A magnesium-based thermoelectric material and a method of making the same

Abstract

The application provides a magnesium-based thermoelectric material and a preparation method and device thereof. The preparation method comprises the following steps: placing reaction raw materials of the magnesium-based thermoelectric material into a yttria-doped zirconia crucible; sealing the yttria-doped zirconia crucible containing the reaction raw materials into a tantalum crucible; sealing the tantalum crucible obtained in the step (2) into a quartz tube; and placing the sealed quartz tube into a rocking growth furnace to perform grain growth and solidification of the magnesium-based thermoelectric material. The preparation method provided by the application can prepare a magnesium-based thermoelectric material with higher performance and large grain size through a high-temperature melting method.

Description

Technical Field

[0001] This invention relates to a magnesium-based thermoelectric material and its preparation method and apparatus, specifically to a method for preparing a higher-performance magnesium-based thermoelectric material with large grain size by a high-temperature melting method, and the magnesium-based thermoelectric material obtained by the method. Background Technology

[0002] Thermoelectric materials are functional materials capable of directly converting heat energy into electrical energy. Thermoelectric devices made from these materials possess advantages such as light weight, small size, simple structure, no noise, zero emissions, long service life, and the ability to be used in distant outer space. This is of great significance for solving the severe energy crisis and environmental pollution problems currently facing humanity, and therefore has received high attention from countries around the world. With the discovery of new thermoelectric materials and the development of device fabrication processes and technologies, the performance of thermoelectric materials has been gradually optimized and improved. Currently, thermoelectric devices can be commercialized to a certain extent, with bismuth telluride-based thermoelectric devices showing particular advantages. However, the high cost of bismuth telluride material preparation and the scarcity and toxicity of some of the elements used limit its further large-scale use in thermoelectric devices. Therefore, developing new high-performance thermoelectric materials and fabricating high-performance devices is a strategic need for the entire thermoelectric field and also a current bottleneck in the development of thermoelectric devices.

[0003] Magnesium-bismuth-antimony alloys and magnesium-silver-antimony alloys have been research hotspots in thermoelectric materials since their discovery. Through in-depth research, the thermoelectric properties of these two magnesium-based materials have been significantly improved. Thermoelectric devices based on magnesium-based materials are also under simultaneous research and have achieved promising initial results, comparable to currently commercialized bismuth telluride-based thermoelectric devices. In addition, magnesium-silicon-germanium-tin alloys are also high-performance magnesium-containing thermoelectric materials.

[0004] Currently, the preparation of magnesium-based thermoelectric materials remains in the laboratory stage. Traditional preparation processes involve weighing a small amount of raw material in a glove box, ball milling to ensure uniform mixing, placing the powder in a graphite mold, and sintering it into blocks using spark plasma or hot pressing techniques. However, the powder adherence to the walls during ball milling leads to significant raw material loss and introduces impurities, resulting in some performance degradation. To advance the industrialization of magnesium-based thermoelectric devices, both material performance and cost must be considered. High-temperature melting is a method that can simultaneously achieve large-grain-size sample growth and mass production. Given the high vapor pressure and high reactivity of magnesium, finding a suitable crucible is crucial. Commonly used crucibles in this method include carbon crucibles, magnesium oxide crucibles, alumina crucibles, and tantalum crucibles. However, these crucibles react with magnesium-based alloys to varying degrees at high temperatures, making it difficult to prepare high-performance thermoelectric materials and hindering the commercial application of magnesium-based thermoelectric devices. Summary of the Invention

[0005] To realize the application of magnesium-based thermoelectric materials in devices, save time and costs, and improve economic efficiency, the purpose of this invention is to address the limitations of traditional laboratory techniques by exploring crucibles suitable for high-temperature melting methods to grow high-performance magnesium-based materials, thereby achieving the production of higher-performance magnesium-based thermoelectric materials with large grain sizes and promoting the industrialization of magnesium-based devices.

[0006] On one hand, the present invention provides a high-temperature melting apparatus, which includes a zirconium oxide crucible doped with yttrium oxide for directly containing raw materials, a tantalum crucible encased outside the zirconium oxide crucible doped with yttrium oxide, and a quartz tube encased outside the tantalum crucible.

