A comprehensive study of NiFe2O4 and NiFe2O4/rGO (reduced graphene oxide) nanocomposite: synthesis, structural, optical, dielectric, magnetic and magneto-dielectric analysis

A sol–gel method was employed to synthesize a pure and reduced graphene oxide (rGO)—decorated NiFe2O4 (NFO) nanocomposite. Analysis of the X-ray diffraction (XRD) data revealed that both of these samples exhibit a cubic structure with an Fd-3m space group. According to Debye–Scherer’s equation, the average sizes for NFO and NFO/rGO nanocomposites are 21 and 17 nm, respectively. The Raman spectra of the NFO/rGO nanocomposite showed two prominent bands (D and G), confirming the presence of rGO with an ID/IG ratio of 0.8. The FTIR spectra determined the various functional groups present in these samples. Using UV–visible spectroscopy, the optical band gap (Eg) for NFO and NFO/rGO nanocomposite was determined to be 2.04 and 2.26 eV, respectively. The dielectric permittivity (ε) and tangent loss (tan δ) of NFO and NFO/rGO were investigated as functions of frequency (100 kHz to 1 MHz) at diverse temperatures ranging from 300 to 773 K, and they were explained by Maxwell–Wagner-type polarization. Frequency-dependent conductivity (σ) followed Jonscher's power law. Impedance spectroscopy further evaluated electrical characteristics, such as relaxation time (τ). At room temperature, NFO and NFO/rGO exhibited strong negative magneto-dielectric coupling (MD) in low-frequency regions. The magneto-dielectric (MD) percentages for the NFO and NFO/rGO nanocomposites are − 21.21 and − 62.47