Near infrared long-persistent phosphorescence in La₃Ga ₅GeO₁₄:Cr³⁺ phosphor

Near infrared (NIR; 660?1300 nm) long-persistent phosphorescence from Cr3+ ions with persistence time of more than 1 hour was realized in La ₃Ga₅GeO₁₄:Cr³⁺ phosphor (with or without co-dopants such as Li⁺, Zn²⁺, Ca²⁺, Mg²⁺ and Dy³⁺). The NIR phosphorescence can be effectively achieved under UV illumination (∼240?360 nm) but is barely achieved by blue light (∼480 nm) irradiation, even though the blue light excitation are effective to the NIR fluorescence. The NIR phosphorescence mechanisms were discussed by measuring the irradiation energy dependence of the phosphorescence intensity.