Effect of Cr on long-persistent luminescence of near-infrared phosphor Zn3Ga2Ge2O10:Cr3

The long persistent luminescence near-infrared (NIR) phosphors Zn3Ga2Ge2O10: x % Cr3+(x=0.1, 0.5, 2.5) were synthesized by solid-state reaction method. The microstructure and luminescence properties of the obtained samples were studied systemically. The results demonstrate that the luminescent intensity and afterglow time of the sample can be regulated by changing Cr3+ doping concentration and the calcine process. The afterglow mechanism of the samples were investigated and we found a method to balance the emission intensity and afterglow decay time. Specifically, Zn3Ga2Ge2O10: 2.5% Cr3+ samples show highest initial phosphorescence intensity but decay faster than other samples. Meanwhile, the host material obtained at 1300°C (with pre-sintering) can luminesce more than 40h after stoppage of the 365nm ultraviolet light irradiation. This new developed NIR long-persistent phosphor may have significant potential to be applied in many fields such as in vivo bio-imaging technology. •Long-lasting near-infrared (NIR) persistent phosphors were synthesized by solid state reaction method.•The persistence time lasts more than 30h.•Afterglow intensity of different samples is associated with afterglow time.•Changing Cr3+ concentration can greatly affect the afterglow time.•The mechanism of luminous of the new phosphor is explained in detail.