Effect of intrinsic defects on the thermal conductivity of PbTe from classical molecular dynamics simulations

Lead telluride (PbTe) is a reference high-performance thermoelectric which can exhibit low values of thermal conductivity in the presence of intrinsic defects. Here, we present an optimized Buckingham potential that provides an improved description of this material, especially for the lattice thermal conductivity. The latter is computed using two different methods: Green-Kubo method and direct thermostatting. Comparison with other classical force fields proposed in the literature shows substantial improvement.
Using this potential we studied how intrinsic defects influence the thermal conductivity, paying special attention to vacancies, interstitials and grain boundaries. Our results show that intrinsic point defects and grain boundaries can reduce the lattice conductivity of PbTe by a factor of 4, and converge towards the value of pristine PbTe under typical experimental concentrations of defects in samples. We also determine the thermal resistance of grain boundaries.