Junction configuration-induced mechanisms govern elastic and inelastic deformations in hybrid carbon nanomaterials
R Shahsavari and N Sakhavand, CARBON, 95, 699-709 (2015).
Although various hybrid 3D carbon-based architectures are reported by covalently connecting low dimensional carbon allotropes, the effect of junction configuration on deformation and mechanical properties of the hybrid carbon architectures remain elusive. Here, we focus on Pillared Graphene Nanostructure (PGN) as a model system with symmetric and asymmetric junctions to explore its diverse elastic and inelastic properties via first-principles and molecular dynamics simulations. By introducing heptagonal and octagonal rings in the junctions, our findings demonstrate that in contrast to the stacked of graphene sheets, which exhibit weak out-of-plane properties, both junction types impart a cooperative two-regime deformation mechanism that provides a number of superior characteristics in PGN, including 3D balance of strength and toughness as well as an outstanding similar to 42% out-of-plane ductility preceding the failure. Furthermore, asymmetric junctions impose wrinkles in the PGN sheets, which add extra in-plane flexibility and shear compliance, result in a nearly zero/negative in-plane Poisson's ratio in PGN, and cause the octagonal rings to act as hotspot for initiating of fracture. Our results provide the first atomistic "lens" on fundamental understanding of junction-induced deformation mechanisms in pillared graphene and can potentially provide a new phase space to better control and design mechano-mutable hybrid carbon nanostructures. (C) 2015 Elsevier Ltd. All rights reserved.
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