Compositional dependence of phase structure and electrical properties in (K0.42Na0.58)NbO3-LiSbO3 lead-free ceramics

( 1 − x ) ( K 0.42 Na 0.58 ) NbO 3 - x LiSbO 3 [(1−x)KNN-xLS] lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases was identified in the composition range of 0.04<x<0.06. The ceramics near the MPB exhibit a strong compositional dependence and enhanced piezoelectric properties. The ceramics with 5 mol. % LS exhibit enhanced electrical properties (d33∼270 pC/N, kp∼47.2%, Tc∼364 °C , To-t=35 °C, εr∼1412, tan δ∼2.8%, and Pr∼25.7 μC/cm2; Ec∼11.1 kV/cm) and possess low dielectric loss (<2%) at 10 and 100 kHz at high temperature (250–400 °C). The low dielectric loss at high temperature is very important for high-temperature application of the ceramics. The related mechanism of the enhanced electrical properties of the ceramics was also discussed. These results show that (1−x)KNN-xLS (x=0.05) ceramic is a promising lead-free piezoelectric material.