MnTe alloying regulated agsbt e2-based thermoelectric material and preparation and application thereof

Abstract

The application relates to the technical field of thermoelectric materials, in particular to a MnTe alloying-regulated AgSbTe2-based thermoelectric material and preparation and application thereof. Through the MnTe alloying strategy, local composition fluctuation and lattice distortion are induced in the AgSbTe2 matrix, sub-micron scale Ag2Te second phases and Mn-Te enrichment regions are formed, intrinsic Ag / Sb cation disorder is combined, a multi-scale phonon scattering network is constructed, the propagation of phonons with different frequencies is effectively inhibited, the lattice thermal conductivity is significantly reduced, meanwhile, through carrier concentration optimization and Fermi level regulation, the Seebeck coefficient is effectively improved while the reasonable electrical conductivity is maintained, the power factor of the material is obviously improved, and therefore, the thermoelectric performance of the MnTe solid solution sample is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric materials technology, and in particular to an AgSbTe2-based thermoelectric material with MnTe alloying control, its preparation and application. Background Technology

[0002] Thermoelectric materials are a class of functional materials capable of directly converting heat energy into electrical energy, and they have broad application prospects in fields such as industrial waste heat recovery, automobile exhaust power generation, and energy utilization. The performance of thermoelectric materials is typically expressed as the dimensionless thermoelectric figure of merit. zT To characterize, where zT =S 2 σT / κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature. The key to achieving high-performance thermoelectric materials lies in improving the power factor (ST / κ). 2 While reducing thermal conductivity (σ), the Seebeck coefficient, electrical conductivity, and thermal conductivity are inherently coupled, making it difficult to independently control the electrothermal transport parameters, thus limiting further improvements in thermoelectric performance.

[0003] AgSbTe2 is a typical mid-temperature p-type thermoelectric material with a NaCl-like disordered crystal structure and space group Fm. In its crystal structure, Ag and Sb atoms randomly occupy cation sites, while Te atoms occupy anion sites. Due to the disordered distribution of the cation sublattice and the interfacial scattering effect between the Ag₂Te and Sb₂Te₃ second phases, this material exhibits a low intrinsic thermal conductivity, typically around 0.5–0.7 W·m⁻¹. -1 ·K -1 Within an appropriate carrier concentration range, this system can achieve a high Seebeck coefficient and relatively stable electrical transport properties. However, existing AgSbTe2-based materials still face certain technical challenges. On the one hand, the carrier mobility is limited due to lattice disorder and impurity phases, resulting in low electrical conductivity and limited potential for power factor improvement. On the other hand, microstructure evolution is easily accompanied by compositional adjustments or heat treatment, which affects performance stability.

[0004] Currently, related technologies improve thermoelectric performance through element doping, alloying, or constructing composite structures. However, it remains challenging to further reduce thermal conductivity while improving power factor, and it is difficult to achieve effective synergistic optimization of electrical and thermal transport performance.

[0005] Therefore, developing a simple, efficient, and reproducible preparation method to achieve synergistic optimization of thermoelectric properties is of great significance for the preparation of high-performance AgSbTe2-based thermoelectric materials. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide an AgSbTe2-based thermoelectric material with MnTe alloying control, and its preparation and application.

[0007] MnTe, as an environmentally friendly and structurally stable wide-bandgap semiconductor, exhibits unique tuning potential. MnTe possesses a special magnetic and electronic configuration. When Mn ions enter the semiconductor lattice, they not only generate a strong microscopic strain field due to differences in atomic mass and radius, but also utilize their spin magnetic moment and orbital hybridization to induce additional carrier and phonon scattering mechanisms. Furthermore, as a transition metal element, Mn exhibits unique amphoteric doping characteristics in the AgSbTe2 lattice: when Mn occupies an Ag site (Mn... Ag When electrons are introduced into the matrix, they recombine with holes, leading to a decrease in electrical conductivity (σ) while suppressing electronic thermal conductivity (κ). e When Mn occupies the Sb bit (Mn Sb When the doping is active, it exhibits acceptor doping, which increases the hole concentration to improve σ while maintaining a high Seebeck coefficient, thereby significantly improving the power factor (PF) and enabling the material to exhibit superior thermoelectric performance in the mid-temperature region. This amphoteric doping effect provides new possibilities for finely controlling carrier concentration and synergistically optimizing electrothermal transport performance.

