An n-type and p-type thermoelectric material with the same chemical composition BiSbSe x Te x and its preparation method and application

Abstract

The application belongs to the technical field of thermoelectric materials, and particularly relates to n-type and p-type thermoelectric materials with the same chemical composition BiSbSe 3‑x Te x and a preparation method and application thereof. The application provides a thermoelectric material, which comprises n-type thermoelectric material or p-type thermoelectric material, and a molecular formula of the n-type thermoelectric material or the p-type thermoelectric material is independently BiSbSe 3‑x Te x , and 1<=x<=1.75. The thermoelectric material provided by the application can be made into n-type and p-type thermoelectric materials, and the components of the n-type and p-type thermoelectric materials are the same, and the alloy structures are similar, so that the obstacles encountered by the carriers during transmission can be greatly reduced, and the efficiency of thermoelectric conversion can be significantly improved. Because the thermal expansion coefficients are similar, the stress concentration caused by the difference in thermal expansion coefficients can be effectively reduced, the mechanical properties of the thermoelectric component are improved, and the development and design of the thermoelectric device with excellent performance are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric materials, and particularly relates to n-type and p-type thermoelectric materials with the same chemical composition BiSbSe 3-x Te x and their preparation methods and applications. Background Art

[0002] The research on thermoelectric materials, thermoelectric conversion effects, and application technologies has a long history. Since thermoelectric materials can achieve the mutual conversion between thermal energy and electrical energy, and have the advantages of no noise, no vibration, no pollution, etc., they can greatly improve energy utilization efficiency and reduce environmental pollution. Studying them opens up a new perspective for the development of new energy technologies.

[0003] According to the different carriers transported by thermoelectric materials, they are divided into n-type thermoelectric materials and p-type thermoelectric materials. The n-type and p-type thermoelectric materials can be respectively made into n-type thermocouple arms and p-type thermocouple arms. A π-shaped element composed of an n-type thermocouple arm and a p-type thermocouple arm assembled in a thermally parallel and electrically series manner can form a thermoelectric conversion device. When the structural and compositional differences between the materials of the n-type thermocouple arm and the p-type thermocouple arm are smaller, the values of the power generation efficiency, output power, refrigeration efficiency, and maximum refrigeration capacity of the thermoelectric module composed of them will be larger, that is, the thermoelectric conversion performance will be more excellent. At the same time, the smaller structural and compositional differences can make the materials of the n-type thermocouple arm and the p-type thermocouple arm have more similar thermal expansion coefficients, effectively reducing the stress concentration caused by the difference in thermal expansion coefficients, thereby improving the mechanical properties of the thermoelectric module and providing greater feasibility and flexibility for the design of aspects such as the height, shape, and area of the thermoelectric arms.

[0004] In the prior art, when preparing n-type and p-type thermoelectric materials, most of them generate electrons or holes by substituting and doping elements at different positions of the matrix thermoelectric materials, so that they respectively exhibit n-type and p-type conduction modes. However, the thermoelectric conversion efficiency of the thermoelectric materials prepared by them is mostly low, and the mechanical strength of the thermoelectric modules composed of them is poor. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide n-type and p-type thermoelectric materials with the same chemical composition BiSbSe 3-x Te x and their preparation methods and applications. The thermoelectric materials provided by the present invention can be made into n-type and p-type thermoelectric materials with the same chemical composition, which can reduce the obstacles encountered by carriers during transmission and the stress concentration of the thermoelectric module, and improve the thermoelectric conversion efficiency and mechanical properties.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: [[ID=?]]

[0007] The present invention provides n-type and p-type thermoelectric materials with the same chemical composition BiSbSe 3-x Te x including n-type thermoelectric materials or p-type thermoelectric materials, and the molecular formula of the n-type thermoelectric materials or p-type thermoelectric materials is independently BiSbSe 3-x Te x , where 1 ≤ x ≤ 1.75.

[0008] Preferably, x is 1, 1.25, 1.5, or 1.75.

