期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 6, 期 15, 页码 6493-6502出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c8ta00631h
关键词
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资金
- National Natural Science Foundation of China (NSFC) [51472262, 51625205]
- Key Research Program of Chinese Academy of Sciences [KFZD-SW-421]
- International S&T Cooperation Program of China [2015DFA51050]
- Shanghai Government [15JC1400301]
- Youth Innovation Promotion Association, CAS [2016232]
High-symmetry crystal structures are preferred for thermoelectrics because high structural symmetry usually yields good electron transport properties. Entropy engineering is an effective approach to improve the structural symmetry of low-symmetry materials, and thus to enhance their thermoelectric performance. In this study, via introducing Te into the argyrodite-type compound Cu7PSe6, the configurational entropy is significantly increased to successfully improve its initial low-symmetry cubic structure (P2(1)3) to the high-symmetry cubic structure (F (4) over bar 3m)at room temperature. Such improved structural symmetry leads to a high density-of-state effective mass but similar carrier mobility in the same carrier concentration range as compared with the pristine Cu7PSe6. Thus, significantly optimized electron transport properties are achieved in the Te-alloyed Cu7PSe6 samples. In particular, at room temperature, the power factor of the high-symmetry cubic Cu7PSe5.7Te0.3 sample is about 15-times higher than that of the low-symmetry Cu7PSe6 matrix. Combining the well-maintained ultralow lattice thermal conductivity, a maximum ZT of around 0.55 at 600 K is obtained in Cu7PSe5.7Te0.3. This work strongly shows that entropy engineering using multiple components is a very powerful strategy to discover or design novel high-performance TE materials starting from low-symmetry compounds.
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