A facile particulate sol–gel route to synthesize nanostructured CoTiO₃ thin films and powders and their characteristics

Nanostructured CoTiO₃ thin films and powders were prepared by a straightforward aqueous particulate sol–gel route. Titanium(IV) isopropoxide and cobalt chloride were used as titanium and cobalt precursors, respectively. Also, hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. The effect of Co:Ti molar ratio and annealing temperature were studied on the crystallization behavior and chemical properties of the products. X-ray diffraction and Fourier transform infrared spectroscopy revealed that the powders crystallized at the low annealing temperature of 300 °C for 1 h, containing anatase-TiO₂, rutile-TiO₂, CoTiO₃ and Co₃O₄ phases, depending on annealing temperature and Co:Ti molar ratio. Furthermore, TiO₂ transformation from anatase to rutile phase occurred at 500 °C. The activation energy of crystallite growth was calculated in the range of 3.1–8.5 kJ/mol. Simultaneous differential thermal analysis showed that the final annealing temperature to obtain organic-free cobalt titanate powders could be determined at 560 °C. Field emission scanning electron microscope analysis revealed that the deposited thin films had crystallite and nanostructured morphology with the average grain size in the range 22–32 nm at 500 °C. Atomic force microscopy illustrated 2D and 3D topographies of thin films annealed at 500 °C for 1 h showed that the deposited films had homogeneous, rough structure with nanosized grains.