Synthesis and Characterization of the Rare-Earth Vanadium Oxyselenides Ln7VO4Se8 (Ln=Nd, Sm, Gd)

✍ Scribed by Olivier Tougait; James A. Ibers

• Book ID: 102608650
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 181 KB
• Volume: 154
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8884

✦ Synopsis

The new compounds Ln 7 VO 4 Se 8 (Ln ‫؍‬ Nd, Sm, Gd) were each prepared by heating V, Se, and the corresponding rare-earth sesquioxide at 1223 K in a sealed fused-silica tube. Single crystals have been grown through the use of an antimony 6ux. They have been characterized by single-crystal and powder X-ray di4raction measurements and by energy dispersive X-ray analysis. These isostructural compounds crystallize with two formula units in the orthorhombic space group Pbam in cells (at 153 K) of dimensions: Nd 7 VO 4 Se 8 , a ‫؍‬ 14.3419(9) A > , b ‫؍‬ 15.5528(10) A > , c ‫؍‬ 3.9948(3) A > ; Sm 7 VO 4 Se 8 , a ‫؍‬ 14.200(2) A > , b ‫؍‬ 15.451(2) A > , c ‫؍‬ 3.9511(6) A > ; Gd 7 VO 4 Se 8 , a ‫؍‬ 14.075(8) A > , b ‫؍‬ 15.424(6) A > , c ‫؍‬ 3.903(1) A > . The new structure type comprises four crystallographically independent Ln atoms with three di4erent coordination geometries and one V atom in an octahedral environment. Magnetic measurements reveal that Gd 7 VO 4 Se 8 is paramagnetic down to 5 K.