Thermal conductivity of core-shell nanocomposites for enhancing thermoelectric performance

The differential effective medium method (DEM) is presented from a physical viewpoint and employed to calculate the lattice thermal conductivity of nano-bulk composites comprising core-shell particles. Extended from the average-T-matrix single-particle approximation, DEM incorporates multiparticle effect essential for the study of core-shell nanocomposites (CSN). Interparticle boundary scattering in addition to intraparticle boundary scattering in CSN is found to add to the reduction of thermal conductivity of nanocomposites. Thus, CSN hold the promise of improving the thermoelectric dimensionless figure of merit ZT above that of monolithic nano-bulk phases. Si and SiGe based CSN serve as illustrative examples.