Xunlin Qiu, Werner Wirges, Reimund Gerhard

• Polarization-vs.-applied-voltage hysteresis curves are recorded on tubular-channel fluoroethylene-propylene (FEP) copolymer ferroelectrets by means of a modified Sawyer-Tower circuit. Dielectric barrier discharges (DBDs) inside the cavities are triggered when the applied voltage is sufficiently high. During the DBDs, the cavities become man-made macroscopic dipoles which build up an effective polarization in the ferroelectret. Therefore, a phenomenological hysteresis curve is observed. From the hysteresis loop, the remanent polarization and the coercive field can be determined. Furthermore, the polarization can be related to the respective piezoelectric coefficient of the ferroelectret. The proposed method is easy to implement and is useful for characterization, further development and optimization of ferro- or piezoelectrets.