Thermoelectric properties and cost optimization of spark plasma sintered n-type Si0.9Ge0.1 - Mg2Si nanocomposites

Abstract

We report on thermoelectric properties of low Ge content n-type Si0.9Ge0.1–Mg2Si nanocomposite. Introduction of the Mg2Si phase into a SiGe matrix resulted in a dramatic drop of the lattice thermal conductivity beyond the previously reported lowest limit for SiGe alloys due to intensification of phonon scattering on SiGe–Mg2Si grain boundaries. For a sample doped with 1 at.% of Mg2Si, the peak value of thermoelectric figure of merit ZT reached ~ 0.8 at 800 °C. Sintered nanocomposites still exhibit high thermoelectric performance while being almost two times cheaper than Si0.8Ge0.2.