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

Abstract

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.