Energy transfer and luminescence studies of Pr3+, Yb3+ co-doped lead borate glass

Lead borate glass samples doped with the tripositive lanthanide ions Pr3+ and Yb3+ were synthesized by the conventional melting-quenching method. The luminescence properties and energy transfer process from Pr3+ to Yb3+ were investigated. Upon ultraviolet excitation, the room temperature luminescence decay curve of a sample containing only a low concentration of Pr3+ exhibited monoexponential decay from D-1(2) with the lifetime 37 mu s, without emission from P-3(0). The room temperature Pr3+ emission intensity decreased with the increase of Vb(3+) mole ratio in the glass. Under the excitation of 454.5 nm at 10K, a broad red emission band centered at 605 nm, and an NIR emission band at 995 nm were observed in the co-doped lead borate glass, originating from Pr3+ and Yb3+ ions, respectively. The decay curves of the D-1(2) emission from Pr3+ with addition of Yb3+ in lead borate glass show non-monoexponential character, and are best described by a stretched exponential function. The average D-1(2) decay time decreases considerably with the addition of Yb3+ in the glass. Decay curve fitting using a modified Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Pr3+ to Yb3+, which is consistent with the expected cross-relaxation scheme. There is a good agreement of the estimated overall energy transfer efficiency obtained from the integrals under the normalized decay curves, or from the lifetimes fitted by the stretched exponential function, or from the average decay times. (C) 2011 Elsevier B.V. All rights reserved.