(Ca0.95Cd0.10)Pd2Cd3, SrPd2Cd3 and (Eu0.95Cd0.10) Pd2Cd3 with YNi2Al3 type structure - crystal chemistry and magnetic hyperfine interactions

The intermetallic compounds (Ca0.95Cd0.10)Pd2Cd3, SrPd2Cd3 and (Eu0.95Cd0.10)Pd2Cd3 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: YNi2Al3 type, P6/mmm, a = 984.61(5), c = 455.33(3) pm, wR2 = 0.0216, 376 F-2 values, 21 variables for (Ca0.95Cd0.10)Pd2Cd3, a = 998.55(8), c = 453.65(3) pm, wR2 = 0.0296, 341 F-2 values, 17 variables for SrPd2Cd3 and a = 992.57(4), c = 457.34(2) pm, wR2 = 0.0300, 384 F-2 values, 21 variables for (Eu0.95Cd0.10)Pd2Cd3. The striking crystal chemical motif in the three structures is a planar [PdCd2] 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 (Eu0.95Cd0.10)Pd2Cd3. Temperature dependent magnetic susceptibility measurements show Curie-Weiss behaviour (7.63(1) mu(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 Eu-151 Mossbauer spectroscpy.