Thermal transport through Zn3P2 nanowire-BN microparticle/nanoparticle composites and hybrids

Abstract

Composites and hybrids of BN and Zn3P2 nanowires were made by consolidating respectively BN micropowder-Zn3P2 nanowire mixtures and non-conformally BN decorated Zn3P2 nanowires. The intent here is to study whether mere solid-state mixing of a thermal conductor and a thermal insulator leads to the engineering of the thermal conductivities of the resulting composites and hybrids. The results demonstrated that contrary to intuition, mere mixing of two materials, a thermal conductor (BN) and a thermal insulator (Zn3P2 nanowires), does not result in composites and hybrids that have thermal conductivities higher than those of the thermal insulator and lower than those of the thermal conductor. This contrary result is especially true in instances where microparticles or nanoparticles of a high thermal conductivity material are introduced into a matrix of the thermal insulator for achieving spatially uniform composites/hybrids and engineering the resulting materials’ thermal conductivities. Here, both the size of the filler material and the type of interfaces formed between the matrix and the filler material play a major role in determining the ultimate thermal conductivities of the composites/hybrids. Imperfect interface formed between materials that have high lattice mismatches lead to lowering of the thermal conductivities of the composites/hybrids.