[0009] The present invention also provides a preparation method for the thermoelectric materials described in the above technical solution, including the following steps:

[0010] Mix Bi单质, Sb单质, Se单质, and Te单质, and after alloying and sintering the obtained mixture in a vacuum environment, pulverize it to obtain alloyed powder;

[0011] Perform hot pressing and sintering on the alloyed powder to obtain n-type thermoelectric materials;

[0012] The pressure for the hot pressing and sintering is 30 - 50 MPa, the temperature is 400 - 450 °C, and the heat preservation time is 1 - 3 h;

[0013] After pre-pressing and forming the alloyed powder, perform sintering to obtain p-type thermoelectric materials;

[0014] The pressure for the pre-pressing and forming is 5 - 10 MPa, and the time is 3 - 5 min;

[0015] The temperature for the sintering is 400 - 450 °C, and the heat preservation time is 6 - 9 h.

[0016] Preferably, the vacuum degree of the vacuum environment < 1.0 × 10 -2 Pa.

[0017] Preferably, the alloying and sintering includes first alloying and sintering and second alloying and sintering carried out in sequence; the temperature for the first alloying and sintering is 300 - 500 °C, and the heat preservation time is 0.5 - 1 h; the temperature for the second alloying and sintering is 700 - 900 °C, and the heat preservation time is 6 - 9 h.

[0018] Preferably, the heating rate for raising the temperature to the first alloying and sintering temperature and the second alloying and sintering temperature is independently 5 - 8 °C / min.

[0019] Preferably, the particle size of the alloyed powder is 1 - 100 μm.

[0020] Preferably, the purity of Bi单质, Sb单质, Se单质, and Te单质 is independently > 99.99%. It should be noted that some of the Chinese terms in the original text seem to be in an incorrect format. I have translated them as they are. If they are supposed to be specific chemical element names in Chinese, they should be corrected for a more accurate translation.

[0021] Preferably, the Bi, Sb, Se, and Te elemental substances are all elemental particles.

[0022] The present invention also provides an application of the thermoelectric material described in the above technical solution or the thermoelectric material prepared by the preparation method described in the above technical solution in a thermoelectric component.

[0023] The present invention provides a thermoelectric material of n-type and p-type with the same chemical composition BiSbSe 3-x Te x , including an n-type thermoelectric material or a p-type thermoelectric material. The molecular formula of the n-type thermoelectric material or the p-type thermoelectric material is independently BiSbSe 3-x Te x , where 1 ≤ x ≤ 1.75. The thermoelectric material provided by the present invention can be made into n-type and p-type thermoelectric materials with the same chemical composition. The results of the examples show that the Seebeck coefficient S of the n-type BiSbSe 3-x Te x thermoelectric material is -135 μV / K -1 ~-161 μV / K -1 , the power factor PF is 554 μW / (m·K) -1 K -2 ~687 μW / (m·K) -1 K -2 , the thermal conductivity κ is 0.68 W / (m·K) -1 K -1 ~0.82 W / (m·K) -1 K -1 , and the Seebeck coefficient S of the p-type BiSbSe 3-x Te x thermoelectric material is 69 μV / K -1 ~257 μV / K -1 , the power factor PF is 16 μW / (m·K) -1 K -2 ~173 μW / (m·K) -1 K -2 , and the thermal conductivity κ is 0.46 W / (m·K) -1 K -1 ~0.70 W / (m·K) -1 K -1 . Because the n-type and p-type thermoelectric materials have the same composition and similar alloy structures, the hindrance encountered by carriers during transmission can be greatly reduced, thereby significantly improving the thermoelectric conversion efficiency. Because they have similar thermal expansion coefficients, the stress concentration caused by the difference in thermal expansion coefficients can be effectively reduced, and the mechanical properties of the thermoelectric component can be improved, providing assistance for the development and design of high-performance thermoelectric devices.

