High-performance n-type Mg3 (Sb, Bi) 2-based thermoelectric material and preparation method and application thereof

Abstract

The invention provides a high-performance n-type Mg3 (Sb, Bi) 2-based thermoelectric material as well as a preparation method and application thereof, and the chemical composition of the thermoelectric material is as follows: 3.2-3.5% of Mg, 1.0-1.5% of Sb, 0.49-1.0% of Bi and 0.01-0.03% of Te. The preparation method of the thermoelectric material comprises the following steps: in an inert atmosphere, mixing Mg particles, Bi particles, Sb particles and Te powder, and carrying out ball milling to obtain precursor powder; and sintering the precursor powder to obtain the high-performance n-type Mg3 (Sb, Bi) 2-based thermoelectric material. According to the thermoelectric material, thermoelectric performance decoupling is achieved on the premise that component optimization is not carried out, and improvement of the zT value is promoted. When the thermoelectric material is prepared, oscillation pressure is introduced in the sintering process, grain size sufficient growth, grain deformation and redistribution of element segregation are promoted, and the thermoelectric performance of the thermoelectric material is further improved.

Description

Technical Field

[0001] The present invention relates to thermoelectric material technology, and in particular to a high-performance n-type Mg3(Sb, Bi)2-based thermoelectric material, a preparation method thereof, and applications thereof. Background Art

[0002] Thermoelectric materials are characterized by their small size, pollution-free nature, and low noise, and have important application prospects in refrigeration and power generation. With the continuous development of thermoelectric technology, the requirements for material performance are also increasing, requiring materials to have better thermoelectric performance over a wider temperature range. The performance of thermoelectric materials is characterized by the dimensionless thermoelectric figure of merit zT, which is expressed as zT = S 2 σT / κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature.

[0003] Among numerous thermoelectric materials, n-type polycrystalline Mg3(Sb,Bi)2-based thermoelectric materials have attracted the most attention in recent years for their non-toxicity, low cost, and other advantages. Currently, research on these materials primarily focuses on optimizing thermoelectric performance through compositional manipulation. However, due to limitations in solid solubility and the inherent properties of the elements, compositional manipulation is difficult to adapt to a wide range of situations. Therefore, it is particularly important for Mg3(Sb,Bi)2-based thermoelectric materials to prioritize compositional control to provide foundational performance and process control to further enhance these advantages. Summary of the Invention

[0004] The purpose of the present invention is to address the problem that traditional n-type polycrystalline Mg3(Sb,Bi)2-based thermoelectric materials are difficult to adapt to various situations due to the limitations of solid solubility and the characteristics of the elements themselves. This invention proposes a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material that achieves thermoelectric performance decoupling without composition optimization, thereby promoting an improvement in the zT value. During the preparation of the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material of the present invention, oscillating pressure is introduced during sintering to promote full grain size growth, grain deformation, and redistribution of element segregation, further improving the thermoelectric performance of the thermoelectric material.

[0005] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material, the chemical composition of which is Mg 3.2-3.5 Sb 1.0-1.5 Bi 0.49-1.0 Te 0.01-0.03 .

[0007] Furthermore, the high performance n-type Mg3(Sb,Bi)2-based thermoelectric material preferably has a chemical composition of Mg 3.2 Sb 1.5 Bi 0.49 Te 0.01 .

[0008] Furthermore, the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material has a power factor of 1.60-2.00 mW m at 723K. -1 K -2 , thermal conductivity is 0.70~0.80W m -1 K -1 .

[0009] Furthermore, the high performance n-type Mg3(Sb,Bi)2-based thermoelectric material is Mg 3.2 Sb 1.5 Bi 0.49 Te 0.01 The power factor at 723K is 1.80mW m -1 K -2 , thermal conductivity is 0.76W m -1 K -1 .

[0010] Furthermore, the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material has a thermoelectric figure of merit of 1.55 to 1.75 at 723K and an average zT of 1.2 to 1.4 at 323 to 723K.

