Complex permittivity scaling of functionally graded composites

In this paper, we provide a fundamental understanding of dielectric loss behavior as a function of applied electric field and frequency in functionally graded composites with varying numbers of layers and compositions. A new power-law scaling relation in the form of f pE o q was derived based upon the ferroelectric hysteresis. The magnitude of the imaginary component of the dielectric permittivity () was estimated from the polarization-electric field hysteresis loop. The changes in exponents of the scaling relation were correlated with the mechanism controlling the dielectric loss and interfacial coupling in graded structures. Building upon the scaling analysis, we investigated the effect of Efield on the domain mobility () for various functionally graded systems. These results were correlated with the experimental investigation on ferroelectric domains using transmission electron microscopy and piezoresponse force microscopy.