Electromagnetic Properties of Iron deficient Ni-Cu-Zn Ferrites and the influence of additives as sintering AID

Abstract

The present work is focused on the influence of substitutions and sintering aids on electromagnetic properties of Fe-deficient Ni-Cu-Zn ferrite. Three series of ferrite samples of the compositions (Ni0.28Cu0.10Zn0.62O) (Fe2O3)1-x (where x=0.00, 0.02, 0.04, 0.06 & 0.08), Ni0.28Cu0.10+Zn0.62-x Fe1.98O4 (where x=0.00, 0.03, 0.06, 0.09 & 0.12) and Ni0.28Cu0.10Zn0.62Fe1.98O4 doped with V2O5 and Li2O were prepared by using the solid state reaction technique. The phase identification was carried out by using the X-ray diffraction. The X-ray diffraction analysis revealed that all the samples of the studied three series were found to crystallize in single-phase cubic spinel structure. A slight increase of Curie temperature, Tc and saturation magnetization, Ms of (Ni0.28Cu0.10Zn0.62O) (Fe2O3)1-x series with increasing iron deficiency were observed. Lattice parameter of Ni0.28Cu0.10Zn0.62O) (Fe2O3)1-x series slightly decreases with x content. Initial permeability was found to increase with increasing iron deficiency and also with increasing sintering temperature which may be attributed to enhanced density and reduced anisotropy energy as well as increase in grain size of the studied samples. The permeability spectrum with frequency follows the Snoek's limit. From hysteresis parameters it was revealed that optimum soft magnetic properties corresponds to the composition with x=0.08 sintered at Ts=1150°C having highest permeability of 358, maximum induction, minimum coercivity and hysteresis losses. From the detail study on the magnetic properties of Ni0.28Cu0.10+xZn0.62-xFe1.98O4 series, it appeared that optimum soft magnetic properties were found in the composition with x=0.09 with the manifestation of highest permeability of 586 with low coercivity of 0.75 Oe and hysteresis loss of 15.5 W/kg. Saturation magnetization, M increases with x content with high value of 61.8 emu/g for x0.09. Lattice parameter decreases linearly with increasing Cu content while Curie temperature increases linearly with Cu content. The decrease of Curie temperature may be attributed to the strengthening of A-B (JAB) exchange interaction. Initial permeability increases gradually with increasing Cu content and sintering temperature, Ts attaining a maximum value for x0.09 at Ts=1200°C. This enhancement of permeability may be correlated with improved microstructural features. The effect of dopants such as V2O5 (0.4 wt %) and Li2O (0.4 wt %) on the composition Ni0.28Cu0.10Zn0.62Fe1.98O4 with Ts=1150°C revealed that a substantial increase of initial permeability from 284 to 476 for V2O5 and 380 for Li2O is observed. This may be accounted for due to increased density and grain size. A noticeable decrease of coercivity and increase of magnetization of the doped samples have been observed resulting in high permeability.