Sb / Mn / Ge co-doped tin telluride-based thermoelectric material and preparation method and application thereof

Abstract

The invention discloses a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material and a preparation method and application thereof, the molecular formula of the Sb / Mn / Ge co-doped tin telluride-based thermoelectric material is Sn < 1.01-x-y > Sb < 0.04 > MnxGeyTe, x is more than or equal to 0.04 and less than or equal to 0.08, and y is more than or equal to 0 and less than or equal to 0.10. The preparation method comprises the following steps: weighing raw materials Sn, Te, Sb, Mn and Ge, grinding, mixing, transferring into a carbon-plated quartz tube, and performing vacuum sealing; carrying out a melting reaction on the carbon-plated quartz tube, and quenching after the reaction is finished to obtain a cast ingot; and grinding into powder, loading into a mold, sintering by discharge plasma, and relieving pressure and cooling. The invention discloses application of the thermoelectric material in a medium-high temperature thermoelectric power generation device for industrial waste heat recovery. The raw materials are non-toxic and environment-friendly, the carrier concentration is reduced through Sn compensation, meanwhile, the energy difference between light and heavy valence bands is reduced through Sb / Mn / Ge co-doping, and the energy band degeneracy and the state density effective quality are improved.

Description

Technical Field

[0001] This invention pertains to thermoelectric materials, their preparation methods and applications, specifically Sb / Mn / Ge co-doped tin telluride-based thermoelectric materials, their preparation methods and applications. Background Technology

[0002] Thermoelectric technology is an important way to alleviate the two major problems of energy consumption and environmental pollution, mainly in the following two aspects: First, thermoelectric technology can directly convert heat energy into electrical energy, which is conducive to recovering a large amount of waste heat from traditional fossil fuels and thus realizing secondary power generation; Second, thermoelectric technology does not emit any pollutants, and reduces pollutant emissions by reducing fossil fuel consumption through waste heat recovery. The development of thermoelectric technology mainly relies on thermoelectric materials, among which environmentally friendly tin telluride is an important mid-temperature semiconductor material and an ideal material to replace typical lead telluride thermoelectric materials.

[0003] Intrinsic tin telluride exhibits low thermoelectric figure of merit due to its high carrier concentration, large light-heavy band energy difference, and high lattice thermal conductivity. Improving its power factor is an effective method to obtain high ZT. Researchers have proposed various strategies to improve the power factor, such as tin hole compensation, resonant energy levels, band degeneracy, and energy filtering. Among these, band degeneracy mainly improves the band degeneracy and effective mass of the density of states by reducing the energy difference between the light and heavy bands of tin telluride, thereby optimizing the Seebeck coefficient without degrading conductivity. Nevertheless, the improvement of the effective mass of the density of states by traditional L and Σ band degeneracy is limited. Therefore, there is an urgent need to develop an effective strategy to achieve degeneracy of more bands. Summary of the Invention

[0004] Purpose of the Invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a high power factor Sb / Mn / Ge co-doped tin telluride-based thermoelectric material. Another purpose of this invention is to provide an energy-saving and environmentally friendly preparation method for Sb / Mn / Ge co-doped tin telluride-based thermoelectric material. A further purpose of this invention is to provide an application of Sb / Mn / Ge co-doped tin telluride-based thermoelectric material in medium- and high-temperature thermoelectric power generation devices for industrial waste heat recovery.

[0005] Technical solution: The present invention relates to a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material, the molecular formula of which is Sn. 1.01-x-y Sb 0.04 Mn x Ge y Te, where 0.04≤x≤0.08, 0≤y≤0.10.

[0006] Furthermore, the Sb / Mn / Ge co-doped tin telluride-based thermoelectric material exhibits a power factor of 5.0–10.2 μWm at 300 K. -1 K-2 The power factor at 873 K is 22.6–24.8 μW / m². -1 K -2 .

[0007] Furthermore, its molecular formula is Sn. 0.97 Sb 0.04 Mn 0.04 Te、Sn 0.95 Sb 0.04 Mn 0.06 Te、Sn 0.93 Sb 0.04 Mn 0.08 Te、Sn 0.90 Sb 0.04 Mn 0.08 Ge 0.03 Te、Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te or Sn 0.83 Sb 0.04 Mn 0.08 Ge 0.10 Te. Preferably, its molecular formula is Sn. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te.

