Synthesis and thermoelectric properties of "nano-engineered" CoSb3 skutterudite materials

Because of their good electrical transport properties, skutterudites have been widely studied as potential next-generation thermoelectric (TE) materials. One of the main obstacles to further improving their thermoelectric performance has been reducing their relatively high thermal conductivity. To some extent, this hindrance has been partially resolved by filling the voids found in the skutterudite structure with so-called "rattling" atoms. It has been predicted that reducing the dimensionality in a TE material would have a positive effect in enhancing its thermoelectric properties, for example increasing the thermopower and reducing the thermal conductivity. Introducing nanoparticles into the skutterudite materials could therefore have favorable effects on their electrical properties and should also reduce lattice thermal conductivity by introducing extra scattering centers throughout the sample. Nanoparticles may also be used in conjunction with void filling for further reduction of the thermal conductivity of skutterudites. Cobalt triantimonide (CoSb3) samples with different amounts of embedded nanoparticles have been grown, and the electrical and thermal transport properties for these composites have been measured from 10 K to 650 K. The synthetic techniques and electrical and thermal transport data are discussed in this paper.