White-light long persistent luminescence of Tb3+-doped Y3Al2Ga3O12 phosphor

A novel white long persistent phosphor of Y3Al2Ga3O12:Tb3+ was prepared by the soft chemical method. Y3Al2Ga3O12:Tb3+ presented a white long persistent luminescence when the doping concentration of Tb3+ was just 0.1% and the afterglow time was able to last more than 2 h. The persistent emission of Tb3+ in Y3Al2Ga3O12 consisted of all color emissions in the visible spectrum from an identical luminescent center (Tb3+); meanwhile, the white-light color won't vary as the afterglow time goes on. The mystery behind this phenomenon was studied deeply including trap depths, distribution and types. The trap depths was calculated from 0.65 to 1.15 eV by the initial rise method analysis, highly corresponding to the ideal energy for trapping and releasing at room temperature. What's more, the estimated trap structure was proved to be a continuous trap distribution by varying the thermal cleaning temperature. The persistent luminescence mechanism of Y3Al2Ga3O12:Tb3+ was illustrated and discussed in detail on the basis of the experimental results. This work provides a promising approach for the development of white long persistent phosphor.