XAFS Study of Fe K Edge in Al_2O_3-B_2O_3-Fe_2O_3-Na_2O-SiO_2 Glasses

摘要

Valence state and local environment of Fe in complex glasses related to the system Al_2O_3-B_2O_3-Fe_2O_3-Na_2O-SiO_2 were studied. In all the glasses, the major fraction of Fe exists as Fe~(3+) ions but a minor fraction of Fe~(2+) ions especially in the glass with the lowest K=[SiO_2]/[B_2O_3] ratio was also present. Average Fe - O distance in the first shell is 1.80-1.85 A and coordination number is 4-6. The intensity due to the second sphere is rather weak demonstrating homogeneous distribution of Fe ions in the glass.