Dresden 2011 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 1: Dielectric and ferroelectric thin films 1
DF 1.6: Vortrag
Montag, 14. März 2011, 12:20–12:40, MÜL Elch
Ferroelectric poly(vinylidene fluoride) films crystallized with ionic liquids: Structure-property relations — •Feipeng Wang1, Alexander Lack1, Zailai Xie2, Peter Frübing1, Werner Wirges1, and Reimund Gerhard1 — 1Applied Condensed-Matter Physics, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany — 2Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany
Ferroelectric polymer films from poly(vinylidene fluoride) (PVDF) and its copolymers are often used in all-organic electronics. However, preparation of thin ferroelectric β-phase PVDF films is a challenging task due to the various crystalline phases of PVDF. In this work, ferroelectric PVDF films were obtained by spin coating from a solution containing a small portion of the ionic liquid 1-Ethyl-3-methylimidazolium nitrate ([EMIM][NO3]) and subsequent drying and annealing at elevated temperatures. The films show clear ferroelectric hysteresis behavior, with a remnant polarization of about 60 mC/m2 and a relatively high coercive field of about 200 MV/m. The quasi-static pyroelectric coefficient increases from 14 to 18 μC/(m2K) at temperatures between -20 and 40 °C. However, the measured pyroelectricity drops rapidly to 5 μC/(m2K) when the films are heated up to 70 °C. The pyroelectric activity remains 60 % after the films were heated to 120 °C for 1 h and cooled back to 20 °C. X-ray diffraction measurements prove that addition of the ionic liquid enhances the films' crystallinity.