Abstract
► The paper discusses the influence of Mg doping on the transport electrical and magnetic properties of ferrite nanoparticles. ► Impedance spectroscopy shows existence of one relaxation mechanism, due to the co-effect of grains and grain boundaries. ► The Mg substitution has resulted in the decrease in the saturation.
Nanoscale Ni0.7−xMgxCu0.3Fe2O4 (0.0⩽x⩽0.5) ferrite powders were prepared by sol–gel method and obtained as dried gel after successful reaction between respective metal nitrates. X-ray diffraction (XRD) confirmed the successful synthesis of materials, and the formation of single-phase cubic spinel structure. The average particle sizes of these materials were found between 40 to 50nm and confirmed by TEM (±1). Dielectric constant (ε′) measured in the frequency range (42Hz to 5MHz) was found to decrease with increasing frequency of the applied field, which shows normal behavior, and has been explained in the light of Maxwell–Wagner interfacial polarization. Debye relaxation peaks were observed for lower concentration of Mg in frequency dependent dielectric loss tangent curves. Real and imaginary parts of impedance (Z′ and Z″) suggest existence of one relaxation mechanism which is attributed to the co-effect of grains and grain boundaries. The room temperature dc magnetization studies infer magnetic moment of Ni–Cu–Mg nanoparticles decreases with increasing Mg2+ doping content.