Bi2S3 thermoelectric material and preparation method thereof
Through the cyclic processing of cold pressing and vacuum sintering, the problems of time and energy consumption and purity control in the preparation of Bi2S3 thermoelectric materials were solved, and the efficient preparation of high-performance Bi2S3 thermoelectric materials was achieved, thereby improving their thermoelectric performance.
Patent Information
- Application Number
- CN202510901772.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-10-03
AI Technical Summary
The preparation process of existing Bi2S3 thermoelectric materials is time-consuming and energy-consuming. Traditional methods use toxic solvents or have high equipment requirements, making it difficult to precisely control the chemical composition, which affects its electrical properties.
Bi2S3 thermoelectric material was prepared by adopting a cyclic processing method of cold pressing and vacuum sintering. The grinding, cold pressing and vacuum sintering were repeated many times. The vacuum sintering parameters were adjusted to promote solid phase reaction and grain growth and avoid oxidation reaction.
Significantly improve the thermoelectric properties of Bi2S3 bulk thermoelectric materials, reduce thermal conductivity, increase material purity and density, improve electrical properties, and obtain high ZT value and power factor.
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Figure CN120736902A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of thermoelectric materials, and in particular to a Bi2S3 thermoelectric material and a preparation method thereof. Background Art
[0002] Thermoelectric materials can realize the direct conversion between thermal energy and electrical energy. Thermoelectric devices created from thermoelectric materials have the advantages of small size, light weight, pollution-free and maintenance-free. They have broad application prospects in the fields of thermoelectric power generation and solid-state refrigeration.
[0003] Bi2Te3 and its alloys are the best-performing thermoelectric materials at room temperature and have achieved commercial application. However, the toxicity and high cost of Te limit their large-scale application. Furthermore, some traditional high-performance thermoelectric materials, such as PbX (where X is S, Se, and Te), contain the toxic element Pb, while materials such as Skutterudite, Half-Heusler, and SiGe contain rare and expensive elements, all of which restrict their wider application.
[0004] Bi2S3, a Group V-VI narrowband semiconductor with a similar lamellar crystal structure to Bi2Te3, offers significant potential for enhanced thermoelectric performance. Furthermore, Bi2S3 offers advantages such as low cost, low toxicity, and environmental friendliness, making it a promising alternative to traditional thermoelectric materials.
[0005] Currently, Bi2S3 is mainly prepared through smelting, hydrothermal / solvothermal, spark plasma sintering and other methods. The preparation process is time-consuming and energy-consuming, and the hydrothermal / solvothermal method requires the use of toxic solvents. The smelting method cannot accurately control the chemical composition of the sample, and the spark plasma sintering equipment has high requirements. Summary of the Invention
[0006] Based on the above description, the present invention provides a Bi2S3 thermoelectric material and a preparation method thereof to solve the problem of how to simplify the Bi2S3 preparation process while improving the electrical properties of Bi2S3.
[0007] The technical solution of the present invention to solve the above technical problems is as follows: The present invention provides a method for preparing a Bi2S3 thermoelectric material, comprising the following steps: S1. Obtain Bi powder and S powder, mix the Bi powder and S powder to obtain a mixed powder; S2. The mixed powder is cold pressed to obtain a blank; S3. The blank is vacuum sintered to obtain a block; S4. Grinding, cold pressing, and vacuum sintering the block to obtain Bi2S3 thermoelectric material.
[0008] Furthermore, step S4 is repeated 2 to 3 times.
[0009] Furthermore, in step S1, the purity of the Bi powder is not less than 99.99% and the particle size is 50 nm; The purity of S powder is not less than 99.95% and the particle size is 200 nm.
[0010] Furthermore, in step S2, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min; and / or, In step S4, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min.
[0011] Furthermore, in step S3, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min; and / or, In step S4, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min.
[0012] Furthermore, in step S4, the grinding is carried out in a vacuum environment with a vacuum degree less than 5 MPa.
[0013] The present invention also provides a Bi2S3 thermoelectric material, including the Bi2S3 thermoelectric material prepared according to the above-mentioned preparation method of the Bi2S3 thermoelectric material.
