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Title: Synthesis, structure and properties of the oxychalcogenide series A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd, Tb, Dy, Ho, Er and Y)

Seven oxyselenide materials have been synthesised with composition A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) via solid state reactions of A{sub 2}O{sub 3}, TiSe{sub 2} and Se at 900 °C. They are all isostructural with Gd{sub 4}O{sub 4}TiSe{sub 4}. Structures have been refined from powder X-ray diffraction data and have monoclinic C2/m symmetry with unit cell parameters of a≈15.7 Å, b≈3.75 Å, c≈9.65 Å and β≈117.5°. They contain infinite ribbons of edge-sharing A{sub 4}O and A{sub 3}TiO tetrahedra 4 units wide, which are linked by chains of TiSe{sub 4}O{sub 2} edge-sharing octahedra. Compositions A=Gd–Ho, Y are semiconductors with conductivities 1–3 Sm{sup −1} at 300 K, with electronic band gaps of between 0.25 and 0.37 eV. Magnetic susceptibility is reported from 1.8 K to 300 K for compositions A=Gd–Ho. Rare earth moments appear to order antiferromagnetically at low temperatures with Gd and Tb showing evidence of ferromagnetism due to spin canting over a narrow temperature range close to T{sub N}. - Graphical abstract: Illustration of the A{sub 4}O{sub 4}TiSe{sub 4} crystal structure (C2/m symmetry), A{sub 4}O and A{sub 3}TiO edge sharing tetrahedral ribbons in red, chains of edge-sharing TiSe{sub 4}O{sub 2} in blue. Rare earth=green, titanium=blue, selenium=yellow, and oxygen=red. Display Omittedmore » - Highlights: • Seven materials with A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) have been synthesised as bulk phases for the first time. • Materials are semiconductors and order antiferromagnetically at ∼4 K. • Structure contains M{sub 4}O tetrahedral ribbons and TiSe{sub 4}O{sub 2} 1D octahedral chains.« less
Authors:
;
Publication Date:
OSTI Identifier:
22274214
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 210; Journal Issue: 1; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ELECTRIC CONDUCTIVITY; FERROMAGNETISM; MAGNETIC SUSCEPTIBILITY; MONOCLINIC LATTICES; POWDERS; RARE EARTHS; SEMICONDUCTOR MATERIALS; SOLIDS; SYNTHESIS; TEMPERATURE RANGE 0065-0273 K; TITANIUM; TITANIUM SELENIDES; X-RAY DIFFRACTION