Controlling the properties of magnesium-manganese ferrites

The effect of substitution of In3+, Al3+ and Cr3+ ions on the electrical an d magnetic properties of Mg-Mn ferrites has been investigated. The substitu tion of In3+ ions in place of Fe3+ ions, resulted in an increase of lattice parameter, owing to the larger size of the substituted ions. whereas latti ce parameter decreased on substituting Al3+ and Cr3+ ions in place of the F e3+ ions, owing to the smaller sizes of these substituted ions. D.C. resist ivity was found to increase with the substitution of In3+, Al3+ or Cr3+ ion s in the Mg-Mn ferrite system. The improvement in the d.c. resistivity has been observed at the expense of deterioration in the magnetic properties of Al3+ and Cr3+ substituted Mg-Mn ferrites. A significant reduction in the v alue of initial permeability, saturation magnetization and Curie temperatur e were observed with successive increase of Al3+ C and Cr3+ ions. The satur ation magnetization and initial permeability were found to increase with in corporation of In3+ ions. A marked increase in the value of initial permeab ility was found for the Mg0.9Mn0.1In0.5Fe1.5O4 ferrites. The Curie temperat ure was found to decrease with an increase of In3+ ion concentration. These changes in the properties are explained on the basis of a modified cation distribution and their magnetic interactions and various models. (C) 2001 E lsevier Science B.V. All rights reserved.