[0011] Furthermore, the high performance n-type Mg3(Sb,Bi)2-based thermoelectric material is Mg 3.2 Sb 1.5 Bi 0.49 Te 0.01 Its thermoelectric figure of merit at 723K is 1.7, and its average zT at 323~723K is 1.33.

[0012] Another object of the present invention is to disclose a method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material. The present invention adopts oscillating pressure sintering to increase the grain size while converting equiaxed crystals into a coexistence of columnar crystals and equiaxed crystals, and introducing a large number of subgrain boundaries; in addition, the oscillating pressure promotes element redistribution, so that the Bi segregation changes from a network to a strip.

[0013] Specifically, the preparation method of the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material of the present invention comprises the following steps:

[0014] (1) In an inert atmosphere, Mg particles, Sb particles, Bi particles, and Te powder are mixed according to a ratio and ball-milled to obtain a precursor powder;

[0015] (2) The precursor powder is subjected to oscillation pressure sintering to obtain a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material.

[0016] Furthermore, the inert atmosphere in step (1) is high-purity argon, preferably high-purity argon with a water and oxygen content of less than 1 ppm, and more preferably high-purity argon with a water and oxygen content of less than 0.5 ppm. Since Mg readily reacts with water and oxygen in the air, resulting in a sharp decrease in the power factor of the material, the entire preparation process must be carried out in an argon-filled glove box.

[0017] Furthermore, the ball milling in step (1) is a vibrating ball milling, the ball milling speed is 1000-1500 rpm, the ball milling time is 3-7 hours, the ball milling time is preferably 3-10 hours, and more preferably 4-6 hours. The clamp operation rate is 850-890 cycles / minute. The present invention preferably stops the ball milling for 1 hour every two hours, and scrapes the sticky particles in the glove box to prevent damage to the ball mill and uneven ball milling caused by agglomeration of the ball milled powder, thereby ensuring the completeness of the ball milled powder reaction and the uniformity of the element distribution. After the ball milling is completed, the inner wall powder needs to be scraped and the ball milling is carried out for another 1-3 minutes to prevent the presence of large particles and affect sintering.

[0018] Furthermore, the ball milling in step (1) is preferably performed using a Spex 8000D ball mill.

[0019] Furthermore, the sources of the Mg particles, Bi particles, Sb particles, and Te powder in step (1) are not particularly limited, and commercially available products known to those skilled in the art may be used. In an embodiment of the present invention, the Mg particles are preferably metallic Mg, preferably having a purity of 99.95%; the Bi particles are preferably metallic Bi, preferably having a purity of 99.999%; the Sb particles are preferably metallic Sb, preferably having a purity of 99.99%; and the Te powder is preferably metallic Te, preferably having a purity of 99.99%.

[0020] Furthermore, the molar ratio of the Mg particles, Sb particles, Bi particles, and Te powder in step (1) is 3.2-3.5:1.0-1.5:0.49-1.0:0.01-0.03. In the present invention, an excess of Mg is used in the raw materials to prevent magnesium volatilization caused by long-term heat preservation, thereby ensuring that the thermoelectric material is an n-type semiconductor.

[0021] Furthermore, the oscillation pressure sintering in step (2) is spark plasma sintering.

[0022] Furthermore, the temperature of the shock pressure sintering in step (2) is 750-850° C., preferably 800° C.; the time of the shock pressure sintering is 10-20 minutes, preferably 13-18 minutes.

[0023] Furthermore, the temperature rise method of the oscillating pressure sintering in step (2) is step-by-step temperature rise: the temperature is raised to 600-650° C. within 5-6 minutes, and then the temperature is raised to 750-850° C. within 5-6 minutes and kept warm.

[0024] Furthermore, the upper limit of the pressure during the oscillating pressure sintering in step (2) is 40-60 MPa, preferably 45-55 MPa, and more preferably 50 MPa; the lower limit of the pressure during the oscillating pressure sintering is 5-30 MPa, preferably 15-25 MPa, and more preferably 20 MPa. That is, the holding pressure during the sintering in step (2) oscillates between 5-60 MPa, preferably between 15-55 MPa, and more preferably between 20-50 MPa.

