期刊
PHYSICAL REVIEW LETTERS
卷 119, 期 8, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.119.085501
关键词
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资金
- National Basic Research Program of China (973-program) [2013CB632505]
- 111 Project of China [B07040]
- Materials Project by Department of Energy Basic Energy Sciences Program [EDCBEE]
- DOE [DE-AC02-05CH11231]
- China Postdoctoral Science Foundation [408-32200031]
- National Aeronautics and Space Administration
- NASA
- U.S. Nuclear Regulatory Commission (NRC) [NRC-HQ-84-15-G-0028]
- Act 211 Government of the Russian Federation [02.A03.21.0011]
- Supercomputer Simulation Laboratory of South Ural State University
- NSF [DMR-1436985]
Bismuth telluride (Bi2Te3) based thermoelectric (TE) materials have been commercialized successfully as solid-state power generators, but their low mechanical strength suggests that these materials may not be reliable for long-term use in TE devices. Here we use density functional theory to show that the ideal shear strength of Bi2Te3 can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi2Te3 is the weak van derWaals interaction between the Te1 coupling two Te1-Bi-Te2-Bi-Te1 five-layer quint substructures. However, we demonstrate here a surprising result that forming twin boundaries between the Te1 atoms of adjacent quints greatly strengthens the interaction between them, leading to a tripling of the ideal shear strength in nanotwinned Bi2Te3 (0.6 GPa) compared to that in the single crystalline material (0.19 GPa). This grain boundary engineering strategy opens a new pathway for designing robust Bi2Te3 TE semiconductors for high-performance TE devices.
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