  A new model for predicting the effective thermal conductivity of
polycrystalline materials is presented. In contrast to existing models, our new
model is based on the thin-interface description of grain boundaries (GBs) and
treats GBs as an autonomous phase with its own thermal conductivity. This
treatment allows the model to account for the effects of segregation/doping,
interface structural/phase transition, and interface decohesion on the
effective thermal conductivity. finite-element simulations were performed to
validate the new model. The simulations proved its higher accuracy compared to
existing models.
