Geometry and temperature dependent thermal conductivity of diamond nanowires: A non-equilibrium molecular dynamics study

Using non-equilibrium molecular dynamics methods, the analysis of geometry and temperature dependent thermal conductivities of diamond nanowires is carried out. It is found that at the same temperature conditions, thermal conductivities of diamond nanowires increase with increasing lengths, ranging from 20 to 350 nm and cross-sectional areas ranging from 2 to 30 nm2. At the same length, temperature and cross-sectional area conditions, thermal conductivities of 〈0 1 1〉 crystal orientation diamond nanowires are larger than those of other crystal orientation diamond nanowires. First, in the temperature range 0-1000 K, thermal conductivities of diamond nanowires increase with the increase in temperature, and then they decrease. The results of our calculation have also indicated that all thermal conductivities of the diamond nanowires analyzed here are smaller than those of the corresponding orientations in bulk diamond. Finally, a relationship between thermal conductivity and density of phonon state is discussed.