are effectively pinned, significantly improving the critical current density of the tape under a magnetic field. However, as superconducting materials are applied to more extreme environments (higher magnetic fields, wider temperature ranges, and stronger irradiation conditions), traditional single-component or simple composite pinning centers face severe challenges, such as performance saturation and high-temperature failure, insufficient pinning barriers, and limitations in material stability. Therefore, the field of superconducting materials research urgently needs a new type of pinning center with stronger pinning capabilities and higher stability to achieve further breakthroughs in the performance of superconducting materials. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-entropy nano-artificial pinning centers (HETiO3) for flux pinning enhancement of superconducting materials. This method introduces a high-entropy component, utilizing the unique lattice distortion and slow diffusion effects of high-entropy materials to endow the pinning centers with excellent thermal stability and stronger potential pinning ability. Simultaneously, it achieves atomic-level uniform mixing of metal ions, resulting in high phase purity. This provides a new and effective approach to improving the current-carrying performance of superconducting materials under extreme environments, solving the problem that traditional single-component or simple composite pinning centers cannot cope with more extreme environments.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing high-entropy nano-artificial pinning centers HETiO3 for magnetic flux pinning enhancement of superconducting materials, characterized in that the preparation method includes the following steps: Step 1: Dissolve citric acid in deionized water to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir until the solution separates into layers, and then separate and extract to obtain clear solution A; Step 3: Add the clear solution A obtained in Step 2 to the HE component, and stir until the HE component is completely dissolved to obtain clear solution B; the HE component is a high-entropy component. Step 4: Add ethylene glycol to the clear solution B obtained in Step 3 and stir until a sol is formed; Step 5: The sol formed in Step 4 is subjected to low-temperature calcination and medium-temperature calcination in sequence to obtain powder; Step 6: The powder obtained in Step 5 is calcined at high temperature and cooled to obtain high-entropy nano-artificial pinning centers HETiO3.

[0006] This invention utilizes the sol-gel method to prepare high-entropy nanomaterials, offering significant advantages over traditional solid-state sintering methods. The sol-gel method enables atomic-level mixing of multiple dopant elements, effectively avoiding the problems of impurities or element segregation that often arise from uneven mechanical mixing in traditional solid-state reactions. Furthermore, the sol-gel method exhibits good compatibility with precursors such as inorganic salts and organometallic compounds, making it relatively easy to integrate various metal elements with disparate properties (such as rare earth, transition metals, alkali metals, and alkaline earth metals) into a single crystal lattice. This makes it possible to move the high-entropy nano-artificial pinning centers of this invention from laboratory research to practical applications.

[0007] This invention involves forming a homogeneous sol with HE components, tetrabutyl titanate, citric acid, and ethylene glycol, followed by low-temperature calcination to remove moisture and gel, medium-temperature calcination to remove organic matter and form a pure phase, and finally high-temperature calcination to obtain the final product. High-entropy alloys are composed of multiple main elements in equimolar or near-equimolar amounts, and their extremely high configurational entropy makes them prone to forming simple solid solution phases. Simultaneously, high-entropy alloys exhibit lattice distortion effects, where elements of different atomic sizes are mixed in the same lattice, resulting in severe lattice distortion and thus creating a huge stress field within the material. Furthermore, the presence of multiple elements endows the material with excellent thermal stability, and the synergistic effect of these elements can produce comprehensive performance exceeding that of a single component. Therefore, this invention improves the performance of superconducting materials by replacing the traditional nano-pinned phase composed of one or two or three oxides with high-entropy compound nanoparticles composed of multiple cations in a high-entropy form.

[0008] The preparation method of the high-entropy nano-artificial pinning center HETiO3 for magnetic flux pinning enhancement of superconducting materials is characterized in that, in step one, the citric acid is dissolved in deionized water and the pH value is adjusted to 6-8.

[0009] This invention facilitates the subsequent formation of titanium citrate by adjusting the solution to a near-neutral state.

[0010] The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the stirring temperature in steps two and three is 80℃~90℃.

[0011] This invention controls temperature to prevent solution boiling, increase reactivity, and accelerate solvent evaporation.

[0012] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the HE component in step three is composed of Na, K, Bi and RE, wherein RE is a rare earth element.

[0013] This invention provides point pinning by introducing alkali metal elements and local magnetism by introducing rare earth elements into the system.

