A study of the local structure around Eu 3+ ions in oxide glasses using Mössbauer spectroscopy

Abstract

The local structure around Eu 3+ ions in several oxide glasses (silicate, germanate and borophosphate glasses) was investigated by using 151Eu Mössbauer spectroscopy. It was found that the isomer shift (IS) of silicate and borophosphate glasses was independent of the sodium content, but that of germanate glasses was not. This means the first coordination sphere around Eu 3+ ions in silicate glasses is insensitive to the composition of the glass matrix. It is assumed that, regardless of the sodium content, Eu 3+ ions in silicate glasses attract a certain amount of nonbridging oxygen (NBO, SiO ⊖) when incorporated stably into silicate glass matrix, because NBO is the only species donating negative charge. For germanate glasses, the behavior of IS is considered to be related to the presence of GeO 6 2 octahedra. On the basis of experimental results, the coordination models of Eu 3+ in these systems are proposed.