[0007] On the other hand, the present invention provides a method for preparing a magnesium-based thermoelectric material, the method comprising the following steps:

[0008] (1) Place the reaction raw materials of magnesium-based thermoelectric materials into a zirconium oxide crucible doped with yttrium oxide;

[0009] (2) Seal the zirconium oxide crucible containing the reactants, which is doped with yttrium oxide, inside the tantalum crucible;

[0010] (3) Seal the tantalum crucible obtained in step (2) into a quartz tube;

[0011] (4) Place the sealed quartz tube into the swing growth furnace to carry out the grain growth and solidification of magnesium-based thermoelectric materials.

[0012] According to the preparation method provided by the present invention, the reaction raw materials include: Mg and one or more elements selected from Bi, Sb, Te, Ag, Si, Ge, Sn, Al, Zn and optional transition metals Y, Cu, Mn, etc., in their elemental form or alloys thereof. For example, when the chemical formula of the magnesium-based thermoelectric material is Mg... 3.15 Bi 1.4975 Sb 0.5 Te 0.0025 The reaction raw materials can be Mg particles, Bi blocks, Sb blocks and Te blocks weighed according to the chemical formula molar ratio.

[0013] According to the preparation method provided by the present invention, preferably, step (1) includes weighing the reaction raw materials in a glove box and placing them into a zirconium oxide crucible doped with yttrium oxide.

[0014] Preferably, step (2) includes sealing a yttrium-doped zirconium oxide crucible containing the reaction raw materials into a tantalum crucible in an inert atmosphere by means of an electric arc melting technique.

[0015] Preferably, step (3) is performed in a vacuum environment.

[0016] According to the preparation method provided by the present invention, step (4) may include: placing a quartz tube containing the reaction raw materials into a rocking growth furnace, heating it to 500-1050°C at a rate of 10-100°C / hour, rocking it at this temperature for 0.5-20 hours, then slowly cooling it to 300-900°C at a rate of 2-50°C / hour, maintaining it at this temperature for 1-15 days, and then cooling it to room temperature with the furnace.

[0017] According to the preparation method provided by the present invention, the inner diameter of the yttrium-doped zirconium oxide crucible can be 13-50 mm and the height can be 60-100 mm.

[0018] In an exemplary embodiment, the preparation method of the present invention can be carried out as follows: First, the reaction raw materials are weighed in a glove box and placed in a yttrium-doped zirconia crucible; under an argon atmosphere, they are sealed inside a tantalum crucible using an electric arc melting technique, and then a quartz tube is sealed in a vacuum environment; the sealed tube is placed in a rocking growth furnace, heated to a specific temperature at a specific rate and held for a certain period of time (0.5-20 hours) while being rocked, and then cooled to a specified specific temperature at a relatively slow cooling rate (2-50℃ / hour) to achieve grain growth and solidification of the material. The obtained sample is generally cylindrical with a diameter of 13-50 mm, and the specific size can be changed according to the size of the crucible.

[0019] Furthermore, the present invention also provides a magnesium-based thermoelectric material prepared by the above-described preparation method.

[0020] According to the magnesium-based thermoelectric material provided by the present invention, the average grain size of the magnesium-based thermoelectric material is 5~130 μm.

[0021] Preferably, the axial resistivity of the magnesium-based thermoelectric material is 7.5~14 μΩ m.

[0022] Preferably, the power factor of the magnesium-based thermoelectric material is 25~32 µW cm⁻¹. -1 K -2 .

[0023] Preferably, the room temperature thermoelectric figure of merit zT of the magnesium-based thermoelectric material is 0.4~0.8.

[0024] The innovation of this invention lies primarily in the use of a high-temperature melting apparatus composed of a yttrium-doped zirconium oxide crucible, a tantalum crucible, and a quartz tube to grow a large quantity of high-performance, large-grain-size magnesium-based materials. Thermoelectric devices fabricated based on this material can achieve the level of existing bismuth telluride-based thermoelectric devices, while simultaneously achieving a significant cost reduction. Currently, no reports have been found internationally regarding this type of magnesium-based material growth technology.

[0025] The high-temperature melting apparatus selected in this invention, suitable for the growth of magnesium-based thermoelectric materials, has significant application value and promising prospects. The use of this apparatus enables the production of high-performance magnesium-based thermoelectric materials with larger grain sizes, while saving considerable time and costs. This makes the industrialization of high-performance magnesium-based thermoelectric materials possible, allowing them to enter the market and be used in the fabrication of high-performance thermoelectric devices. The selection of the high-temperature melting apparatus, combined with the method of this invention, allows for the mass production of high-performance magnesium-based thermoelectric materials with larger grain sizes, gradually replacing existing bismuth telluride-based thermoelectric devices on the market. This represents a breakthrough in thermoelectric device applications, with enormous potential for improving economic efficiency and broad development prospects.

