Piezoelectric properties in perovskite 0.948(K0.5Na0.5)NbO3-0.052LiSbO3 lead-free ceramics

Lead-free piezoelectric ceramics, with the nominal composition of 0.948(K0.5Na0.5)NbO3-0.052LiSbO(3) (KNN-LS5.2), were synthesized by conventional solid-state sintering, and the piezoelectric and electromechanical properties were characterized as a function of temperature. The Curie temperature of the KNN based perovskite material was found to be 368 degrees C with an orthorhombic-tetragonal polymorphic phase transition (TO-T) temperature at approximately similar to 35 degrees C. The room temperature dielectric permittivity (epsilon(T)(33)/epsilon(0)) and loss were found to be 1380 and 2%, respectively, with piezoelectric properties of k(33)similar to 62% and d(33)similar to 265 pC/N and k(31)similar to 30% and d(31)similar to-116 pC/N. The temperature dependence of the properties mimicked the compositional variation seen in the proximity of a morphotropic phase boundary [e.g., lead zirconate titanate (PZT)], with a maxima in the dielectric and piezoelectric properties and a corresponding "softening" of the elastic properties. Unlike that found for PZT-type materials, the modified KNN material exhibited characteristics of both "soft" and "hard" piezoelectricities owing to the distinctly different domain states associated with orthorhombic and tetragonal phases. (c) 2006 American Institute of Physics.