(K,Na)NbO3 lead-free piezoelectric ceramics synthesized from hydrothermal powders

Among various lead-free piezoelectric materials, (K,Na)NbO3 is a very promising candidate. In this study, (K,Na)NbO3 ceramics were sintered from mixed KNbO3 and NaNbO3 powders prepared by hydrothermal reaction. These two powders were mixed with distilled water in a KNbO3/NaNbO3 molar ratio of 1. After sintering the mixed powder, the solid solution of (Na,K)NbO3 ceramics was obtained. The electrical properties such as the electromechanical coupling factors kp and k33, the mechanical quality factor, Qm, and the piezoelectric constant d33 of the sintered (K,Na)NbO3 ceramics were 0.32, 0.48, 71 (radial mode), 118 ((33)mode), and 107 pC/N, respectively.