[0025] Furthermore, the pressure change mode of the oscillating pressure sintering in step (2) is programmed pressure change: the pressure is increased to between the upper and lower pressure limits (for example, 30 MPa) within 4 to 6 minutes, and then the pressure is increased to the upper pressure limit (for example, 50 MPa) within 5 to 6 minutes, and then the pressure is reduced to the lower pressure limit (for example, 20 MPa) within 2 to 3 minutes, and then the pressure is increased to the upper pressure limit (for example, 50 MPa) within 2 to 3 minutes, and the pressure cycle ends at the insulation stage.

[0026] Furthermore, after the oscillation pressure sintering in step (2) is completed, the pressure is reduced to 0.05-0.1 MPa within 1-2 minutes, and then cooled to room temperature in the furnace.

[0027] Another object of the present invention is to disclose the application of a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material in the fields of thermoelectric power generation and chip cooling.

[0028] The high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material of the present invention, its preparation method and application have the following advantages compared with the prior art:

[0029] The high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material of the present invention is a high-performance magnesium-based thermoelectric material prepared by oscillatory pressure sintering. Through oscillatory pressure sintering, the present invention converts completely equiaxed grains into equiaxed and columnar crystals while increasing grain size and introducing a large number of subgrain boundaries. Furthermore, oscillatory pressure sintering promotes element redistribution, transforming Bi segregation from a mesh to a stripe pattern and grain boundary segregation from the original mesh arrangement to a stripe pattern. The increase in grain size and the change in grain boundary segregation promote an increase in electrical conductivity, while the columnar grains and subgrain boundaries enhance phonon scattering.

[0030] The high-performance n-type Mg3(Sb, Bi)2-based thermoelectric material of the present invention has a thermoelectric figure of merit of 1.55-1.75 at 723K and an average value zT of 1.2-1.4 at 323-723K.

[0031] The high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material of the present invention has good application prospects and large-scale promotion potential in the fields of temperature difference power generation and chip refrigeration. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Mg in Examples 1, 2, 3 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 Conductivity graph of thermoelectric materials;

[0033] Figure 2 Mg in Examples 1, 2, 3 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 Seebeck coefficient curve of thermoelectric materials;

[0034] Figure 3 Mg in Examples 1, 2, 3 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 Power factor curve of thermoelectric materials;

[0035] Figure 4 Mg in Examples 1, 2, 3 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 Thermal conductivity curve of thermoelectric materials;

[0036] Figure 5 Mg in Examples 1, 2, 3 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 Thermoelectric figures of merit of thermoelectric materials;

[0037] Figure 6 Mg in Example 2 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 BSE and EPMA images of thermoelectric materials;

[0038] Figure 7Mg in Example 2 and Comparative Example 1 3.2 Sb 1.5 Bi 0.49 Te 0.01 EBSD data of thermoelectric materials. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the following examples. The following description of the technical features is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0040] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0041] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0042] In this specification, the numerical range expressed using "above" or "below" means a numerical range including the number.

[0043] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0044] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0045] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0046] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0047] The present invention provides a method for preparing Mg by oscillating pressure sintering. 3.2 Sb 1.5 Bi 0.49 Te 0.01The method for preparing thermoelectric materials, wherein the sintering and heat-insulating pressure oscillates between x and 50 MPa, where 5≤x≤30 MPa. In the present invention, conventional constant pressure sintering is changed to oscillating pressure sintering, which adjusts the grain structure and element segregation of the material. While not significantly reducing the Seebeck coefficient, the electrical conductivity is greatly improved. At the same time, the coexistence of subgrain boundaries and columnar crystals with equiaxed crystals greatly enhances phonon scattering and reduces the thermal conductivity of the material, ultimately making the material's thermoelectric figure of merit at 723 K 1.7 and the average value zT at 323 to 723 K 1.33. In the present invention, the thermoelectric performance of the material is optimized by changing the range of the oscillation pressure.