[0014] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the chemical formula of the high-entropy nano-artificial pinning centers HETiO3 is (RE1 2-x RE2 x (Na) 2-y K y BiTiO3, where RE1 is La or Pr, RE2 is Sm or Nd, x takes values ​​of 0.8~1.2, and y takes values ​​of 0.8~1.2.

[0015] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the stirring temperature in step four is 80℃~85℃, and the pH value is adjusted to 4~5 after adding ethylene glycol to the clarified solution B to facilitate the rapid formation of sol.

[0016] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the molar ratio of the total metal ions of tetrabutyl titanate and HE component in step two to citric acid in step one is 1:1.5~2, and the molar ratio of ethylene glycol to citric acid in step one is 2~3:1.

[0017] This invention controls the component ratio to ensure complete chelation of metal ions and rapid formation of a stable sol.

[0018] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the low-temperature calcination temperature in step five is 160℃~200℃, and the low-temperature calcination time is 12h~24h; the medium-temperature calcination temperature is 700℃~800℃, and the medium-temperature calcination time is 6h~12h.

[0019] This invention employs segmented calcination to ensure that organic components and nitrate ions in the gel are completely removed during the calcination process.

[0020] The preparation method of the high-entropy nano-artificial pinning center HETiO3 for flux pinning enhancement of superconducting materials is characterized in that, in step six, the powder is ground and pressed into tablets before high-temperature calcination, and the grinding time is 20 min to 30 min.

[0021] This invention achieves a more complete reaction by performing pretreatment before grinding, pressing, and calcination; and avoids uneven mixing due to too short a grinding time and agglomeration of nanoparticles due to too long a grinding time by controlling the grinding time.

[0022] The above-mentioned method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials is characterized in that the high-temperature calcination temperature in step six is ​​1050℃~1100℃, the high-temperature calcination time is 5h~10h, and the cooling rate is 5℃ / h~10℃ / h.

[0023] This invention avoids the formation of impurity phases by controlling temperature conditions and processing in a stable temperature environment.

[0024] Compared with the prior art, the present invention has the following advantages: 1. This invention designs a high-entropy compound HETiO3 by combining metal cations and titanate groups in a high-entropy component. It utilizes the slow diffusion effect, the ability to hinder atomic migration, and the excellent thermal stability of high-entropy materials. Furthermore, under the unique multi-element synergistic effect of high-entropy materials, HETiO3 has the potential to have stronger pinning ability. This provides an ideal approach for improving the performance of superconducting materials and for studying the formation kinetics of high-entropy phases in superconducting matrices and the influence of extreme local strain on superconductivity.

[0025] 2. This invention prepares high-entropy nano-artificial pinning centers HETiO3 by using a sol-gel method, which involves forming a complex between metal cations and citric acid, and then adding ethylene glycol to form a sol. Compared with the solid-phase reaction method, this method can achieve uniform dispersion of metal ions, more complete reaction, and higher phase purity.

[0026] 3. This invention prepares high-entropy nano-artificial pinning centers HETiO3 using the sol-gel method, which has the advantage of simple phase formation and is suitable for application to the preparation of other high-entropy spin-frustrated materials.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a SEM image of the high-entropy nano-artificial pinning center HETiO3 prepared in Example 1 of the present invention.

[0029] Figure 2 The EDS spectrum of the high-entropy nano-artificial pinning center HETiO3 prepared in Example 1 of this invention. Detailed Implementation

[0030] Example 1 The preparation method of this embodiment includes the following steps: Step 1: According to the chemical formula (La) 2-x Sm x (Na) 2-y K y BiTiO3, where x is 0.8 and y is 0.8, weigh Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, NaNO3, and tetrabutyl titanate, and weigh citric acid with a total molar number of 1.5 times the metal ions; dissolve citric acid in deionized water, and adjust the pH to 6.0 by adding 28% ammonia water to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir at 80°C until the solution separates into layers, and then separate and extract to obtain a clear solution A; the molar ratio of tetrabutyl titanate to acetylacetone is 1:1. Step 3: Add the clear solution A obtained in Step 2 to the mixture of Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, and NaNO3, and stir at 80°C until the HE component is completely dissolved to obtain clear solution B; Step 4: Add ethylene glycol to the clear solution B obtained in Step 3, adjust the pH to 4.0 with 2 mol / L dilute nitric acid, and stir at 85°C until a sol is formed; the molar ratio of ethylene glycol to citric acid is 2:1. Step 5: Calcine the sol formed in step 4 at 160°C for 12 hours in air to obtain a gel, and then calcine it at 700°C for 6 hours in air to obtain a powder. Step 6: Grind the powder obtained in Step 5 for 30 minutes, compress it into tablets, and then calcine it at 1100℃ for 10 hours in air atmosphere. Cool it at a rate of 5℃ / h to obtain high-entropy nano-artificial pinning centers HETiO3.

