Morphotropic phase boundary and piezoelectric properties of (Bi1/2Na1/2)1 − x(Bi1/2K1/2)xTiO3–0.03(Na0.5K0.5)NbO3 ferroelectric ceramics

Lead-free piezoelectric ceramics, (Bi1/2Na1/2)1 − x(Bi1/2K1/2)xTiO3–0.03(Na0.5K0.5)NbO3 (x = 0.10–0.40) were synthesized by conventional solid-state sintering. A morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases was confirmed. Two dielectric anomalies can be observed, showing diffused phase transition behavior. There is no shift of the dielectric maximum temperature with frequency due to the contribution of space charge at high temperatures, similar to pure (Bi1/2Na1/2)TiO3. The materials near MPB show a strong compositional dependence with the optimal properties of a d33 of 167 pC/N, a kp of 35.5%, a Pr of 27.6 μC/cm2 and a Ec of 27.9 kV/cm, suitable for future application.