Sintering of lead titanate and titano-zirconate sol-gel thin films

Alkoxides of titanium and zirconium with lead acetate or 2-ethyl hexanoate have been used to obtain precursors of lead titanate (PT) and titanozirconate (PZT) in several solvants with additional ligands. Stable sols are spin-coated on single-crystal substrates used in microelectronics, dried to obtain a gel precursor, and fired at temperatures between 500 and 700°C. The stability conditions of the sols are described, with emphasis on the important role of viscosity. The evolution of the gel with temperature was followed by thermogravimetric analysis (TGA) and high temperature X-ray diffraction (XRD). The TGA experiments showed that decomposition rates are strongly dependent on the raw material used and the reflux conditions. The XRD experiments showed that crystallization of the phase occurs between 500 and 600°C. The thickness of the films and the grain size have been derived from scanning electron microscopy observation. The ferroelectric hysteresis loops were measured with a Sawyer-tower circuit