Method for reducing impurities in potassium fluoride doped iron-based superconductor

Abstract

The invention discloses a method for reducing impurities in a potassium fluoride doped iron-based superconductor, belongs to the technical field of iron-based superconducting materials, and provides a method for removing impurities in an Ae1-xKxFe2As2 superconductor prepared from potassium fluoride, which comprises the following steps: in the aspect of raw materials, the molar ratio of Ae element in the preparation raw materials is increased; the sintered blocks are crushed in a glove box under Ar atmosphere protection, the crushed powder is loaded into a ball milling tank containing a solvent, the solvent is methyl alcohol, ethyl alcohol, diethyl ether, acetone or n-hexane, the ball milling tank is loaded into a ball mill for ball milling, the ball milling rotating speed is 100-500 r / min, and the ball milling time is 0.5-10 h; and after the ball milling is completed, removing the upper-layer solvent, and drying the residual powder to obtain the superconductor with impurities removed. According to the method for removing the impurities in the potassium fluoride doped iron-based superconductor, the phase purity of the final product can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron-based superconducting materials, and in particular relates to a method for reducing impurities in potassium fluoride-doped iron-based superconductors. Background Art

[0002] In 2008, Tokyo Institute of Technology in Japan discovered a new type of iron-based high-temperature superconductor. (x=0.05-0.12) with T c =26 KJ Am. Chem. Sco. 130, 3296-3297(2008)], its superconducting transition temperature reaches 26 K, which has attracted wide attention in the field of superconducting research. According to the different parent structures, iron-based superconductors are mainly divided into four categories: 1111 system, 122 system, 11 system and 111 system. In 122 system superconductors, Ae 1-x K x Fe2As2 (Ae = Ba, Sr, Ca, Eu), 0 < x < 1, has the characteristics of high critical current density, high upper critical field, small anisotropy, and small dependence of critical current on strong magnetic field. It has broad application prospects in medium and low temperature and strong magnetic fields, and is expected to be widely used in medical, energy, transportation, national defense and other fields.

[0003] Ae 1-x K x The raw materials in Fe2As2 superconductors are relatively active and easily react with air and water. Therefore, the preparation of iron-based superconductors needs to be carried out under the protection of an argon atmosphere. However, the K element is very active. Therefore, Patent: ZL202110934020.6 provides a method for preparing Ae2As2 using potassium fluoride as a raw material. 1-x K x The method for preparing Fe2As2 superconductor improves the safety and practicality of preparation and is conducive to mass production. However, in the iron-based superconductor prepared by this method, impurities such as FeAs and BaF2 exist in the final product, which affects the phase purity. Summary of the invention

[0004] The purpose of the present invention is to provide a method for reducing impurities in potassium fluoride-doped iron-based superconductors and improving the phase purity of the final product.

[0005] The technical solution of the present invention is as follows:

[0006] A method for reducing impurities in potassium fluoride-doped iron-based superconductors comprises the following steps:

[0007] Step 1: Increase the molar ratio of the Ae element in the raw material to (1-x)-(1-x / 10).

[0008] Step 2: crush the sintered block in a glove box under Ar atmosphere protection, and put the crushed powder into a ball mill filled with a solvent.

[0009] Step 3: Place the ball mill jar into a ball mill for ball milling.

[0010] Step 4: After the ball milling is completed, the upper layer of solvent is removed and the remaining powder is dried on a heating platform to obtain a superconductor after impurities are removed.

[0011] In the above technical solution, the potassium fluoride-doped iron-based superconductor is potassium fluoride-doped Ae 1-x K x Fe2As2 superconductor, where Ae = Ba, Sr, Ca, Eu, 0 < x < 1.

[0012] In the above technical solution, in step 2, the solvent is methanol, ethanol, ether, acetone or n-hexane.

[0013] In the above technical solution, in step 3, the ball milling speed is 100-500 r / min.

[0014] In the above technical solution, in step 3, the ball milling time is 0.5-10 h.

[0015] In the above technical solution, in step 4, the drying temperature is 80-300 °C.

[0016] In the above technical solution, in step 4, the drying time is 10-300 min.

[0017] Compared with the existing preparation method, the present invention has the following beneficial effects:

[0018] (1) Preparation of Ae using potassium fluoride 1-x K x When Fe2As2 superconductor is produced, the F element reacts chemically with the Ae element first, resulting in the lack of the Ae element in the final effective product, thereby causing the production of FeAs. The present invention increases the Ae element content, makes up for the Ae element in the final effective product, and thus inhibits the production of FeAs impurity phase.

[0019] (2) Preparation of Ae using potassium fluoride 1-x K x Fe2As2 superconductor inevitably generates AeF2 impurities. The organic solvent ball milling process proposed in the present invention can reduce the AeF2 impurity content without affecting the quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The X-ray diffraction (XRD) diagram of the superconductor after ball milling with ethanol as the solvent when the Ba content was increased to 0.8.

[0021] Figure 2 It is Ba prepared from potassium fluoride 0.6 K 0.4 XRD pattern of Fe2As2 superconductor. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0023] Example 1

[0024] In the preparation of potassium fluoride doped Ba 0.6 K 0.4 When producing Fe2As2 superconductor, the Ba content is increased to 0.8.

