Understanding of Relaxor Ferroelectric Behavior of Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) Terpolymers

Relaxor ferroelectric poly(vinylidene fluoride) (PVDF) based terpolymers are attracting tremendous interest because of their potential applications in advanced energy harvesting and storage devices. Fundamental understanding of the ferroelectric behaviors of poly(vinylidene fluoride) (PVDF) based terpolymers has proved elusive. Current research suggests that the existence of different hysteresis loops results from physical pinning of the ferroelectric domains by the bulky defect monomers and that the size of the defect monomer determines the ferroelectric behavior. In this study, a poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorotrifluoroethylene) random terpolymer is processed using a variety of methods and found to exhibit normal ferroelectric, single hysteresis loop (SHL), and double hysteresis loop (DHL) behaviors depending on the processing method. This indicates that the ferroelectric behavior of the terpolymer is related to not only the size of an individual defect unit but also how they are arranged within the relaxor ferroelectric phase. The results show that DHL behavior is a result of paraelectric domains that are promoted by long crystallization times, while the SHL behavior stems from a more random dispersion of these defects.