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Vol.61, No.10, 785 ~ 793, 2023
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| Title |
| Optimization of Sintering Temperature for the Synthesis of n-type Mg3SbBi0.99Te0.01 Thermoelectric Materials |
| 주성재 Sung-jae Joo , 손지희 Ji-hee Son , 장정인 Jeongin Jang , 김봉서 Bong-seo Kim , 민복기 Bok-ki Min |
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| Abstract |
| Mg3Sb2-based materials are promising candidates to replace n-type Bi2Te3 for cooling and power generation at low temperatures. Generally, the thermoelectric performance of a material is sensitively affected by synthesis process parameters, and among them, sintering temperature (Ts) is a critical one. In this study, n-type Mg3SbBi0.99Te0.01 polycrystalline samples were fabricated by mechanical alloying and spark plasma sintering (SPS), and the effects of varying Ts (923 - 1073 K) on the thermoelectric properties were investigated. Sintering Mg3SbBi0.99Te0.01 at an elevated temperature of 1073 K resulted in a notable increase in electrical conductivity at low temperatures below about 423 K. This is ascribed to a sharp reduction in carrier scattering by ionized impurities. For the same reason, the carrier mobility increased sharply at a Ts of 1073 K, which is a critical temperature for sintering in this study. Moreover, the Seebeck coefficient increased and thermal conductivity decreased simultaneously by raising Ts, resulting in the maximum power factor (PFmax) of 2.2 × 10-3 W m-1K-2 and the maximum dimensionless figure of merit (zTmax) of 1.20 in the sample sintered at 1073 K. Therefore, when Ts was raised from 923 K to 1073 K, the PFmax and zTmax increased by 29 % and 64 %, respectively. This improvement in performance is attributed to the annihilation of defects generated during the mechanical alloying process, which was confirmed by microstructure analysis by transmission electron microscopy (TEM).
(Received 21 April, 2023; Accepted 28 June, 2023) |
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| Key Words |
| Mg3SbBi0.99Te0.01, sintering temperature, mechanical alloying |
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