Luminescent properties of Tb3+-doped transparent glass ceramics

Dense transparent glass ceramics containing BaGdF5 and BaLu2F8 nanocrystals were prepared from the Tb3+-activated SiO2-B2O3-BaF2-Lu2O3-Gd2O3 oxyfluoride scintillating glasses by thermal treatment technology. Glass structure was investigated by X-ray diffraction (XRD) and scanning electron micrograph (SEM); the optical properties including transmission, luminescent properties excited under both ultraviolet light and X-ray excitation, and the decay times of the glass and glass ceramics were also investigated. The coexistence of BaGdF5 and BaLu2F8 nanocrystals in the transparent glass ceramics was confirmed by the XRD results, which plays a key role in the improvement of scintillation performance. The density of glass ceramics is higher compared with the precursor glass, and it increases with the increasing temperature of heat treatment. Moreover, a blue-shift in the excitation spectra and the decreasing decay times of Tb3+ ions are obviously observed in the glass and glass ceramics with the increasing heat treatment temperature. Compared with the precursor glass, the enhanced emission intensity of Tb3+ ions in the glass ceramics is associated with the increasing energy transfer efficiency from Gd3+ to Tb3+ ions, which is due to the precipitation of BaGdF5 and BaLu2F8 nanocrystals in glass ceramics. In addition, the energy transfer efficiency from Gd3+ to Tb3+ ions was also discussed by the stretched exponential function.