Structure and photoluminescence properties of Er3＋-doped TiO2-SiO2 powders prepared by sol-gel method

Er3＋-doped TiO2-SiO2 powders are prepared by the sol-gel method, and they are characterized by high resolution transmission electron microscopy （HR-TEM）, X-ray diffraction （XRD） spectra, and Raman spectra of the samples. It is shown that the TiO2 nanocrystals are surrounded by an SiO2 glass matrix. The photoluminescence （PL） spectra are recorded at room temperature. A strong green luminescence and less intense red emission are observed in the samples when they are excited at 325 nm. The intensity of the emission, which is related to the defect states, is strongest at the annealing temperature of 800℃. The PL intensity of Er3＋ ions increases with increasing Ti/Si ratio due to energy transfer between nano-TiO2 particles and Er3＋ ions.