CN116903370A - SnTe-based thermoelectric material with multi-scale nano composite structure and preparation method thereof - Google Patents
SnTe-based thermoelectric material with multi-scale nano composite structure and preparation method thereof Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 79
- 229910005642 SnTe Inorganic materials 0.000 title claims abstract description 48
- 239000002114 nanocomposite Substances 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 239000000126 substance Substances 0.000 claims abstract description 40
- 229910052802 copper Inorganic materials 0.000 claims abstract description 39
- 229910052751 metal Inorganic materials 0.000 claims abstract description 24
- 239000002184 metal Substances 0.000 claims abstract description 24
- 238000000137 annealing Methods 0.000 claims abstract description 21
- 238000010791 quenching Methods 0.000 claims abstract description 18
- 230000000171 quenching effect Effects 0.000 claims abstract description 18
- 238000005245 sintering Methods 0.000 claims abstract description 12
- 238000000227 grinding Methods 0.000 claims abstract description 11
- 239000000843 powder Substances 0.000 claims abstract description 11
- 239000002994 raw material Substances 0.000 claims abstract description 11
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- 239000011261 inert gas Substances 0.000 claims description 9
- 238000003303 reheating Methods 0.000 claims description 9
- 229910052727 yttrium Inorganic materials 0.000 claims description 9
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Abstract
The invention discloses a SnTe-based thermoelectric material and a preparation method thereof, relates to the field of thermoelectric materials, and in particular relates to a SnTe-based thermoelectric material with a multi-scale nano composite structure and a preparation method thereof. The thermoelectric material has a chemical formula of Sn 1‑x Y x Te‑5％Cu 2 Te, wherein x is 0, 0.01, 0.03,0.05 or 0.07, which is prepared by taking a high-purity metal simple substance as a raw material according to the chemical metering ratio of the chemical formulaSealing the tube by using an empty flame, quenching by using a melting reaction, annealing at a high temperature, grinding into powder, and performing vacuum discharge plasma sintering to obtain the block SnTe-based thermoelectric material. Compared with the prior art, the hole carrier concentration and the energy band structure of the SnTe material are optimized by co-doping the Cu and the Y with the SnTe. Meanwhile, the Y solid solubility is improved, so that a multi-scale nano structure is formed in situ in the SnTe, the heat conductivity of the SnTe is further reduced, and the thermoelectric performance of the SnTe material is greatly improved.
Description
Technical Field
The invention relates to the technical field of new energy material science, in particular to a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure.
Background
Thermoelectric materials play a key role in the development of sustainable energy-saving technology, thermoelectric equipment can directly convert heat energy into electric energy by utilizing a thermoelectric power generation mode, and thermoelectric power generation is a full-static direct power generation mode for converting heat energy into electric energy by utilizing thermoelectric conversion materials. Theoretically, these thermoelectric devices can use any heat source, including solar energy and waste heat, the energy cleaning properties of which have been of great interest. In addition, the thermoelectric devices have the advantages of reliable performance, no noise, no abrasion, no leakage, flexible movement and the like, and are applied to various fields of aerospace, medicine, microelectronics and the like.
The conversion efficiency of the thermoelectric material is determined by the figure of merit zt=s 2 σT/(κ e +κ lat ) Evaluation was performed wherein S, σ, T, κ e And kappa (kappa) lat Respectively the seebeck coefficient, electrical conductivity, absolute temperature, carrier thermal conductivity and lattice thermal conductivity. However, the mutual coupling relationship between these parameters prevents the realization of high ZT values.
