AC measurements and magnetic properties of magnesium ferrite and its composites with reduced graphene oxide (rGO) and polypyrrole (PPy).

Nanoparticle magnesium ferrite and its three composites have been successfully synthesized. The composites incorporate 10% of rGO, 10% of PPy, and 10% of both materials, respectively, with appropriate ratios of Mg ferrite. X-ray diffraction confirmed the formation of a homogeneous spinel phase in all samples. FTIR spectra of the rGO and PPy composites revealed characteristic peaks corresponding to functional groups such as C-O, C = C, and C-H, while interaction between the aromatic rings of PPy and rGO was evident in the ternary composite. Magnetic measurements via VSM showed soft ferrimagnetic behavior for all samples. AC conductivity analysis indicated semiconducting characteristics, with a notable enhancement in the composite containing both rGO and PPy. This improvement is attributed to π-π stacking interactions that facilitate charge transport. Dielectric behavior as a function of frequency suggests that interfacial polarization plays a significant role in the observed properties. Quantitatively, the dielectric constant increased from ~ 36 for pure MgFe₂O₄ to ~ 220 for the MgFe₂O₄/10% rGO/10% PPy composite (≈ 510% enhancement), while the AC conductivity rose from ~ 8 × 10⁻⁵ S/m to ~ 6 × 10⁻⁴ S/m (≈ 650% increase). The Impedance Cole-Cole diagram of the ferrite sample shows a part of a semicircle. As the amounts of rGO or PPy have been raised, the shape of the Cole-Cole diagram becomes smaller and closer to well-observed semicircles in the ferrite/rGO/PPy composite because of the strong π-π stacking interactions mentioned above. These enhancements indicate that the composites are promising candidates for applications in supercapacitors.