[0024] The present invention provides a preparation method for the above thermoelectric material. By adjusting the conditions of pre-press molding and hot-press sintering, BiSbSe3-x Te x Thermoelectric materials are respectively made into n-type and p-type thermoelectric materials. The preparation method adopted in the present invention is simple, has a short cycle, low production cost, and no toxic and harmful gases are generated during the whole preparation process, reducing environmental pollution and being convenient for use in large-scale production. It has important significance for developing n-type and p-type thermoelectric materials with the same constituent elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD diagrams of the thermoelectric materials obtained in Examples 5 to 8 of the present invention;

[0026] Figure 2 SEM diagrams of the thermoelectric materials obtained in Examples 5 to 8 of the present invention;

[0027] Figure 3 Trend diagrams of the Seebeck coefficient of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0028] Figure 4 Trend diagrams of the electrical conductivity of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0029] Figure 5 Trend diagrams of the power factor of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0030] Figure 6 Trend diagrams of the total thermal conductivity number of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0031] Figure 7 Trend diagrams of the electronic thermal conductivity of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0032] Figure 8 Trend diagrams of the sum of the lattice thermal conductivity and the bipolar thermal conductivity of the thermoelectric materials obtained in Examples 5 and 6 of the present invention with respect to temperature;

[0033] Figure 9 Figure of the dimensionless thermoelectric figure of merit of the thermoelectric materials obtained in Examples 5 and 6 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present invention provides an n-type and a p-type thermoelectric material with the same chemical composition BiSbSe 3-x Te x including the n-type thermoelectric material or the p-type thermoelectric material, and the molecular formula of the n-type thermoelectric material or the p-type thermoelectric material is independently BiSbSe 3-x Te x , where 1 ≤ x ≤ 1.75.

[0035] In the present invention, x is preferably 1, 1.25, 1.5, 1.75, and more preferably 1.5.

[0036] The n-type thermoelectric material and p-type thermoelectric material provided by the present invention have the same chemical composition and similar alloy structures, so the hindrance encountered by carriers during transmission can be greatly reduced, thereby significantly improving the efficiency of thermoelectric conversion. Due to their similar thermal expansion coefficients, the stress concentration caused by the difference in thermal expansion coefficients can be effectively reduced, and the mechanical properties of the thermoelectric component can be improved.

[0037] The present invention also provides a preparation method for the thermoelectric material described in the above technical solution, including the following steps:

[0038] Mix elemental Bi, elemental Sb, elemental Se, and elemental Te, and after alloying and sintering the obtained mixture in a vacuum environment, pulverize it to obtain an alloyed powder;

[0039] Perform hot pressing sintering on the alloyed powder to obtain an n-type thermoelectric material;

[0040] After pre-pressing and forming the alloyed powder, perform sintering to obtain a p-type thermoelectric material.

[0041] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used in the preparation, and commercially available products well-known to those skilled in the art can be used.

[0042] The present invention mixes elemental Bi, elemental Sb, elemental Se, and elemental Te to obtain a mixture.

[0043] In the present invention, the atomic ratio of elemental Bi to elemental Sb is preferably (0.5 - 1):(1 - 1.5), and more preferably 1:1; the atomic ratio of elemental Bi to elemental Se is preferably (0.5 - 1):(1.5 - 2), and more preferably 1:1.5; the atomic ratio of elemental Bi to elemental Te is preferably (0.5 - 1):(1 - 2), and more preferably 1:1.5.

[0044] In the present invention, the purity of elemental Bi, elemental Sb, elemental Se, and elemental Te is preferably > 99.99%; elemental Bi, elemental Sb, elemental Se, and elemental Te are all preferably elemental particles; the particle size of elemental Se particles is preferably 2 - 5 mm; the particle size of elemental Sb particles is preferably 2 - 6 mm; the elemental Sb particles are spherical-like; the particle size of elemental Bi particles is preferably 1 - 6 mm; the elemental Bi particles are irregular; the particle size of elemental Te particles is preferably 1 - 10 mm.

[0045] In the present invention, the mixing is preferably to place elemental Bi, elemental Sb, elemental Se, and elemental Te in a quartz tube, shake it well to make it evenly mixed, and then under a vacuum degree < 1.0×10-2 Under the condition of [[Pa]], a hydrogen flame gun is used for sealing the tube.

[0046] After obtaining the said mixture, the present invention alloy-sinterizes the said mixture in a vacuum environment to obtain an alloy-sinterized product.

[0047] In the present invention, the vacuum degree of the said vacuum environment is preferably < 1.0×10 -2 [[Pa]], more preferably 5.0×10 -3 [[Pa]].

