Can charge cause dielectric hysteresis? Observations on non-ferroelectric alpha-PVDF

Under suitable conditions, hysteresis of the current or of the polarization can be observed as a function of the electric field during poling of ferro electric polymer films. This behavior has been investigated extensively, an d was explained for various ferroelectric polymers with the well-known theo ry of ferroelectrics. The present work, however, indicates that poling of p olymers that contain excess charges but no polar crystallites, sometimes le ads to a similar hysteresis behavior. In support of this finding, we presen t and discuss current measurements during the electric poling of alpha -pol yvinylidenefluoride (PVDF) films and compare the results to the respective behavior of ferroelectric beta -PVDF films in which charge effects play qui te a different role.