A study of temperature induced phase transformations in Cobalt doped titanium dioxide thin films

Co (III) doped titanium dioxide (Ti1- xCoxO2) thin films with different Co volume ratios (x = 0.0, 0.05, 0.1, 0.15, 0.2) were successfully deposited using Sol-Gel route. X-ray Diffraction patterns revealed that the films were deposited with amorphous, anatase and rutile phases. These phases strongly influenced by annealing temperatures and doping profiles. By annealing at 500°C, the structure has changed from amorphous to the anatase crystalline state. The phase transformation from anatase to rutile was observed in the temperature range 600-700°C. However, with the doping of Co resulted in extended phase transformation temperature upto 700 °C. The lattice constants `a' and `c' were calculated from TiO2 (200), TiO2 (101) peaks and grain size using the Scherrer's formula for TiO2 (101) peak and these parameters increased with increasing the annealing temperature.