Phononic thermal transport properties of C3N nanotubes

Reverse nonequilibrium molecular dynamics (RNEMD) is employed to study the phononic thermal transport properties of C₃N nanotubes. We study the effect of nanotube length and diameter on the thermal conductivity and investigate the phonon transport transition from ballistic to diffusive regime in C₃N nanotubes. It is found that the thermal conductivity of C₃N nanotubes is significantly lower than those of carbon nanotubes across the entire ballistic-diffusive range. In addition, significantly lower ballistic to diffusive transition length (72-80 nm) is observed in C₃N nanotubes compared to carbon nanotubes. The inspection of phonon dispersion curves shows that carbon nanotubes have stiffer acoustic modes than C₃N nanotubes which results in lower group velocities for C₃N nanotubes. Due to the presence of nitrogen atoms, the phonon mean free paths and relaxation times of C₃N nanotubes are shorter than those of the carbon nanotubes. The combined effect of lower group velocities and relaxation times leads to the lower thermal conductivity of C₃N nanotubes.