Thermal conductivity of amorphous silica using non-equilibrium molecular dynamics simulations

In several recent applications, including those aimed at developing novel thermal interface materials, nano-particulate systems have been proposed to improve the effective behavior of the system. While nano-particles by themselves may have low conductivities, their use along with larger particles is believed to enhance the percolation threshold leading to better materials overall. One crucial challenge in using nano-particulate systems is the lack of knowledge regarding their thermal conductivity. A novel non-equilibrium molecular dynamics approach is used in this paper to determine the thermal conductivity of clusters of atoms without periodic boundary conditions. This method is first tested on bulk amorphous silica and conductivity values are compared to those reported in the literature. The method is then modified in order to study silica clusters. This modified approach is an approximation to the actual physical heat-transfer process in a cluster. Three different system sizes consisting 300, 600 and 900 atom clusters are considered and the values of conductivity for each are reported. The conductivity values obtained range from 1.49 W/mK to 1.94 W/mK. No significant effect of the cluster size on the thermal conductivity was found.