Influence of A-site nonstoichiometry on sintering, microstructure and electrical properties of (Bi0.5Na0.5)TiO3 ceramics

Lead-free (Bi0.5Na0.5)1+xTiO3 ceramics (x = −0.02, −0.01, −0.005, 0, 0.005 and 0.01) were prepared by ordinary sintering. The effect of A-site stoichiometry on the densification, microstructure, dielectric properties, high-temperature impedances, and piezoelectric properties was explored. It was found that the high conductivity of (Bi0.5Na0.5)TiO3 (BNT) ceramics should be mainly attributed to the formation of A-site cation vacancies during sintering. Improved physical and electrical properties can be achieved in the sample with A-site cation excess. The control of the stoichiometry proves to be an effective way to improve BNT ceramics for possible application.