ZnGa2O4?:?Cr3+@Calcium Phosphate Nanocomposite with Near-Infrared Persistent Luminescence and High Stability

Persistent luminescence (PersL) is an optical phenomenon which allows for materials to emit luminescence after ceasing excitation. The long-lasting luminescence is ascribed to the presence of trap states, which can be exploited through the introduction of various dopants and post-synthesis treatment. In this study, ZnGa2O4 : Cr3+ (CZGO), one of the most widely investigated near-infrared-emitting PersL materials, is synthesized in the form of nanoparticles, and incorporated into amorphous calcium phosphate (ACP) to form a luminescent nanocomposite with drug attachment potential. The effects of annealing CZGO in the composite are comparatively studied alongside the composite that contains unannealed CZGO. We find that ACP with annealed CZGO exhibits much higher luminescence intensity and longer PersL duration. The formation of the nanocomposite also results in the redistribution of Zn, and its influence on the composite luminescence intensity and the long-term chemical stability are investigated.