Elastic and Melting Properties of Crystalline SiC Nanotubes

Abstract

In this paper, the elastic and melting properties of single-crystal SiC nanotubes were investigated with the help of molecular dynamics simulation based on the Tersoff bond-order potential. It was found that the Young’s moduli and melting temperatures were tightly dependent on the wall thickness of the SiC nanotube, and the radius of the nanotube slightly influences these properties. Our calculations predicted that the Young’s moduli decrease monotonously toward the values of bulk SiC crystals as the wall thicknesses increase. For the SiC nanotubes with the same wall thicknesses, the calculated Young’s moduli are almost identical no matter how large the difference of the radius between them is. The reason is that the ratios of volume to surface of SiC nanotubes increase as their wall thicknesses increase, whereas the ratios remain constant when the wall thicknesses are invariable. On the contrary, the melting temperatures (starting melting temperature T1 and entirely molten temperature T2) of SiC nanotubes exhibit an increasing behavior as the wall thicknesses increase. This is because the single-crystal SiC nanotubes melt from the outer and inner surface layers toward the center layers. Consequently, the thin nanotubes with fewer body atomic layers possess lower melting temperature and the thick nanotubes have higher melting temperature. Both Young’s modulus and melting temperatures do not change significantly when the wall thickness of a SiC nanotube is larger than 2 nm, which indicates that the thick single-crystal SiC nanotubes inherit the superior mechanical and thermal properties of bulk SiC crystals. According to our calculations, single-crystal SiC nanotubes are perhaps the best candidate of one-dimensional semiconducting materials for nanoscale electronic devices under harsh environments.