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DF: Fachverband Dielektrische Festkörper
DF 15: Dielectric and ferroelectric thin films
DF 15.3: Vortrag
Donnerstag, 29. März 2012, 10:35–10:55, EB 107
Nonlinear Dielectric Properties and Polarization in Ferroelectric P(VDF-TrFE) Copolymer Thin Films — •Danny von Nordheim, Steffen Hahne, and Bernd Ploss — Department of SciTec, University of Applied Sciences (FH) Jena, Carl-Zeiss-Promenade 2, 07745 Jena, Germany
VDF-TrFE copolymer ferroelectric thin films of molar composition 70/30 have been prepared by spin coating on glass substrate covered with aluminum electrode. Copolymer - solvent composition was varied from 1 wt% to 5 wt% in order to obtain sample thicknesses from 25 nm to 175 nm. Nonlinear permittivities up to ε3 of poled and unpoled samples have been studied over temperature in heating and cooling cycles up to 120 ∘C i. e., above the Curie temperature. The polarization and its temperature dependence is derived from first and second order permittivities ε1 and ε2. Results offer a non-destructive readout of the polarization state. A non-switchable polarization is found which remains after heating the material above Curie temperature. This non-switchable polarization points from the bottom to the top electrode and is not influenced by the initial polarization direction.