[0048] In the present invention, the said alloy-sinterization preferably includes the first alloy-sinterization and the second alloy-sinterization; the temperature of the first alloy-sinterization is preferably 300 - 500 [[DEG]]C, more preferably 500 [[DEG]]C, and the heat preservation time is preferably 0.5 - 1 h, more preferably 0.5 h; the temperature of the second alloy-sinterization is preferably 700 - 900 [[DEG]]C, more preferably 700 [[DEG]]C, and the heat preservation time is preferably 6 - 9 h, more preferably 6 h;

[0049] In the present invention, the heating rate for rising the temperature to the temperature of the first alloy-sinterization and the second alloy-sinterization is independently preferably 5 - 8 [[DEG]]C / min, more preferably 6 [[DEG]]C / min.

[0050] In the present invention, the equipment for the said alloy-sinterization is preferably a muffle furnace.

[0051] During the alloy-sinterization process, Bi element, Sb element, Se element and Te element form an alloy ingot.

[0052] After obtaining the said alloy-sinterized product, the present invention pulverizes the said alloy-sinterized product to obtain an alloy powder.

[0053] In the embodiments of the present invention, the said pulverization is preferably carried out by crushing with an agate mortar and fully grinding. In the present invention, the particle size of the said alloy powder is preferably 1 - 100 [[mu]]m, more preferably 50 [[mu]]m.

[0054] After obtaining the said alloy powder, the present invention hot-presses and sinterizes the said alloy powder to obtain an n-type thermoelectric material.

[0055] In the present invention, the pressure of the said hot-press sinterization is preferably 30 - 50 MPa, more preferably 50 MPa, the temperature is preferably 400 - 450 [[DEG]]C, more preferably 420 [[DEG]]C, and the heat preservation time is preferably 1 - 3 h, more preferably 1 h.

[0056] After obtaining the said alloy powder, the present invention pre-presses and forms the said alloy powder to obtain a green body.

[0057] In this invention, the pre-compression pressure is preferably 5-10 MPa, more preferably 10 MPa; the pre-compression time is preferably 3-5 min, more preferably 3 min.

[0058] After obtaining the blank, the present invention sinters the blank to obtain a p-type thermoelectric material.

[0059] In this invention, the sintering pressure is preferably 0 MPa, the temperature is preferably 400-450°C, more preferably 420°C, and the holding time is preferably 6-9 h, more preferably 9 h.

[0060] This invention, by adjusting the conditions of pre-pressing and hot-pressing sintering, can produce BiSbSe 3-x Te x Thermoelectric materials are prepared into n-type and p-type thermoelectric materials, respectively. The preparation method used in this invention is simple, has a short cycle, low production cost, and produces no toxic or harmful gases during the entire preparation process, reducing environmental pollution and facilitating use in large-scale production. It is of great significance for the development of n-type and p-type thermoelectric materials with the same constituent elements.

[0061] The present invention also provides the application of the thermoelectric materials described in the above technical solutions or the thermoelectric materials prepared by the preparation methods described in the above technical solutions in thermoelectric components.

[0062] The present invention does not impose any particular limitation on the application of the thermoelectric material in thermoelectric components; any application method known in the art may be used.

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0064] Example 1

[0065] (1) Batching: According to the atomic stoichiometry of BiSbSe2Te, weigh out metal elemental particles Bi, Sb, Se and Te with a purity higher than 99.99% and place them in a quartz tube. Shake thoroughly to mix them evenly, and then place them in a vacuum of 5.0×10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0066] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0067] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0068] (4) Hot pressing sintering: The ingredients are loaded into a graphite mold and hot pressing sintered for 1 hour under a sintering pressure of 50MPa and a temperature of 420℃. The material is then cooled in the furnace to obtain n-type BiSbSe2Te thermoelectric material.

[0069] Example 2

[0070] (1) Batching: According to the atomic stoichiometry of BiSbSe2Te, weigh out metal elemental particles Bi, Sb, Se and Te with a purity higher than 99.99% and place them in a quartz tube. Shake thoroughly to mix them evenly, and then place them in a vacuum of 5.0×10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0071] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0072] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0073] (4) Pre-pressing: The alloyed powder is pressed at 10MPa and held for 3min to obtain a blank;

[0074] (5) Hot pressing sintering: The blank is loaded into a graphite mold and hot pressing sintered for 9 hours under the conditions of sintering pressure of 0MPa and temperature of 420℃. It is then cooled with the furnace to obtain p-type BiSbSe2Te thermoelectric material.

