Structure and luminescence properties of Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ green phosphor with zero-thermal quenching of Tb3+ for WLEDs
In this paper, novel green-emitting Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ phosphor with zero-thermal quenching of Tb3+ had been prepared and investigated. X-ray diffraction together with Rietveld structure refinement was employed to give an insight into the structure of samples. Verified by the luminescence spectra at 300 K and 80 K, the Ce3+ ions in Sr4Gd3Na3(PO4)6F2:Ce3+ were distributed randomly in the cation sites and gave intense emission. Utilizing the Ce3+→Tb3+ energy transfer, intense green emitting Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ had been obtained. The energy migration mechanism of Ce3+ in Sr4Gd3Na3(PO4)6F2:Ce3+ as well as energy transfer mechanism of Ce3+→Tb3+ in Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ were determined by the analysis of photoluminescence spectra and decay curves. The Sr4Gd3Na3(PO4)6F2:Ce3+,Tb3+ exhibited a substantial thermal-induced enhancement of Tb3+ emission in 25-300ºC, indicating an excellent thermal stability. Moreover, utilizing our prepared Sr4Gd3Na3(PO4)6F2:0.06Ce3+,0.15Tb3+ phosphor, green and white emitting LED devices had been fabricated. Our investigation indicated the potential application of prepared green phosphor in UV WLEDs and the feasible method to explore high thermal stable phosphors utilizing the high thermal stability of donors together with energy transfer from donors to acceptors.