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

Abstract Eu/Tb codoped transparent oxyfluoride borosilicate glass ceramics containing Sr 2 GdF 7 nanocrystals were fabricated under a reductive atmosphere and the conversion of Eu 3+ ions to Eu 2+ ions was observed. The Sr 2 GdF 7 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 5 D 0  →  7 F 2 and 5 D 0  →  7 F 1 , and long fluorescence lifetimes of Eu 2+ , Eu 3+ , and Tb 3+ ions revealed that more rare earth ions were partitioned into the low phonon energy environment Sr 2 GdF 7 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.