Photoluminescence and thermally stimulated luminescence properties of Pr³⁺-doped zinc sodium bismuth borate glasses

Present study reports the effects of varying concentrations of Pr³⁺ ions on the optical properties of 10ZnO-5Na₂CO₃-10Bi₂O₃-75-xB₂O₃-xPr₆O₁₁ (x = 0.1–1 mol%) glasses prepared through melt-quench technique with an aim to achieve suitable optical gain medium for optoelectronic applications. Minimal changes in the measured density, X-Ray diffractogram and Fourier Transform Infrared spectra of the prepared samples confirmed the stability of the glass structure even after 1 mol% doping of the Pr³⁺. Bonding nature of Pr³⁺ ion with surrounding ligands and Judd-Oflet (J-O) intensity parameters of the glasses were determined using optical absorption spectra. The photoemission spectra exhibited reddish orange emission around 605 nm at 445 nm excitation. The calculated color chromaticity with x = 0.5847, y = 0.3701 coordinates for 0.1 mol% of the Pr³⁺ in the glasses suggests suitable optical gain medium for reddish orange LED applications. Metastable lifetimes of the Pr³⁺ ion were found-out by exponential fitting to the decay profiles. Lasing parameters of the glasses such as branching ratio, radiative transition probability and stimulated emission cross-section of ¹D₂→³H₄ transition were calculated using JO parameters indicating 0.1 mol% Pr³⁺-doped glasses suitable for 605 nm solid-state laser applications. The mechanism of energy transfer is determined by applying the Inokuti-Hirayama model and was found to involve a dipole-dipole type of interactions. Thermoluminescence (TL) glow curves of the gamma-ray treated 0.1 mol% Pr³⁺-doped zinc sodium bismuth borate glasses were de-convoluted using Computerized Glow Curve Deconvolution method to evaluate the energy storage properties of the glasses. The intensity variation of the TL component peak (CP2) at 500 K showed linear behavior up to 3 kG y suggesting application in high dose measurements.