Poling Field Dependence of Ferroelectric Properties in Alkali Bismuth Titanate Lead-Free Ceramics

Abstract

The DC poling field dependence of ferroelectric properties was investigated to evaluate the mechanism of domain alignment in lead-free ceramics of the forms of (1-x)(Na0.5Bi0.5)TiO3–x(K0.5Bi0.5)TiO3 (x=0.08–0.28), 0.79(Na0.5Bi0.5)TiO3–0.20(K0.5Bi0.5)TiO3–0.01Bi(Fe0.5Ti0.5)O3 and (1-x)(Na0.5Bi0.5)TiO3–xBaTiO3 (x=0.03–0.11). From the DC poling field (E) dependence of ferroelectric properties, asymmetrical shapes in piezoelectric constants vs ±E caused by nonuniform mobility of domain alignment in the application of positive and negative poling fields were observed in the small amount substitution by (K0.5Bi0.5)TiO3 (x≦0.11) and BaTiO3 (x≦0.03). On the other hand, symmetrical shapes in piezoelectric constants vs ±E were observed in higher piezoelectricity with lower frequency constant accompanied with typical domain clamping. The effects to improve ferroelectric properties by Bi(Fe0.5Ti0.5)O3 and by BaTiO3 substitutions for (Na0.5Bi0.5)TiO3 were also proved by the measurement of P–E hysteresis loops.