Structure-dependent mechanical properties of extended beta-graphyne

Owing to their remarkable electronic and thermal properties, graphynes have been considered new promising carbon materials after graphene. However, our understanding of their structure-dependent mechanical properties is far from complete. In this paper an analytical molecular mechanics model is proposed to mathematically establish a relationship between the structure and the elastic properties of β−graphyne. Extensive molecular dynamics simulations are performed for comparison. We show that the elastic properties of β−graphyne exhibit a strong dependence on its structure. The in-plane stiffness, in-plane shear stiffness and layer modulus decrease with increasing percentage of the acetylenic linkages, while the Poisson's ratio increases. Further analysis demonstrates that this dependence of structure attributes to the change in bond density. Based on the concept of effective bond density, scaling laws are developed for the elastic properties of β−graphyne, which demonstrate a useful approach for linking mechanical properties of graphene allotropes to those of graphene.

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