Compositional-dependent properties of Pr³⁺-doped multicomponent fluoro-phosphate glasses for visible applications: a photoluminescence study

Five fluoro-phosphate (FP) glasses of different compositions, 49.5P₂O₅–10AlF₃–10BaF₂–10SrF₂–10PbO–10M (M = Li₂O, Na₂O, K₂O, ZnO, and Bi₂O₃), doped with 0.5 mol% praseodymium were prepared by melt quenching technique. For these glass matrices, structural, thermal, dielectric, electrical, and optical properties have been studied. The structures are characterized by XRD, Fourier transform infrared, Raman spectroscopy, and solid-state ³¹P and ²⁷Al magic angle spinning nuclear magnetic resonance techniques. The chemical and electronic states of these glass materials are characterized by X-ray photoelectron spectroscopy. The thermal stability for the host glass matrix is estimated from differential scanning calorimetry technique. From the impedance spectroscopy, various parameters, viz. electrical conductivity, dielectric constant (ε′), and dielectric losses (tan δ), at various frequencies and temperatures have been measured. X-ray absorption near-edge spectroscopy was used to study the electronic structure of praseodymium in the host glass matrices. By analyzing the absorption spectra with Judd–Ofelt theory, three intensity parameters (Ω _λ , λ = 2, 4, 6) are obtained. In turn, these parameters are used to calculate radiative properties such as emission probabilities (A _R), radiative lifetimes (τ _R), and integrated absorption cross sections (Σ) of different Pr³⁺ transitions. Luminescence parameters such as stimulated emission cross sections (σ _p) and branching ratios (β _exp) have been studied through photoluminescence spectra. Further, decay time constants are estimated from the decay profiles of Pr³⁺-doped different FP glasses.