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

Abstract

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 ⁴F_9/2 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.