Partial filling of skutterudites: Optimization for thermoelectric applications

Over the last ten years there has been substantial experimental and theoretical effort in understanding the transport properties of filled skutterudite compounds to optimize their thermoelectric properties. One such approach involves partially filling the voids in attempting to optimize the electrical properties while minimizing the thermal conductivity. We illustrate the importance of this approach by plotting and comparing the figure of merit of CoSb₃ over a large range of carrier concentrations and thermal conductivity values. The thermal conductivity of partially filled skutterudites A_xCo₄Sb₁₂, where A = La, Eu, and Yb, is analyzed using the Debye model to correlate the data with the type of filler atom in evaluating the role of the filler in affecting the thermal conductivity. Partial void filling has resulted in relatively high thermoelectric figures of merit at moderately high temperatures.