Mn3+ substituted Co–Cd ferrites, CoCd0.4MnxFe1.6−xO4 (0.1 ⩽ x ⩽ 0.6): Cation distribution, structural, magnetic and electrical properties

Abstract

The substitution of Mn3+ ions in cobalt–cadmium ferrites (synthesized via sol–gel auto-combustion method) is found to remarkably influence their structural, magnetic and electrical properties. The structural evolutions of the nanophase, investigated using powder X-ray diffraction (XRD) studies reveal the formation of single-phased cubic spinel structures, with Fd-3m space group. As the Mn3+ concentration is increased, the values of the structural parameters like lattice constant, crystallite size, X-ray density, bulk density and porosity undergo significant changes. The value of lattice constant is found to be ∼8.40Å and the average crystallite size is in the range of 41–45nm. The porosity in the entire ferrite samples is low (4.0–10.2%). The magnetic properties, like saturation magnetization and coercivity, show a decreasing trend with increase in Mn3+ concentration. Using the values of saturation magnetization, the cation distribution has been proposed. The proposed cation distribution is further correlated with the electrical properties. It is observed that the D.C. resistivity increases with Mn3+ concentration, suggesting occupancy of Mn3+ ions in the octahedral B-sites which leads to the dilution of Fe2+–Fe3+ conduction. The activation energy calculated from the D.C. resistivity vs temperature curves is found to be ∼0.50eV.