Effects of Proton Irradiation on the Structure and Properties of Poly(Vinylidene Fluoride-Trifluoroethylene) 80/20 mol.% Copolymer

Films of poly(vinylidene fluoride-trifluoroethylene) 80/20 mol.% copolymer have been irradiated with 200 Mrad of 3 MeV protons. The effects of irradiation on the electric field induced strain, polarization hysteresis, dielectric constant, lattice spacing and phase transition behavior have been investigated. The irradiated copolymer exhibits a typical relaxor ferroelectric behavior, indicating that the proton irradiation breaks up the coherent polarization domains in the normal ferroelectric copolymer into nano-sized regions, thereby converting the material into a relaxor ferroelectric. The transformation of the nano-sized regions between nonpolar and polar phase induced by an external electric field gives rise to a large lattice strain and hence a high electrostrictive response.