Failure of Graphdiyne: Structurally Directed Delocalized Crack Propagation

Abstract

Among the many potential twodimensional carbon allotropes inspired by graphene, graphynes have received exceptional attention recently. Graphynes exhibit remarkable mechanical properties depending on their structure. The similar structure and twodimensional nature of these materials yield many properties that are similar to those of graphene, but the presence of heterogeneous bond types is expected to lead to distinct properties. The main subject of this work is graphdiyne, one of the few graphynes that has been fabricated in large quantities. In this paper, we perform fracture analysis on graphdiyne and find a delocalized failure mechanism in which a crack propagates along a diagonal with respect its original direction. The covalence of the material allows for this simple but intriguing phenomenon to be investigated. Graphene is also tested to compare the behavior. This mechanism has implications for the toughness and robustness of this material, which is topical for many device applications recently proposed in the literature. Further, connections of such delocalized failure mechanisms are made to that of hidden length and sacrificial bonding in some biological systems such as proteins, bone, and nacre.