[0008] The objective of this invention can be achieved through the following technical solutions: The first objective of this invention is to provide an AgSbTe2-based thermoelectric material with MnTe alloying control, wherein the general chemical formula of the thermoelectric material is (AgSbTe2). 1-x (MnTe) x The value of x is in the range of 0.15 ≤ x ≤ 0.3; Preferably, x is 0.15, 0.2, 0.25, or 0.3; More preferably, x is 0.25, and the MnTe alloy-controlled AgSbTe2-based thermoelectric material at 673 K... zT The value is 1.86.

[0009] The second objective of this invention is to provide a method for preparing AgSbTe2-based thermoelectric materials with MnTe alloying control, comprising the following steps: (S1) Ag elemental raw material, Sb elemental raw material, Te elemental raw material and Mn elemental raw material are placed in a quartz tube, sealed and then subjected to melting, quenching, annealing and grinding processes in sequence to obtain precursor powder; (S2) The precursor powder prepared in step (S1) is subjected to vacuum hot pressing sintering to obtain AgSbTe2-based thermoelectric material.

[0010] In one embodiment of the present invention, in step (S1), the purity of Ag elemental raw material (Ag particles), Sb elemental raw material (Sb particles), Te elemental raw material (Te blocks), and Mn elemental raw material (Mn particles) is greater than 99.9%, and the weighing process is carried out in an inert atmosphere.

[0011] In one embodiment of the present invention, in step (S1), during the melting process, the heating rate is 1~2 °C / min, the melting temperature is 900~1000 °C, and the holding time is 20~24 h; Water quenching is used for quenching treatment; The annealing process is carried out in a muffle furnace with a heating rate of 1~2 ℃ / min, an annealing temperature of 500~600℃, and a holding time of 3~5 days; The grinding process is carried out in an argon glove box for 30-40 minutes.

[0012] In one embodiment of the present invention, during the melting process, the heating rate is 2 °C / min, the melting temperature is 1000 °C, and the holding time is 24 h; Water quenching is used for quenching treatment; During the annealing process, the heating rate was 2 ℃ / min, the annealing temperature was 500 ℃, and the holding time was 3 days. The grinding process was carried out under an argon atmosphere for 30 minutes.

[0013] In one embodiment of the present invention, in step (S2), during the vacuum hot pressing sintering process, the axial pressure is 40~50 MPa, the heating rate is 30~50 K / min, the sintering temperature is 673~693 K, and the holding time is 25~35 min.

[0014] In one embodiment of the present invention, during the vacuum hot pressing sintering process, the axial pressure is 50 MPa, the heating rate is 50 K / min, the sintering temperature is 693 K, and the holding time is 30 min.

[0015] This invention induces local compositional fluctuations and lattice distortions in the AgSbTe2 matrix through a MnTe alloying strategy, forming a submicron-scale Ag2Te second phase and Mn-Te enriched regions. Combined with intrinsic Ag / Sb cation disorder, a multi-scale phonon scattering network is constructed, effectively suppressing the propagation of phonons of different frequencies and significantly reducing the lattice thermal conductivity. Simultaneously, through carrier concentration optimization and Fermi level modulation, the Seebeck coefficient is effectively improved while maintaining reasonable electrical conductivity, resulting in a significant improvement in the power factor of the material. As a result, the thermoelectric properties of the MnTe solid solution sample are significantly enhanced.

