Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

Abstract: Nanosized cerium-doped lutetium aluminum garnet (LuAG:Ce) phosphors were prepared by nitrate-citrate sol-gel combustion process using 1:1 ratio of the citrate:nitrate. The prepared LuAG:Ce phosphors were characterzed by XRD, TEM, photoluminescence and radio luminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG:Ce was obtained at 900 °C by directly crystallizing from amorphous materials. The resultant Lu-AG:Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 nm. Both photoluminescence and radioluminescence were well-known Ce³⁺ emissions located in the range of 470 ∼ 600 nm consisting of two emission bands because of the transition from the lowest 5d excited state (²D) to the 4f ground state of Ce^3-, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.