Concentration quenching of praseodymium ions Pr3+ in BaGd2(MoO4)4 crystals
Abstract
The concentration effect on the photoluminescence (PL) of the praseodymium Pr3+ ion is studied at 298–12 K for barium gadolinium molybdate (BaGd2(MoO4)4, called BGM) crystals with a wide Pr3+ concentration range of 0.05–25.0 mol%. Three types of concentration dependences are observed for the emissions although all types show PL quenching at high concentrations. The first type (Type A) has the maximum PL intensity at about 10 mol% with a non-zero intensity at high concentrations, which is observed for the 3P0 emissions except for emission at 621 nm. The second and third types (Type B-1 and B-2) have the maximum at about 1 mol% with a finite residual intensity and nearly zero intensity at high concentrations, respectively, which are observed for the 621 nm emission and all the 1D2 emissions. It is suggested that the energy migration mechanism is responsible for Type A, while the non-resonant cross-relaxation is responsible for Type B-1 and the resonant cross-relaxation for Type B-2.