Structure and luminescence properties of Eu/Tb codoped oxyfluoride glass ceramics containing Sr2GdF7 nanocrystals

Abstract Eu/Tb codoped transparent oxyfluoride borosilicate glass ceramics containing Sr2GdF7 nanocrystals were fabricated under a reductive atmosphere and the conversion of Eu3+ ions to Eu2+ ions was observed. The Sr2GdF7 nanocrystals with an average size of 32 nm were homogeneously precipitated in the oxyfluoride borosilicate glass matrix, which could be evidenced by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy. The enhancement of photoluminescence emission intensity, reduction of the relative emission intensities between 5D0 → 7F2 and 5D0 → 7F1, and long fluorescence lifetimes of Eu2+, Eu3+, and Tb3+ ions revealed that more rare earth ions were partitioned into the low phonon energy environment Sr2GdF7 nanocrystals. Under ultraviolet excitation, pure and bright white light emission was obtained in the oxyfluoride borosilicate glass ceramic, which may be a potential blue, green and red-emitting phosphor for white LEDs.