Crystallization and spectroscopic properties of Eu-doped CaF2 nanocrystals in transparent oxyfluoride glass-ceramics

Transparent oxyfluoride glass-ceramic in the system SiO₂–Al₂O₃–CaF₂–EuF₂ containing Eu-doped CaF₂ nanocrystals were produced by using the controlled crystallization of melt-quenched glass. X-ray diffraction and transmission electron microscopy data have revealed the formation of the CaF₂ nanocrystals of about 65 nm size. Photoluminescence spectra have shown an increase of the splitting of the luminescences associated to the Eu³⁺ ion along with annealing time which is consistent with the Eu³⁺ environment evolving from a glassy to a crystalline state.