Method for regulating Jc of FeySexTe1-x polycrystal and FeySexTe1-x polycrystal

Abstract

The invention discloses a method for regulating and controlling Jc of # imgabs0 # polycrystal and # imgabs1 # polycrystal, the regulating and controlling method comprises the following steps: (1) selecting a first polycrystal # imgabs2 #, the Jc value of the first polycrystal and the Jc value of # imgabs3 # are known; (2) adjusting a # imgabs4 # value according to the requirement of a predetermined target to obtain a y value, wherein x is equal to # imgabs5 #; wherein the predetermined target comprises Jc in a high field or Jc in a low field. According to the method for regulating and controlling # imgabs6 polycrystal Jc, the content of a second phase and interstitial iron in the polycrystal is regulated by regulating the Fe content in the raw material ratio, so that the purpose of regulating and controlling Jc is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting material preparation, and in particular to a method for regulating Polycrystalline J c Methods and Polycrystalline. Background Art

[0002] In 2008, Japanese scientist Hideo Hosono's research group discovered LaFeAsO 1-x F x The critical transition temperature (T) is 26 K. c ), which kicked off a wave of research on iron-based superconductors (IBS). IBS has high T c , high upper critical field (H c2 ) and low anisotropy (γ), it has unique advantages in high-field applications such as magnetic resonance imaging systems (MRI), nuclear magnetic resonance spectrometers (NMR), superconducting energy storage systems (SMES) and high-energy physics accelerators.

[0003] There are four systems of iron-based superconductors that are widely studied, namely: 1111 series REFeAsO, 111 series LiFeAs, 122 series AEFe2As2 and 11 series FeSe. Among them, the uniqueness of the 11 series iron-based superconductors (usually referring to FeSe and FeSeTe) is that they are not only simple in structure, but also do not contain toxic elements (As) and 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 Fe(Se, Te) can exceed 14 K, and the measured upper critical field of Fe(Se,Te) can reach 50 T. In addition, Fe(Se, Te) single crystals and thin films exhibit excellent superconducting properties under high fields (critical current density J c More than 10 5 A / cm 2 ). The above shows that Fe(Se, Te) has great application potential in terms of both material properties and superconducting performance. If high-performance wire and strip can be successfully prepared, it will become a candidate for application in low-temperature and high-field environments.

[0004] The preparation of Fe(Se, Te) polycrystalline bulk with excellent performance is a necessary condition for the successful preparation of Fe(Se, Te) wire and strip. On the one hand, the practical wire and strip itself is also polycrystalline. On the other hand, like the 122 series wire and strip, the powder obtained by crushing the polycrystalline is the precursor for preparing the wire and strip by the pre-powder tube method. Critical current density J c It is an important indicator to measure the performance of practical superconducting materials, and it is closely related to T c and H c2The difference is not the intrinsic parameter of the material, but is closely related to the microstructure. c Conduct research to master polycrystalline bulk materials c The regulation 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] The Fe(Se, Te) polycrystal J prepared so far c The magnetic field dependence is strong. As the magnetic field increases, J c Continue to decrease. If you need to prepare J c For Fe(Se, Te) polycrystals with weaker magnetic field dependence, it is necessary to first prepare pure phase Fe(Se, Te) polycrystals and anneal them in an oxygen-containing environment for sufficient annealing, and the process is relatively complicated.

[0006] Therefore, a regulation is needed Polycrystalline J c method. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a control Polycrystalline J c This method can adjust the J by adjusting the Fe content to affect the increase and decrease of the second phase and interstitial iron. c , get different J c Features Polycrystalline.

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

[0009] In order to achieve the above object, the present invention adopts the following technical scheme:

[0010] A kind of regulation Polycrystalline J c A method comprising the steps of:

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

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

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

[0014] Among them, step (1) is specifically as follows:

[0015] When the target is J under high field c When the first polycrystalline high field J c J whose value is less than the predetermined target c value;

[0016] When the target is J in the low field c When the first polycrystalline is subjected to low field, J c J whose value is less than the predetermined target c value.

[0017] Wherein, (2) is adjusted according to the requirements of the predetermined target The y value can be obtained by:

[0018] When the target is J under high field c , and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When y< ;

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

[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 the J of the first polycrystalline under high field c When the value is 0< <0.04, where .

