VIBRATIONAL-SPECTRA OF COMPLEX RING SILICATE ANIONS - METHOD OF RECOGNITION

In this work is presented an attempt to apply vibrational spectroscopy to study the structure of ring silicates, in particular to recognize the number of members in tetrahedra. A number of synthetic ring silica tes prepared by various methods was subjected to the studies. They con tained cations of various metals (Na, Ca, Sr, Pb), and the polyanions occurring in their structures differed in both the number of ring memb ers (n = 3, 4 and 6) and the extent of deformation. The bands characte ristic of the ring systems are located mainly in the middle IR spectra in the range 780-500 cm(-1). The bands due to Si-O vibrations were as signed as originating from both subunits containing bridging oxygen at oms (Si-O-Si) and those containing terminal oxygen atoms (Si-O-, broke n bridges). The influence of crystalline field on the shape of the spe ctra has been analyzed. (C) 1997 Elsevier Science B.V.