Dielectric relaxation and polarization response in relaxor ferroelectric P(VDF-TrFE) copolymer

Dielectric responses are characterized for high-energy electron irradiated P(VDF-TrFE) 65/35 mol% copolymer system, which exhibits many features resembling to be relaxor ferroelectric behavior observed in inorganic systems. In this paper we explore the relation between the relaxor ferroelectric behavior observed in irradiated copolymer system with fundamental polarization relaxation processes. The dielectric behavior of copolymer is investigated over a broad frequency (0.01Hz-10MHz) and temperature (-40 °C - 80 °C) range to cover the change in polarization dynamics of the copolymer system. In contrast to the inorganic relaxor ferroelectric system where the freezing of polar units occurs at a very high frequency region, the relaxor ferroelectric copolymer system clearly shows the freezing process in the measurable frequency range. The results of analysis suggest that the observed V-F freezing process is due to the increased coupling among the local polar chain segment motions in the crystalline region, frustrated by the randomness due to the irradiation which prevents the formation of macroscopic polarization. It is confirmed that the V-F freezing does not show any correlation with glass transition, which appeared due to the amorphous nature of the copolymer system