Spectral properties and self-reduction of Eu3+ to Eu2+ in aluminosilicate oxyfluoride glass

Eu-doped aluminosilicate oxyfluoride glass prepared via a melt-quenching method was investigated using X-ray diffraction, absorption spectroscopy, X-ray fluorescence spectrometry, photoluminescence spectroscopy and fluorescence decay curves. We found that the reduction of Eu3+ to Eu2+ ions occurred in the glass prepared in air. The emission spectra showed that the intensity of 4f65d → 4f7 transition of Eu2+ ions varied with increasing incident beam wavelength. Meanwhile, the fluorescence lifetimes of Eu3+: 5D0 → 7F2 monitored at 617 nm in the glass change with the variation of excitation wavelength. The energy transfer between Eu2+ and Eu3+ and the emission mechanisms of Eu2+ ions in the glass were also discussed.