Dielectric and Field-Induced Piezoelectric Responses in Electron-Irradiated Poly(Vinylidene Fluoride- Trifluoroethylene) Copolymer

Abstract

Ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymers were transformed into relaxor ferroelectric phase by high-energy electron irradiation. Temperature and frequency dependence of dielectric properties were investigated under dc bias field. The relaxor ferroelectric copolymers show high electrostrictive strain response (Q12 = 10 m4/C2) with an effective d31 = 180 pm/V at a field of 50 MV/m. Direct piezoelectric response of the relaxor ferroelectric copolymer can be tuned by dc bias, d31 is measured to be 116 pC/N at 40 MV/m bias field. Electromechanical coupling (k31 = 0.28 at 60 MV/m bias field) was significantly enhanced in the relaxor ferroelectric copolymers as compared to that in the normal ferroelectric P(VDF-TrFE) copolymers.