[0008] The present invention discloses a method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material, comprising the following steps:

[0009] Step 1: Weigh the raw materials Sn, Te, Sb, Mn and Ge according to the stoichiometric ratio, grind and mix them, transfer them to a carbon-plated quartz tube, evacuate and seal it;

[0010] Step 2: The carbon-coated quartz tube obtained in Step 1 is subjected to a melting reaction. After the reaction is completed, it is quenched to obtain an ingot.

[0011] Step 3: Grind the material obtained in Step 2 into powder, load it into a mold, sinter it using discharge plasma, and then depressurize and cool it to obtain Sb / Mn / Ge co-doped tin telluride-based thermoelectric material.

[0012] Furthermore, in step one, the purity of the raw materials Sn, Te, Sb, Mn, and Ge is ≥99.95%, and the particle size is less than 100 mesh. The molar mass ratio of the raw materials Sn, Te, Sb, Mn, and Ge is 0.83~0.97:1:0.04:0.04~0.08:0~0.10.

[0013] Furthermore, in step one, a vacuum is drawn to 10. -2 Below Pa.

[0014] Furthermore, in step two, the melting reaction occurs at a rate of 1~3 o Heating rate is increased to 950~1100 ℃, and held at this temperature for 6~18 hours. Quenching is then carried out in water at 10~40 ℃.

[0015] Furthermore, in step three, the grinding time is 20~120 min.

[0016] Furthermore, in step three, the discharge plasma sintering involves heating to 500-600 ℃ in 8-10 minutes, holding at that temperature for 5-30 minutes, and sintering at a pressure of 30-60 MPa.

[0017] This invention provides an application of Sb / Mn / Ge co-doped tin telluride-based thermoelectric material in medium- and high-temperature thermoelectric power generation devices for industrial waste heat recovery.

[0018] Preparation principle: Doping with Sb and Mn elements reduces the energy difference between the L and Σ valence bands of tin telluride. Further doping with Ge element activates the Λ band, thereby achieving alignment of the L, Σ, and Λ triple valence bands. The band degeneracy is increased from 4 to 24, thus significantly improving the density of states, effective mass, and Seebeck coefficient. Combined with Sn self-compensation to reduce carrier concentration, the Sb / Mn / Ge co-doped tin telluride-based thermoelectric material ultimately achieves a high power factor.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0020] 1. Using non-toxic Sn, Te, Sb, Mn and Ge as raw materials ensures the environmental friendliness of tin telluride-based thermoelectric materials. First, Sn compensation reduces the carrier concentration, while Sb / Mn / Ge co-doping promotes the reduction of the energy difference between light and heavy valence bands, thereby improving the band degeneracy and effective mass of density of states.

[0021] 2. Preparation of Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The Te material has a power factor of 10.2 μW / m at 300 K. -1 K -2 The power factor at 873 K is 24.8 μW / m². -1 K -2 . Attached Figure Description

[0022] Figure 1 The X-ray diffraction pattern of the material obtained in this invention;

[0023] Figure 2 This is a diagram showing the conductivity of the material obtained in this invention as a function of temperature.

[0024] Figure 3 The Seebeck coefficient of the material obtained in this invention varies with temperature.

[0025] Figure 4 This is a power factor diagram of the material obtained in this invention as a function of temperature.

[0026] Figure 5 The X-ray diffraction pattern of the material obtained in this invention;

[0027] Figure 6 This is a diagram showing the conductivity of the material obtained in this invention as a function of temperature.

[0028] Figure 7 The Seebeck coefficient of the material obtained in this invention varies with temperature.

[0029] Figure 8 This is a power factor diagram of the material obtained in this invention as a function of temperature.

[0030] Figure 9 This is a thermal conductivity diagram as a function of temperature obtained in this invention.

[0031] Figure 10 This is a thermoelectric figure of merit diagram as a function of temperature obtained in this invention. Detailed Implementation

[0032] Unless otherwise specified, all materials and reagents used in the following embodiments are commercially available. Experimental methods not specifically described in the embodiments are generally performed under standard conditions or as recommended by the manufacturer. The particle size of the raw materials Sn, Te, Sb, Mn, and Ge powders is less than 100 mesh.

[0033] Example 1

[0034] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.97 Sb 0.04 Mn 0.04 The preparation method of Te includes the following steps:

[0035] (1) According to Sn 0.97 Sb 0.04 Mn 0.04 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0036] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0037] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 20 °C to obtain Sn. 0.97 Sb 0.04 Mn 0.04 Te compound ingots.

