A low thermal conductivity tin telluride-based thermoelectric material and a method of preparation

Abstract

The present invention discloses a low thermal conductivity tin telluride-based thermoelectric material and a preparation method thereof. The chemical formula of the tin telluride thermoelectric material is Sn 0.79 Sb 0.06 Ge 0.15 Te - x%CdS, where 0 < x ≤ 6. The prepared Sn 0.79 Sb 0.06 Ge 0.15 Te - 4%CdS material has a thermal conductivity of 2.8 W m ‑1 K ‑1 , and a thermal conductivity of 1.5 W m ‑1 K ‑1 at 874 K. The low thermal conductivity can effectively maintain the temperature difference between the cold end and the hot end of the thermoelectric arm, ensuring the continuous operation of the thermoelectric generator device. Meanwhile, the preparation method of the thermoelectric material described in the present invention also has the advantages of simple process, easy scale-up production and strong practicability.

Description

Technical Field

[0001] This invention belongs to the field of energy materials technology, specifically relating to a tin telluride-based thermoelectric material with low thermal conductivity and its preparation method. Background Technology

[0002] Energy consumption is constantly increasing, and environmental problems are becoming increasingly serious. More than two-thirds of the Earth's fossil fuels are wasted as heat during use. Effectively recovering and utilizing this waste heat would bring enormous benefits to both the economy and the environment. In recent years, thermoelectric devices and materials have attracted widespread attention because they can achieve direct and reversible conversion between heat and electricity, enabling noiseless, vibration-free, and emission-free all-solid-state power generation or refrigeration. These characteristics give thermoelectric devices and materials significant advantages in heat harvesting and solid-state refrigeration. For example, thermoelectric devices and materials can convert solar energy, geothermal energy, and industrial waste heat into electricity, and can also be used as heat pumps for cooling laser diodes, infrared detectors, computer CPUs, and microelectronic integrated devices.

[0003] Tin telluride, a green and non-toxic component, possesses the same crystal structure and similar band structure as lead telluride, making it a promising medium-to-high temperature thermoelectric material that could potentially replace lead telluride. However, tin telluride's high thermal conductivity limits its applications. On one hand, high thermal conductivity restricts the improvement of the material's thermoelectric figure of merit, resulting in low efficiency in the conversion of thermal and electrical energy. On the other hand, high thermal conductivity rapidly transfers temperature from the hot end to the cold end of the thermoelectric arm, making it impossible for the device to maintain a large temperature difference, leading to device failure. Therefore, exploring suitable control strategies to significantly reduce the thermal conductivity of tin telluride is an urgent problem to be solved. Summary of the Invention

[0004] To address the above problems, this invention provides a low thermal conductivity tin telluride-based thermoelectric material and its preparation method, using Sn obtained in Example 3. 0.79 Sb 0.06 Ge 0.15 The thermal conductivity of the Te-4%CdS thermoelectric material at 323 K is 2.8 W / m. -1 K -1 The thermal conductivity at 874 K is 1.5 W / m. -1 K -1 Meanwhile, the method for preparing the thermoelectric material described in this invention also has the advantages of simple process, easy large-scale production, and strong practicality.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a tin telluride-based thermoelectric material with low thermal conductivity, wherein the chemical formula of the tin telluride thermoelectric material is Sn. 0.79 Sb 0.06 Ge0.15 Te-x%CdS. Here Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS means CdS is solid-solved in Sn 0.79 Sb 0.06 Ge 0.15 Te in mass, x% of CdS is solid-solved in Sn 0.79 Sb 0.06 Ge 0.15 Te, wherein 0 < x ≤ 6. For example, x is 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 or 6. The SnTe-based thermoelectric material is applied to thermoelectric power generation.

[0007] Preferably, the SnTe-based thermoelectric material has the chemical formula Sn 0.79 Sb 0.06 Ge 0.15 Te-4%CdS.

[0008] In a second aspect, the present application provides a preparation method of a low-thermal-conductivity SnTe-based thermoelectric material, which specifically comprises the following steps:

[0009] S1, preparing raw materials Sn particles, Sb particles, Ge particles, Cd particles, Te particles and S particles;

[0010] S2, weighing the elements Sn, Sb, Ge, Cd, Te and S according to the atomic ratio respectively, and pouring them into a dried quartz tube, sealing the quartz tube after vacuumizing, and obtaining a Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS ingot after reaction;

[0011] S3, grinding the ingot obtained in S2, and then sintering to obtain the thermoelectric material.