[0031] Microscopic analysis was performed on the high-entropy nano-artificial pinning centers HETiO3 prepared in this embodiment, such as... Figure 1 and Figure 2 As shown, the high-entropy nano-artificial pinning center HETiO3 has a nanoscale size, and the doping elements are distributed throughout the sample, proving that the metal cations in the high-entropy component were successfully doped.

[0032] Example 2 The preparation method of this embodiment includes the following steps: Step 1: According to the chemical formula (La) 2-x Sm x (Na) 2-y K y BiTiO3, where x is 1.2 and y is 1.2, weigh Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, NaNO3, and tetrabutyl titanate, and weigh citric acid with a total molar number of 1.5 times the metal ions; dissolve citric acid in deionized water, and adjust the pH to 6.3 by adding 28% ammonia water to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir at 85°C until the solution separates into layers, and then separate and extract to obtain a clear solution A; the molar ratio of tetrabutyl titanate to acetylacetone is 1:1. Step 3: Add the clear solution A obtained in Step 2 to the mixture of Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, and NaNO3, and stir at 85°C until the HE component is completely dissolved to obtain clear solution B; Step 4: Add ethylene glycol to the clear solution B obtained in Step 3, adjust the pH to 4.6 with 2 mol / L dilute nitric acid, and stir at 85°C until a sol is formed; the molar ratio of ethylene glycol to citric acid is 2.3:1. Step 5: Calcine the sol formed in step 4 at 170°C for 16 hours in air to obtain a gel, and then calcine it at 750°C for 8 hours in air to obtain a powder. Step 6: Grind the powder obtained in Step 5 for 20 minutes, compress it into tablets, and then calcine it at 1050℃ for 5 hours in an air atmosphere. Cool it at a rate of 10℃ / h to obtain high-entropy nano-artificial pinning centers HETiO3.

[0033] Testing revealed that the high-entropy nano-artificial pinning centers HETiO3 obtained in this embodiment have nanoscale dimensions, and all dopant elements are distributed within the sample.

[0034] Example 3 The preparation method of this embodiment includes the following steps: Step 1: According to the chemical formula (Pr) 2-x Nd x (Na) 2-y K y BiTiO3, where x is 1.0 and y is 1.0, weigh Bi(NO3)3, Pr(NO3)3, Nd(NO3)3, KNO3, NaNO3, and tetrabutyl titanate, and weigh citric acid with a total molar number of 1.5 times the metal ions; dissolve citric acid in deionized water, and adjust the pH to 7.2 by adding 28% ammonia water to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir at 90°C until the solution separates into layers, and then separate and extract to obtain a clear solution A; the molar ratio of tetrabutyl titanate to acetylacetone is 1:1. Step 3: Add the clear solution A obtained in Step 2 to the mixture of Bi(NO3)3, Pr(NO3)3, Nd(NO3)3, KNO3, and NaNO3, and stir at 90°C until the HE component is completely dissolved to obtain clear solution B; Step 4: Add ethylene glycol to the clear solution B obtained in Step 3, adjust the pH to 4.8 with 2 mol / L dilute nitric acid, and stir at 85°C until a sol is formed; the molar ratio of ethylene glycol to citric acid is 2.6:1. Step 5: Calcine the sol formed in step 4 at 190°C for 18 hours in air to obtain a gel, and then calcine it at 800°C for 10 hours in air to obtain a powder. Step 6: Grind the powder obtained in Step 5 for 25 minutes, compress it into tablets, and then calcine it at 1060℃ for 8 hours in air atmosphere. Cool it at a rate of 8℃ / h to obtain high-entropy nano-artificial pinning centers HETiO3.

[0035] Testing revealed that the high-entropy nano-artificial pinning centers HETiO3 obtained in this embodiment have nanoscale dimensions, and all dopant elements are distributed within the sample.

