A clue to the origin of pyroelectricity in PVF2from the low temperature behavior

Since the discovery of pyroelectricity in the polymer polyvlnylidene fluoride (PVF2), there has been a continuing effort to identify the origin of the effect and to determine whether the material is best classified as an electret or ferroelectric. A recent study of the pyroelectric signal following pulsed heating provided fairly strong evidence that the primary pyroelectricity contributes at most a very small fraction of the total effect: the dominant contribution coming from thermal expansion of the piezoelectric polymer (secondary pyroelectricity). We report additional evidence from low temperature pyroelectric measurements that there is no significant contribution to the pyroelectric effect from low lying optic modes.