Preparation of ferroelectric single crystalline films by sol-gel processing

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The aim of this research is to obtain the fundamental knowledge to make single crystalline PZT films through sol-gel processing using the alkoxides of Zr and Ti. Coating liquids were prepared by dissolving the alkoxides and lead acetate trihydrate into n-prophy alcohol, dip- or spin-coated on MgO, SiO_2 and stainless steel substrates, and fired at 300-850ﾟC.Higher temperature was required in the SiO_2 substrate than the MgO substrate. By the heat treatment at 600ﾟC, perovskite phase was obtained in MgO and stainless steel substrates. (100) oriented films were realized by using a cleaved MgO substrate. In order to make thick films for the actual uses such as sensors and actuators, multiple coatings were tried and a crack-free film with a thickness of 10,000nm was obtained. For the actual uses, preparation of substrates with good electric conductivity is important, and the substrates coated with ZrO_2-Y_2O_3 films for oxidation protection were prepared by the sol-gel processing. The insulating resistance of zirconia films showed a breakdown strength of the order of 10kV/mm. Preparation of PZT film on this substrate was also tried.