Antiferroelectric-like behavior of vinylidene fluoride trifluoroethylene copolymers with low vinylidene fluoride content

Vinylidene Fluoride/Trifluoroethylene copolymers with compositions 47/53 and 37/63mol% exhibit a ferroelectric square D-E hysteresis loop at low temperatures (below -40 degrees C) and undergo transition to a paraelectric motional phase near T-c= 70 degrees C. At intermediate temperature they exhibit a double-hysteresis loop suggesting that polarization reversal occurs through a non-polar phase. Time domain measurement of polarization reversal shows two-step switching transient consisting of fast depolarization and slow re-polarization processes. The remanent polarization imparted in the ferroelectric phase shows gradual decay on heating and disappears completely well below T-c. We conclude that these copolymers take an antiferroelectric-like non-polar phase between low temperature ferroelectric and high temperature paraelectric phases.