Synthesis and characterisation of a stannosilicate with the structure of penkvilksite-1M

The hydrothermal synthesis of the small-pore framework sodium stannosilicate Na2SnSi4O11 · 2H2O (Sn-AV-14) possessing the structure of the rare titanosilicate mineral penkvilksite-1M has been reported. The synthesis of this material has been optimised and shown to be very sensitive to the composition of the precursor gel, particularly the Si and water contents. Seeding is required to obtain this phase. The framework of Sn-AV-14 consists of [Si4O11] silicate sheets (arising from the combination of spiral chains formed by corner-sharing SiO4 tetrahedra) interconnected by SnO6 octahedra. Narrow six-ring channels run along [0 1 0] and [0 0 1], housing Na+ and water molecules. Sn-AV-14 materials have been studied by bulk chemical analysis, powder X-ray diffraction, scanning electron microscopy, 23Na, 29Si and 119Sn magic-angle spinning NMR, Fourier transformed infrared spectroscopy and thermogravimetry.