A method for preparing a bismuth-tellurium-selenium alloy target

Abstract

The application discloses a preparation method of a bismuth-tellurium-selenium alloy target material and belongs to the technical field of target material preparation. 3‑x Se x The raw material Bi, the raw material Te and the raw material Se are proportioned according to Bi2Te x=0.15-0.5, and then are smelted, the obtained bismuth-tellurium-selenium alloy ingot is subjected to gas atomization to obtain a bismuth-tellurium-selenium alloy powder with an average particle size less than 45 μm; the bismuth-tellurium-selenium alloy powder is subjected to step-by-step hot-pressing sintering to obtain a bismuth-tellurium-selenium alloy target material; the first hot-pressing sintering condition includes that the sintering temperature is 180-360 ℃ and the sintering pressure is 15-20 MPa; the second hot-pressing sintering condition includes that the sintering temperature is 320-360 ℃ and the sintering pressure is 12-15 MPa. The application obtains the bismuth-tellurium-selenium alloy target material with small and uniform grain sizes, high density and high purity through step-by-step sintering and control of the parameters of the step-by-step sintering, and the method is simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of target preparation technology, specifically relating to a method for preparing a bismuth tellurium selenide alloy target. Background Technology

[0002] Thermoelectric materials are functional materials capable of converting electrical energy into thermal energy, and bismuth telluride-based alloys are currently the best-performing commercially available thermoelectric materials near room temperature. They possess excellent characteristics such as being pollution-free, lossless, and highly reliable, and are expected to significantly improve energy efficiency and alleviate environmental pollution.

[0003] Due to the inability to effectively reduce the thermal conductivity of bulk thermoelectric materials, progress in their performance research has been slow. Since the early 1990s, when Hicks et al. proposed the theory that dimensional reduction could significantly improve the performance of thermoelectric materials, thin-film thermoelectric materials have begun to receive widespread attention. Magnetron sputtering utilizes accelerated ions to bombard target atoms and deposit a film. Compared with other preparation methods, bismuth telluride-based thin films prepared by magnetron sputtering have advantages such as low deposition temperature, fast deposition rate, good compositional consistency between the film and the target, and accurate thickness control. It is suitable for preparing multilayer thin films of various materials and is easy to industrialize, making it a commonly used thin film preparation method. Since the performance of the thin film material is closely related to the performance of the sputtering target, the preparation of the target is crucial.

[0004] The target material has a polycrystalline structure. The finer the grains, the larger the grain boundary area, and the greater the impact on performance. For the same target material, the sputtering rate of a target with fine grains is faster than that of a target with coarse grains; and the film thickness of the film deposited by sputtering a target with smaller differences in grain size (uniform distribution) is more uniform.

[0005] Patent CN 112457013 B discloses a method for preparing tellurium-bismuth-based targets. The method involves melting an alloy crystal rod in a vacuum melting crucible, casting the melt to obtain a tellurium-bismuth-based target blank, and then machining the blank to obtain the tellurium-bismuth-based target material. The target material prepared by this melting and casting method has coarse grains, and its microstructure, properties, and defects are difficult to control.

[0006] Powder metallurgy typically involves alloying raw materials to form ingots, then mechanically crushing them to obtain powder, which is then sintered into a final shape. However, the crushing process easily introduces impurities and increases oxygen content, and the resulting powder usually has an irregular morphology, which is not conducive to obtaining good microstructure and properties.

[0007] Therefore, in order to facilitate research on improving the performance of thermoelectric materials, there is an urgent need for a method to prepare bismuth telluride selenide alloy targets with fine and uniform grains. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing bismuth tellurium selenide alloy targets; the target material prepared by this method has small and uniform grain size and high density.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing a bismuth tellurium selenide alloy target includes the following steps:

[0011] Preparation of bismuth tellurium selenide alloy powder: raw materials Bi, Te, and Se are mixed in the manner of Bi2Te 3-x Se x The ingredients with x = 0.15-0.5 were smelted, and the resulting bismuth tellurium selenide alloy ingots were atomized to obtain bismuth tellurium selenide alloy powder with an average particle size of less than 45 μm.

[0012] Preparation of bismuth tellurium selenide alloy target: Bismuth tellurium selenide alloy powder is subjected to stepwise hot pressing sintering to obtain bismuth tellurium selenide alloy target; the conditions for the first hot pressing sintering include: sintering temperature of 180-360℃ and sintering pressure of 15-20MPa; the conditions for the second hot pressing sintering include: sintering temperature of 320-360℃ and sintering pressure of 12-15MPa.