[0025] After sintering, the superconducting block was crushed in a glove box under the protection of Ar atmosphere, and the crushed powder was put into a ball mill filled with ethanol with a purity of 95%.

[0026] The ball mill jar was placed into a ball mill for ball milling at a speed of 200 r / min and a ball milling time of 1 h.

[0027] After the ball milling is completed, the upper layer of solvent is poured off in the glove box, and the remaining mixture is dried on a heating platform at a drying temperature of 150 °C for 120 min. The final powder is a superconductor after impurities are removed.

[0028] The product in Example 1 was subjected to XRD analysis using a Bruker D8 X-ray diffractometer in a test range of 10°≤2θ≤80°. The XRD results are shown in FIG. Figure 1 As shown. Figure 1 and Figure 2 By comparing the product prepared by the method not used in this example, it can be concluded that no diffraction peak of FeAs impurity phase is found in the superconductor prepared in Example 1, and the diffraction peak intensity of BaF2 impurity is greatly reduced, indicating that the phase purity of the product prepared in the example is improved.

[0029] Example 2

[0030] In the preparation of potassium fluoride doped Ba 0.6 K0.4 When producing Fe2As2 superconductor, the Ba content is increased to 0.8.

[0031] After sintering, the superconducting block was crushed in a glove box under the protection of Ar atmosphere, and the crushed powder was put into a ball mill filled with 99% pure n-hexane.

[0032] The ball mill jar was placed into a ball mill for ball milling at a speed of 200 r / min and a ball milling time of 1 h.

[0033] After the ball milling is completed, the upper layer of solvent is poured off in the glove box, and the remaining mixture is dried on a heating platform at a drying temperature of 150 °C for 120 min. The final powder is a superconductor after impurities are removed.

[0034] The results of the product of Example 2 are the same as those of the product of Example 1.

[0035] Example 3

[0036] In the preparation of potassium fluoride doped Ba 0.6 K 0.4 When producing Fe2As2 superconductor, the Ba content is increased to 0.85.

[0037] After sintering, the superconducting block was crushed in a glove box under the protection of Ar atmosphere, and the crushed powder was put into a ball mill filled with ethanol with a purity of 95%.

[0038] The ball mill jar was placed into a ball mill for ball milling at a speed of 200 r / min and a ball milling time of 1 h.

[0039] After the ball milling is completed, the upper layer of solvent is poured off in the glove box, and the remaining mixture is dried on a heating platform at a drying temperature of 150 °C for 120 min. The final powder is a superconductor after impurities are removed.

[0040] The results of the product of Example 3 are the same as those of the product of Example 1.

[0041] Example 4

[0042] In the preparation of potassium fluoride doped Sr 0.6 K 0.4 When producing Fe2As2 superconductor, the Ba content is increased to 0.8.

[0043] After sintering, the superconducting block was crushed in a glove box under the protection of Ar atmosphere, and the crushed powder was put into a ball mill filled with ethanol with a purity of 95%.

[0044] The ball mill jar was placed into a ball mill for ball milling at a speed of 200 r / min and a ball milling time of 1 h.

[0045] After the ball milling is completed, the upper layer of solvent is poured off in the glove box, and the remaining mixture is dried on a heating platform at a drying temperature of 150 °C for 120 min. The final powder is a superconductor after impurities are removed.

[0046] The results of the product of Example 4 are the same as those of the product of Example 1.

[0047] Example 5

[0048] In the preparation of potassium fluoride doped Ba 0.6 K 0.4 When producing Fe2As2 superconductor, the Ba content is increased to 0.8.

[0049] After sintering, the superconducting block was crushed in a glove box under the protection of Ar atmosphere, and the crushed powder was put into a ball mill filled with ethanol with a purity of 95%.

[0050] The ball mill jar was placed into a ball mill for ball milling at a speed of 400 r / min and a ball milling time of 0.5 h.

[0051] After the ball milling is completed, the upper layer of solvent is poured off in the glove box, and the remaining mixture is dried on a heating platform at a temperature of 200 °C for 600 min. The final powder is a superconductor after impurities are removed.

[0052] The results of the product of Example 5 are the same as those of the product of Example 1.

[0053] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for reducing impurities in potassium fluoride-doped iron-based superconductors, characterized in that: The steps include: Step 1, increasing the molar ratio of the Ae element in the raw material to (1-x)-(1-x / 10); Step 2, crushing the sintered block in a glove box under Ar atmosphere, and putting the crushed powder into a ball mill filled with solvent; Step 3, loading the ball mill jar into a ball mill for ball milling; Step 4: After the ball milling is completed, the upper layer of solvent is removed and the remaining powder is dried on a heating platform to obtain a superconductor after impurities are removed.

2. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: The potassium fluoride-doped iron-based superconductor is potassium fluoride-doped Ae 1-x K x Fe2As2 superconductor, where Ae = Ba, Sr, Ca, Eu, 0 <x < 1。 3. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: In step 2, the solvent is methanol, ethanol, ether, acetone or n-hexane.

4. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: In step 3, the ball milling speed is 100-500 r / min.

5. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: In step 3, the ball milling time is 0.5-10 h.

6. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: In step 4, the drying temperature is 80-300 °C.

7. The method for reducing impurities in potassium fluoride-doped iron-based superconductors according to claim 1, characterized in that: In step 4, the drying time is 10-300 min.

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