MECHANICAL PROPERTIES OF NANOCRACKS IN HYBRID GRAPHENE/HEXAGONAL BORON NITRIDE SHEETS

Graphene/hexagonal boron nitride (h-BN) is a type of hybrid material to regulate the electronic properties of pristine graphene and is recognized as having potential application in functional devices. Its fracture behavior is one of the most important parameters to affect the device performance. In this work, the fracture behaviors of hybrid graphene/h-BN sheets with cracks were studied using molecular dynamics method. Effects of the crack size, type and location on the failure behavior of the hybrid sheets were considered and analyzed. For most of the models, both Young's modulus and the fracture strength reduced with the increasing crack size. A threshold of the crack size was found for the models: when the crack size was larger than 0.1L (where L is the periodic length of the sheet), Young's modulus dropped rapidly, while the reduction of the fracture strength slowed down. Crack location had no obvious effect on the fracture strength of the hybrid sheets with a crack of c = 0 :05L. However, the fracture strength exhibited more dependence on the crack location for a relatively large crack (c = 0 :15L or 0:3L). The fracture process of the hybrid sheet with a crack usually started from the crack tips where stress concentration existed. If the crack was located in or close to the graphene/h-BN interface, the fracture usually happened in the h-BN domain. The work would provide useful mechanical property information for the applications of hybrid graphene/h-BN sheets in material devices.