Analysis of the influence of trivalent Cr3+ doping on the structural and electromagnetic properties of Cu0.5Mg0.5CrxFe2−xO4 nanoferrites

In this inspection, the structural, microstructural, electrical, and magnetic properties of Cr-doped Cu0.5Mg0.5CrxFe2−xO4 (x = 0.0, 0.04, 0.08, 0.12, and 0.16) composites were examined, which were prepared using the sol–gel technique. The x-ray diffraction patterns of the samples sintered at 700 °C for 5 h demonstrate the production of single-phase spinel ferrite. FESEM images indicate a nearly homogeneous surface morphology with non-spherical particles. The average grain size was found to decrease with the Cr concentration. The EDS spectroscopy study of the parent composition and a representative sample of doping composition (x = 0.08) revealed the existence of doped Cr, as well as Fe, Mg, Cu, and O, in the sample. The fluctuation of Cr doping has a significant impact on the magnetic characteristics. The saturation magnetization (Ms) declines as the Cr level grows up to x = 0.08 and then again increases with the increasing Cr content, which may be due to antiferromagnetic Cr not remaining at B sites. Permeability measurements show a similar trend as well. This is expected since μ′ is proportional to Ms squared and grain size. The imaginary part of the permeability decreases with increasing frequency and remains almost constant in the high frequency region. The dielectric constant decreases with frequency increment and remains almost persistent in a higher frequency range. The dielectric permittivity increases with the increasing Cr content up to x = 0.08 but then decreases for greater Cr concentrations. Lower hopping probabilities across grain boundaries may explain the decreasing tendency of the dielectric measurement and rising resistivity with Cr doping after the x = 0.08 concentration. These samples are well-suited for use in high-frequency systems due to their low dielectric loss.