Thermoelectric material with n-type conductive type and p-type conductive type in different regions and preparation method and application thereof

Abstract

The invention belongs to the technical field of thermoelectric materials, and provides a thermoelectric material with n-type and p-type conductive types in different regions and a preparation method and application thereof.The preparation method comprises the steps that according to the composition of a BiySb2-ySe3-xTex thermoelectric material, a Bi elementary substance, an Sb elementary substance, an Se elementary substance and a Te elementary substance are mixed and subjected to alloying sintering, and alloyed powder is obtained; and forming and sintering the alloyed powder in sequence to obtain the thermoelectric material with n-type and p-type conductive types in different regions respectively. According to the thermoelectric material preparation method provided by the invention, n-type and p-type thermoelectric materials with the same chemical components can be simultaneously prepared in different areas of the same block material, and a thermoelectric element with a specified shape can be directly obtained after the block material is processed; hindrance encountered by carriers during transmission and stress concentration of a thermoelectric assembly can be effectively reduced, and thermoelectric conversion efficiency and mechanical performance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric materials, and in particular to a thermoelectric material having n-type and p-type conductivity types in different regions thereof, and a preparation method and application thereof. Background Art

[0002] Research on thermoelectric materials, the thermoelectric conversion effect, and applied technologies is of paramount importance. Thermoelectric materials can directly convert heat into electricity and vice versa. They can be used to create zero-emission, highly reliable, stable, and long-life thermoelectric power generation devices, as well as compact, fast-acting, refrigerant-free, and precise temperature control thermoelectric cooling devices. Research into these materials can significantly improve energy efficiency and reduce environmental pollution.

[0003] Thermoelectric materials can be divided into two main categories, p-type and n-type, based on the type of charge carriers they transport. P-type and n-type thermoelectric materials can be fabricated into thermoelectric arms to form π-shaped, Y-shaped, or ring-shaped thermoelectric elements. These elements can be connected in parallel thermally and in series electrically to form thermoelectric conversion devices. Differences in composition and crystal structure between p-type and n-type thermoelectric materials, as well as interfacial effects created by barrier layers during thermoelectric device assembly, can hinder carrier transport, significantly reducing the device's conversion efficiency, response speed, cooling efficiency, and accuracy. Furthermore, the p-type and n-type thermoelectric materials, interconnect materials, and barrier layer materials that comprise thermoelectric devices often exhibit significant differences in thermal expansion coefficients. This can lead to stress concentrations within the device, significantly reducing the mechanical properties of the thermoelectric assembly and potentially causing damage or failure. This also severely limits the height, shape, and area of the thermoelectric arms, hindering the widespread commercialization and application of thermoelectric devices.

[0004] Existing technologies typically create n-type and p-type thermoelectric materials by substitutionally doping elements at different locations in a base material to generate electrons or holes, respectively. Furthermore, n-type and p-type thermoelectric materials cannot be simultaneously produced from the same material. Consequently, the resulting n-type and p-type thermoelectric materials typically exhibit low conversion efficiency and poor mechanical strength when used to construct thermoelectric devices. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems in the prior art and provide a thermoelectric material having n-type and p-type conductivity types in different regions, a preparation method and application thereof.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a thermoelectric material having n-type and p-type conductivity types in different regions, comprising the following steps:

[0008] (1) According to Biy Sb 2-y Se 3-x Te x The composition of the thermoelectric material is to mix Bi, Sb, Se and Te, perform alloying and sintering, and obtain alloy powder;

[0009] (2) The alloyed powder is sequentially molded and sintered to obtain a thermoelectric material in which the different regions have n-type and p-type conductivity types, respectively.

[0010] As a preference, Bi y Sb 2-y Se 3-x Te x In thermoelectric materials, the value of x is 0.25 to 1.75, and the value of y is 0.5 to 1.75.

[0011] Preferably, the vacuum degree of the alloying sintering in step (1) is ≤1.0×10 -3 Pa.

[0012] Preferably, the alloying sintering in step (1) is a first alloying sintering, a second alloying sintering and a third alloying sintering performed sequentially;

[0013] The temperature of the first alloying sintering is 200-300° C., the holding time is 0.5-1 hour, and the heating rate to the first alloying sintering temperature is 5-8° C. / min.