[0013] In a preferred embodiment of the preparation method of the bismuth tellurium selenide alloy target of this application, the temperature of the first hot pressing sintering is 300-360℃; the temperature of the second hot pressing sintering is 330-350℃.

[0014] In this application, a bismuth telluride selenide alloy target with small and uniform grain size, high density, and high purity is obtained by step-by-step sintering and controlling the parameters of step-by-step sintering. Since the average particle size of bismuth telluride selenide alloy powder is less than 45 μm, the following problems will occur when preparing the target by hot pressing sintering in one step: (1) serious powder loss during sintering; (2) low density of the target; (3) high brittleness of the target and easy cracking. Among them, if the temperature of the first sintering is too high, it will cause the grain size distribution of the target to be uneven, which will lead to uneven thickness distribution of the film sputtered by the target and reduce the performance of the film. If the temperature of the second sintering is too high, it will cause the grains of the target to grow; if the temperature of the second sintering is too low, it will cause the density of the target to be low. The preferred temperature of the first hot pressing sintering in this invention is 300-360℃; the temperature of the second hot pressing sintering is 340-360℃, so as to obtain a bismuth telluride selenide alloy target with small and more uniform grain size and higher density.

[0015] In a preferred embodiment of the preparation method of the bismuth tellurium selenide alloy target of this application, the first hot pressing sintering time is 60-90 min, and the second hot pressing sintering time is 50-80 min.

[0016] The hot pressing sintering time also affects the grain size and density of the target material. If the first hot pressing sintering time is too long, it will cause the grains of the target material to grow. If the sintering time is too short, the density of the material after demolding will be low, making it difficult to obtain a bismuth telluride selenide alloy target material with smaller and more uniform grain size and higher density after a second hot pressing sintering. If the second sintering time is too short, it will also lead to low density of the target material. If the sintering time is too long, it will also lead to grain growth of the target material, resulting in uneven grain size distribution.

[0017] In a preferred embodiment of the preparation method of the bismuth tellurium selenide alloy target of this application, the heating rate of the first hot pressing sintering is 10-20℃ / min; the heating rate of the second hot pressing sintering is 10-20℃ / min.

[0018] In a preferred embodiment of the preparation method of the bismuth tellurium selenide alloy target of this application, the pressure increase rate of the first hot pressing sintering is 0.3-1.5 MPa / min; the pressure increase rate of the second hot pressing sintering is 0.3-1.5 MPa / min.

[0019] The heating and pressurization rates within the aforementioned range can improve the uniformity and density of the target grain size, and also increase the efficiency of target preparation.

[0020] In this application, the bismuth telluride selenide alloy powder is the n-type bismuth telluride-based thermoelectric material as described in claim 9 of patent CN 113800480 A, and its preparation method is described in detail in that patent document.

[0021] Specifically, the preparation method of the bismuth tellurium selenide alloy powder is as follows:

[0022] (1) Mix raw materials Bi, Te and Se according to Bi2Te 3-x Se x x = 0.15-0.5 The ingredients are added to a glass tube and then vacuum-sealed.

[0023] (2) The vacuum-sealed glass tube is placed in a swing furnace for melting. After melting, the glass tube is taken out and placed vertically to cool, thus obtaining a bismuth telluride-based alloy ingot.

[0024] (3) Place the bismuth telluride-based alloy ingot into the gas atomization equipment, evacuate the atomization chamber, and then introduce atomizing gas to clean the furnace.

[0025] (4) After the furnace is cleaned, the temperature is raised and smelted. After the bismuth telluride-based alloy ingot is completely melted into a melt, it is kept at the temperature for refining. Then the temperature is raised to the atomization temperature, the nozzle is heated, and the atomizing gas is started. When the gas atomization pressure is reached, atomization begins.

[0026] (5) After atomization, cool to room temperature to obtain n-type bismuth telluride selenium alloy powder.

[0027] This application utilizes a gas atomization process to obtain n-type bismuth telluride selenium alloy powder with good sphericity, low oxygen content, and spherical powder characteristics.

[0028] Another objective of this application is to provide a bismuth telluride selenide alloy target material, which is prepared by the above-described method for preparing bismuth telluride selenide alloy targets.

