[18p-Z16-1~16] 9.1 Dielectrics, ferroelectrics

▲ [18p-Z16-10] Influence of grain size effect and Ba/Ti ratios on dielectric, ferroelectric, and piezoelectric properties of Barium titanate ceramics

〇(D)Piyush Sapkota¹, Ichiro Fujii¹, Shintaro Ueno¹, Satoshi Wada¹ (1.Univ. of Yamanashi)

Keywords:Dielectric

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, respectively. The remanent polarization, P_r, was relatively higher for Ba-excess BT ceramics, as shown in Fig. 1. 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 would not retain upon electric-field unloading, resulting in lower P_r.