SPECTROSCOPIC EVIDENCE OF OCTAHEDRAL IRON(III) IN SODA-LIME SILICATE-GLASSES

Optical X-ray and Mossbauer absorption spectroscopies were used to observe the environment of Fe3+ ions in oxidized soda-lime silicate glasses (with 0.3, 3 and 8% Fe2O3), melted at 1450-degrees-C. The Mossbauer lineshapes show magnetic relaxation phenomena. Optical absorption spectra are mainly characterized by peaks of ferric iron in fourfold environment and, for the 0.3% Fe2O3 glass, by two bands near 1100 and 1600 cm-1 attributed to the sixfold environment. These two bands are not detected in samples with higher iron concentrations. X-ray absorption spectra of the 3 and 8% Fe2O3 glasses present in a split pre-edge in which fine structure confirms the presence of trivalent iron in the two coordinations.