Effects of electron irradiation and annealing on ferroelectric vinylidene fluoride-trifluoroethylene copolymers

Abstract

It is shown that the Curie point of the ferroelectric vinylidene fluoride-trifluoroethylene copolymer can be shifted to the low temperatures by electron radiation. This effect was studied by in situ dielectric measurements as a function of the dose and of the irradiation temperature. An additional effect of the irradiation, in particular when performed at high temperature, was to noticeably decrease ε′. We also have studied annealing at temperatures around the melting point and shown that most of the irradiation damage was nonreversible and cumulative whereas part of it could be annealed. We have shown that it was apparently impossible to shift the Curie temperature lower than a limit temperature of the order of 0 °C. We discuss this effect and suggest the hypothesis of a competition with the glassy transition occuring in this temperature region.