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Abstract
Two systems of mixed ferrite samples were prepared by conventional ceramic method. The first system has a chemical formula Ni0.4 Cu0.2 Zn0.4 Alx Fe2-x O4 (x=0.0 to x=0.15 with step 0.025) while the chemical formula of the second one is Ni0.4 Cu0.2 Zn0.4 Crx Fe2-x O4 (x=0.0 to x=0.15 with step 0.025). XRD, SEM, FTIR and porosity measurements are carried out to investigate the physical properties of the samples. The saturation magnetization is obtained using the vibrating sample magnetometer (VSM). The temperature dependence of initial permeability (μi) is measured and hence the Curie temperatures (Tc) are determined. The composition dependence of dc electrical resistivity (ρ) at room temperature is measured. X-ray analysis showed that all samples are formed in a single spinel phase. The lattice
parameter (a) of the two systems is found to decrease with increasing Al/Cr-concentration. Both
the porosity (P %) and average grain size are decreased with increasing Al/Cr-concentration in
the two systems . In the Ni0.4 Cu0.2 Zn0.4 Alx Fe2-x O4 system the magnetization and initial
permeability showed a maximum at x=0.05 while in the Ni0.4 Cu0.2 Zn0.4 Crx Fe2-x O4 system both of the magnetization and initial permeability decreased with increasing Cr-content. The Curie
temperature of the first system is found to be constant with increasing Al- concentration, but in the second system it is decreased with increasing Cr- concentration. The dc electrical resistivity (ρ) is increased with increasing Al- concentration in the first system, as well as happened with
increasing Cr- concentration in the second system.