Thermoelectric properties of uranium filled skutterudites Uy(FexCo4−x)Sb12

The filled skutterudites of the form UyFexCo4−xSb12 were fabricated and the thermoelectric properties for certain samples studied. For samples containing 100% cobalt, uranium could not be incorporated, or 'filled', into the voids in the skutterudite structure. With substitution of iron for cobalt the void occupancy by uranium increased. Uranium filled samples indicated relatively large Seebeck coefficient and p-type behavior. The thermal conductivity, especially below 500 K, of UyFexCo4−xSb12 was strongly depressed by uranium filling and iron substitution. The dimensionless thermoelectric figure of merits, ZT, were improved by uranium filling and showed a maximum value ZT = 0.55 at 800 K for U0.2FeCo3Sb12 of nominal composition.