Effects of temperature and intrinsic structural defects on mechanical properties and thermal conductivities of InSe monolayers

VT Pham and TH Fang, SCIENTIFIC REPORTS, 10, 15082 (2020).

DOI: 10.1038/s41598-020-72162-9

We conduct molecular dynamics simulations to study the mechanical and thermal properties of monolayer indium selenide (InSe) sheets. The influences of temperature, intrinsic structural defect on the tensile properties were assessed by tensile strength, fracture strain, and Young's modulus. We found that the tensile strength, fracture strain, and Young's modulus reduce as increasing temperature. The results also indicate that with the existence of defects, the stress is concentrated at the region around the vacancy leading to the easier destruction. Therefore, the mechanical properties were considerably decreased with intrinsic structural defects. Moreover, Young's modulus is isotropy in both zigzag and armchair directions. The point defect almost has no influence on Young's modulus but it strongly influences the ultimate strength and fracture strain. Besides, the effects of temperature, length size, vacancy defect on thermal conductivity (kappa) of monolayer InSe sheets were also studied by using none-equilibrium molecular dynamics simulations. The kappa significantly arises as increasing the length of InSe sheets. The kappa of monolayer InSe with infinite length at 300 K in armchair direction is 46.18 W/m K, while in zigzag direction is 45.87 W/m K. The difference of kappa values in both directions is very small, indicating the isotropic properties in thermal conduction of this material. The kappa decrease as increasing the temperature. The kappa goes down with the number of atoms vacancy defect increases.

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