[0026] In addition, other non-thermoelectric magnesium alloys, such as magnesium-aluminum alloys and magnesium-manganese alloys, can also be produced by high-temperature melting using the high-temperature melting method provided by this invention. Attached Figure Description

[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0028] Figure 1 A schematic diagram of the high-temperature melting device of the present invention;

[0029] Figure 2 The interface between the magnesium-based material and the yttrium oxide-doped zirconium oxide crucible is shown under a scanning electron microscope.

[0030] Figure 3A schematic diagram of the method for testing the resistivity and Seebeck coefficient of thermoelectric materials;

[0031] Figure 4 This is a comparison diagram of the X-ray diffraction patterns of the magnesium-based thermoelectric materials prepared in Examples 1-3 of the present invention with the standard diffraction peaks. Detailed Implementation

[0032] Figure 1 This is a schematic diagram of the high-temperature melting apparatus of the present invention. The apparatus includes a yttrium-doped zirconium oxide crucible that is in direct contact with the reactants, a tantalum crucible encased outside the yttrium-doped zirconium oxide crucible, and a quartz tube encased outside the tantalum crucible.

[0033] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] (1) Mix Mg particles, Bi blocks, Sb blocks, and Te blocks according to the chemical formula Mg 3.15 Bi 1.4975 Sb 0.5 Te 0.0025 Weigh the contents in a glove box; the total weight is 12g. Place the contents into a zirconium oxide crucible doped with yttrium oxide.

[0036] (2) Place the yttrium-doped zirconium oxide crucible from step (1) into the tantalum crucible, and evacuate to 10°C in the arc melting furnace. -4 Pa, fill with argon gas and seal the tantalum crucible;

[0037] (3) Place the sealed tantalum crucible inside the quartz tube, evacuate to 0.3 Pa, and melt and seal it under a high-temperature flame gun;

[0038] (4) Place the quartz tube containing the reaction raw materials into the rocking growth furnace, heat it to 1000°C at a rate of 100°C / hour, rock it at this temperature for 10 hours, then slowly cool it to 500°C at a rate of 3°C / hour, keep it at this temperature for 5 days, and then cool it to room temperature with the furnace.

[0039] (5) By successively breaking open the quartz tube, cutting open the tantalum crucible, and breaking the yttrium-doped zirconium oxide crucible, a cylindrical magnesium-based thermoelectric material Mg can be obtained. 3.15 Bi 1.4975 Sb 0.5 Te 0.0025 It has a diameter of 13 mm and a height of approximately 17 mm.

[0040] Example 2

[0041] Magnesium-based thermoelectric material MgAgSb was prepared using the same method as in Example 1, except that:

[0042] The growth conditions in the swing growth furnace in step (4) are as follows: the temperature is increased to 1050°C at a rate of 100°C / hour, the temperature is swinged and maintained at this temperature for 12 hours, and then cooled with the furnace until room temperature.

[0043] Furthermore, step (6) was performed whereby the obtained cylindrical MgAgSb material was placed inside a quartz tube, evacuated to 0.3 Pa, and melted and sealed under a high-temperature flame gun. Subsequently, the quartz tube was placed in a pit furnace and heated to 300°C at a rate of 100°C / hour, maintained at this temperature for 7 days, and then cooled to room temperature with the furnace.

[0044] Example 3

[0045] Magnesium-based thermoelectric material Mg2Si was prepared using the same method as in Example 1. 0.39 Sn 0.6 Sb 0.01 The difference is that the growth conditions in step (4) in the swing growth furnace are: heating to 900°C at a rate of 100°C / hour, swinging at this temperature for 1 hour, then slowly cooling to 700°C at a rate of 4°C / hour, then slowly cooling to 300°C at a rate of 20°C / hour, and then cooling to room temperature with the furnace.

[0046] Comparative Example 1

[0047] This comparative example uses a conventional sintering method to prepare an alloy sample with the same composition as in Example 1.

[0048] (1) Mix Mg chips, Bi blocks, Sb blocks, and Te blocks according to the chemical formula Mg 3.15 Bi 1.4975 Sb 0.5 Te 0.0025 Weigh the contents in the glove box; the total weight is 10 g. Place the contents into a steel ball mill jar.

