Phase transition behavior and electrical properties of lead-free (Bi0.5K0.5)TiO3–LiNbO3 relaxor ferroelectric ceramics

Abstract

(1−x)(Bi0.5K0.5)TiO3–xLiNbO3 ((1−x)BKT–xLN) lead-free relaxor ferroelectric ceramics were prepared by a conventional solid-state route and their phase transition behavior and the corresponding electrical properties were investigated. A morphotropic phase boundary separating rhombohedral and tetragonal phases was identified in the composition range of 0.015<x<0.03, where the improved electrical properties of piezoelectric constant d33=75pC/N and electromechanical coupling factor kp=0.18 were obtained. Moreover, all samples show typical relaxor behavior characterized by the presence of diffuse phase transition and frequency dispersion. It was found that the dielectric relaxation behavior of BKT ceramics can be obviously enhanced with the addition of LN. In addition, the effect of the LN addition on the ferroelectric properties was also investigated by measuring polarization versus electric field hysteresis loops.