Glass-ceramic materials: influence of fluoride nanocrystals on emission properties of lanthanide ions

In this work, the oxyfluoride glass-ceramic materials containing LaF3 nanocrystals, prepared by using the sol-gel method, were described. The influence of fluoride nanocrystals on the photoluminescence properties of selected lanthanide ions was determined. The experimental results obtained for nano-glass-ceramics were compared to the precursor xerogels. Those Ln3+-doped sol-gel materials with dispersed LaF3 nanocrystals exhibit several visible emission bands. It was observed that heat-treatment process caused the elongation of the lifetimes of the 5D0 state from τ = 0.22 ms to τ1 = 0.79 ms, τ2 = 9.76 ms (for Eu3+-doped materials) and of the 4F9/2 state from τ = 0.027 ms to τ1 = 0.034 ms, τ2 = 1.731 ms (for Dy3+‑doped materials). The performed studies clearly revealed that luminescence behaviour also depends on an activator concentration and a distribution of energy levels of lanthanide ions.