Effects of composition on phase structure, microstructure and electrical properties of (K 0.5Na 0.5)NbO 3–LiSbO 3 ceramics

Abstract

Lead-free piezoelectric ceramics with the composition of (1 − x)(K 0.5Na 0.5)NbO 3– xLiSbO 3 [(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)O 3, 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/cm 3, ɛ r = 708 (10 kHz), tan δ = 0.037 (10 kHz), d 33 = 171 pC/N, k p = 0.38 and T c = 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 ( P r) of 18.9 μC/cm 2 and coercive field ( E c) 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.