Effects of Flux on the Synthesis and the Luminescence of Lu3Al5O12:Ce3+ Phosphors

Ce3(+)doped Lu3Al5O12 (LuAG:Ce3+) powder was synthesized using a solid state reaction method in the presence of metal fluoride flux. AIF(3) flux was used alone and in combination with BaF2 and NaF. Crystallographic data were determined by Rietveld refinement. The photoluminescence (PL) excitation spectra consisted of strong and weak bands owing to the ground state doublet (F-2(7/2) and F-2(5/2)) of the Ce3+ ions. Asymmetrical emission spectra were observed in the green wavelength region, which resulted from two overlapping subbands that originated from the D-2 -> F-2(5/2), F-2(7/2) transitions of the Ce3+ ions. The addition of flux affected particle morphologies, crystal structures, and the incorporation of Ce3+ ions into the host lattice, leading to a change in PL properties. The emission intensity of powder synthesized using AIF(3) in combination with NaF was higher than that for powder synthesized using AIF(3) alone. A transition from a red- to blue-shift of the dominant emission wavelengths was observed. This behavior was explained by considering the change in the lattice constant and the incorporation of fluorine ions into the host lattice.