Synthesis of filled skutterudite compounds:: BayFexCo4-xSb12

Ba-filled skutterudite compounds, BayFexCo4-xSb12, were synthesized by a two-step solid reaction method. A binary compound of Sb3Ba and a ternary compound of FexCo1-xSb2 were first synthesized at 900 and 973 K, respectively. The presynthesized Sb3Ba and FexCo1-xSb2 were then mixed with Sb and heated at 973 K in an Ar atmosphere. The resulting powder was of single phase with a composition of BayFexCo4-xSb12, having skutterudite structure with the Sb-dodecahedron voids fractionally filled by Ba. The lattice constant of BayFexCo4-xSb12 increased with Ba and Fe content. The maximum filling fraction of Ba (y(max)) in BayFexCo4-xSb12 was found to be greater than that of Ce or La in Ln(y)Fe(x)Co(4-x)Sb(12), especially in the lower Fe content region. The y(max) varied from 0.35 to near 1.0 when Fe content (x) changed from 0 to 4.