Sintering Characteristic, Microstructure, and Dielectric Relaxor Behavior of (K _0.5 Na _0.5 )NbO ₃ –(Bi _0.5 Na _0.5 )TiO ₃ Lead‐Free Ceramics

Abstract

Highly dense lead‐free ceramics (1− x )(K 0.5 Na 0.5 )NbO 3 − x (Bi 0.5 Na 0.5 )TiO 3 [(1− x )KNN− x BNT] have been synthesized by pressureless sintering owing to the careful control of processing conditions. The densification of (1− x )KNN− x BNT ceramics improves with increasing addition of BNT. The translucence is observed in 0.96 KNN–0.04 BNT ceramics. Diffuse phase transition and frequency dispersion of the dielectric constant, which are two typical characteristics for relaxor ferroelectrics, are observed in (1− x )KNN− x BNT ceramics. Dielectric relaxor behavior obeys a modified Curie–Weiss law. In addition, (1− x )KNN− x BNT ceramics possess a high Curie temperature (>320°C). The results indicate that (1− x )KNN− x BNT ( x =0.06) ceramics are promising lead‐free candidate relaxor ferroelectrics for high‐temperature applications.