Iron-selenium-tellurium superconducting target material and preparation method thereof

Abstract

The invention belongs to the technical field of target material preparation, and relates to an iron selenium tellurium superconducting target material and a preparation method thereof. The iron selenium tellurium superconducting target material is FeySexTe1-x, wherein x is more than or equal to 0.4 and less than or equal to 1, and y is more than or equal to 0.6 and less than or equal to 2.0. The precursor FeySe1-xTex polycrystalline powder is subjected to high-temperature hot pressing sintering, and the FeSeTe superconducting target material which is good in uniformity, extremely high in density and free of cracks and pores is obtained. The preparation method can also meet different requirements, multiple FeSeTe target materials with different components can be prepared at the same time, and the preparation efficiency and flexibility of the FeSeTe target materials are greatly improved. Compared with the prior art, the preparation method has the advantages that the preparation time is shortened while the high quality of the FeSeTe target material is ensured, so that the preparation efficiency of the target material and the stability of the performance of the target material are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of target material preparation, and in particular relates to an iron-selenium-tellurium superconducting target material and a preparation method thereof. Background Art

[0002] Iron-based superconducting materials have great application potential in high magnetic field applications, such as controlled nuclear fusion and high-field magnets, due to their ultra-high upper critical field, small anisotropy and large critical current density. y Se x Te 1-x (hereinafter referred to as FeSeTe) superconducting materials have important application prospects in high-field magnets due to their simple structure, lack of toxic elements, and easy preparation into long strips of coated conductors with high strength and high uniformity. They have become a research hotspot in this field. At present, the main method for preparing high-performance FeSeTe coated conductors is pulsed laser deposition (PLD). Studies have shown that the superconducting properties of FeSeTe coatings, such as critical current density, are closely related to PLD deposition conditions, and high-quality target materials are one of the key factors in obtaining high-performance films.

[0003] The main preparation method of traditional FeSeTe target material is solid phase reaction method. This method has some defects that are difficult to overcome: due to the relatively low sintering temperature, the density of the final target material is low, and the composition is difficult to accurately control. In addition, cold pressing sintering is to press the sheet into shape before sintering. During the cooling process after sintering, there will be uneven shrinkage, resulting in poor density consistency of the target material, easy to produce cracks, and affect the performance and service life of the target material. In the preparation of FeSeTe coated conductors, the FeSeTe target material is a sputtering source that continuously generates plasma plume through the bombardment of PLD laser; however, the density of FeSeTe target materials prepared by the traditional solid phase reaction method is generally not high; such target materials are easy to pulverize under the high energy density and high frequency laser bombardment generated by PLD, resulting in uneven and poor uniformity of subsequent film formation, thereby affecting the performance of FeSeTe thin films and unable to achieve the preparation of long strips of coated conductors.

[0004] In contrast, the hot pressing sintering method can be sintered under pressure, effectively increasing the sintering temperature and promoting the fusion between powders, thereby obtaining a FeSeTe target with higher density and better uniformity. However, the traditional hot pressing sintering process also has some shortcomings: complex process, low preparation efficiency, high energy consumption and other problems, which limit its large-scale application. Patent CN114242333A provides an iron selenium tellurium sulfur superconducting target material and its preparation method and application, which combines grinding, pressing treatment and solid-phase sintering process. By sintering in different temperature ranges, the volatile vapor pressure of sulfur and selenium elements is greatly reduced, and a block with good uniformity and high density is obtained, and the Fe 7 Se 8 The generation of non-superconducting phases such as , improves the superconducting performance of Fe(Se,Te,S) target. However, the density of the target provided by the patent is 3.80g / cm 3 The density is not high, and the holes and cracks in the target material will affect the uniformity of the film and the life of the target material. Patent CN112010270A provides a FeBi (Te, Se) polycrystalline superconducting material and its preparation method and application, which combines grinding, pressing and solid phase sintering processes, and reduces the FeTe in Fe (Te, Se) by adding Bi. 2 The generation of impurities and the promotion of their grain growth greatly reduce the weak connection effect of Fe(Te,Se), and the obtained polycrystalline superconducting material has a high critical current density. However, the preparation process provided by the patent is time-consuming, inefficient, energy-intensive, and costly, and is not suitable for industrial production.

