LaPdIn 2 with MgCuAl 2 and REPdIn 2 (RE ) Y, Pr, Nd, Sm, Gd-Tm, Lu) with HfNiGa 2 -Type Structure: Synthesis, Structure, and Physical Properties Vasyl’ I. Zaremba † Inorganic Chemistry Department, Ivan Franko National University, Kyryla and Mephodiya Street 6, 79005 Lviv, Ukraine Dariusz Kaczorowski ‡ Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw, Poland Ute Ch. Rodewald, Rolf-Dieter Hoffmann, and Rainer Po ¨ttgen* Institut fu ¨ r Anorganische und Analytische Chemie, Universita ¨ t Mu ¨ nster, Wilhelm-Klemm-Strasse 8, D-48149 Mu ¨ nster, Germany Received October 9, 2003. Revised Manuscript Received November 10, 2003 New indides REPdIn 2 (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 LaPdIn 2 were obtained by recrystallization of a LaPdIn 2 sample from an indium flux. LaPdIn 2 crystallizes with the MgCuAl 2 structure: Cmcm, a ) 463.79(7) pm, b ) 1074.3(2) pm, c ) 746.4(2) pm, wR2 ) 0.1149, 380 F 2 values, and 16 variables. The structure may be described as a palladium-filled LaIn 2 substructure. The latter is a strongly distorted CaIn 2 -like arrangement. Together, the palladium and indium atoms build a three-dimensional [PdIn 2 ] network in which the lanthanum atoms fill distorted pentagonal channels. The other REPdIn 2 indides crystallize with the HfNiGa 2 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 F 2 values, 64 variables for PrPdIn 2 ; a ) 1368.5(1) pm, c ) 912.8(1) pm, wR2 ) 0.1113, 2102 F 2 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 F 2 values, 64 variables for Tm 0.986(2) PdIn 2.014(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 [PdIn 2 ] network, but is more complex when compared with that of LaPdIn 2 . The four crystallographically different rare earth metal atoms lie in larger voids formed by this network. The magnetic and electrical transport properties of REPdIn 2 (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 LuPdIn 2 show localized magnetism due to the presence of magnetic moments on the RE 3+ ions. The compounds with RE ) Pr, Nd, Sm, and Gd order magnetically at low temperatures. PrPdIn 2 is antiferromagnetic below T N ) 5.5 K. The other three phases show complex magnetic behavior below T N ) 4.9, 9, and 10 K, for NdPdIn 2 , SmPdIn 2 , and GdPdIn 2 , respectively. In the case of GdPdIn 2 the magnetic ordering involves a strong ferromagnetic component. For SmPdIn 2 another phase transition at T t ) 5.5 K has been established, probably a change in the magnetic structure. In contrast to the other compounds, ErPdIn 2 and TmPdIn 2 remain Curie-Weiss paramagnetic down to 1.7 K, and LuPdIn 2 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 PrPdIn 2 , NdPdIn 2 , SmPdIn 2 , and GdPdIn 2 manifest themselves as distinct anomalies in the temper- ature-dependent resistivity. In the ordered state the resistivity shows a behavior reflecting reduction in the spin-disorder scattering. Introduction Recent investigations of the ternary alkaline earth metal (AE)-transition metal (T)-indium and tin sys- tems revealed a large family of intermetallic compounds AETIn 2 (AE ) Ca, Sr, Ba; T ) Ni, Cu, Rh, Pd, Ir, Pt, Au) 1-5 and CaTSn 2 (T ) Rh, Pd, Ir). 6 The structural chemistry and chemical bonding of these indides and stannides can easily be understood on the basis of the Zintl-Klemm concept. These intermetallics crystallize with the orthorhombic MgCuAl 2 -type structure (space * To whom correspondence should be addressed. E-mail: pottgen@uni- muenster.de. † E-mail: vazar@franko.lviv.ua. ‡ E-mail: dkaczor@int.pan.wroc.pl. 466 Chem. Mater. 2004, 16, 466-476 10.1021/cm031139m CCC: $27.50 © 2004 American Chemical Society Published on Web 01/13/2004