Amorphous phases and piezoelectricity in (Na0.5Bi0.5)0.94Ba0.06TiO3-Bi12TiO20 flexoelectric-type nanocomposite ceramics

(Na0.5Bi0.5)0.94Ba0.06TiO3-Bi12TiO20 composite ceramics, which display macroscopic interfaces and have a net macroscopic polarization, were fabricated by an ordinary sintering technique. All the coarse grains were found to have nano-networked surfaces, implying a relatively high content of amorphous phases in this kind of ceramic. Because these interface-related amorphous phases are distributed non-homogeneously throughout the ceramic, we propose that the macroscopic polarization is due to partial alignment of the distorted TiO6 octahedra and the distorted BiO5 polyhedra in the amorphous phases.