(K_0.5Na_0.5)NbO₃ lead-free ceramics with improved piezoelectricity and field-induced strain

The sintering additive 0.4ZnO-0.6B₂O₃ (abbreviated as ZnB) was proposed to improve the sintering behavior of (K,Na)NbO₃ ceramics. The influence of ZnB on the microstructure and electrical properties of (K,Na)NbO₃ ceramics was carefully investigated in detail. Results demonstrated that during the sintering process a liquid phase can form at a relative low temperature, which could favor and accelerate the densification of (K,Na)NbO₃ ceramics. Moreover, it was found that (K,Na)NbO₃ ceramics with 1.2 wt% ZnB exhibited excellent properties with the piezoelectric constant of d₃₃ = 134 pC/N and planar electromechanical coupling coefficient of k_p = 40%. Moreover, the field induced strain of 0.135@5 kV/mm was also achieved with this composition. Meanwhile, the mechanism for this enhancement of property was discussed.