Enhanced Optical Properties of Eu₂O₃-Doped Zinc Borate Lanthanum Glasses with Gold Nanoparticle Integration

Gold nanoparticles embedded in sodium-zinc-borate-lanthanum glasses doped with Eu³⁺ ions were prepared employing the melt-quench process, and their structural, luminescent, and physical characteristics were investigated. The nucleation of nanoparticles (NPs) was controlled by modifying the gold nanoparticle (AuNP) concentration. The obtained gold nanoparticles existence, size, and shape were investigated by HR-TEM and SAED examination. The surface plasmon resonance (SPR) bands, which redshift the plasmon peak, have been identified in the 579–604 nm range, demonstrating the growth of AuNPs in the glass structure. Five prominent emission maxima have been detected in the luminosity spectra at 577, 591, 613, 651, and 700 nm; these correspond to the transition levels ⁵D₀ →⁷F₀, ⁷F₁, ⁷F₂, ⁷F₃, and ⁷F₄, respectively. The glass specimens bearing AuNPs possess intensity augmentation, which is ascribed to the AuNPs local field effect, while the energy transfer from Eu³⁺ to AuNPs causes quenching. Judd-Ofelt theory has been applied to identify and evaluate the intensity parameters associated with the radiative transitions inside the 4f configuration of Eu³⁺ ions. We explored intensity parameters (Ω₂ and Ω₄) as well as radiative attributes. The prepared glasses showed a pattern of Ω₂ > Ω₄, indicating an elevated symmetry environment surrounding Eu³⁺. In comparison with glasses without AuNPs, the photoluminescence intensity in glasses bearing AuNPs was doubled. Further, the 1931 CIE color chromaticity chart was employed to assess the current glasses appropriateness for solid-state lighting applications. The results presented in the manuscript revealed that when creating efficient glassy specimens for greater performance of luminescent materials interconnected between the SPR of AuNPs and Eu³⁺ luminescence, precursor evaluation, as well as selection, are crucial elements to consider.