High-entropy iron-based superconducting compound for superconducting wire and preparation method of high-entropy iron-based superconducting compound

Abstract

A high-entropy iron-based superconducting compound for a superconducting wire has the following chemical formula: HEO1-xFeAsFx, x is greater than or equal to 0 and less than or equal to 0.5; wherein HE is composed of 3-14 metal elements selected from the group IIIB of the periodic table of elements and metal elements selected from the group IA-IIA of the periodic table of elements; on the basis of the atom number of HE, the atom proportions of 3-14 metal elements of the IIIB family of the periodic table are respectively 2%-60%, the atom proportions of the metal elements of the IA-IIA family of the periodic table are respectively 0-10%, and the sum of the atom proportions of the metal elements in HE is equal to 100%. The invention further provides a method for preparing the high-entropy iron-based superconducting compound for the superconducting wire. HEO1-xFeAsFx is synthesized through a solid-phase reaction, wherein x is greater than or equal to 0 and less than or equal to 0.5. The high-entropy iron-based superconducting compound is high in chemical stability and does not react with a wrapping material.

Description

Technical Field

[0001] The present invention belongs to the technical field of superconducting materials. Specifically, the present invention relates to a high-entropy iron-based superconducting compound for superconducting wire materials and a preparation method thereof. Background Art

[0002] Superconducting materials exhibit macroscopic quantum phenomena such as zero resistance and perfect diamagnetism, and are typical quantum materials.

[0003] Currently, thousands of superconducting materials have been discovered. However, based on the screening of comprehensive properties such as current-carrying performance, thermal stability, and formability, the superconducting materials with practical application prospects are limited. Among low-temperature superconducting materials (T c <25K), the mainly commercialized ones are NbTi (T c = 9.5K) and Nb3Sn (T c = 18K); among high-temperature superconducting materials (T c ≥25K), the currently practically valuable high-temperature superconducting materials include: bismuth-based superconductors, copper oxide superconductors, magnesium diboride (MgB2), and iron-based superconductors, etc.

[0004] The currently applied traditional low-temperature superconductors NbTi and Nb3Sn have low Tc and relatively low upper critical fields. Copper oxide superconductors have high anisotropy, and when preparing superconducting wire materials, the superconducting current-carrying performance decreases due to anisotropy. MgB2 lacks effective flux pinning centers and porous characteristics, and the critical current density (Jc) is relatively low. While the upper critical field of iron-based superconductors is high (100 - 250T), much higher than that of MgB2 (40T) and traditional low-temperature superconductors NbTi (11T) and Nb3Sn (23T), and the anisotropy of iron-based superconductors is relatively low (1 < γ H <2), much smaller than that of copper oxide superconductors (5 < γ H <20), which has great advantages for the production of superconducting wire materials. The intrinsic flux pinning ability of iron-based superconductors is strong, and the critical current density (J c ) can still maintain a relatively high level at high fields. These characteristics mean that iron-based superconducting materials have unique application advantages in high-field fields.

[0005] The main method for preparing iron-based superconducting wire tapes is the powder-in-tube (PIT) method. This method is designed for processing superconducting materials with poor plasticity. The specific process is to first mix the starting powder evenly under a protective gas atmosphere and then fill it into a metal tube. Then, the metal tube is formed into a wire through cold working processes such as rotary swaging, drawing, and rolling. Finally, the formed wire is heat-treated under a protective atmosphere to form a superconducting wire with good connection performance. However, there is a problem that the iron-based superconductor reacts with the superconducting core material and the sheath material, generating impurity phases such as REAs and REOF (RE is a rare earth metal element), which hinders the transmission of superconducting current. At the same time, due to the diffusion reaction of As element into the sheath, the composition of the superconducting core deviates greatly, increasing the porosity generation rate and resulting in a decrease in superconducting performance.

