Dielectric studies of PVDF-BaFe12O19 film

Abstract

Composite thick films of dielectrics having magnetism are promising for variety of electronics applications. Polyvinylidene fluoride (PVDF) as polymer matrix for composites is very impressive due to its high dielectric values and less loss tangent, also the ferroelectric property in β phase among other phase has also been very tempting in polymer family. Barium Hexaferrite, i.e. BaFe12O19 (BHF) is a ferromagnetic material having large saturation magnetisation and high coercively. Thus, the combination of these two materials having composite film may lead to multiferroic properties which are good for enhancing magneto-dielectric properties with the flexibility of the polymer. PVDF based BaFe12O19 (BHF) was successfully synthesized into a free standing flexible thick film by using sol gel method. The thickness of the films was in the range of 40 μm to 50 μm. Phase purity of the film was investigated by X-ray diffraction and the dielectric properties under the applied magnetic field were studied up to 10 MHz frequency. Extremely high values of dielectric permittivity values beyond 500 were observed for the composite thick films. Very small effects magnetic field was seen. A monotonous increase in the AC conductivities with increasing BHF doping in PVDF were observed. The BHF nanoparticles matrices between the chains of PVDF acts as the external source to polarise the PVDF-α, γ, δ phases into ferroelectric crystalline β-phase under the presence of electric field which helps to improve the dielectric value. Moreover, interfacial spaces between BHF and PVDF heterogeneous mixtures give raise to Maxwell-Wagner-Sillar effect which in turn enhances the dielectric permittivity of the composite thick film.