International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China.
Nanotechnology. 2016 Aug 5;27(31):315704. doi: 10.1088/0957-4484/27/31/315704. Epub 2016 Jun 27.
Due to low formation energies, it is very easy to create atomic defects in phosphorene during its fabrication process. How these atomic defects affect its mechanical behavior, however, remain unknown. Here, we report on a systematic study of the effect of atomic vacancies on the mechanical properties and failure behavior of phosphorene using molecular dynamics simulations. It is found that atomic vacancies induce local stress concentration and cause early bond-breaking, leading to a significant degradation of the mechanical properties of the material. More specifically, a 2% concentration of randomly distributed mono-vacancies is able to reduce the fracture strength by ∼40%. An increase in temperature from 10 to 400 K can further deteriorate the fracture strength by ∼60%. The fracture strength of defective phosphorene is also found to be affected by defect distribution. When the defects are patterned in a line, the reduction in fracture strength greatly depends on the tilt angle and the loading direction. Furthermore, we find that di-vacancies cause an even larger reduction in fracture strength than mono-vacancies when the loading is in an armchair direction. These findings provide important guidelines for the structural design of phosphorene in future applications.
由于形成能较低，在制备磷烯的过程中很容易在原子中产生缺陷。然而，这些原子缺陷如何影响其力学性能仍不清楚。在这里，我们使用分子动力学模拟系统地研究了原子空位对磷烯力学性能和失效行为的影响。研究发现，原子空位会引起局部应力集中，并导致早期键断裂，从而显著降低材料的力学性能。更具体地说，2%浓度的随机分布单空位能够使断裂强度降低约 40%。温度从 10 增加到 400 K 还可以进一步降低约 60%的断裂强度。还发现，缺陷磷烯的断裂强度也受到缺陷分布的影响。当缺陷呈线状分布时，断裂强度的降低在很大程度上取决于倾斜角度和加载方向。此外，当加载方向为扶手椅方向时，我们发现双空位导致的断裂强度降低比单空位更大。这些发现为磷烯在未来应用中的结构设计提供了重要的指导。
