Microstructure and Thermoelectric Properties of Yb-Filled Skutterudites Prepared by Rapid Solidification

Single-phase nanostructured bulk Yb0.2Co4Sb12 skutterudites have been prepared by combining a melt spinning technique with spark plasma sintering. The effects of a pre-annealing process on the microstructure and phase composition of ribbon samples and bulk materials are investigated. After the pre-annealing process, average grain size increases from 200 nm to 300 nm for ribbon samples and from 250 nm to 350 nm for bulk materials, and nearly single-phase skutterudites have formed. Because of the nanostructure, the thermal conductivity of bulk skutterudites notably decreases 25% at 800 K. As␣a result, the ZT values are improved compared with starting material prepared by the traditional method.