A Bi2Te 2.7 Se 0.3 GaAs-AgBiSe2 composite thermoelectric materials and their preparation methods
By introducing AgBiSe2 nanoparticles and GaAs into the Bi2Te2.7Se0.3 matrix, an interfacial barrier and phonon scattering center are formed, which solves the problems of poor mechanical properties and high thermal conductivity of Bi2Te3-based materials and achieves a significant improvement in thermoelectric performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NAT UNIV OF DEFENSE TECH
- Filing Date
- 2023-09-04
- Publication Date
- 2026-07-24
Smart Images
Figure HDA0004429945510000011 
Figure HDA0004429945510000012 
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Abstract
Description
Technical Field
[0001] This invention relates to the field of thermoelectric material preparation technology, and particularly to a Bi2Te 2.7 Se 0.3 -GaAs-AgBiSe2 composite thermoelectric material and its preparation method. Background Technology
[0002] Bi₂Te₃-based thermoelectric materials, as typical room-temperature thermoelectric materials, are widely used in thermoelectric refrigeration, precision temperature control, and waste heat recovery. Furthermore, it is a typical narrow bandgap (~0.13 eV) semiconductor with the highest power factor known to date. Commercially available single crystals are often obtained through controlled growth via melting and then mechanically cut to fabricate devices. However, these materials have low mechanical properties, high strength, and high scrap rates during processing, making miniaturization of devices difficult. Therefore, researchers have used powder metallurgy and other methods to prepare polycrystalline Bi₂Te₃-based materials to improve their mechanical properties; however, the conversion efficiency of these thermoelectric materials remains low, limiting their commercial applications. Different doping methods on the Bi₂Te₃ matrix have yielded p-type and n-type semiconductor thermoelectric materials with different conductivity types. 2.7 Se 0.3 (BTS) alloy is a known high-performance n-type Bi2Te3-based thermoelectric material, but its ZT value is limited by its high thermal conductivity. Summary of the Invention
[0003] In view of this, the present invention aims to provide a Bi2Te 2.7 Se 0.3 -GaAs-AgBiSe2 composite thermoelectric material and its preparation method.
[0004] AgBiSe2 is an n-type thermoelectric material with intrinsically low thermal conductivity (0.45 W / m² at 300 K). -1 K -1 The carrier concentration is ~10¹⁸ cm⁻¹. -3 At low temperatures (T < 393 K), it exhibits a hexagonal structure (α phase); at medium temperatures (393 K < T < 560 K), it transforms into an orthorhombic structure (β phase); and at high temperatures (T > 560 K), it converts to a cubic structure (γ phase). By introducing AgBiSe2 nanoparticles and GaAs into the BTS matrix, the composite phase and the matrix have different band structures, resulting in an interfacial barrier that filters carrier energy, significantly improving the Seebeck coefficient and thus optimizing its power factor. Simultaneously, the composite phase acts as a phonon scattering center, hindering phonon motion and suppressing its lattice thermal conductivity.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a Bi2Te 2.7 Se 0.3 The preparation method of GaAs-AgBiSe2 composite thermoelectric material includes the following steps:
[0006] (1) Add selenium powder to ethylenediamine, heat and reflux in an oil bath at 150°C, stir magnetically, and after boiling, use residual heat to evaporate the ethylenediamine and dissolve it in ethylene glycol while hot to form a selenium anion precursor.
[0007] (2) Ethylene glycol, silver nitrate, bismuth chloride and glycerol were added to the selenium anion precursor obtained in step (1), stirred and dissolved, reacted at 180°C for 6 h, and the precipitate was collected after cooling to room temperature and washed and dried to obtain AgBiSe2 nanoparticles.
[0008] (3) Combine GaAs material and Bi2Te 2.7 Se 0.3 After grinding the matrix separately, it is mixed evenly with the AgBiSe2 nanoparticles obtained in step (2) and then ground again. Then, vacuum hot pressing sintering is performed to obtain a dense bulk.
[0009] Preferably, the ratio of selenium powder to ethylenediamine in step (1) is 3 mmol: 30-80 ml.
