Investigation on mechanical performances of grain boundaries in hexagonal boron nitride sheets

Abstract

In this work, molecular dynamic simulations were performed to investigate the effect of grain boundaries (GBs) on the mechanical properties and failure behaviors of hexagonal boron nitride (h-BN) nanosheets. It was confirmed that both the GB linear density and the detailed arrangements of GBs could affect the mechanical properties of h-BN sheets. The tensile tests of GB models were performed at different strain rates. Results showed that the ultimate tensile strength of GBs increased obviously with the increasing of strain rate. The effect of temperature on the mechanical properties of h-BN sheets was also discussed. Results showed that high temperature could reduce the ultimate tensile strength and Young's modulus of models containing high density of GBs. Molecular dynamics (MD) and density functional theory (DFT) calculation results indicated that the fracture behavior of GBs tended to begin at the bond with the lowest electron density. The information obtained in this work could provide evidence for further investigations of mechanical properties and failure mechanism of h-BN sheets with GBs.