Microstructure and ferroelectric properties of sol-gel PZT thin films on nickel alloy electrode for use with soda-lime glass substrate

The Ni alloy electrode was used for a bottom electrode of PZT thin films prepared by sol-gel process. Although BaTiO₃ films had consisted of a perovskite single phase, PZT films were composed of a perovskite phase with second phases of Pb₃O₄ and ZrTiO₄ on the alloy electrode. In order to prevent the second phases forming, the heat treatment time of the electrode was increased to obtain the thicker Al₂O₃ layer on the alloy electrode. The second phases decreased with increasing the heat treatment time, however, the phases did not disappear. When BaTiO₃ films were inserted between the electrodes and PZT films, the grain growth of PZT films was promoted by the existence of the BaTiO₃ buffer layer, finally, the PZT single phase was obtained. As the tan δ of the films decreased with decreasing the amount of the second phases, it became 3.9%, the film of which possessed a remanent polarization of 20 μC/cm²