Characterization And Curie Temperature Of Co Doped Ni-Zn Perminvar Ferrite

Abstract

Ni-Zn perminvar ferrites having the compositions Co_0.02Zn_0.20Ni_0.58Fe_2.2O₄ and Co_0.02Zn_0.28 Ni_0.50Fe_2.2O₄ were prepared through the solid state reaction using conventional ceramic method. The homogeneous phase of perminvar ferrites has been observed from the study of X-ray diffraction. Lattice parameter of the samples was found to be 8.369, 8.372 and 8.375Å for the sample Co_0.02Zn_0.20Ni_0.58Fe_2.2O₄ and 8.382, 8.383 and 8.384Å for the sample Co_0.02Zn_0.28 Ni_0.50Fe_2.2O₄ sintered at 1200, 1300 and 1350°C respectively. Both the bulk density and porosity decreases with Zn content and sintering temperatures. The values of Curie temperature of the two compositions were found to be 511, 508 and 508°C (for TS = 1200, 1300 and 1350°C) for the sample of Co_0.02Zn_0.20Ni_0.58Fe_2.2O₄ and 460 and 455°C (for Ts = 1300 and 1350°C) for the sample of Co_0.02Zn_0.28Ni_0.50Fe_2.2O₄, respectively. Frequency dependence permeability spectra, revealed that permeability of all the samples is almost independent of frequency up to 1 MHz. It is observed that permeability increases with Zn content and hence the relative quality factor decreases with increasing Zn content.

Key words: Perminvar ferrite; Curie temperature; Initial permeability; Quality factor

DOI: http://dx.doi.org/10.3329/jbas.v35i2.9421

JBAS 2011; 35(2): 171-178