[0038] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.97 Sb 0.04 Mn 0.04 Te thermoelectric materials.

[0039] Example 2

[0040] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.95 Sb 0.04 Mn 0.06 The preparation method of Te includes the following steps:

[0041] (1) According to Sn 0.95 Sb 0.04 Mn 0.06 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0042] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0043] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 40°C to obtain Sn. 0.95 Sb0.04 Mn 0.06 Te compound ingots.

[0044] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.95 Sb 0.04 Mn 0.06 Te thermoelectric materials.

[0045] Example 3

[0046] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.93 Sb 0.04 Mn 0.08 The preparation method of Te includes the following steps:

[0047] (1) According to Sn 0.93 Sb 0.04 Mn 0.08 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0048] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0049] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 40°C to obtain Sn. 0.93 Sb 0.04 Mn 0.08 Te compound ingots.

[0050] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.93 Sb 0.04 Mn 0.08 Te thermoelectric materials.

[0051] Example 4

[0052] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.90 Sb 0.04 Mn 0.08 Ge 0.03 The preparation method of Te includes the following steps:

[0053] (1) According to Sn 0.90 Sb 0.04 Mn 0.08 Ge 0.03 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0054] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0055] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 40°C to obtain Sn. 0.90 Sb 0.04 Mn 0.08 Ge 0.03 Te compound ingots.

[0056] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.90 Sb 0.04 Mn 0.08 Ge 0.03 Te thermoelectric materials.

[0057] Example 5

[0058] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te includes the following steps:

[0059] (1) According to Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0060] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0061] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 40°C to obtain Sn. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te compound ingots.

[0062] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te thermoelectric materials.

[0063] Application Example 1

[0064] The Sn obtained in Example 5 of this embodiment 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te thermoelectric materials are used in medium- and high-temperature thermoelectric power generation devices for industrial waste heat recovery. Specifically, in traditional power generation industries that use fossil fuels as fuel, the energy utilization efficiency is only ~34%, with most of the remaining energy lost as waste heat. Thermoelectric power generation devices based on Sb / Mn / Ge co-doped tin telluride-based thermoelectric materials are applied to the surface of high-temperature pipes or equipment to efficiently recover this heat as electrical energy, thus achieving secondary power generation. For example, Sn... 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The average thermoelectric figure of merit of Te is 0.53 (300-873 K). Assuming the hot end and cold end temperatures are 873 K and 300 K respectively, the theoretical energy conversion efficiency is approximately 10%.

[0065] Example 6

[0066] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.83 Sb 0.04 Mn 0.08 Ge 0.10 The preparation method of Te includes the following steps:

[0067] (1) According to Sn 0.83 Sb 0.04 Mn 0.08 Ge 0.10 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0068] (2) After grinding and mixing, the mixture is transferred to a 13 mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0069] (3) The sealed carbon-plated quartz tube is placed in a muffle furnace for melting reaction, and its temperature control program is set as follows: at 1 o The heating rate was increased from room temperature to 1000 °C / min. o C, and held at this temperature for 12 hours, then quenched in water at 40°C to obtain Sn. 0.83 Sb 0.04 Mn 0.08 Ge 0.10 Te compound ingots.

[0070] (4) Grind the ingot obtained from the above reaction in a glove box for 40 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 40 MPa and then depressurize, then rapidly increase the temperature from room temperature to 600 °C in 8 min. o C. Pressure: Pressurize to 40 MPa in 6 minutes, then at 600... o After holding at C and 40 MPa for 5 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.83 Sb 0.04 Mn 0.08 Ge 0.10 Te thermoelectric materials.

[0071] Figure 1 and Figure 5 The X-ray diffraction patterns of Examples 1-3 and Examples 4-6 are shown respectively. The main diffraction peaks of all samples are completely consistent with the SnTe standard card PDF#46-1210, indicating that the thermoelectric material with pure tin telluride phase was successfully prepared.

[0072] Figures 2-4 The conductivity, Sebek coefficient, and power factor of Examples 1-3 are respectively. Sn self-compensation reduces carrier concentration, and Sb / Mn doping reduces the energy difference between the L and Σ bands. 1.01-x Sb 0.04 Mn x The Te sample exhibited superior electrical properties compared to tin telluride.

