Green emission from Tb3+-doped CaLaAl3O7 phosphor - A photoluminescence study

A series of Tb3+-doped CaLaAl3O7 phosphors were successfully synthesized via a sol-gel method. The formation of the synthesized phosphors was confirmed using X-ray powder diffraction (XRPD) studies. A scanning electron microscope (SEM) was used to characterize the surface morphology and to investigate the photoluminescence behaviors in detail. Under the excitation of 235 nm, the emission spectrum consists of the characteristic Tb3+ transitions that mainly peak at 543 nm and correspond to the 5D4 → 7F5 transition. The intensity was greatly improved due to the Tb3+ concentration in the present phosphors. The optimum Tb3+-doping concentration was determined to be 0.05 mol. The chromaticity coordinates of the CaLaAl3O7:Tb3+ were fixed to make it tunable for the blue-to-green region. The typical photographs of the CaLaAl3O7:Tb3+ under a 254-nm UV light revealed an intense-green powder. The results showed that this kind of phosphor is potentially applicable in terms of UV-excited white LEDs.