Cracking and orientation of solution-deposited rutile TiO2 films

In this study, c-axis oriented rutile phase TiO2 films were deposited at 60 degreesC on silica glass substrates from acidic TiCl4 aqueous solutions. X-ray diffraction and scanning electron microscopy showed that oriented film growth was the result of a combination of preferential growth of the primary crystallites and a geometrical constraint imposed on agglomerating crystallites. It was also observed that the film cracked during drying. The severity of cracking was reduced when the wash solvent was changed from water to methanol. As methanol has a lower surface tension, this indicated that film cracking was due to the high capillary stresses generated during drying and also meant that the film contained nanosized pores.