XANES characterization of Ce valence state in polycrystalline Lu2SiO5:Ce powders and Its VUV spectroscopic properties

The valence state of Ce in the polycrystalline Lu2SiO5:Ce(LSO:Ce) luminescent powders was characterized by X-ray absorption near edge structure (XANES) spectra. The result demonstrates that Ce3+ contents relative to Ce in the LSO:Ce powders with different Ce-doped concentration are only 18%~39%. Annealed at 1 000℃ for 2 h in a flowing hydrogen atmosphere, the relative Ce3+ content of LSO:0.5%Ce powder increases significantly to 83% from 39%. The emission spectra excited by vacuum ultra violet (VUV) suggest that the luminescence intensity of LSO:Ce with Ce mole fraction from 0.25% to 1% is correlated closely with Ce3+ content in the powders. The luminescence intensity of LSO:0.5%Ce increases about 40% by annealing in a flowing hydrogen atmosphere. The emission intensity is very stable at different temperatures (50~250 K) without thermal quenching effect observing.