A novel synthesis route to monodisperse Na5Lu9F32:Tb3+ phosphors with superior thermal stability

Abstract Nanocrystalline Tb3+-doped Na5Lu9F32 powders were prepared by a facile and environmentally-friendly hydrothermal process for the first time. Upon excitation at 368 nm, the Na5Lu9F32:Tb3+ nanocrystals show the characteristic f-f emissions and gives strong green emission. Furthermore, the optimum doping concentration of the Tb3+ is 7 mol% and its lifetime value is 10.227 ms. Compared with the strong absorbed exciting radiation (at 368 nm), the weak absorbed exciting radiation (at 317 nm) can be used to explore the mechanism of concentration quenching and the concentration quenching was demonstrated to occur among nearest-neighbor ions. The temperature-dependent PL spectra suggested that the products possessed good thermal stability and the activation energy was found to be 0.14 eV. These results show this green-emitting phosphors material may have potential applications in w-LEDs.