[0075] Example 3

[0076] (1) Ingredients: According to BiSbSe 1.75 Te 1.25 To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0077] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0078] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0079] (4) Hot pressing sintering: The ingredients are loaded into a graphite mold and hot-pressed for 1 hour under a sintering pressure of 50 MPa and a temperature of 420 °C. After cooling in the furnace, n-type BiSbSe is obtained. 1.75 Te 1.25 Thermoelectric materials.

[0080] Example 4

[0081] (1) Ingredients: According to BiSbSe 1.75 Te 1.25 To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0082] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0083] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0084] (4) Pre-pressing: The alloyed powder is pressed at 10MPa and held for 3min to obtain a blank;

[0085] (5) Hot pressing sintering: The green body is placed into a graphite mold and hot-pressed for 9 hours at a sintering pressure of 0 MPa and a temperature of 420°C, followed by furnace cooling to obtain p-type BiSbSe. 1.75 Te 1.25 Thermoelectric materials.

[0086] Example 5

[0087] (1) Ingredients: According to BiSbSe 1.5 Te 1.5 To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0088] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0089] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0090] (4) Hot pressing sintering: The ingredients are loaded into a graphite mold and hot-pressed for 1 hour under a sintering pressure of 50 MPa and a temperature of 420 °C. After cooling in the furnace, n-type BiSbSe is obtained. 1.5 Te 1.5 Thermoelectric materials.

[0091] Example 6

[0092] (1) Ingredients: According to BiSbSe 1.5 Te 1.5 To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0093] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0094] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0095] (4) Pre-pressing: The alloyed powder is pressed at 10MPa and held for 3min to obtain a blank;

[0096] (5) Hot pressing sintering: The green body is placed into a graphite mold and hot-pressed for 9 hours at a sintering pressure of 0 MPa and a temperature of 420°C, followed by furnace cooling to obtain p-type BiSbSe. 1.5 Te 1.5 Thermoelectric materials.

[0097] Example 7

[0098] (1) Ingredients: According to BiSbSe 1.25 Te 1.75To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0099] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0100] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0101] (4) Hot pressing sintering: The ingredients are loaded into a graphite mold and hot-pressed for 1 hour under a sintering pressure of 50 MPa and a temperature of 420 °C. After cooling in the furnace, n-type BiSbSe is obtained. 1.25 Te 1.75 Thermoelectric materials.

[0102] Example 8

[0103] (1) Ingredients: According to BiSbSe 1.25 Te 1.75 To determine the atomic stoichiometry, metallic elemental particles Bi, Sb, Se, and Te, each with a purity higher than 99.99%, were weighed and placed in a quartz tube. After thorough shaking to ensure uniform mixing, the mixture was then subjected to a vacuum of 5.0 × 10⁻⁶. -3 Under the condition of Pa, the tube was sealed using a hydrogen flame gun;

[0104] (2) Alloying sintering: The sealed quartz tube is placed in a muffle furnace for alloying sintering. The temperature is raised to 500°C at a heating rate of 6°C / min and held for 0.5h. Then the temperature is raised to 700°C at a heating rate of 6°C / min and held for 6h. After that, the tube is cooled with the furnace.

[0105] (3) Crushing: The obtained alloyed sintered product is crushed with an agate mortar and ground thoroughly to obtain alloyed powder;

[0106] (4) Pre-pressing: The alloyed powder is pressed at 10MPa and held for 3min to obtain a blank;

[0107] (5) Hot pressing sintering: The green body is placed into a graphite mold and hot-pressed for 9 hours at a sintering pressure of 0 MPa and a temperature of 420°C, followed by furnace cooling to obtain p-type BiSbSe. 1.25 Te 1.75 Thermoelectric materials.