[0014] Preferably, the temperature of the second alloying and sintering is 300-500° C., the holding time is 0.5-1 h, and the heating rate from the first alloying and sintering temperature to the second alloying and sintering temperature is 5-8° C. / min.

[0015] Preferably, the temperature of the third alloying and sintering is 700-900° C., the holding time is 6-10 h, and the heating rate from the second alloying and sintering temperature to the third alloying and sintering temperature is 5-8° C. / min.

[0016] Preferably, the particle size of the alloyed powder in step (1) is 1 to 100 μm;

[0017] The molding pressure in step (2) is 5 to 20 MPa, and the holding time is 5 to 10 minutes.

[0018] Preferably, the sintering pressure in step (2) is 0-30 MPa, the temperature is 400-450° C., and the time is 3-6 h.

[0019] The present invention also provides a method for preparing the thermoelectric material having n-type and p-type conductivity types in different regions, and the prepared thermoelectric material having n-type and p-type conductivity types in different regions.

[0020] The present invention also provides the use of the thermoelectric material having n-type and p-type conductivity in different regions in a thermoelectric component.

[0021] The present invention provides a method for preparing a thermoelectric material having n-type and p-type conductivity types in different regions, comprising the following steps: (1) y Sb 2-y Se 3-x Te x The composition of the thermoelectric material is as follows: Bi, Sb, Se and Te are mixed and alloyed and sintered to obtain an alloyed powder; (2) the alloyed powder is sequentially molded and sintered to obtain a thermoelectric material in which different regions have n-type and p-type conductivity types, respectively.

[0022] The thermoelectric material preparation method provided by the present invention can simultaneously prepare n-type and p-type thermoelectric materials with the same chemical composition in different regions of the same bulk material, and can directly obtain thermoelectric elements of a specified shape after processing the bulk material, which can effectively reduce the obstacles encountered by carriers during transmission and the stress concentration of thermoelectric components, thereby improving the efficiency and mechanical properties of thermoelectric conversion.

[0023] The method for preparing thermoelectric materials provided by the present invention can simultaneously obtain n-type and p-type thermoelectric materials in different regions of the same bulk material. y Sb 2-y Se 3-x Te x The Seebeck coefficient S in the n-type region is -131μV / K to -150μV / K, and the Seebeck coefficient S in the p-type region is 200μV / K to 220μV / K. Because both n-type and p-type thermoelectric materials are obtained from the same bulk material, they have the same chemical composition and similar alloy structure, and can be directly processed into thermoelectric elements of the required shape, size and specifications. This will greatly reduce the obstacles encountered by carriers during transmission, thereby significantly improving the efficiency of thermoelectric conversion. It can also effectively reduce the stress concentration caused by differences in thermal expansion coefficients, improve the mechanical properties of thermoelectric components, and provide support for the development and design of thermoelectric devices with excellent performance.

[0024] The present invention provides a method for preparing the above-mentioned thermoelectric material. The present invention can adjust the conditions of pre-pressing and hot pressing sintering to obtain the same block material Bi y Sb 2-y Se 3-x Te xThe preparation method employed in the present invention has the advantages of simple process, short preparation cycle, low production cost, no generation of toxic and harmful gases during the entire preparation process, reduced environmental pollution, and ease of use in large-scale production. It is of great significance for the development of p-type and n-type thermoelectric materials with the same chemical composition and similar alloy structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD test pattern of the thermoelectric material of Example 9;

[0026] Figure 2 This is a SEM test image of the thermoelectric material of Example 9;

[0027] Figure 3 This is the EPMA test diagram of the thermoelectric material in Example 9. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a thermoelectric material having n-type and p-type conductivity types in different regions, comprising the following steps:

[0029] (1) According to Bi y Sb 2-y Se 3-x Te x The composition of the thermoelectric material is to mix Bi, Sb, Se and Te, perform alloying and sintering, and obtain alloy powder;

[0030] (2) The alloyed powder is sequentially molded and sintered to obtain a thermoelectric material in which the different regions have n-type and p-type conductivity types, respectively.

[0031] In the present invention, Bi y Sb 2-y Se 3-x Te x In the thermoelectric material, the value of x is preferably 0.25 to 1.75, more preferably 0.75, 1, 1.25, or 1.5; the value of y is preferably 0.5 to 1.75, more preferably 0.75, 1, 1.25, or 1.5.

