Thermal conductivity of carbon nanotube peapods

Thermal conductivity of a $(10,10)$ carbon nanotube filled with ${\mathrm{C}}_{60}$ fullerenes (or a peapod) is computed using direct molecular-dynamics simulations with the Tersoff-Brenner potential for $\mathrm{C}\text{−}\mathrm{C}$ bonding interactions and the van der Waals potential for nonbonding interactions. The temperature-dependent thermal conductivity of the peapod, while showing qualitatively similar behavior to that of an unfilled carbon nanotube, is found to be higher than the nanotube at all temperatures. This is in agreement with recent experimental observations. The increase in thermal conductivity in the peapod is explained through (a) an energy transfer between fullerenes and nanotube due to low-frequency radial vibration coupling between fullerenes and nanotube, and (b) energy transfer along the peapod axis due to fullerene-fullerene collisions.

Figure 1

Total-energy optimized geometries of a bare $(10,10)$ nanotube and the same $(10,10)$ nanotube encapsulating a ${\mathrm{C}}_{60}$ chain.

Figure 2

Stationary-state temperature profile at $300\mathrm{K}$ along the $(10,10)$ peapod.

Figure 3

Temperature dependence of peapod thermal conductivity as compared with that of an empty CNT.

Figure 4

Distribution of heat between the CNT and the ${\mathrm{C}}_{60}$ chain at a temperature of $300\mathrm{K}$.

Figure 5

The computed total, radial, azimuthal, and axial spectra of the peapod at $300\mathrm{K}$ in comparison with the contributions from the ${\mathrm{C}}_{60}$ fullerenes and the carbon nanotube part in the frequency range of $1–55\mathrm{THz}$. The solid line corresponds to the spectra for the peapod, with CNT contributions shown as dotted lines and the fullerene contributions shown as dashed lines.