Effect of Rare Earth Metal Substitution on the Structural, Magnetic and Transport properties of Ni-Zn Ferrites

Abstract

The present work is focused on the influence of substitutions rare earth ions in Ni-Zn ferrites. Three series of ferrite samples of the compositions Ni0.60Zn0.40-xLaxFe2O4 (where x = 0.05, 0.10 and 0.15), Ni0.60Zn0.40-xYxFe2O4 [x = 0.05, 0.10 and 0.15] and Ni0.60Zn0.40-xEuxFe2O4 [x = 0.05, 0.10 and 0.15] were prepared by using solid state reaction technique. The phase identification was carried out by using the X-ray diffraction (XRD). The XRD analysis revealed that undoped rare earth in sample shows formulation of cubic spinel structure with no extra peak but other three RE (La, Y and Eu) doped samples show additional peaks other spinel structure and corresponding to a second orthoferrite phase. Lattice parameters of all three series slightly decrease with increasing x-content. A slightly increase in bulk density has been found with increasing RE content. The average grain size increases significantly with increasing RE content. The increase in density and grain growth of the samples may be attributed to the liquid phase at constant sintering temperature. A slight increase of Curie temperature, Tc and saturation magnetization Ms of Ni0.60Zn0.40- xRExFe2O4 [RE = La, Y and Eu] series with increasing RE in were observed. The change of Ms with the increase of RE substitution has been explained on the Neel’s Collinear two sublattices magnetization model and Yafet-Kittels’ non-collinear magnetization model. Initial permeability decreases with the increasing of RE ions. Quality factor signifies the merit of the material from the application point of view. The variation of the quality factor with frequency shows a similar trend for all three samples. From these three series of samples are seen that the real part of initial permeability almost constant up to 4MHz. The AC resistivity decreases with increasing temperature. The dielectric constant is found to decrease continuously with increasing frequency and remains almost constant at higher frequency range. The variation of electrical resistivity and dielectric properties is explained of Fe2+/Fe3+ ionic concentration with affect RE ions as well as the electronic hoping frequency between Fe2+ and Fe3+ ions.