Order-Tuned Deformability of Bismuth Telluride Semiconductors: An Energy-Dissipation Strategy for Large Fracture Strain.
Order-Tuned Deformability of Bismuth Telluride Semiconductors: An Energy-Dissipation Strategy for Large Fracture Strain.
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DOI：
10.1021/acsami.1c18583
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发表时间：
2021-11
影响因子：
9.5
通讯作者：
Ben Huang;Guodong Li;Bo Duan;Wenjuan Li;P. Zhai;W. Goddard
中科院分区：
文献类型：
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作者：
Ben Huang;Guodong Li;Bo Duan;Wenjuan Li;P. Zhai;W. Goddard
除了通过缺陷或应变工程调整热电(TE)性能外，机械研究的进展对于受变形能力较差限制的碲化铋(Bi2Te3)Te半导体的可穿戴应用越来越重要。为了改善位错控制的变形能力，我们阐明了一种有序调谐的能量耗散策略，该策略通过多层交替滑移和层错失稳来促进大变形。考虑到能量耗散和位错运动受van der Waals牺牲键(SB)行为的支配，用分子动力学模拟揭示了Bi2Te3晶体的剪切变形性与晶格有序变化之间的关系。采用根据位形能分布定义的无序参数(D)，应变速率和初始裂纹效应的结果表明，适当的初始结构和外部条件的设计可以抑制应变局部化，而应变局部化是由于能量耗散不足而导致结构失效，从而导致Bi2Te3纳米晶大的均匀变形。这项研究揭示了调谐机制的本质，在调谐机制中，高度变形的Bi2Te3晶体应该尽可能缓慢地变得无序，直到断裂。这突显了Sb缺陷协同作用的亚结构演化在滑移过程中促进能量耗散和性能稳定性的作用。无序参数D在微观/局部力学和断裂应变之间架起了一座桥梁，暗示了Bi2Te3半导体通过有序调节和能量耗散来设计柔性TE器件的可能的力学改进。
In addition to thermoelectric (TE) performance tuning through defect or strain engineering, progress in mechanical research is of increasing importance to wearable applications of bismuth telluride (Bi2Te3) TE semiconductors, which are limited by poor deformability. For improving dislocation-controlled deformability, we clarify an order-tuned energy-dissipation strategy that facilitates large deformation through multilayer alternating slippage and stacking fault destabilization. Given that energy dissipation and dislocation motions are governed by van der Waals sacrificial bond (SB) behavior, molecular dynamics simulation is implemented to reveal the relation between the shear deformability and lattice order changes in Bi2Te3 crystals. Using the disorder parameter (D) that is defined according to the configurational energy distribution, the results of strain rates and initial crack effects show how the proper design of the initial structure and external conditions can suppress strain localization that would cause structural failure from the lack of energy dissipation, resulting in large homogeneous deformation of Bi2Te3 nanocrystals. This study uncovers the essence of the tuning mechanism in which highly deformable Bi2Te3 crystals should become disordered as slowly as possible until fracture. This highlights the role of the substructure evolution of SB-defect synergy that facilitates energy dissipation and performance stability during slipping. The disorder parameter D provides a bridge between micro/local mechanics and fracture strain, hinting at the possible mechanical improvement of Bi2Te3 semiconductors for designing flexible TE devices through order tuning and energy dissipation.