Effect of processing parameters on the magnetic properties of Ni_0.8Zn_0.2Fe₂O₄

Abstract

Polycrystalline nickel-zinc ferrite powder has been obtained by chemical co-precipitation, involving the corresponding metal nitrates and sodium hydroxide under the different processing parameters for precipitation from those reported in our earlier paper [1, Anilkumar <i>et al., Mater Lett, </i>27(1996) 293]. The precipitate, when dried at 80°C in air shows cubic ferrite with lower values for <i>Ms </i>≈ 17.7emu/g (<i>Ms </i>≈<i> </i>44 emu/g as reported in the earlier paper

cited above). Different modes of drying such as IR drying, microwave drying do not improve <i>Ms </i>values. On the other hand, <i>Ms </i>value improves substantially when the precipitate is further

processed hydrothermally. When calcined at 1200°C/4h in air, all the samples reach 96-100% of the saturation value (<i>Ms ≈</i>77 emu/g). All these experimental results (XRD, VSM) are analyzed in terms of the microscopic inhomogeneity (structural and chemical) of the precipitated and calcined samples.