[0012] Preferably, the purity of the elements Sn, Sb, Ge, Cd and Te in step S1 is greater than 99%.

[0013] Preferably, in step S2, the specific process of the reaction is: increasing the temperature from room temperature to 1000℃, 1050℃, 1100℃ or 1150℃ at a temperature increasing rate of 40℃ / h, 50℃ / h, 60℃ / h, 70℃ / h or 80℃ / h, and keeping the temperature for 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, and then water quenching to obtain a Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS compound; preferably, the specific process of the reaction is: increasing the temperature to 1050℃ in 16 hours, keeping the temperature at 1050℃ for 6h, and then water quenching to obtain a Sn0.79 Sb 0.06 Ge 0.15 Te-x%CdS compound;

[0014] Preferably, in step S3, the sintering adopts spark plasma sintering or hot-press sintering, the rate of temperature rise to the sintering temperature is 5℃ / min, 10℃ / min, 20℃ / min, 30℃ / min, 40℃ / min, 50℃ / min, 60℃ / min, 70℃ / min, 80℃ / min, 90℃ / min, 100℃ / min, 110℃ / min, 120℃ / min, 130℃ / min, 140℃ / min or 150℃ / min; the sintering temperature is 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃; the sintering pressure is 10Mpa, 20Mpa, 30Mpa, 40Mpa, 50Mpa, 70Mpa or 100Mpa; the sintering time is 5min, 10min, 20min, 40min, 60min, 80min, 100min or 120min. Preferably, in the spark plasma sintering process, the temperature is raised from room temperature to 500℃ in 7min, and the temperature and pressure are maintained at 500℃ and 40MPa for 10min.

[0015] The above technical solution has the following advantages:

[0016] The experiment uses non-toxic and environmentally friendly tin and tellurium elements as raw materials, which solves the problem of lead toxicity in traditional lead telluride-based thermoelectric materials from the source, and the prepared P-type tin telluride thermoelectric material has low thermal conductivity, which is conducive to maintaining the temperature difference between the two ends of the thermoelectric arm; at the same time, low thermal conductivity leads to high thermoelectric figure of merit, which is conducive to obtaining high thermoelectric conversion efficiency. At the same time, the preparation method of the thermoelectric material has the advantages of simple process, easy to scale production and strong practicability. The prepared Sn 0.79 Sb 0.06 Ge 0.15 The thermal conductivity of the Te-4%CdS material at 323 K is 2.8 W m -1 K -1 , and the thermal conductivity at 874K is 1.5 W m -1 K -1 . BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The powder X-ray diffraction pattern of the Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS material in Examples 1-3 of the present application;

[0018] Figure 2 Sn for the present invention examples 1-3 0.79 Sb 0.06 Ge 0.15 Temperature dependence of the electrical conductivity of the Te-x%CdS material;

[0019] Figure 3 Sn for the present invention examples 1-3 0.79 Sb 0.06 Ge 0.15 Temperature dependence of the thermoelectric power of the Te-x%CdS material;

[0020] Figure 4 Sn for the present invention examples 1-3 0.79 Sb 0.06 Ge 0.15 Temperature dependence of the thermal conductivity of the Te-x%CdS material;

[0021] Figure 5 Sn for the present invention examples 1-3 0.79 Sb 0.06 Ge 0.15 Temperature dependence of the thermoelectric figure of merit of the Te-x%CdS material; DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0023] Prepare Sn particles, Sb particles, Ge particles, Cd particles, Te particles and S particles. The purity of Sn particles is 99.99% (produced by Hebei Luohong Technology Co., Ltd.), the purity of Sb particles is 99.99% (produced by Hebei Luohong Technology Co., Ltd.), the purity of Ge particles is 99.999% (produced by Hebei Luohong Technology Co., Ltd.), the purity of Cd particles is 99.99% (produced by Hebei Luohong Technology Co., Ltd.), the purity of Te particles is 99.99% (produced by Hebei Luohong Technology Co., Ltd.), and the purity of S particles is 99.999% (produced by Hebei Luohong Technology Co., Ltd.).

[0024] Example 1 Sn 0.79 Sb 0.06 Ge 0.15 Preparation of Te-2%CdS

[0025] 1) Sn, Sb, Ge, Cd, Te and S elements were weighed according to the atomic ratio respectively, and poured into a dried quartz tube, and the quartz tube was sealed after vacuumizing by using hydrogen-oxygen flame;

[0026] 2) The sealed vacuum quartz tube in step 1) was placed in a muffle furnace for solid phase reaction, and the reaction condition was that the temperature was uniformly increased from room temperature to 1050 DEG C for 16 hours, and the temperature was kept at 1050 DEG C for 6 hours, and then water quenching was performed to obtain Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS ingot.

