Nanomechanics of Antimonene Allotropes

Abstract

Monolayer antimonene has drawn the attention of research communities due to its promising physical properties. But mechanical properties of antimonene is still largely unexplored. In this work, we investigate the mechanical properties and fracture mechanisms of two stable phases of monolayer antimonene -- the $α$ antimonene ($α$-Sb) and the $β$ antimonene ($β$-Sb), through molecular dynamics (MD) simulations. Our simulations reveal that stronger chiral effect results in a greater anisotropic elastic behavior in $β$-antimonene than in $α$-antimonene. In this paper we focus on crack-tip stress distribution using local volume averaged virial stress definition and derive the fracture toughness from the crack-line stress. Our calculated crack tip stress distribution ensures the applicability of linear elastic fracture mechanics (LEFM) for cracked antimonene allotropes with considerable accuracy up to a pristine structure. We evaluate the effect of temperature, strain rate, crack-length and point-defect concentration on the strength and elastic properties. Tensile strength goes through significant degradation with the increment of temperature, crack length and defect percentage. Elastic modulus is less susceptible to temperature variation but is largely affected by the defect concentration. Strain rate induces a power law relation between strength and fracture strain. Finally, we discuss the fracture mechanisms in the light of crack propagation and establish the links between the fracture mechanism and the observed anisotropic properties.