[0006] Therefore, there is an urgent need for a superconducting wire with high chemical stability and no reaction with the sheath material. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-entropy iron-based superconducting compound for superconducting wire. This high-entropy iron-based superconducting compound has high chemical stability, is easy to process, and does not react with the sheath material when used for superconducting wire.

[0008] The above object of the present invention is achieved by the following technical solutions.

[0009] In the context of the present invention, the term "high-entropy material" refers to a material composed of more than 3 metal elements selected from Group IIIB of the periodic table.

[0010] On the one hand, the present invention provides a high-entropy iron-based superconducting compound for superconducting wire, which has the following chemical formula:

[0011] HEO 1-x FeAsF x , 0 ≤ x ≤ 0.5;

[0012] Wherein, HE is composed of 3-14 metal elements selected from Group IIIB of the periodic table and metal elements of Group IA-IIA of the periodic table;

[0013] Based on the atomic number of HE, the atomic proportions of the 3-14 metal elements of Group IIIB of the periodic table are independently 2%-60%, and the atomic proportions of the metal elements of Group IA-IIA of the periodic table are independently 0-10%, and the sum of the atomic proportions of each metal element in HE is equal to 100%.

[0014] The inventors of the present invention have found that when the HE site of the iron-based superconducting compound is selected as a high-entropy material, a high-entropy iron-based superconducting compound with high chemical stability can be obtained, and when this high-entropy iron-based superconducting compound is used in superconducting wires, it does not react with the sheath material. The high-entropy material of the present invention improves the brittleness of conventional iron-based superconductors, enhances grain connectivity, and improves stability, effectively suppressing the reaction between the iron-based superconductor and the sheath material.

[0015] Preferably, in the high-entropy iron-based superconducting compound for superconducting wires of the present invention, HE is composed of 3-14 metal elements selected from Sc, Y, La, Sm, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0016] Preferably, in the high-entropy iron-based superconducting compound for superconducting wires of the present invention, the metal elements of Group IA-IIA of the periodic table are selected from one or more of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba.

[0017] Preferably, in the high-entropy iron-based superconducting compound for superconducting wires of the present invention, the high-entropy iron-based superconducting compound is single crystal or polycrystal; preferably polycrystal.

[0018] In a specific embodiment of the present invention, the high-entropy iron-based superconducting compound can be in the form of powder, thin sheet, granule, and bulk.

[0019] On the other hand, the present invention provides a method for preparing the high-entropy iron-based superconducting compound for superconducting wires of the present invention, which includes the following steps:

[0020] Mix HE, As, Fe, Fe2O3, and fluorides of each metal element in HE evenly, and carry out a first solid-phase reaction to obtain HEO 1-x FeAsF x , 0≤x≤0.5; or

[0021] Mix HE and As evenly according to the molar ratio HE:As = 1:1, then carry out a second solid-phase reaction to obtain HEAs; subsequently, mix HEAs, Fe, Fe2O3, and fluorides of each metal element in HE evenly, and carry out a third solid-phase reaction to obtain HEO 1-x FeAsF x , 0≤x≤0.5.

[0022] HE is composed of 3-14 metal elements of Group IIIB of the periodic table and metal elements of Group IA-IIA of the periodic table;

[0023] The atomic proportion of 3-14 metal elements in Group IIIB of the periodic table is independently 2%-60%, the atomic proportion of metal elements in Group IA-IIA of the periodic table is independently 0-10%, and the sum of the atomic proportions of each metal element in HE is equal to 100%.

[0024] Preferably, in the method of the present invention, the second solid-phase reaction is carried out under the following conditions: the reaction temperature is 500-900 °C, and the reaction time is 10-15 hours.

[0025] Preferably, in the method of the present invention, the first solid-phase reaction and the third solid-phase reaction are each independently carried out under the following conditions: the reaction temperature is 700-1300 °C, and the reaction time is 20-150 hours.

