Enhancement in Curie temperature of nickel substituted Co-Mn ferrite

Curie temperature of Co0.7-xNixMn0.3Fe2O4 (with X=0.00, 0.05, 0.10 and 0.15) synthesized by the double sintering ceramic method, was recorded by, Lorria Sinha (T-CL), dc resistivity (T-CR) and dielectric measurement (T-CD). Curie temperatures obtained by three various methods are in good agreement with each other. Curie temperature measurements exhibit anomalous increasing trend with increasing nickel content for all the compositions. Three - sublattice model is used to elucidate anomalous behavior as, Neels two - sublattice model Mils to explain increase in Curie temperature, even after the replacement of Co2+ ions (3 mu B) by Ni2+ ions (2 mu B). Decrease in lattice constant and interionic distances can be probably originated by strengthening of A-B interaction. Enhancement in Curie temperature is observed due to the strengthening of A-B interaction. Values of magnetic moments and interaction between them are not the only reasons for enhancement of T-c but change in their orientation with temperature is also important and therefore analysis of Curie temperature is given on basis of anisotropic energy. (C) 2014 Published by Elsevier B.V.