Crystal structures of two tin–tungsten oxides

Abstract

A compound of approximate composition Sn_0·2WO₃ has an orthorhombic structure, space-group Pmma, with a= 7·415 ± 0·002, b= 3·787 ± 0·005, c= 20·40 ± 0·02 Å, and a superstructure containing 12 of these units. The structure of the basic unit, was determined from photographic data by Patterson techniques and refined by least-squares methods to R 0·13 for 395 reflections. It is formed by corner-sharing octahedra, both the tungsten and tin ions occupying the octahedra. A similar structure of composition Sn_0·3WO₃ was also determined and refined to R 0·15 for 295 reflections. The basic unit has space-group Cmmm and unit-cell dimensions a= 7·12 ± 0·03, b= 33·24 ± 0·04, c= 3·795 ± 0·004 Å; the superstructure contains 14 of the basic units.