Role of grain boundary and nanoholes in geometrical deformation and bonding energies of graphene/hexagonal boron nitride

The geometric deformation, bonding energies and mechanical properties of graphene-h-BN heterostructures (Gr-h-BN) under the coupling of external field (strain rate and temperature) and internal field (grain boundary (GBs) and nanoholes) were studied by using molecular dynamics and nonlinear mechanics. The results show that GBs and nanoholes will cause the Gr-BN-GBs configuration to deviate from the plane configuration, and produce a saddle shape with positive curvature and negative curvature, and its displacement field diverges with distance. In addition, the presence of GBs and nanoholes leads to a reduction in failure stress, Young's modulus and Von-mises stress. However, the presence of GBs and nanoholes also improves the bending rigidities of two dimensional (2D) materials. The adverse and strengthening effects induced by GBs and nanoholes are strongly dependent on temperature and strain rate. A full study of the built-in distorted stress field generated by the interaction of defects in 2D materials will help us to understand the physical mechanism of the relationship between structure and properties in low dimensions, and even design new applications. © 2022