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Superstrengthening Bi_{2}Te_{3} through Nanotwinning.
Guodong Li1,2, Umut Aydemir2,3, Sergey I Morozov4
1State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
Physical Review Letters
|September 28, 2017
Summary
Nanoscale twins significantly enhance the mechanical strength of bismuth telluride (Bi_{2}Te_{3}) thermoelectric materials. This grain boundary engineering approach improves the weak inter-layer interactions, paving the way for more robust thermoelectric devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Bismuth telluride (Bi_{2}Te_{3}) is a key material for thermoelectric (TE) power generation.
- Low mechanical strength limits the long-term reliability of Bi_{2}Te_{3} in TE devices.
Purpose of the Study:
- To investigate the effect of nanoscale twins on the mechanical strength of Bi_{2}Te_{3}.
- To understand the strengthening mechanism at the atomic level.
Main Methods:
- Density functional theory (DFT) calculations were employed.
- Analysis of ideal shear strength and interatomic interactions in single crystalline and nanotwinned Bi_{2}Te_{3}.
Main Results:
- Nanoscale twinning enhances the ideal shear strength of Bi_{2}Te_{3} by up to 215%.
- The weak van der Waals interaction between Te1 layers in single crystals was identified as the cause of low strength.
- Twin boundaries between Te1 atoms in adjacent quintuple layers significantly strengthen inter-layer interactions.
Conclusions:
- Nanotwinned Bi_{2}Te_{3} exhibits a tripling of ideal shear strength (0.6 GPa) compared to single crystals (0.19 GPa).
- Grain boundary engineering via nanotwinning offers a viable strategy for developing robust Bi_{2}Te_{3} thermoelectric semiconductors.
- This approach enables the design of high-performance and reliable TE devices.
