Influence of crystallization on the luminescence characteristics of Pr ³⁺ ions in PbO-Sb₂O₃-B₂O₃ glass system

PbO-Sb₂O₃-B₂O₃ glasses mixed with different concentrations of Pr₂O₃ (ranging from 0 to 0.6 mol%) were crystallized. The samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy techniques. The XRD studies have revealed the presence of Pb₅Sb₂O₈, Pb ₃(SbO₄)₂, PbB₄O₇, β-PrSbO₄, Pr₃SbO₇, and Pr ₃Sb₅O₁₂ crystalline phases. Optical absorption (in the visible and NIR regions) and fluorescence spectra of these samples have been recorded at room temperature. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of Pr ³⁺ ions in these samples. From the luminescence spectra, various radiative properties like transition probability A, branching ratio β_r, and the radiative lifetime τ_r for various emission levels originating from the ³P₀ level of Pr ³⁺ ion in the glasses glass ceramic samples have been evaluated. The radiative lifetime of the ³P₀→³H ₆ transition is measured and the quantum efficiency has been estimated. The crystallization causes to improve the luminescence efficiency to a large extent. The changes observed in the radiative properties due to crystallization have been discussed in the light of varying co-ordinations of antimony ions in the glass network.