Influence of grain size effect and Ba/Ti ratios on dielectric, ferroelectric, and piezoelectric properties of BaTiO3ceramics

The grain size effect on the dielectric, ferroelectric, and piezoelectric properties of BaTiO3 (BT) ceramics with different Ba/Ti ratios, prepared by solid-state reaction and conventional sintering, was investigated, and the corresponding electrical properties of these ceramics with similar grain size were compared. The BT ceramics with Ba/Ti ratios of 0.997, 1.000, and 1.003 and grain sizes of approximately 1 μm exhibited dielectric constants of 4265, 4275, and 4835 and converse piezoelectric coefficients, d33*, of 703, 645, and 466 pm V−1, respectively. The remanent polarization, Pr, was relatively higher for Ba-excess BT ceramics. These results indicated that, in Ti-excess BT ceramics, domain walls were strongly pinned due to oxygen vacancies under small electric fields and they were de-pinned at high electric fields, contributing to the higher d33*, while the orientation of domains in high electric fields did not retain upon electric field unloading, resulting in lower Pr.