[0010] Preferably, the molar ratio of the selenium powder, silver nitrate, and bismuth chloride is 3:6:6.
[0011] Preferably, the washing in step (2) is performed using distilled water and anhydrous ethanol, respectively.
[0012] Preferably, the amount of AgBiSe2 nanoparticles in step (3) is 0.1-0.5 wt% of the obtained bulk material, more preferably 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, and most preferably 0.1 wt% and 0.2 wt%; the amount of GaAs is 0.1-0.8 wt% of the obtained bulk material, more preferably 0.3 wt%.
[0013] Preferably, the vacuum hot pressing sintering conditions in step (3) are: temperature of 523-673K, time of 0.5-2h, and pressure of 20-500MPa.
[0014] Preferably, the grinding time in step (3) is 20-30 min.
[0015] The present invention also provides Bi2Te prepared by the preparation method described in the above technical solution. 2.7 Se 0.3 -GaAs-AgBiSe2 composite thermoelectric material.
[0016] Beneficial technical effects:
[0017] By incorporating appropriate amounts of GaAs and AgBiSe2 nanoparticles into BTS, this invention can fully utilize the excellent properties of GaAs and AgBiSe2 materials, synergistically regulate and improve the thermoelectric properties of the materials, so that the ZT value of the composite system sample reaches a maximum of 1.32 at 346K, which is ~106.3% higher than that of the matrix BTS (0.64). Attached Figure Description
[0018] Figure 1 The XRD diffraction pattern of AgBiSe2 prepared in Example 1;
[0019] Figure 2 Bi2Te 2.7 Se 0.3 Bi2Te obtained in Examples 1-2 2.7 Se 0.3 XRD diffraction pattern of the GaAs-AgBiSe2 composite sample;
[0020] Figure 3 The composite sample (1) obtained in Example 5 and the uncomposite Bi2Te 2.7 Se 0.3 (2) XRD patterns obtained at a slow scan rate of 2° / min;
[0021] Figure 4 The matrix is BTS, and the Bi2Te obtained in Example 1 is also used. 2.7 Se 0.3 -0.3wt% GaAs -0.1wt% AgBiSe2, Bi2Te obtained in Example 2 2.7 Se 0.3 ZT value versus temperature for -0.3wt% GaAs-0.2wt% AgBiSe2;
[0022] Figure 5 The matrix is BTS, and the composite sample is Bi2Te. 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te 2.7 Se 0.3 Thermal transport properties of -0.3wt% GaAs-0.2wt% AgBiSe2. Detailed Implementation
[0023] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.
[0024] Example 1
[0025] (1) Preparation of selenium anion precursor
[0026] Weigh 0.2369 g (3 mmol) of elemental selenium powder, add 50 mL of ethylenediamine, heat to reflux at 150 °C in an oil bath, stir magnetically, and after boiling, use the residual heat to evaporate the ethylenediamine, and dissolve it in 10 mL of ethylene glycol while hot to form a selenium anion precursor.
[0027] (2) Preparation of AgBiSe2 nanoparticles
[0028] The prepared selenium anion precursor was added to a 70 mL high-pressure reactor lined with polytetrafluoroethylene, followed by the addition of 10 mL ethylene glycol, 1.0192 g (6 mmol) silver nitrate, 1.892 g (6 mmol) bismuth chloride, and 30 mL glycerol. The mixture was magnetically stirred to ensure complete decomposition of the particles in the solvent. The reactor was then sealed and placed in an oven at 180 °C for 6 hours. After cooling to room temperature, the particles were washed with distilled water and anhydrous ethanol to remove impurities and dried to obtain AgBiSe2 nanoparticles.
[0029] The obtained AgBiSe2 nanoparticles were characterized by XRD, such as... Figure 1 As shown, the results indicate that, except for a few diffraction peaks with weak diffraction intensity, the remaining characteristic diffraction peaks can be well matched with the AgBiSe2 phase (JCPDS#74-0842), indicating that AgBiSe2 nanoparticles were successfully synthesized.
