Effect of annealing temperature and doping concentrations on structure and optical properties of Eu3+-doped TiO2 nanomaterials

In this study, we successfully synthesized europium-doped TiO2 (TiO2:Eu3+) nanomaterials (NMs) with crystalline sizes ranging from 6.5 to 71.7 nm through a sol-gel method. Analysis of X-ray diffraction (XRD) patterns and ultraviolet-visible (UV-Vis) spectra indicates that the substitution of smaller-sized Ti4+ ions (0.745 Å) by larger-sized Eu3+ ions (0.947 Å) was more efficient at higher doping concentrations and annealing temperatures. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the synthesized TiO2:7%Eu3+NMs exhibit a strong red emission band peaking at 613 nm and remarkable absorption in the blue light region centered at 463 nm, making them suitable for use in white light-emitting diode (WLED) applications. Our findings reveal that both annealing temperature and doping concentration significantly influence the structure and properties of these materials. Besides, the research team has seen, under the experimental conditions, the TiO2:7%Eu3+ sample annealed at 800°C exhibits the highest PL intensity. These results underscore the potential of the synthesized TiO2:Eu3+ NMs as red-emitting materials for WLED applications.