Electromechanical coupling behavior of ferroelectric ceramics under multiaxial electric switching

Abstract

When a fully poled ferroelectric polycrystal is subjected to an external electric field at an angle θ to the original poling direction, its electromechanical response will also depend on such an angle. In order to evaluate such an angle-dependent nonlinear response, an orientation-dependent dual-phase equivalent system is introduced, and then a micromechanics theory based on irreversible thermodynamics and physics of domain switch is developed. The developed theory results in a kinetic equation that connects the new domain concentration at a given level of electric field and loading angle through an orientation-dependent Eshelby-type of S-tensor in a transversely isotropic piezoelectric matrix. The calculated results show that, as the angle between the initial poling direction and the newly applied field direction increases, the generated electric displacement at the same level of the electric field also increases. While all the responses—except for θ=0°–are all nonlinear, the calculated nonlinearity is most pronounced with the reversed switch θ=180°. These theoretical results are found to be in good qualitative and quantitative agreement with the experimental data of PZT-5H provided by Huber and Fleck [J. E. Huber and N. A. Fleck, J. Mech. Phys. Solids 49, 785 (2001)].