Modeling and Characterization of the Effects of Field Gradients on the Behavior of Ferroelectrics With Interdigitated Electrodes

Macro fiber composites (MFCs) are used in applications ranging from sensing and actuation to energy harvesting and piezoelectric damping. MFCs are comprised of interdigitated electrodes (IDEs) on ferroelectric fibers that result in anisotropic in plane sensing and actuation capability. Minor hysteresis loops were measured for a MFC and the area within the minor hysteresis loops was used to assess material loss under unipolar cyclic loading. A separate set of minor hysteresis loops was run on a fully electroded plate of the same material to determine the material loss when the electric field was uniform. The MFC displayed considerably more material loss than the uniformly loaded plate. A micromechanical model implemented in a finite element code was used to model the effect of inhomogeneous fields, local stress, and polarization reorientation on the dielectric losses. The results indicate that the development of local stress in the ferroelectric material beneath the inerdigitated electrodes results in ferroelastic polarization reorientation that contributes to dielectric losses.