A method for regulating Fe y Se x Te 1-x Polycrystalline J c Methods and Fe y Se x Te 1-x polycrystalline

Abstract

The application discloses a method for regulating polycrystal J c and polycrystal, and the method comprises the following steps: (1) selecting a first polycrystal, wherein the J c value of the first polycrystal is known; (2) adjusting the value according to the requirement of a predetermined target, so as to obtain the y value, and x=; wherein the predetermined target comprises high-field J c or low-field J c . The method for regulating polycrystal J c of the application can regulate the content of the second phase and the interstitial iron in the polycrystal by adjusting the content of Fe in the raw material, so as to regulate J c .

Description

Technical Field

[0001] This invention relates to the field of superconducting material preparation technology, and particularly to a method for regulating... Polycrystalline J c Methods and Polycrystalline. Background Technology

[0002] In 2008, Japanese scientist Hideo Hosono's research group discovered LaFeAsO₂. 1-x F x It has a critical transition temperature of 26 K (T c This sparked a research boom in iron-based superconductors (IBS). IBS possesses high TT... c High upper critical field (H c2 Its characteristics, such as low anisotropy (γ), give it unique advantages in high-field applications such as nuclear magnetic resonance imaging (MRI), nuclear magnetic resonance spectrometer (NMR), superconducting energy storage system (SMES), and high-energy physics accelerators.

[0003] Currently, four systems of iron-based superconductors are widely studied: 1111-series REFeAsO, 111-series LiFeAs, 122-series AEFe2As2, and 11-series FeSe. Among them, the 11-series iron-based superconductors (usually referring to FeSe and FeSeTe) are unique in that they not only have a simple structure but also do not contain toxic elements (As) or unstable elements (K, Li), making them more suitable for large-scale applications. Although the transition temperature of FeSe is only 8 K, simple Te doping to become Fe(Se,Te) can exceed 14 K, and the measured critical field of Fe(Se,Te) can reach 50 T. Furthermore, both Fe(Se,Te) single crystals and thin films exhibit excellent superconducting properties at high fields (critical current density J). c More than 10 5 A / cm 2 The above demonstrates that Fe(Se, Te) has enormous application potential in terms of both material properties and superconducting performance. If high-performance wires and strips can be successfully fabricated, they will become candidates for applications in low-temperature, high-field environments.

[0004] The preparation of high-performance Fe(Se, Te) polycrystalline bulk materials is a necessary condition for the successful preparation of Fe(Se, Te) wires and strips. On one hand, practical wires and strips are themselves polycrystalline. On the other hand, similar to 122-series wires and strips, the powder obtained from polycrystalline crushing is a precursor for the pre-positioned powder-packing method in wire and strip preparation. Critical current density J c It is an important indicator for evaluating the performance of practical superconducting materials, and it is related to T c and H c2The difference is not an intrinsic parameter of the material, but is closely related to its microstructure. Therefore, for Fe(Se, Te) polycrystalline bulk materials, J... c Conduct research to master the J of polycrystalline bulk materials c The proposed control method will lay the foundation for the preparation of high-performance Fe(Se, Te) wires and strips and their application in the field of low temperature and high magnetic field.

[0005] Currently prepared Fe(Se, Te) polycrystalline J c It is highly dependent on the magnetic field; as the magnetic field increases, J c Continuously decreasing. And if J needs to be prepared... c For Fe(Se, Te) polycrystalline materials with weak magnetic field dependence, it is necessary to first prepare pure-phase Fe(Se, Te) polycrystalline materials and then anneal them fully in an oxygen-containing environment, which is a relatively complex process.

[0006] Therefore, a regulatory mechanism is needed. Polycrystalline J c The method. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a regulation Polycrystalline J c This method involves adjusting the Fe content to influence the balance between the second phase and interstitial iron, thereby controlling J. c To obtain different J c Features Polycrystalline.

[0008] A further technical problem to be solved by the present invention is to provide a Polycrystalline.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A regulation Polycrystalline J c The method includes the following steps:

[0011] (1) Select the first polycrystalline Among them, the first polycrystalline J c The value is known;

[0012] (2) Adjust according to the requirements of the predetermined target The value of y can be obtained by taking the value, and x = ;

[0013] The predetermined target includes J under high field. c or low field J c .

[0014] Specifically, step (1) is as follows:

[0015] When the predetermined target is J under high field c At that time, J under the high field of the first polycrystalline material c The value of J is less than the predetermined target. c value;

[0016] When the predetermined target is J under low field c At that time, J under the low field of the first polycrystalline material c The value of J is less than the predetermined target. c value.