[0048] Specifically, the preparation method of the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material comprises the following steps:

[0049] (1) In an inert atmosphere, Mg particles, Bi particles, Sb particles, and Te powder are ball-milled to obtain a precursor powder;

[0050] (2) The precursor powder obtained in step (1) is subjected to pressure sintering to obtain an n-type Mg3(Sb,Bi)2-based thermoelectric material.

[0051] The present invention does not specifically limit the sources of the Mg particles, Bi particles, Sb particles, and Te powder; commercially available products familiar to those skilled in the art may be used. In an embodiment of the present invention, the Mg particles are preferably metallic Mg, preferably having a purity of 99.95%; the Bi particles are preferably metallic Bi, preferably having a purity of 99.999%; the Sb particles are preferably metallic Sb, preferably having a purity of 99.99%; and the Te powder is preferably metallic Te, preferably having a purity of 99.99%.

[0052] In the present invention, the molar ratio of the Mg particles, Bi particles, Sb particles, and Te powder is 3.2:0.49:1.5:0.01. In the present invention, the excessive amount of Mg in the raw materials is used to prevent the volatilization of magnesium caused by long-term heat preservation, ensuring that the thermoelectric material is an n-type semiconductor.

[0053] In the present invention, the inert atmosphere is preferably high-purity argon, more preferably one with a water and oxygen content of less than 1 ppm, and most preferably one with a water and oxygen content of less than 0.5 ppm. Because Mg readily reacts with water and oxygen in the air, resulting in a significant decrease in the material's power factor, the entire preparation process must be performed in an argon-filled glove box.

[0054] In the present invention, the ball mill is preferably a vibration ball mill.

[0055] In the embodiment of the present invention, preferably 6 to 10 g of raw materials are weighed each time and placed in a ball mill containing two 1 / 2 inch stainless steel balls. The present invention ensures the thoroughness of the ball milling process by controlling the input amount of the ball milling raw materials.

[0056] In the present invention, the ball milling time is preferably 3 to 10 hours, more preferably 4 to 6 hours. The ball milling is preferably stopped for 1 hour every two hours, and particles adhering to the wall are scraped in a glove box to prevent damage to the ball mill and uneven milling caused by agglomeration of the ball milled powder, thereby ensuring complete reaction of the ball milled powder and uniform element distribution.

[0057] In the present invention, the ball milling is preferably performed using a Spex 8000D ball mill.

[0058] After the ball milling is completed, the inner wall powder needs to be scraped and the ball milling should be continued for 1 to 3 minutes to prevent the presence of large particles that affect sintering.

[0059] After obtaining the precursor powder, the present invention sintered the precursor powder to obtain an n-type Mg3(Sb,Bi)2-based thermoelectric material.

[0060] In the present invention, the oscillation pressure sintering is preferably spark plasma sintering.

[0061] In the present invention, the upper pressure limit of the oscillating pressure sintering is preferably 40-60 MPa, more preferably 45-55 MPa, and most preferably 50 MPa; the lower pressure limit is preferably 5-35 MPa, more preferably 15-25 MPa, and most preferably 20 MPa; the sintering temperature is preferably 750-850°C, more preferably 800°C; and the sintering time is preferably 10-20 minutes, more preferably 13-18 minutes. In the present invention, by introducing oscillating pressure during the sintering and holding stage, the deformation of the grain size and the redistribution of element segregation are promoted during the crystal growth process, thereby decoupling the electroacoustic transport properties.

[0062] In the present invention, the sintering temperature is preferably increased in a stepwise manner: the temperature is increased to 600-650° C. within 5-6 minutes, and then the temperature is increased to the sintering temperature within 5-6 minutes.

[0063] After sintering is completed, the present invention preferably reduces the pressure to 0.05-0.1 MPa within 1-2 minutes, and then cools the furnace to room temperature.

[0064] The preparation method of the n-type Mg3(Sb,Bi)2-based thermoelectric material provided by the present invention promotes the full growth of grain size, grain deformation and redistribution of element segregation by introducing oscillating pressure during sintering, thereby further improving the thermoelectric performance of the thermoelectric material.

