Method for preparing GeTe-based thermoelectric material by eliminating Ge enrichment through chemical reaction

Abstract

The invention belongs to the technical field of preparation of high-performance thermoelectric materials, and particularly relates to a method for preparing a GeTe-based thermoelectric material by eliminating Ge enrichment through a chemical reaction. In order to further excavate the application potential of the GeTe material, the invention provides a high-performance GeTe-based thermoelectric material, the molecular formula of the high-performance GeTe-based thermoelectric material is (GeTe) 1-x (BiSbSe) x, and x is 0.03, 0.04, 0.05 or 0.06. The thermoelectric material is prepared by taking germanium particles, tellurium particles, bismuth particles, antimony particles and selenium particles as raw materials, respectively preparing GeTe and BiSbSe3 through a melting method, mixing, carrying out high-energy ball milling treatment, and carrying out spark plasma sintering to form blocks. According to the preparation method, Ge enrichment is completely eliminated through BiSbSe3 alloying reaction, so that the thermoelectric performance and the service stability of the prepared GeTe-based thermoelectric material are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing high-performance thermoelectric materials, and particularly relates to a method for preparing GeTe-based thermoelectric materials by eliminating Ge enrichment through a chemical reaction. Background Art

[0002] Thermoelectric materials can directly convert thermal energy into electrical energy and vice versa, and have broad application prospects in fields such as waste heat recovery, solid-state refrigeration, and deep space exploration. In recent years, PbTe-based thermoelectric materials have been widely used in the medium-temperature range, but the toxicity of Pb contained therein has hindered their further popularization and application. GeTe has a similar crystal structure and energy band structure to PbTe, and also has a high intrinsic ZT value, which can make up for the deficiencies of PbTe and become a promising material for thermoelectric applications in the medium-temperature region, and is expected to play an important role in related fields.

[0003] At present, the multi-effect synergistic optimization strategy has significantly improved the thermoelectric performance of GeTe materials and made important progress. However, there are still challenges in enhancing the stability and structural regulation of this material. Among them, the common Ge-rich phase segregation phenomenon in GeTe and its potential hazards have not been deeply studied, and the corresponding optimization strategies need to be improved. Although heat treatment processes such as quenching and annealing, and methods to increase the Ge vacancy formation energy can reduce the generation of Ge-rich phases and improve lattice uniformity to a certain extent, in practical applications, the effects of these methods are still not satisfactory. Therefore, in order to further explore the application potential of GeTe materials, it is urgent to explore new methods to improve their thermoelectric performance and stability. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention proposes a method for improving the performance and stability of GeTe-based thermoelectric materials by eliminating Ge enrichment through a chemical reaction. Through the BiSbSe3 alloying reaction, Ge enrichment is completely eliminated, thereby improving the phase structure stability and thermoelectric performance of the material.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a GeTe-based thermoelectric material, and the molecular formula of the GeTe-based thermoelectric material is (GeTe) 1-x (BiSbSe) x , where x = 0.03, 0.04, 0.05, 0.06.

[0007] The present invention also provides a preparation method of the above GeTe-based thermoelectric material, and the method includes the following steps:

[0008] S1. Weigh two raw materials, Ge and Te, according to the molar ratio of Ge:Te = 1:1. Then, conduct a high-temperature melting reaction under vacuum conditions, followed by quenching to room temperature. After that, perform an annealing treatment and then quench to room temperature again. After grinding the obtained ingot into powder, conduct pulse electric current pressure sintering to obtain the P-type GeTe thermoelectric material.

[0009] S2. Weigh the raw materials Bi, Sb, and Se according to the stoichiometric ratio of BiSbSe3. Then, conduct a high-temperature melting reaction under vacuum conditions, followed by quenching to room temperature. After that, perform an annealing treatment and then cool with the furnace. Grind the obtained ingot to obtain the BiSbSe3 powder raw material.

[0010] S3. Weigh the GeTe and BiSbSe3 powder raw materials according to the stoichiometric ratio of GeTe:BiSbSe3 = 1 - x:x, where x = 0.03, 0.04, 0.05, 0.06. Then, conduct high-energy ball milling under an inert gas atmosphere, followed by pulse electric current pressure sintering to prepare the GeTe-based thermoelectric material.

