A-site cation off-centering contribution on ferroelectricity and piezoelectricity in pseudo-cubic perovskite structure of Bi-based lead-free piezoelectrics

The origin of the significantly large piezoelectricity and ferroelectricity was investigated in the 0.67BiFeO(3)-0.33BaTiO(3) ceramics. The crystal structure of 0.67BiFeO(3)-0.33BaTiO(3), identified using the Rietveld method, suggested a cubic structure at 950 K and a rhombohedral structure at 300 K with small lattice distortion 89.94(4) degrees, which is close to 90 degrees of cubic structure. Despite the small lattice distortion at 300 K, significantly large piezoelectricity and ferroelectricity was observed in the 0.67BiFeO(3)-0.33BaTiO(3), which is associated Bi ion off-centering. The Bi3+ ions were off-centered from the corner of the Ba2+ position along the (100 ) directions at 300 K, occupying three equivalent neighboring sites in the [100], [010], and [001] directions. The occupancies of Bi ions could be changed, and partially ordered along the applied electric field direction. The off-centered Bi ions are attributed to the ferroelectricity and piezoelectricity in non-centrosymmetry structure with a small lattice distortion, i.e., pseudo-cubic structure, due to partial ordering under the electric field. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the origin of significantly large piezoelectricity and ferroelectricity in 0.67BiFeO(3)-0.33BaTiO(3) ceramics. It was found that despite a small lattice distortion at 300K, the material still exhibited significant piezoelectric properties, attributed to the off-centering of Bi ions. The off-centered Bi ions are believed to contribute to the ferroelectricity and piezoelectricity in a non-centrosymmetric structure with a small lattice distortion.