Concentration-Dependent Fluorescence and Judd–Ofelt Analysis of Trivalent-Praseodymium-Doped Alkali Fluoroborate Glass

Abstract

The effects of different concentrations of Pr3+ ions on the optical properties of (70−x)B2O3 + 10BaO + 10K2O + 10ZnF2 + xPr6O11 (x = 0.02 mol.%, 0.03 mol.%, 0.05 mol.%, 0.1 mol.%, and 0.5 mol.%) glass prepared by the melt quenching technique have been studied. The structural and luminescence behavior of the prepared glasses were studied by x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, optical absorption spectroscopy, and photoluminescence excitation and emission spectroscopy. The XRD spectrum confirmed the amorphous nature while the FTIR spectrum revealed the presence of different structural groups in the prepared glass samples. The optical absorption spectrum was used to determine important parameters such as the nephelauxetic ratio, bonding parameter, optical bandgap energy, and Urbach energy. The PL spectra of the prepared glasses showed four prominent peaks at wavelengths of 484 nm, 601 nm, 693 nm, and 725 nm, related to the 3P0 → 3H4, 1D2 → 3H4, 3P0 → 3F3, and 3P0 → 3F4 transitions, respectively. Furthermore, the Judd–Ofelt (JO) intensity parameters Ωλ (λ = 2, 4, 6) and other important spectroscopic parameters such as the transition probability (A), radiative lifetime (τR), and branching ratio (βR) were calculated to evaluate the radiative properties of Pr3+levels from the optical absorption spectrum. In the host matrix, the JO parameters followed the trend Ω2 > Ω4 > Ω6. The emission spectra suggested that the prepared glass samples are excellent orange–red light-emitting materials under excitation at 442 nm (3H4 → 3P2). Quenching of the fluorescence intensity with increase of the Pr3+ concentration was also observed. The emission spectrum was used to determine the Commission Internationale de I’Eclairage (CIE) 1931 color coordinates. The results suggested the suitability of the prepared materials for various orange–red light-emitting applications, mainly in display devices, lasers, and optical amplifiers.