(Ca_0.95Cd_0.10)Pd₂Cd₃, SrPd₂Cd₃ and (Eu_0.95Cd_0.10)Pd₂Cd₃ with YNi₂Al₃ type structure – crystal chemistry and magnetic hyperfine interactions

Abstract The intermetallic compounds (Ca 0.95 Cd 0.10 )Pd 2 Cd 3 , SrPd 2 Cd 3 and (Eu 0.95 Cd 0.10 )Pd 2 Cd 3 were synthesized from the elements in sealed niobium ampoules in an induction furnace. The polycrystalline samples were characterized through their Guinier powder patterns. The structures were refined from single crystal X-ray diffractometer data: YNi 2 Al 3 type, P 6/ mmm , a = 984.61(5), c = 455.33(3) pm, w R 2 = 0.0216, 376 F 2 values, 21 variables for (Ca 0.95 Cd 0.10 )Pd 2 Cd 3 , a = 998.55(8), c = 453.65(3) pm, w R 2 = 0.0296, 341 F 2 values, 17 variables for SrPd 2 Cd 3 and a = 992.57(4), c = 457.34(2) pm, w R 2 = 0.0300, 384 F 2 values, 21 variables for (Eu 0.95 Cd 0.10 )Pd 2 Cd 3 . The striking crystal chemical motif in the three structures is a planar [PdCd 2 ] Kagome-type layer. The two crystallographically independent Ca (Sr, Eu) atoms have a coordination number of 18 by 6 Pd and 12 Cd atoms. The calcium and europium compound show a small degree of Ca (Eu) substitution by Cd 2 dumb-bells with 281 pm Cd–Cd in (Eu 0.95 Cd 0.10 )Pd 2 Cd 3 . Temperature dependent magnetic susceptibility measurements show Curie–Weiss behaviour (7.63(1) µ B /Eu atom) for the europium compound and the onset of ferromagnetic ordering at T C = 14.9(2) K. The divalent character of europium is corroborated by 151 Eu Mössbauer spectroscpy.