[0026] Preferably, in the method of the present invention, HE is composed of 3-14 metal elements selected from Sc, Y, La, Sm, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0027] Preferably, in the method of the present invention, the metal elements in Group IA-IIA of the periodic table are selected from one or more of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba.

[0028] Preferably, in the method of the present invention, the high-entropy iron-based superconducting compound is polycrystalline.

[0029] In an embodiment of the present invention, the material for sheathing the superconducting wire of the present invention can be a metal with a certain ductility such as Fe, Cu, Ag, Ta, Nb, Ti, etc., or a sheathing material prepared from a silver-based composite material such as Ag / Fe, Ag / Cu, Ag / stainless steel, Ag / Monel, etc. The ratio of the inner diameter to the outer diameter of the tube is (6-8):10.

[0030] In an embodiment of the present invention, the sheathing material can have various forms. One is to form a wire alone, and the other is to form a wire by compounding multiple materials, such as Figure 1 shown.

[0031] In an embodiment of the present invention, the heat treatment is carried out 2 times, before and after rolling, and the temperature is in the range of 300 °C to 1500 °C.

[0032] In an embodiment of the present invention, the atomic proportion of the Group IA and IIA metal elements that improve the material stability and brittleness is preferably within the scope of the present invention, because if the doping ratio is too large, it will affect the superconducting properties.

[0033] In an embodiment of the present invention, the high-entropy iron-based superconducting compound can be used to prepare superconducting wire materials by an in-situ method or a pre-position method. The in-situ method involves uniformly mixing precursor powders and loading them into a sheath material. After drawing and rolling into a wire strip, a superconducting phase is formed through heat treatment reaction. The pre-position method involves loading precursor powders (HEO 1-x FeAsF x , 0 ≤ x ≤ 0.5) that have been sintered into a superconducting phase into a sheath material for processing. The precursor powders can be HE, As, Fe, Fe2O3, and fluorides of each metal element in HE, or HEAs, Fe, Fe2O3, and fluorides of each metal element in HE.

[0034] In an embodiment of the present invention, after the iron-based precursor powders are uniformly mixed, they are filled into a sheath material, and wire materials are formed through cold working processes such as rotary swaging, drawing, and rolling. Finally, the wire strip is heat-treated in a protective atmosphere, where the heat treatment temperature is 300°C to 1500°C.

[0035] The present invention has the following beneficial effects:

[0036] The high-entropy treatment of the iron-based superconducting material improves the brittleness of the material itself, making it easy to process, and has high chemical stability and is not prone to reaction with the sheath material. Therefore, the selection range of the sheath material can be expanded, which is beneficial to cost reduction and enables the large-scale application of the iron-based high-entropy superconducting material.

[0037] The high-entropy iron-based superconducting compound of the present invention has excellent grain boundary coupling, which is more conducive to the formation of a texture structure and can significantly improve the J of the superconducting wire material c . The improvement of the upper critical magnetic field is beneficial to the large-scale low-cost application of the high-entropy iron-based superconducting material in the high-field field. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings, where:

[0039] Figure 1 is a cross-sectional schematic diagram of a superconducting wire material according to a specific embodiment of the present invention;

[0040] Figure 2 is the XRD pattern of the high-entropy iron-based superconducting compound Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 in Example 1;

[0041] Figure 3 is the XRD pattern of the high-entropy iron-based superconducting compound Sc 0.1 Y 0.1 La0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 XRD pattern of;

[0042] Figure 4 For the high-entropy iron-based superconducting compound K of Example 3 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 XRD pattern of;

[0043] Figure 5 For the high-entropy iron-based superconducting compound Sc of Example 1 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 Comparison chart of XRD patterns after mixing evenly with iron powder and heat treatment, where (a) is the XRD of the sample and iron powder mixed evenly, and (b) is the XRD pattern of the sample and iron powder mixed evenly after heat treatment;