[0030] (3)Bi2Te 2.7 Se 0.3 Preparation of GaAs-AgBiSe2 composite samples
[0031] BTS ingots were ground into powder using a mortar and pestle for 30 minutes, ensuring uniform and consistent grinding force each time. GaAs sheet material was then vibratory ball-milled for 1 hour to prepare nanoscale GaAs powder. The mixture of AgBiSe2 nanoparticles (0.1 wt%) and ground GaAs powder (0.3 wt%) was then mixed with the BTS powder obtained through grinding, and finely ground in a mortar for 20 minutes to obtain a fine and relatively uniform composite powder. This powder was then placed in a tungsten carbide mold with an inner diameter of 13 mm and vacuum hot-pressed at 623 K and 250 MPa for 1 hour to obtain a dense bulk material, denoted as Bi2Te. 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2.
[0032] Example 2
[0033] Same as Example 1, except that the AgBiSe2 nanoparticles were mixed with the ground GaAs powder at a concentration of 0.2 wt% and the BTS powder obtained by grinding at a concentration of 0.3 wt%, and the mixture was denoted as Bi2Te. 2.7 Se 0.3 -0.3wt%GaAs-0.2wt%AgBiSe2.
[0034] Example 3
[0035] Same as Example 1, except that the AgBiSe2 nanoparticles were mixed with the ground GaAs powder at a concentration of 0.3 wt% and the BTS powder obtained by grinding at a concentration of 0.1 wt%, and the mixture was denoted as Bi2Te. 2.7 Se 0.3 -0.1wt%-GaAs-0.3wt%AgBiSe2.
[0036] Example 4
[0037] Same as Example 1, except that the AgBiSe2 nanoparticles were mixed with the ground GaAs powder at a concentration of 0.4 wt% and the BTS powder obtained by grinding at a concentration of 0.2 wt%, and the mixture was denoted as Bi2Te. 2.7 Se 0.3 -0.2wt%GaAs-0.4wt%AgBiSe2.
[0038] Example 5
[0039] Same as Example 1, except that the AgBiSe2 nanoparticles were mixed with the ground GaAs powder at a concentration of 0.5 wt% and the BTS powder obtained by grinding at a concentration of 0.2 wt%, and the mixture was denoted as Bi2Te. 2.7 Se 0.3 -0.8wt%GaAs-0.5wt%AgBiSe2.
[0040] The composite materials obtained from AgBiSe2 nanoparticles and GaAs with different doping amounts in Examples 1 and 2 were characterized by XRD. Figure 2 It can be seen that the diffraction peaks of all samples perfectly match those of the standard card (JCPDS No. 50-0954). Secondly, due to the relatively low proportions of GaAs and AgBiSe2 in the composite sample, no corresponding diffraction peaks were found in the fast scan diffraction pattern, but these peaks were observed in the slow scan pattern at a scan rate of 2° / min. Figure 3Among them, the peak marked with a diamond shape is the (111) diffraction peak of GaAs, and the peak marked with a circle is the (104) diffraction peak of AgBiSe2. It can be observed that the main peaks of GaAs phase and AgBiSe2 phase are at 2θ = 27.3° and 2θ = 30.8°, respectively. This indicates that GaAs phase and AgBiSe2 phase do exist in the hot-pressed bulk of the composite sample.
[0041] Experimental example:
[0042] 1. Testing the thermoelectric figure of merit ZT
[0043] like Figure 4 As shown, the matrix is BTS and the substrate is Bi2Te. 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te 2.7 Se 0.3 The graph shows the relationship between ZT values and temperature for Bi₂Te₂ (-0.3wt% GaAs-0.2wt% AgBiSe₂). From the graph, it can be seen that... 2.7 Se 0.3 -0.3wt% GaAs -0.1wt% AgBiSe2 and Bi2Te 2.7 Se 0.3 The ZT values of -0.3wt% GaAs and -0.2wt% AgBiSe2 were 1.32 and 1.04, respectively, which were significantly improved compared to the matrix BTS throughout the entire test temperature range.
