A new yellow long persistent luminescence phosphor Ca2Al2SiO7:Eu2+,Tm3+ found by co-doping Ln3+ (Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) with Eu2+ in Ca2Al2SiO7 host

A series of Eu2+ doped Ca2Al2SiO7 (CASO) phosphors with or without Ln3+ (Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) co-dopant in the host were synthesized by solid-state reaction method in order to obtain long persistent luminescence (LPL). Their structural and photoluminescent properties were investigated by X-ray powder diffraction (XRD) and photoluminescence emission (PL) and excitation (PLE) spectra in detail. Meanwhile, the decay curve measurements were performed on those phosphors to study their afterglow properties. Among them, the Ca2Al2SiO7:Eu2+,Tm3+ (CASO:Eu,Tm) phosphor yielded a bright LPL in the yellow region with afterglow duration much longer than those of other samples. Its luminescence can be observed by human eye for more than 2 h after shutting down the 365 nm excitation source. Further thermoluminescence (TL) study on CASO:Eu,Tm phosphor indicated that the introduced Tm3+ ions indeed increased substantially the amount of charge carrier traps. A possible explanation were given to illustrate the LPL mechanism of CASO:Eu,Tm based on the experimental results. This work suggests that CASO:Eu,Tm phosphor is a promising yellow-emitting LPL phosphor.