  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.
