LAUSR

Abstract Low-cost Ce has been proved to be an effective auxiliary filler for performance tuning in CoSb3-based skutterudite, one of the most promising thermoelectric materials at medium temperature. However, the low solubility of Ce in CoSb3 makes its overall thermoelectric properties so far inferior to that with expensive and scarce Yb filler. Herein, using non-equilibrium processing, we successfully synthesized a series of double-filled skutterudites with Ce as the dominating filling element and Y as the auxiliary filler. Our investigation shows that Y filling not only optimizes the carrier concentration and thus enhances the overall power factor but also introduces additional phonon scattering and hence leads to significantly suppressed lattice thermal conductivity. The concurrently optimized electrical and thermal properties realize the maximum ZT of ~1.37 at 873 K in the Y0.05Ce0.15Co4Sb12 sample, prevailing over the other involved Ce single- or even double-filled skutterudites, which will potentially facilitate a widespread application of filled skutterudites.