Stability of single-wall silicon carbide nanotubes – molecular dynamics simulations

Abstract

One-dimensional silicon carbide (SiC) nanotubes and nanowires are both realizable and may co-exist. The stability of SiC nanotubes relative to nanowires and against heating is still unknown. Using classical molecular dynamics simulations, the authors investigate the stabilities of SiC nanotubes; as a first step, the study focuses on single-wall nanotubes (SWNTs). The results show that SiC nanotubes are more stable than nanowires below a critical diameter of about 1.6nm, while SiC nanowires are more stable than nanotubes beyond that. As temperature increases, melting takes place at about 1620K in SiC nanotubes by heterogeneous nucleation from the non-hexagonal defects due to reconstruction at a free end, and at about 1820K in nanotubes without free ends by homogeneous nucleation within the wall from thermally activated 5-7-7-5 defects. In both cases formation of Si–Si and C–C bonds proceeds melting.