Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl2O4:Eu2+, R3+ (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R3+ ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl2O4:Eu2+. The greatly improved LPL performance was observed in Nd3+ co-doped samples, which indicates that the incorporation of Nd3+ creates suitable traps for LPL. While co-doping Tm3+ ions, the intensity of high temperature of thermoluminescence band in CaAl2O4:Eu2+ phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R3+ ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl2O4:Eu2+, R3+ exhibits different read-in/read-out performance as well. OSL emission spectra of Ca0.995Al2O4:0.0025Eu2+, 0.0025R3+ (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100s). Inset: Blue emission pictures under varying stimulation time. [Display omitted] •The LPL and OSL properties of CaAl2O4:Eu2+, R3+ were investigated.•An alternative approach to control the trap depth of CaAl2O4:Eu2+ phosphor was proposed.•A new oxide ETM phosphor exhibiting intense and stable OSL was explored.