Preparation and photoluminescence of Eu-doped oxyfluoride borosilicate glass ceramics

Eu-doped transparent oxyfluoride borosilicate glass ceramics containing Ba2GdF7 nanocrystals were prepared by controlling crys-tallization 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 excita-tion and emission spectra.