[0017] Among them, (2) is adjusted according to the requirements of the predetermined target. The value of y can be obtained by taking the value of y.

[0018] When the predetermined target is J under high field c And the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When y < ;

[0019] When the predetermined target is J under low field c And the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When y > 0, .

[0020] Among them, when the predetermined target is J under high field c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is 0 < <0.04, where .

[0021] Furthermore,

[0022] Among them, when the predetermined target is J in a low field c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is 0 < <0.02, where .

[0023] Furthermore,

[0024] The control method further includes the following steps:

[0025] (3) Weigh appropriate amounts of Fe powder, Se powder and Te powder according to the x and y values ​​designed in step (2);

[0026] (4) Under the protection of an inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are thoroughly mixed and loaded into a reaction vessel;

[0027] (5) The reaction vessel is melt-sintered and cooled to obtain the desired product. Polycrystalline.

[0028] The present invention also provides a preparation method described above that yields a product. Polycrystalline.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) Regulation of the present invention Polycrystalline J c The method adjusts the Fe content in the raw material ratio, thereby regulating the content of the second phase and interstitial iron in the polycrystalline material, thus achieving the control of J. c The purpose.

[0031] (2) The present invention can prepare different J according to the target requirements. c The polycrystalline structure reduces the amount of experimentation and saves costs.

[0032] (3) The control method of the present invention can be combined with other process optimization methods. Since the present invention starts with the initial Fe ratio, it will not affect the optimization of subsequent processes such as powder mixing, packaging, and melting. Therefore, when other processes have better operating methods, they can still be combined with the present invention. In other words, the present invention can be applied to any process involving... This invention can also be used in the preparation of polycrystalline bulk materials, and even in the preparation of wire and strip materials, to treat J. c To implement regulation. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] This invention provides a regulation Polycrystalline J c The method includes the following steps:

[0035] (1) Select the first polycrystalline Among them, the first polycrystalline J c The value is known; the J value of the first polycrystalline material can be obtained under high field conditions by consulting existing technologies such as literature. c J value, low field c value, Value and When searching for literature, try to select a value that matches your intended target. c The first polycrystalline material with a value close to that of the first polycrystalline material; of course, by preparing a basic first polycrystalline material, its J value under a high field can be obtained. c J value, low field c value.

[0036] (2) Adjust according to the requirements of the predetermined target The value of y can be obtained by taking the value, and x = .

[0037] The predetermined target includes J under high field. c or low field J c .

[0038] Preferably, step (1) specifically involves: when the predetermined target is J under a high field... c At that time, J under the high field of the first polycrystalline material c The value of J is less than the predetermined target. c Value; when the predetermined target is J in a low field c At that time, J under the low field of the first polycrystalline material c The value of J is less than the predetermined target. c Value. That is, the J value of the corresponding high or low field of the first polycrystalline material we choose. c The values ​​are all lower than the predetermined target J. c value.

[0039] Preferably, step (2) is adjusted according to the requirements of the predetermined target. The value of y can be obtained by taking the value of y.

[0040] When the predetermined target is J under high field c And the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When y < That is, to reduce the Fe content of the first polycrystalline material;

[0041] When the predetermined target is J under low field c And the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is y> That is, increase the Fe content of the first polycrystalline material.

[0042] Our research has identified two factors affecting the Jo of the Fe(Se,Te) polycrystalline system. c The most significant impacts are on two phases: the non-superconducting second phase in polycrystalline materials and the interstitial iron in the superconducting phase of polycrystalline materials. Both have an effect on J... cThe effects are significantly different. When the interstitial iron content in the superconducting phase is high, that is, when the polycrystalline phase purity is high, the J of the polycrystalline phase under low field is significantly different. c The content of the second phase in the polycrystalline material is relatively high. However, when the content of the second phase in the polycrystalline material is relatively high, although the J of the polycrystalline material under a low field is relatively high... c The ΔT of polycrystalline materials under high field is relatively low, but due to the reduced interstitial iron content, the ΔT is lower. c The pinning becomes stronger, therefore polycrystalline J c The magnetic field dependence is relatively weak, and a significant second peak effect may even appear.

