Multi-Scale Modeling of Dielectric Polarization in Polymer/Ferroelectric Composites

Ferroelectric materials are attractive fillers for polymer composites due to their high and non-linear dielectric constants. In this study, the dielectric response of the epoxy/BaTiO3 composite is obtained by a Sawyer-Tower measurement. In addition, we propose a multiscale computational approach that allows simulation of the polarization behavior of polymer/ferroelectric composites on the timescale above 100 ms, which is several orders of magnitude longer than previous studies. The model is free of ad hoc parameters and therefore can simulate the polarization characteristics from first-principles. Both in experiments and simulations, non-linear hysteresis behavior was observed in the epoxy/BaTiO3 composite even when the electric field across the BaTiO3 is more than an order of magnitude lower than the coercive field. The computational results suggested that this originates from the domain wall motion in BaTiO3. Some practical implications drawn from the computational results are discussed.