Published online by Cambridge University Press: 01 February 2011
We report on the development of an efficient n-type skutterudite based on the double-filled structure of CoSb3. The chosen filler species Ba and Yb have a large phonon contrast and this combination is very effective in lowering the lattice thermal conductivity. The highest figure of merit in excess of 1.3 is obtained near 800K and the figure of merit greater than unity persists down to temperatures of about 550K. The compounds are synthesized with high purity Co (99.998%) and Sb (99.9999%). In order to reduce the cost of the materials, we have also prepared filled skutterudites of similar composition but using less pure Co (99.8%) and Sb (99.999%). The figure of merit of these lower purity compounds reaches ZT = 1 at 800K with the materials' cost dramatically reduced.