Single crystals of the cerium(III) borosilicate Ce-3[BSiO6][SiO4]

Colorless, lath-shaped single crystals of Ce-3[BSiO6][SiO4] (orthorbombic, Pbca; a=990.07(6), b=720.36(4), c=2329,2(2)pm, Z=8) were obtained in attemp ts to synthesize fluoride berates with trivalent cerium in evacuated silica tubes by reaction of educt mixtures of elemental cerium, cerium dioxide, c erium trifluoride, and boron sesquioxide (Ce, CeO2, CeF3, B2O3; molar ratio 3:1:3:3) in fluxing CsCl (700 degreesC, 7d) with the glass wall, The cryst al structure contains eight- (Ce1) and ninefold coordinated Ce3+ cations (C e2 add Ce3) surrounded by oxygen atoms. Charge balance is achieved by both discrete borosilicate ([BSiO6](5-) = [O2BOSiO3](5-)) and ortho-silicate ani ons ([SiO4](4-)). The former consists of a [BO3] triangle linked to a [SiO4 ] tetrahedron by a single vertex, The anions form layers in [001] direction alternatingly built up from [BSiO6](5-) and [SiO4](4-) groups while Ce3+ c ations are located in between.