Structure and Raman Spectroscopy of Nanocrystalline TiO₂ Powder Derived by Sol-Gel Process

Nanocrystalline TiO₂ powder was prepared by sol-gel process. The structures of the as-prepared and the TiO₂ powder heat-treated at different temperatures were studied by thermogravimetric analyzer, differential thermal analysis, x-ray diffraction, and Raman spectra. As the powder was heat-treated at 350°C, it turned into tetragonal anatase structure. A structural transformation from anatase to rutile type occurred and the grains of the powder grew drastically when the powder was heat-treated at above 550°C. The structural transformation from anatase to rutile type completed at 750°C. The Raman spectra of TiO₂ nanocrystalline powder were also studied.