Effects of dopants on the microstructural and magnetic properties of some stoichiometric nickel-zinc ferrites

Abstract

Stoichiometric Ni-Zn ferrite samples with and without dopant iue prepared with ceramic method and sintered at different temperatures. The dopants, used in this work are LilO, CaO, CrlO) and COlO). For characterization and determination of lattice parameters, X-ray diffraction is carried out and for microstructural study, optical microscopy is used. For the understanding of the magnetic properties of the samples as modified by compositional change, doping and heat treatment, Curie temperature measurements, magnetization measurements and permeability measurements are performed. X-ray diffraction results indicate that, samples are in good crystalline form. The Curie temperature measurements show that, with increasing amount of Znl+ Curie temperature decreases, but dopants appear to have little effect on this ordering temperature. The magnetization measurements reveal that the use of Li20, CaO and Cr20) increases the saturation magnetization initially, but with the increase of these dopants, there is a decrease in the value of saturation mab'lletization. In the case of C020), however, the saturation magnetization decreases with the addition of C020) all the way. From the permeability measurements, it is observed that samples with higher sintering temperature have higher permeability and dopants have apreciable effect on the permeability. Loss factors and quality factors are also determined which show compositional dependence to some extent. The experimental results of the permeability measurements are interpreted in terms of coherent and incoherent domain wall movements. It has_been found that the samples Nio) ZIIo1Fe204with 0.5% mole Li20 dopant has the best composition for higher permeability. The microstructural study reveals that, as the sintering temperature is increased the grain size is increased accordingly.