[0016] The third objective of this invention is to provide an application of MnTe alloy-controlled AgSbTe2-based thermoelectric material in the field of medium-temperature thermoelectric materials.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention utilizes the amphoteric doping characteristics of Mn through a MnTe alloying strategy to achieve precise control of the carrier concentration in AgSbTe2-based materials. Mn occupies both Ag and Sb sites, optimizing the hole concentration through charge compensation effect, effectively suppressing the bipolar effect in the high-temperature region, and significantly improving the Seebeck coefficient while maintaining reasonable conductivity, thus optimizing the electrical transport performance.

[0018] (2) This invention constructs a multi-scale phonon scattering network in the material through MnTe alloying: atomic-scale Mn solid solution introduces mass fluctuations and local lattice distortion, enhancing the scattering of high-frequency phonons by point defects; submicron-scale dispersed Ag2Te second phase and Mn-Te enriched regions form interface scattering centers, effectively blocking mid- and low-frequency phonons; intrinsic Ag / Sb cations further scatter the remaining phonons due to disorder. This multi-level scattering mechanism significantly reduces the lattice thermal conductivity, reaching as low as 0.31 W·m at 673 K. -1 ·K -1 It approaches the theoretical amorphous limit.

[0019] (3) This invention significantly improves the thermoelectric properties of materials through MnTe alloying, resulting in a synergistic effect of optimized electrical transport and a significant reduction in lattice thermal conductivity. All alloyed samples... zT The values ​​are all higher than those of the undoped AgSbTe2 matrix, with the sample at x=0.25 achieving the highest value at 673 K. zT With a value of 1.86, it exhibits excellent thermoelectric properties.

[0020] (4) The AgSbTe2-based thermoelectric material provided by the present invention has good thermal stability and achieves excellent thermoelectric performance while maintaining the original crystal structure.

[0021] (5) The preparation method of AgSbTe2-based thermoelectric material provided by the present invention is simple and convenient, low in cost, highly controllable and reproducible, and suitable for large-scale production. Attached Figure Description

[0022] Figure 1 The X-ray diffraction patterns are of samples from Examples 1-4 and Comparative Example 1. Figure 2 This is a schematic diagram showing the relationship between DSC and temperature for samples from Examples 1-4 and Comparative Example 1. Figure 3 This is a schematic diagram showing the relationship between the conductivity of the samples in Examples 1-4 and Comparative Example 1 and temperature. Figure 4 This is a schematic diagram showing the relationship between the Seebeck coefficient and temperature for samples from Examples 1-4 and Comparative Example 1. Figure 5 This is a schematic diagram showing the relationship between the power factor of the samples in Examples 1-4 and Comparative Example 1 and temperature. Figure 6 This is a schematic diagram showing the relationship between the total thermal conductivity of the samples in Examples 1-4 and Comparative Example 1 and temperature. Figure 7 This is a schematic diagram showing the relationship between the thermoelectric figure of merit of the samples in Examples 1-4 and Comparative Example 1 and temperature. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.