[0044] Figure 6 For the high-entropy iron-based superconducting compound Sc of Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 Comparison chart of XRD patterns after mixing evenly and heat treatment with iron powder, where (a) is the XRD of the sample and iron powder mixed evenly, and (b) is the XRD pattern of the sample and iron powder mixed evenly after heat treatment;

[0045] Figure 7 For the high-entropy iron-based superconducting compound K of Example 3 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1Comparison diagram of XRD patterns after mixing evenly with iron powder and after heat treatment, where (a) is the XRD of the sample mixed evenly with iron powder, and (b) is the XRD pattern of the sample mixed evenly with iron powder after heat treatment;

[0046] Figure 8 For the high-entropy iron-based superconducting compound LaO 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after mixing evenly with iron powder and after heat treatment, where (a) is the XRD of the sample mixed evenly with iron powder, and (b) is the XRD pattern of the sample mixed evenly with iron powder after heat treatment;

[0047] Figure 9 For the high-entropy iron-based superconducting compound La 0.5 Ce 0.5 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after mixing evenly with iron powder and after heat treatment, where (a) is the XRD of the sample mixed evenly with iron powder, and (b) is the XRD pattern of the sample mixed evenly with iron powder after heat treatment;

[0048] Figure 10 For the high-entropy iron-based superconducting compound Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after mixing evenly with Cu powder and after heat treatment, where (a) is the XRD of the sample mixed evenly with Cu powder, and (b) is the XRD pattern of the sample mixed evenly with Cu powder after heat treatment;

[0049] Figure 11 For the high-entropy iron-based superconducting compound Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 Schematic diagram of the unit cell structure;

[0050] Figure 12 For the high-entropy iron-based superconducting compound Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 Schematic diagram of the unit cell structure of Detailed implementation manners

[0051] The present invention will be further described in detail below in conjunction with the detailed implementation manners. The examples given are only for clarifying the present invention, rather than limiting the scope of the present invention.

[0052] Example 1

[0053] Preparation of the high-entropy iron-based superconducting compound Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1

[0054] Mix rare earth powders Sc, Y, La, Sm, Pr with equal molar ratios evenly, prepare HEAs powder according to the molar ratio of HE:As = 1:1, and react at 700 °C for 12 hours after compaction to obtain HEAs.

[0055] Mix HEAs, Fe2O3, Fe, ScF3, YF3, LaF3, SmF3, PrF3 evenly according to the molar ratio of HEAs:Fe2O3:Fe:HEF3 = 2.97:1:1:0.03 (where HEF3 is the equimolar ratio mixture of ScF3, YF3, LaF3, SmF3, PrF3), and react at 1200 °C for 50 hours to obtain the powdered polycrystalline high-entropy iron-based superconducting material Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 .

[0056] Example 2

[0057] The high-entropy iron-based superconducting compound Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9FeAsF 0.1 Preparation of

[0058] Mix rare earth powders Sc, Y, La, Sm, Pr, Ce, Nd, Gd, Dy, Eu with equal molar ratio evenly, prepare HEAs powder according to the ratio of HE:As = 1:1, react at 900 °C for 12 hours after compaction to obtain HEAs.

[0059] Mix HEAs, Fe2O3, Fe, ScF3, YF3, LaF3, SmF3, PrF3, CeF3, NdF3, GdF3, DyF3 evenly according to the molar ratio of HEAs:Fe2O3:Fe:HEF3 = 2.97:1:1:0.03 (where HEF3 is the equal molar ratio mixture of ScF3, YF3, LaF3, SmF3, PrF3, CeF3, NdF3, GdF3, DyF3), react at 1200 °C for 50 hours to obtain the powdered polycrystalline high-entropy iron-based superconducting material Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 。

[0060] Example 3

[0061] High-entropy iron-based superconducting compound K 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 Preparation of

[0062] Mix rare earth powders La, Ce, Pr with equal molar ratio evenly, prepare HEAs powder according to the ratio of HE:As = 1:1, react at 900 °C for 12 hours after compaction to obtain HEAs.