The SnTe-based thermoelectric material is a nontoxic and easy-to-prepare intermediate-temperature TE material, and is successfully applied to the fields of deep space exploration, waste heat recovery and the like. Has the same crystal structure and similar energy band structure as PbTe and is environment-friendly, so that the PbTe is widely used as a potential substitute of toxic PbTe. However, due to the large amount of intrinsic Sn voids in SnTeThe bits result in high hole carrier concentrations, low seebeck coefficients, and relatively high electron thermal conductivities, with poor intrinsic SnTe thermoelectric properties. The thermal conductivity of SnTe can be effectively reduced by introducing some extrinsic elements, so that the thermoelectric figure of merit of the SnTe is improved. Studies have shown (Interstitial Point Defect Scattering Contributing to High Thermoelectric Performance in SnTe.advanced Electronic Materials,2016,2.DOI: 10.1002/aelm.20160019), snTe solid solution copper telluride (Cu 2 Te) is capable of forming a large number of interstitial copper defects, resulting in a significant reduction in lattice thermal conductivity due to the strong phonon scattering mechanism of interstitial copper. Although the work effectively reduces the thermoelectric rate of the SnTe system and improves the thermoelectric performance to a certain extent, the overall Seebeck coefficient is not obviously improved, the thermoelectric figure of merit ZT is still smaller, and the thermoelectric performance is still to be optimized.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention aims to provide the SnTe-based thermoelectric material which is directly used for researching thermoelectric mechanism, and has the advantages of simple preparation process, short experimental period and larger thermoelectric figure-of-merit improvement range.
The aim of the invention is achieved by the following technical scheme:
the invention provides a preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure, which comprises the following steps:
s1: under the protection of inert gas, the formula Sn 1-x Y x Te-5％Cu 2 Weighing Te, sn, cu and Y which are metal simple substance materials according to the stoichiometric ratio of Te, wherein x is 0, 0.01, 0.03,0.05 or 0.07, uniformly mixing the simple substance materials, transferring the mixed materials into a quartz tube, and sealing the tube by flame in a vacuum environment by utilizing an oxyhydrogen machine;
s2: heating the quartz tube vacuum-packaged in the step S1 in a box furnace under a vacuum condition, fully reacting raw materials in a high-temperature melting state, and quenching to obtain an ingot;
s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing;
s4: fully grinding the cast ingot obtained in the step S3 into fine powder, and then carrying out spark plasma sintering under certain conditions to obtain a high-density block SnTe-based thermoelectric material;
further, in S1, the purity of each metal simple substance is not lower than 99.999 percent respectively;
further, in S2, the process conditions of the melting reaction include: raising the temperature in the quartz tube from room temperature to 1200-1300K within 6-8 hours, preserving the heat for 8-12 hours, and immediately placing the quartz tube into supersaturated brine at room temperature for quenching after the heat preservation is finished; preferably, the temperature is raised to 1273k; preferably, the temperature is kept for 10 hours;
further, in S3, the annealing process includes: heating the quartz tube to 900-950K from room temperature within 3-5 hours, preserving heat for 1-3 days, and then cooling to room temperature; preferably, the temperature is raised to 1273k; preferably, the incubation is for 3 days;
further, in S4, the spark plasma sintering process includes: vacuumizing the reaction system, and sintering for 3-10 min under Ar protection and under the conditions of 773-823K and 45-55 MPa; preferably, the temperature is 823k; preferably, the pressure is 50MPa; preferably, the sintering time is 5 minutes.
Advantageous effects
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention fixes Cu with specific concentration in SnTe 2 Based on the research of Te, rare earth element Y with specific concentration is further doped. With the addition of Y, on one hand, the Y filled Sn vacancies reduce the hole carrier concentration, and meanwhile, the energy offset between the light and heavy hole valence bands is reduced to a certain extent, so that the Seebeck coefficient in the whole measurement temperature range is improved; on the other hand, microstructure characterization shows that in a Y high doping system, Y is taken as in-situ grown Y 2 Te 3 A multi-scale nano second phase structure exists in SnTe, and these multi-scale nano structures are very beneficial to phonon scattering enhancement, which further significantly reduces the lattice thermal conductivity of the compound. Finally, at nominal composition Sn 0.97 Y 0.03 Te-5％Cu 2 In Te samples, zT peak values of up to-1.2 were obtained at 823K7, the thermoelectric performance of the material is greatly improved.
