Effective medium approach to thermal conductivity: applying to core-shell nanocomposites

The effective medium method is employed to study thermal conductivity of nanostructured phases consisting of embedded particles in a host. Beyond the average T-matrix single-particle approximation, the effect of higher-order inter-particle terms on heat transport is estimated to be small, which can be validated by using a re-formulated differential effective medium (DEM) approach. However, the effect of higher-order terms on heat transport is found to become significant when phonon scattering from embedded particles is considered. Applying the DEM approach to two-phase nanocomposites, particularly core-shell materials that mimic a three-dimensional superlattice, it results in a large reduction of thermal conductivity, and potentially high ZT.