Hysteresis in Copolymers of Vinylidene Fluoride and Trifluoroethylene.
Abstract
Copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE), with more than 50 mole percent VDF exhibit D-E hysteresis loops at room temperature which are much sharper than those exhibited by various crystal phases of the PVDF homopolymer. For the copolymer samples investigated here, appreciable conductivity develops at elevated temperatures which in the presence of electric fields leads to trapped charges in the polymer film, These charges then prevent the switching of dipoles at values of electric field that were applied, the room temperature hysteresis is greatly reduced and polarization through the thickness of the film is highly non-uniform. Upon heating the copolymers above the ferroelectric to paraelectric transition temperature, the polarization is destroyed, the space charges are apparently released and room temperature hysteresis is restored. Experiments with aluminum and gold electrodes and with mica blocking electrode lead to the conclusion that the charges are generated internally and are not injected from the electrodes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1984
- Accession Number
- ADA137446
Entities
People
- A. J. Lovinger
- G. T. Davis
- M. G. Broadhurst
- Tomonari Furukawa
Organizations
- National Institute of Standards and Technology