FINE-PROBING THE CRYSTAL-CHEMISTRY OF TALC BY MAS-NMR SPECTROSCOPY

Abstract

Magic-Angle-Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy was used to probe the crystallographic environment of Si, Al, F and H in 14 natural talc samples originating from different localities and containing various, small amounts of iron (Fe2O3[total]< 2 wt %). We show that iron induces strong variations in NMR spectra and that even very low quantities can be used as an indirect NMR parameter to characterize in detail the crystal-chemistry of talc. Conversely, their correlations with full width at half height (FWHH) in MAS-NMR spectra for 29Si, 27A1, 'H, and 19F obtained from these 14 talc samples allow for rapid estimations of the total iron content. Finally we highlight how, by simply recording Mössbauer, NIR and NMR spectra, one can obtain an accurate structural formula of talc, which is a necessary parameter for uses in specific industrial applications. © 2006 E. Schweizerbart'sche Verlagsbuchhandlung.