[0021] Furthermore,

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

[0023] Furthermore,

[0024] Wherein, the control method further comprises 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 inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are fully mixed and loaded into a reaction container;

[0027] (5) The reaction vessel is melted, sintered and cooled to obtain Polycrystalline.

[0028] The present invention also provides a kind of preparation method obtained by the above-mentioned Polycrystalline.

[0029] The beneficial effects of the present 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 and then adjusts the content of the second phase and interstitial iron in the polycrystal, thereby achieving the goal of regulating J c purpose.

[0031] (2) The present invention can prepare different J according to target requirements. c The unique multi-crystal structure reduces the amount of experiments 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 process, packaging process, and melting process. 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 The present invention can also be used in the preparation of polycrystalline blocks and even wire strips. c To regulate. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] The present invention provides a control Polycrystalline J c The method comprises the following steps:

[0035] (1) Select the first polycrystalline , among which the first polycrystalline J c The value is known; the J value of the first polycrystal under high field can be obtained by consulting the existing technology such as literature c Value, J under low field c value, Value and If you are searching for literature, try to select J that matches the target. c The first polycrystal with a close value can of course be prepared by preparing a basic first polycrystal to obtain its J under high field c Value, J under low field c value.

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

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

[0038] Preferably, step (1) is specifically as follows: when the predetermined target is J under high field c When the first polycrystalline high field J c J whose value is less than the predetermined target c value; when the target is J under low field c When the first polycrystalline is subjected to low field, J c J whose value is less than the predetermined target c That is to say, the corresponding high field or low field J of the first polycrystal we choose c The values ​​must be lower than the predetermined target J c value.

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

[0040] When the target is J under high field c , and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When y< ; That is, reducing the Fe content of the first polycrystal;

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

[0042] According to our research, there are two factors that affect the Fe(Se, Te) polycrystalline system J c The most significant influence is the non-superconducting second phase in the polycrystal and the interstitial iron in the superconducting phase of the polycrystal. cThere is a clear difference in the effect of the interstitial iron content in the superconducting phase. When the interstitial iron content in the superconducting phase is high, that is, when the phase purity of the polycrystal is high, the J of the polycrystal under low field is c When the second phase content in the polycrystal is high, although the J c However, due to the reduction of interstitial iron content, the ΔT of polycrystalline under high field is c Pinning becomes stronger, so polycrystalline J c The magnetic field dependence is weak, and even an obvious second peak effect will appear.

[0043] In the process of preparing Fe(Se, Te) polycrystals, interstitial iron and the second phase are in a competitive relationship, which is determined by the Fe content. When the Fe content is high, the phase purity of Fe(Se, Te) polycrystals is high, but the interstitial iron content in the superconducting phase will also increase. When the Fe content is low, the interstitial iron content in the superconducting phase of Fe(Se, Te) polycrystals decreases, but the non-superconducting second phase in the polycrystal increases.

[0044] Based on the above analysis, it can be concluded that the Fe content is related to the J of Fe(Se, Te) polycrystals. c There is a close relationship between the second phase and interstitial iron, and J can be regulated by adjusting the Fe content to affect the increase and decrease of the second phase and interstitial iron. c , get different J c Therefore, if you need a polycrystal with higher performance under high field, you can reduce the interstitial iron content in the superconducting phase by reducing the Fe content in the raw material, enhance the pinning ability of the polycrystal, and improve the J under high field. c If you need polycrystals with higher performance under low field, you can increase the Fe content in the raw material to reduce the content of the second phase in the polycrystal, improve the purity of the polycrystal, and improve the J under low field. c .

[0045] Better, when the target is J under high field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When the value is 0< <0.04, where Among them, it is preferred

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

[0047] Preferably, the control method further comprises 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 inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are fully mixed and loaded into a reaction container;

[0050] (5) The reaction vessel is melted, sintered and cooled to obtain Polycrystalline.

[0051] Better, 0.96< <1.02.

[0052] Example 1

[0053] The intended goal is to get a low field J c More than 80000 Polycrystalline.

