Berlin 2005 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: FV-internes Symposium „Polare Polymere und Ferroelektrete“

DF 3.4: Vortrag

Samstag, 5. März 2005, 10:20–10:40, TU C130

Charging and Switching of Ferroelectrets: How Much Can Ferroelectrets Behave Like Ferroelectrics? — •Reinhard Schwödiauer, Ingrid Graz, Mario Dansachmüller, and Siegfried Bauer — Johannes Kepler Universität, Altenbergerstr. 69, A-4040 Linz

Nonpolar porous charge electrets with internally charged surfaces can exhibit pronounced piezoelectricity and have been termed "Ferroelectrets". Their puzzling and unexpected features resemble those normally known from traditional ferroelectrics: Ferroelectrets are piezo- and pyroelectric, their polarization can be reversed by means of an external field and electrical as well as mechanical hysteresis loops were observed. Here we report about the very different charging and switching mechanism in ferroelectrets, both in simple model-systems and in less simple foam structures. We also want to address some of the specific peculiarities and pitfalls related to present ferroelectrets and their characterization. Interfacial charge injection at high electric fields and anelastic non-linearities, for instance, can be the cause for false ferroelectric-like hysteresis effects which do not reflect any polarization reversal. Our contribution is an attempt towards a more comprehensive picture of how much ferroelectrets behave like ferroelectrics.