[0011] The thermoelectric material of the present invention uses germanium grains, tellurium grains, bismuth grains, antimony grains, and selenium grains as raw materials. GeTe and BiSbSe3 are respectively prepared by the melting method, mixed and subjected to high-energy ball milling treatment, and then formed into a block by spark plasma sintering to obtain the product. Through the BiSbSe3 alloying reaction, Ge enrichment is completely eliminated, effectively improving the thermoelectric performance and service stability of the prepared GeTe-based thermoelectric material.

[0012] Preferably, in S1, the Ge is ultra-pure germanium grains with a purity of ≥99.999%, and the Te is ultra-pure tellurium blocks with a purity of ≥99.999%.

[0013] Preferably, in S1, the high-temperature melting reaction is heated to 1173 - 1273K at a rate of 1 - 2K / min and held for 250 - 350min.

[0014] Preferably, in S1, the annealing treatment is heated to 873 - 973K at a rate of 1 - 2K / min and held for 4200 - 4500min.

[0015] Preferably, in S1 and S3, the temperature of the pulse electric current pressure sintering is 723 - 823K, the pressure is 40 - 50MPa, and the time is 4 - 6min.

[0016] Preferably, in S2, the Bi is ultra-pure Bi grains with a purity of ≥99.999%, the Sb is ultra-pure antimony grains with a purity of ≥99.999%, and the Se is ultra-pure selenium grains with a purity of ≥99.999%.

[0017] Preferably, in S2, the high-temperature melting reaction is carried out by heating to 1073 - 1273K at a rate of 1 - 2K / min and holding for 700 - 800min.

[0018] Preferably, in S2, the annealing treatment is carried out by heating to 623 - 773K at a rate of 1 - 2K / min and holding for 2500 - 3000min.

[0019] Preferably, in S3, the high-energy ball milling time is 1 - 2 hours.

[0020] Preferably, in S1 and S2, the vacuum degree of the vacuum condition is less than 10 -4 Pa.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention discloses a P-type GeTe thermoelectric material, namely a GeTe material alloyed with BiSbSe3, with the chemical formula (GeTe) 1-x (BiSbSe3) x , where x = 0.03, 0.04, 0.05, 0.06. This thermoelectric material uses germanium grains, tellurium grains, bismuth grains, antimony grains, and selenium grains as raw materials. GeTe and BiSbSe3 are respectively prepared by the melting method, mixed and subjected to high-energy ball milling treatment, and then formed into a bulk by spark plasma sintering to obtain the product. Through the high-energy ball milling process, the present invention conducts mechanical chemical reactions on the GeTe and BiSbSe3 raw materials, thereby completely eliminating the Ge-rich phase in the GeTe material and avoiding the problem that the common melting of raw materials in the research process of GeTe alloying cannot avoid Ge enrichment. In addition, through the doping of various elements, the Seebeck coefficient and thermal conductivity of the material are optimized; ultimately, the co-optimization of thermoelectric performance and structural stability is achieved, solving the problems of Ge enrichment and insufficient thermoelectric performance in P-type GeTe. Description of the Drawings

[0023] Figure 1 SEM diagrams of WQ and FC samples.

[0024] Figure 2 Cooling curves of WQ and FC samples after three cycles of DSC tests.

[0025] Figure 3 GeTe phase diagram.

[0026] Figure 4 Results of double-phase refinement of XRD tests before and after two cycles of WQ and FC samples (WQ0 and FC0 are before thermal cycling, WQ1 and FC1 are after one thermal cycle, and WQ2 and FC2 are after two thermal cycles).

[0027] Figure 5 Variation curves of electrical conductivity and lattice thermal conductivity of WQ and FC samples for 4 cycles at 373 K (a) and 773 K (b).

[0028] Figure 6 For (GeTe) 1-x (BiSbSe3) x XRD test patterns of (x = 0, 0.03, 0.04, 0.05, 0.06) samples (a); enlarged diffraction peak of (202) in (a) (b); lattice parameters and c / a values obtained by XRD refinement (c); (GeTe) 1-x (BiSbSe3) x DSC curves of (x = 0, 0.03, 0.04, 0.05, 0.06) samples (d).

[0029] Figure 7 For (GeTe) 1-x (BiSbSe3) x SEM and EDS characterizations of (x = 0, 0.03, 0.04, 0.05, 0.06).

[0030] Figure 8 For (GeTe) 1-x (BiSbSe3) x Seebeck coefficients of (x = 0, 0.03, 0.04, 0.05, 0.06) (a) and variation relationship of electrical conductivity with temperature (b).