[0014] Furthermore, the ZT value of the Bi2S3 thermoelectric material is 1.35@723K.
[0015] Furthermore, the power factor of the Bi2S3 thermoelectric material is 749 μWm -1 K -2 @723K.
[0016] Furthermore, the thermal conductivity of the Bi2S3 thermoelectric material is 0.4 Wm -1 K -1 @723K.
[0017] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: 1. The present invention combines cold pressing with vacuum sintering. Through the cyclic processing of cold pressing molding and vacuum sintering, Bi powder and S powder can be synthesized into Bi2S3, and the electrical properties of Bi2S3 are synergistically improved, its thermal conductivity is reduced, and the thermoelectric performance of Bi2S3 bulk thermoelectric material is significantly improved.
[0018] 2. By adjusting the parameters of vacuum sintering, the solid-phase reaction between Bi and S can be completed, further promoting grain growth and structural densification without causing significant grain coarsening or decomposition. By sintering in a vacuum environment of less than 5 MPa, oxygen and other gases can be effectively excluded, avoiding the oxidation reaction of Bi2S3 at high temperatures and significantly reducing the generation of impurities.
[0019] 3. By repeatedly grinding, cold pressing, and vacuum sintering, the pores and defects inside the material are effectively eliminated, so that the final Bi2S3 thermoelectric material has a higher density and more uniform composition distribution, which can further improve the thermoelectric performance of the thermoelectric material. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 XRD patterns of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention; Figure 2 Graph showing the relationship between the electrical conductivity and the test temperature of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention; Figure 3 Graph showing the relationship between the Seebeck coefficient and the test temperature of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention; Figure 4 Graph showing the relationship between the power factor and the test temperature of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention; Figure 5 Graph showing the relationship between thermal conductivity and test temperature of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention; Figure 6 Graph showing the relationship between the ZT value and the test temperature of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 of the present invention. DETAILED DESCRIPTION
[0021] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.
[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.
[0023] Currently, Bi2S3 is mainly prepared through smelting, hydrothermal / solvothermal, spark plasma sintering and other methods. The preparation process is time-consuming and energy-consuming, and the hydrothermal / solvothermal method requires the use of toxic solvents. The smelting method cannot accurately control the chemical composition of the sample, and the spark plasma sintering equipment has high requirements.
[0024] In view of this, the present invention provides a method for preparing a Bi2S3 thermoelectric material, comprising the following steps: S1. Obtain Bi powder and S powder, mix the Bi powder and S powder to obtain a mixed powder; S2. The mixed powder is cold pressed to obtain a blank; S3. The blank is vacuum sintered to obtain a block; S4. Grinding, cold pressing, and vacuum sintering the block to obtain Bi2S3 thermoelectric material.
[0025] In the technical solution of the present invention, Bi powder and S powder can be synthesized into Bi2S3 through the cyclic processing of cold pressing and vacuum sintering, and the electrical properties of Bi2S3 can be synergistically improved, its thermal conductivity can be reduced, and the thermoelectric properties of Bi2S3 bulk thermoelectric materials can be significantly improved; by sintering in a vacuum environment, the generation of oxidation by-products or other impurity phases can be suppressed, thereby improving the purity and stability of the material.
[0026] Specifically, in some embodiments of the present invention, the molar ratio of Bi powder to S powder is 2:3, which prevents incompletely reacted reactants from affecting the purity of the Bi2S3 thermoelectric material and further improves the purity and stability of the material.
[0027] Furthermore, step S4 is repeated 2 to 3 times.
[0028] In the technical solution of the present invention, by repeating step S4 (grinding, cold pressing, vacuum sintering) 2 to 3 times, the pores and defects inside the material are effectively eliminated, so that the final obtained Bi2S3 thermoelectric material has a higher density and a more uniform composition distribution, which can further improve the thermoelectric performance of the thermoelectric material.
[0029] Furthermore, in step S1, the purity of the Bi powder is not less than 99.99% and the particle size is 50 nm; The purity of S powder is not less than 99.95% and the particle size is 200 nm.