Drawings
FIG. 1 shows the composition SnTe-y% Cu 2 A Seebeck coefficient and ZT value dependence graph of Te with temperature;
FIG. 2 shows Sn of different compositions 1-x Y x Te-5％Cu 2 XRD pattern of Te;
FIG. 3 is Sn 1-x Y x Te-5％Cu 2 Te resistivity versus temperature dependence graph;
FIG. 4 is Sn 1-x Y x Te-5％Cu 2 A Seebeck coefficient and temperature dependence graph of Te;
FIG. 5 is Sn 1-x Y x Te-5％Cu 2 A plot of Te as a function of room temperature carrier concentration and mobility as a function of Y content;
FIG. 6 is Sn 1-x Y x Te-5％Cu 2 A power factor and temperature dependence graph of Te;
FIG. 7 is Sn 0.97 Y 0.03 Te-5％Cu 2 FSEM pictures of Te bulk products at high magnification of free fracture surface;
FIG. 8 is Sn 1-x Y x Te-5％Cu 2 A plot of total thermal conductivity, lattice thermal conductivity, and temperature dependence of Te;
FIG. 9 is Sn 1-x Y x Te-5％Cu 2 And a graph of ZT value and temperature dependence of Te.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
Example 1
A preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure comprises the following steps:
s1: under the protection of inert gas, snTe-5% Cu according to chemical formula 2 The stoichiometric ratio of Te is to weigh the Te, sn, cu and Y of each metal simple substance, the purity of each metal simple substance is not lower than 99.999%, then the single substance materials are evenly mixed and transferred to a quartz tubeIn the process, a oxyhydrogen machine is utilized to seal a tube by flame in a vacuum environment; s2: heating the quartz tube subjected to vacuum encapsulation in the step S1 in a box furnace, fully reacting raw materials in a high-temperature melting state, quenching to obtain an ingot, heating the interior of the quartz tube to 1280K from room temperature within 8 hours, preserving heat for 8 hours, and immediately quenching to room temperature to obtain the ingot after the heat preservation is finished; s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 920K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 823K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the high-density block thermoelectric material. Further, in S3, the annealing process includes: heating the quartz tube to 940K from room temperature within 3-5 hours, preserving heat for 3 days, and then cooling to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 800K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the high-density block thermoelectric material.
Example 2
A preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure comprises the following steps:
s1: under the protection of inert gas, sn according to chemical formula 0.99 Y 0.01 Te-5％Cu 2 The stoichiometric ratio of Te is to weigh the metal simple substance materials Te, sn, cu and Y, the purity of each metal simple substance is not lower than 99.999 percent, then the metal simple substance materials are evenly mixed and transferred into a quartz tube, and flame sealing is carried out in a vacuum environment by utilizing an oxyhydrogen machine; s2: heating the quartz tube subjected to vacuum encapsulation in the step S1 in a box furnace, fully reacting raw materials in a high-temperature melting state, quenching to obtain an ingot, heating the quartz tube to 1280K from room temperature within 6 hours, preserving heat for 8 hours, and immediately quenching to room temperature after the heat preservation is finished to obtain the ingot; s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 3 hours, the quartz tube is heated up to 920K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: will be S3And (3) fully grinding the cast ingot into fine powder, and then performing spark plasma sintering under the conditions of an absolute vacuum, a sintering temperature of 820K, a pressure of 50MPa and a time of 5min to obtain the high-density block-shaped thermoelectric material.
Example 3
A preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure comprises the following steps:
s1: under the protection of inert gas, sn according to chemical formula 0.97 Y 0.03 Te-5％Cu 2 The stoichiometric ratio of Te is to weigh the metal simple substance materials Te, sn, cu and Y, the purity of each metal simple substance is not lower than 99.999 percent, then the metal simple substance materials are evenly mixed and transferred into a quartz tube, and flame sealing is carried out in a vacuum environment by utilizing an oxyhydrogen machine; s2: heating the quartz tube subjected to vacuum encapsulation in the step S1 in a box furnace to enable raw materials to fully react in a high-temperature melting state, quenching to obtain an ingot, heating the inside of the quartz tube to 1275K from room temperature within 8 hours, preserving heat for 8 hours, and immediately quenching to room temperature to obtain the ingot after the heat preservation is finished; s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 923K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 820K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the high-density block thermoelectric material.
