Synthesis and Thermoelectric Properties of the Double-Filled Skutterudite Yb0.2In y Co4Sb12

Filled skutterudites have long been singled out as one of the prime examples of phonon glass electron crystal materials. Recently the double-filling approach in these materials has been attracting increased attention. In this study, Yb0.2In (y) Co4Sb12 (y = 0.0 to 0.2) samples have been prepared by a simple melting method and their thermoelectric properties have been investigated. The power factor is increased dramatically when increasing the In content, while the lattice thermal conductivity is lowered considerably, leading to a large increase of the ZT value. A state-of-the-art ZT value of 1.0 is attained in Yb0.2In0.2Co4Sb12 at 750 K.