[0065] Example 1

[0066] This embodiment discloses a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material, the chemical composition of which is Mg3Sb 1.5 Bi 0.49 Te 0.01 , the oscillation pressure is 10~50Mpa.

[0067] The high performance n-type Mg3Sb 1.5 Bi 0.49 Te 0.01 A method for preparing a thermoelectric material comprises the following steps:

[0068] (1) Weigh the raw materials in a glove box with an argon atmosphere and a water and oxygen content of less than 1 ppm. The chemical composition of the thermoelectric material is Mg3Sb 1.5 Bi 0.49 Te 0.01 The reaction raw materials are 1.7089g Mg metal particles, 4.0130g Sb metal particles, 2.2500g Bi metal particles and 0.028g Te metal powder, wherein the amount ratio of Mg metal particles, Sb metal particles, Bi metal particles and Te metal powder is 3.2:1.5:0.49:0.01; and the weighed Mg metal particles, Sb metal particles, Bi metal particles, and Te metal powder are added to a spex ball mill containing two 1 / 2 inch stainless steel balls and ball milled for 5h. The ball mill is first run for 1h, and the machine is stopped to scrape the powder on the wall of the ball mill jar. After that, the powder stuck on the wall of the ball mill jar is scraped off in the glove box every 2h, and the powder is put into the jar and continued to be ball milled. After the ball milling is completed, the ball mill is further ball milled for 1min to ensure that the obtained powder has no agglomerated particles; the ball mill speed is 1500rpm, and the fixture operation rate is 875 cycles / min;

[0069] (2) The ball-milled powder obtained in step (1) is placed in an inert atmosphere into a graphite mold, and the graphite mold is placed in a spark plasma sintering furnace. The temperature is raised to 610° C. and the pressure is increased to 30 MPa within 5 minutes. The temperature is then raised to 800° C. and the pressure is increased to 50 MPa within 5 minutes. The oscillation pressure sintering is carried out at 800° C. for 15 minutes, wherein the pressure is reduced to 10 MPa within 3 minutes, and then increased to 50 MPa within 3 minutes, until the post-sintering is completed after 15 minutes. After the sintering is completed, the pressure is reduced to 0.05 MPa within 1 minute, and the furnace is then cooled to room temperature to obtain an OP-1050 sample.

[0070] Example 2

[0071] Example 2 discloses a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material, which differs from Example 1 in that the pressure range of the oscillating pressure sintering is 20-50 MPa, and the sample number is OP-2050; the rest is the same as Example 1.

[0072] Example 3

[0073] Example 3 discloses a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material, which differs from Example 1 in that the pressure range of the oscillating pressure sintering is 30-50 MPa, and the sample number is OP-3050; the rest is the same as Example 1.

[0074] Comparative Example 1

[0075] Comparative Example 1 discloses a thermoelectric material, which differs from Example 1 in that constant pressure sintering is adopted, that is, when the sample reaches the holding temperature of 800°C, the pressure is kept constant at 50 MPa until the sintering is completed. The sample is numbered CP-50; the rest is the same as Example 1.

[0076] The high-performance n-type Mg3(Sb,Bi)2-based thermoelectric materials of Examples 1-3 and the thermoelectric material of Comparative Example 1 were tested respectively. The test methods and test results are as follows:

[0077] The electrical performance test of the thermoelectric materials obtained in Examples 1 to 3 and Comparative Example 1 was conducted using the LSR-3 electrical performance test system. The test curves of electrical conductivity are shown in FIG. Figure 1 As shown, the test curve of Seebeck coefficient is as follows Figure 2 As shown, the test curve of power factor is as follows Figure 3 As shown. Figures 1 to 3 It can be seen that the improvement of electrical conductivity by oscillation pressure sintering is greater than the reduction of Seebeck coefficient, which ultimately improves the power factor of the obtained composite thermoelectric material.

