Thermally stimulated depolarization current in annealed, quenched and γ-irradiated VDF/TrFE copolymers

Three types of VDF/TrFE copolymer samples were prepared. Thermally stimulated depolarization currents (TSDC) of copolymers have been measured with a modified thermal electric analyzer. For the quenched VDF(70)/TrFE(30) sample, if the poling temperature T-p is below 80 degreesC, the TSDC spectra only show one peak and the peak shifts monotonously to higher temperatures as T-p increases. Compared with the quenched sample, stronger TSDC signal for the annealed one suggests that the orientation of dipoles and the formation of traps are related to the perfect crystallites. gamma-irradiation lowers the Curie point and induces cross-linking of chains in the copolymer. With the increase in irradiation dose the TSDC signal decreases. The irradiated materials lose their ferroelectric properties at doses above 400 kGy.