[0029] Another object of this application is to provide the application of the bismuth telluride selenide alloy target in the preparation of bismuth telluride selenide thin films.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application obtains bismuth telluride selenide alloy targets with small and uniform grain size, high density and purity by step-by-step sintering and controlling the parameters of step-by-step sintering. The method of the present invention is simple and suitable for large-scale industrial production. Attached Figure Description

[0031] Figure 1 This is a scanning electron microscope image of a local fracture surface of the target material obtained in Example 1;

[0032] Figure 2 The image shows a scanning electron microscope (SEM) image of a local fracture surface of the target material obtained in Comparative Example 1.

[0033] Figure 3 The image shows a scanning electron microscope (SEM) image of a local fracture surface of the target material obtained in Comparative Example 2.

[0034] Figure 4 This is a scanning electron microscope image of a local fracture surface of the target material obtained in Comparative Example 6. Detailed Implementation

[0035] To better illustrate the purpose, technical solution, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, aims to provide a detailed understanding of the invention, rather than limiting it. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0036] In the embodiments and comparative examples of this application, the purity of raw material Bi is ≥99.99%, the purity of raw material Te is ≥99.999%, and the purity of raw material Se is ≥99.995%.

[0037] In Examples 1-8 and Comparative Examples 1-5 of this application, the method for preparing the bismuth telluride selenium alloy powder includes the following steps:

[0038] (1) Based on a total feed amount of 1 kg, according to Bi2Te 2.7 Se 0.3 Weigh the ingredients according to the stoichiometric ratio, add them to a high borosilicate glass tube, and seal under vacuum.

[0039] (2) Place the vacuum-sealed high borosilicate glass tube into the swing furnace for full melting. The melting temperature is 700℃. First, preheat for 5 minutes, then swing and melt for 6 minutes. Take it out and shake it evenly. Then put it back into the swing furnace for 2 minutes of refining. Take it out and stand it upright against the iron frame. Gently tap the glass tube wall to remove the bubbles in the melt. After naturally cooling to room temperature, break the glass tube and take out the alloyed n-type bismuth telluride-based alloy ingot.

[0040] (3) Add n-type bismuth telluride-based alloy ingots to an alumina crucible, with a total feed amount of 5 kg, and then evacuate the atomization chamber to 10 °C. -3 After Pa, argon gas is introduced and the furnace is cleaned for 10 minutes. The temperature is increased to 650℃ at a rate of 12℃ / min for melting. After the alloy is completely melted into a molten body, it is held at this temperature for 6 minutes for refining. When the molten body temperature reaches the atomization temperature of 700℃, the nozzle is heated to 400℃. The nozzle diameter is 3.5mm. The stopper rod is pressed down, and argon gas is started. When the gas atomization pressure reaches 0.8MPa, the stopper rod is pulled up to start atomization.

[0041] (4) After atomization, turn off the argon gas and the nozzle heating power, maintain the argon gas pressure at 0.02 MPa, and cool it down to room temperature. Clean the powder from the collection chamber and cyclone separator to obtain n-type bismuth tellurium selenide alloy powder. The composition test results of the bismuth tellurium selenide alloy powder show that Bi is 53.05 wt.%, Te is 43.81 wt.%, Se is 3.06 wt.%, and the oxygen content is 0.04%. 50 It is 18.000μm.

[0042] Example 1

[0043] This embodiment provides a method for preparing a bismuth tellurium selenide alloy target, including the following steps:

[0044] 500g of bismuth tellurium selenide alloy powder was weighed and placed in a mold. At the same time, the pressure and temperature were increased to the temperature and pressure for the first sintering. The pressure and temperature increase time was 10min. The first sintering was carried out at 180℃ and 18MPa for 80min. After the first sintering was completed, the sample was cooled to room temperature and then demolded. When the sample was demolded after the first sintering, it cracked in half radially to obtain fragments.

[0045] The obtained fragments were broken and placed in a mold. At the same time, pressure and temperature were increased to the temperature and pressure for the second sintering. The pressure and temperature increase time was 20 minutes. The second sintering was carried out at 360℃ and 15MPa for 70 minutes. After the second sintering was completed, the material was cooled to room temperature and demolded to obtain the bismuth tellurium selenide alloy target.

[0046] Example 2

[0047] This embodiment provides a method for preparing a bismuth tellurium selenide alloy target, including the following steps:

[0048] 500g of bismuth tellurium selenide alloy powder was weighed and placed in a mold. The temperature and pressure were simultaneously increased to the temperature and pressure for the first sintering. The time for increasing the temperature and pressure was 30min. The first sintering was carried out at 360℃ and 18MPa for 60min. After the first sintering was completed, the sample was cooled to room temperature and then demolded. When the sample was demolded after the first sintering, it cracked in half radially to obtain fragments.

