Microstructure and local piezoelectric properties of (Pb,Ca)TiO₃ thin films

Microstructure and local piezoelectric properties of Ca-doped PbTiO 3 (PCT) films prepared by sol-gel method and crystallized using UV-assisted rapid thermal annealing are investigated by Scanning Force Microscopy. The surface morphology is characterized by fine grains organized in circular structures with the mean diameter of the rings ≈ 80 nm and the average depth of the depressions inside the rings ≈ 10 nm. The average fraction of the depressions on the PCT surface is about 20%. Domain pictures acquired by SFM show no correlation between the morphology of the grains and domain structure of as-grown films. However, local hysteresis loops are different in grains located inside the rings and on the ring walls. This effect is attributed to the contribution of electrostatic interaction to the measured piezoelectric response. The prospects of using ring-shaped microstructure of PCT films for the development of piezoelectric nanocomposites are discussed.