Influence of ZnO nano-inclusions on the transport properties of the CoSb3 skutterudite

Addition of nanoparticles into bulk materials is one of the strategies designed to synthesize thermoelectric materials with superior efficiency. The presence of nanoparticles is expected to act as a barrier of the heat transport due to an increased amount of nanoscopic interfaces and to enhance the electronic properties via quantum confinement effects. Here, this approach was applied to the skutterudite CoSb3 matrix in which different amounts of ZnO (2–12 wt.%) nanoparticles were introduced. The samples were densified by spark plasma sintering and characterized by X-ray diffraction and scanning electron microscopy. The thermoelectric properties were investigated in a broad temperature range (2–800 K) to better assess the influence of the ZnO nanoparticles. The nanostructured materials showed a significant enhancement in the thermopower values combined with a slight decrease in the thermal conductivity. A small amount of ZnO nanoparticles (2 wt.%) has a beneficial influence on the dimensionless thermoelectric figure of merit ZT suggesting that introducing stable oxide nanoparticles may be an interesting way to improve the thermoelectric properties of skutterudite compounds.

► Synthesis of ZnO/CoSb3 composites.
► Thorough analysis of the transport properties measured in a wide temperature range.
► Beneficial influence of minute amounts of ZnO on the thermoelectric figure of merit of CoSb3.