▎ 摘　　要

Rare earth Nd3+ doped Mg0.8Ca0.2Fe2O4 nanoparticles were prepared via chemical co-precipitation route. XRD confirmed the cubic structure of all compositions and XRD data was used to determine the lattice constant (a), cell volume (V), crystallite size (D) and porosity. Reduced graphene oxide (rGO) prepared via chemical route was utilized to obtain the Mg0.8Ca0.2Fe2-xO4-rGO nanocomposite materials. SEM analysis confirmed the well dispersed Mg0.8Ca0.2Fe2-xO4 nanoparticles among the graphene sheets. The photocatalytic degradation rate of methylene blue was higher in the presence of nanocomposite as compared to the bare nanoparticles under visible light irradiation. The enhanced photocatalytic activity of Mg0.8Ca0.2Fe2-xO4-rGO nanocomposite could be related to the decreased charge transfer resistance of composite materials investigated by electrochemical impedance spectroscopic (EIS) analysis. The value of dielectric constant and dielectric loss decreased with the increase in value of Nd3+ from 0 to 0.12 mol.