MgCuAl _2-type intermetallics REPdCd _2(RE = Ce, Pr, Nd, Sm)

摘要

The cadmium-rich intermetallic compounds REPdCd _2 (RE = Ce, Pr, Nd, Sm) were obtained by high-frequency melting of the elements in sealed niobium ampoules and subsequent annealing in muffle furnaces. The REPdCd _2 phases crystallize with the orthorhombic MgCuAl _2-type structure, space group Cmcm. The structure of NdPdCd _2 was refined from single-crystal X-ray diffractometer data: a = 421.9(3), b= 995.4(7), c= 834.5(6) pm, wR = 0.0286, 451 structure factors, 16 variables. The palladium and cadmium atoms build up a three-dimensional [PdCd _2] network (281-283 pm Pd-Cd; 298-335 pm Cd-Cd) in which the neodymium atoms fill cavities. They are connected to the [PdCd _2] network via shorter Nd-Pd bonds of 286 pm.