[0063] Mix K, HEAs, Fe2O3, Fe, LaF3, LaF3, PrF evenly according to the molar ratio of K:HEAs:Fe2O3:Fe:HEF3 = 0.1:2.97:1:1:0.03 (where HEF3 is the equal molar ratio mixture of LaF3, LaF3, PrF), react at 1200 °C for 50 hours to obtain the powdered polycrystalline high-entropy iron-based superconducting material K 0.1 La 0.3 Ce 0.3 Pr 0.3O 0.9 FeAsF 0.1 。

[0064] Example 4

[0065] The high-entropy iron-based superconducting compound Sc of Example 1 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O .0.9 FeAsF 0.1 was respectively encapsulated into copper tubes, iron tubes and silver tubes with an outer diameter of 10 mm and an inner diameter of 8 mm, and then drawn and reduced in diameter to 0.5 mm copper sleeves, iron sleeves and silver sleeves respectively to prepare copper sleeve Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 、iron sleeve Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 and silver sleeve Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 。

[0066] Example 5

[0067] The high-entropy iron-based superconducting compound Sc of Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0. 1O 0.9 FeAsF 0.1 was respectively encapsulated into copper tubes, iron tubes and silver tubes with an outer diameter of 10 mm and an inner diameter of 8 mm, and then drawn and reduced in diameter to 0.7 mm copper sleeves, iron sleeves and silver sleeves respectively to prepare copper sleeve Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 、 iron sleeve Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 and silver sleeve Sc 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 。

[0068] Example 6

[0069] The high-entropy iron-based superconducting compound K of Example 3 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 was respectively encapsulated into copper tubes, iron tubes and silver tubes with an outer diameter of 10 mm and an inner diameter of 8 mm, and then drawn and reduced in diameter to 0.6 mm copper sleeves, iron sleeves and silver sleeves to respectively prepare copper sleeve K 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 、 iron sleeve K 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 and silver sleeve K 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 。

[0070] Comparative Example 1

[0071] Preparation of iron-based superconducting compound LaO 0.9 FeAsF 0.1

[0072] Prepare LaAs powder from rare earth powder La in a ratio of La:As = 1:1. After compaction, react at 900 °C for 12 hours to obtain LaAs.

[0073] Mix LaAs, Fe2O3, Fe, and LaF3 evenly in a molar ratio of LaAs:Fe2O3:Fe:LaF3 = 2.97:1:1:0.03, and react at 1200 °C for 50 hours to obtain a powdered polycrystalline high-entropy iron-based superconducting material LaO 0.9 FeAsF 0.1 .

[0074] Encapsulate the obtained high-entropy iron-based superconducting compound LaO 0.9 FeAsF 0.1 into copper tubes, iron tubes, and silver tubes with an outer diameter of 10 mm and an inner diameter of 8 mm respectively, and then draw and reduce the diameter to 0.6 mm copper sleeves, iron sleeves, and silver sleeves respectively to prepare copper sleeve LaO 0.9 FeAsF 0.1 , iron sleeve LaO 0.9 FeAsF 0.1 and silver sleeve LaO 0.9 FeAsF 0.1 .

[0075] Comparative Example 2

[0076] Preparation of iron-based superconducting compound La 0.5 Ce 0.5 O 0.9 FeAsF 0.1

[0077] Prepare La 0.5 Ce 0.5 As powder from rare earth powder La in a ratio of La:Ce:As = 0.5:0.5:1. After compaction, react at 900 °C for 12 hours to obtain La 0.5 Ce 0.5 As.

