Characterization of Luminescent Li₃Ba₂Gd₃Mo₈O₃₂:Tb³⁺ Phosphors Prepared via Sol–Gel Method

Luminescent Li₃Ba₂Gd₃Mo₈O₃₂:Tb³⁺ phosphors were synthesized using the sol–gel method, and extensively characterized through various spectroscopic techniques, including x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, photoluminescence (PL) excitation, and emission. SEM micrographs revealed the irregular and non-uniform morphology and size of the prepared phosphors. The FT-IR spectra offered insights into the functional groups and bonding within the phosphor. The PL excitation spectra at a 545 nm emission wavelength displayed a slight shift in peak positions with a prominent peak at 283 nm, corresponding to the characteristic 4f⁸ → 4f⁷5d¹ transitions of Tb³⁺ ions, while under excitation at λ_exc = 283 nm, PL emission spectra exhibited distinct peaks associated with ⁵D₄ → ⁷F_j (j = 6, 5, 4, 3) transitions. Notably, the transition ⁵D₄ → ⁷F₅ at 545 nm demonstrated strong and particularly high intensity in the Li₃Ba₂Gd₃Mo₈O₃₂:0.09Tb³⁺ phosphor. Photometric analysis showed the potential of this phosphor to serve as a vivid green light source for various display applications. The Li₃Ba₂Gd₃Mo₈O₃₂:Tb³⁺ phosphor may be used for creating sensors for environmental monitoring. Future research could explore its biocompatibility for biomedical applications and improve its targeting and photostability.