Defective carbon nanotube for use as a thermal rectifier

We investigated the thermal properties of a single-walled carbon nanotube with vacancy defects to determine its applicability to solid-state thermal rectification. Nonequilibrium molecular dynamics simulation of a nanotube with randomly located defects only along half the length revealed asymmetric heat conduction at room temperature. The direction of rectification is in good agreement with that obtained in a past experiment in which C9H16Pt was asymmetrically deposited on a nanotube, as far as the local deposition is supposed to cause defects in the nanotube lattice. The mechanism underlying the current thermal rectification effect is discussed considering the temperature dependence of the local thermal conductivity and the phonon filtering effect. The calculated phonon density of states shows larger overlapping when heat flows from the defective part to the pristine part and intermediate-frequency phonons are mainly responsible for rectification.