Phase Transformation of TiO2 from Anatase to Rutile by Thermal Annealing and Swift Heavy Ion Irradiation

In the present study, we probe into the phase transition from anatase to rutile in nanocrystalline thin films under thermal annealing and swift heavy ion (SHI) irradiation. TiO2 thin films were prepared through chemical route using sol-gel and spin coating techniques on silicon (100) substrates. The structural studies of the annealed films were characterized by GAXRD and Raman spectroscopy. Though thermal annealing is known to cause transformation from anatase to rutile phase of TiO2 in a temperature interval of 700 to 900 C, in nanoparticle thin films, we found ∼35 vol% of anatase still remains even after annealing at 1000 C. SHI irradiation by 200 MeV Ag ions on the other hand resulted in complete conversion to rutile phase at fluence of 3x1012 ions.cm-2. SHI induced thermal spike seems to be responsible for conversion of anatase to rutile phase.