Strong red-emission of Eu³⁺:Li₄Ti₅O₁₂ powders for phosphor applications

The synthesis and photoluminescence properties of trivalent europium doped lithium titanate (Eu³⁺:Li₄Ti₅O₁₂) with different Eu³⁺ concentrations (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) are reported and analyzed as a phosphor. Europium (III) nitrate (Eu(NO₃)₃) was employed as Eu³⁺ source, while lithium acetate dihydrate (CH₃COOLi·2H₂O) and titanium n-butoxide (Ti(OC₄H₉)₄) were adopted as raw materials to synthesize the host lithium titanate with a Li:Ti stoichiometry of 4.5:1. Phase identification was performed using X-ray diffraction (XRD), and morphology was examined using scanning electron microscopy (SEM). Eu³⁺:Li₄Ti₅O₁₂ powders showed strong red emission at 612 nm, corresponding to the ⁵D₀-⁷F₂ transition, with the strongest excitation peak observed in the blue light region at 464 nm. Decay time analyses revealed relatively short lifetimes accompanying typical exponential decay rates. The effect of Eu³⁺ concentration (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) on photoluminescence intensity and decay time was explored, and is reported here. It was determined that the CIE color coordinates (0.66, 0.34) of the doped Li₄Ti₅O₁₂ powders were independent of Eu³⁺ concentration, and that the coordinates are very similar to the ideal red chromaticity (0.67, 0.33) designated by the National Television Standard Committee (NTSC) system.