Judd–Ofelt analyses and luminescence of Er3+/Yb3+ co-doped transparent glass ceramics containing NaYF4 nanocrystals

Er3+/Yb3+ co-doped transparent glass ceramics containing NaYF4 nanocrystals were prepared by melt-quenching and subsequent heating. Judd–Ofelt analyses of Er3+ ions in the precursor glasses and glass ceramics were performed to evaluate the intensity parameters Ω2,4,6. The Ω2 value of glass ceramic is smaller than that of glass, which reflects the change of Er3+ local structure after crystallization, i.e., Er3+ partitions into the precipitated NaYF4 nanocrystals. Under 980 nm excitation, intense red and green upconversion luminescence induced by efficient energy transfer from Yb3+ to Er3+ was achieved in the glass ceramics. Based on the fluorescence decay lifetimes, the energy transfer efficiency was evaluated, with the maximum value exceeding 68% for the 1 mol% Yb3+/2 mol% Er3+ co-doped sample.