Thermoelectric property enhancement in Yb-doped n-type skutterudites YbxCo4Sb12

We present a study on the dimensionless thermoelectric figure-of-merit (ZT) of nanostructured YbxCo4Sb12 (x = 0.2, 0.35, 0.45. 0.5 and 0.6) made by hot pressing the nanopowder obtained from ball milling an ingot in comparison with that made directly from ball milling the elements. It was found that the electrical conductivity of the sample made from the ingot is higher and the thermal conductivity is lower compared to the sample made from directly ball milling the elements. It is believed that the higher electrical conductivity is due to the presence of fewer defects, while the lower thermal conductivity may be due to stronger phonon scattering from the different grain sizes. We have achieved a peak ZT of ∼1.4 at 550 °C in Yb0.35Co4Sb12.