Heat conduction of double-walled carbon nanotubes (DWCNTs) with intertube additional carbon atoms was investigated using molecular dynamics (MD) simulation method. The interaction between carbon atoms was modeled using the Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) Potential. The related phonon density of states (DOS) was analyzed to help explain the heat conduction mechanism. It is indicated that intertube additional atoms of DWCNT will weaken the heat conduction along the axis. The addition of intertube atoms, which are covalently bonded to the inner and outer tubes, leads to localized structural deformation, which acting as a phonon barrier for ballistic heat transport. In addition, the intertube atoms become the new centers of phonon scattering and reduce VDOS. The deformation is the primary reason for the reduction of thermal conductivity. With the increasing number of additional atoms, the thermal conductivity of DWCNTs with atoms added at the same cross section drops sharply than that added along the tube axis, because the former addition causes more serious local deformation. Under the situation of addition at the cross section, if the number of intertube atoms is beyond a critical value, the distribution of these atoms seems to have little influences on the heat conduction in the tube.
Extremely high thermal conductivity anisotropy of double-walled carbon nanotubes