[0108] Performance testing

[0109] (1) XRD tests were performed on the thermoelectric materials obtained in Examples 5-8, and the test results are as follows: Figure 1 As shown, (a) is BiSbSe 1.5 Te 1.5 (b) is BiSbSe 1.25 Te 1.75 .

[0110] Depend on Figure 1 As can be seen, single-phase samples were obtained in all embodiments of the present invention.

[0111] (2) The thermoelectric materials obtained in Examples 5-8 were subjected to SEM testing, and the test results are as follows: Figure 2 As shown, (a) is an n-type BiSbSe 1.5 Te 1.5 (b) is a p-type BiSbSe 1.5 Te 1.5 (c) is an n-type BiSbSe 1.25 Te 1.75 (d) is a p-type BiSbSe 1.25 Te 1.75 .

[0112] Depend on Figure 2 It is understood that no second phase exists in any of the embodiments of the present invention.

[0113] (3) The Seebeck coefficient and conductivity of the thermoelectric materials obtained in Examples 5 and 6 were tested using a Lindsay LSR-3 tester, and the power factor value was calculated according to the formula. The measurement results are as follows: Figures 3 to 5 As shown, where, Figure 3 This shows the Seebeck coefficient of thermoelectric materials as a function of temperature. Figure 4 This shows the trend of electrical conductivity of thermoelectric materials as a function of temperature. Figure 5 This represents the trend of the power factor of thermoelectric materials as a function of temperature.

[0114] Depend on Figures 3 to 5 It can be seen that n-type BiSbSe 3-x Te x The Seebeck coefficient S of the thermoelectric material is -135 μVK. -1 ~-161μVK -1 The power factor PF is 554 μWm. -1 K -2 ~687μWm -1 K -2 The thermal conductivity κ is 0.68 W / m². -1 K -1 ~0.82Wm -1 K-1 p-type BiSbSe 3- x Te x The Seebeck coefficient S of the thermoelectric material is 69 μVK. -1 ~257μVK -1 The power factor PF is 16 μWm -1 K -2 ~173μWm -1 K -2 The thermal conductivity κ is 0.46 W / m². -1 K -1 ~0.70Wm -1 K -1 .

[0115] Depend on Figure 3 It can be seen that the method provided by this invention can successfully prepare n-type and p-type BiSbSe. 1.5 Te 1.5 Thermoelectric materials.

[0116] Depend on Figure 4 It can be seen that n-type BiSbSe 1.5 Te 1.5 Thermoelectric materials have higher electrical conductivity.

[0117] Depend on Figure 5 It can be seen that p-type BiSbSe 1.5 Te 1.5 Although thermoelectric materials have a large Seebeck coefficient, their low electrical conductivity results in a power factor lower than that of n-type BiSbSe over the entire measurement temperature range. 1.5 Te 1.5 Power factor of thermoelectric materials.

[0118] (4) The thermal diffusivity and specific heat of the thermoelectric materials obtained in Examples 5 and 6 were tested using Netzsch LFA457 and Netzsch DSCSTA449F3, respectively. The total thermal conductivity, electronic thermal conductivity, and the sum of lattice thermal conductivity and bipolar thermal conductivity were calculated according to the formula. The measurement results are as follows: Figures 6 to 8 As shown, where Figure 6 This shows the trend of the total thermal conductivity of thermoelectric materials as a function of temperature. Figure 7 This shows the trend of electronic thermal conductivity of thermoelectric materials as a function of temperature. Figure 8 This represents the trend of the sum of the lattice thermal conductivity and the bipolar thermal conductivity of the thermoelectric material as a function of temperature.

[0119] Depend on Figure 6 It can be seen that n-type BiSbSe can be prepared using the method provided by this invention. 1.5 Te 1.5 Thermoelectric materials are more p-type than BiSbSe 1.5Te 1.5 Thermoelectric materials have higher thermal conductivity.

[0120] Depend on Figure 7 It can be seen that, due to the n-type BiSbSe 1.5 Te 1.5 Thermoelectric materials have higher electrical conductivity, resulting in higher electronic thermal conductivity than p-type BiSbSe over the entire measurement temperature range. 1.5 Te 1.5 Electronic thermal conductivity of thermoelectric materials.