[0005] Therefore, there is an urgent need to develop an efficient, controllable and flexible hot pressing method for preparing FeSeTe superconducting targets to solve the problems of low preparation efficiency and high cost in the existing technology and provide a basis for the preparation of high-performance FeSeTe coated conductors. Summary of the invention

[0006] The purpose of the present invention is to provide an iron selenium tellurium superconducting target material and a preparation method thereof in order to overcome the defects of the above-mentioned prior art. The superconducting target material has good uniformity, high density, no cracks, and no pores, and multiple high-quality superconducting target materials can be obtained by one hot pressing and sintering, and the preparation efficiency is high.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a method for preparing an iron-selenium-tellurium superconducting target material, comprising the following steps:

[0009] S1, iron powder, selenium powder and tellurium powder are mixed, fully ground to obtain uniform powder and sealed, heated and sintered in a vacuum environment, and then cooled in the furnace to obtain a polycrystalline block, and then the Fe ySe 1-x Te x Polycrystalline powder, which is used as a powder for hot pressing target material;

[0010] S2, heating and pressurizing the powder to sinter in a vacuum environment, and grinding and polishing the powder after sintering to obtain an FeSeTe superconducting target.

[0011] Furthermore, in step S1, the heating and sintering conditions are: heating to 1000-1100°C for 2-5 hours, keeping the temperature for 5-24 hours, and then cooling with the furnace to obtain a polycrystalline block.

[0012] Further, in step S1, the Fe y Se 1-x Te x Polycrystalline powder, where 0≤x≤0.4, 0.6 <y≤2.0。

[0013] Furthermore, in step S1, the particle size of the powder is 300-1500 mesh.

[0014] Furthermore, in step S2, before heating and pressurizing sintering, the powder is placed in a hot pressing mold, the powder and the hot pressing mold are separated by a sealing material, and then the hot pressing mold containing the powder is placed in a hot pressing furnace body for heating and pressurizing sintering.

[0015] Furthermore, step S2 specifically includes putting multiple powders into a hot pressing mold, separating the mold and the powders with a sealing material, and then separating the powders with a gasket material, separating the gasket and the powders with a sealing material, thereby completing the preparation of multiple target materials at one time.

[0016] Furthermore, the sealing material is graphite paper; and the gasket material is graphite gasket.

[0017] Furthermore, in step S2, the vacuum environment is achieved by controlling the vacuum degree to 1×10 -4 Pa-5×10 - 3 Pa achieved.

[0018] Furthermore, in step S2, the heating is specifically that the heating temperature is set at 500-700°C.

[0019] Furthermore, in step S2, the pressurization is specifically that the pressure is set at 20-27 MPa.

[0020] The invention also provides an iron-selenium-tellurium superconducting target material prepared by the preparation method.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The present invention aims to solve the problems of low efficiency and high cost in the preparation of superconducting target materials in the prior art, and provides an efficient and flexible hot pressing preparation method to obtain high-quality Fe y Se x Te 1-x Target material. Due to the complex phase diagram of iron selenium telluride materials, the superconducting tetragonal phase is easily converted into a non-superconducting hexagonal phase at high temperature. The sintering temperature cannot be too high, generally less than 450°C. Therefore, after cold pressing and sintering, it can only be heated and sintered at a lower temperature, which makes the target material density lower. In addition, Se and Te are both volatile elements. After sintering after tableting, the volatilization loss of Se and Te will also form loosely connected areas in the target material. Under pressurized conditions, the thermal stability of the superconducting tetragonal phase is enhanced, and it can be sintered at a higher temperature. The coupling of heating and pressurization enhances the volume diffusion of particles inside the target material. Under high temperature and high pressure, the particles undergo plastic deformation, which promotes particle contact, helps eliminate pores, and promotes densification. Therefore, the precursor Fe y Se 1-x Te x The polycrystalline powder is sintered by high-temperature hot pressing. By setting reasonable pressure, sintering temperature and holding time, a FeSeTe target with good uniformity, extremely high density, no cracks and no pores is obtained.

