Structure and temperature-stability of piezoelectric properties of K0.5Na0.5NbO3–LiSbO3–Al(Fe0.9Mn0.1)O3 lead-free ceramics

Abstract

(1 − x)(0.95K0.5Na0.5NbO3–0.05LiSbO3) − xAl(Fe0.9Mn0.1)O3 (KNN–LS–AFM) lead-free piezoelectric ceramics have been fabricated by a traditional ceramic technique. The structure and piezoelectric properties of this system have been studied. The result of X-ray diffraction analysis shows that LS and AFM diffuse into the KNN lattices to form a new solid solution with a perovskite structure. The phase structure of the ceramics has a transition from the coexistence of tetragonal and orthorhombic phases to single tetragonal phase, with increasing the AFM content. The orthorhombic–tetragonal phase-transition peaks in the temperature-dielectric constant (er) plots first shifts to the room temperature and then almost disappears, while the Curie temperature does not change evidently with the addition of AFM. The ceramic at x = 0.004 exhibits the best piezoelectric properties: d33 = 285 pC/N, kp = 53.9 %, Qm = 22.64. The Curie temperature is about 350 °C. Below the Curie temperature, all samples show a temperature-stable piezoelectric constant, indicating the possibility of applications from the room temperature to high temperature.