Luminescent properties of LuAG:Ce phosphors with different Ce contents prepared by a sol-gel combustion method

Nanosized LuAG:Ce phosphors with different Ce concentrations were prepared by the sol-gel combustion method. Phase evolution, morphology and luminescent properties of the obtained materials were characterized by XRD, TEM, photoluminescent and radioluminescent spectra excited by blue light and X-ray, respectively. The purified crystalline phase of LuAG:Ce was obtained at 820 °C by directly crystallizing from amorphous materials. Both the photoluminescence and radioluminescence are the well-known Ce emissions located in the 470-600 nm consisting of two emission bands due to the transitions from the lowest 5d excited state (²D) to the 4f ground state of Ce³⁺, which matches well with the sensitivity curve of the Si-photodiode. The luminescent intensity of LuAG:Ce phosphors varies with the Ce contents and reaches the maximum at 0.5 at.% doped. There is a little red shift for the main emission component from blue light-excited emission spectra to X-ray-excited ones. The luminescent intensity of LuAG:Ce phosphors increases with increasing the calcining temperatures due to the improved crystallization.