Polarization behavior during high field poling of poly(vinylidene fluoride)

Abstract

The polarization process which takes place during electric poling of poly(vinylidene fluoride) is investigated by measuring the time dependence of currents in poling circuits with varying RC time constants. For applied voltages between 3 and 8 kV (average field strengths 1.2–3.2 MV/cm) and RC values between 10 and 10−3 s, the current-time behavior, normalized by the corresponding RC time constants and initial current values, can be described by a single curve (quasi-steady state). Such a representation indicates that the switching of polarization is simply a voltage- or field-induced effect. A phenomenological description of the poling process is presented which allows one to determine the dependence of polarization with respect to the voltage across the sample. The corresponding density function shows a steep rise in polarization at about 2400 V (average electric field strength 1 MV/cm) followed by an exponentially decaying tail toward higher voltages. Implication of such a distribution is discussed briefly.