Effects of composition on phase structure, microstructure and electrical properties of (K0.5Na0.5)NbO3–LiSbO3 ceramics

Lead-free piezoelectric ceramics with the composition of (1 − x)(K0.5Na0.5)NbO3–xLiSbO3 [(1 − x)KNN–xLS] have been synthesized by conventional solid-state sintering process and without cold isostatic pressing (CIP). A morphotropic phase boundary (MPB) between orthorhombic and pseudocubic phases was found in the composition range of 0.06 ≤ x < 0.10. Analogous to Pb(Zr, Ti)O3, the density, dielectric and piezoelectric properties were enhanced for the composition near the MPB. The 0.94KNN–0.06LS ceramics show excellent electrical properties, which are as follows: ρ = 4.44 g/cm3, ɛr = 708 (10 kHz), tan δ = 0.037 (10 kHz), d33 = 171 pC/N, kp = 0.38 and Tc = 365 °C. Dielectric study revealed that the dielectric relaxor behavior was induced by increasing LS content. In addition, 0.94KNN–0.06LS ceramics also exhibited relatively good ferroelectric properties with remanent polarization (Pr) of 18.9 μC/cm2 and coercive field (Ec) of 9.38 kV/cm. The results show that KNN–LS ceramics have the potential to be one of the leading lead-free piezoelectric materials for electromechanical transducers applications in the future.