[0073] Figures 6-8 The conductivity, sebeck coefficient, and power factor of Examples 4-6 are respectively, based on Sn optimized by component ratio. 0.93 Sb 0.04 Mn 0.08Te samples, further doped with Ge, promote the degeneracy of the L, Σ, and Λ triple valence bands, therefore Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The power factor of the Te sample increased to 10.2 μW cm⁻¹ at 300 K and 873 K, respectively. -1 K -2 and 24.8 μW cm -1 K -2 Sn 0.97 Sb 0.04 Mn 0.04 The Te thermoelectric material has a power factor of 5.0 μW cm⁻¹ at 300 K. -1 K -2 Sn 0.93 Sb 0.04 Mn 0.08 The Te thermoelectric material has a power factor of 22.6 μW cm⁻¹ at 873 K. -1 K -2 .

[0074] Figure 9 The thermal conductivity of Examples 1-6 is due to point defects and strain fluctuations caused by Sb / Mn / Ge replacing Sn atoms, and all Sn 1.01-x-y Sb 0.04 Mn x Ge y The Te sample exhibits lower thermal conductivity than undoped tin telluride, while Sn 0.90 Sb 0.04 Mn 0.08 Ge 0.03 The thermal conductivity of the Te sample decreased to 1.87 W / m. -1 K -1 (873 K).

[0075] Figure 10 The thermoelectric figure of merit for Examples 1-6 is achieved by benefiting from the reduced carrier concentration and increased effective mass of the density of states, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The maximum thermoelectric figure of merit for the Te sample was 1.1 at 873 K, which is 3.6 times that of the undoped tin telluride.

[0076] Example 7

[0077] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.97 Sb 0.04 Mn 0.04 The preparation method of Te includes the following steps:

[0078] (1) According to Sn 0.97 Sb 0.04 Mn 0.04 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0079] (2) After grinding and mixing, the mixture is transferred to a 13mm diameter carbon-plated quartz tube and evacuated to a vacuum level of 3×10⁻⁶. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0080] (3) Place the sealed carbon-plated quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: at 3 o The heating rate was increased from room temperature to 950 °C / min. o C, and held at this temperature for 18 hours, then quenched in water at 10°C to obtain Sn. 0.97 Sb 0.04 Mn 0.04 Te compound ingots.

[0081] (4) Grind the ingot obtained from the above reaction in a glove box for 20 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize to 30 MPa and then depressurize; then, rapidly increase the temperature from room temperature to 500 °C in 10 min. o C. Pressure: Pressurize to 30 MPa in 6 minutes, then at 500... o After holding at C and 30 MPa for 30 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.97 Sb 0.04 Mn 0.04 Te thermoelectric materials.

[0082] Example 8

[0083] A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material Sn 0.97 Sb 0.04 Mn 0.04 The preparation method of Te includes the following steps:

[0084] (1) According to Sn 0.97 Sb 0.04 Mn 0.04 Weigh out germanium powder with a purity of 99.999%, manganese powder with a purity of 99.95%, tin powder with a purity of 99.99%, tellurium powder, and antimony powder with a purity of 99.99% according to the stoichiometric ratio of Te, and mix the above powders thoroughly in a mortar for 20 minutes.

[0085] (2) After grinding and mixing, the mixture is transferred to a 13mm diameter carbon-plated quartz tube and evacuated to a vacuum degree of 9×10⁻⁶. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0086] (3) Place the sealed carbon-plated quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: 1~3 o The heating rate was increased from room temperature to 1100 °C / min. o C, and held at this temperature for 6 hours, then quenched in water at 40°C to obtain Sn. 0.97 Sb 0.04 Mn 0.04 Te compound ingots.

[0087] (4) Grind the ingot obtained from the above reaction in a glove box for 120 min to obtain powder material; put the powder into a mold with a diameter of 12.7 mm, and place graphite paper around the powder to facilitate demolding. The discharge plasma sintering process is as follows: First, pre-pressurize 60 MPa and then depressurize, then rapidly increase the temperature from room temperature to 550 °C in 9 min. o C. Pressure: Pressurize to 60 MPa in 6 minutes, then at 550... o After holding at C and 60 MPa for 15 minutes, the pressure was finally released and cooled. After sintering, Sn was obtained. 0.97 Sb 0.04 Mn 0.04 Te thermoelectric materials.

