Synthesis and thermoelectric properties of KyCo4Sb12

Abstract

Polycrystalline K-filled $\mathrm{Co}{\mathrm{Sb}}_3$ are synthesized successfully. The uplimit for K filling is at least 0.45, being higher than those of either alkaline-earth (AE) or rare-earth (RE) metals but being in consistent with our earlier theoretical prediction. The measured transport properties $(300–800\mathrm{K})$ show that K filling does not lower thermal conductivity much in comparison with AE or RE filling due to the relatively low mass of K atom. However, it improves electrical conductivity, retains large Seebeck coefficient, and leads to a reasonably good thermoelectric performance for the filled skutterudites. The maximum figure of merit $ZT$ reaches 1 at $800\mathrm{K}$ for ${\mathrm{K}}_{0.38}{\mathrm{Co}}_4{\mathrm{Sb}}_{12}$ .