LaPdIn2 with MgCuAl2 and REPdIn2 (RE = Y, Pr, Nd, Sm, Gd-Tm, Lu) with HfNiGa2-Type Structure: Synthesis, Structure, and Physical Properties

New indides REPdIn2 (RE = Y, La, Pr, Nd, Sm, Gd-Tm, Lu) have been synthesized from the elements by arc-melting. The indides with Y, Pr, Nd, Sm, Gd-Tm, and Lu as the rare earth metal component have been obtained in pure form by annealing the arc-melted samples in tantalum containers. Single crystals of LaPdIn2 were obtained by recrystallization of a LaPdIn2 sample from an indium flux. LaPdIn2 crystallizes with the MgCuAl2 structure: Cmcm, a = 463.79(7) pm, b = 1074.3(2) pm, c = 746.4(2) pm, wR2 = 0.1149, 380 F2 values, and 16 variables. The structure may be described as a palladiumfilled LaIn2 substructure. The latter is a strongly distorted CaIn2-like arrangement. Together, the palladium and indium atoms build a threedimensional [PdIn2] network in which the lanthanum atoms fill distorted pentagonal channels. The other REPdIn2 indides crystallize with the HfNiGa2 type, space group I4mm. Single crystals have been obtained for three compounds: a = 1397.7(1) pm, c = 925.5(1) pm, wR2 = 0.0662, 2098 F2 values, 64 variables for PrPdIn2; a = 1368.5(1) pm, c = 912.8(1) pm, wR2 = 0.1113, 2102 F2 values, 65 variables for Tb0.980(4)PdIn2.020(4); and a = 1358.8(1) pm, c = 908.4(1) pm, wR2 = 0.0777, 1983 F2 values, 64 variables for Tm0.986 (2)PdIn2.014(2). The terbium and thulium compounds show a small homogeneity range where the Tb3\Tm3 position shows mixed occupancy with indium. Again, the palladium and indium atoms form a three-dimensional [PdIn2] network, but is more complex when compared with that of LaPdIn2. The four crystallographically different rare earth metal atoms lie in larger voids formed by this network. The magnetic and electrical transport properties of REPdIn2 (RE = Pr, Nd, Sm, Gd, Er, Tm, and Lu) have been studied over wide ranges of temperature and magnetic field. All these indides except for LuPdIn2 show localized magnetism due to the presence of magnetic moments on the RE3+ ions. The compounds with RE = Pr, Nd, Sm, and Gd order magnetically at low temperatures. PrPdIn2 is antiferromagnetic below TN = 5.5 K. The other three phases show complex magnetic behavior below TN = 4.9, 9, and 10 K, for NdPdIn2, SmPdIn2, and GdPdIn2, respectively. In the case of GdPdIn2 the magnetic ordering involves a strong ferromagnetic component. For SmPdIn2 another phase transition at Tt = 5.5 K has been established, probably a change in the magnetic structure. In contrast to the other compounds, ErPdIn2 and TmPdIn2 remain Curie-Weiss paramagnetic down to 1.7 K, and LuPdIn2 is a Pauli paramagnet. All the compounds studied show metallic conductivity with some features characteristic of crystal field interactions and\or spin fluctuations. The magnetic phase transitions in PrPdIn2, NdPdIn2, SmPdIn2, and GdPdIn2 manifest themselves as distinct anomalies in the temperature-dependent resistivity. In the ordered state the resistivity shows a behavior reflecting reduction in the spin-disorder scattering