Superstrengthening Bi_{2}Te_{3} through Nanotwinning.
Superstrengthening Bi_{2}Te_{3} through Nanotwinning.
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DOI：
10.1103/physrevlett.119.085501
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发表时间：
2017-08
影响因子：
8.6
通讯作者：
Guodong Li;U. Aydemir;S. Morozov;Max Wood;Q. An;P. Zhai;Qingjie Zhang;W. Goddard;G. J. Snyder
中科院分区：
文献类型：
--
作者：
Guodong Li;U. Aydemir;S. Morozov;Max Wood;Q. An;P. Zhai;Qingjie Zhang;W. Goddard;G. J. Snyder
基于碲化铋（Bi_{2}Te_{3}）的热电（TE）材料已经作为固态发电机成功商业化，但它们的低机械强度表明这些材料可能不可靠，不能长期用于TE器件。本文利用密度泛函理论表明，施加纳米孪晶可以使bi_{2} te_{3}的理想抗剪强度显著提高至215%。揭示了单晶Bi_{2}Te_{3}低强度的成因是Te1耦合两个Te1─Bi─Te2─Bi─Te1五层量子子结构之间的弱范德华相互作用。然而，我们在这里证明了一个令人惊讶的结果，在相邻五分晶的Te1原子之间形成孪晶边界大大加强了它们之间的相互作用，导致纳米孪晶Bi_{2}Te_{3}的理想剪切强度（0.6 GPa）比单晶材料（0.19 GPa）提高了三倍。这种晶界工程策略为高性能TE器件设计稳健的Bi_{2}Te_{3} TE半导体开辟了新的途径。
Bismuth telluride (Bi_{2}Te_{3}) 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 Bi_{2}Te_{3} can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi_{2}Te_{3} is the weak van der Waals 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 Bi_{2}Te_{3} (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 Bi_{2}Te_{3} TE semiconductors for high-performance TE devices.