[0043] In the preparation of Fe(Se, Te) polycrystalline materials, interstitial iron and the second phase exhibit a competitive relationship, determined by the Fe content. Higher Fe content results in higher phase purity in the Fe(Se, Te) polycrystalline material, but also increases the interstitial iron content in the superconducting phase. Conversely, lower Fe content reduces the interstitial iron content in the superconducting phase of the Fe(Se, Te) polycrystalline material, but increases the amount of the non-superconducting second phase within the polycrystalline material.

[0044] Based on the above analysis, it can be concluded that the Fe content is related to the J of Fe(Se, Te) polycrystalline materials. c They are closely related; by adjusting the Fe content, the ebb and flow between the second phase and interstitial iron can be controlled, thus regulating J. c To obtain different J c The Fe(Se,Te) polycrystalline material exhibits unique characteristics. Therefore, to achieve higher performance at high fields, the interstitial iron content in the superconducting phase can be reduced by decreasing the Fe content in the raw materials, thereby enhancing the pinning ability of the polycrystalline material and improving J at high fields. c To achieve higher performance at low fields in polycrystalline materials, the Fe content in the raw materials can be increased to reduce the content of the second phase, thereby improving the purity of the polycrystalline material and enhancing J at low fields. c .

[0045] Even better, when the predetermined target is J in a high field c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is 0 < <0.04, where Among them, the preferred option is...

[0046] Among them, when the predetermined target is J in a low field c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is 0 < <0.02, where Better,

[0047] Preferably, the control method further includes the following steps:

[0048] (3) Weigh appropriate amounts of Fe powder, Se powder and Te powder according to the x and y values ​​designed in step (2);

[0049] (4) Under the protection of an inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are thoroughly mixed and loaded into a reaction vessel;

[0050] (5) The reaction vessel is melt-sintered and cooled to obtain the desired product. Polycrystalline.

[0051] Even better, 0.96 < <1.02.

[0052] Example 1

[0053] The predetermined goal is to obtain J under low field conditions. c Greater than 80,000 Polycrystalline.

[0054] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 The J of the first polycrystalline material under low field was measured. c The value is 76000. =1 and =0.5. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1:0.5:0.5 (FeSe... 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it at 880℃ for 3 days in a box-type muffle furnace. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain FeSe. 0.5 Te 0.5 Polycrystalline.

[0055] (2) J under the predetermined target low field c The value is greater than J under low field of the first polycrystalline material. c If the value increases, then increase. The value of y can be obtained by taking the value. In this embodiment, y = 1.005.

[0056] (3) Preparation of Fe 1.005 Se 0.5 Te 0.5Polycrystalline. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1.005:0.5:0.5 (Fe... 1.005 Se 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 1.005 Se 0.5 Te 0.5 Polycrystalline.

[0057] Example 2

[0058] The predetermined goal is to obtain J under low field conditions. c Greater than 80,000 Polycrystalline.

[0059] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 The J of the first polycrystalline material under low field was measured. c The value is 76000. =1 and =0.5. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1:0.5:0.5 (FeSe... 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it at 880℃ for 3 days in a box-type muffle furnace. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain FeSe. 0.5 Te 0.5 Polycrystalline.

[0060] (2) J under the predetermined target low field c The value is greater than J under low field of the first polycrystalline material. c If the value increases, then increase. The value of y can be obtained by taking the value. In this embodiment, y = 1.01.

[0061] (3) Preparation of Fe 1.01 Se 0.5 Te 0.5Polycrystalline. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1.01:0.5:0.5 (Fe... 1.01 Se 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 1.01 Se 0.5 Te 0.5 Polycrystalline.

[0062] Example 3

[0063] The predetermined goal is to obtain J under low field conditions. c Greater than 80,000 Polycrystalline.

[0064] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 The J of the first polycrystalline material under low field was measured. c The value is 76000. =1 and =0.5. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1:0.5:0.5 (FeSe... 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it at 880℃ for 3 days in a box-type muffle furnace. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain FeSe. 0.5 Te 0.5 Polycrystalline.

[0065] (2) J under the predetermined target low field c The value is greater than J under low field of the first polycrystalline material. c If the value increases, then increase. The value of y can be obtained by taking the value. In this embodiment, y = 1.015.

[0066] (3) Preparation of Fe 1.015 Se 0.5 Te 0.5Polycrystalline. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1.015:0.5:0.5 (Fe... 1.015 Se 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 1.015 Se 0.5 Te 0.5 Polycrystalline.

[0067] Comparative Example 1

[0068] In this embodiment, y = 1.02 is designed.