[0078] The thermal diffusion coefficient F of the thermoelectric materials obtained in Examples 1 to 3 and Comparative Example 1 was measured by laser flash method (LFA-457 laser thermal conductivity meter), and the sample density Dd measured by Archimedes drainage method and the formula Cp [J g -1 K -1 ]=3NR / MW·(1+1.3×10 -4 ×T-4×10 -3 ×T 2 ) The heat capacity Cp is calculated, and then the total thermal conductivity κ is calculated according to the following formula: κ=CpDd. The result of the total thermal conductivity is as follows Figure 4 As shown. Figure 4 It can be seen that oscillating pressure sintering leads to a decrease in thermal conductivity.

[0079] Using the formula zT=S 2 σT / κ tot The thermoelectric figures of merit of the thermoelectric materials obtained in Examples 1 to 3 and Comparative Example 1 were calculated, and the results were as follows: Figure 5 As shown. Figure 5It can be seen that by using appropriate oscillating pressure for sintering, the thermoelectric performance of the material is improved overall.

[0080] The surfaces of the thermoelectric materials obtained in Example 2 and Comparative Example 1 were polished, and then EPMA tests were performed using a field emission electron probe (JXA-8530F PLUS). Figure 6 It can be seen that the Bi segregation of the sample obtained by oscillating pressure sintering changes from a network to a strip.

[0081] The surfaces of the thermoelectric materials obtained in Example 2 and Comparative Example 1 were polished and then subjected to EBSD testing using a high-resolution field emission scanning electron microscope (JSM-IT800). Figure 7 It can be seen that the sample sintered by oscillation pressure has a larger grain size, while the grains are severely deformed. In addition, there are a large number of subgrain boundaries inside the material.

[0082] In summary, the n-type Mg3(Sb,Bi)2-based thermoelectric material provided by the present invention has an improved thermoelectric figure of merit in the entire temperature range due to the simultaneous improvement of power factor and thermal conductivity.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material, characterized in that: Its chemical composition is Mg 3.2- 3.5 Sb 1.0-1.5 Bi 0.49-1.0 Te 0.01-0.03 .

2. A method for preparing the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 1, characterized in that: The following steps are involved: (1) In an inert atmosphere, Mg particles, Bi particles, Sb particles, and Te powder are mixed according to a ratio and ball-milled to obtain a precursor powder; (2) The precursor powder is subjected to oscillation pressure sintering to obtain a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material.

3. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The inert atmosphere in step (1) is high-purity argon.

4. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The ball milling in step (1) is a vibration ball milling, the ball milling speed is 1000-1500 rpm, and the ball milling time is 3-7 hours; And / or, stop ball milling for 1 hour every two hours and scrape the particles sticking to the wall; And / or, after the ball milling is completed, the inner wall powder needs to be scraped and the ball milling is continued for another 1 to 3 minutes.

5. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The oscillating pressure sintering in step (2) is spark plasma sintering; And / or, the temperature of the shock pressure sintering in step (2) is 750-850° C., and the time of the shock pressure sintering is 10-20 minutes.

6. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The temperature rise method of the oscillating pressure sintering in step (2) is stepwise heating: the temperature is raised to 600-650°C within 5-6 minutes, and then the temperature is raised to 750-850°C within 5-6 minutes and kept warm.

7. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The upper limit of the pressure of the oscillating pressure sintering in step (2) is 40 to 60 MPa; the lower limit of the pressure of the oscillating pressure sintering is 5 to 35 MPa.

8. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: The pressure change mode of the oscillating pressure sintering in step (2) is programmed pressure change: the pressure is increased to between the upper and lower pressure limits within 4 to 6 minutes, then the pressure is increased to the upper pressure limit within 5 to 6 minutes, then the pressure is reduced to the lower pressure limit within 2 to 3 minutes, and then the pressure is increased to the upper pressure limit within 2 to 3 minutes, and the pressure cycle ends when the insulation stage is completed.

9. The method for preparing a high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 2, characterized in that: After the shock pressure sintering in step (2) is completed, the pressure is reduced to 0.05-0.1 MPa within 1-2 minutes, and then cooled to room temperature in the furnace.

10. Application of the high-performance n-type Mg3(Sb,Bi)2-based thermoelectric material according to claim 1 in the fields of thermoelectric power generation and chip cooling.

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