[0054] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 , the J of the first polycrystal 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%) were mixed at a ratio of Fe:Se:Te=1:0.5:0.5 (FeSe 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to allow the muffle furnace to cool naturally to room temperature to obtain FeSe 0.5 Te 0.5 Polycrystalline.

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

[0056] (3) Preparation of Fe 1.005 Se 0.5 Te 0.5Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=1.005:0.5:0.5 (Fe 1.005 Se 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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 intended goal is to get a low field J c More than 80000 Polycrystalline.

[0059] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 , the J of the first polycrystal 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%) were mixed at a ratio of Fe:Se:Te=1:0.5:0.5 (FeSe 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to allow the muffle furnace to cool naturally to room temperature to obtain FeSe 0.5 Te 0.5 Polycrystalline.

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

[0061] (3) Preparation of Fe 1.01 Se 0.5 Te 0.5Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=1.01:0.5:0.5 (Fe 1.01 Se 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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 intended goal is to get a low field J c More than 80000 Polycrystalline.

[0064] (1) Preparation of the first polycrystalline Fe1Se 0.5 Te 0.5 , the J of the first polycrystal 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%) were mixed at a ratio of Fe:Se:Te=1:0.5:0.5 (FeSe 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to allow the muffle furnace to cool naturally to room temperature to obtain FeSe 0.5 Te 0.5 Polycrystalline.

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

[0066] (3) Preparation of Fe 1.015 Se 0.5 Te 0.5Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=1.015:0.5:0.5 (Fe 1.015 Se 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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 is designed to be 1.02.

[0069] The same method was used to prepare Fe 1.02 Se 0.5 Te 0.5 Polycrystalline.

[0070] J of the first polycrystalline, Example 1, Example 2, Example 3, and Comparative Example 1 c The value detection results are shown in Table 1:

[0071] Table 1

[0072]

[0073] It can be seen from Table 1 that when the predetermined target is J under low field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under low field c When the Fe content is increased (y > ) can reduce the content of the second phase in the polycrystal, improve the purity of the polycrystal, and increase the J under low field c However, the increase is also limited. The inventors found through experiments that the increase should not be too large. After experiments, it was found that the increase is preferably 0 < <0.02.

[0074] Example 4

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

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

[0077] (2) J at the target high field c The value is greater than the J of the first polycrystalline under high field c value, then reduce The y value can be obtained by setting the value. In this embodiment, y=0.99 is designed.

[0078] (3) Preparation of Fe 0.99 Se 0.5 Te 0.5 In an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=0.99:0.5:0.5 (Fe 0.99 Se 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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] The first polycrystal in Example 1 is also used as the basic polycrystal; in this example, y=0.97 is designed.

[0081] (3) Preparation of Fe 0.97 Se 0.5 Te 0.5 In an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=0.97:0.5:0.5 (Fe 0.97 Se 0.5 Te 0.5 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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] The first polycrystal in Example 1 is also used as the basic polycrystal; in this example, y=0.96 is designed.

[0084] The same method was used to prepare Fe 0.96 Se 0.5 Te 0.5 Polycrystalline.

[0085] J of the first polycrystalline, Example 4, Example 5 and Comparative Example 2 c The value detection results are shown in Table 2:

[0086] Table 2

[0087]

[0088] It can be seen from Table 2 that when the predetermined target is J under high field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When the Fe content in the raw material is reduced (i.e. y< ) to reduce the interstitial iron content in the superconducting phase, enhance the pinning ability of the polycrystalline, and improve the J under high field c Similarly, the reduction in Fe content is also limited. The inventors found that the reduction The range is 0< <0.04, preferred

[0089] Example 6

[0090] The intended goal is to get a low field J c More than 70000 Polycrystalline.

[0091] (1) Preparation of the first polycrystalline Fe1Se 0.4 Te 0.6 , the J of the first polycrystal 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%) were mixed at the ratio of Fe:Se:Te=1:0.4:0.6 (FeSe 0.4 Te 0.6 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to allow the muffle furnace to cool naturally to room temperature to obtain FeSe 0.4 Te 0.6 Polycrystalline.

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

[0093] (3) Preparation of Fe 1.01 Se 0.4 Te 0.6 Specifically, in an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=1.01:0.4:0.6 (Fe 1.01 Se 0.4 Te 0.6 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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 is designed to be 1.02.