[0032] In the present invention, the particle size of the Bi element is preferably 1 to 6 mm, more preferably 2 to 5 mm, and more preferably 3 to 4 mm; the particle size of the Sb element is preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and more preferably 3 to 4 mm; the particle size of the Se element is preferably 2 to 5 mm, more preferably 2.5 to 4.5 mm, and more preferably 3 to 4 mm; the particle size of the Te element is preferably 1 to 10 mm, more preferably 2 to 8 mm, and more preferably 4 to 6 mm.

[0033] In the present invention, the vacuum degree of the alloying sintering in step (1) is preferably ≤1.0×10 -3 Pa, more preferably ≤0.8×10 -3 Pa, more preferably ≤0.2×10 -3 Pa.

[0034] In the present invention, the alloying sintering in step (1) is a first alloying sintering, a second alloying sintering and a third alloying sintering performed sequentially.

[0035] In the present invention, the temperature of the first alloying sintering is preferably 200-300°C, more preferably 220-280°C, and more preferably 240-260°C; the holding time is preferably 0.5-1h, more preferably 0.6-0.9h, and more preferably 0.7-0.8h; the heating rate to the first alloying sintering temperature is preferably 5-8°C / min, more preferably 5.5-7.5°C / min, and more preferably 6-7°C / min.

[0036] In the present invention, the temperature of the second alloying sintering is preferably 300-500°C, more preferably 350-450°C, and more preferably 380-420°C; the holding time is preferably 0.5-1h, more preferably 0.6-0.9h, and more preferably 0.7-0.8h; the heating rate from the first alloying sintering temperature to the second alloying sintering temperature is preferably 5-8°C / min, more preferably 5.5-7.5°C / min, and more preferably 6-7°C / min.

[0037] In the present invention, the temperature of the first alloying and sintering is different from the temperature of the second alloying and sintering.

[0038] In the present invention, the temperature of the third alloying sintering is preferably 700-900°C, more preferably 750-850°C, and more preferably 780-820°C; the holding time is preferably 6-10h, more preferably 7-9h, and more preferably 7.5-8h; the heating rate from the second alloying sintering temperature to the third alloying sintering temperature is preferably 5-8°C / min, more preferably 5.5-7.5°C / min, and more preferably 6-7°C / min.

[0039] In the present invention, Bi, Sb, Se and Te are formed into alloy ingots through the alloying sintering process in step (1), and the alloy ingots are ground and crushed to obtain alloyed powders.

[0040] In the present invention, the particle size of the alloyed powder in step (1) is preferably 1 to 100 μm, more preferably 20 to 80 μm, and even more preferably 40 to 60 μm.

[0041] In the present invention, the molding pressure in step (2) is preferably 5-20 MPa, more preferably 10-15 MPa, more preferably 12-13 MPa; the holding time is preferably 5-10 min, more preferably 6-9 min, more preferably 7-8 min.

[0042] In the present invention, the sintering pressure in step (2) is preferably 0-30 MPa, more preferably 5-25 MPa, more preferably 10-20 MPa; the temperature is preferably 400-450°C, more preferably 410-440°C, more preferably 420-430°C; the time is preferably 3-6 h, more preferably 4-5 h, more preferably 4.4-4.6 h.

[0043] By adjusting the conditions of pre-pressing and hot pressing sintering, the present invention can obtain Bi with n-type and p-type conductivity types in different regions. y Sb 2-y Se 3-x Te x Thermoelectric materials. The preparation method adopted by the present invention has the advantages of simple equipment, short preparation cycle, low production cost, less environmental pollution, and suitability for large-scale promotion and application. It is of great significance for the development of thermoelectric materials with n-type and p-type conductivity types in different regions.

[0044] By adjusting the time and pressure of the hot-pressing sintering process, the dislocation motion and donor-like effect in the sample are regulated. By controlling the formation of different types of antisite defects and vacancies, releasing holes and free electrons respectively, the type of carrier transport in the sample is effectively regulated. During long-term heat preservation, dislocations will move in the sample, causing more anion vacancies to annihilate, reducing the concentration of free electrons in the lattice, and thus exhibiting p-type conductivity in the dislocation slip region. The high-pressure and high-temperature hot-pressing process provides additional energy for atomic diffusion, resetting more cationic elements occupying anionic sites in antisite defects, greatly promoting the donor-like effect, releasing a large number of electrons, and achieving stable n-type conductivity in some areas of the bulk sample.

