A microscopic physical approach of nonlinear constitutive behaviors for BaTiO_3 ferroelectric single crystal

摘要

A lot of experiments have proved that the basic reason of the nonlinear and hysteresis constitutive curve in ferroelectric ceramics is domain switching. The microscopic domain switching behaviors of BaTiO_3 single crystals have been studied detailed. The forward and sideway motion of 180° domain wall has been measured by direct stroboscopic observation. The velocity expressions are given. In order to get the evolution equation of the volume fraction of domain switching, a square domain switching model is developed according to the relationship between the domain wall velocity and applied electric field. The model is compared to available experimental data of BaTiO_3 single crystals. It turns out that the model can represent the typical nonlinear electromechanical coupling phenomena. The evolution equation of the volume fraction of domain switching is reasonably consistent with a previous phenomenological model. Furthermore the evolution equation based on microscopic domain motion can further improve the microscopic phenomenological model.