Preparation and photoluminescence of Eu-doped oxyfluoride borosilicate glass ceramics

Eu-doped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared by controlling crystallization of melt-quenched glass fabricated under a reductive atmosphere. In the oxyfluoride borosilicate glass ceramics, the mean crystal size of Ba2GdF7 nanocrystals was about 30 nm, which could be observed by X-ray diffraction (XRD) and transmission electron microscopy analysis. The photoluminescence spectra of the samples excited at 392 nm showed that, besides the characteristic sharp emissions of Eu3+ ions, a very intense broadband emission of Eu2+ ions centered at 450 nm appeared. The photoluminescence intensity of Eu3+ and Eu2+ ions in the glass ceramics was much stronger than that in the as-made precursor. The long decay lifetimes of Eu3+ and Eu2+ ions evidenced the partitions of Eu3+ and Eu2+ ions into the Ba2GdF7 nanocrystals. The energy transfer from Gd3+ ions to Eu3+ and Eu2+ ions was confirmed by the excitation and emission spectra.