Poling Field Dependence of Ferroelectric Properties in Piezoelectric Ceramics and Single Crystal

Abstract

Domain structures of ferroelectric materials were investigated by measuring the poling field dependence of dielectric and piezoelectric properties. Ferroelectric materials evaluated consist of as follows: soft and hard lead zirconate titanate (PZT) ceramics with tetragonal and rhombohedral phases, lead titanate (PT) ceramics, barium titanate (BT) ceramics and a relaxor based single crystal of Pb(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 O 3 (PZNT). Changing the poling field (E) from 0 M +E M 0 M m E M 0 to +E, the electromechanical coupling factor (k p , k 33 ), dielectric constant ( l r ) and frequency constant (fc) were measured. The minimum k p , k 33 and l r were obtained at the same E because of the 180° domain clamping. Furthermore, the E due to the domain clamping corresponded to the coercive field (Ec) determined by the poling field dependences. At the Ec, maximum fc was confirmed in the cases of soft PZT (tetragonal and rhombohedral) and hard PZT (tetragonal) ceramics, BT ceramics and PZNT single crystal. It was thought that the materials became mechanically hard by the electrical attracting through the domain clamping ( N O ). In hard PZT (rhombohedral), PT and BT ceramics, the peak of l r and/or minimum fc were observed at an E, which corresponds to the threshold of 90°, 71° or 109° domain rotations.