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摘要
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 degrees 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 degrees 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 degrees 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 degrees C. Atomic force microscopy illustrated 2D and 3D topographies of thin films annealed at 500 degrees C for 1 h showed that the deposited films had homogeneous, rough structure with nanosized grains.
- 出版日期2015-7
