Influence of sintering temperature and Eu³⁺ concentration on the structural, optical, and Judd-Ofelt parameters of...

In this study, we synthesized Eu³⁺-doped CaY₂O₄ materials using a solid-phase reaction method, with sintering temperatures ranging from 1000 to 1300 °C and Eu³⁺ concentrations ranging from 0 to 6%. SEM, XRD, Raman, FTIR, EDX, XPS, PL, and PLE measurements were used to examine the surface morphology, structure, microstructure, elemental ratios, surface ionic bonding, and optical properties of the materials. The results show that the fabricated materials have an orthorhombic structure in the Cmcm space group (No. 63), with the highest crystallinity achieved at 1200 °C. As the sintering temperature increased from 1000 to 1200 °C, particle size increased from 100 nm to 800 nm, and aggregation into larger particles began at 1300 °C. At the same time, the crystal size decreased from 49.53 nm to 37.00 nm, corresponding to an increase in the Eu³⁺ concentration from 2% to 6%. Optical property analysis indicated that the material exhibits strong absorption in the ultraviolet and near-ultraviolet regions, resulting in intense red emission with characteristic Eu³⁺ ion lines during transitions from the excited state ⁵D₀ to the ⁷F _j states. Concentration-induced fluorescence quenching was also detected at 5% Eu³⁺ concentration. The analysis suggests that this material is suitable for applications as a color display material and as a red-emitting component in white LEDs.