High pressure synthesis and thermoelectric properties of Ba-filled CoSb3 skutterudites

The filling behavior of barium into voids of CoSb3 under high pressure was investigated with the first principles calculations, revealing that the filling fraction limit can be further increased under high pressure. Inspired by the theoretical investigation result, we synthesized Bafilled CoSb3 with a high pressure synthesis method. The products show the skutterudite structure of Im (3) over bar symmetry. The maximal filling fraction of Ba in CoSb3 is increased to 0.51. The power factor is significantly enhanced meanwhile the lattice thermal conductivity is dramatically suppressed after Ba filling, and ZT of Ba0.51Co4Sb12 reaches a value of ca. 1.0 at 883 K. Compared with the traditional solid state reaction method for fabricating elemental- filled skutterudites, the high pressure synthesis method shows the advantages of fast process, broadening fillable elements, and increasing the filling fraction.