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http://hdl.handle.net/10397/577
| Title: | Spontaneous depolarization current in different mole ratio VDF/TrFE ferroelectric copolymers | Authors: | Peng, Z Zhang, X Chan, HLW Choy, CL |
Issue Date: | 1999 | Source: | ISE 10 : 10th International Symposium on Electrets : 22-24 September 1999, European Cultural Centre of Delphi, Greece : proceedings, p. 379-382 | Abstract: | Vinylidene fluoride (VDF)/trifluoroethylene (TrFE) ferroelectric copolymer samples with different mole ratio of 56/44, 70/30 and 77/23 were fabricated by casting from methyl ethyl ketone and followed by slowly cooling from melting state. Trapped delocalized charges during circulating thermo-stimulating have been observed as spontaneous depolarization current (SDC). For VDF(56)/TrFE(44) copolymer, SDC spectra show a positive current peak at 72°C during heating and a negative peak at 58°C during cooling. For VDF(70)/TrFE(30) copolymer, SDC spectra display a positive current peak at 114°C during heating and present a negative peak at 58°C and a positive one at 52°C during cooling, respectively. As for VDF(77)/TrFE(23) sample, SDC show a negative peak at 71°C and a positive one at 63°C during cooling. By comparison with DSC measurements, the peaks are ascribed to the conformation change during ferro-to-paraelectric or para-to-ferroelectric phase transition at heating or cooling processes. This is also an evidence of two coexistent ferroelectric phases in the VDF/TrFE copolymers. Poling above Tc, the electric field can cause the sample an observable change. | Keywords: | Cooling Differential scanning calorimetry Electric charge Electric current measurement Electric fields Ferroelectric materials Heat treatment Organic compounds Phase transitions Plastics casting Spectroscopy Temperature |
Publisher: | IEEE | ISBN: | 0-7803-5025-1 | Rights: | © 1999 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. |
| Appears in Collections: | Conference Paper |
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