Color tunable phosphorescence in KY_3F_(10):Tb~(3+) for x-ray or cathode-ray tubes

摘要

We report a persistent phosphor of KY_(3(1-x))Tb_(3x)F_(10) (KY_3F_(10):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 ~5D_3→~7F_J and ~5D_4→~7F_J transitions of Tb~(3+), respectively. The phosphorescent emitting color can be tuned from blue to green by gradually increasing Tb~(3+) concentrations, which is attributed to the enhanced ~5D_(3~-)~5D_4 relaxation through the cross relaxation between two Tb~(3+) ions, as described by of (~5D_3,~7F_6)-(~5D_4,~7F_0). The Tb~(3+) 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 ~5D_3 and ~5D_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.