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

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• 作者：Vasyl' I. Zaremba ; Dariusz Kaczorowski ; Ute Ch. Rodewald ; Rolf-Dieter Hoffmann ; and Rainer P&ouml ; ttgen
• 刊名：Chemistry of Materials
• 出版年：2004
• 出版时间：February 10, 2004
• 年：2004
• 卷：16
• 期：3
• 页码：466 - 476
• 全文大小：336K
• 年卷期：v.16,no.3(February 10, 2004)
• ISSN：1520-5002

文摘

New indides REPdIn₂ (RE = Y, La, Pr, Nd, Sm, Gd-Tm, Lu) have been synthesized fromthe elements by arc-melting. The indides with Y, Pr, Nd, Sm, Gd-Tm, and Lu as the rareearth metal component have been obtained in pure form by annealing the arc-melted samplesin tantalum containers. Single crystals of LaPdIn₂ were obtained by recrystallization of aLaPdIn₂ 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 palladium-filled LaIn₂ substructure.The latter is a strongly distorted CaIn₂-like arrangement. Together, the palladium andindium atoms build a three-dimensional [PdIn₂] network in which the lanthanum atoms filldistorted 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 Tb_0.980(4)PdIn_2.020(4);and a = 1358.8(1) pm, c = 908.4(1) pm, wR2 = 0.0777, 1983 F² values, 64 variables forTm_0.986(2)PdIn_2.014(2). The terbium and thulium compounds show a small homogeneity rangewhere the Tb3/Tm3 position shows mixed occupancy with indium. Again, the palladium andindium atoms form a three-dimensional [PdIn₂] network, but is more complex when comparedwith that of LaPdIn₂. The four crystallographically different rare earth metal atoms lie inlarger voids formed by this network. The magnetic and electrical transport properties ofREPdIn₂ (RE = Pr, Nd, Sm, Gd, Er, Tm, and Lu) have been studied over wide ranges oftemperature and magnetic field. All these indides except for LuPdIn₂ show localizedmagnetism due to the presence of magnetic moments on the RE³⁺ ions. The compoundswith RE = Pr, Nd, Sm, and Gd order magnetically at low temperatures. PrPdIn₂ isantiferromagnetic below T_N = 5.5 K. The other three phases show complex magnetic behaviorbelow T_N = 4.9, 9, and 10 K, for NdPdIn₂, SmPdIn₂, and GdPdIn₂, respectively. In the caseof GdPdIn₂ the magnetic ordering involves a strong ferromagnetic component. For SmPdIn₂another phase transition at T_t = 5.5 K has been established, probably a change in themagnetic structure. In contrast to the other compounds, ErPdIn₂ and TmPdIn₂ remainCurie-Weiss paramagnetic down to 1.7 K, and LuPdIn₂ is a Pauli paramagnet. All thecompounds studied show metallic conductivity with some features characteristic of crystalfield 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 reflectingreduction in the spin-disorder scattering.