Room temperature AC properties and impedance analysis of Mg ferrite/polypyrrole (PPy) and Mg ferrite/reduced graphene oxide (rGO) composites

The auto-combustion sol–gel method has been used to synthesize a powder sample of MgFe₂O₄ nanoparticles. Nanocomposites of Mg-ferrite/PPy and Mg-ferrite/rGO have been prepared by thorough physical mixing, with weight ratios of 20% PPy and 20% rGO, respectively. To have a full insight into the materials, their structural properties have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT-IR). DC conductivity has been investigated too, and by comparing the results, it has been observed a significant increase in the DC conductivity of the Mg-ferrite/PPy composite sample compared to the corresponding Mg-ferrite/rGO sample, a finding that would potentially impact the composite’s applications. The discussion of the frequency dependence of ε′, σ_ac, and tan(δ) in these composite samples revolves around the concept of Maxwell–Wagner interfacial polarization. The sample Cole–Cole plots show distinct areas where incomplete semicircles overlap, each representing a different conduction process. These semicircles correspond to two equivalent circuits of parallel resistor–capacitor (R–C) combinations connected in series. Finally, it could be concluded that the new nanocomposite samples of MgFe₂O₄/20% rGO and MgFe₂O₄/20% PPy show dielectric properties that may be a stimulus for more studies in future work, where they are expected to be promising candidates for supercapacitor applications.