Electrical and magnetic transport properties of Ni-Cu-Mg ferrite nanoparticles prepared by sol-gel method

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 50 nm and confirmed by TEM (+/- 1). Dielectric constant (epsilon') measured in the frequency range (42 Hz to 5 MHz) 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. (C) 2013 Elsevier B. V. All rights reserved.