Mechanical and thermal properties of phosphorene under shear deformation

Abstract

Phosphorene, a new two-dimensional material beyond graphene, has received increasing attention in recent years owing to its superior physical properties of significant utility. Herein we carry out molecular dynamics simulations to systematically study the mechanical and thermal properties of phosphorene under shear loadings. It is found that the shear modulus of phosphorene is about 22 GPa in both the armchair direction and zigzag direction. The fracture strength and ultimate strain of phosphorene can be significantly reduced owing to stronger thermal vibrations of atoms at a higher temperature. The thermal conductivity of pristine phosphorene at room temperature is obtained, specifically, it is 18.57 W·m^–1·K^–1 along the armchair direction and 52.52 W·m^–1·K^–1 in the zigzag direction. When either an armchair- or a zigzag-oriented shear strain is applied, the armchair-oriented thermal conductivity decreases monotonically with the strain increasing. Whereas the zigzag-oriented thermal conductivity exhibits a non-monotonic behavior. The strain-induced redshift occurs in the high-frequency phonons of out-of-plane flexural modes in the phonon density of states of the sheared phosphorene. In addition, the buckled structure of phosphorene will lead the deformation characteristics under the shear strain differ from those of the planar structure such as graphene, which has a significant influence on the lattice anharmonicity and phonon scattering. It is believed that the interplay between the shift of phonon density of states and the change of phonon scattering channels results in the unique thermal transport behavior of phosphorene under shear deformation. The findings provide an insight into the understanding of the mechanical and thermal properties of phosphorene, and have significance for the future applications in phosphorene-based novel devices.