Nanoscale fracture of defective popgraphene monolayer

Abstract

A new carbon allotrope, namely popgraphene, has been recently demonstrated to possess high potentials for nanodevice applications. Here, the fracture of defective popgraphene was studied using molecular dynamics simulations and continuum modeling. Three scenarios of defects were considered, including an individual point defect, distributed point defects, and nanocracks. It was found that the fracture stress of popgraphene with an individual point defect was governed by both the geometry of the defect and the critical bond where fracture initiates.Moreover, the fracture stress of popgraphene with distributed point defects was discovered to be inversely proportional to the defect density, showing a nice linear trend. Furthermore, for popgraphene with a nanocrack, it failed in a brittle fashion and exhibited a negligible lattice trapping effect. Griffith criterion was subsequently employed with the consideration of crack deflection to accurately predict the dependence of fracture stress on crack size. The present study lays a mechanistic foundation for nanoscale applications of popgraphene and offers a better understanding of the roles of defects in fracture of low-dimensional materials. (Dong Wei) i) Individual point defect: SV and DV were created by removing one and two atoms respectively from the popgraphene, while SW was formed by rotating a bond in popgraphene by 90°. The unique lattice sites where defects can form were illustrated in Fig. 2a. For SV, two defect configurations are possible, denoted as SV α and SV β as shown in Fig. 2b, while for DV and SW, each can have three defect configurations, denoted as DV αβ , DV βγ , and DV δη , and SW αβ , SW βγ , and SW δη , respectively, the atomic configurations of which were shown in Fig. 2cd, respectively.