Thermal conductivity of ``nanoparticle in alloy'' materials from a first principles approach*

It has been demonstrated that nanoparticles embedded in alloys can produce large reductions in lattice thermal conductivity with corresponding increases in the thermoelectric figure of merit [1,2]. Here we present an\textit{ ab initio} approach to calculate the lattice thermal conductivity of an SiGe alloy host containing embedded nanoparticles. This approach is based on density functional perturbation theory and employs a virtual crystal approximation for the alloy and a relaxation time approximation for anharmonic, alloy disorder, and nanoparticle scattering. We apply the method to nanoparticles with a range of different chemical compositions, concentrations and sizes embedded in the SiGe alloy. We compare our first principles based results to those from previous calculations [2] based on the debye approximation. \\[4pt] [1] W. Kim, J. Zide, A. Gossard, D. Klenov, S. Stemmer, A. Shakouri, and A. Majumdar, Phys. Rev. Lett. 96, 045901 (2006). \\[0pt] [2] N. Mingo, D. Hauser, N. P. Kobayashi, M. Plissonnier and A. Shakouri, Nano Letters 9, 711 (2009); S. Wang and N. Mingo, Appl. Phys. Lett. 94, 203109 (2009).