Thermal conductance across grain boundaries in diamond from molecular dynamics simulation

We determine the dependence of the interfacial conductance on twist angle for (001) symmetric twist grain boundaries (GBs) in diamond. We find that the conductances are extremely large, ranging from 7.7 to 17.6 GW/m(2) K. Nevertheless, when normalized to the single-crystal conductivity, the resulting Kapitza lengths are actually longer in diamond than in Si, indicating that the diamond GBs are relatively worse conductors of heat. This result is consistent with the poorer bonding across the diamond grain boundaries. We find that the interfacial conductance and Kapitza length can be well fitted by an extended Read-Shockley model