Influence of Cr3+-substitution on the electrical and magnetic properties of Ni1.05Sn0.05Fe1.9O4 ferrites

The effect of Cr3+-substitution on dc resistivity, dielectric constant, initial permeability, saturation magnetization, and Curie temperature have been studied for Ni1.05Sn0.05CrxFe1.9−xO4 ferrites, wherein x varies from 0.0 to 0.5 in steps of 0.1. The dc resistivity increases slowly for x≤0.3 followed by a rapid increase for x≳0.3 and has been explained on the basis of Verwey hopping mechanism and dilution effect of Cr3+ ions. The behavior of dielectric constant for x≤0.4 is attributed to interfacial polarization and follows the Koops model, whereas for x≳0.4 a complex dielectric model seems to be applicable. The saturation magnetization and the Curie temperature decrease continuously with increased substitution of Cr3+ ions and have been explained by using the concepts of sublattice magnetizations and exchange interactions. The decrease in initial permeability is attributed mainly to the decrease in saturation magnetization. The dispersions in initial permeability and magnetic loss tangent have been discussed on the basis of domain wall movements.