Ionic Conduction and Anomalous Diffusion in Sr and Ga Acceptors Co-Doped Bismuth Sodium Titanate Solid Solutions

Recently, ferroelectrics of Bi0.5Na0.5TiO3 (BNT) based perovskite-structured oxides that exhibit ionic conductive grain have attracted great attention, and been proved to be highly dependent on the chemical composition. Herein, effects of Sr and Ga acceptors co-doping on the impedance characteristics and electric properties of non-stoichiometric BNT ceramics were studied. It indicates that the conductivity of BNT ceramics is significantly improved after introducing a certain amount of Sr and Ga, where the grain conductivity and grain boundary conductivity can be clearly distinguished. The inhomogeneity is reflected in which the acceptors preferentially diffuse along the grain boundaries with the change in activation energy. The conductivity could be influenced associated with dopant-vacancy defect complexes as the increasing of dopant content and sintering time. Ionic dominated conductive properties easily mixed with electronic contribution can be derived at different atmospheres. The degree of diffuseness and relaxation are enhanced monotonically with dopant concentration that revealed by a modified Curie-Weiss law at the high frequency.