The Heat Pulse Porpagations in Multiwall Carbon Nanotubes

The microscopic mechanism of heat transport in armchair and zigzag double wall carbon nanotube (DWCNT) was studied by using Molecular Dynamics (MD) simulations. In order to generate heat waves in different phonon modes, strong heat pulse was applied to DWCNT. It was observed that leading heat wave packets in both DWCNTs and those in corresponding single wall carbon nanotubes (SWCNTs) move at the speed of longitudinal acoustic (LA) phonon modes. The kinetic temperatures of leading heat wave packets in inner and outer shell of DWCNT were greater than those of corresponding SWCNT. Within the leading heat wave packets, inner shell was longitudinally compressed while outer shell was expanded. However, it was observed the smaller longitudinal compression or expansion in SWCNT. The compression and expansion mechanism in both DWCNTs was found to depend on chirality. The local deformation of atomic structure in DWCNT is believed to increase the potential energy at corresponding regions and it is responsible for strong leading heat wave packets in each shell.