[0049] The obtained fragments were broken and placed in a mold. At the same time, pressure and temperature were increased to the temperature and pressure for the second sintering. The pressure and temperature increase time was 20 minutes. The second sintering was carried out at 360℃ and 15MPa for 70 minutes. After the second sintering was completed, the material was cooled to room temperature and demolded to obtain the bismuth tellurium selenide alloy target.

[0050] Example 3

[0051] This embodiment provides a method for preparing a bismuth tellurium selenide alloy target, including the following steps:

[0052] 500g of bismuth tellurium selenide alloy powder was weighed and placed in a mold. The temperature and pressure were simultaneously increased to the temperature and pressure for the first sintering. The time for increasing the temperature and pressure was 30min. The first sintering was carried out at 360℃ and 15MPa for 60min. After the first sintering was completed, the sample was cooled to room temperature and then demolded. When the sample was demolded after the first sintering, it cracked in half radially to obtain fragments.

[0053] The obtained fragments were broken and placed in a mold. At the same time, pressure and temperature were increased to the temperature and pressure for the second sintering. The pressure and temperature increase time was 30 minutes. The second sintering was carried out at 360℃ and 12MPa for 60 minutes. After the second sintering was completed, the material was cooled to room temperature and demolded to obtain the bismuth tellurium selenide alloy target.

[0054] Example 4

[0055] This embodiment provides a method for preparing a bismuth tellurium selenide alloy target, including the following steps:

[0056] 500g of bismuth tellurium selenide alloy powder was weighed and placed in a mold. The temperature and pressure were simultaneously increased to the temperature and pressure for the first sintering. The time for increasing the temperature and pressure was 30min. The first sintering was carried out at 360℃ and 20MPa for 90min. After the first sintering was completed, the sample was cooled to room temperature and then demolded. When the sample was demolded after the first sintering, it cracked in half radially to obtain fragments.

[0057] The obtained fragments were broken and placed in a mold. At the same time, pressure and temperature were increased to the temperature and pressure for the second sintering. The pressure and temperature increase time was 30 minutes. The second sintering was carried out at 360℃ and 13MPa for 50 minutes. After the second sintering was completed, the material was cooled to room temperature and demolded to obtain the bismuth tellurium selenide alloy target.

[0058] Example 5

[0059] The only difference between the preparation method of the bismuth telluride selenium alloy target in this embodiment and that in Embodiment 3 is that the temperature of the first sintering is 300°C.

[0060] Example 6

[0061] The only difference between the preparation method of the bismuth telluride selenium alloy target in this embodiment and that in Embodiment 3 is that the temperature of the first sintering is 250°C.

[0062] Example 7

[0063] The only difference between the preparation method of the bismuth telluride selenium alloy target in this embodiment and that in Example 3 is that the temperature of the second sintering is 340°C.

[0064] Example 8

[0065] The only difference between the preparation method of the bismuth telluride selenium alloy target in this embodiment and that in Example 3 is that the temperature of the second sintering is 320°C.

[0066] Comparative Example 1

[0067] The only difference between the preparation method of the bismuth tellurium selenide alloy target described in this comparative example and Example 1 is that the bismuth tellurium selenide alloy target is subjected to only one hot-pressing sintering. The steps of the one-time hot-pressing sintering are as follows: 500g of bismuth tellurium selenide alloy powder is weighed and placed in a mold, and pressure is applied and heated to the sintering temperature and pressure at the same time. The pressure and heating time is 10min, and sintering is carried out at 180℃ and 18MPa for 80min. After sintering, the target is demolded after cooling to room temperature; the bismuth tellurium selenide alloy target is obtained.

[0068] Comparative Example 2

[0069] The only difference between the preparation method of the bismuth telluride selenide alloy target described in this comparative example and Example 1 is that the bismuth telluride selenide alloy target is subjected to only one hot-pressing sintering. The steps of the one hot-pressing sintering are as follows: 500g of bismuth telluride selenide alloy powder is weighed and placed in a mold, and pressure is applied and heated to the sintering temperature and pressure at the same time. The pressure and heating time is 20min, and sintering is carried out at 360℃ and 15MPa for 70min. After sintering, the target is demolded after cooling to room temperature to obtain the bismuth telluride selenide alloy target.

