Relaxor ferroelectric of gamma-irradiated poly(vinylidene fluoride-trifluoroethylene) copolymers

Abstract

We have conducted a systematic investigation on g-irradiated poly~vinylidene fluoride-trifluoroethylene! equimolar samples. The appearance of relaxor features is clearly demonstrated for this copolymer, for gammairradiation doses comparable to those of electron irradiated samples. This material constitutes a new class of relaxor ferroelectrics, since its structure has no direct relationship with perovskite or tungsten-bronze structures and it is also the first non-displacive relaxor ferroelectric. Dielectric, calorimetric, structural, and spectroscopic data allowed us to draw a picture of the chemical and morphological modifications that cause the appearance of the relaxor behavior of the material. In particular, the loss of stability of the ferroelectric domains is attributed to the freezing of the amorphous phase, which forbids the establishment of long-range ferroelectric order.