The cadmium-rich intermetallic phases RE Pd ₂ Cd ₂₀ ( RE

Abstract

The series of cadmium-rich rare earth intermetallics RE Pd ₂ Cd ₂₀ ( RE = Ca, Y, La, Ce, Nd, Eu–Lu) was synthesized by high-temperature reactions of the elements in sealed tantalum ampoules. Single crystals were grown by slow cooling of the reaction products. All RE Pd ₂ Cd ₂₀ phases were characterized through their Guinier powder patterns. The structure of GdPd ₂ Cd ₂₀ was refined from single crystal X-ray diffractometer data: CeCr ₂ Al ₂₀ type, Fd

m , a = 1,560.28(2) pm, w R = 0.0521, 356 F ² values and 17 variables. The RE Pd ₂ substructure has the topology of the cubic Laves phase MgCu ₂ . The rare earth and palladium atoms have 16 and 12 cadmium neighbors forming Frank-Kasper type polyhedra, respectively. Temperature dependent magnetic susceptibility measurements show Pauli paramagnetism for YPd ₂ Cd ₂₀ and Curie-Weiss paramagnetism for the remaining rare earth compounds. EuPd ₂ Cd ₂₀ , GdPd ₂ Cd ₂₀ , TbPd ₂ Cd ₂₀ and DyPd ₂ Cd ₂₀ show antiferromagnetic ordering below the Néel temperatures of 8.9(1) ( RE = Eu), 15.6(1) ( RE = Gd), 9.5(3) K ( RE = Tb) and 7.4(1) K ( RE = Dy), respectively. TbPd ₂ Cd ₂₀ and DyPd ₂ Cd ₂₀ exhibit metamagnetic transitions at critical fields of 12(1) and 6.9(2) kOe, respectively. EuPd ₂ Cd ₂₀ has a stable divalent ground state. The ¹⁵¹ Eu Mössbauer spectrum at 78 K shows an isomer shift of −10.58(2) mm s ⁻¹ .