A method for reducing impurities in potassium fluoride-doped iron-based superconductors

Abstract

This invention discloses a method for reducing impurities in potassium fluoride-doped iron-based superconductors, belonging to the technical field of iron-based superconducting materials. This invention provides an Al₂O₃ superconductor prepared using potassium fluoride. 1‑ x K x A method for removing impurities from Fe2As2 superconductors includes the following steps: Raw material preparation: increasing the molar ratio of Al (Ae) in the raw materials; Post-processing: pulverizing the sintered bulk material in a glove box under Ar atmosphere protection; loading the pulverized powder into a ball mill jar containing solvent (methanol, ethanol, diethyl ether, acetone, or n-hexane); ball milling the jar in a ball mill at a speed of 100-500 r / min for 0.5-10 h; after ball milling, removing the upper solvent layer and drying the remaining powder to obtain the superconductor after impurity removal. This method for removing impurities from potassium fluoride-doped iron-based superconductors can improve the phase purity of the final product.

Description

Technical Field

[0001] This invention belongs to the field of iron-based superconducting materials technology, specifically relating to a method for reducing impurities in potassium fluoride-doped iron-based superconductors. Background Technology

[0002] In 2008, the Tokyo Institute of Technology in Japan discovered a new type of iron-based high-temperature superconductor [LaO2]. 1-x F x FeAs (x=0.05-0.12) with T c =26 KJ [Am. Chem. Sco. 130, 3296-3297 (2008)], its superconducting transition temperature reaches 26 K, attracting widespread attention in the field of superconductivity research. Based on different parent structures, iron-based superconductors are mainly divided into four categories: 1111 system, 122 system, 11 system, and 111 system. In the 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 low dependence of critical current on strong magnetic field. It has broad application prospects in medium and low temperature and strong magnetic field, and is expected to be widely used in medical, energy, transportation and defense fields.

[0003] Ae 1-x K x The raw materials in Fe2As2 superconductors are relatively reactive and readily react with air and water. Therefore, the preparation of iron-based superconductors requires an argon atmosphere. However, potassium (K) is highly reactive. Therefore, patent ZL202110934020.6 provides a method for preparing As2 using potassium fluoride as a raw material. 1-x K x The method for preparing Fe2As2 superconductors improves the safety and practicality of the preparation process, facilitating mass production. However, in the iron-based superconductors prepared using this method, impurities such as FeAs and BaF2 are present in the final product, affecting phase purity. Summary of the Invention

[0004] The purpose of this 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 includes the following steps:

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

[0008] Step 2: After sintering, the block is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing solvent.

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

[0010] Step 4: After ball milling, remove the upper solvent and dry the remaining powder on a heating platform to obtain a superconductor after impurity removal.

[0011] In the above technical solution, the potassium fluoride-doped iron-based superconductor is a potassium fluoride-doped Ale superconductor. 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, diethyl ether, acetone or n-hexane.

[0013] In the above technical solution, in step 3, the ball mill rotation 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 existing preparation methods, the present invention has the following advantages:

[0018] (1) Preparation of Al using potassium fluoride 1-x K x In Fe2As2 superconductors, the preferential chemical reaction between fluorine (F) and eutectic ion (Ae) leads to the absence of Ae in the final effective product, resulting in the formation of FeAs. This invention increases the Ae content, compensating for the Ae deficiency in the final effective product and thus suppressing the formation of the FeAs impurity phase.

[0019] (2) Preparation of Al using potassium fluoride 1-x K x Fe2As2 superconductors inevitably generate AeF2 impurities. The organic solvent ball milling process proposed in this invention can reduce the AeF2 impurity content without affecting the product quality. Attached Figure Description

[0020] Figure 1 The image shows the X-ray diffraction (XRD) pattern of a superconductor after ball milling with Ba content increased to 0.8% and ethanol as solvent.

[0021] Figure 2 Ba is prepared using potassium fluoride. 0.6 K 0.4 XRD pattern of Fe2As2 superconductor. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the 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 using Fe2As2 superconductors, the Ba element content is increased to 0.8%.

[0025] After sintering, the superconducting bulk material is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing 95% pure ethanol.

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

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

[0028] The product in Example 1 was identified by XRD using a Bruker D8 X-ray diffractometer. The test range was 10° ≤ 2θ ≤ 80°. The XRD results are as follows: Figure 1 As shown. By Figure 1 and Figure 2 Compared with products prepared using methods not described in this embodiment, it can be concluded that no diffraction peaks of the FeAs impurity phase were found in the superconductor prepared in Example 1, and the diffraction peak intensity of the BaF2 impurity was significantly reduced. This indicates that the phase purity of the product prepared in this example was improved.

[0029] Example 2

[0030] In the preparation of potassium fluoride-doped Ba 0.6 K0.4 When using Fe2As2 superconductors, the Ba element content is increased to 0.8%.

[0031] After sintering, the superconducting bulk material is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing 99% pure n-hexane.

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

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

[0034] The results for the product in Example 2 were the same as those for the product in Example 1.

[0035] Example 3

[0036] In the preparation of potassium fluoride-doped Ba 0.6 K 0.4 When using Fe2As2 superconductors, the Ba element content is increased to 0.85.

[0037] After sintering, the superconducting bulk material is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing 95% pure ethanol.

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

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

[0040] The results for the product in Example 3 were the same as those for the product in Example 1.

[0041] Example 4

[0042] In the preparation of potassium fluoride-doped Sr 0.6 K 0.4 When using Fe2As2 superconductors, the Sr element content is increased to 0.8.

[0043] After sintering, the superconducting bulk material is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing 95% pure ethanol.

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

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

[0046] The results for the product in Example 4 were the same as those for the product in Example 1.

[0047] Example 5

[0048] In the preparation of potassium fluoride-doped Ba 0.6 K 0.4 When using Fe2As2 superconductors, the Ba element content is increased to 0.8%.

[0049] After sintering, the superconducting bulk material is crushed in a glove box under Ar atmosphere protection, and the crushed powder is loaded into a ball mill jar containing 95% pure ethanol.

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

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

[0052] The results for the product in Example 5 were the same as those for the product in Example 1.

[0053] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for reducing impurities in potassium fluoride-doped iron-based superconductors, characterized in that, Includes the following steps: Step 1: Increase the molar ratio of Al in the raw materials to (1-x)-(1-x / 10). Step 2: After sintering, the block is crushed in a glove box under Ar atmosphere protection. The crushed powder is then loaded into a ball mill jar containing a solvent, such as methanol, ethanol, diethyl ether, acetone, or n-hexane. Step 3: Load the ball mill jar into the ball mill for ball milling; Step 4: After ball milling, remove the upper solvent and dry the remaining powder on a heating platform to obtain a superconductor after impurity removal.

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 a potassium fluoride-doped Ale superconductor. 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 3, the ball mill rotation speed is 100-500 r / min.

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 time is 0.5-10 h.

5. 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.

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 time is 10-300 min.

Images