Understanding of the Extremely Low Thermal Conductivity in High‐Performance Polycrystalline SnSe through Potassium Doping |
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| Authors: | Yue‐Xing Chen Zhen‐Hua Ge Meijie Yin Dan Feng Xue‐Qin Huang Wenyu Zhao Jiaqing He |
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| Affiliation: | 1. Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, South University of Science and Technology of China, Shenzhen, China;2. Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, China;3. State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, China |
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| Abstract: | P‐type polycrystalline SnSe and K0.01Sn0.99Se are prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). The highest ZT of ≈0.65 is obtained at 773 K for undoped SnSe by optimizing the MA time. To enhance the electrical transport properties of SnSe, K is selected as an effective dopant. It is found that the maximal power factor can be enhanced significantly from ≈280 μW m?1 K?2 for undoped SnSe to ≈350 μW m?1 K?2 for K‐doped SnSe. It is also observed that the thermal conductivity of polycrystalline SnSe can be enhanced if the SnSe powders are slightly oxidized. Surprisingly, after K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nanoprecipitates in the SnSe matrix contribute to an impressively low lattice thermal conductivity of ≈0.20 W m?1 K?1 at 773 K along the sample section perpendicular to pressing direction of SPS. This extremely low lattice thermal conductivity coupled with the enhanced power factor results in a record high ZT of ≈1.1 at 773 K along this direction in polycrystalline SnSe. |
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| Keywords: | polycrystalline SnSe thermal conductivity thermoelectric materials transmission electron microscopy |
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