Crack formation in TiO2 films prepared by sol-gel processing:: Quantification and characterization

TiO2 thin films were prepared by dip-coating from soluble precursor powders using different solvent mixtures. Under certain conditions cracking occurs during drying and thermal treatment. Both extent of damage and time of formation were evaluated from micrographs using image processing software. Different approaches for data evaluation are applied and compared. It is shown that reproducible measurements of defect densities are a useful tool for the optimization of process parameters. Data indicate that the presence of 1,5-pentanediol retards the formation of a rigid xerogel network that is responsible for crack formation during film drying. The air moisture during dip-coating also turns out to have a systematic effect on the microstructure of the densifying film as demonstrated by quantitative defect analysis. This method has to be used carefully, though, that a qualitative change of the damage pattern does not lead to a misinterpretation of the data. (c) 2006 Elsevier B.V. All rights reserved.