[0031] Figure 9 For (GeTe) 1-x (BiSbSe3) x Total thermal conductivities of (x = 0, 0.03, 0.04, 0.05, 0.06) (a) and variation relationship of ZT value with temperature (b). Specific Embodiments

[0032] The following further describes the specific embodiments of the present invention. It should be noted here that the descriptions of these embodiments are for helping to understand the present invention, but do not constitute a limitation to the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] In the following embodiments, the experimental methods are all conventional methods unless otherwise specified, and the test materials used in the following embodiments can all be obtained through conventional commercial channels unless otherwise specified.

[0034] Example 1: Study on the Influence of Ge-Rich Phase on GeTe

[0035] 1. Experimental Method

[0036] 1.1. Sample preparation:

[0037] Weigh two raw materials in a glove box filled with argon according to the molar ratio of Ge:Te = 1:1, where Ge is ultra-pure germanium grains with a purity of ≥99.999% and Te is ultra-pure tellurium blocks with a purity of ≥99.999%, and a total of 6 g is weighed. Place the raw materials in the quartz tube in the order of Ge and Te. The inner diameter of the quartz tube used is 15 ± 0.2 mm, the wall thickness is 2 ± 0.2 mm, and a necking treatment is performed at a position about 100 mm from the bottom of the quartz tube. Install a barrier valve on the quartz tube in the glove box, and then transfer it to a sealing machine for vacuum pumping until the vacuum degree is less than 10 -4 Pa and then perform encapsulation. Then heat it up to 1223 K at a rate of 1 K / min, hold for 300 min for the melting reaction, then quench to room temperature, reheat it up to 923 K at a rate of 1 K / min, hold for 4320 min for annealing, and then quench to room temperature again. After obtaining the ingot, hand-grind it with a mortar for 10 min. Load the obtained powder into a graphite mold with a diameter of 12.7 mm and perform pulsed electric current pressure sintering (SPS) at a temperature of 773 K and a pressure of 45 MPa for 5 min to finally obtain a p-type GeTe thermoelectric material, simply referred to as the WQ sample. After wire-cutting the obtained GeTe thermoelectric material, grind it into a suitable size for performance testing.

[0038] At the same time, prepare another group of FC group samples. Except that the two quenches to room temperature are changed to furnace cooling to room temperature, all other procedures are the same as those in the WQ group experiment.

[0039] 1.2. Sample testing:

[0040] (1) SEM testing: After polishing the sintered WQ and FC samples with 600-mesh, 1000-mesh, 2000-mesh sandpaper and 1.5-micron polishing paste of a polishing machine, perform SEM testing.

[0041] (2) DSC testing: Take 10 mg of the WQ and FC samples respectively, load them into an aluminum crucible, heat them up to 823 K at a heating rate of 10 K / min, then cool with the equipment, and make a DSC data curve during the cooling process. Repeat the above process 3 times to obtain cyclic DSC test data.

[0042] (3) XRD test: The sintered WQ and FC samples were respectively divided into three groups. The first group was not treated. The second and third groups were heated to 773 K at a rate of 5 K / min and then cooled in the furnace. The third group was reheated to 773 K at a rate of 5 K / min and then cooled in the furnace. Then, the three groups of samples were ground in a mortar for 5 minutes, and the obtained powders were subjected to XRD test. After XRD biphasic refinement with the same refinement sequence for the three groups of data obtained, the refined data of the cyclic biphasic ratio were obtained.

[0043] (4) Thermoelectric performance test: The WQ and FC samples were polished into standard specimens, and the electrical and thermal performance tests were respectively carried out in ZEM (Seebeck coefficient / resistance measurement system) and LFA (laser flash method / laser thermal conductivity meter) equipment (manufacturer: ADVANCERIKO, model: ZEM-3 (M10)), and the thermoelectric parameters at 373 K and 773 K were respectively tested under heating conditions. Among them, the thermal conductivity was calculated by combining the thermal diffusivity (D) obtained by testing with a laser thermal conductivity meter, the density (ρ) obtained by the Archimedes drainage method, and the constant-pressure specific heat capacity Cp calculated by Dulong-Petit's law: κ = D × Cp × ρ. Combining with the total thermal conductivity calculation formula κ = κ e +κ L , through κ e = LσT, the electronic thermal conductivity was calculated, and then the lattice thermal conductivity κ L was obtained. Among them, the calculation formula of L is Among them, κ is the total thermal conductivity, κ e is the electronic thermal conductivity, κ L is the lattice thermal conductivity, L is the Lorentz constant, σ is the conductivity, T is the absolute temperature, and S is the Seebeck coefficient. During the performance test, the test was repeated 2 - 4 times without taking out the sample.

