The origin of two quenching concentrations and unusual afterglow behaviors of Ba2SnO4:Sm3+ phosphor

In order to interpret the origin of two emission quenching concentrations and a sharp increase of afterglow at certain Sm3+ doping concentration in Ba2SnO4:Sm3+ phosphor, the Eu3+ is used as a probe and it reveals that the Sm3+ ions occupy Sn4+ sites at low Sm3+ concentration and then the Ba2+ sites at a high concentration. The Sm3+ centers at different sites lead to two quenching processes and the two quenching concentrations effect. The thermoluminescence reveals that the substitution of Sm3+ for Ba2+ sites will induce a large amount of shallow hole traps and it should be mainly responsible for the sharp enhancement of the afterglow. (C) 2012 Elsevier B.V. All rights reserved.