[0030] In the technical solution of the present invention, by adopting high-purity Bi powder and S powder, the introduction of impurity elements can be significantly reduced, the generation of by-products can be reduced, the purity of Bi2S3 thermoelectric materials can be improved, and the thermoelectric properties of thermoelectric materials can be further improved; by adopting nano-scale Bi powder and S powder, it helps to accelerate the solid-phase reaction rate in the subsequent sintering process, promote the full reaction of Bi and S to generate Bi2S3, improve the phase formation efficiency, and shorten the sintering time.
[0031] Furthermore, in step S2, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min; and / or, In step S4, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min.
[0032] In the technical solution of the present invention, by adjusting the parameters of cold pressing, the block or blank obtained after each cold pressing has good mechanical strength, providing a solid foundation for subsequent vacuum sintering; cold pressing is carried out within a pressure range of 10 to 30 MPa, which can ensure close contact between powder particles without causing particle breakage or undesirable crystal transformation due to excessive pressure; controlling the temperature at 20 to 30°C and operating under conditions close to room temperature is conducive to maintaining the original physical and chemical properties of the powder raw materials and avoiding oxidation or other side reactions that may occur at high temperatures; the cold pressing time of 5 to 15 minutes is sufficient for the powder particles to fully deform and fill the gaps, while not excessively extending the processing time, thereby improving production efficiency.
[0033] Furthermore, in step S3, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min; and / or, In step S4, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min.
[0034] In the technical solution of the present invention, by adjusting the parameters of vacuum sintering, the solid-phase reaction between Bi and S can be completed, and grain growth and structural densification can be further promoted without causing obvious grain coarsening or decomposition; by sintering in an environment with a vacuum degree of less than 5 MPa, oxygen and other gases can be effectively excluded, avoiding the oxidation reaction of Bi2S3 at high temperature, and significantly reducing the generation of impurities.
[0035] Furthermore, in step S4, the grinding is carried out in a vacuum environment with a vacuum degree less than 5 MPa.
[0036] In the technical solution of the present invention, by grinding in a vacuum environment, unnecessary chemical changes of Bi and S elements due to contact with air during the grinding process are prevented, thereby ensuring the stability and consistency of the material composition; and grinding in an oxygen-free environment helps to maintain or refine the grain size, so as to facilitate the control of the grain size and distribution of the final product. Small and evenly distributed grains help to improve the thermoelectric properties of the material.
[0037] The present invention also provides a Bi2S3 thermoelectric material, including the Bi2S3 thermoelectric material prepared according to the above-mentioned preparation method of the Bi2S3 thermoelectric material.
[0038] Since the present Bi2S3 thermoelectric material adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described one by one here.
[0039] Furthermore, the ZT value of the Bi2S3 thermoelectric material is 1.35@723K.
[0040] Furthermore, the power factor of the Bi2S3 thermoelectric material is 749 μWm -1 K -2 @723K.
[0041] Furthermore, the thermal conductivity of the Bi2S3 thermoelectric material is 0.4 Wm -1 K -1 @723K.
[0042] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.
[0043] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.
[0044] Example 1 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 400 ° C, and sintering time is 20 min to obtain a block sample; (4) The bulk sample obtained in (3) was crushed and ground in an agate mortar for 30 min, then cold pressed into shape. The blank was then sintered in a vacuum tube furnace using the same sintering process as in (3); (5) Repeat step (4) twice to obtain Bi2S3 bulk thermoelectric material.
[0045] Example 2 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 300 ° C, and sintering time is 20 min to obtain a block sample; (4) The bulk sample obtained in (3) was crushed and ground in an agate mortar for 30 min, then cold pressed into shape. The blank was then sintered in a vacuum tube furnace using the same sintering process as in (3); (5) Repeat step (4) twice to obtain Bi2S3 bulk thermoelectric material.