[0069] Fe was prepared using the same method 1.02 Se 0.5 Te 0.5 Polycrystalline.

[0070] First polycrystalline, Example 1, Example 2, Example 3, Comparative Example 1 J c The test results are shown in Table 1:

[0071] Table 1

[0072]

[0073] As can be seen from Table 1, when the predetermined target is J under low field conditions c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is y, increase the Fe content (y > y). This can reduce the content of the second phase in polycrystalline materials, increase the purity of polycrystalline materials, and improve J at low fields. c However, there are certain limitations to the increase. The inventors discovered through experiments that the increase cannot be too large; ideally, the increase should be less than 0. <0.02.

[0074] Example 4

[0075] The predetermined goal is to obtain J under high field conditions. c Greater than 10000 Polycrystalline.

[0076] (1) The first polycrystalline material of Example 1 is also used as the base polycrystalline material. J under high field of the first polycrystalline material c The value is 10000.

[0077] (2) J under the predetermined target high field c The value is greater than J under high field in the first polycrystalline material. c If the value decreases, then the value decreases. The value of y can be obtained by taking the value. In this embodiment, y = 0.99.

[0078] (3) Preparation of Fe 0.99 Se 0.5 Te 0.5 Polycrystalline. In an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) were mixed in an atmosphere of Fe:Se:Te = 0.99:0.5:0.5 (Fe... 0.99 Se 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 0.99 Se 0.5 Te 0.5 Polycrystalline.

[0079] Example 5

[0080] Similarly, the first polycrystalline material of Example 1 is used as the base polycrystalline material; in this example, y=0.97 is designed.

[0081] (3) Preparation of Fe 0.97 Se 0.5 Te 0.5 Polycrystalline. In an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) were mixed in an atmosphere where Fe:Se:Te = 0.97:0.5:0.5 (Fe... 0.97 Se 0.5 Te 0.5 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 0.97 Se 0.5 Te 0.5 Polycrystalline.

[0082] Comparative Example 2

[0083] Similarly, the first polycrystalline material of Example 1 is used as the base polycrystalline material; in this example, y=0.96 is designed.

[0084] Fe was prepared using the same method 0.96 Se 0.5 Te 0.5 Polycrystalline.

[0085] First polycrystalline, Example 4, Example 5 and Comparative Example 2 J c The test results are shown in Table 2:

[0086] Table 2

[0087]

[0088] As can be seen from Table 2, when the predetermined target is J under high field c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is low, reduce the Fe content in the raw material (i.e., y < y). This reduces the interstitial iron content in the superconducting phase, enhances the pinning ability of polycrystalline materials, and improves J at high fields. c Similarly, the reduction in Fe content is also limited; the inventors discovered that the reduction... The range is 0 < <0.04, preferred

[0089] Example 6

[0090] The predetermined goal is to obtain J under low field conditions. c Greater than 70,000 Polycrystalline.

[0091] (1) Preparation of the first polycrystalline Fe1Se 0.4 Te 0.6 The J of the first polycrystalline material under low field was measured. c The value is 66000. =1 and =0.4. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1:0.4:0.6 (FeSe... 0.4 Te 0.6 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it at 880℃ for 3 days in a box-type muffle furnace. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain FeSe. 0.4 Te 0.6 Polycrystalline.

[0092] (2) J under the predetermined target low field c The value is greater than J under low field of the first polycrystalline material.c If the value increases, then increase. The value of y can be obtained by taking the value. In this embodiment, y = 1.01.

[0093] (3) Preparation of Fe 1.01 Se 0.4 Te 0.6 Polycrystalline. Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) are mixed in a ratio of Fe:Se:Te = 1.01:0.4:0.6 (Fe... 1.01 Se 0.4 Te 0.6 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 1.01 Se 0.4 Te 0.6 Polycrystalline.

[0094] Comparative Example 3

[0095] In this embodiment, y = 1.02 is designed.

[0096] Fe was prepared using the same method 1.02 Se 0.4 Te 0.6 Polycrystalline.

[0097] First polycrystalline, Example 6, Comparative Example 3 J c The results of the value detection are shown in Table 3:

[0098] Table 3

[0099]

[0100] Similarly, as can be seen from Table 3, when the predetermined target is J under low field conditions... c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is y, increase the Fe content (y > y). This can reduce the content of the second phase in polycrystalline materials, increase the purity of polycrystalline materials, and improve J at low fields. c .

