Effect of Li addition on phase formation behavior and electrical properties of (K<inf>0.5</inf>Na<inf>0.5</inf>)NbO<inf>3</inf>lead free ceramics

Abstract

In this work, Li-modified KNN ceramic compositions ((K0.5Na0.5)1-xLix)NbO3with x = 0.03, 0.04, 0.05, 0.06, 0.65 and 0.07 were prepared by a conventional solid-state mixed-oxide method. The structural phase formation and microstructure were characterized by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). It has been found that a morphotropic phase boundary (MPB) between orthorhombic phase and tetragonal phases should exist between compositions with Li contents of 6-6.5%. The Curie temperature (Tc) of the ceramics shifted to higher temperature with increasing Li content. The room temperature dielectric constant was also seen to be higher than the pure KNN ceramics. In addition, the ferroelectric properties were found to enhance at near MPB compositions. This study clearly showed that the addition of Li could improve the dielectric and ferroelectric properties in (K0.5Na0.5)NbO3ceramics. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.