[0027] 3) The ingot obtained in step 2) was manually ground for 30 min, and then discharge plasma spark sintering was performed at 550 DEG C, 200 MPa and vacuum for 5 min to obtain the thermoelectric material.

[0028] Example 2 Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS preparation

[0029] 1) Sn, Sb, Ge, Cd, Te and S elements were weighed according to the atomic ratio respectively, and poured into a dried quartz tube, and the quartz tube was sealed after vacuumizing by using hydrogen-oxygen flame;

[0030] 2) The sealed vacuum quartz tube in step 1) was placed in a muffle furnace for solid phase reaction, and the reaction condition was that the temperature was uniformly increased from room temperature to 1050 DEG C for 16 hours, and the temperature was kept at 1050 DEG C for 6 hours, and then water quenching was performed to obtain Sn 0.79 Sb 0.06 Ge 0.15 Te-4%CdS ingot.

[0031] 3) The ingot obtained in step 2) was manually ground for 30 min, and then discharge plasma spark sintering was performed at 550 DEG C, 200 MPa and vacuum for 5 min to obtain the thermoelectric material.

[0032] Example 3 Sn 0.79 Sb 0.06 Ge 0.15 Te-4%CdS preparation

[0033] 1) Sn, Sb, Ge, Cd, Te and S elements were weighed according to the atomic ratio respectively, and poured into a dried quartz tube, and the quartz tube was sealed after vacuumizing by using hydrogen-oxygen flame;

[0034] 2) The sealed vacuum quartz tube in step 1) was placed in a muffle furnace for solid phase reaction, and the reaction condition was that the temperature was uniformly increased from room temperature to 1050 DEG C for 16 hours, and the temperature was kept at 1050 DEG C for 6 hours, and then water quenching was performed to obtain Sn0.79 Sb 0.06 Ge 0.15 Te-6%CdS ingot.

[0035] 3) The ingot obtained in step 2) is manually ground for 30 minutes, and then sintered by discharge plasma spark sintering for 5 minutes under the conditions of 550℃, 200MPa and vacuum to obtain the thermoelectric material.

[0036] Comparative Example 1: Preparation of SnTe

[0037] 1) Weigh out the elements Sn and Te according to their atomic ratio, pour them into a dried quartz tube, evacuate the tube, and seal it with an oxyhydrogen flame.

[0038] 2) Place the sealed vacuum quartz tube from step 1) into a muffle furnace for solid-phase reaction. The reaction conditions are: the temperature is raised from room temperature to 1050℃ at a constant rate for 16 hours, and held at 1050℃ for 6 hours. The SnTe ingot is obtained by water quenching.

[0039] 3) The ingot obtained in step 2) is manually ground for 30 minutes, and then sintered by discharge plasma spark sintering for 5 minutes under the conditions of 550℃, 200MPa and vacuum to obtain the thermoelectric material.

[0040] Performance testing:

[0041] 1) First, weigh out 0.5 g of Sn. 0.79 Sb 0.06 Ge 0.15 Te-x%CdS compounds (prepared in Examples 1-3) and SnTe (prepared in Comparative Example 1) were then ground into powder samples using an agate mortar and pestle for powder X-ray diffraction analysis. See attached... Figure 1 As shown. The test angle was 10–90 degrees. The X-ray diffraction peaks of the prepared samples were in perfect agreement with the tin telluride standard card, and no impurity phases were observed. XRD results showed that CdS and Sn... 0.79 Sb 0.06 Ge 0.15 Te formed a solid solution phase.

[0042] 2) The electrical properties of the materials prepared in Examples 1-3 and Comparative Example 1 were tested using the ZEM-3 thermoelectric material testing system from Advance Riko, Japan. The relationship between electrical conductivity and thermoelectric potential coefficient as a function of temperature is shown in the attached figure. Figure 2 and attached Figure 3 As shown. The electrical conductivity of the prepared material decreases with increasing temperature. The conductivity decreases with increasing CdS content. At 874 K, SnTe (Comparative Example 1), Sn 0.79 Sb 0.06 Ge0.15 Te-2%CdS (Example 1), Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS (Example 2) and Sn 0.79 Sb 0.06 Ge 0.15 The conductivity of Te-4%CdS (Example 3) was 1003 S cm⁻¹. -1 841 S cm -1 801 S cm -1 and 740 S cm -1 The absolute value of the thermoelectric potential of the prepared material increases with increasing temperature. At 874 K, SnTe, Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS, Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS and Sn 0.79 Sb 0.06 Ge 0.15 The thermoelectric potentials of Te-4%CdS are 135 μV K. -1 172μV K -1 180 μV K -1 and 181μV K -1 .

