The negative piezoelectric effect of the ferroelectric polymer poly(vinylidene fluoride).
- Katsouras I Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- Asadi K Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- Li M Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4 9747 AG, Groningen, The Netherlands.
- van Driel TB Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.
- Kjær KS Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.
- Zhao D Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- Lenz T Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- Gu Y Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.
- Blom PW Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- Damjanovic D Ceramics Laboratory, Swiss Federal Institute of Technology-EPFL, 1015 Lausanne, Switzerland.
- Nielsen MM Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.
- de Leeuw DM Max-Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany.
- 2015-10-06
Published in:
- Nature materials. - 2016
English
Piezoelectricity describes interconversion between electrical charge and mechanical strain. As expected for lattice ions displaced in an electric field, the proportionality constant is positive for all piezoelectric materials. The exceptions are poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (P(VDF-TrFE)), which exhibit a negative longitudinal piezoelectric coefficient. Reported explanations exclusively consider contraction with applied electric field of either the crystalline or the amorphous part of these semi-crystalline polymers. To distinguish between these conflicting interpretations, we have performed in situ dynamic X-ray diffraction measurements on P(VDF-TrFE) capacitors. We find that the piezoelectric effect is dominated by the change in lattice constant but, surprisingly, it cannot be accounted for by the polarization-biased electrostrictive contribution of the crystalline part alone. Our quantitative analysis shows that an additional contribution is operative, which we argue is due to an electromechanical coupling between the intermixed crystalline lamellae and amorphous regions. Our findings tie the counterintuitive negative piezoelectric response of PVDF and its copolymers to the dynamics of their composite microstructure.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1038/nmat4423
- PMID 26436342
- Persistent URL
- https://sonar.ch/global/documents/212440
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