MICROSTRUCTURE DEVELOPMENT OF DIOL-BASED SOL-GEL PROCESSED LEAD TITANATE THIN-FILMS

Lead titanate thin films were prepared from a sol-gel process based on diol solvents, HOCnHe2nOH, with n = 3, 4 or 5. Their microstructures have been studied by a combination of electron microscopy and image analysis. The microstructures of the thin films annealed at 600 degrees C are related to the diol used as solvent. For films prepared from solutions in diol with n = 3, a homogeneous microstructure characterized by a narrow distribution of grain sizes was found. For n = 4 and 5, associations of grains with well-defined boundaries, or clusters, are observed. In the latter films the recrystallization of the clusters creates a heterogeneous microstructure. The origin of these microstructural differences is ascribed to the distinct thermal evolution during annealing of the films deposited by spin-coating of the precursor solutions. The distinct thermal evolution is caused by the distinct content of carbon of the diol solvent. The results reveal a straightforward method for the microstructural control of the thin films prepared by this sol-gel route by the selection of the appropriate precursor solutions.