Abstract：In this paper, by establishing a stick-spiral model of chirality-dependent hexagonal boron nitride (h-BN) which based on the Tersoff potential function between hexagonal boron nitride atoms, the nonlinear mechanical behavior of chirality-dependent h-BN under large deformation have been investigated. The findings indicate that the fracture modes of h-BN range from ductile fracture to brittle fracture when the chiral angle changes from armchair (AC, chiral angle is 0o) to zigzag (ZZ, chiral angle is 30o). That the change of bond angles plays a more important role in the stretching process than that of bond lengths is the main reason of the occurrence of ductile fracture, through the analysis of the change of bond lengths and bond angles in the stretching process. By analysing the distribution of maximum stress and fracture stress of h-BN with chiral angle, the chiral angle of brittle-ductile transition is around 15°. The change of bond length dominates the fracture mode of graphene in the stretching process, while the change of both bond length and bond angle dominate the fracture mode of h-BN, by comparison the h-BN and graphene under the same conditions. Finally, checking against the molecular dynamics simulations shows that the theoretical results are reasonable. This study provides theoretical support for understanding the excellent mechanical properties of h-BN and its application in the field of micro-nano devices.
2021, Vol. 42 