[0049] (2) Place the steel ball mill jar from step (1) into a high-energy ball mill and ball mill for 12 hours to obtain a uniformly mixed powder;

[0050] (3) In the glove box, open the ball mill jar, weigh about 1.4g of the well-mixed powder and fill it into a graphite mold with a diameter of 12.7mm. Place graphite paper on both sides to prevent the sample from being squeezed out.

[0051] (4) Place the graphite mold containing powder into the discharge plasma sintering system, evacuate it to 10 Pa, raise the temperature to 600°C at a rate of 50°C / min under a pressure of 50 MPa, hold it at this temperature for 2 minutes, raise the temperature to 780°C at a rate of 50°C / min, hold it at this temperature for 2 minutes, and then let it cool naturally to room temperature.

[0052] (5) Remove the sintered block sample from the graphite mold, grind off the graphite paper, and you will get a disc-shaped magnesium-based thermoelectric material Mg. 3.15 Bi 1.4975 Sb 0.5 Te 0.0025 It has a diameter of 12.7 mm and a height of approximately 1.6 mm.

[0053] Comparative Example 2

[0054] This comparative example uses a conventional sintering method to prepare an alloy sample with the same composition as in Example 2.

[0055] (1) Weigh the Mg particles and Ag particles in a glove box at a mass ratio of Mg:Ag = 1:1. The total weight is 5.2053g. Place them in a steel ball mill jar.

[0056] (2) Place the steel ball mill jar from step (1) into a high-energy ball mill and ball mill for 10 hours to obtain uniformly mixed MgAg powder;

[0057] (3) Weigh 4.7948g of Sb block in the glove box and add it to the ball mill jar containing MgAg powder obtained in step (2). Then put it into a high-energy ball mill and ball mill for 10 hours to obtain uniformly mixed MgAgSb powder.

[0058] (4) In the glove box, open the ball mill jar, weigh about 1.3g of the well-mixed powder and fill it into a graphite mold with a diameter of 12.7mm. Place graphite paper on the top and bottom sides of the powder to prevent the sample from being squeezed out.

[0059] (5) Place the graphite mold containing powder into the discharge plasma sintering system, evacuate it to 10 Pa, heat it to 300°C at a rate of 50°C / min under a pressure of 80 MPa, hold it at this temperature for 5 minutes, and then let it cool naturally to room temperature.

[0060] (6) Take out the sintered block sample from the graphite mold, grind off the graphite paper, and you can get a circular magnesium-based thermoelectric material MgAgSb with a diameter of 12.7 mm and a height of about 1.5 mm.

[0061] Comparative Example 3

[0062] This comparative example uses a conventional sintering method to prepare an alloy sample with the same composition as in Example 3.

[0063] (1) According to the chemical formula Mg 2.7 Si 0.39 Sn 0.6 Sb 0.01 Weigh Mg chips, SnCl2 powder, Si powder and Sb blocks in a glove box, totaling 10 g, and place them in a steel ball mill jar. The excess Mg can not only reduce SnCl2 to Sn, but also compensate for the magnesium loss during the sintering process.

[0064] (2) Place the steel ball mill jar from step (1) into a high-energy ball mill and ball mill for 6 hours to obtain a uniformly mixed powder;

[0065] (3) In the glove box, open the ball mill jar, weigh about 5g of the well-mixed powder and fill it into a graphite mold with a diameter of 12.7mm, and put graphite paper on both sides to prevent the sample from being squeezed out.

[0066] (4) Place the graphite mold containing powder into the discharge plasma sintering system, evacuate it to 10 Pa, heat it to 750°C at a rate of 50°C / min under a pressure of 50 MPa, hold it at this temperature for 15 minutes, and then let it cool naturally to room temperature.

[0067] (5) Remove the sintered block sample from the graphite mold, grind off the graphite paper, and you will get the disc-shaped magnesium-based thermoelectric material Mg2Si. 0.39 Sn 0.6 Sb 0.01 It has a diameter of 12.7 mm and a height of approximately 1.2 mm.

[0068] Product characterization and performance testing

[0069] I. For example Figure 2 As shown, under a scanning electron microscope, a very clear interface exists between the magnesium-based material prepared in Example 1 and the yttrium-doped zirconium oxide crucible, within an area of ​​approximately 4 × 5 mm. 2 Within the field of view, the material composition is relatively uniform and close to the weighed composition.

