Fabrication of flexible and self-standing inorganic–organic three phase magneto-dielectric PVDF based multiferroic nanocomposite films through a small loading of graphene oxide (GO) and Fe3O4 nanoparticles

Abstract

Flexible inorganic–organic magneto-electric (ME) nanocomposite films (PVDF, PVDF-GO, PVDF-Fe₃O₄ and PVDF-GO-Fe₃O₄), composed of well-dispersed graphene oxide (GO 5 wt%) and magnetic Fe₃O₄ nanoparticles (5 wt%) embedded into a poly(vinylidene-fluoride) (PVDF) matrix, have been prepared by a solvent casting route. The magnetic, ferroelectric, dielectric, magneto-dielectric (MD) coupling and structural properties of these films have been systematically investigated. Magnetic (M_s = 2.21 emu g⁻¹) and ferroelectric (P = 0.065 μC cm⁻²) composite films of PVDF-GO-Fe₃O₄ (PVDF loaded with 5% GO and 5% Fe₃O₄) with an MD coupling of 0.02% at room temperature (RT) showed a three times higher dielectric constant than that of the pure PVDF film, with a dielectric loss as low as 0.6. However, the PVDF-Fe₃O₄ film, which exhibited improved magnetic (M_s = 2.5 emu g⁻¹) and MD coupling (0.04%) properties at RT with a lower dielectric loss (0.3), exhibited decreased ferroelectric properties (P = 0.06 μC cm⁻²) and dielectric constant compared to the PVDF-GO-Fe₃O₄ film. MD coupling measurements carried out as a function of temperature on the multi-functional PVDF-GO-Fe₃O₄ film showed a systematic increase in MD values up to 100 K and a decrease thereafter. The observed magnetic, ferroelectric, dielectric, MD coupling and structural properties of the nanocomposite films are attributed to the homogeneous dispersion and good alignment of Fe₃O₄ nanoparticles and GO in the PVDF matrix along with a partial conversion of nonpolar α-phase PVDF to polar β-phase. The above multi-functionality of the composite films of PVDF-Fe₃O₄ and PVDF-GO-Fe₃O₄ paves the way for their application in smart multiferroic devices.