Effects of poling field and time on pyroelectric coefficient and polarization uniformity in polyvinyl fluoride

Electroded films of polyvinyl fluoride (PVF) were polarized with DC electric fields as high as 315 MV m−1 for periods between 60 and 7200 seconds at room temperature. Thermal pulse data to determine the depth of polarization and pyroelectric coefficients were obtained on all samples. Large pyroelectric coefficients could be produced above a threshold mean polarizing field of 100 MV m−1; with mean fields greater than 200 MV m−1, all samples appeared to be uniformly poled with pyroelectric coefficients in the 12–16 μC m−2 K−1 range. The thermal pulse data definitely established that, in partially-poled samples, the polarization was strongest near the poling cathode. Mathematical techniques were developed for the computation of fraction poled from the thermal pulse data using a nonlinear least squares analysis.