Enhancement of dielectric, ferroelectric and magneto-dielectric properties in PVDF-BaFe12O19 composites: a step towards miniaturizated electronic devices

Highly flexible inorganic-organic composite films of barium hexaferrite (BHF) nanoparticles and a polyvinylidene fluoride (PVDF) polymer with small but appreciable magneto-dielectric coupling have been fabricated at room temperature. The films have been thoroughly characterized by using different techniques like X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Coexistence of alpha and beta forms of PVDF has been established in undoped and doped PVDF. The amount of electro-active beta phase of PVDF increases with an increase in filler (BHF) amount. Interestingly, dielectric permittivity of PVDF is enhanced up to eight times upon addition of the optimum amount of BHF. This increase in permittivity has been explained by the space charge polarization at the interfaces between the two phases of the composite and the formation of several micro-capacitors within the samples. The electrical and magnetic polarization measurements on the films confirm the composite materials are ferroelectric as well as ferromagnetic in nature. Subsequently, magneto-dielectric (MD) coupling measurements confirm the multiferroic nature of the composite films.