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.