Thermal conductivity reduction by acoustic Mie resonance in nanoparticles.

We evaluate the impact of acoustic Mie resonance in nanoparticles on the thermal conductivity of semiconductor and polymer composites. By appropriately choosing the bulk modulus and density, and selecting the size of the nanoparticle to align the Mie resonances with the dominant portion of the thermal conductivity spectrum, we show that large reductions in thermal conductivity are achievable with dilute concentrations of nanoparticles. In semiconductor alloys, where the spectral thermal conductivity is known, our model can explain the steep reductions in thermal conductivity observed previously. However, the results of our effort to evaluate acoustic Mie resonance in polymer composites are inconclusive due to uncertainties in the spectral thermal conductivity. Acoustic Mie resonances can be useful for maximizing ZT for thermoelectric applications, since a dilute loading of nanoparticles can reduce thermal conductivity with minimal impact on electrical conductivity.