[0025] Example 1 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials controlled by MnTe alloying. The AgSbTe2-based thermoelectric material controlled by MnTe alloying is a P-type thermoelectric material formed by alloying AgSbTe2 and MnTe, with the general chemical formula (AgSbTe2). 0.85 (MnTe) 0.15 ; The specific preparation method of AgSbTe2-based thermoelectric materials controlled by MnTe alloying is as follows: (S1) In an argon glove box, weigh a total of 6g of raw material according to Ag:Sb:Te:Mn (molar ratio) = 0.85:0.85:1.85:0.15 (where the purity of Ag granules, Sb granules, Te blocks and Mn powder are all greater than 99.9%, and the weighing is performed using an electronic balance with an accuracy of 0.1 mg). The weighed raw materials are placed in a quartz tube, the quartz tube is connected to the sealing equipment, and the air is pumped and washed three times until the vacuum degree is less than 3 Pa. The quartz plug is heated by a high-temperature hydrogen-oxygen flame to melt and soften the quartz tube to achieve vacuum sealing. (S2) The quartz tube packaged in step (S1) is placed in a tube furnace and heated to 1000 °C at a heating rate of 2 °C / min. It is held at this temperature for 24 h to allow the raw material to fully melt. Then, the quartz tube is quickly removed and quenched in water to maintain the high-temperature phase structure. The quenched quartz tube is placed in a muffle furnace and heated from room temperature to 500 °C at a heating rate of 2 °C / min. It is held at this temperature for 3 days and then cooled to room temperature with the furnace to obtain (AgSbTe2). 0.85 (MnTe)0.15 Alloy ingots; (S3) In an argon glove box, place the (AgSbTe2) obtained in step (S2) 0.85 (MnTe) 0.15 The alloy ingot was placed in an agate mortar and ground for 30 minutes. After sieving, the precursor powder was obtained and stored in a glove box for later use. (S4) Weigh 1 g of the precursor powder prepared in step (S3) in an argon glove box and place it into a graphite mold with an inner diameter of 10 mm (with a layer of carbon paper on both the top and bottom of the precursor powder); place the graphite mold in a vacuum hot pressing sintering furnace, evacuate, apply a pressure of 50 MPa for pre-pressing, then heat to 693 K at a heating rate of 50 K / min, hold for 30 min, remove the applied pressure and allow it to cool naturally to room temperature, remove the mold, and polish off the carbon paper on the sample surface with sandpaper to obtain the MnTe alloy-controlled AgSbTe2-based thermoelectric material: bulk (AgSbTe2). 0.85 (MnTe) 0.15 Thermoelectric materials.

[0026] Example 2 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials controlled by MnTe alloying. The AgSbTe2-based thermoelectric material controlled by MnTe alloying is a P-type thermoelectric material formed by alloying AgSbTe2 and MnTe, with the general chemical formula (AgSbTe2). 0.8 (MnTe) 0.2 ; Except for the following, everything else is the same as in Example 1: In step (S1), the molar ratio of Ag:Sb:Te:Mn is 0.8:0.8:1.8:0.2.

[0027] Example 3 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials controlled by MnTe alloying. The AgSbTe2-based thermoelectric material controlled by MnTe alloying is a P-type thermoelectric material formed by alloying AgSbTe2 and MnTe, with the general chemical formula (AgSbTe2). 0.75 (MnTe) 0.25 ; Except for the following, everything else is the same as in Example 1: In step (S1), the molar ratio of Ag:Sb:Te:Mn is 0.75:0.75:1.75:0.25.

[0028] Example 4 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials controlled by MnTe alloying. The AgSbTe2-based thermoelectric material controlled by MnTe alloying is a P-type thermoelectric material formed by alloying AgSbTe2 and MnTe, with the general chemical formula (AgSbTe2). 0.7 (MnTe) 0.3 ; Except for the following, everything else is the same as in Example 1: In step (S1), the molar ratio of Ag:Sb:Te:Mn is 0.7:0.7:1.7:0.3.