[0070] Comparative Example 3

[0071] The only difference between the preparation method of the bismuth telluride selenium alloy target described in this comparative example and that in Example 3 is that the temperature of the first sintering is 380°C.

[0072] Comparative Example 4

[0073] The only difference between the preparation method of the bismuth telluride selenium alloy target described in this comparative example and that in Example 3 is that the temperature of the second sintering is 380°C.

[0074] Comparative Example 5

[0075] The only difference between the preparation method of the bismuth telluride selenium alloy target described in this comparative example and that in Example 3 is that the pressure of the second sintering is 18 MPa.

[0076] Comparative Example 6

[0077] This comparative example provides a method for preparing a bismuth tellurium selenide alloy target, comprising the following steps:

[0078] (1) Based on a total feed amount of 1 kg, according to Bi2Te 2.7 Se 0.3 Weigh the ingredients according to the stoichiometric ratio, add them to a high borosilicate glass tube, and seal under vacuum.

[0079] (2) Place the vacuum-sealed high borosilicate glass tube into the swing furnace for full melting. The melting temperature is 700℃. First, preheat for 5 minutes, then swing and melt for 6 minutes. Take it out and shake it evenly. Then put it back into the swing furnace for 2 minutes of refining. Take it out and stand it upright against the iron frame. Gently tap the glass tube wall to remove the bubbles in the melt. After naturally cooling to room temperature, break the glass tube and take out the alloyed n-type bismuth telluride-based alloy ingot.

[0080] (3) The n-type bismuth telluride-based alloy ingot was pulverized and passed through a 325-mesh sieve to obtain n-type bismuth telluride selenide alloy powder; the composition test results of the bismuth telluride selenide alloy powder showed that Bi was 53.01 wt.%, Te was 43.87 wt.%, Se was 3.04 wt.%, and the oxygen content was 0.08%; D 50 It is 18.000 μm;

[0081] (4) Weigh 500g of bismuth tellurium selenide alloy powder and place it in the mold. At the same time, pressurize and heat it to the temperature and pressure of the first sintering. The pressurization and heating time is 10min. The first sintering is carried out at 180℃ and 18MPa for 80min. After the first sintering is completed, the sample is cooled to room temperature and then demolded. When the sample is demolded after the first sintering, the sample cracks in half along the radial direction to obtain fragments.

[0082] The obtained fragments were broken and placed in a mold. At the same time, pressure and temperature were increased to the temperature and pressure for the second sintering. The pressure and temperature increase time was 20 minutes. The second sintering was carried out at 360℃ and 15MPa for 70 minutes. After the second sintering was completed, the material was cooled to room temperature and demolded to obtain the bismuth tellurium selenide alloy target.

[0083] Performance testing:

[0084] The composition, relative density, and grain size of the bismuth tellurium selenide alloy targets obtained in each embodiment and comparative example were tested. The test results are shown in Tables 1-2 and 2-3. Figure 1-3 As shown.

[0085] Table 1. Property test results of bismuth tellurium selenide alloy sputtering targets

[0086]

[0087]

[0088] Table 2. Test results of impurity content in bismuth tellurium selenide alloy sputtering targets.

[0089]

[0090] As can be seen from Table 1, the bismuth tellurium selenide alloy target material prepared in this application has small and uniform grain size, no cracks, and a relative density greater than 99%.

[0091] The experimental data from Example 1 and Comparative Examples 1-2 show that the target material obtained by one sintering has a low relative density. A low sintering temperature in one sintering will lead to the problem of grains not growing properly. If the sintering temperature in one sintering is too high, the grain size of the target material will increase and the relative density will decrease slightly.

[0092] The experimental data from Examples 3, 5-6 and Comparative Example 4 show that the temperature of the first sintering affects the performance of the target material. If the temperature of the first sintering is too high, the target material grains grow larger. When the temperature of the first sintering is 300-360℃, the grain size of the target material is more uniform and the relative density is higher.

[0093] The experimental data from Example 3 and Comparative Example 3 show that the target material shattered when the pressure during the first sintering exceeded the range of the present invention.

[0094] The experimental data from Examples 3, 7-8 and Comparative Examples 5-6 show that the temperature and pressure of the second sintering also affect the performance of the target material. When the temperature of the second sintering is 340-360℃, the grain size of the target material is more uniform and the relative density is higher. However, when the temperature or pressure of the second sintering exceeds the range of this application, the uniformity of the grain size of the obtained target material decreases and the relative density also decreases.

