Coexisting ferroelectric and paraelectric phases in electron beam irradiated P(VDF-TrFE) films

We report on structural, electrical, and Raman investigations of phase changes induced in P(VDF-TrFE) films by electron beam irradiation. With increasing electron beam dose, the ferroelectric β-phase is weakened because of reductions in the coercive field, remnant polarization, and Curie temperature. Finally, highly dosed (9.38 × 1016 cm−2) P(VDF-TrFE) shows a paraelectric α-phase. A Vogel-Folcher type relaxor behavior becomes strong with the decreasing freezing temperature and the increasing activation energy. From the Raman scattering measurement, we observed that both the α- and the β-phases coexist irrespective of the electron beam irradiation and that the temperature dependences of the α- and β-phases are quite different. The ratio of the intensity of the α-phase to that of the β-phase sharply increases at a certain temperature, at which polar nanoregions may disappear.