[0046] Example 3 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 200 ° C, and sintering time is 20 min to obtain a block sample; (4) The block sample obtained in (3) was crushed and ground in an agate mortar for 30 min, then cold pressed into shape. The blank was then sintered in a vacuum tube furnace. The sintering process was the same as in (3); (5) Repeat step (4) twice to obtain Bi2S3 bulk thermoelectric material.
[0047] Example 4 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 400 ° C, and sintering time is 10 min to obtain a block sample; (4) The bulk sample obtained in (3) was crushed and ground in an agate mortar for 30 min, then cold pressed into shape. The blank was then sintered in a vacuum tube furnace using the same sintering process as in (3); (5) Repeat step (4) twice to obtain Bi2S3 bulk thermoelectric material.
[0048] Example 5 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 400 ° C, and sintering time is 20 min to obtain a block sample; (4) The bulk sample obtained in (3) was crushed and ground with an agate mortar for 30 min, then cold pressed into shape. The blank was then sintered in a vacuum tube furnace. The sintering process was the same as in (3), and Bi2S3 bulk thermoelectric material was obtained.
[0049] Example 6 The Bi2S3 bulk thermoelectric material provided in this embodiment is prepared by the following method: (1) Weigh 16.2643 g of Bi powder and 3.7357 g of S powder and grind them in an agate mortar in a vacuum glove box for 30 min to obtain a uniformly mixed initial powder; (2) Pour the mixed powder into the alloy mold and cold press it. The cold pressing pressure is set to 20 MPa and the pressure is maintained for 10 minutes to obtain a blank. (3) The above blank is placed in a vacuum tube furnace for sintering. The sintering process is as follows: vacuum degree is less than 5 MPa, sintering temperature is 400 ° C, and sintering time is 20 min, thereby obtaining Bi2S3 bulk thermoelectric material.
[0050] The phase composition and performance of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 were tested.
[0051] Figure 1 The XRD patterns of the Bi2S3 bulk thermoelectric materials prepared in Examples 1-6 closely match those of the standard Bi2S3 spectra. This indicates that pure Bi2S3 bulk thermoelectric materials were prepared in Examples 1-6. This demonstrates that a single vacuum sintering step allows for a full reaction between the nano-Bi and nano-S powders.
[0052] Figure 2 Figure 2 shows the relationship between the electrical conductivity and test temperature for the Bi2S3 bulk thermoelectric materials prepared in Examples 1-6. The Bi2S3 prepared in Examples 1-4 all exhibit semi-metallic electrical conductivity. However, the electrical conductivity of the Bi2S3 prepared in Examples 5 and 6 decreases with increasing test temperature from room temperature to 673 K, reaching a minimum at 673 K before increasing with increasing temperature.
[0053] Figure 3 Figure 2 shows the relationship between the Seebeck coefficient and test temperature for the Bi2S3 bulk thermoelectric materials prepared in Examples 1-6. The absolute values of the Seebeck coefficients for the Bi2S3 prepared in Examples 1-4 increase with increasing test temperature within the test temperature range. For the Bi2S3 prepared in Examples 5-6, the absolute values of the Seebeck coefficients increase with increasing test temperature over the test temperature range from room temperature to 673 K, reaching a maximum at 673 K and then decreasing with increasing test temperature.
[0054] Figure 4 Figure 2 shows the relationship between the power factor and test temperature for the Bi2S3 bulk thermoelectric materials prepared in Examples 1-6. The power factor of the samples prepared in Examples 1-6 shows a similar dependence on test temperature. The power factor of the Bi2S3 prepared in Examples 1-4 is higher than that of Examples 5 and 6 at the same test temperature. The maximum power factor of 749 μW m-1 K-2 at 723 K is achieved in the Bi2S3 prepared in Example 1.
[0055] Figure 5The thermal conductivity of the Bi2S3 bulk thermoelectric materials prepared in Examples 1-6 is plotted as a function of test temperature. The thermal conductivity of the Bi2S3 prepared in Examples 1-6 shows roughly the same dependence on test temperature. At the same test temperature, the thermal conductivity of the Bi2S3 prepared in Examples 1-6 increases sequentially. The minimum thermal conductivity of 0.4 at 723 K is achieved in the Bi2S3 prepared in Example 1.