[0045] During the long-term sintering and heat preservation process, under appropriate pressure, the "pinning" effect in the sample is weak, and the dislocation will slip. Along with the slip of the dislocation, a large number of vacancies will be absorbed by the dislocation, resulting in the annihilation of vacancies near the dislocation. Due to the special layered structure of the sample, the dislocation movement will end at the Te(Se) atom on the Te(Se)-Te(Se) plane that is bound by weak van der Waals forces, so that its free energy reaches the lowest. Therefore, its initial driving force is likely to be the reduction of free energy by the slip of a single dislocation to the low-energy Te(Se)-Te(Se) plane. It is worth noting that since dislocations are more likely to slip to the Te(Se)-Te(Se) plane with lower energy, it will lead to anion vacancies ( and ) is more than the number of cation vacancies (V″′ Bi and V″′ Sb This results in an anion-cation vacancy ratio lower than 3:2. According to the principle of charge conservation, the annihilation of anion vacancies gradually reduces the concentration of free electrons. Furthermore, because the Sb cation and Te anion have the lowest antisite defect formation energy, EAS(Sb-Te), Sb atoms are more likely to occupy the positions of Te atoms and ionize to create holes. When the concentration of positively charged holes exceeds that of negatively charged electrons, the sample exhibits stable p-type conductivity.

[0046] During the hot pressing sintering process, non-basal slip and basal slip will still exist in the sample matrix. On the one hand, the non-basal slip process produces a large number of cation vacancies, which makes it easier for the cation elements originally occupying the anion sites in the antisite defects to diffuse back to their original positions, thereby generating more anion vacancies ( and ) and release electrons. On the other hand, due to the existence of basal plane slip, more anion vacancy-interstitial atom pairs are generated, accompanied by the release of electrons in the lattice. In addition, high sintering temperatures can promote the occurrence of the point defect model from left to right. That is, under the action of high temperature, the cation atoms (Bi and Sb) in the antisite defects will have high energy, and the probability of cation atoms overcoming the energy barrier required for diffusion increases, causing more cation atoms to diffuse back to their original positions, thereby greatly promoting the occurrence of the donor-like effect and releasing a large number of electrons. Under the combined action of these factors, the electron concentration in the sample is much greater than the vacancy concentration, resulting in stable n-type conductive behavior.

[0047] Point defect model:

[0048]

[0049] Among them, C′ ANegatively charged antisite defects formed during alloying and sintering, including Bi′ Te , Sb′ Te , Bi′ Se and Sb′ Se ; are atoms that diffuse back to their original positions in the antisite defect, including and This corresponds to the anti-site defects formed during the alloying and sintering process.

[0050] The present invention also provides a method for preparing the thermoelectric material having n-type and p-type conductivity types in different regions, and the prepared thermoelectric material having n-type and p-type conductivity types in different regions.

[0051] The present invention also provides the use of a thermoelectric material having n-type and p-type conductivity types in different regions in a thermoelectric component.

[0052] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0053] Example 1

[0054] (1) Ingredients: According to Bi 0.75 Sb 1.25 The atomic ratio of Se2Te was determined by weighing metal particles Bi, Sb, Se and Te (Bi particle size was 5 mm, Sb particle size was 4 mm, Se particle size was 3 mm, Te particle size was 5 mm) with purity higher than 99.999% and placing them in a quartz tube. After being shaken thoroughly to mix them evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0055] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0056] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0057] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0058] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se2Te thermoelectric material.

[0059] Example 2

[0060] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 2.75 Te 0.25 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0061] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0062] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0063] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0064] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 2.75 Te 0.25 Thermoelectric materials.

[0065] Example 3

[0066] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 2.5 Te 0.5The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0067] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0068] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0069] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0070] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 2.5 Te 0.5 Thermoelectric materials.

[0071] Example 4

[0072] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 2.25 Te 0.75 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0073] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0074] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0075] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0076] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 2.25 Te 0.75 Thermoelectric materials.

