Thermal Conductivity of Polycrystalline Diamond Using Molecular Dynamics

Because of its high thermal conductivity (~ 2,000 W/m K), diamond is a promising candidate for thermal management applications. In this study, we examine thermal conductivity of polycrystalline diamond using the molecular dynamics method. The interactions between carbon atoms are modeled by the AIREBO potential and the thermal conductivity is computed using both Green-Kubo and the direct methods. Temperature is varied from 300 and 1000 K and the multigrain structure is constructed using Voronoi tessellation. To see the effect of grain size, 1, 2, 5, and 10 grain configurations are chosen. We first compute the thermal conductivity of single crystal diamond as a reference system and then polycrystalline diamond is also tested. The simulation results show that the thermal conductivity drops from 834 W/m K for single crystal to 14.15 W/m K for one grain model. This sharp drop in thermal conductivity is attributed to the grain boundary thermal resistance related to complex lattice dynamics associated with grain boundaries.