Sol–gel synthesis, characterization and luminescent properties of Tb3+ doped MLa2O4 (M = Sr or Ba) nanophosphors

Tb3+ doped SrLa2O4 and BaLa2O4 nanophosphors were successfully synthesized via tartaric acid assisted sol–gel method and their luminescent properties were investigated. The crystal structure and morphology of SrLa2O4:Tb3+ and BaLa2O4:Tb3+ was studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Thermal decomposition behavior of the dried gels was investigated by thermogravimetry (TG) and differential thermal analysis (TGA). Photoluminescence (PL) behaviors of these nanophosphors were checked by the excitation and emission spectra. These SrLa2O4 and BaLa2O4 nanophosphors displayed green color under a UV source due to characteristic transition of Tb3+ from 5D4 → 7F5 at 544 nm. The dependence of photoluminescence intensity on Tb3+ ion concentration, tartaric acid concentration and annealing temperature were also studied in detail. In addition, the optimum doping concentration and time-resolved luminescence spectroscopy were also investigated.