A novel near infrared long-persistent phosphor La2MgGeO6:Cr3+, RE3+(RE = Dy, Sm)

A novel near infrared long-persistent phosphor La2MgGeO6:Cr3+ was successfully prepared. Near infrared emission originates from the E-2 ->(4)A(2) transition of Cr3+ in strong crystal field. Due to the electric dipole-dipole interaction, the luminescence quenches when doping concentration of Cr3+ beyond 0.003. By co-doping Dy3+ and Sin(3+), the long-persistent luminescence intensity is significantly enhanced, and the long-persistent luminescence time is also prolonged. The results of the thermoluminescence measurement show that there are two kinds of traps in La2MgGeO6:Cr3+ phosphors. The depths of two traps were calculated to be 0.796 and 1.200 eV, respectively. The co-doping of Sm3+ and Dy3+ has a great influence on deep traps and has little effect on shallow traps. The present investigation has important guiding significance for a deep understanding of the nature of traps, which has an important influence on the long-persistent luminescence of the phosphors.