Morphotropic phase boundary and electrical properties of lead-free (1−x)BaTiO3−xBi(Li1/3Ti2/3)O3 ceramics

Abstract

Dense polycrystalline ceramics of lead-free perovskite solid solution (1−x)BaTiO3−xBi(Li1/3Ti2/3)O3 (0.05≤x≤0.20) have been synthesized via the conventional solid state reaction method. A morphotropic phase boundary separating the tetragonal and orthorhombic phases was observed between the compositions x=0.07 and 0.10. With increasing Bi(Li1/3Ti2/3)O3 content, the solid solution displays a stronger frequency dispersion in its dielectric behavior and a significant suppression in the sharp dielectric anomaly at the Curie point as well as the remanent polarization. However, the Curie point of the solid solution is almost independent of x in the composition range studied. These behaviors can be explained by the observed core-shell grain structure. The incorporation of Bi(Li1/3Ti2/3)O3 into BaTiO3 leads to the formation of nanodomains in the shell, which imparts the relaxor characteristics to the dielectric behavior. The core of the grain preserves the large lamellar domains as those in BaTiO3, contributing to the sharp transition at ∼130 °C. The best piezoelectric coefficient was obtained in the composition x=0.07 with d33=110 pC/N.