[0029] Comparative Example 1 This comparative example provides a method for preparing an AgSbTe2-based thermoelectric material, whose general chemical formula is AgSbTe2; The specific preparation method of AgSbTe2-based thermoelectric materials is as follows: (S1) In an argon glove box, weigh a total of 6 g of raw material according to Ag:Sb:Te (molar ratio) = 1:1:2 (where the purity of Ag particles, Sb particles and Te blocks is greater than 99.9%, and the weighing is performed using an electronic balance with an accuracy of 0.1 mg). The weighed raw materials are placed in a quartz tube, the quartz tube is connected to the sealing equipment, and the air is pumped and washed three times until the vacuum degree is less than 3 Pa. The quartz plug is heated by a high-temperature hydrogen-oxygen flame to melt and soften the quartz tube to achieve vacuum sealing. (S2) The quartz tube packaged in step (S1) is placed in a tube furnace and heated to 1000 ℃ at a heating rate of 2 ℃ / min. It is held at this temperature for 24 h to allow the raw material to fully melt. Then, the quartz tube is quickly removed and placed in water for quenching to maintain the high-temperature phase structure. The quenched quartz tube is placed in a muffle furnace and heated from room temperature to 500 ℃ at a heating rate of 2 ℃ / min. It is held at this temperature for 3 days and then cooled to room temperature with the furnace to obtain AgSbTe2 alloy ingot. (S3) In an argon glove box, place the AgSbTe2 alloy ingot obtained in step (S2) into an agate mortar and grind for 30 min. After sieving, obtain precursor powder and store it in the glove box for later use. (S4) Weigh 1 g of the precursor powder prepared in step (S3) in an argon glove box and put it into a graphite mold with an inner diameter of 10 mm (with a layer of carbon paper on the top and bottom of the precursor powder); put the graphite mold into a vacuum hot pressing sintering furnace, evacuate, apply a pressure of 50 MPa for pre-pressing, then heat to 693 K at a heating rate of 50 K / min, hold for 30 min, remove the applied pressure and cool naturally to room temperature, take out the mold, and use sandpaper to polish off the carbon paper on the sample surface to obtain AgSbTe2-based thermoelectric material: bulk AgSbTe2 thermoelectric material.

[0030] Performance Analysis: Comparison of AgSbTe2 prepared in Comparative Example 1 with (AgSbTe2) prepared in Examples 1-4 1-x (MnTe) x XRD phase characterization and differential scanning calorimetry (DSC) analysis were performed on the thermoelectric material. The XRD patterns and DSC curves are shown below. Figure 1 and Figure 2 As shown. (Through) Figure 1 and Figure 2 It can be observed that MnTe successfully enters the AgSbTe2 matrix lattice. A trace amount of Ag2Te impurity phase exists in the sample, but the diffraction peaks are relatively weak. DSC tests show that as the amount of MnTe solid solution increases, the relative intensity of the endothermic peak gradually weakens, indicating that the MnTe solid solution inhibits the generation of the Ag2Te second phase in the matrix to a certain extent.

[0031] The AgSbTe2 prepared in Comparative Example 1 was compared with the (AgSbTe2) prepared in Examples 1-4. 1-x (MnTe) x The thermoelectric material was cut into 10×1.5×3.5 mm pieces using a diamond cutter. 3 Rectangular strip-shaped samples were subjected to electrical performance tests using a ULVAC-RIKO ZEM-3 instrument. Test data included conductivity and Seebeck coefficient. The test results are as follows: Figure 3 and Figure 4 As shown.

[0032] pass Figure 3 It can be observed that the (AgSbTe2) prepared in Examples 1-4... 1-x (MnTe) x The conductivity was significantly improved compared to the substrate. All samples exhibited non-monotonic temperature-dependent characteristics: the conductivity decreased with increasing temperature in the temperature range of 300–473 K, exhibiting the transport characteristics of a degenerate semiconductor; after 473 K, the conductivity of all samples increased with increasing temperature, indicating that this narrow bandgap semiconductor began to exhibit a bipolar effect.

[0033] passFigure 4 It can be observed that the test samples of Examples 1-4 and Comparative Example 1 exhibited positive values ​​throughout the entire test temperature range, indicating that the system consistently maintained p-type conductivity. The Seebeck coefficient first increased and then decreased with increasing temperature, which is related to the aforementioned bipolar effect. Furthermore, the Seebeck coefficient generally showed an upward trend with increasing MnTe content, especially in the mid-to-high temperature range. For example, the samples with x=0.25 and 0.30 reached 360~370 μV / K near 473 K, significantly higher than the matrix; this indicates that the introduction of MnTe reduced the effective hole concentration or adjusted the Fermi level position, thereby increasing the Seebeck coefficient.

