The cadmium-rich intermetallic phases RE Pd ₂ Cd ₂₀ ( RE = Ca, Y, La, Ce, Nd, Eu–Lu)

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:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mover accent="true"> <m:mn>3</m:mn> <m:mo>̅</m:mo> </m:mover> </m:mrow> </m:math> ̅3 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 .