Study on the enhancement of ferroelectric β phase in P(VDF-HFP) films under heating and poling conditions

Free-standing, flexible films of poly(vinylidene fluoride-hexafluoropropylene), (P(VDFHFP)) were prepared by spin coating technique, and the effects of heat treatment and poling on the formation of electroactive (beta phase were studied. The X-ray diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy and Atomic force microscopy studies proved that the melt-quenching process influences the transformation of non-ferroelectric a phase to ferroelectric (beta-phase, when compared to heat drying process. The variation in the beta-phase content resulted in the enhanced ferroelectric response in the melt-quenched samples, which was proved by the dynamic contact electrostatic force microscopy (DC-EFM) studies and also by the ferroelectric hysteresis. The polarization switching behavior of the films was also investigated with DC-EFM. The electrical poling at 30 MV/m further enhanced the ferroelectric nature of the films by 29-30%. The films exhibited high dielectric constant, low dielectric loss, and low-leakage current, and it was identified that the leakage current in the films was originated due to the Schottky emission. (C)2017 Elsevier Ltd. All rights reserved.