Thermal conductivity in fluorine-doped single-walled carbon nanotubes

Abstract

Herein, we report on the axial thermal conductivity (κzz) of a non-degenerate fluorine-doped single-walled carbon nanotubes (FSWCNTs) under single and dual relaxation models. We derived the expressions for the carrier thermal current density (Q→), carrier thermal conductivity (κe), and simulated the lattice thermal conductivity (κℓ) using Callaway’s dual relaxation time model as a function of temperature field. The thermal conductivity was observed to be strongly nonlinear and purely phonon dominated. Moreover, the study investigated the effect of impurity concentration (no), and overlapping integrals for jumps (Δs and Δz) on κzz. Our results showed that, the axial thermal conductivity (κzz) and the operational temperature range of FSWCNTs could be tuned using doping (impurity) and overlapping integrals. The ac component of the electric field was observed to strongly energise the FSWCNT carrier gas and thus, caused the carrier contribution to the axial thermal conductivity to be non-significant but solely phonon dominated. Interestingly, using the Callaway’s model, κℓ was evaluated to be 107.201 W/mK, at 300 K. Thus, base on the FSWCNT’s low κℓ and its possibility of tuning to operate at high temperatures makes it a good choice for thermoelectric applications including chip level cooling, heat sinks and power generation.