Ferroelectric switching in PVDF at low temperatures and in high electric fields

Abstract

In ferroelectric switching experiments with stretched and unstretched PVDF-foils we have measured the time dependent growth of the polarization after applying a high electric field (of about 200 MV/m). These experiments were performed between 300 K and about 140 K. During the dipolar re-orientation (p=dipol moment per monomer) in the high field regime (E = electric field) the liberated energy p»E per monomer is of the same order as kT, and therefore the process of polarization in high fields is expected to be strongly influenced by the liberated energy and thus to proceed in a cooperative way. This cooperative polarization process is demonstrated in the strongly field dependent growth time of the polarization which rapidly decreases when higher fields are applied as can be best observed at temperatures above 200 K.