Luminescent properties of Ce3+/Tb3+ co-doped glass ceramics containing YPO4 nanocrystals for W-LEDs

Ce3+/Tb3+ co-doped transparent glass ceramics containing YPO4 nanocrystals were prepared using high temperature melting method, and their structural and luminous properties were investigated. XRD analysis and TEM images confirmed the existence of YPO4 nanocrystals in glass ceramics. The transmission spectra proved that the glass ceramics specimens still maintained a high transparency. Then the excitation and emission spectra of the Ce3+ and Tb3+ single-doped and co-doped glass and glass ceramics were discussed, which proved that the glass ceramics had better luminescent properties. Under the near ultraviolet (331 nm) excitation, the broadband emission located at 385 nm was observed which was ascribed to 5d -> F-2(5/2) and F-2(7/2) transition of Ce3+ ions. Several characteristic sharp peaks centered at 489, 543, 578 and 620 nm originated from the D-5(4) to F-7(J) (J=6, 5, 4, 3) of Tb3+ ions. The decay time of Tb3+ ions at 543 nm and the relevant energy levels of Ce3+ ions and Tb3+ ions illustrated the transfer process from Ce3+ ions to Tb3+ ions. The best CIE chromaticity coordinate of the glass ceramics specimen was calculated as (x=0.3201, y=0.3749), which was close to the NTSC standard values for white (x=0.333, y=0.333). All the results suggested that the YPO4-based Ce3+/Tb3+ co-doped glass ceramics could act as potential luminescent materials for white light-emitting diodes.