Crystal structure and valence state of cerium in CePd3−xPtx alloys

Cerium is in a mixed valent state in CePd₃ (AuCu₃ type structure) while it is in a trivalent state in CePt₃ (defect C15 Laves type structure). CePd_3?xPt_x alloys have been prepared and are found to have AuCu₃ type structure for 0 ? x ? 1 and defect Laves type structure for 1.75 < x ? 3.0. From susceptibility measurements on these alloys in the temperature range 77–400 K, it is inferred that cerium is in a mixed valent state in all the AuCu₃ type alloys, but in a trivalent state in all the Laves phase type alloys in CePd_3?xPt_x series.