Enhanced dielectric properties and theoretical modeling of PVDF–ceramic composites

The ceramic-polymer composites, consisting of (Bi_0.5K_0.5)(Fe_0.5Nb_0.5)O₃ [BKFN] as fillers and poly (vinylidene fluoride) (PVDF) as matrix, with different ratios (weight ratio of BKFN to PVDF, are 10%, 30% and 50%) have been prepared by using a solution casting method. The X-ray diffraction (XRD) pattern evidenced a semi-crystalline structure containing mixed α-, β- and γ- phases of PVDF which was further confirmed by Fourier transform-infrared spectroscopy. Using scanning electron micrograph, the dispersion of the particulate filler in PVDF matrix is examined. With an increase of BKFN content, in the BKFN–PVDF composite films, both the dielectric constant and remnant polarizations showed a remarkable increase as compared to those of PVDF. Different theoretical models were proposed with experimental data to determine the effective dielectric constants of the prepared composites. Also, increased optical band gap is observed due to addition of BKFN in PVDF.