[0056] Figure 6 The figure shows the relationship between the ZT values of the Bi2S3 bulk thermoelectric materials prepared in Examples 1 to 6 and the test temperature. The ZT values of the Bi2S3 prepared in Examples 1 to 4 are higher than those of the Bi2S3 prepared in Examples 5 and 6 across the entire test temperature range. This demonstrates that the thermoelectric performance of Bi2S3 bulk thermoelectric materials can be significantly improved by combining repeated grinding and vacuum sintering. The maximum ZT value of 1.35 at 723K was achieved in the Bi2S3 sample prepared in Example 1.
[0057] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
[0058] In summary, the technical solution of this application has the following beneficial technical effects: 1. The present invention combines cold pressing with vacuum sintering. Through the cyclic processing of cold pressing molding and vacuum sintering, Bi powder and S powder can be synthesized into Bi2S3, and the electrical properties of Bi2S3 are synergistically improved, its thermal conductivity is reduced, and the thermoelectric performance of Bi2S3 bulk thermoelectric material is significantly improved.
[0059] 2. By adjusting the parameters of vacuum sintering, the solid-phase reaction between Bi and S can be completed, further promoting grain growth and structural densification without causing significant grain coarsening or decomposition. By sintering in a vacuum environment of less than 5 MPa, oxygen and other gases can be effectively excluded, avoiding the oxidation reaction of Bi2S3 at high temperatures and significantly reducing the generation of impurities.
[0060] 3. By repeatedly grinding, cold pressing, and vacuum sintering, the pores and defects inside the material are effectively eliminated, so that the final Bi2S3 thermoelectric material has a higher density and more uniform composition distribution, which can further improve the thermoelectric performance of the thermoelectric material.
Claims
1. A method for preparing Bi2S3 thermoelectric material, characterized in that: The following steps are involved: S1. Obtain Bi powder and S powder, mix the Bi powder and S powder to obtain a mixed powder; S2. The mixed powder is cold pressed to obtain a blank; S3. The blank is vacuum sintered to obtain a block; S4. Grinding, cold pressing, and vacuum sintering the block to obtain Bi2S3 thermoelectric material.
2. The method for preparing the Bi2S3 thermoelectric material according to claim 1, characterized in that: Step S4 is repeated 2 to 3 times.
3. The method for preparing the Bi2S3 thermoelectric material according to claim 1, characterized in that: In step S1, the purity of the Bi powder is not less than 99.99% and the particle size is 50 nm; The purity of S powder is not less than 99.95% and the particle size is 200 nm.
4. The method for preparing the Bi2S3 thermoelectric material according to claim 1, characterized in that: In step S2, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min; and / or, In step S4, the cold pressing pressure is 10-30 MPa, the cold pressing temperature is 20-30° C., and the cold pressing time is 5-15 min.
5. The method for preparing the Bi2S3 thermoelectric material according to claim 1, characterized in that: In step S3, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min; and / or, In step S4, the vacuum degree of vacuum sintering is less than 5 MPa, the temperature of vacuum sintering is 200-400° C., and the time of vacuum sintering is 10-30 min.
6. The method for preparing the Bi2S3 thermoelectric material according to claim 1, characterized in that: In step S4, the grinding is carried out in a vacuum environment with a vacuum degree of less than 5 MPa.
7. A Bi2S3 thermoelectric material, characterized in that It includes the Bi2S3 thermoelectric material prepared by the preparation method of Bi2S3 thermoelectric material according to any one of claims 1 to 6.
8. The Bi2S3 thermoelectric material according to claim 7, characterized in that The ZT value of the Bi2S3 thermoelectric material is 1.35@723K.
9. The Bi2S3 thermoelectric material according to claim 7, characterized in that The power factor of the Bi2S3 thermoelectric material is 749 μWm -1 K -2 @723K.
10. The Bi2S3 thermoelectric material according to claim 7, characterized in that The thermal conductivity of the Bi2S3 thermoelectric material is 0.4 Wm -1 K -1 @723K.