Influence of Bi₂O₃ co-doping on Cr-doped ZnGa₂O₄ red persistent phosphors synthesized by a liquid phase precursor process

The long persistence luminescent property of Cr-doped ZnG₂O₄ phosphor in the deep red/near-infrared region has been of great interest for the purpose of in vivo bioimaging application. Improving the optical property and afterglow lifetime of this material remain challenging. The microcrystalline cellulose assisted liquid phase precursor process was developed for the synthesis of high-quality ZnGa₂O₄ phosphors, which process enables uniform distribution of the dopant and co-dopant. In this paper, the co-doping of Bi enhanced the photoluminescence intensity by about 2.5 times, while significantly improving the long afterglow property. Investigation of the influence of the Bi addition indicated that the co-doping Bi not only serves to purify Cr ions in ZnGa₂O₄, but also brings about the growth of particles and changes in morphology through the role of flux.