Spectroscopic properties of nano-sized cerium-doped lutetium aluminum garnet phosphors via sol-gel combustion process

Nano-sized cerium-doped lutetium aluminum garnet (LuAG:Ce) phosphors were prepared via a sol-gel combustion process from a mixed aqueous solution of metal nitrates, using glycine as a fuel. The prepared LuAG:Ce phosphors were characterized by XRD, EPMA, and TEM, respectively. The spectroscopic properties of the phosphors were investigated. The as-prepared phosphors are agglomerated with a primary particle size of about 30 nm and have a foamy-like morphology. The pure crystalline LuAG:Ce with uniform size of 40 nm was obtained after calcined at 1000 °C for 2 h. The excitation spectrum shows two bands localized at 350 and 450 nm due to transitions from the 4f ground state to the excited 5d band. Both the photoluminescence excited by UV and the radioluminescence excited by X-ray show the same two emission bands, corresponding to transitions from the lowest 5d excited state (²D) to the 4f ground state of Ce³⁺ (²F_5/2,²F_7/2).