bcc superstructures: RE 2 RuIn with RE = Sc, Y, Dy-Tm and Lu

The rare earth-rich intermetallic phases RE 2 RuIn with RE = Sc, Y, Dy-Tm and Lu were synthesized by reactions of the elements in sealed tantalum ampoules in an induction furnace. The samples were characterized through Guinier powder patterns and the structures of Sc 2 RuIn and Er 2 RuIn were refined from single crystal X-ray diffraction data. The indides crystallize with the Pt 2 ZnCd type space group P 4/ mmm . The RE 2 RuIn phases are superstructures of the bcc packing and can be explained as intergrowth variants of tetragonally distorted, CsCl derived slabs of compositions RE Ru and RE In. Chemical bonding is discussed for Sc 2 RuIn and Sc 2 RuMg in comparison with the binaries ScRu, ScMg and ScIn. The Ru/Mg respectively Ru/In ordering leads to an increase of Sc–Sc bonding for the slab with the shorter Sc–Sc distances, while the Sc–Ru bond strength values remain similar. The strongest bonding interactions occur within the magnesium and indium square nets. Magnetic susceptibility measurements reveal Pauli paramagnetism for Lu 2 RuIn while Dy 2 RuIn, Ho 2 RuIn, Er 2 RuIn and Tm 2 RuIn are Curie–Weiss paramagnets. Antiferromagnetic ordering occurs at 13.1, 5.3 and 2.9 K for Dy 2 RuIn, Er 2 RuIn and Tm 2 RuIn, respectively. Dy 2 RuIn and Er 2 RuIn show metamagnetic transitions at critical fields of 4.6 and 3.2 T.