Effects of Nd 3+ co-doping on the long lasting phosphorescence and optically stimulated luminescence properties of green emitting NaBaScSi 2 O 7 :Eu 2+ phosphor

Green emitting NaBaScSi2O7:Eu2+/Eu2+, Nd3+ phosphors are prepared by a solid state reaction under a reductive atmosphere. The introduction of Nd3+ ion, which acts as trap center, largely extends the thermoluminescence characteristics and evidently enhances the long lasting phosphorescence and optically stimulated luminescence properties of the phosphors. The persistent green emission of the co-doped phosphor can last for about five and a half hours above recognizable intensity level (>= 0.32 mcd/m(2)). According to the analysis of thermoluminescence characteristics, it is concluded that the shallow T-1(') traps with a continuous trap depth distribution are exactly the traps that lead to the long lasting phosphorescence and other three kinds of deep traps, i.e., T-2('), T-3(') and T-4('), corresponding to a separated trap depth distribution, should mainly contribute to the optically stimulated luminescence performance. Finally, a possible mechanism for the optical phenomenon is proposed. (C) 2016 Elsevier Ltd. All rights reserved.