Example 4
A preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure comprises the following steps:
s1: under the protection of inert gas, sn according to chemical formula 0.95 Y 0.05 Te-5％Cu 2 The stoichiometric ratio of Te is to weigh the metal simple substance materials Te, sn, cu and Y, the purity of each metal simple substance is not lower than 99.999 percent, then the metal simple substance materials are evenly mixed and transferred into a quartz tube, and flame sealing is carried out in a vacuum environment by utilizing an oxyhydrogen machine; s2: heating the quartz tube vacuum-packaged in the step S1 in a box furnace to fully melt the raw materials at a high temperatureReacting, quenching to obtain an ingot, heating the quartz tube to 1273K from room temperature within 7 hours, preserving heat for 10 hours, and immediately quenching to room temperature after the heat preservation is finished to obtain the ingot; s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 923K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 823K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the high-density block thermoelectric material.
Example 5
A preparation method of a SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure comprises the following steps:
s1: under the protection of inert gas, sn according to chemical formula 0.93 Y 0.07 Te-5％Cu 2 The stoichiometric ratio of Te is to weigh the metal simple substance materials Te, sn, cu and Y, the purity of each metal simple substance is not lower than 99.999 percent, then the metal simple substance materials are evenly mixed and transferred into a quartz tube, and flame sealing is carried out in a vacuum environment by utilizing an oxyhydrogen machine; s2: heating the quartz tube subjected to vacuum encapsulation in the step S1 in a box furnace to enable raw materials to fully react in a high-temperature melting state, quenching to obtain an ingot, heating the inside of the quartz tube to 1273K from room temperature within 8 hours, preserving heat for 10 hours, and immediately quenching to room temperature to obtain the ingot after the heat preservation is finished; s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 920K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 823K, the pressure of 55MPa and the time of 5min under absolute vacuum to obtain the high-density block thermoelectric material.
Experimental example
Experimental example (one): base material SnTe-5% Cu 2 Screening of Te
In order to compare the chemical properties of the material of the invention, the chemical formulas are SnTe and SnTe-3% Cu 2 Te、SnTe-5％Cu 2 Te、SnTe-7％Cu 2 Te is prepared into SnTe-y% Cu with different concentrations according to the following preparation method 2 Te (y=0, 3, 5, 7, 9) block material, the preparation method is as follows:
s1: under the inert gas environment, the Cu is expressed as SnTe-y% 2 The stoichiometric ratio of Te (y=0, 3, 5, 7, 9) is used for weighing the Te, sn and Cu metal single-substance raw materials, the purity of each metal single-substance raw material is not lower than 99.999%, then the single-substance raw materials are uniformly mixed and transferred into a quartz tube, and flame sealing is carried out by utilizing an oxyhydrogen machine under the vacuum environment with absolute vacuum degree not more than 0.1 Pa; s2: heating the vacuum-packaged quartz tube in the step S1 to 1273K from room temperature in a box furnace for 8 hours, preserving heat for 10 hours, and immediately quenching the quartz tube to room temperature after the heat preservation is finished to obtain an ingot; s3: reheating the ingot of S2, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 923K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 823K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the SnTe-based block thermoelectric material with high density.
The thermoelectric material SnTe-y% Cu is obtained by testing the thermoelectric performance 2 The seebeck coefficient of Te and the dimensionless thermoelectric figure of merit ZT are shown in fig. 1 (a, b). As can be seen, cu 2 And after Te is in solid solution with SnTe, the thermoelectric performance is optimized, and when the solid solubility is 5%, the effect of improving ZT value is optimal. Therefore, we select SnTe-5% Cu in the next step Cu and Y co-doped SnTe system 2 Te was used as a base material. Experimental example (ii): sn (Sn) 1-x Y x Te-5％Cu 2 Screening of Te
In order to compare the chemical properties of the material, for the SnTe-based high-performance thermoelectric material with a multi-scale nano composite structure, the chemical formula of the material is Sn 1-x Y x Te-5％Cu 2 Te (x=0, 0.01, 0.03,0.05, 0.07), sn of different concentrations was obtained according to the following preparation method 1-x Y x Te-5％Cu 2 Te block material, the preparation method is as follows:
s1: chemical treatment under inert gas environmentSn (Sn) 1-x Y x Te-5％Cu 2 The stoichiometric ratio of Te is to weigh Te, sn, cu and Y as metal simple substance materials, the purity of each metal simple substance is not lower than 99.999 percent, then the metal simple substance materials are uniformly mixed and transferred into a quartz tube, and flame sealing is carried out by utilizing an oxyhydrogen machine under the vacuum environment with the absolute vacuum degree not more than 0.1 Pa; s2: heating the vacuum-packaged quartz tube in the step S1 to 1273K from room temperature in a box furnace for 8 hours, preserving heat for 10 hours, and immediately quenching the quartz tube to room temperature after the heat preservation is finished to obtain an ingot; s3: reheating the ingot of S2, and performing high-temperature annealing, wherein the annealing process comprises the following steps: within 5 hours, the quartz tube is heated up to 923K from room temperature, kept warm for 3 days, and then cooled down to room temperature; s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then performing spark plasma sintering at the sintering temperature of 823K, the pressure of 50MPa and the time of 5min under absolute vacuum to obtain the SnTe-based block thermoelectric material with high density.
