Longitudinal piezoelectric strain measurements of poly(vinylidene fluoride) films

The longitudinal piezoelectric strain of poly(vinylidene fluoride) (PVF₂) films has been measured at room temperature using a high-sensitivity ac capacitance-type dilatometer. The dc bias field dependence of the piezoelectric strain coefficient d₃₃ has been determined. The polarization-related electrostrictive coefficient Q₃₃ obtained is several hundred times larger than the value in normal piezoelectric oxide crystals and is of opposite sign.