MOSSBAUER EFFECT AND X-RAY DISTRIBUTION FUNCTION ANALYSIS IN COMPLEX Na.OCaOZnO--Fe_2O_rAl_2O_3--SiO_2 GLASSES AND GLASS-CERAMICS

摘要

M0ssbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO_2--CaO- ZnO--Na_2O--Fe_2O_3--Al_2O_3 system. Isomer shift values of the glasses suggest that Fe~3+ and Fe~2+ are in tetrahedral and octahedral coordination, respec- tively. The spectrum of the glass-ceramic shows that about 60 wt/100 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 distorted when the iron content is greater. X-ray diffraction measurements were carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.