Sn at different Y concentrations by X-ray diffraction (XRD) 1-x Y x Te-5％Cu 2 The Te thermoelectric material was subjected to phase analysis as shown in fig. 2, in which the ordinate Intensity represents the Intensity of the diffraction peak and the abscissa 2θ represents the angle of the diffraction peak. By comparing with a standard PDF card of SnTe, the diffraction peak shows single-phase behavior, and the main phase can be attributed to a SnTe cubic structure. In addition, small amounts of Y occur in samples highly doped with Y (x.gtoreq.0.03) 2 Te 3 The impurity phase was further confirmed from SEM and EDS analysis.
And (3) testing the electrical properties of the block thermoelectric material at 50-550 ℃ by using a thermoelectric property evaluation device (CTA-3) to obtain the corresponding resistivity and Seebeck coefficient. The test results are shown in fig. 3 and 4, respectively. The resistivity and the Seebeck coefficient of the doped material both tend to increase with the increase of the Y doping amount. The increase in resistivity is caused by a decrease in hole carrier concentration, as shown in fig. 5. The increase in seebeck coefficient results from a degree of convergence of the valence band. However, when Y reaches the solid solution limit, the seebeck coefficient falls back with the generation of the impurity phase.
The Power Factor (PF) characterizes the electrical transmission capacity of the thermoelectric material, as shown in fig. 6, the ordinate PF represents the power factor, and the abscissa T represents the temperature. After doping, due to the influence of general conductivity and high Seebeck coefficient, a higher power factor is finally obtained, and the thermoelectric material has better electric transmission performance.
For Sn in the examples 0.97 Y 0.03 Te-5％Cu 2 And analyzing the free fracture surface morphology of the Te thermoelectric compound block material sample. As shown in fig. 7, wherein fig. 7 (b) and (d) are high-magnification diagrams of fig. 7 (a) and (c), respectively. As can be seen from fig. 7 (a) and (b), after the doped Y content exceeds the solid solution limit, it was found that nano second phases with uniform size (50-100 nm) were precipitated in situ at the SnTe matrix grain boundaries. By EDS analysis, the main component of these nanostructure aggregation regions is Y 2 Te 3 The other regions are Sn 0.97 Y 0.03 Te-5％Cu 2 Te matrix. At the same time, finer Y was observed at these nanoscale Y microstructured surfaces 2 Te 3 Nanostructure (10-20 nm). No similar microstructure was found in the Y low doping amount. The invention can control the content of doping elements to effectively adjust the microstructure of the SnTe-based thermoelectric material.
The thermal conductivity of the bulk material was tested at a temperature of 50-550 c using a laser thermal conductivity meter model LFA457, manufactured by the german relaxation company. As shown in FIG. 8, the thermal conductivity of the samples with different Y doping concentrations varies with temperature, and it is known that the total thermal conductivity κ after Y doping tot Is further suppressed. This drop is due to lighter and smaller Y 3+ Entering Sn 2+ The phonon scattering process is exacerbated by the quality fluctuations and lattice distortions at the sites. In addition, due to Y 2 Te 3 The advent of multi-scale nanostructures, sn with supersaturated solid solubility 1-x Y x Te-5％Cu 2 The total heat conductivity of Te alloy (x= 0.03,0.05,0.07) was reduced by a greater extent than that of the light alloy sample (x=0.01). Wherein, when the doping amount of Y is 5%, the lattice thermal conductivity reaches the minimum value of 0.43Wm at 823K -1 K -1 . This particular in-situ multi-scale nanocomposite structure greatly enhances the range of phonon scattering, resulting in more frequency-type phonons being blocked by this particular structure and thus greatlyThe amplitude reduces the lattice thermal conductivity of the material.
