Synthesis and photoluminescence of green-emitting Ce3+,Tb3+ co-doped Al6Si2O13 phosphors with high thermal stability for white LEDs

In this article, novel green-emitting Ce3+,Tb3+ co-doped Al6Si2O13 phosphors have been successfully prepared by a high-temperature solid-state reaction method using Al2O3, SiO2, CeO2, and Tb4O7 powders as initial materials. Single-phased and good-crystallized phosphors have been obtained after calcining the mixed powders at 1470 °C under a weak reducing atmosphere. The average particle size of the as-synthesized phosphors is less than 20 μm. The optimized doping concentration of Tb3+ ion is determined to be 8 mol%. With Ce3+ co-doping as a sensitizer, the luminescence intensity of the Al6Si2O13:Ce3+/Tb3+ phosphors drastically improves as the Ce3+ doping concentration increases to 1.3 mol%. The Ce3+,Tb3+ co-doped Al6Si2O13 phosphors exhibit intense green emissions at 488, 541, 584, and 620 nm, which correspond to the characteristic level transition of 5D4-7F6, 5D4-7F5, 5D4-7F4, and 5D4-7F3 of Tb3+ ion, respectively. And Al6Si2O13:8%Tb3+,1.3%Ce3+ possesses a decay time of 31.4 ns, as well as a quantum yield of ∼45.7%. In addition, the solid-state synthesized Al6Si2O13:Ce3+/Tb3+ phosphor powders have comparable green luminescence properties and better thermal stability compared with available commercial green phosphors. In this regard, our target products, Al6Si2O13:Ce3+/Tb3+, may potentially serve as green-emitting phosphors for UV-converted white LEDs.