Inhibitory Effect of Increasing Milling Time on Anatase to Rutile Phase Transformation of Mecanochemically Synthesized Titania Nanoparticles

Mechanochemical processing of TiOSO₄ precursor has been used to produce nanocrystalline powders of titania (TiO₂). This process involves high energy ball milling of precursor with NaCl as diluent phase and post heat treatment of as-milled powder. Subsequent washing with distilled water was then used to recover a nanocrystalline titania by removing the sodium chloride salt matrix which effectively seprated the titania powder particles during heat treatment and washing stages. The effect of milling time on TiO₂ nanocrystalline size and anatase to rutile transformation (A→R) was investigated. Characterization of the powder was performed by Thermograviometric Analysis (TGA), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Experimental results show that increasing the milling time can effectively reduce the nanocrystalline size of TiO₂ and inhibit A→R. Also it was found that particles have equiaxed morphology with the crystallite size in rang of 5-28 nm and narrow particle size distribution.