Spectral properties and self-reduction of Eu(3+) to Eu(2+) 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 Eu(3+) to Eu(2+) ions occurred in the glass prepared in air. The emission spectra showed that the intensity of 4f(6)5d → 4f(7) transition of Eu(2+) ions varied with increasing incident beam wavelength. Meanwhile, the fluorescence lifetimes of Eu(3+): (5)D(0) → (7)F(2) monitored at 617 nm in the glass change with the variation of excitation wavelength. The energy transfer between Eu(2+) and Eu(3+) and the emission mechanisms of Eu(2+) ions in the glass were also discussed.