Fabrication of (K,Na)NbO<sub>3</sub>-based composite lead-free piezoelectric ceramics and their high-power properties

Mn-added (K,Na)NbO3-based composite lead-free piezoelectric ceramic containing KTiNbO5 phase was fabricated for potential application to high-power fields. The resulting with 2 mol % MnO2 exhibited properties (mechanical quality factor Qm = 650, constant d33 140 pC/N, electromechanical coupling coefficient kp 0.42, dielectric ε33T/ε0 750, loss tan δ 0.5 %), and adequate heat resistance (Curie temperature Tc 320 °C). It an internal electric field, as indicated by a shift of the polarization–electric field hysteresis loop in direction field. High-power characteristics bolt-clamped Langevin transducers prepared using superior those Pb(Zr,Ti)O3 at vibration velocity under high input voltage. has good resistance, dense microstructure, process stability, is considered be promising candidates ceramics devices, such ultrasonic motors, transformers, transducers.