[0044] The significant improvement in the thermoelectric performance of the dual-composite sample is attributed to the strong scattering of mid-to-high frequency phonons by the composite GaAs, which reduces thermal conductivity, and the strong energy filtering effect caused by the composite AgBiSe2, which enhances the thermoelectric potential. Simultaneously compositing GaAs and AgBiSe2 nanophases in BTS effectively leverages the respective advantages of the two composite phases, synergistically regulating electrical and thermal transport properties, ultimately achieving a substantial improvement in thermoelectric performance.
[0045] 2. Test thermal conductivity
[0046] The matrix BTS and Bi2Te were tested separately. 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te 2.7 Se 0.3 Thermal conductivity of -0.3wt% GaAs-0.2wt% AgBiSe2, such as Figure 5 The figure shows the matrix BTS and the composite sample Bi2Te. 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te2.7 Se 0.3 Thermal transport properties of the composite sample Bi2Te (0.3wt% GaAs-0.2wt% AgBiSe2). The figure shows that, across the entire temperature range, the composite sample Bi2Te... 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te 2.7 Se 0.3 The overall thermal conductivity of -0.3wt% GaAs-0.2wt% AgBiSe2 is significantly lower than that of the matrix BTS. For example, at 300 K, the overall thermal conductivity of the matrix BTS is 1.39 W / m². -1 K -1 The composite sample Bi2Te 2.7 Se 0.3 -0.3wt%GaAs-0.1wt%AgBiSe2, Bi2Te 2.7 Se 0.3 The total thermal conductivity of -0.3wt% GaAs and -0.2wt% AgBiSe2 is 0.78 W / m. - 1 K -1 0.80W m -1 K -1 The thermal conductivity of the two materials decreased by approximately 43.9% and 42.4% respectively compared to the base BTS.
[0047] The above experimental results show that introducing appropriate amounts of AgBiSe2 nanoparticles and GaAs into the BTS matrix can significantly reduce the thermal conductivity of the material and increase its ZT value.
[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A Bi2Te 2.7 Se 0.3 The method for preparing GaAs-AgBiSe2 composite thermoelectric materials is characterized by... Includes the following steps: (1) Add selenium powder to ethylenediamine, heat and reflux in an oil bath at 150 °C, stir magnetically, and after boiling, use residual heat to evaporate the ethylenediamine and dissolve it in ethylene glycol while hot to form a selenium anion precursor. (2) Ethylene glycol, silver nitrate, bismuth chloride and glycerol were added to the selenium anion precursor obtained in step (1), stirred and dissolved, reacted at 180 °C for 6 h, and the precipitate was collected after cooling to room temperature and washed and dried to obtain AgBiSe2 nanoparticles. (3) Combine GaAs material and Bi2Te 2.7 Se 0.3 After grinding the matrix separately, it is mixed evenly with the AgBiSe2 nanoparticles obtained in step (2) and then ground again. Then, vacuum hot pressing sintering is performed to obtain a dense bulk. In step (3), the amount of AgBiSe2 nanoparticles is 0.1-0.5 wt% of the obtained bulk material, and the amount of GaAs is 0.1-0.8 wt% of the obtained bulk material.
2. The preparation method according to claim 1, characterized in that, The ratio of selenium powder to ethylenediamine in step (1) is 3 mmol: 30-80 ml.
3. The preparation method according to claim 1, characterized in that, The molar ratio of selenium powder, silver nitrate and bismuth chloride is 3:6:
6.
4. The preparation method according to claim 1, characterized in that, The washing in step (2) involves washing with distilled water and anhydrous ethanol, respectively.
5. The preparation method according to claim 1, characterized in that, The vacuum hot pressing sintering conditions in step (3) are: temperature of 523-673 K, time of 0.5-2 h, and pressure of 20-500 MPa.
6. The preparation method according to claim 1, characterized in that, The grinding time in step (3) is 20-30 min.
7. The Bi₂Te prepared by the preparation method according to any one of claims 1-6 2.7 Se 0.3 -GaAs-AgBiSe2 composite thermoelectric material.