Effect of the particle size in PZT precursor sols on the orientation of the thin films

In the sol-gel processing of the ferroelectric thin films of PbZr_xTi_1-xO₃ (PZT), solution precursor characteristics have long been considered as factors which affect thin film microstructure. In this study, the structures of PZT precursor sols before and after hydrolysis were characterised by using NMR (nuclear magnetic resonance), PCS (photon correlation spectroscopy), and SAXS (small angle X-ray scattering) techniques as well as the measurement of the rheological properties of the PZT precursor solutions. The measurements discovered that alkoxy ligands which were bonded to metals were completely replaced by acetate ligands in the unhydrolysed sols. The particles in our PZT sols are chain-like and their average size increases linearly after hydrolysis on a logarithmic scale due to the hydrolysis and condensation reactions. To examine the relationship between the film orientation and the particle size in the precursor sols, the films were fabricated with different particle sizes and then annealed at 480°C. The preferred orientations were investigated using X-ray diffraction.