[0070] II. Characterization of material grain size

[0071] Instrument: eFlashHR+ Bruker electron backscatter diffractometer

[0072] method:

[0073] (1) Sample preparation: First, the sample to be tested (approximately 5 mm × 5 mm × 1.5 mm) is processed by mechanical polishing combined with ion etching or focused ion beam cutting to remove any damage to the sample surface, so as to ensure that the sample surface is flat, clean and free of residual strain / stress.

[0074] (2) Measurement of sample grain size: First, fix the prepared sample on a 70° inclined sample stage with conductive glue or 502 glue, place it in the sample chamber, select an appropriate magnification, and focus it; select an appropriate step size (about one-tenth of the grain size) and scanning area; obtain high-quality scanning images by adjusting parameters such as accelerating voltage, working distance and probe current; finally, obtain data such as average grain area and standard deviation by performing noise reduction and calibration operations through analysis software.

[0075] Example 1 yielded a magnesium-based thermoelectric material with an average grain size of approximately 130 μm, which is 6 times that of the traditional laboratory sintered sample (23 μm).

[0076] Example 2 yielded a magnesium-based thermoelectric material with an average grain size of about 5 μm, which is 25 times that of the traditional laboratory sintered sample (200 nm).

[0077] Example 3 yielded a magnesium-based thermoelectric material with an average grain size of about 5 μm, which is 5 times that of the traditional laboratory sintered sample (1 μm).

[0078] III. Characterization of the thermoelectric properties of materials

[0079] Typically, the performance of thermoelectric materials is characterized by a dimensionless thermoelectric figure of merit, zT. Where S is the Seebeck coefficient and ρ is the resistivity. Where is the thermal conductivity, and T is the absolute temperature. The power factor represents the overall electrical properties of a thermoelectric material. The Seebeck coefficient S, resistivity ρ, and thermal conductivity are obtained through measurement. The power factor and thermoelectric figure of merit zT can then be calculated.

[0080] (1) Measurement of resistivity and Seebeck coefficient

[0081] Equipment: Linseis LSR-3 Seebeck coefficient and resistance analysis system

[0082] Method: The sample to be tested was cut into strips with dimensions approximately 2 mm × 2 mm × 10 mm, such as... Figure 3 As shown, fix it between the upper and lower electrodes of the device, input the specific dimensions of the sample into the program, set the test conditions, and calculate the voltage value based on the applied current I and the measured voltage value. The resistivity of the material can be obtained from the sample cross-sectional area A and the distance d between the two probes on the sample side. In a helium atmosphere, the ambient temperature is maintained at a specific value by heating the furnace body. The sample is then heated a second time using the lower electrode block to create a temperature difference in the material. The potential difference is recorded using two probes on the side. and temperature difference The Seebeck coefficient can be calculated. .

[0083] (2) Measurement of thermal conductivity

[0084] Equipment: Linseis LFA-1000 laser thermal conductivity meter

[0085] Method: The sample to be tested was ground into a circular disc with a diameter of 10 mm or 12.7 mm and a thickness between 1 and 1.5 mm. A thin layer of graphite paint was sprayed onto its surface to improve heat conduction uniformity. The test was conducted under a helium atmosphere. The sample to be tested was placed in a sample holder, and a pulsed laser beam was directed onto the lower surface of the disc. The temperature change of the upper surface of the sample over time was recorded using an infrared thermometer, and the temperature was calculated according to the formula... The thermal diffusivity can be calculated. Where l is the thickness of the disc, This is the time required for the surface temperature of the disc to reach half of its maximum value. Furthermore, the sample density ρ can be measured using Archimedes' displacement method, and the isobaric heat capacity C... p It can be calculated using the Duron-Party law, according to the formula. The thermal conductivity of the material can be obtained. .

[0086] Example 1 yielded a magnesium-based thermoelectric material with a low axial resistivity (14 μΩ m) and a power factor reaching 32 µW cm⁻¹. -1 K -2 The thermoelectric figure of merit at room temperature, zT, is 0.8.

[0087] The resistivity of the laboratory sintered sample prepared in Comparative Example 1 was 20 μΩ m, and the power factor was 24 µW cm. -1 K -2 zT is around 0.7.