[0121] Depend on Figure 8 It can be seen that at high temperatures, n-type and p-type BiSbSe 1.5 Te 1.5 Intrinsic excitations occur in thermoelectric materials, resulting in a bipolar diffusion effect and leading to bipolar thermal conductivity, thus increasing its thermal conductivity at high temperatures. Furthermore, p-type BiSbSe... 1.5 Te 1.5 The intrinsic excitation temperature of thermoelectric materials is lower than that of n-type BiSbSe. 1.5 Te 1.5 The temperature at which thermoelectric materials generate intrinsic excitation.

[0122] (5) The dimensionless thermoelectric figure of merit of the thermoelectric materials obtained in Examples 5 and 6 were calculated, and the results are as follows: Figure 9 As shown.

[0123] Depend on Figure 9 It can be seen that, within the measurement temperature range, n-type BiSbSe 1.5 Te 1.5 Thermoelectric materials exhibit higher dimensionless thermoelectric figures of merit. Furthermore, due to the influence of intrinsic excitation, the dimensionless thermoelectric figure of merit shows a trend of first increasing and then decreasing with temperature. The temperatures at which each material reaches its maximum dimensionless thermoelectric figure of merit are as follows: n-type BiSbSe 1.5 Te 1.5 The thermoelectric material reaches its maximum dimensionless thermoelectric figure of merit of 0.45 at 475 K; p-type BiSbSe 1.5 Te 1.5 The thermoelectric material achieves its maximum dimensionless thermoelectric figure of merit of 0.14 at 375 K. The results demonstrate that BiSbSe with thermoelectric properties can be successfully prepared simultaneously using this invention. 3-x Te x n-type and p-type thermoelectric materials.

[0124] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing an n-type thermoelectric material, characterized in that, Includes the following steps: Bi, Sb, Se and Te were mixed, and the resulting mixture was alloyed and sintered in a vacuum environment. The mixture was then pulverized to obtain alloyed powder. The alloyed powder is hot-pressed and sintered to obtain an n-type thermoelectric material. The molecular formula of the n-type thermoelectric material is BiSbSe. 3-x Te x , 1≤x≤1.75; The hot pressing sintering pressure is 30~50MPa, the temperature is 400~450℃, and the holding time is 1~3h.

2. A method for preparing a p-type thermoelectric material, characterized in that, Includes the following steps: Bi, Sb, Se and Te were mixed, and the resulting mixture was alloyed and sintered in a vacuum environment. The mixture was then pulverized to obtain alloyed powder. The alloyed powder is pre-pressed and then sintered to obtain a p-type thermoelectric material; the molecular formula of the p-type thermoelectric material is BiSbSe. 3-x Te x , 1≤x≤1.75; The pre-compression molding pressure is 5~10MPa, and the time is 3~5min; The sintering temperature is 400~450℃, and the holding time is 6~9h.

3. The preparation method according to claim 1 or 2, characterized in that, The x values ​​are 1, 1.25, 1.5, and 1.

75.

4. The preparation method according to claim 1 or 2, characterized in that, The vacuum level of the vacuum environment is <1.0×10⁻⁶. -2 Pa.

5. The preparation method according to claim 1 or 2, characterized in that, The alloying sintering includes a first alloying sintering and a second alloying sintering performed sequentially; the temperature of the first alloying sintering is 300~500℃ and the holding time is 0.5~1h; the temperature of the second alloying sintering is 700~900℃ and the holding time is 6~9h.

6. The preparation method according to claim 5, characterized in that, The heating rate to the first alloying sintering temperature and the second alloying sintering temperature is independently 5~8℃ / min.

7. The preparation method according to claim 1 or 2, characterized in that, The particle size of the alloyed powder is 1~100μm.

8. The preparation method according to claim 1 or 2, characterized in that, The purity of the Bi, Sb, Se, and Te elements is independently >99.99%.

9. The preparation method according to claim 1 or 2, characterized in that, The Bi, Sb, Se, and Te elements are all elemental particles.

10. The application of the n-type thermoelectric material prepared by the preparation method according to any one of claims 1, 3 to 9 or the p-type thermoelectric material prepared by the preparation method according to any one of claims 2 to 9 in a thermoelectric assembly.

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