Polarization switching dynamics by inhomogeneous field mechanism in ferroelectric polymers

Abstract

The understanding of polarization switching dynamics of ferroelectrics is of great importance for practical applications and has been steadily advanced for ferroelectric ceramics and polymers for more than half a century. The temporal behaviour of polarization reversal in ferroelectric copolymers such as P(VDF-TrFE) cannot be satisfactorily explained by simple models such as the classical Kolmogorov–Avrami–Ishibashi nucleation and growth theory.In this paper the inhomogeneous field mechanism (IFM) model recently proposed for PZT ceramics has been applied to polymer ferroelectrics for the first time. The model is based on the assumption that the switching volume is divided into many spatial regions with independent dynamics, only determined by the local electric field. The local field values are randomly distributed over the ensemble of regions due to intrinsic inhomogeneities of the material. Therefore an inhomogeneous switching behaviour is induced by the varying local fields of each region. The statistical distribution of local field values can be directly extracted from the experimental data. The model satisfactorily describes virgin P(VDF-TrFE) samples over a broad time-field domain covering eight orders of magnitude of poling time and electric field values from 30–150 kV mm−1. In the same way we can conclude that the IFM model is adaptive to both ferroelectric ceramics and semi-crystalline polymers.