[0023] (2) The present invention separates different powders by adding gaskets in a high-temperature hot-pressing mold, and completes the preparation of multiple target materials in one production experiment, which fully demonstrates the high efficiency and flexibility of the target material preparation method. On the one hand, for the same batch of alloy powders with the same components, multiple high-quality targets with the same performance can be obtained by hot pressing and sintering at one time, which not only reduces the background error caused by multiple batches of experiments, ensures the uniformity of target quality, and further provides batch targets with stable performance for the long strip preparation of high-quality superconducting films; in addition, the preparation time of a single target material is used to achieve the preparation of multiple targets, greatly reducing energy loss. On the other hand, for the same batch of alloy powders with different components, multiple high-quality targets with different components can be obtained by hot pressing at one time. Whether it is the same component or different components, the "high efficiency" of this technology is reflected.

[0024] (3) The present invention prepares multiple targets at one time by separating them with gaskets, which improves the repeatability of the process, can effectively reduce production costs, greatly improve preparation efficiency, and also ensure the performance stability of targets produced in the same batch. At the same time, the present invention flexibly prepares targets that meet different needs by adjusting the number of gaskets and filling powders with different ingredients, reflecting the "flexibility" of high-throughput technology.

[0025] (4) The FeSe superconducting target material of the present invention has a regular shape, uniform texture, smooth surface and no cracks, and its main phase is the FeSe superconducting phase. Its mass is measured to be 11.0 g, its diameter is 19.5 mm, its thickness is 6.7 mm, and its density is calculated to be 5.4 g / cm 3 The actual density reaches 94% of the theoretical density, and the density is extremely high. Another FeSeTe superconducting target material of the present invention has high density, and the volume magnetic susceptibility of the target material reaches negative 90% at 1.8K. The target material exhibits strong anti-magnetism, indicating that the superconductor almost completely repels the external magnetic field at this time, showing significant superconducting properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a diagram of an experimental device for comparative example 1 of the present invention;

[0027] Figure 2 is a diagram of an experimental device of Embodiment 1-2 of the present invention;

[0028] Figure 3 is a physical picture of two target materials obtained in a single experiment in Example 1 of the present invention;

[0029] Figure 4 is the X-ray diffraction pattern of two target materials obtained in a single experiment in Example 1 of the present invention;

[0030] Figure 5 is a SEM image of two target materials obtained in a single experiment in Example 1 of the present invention, Figure 5 a is the SEM image of target A, Figure 5 b is the SEM image of target B;

[0031] Figure 6 is the X-ray diffraction pattern of four iron-selenium-tellurium targets of different compositions obtained in a single experiment in Example 2 of the present invention;

[0032] Figure 7 The Fe obtained in Example 2 of the present invention 1.06 Se 0.4 Te 0.6 SEM image of the target;

[0033] Figure 8 The Fe obtained in Example 2 of the present invention 1.06 Se 0.4 Te 0.6 The target volume magnetic susceptibility as a function of temperature;

[0034] Fig. 9 This is a physical picture of a target material obtained in a single experiment in Comparative Example 1 of the present invention;

[0035] Fig.10It is a SEM picture of the target material obtained in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0037] The raw materials and equipment used in the present invention are all conventional raw materials and equipment in the art. In the following embodiments, raw materials or processing techniques, unless otherwise specified, are all conventional commercially available raw materials or conventional processing techniques in the art.

[0038] The present invention provides an iron-selenium-tellurium superconducting target material, which is prepared by the following steps:

[0039] S1, iron powder, selenium powder and tellurium powder are mixed, fully ground to obtain uniform powder and placed in a quartz tube for vacuum sealing, placed in a high-temperature sintering furnace, heated to 1000-1100°C for 2-5 hours, kept at this temperature for 5-24 hours, and then cooled with the furnace to obtain a polycrystalline block, the polycrystalline block is crushed and fully ground to obtain Fe y Se 1-x Te x Polycrystalline powder, used as a powder for hot pressing target. y Se 1-x Te x Polycrystalline powder, the particle size is 300-1500 mesh, where 0≤x≤0.4, 0.6 <y≤2.0。

