Structure and electrical properties of (Li, Sr, Sb)-modified K0.5Na0.5NbO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (K0.5Na0.5)0.96−xLixSr0.02Nb0.98Sb0.02O3 (abbreviated as KNSNS-Lix, x = 0–0.07) were prepared by conventional solid state reaction method. The compositional dependence of phase structure and electrical properties of the ceramics was studied. X-ray diffraction analysis showed that a morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases existed in the composition range of 0.04 ≤ x ≤ 0.05, near which the electrical properties were enhanced. The ceramics of x = 0.04 exhibited good properties (d33 = 142 pC/N, kp = 38.2%, Pr = 20.4 μC/cm2, Tc = 353 °C, ɛr = 774, tan δ = 3.2%) owning to the formation of MPB. These results showed that the KNSNS-Lix ceramic was a promising lead-free piezoelectric material.