Phonon sideband spectra and local structure around Eu 3+ ions in sodium silicate glasses

Abstract

The local structure around Eu 3+ ions in sodium silicate glasses was investigated by the phonon sideband associated with 5 D 2 ← 7 F 0 transition of Eu 3+. Since the shapes of the electronic transition were asymmetric due to the Stark splitting of 5D 2 level, the spectra were analyzed by assuming the superposition of the Gaussian distributions of phonon energy and coordination of non-bridging oxygen of the Q n ( n = 3, 2, 1) unit in silicate glass. The phonon energy almost corresponded to those of the stretching vibrations of Q n units by Raman spectra. The type and fraction of the Q n units coordinating Eu 3+ varied with alkaline content. The compositional variations of Q n units were similar to those determined by NMR for undoped alkaline silicate glasses. It is shown that the local structure around Eu 3+ is affected by the composition of matrix glass and the phonon sideband analysis can become a powerful technique to estimate the local distribution of Q n in silicate glasses.