Long-lasting luminescence in ZnGa2O4: Cr3+ through persistent energy transfer

Cr[Formula: see text]-doped zinc gallate (ZnGa 2 O 4 ) near-infrared (NIR) phosphors were synthesized via a high temperature solid state method. The luminescence properties of the phosphors were studied systematically. A significant spectra overlap between the emission of ZnGa 2 O 4 and the absorption of Cr[Formula: see text] was observed and 300 nm excitation exhibited the most excellent long-lasting luminescence properties among the three main excitation bands. Luminescence intensity was changed with the ratio of Ga[Formula: see text]/Cr[Formula: see text] and the blue host emission of ZnGa 2 O 4 was suppressed when doping Cr[Formula: see text] into ZnGa 2 O 4 . The fluorescence decay curves of blue emission of ZnGa 2 O 4 with different Cr[Formula: see text] doping concentrations indicated that the lifetime of ZnGa 2 O 4 at 505 nm become shorter with the increase of the Cr[Formula: see text] concentration. Herein, a possible mechanism of long-lasting luminescence in ZnGa 2 O 4 : Cr[Formula: see text] was proposed that the NIR long-lasting luminescence in ZnGa 2 O 4 : Cr[Formula: see text] comes from the persistent energy transfer from ZnGa 2 O 4 to Cr[Formula: see text].