The Influence of Particle Size of Acetic Acid Modified PZT Precursor Solution on the Crystallization and Electrical Properties of Sol-Gel Processed PZT Thin Films

摘要

In the sol-gel processing of the ferroelectric thinfilms of PbZr_xTi_-xO_3(PZT), solution precursor characteristicshave been long considered as a factor, which affects thin filmmicrostructure and orientation. In this study, we used a hybridsolvent of acetic acid and methanol to prepare PZT precursor sols.The structures of PZT precursor sols before and after hydrolysiswere characterised by using NMR (nuclear magnetic resonance),PCS (photon correlation spectroscopy), and SAXS (small angle X-ray scattering) techniques. We also measured the rheologicalproperties of the PZT precursor solutions. The measurementsrevealed that methoxy ligands, which were bonding to metals, werecompletely replaced by acetate ligands in the unhydrolysed sols.The particles in our PZT sols are chain-like and their average sizeincreases linearly on a logarithmic scale after extra water wasadded due to the hydrolysis and condensation reactions. Toexamine the relationship between the film crystallisation and theparticle size in the precursor sols, the films were fabricated withdifferent particle sizes and then annealed at 480 deg C. Thecrystallisation of the thin films was investigated using X-raydiffraction. Under the identical fabrication conditions, pyrochlorephase appeared in the films prepared with the solutions of largerparticle sizes. Ferroelectric properties were degraded when usingthe solutions with large particles.