Influence of Interface Arrangement on Phonon Heat Transfer in Nanocomposites

Abstract

The influence of interface arrangement in two- and three-dimensional silicon–germanium nanostructures on heat transfer is investigated by phonon Boltzmann transport equation model. For all nanocomposites studied here, the thermal conductivity decreases monotonically with increasing interface density and decreases monotonically with decreasing characteristic size. The interface density plays an important role to correlate the size effect of phonon transport. Another factor called structure efficiency, which taking into account both the structure dimensions and the interface arrangement, is also found to affect significantly the thermal conductivities of the nanocomposites. For the structure efficiency of a composite structure, it is found that the superlattice structure has the best structure efficiency in transverse transport and the compacted-wire structure has the best structure efficiency in longitudinal transport. High-dimensional (wire and particle) structures contain large interface density which is beneficial for reducing thermal conductivity. At the same characteristic size, the compacted-particle structure can yield the lowest thermal conductivity in transverse transport and the compacted-wire structure can yield the lowest thermal conductivity in longitudinal transport. The obtained results may provide essential information for the development of bulk-nanostructured thermoelectric devices.