Prediction of the Thermal Conductivity of ZnO Nanostructures

Abstract

The kinetic theory of gas is used to predict the specific heat and thermal conductivity of ZnO nanostructures. In this model, phonons are considered as a gas whose basic properties are given by phonon dispersion curves. The model also requires knowledge of the boundary relaxation time parameter (F), the defect relaxation time parameter D, and the relaxation time parameters which take into account lattice anisotropy. These parameters can be determined independently from experimental measurements. Excellent agreements were found when comparing both the estimated specific heat and thermal conductivity to bulk sample measurement data. Comparison with previous results obtained with molecular dynamics (MD) simulations leads to the conclusion that for ultra narrow nanobelts, thermal conductivity depends on their length. Behavior of the thermal conductivity of nanofilms is also studied. The results are consistent with previous works on 1D and 2 D systems. Finally, the thermal conductivity of nanobelts is presented as are the influences of boundary and defect parameters.