[0034] Figure 5 This is a schematic diagram showing the relationship between the power factor and temperature for samples from Examples 1-4 and Comparative Example 1. Figure 5 It can be observed that, due to the slightly increased conductivity and the maintenance of a relatively high Seebeck coefficient, the power factor of the test samples in Examples 1-4 was significantly improved compared to that of the test sample in Comparative Example 1.

[0035] The AgSbTe2 prepared in Comparative Example 1 was compared with the (AgSbTe2) prepared in Examples 1-4. 1-x (MnTe) x A layer of graphite was uniformly sprayed onto the upper and lower surfaces of the thermoelectric material, and its thermal performance was tested on a NETZSCH LFA 457 device, mainly testing the thermal diffusivity D.

[0036] The formula for calculating thermal conductivity is κ = DC. p ρ, where specific heat capacity C p The density ρ is estimated using the Dulong-Petty law, which can be used to estimate the material density using Archimedes' method of displacement.

[0037] pass Figure 6 It can be observed that all samples exhibit intrinsically low thermal conductivity throughout the entire test temperature range, with values ​​mainly distributed between 0.4 and 0.7 W·m. -1 K -1 The temperature range of 300–473 K reflects the typical low thermal conductivity characteristic of the AgSbTe2 system. Within this range, κ gradually decreases with increasing temperature, while it shows a slight upward trend when T > 473 K. Specifically, (AgSbTe2) 0.75 (MnTe) 0.25 The sample exhibits the lowest total thermal conductivity, decreasing by 0.63 W·m from the matrix at 573 K. -1 K -1 Reduced to 0.38 W·m -1 K -1The overall thermal conductivity was significantly lower than that of other components, indicating that MnTe alloying has a significant effect on suppressing thermal transport. The reduction in overall thermal conductivity can be attributed to the synergistic effect of multi-scale phonon scattering mechanisms: Mn substitution for Ag / Sb causes mass fluctuations and local lattice distortion, which enhances point defect scattering and effectively scatters high-frequency phonons; the submicron-scale dispersed Ag2Te second phase and Mn-Te enriched region act as interface scattering centers, effectively blocking the propagation of mid- and low-frequency phonons; and the intrinsic Ag / Sb cation disorder further scatters the remaining phonons.

[0038] pass Figure 7 It can be observed that the sample's... zT Value, (AgSbTe2) 0.75 (MnTe) 0.25 At 673K zT The value is as high as 1.86, which is a significant improvement compared to the matrix.

[0039] Example 5 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials with MnTe alloying control, the general chemical formula of which is (AgSbTe2). 0.85 (MnTe) 0.15 ; Except for the following, everything else is the same as in Example 1: In step (S2), during the melting process, the heating rate is 1 ℃ / min, the melting temperature is 950 ℃, and the holding time is 22 h; During the annealing process, the heating rate was 2 ℃ / min, the annealing temperature was 600 ℃, and the holding time was 4 days. In step (S3), the grinding time is 35 min; In step (S4), during the vacuum hot pressing sintering process, the axial pressure is 40 MPa, the heating rate is 50 K / min, the sintering temperature is 653 K, and the holding time is 30 min.

[0040] Example 6 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials with MnTe alloying control, the general chemical formula of which is (AgSbTe2). 0.85 (MnTe) 0.15 ; Except for the following, everything else is the same as in Example 1: In step (S2), during the melting process, the heating rate is 2 ℃ / min, the melting temperature is 900 ℃, and the holding time is 24 h; During the annealing process, the heating rate was 1 ℃ / min, the annealing temperature was 550 ℃, and the holding time was 5 days. In step (S3), the grinding time is 30 min; In step (S4), during the vacuum hot pressing sintering process, the axial pressure is 45 MPa, the heating rate is 40 K / min, the sintering temperature is 623 K, and the holding time is 35 min.

