  We calculate the thermal conductivity of PbTe and PbS with seven different
types of nanoprecipitates using an ab-initio-based Boltzmann transport
approach. We find that precipitates with realistic size distributions can
reduce the thermal conductivity well below the predictions of theoretical
models assuming a single precipitate size.We explore the question of how to
tune this distribution to reduce the thermal conductivity even further. The
predicted minimum value is strongly correlated with the phonon spectrum of the
host material and with the mass density difference between the host and the
inclusions.
