SYNTHESIS, CHARACTERIZATION AND RIETVELD REFINEMENT OF THE TETRAGONAL VARIANT OF ALPO4-16 PREPARED IN FLUORIDE MEDIUM

The tetragonal variant of AlPO4-16 isostructural of the clathrasil octadecasil was obtained by using quinuclidine as a template in the presence of fluoride anions. The as-synthesized material was characterized by C-13, F-19, Al-27 and P-31 nuclear magnetic resonance (NMR) spectroscopy. The structure was refined in the space group I4BAR [a = 9.3423 (1) angstrom, c = 13.4760 (2) angstrom] from powder X-ray data. The position parameters of the four highest maxima of the residual electron density representative of the disordered organic species were used in the refinement procedure. Part of the fluoride present in the material was found in the D4R units of the structure. The final Rietveld residuals are R(F) = 0.034 and R(wp) = 0.114.