Crossover from ballistic to diffusive thermal conductance in helically coiled carbon nanotubes

Abstract

Thermal conductance in helically coiled carbon nanotubes (HCCNTs) is calculated out of phonon dispersion relations: anharmonicity is included through Brenner interatomic potential and scattering rates of the three-phonon Umklapp processes are calculated exactly, for all allowed transport channels. Highlighted are the universal features of the quantized thermal conductance and crossover from the ballistic to the diffusive transport regime is studied in detail. Correlation between the geometrical parameters of HCCNTs and thermal conductance is investigated. Finally, the specific heat is calculated and compared to that of the other carbon materials.