Study of substitution limit, structural, bulk magnetic and electrical properties of Ca2+ substituted magnesium ferrite

The percentage substitution of large cation like Ca2+ for Mg2+ in MgFe2O4 without altering the cubic symmetry and its effect on structural, bulk magnetic and electrical properties have been investigated for Mg1-xCaxFe2O4 (x = 0.0-0.35) spinel ferrite system by means of X-ray diffraction (XRD), magnetization, ac susceptibility and dc resistivity measurements. It is found that a maximum of 23% of Ca2+ can be substituted for Mg2+. The variation of magneton number with x can be explained on the basis of Neel's collinear spin model. The Neel temperature determined through ac susceptibility and dc resistivity measurements agree with those calculated theoretically. The variation of electrical resistivity go hand in hand with the variation of the activation energy with the Ca-content. (C) 2004 Elsevier B.V. All rights reserved.