Photochromism and white long-lasting persistent luminescence in Bi^3+-doped ZnGa_2O_4 ceramics

Abstract
White long-lasting persistent luminescence covering the whole visible region in Bi[3+]-doped ZnGa[2]O[4] ceramics is reported. The afterglow luminescence can be observed for several tens of minutes after 360 nm or 280 nm excitation. Photochromism is also observed during ultra-violet excitation. The persistent luminescence and photochromism are considered to originate from electron trapping by defect centers in the ZnGa[2]O[4] crystals. The Bi[3+]-doped ZnGa[2]O[4] ceramics are expected to be potential white-color afterglow phosphors