Synthesis and Characterization of Titania Nanoparticles by Sol-gel Technique

Ever increasing interest in titania nanoparticles arises due to its applications as photo catalyst and as a window layer in photovoltaics. Titania exists in three important crystallographic phases namely rutile, anatase and brookite. Among these phases rutile is the most stable phase of titania. In order to study the effect of pH on titania nanoparticles we here report sol-gel assisted synthesis of titania nanoparticles using TiCl4 precursor. Ammonia was used to vary the pH of sol from 1 to 11. XRD results show amorphous nature of nanoparticles at low pH (1). While increasing the pH to 3 results in formation of highly crystalline rutile phase titania nanoparticles. Crystallite size decreases as pH is increased to 7 while increasing the pH in basic medium results in increase in crystallite size. Nanoparticles prepared with pH 1 show high transmission >87% in the visible and infrared region. Band gap values lies in the range of 2.87-3.05 eV. High refractive index (2.5-2.8) and low values of extinction coefficient makes these nanoparticles a promising candidate for their applications.