Synthesis and characterization of nanoestructured TiO2 anatase-phase powders obtained by the homogeneous precipitation method

Titanium dioxide (TiO₂) nanoparticles were synthesized by the homogeneous precipitation method using titanium (IV) butoxide as Ti precursor. The solution was prepared by dissolving 26 ml of titanium (IV) butoxide in a mix of ethanol, glacial acetic acid, and sulfuric acid (53:43:4 ml, volume proportion), under constant magnetic stirring at 55 °C, until having a white precipitate. This precipitate was centrifuged, decanted, and finally dried at 100°C for two hours. The resultant product was thermally annealed at different temperatures and times, namely, 450, 550, 600, and 650 °C for 6, 12 and 24 h, respectively. Finally the powders were milled at 400 rpm in a planetary ball milling at different times, 2, 6 and 8 h. All powders were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). All the X-ray spectra confirmed the existence of anatase phase. From the XRD spectra, the crystallites size was estimated by using the Scherrer´s fomula, giving values in an interval of 18 to 22 nm. The SEM micrographs showed a uniform particle distribution, with a spherical shape. The particle size was measured by TEM and SEM, which oscillated from 20 to 35 nm.