Dy³⁺ ions in fluorophosphate glasses for luminescent white light applications

Abstract

In this study, a series of fluorophosphate (FP) glasses, activated with Dy3+ ions and displaying concentration dependence, have been prepared and analyzed for their suitability in luminescent white light applications. The melt quenching method was utilized to fabricate a set of FP glasses, doped with Dy3+ ions and possessing the composition of (60-x) P2O5+10MgO+10ZnO+10BiF3+10KF+xDy2O3, where x ranges from 0.1 to 2.0 mol%. The structural properties of the samples were analysed using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and Raman spectroscopy while the optical properties of the samples were studied using absorption and emission spectra. The amorphous nature of the FP glasses was confirmed through SEM analysis and XRD profiles. Moreover, the presence of elements in their composition was verified using EDX. The FTIR spectra of the FP glasses exhibited vibration bands consistent with the characteristic phosphate groups, which was further supported by Raman analysis. The absorption spectra were used to calculate oscillator strengths (fexp & fcal) and Judd-Ofelt parameters Ωλ (λ=2, 4, 6). The values of Ωλ (λ=2, 4, 6) followed this order: Ω6>Ω2>Ω4. The emission spectra displayed three prominent transitions in the UV-visible region: (4F9/2→ 6H15/2) blue, (4F9/2→ 6H13/2) yellow, and (4F9/2→ 6H11/2) red. The peak at 553 nm (4F9/2→ 6H13/2) was the most intense and dominant. Radiative characteristics were evaluated from the emission spectra through the employment of J-O intensity parameters and refractive indices. The Y/B intensity ratio values were greater than 1, indicating the high covalency of Dy3+ ions. The color coordinates (x, y) and correlated color temperature values of CIE 1931 were situated in the cool white region. The comprehensive analysis suggests that these glasses have the potential to become highly favorable candidates as luminescent components for solid-state white light emitting instruments.