Synthesis and structures of M₈[ALSiO₄]₆·(XO₄)₂, M = Na, Li, K; X = Cl, Mn Sodalites

Sodalites with the formulae Na[AlSiO]·(ClO), Na[AlSiO]·(MnO), and KNa[AlSiO]·(ClO) have been synthesized and characterized by powder X-ray diffraction, neutron diffraction, Si MAS n.m.r., FT i.r., and FT-Raman spectroscopy. The structures were determined by Rietveld refinement of powder neutron diffraction data at both 4 and 300 K in order to delineate as far as possible the framework and anion geometries. For all refinements, the positions of the framework atoms and the metals are in good agreement with similar sodalites with varying amounts of framework collapse. The central anion was found to be highly disordered with 12 possible orientations of the tetrahedral XO group.