Ultraviolet and visible persistent luminescence from Sr3MgSi2O8:Pr3+

In this paper, a low dose X-ray induced long afterglow luminescent phosphor Sr3MgSi2O8:Pr3+ has been reported. The structure analysis shows the as-prepared samples possess good crystallinity and the emitting center Pr3+ is more likely to occupy the lattice position of Sr2+ due to their similar ionic radius. And under 471.1 nm excitation, Sr3MgSi2O8:Pr3+ shows bright visible lights peaked at 545.5, 617.1 and 648.6 nm, respectively, corresponding to the transitions of 3P0 -> 3H5, 3P0 -> 3H6 and 3P0 -> 3F2 of Pr3+. After the X-ray irradiation, this phosphor shows strong ultraviolet C (291.7 nm), blue (493.2 nm) and red lights (617.1 nm). More important, only 5 s X-ray irradiation X-ray irradiation can easily charge Sr3MgSi2O8:Pr3+ to produce 5400 s afterglow emission. Even after 5400 s, its afterglow emissions still remain strong, which is about 20 times of the background intensity. The thermoluminescent results indicate that Sr3MgSi2O8 possesses a high absorption rate for X-rays and thus X-ray irradiation can excite the host to produce large number of electrons, Secondary electron, which would rapidly fill up the traps and thus produce excellent long afterglow luminescence. In addition, the existing suitable traps with 0.76 eV trap depth are also favorable for persistent luminescence at room temperature. Thus, Sr3MgSi2O8:Pr3+ is confirmed to be a very efficient low dose X-ray induced long afterglow luminescent phosphor.