High quantum yield and low concentration quenching of Eu3+ emission in oxyfluoride glass with high BaF2 and Al2O3 contents

• New oxyfluoride glasses with high amount of BaF2 and Al2O3 were synthesized.
• Photoluminescence properties of Eu3+ in the oxyfluoride glasses were clarified.
• The glasses showed excellent red luminescence with extremely high quantum yield up to 97%.
• The effect of concentration quenching was also very small.
• High efficient green and yellow emission were also achieved in the glasses.

New oxyfluoride glasses of 1Eu2O3–50BaF2–xAl2O3–(50−x)B2O3 (x = 0–25), yEu2O3–50BaF2–25Al2O3–25B2O3 (y = 0–10) (mol), and zEu2O3–1Tb4O7–50BaF2–25Al2O3–25B2O3 (z = 0, 0.5) (mol) with a high fluorine content (F/(F + O) = 0.4) were synthesized by using a conventional melt-quenching method, and photoluminescence properties such as quantum yield (η), lifetime (τ), and concentration quenching effect of Eu3+ ions were clarified. The glass with 25Al2O3 showed an excellent red luminescence with extremely high quantum yield (η) of 97% in the visible region at the excitation of the wavelength λ = 396 nm and a long lifetime of τ = 3.29 ms for the emission (λ = 612 nm) of Eu3+ ions at the 5D0 level. The effect of concentration quenching in these glasses was also very small, e.g., η = 72% even for the glass with 10Eu2O3. The values of η = 52% for the green emission of Tb3+ ions and of η = 81% for the yellow emission of Eu3+–Tb3+ co-doped ions were also achieved in the glasses. The present study indicates that rare-earth ions of Eu3+ and Tb3+ are dispersed homogeneously in these oxyfluriode glasses and the degree of their its asymmetry (i.e., the electric field gradient) is also widely distributed due to the coordination of both F− and O2− ions. The new oxyfluoride glasses with high BaO and Al2O3 contents have a high potential as hosts for new phosphors with rare-earth ions.