Phase transition induced by thermal and electric fields in electron-irradiated poly (vinylidene fluoride-trifluoroethylene) copolymers

The reversible transformations between the metastable paraelectric phase induced in irradiation and polar ferroelectric phase (FEP) during both applied external field and thermal cycling process, were observed experimentally. The transition induced by thermal is interpreted by the ferroelectric theory of first-order transition, and the other one induced by electric field is explained by Landau-Devonshire phase transition theory. It is useful to elucidate the microscopic mechanism involved, and this might also be the most possible microscopic interpretation for large electrostrictive strain in these copolymers