Temperature dependence of coercive field and fatigue in poly(vinylidene fluoride-trifluoroethylene) copolymer ultra-thin films

• Published in: Journal of physics. D, Applied physics Applied physics, 2011-04, Vol.44 (15), p.155501
• Main Authors: Zhang, Xiuli, Xu, Haisheng, Zhang, Yanni
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Structure, morphology and analysis
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/44/15/155501

The experimental intrinsic coercive field of ferroelectric poly(vinylidene fluoride-trifluoethylene) copolymer films, with both bottom and top gold electrodes is measured at a wide temperature range. In the lower temperature region from −20 to 25 °C, the temperature dependence of coercive field shows good agreement with the prediction by the Landau–Ginzburg (LG) mean-field theory. In the higher temperature region from 25 to 80 °C, the coercive field shows a slow decrease with the increased temperature, where the LG theory is not applicable any more. The temperature-dependent changes in the polymer chains have been analysed. A reversible ‘inherent fatigue’ is observed from the partially recovered remanent polarization after re-annealing a fatigued P(VDF-TrFE) film. FTIR spectra indicate that the interchain spacing does not change from 10 to 10 7 switching cycles while the degree of all-trans ferroelectric phase decreases gradually with applied switching cycles. After a re-annealing treatment, ferroelectric phase recovers and dipoles at the boundary of crystallites acquire much higher energy.