[0101] Example 7

[0102] The predetermined goal is to obtain J under high field conditions. c Greater than 9000 Polycrystalline.

[0103] (1) Preparation of the first polycrystalline Fe1Se 0.4 Te 0.6 J under high field in the first polycrystalline material c The value is 8600.

[0104] (2) J under the predetermined target high field c The value is greater than J under high field in the first polycrystalline material. c If the value decreases, then the value decreases. The value of y can be obtained by taking the value. In this embodiment, y = 0.99.

[0105] (3) Preparation of Fe 0.99 Se 0.4 Te 0.6 Polycrystalline. In an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) were mixed in an atmosphere of Fe:Se:Te = 0.99:0.4:0.6 (Fe... 0.99 Se 0.4 Te 0.6 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 0.99 Se 0.4 Te 0.6 Polycrystalline.

[0106] Example 8

[0107] Similarly, the first polycrystalline material of Example 7 is used as the base polycrystalline material; in this example, y=0.97 is designed.

[0108] (3) Preparation of Fe 0.97 Se 0.4 Te 0.6 Polycrystalline. In an argon glove box, Fe powder (99.9%), Se powder (99.99%), and Te powder (99.99%) were mixed in an atmosphere of Fe:Se:Te = 0.97:0.4:0.6 (Fe... 0.97 Se 0.4 Te 0.6 Weigh 10 g of the mixture and mix it in a mortar. Then, place the mixture into a cylindrical alumina crucible with an inner diameter of 1 cm, an outer diameter of 1.2 cm, and a height of 5 cm, and cover it. Seal the crucible in a vacuum quartz tube and sinter it in a box-type muffle furnace at 880℃ for 3 days. Then, disconnect the power and allow the muffle furnace to cool naturally to room temperature to obtain Fe. 0.97 Se 0.4 Te 0.6 Polycrystalline.

[0109] Comparative Example 4

[0110] Similarly, the first polycrystalline material of Example 7 is used as the base polycrystalline material; in this example, y=0.96 is designed.

[0111] Fe was prepared using the same method 0.96 Se 0.4 Te 0.6 Polycrystalline.

[0112] First polycrystalline, Example 7, Example 8 and Comparative Example 4 J c The test results are shown in Table 4:

[0113] Table 4

[0114]

[0115] Similarly, as can be seen from Table 4, when the predetermined target is J under high field... c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is low, reduce the Fe content in the raw material (i.e., y < y). This reduces the interstitial iron content in the superconducting phase, enhances the pinning ability of polycrystalline materials, and improves J at high fields. c .

[0116] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0117] The parts of this invention not described in detail are well-known in the art. The above embodiments are provided merely for the purpose of describing the invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A type of regulation Polycrystalline J c The method is characterized by, Includes the following steps: (1) Select the first polycrystalline Among them, the first polycrystalline J c The value is known; (2) Adjust according to the requirements of the predetermined target The value of y can be obtained from the value of x, and x = ; The predetermined target includes J under high field. c or low field J c ; Step (1) specifically involves: When the predetermined target is J under high field c At that time, J under the high field of the first polycrystalline material c The value of J is less than the predetermined target. c value; When the predetermined target is J under low field c At that time, J under the low field of the first polycrystalline material c The value of J is less than the predetermined target. c value; The aforementioned (2) refers to adjusting according to the requirements of the predetermined target. The value of y can be obtained by taking the value of y. When the predetermined target is J under high field c And the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When y < ; When the predetermined target is J under low field c And the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When y > 0, ; Where the predetermined target is J under high field c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is 0 < <0.04, where ; When the predetermined target is J under low field c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is 0 < <0.02, where .

2. The regulation according to claim 1 Polycrystalline J c The method is characterized by, When the predetermined target is J under high field c Value, and the predetermined target J c The value is greater than J under high field in the first polycrystalline material. c When the value is, .

3. The regulation according to claim 1 Polycrystalline J c The method is characterized by, When the predetermined target is J under low field c Value, and the predetermined target J c The value is greater than J under low field of the first polycrystalline material. c When the value is, .

4. The regulation according to any one of claims 1 to 3 Polycrystalline J c The method is characterized by, The control methods also include the following steps: (3) Weigh appropriate amounts of Fe powder, Se powder and Te powder according to the x and y values ​​designed in step (2); (4) Under the protection of an inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are thoroughly mixed and loaded into a reaction vessel; (5) The reaction vessel is melt-sintered and cooled to obtain the desired product. Polycrystalline.

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