Role of 1D edge in the elasticity and fracture of h-BN doped graphene nanoribbons

Recent achievement of BN-graphene alloy material has enabled the potential of bandgap tuning through both sub-10 nm width control and BN concentration variation. However, its mechanics, which is necessary for prediction of stability in functional applications, is not well studied. Here, molecular dynamics simulation is performed to conduct uniaxial tensile test for BN-doped graphene nanoribbons (BN-GNR) with varying widths and BN atom fractions. Efforts are made to study the constitutive relations for the edges and the whole BN-GNR and explore the fracture mechanisms of the hybrid nanoribbons. The substantial softening effect of the edges induced by wrinkling alters the impact of BN concentration on the stiffness in the sub-20 nm regime deviating from the linear behaviour observed in the bulk case. Fracture properties are unexpectedly independent of BN concentrations unlike in the bulk and the failure behaviour is rather decided by the graphene ribbon edge structure. Here the armchair edges serve as the source of crack nucleation at an early stage leading to weakened strength and reduced stretchability, whereas zigzag edges do not promote early crack nucleation and leads to the size dependence of fracture properties.