[0077] Example 5

[0078] (1) Ingredients: According to Bi 0.75 Sb 1.25 The atomic ratio of Se2Te was determined by weighing metal particles Bi, Sb, Se and Te (Bi particle size was 5 mm, Sb particle size was 4 mm, Se particle size was 3 mm, Te particle size was 5 mm) with purity higher than 99.999% and placing them in a quartz tube. After being shaken thoroughly to mix them evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0079] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0080] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0081] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0082] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se2Te thermoelectric material.

[0083] Example 6

[0084] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 1.75 Te 1.25 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0085] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0086] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0087] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0088] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 1.75 Te 1.25 Thermoelectric materials.

[0089] Example 7

[0090] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 1.5 Te 1.5 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0091] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0092] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0093] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0094] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 1.5 Te 1.5 Thermoelectric materials.

[0095] Example 8

[0096] (1) Ingredients: According to Bi 0.75 Sb 1.25 Se 1.25 Te 1.75 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0097] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0098] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0099] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0100] (5) Hot pressing sintering: The green blank is placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The blank is cooled in the furnace to obtain Bi with n-type and p-type conductivity in different regions. 0.75 Sb 1.25 Se 1.25 Te 1.75 Thermoelectric materials.

[0101] Example 9

[0102] (1) Ingredients: According to the atomic ratio of BiSbSe2Te, metal particles of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size of 5 mm, Sb particle size of 4 mm, Se particle size of 3 mm, Te particle size of 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was heated in a vacuum of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0103] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0104] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0105] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0106] (5) Hot pressing sintering: The green blank is placed in a graphite mold and hot pressed and sintered for 6 hours at a sintering pressure of 20 MPa and a temperature of 420°C. The blank is then cooled in the furnace to obtain BiSbSe2Te thermoelectric materials with n-type and p-type conductivity types in different regions.

[0107] Example 10

[0108] (1) Ingredients: BiSbSe 2.75 Te 0.25 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0109] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0110] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0111] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0112] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 2.75 Te 0.25 Thermoelectric materials.

[0113] Example 11

[0114] (1) Ingredients: BiSbSe 2.5 Te 0.5 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0115] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0116] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0117] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0118] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 2.5 Te 0.5 Thermoelectric materials.

[0119] Example 12

[0120] (1) Ingredients: BiSbSe 2.25 Te 0.75 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0121] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0122] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0123] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0124] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 2.25 Te 0.75 Thermoelectric materials.

[0125] Example 13

[0126] (1) Ingredients: BiSbSe 2.15 Te 0.85 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0127] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0128] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0129] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0130] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 2.15 Te 0.85 Thermoelectric materials.

[0131] Example 14

[0132] (1) Ingredients: BiSbSe 1.75 Te 1.25 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0133] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0134] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0135] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0136] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 1.75 Te 1.25 Thermoelectric materials.

[0137] Example 15

[0138] (1) Ingredients: BiSbSe 1.25 Te 1.75 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4 Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0139] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0140] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0141] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0142] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 1.25 Te 1.75 Thermoelectric materials.

[0143] Example 16

[0144] (1) Ingredients: BiSbSe 1.25 Te 1.75 The atomic stoichiometric ratio of Bi, Sb, Se and Te with a purity higher than 99.999% (Bi particle size is 5 mm, Sb particle size is 4 mm, Se particle size is 3 mm, Te particle size is 5 mm) were weighed and placed in a quartz tube. After being shaken thoroughly to mix evenly, the mixture was stirred at a vacuum degree of 5.0×10 -4Under the condition of Pa, the tube is sealed using a hydrogen flame gun;

[0145] (2) Alloying and sintering: The sealed quartz tube was placed in a muffle furnace for alloying and sintering. The temperature was raised to 300°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 500°C at a heating rate of 6°C / min, and kept at this temperature for 0.5 h. The temperature was then raised to 900°C at a heating rate of 6°C / min, and kept at this temperature for 9 h. The tube was then cooled in the furnace.

[0146] (3) Crushing: The alloyed sintered product was crushed with an agate mortar and fully ground to obtain alloyed powder (50 μm);

[0147] (4) Pre-pressing: The alloyed powder is pressed under 15 MPa and maintained for 5 min to obtain a green billet;

[0148] (5) Hot pressing sintering: The green blank was placed into a graphite mold and hot pressed for 6 hours at a sintering pressure of 20 MPa and a temperature of 420 ° C. The hot pressing was then carried out and the BiSbSe with n-type and p-type conductivity in different regions was obtained. 1.25 Te 1.75 Thermoelectric materials.

