Irradiation effects on the ferroelectric phase transition of vinylidene fluoride and trifluoroethylene copolymers

Recently, ferroelectric fluoro-polymers have attracted much interest because of their useful piezoelectric and pyroelectric activities. A major characterestic of most ferroelectrics is the Curie temperature, Tc, above which polarization is lost so that they become paraelectric. A series of the random copolymers of vinylidene fluoride and trifluoroethylene (P-VDFx/TrFE100-x) is the first ferroelectric polymer which exhibits a ferroelectric-to-paraelectric phase transition. One of authors (A.O.) gave a statistical theory for the ferroelectric phase transition of these copolymers (1). Work in this field has so far concentrated mainly on the transition behavior and corresponding structural change, which are depended upon the composition x in P-VDFx/TrFE100-x (2,3).