Existence, structure and valence properties of the skutterudites CeyFe4-xCoxSb12

We report on sample preparation, annealing effects, electron microprobe analysis in the series CeyFe4-xCoxSb12 which shows that a phase separation occurs for substituted samples (0<x<4) annealed at 650 and 550degreesC. Single phase samples are obtained for either CeyFe4Sb12 or CeyCo4Sb12 samples annealed at 650degreesC and for all compositions when annealed at 700degreesC. The valence state of Ce in homogeneous samples has been studied using X-ray absorption spectroscopy (XAS). Ce ions are trivalent throughout the series and the XAS spectra does not show effect of the crystal field on the 5d-final state. (C) 2002 Elsevier Science B.V. All rights reserved.