Effect of Flux Addition on the Luminescence Performance of Ca_0.5Gd_1−x(MoO₄)₂:xEu³⁺ Phosphor: Judd–Ofelt Investigation

In the present work, the effect of the addition of NaCl as a flux on the luminescence properties of the Ca_0.5Gd(MoO₄)₂ phosphor doped with different concentrations of Eu³⁺ (0.04, 0.08, 0.12, 0.16, and 0.20 mol.) was investigated. The powder x-ray diffraction (XRD) patterns show that the synthesized materials possess a scheelite-type crystal structure with a tetragonal phase. The mean particle size estimated from the scanning electron microscopy (SEM) analysis is 6.6 μm, and the energy-dispersive x-ray analysis (EDX) confirms the presence of Ca, Gd, Mo, O, Eu, and Na elements. The photoluminescence (PL) properties of Ca_0.5Gd(MoO₄)₂:Eu³⁺, Na⁺ phosphor indicate bright red emission in the visible light region due to the characteristic ⁵D_0→⁷F₂ transition. More importantly, the phosphor Ca_0.5Gd(MoO₄)₂:Eu³⁺, when added with sodium chloride as a flux, exhibits enhanced luminescence. Investigations into the photophysical characteristics and quantum efficiencies of the synthesized phosphors have been carried out with the help of Judd–Ofelt theory.