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DF: Fachverband Dielektrische Festkörper

DF 1: Dielectric and ferroelectric thin films 1

DF 1.7: Vortrag

Montag, 14. März 2011, 12:40–13:00, MÜL Elch

Ferro- and pyroelectric characterization of thin poly(vinylidene fluoride) films — •Alexander Lack, Feipeng Wang, Peter Frübing, Werner Wirges, and Reimund Gerhard — Applied Condensed-Matter Physics, Department of Physics and Astronomy, Faculty of Science, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany

Ferroelectric poly(vinylidene fluoride) (PVDF) films with a thickness of about 430 nm were prepared by spin coating from DMF/acetone solution with addition of the ionic liquid 1-Ethyl-3-methylimidazolium nitrate ([EMIM][NO3]). After drying and annealing at elevated temperature, Fourier-transform infrared (FTIR) spectra and X-ray diffraction (XRD) measurements indicate dominance of the ferroelectric β phase. Ferroelectric hysteresis loops were obtained by integrating non-linear current-voltage characteristics from a uni/bipolar electric-field sweep that allows separation of ferroelectric switching from capacitive charging and conduction. The nano-scale films show a relatively high coercive field of 200 MV/m. The remnant polarization is about 60 mC/m2, which agrees with the degree of crystallinity. The pyroelectric coefficient is determined by analyzing the short-circuit current response during low-frequency temperature oscillations at different temperatures. From XRD measurements, the crystallinity, and the size and the distribution of the crystallites are determined.