Influence of Phase Composition on the Thermoelectric Properties of Nanostructured Skutterudite and Ceramic Composites

Nanostructuring of unfilled CoSb₃ Skutterudites has been successful in reducing the thermal conductivity of these materials [Toprak, et al., 2004]. First measurements on a mixture of the Skutterudite and an inert ceramic with particle sizes in the nanometer range have shown promising results for a further reduced thermal conductivity by decorating the grain boundaries of the thermoelectric material [Stiewe, et al., 2006]. A strong influence of additional phases like CoSb₂ and pure Sb in the samples has been encountered, too. Therefore in the present work a more detailed investigation of the effect of phase purity and grain size by an intentional variation of the phase composition is presented. The impact of a variation in the amount of the ceramics addition and of the phase composition on the thermoelectric properties (kappa, sigma, S) of pure and doped CoSb ₃, respectively, are studied and the results are discussed with respect to an enhancement of the thermoelectric figure of merit