Regensburg 2007 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 11: Poster Session

DF 11.4: Poster

Donnerstag, 29. März 2007, 14:30–18:00, Poster C

Breakdown-induced light emission and poling dynamics of porous fluoropolymers — •Sergej Zhukov and Heinz von Seggern — Electronic Materials Division, Institute of Materials Science, Darmstadt University of Technology, Petersenstrasse 23, 64287 Darmstadt

Until today the charging mechanisms of novel porous electrets materials are not completely understood. The present study is focused on the investigation of light emission during corona poling of films of expanded polytetrafluoroethylene (ePTFE) and sandwiched structures with the ePTFE film between two solid FEP films. One observes that as soon as the applied electric field exceeds a certain threshold value the individual film as well as the sandwich structure starts to emit light due to electrical breakdown in the pores. It will be demonstrated that a polarization hysteresis loop can be derived from the emitted light intensity in a polarization switching experiment. In the case of free-standing ePTFE films a continuous light emission indicates that breakdown generated charges are not trapped permanently at the fibers in the open pore media. The present results explain the drastic difference in piezoactivity between individual porous films and sandwiched structures.

The work is supported by Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF) *Otto von Guericke* e.V