[0043] 3) The thermal diffusivity D of the materials prepared in Examples 1-3 and Comparative Example 1 was tested using a Netzsch LFA 467 laser flare thermal conductivity meter. Thermal conductivity was determined by κ = C. p Dρ is calculated, density ρ is obtained by Archimedes' method, and specific heat C is obtained by calculation. p Calculated using the Dulong-Petty formula. The relationship between thermal conductivity and temperature is shown in the attached figure. Figure 4 As shown. The thermal conductivity of the prepared material decreases with increasing temperature. At 874 K, SnTe and Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS, Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS and Sn 0.79 Sb 0.06 Ge 0.15 The thermal conductivity of Te-4%CdS is 8.73 W / m. -1 K -1 2.98 Wm -1 K -1 2.9 W m-1 K −1 and 2.85 W m -1 K -1 At 874K, SnTe, Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS, Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS and Sn 0.79 Sb 0.06 Ge 0.15 The thermal conductivity of Te-4%CdS is 2.82 W / m. -1 K -1 1.78 Wm -1 K -1 1.71 W m -1 K -1 and 1.57 W m -1 K -1 . Figure 5 Sn in Embodiments 1-3 and Comparative Example 1 of the present invention 0.79 Sb 0.06 Ge 0.15 Thermoelectric figure of merit of Te-3%CdS and SnTe materials as a function of temperature is shown in the attached figure. Figure 5 As shown, at 874K, SnTe and Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS, Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS and Sn 0.79 Sb 0.06 Ge 0.15 The thermoelectric figures of merit for Te-4%CdS are 0.56, 1.22, 1.32 and 1.34, respectively.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low thermal conductivity SnTe-based thermoelectric material, characterized by: The low thermal conductivity tin telluride-based thermoelectric material has the chemical formula Sn. 0.79 Sb 0.06 Ge 0.15 Te-x%CdS; Here Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS represents Sn 0.79 Sb 0.06 Ge 0.15 Te's mass meter, in Sn 0.79 Sb 0.06 Ge 0.15 x% of CdS is dissolved in Te, where x is greater than or equal to 1 and x is less than or equal to 6.

2. The low thermal conductivity tin telluride-based thermoelectric material of claim 1, wherein: The low thermal conductivity Sn-Te-based thermoelectric material is Sn 0.79 Sb 0.06 Ge 0.15 Te-2%CdS, Sn 0.79 Sb 0.06 Ge 0.15 Te-3%CdS or Sn 0.79 Sb 0.06 Ge 0.15 Te-4%CdS.

3. A method of producing a low thermal conductivity SnTe-based thermoelectric material as claimed in claim 1 or 2, characterized by, Specifically comprising the following steps: S1, preparing raw materials Sn particles, Sb particles, Ge particles, Cd particles, Te particles and S particles; S2, Sn, Sb, Ge, Cd, Te and S are weighed according to the atomic ratio, poured into a quartz tube after drying, vacuumed and sealed with hydrogen oxygen flame, and Sn is obtained after reaction 0.79 Sb 0.06 Ge 0.15 Te-x%CdS ingot S3, grinding the ingot obtained in step S2, and then sintering to obtain the thermoelectric material.

4. The production method according to claim 3, characterized by: In step S2, the specific process of the reaction is: 10-18 hours from room temperature to 1000-1150℃, and keep the temperature for 5-8h, water quenching to obtain Sn 0.79 Sb 0.06 Ge 0.15 Te-x%CdS compound; the heating rate is 40-80℃ / h.

5. The preparation method according to claim 3, characterized in that, In step S3, the sintering is performed by using a discharge plasma spark sintering or a hot-pressing sintering, the sintering temperature is 400-600℃, the sintering time is 5-120min, and the temperature rising rate is 5-150℃ / min.

6. The preparation method according to claim 3, characterized in that, In step S3, the sintering is performed at a temperature of 400-600℃ and a pressure of 10-250MPa.

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