Controlling the properties of magnesium–manganese ferrites

Abstract

The effect of substitution of In 3+, Al 3+ and Cr 3+ ions on the electrical and magnetic properties of Mg–Mn ferrites has been investigated. The substitution of In 3+ ions in place of Fe 3+ ions, resulted in an increase of lattice parameter, owing to the larger size of the substituted ions, whereas lattice parameter decreased on substituting Al 3+ and Cr 3+ ions in place of the Fe 3+ ions, owing to the smaller sizes of these substituted ions. D.C. resistivity was found to increase with the substitution of In 3+, Al 3+ or Cr 3+ ions 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 Al 3+ and Cr 3+ substituted Mg–Mn ferrites. A significant reduction in the value of initial permeability, saturation magnetization and Curie temperature were observed with successive increase of Al 3+ and Cr 3+ ions. The saturation magnetization and initial permeability were found to increase with incorporation of In 3+ ions. A marked increase in the value of initial permeability was found for the Mg 0.9Mn 0.1In 0.5Fe 1.5O 4 ferrites. The Curie temperature was found to decrease with an increase of In 3+ ion concentration. These changes in the properties are explained on the basis of a modified cation distribution and their magnetic interactions and various models.