[0088] Example 2 yielded a magnesium-based thermoelectric material with a low axial resistivity (9 μΩ m) and a power factor reaching 25 µW cm⁻¹. -1 K -2 The thermoelectric figure of merit at room temperature, zT, is 0.65.

[0089] The resistivity of the laboratory sintered sample prepared in Comparative Example 2 was 36 μΩ m, and the power factor was 17 µW cm. -1 K -2 zT is around 0.6.

[0090] Example 3 yielded a magnesium-based thermoelectric material with a low axial resistivity (7.5 μΩ m) and a power factor reaching 30 µW cm⁻¹. -1 K -2 The thermoelectric figure of merit at room temperature, zT, is 0.4.

[0091] The resistivity of the laboratory sintered sample prepared in Comparative Example 3 was 9 μΩ m, and the power factor was 25 µW cm. -1 K -2 zT is around 0.35.

[0092] The characterization results of grain size and thermoelectric properties show that, compared with the traditional sintering method, the high-temperature melting device composed of a yttrium-doped zirconium oxide crucible, a tantalum crucible and a quartz tube provided by this invention can grow magnesium-based thermoelectric materials with larger grain size and better thermoelectric properties by using the high-temperature melting method.

[0093] IV. X-ray Diffraction Analysis

[0094] Figure 4 This is a comparison diagram of the X-ray diffraction patterns and standard diffraction peaks of the magnesium-based thermoelectric materials prepared in Examples 1-3 of this invention. Figure 4 It is evident that a pure phase can be obtained by using the high-temperature melting device and high-temperature melting method of this invention. Since the magnesium-silver-antimony-based alloy contains a low-temperature α phase and a high-temperature β phase, annealing at 300°C was subsequently performed to eliminate the high-temperature β phase in order to retain the α phase, which exhibits excellent thermoelectric properties.

Claims

1. A method for preparing a magnesium-based thermoelectric material, the method comprising the following steps: (1) Place the reaction raw materials of magnesium-based thermoelectric materials into a zirconium oxide crucible doped with yttrium oxide; (2) Seal the zirconium oxide crucible containing the reactants, which is doped with yttrium oxide, inside the tantalum crucible; (3) Seal the tantalum crucible obtained in step (2) into a quartz tube; (4) Place the sealed quartz tube into the swing growth furnace to carry out the grain growth and solidification of magnesium-based thermoelectric materials.

2. The preparation method according to claim 1, wherein, The reaction raw materials include: Mg and optional elements or alloys of one or more of Bi, Sb, Te, Ag, Si, Ge, Sn, Al, Zn and optional transition metals Y, Cu, Mn.

3. The preparation method according to claim 1, wherein, Step (1) includes weighing the reaction raw materials in a glove box and placing them into a yttrium-doped zirconium oxide crucible.

4. The preparation method according to claim 1, wherein, Step (2) includes sealing a yttrium-doped zirconium oxide crucible containing the reaction raw materials into a tantalum crucible in an inert atmosphere using an electric arc melting technique.

5. The preparation method according to claim 1, wherein, Step (3) is performed in a vacuum environment.

6. The preparation method according to claim 1, wherein, Step (4) includes: placing a quartz tube containing the reaction raw materials into a rocking growth furnace, heating it to 500-1050°C at a rate of 10-100°C / hour, rocking it at this temperature for 0.5-20 hours, then slowly cooling it to 300-900°C at a rate of 2-50°C / hour, maintaining it at this temperature for 1-15 days, and then cooling it with the furnace until it reaches room temperature.

7. The preparation method according to any one of claims 1 to 6, wherein, The yttrium-doped zirconium oxide crucible has an inner diameter of 13-50 mm and a height of 60-100 mm.

8. A magnesium-based thermoelectric material prepared by any one of claims 1 to 7.

9. The magnesium-based thermoelectric material according to claim 8, wherein, The average grain size of the magnesium-based thermoelectric material is 5~130 μm.

10. The magnesium-based thermoelectric material according to claim 8, wherein, The axial resistivity of the magnesium-based thermoelectric material is 7.5~14 μΩ m.

11. The magnesium-based thermoelectric material according to claim 8, wherein, The power factor of the magnesium-based thermoelectric material is 25~32µW cm⁻¹. -1 K -2 .

12. The magnesium-based thermoelectric material according to claim 8, wherein, The room temperature thermoelectric figure of merit zT of the magnesium-based thermoelectric material is 0.4~0.8.

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