bcc superstructures: RE2RuIn with RE = Sc, Y, Dy-Tm and Lu

Abstract

The rare earth-rich intermetallic phases RE₂RuIn 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 Sc₂RuIn and Er₂RuIn were refined from single crystal X-ray diffraction data. The indides crystallize with the Pt₂ZnCd type space group P4/mmm. The RE₂RuIn phases are superstructures of the bcc packing and can be explained as intergrowth variants of tetragonally distorted, CsCl derived slabs of compositions RERu and REIn. Chemical bonding is discussed for Sc₂RuIn and Sc₂RuMg 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 Lu₂RuIn while Dy₂RuIn, Ho₂RuIn, Er₂RuIn and Tm₂RuIn are Curie–Weiss paramagnets. Antiferromagnetic ordering occurs at 13.1, 5.3 and 2.9 K for Dy₂RuIn, Er₂RuIn and Tm₂RuIn, respectively. Dy₂RuIn and Er₂RuIn show metamagnetic transitions at critical fields of 4.6 and 3.2 T.