Luminescence and energy transfer in Dy3+/Eu3+ co-doped aluminosilicate oxyfluoride glasses and glass-ceramics

Highlights: • Dysprosium and europium singly- and co-doped oxyfluoride glasses were synthesized. • Glass ceramics were obtained by the heat treatment method at 680 °C and 750 °C. • The average lifetimes of Dy³⁺ (⁴F_9/2 → ⁶H_13/2) decrease with the addition of Eu³⁺ ions • Energy transfer from Dy³⁺ to Eu³⁺ ions in glasses and glass ceramics was evaluated. • Samples with similar Dy³⁺ and Eu³⁺ doping concentrations emit white light. A series of oxyfluoride glasses with the composition SiO₂–CaF₂–Al₂O₃–CaO, doped with Dy₂O₃ (0.5–1 mol%) and Eu₂O₃ (0–4 mol%), have been prepared using the melt quenching method. The glass-ceramics have been obtained by heating the as-made glasses at 680 °C and 750 °C for 1 h. The glasses and the glass-ceramics were investigated using photoluminescence techniques in the near-UV and visible ranges, and differential thermal analysis (DTA) and x-ray diffraction (XRD) measurements were performed. The samples doped with 0.5 mol% Dy³⁺ were observed to have the highest luminescence intensity under 453 nm excitation compared to the samples doped with 1 mol% Dy³⁺ and the co-doped samples. The increased luminescence intensity could be caused by energy transfer between rare-earth (RE) ions and cross-relaxation of Dy³⁺ ions. Energy transfer from Dy³⁺ to Eu³⁺ ions in the glasses and the glass-ceramics was confirmed by excitation spectra and luminescence decay kinetics. The average luminescence lifetimes of the Dy³⁺ emission band at 575 nm under 453 nm excitation decrease with the addition of Eu³⁺ ions. Energy transfer in the glasses and the glass-ceramics was estimated to be in the range from 11% to 68%, depending on the RE ion concentration.