Piezoelectric properties of (Li, Ag, Sb) modified (K0.50Na0.50)NbO3 lead-free ceramics

(1 − x)[(K0.4725Na0.4725)Li0.055]NbO3–xAgSbO3 [(1 − x)KNNL–xAS] lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. Effect of the amount of AgSbO3 (AS) on the phase structure, microstructure, ferroelectric and piezoelectric properties of (1 − x)KNNL–xAS ceramics were systematically investigated. It was found that the AS content in (1 − x)KNNL–xAS ceramics strongly affects the structure and electrical properties. A morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases was identified in the composition range of 0.01 < x < 0.03. The materials near the MPB exhibit a strong compositional dependence and enhanced electrical properties while maintaining high Curie temperature. The (1 − x)KNNL–xAS (x = 0.02) ceramics exhibit enhanced electrical properties (d33 ∼ 230 pC/N, Tc ∼ 430 °C, kp ∼ 39%, Pr ∼ 40.3 μC/cm2 and Ec ∼ 12.3 kV/cm) for the formation of MPB. These results show that (1 − x)KNNL–xAS ceramics are promising candidates for lead-free piezoelectric materials.