Rapid processing for hydrothermal deposition of (K,Na)NbO3 (KNN) thick films was proposed with the assistance of microwave (MW) heating, for short-time fabrication of ferroelectric/piezoelectric films with thicknesses of several micrometers within 1 h. MW irradiation raised the temperature of water medium up to 240 °C within 10 min, whereas conventional heating using hot-air convection required more than 2 h. Epitaxial KNN films were successfully deposited on single-crystal substrates of (100)SrTiO3:Nb and (100)SrRuO3//(100)SrTiO3 at reaction temperature of 180 °C–240 °C within 1 h; especially, the films with thicknesses over 10 μm could be obtained on at 220 °C for 40 min. The resulting film exhibited domain structure and dielectric/ferroelectric properties comparable with the KNN films derived from conventional hydrothermal deposition.

Low-temperature processing based on microwave-assisted hydrothermal synthesis was proposed for deposition of piezoelectric oxoate KNbO 3 films. The films were deposited on various substrates at reaction temperature below 200 °C using Nb 2 O 5 powder and KOH solution. Epitaxial (100) c KNbO 3 film with ³1.3 ¯m-thick was deposited at a reaction temperature of 150 °C on (100) c SrRuO 3 //(100)SrTiO 3 using 12 mol dm ¹3 KOH solution for 80 min, which is significantly faster than conventional hydrothermal process.