Mossbauer effect and X-ray distribution function analysis in complex Na2O-CaO-ZnO-Fe2O3-Al2O3-SiO3 glasses and glass-ceramics

Mossbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO2-CaOZn O-Na2O-Fe2O3-Al2O3 system. Isomer shift values of the glasses suggest that Fe3+ and Fe2+ are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe+3/Fe+2 ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distor ted when the iron content is greater. X-ray diffraction measurements were c arried out to obtain the radial distribution function (RDF). The interatomi c distances for Si-Si and Si-O have been determined. The complex compositio n of these glasses does not allow the estimation of Al-O and Fe-O distances . (C) 1999 Elsevier Science Ltd.