Raman and infrared study of phyllosilicates containing heavy metals (Sb, Bi): bismutoferrite and chapmanite

The kaolinite-like phyllosilicate minerals bismutoferrite BiFe(2)(3+)Si(2)O(8)(OH) and chapmanite SbFe(2)(3+)Si(2)O(8)(OH) have been studied by Raman spectroscopy and complemented with infrared spectra. Tentatively interpreted spectra were related to their molecular structure. The antisymmetric and symmetric stretching vibrations of the Si-O-Si bridges, delta SiOSi and delta OSiO bending vibrations, nu (Si-O(terminal)) stretching vibrations, nu OH stretching vibrations of hydroxyl ions, and delta OH bending vibrations were attributed to the observed bands. Infrared bands in the range 3289-3470 cm(-1) and Raman bands in the range 1590-1667 cm(-1) were assigned to adsorbed water. O-H center dot center dot center dot O hydrogen-bond lengths were calculated from the Raman and infrared spectra. Copyright (C) 2009 John Wiley & Sons, Ltd.