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BP: Fachverband Biologische Physik
BP 28: Focus: Charge Effects in Soft and Biological Matter II (joint CPP, BP, ST)
BP 28.9: Vortrag
Donnerstag, 25. März 2010, 16:45–17:00, H37
Three-layer piezoelectrets from fluoroethylenepropylene (FEP) copolymer films: Arrangement, preparation and characterization — •Peng Fang1, Feipeng Wang1, Werner Wirges1, Heitor Cury Basso2, and Reimund Gerhard1 — 1Applied Condensed-Matter Physics, Department of Physics and Astronomy, Faculty of Science, University of Potsdam, Potsdam-Golm, Germany — 2Department of Electrical Engineering, São Carlos School of Engineering, University of São Paulo, São Carlos - SP, Brazil
Piezoelectrets are very useful transducer materials for electromechanical and electroacoustical sensors and actuators. A new process for the preparation of three-layer FEP-sandwich piezoelectrets is introduced. The samples are prepared from commercial FEP films by means of simple procedures such as laser cutting, laser bonding, electrode evaporation and high-field poling. The resulting dielectric-resonance spectrum demonstrates the piezoelectricity of the FEP sandwich. A DC poling voltage of around -4 kV is sufficient to achieve piezoelectric d33 coefficient as high as 40 to 50 pC/N. After a continuous dynamic measurement of d33 over 5000 cycles (around 1 day), samples still retain 90% of their initial piezoelectricity. Higher measuring frequencies lead to a decrease of d33. At 100 Hz, d33 is 70% of the value at 2 Hz. Samples charged at elevated temperatures show much better thermal stability of d33. No obvious decay of d33 is found on samples charged at 130 degree C after one-hour storage at 120 degree C. Samples retain more than half of their initial piezoelectricity after a thermal treatment at 140 degree C and are still piezoelectric at 160 degree C.