[0088] Of the above embodiments, the preferred embodiment is Embodiment 5.

[0089] Comparative Example 1

[0090] The remaining steps in this comparative example are the same as in Example 5, except that the 99.999% pure germanium powder is replaced with 95% pure germanium powder. The reduced purity of the product after the melt reaction introduces 5% impurity atoms, severely affecting carrier concentration or mobility, and hindering the acquisition of excellent electronic transport properties and thermoelectric performance.

[0091] Comparative Example 2

[0092] The remaining steps of this comparative example are the same as those in Example 5, except that the 99.99% pure tin powder is replaced with 95% pure tin powder. The composition of the product obtained from the melting reaction fluctuates, introducing a large number of impurities, resulting in an imbalance of the molar mass of Sn, Sb, Mn and Te and a decrease in thermoelectric properties.

[0093] Comparative Example 3

[0094] The remaining steps in this comparative example are the same as in Example 5, except that the grinding in step (1) is omitted. Before the high-temperature reaction, the metal powder produces different stratification results due to different operating methods, affecting the local melting process and the compositional uniformity of the product.

[0095] Comparative Example 4

[0096] The remaining steps of this comparative example are the same as those of Example 5, except that the sintering pressure in step (4) is replaced with 20 MPa. A very low sintering pressure leads to incomplete sintering, which is detrimental to obtaining high-density products and high-performance tin telluride materials.

[0097] Comparative Example 5

[0098] The remaining steps of this comparative example are the same as those in Example 5, except that the sintering pressure in step (4) is replaced with 70 MPa. Increasing the sintering pressure can improve the density and optimize the electron transport properties; however, high pressure can also cause sample ejection problems during sintering and reduce the experimental yield.

Claims

1. A Sb / Mn / Ge co-doped tin telluride-based thermoelectric material, characterized in that: Its molecular formula is Sn 1.01-x- y Sb 0.04 Mn x Ge y Te, where 0.04≤x≤0.08, 0≤y≤0.

10.

2. The Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 1, characterized in that: The power factor at 300K is 5.0–10.2 μW / m. -1 K -2 The power factor at 873 K is 22.6–24.8 μW / m². -1 K -2 .

3. The Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 1, characterized in that: Its molecular formula is Sn 0.97 S 0.04 Mn 0.04 Te, Sn 0.95 S 0.04 Mn 0.06 Te, Sn 0.93 S 0.04 Mn 0.08 Te, Sn 0.90 S 0.04 Mn 0.08 Ge 0.03 Te, Sn 0.88 S 0.04 Mn 0.08 Ge 0.05 Te or Sn 0.83 S 0.04 Mn 0.08 Ge 0.10 Te.

4. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 1, characterized in that, Includes the following steps: Step 1: Weigh the raw materials Sn, Te, Sb, Mn and Ge according to the stoichiometric ratio, grind and mix them, transfer them to a carbon-plated quartz tube, evacuate and seal it; Step 2: The carbon-coated quartz tube obtained in Step 1 is subjected to a melting reaction. After the reaction is completed, it is quenched to obtain an ingot. Step 3: Grind the material obtained in Step 2 into powder, load it into a mold, sinter it using discharge plasma, and then depressurize and cool it to obtain Sb / Mn / Ge co-doped tin telluride-based thermoelectric material.

5. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 4, characterized in that: In step one, the purity of the raw materials Sn, Te, Sb, Mn and Ge is ≥99.95%, and the particle size is less than 100 mesh.

6. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 4, characterized in that: In step one, the vacuum is evacuated to 10. -2 Below Pa.

7. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 4, characterized in that: In step two, the melting reaction is carried out at a rate of 1~3 o Heating rate is increased to 950~1100 ℃, and held at this temperature for 6~18 hours. Quenching is then carried out in water at 10~40 ℃.

8. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 4, characterized in that: In step three, the grinding time is 20-120 minutes.

9. The method for preparing a Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 4, characterized in that: In step three, the discharge plasma sintering involves heating to 500-600 °C in 8-10 minutes, holding at that temperature for 5-30 minutes, and sintering at a pressure of 30-60 MPa.

10. The application of the Sb / Mn / Ge co-doped tin telluride-based thermoelectric material according to claim 1 in medium- and high-temperature thermoelectric power generation devices for industrial waste heat recovery.

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