[0040] S2, such as Figure 1 As shown, the powder is placed in a hot pressing mold, the powder and the hot pressing mold are separated by a sealing material, and then the hot pressing mold containing the powder is placed in a hot pressing furnace, and the powder is heated and pressurized to sinter in a vacuum environment. After sintering, the powder is polished with sandpaper to obtain an FeSeTe superconducting target. The vacuum environment is controlled by controlling the vacuum degree to 1×10 -4 Pa-5×10 -3 Pa is achieved; the heating is specifically that the heating temperature is set at 500-700°C; the pressurization is specifically that the pressure is set at 20-27MPa.

[0041] In some specific embodiments, multiple powders are placed in a hot pressing mold, the mold and the powders are separated by a sealing material, and then the powders are separated by a gasket material, and the gasket and the powders are separated by a sealing material, so that the preparation of multiple target materials is completed at one time, such as Figure 2 shown.

[0042] In some specific implementations, the sealing material is graphite paper; and the gasket material is graphite gasket.

[0043] Example 1

[0044] The specific steps of this embodiment are as follows:

[0045] 1) In an argon-protected glove box, 24 g of iron powder (purity 99.9%) and selenium powder (purity 99.9%) were mixed evenly in a molar ratio of 1:1 to obtain a mixed powder. The mixed powder was placed in a quartz tube for vacuum sealing, placed in a high-temperature sintering furnace, heated to 1100°C for 5 hours, kept warm for 24 hours, and then cooled with the furnace to obtain a polycrystalline block. The polycrystalline block was crushed, put into a mortar, and ground evenly for 0.5 hours to obtain a polycrystalline powder FeSe as a powder for a hot pressing target.

[0046] 2) In an argon-protected glove box, the powder was divided into two equal parts, each with a mass of 12 g. The two parts of alloy powder were placed in a graphite mold with an inner diameter of 20 mm for high-temperature hot pressing. The two parts of alloy powder were separated by a graphite sheet. At the same time, the alloy powder and the graphite mold were separated by graphite paper to avoid adhesion. The graphite mold containing the alloy powder was placed in a hot pressing furnace, and then vacuum hot pressing was performed to obtain two FeSe superconducting targets, which were named target A and target B respectively. The vacuum degree during the sintering process was not less than 1×10 -3 Pa, the sintering temperature is 600℃, the holding time is 5 hours, and after the holding is completed, the furnace is cooled to 25℃. The applied pressure is 27MPa, and the pressure is maintained throughout the sintering process until the target is taken out after the sintering is completed.

[0047] 3) Take out the hot-pressed target material and polish it with sandpaper to obtain a FeSe target material with a smooth surface.

[0048] The XRD test process of this embodiment is as follows:

[0049] An X-ray diffractometer (Bruker, Germany, D2 PHASER desktop diffractometer) was used. The instrument used a Cu target as the anode target and the wavelength of the Kα ray was The angle resolution is 0.02°, the peak intensity accuracy is ±2%, and the upper limit of peak width detection is 0.05°. First, place the target on the sample stage, align the target surface with the horizontal plane, and then perform conventional X-ray diffraction on the target surface at room temperature. The measurement angle range is set to 10°~70°, the step size is set to 0.05°, and the test time is about 15 minutes.

[0050] Figure 3 Figure 2 is a physical picture of target material A and target material B obtained in this embodiment. Figure 3As shown, it can be seen that target A and target B have regular shapes, uniform texture, smooth surface and no cracks. After measurement, the mass of target A is 11.0g, the diameter is 19.6mm, the thickness is 6.7mm, and its density is calculated to be 5.4g / cm 3 Target B has a mass of 11.0 g, a diameter of 19.5 mm, and a thickness of 6.7 mm. Its density is calculated to be 5.4 g / cm 3 The actual density of target A and target B both reached 94% of the theoretical density, and the density was extremely high.

[0051] Figure 4 The X-ray diffraction results of target material A and target material B obtained in this embodiment show that the phase compositions of target material A and target material B are almost identical, and the main phases are both FeSe superconducting phases.