[0096] The same method was used to prepare Fe 1.02 Se 0.4 Te 0.6 Polycrystalline.

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

[0098] Table 3

[0099]

[0100] Similarly, it can be seen from Table 3 that when the target is J under low field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under low field c When the Fe content is increased (y > ) can reduce the content of the second phase in the polycrystal, improve the purity of the polycrystal, and increase the J under low field c .

[0101] Example 7

[0102] The intended goal is to obtain high field J c More than 9000 Polycrystalline.

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

[0104] (2) J at the target high field c The value is greater than the J of the first polycrystalline under high field c value, then reduce The y value can be obtained by setting the value. In this embodiment, y=0.99 is designed.

[0105] (3) Preparation of Fe 0.99 Se 0.4 Te 0.6 In an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=0.99:0.4:0.6 (Fe 0.99 Se 0.4 Te 0.6 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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] The first polycrystal in Example 7 is also used as the basic polycrystal; in this example, y=0.97 is designed.

[0108] (3) Preparation of Fe 0.97 Se 0.4 Te 0.6 In an argon glove box, Fe powder (99.9%), Se powder (99.99%) and Te powder (99.99%) were mixed at the ratio of Fe:Se:Te=0.97:0.4:0.6 (Fe 0.97 Se 0.4 Te 0.6 ) were weighed 10 g and mixed in a mortar, then placed in 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 covered. The crucible was sealed in a vacuum quartz tube and melted and sintered at 880°C in a box-type muffle furnace for 3 days, and then the power was cut off to 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] The first polycrystal in Example 7 is also used as the basic polycrystal; in this example, y=0.96 is designed.

[0111] The same method was used to prepare Fe 0.96 Se 0.4 Te 0.6 Polycrystalline.

[0112] J of the first polycrystalline, Example 7, Example 8 and Comparative Example 4 c The value detection results are shown in Table 4:

[0113] Table 4

[0114]

[0115] Similarly, it can be seen from Table 4 that when the predetermined target is J under high field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When the Fe content in the raw material is reduced (i.e. y< ) to reduce the interstitial iron content in the superconducting phase, enhance the pinning ability of the polycrystalline, and improve the J under high field c .

[0116] It will be easily understood by those skilled in the art that the above description is only 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 in the protection scope of the present invention.

[0117] The parts not elaborated in detail in the description of the present invention belong to the known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A regulation Polycrystalline J c The method is characterized in that The steps include: (1) Select the first polycrystalline , among which the first polycrystalline J c The value is known; (2) Adjust according to the requirements of the predetermined goals The y value can be obtained by using the value, and x= ; The predetermined target includes J under high field c Or low field J c .

2. The method according to claim 1 Polycrystalline J c The method is characterized in that Step (1) is as follows: When the target is J under high field c When the first polycrystalline high field J c J whose value is less than the predetermined target c value; When the target is J in the low field c When the first polycrystalline is subjected to low field, J c J whose value is less than the predetermined target c value.

3. The method according to claim 2 Polycrystalline J c The method is characterized in that (2) Adjust according to the requirements of the predetermined goals The y value can be obtained by: When the target is J under high field c , and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When y< ; When the target is J in the low field c , and the predetermined target J c The value is greater than the J of the first polycrystalline under low field c When y> .

4. The method according to claim 3 Polycrystalline J c The method is characterized in that When the target is J under high field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under high field c When the value is 0< <0.04, where .

5. The method according to claim 4 Polycrystalline J c The method is characterized in that 6. The method according to claim 3 Polycrystalline J c The method is characterized in that When the target is J in the low field c value, and the predetermined target J c The value is greater than the J of the first polycrystalline under low field c When the value is 0< <0.02, where .

7. The method according to claim 6 Polycrystalline J c The method is characterized in that 8. The method according to any one of claims 1 to 7. Polycrystalline J c The method is characterized in that The control method further comprises 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 inert gas, the Fe powder, Se powder and Te powder weighed in step (3) are fully mixed and loaded into a reaction container; (5) The reaction vessel is melted, sintered and cooled to obtain Polycrystalline.

9. The method according to any one of claims 1 to 8 obtained Polycrystalline.

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