Nondoped Potassium Niobate Ceramics Synthesized by Hydrothermal Method with Optimum Temperature Condition

Abstract

Nondoped potassium niobate (KNbO3) ceramics were synthesized with fine powders obtained by a hydrothermal method. The hydrothermal method employs a chemical reaction in a solution. Low reaction temperature and self-assembly growth resulted in high-quality KNbO3 powders. In this study, various temperature conditions from 180 to 230 °C were examined for high-performance KNbO3 ceramics. After sintering at 1030 °C using hydrothermally crystal powders under respective conditions, the dielectric loss and permittivity of each ceramic were measured. As a result, the suitable temperature condition of the hydrothermal synthesis for piezoceramics was 210 °C. With admittance measurements, the piezoelectric performance of fabricated KNbO3 ceramics was confirmed. From the resonance frequency response corresponding to the radial vibration and thickness vibration modes, the coupling factors kr and kt and the piezoelectric constants d31 and d33 were measured to be 0.14 and 0.26, and -28 and 55 pm/V, respectively.