[0149] The thermoelectric material obtained in Example 9 was subjected to XRD test, and the test results are as follows: Figure 1 As shown, from Figure 1 It can be seen that in the embodiments of the present invention, no other impurity peaks are generated in the ingot sample (Ingot), alloyed powder (Powder) and p-type region and n-type region bulk samples, indicating that the method provided by the present invention can obtain a single-phase sample with good chemical stability.

[0150] The thermoelectric material obtained in Example 9 was subjected to SEM testing, and the test results are as follows: Figure 2 As shown, (a) is the p-type region, (b) is the n-type region, Figure 2 It can be seen that the grains in the embodiments of the present invention all have a flake structure.

[0151] The thermoelectric material obtained in Example 9 was subjected to EPMA test, and the test results are as follows: Figure 3 As shown, (a) is the p-type region, (b) is the n-type region, Figure 3 It can be seen that no second phase exists in the embodiments of the present invention, and the method provided by the present invention can be used in the bulk material Bi y Sb 2-y Se 3-x Te x N-type and p-type thermoelectric materials were successfully obtained in different areas of the tube.

[0152] The Seebeck coefficient of the thermoelectric material obtained in Example 9 was tested using a portable Seebeck coefficient tester PTM-3, and the resistance of the thermoelectric material obtained in Example 9 was tested using a multimeter. The measurement results are shown in Table 1.

[0153] Table 1 Resistance test results

[0154]

[0155] As shown in Table 1, at room temperature, the Seebeck coefficient S of the p-type region of the BiSbSe2Te thermoelectric material is 200μV / K~220μV / K, and the resistance is 150Ω~180Ω; the Seebeck coefficient S of the n-type region is -131μμV / K~150μV / K, and the resistance is 20Ω~50Ω.

[0156] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a thermoelectric material having n-type and p-type conductivity in different regions, characterized in that: It includes the following steps: (1) According to Bi y Sb 2-y Se 3-x Te x The composition of the thermoelectric material is to mix Bi, Sb, Se and Te, perform alloying and sintering, and obtain alloy powder; (2) The alloyed powder is sequentially molded and sintered to obtain a thermoelectric material in which the different regions have n-type and p-type conductivity types, respectively.

2. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 1, characterized in that: Bi y Sb 2-y Se 3-x Te x In thermoelectric materials, the value of x is 0.25 to 1.75, and the value of y is 0.5 to 1.

75.

3. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 2, characterized in that: The vacuum degree of the alloying sintering in step (1) is ≤1.0×10 -3 Pa.

4. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 3, wherein: The alloying sintering in step (1) is a first alloying sintering, a second alloying sintering and a third alloying sintering performed sequentially; The temperature of the first alloying sintering is 200-300° C., the holding time is 0.5-1 hour, and the heating rate to the first alloying sintering temperature is 5-8° C. / min.

5. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 4, characterized in that: The temperature of the second alloying and sintering is 300-500° C., the holding time is 0.5-1 hour, and the heating rate from the first alloying and sintering temperature to the second alloying and sintering temperature is 5-8° C. / min.

6. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 4, wherein: The temperature of the third alloying and sintering is 700-900° C., the holding time is 6-10 hours, and the heating rate from the second alloying and sintering temperature to the third alloying and sintering temperature is 5-8° C. / min.

7. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 6, characterized in that: The particle size of the alloying powder in step (1) is 1 to 100 μm; The molding pressure in step (2) is 5 to 20 MPa, and the holding time is 5 to 10 minutes.

8. The method for preparing a thermoelectric material having n-type and p-type conductivity in different regions according to claim 7, characterized in that: The sintering pressure in step (2) is 0-30 MPa, the temperature is 400-450° C., and the time is 3-6 hours. 9 . Thermoelectric material having n-type and p-type conductivity types in different regions prepared by the method for preparing a thermoelectric material having n-type and p-type conductivity types in different regions according to any one of claims 1 to 8 .

10. Use of the thermoelectric material according to claim 9, wherein different regions have n-type and p-type conductivity types, respectively, in a thermoelectric component.

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