Deformation mechanism of ripplocation in silicon–graphite composites

Abstract

Recently, ripplocation has been proposed as an alternative to basal dislocations for explaining the deformation of layered crystals in response to compressive strain. Thus, understanding the atomic mechanisms underlying the formation, propagation, and interactions of ripplocation is crucial for investigating the effects of plastic deformation on laminated materials. In this study, we investigated the generation of ripplocations and ripplocation boundaries (RBs) in sandwich-structured graphite–silicon composites under lateral loading using the molecular dynamics method. Ripplocation was shown to be a fully reversible elastic deformation, and it was found that RBs of the same sign integrate when compressed to certain conditions. Further, the out-of-plane deformation of the graphene-forming curvature was described using differential geometry, and the mean curvature ranging from −0.83 to 0.83 Å−1 increases with an increase in graphene flexure.Furthermore, using the Helfrich Hamiltonian theory, we demonstrated the relationship between the bending energy and local curvature of graphene, revealing that its change trend is the same as that of the Gaussian curvature. Finally, the principal rigidities involved in the sinusoidal corrugated plate were solved according to the orthotropic corrugate plate approximations. There was good agreement between the theoretically calculated deflections and those obtained through molecular dynamics simulations when six layers of graphene and transverse load are 8.86 GPa. This study not only describes the complete ripplocation deformation process but also effectively combines theory and simulation to analyze the deformation mechanism of graphene from multiple perspectives.