[0078] Mix La 0.5 Ce 0.5 As, Fe2O3, Fe, LaF3, and CeF3 in a molar ratio of La 0.5 Ce 0.5 ​​Mix 2.97:1:1:0.015:0.015 of As:Fe2O3:Fe:LaF3:CeF3 evenly and react at 1200 °C for 50 hours to obtain a powdery polycrystalline high-entropy iron-based superconducting material La 0.5 Ce 0.5 O 0.9 FeAsF 0.1 。

[0079] Encapsulate the obtained high-entropy iron-based superconducting compound La 0.5 Ce 0.5 O 0.9 FeAsF 0.1 into copper tubes, iron tubes and silver tubes with an outer diameter of 10 mm and an inner diameter of 8 mm respectively, and then draw and reduce the diameter to 0.6 mm copper sleeves, iron sleeves and silver sleeves respectively to prepare copper sleeve LaO 0.9 FeAsF 0.1 、iron sleeve LaO 0.9 FeAsF 0.1 and silver sleeve LaO 0.9 FeAsF 0.1 。

[0080] Stability test

[0081] In order to compare the reaction problem between the iron-based superconducting compound and the cladding material during the heat treatment process, the iron-based superconducting compounds and iron powder prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are mixed evenly, and the iron-based superconducting compound and copper powder prepared in Example 2 are mixed evenly. By testing the XRD comparison diagrams of the mixed materials before and after heat treatment, the stability of the materials is judged. The heat treatment temperature is 800 °C.

[0082] Figure 5 Show the comparison diagrams of the XRD of the high-entropy iron-based superconducting compound Sc 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 after being mixed evenly with iron powder and after heat treatment, where (a) is the XRD of the sample and iron powder mixed evenly, and (b) is the XRD diagram of the sample and iron powder mixed evenly after heat treatment.

[0083] Figure 6 Show the high-entropy iron-based superconducting compound Sc of Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd0.1 Dy 0. 1Eu 0.1 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after uniformly mixing with iron powder and heat treatment, where (a) is the XRD of the sample uniformly mixed with iron powder, and (b) is the XRD pattern of the sample uniformly mixed with iron powder after heat treatment.

[0084] Figure 7 Showing the high-entropy iron-based superconducting compound K of Example 3 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after uniformly mixing with iron powder and heat treatment, where (a) is the XRD of the sample uniformly mixed with iron powder, and (b) is the XRD pattern of the sample uniformly mixed with iron powder after heat treatment.

[0085] Figure 8 Showing the high-entropy iron-based superconducting compound LaO of Comparative Example 1 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after uniformly mixing with iron powder and heat treatment, where (a) is the XRD of the sample uniformly mixed with iron powder, and (b) is the XRD pattern of the sample uniformly mixed with iron powder after heat treatment.

[0086] Figure 9 Showing the high-entropy iron-based superconducting compound La of Comparative Example 2 0.5 Ce 0.5 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after uniformly mixing with iron powder and heat treatment, where (a) is the XRD of the sample uniformly mixed with iron powder, and (b) is the XRD pattern of the sample uniformly mixed with iron powder after heat treatment.

[0087] Figure 10 Showing the high-entropy iron-based superconducting compound Sc of Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 Comparison diagram of XRD patterns after uniformly mixing with Cu powder and heat treatment, where (a) is the XRD of the sample uniformly mixed with Cu powder, and (b) is the XRD pattern of the sample uniformly mixed with Cu powder after heat treatment.

[0088] By comparison, in the test of iron powder, Sc in Example 1 0.2 Y 0.2 La 0.2 Sm 0.2 Pr 0.2 O 0.9 FeAsF 0.1 The XRD of the high-entropy superconducting iron-based material and iron powder shows that the peak of iron element has no obvious change, indicating the stable existence of iron powder. Sc in Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 The peak of iron element also has no change, indicating the stable existence of iron powder. K in Example 3 0.1 La 0.3 Ce 0.3 Pr 0.3 O 0.9 FeAsF 0.1 The peak of iron element also has no change, indicating the stable existence of iron powder. LaO in Comparative Example 1 0.9 FeAsF 0.11 And La in Comparative Example 2 0.5 Ce 0.5 O 0.9 FeAsF 0.1 The XRD shows that the peak of iron becomes weaker and other impurity peaks appear, indicating that iron reacts with the superconducting material. To verify this conclusion, it is found that Sc in Example 2 0.1 Y 0.1 La 0.1 Sm 0.1 Pr 0.1 Ce 0.1 Nd 0.1 Gd 0.1 Dy 0.1 Eu 0.1 O 0.9 FeAsF 0.1 The XRD of the copper element before and after the homogeneous heat treatment of the high-entropy superconducting iron-based material and copper powder shows no obvious change, indicating that the copper powder can also exist stably (such as Figure 10As shown. In summary, it can be found that with the increase of entropy, the chemical stability of superconducting materials improves, which proves that the high-entropy materials do not react with iron, and the advantages of the stability of high-entropy materials can be extended to inexpensive cladding materials such as iron and copper. It helps to realize the commercial application of iron-based superconducting materials with the help of inexpensive cladding materials.

