Synthesis of filled skutterudite compounds with varied degree of filling

Filled skutterudite antimonides are an example of electron crystal and phonon-glass materials as originally proposed by Slack (1994). A properly optimized compound should exhibit high electrical conductivity and Seebeck coefficients in combination with a very low thermal conductivity, thus resulting in a high value for ZT. In skutterudites, the low thermal conductivity results from the incoherent rattling of the loosely bound ternary atom in the oversize cage-like frame structure. Filled CoSb/sub 3/ compounds with fillings higher than 25% are very difficult if not impossible to synthesize by standard solid state synthetic methods. By using a multilayer technique and depositing Angstrom-thick layers of the individual elemental reactants that interdiffuse upon annealing and can form skutterudite compounds upon annealing. In this study, close to completely filled CeCo/sub 4/Sb/sub 12/ and LaCo/sub 4/Sb/sub 12/ samples have been prepared and the synthesis of a Ce/sub x/Co/sub 4/Sb/sub 12/ and a La/sub x/Co/sub 4/Sb/sub 12/ series are presented.