THE CRYSTAL-STRUCTURE OF CS2TISI6O15

Crystals of a new titanosilicate phase, Cs2TiSi6O15, were grown from a cesium vanadate flux. The compound has monoclinic symmetry, space gro up C2/c, with a 13.386(5), b = 7.423(3), c = 15.134(5) Angstrom = beta = 107.71(3)degrees, Z = 4. The crystal structure was solved using sin gle crystal X-ray data (MoK alpha radition) and refined to R(F) = 0.03 9 for 1874 unique reflections. In the structure, isolated titanium-cen tred octahedra and silica-centred tetrahedra share all corners to form an open framework structure containing large cavities in which the ce sium ions are located. Each cavity is bound by three 5-rings, two 6-ri ngs, and two 8-rings. The cavities are linked via the 8-rings into cha nnels parallel to [101]. The cesium ions occur in pairs along the chan nels, separated by 3.765(2) Angstrom. (C) 1997 Academic Press.