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

(Na0.5Bi0.5)(0.94)Ba0.06TiO3-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. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.