[0052] Figure 5 This is a scanning electron microscope morphology image of the surface of target material A and target material B obtained in this embodiment after grinding and polishing. Figure 5 a is the SEM image of target A, Figure 5 b is the SEM image of target B. Figure 5 It can be seen that both target A and target B are very dense, uniform in texture, and have no obvious cracks, holes, or impurities.

[0053] Example 2

[0054] The specific steps of this embodiment are as follows:

[0055] 1) In an argon-protected glove box, iron powder (purity 99.9%), selenium powder (purity 99.9%) and tellurium powder (purity 99.9%) with molar ratios of 0.6:0.4:0.6, 1.06:0.4:0.6, 1.5:0.4:0.6 and 2.0:0.4:0.6 were mixed evenly to obtain four uniform mixed powders with different proportions. The four mixed powders with different proportions were placed in different quartz tubes for vacuum sealing and placed in a high-temperature sintering furnace. The temperature was raised to 1000°C in 2 hours, kept warm for 12 hours, and then cooled with the furnace to obtain four polycrystalline blocks with different components. The polycrystalline blocks with different components were crushed separately, put into a mortar, and ground evenly for 1 hour to obtain four Fe y Se 1-x Te x The polycrystalline powders have the nominal compositions of Fe 0.6 Se 0.4 Te 0.6 , Fe 1.06 Se 0.4 Te 0.6 , Fe 1.5 Se 0.4 Te 0.6 , Fe2.0 Se 0.4 Te 0.6 , as powder for hot pressing target.

[0056] 2) In an argon-protected glove box, 11 g of each of the following were used: Fe 0.6 Se 0.4 Te 0.6 , Fe 1.06 Se 0.4 Te 0.6 , Fe 1.5 Se 0.4 Te 0.6 , Fe 2.0 Se 0.4 Te 0.6 The polycrystalline powder is put into the graphite mold, and the powders of different compositions are separated by graphite gaskets. At the same time, the powders and the graphite mold are separated by graphite paper to avoid adhesion and demoulding difficulties. The mold is put into the hot pressing furnace and then vacuum hot pressing sintering is carried out. The vacuum degree during the sintering process is not less than 5×10 -3 Pa, the sintering temperature is 600℃, the holding time is 5 hours, and after the holding is completed, the furnace is cooled to 25℃. The applied pressure is 27MPa, and the pressure is maintained throughout the sintering process until the target is taken out after the sintering is completed.

[0057] 3) The hot-pressed target material is taken out and polished with sandpaper to obtain a plurality of FeSeTe superconducting target materials with smooth surfaces.

[0058] The XRD test process of this embodiment is as follows:

[0059] An X-ray diffractometer (Bruker, Germany, D2 PHASER desktop diffractometer) was used. The instrument used a Cu target as the anode target and the wavelength of the Kα ray was The angle resolution is 0.02°, the peak intensity accuracy is ±2%, and the upper limit of peak width detection is 0.05°. First, place the target on the sample stage, align the target surface with the horizontal plane, and then perform conventional X-ray diffraction on the target surface at room temperature. The measurement angle range is set to 10°~70°, the step size is set to 0.05°, and the test time is about 15 minutes.

[0060] Figure 6 The X-ray diffraction patterns of four FeSeTe superconducting targets with different compositions obtained in this example show that the main phase of these superconducting targets is the superconducting tetragonal phase. After testing, the compositions of the targets are: Fe 0.6 Se 0.4 Te 0.6 , Fe 1.06 Se 0.4 Te 0.6 , Fe1.5 Se 0.4 Te 0.6 , Fe 2.0 Se 0.4 Te 0.6 This shows that this technical solution can prepare multiple high-quality FeSeTe targets of different components in one experiment, which greatly improves production efficiency, conforms to the connotation of high-throughput technology, and shortens the production and R&D cycle.

[0061] Figure 7 The Fe 1.06 Se 0.4 Te 0.6 Scanning electron microscope morphology of the target surface after grinding and polishing. Figure 7 It can be seen that Fe 1.06 Se 0.4 Te 0.6 The target material has good density consistency, uniform texture, and no obvious cracks, holes or impurities.

