Articles you may be interested inInvestigating the effect of oxygen vacancy on the dielectric and electromechanical properties in ferroelectric ceramics J. Appl. Phys.Electromechanical properties of ferroelectric thin films are investigated using a two-dimensional four-state Potts model and Monte Carlo simulation. In this model, the mechanical energy density induced by strains of individual cells is included in the system Hamiltonian, in addition to the contributions from dipole-dipole and electric-field-dipole couplings. Moreover, the dipole of each individual perovskite cell is aligned to one of the four mutually perpendicular directions. Four different states of dipole orientations can be defined. The deformation of each cell is associated with its dipole orientation, resulting in two different strain states. Polarization-electric-field hysteresis loops, butterfly loops for both transverse and longitudinal strains against electric field, as well as the phase-transition temperature under different stresses and anisotropy conditions are simulated. Results are comparable to the experimental measurements.

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.

The experimental result on dielectric and mechanical properties of PbZr x Ti 1−x O 3 driven by combined alternating electrical and mechanical loadings in various phase differences has been obtained by Zhou et al. ͓J. Appl. Phys. 96, 6634 ͑2004͔͒. This paper presents the numerical simulation of this result using a two-dimensional four state Potts model. In this model, there are four different dipole orientations to reflect the coexistence of 90°and 180°domain walls. The coupling between the electrical and mechanical responses is implemented by the presence of two different ferroelastic strain states which are associated to the four different dipole orientations. The interactions of these dipoles and strains together with the mechanical energy density are incorporated into the system Hamiltonian. The enhanced and reduced electromechanical responses when the electric field and the compressive stress are out of phase and in phase, respectively, are reproduced by our model.