[0095] Figure 1 This is a partial electron microscope scan image of the target material obtained in Example 1. Figure 1 As can be seen, the internal structure of the target material is very uniform, with an average grain size of less than 10 μm.

[0096] Figure 2 This is a scanning electron microscope image of a local fracture surface of the target material obtained in Comparative Example 1. Figure 2 As can be seen from the data, the target material obtained in Comparative Example 1 has a microstructure of elliptical stacked grains, which is relatively loose and has not fully grown into the layered stacked grain morphology of bismuth tellurium alloy.

[0097] Figure 3 Here is a scanning electron microscope image of a local fracture surface of the target material obtained in Comparative Example 2. Figure 3 As can be seen from Comparative Example 2, the grain size of the target material is not uniform, with some grains being larger in size. This indicates that the grains of the target material grow larger during the hot pressing and sintering process, which leads to a decrease in the uniformity of the grain size of the target material.

[0098] Figure 4 Here is a scanning electron microscope image of a local fracture surface of the target material obtained in Comparative Example 6. Figure 4 As can be seen, the grain size of the target material prepared by conventional methods is relatively large.

[0099] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a bismuth tellurium selenide alloy target, characterized in that, Includes the following steps: Preparation of bismuth tellurium selenide alloy powder: raw materials Bi, Te, and Se are mixed in the manner of Bi2Te 3-x Se x The ingredients with x=0.15-0.5 were smelted, and the resulting bismuth tellurium selenide alloy ingots were atomized to obtain bismuth tellurium selenide alloy powder with an average particle size of less than 45μm. Preparation of bismuth tellurium selenide alloy target: Bismuth tellurium selenide alloy powder is placed in a mold and subjected to a first hot pressing sintering to obtain fragmented blocks; The fragmented pieces are broken up and placed in a mold for a second hot-pressing sintering to obtain a bismuth tellurium selenide alloy target. The conditions for the first hot pressing sintering include: a sintering temperature of 180-360℃ and a sintering pressure of 15-20MPa; the conditions for the second hot pressing sintering include: a sintering temperature of 320-360℃ and a sintering pressure of 12-15MPa.

2. The method for preparing the bismuth tellurium selenide alloy target as described in claim 1, characterized in that, The temperature of the first hot pressing sintering is 300-360℃; the temperature of the second hot pressing sintering is 330-350℃.

3. The method for preparing the bismuth tellurium selenide alloy target as described in claim 1, characterized in that, The first hot pressing sintering time is 60-90 minutes, and the second hot pressing sintering time is 50-80 minutes.

4. The method for preparing the bismuth tellurium selenide alloy target as described in claim 1, characterized in that, The heating rate for the first hot pressing sintering is 10-20℃ / min; the heating rate for the second hot pressing sintering is 10-20℃ / min.

5. The method for preparing the bismuth tellurium selenide alloy target as described in claim 1, characterized in that, The pressure increase rate for the first hot pressing sintering is 0.3-1.5 MPa / min; the pressure increase rate for the second hot pressing sintering is 0.3-1.5 MPa / min.

6. The method for preparing the bismuth tellurium selenide alloy target as described in claim 1, characterized in that, The preparation method of the bismuth tellurium selenide alloy powder is as follows: (1) Mix raw materials Bi, Te and Se according to Bi2Te 3-x Se x x=0.15-0.5 The ingredients are added to the glass tube and then vacuum-sealed. (2) The vacuum-sealed glass tube is placed in a swing furnace for melting. After melting, the glass tube is taken out and placed vertically to cool, thus obtaining a bismuth tellurium selenide alloy ingot. (3) Place the bismuth tellurium selenide alloy ingot into the gas atomization equipment, evacuate the atomization chamber, and then introduce atomizing gas to clean the furnace. (4) After the furnace is cleaned, the temperature is raised and smelted. After the bismuth tellurium alloy ingot is completely melted into a melt, it is kept at the temperature for refining. Then the temperature is raised to the atomization temperature, the nozzle is heated, and the atomizing gas is started. When the gas atomization pressure is reached, atomization begins. (5) After atomization, cool to room temperature to obtain n-type bismuth telluride selenium alloy powder.

7. A bismuth tellurium selenide alloy target, characterized in that, The bismuth telluride selenide alloy target is prepared by the method described in any one of claims 1-6.

8. The application of the bismuth telluride selenide alloy target as described in claim 7 in the preparation of bismuth telluride selenide thin films.

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