Color tunable phosphorescence in KY3F10:Tb3+ for x-ray or cathode-ray tubes

We report a persistent phosphor of KY3(1-x)Tb3xF10 (KY3F10:xTb(3+)) synthesized by solid-state reaction for x-ray or cathode-ray tubes. The phosphorescence consists of a group of blue and green emission lines originating from D-5(3)-> F-7(J) and D-5(4)-> F-7(J) transitions of Tb3+, respectively. The phosphorescent emitting color can be tuned from blue to green by gradually increasing Tb3+ concentrations, which is attributed to the enhanced D-5(3)-D-5(4) relaxation through the cross relaxation between two Tb3+ ions, as described by of (D-5(3),F-7(6))-(D-5(4),F-7(0)). The Tb3+ concentration dependent phosphorescence spectra are well simulated based on the analysis of luminescence dynamical processes using the Judd-Ofelt theory and rate equations concerning the D-5(3) and D-5(4) levels. The energy charge and release pattern of the phosphor are presented and a 10% decay time is 29 s. The measurement of the thermoluminescence glow curve gives convincing evidence for the traps analysis.