Dynamics of ferroelectric switching in copolymer P(VDF-TrFE) films: Evidence for nanoscale monodomain structure

Abstract

The mechanisms of ferroelectric switching in ferroelectric polymers have been the focus of many detailed investigations, but several aspects remain unclear. In the present work, the dynamics of switching have been studied in poly(vinylidene fluoride-trifluoroethylene) films by generating hysteresis loops at different frequencies (0.2–4 Hz) in the temperature range from 40 to 80 °C. Based on the frequency dependence of the coercive field at different temperatures, a model based on the theory of rates of reactions has been used to quantify the activation volume and the contribution of thermal energy to the switching. The estimated values of the activation volume are in the range from 8 to 47 nm3, which are similar to the size of the crystallites reported in the literature (∼27 nm3), suggesting that domain switching in poly(vinylidene fluoride)-based ferroelectric polymers occurs by the switching of nanoscale monodomains.