Structural and optical studies of milled anatase (TiO₂) powder

The studies of structural and optical properties of ball-milled titanium dioxide (TiO2) powders have been conducted. A commercial micron-anatase powder were prepared as raw powder. A size reduction via physical method by planetary ball-mill was conducted for 20 hours at a rotation speed of 150 rpm with a ratio 1.5 gram: 22 gram: 10 ml of anatase powder, ball and ethanol. The phase identification, lattice parameters and crystal size of the before and after milled anatase powders were analyzed by Rietveld method of X-ray diffraction (XRD) data using Match3!, Rietica and MAUD software. The functional group of the powders was determined by Fourier-transform infrared (FTIR) spectroscopy measurement. The absorbance and the band energy were observed using Ultraviolet-Visible (UV-Vis) spectroscopy. Phase studies revealed that there is no phase contained in the powder after the grinding process, the crystal lattice parameters tend to remain unchanged as well. Furthermore, crystal size of anatase decrease from 117 to 99 nm after milling process. The results of FTIR characterization showed the powders containing Ti‒O and O‒Ti‒O functional groups. Microstructural characteristics of the powders were revealed in scanning electron microscopy (SEM) images which showed that the particles in spherical shape. Two absorbance peaks at UV-Vis spectrum were obtained at 209 and 305 nm, and the band gap energy was 3.20 eV for the milled powders.