Doping effect of Cr3+ ions on the structural, magnetic and electrical properties of Co-Cd ferrites: A study on the redistribution of cations in CoCd0.4CrxFe1.6-xO4 (0.1 ≤ x ≤ 0.6) ferrites

Increasing chromium substitution in Co-Cd ferrites, synthesized via sol-gel auto-combustion method, remarkably influences their structural, magnetic and electrical properties. As the Cr3+ concentration is increased, various interesting changes in the values of structural parameters like X-ray density, bulk density and porosity have been observed. The value of lattice constant, is found to be similar to 8.38 angstrom with an average crystallite size of similar to 50 nm. The porosity in the entire ferrite samples is low (5.3%-6.9%). The magnetic properties, like saturation magnetization and coercivity, show a decrease trend with increase in Cr3+ concentration. The proposed cation distribution is further substantiated by the electrical properties. It is observed that the d.c. resistivity increases with Cr3+ concentration, suggesting occupancy of Cr3+ ions in the 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 similar to 0.25 eV. (C) 2013 Elsevier B.V. All rights reserved.