Cr3+ doping optimization in CaAl2O4:Eu2+ blue phosphor

A new composition of phosphor material CaAl2O4:Eu2+ co-doped with Cr3+ was investigated. Various compositions with Eu2+ (1 and 2 mol%) and Cr3+ (0.05–0.1 mol%) were prepared by solid-state reaction method. These compositions show high brightness and longer persistent luminescence. Phase and crystallinity were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Excitation and emission spectra were taken to investigate the luminescence characteristics. Broad band UV excited luminescence of the CaAl2O4:Eu2+, Cr3+ was observed in the blue region (λmax = 440 nm) due to transitions from 4f65d1 to the 4f7 configuration of the Eu2+ ion. Cr3+ ion co-doping generates deep traps which results in longer afterglow phosphorescence compared to parent phosphor.