[0044] 2. Experimental results:

[0045] To systematically study the influence of the Ge-rich phase on the proportion of the GeTe phase, different quenching processes (WQ / FC) were used. Among them, the WQ sample has less Ge-rich phase, and the FC sample shows a larger Ge-rich phase, as Figure 1 presented by the two GeTe samples with different Ge-rich degrees.

[0046] Three thermal cycle tests were carried out on the FC and WQ samples, and the DSC results are as Figure 2 shown. The test results show that during the cooling process, compared with the WQ sample, the FC sample shows an additional significant exothermic peak. In addition, with the increase in the number of cycles, the intensity of the exothermic peak near 573 K gradually increases.

[0047] According to the GeTe phase diagram ( Figure 3) It can be inferred that this additional exothermic peak originates from the Te-rich region adjacent to the Ge-rich region. During the cooling process, the relatively large Ge-rich region leads to a higher Te concentration in the surrounding GeTe region compared to other regions of the matrix. According to the phase diagram analysis, the phase transformation behavior of these Te-rich regions follows the cooling path on the Te-rich side of GeTe. Along this path, the transformation temperature of GeTe from β-GeTe to α-GeTe decreases, resulting in the emergence of a new phase transformation peak near 573K. As the number of thermal cycles increases, the intensity of the exothermic peak near 573K gradually increases, indicating that the influence of the Te-rich region is accumulating. It should be noted that since the DSC uses the data of the cooling process, the temperature does not exactly match the temperature in the phase diagram, but the relevant trends are consistent.

[0048] This hypothesis was further verified by the Rietveld refinement results of the XRD analysis ( Figure 4 ). The XRD analysis showed that the phase ratios of α-GeTe and β-GeTe in the cycled samples changed significantly. Specifically, compared with the WQ sample, the FC sample exhibited a significantly higher residual amount of β-GeTe, while the WQ sample maintained a relatively stable two-phase ratio after cycling. These findings indicate that the Ge-rich region not only changes the local cooling path but also increases the residual amount of β-GeTe, thus exacerbating the instability of the material.

[0049] The influence of different Ge-rich levels on the thermal cycling stability of GeTe samples was further investigated through the thermoelectric performance cycling test diagram ( Figure 5 ). The results showed that the quenched sample (WQ) exhibited higher stability during cycling, while the conventionally cooled sample (FC) was affected by the Ge-rich phase and its performance showed significant dynamic evolution. The change in lattice thermal conductivity showed a downward trend for both samples during cycling. However, the WQ sample showed a smaller decrease in lattice thermal conductivity, reflecting higher lattice stability. In addition, due to the repair of some lattice defects during the heat treatment process, the electrical conductivity initially increased. However, as the thermal cycling continued, microcracks caused by the mismatch of thermal expansion coefficients between different phases led to a decrease in electrical conductivity. During these changes, the WQ sample showed better electrical conductivity stability than the FC sample.

[0050] Based on the above experimental results, it can be seen that minimizing the interference of the Ge-rich phase on the local phase transformation path and maintaining a stable ratio between α-GeTe and β-GeTe are crucial for improving the thermal cycling stability and long-term performance of GeTe materials.

[0051] Example 2: Elimination of Ge enrichment through a chemical reaction-driven BiSbSe3 alloying study

[0052] 1. Experimental method

[0053] 1.1. Sample preparation:

[0054] Weigh Bi, Sb, and Se raw materials with a total mass of 6 g according to the stoichiometric ratio of BiSbSe3 in a glove box filled with argon. Among them, Bi is ultrapure Bi grains with a purity of ≥99.999%, Sb is ultrapure antimony grains with a purity of ≥99.999%, and Se is ultrapure selenium grains with a purity of ≥99.999%. Place the raw materials in a quartz tube. The inner diameter of the quartz tube used is 15 ± 0.2 mm, the wall thickness is 2 ± 0.2 mm, and a necking treatment is made at a position about 100 mm from the bottom of the quartz tube. Install a barrier valve on the quartz tube in the glove box, and then transfer it to a sealing machine for vacuum pumping until the vacuum degree is less than 10 -4 Pa and then encapsulate. Then heat it up to 1173 K at a rate of 1 K / min, keep it warm for 720 min for melting reaction, then quench it to room temperature, and reheat it to 673 K at a rate of 1 K / min and keep it warm for 2880 min for annealing, and then cool it in the furnace. After obtaining the ingot, use a mortar to grind it by hand for 10 min to obtain the BiSbSe3 powder raw material.