[0036] Example 4 The preparation method of this embodiment includes the following steps: Step 1: According to the chemical formula (La) 2-x Sm x (Na) 2-y K yBiTiO3, where x is 1.2 and y is 1.2, weigh Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, NaNO3, and tetrabutyl titanate, and weigh citric acid with a total molar number of metal ions equal to 2.0; dissolve citric acid in deionized water, and adjust the pH to 8.0 by adding 28% ammonia solution to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir at 88°C until the solution separates into layers, and then separate and extract to obtain a clear solution A; the molar ratio of tetrabutyl titanate to acetylacetone is 1:1. Step 3: Add the clear solution A obtained in Step 2 to the mixture of Bi(NO3)3, Sm(NO3)3, La(NO3)3, KNO3, and NaNO3, and stir at 88°C until the HE component is completely dissolved to obtain clear solution B; Step 4: Add ethylene glycol to the clear solution B obtained in Step 3, adjust the pH to 5.0 with 2 mol / L dilute nitric acid, and stir at 85°C until a sol is formed; the molar ratio of ethylene glycol to citric acid is 3:1. Step 5: Calcine the sol formed in step 4 at 200°C for 24 hours in air to obtain a gel, and then calcine it at 800°C for 12 hours in air to obtain a powder. Step 6: Grind the powder obtained in Step 5 for 30 minutes, compress it into tablets, and then calcine it at 1080℃ for 6 hours in air atmosphere. Cool it at a rate of 6℃ / h to obtain high-entropy nano-artificial pinning centers HETiO3.

[0037] Testing revealed that the high-entropy nano-artificial pinning centers HETiO3 obtained in this embodiment have nanoscale dimensions, and all dopant elements are distributed within the sample.

[0038] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-entropy nano-artificial pinning centers (HETiO3) for flux pinning enhancement of superconducting materials, characterized in that, The preparation method includes the following steps: Step 1: Dissolve citric acid in deionized water to obtain a citric acid solution; Step 2: Add the mixture of tetrabutyl titanate and acetylacetone dropwise to the citric acid solution obtained in Step 1, stir until the solution separates into layers, and then separate and extract to obtain clear solution A; Step 3: Add the clear solution A obtained in Step 2 to the HE component, and stir until the HE component is completely dissolved to obtain clear solution B; the HE component is a high-entropy component. Step 4: Add ethylene glycol to the clear solution B obtained in Step 3 and stir until a sol is formed; Step 5: The sol formed in Step 4 is subjected to low-temperature calcination and medium-temperature calcination in sequence to obtain powder; Step 6: The powder obtained in Step 5 is calcined at high temperature and cooled to obtain high-entropy nano-artificial pinning centers HETiO3.

2. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The citric acid mentioned in step one is dissolved in deionized water and the pH value is adjusted to 6-8.

3. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The stirring temperature in steps two and three is 80℃~90℃.

4. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The HE component mentioned in step three is composed of Na, K, Bi, and RE, where RE is a rare earth element.

5. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 4, characterized in that, The specific chemical formula of the high-entropy nano-artificial pinning center HETiO3 is (RE1 2-x RE2 x (Na) 2-y K y BiTiO3, where RE1 is La or Pr, RE2 is Sm or Nd, x takes values ​​of 0.8~1.2, and y takes values ​​of 0.8~1.

2.

6. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The stirring temperature in step four is 80℃~85℃, and the pH value is adjusted to 4~5 after adding ethylene glycol to the clarified solution B.

7. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The molar ratio of the total metal ions of tetrabutyl titanate in step two and HE component in step three to citric acid in step one is 1:1.5~2, and the molar ratio of ethylene glycol in step four to citric acid in step one is 2~3:

1.

8. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The low-temperature calcination in step five is carried out at a temperature of 160℃~200℃ for 12h~24h; the medium-temperature calcination is carried out at a temperature of 700℃~800℃ for 6h~12h.

9. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, In step six, the powder is ground and compressed before high-temperature calcination, and the grinding time is 20 min to 30 min.

10. The method for preparing high-entropy nano-artificial pinning centers HETiO3 for flux pinning enhancement of superconducting materials according to claim 1, characterized in that, The high-temperature calcination temperature in step six is ​​1050℃~1100℃, the high-temperature calcination time is 5h~10h, and the cooling rate is 5℃ / h~10℃ / h.

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