Investigating the effect of oxygen vacancy on the dielectric and electromechanical properties in ferroelectric ceramics

The effect of oxygen vacancy on the dielectric and electromechanical properties in lead titanate zirconate based ferroelectric ceramics is discussed in this paper. The presence of oxygen vacancy forms a defect-dipole inside a perovskite cell. This defect-dipole contributes to the unswitchable polarization and influences the alignment of the ferroelectric dipole in the same cell as well. The latter is due to the displacement of the B-site cation, which contributes to the switchable polarization. It is found that a double hysteresis emerges when the alignment of defect-dipole conforms with the crystal orientation, which is perpendicular to the measured polarization. Moreover, the optimal electromechanical property can be obtained by careful adjustment of c-domain volume fraction and the alignment of defect dipoles. Monte Carlo simulation based on the four-state Potts model is presented. Calculation results are compared with experiments. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.2978376]