摘要
A 2% Gd 2 SiO 5 :Ce nanocrystalline sample was prepared by the sol-gel method at 1200°C, which is much lower than the usual calcination temperature of the solid-state reaction method. The sample was studied by X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS) and photo-luminescence spectroscopy. The crystal structure is of the monoclinic phase and the crystallite size is 22 nm. X-ray absorption near-edge structure (XANES) spectroscopy of the Ce-L III edge indicates that the Ce ion in Gd 2 SiO 5 :Ce has a +3 valence state. EXAFS shows that the coordination numbers of the Gd-O and Ce-O shells are 8.3 and 7.7, respectively. The bond lengths of the Gd-O and Ce-O shells are 2.46 and 2.32 Å, respectively. This suggests that Ce 3+ has entered the Gd 2 SiO 5 lattice and substituted Gd 3+ in two sites. The emission and excitation spectra show similar features to the bulk sample except for a small shift.