Orientation of crystalline dipoles in poly(vinylidene fluoride) films under electric field

Orientation of molecular dipoles in poly(vinylidene fluoride) (PVF 2) films under electric field has been measured by ir spectroscopy using ir transparent indium-tin-oxide electrodes. Significant changes in ir transmission with electric field have been observed at 512 and 446 cm -1, which demonstrate that crystalline dipoles in β-phase PVF2 orient along the electric field. As the field is cycled between positive and negative values, the dipole orientation exhibits a hysteresislike behavior, demonstrating that the polarization of β-phase PVF2 and its switching result directly from the orientation of crystalline dipoles. Time response of dipole orientation shows that the total orientation consists of an instantaneous part and a slowly developing part. Only the latter seems to contribute to the remnant polarization and its switching.