Ternary rare-earth ruthenium and iridium germanides RE{sub 3}M{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu; M=Ru, Ir)

Journal Article · Sat Jun 15 00:00:00 EDT 2013 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2013.03.050· OSTI ID:22306337

Oliynyk, Anton O.; Stoyko, Stanislav S.; Mar, Arthur

Through arc-melting reactions of the elements and annealing at 800 °C, the ternary rare-earth germanides RE{sub 3}Ru{sub 2}Ge{sub 3} and RE{sub 3}Ir{sub 2}Ge{sub 3} have been prepared for most of the smaller RE components (RE=Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE{sub 2}IrGe{sub 2} were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf{sub 3}Ni{sub 2}Si{sub 3}-type structures (space group Cmcm, Z=4) for RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) and monoclinic Sc{sub 2}CoSi{sub 2}-type structures (space group C2/m, Z=4) for RE{sub 2}IrGe{sub 2}. Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE{sub 3}Ru{sub 2}Ge{sub 3} (a=4.2477(6) Å, b=10.7672(16) Å, c=13.894(2) Å for RE=Y; a=4.2610(3)–4.2045(8) Å, b=10.9103(8)–10.561(2) Å, c=14.0263(10)–13.639(3) Å in the progression of RE from Gd to Lu) and for Tb{sub 3}Ir{sub 2}Ge{sub 3} (a=4.2937(3) Å, b=10.4868(7) Å, c=14.2373(10) Å). Both structures can be described in terms of CrB- and ThCr{sub 2}Si{sub 2}-type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y{sub 3}Ru{sub 2}Ge{sub 3} support an alternative description for RE{sub 3}M{sub 2}Ge{sub 3} based on [M{sub 2}Ge{sub 3}] layers built from linked MGe{sub 4} tetrahedra, which emphasizes the strong M–Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE{sub 3}Ru{sub 2}Ge{sub 3} generally indicates metallic behaviour but with low-temperature transitions visible for some members (RE=Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y{sub 3}Ru{sub 2}Ge{sub 3} exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy{sub 3}Ru{sub 2}Ge{sub 3} reveal antiferromagnetic ordering at 3 K and several unusual field-dependent transitions suggestive of complex spin reorientation processes. - Graphical abstract: RE{sub 3}M{sub 2}Ge{sub 3} (M=Ru, Ir) adopts the Hf{sub 3}Ni{sub 2}Si{sub 3}-type structure containing slabs built up from Ge-centred trigonal prisms. - Highlights: • Crystal structures of RE{sub 3}Ru{sub 2}Ge{sub 3} (RE=Y, Gd–Tm, Lu) and Tb{sub 3}Ir{sub 2}Ge{sub 3} were determined. • Strong M–Ge covalent bonds were confirmed by band structure calculations. • Most RE{sub 3}Ru{sub 2}Ge{sub 3} members except Y{sub 3}Ru{sub 2}Ge{sub 3} exhibit metallic behaviour. • Dy{sub 3}Ru{sub 2}Ge{sub 3} displays unusual field-dependent magnetic transitions.

• OSTI ID: 22306337
• Journal Information: Journal of Solid State Chemistry, Vol. 202; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANNEALING
ANTIFERROMAGNETISM
CHEMICAL BONDS
CHROMIUM BORIDES
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
GERMANIDES
HYDROFLUORIC ACID
IRIDIUM
MAGNETIC PROPERTIES
MELTING
MONOCLINIC LATTICES
MONOCRYSTALS
ORTHORHOMBIC LATTICES
RARE EARTHS
RUTHENIUM
SEMICONDUCTOR MATERIALS
SPACE GROUPS
SPIN
X-RAY DIFFRACTION