Enhanced thermoelectric performance in CdO by nano-SiO₂ inclusions

We report enhanced thermoelectric (TE) performance in CdO by using thermally insulating nano-particles to mimic nano pores in the composite. Through simply mechanical alloying, we fabricated CdO-SiO2 composites with varying nano-SiO2 concentration from 0.1 to 3 at%. Due to the very low thermal conductivity of nano-SiO2 distributed in the CdO matrix, the thermal conductivity of the composite was substantially reduced by about 80%, which lead to the dimensionless figure of merit (ZT) value increment about 28% (from 0.32 to 0.41) at 1000 K. TEM shows the nano inclusions formed within the CdO matrix and grain boundaries as well, which is thought to contribute to the reduction of thermal conductivity of the composite by additional scattering mechanism for the mid- to long-wavelength phonons. This facile and low-cost approach might be widely adopted and synergized to other TE materials systems to further improve their performance.