[0055] Weigh a total mass of 6 g of the GeTe powder and BiSbSe3 powder prepared according to the WQ sample process in Example 1 according to the stoichiometric ratio of GeTe:BiSbSe3 = 1 - x:x (x = 0.03, 0.04, 0.05, 0.06). Then load it into a ball milling jar under an argon atmosphere, add two ball milling beads of 8.5 g and 1 g respectively, and then perform high-energy ball milling for 1 hour (the model of the ball mill used is: SPEX8000MMIXER / MILL). After that, sinter and test the obtained powder according to the sintering method of the WQ sample (load the obtained powder into a graphite mold with a diameter of 12.7 mm and perform pulsed electric current pressure sintering at a temperature of 500 °C under a pressure of 45 MPa for 5 min) and the testing method.

[0056] 1.2. Sample testing:

[0057] (1) SEM: The SEM test process is the same as that of the WQ sample.

[0058] (2) DSC: Take 10 mg of alloyed samples (GeTe) of each concentration respectively 1-x (BiSbSe3) x , load them into an aluminum crucible, heat them up to 823 K at a heating rate of 10 K / min, collect the DSC data curve during the heating process, and cool with the equipment.

[0059] (3) XRD test: For the alloyed samples (GeTe) of each concentration after sintering 1-x (BiSbSe3) xThe powder was ground in a mortar for 5 minutes, and then XRD test was performed on the obtained powder. The obtained data were refined to obtain lattice parameter information.

[0060] (4) Thermoelectric performance test: (GeTe) 1-x (BiSbSe3) x The samples were polished into standard specimens, and the electrical and thermal properties were tested in ZEM and LFA equipment respectively. The thermoelectric parameters were tested at room temperature and at various temperature points within the range of 323K-773K with an interval of 50K.

[0061] 2. Experimental results

[0062] XRD results ( Figure 6 a and 6b) show that the diffraction peaks of all samples are consistent with the characteristic peaks of rhombohedral GeTe (PDF#00-47-1049), and the Ge element peak in the doped sample completely disappears. With the increase of BiSbSe3 alloy content, the (202) crystal plane moves significantly to the right. This movement is mainly attributed to the smaller Se atoms (198pm) replacing Te (221pm), forming substitutional point defects, resulting in the contraction of the anion framework. In addition, the (024) and (220) crystal planes gradually merge, indicating that the incorporation of BiSbSe3 causes the distortion of the GeTe matrix. This phenomenon is consistent with the lattice parameter calculation results ( Figure 6 c), showing that as the BiSbSe3 doping ratio increases, the c-axis length gradually decreases and the c / a ratio decreases. The above results further confirm the distortion of the GeTe lattice from the rhombohedral phase to the cubic phase.

[0063] DSC results further supported the above results ( Figure 6 d). As the doping level of BiSbSe3 increases, the rhombohedral lattice gradually relaxes, resulting in a gradual decrease in the phase transition temperature. It is worth noting that in the DSC test, when the alloying ratio x>0.03, a second small endothermic peak appears near 673K, indicating the formation of a second phase GeSe. Since the concentration of GeSe is below the detection limit, GeSe is not detected in the XRD analysis.

[0064] SEM images ( Figure 7 ) clearly shows that the Ge-rich phase disappears in the sample after BiSbSe3 doping. It is speculated that the alloying process effectively eliminates the Ge-rich phase through the following chemical reactions:

[0065] 2GeTe+BiSbSe3+Ge→3GeSe+Bi Ge +Sb Ge +2Te Te +2e - ;

[0066] In this reaction, mechanical alloying combines with the chemical potential gradient caused by the uneven distribution of elements in BiSbSe3 to drive the reaction of anions with free Ge and Ge-rich phases, forming a GeSe solid solution that is more compatible with the matrix. As the chemical reaction progresses, a large number of point defects are generated, and the Ge-rich phase is gradually eliminated.

