Upconversion luminescence in erbium doped transparent oxyfluoride glass ceramics containing hexagonal NaYF4 nanocrystals

In this work transparent erbium doped oxyfluoride glass ceramics containing hexagonal NaYF4 nanocrystals has been prepared by melt-quenching and subsequent heat treatment of the precursor glass. The formation of β-NaYF4 was confirmed by X-ray diffraction measurements. The overall intensity of the upconversion luminescence of the glass ceramics sample is 2 orders of magnitude higher than that of the precursor glass. The observed enhancement of the efficiency is explained by the incorporation of Er3+ into low-phonon β-NaYF4 crystalline phase.