EuTZn (T = Pd, Pt, Au) with TiNiSi-type structure-Magnetic properties and 151Eu Mossbauer spectroscopy

The europium compounds EuTZn (T Pd, Pt, Au) were synthesized from the elements in sealed tantalum tubes in an induction furnace. These intermetallics crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. The structures were investigated by X-ray diffraction on powder sand single crystals: a = 732.3(2), b = 448.5(2), c = 787.7(2) pm, R-1/wR(2) = 0.0400/0.0594, 565 F-2 values for EuPdZn, a = 727.8(3), b = 443.7(1), c = 781.7(3) pm, R-1/wR(2) = 0.0605/0.0866, 573 F-2 values for EuPtZn, and a = 747.4(2), b = 465.8(2), c = 789.1(4) pm, R-1/wR(2) = 0.0351/0.0590, 658 F-2 values for EuAuZn, with 20 variables per refinement. Together the T and zinc atoms build up three-dimensional [TZn] networks with short T-Zn distances. The EuTZn compounds show Curie-Weiss behavior in the temperature range from 75 to 300 K with mu(eff) = 7.97(1), 7.70(1), and 7.94(1) mu B/Eu atom and theta(P) = 18.6(1), 34.9(1), and 55.5(1) K for T = Pd, Pt, and Au, respectively, indicating divalent europium. Antiferromagntic ordering was detected at 15.1(3) K for EuPdZn and canted ferromagnetic ordering at 21.2(3) and 51.1(3) K for EuPtZn and EuAuZn. Eu-151 Mossbauer spectroscopic measurements confirm the divalent nature of the europium atoms by isomer shift values ranging from -8.22(8) (EuPtZn) to -9.23(2) mm/s (EuAuZn). At 4.2 K full magnetic hyperfine field splitting is observed in all three compounds due to magnetic ordering of the europium magnetic moments. (C) 2009 Elsevier Inc. All rights reserved.