[0041] Example 7 This embodiment provides a method for preparing AgSbTe2-based thermoelectric materials with MnTe alloying control, the general chemical formula of which is (AgSbTe2). 0.85 (MnTe) 0.15 ; Except for the following, everything else is the same as in Example 1: In step (S2), during the melting process, the heating rate is 1 ℃ / min, the melting temperature is 1000 ℃, and the holding time is 20 h; During the annealing process, the heating rate was 1 ℃ / min, the annealing temperature was 600 ℃, and the holding time was 3 days. In step (S3), the grinding time is 40 min; In step (S4), during the vacuum hot pressing sintering process, the axial pressure is 50 MPa, the heating rate is 30 K / min, the sintering temperature is 673 K, and the holding time is 25 min.

[0042] The MnTe alloy-controlled AgSbTe2-based thermoelectric materials prepared in Examples 5-7 have comparable performance to the MnTe alloy-controlled AgSbTe2-based thermoelectric materials prepared in Example 1.

[0043] In summary, the AgSbTe2-based thermoelectric material prepared by this invention improves both electrical conductivity and Seebeck coefficient, exhibiting excellent electrical transport properties, while significantly reducing thermal conductivity, thus achieving synergistic optimization of electrothermal transport performance. The prepared material can be widely used in the preparation of thermoelectric materials and / or devices in the mid-temperature range, enabling efficient waste heat recovery.

[0044] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A MnTe alloy-controlled AgSbTe2-based thermoelectric material, characterized in that, The general chemical formula of the thermoelectric material is (AgSbTe2). 1-x (MnTe) x The value of x is in the range of 0.15≤x≤0.

3.

2. The AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 1, characterized in that, The x is 0.15, 0.2, 0.25 or 0.

3.

3. The AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 2, characterized in that, The x value is 0.25, and the MnTe alloy-modified AgSbTe2-based thermoelectric material at 673 K... zT The value is 1.

86.

4. A method for preparing an AgSbTe2-based thermoelectric material with MnTe alloying control as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (S1) Ag elemental raw material, Sb elemental raw material, Te elemental raw material and Mn elemental raw material are placed in a quartz tube, sealed and then subjected to melting, quenching, annealing and grinding processes in sequence to obtain precursor powder; (S2) The precursor powder prepared in step (S1) is subjected to vacuum hot pressing sintering to obtain AgSbTe2-based thermoelectric material.

5. The preparation method of an AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 4, characterized in that, In step (S1), the purity of Ag, Sb, Te, and Mn raw materials is greater than 99.9%, and they are weighed under an inert atmosphere.

6. The preparation method of an AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 4, characterized in that, In step (S1), during the melting process, the heating rate is 1~2 ℃ / min, the melting temperature is 900~1000 ℃, and the holding time is 20~24 h; Water quenching is used for quenching treatment; During the annealing process, the heating rate is 1~2 ℃ / min, the annealing temperature is 500~600 ℃, and the holding time is 3~5 days; The grinding process is carried out under an argon atmosphere, and the grinding time is 30~40 min.

7. The preparation method of an AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 6, characterized in that, During the melting process, the heating rate was 2 °C / min, the melting temperature was 1000 °C, and the holding time was 24 h. Water quenching is used for quenching treatment; During the annealing process, the heating rate was 2 ℃ / min, the annealing temperature was 500 ℃, and the holding time was 3 days. The grinding process was carried out under an argon atmosphere for 30 minutes.

8. The preparation method of an AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 4, characterized in that, In step (S2), during the vacuum hot pressing sintering process, the axial pressure is 40~50 MPa, the heating rate is 30~50 K / min, the sintering temperature is 673~693 K, and the holding time is 25~35 min.

9. The preparation method of an AgSbTe2-based thermoelectric material with MnTe alloying control according to claim 8, characterized in that, During the vacuum hot pressing sintering process, the axial pressure is 50 MPa, the heating rate is 50 K / min, the sintering temperature is 693 K, and the holding time is 30 min.

10. The application of the AgSbTe2-based thermoelectric material with MnTe alloying control as described in any one of claims 1 to 3 in the field of medium-temperature thermoelectric materials.

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