[0067] (GeTe) 1-x (BiSbSe3) x The Seebeck coefficient of Figure 8 varies with temperature as shown in -1 a. As the doping amount of BiSbSe3 increases, S increases from 28 μV K -1 in pure GeTe to 101 μV K

[0068] in the sample with x = 0.06 at 300 K. The substitution of high-valence cations Bi and Sb for Ge and the lattice distortion caused by the substitution of Se for Te during the chemical reaction-driven process induce band convergence, enhance the heavy band effect, and effectively improve the Seebeck coefficient. Figure 8 Meanwhile, the lattice defects and second-phase scattering introduced during the chemical reaction-driven process lead to a decrease in the carrier mobility and a significant decrease in the electrical conductivity ( -1 b). At room temperature, the electrical conductivity drops sharply from 6942 S cm -1 in pure GeTe to 1050 S cm -1 in the sample with x = 0.06. However, this adverse effect is also compensated by the significant reduction in the total thermal conductivity due to the significant reduction in the electronic thermal conductivity. At room temperature, the thermal conductivity of the sample with x = 0.06 is 1.45 W m -1 K -1 while that of pure GeTe is 6.62 Wm -1 ( Figure 9 a).

[0069] In summary, the doping of BiSbSe3 significantly improves the ZT value of GeTe. The sample with x = 0.04 achieves a ZT value of 1.69 at 773 K, which is approximately 50% higher than that of the GeTe sample ( Figure 9 b). It can be seen that through the BiSbSe3 alloying reaction of the present invention, Ge enrichment is completely eliminated, the phase ratio evolution degree during the thermal cycle process is smaller, and the phase structure stability of the material is improved; at the same time, by synergistically optimizing the electrical and thermal properties (the thermal conductivity of pure GeTe is too high), the thermoelectric conversion efficiency (ZT value is increased) is improved, thereby also improving the thermoelectric properties of the material.

[0070] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principles and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A GeTe-based thermoelectric material, characterized in that, The molecular formula of the GeTe-based thermoelectric material is (GeTe) 1-x (BiSbSe) x , where x = 0.03, 0.04, 0.05, 0.

06.

2. The preparation method of the GeTe-based thermoelectric material according to claim 1, characterized in that It includes the following steps: S1. Weigh two raw materials, Ge and Te, according to the molar ratio of Ge:Te = 1:

1. Then, conduct a high-temperature melting reaction under vacuum conditions, followed by quenching to room temperature. After that, perform an annealing treatment, and then quench to room temperature again. Grind the obtained ingot into powder, and then conduct pulsed electric current pressure sintering to obtain a p-type GeTe thermoelectric material. S2. Weigh raw materials of Bi, Sb, and Se according to the stoichiometric ratio of BiSbSe3. Then, conduct a high-temperature melting reaction under vacuum conditions, followed by quenching to room temperature. After that, perform an annealing treatment, and cool it in the furnace. Grind the obtained ingot to obtain BiSbSe3 powder raw materials. S3. Weigh GeTe and BiSbSe3 powder raw materials according to the stoichiometric ratio of GeTe:BiSbSe3 = 1 - x:x, where x = 0.03, 0.04, 0.05, 0.

06. Then, conduct high-energy ball milling under an inert gas atmosphere, and then conduct pulsed electric current pressure sintering to prepare a GeTe-based thermoelectric material.

3. The preparation method of the GeTe-based thermoelectric material according to claim 2, characterized in that, In S1, the Ge is ultra-pure germanium grains with a purity of ≥99.999%, and the Te is ultra-pure tellurium blocks with a purity of ≥99.999%.

4. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein, In S1, the high-temperature melting reaction is heated to 1173 - 1273K at a rate of 1 - 2K / min and held for 250 - 350min.

5. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein, In S1, the annealing treatment is heated to 873 - 973K at a rate of 1 - 2K / min and held for 4200 - 4500min.

6. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein In S1 and S3, the temperature of the pulsed electric current pressure sintering is 723 - 823K, the pressure is 40 - 50MPa, and the time is 4 - 6min.

7. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein, In S2, the Bi is ultra-pure Bi grains with a purity of ≥99.999%, the Sb is ultra-pure antimony grains with a purity of ≥99.999%, and the Se is ultra-pure selenium grains with a purity of ≥99.999%.

8. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein, In S2, the high-temperature melting reaction is heated to 1073 - 1273K at a rate of 1 - 2K / min and held for 700 - 800min.

9. The preparation method of the GeTe-based thermoelectric material according to claim 2, wherein, In S2, the annealing treatment is heated to 623 - 773K at a rate of 1 - 2K / min and held for 2500 - 3000min.

10. The preparation method of the GeTe-based thermoelectric material according to claim 2, characterized in that, In S3, the time of the high-energy ball milling is 1 - 2 hours.

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