Crystal structure and magnetic properties of Sm3ReO7

Crystals of a new ternary samarium rhenium oxide, Sm3ReO7 were obtained by subsolidus reaction of samariumsesquioxide and rheniumdioxide (ratio 1.5:1) in sealed Pt-10Rh-tubes at 1673 K. The structure was determined by single-crystal X-ray diffraction. Sm3ReO7 crystallizes in the orthorhombic system with unit cell dimensions a = 10.736(5), b = 7.392(3), and c = 7.519(3) in space group Cmcm (No. 63) with Z = 4, The structure consists of ReO6 octahedra, distorted SmO6 octahedra, and SmO8 prisms that are interconnected to each other to form a three-dimensional network, Rhenium has the formal oxidation state of +5 but no metal-metal bond is observed in this compound. The observed magnetization in the temperature range 4 K < T < 52 K is explained by a Curie-Weiss law modified by a temperature independent Van Vleck paramagnetism of samarium (3+). (C) 1996 Academic Press, Inc.