[0062] The testing process of volume magnetic susceptibility of this embodiment is as follows:

[0063] The volume susceptibility test was completed on a high-precision magnetic property measurement system (Magnetic Property Measurement System, MPMS) developed by Quantum Desigh, USA. The target sample was cut into 1.5mm×2.0mm×3.2mm rectangular blocks, fixed in the middle of the copper rod used for testing, and then placed in the sample chamber of the magnetic measurement system, evacuated, the temperature was lowered to 1.8K, an external magnetic field of 10Oe was applied, and then zero-field cooling and field cooling tests were performed. The demagnetization factor was calculated according to the sample size, the volume magnetization was calculated according to the ratio of the measured magnetization intensity to the sample volume, and the volume susceptibility was obtained according to the ratio of the volume magnetization intensity to the external magnetic field. The magnetization intensity-temperature curve obtained from the test was then converted into a "volume susceptibility-temperature curve", which can reflect the magnetic properties of the target. Ideally, a superconducting target with a density of 100% can show a negative volume susceptibility of 100% below the superconducting transition temperature, that is, the complete diamagnetism of the superconducting sample.

[0064] Figure 8 The Fe 1.06 Se 0.4 Te 0.6 The volume magnetic susceptibility of a superconductor is plotted as a function of temperature. Ideally, when a superconductor enters the superconducting state, its interior will completely reject the magnetic field, which means that the magnetic susceptibility is negative 100%. Figure 8As shown in the figure, the volume magnetic susceptibility of the target material reaches negative 90% at 1.8K, indicating that the superconductor exhibits strong anti-magnetism, namely the Meissner effect, which means that the superconductor almost completely repels the external magnetic field. It may be due to factors such as experimental conditions or sample quality that the ideal negative 100% is not achieved, but this does not affect the Fe 1.06 Se 0.4 Te 0.6 The target material has remarkable superconducting properties.

[0065] Comparative Example 1

[0066] The specific steps of this comparative example are as follows:

[0067] This comparative example relates to a method for preparing a high-density FeSe superconducting target material. The steps are basically the same as those in Example 1. The raw materials used are iron powder (purity 99.9%) and selenium powder (purity 99.9%) with a total mass of 12g and a molar ratio of 1:1. The method described in this comparative example is different from that in Example 1 only in that no gasket is added to the mold in this comparative example. Figure 1 As shown in the figure, only the powder of a target material is placed. Fig. 9 As shown, the target material of this comparative example is very dense and has a uniform texture without obvious cracks, holes or impurities.

[0068] The mass of the FeSe superconducting target is 11.0 g, the diameter is 19.5 mm, the thickness is 6.7 mm, and its density is 5.4 g / cm 3 , the diameter, thickness and density of the target material hot-pressed in this comparative example and in Example 1 are almost identical, and there is no difference within the error range. In summary, the phase composition, component ratio and density of the target material hot-pressed in this comparative example and in Example 1 are the same as those of the target material in Example 1.

[0069] The results of this comparative example show that there is no obvious quality difference between multiple targets of the same component prepared by separation with gaskets and a single target prepared without gaskets. This indicates that the method of adding gaskets to the mold and obtaining multiple targets in the cycle of preparing one target can effectively reduce production costs and greatly improve preparation efficiency, while also ensuring the performance stability of targets produced in the same batch.

[0070] Comparative Example 2

[0071] The specific steps of this comparative example are as follows:

[0072] 1) In an argon-protected glove box, iron powder (purity 99.9%), selenium powder (purity 99.9%) and tellurium powder (purity 99.9%) in a molar ratio of 1.06:0.4:0.6 were mixed to obtain a uniformly mixed powder. The mixed powder was placed in a quartz tube for vacuum sealing and placed in a high-temperature sintering furnace. The temperature was raised to 1000°C in 2 hours, kept at this temperature for 12 hours, and then cooled with the furnace to obtain Fe 1.06 Se 0.4 Te 0.6 Polycrystalline block. 1.06 Se 0.4 Te 0.6 The polycrystalline block was crushed, put into a mortar, and ground evenly for 1 hour to obtain Fe 1.06 Se 0.4 Te 0.6 powder.

