Structural, spectral and dielectric properties of PVDF-HFP/Cobalt ferrite composite films

Abstract

PVDF-HFP/CFO composite films consisting of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) copolymer as the ferroelectric matrix and cobalt ferrite (CoFe2O4, CFO) nanoparticles as the ferromagnetic component were fabricated using a solution casting method. The CFO nanoparticles were synthesized using the coprecipitation approach, followed by calcination at a temperature of 850°C to obtain the pure phase. To fabricate PVDF-HFP/CFO composite films, CFO nanoparticles were loaded into PVDF-HFP with different weight % values ranging from 5, 10, 15, 20, 25, 30 and 40.The fabricated PVDF-HFP/CFO composite films were subjected to analysis in terms of their structural, morphological, spectral and dielectric properties. The CFO phase formation and its loading in composites was characterized using X-ray diffraction (XRD), while the surface morphology of the synthesized compounds was analyzed using scanning electron microscopy (SEM).The XRD analysis suggested the presence of the \(\beta\)-phase in PVDF-HFP as well as in the composites. The SEM micrographs revealed the spherulite morphology of the PVDF-HFP/CFO composites. The Fourier transform-infrared spectroscopy (FT-IR) measurement results displayed the presence of the \(\beta\)-phase, and the peak related to the \(\beta\)-phase showed an increase upto 20% CFO loading, which also reflects the enhancement of the dielectric constant. UV-Visible absorption spectra were employed to find the direct bandgap energy of the polymer composites using Tauc’s relation. The room temperature dielectric constant measurements displayed a dielectric constant value of 9.5 (PVDF-HFP), which increased to 80.82 (20% CFO-loaded composite) and later decreased as the CFO loading increased. The results were discussed in detail.