The thermal conductivity and thermal rectification of carbon nanotubes studied using reverse non-equilibrium molecular dynamics simulations

The thermal conductivity of single-walled and multi-walled carbon nanotubes has been investigated as a function of the tube length L, temperature and chiral index using non-equilibrium molecular dynamics simulations. In the ballistic-diffusive regime the thermal conductivity follows alpha L-alpha law. The exponent a is insensitive to the diameter of the carbon nanotube; alpha approximate to 0.77 has been derived for short carbon nanotubes at room temperature. The temperature dependence of the thermal conductivity shows a peak before falling at higher temperatures (> 500 K). The phenomenon of thermal rectification in nanotubes has been investigated by gradually changing the atomic mass in the tube-axial direction as well as by loading extra masses on the terminal sites of the tube. A higher thermal conductivity occurs when heat flows from the low-mass to the high-mass region.