[0073] 2) In an argon-protected glove box, 11 g of Fe 1.06 Se 0.4 Te 0.6 The polycrystalline powder was pressed at a pressure of 27 MPa, which was maintained during the entire pressing process for 1 hour to obtain a compact.

[0074] 3) After the pressing is completed, the pressed block is placed in a quartz tube and the quartz tube is vacuum sealed. The internal pressure of the quartz tube is not less than 5×10 -3 Pa. Then the quartz tube is placed in a sintering furnace for heating and sintering. The sintering temperature is 600°C and the holding time is 5 hours. After the holding is completed, the target is cooled to 25°C with the furnace and the target is taken out.

[0075] 4) Grinding and polishing the target surface.

[0076] Fig.10 This is a scanning electron microscope morphology image of the target material obtained in this comparative example after grinding and polishing. Fig.10 As shown in the figure, cold pressing followed by sintering makes the target material density lower; in addition, Se and Te are both volatile elements, and the volatilization loss of Se and Te after sintering will form loosely connected areas in the target material. 1.06 Se 0.4 Te 0.6 The polycrystalline powder is cold pressed and then sintered to obtain Fe 1.06 Se 0.4 Te 0.6 The density consistency of the target material is poor, and there are cracks and pores inside.

[0077] Under the hot pressing sintering conditions of Example 2, the thermal stability of the superconducting tetragonal phase is enhanced, and sintering can be performed at a higher temperature. The coupling of heating and pressurization enhances the volume diffusion of particles inside the target material. Under high temperature and high pressure, the particles undergo plastic deformation, which promotes particle contact, is conducive to eliminating pores, and promotes densification. 1.06 Se 0.4 Te 0.6 The polycrystalline powder is sintered by high temperature hot pressing to obtain Fe 1.06 Se 0.4 Te 0.6 The target material has good uniformity, high density, no cracks, no pores, such as Figure 7 shown.

[0078] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an iron selenium tellurium superconducting target, characterized in that: The steps include: S1, iron powder, selenium powder and tellurium powder are mixed, fully ground to obtain uniform powder and sealed, heated and sintered in a vacuum environment, and then cooled in the furnace to obtain a polycrystalline block, and then the Fe y Se 1-x Te x Polycrystalline powder, which is used as a powder for hot pressing target material; S2, heating and pressurizing the powder to sinter in a vacuum environment, and grinding and polishing the powder after sintering to obtain an FeSeTe superconducting target.

2. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: In step S1, the heating and sintering conditions are: heating to 1000-1100°C for 2-5 hours, keeping the temperature for 5-24 hours, and then cooling in the furnace to obtain a polycrystalline block.

3. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: In step S1, the Fe y Se 1-x Te x polycrystalline powder, where 0 ≤ x ≤ 0.4 and 0.6 < y ≤ 2.0; the particle size of the powder is 300 - 1500 mesh.

4. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: In step S2, before heating and pressurizing sintering, the powder is placed in a hot pressing mold, the powder and the hot pressing mold are separated by a sealing material, and then the hot pressing mold containing the powder is placed in a hot pressing furnace for heating and pressurizing sintering.

5. The method for preparing an FeSeTe superconducting target material according to claim 4, characterized in that: Step S2 specifically includes putting multiple powders into a hot pressing mold, separating the mold and the powders with a sealing material, and then separating the powders with a gasket material, separating the gasket and the powders with a sealing material, thereby completing the preparation of multiple target materials at one time.

6. The method for preparing an FeSeTe superconducting target material according to claim 5, characterized in that: The sealing material is graphite paper; the gasket material is graphite gasket.

7. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: The vacuum environment is achieved by controlling the vacuum degree at 1×10 -4 Pa-5×10 -3 Pa achieved.

8. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: In step S2, the heating is specifically that the heating temperature is set at 500-700°C.

9. The method for preparing an FeSeTe superconducting target material according to claim 1, characterized in that: In step S2, the pressurization is specifically that the pressure is set at 20-27 MPa.

10. An FeSeTe superconducting target material prepared by the preparation method according to any one of claims 1 to 9.

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