Mechanical behaviors of T-carbon: A molecular dynamics study

T-carbon, a new carbon allotrope, was initially predicted to exist in a theoretical study [Phys. Rev. Lett. 106 (2011) 155703] and successfully fabricated in recent experiment [Nat. Commun. 8 (2017) 683]. This work investigates the mechanical behaviors and structural evolution of T-carbon nanowires under tensile loading by using molecular dynamics simulations. It is found that T-carbon nanowires exhibit mechanical anisotropy and excellent ductility. This is due to the fact that global graphitization (sp³-sp² transitions) of T-carbon nanowires can be induced by tensile loading, which has been rarely reported for other carbon materials. Occurrence of the global graphitization is due to the competition between the mechanical strengths of sp³ and sp² networks that eventually determines the graphitization dependence on temperature and lattice direction of T-carbon. A phase diagram of T-carbon nanowires is finally drawn to unveil their graphitization under tensile loading, thus interpreting their mechanical behaviors.