Energy transfer and luminescence studies of Pr 3+, Yb 3+ co-doped lead borate glass

Lead borate glass samples doped with the tripositive lanthanide ions Pr ³⁺ and Yb ³⁺ were synthesized by the conventional melting-quenching method. The luminescence properties and energy transfer process from Pr ³⁺ to Yb ³⁺ were investigated. Upon ultraviolet excitation, the room temperature luminescence decay curve of a sample containing only a low concentration of Pr ³⁺ exhibited monoexponential decay from ¹D ₂ with the lifetime 37 μs, without emission from ³P ₀. The room temperature Pr ³⁺ emission intensity decreased with the increase of Yb ³⁺ mole ratio in the glass. Under the excitation of 454.5 nm at 10 K, 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 Pr ³⁺ and Yb ³⁺ ions, respectively. The decay curves of the ¹D ₂ emission from Pr ³⁺ with addition of Yb ³⁺ in lead borate glass show non-monoexponential character, and are best described by a stretched exponential function. The average ¹D ₂ decay time decreases considerably with the addition of Yb ³⁺ in the glass. Decay curve fitting using a modified Inokuti-Hirayama expression indicates dipole-dipole energy transfer from Pr ³⁺ to Yb ³⁺, 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. © 2011 Elsevier B.V. All rights reserved.