Through testing the electric conductivity and the heat conductivity, the thermoelectric material Sn can be calculated 1-x Y x Te-5％Cu 2 Dimensionless thermoelectric figure of merit ZT for Te is shown in fig. 9. The thermoelectric figure of merit after doping Y on the basis of SnTe copper alloying shows great improvement, and the ZT value reaches 1.27 when 823K, compared with the intrinsic SnTe thermoelectric material, the thermoelectric material has a remarkable improvement of nearly 217%. Therefore, has strong application prospect.
The embodiments described above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the present invention should be made in the equivalent manner, and are included in the scope of the present invention.
Claims (8)
1. The preparation method of the SnTe-based high-performance thermoelectric material with the multi-scale nano composite structure is characterized by comprising the following steps of:
s1: under the protection of inert gas, the formula Sn 1-x Y x Te-5％Cu 2 Weighing Te, sn, cu and Y which are metal simple substance materials according to the stoichiometric ratio of Te, wherein x is 0, 0.01, 0.03,0.05 or 0.07, uniformly mixing the simple substance materials, transferring the mixed materials into a quartz tube, and sealing the tube by flame in a vacuum environment by utilizing an oxyhydrogen machine;
s2: heating the quartz tube vacuum-packaged in the step S1 in a box furnace under a vacuum condition, fully reacting raw materials in a high-temperature melting state, and quenching to obtain an ingot;
s3: reheating the ingot of S2 under vacuum condition, and performing high-temperature annealing;
s4: and (3) fully grinding the cast ingot obtained in the step (S3) into fine powder, and then carrying out spark plasma sintering under certain conditions to obtain the high-density block SnTe-based thermoelectric material.
2. The method for producing a SnTe-based high performance thermoelectric material having a multi-scale nanocomposite structure according to claim 1, wherein in S1, the purity of each metal element is not lower than 99.999%, respectively.
3. The method for preparing a SnTe-based high performance thermoelectric material having a multi-scale nanocomposite structure according to claim 1, wherein in S2, the process conditions of the melting reaction include: and (3) raising the temperature in the quartz tube from room temperature to 1200-1300K within 6-8 hours, preserving the heat for 8-12 hours, and immediately placing the quartz tube into supersaturated brine at room temperature for quenching after the heat preservation is finished.
4. The method for preparing a SnTe-based high performance thermoelectric material having a multi-scale nanocomposite structure according to claim 3, wherein in S2, the process conditions of the melting reaction include: and (3) raising the temperature in the quartz tube to 1273K from room temperature within 8 hours, preserving the heat for 10 hours, and immediately placing the quartz tube into supersaturated saline solution at room temperature for quenching after the heat preservation is finished.
5. The method for preparing a SnTe-based high performance thermoelectric material having a multi-scale nanocomposite structure according to claim 1, wherein in S3, the annealing process comprises: and (3) heating the quartz tube to 900-950K from room temperature within 3-5 hours, preserving heat for 1-3 days, and then cooling to room temperature.
6. The method for preparing a SnTe-based high performance thermoelectric material having a multi-scale nanocomposite structure according to claim 5, wherein the annealing process comprises: within 5 hours, the quartz tube was warmed from room temperature to 923K, incubated for 3 days, and then cooled to room temperature.
7. The method for preparing a SnTe-based high performance thermoelectric material with a multi-scale nanocomposite structure according to claim 1, wherein in S4, the spark plasma sintering process comprises: vacuumizing the reaction system, and sintering for 3-10 min under the protection of Ar at the temperature of 773-823K and the pressure of 45-55 MPa.
8. The method for preparing a SnTe-based high performance thermoelectric material with a multi-scale nanocomposite structure according to claim 7, wherein in S4, the spark plasma sintering process comprises: the reaction system is vacuumized, and then sintered for 5min under the protection of Ar, the temperature is 823K, and the pressure is 50 MPa.
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