Journal of Inorganic Materials ›› 2019, Vol. 34 ›› Issue (3): 335-340.

### Multi-doping in SnTe: Improvement of Thermoelectric Performance due to Lower Thermal Conductivity and Enhanced Power Factor

TAN Xiao-Fang1,2, DUAN Si-Chen1, WANG Hong-Xiang1,3, WU Qing-Song4, LI Miao-Miao5, LIU Guo-Qiang1,3, XU Jing-Tao1,3, TAN Xiao-Jian1,3, SHAO He-Zhu1,3, JIANG Jun1,3

1. 1. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Science, Ningbo 315201, China;
2. Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, China;
3. University of Chinese Academy of Sciences, Beijing 100049, China;
4. Laboratory of Advanced Materials, Fudan University, Shanghai 200438, China;
5. College of Mechanics and Materials, Hohai University, Nanjing 210098, China;
• Received:2018-06-21 Published:2019-03-20 Online:2019-02-26
• About author:TAN Xiao-Fang (1993-), female, Master. E-mail: txf082@mail.ustc.edu.cn
• Supported by:
National Key Research and Development Program of China (2016YFC0101801, 2017YFC0111602);Natural Science Foundation of Zhejiang Province (LY18A040008, LY18E020017);Zhejiang Provincial Science Fund for Distinguished Young Scholars (LR16E020001);Youth Innovation Promotion Association of CAS under Grant No. 2018337

Abstract:

In recent years, tin telluride (SnTe) has attracted considerable interest due to its potential thermoelectric application as a lead-free rock-salt analogue of PbTe. However, pristine SnTe samples show high thermal conductivity and low Seebeck coefficients, resulting in poor thermoelectric performance. In this study, the thermoelectric performance of SnTe was enhanced by well-designed multi-doping, where significantly reduced thermal conductivity and improved Seebeck coefficientswere achieved at the same time. The doped SnTe samples were prepared by hot pressing. The lattice thermal conductivity of SnTe samples is obviously decreased by alloying with Se and S. The transmission electron microscope shows the existence of larger amount of nano-precipitates and the lattice distortions in the alloyed samples. For example, the lattice thermal conductivity of SnTe0.7S0.15Se0.15 sample is reduced to 0.99 W•m-1•K-1 at 300 K. The results reveal that the Seebeck coefficients are improved by introducing In resonant state in the band structure of SnTe. The experiments suggest the effectiveness of designed multi-doping in the thermoelectric performance enhancement of SnTe, and a promising ZT of 0.8 at 850 K is achieved in Sn0.99In0.01Te0.7S0.15Se0.15. The discovery suggests that SnTe is a promising medium-temperature thermoelectric candidate.

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