Claims

1. A high-entropy iron-based superconducting compound for superconducting wire, which has the following chemical formula: HEO 1-x FeAsF x , 0 ≤ x ≤ 0.5; Among them, HE is composed of 3-14 metal elements selected from Group IIIB of the periodic table of elements and metal elements of Group IA-IIA of the periodic table of elements; Based on the atomic number of HE, the atomic proportions of the 3-14 metal elements of Group IIIB of the periodic table of elements are independently 2%-60%, and the atomic proportions of the metal elements of Group IA-IIA of the periodic table of elements are independently 0%-10%, and the sum of the atomic proportions of each metal element in HE is equal to 100%.

2. The high-entropy iron-based superconducting compound for superconducting wire according to claim 1, wherein, HE is composed of 3-14 metal elements selected from Sc, Y, La, Sm, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

3. The high-entropy iron-based superconducting compound for superconducting wires according to claim 1, wherein, The metal elements of Group IA-IIA of the periodic table of elements are selected from one or more of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba.

4. The high-entropy iron-based superconducting compound for superconducting wires according to claim 1, wherein, The high-entropy iron-based superconducting compound is single crystal or polycrystalline; preferably polycrystalline.

5. A method for preparing the high-entropy iron-based superconducting compound for superconducting wire according to claims 1-4, which comprises the following steps: Mix HE, As, Fe, Fe2O3 and fluorides of various metal elements in HE evenly, and carry out the first solid-phase reaction to obtain HEO 1-x FeAsF x , 0 ≤ x ≤ 0.5; or HE and As are uniformly mixed in a molar ratio of HE:As = 1:1, and then a second solid-phase reaction is carried out to obtain HEAs; subsequently, HEAs, Fe, Fe2O3, and fluorides of each metal element in HE are uniformly mixed, and a third solid-phase reaction is carried out to obtain HEO 1-x FeAsF x , 0 ≤ x ≤ 0.5; Among them, HE is composed of 3-14 metal elements selected from Group IIIB of the periodic table of elements and metal elements of Group IA-IIA of the periodic table of elements; The atomic proportions of the 3-14 metal elements of Group IIIB of the periodic table of elements are independently 2%-60%, and the atomic proportions of the metal elements of Group IA-IIA of the periodic table of elements are independently 0%-10%, and the sum of the atomic proportions of each metal element in HE is equal to 100%.

6. The method according to claim 5, wherein, The second solid-phase reaction is carried out under the following conditions: the reaction temperature is 500-900 °C, and the reaction time is 10-15 hours.

7. The method according to claim 5, wherein, The first solid-phase reaction and the third solid-phase reaction are each independently carried out under the following conditions: the reaction temperature is 700-1300 °C, and the reaction time is 20-150 hours.

8. The method according to claim 5, wherein HE is composed of 3-14 metal elements selected from Sc, Y, La, Sm, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

9. The method according to claim 5, wherein The metal elements of Group IA-IIA of the periodic table of elements are selected from one or more of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba.

10. The method according to claim 5, wherein, The high-entropy iron-based superconducting compound is polycrystalline.

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