X-ray Absorption Fine Structure Analysis of Valence State of Ce in Polycrystalline Ce:LuAG Films

Ce³⁺ doped lutetium aluminum garnet (Ce:Lu₃Al5₅O₁₂/Ce:LuAG) Polycrystalline scintillation films have been fabricated on silicon (111) substrates by Pechini sol-gel method combined with spin-coating technique. Photoluminescence (PL) spectra and X-ray absorption fine structure (XAFS) analysis were used to characterize the as-prepared films. X-ray absorption near-edge structure (XANES) spectra of the Ce-L₃ edge demonstrated that the Ce ion in Ce:LuAG films synthesized in air exhibited two charge states, +3 and +4 valence respectively. By post annealing in H₂ atmosphere, the relative content of Ce³⁺ ions increased from 46.3% to 80.5% for 1.0 mol%Ce:LuAG films, which corresponded with the enhancement of luminescence intensity of this samples.