Effect of Zn substitution on magnetic properties of nanocrystalline cobalt ferrite

The Zn substituted cobalt ferrite nanoparticles having the generic formula Co 1 − x Zn x Fe 2 O 4 ( x = 0.0 - 0.7 ) were prepared by wet chemical coprecipitation technique using analytical reagent (AR) grade sulphates. The prepared samples were heated at 150 ° C to remove water molecules and then annealed at 725 ° C for 16 h. Investigation of the structural properties were carried out using x-ray diffraction, transmission electron microscopy (TEM), and scanning electron microscopy techniques. The nanocrystalline nature of the samples is confirmed by TEM data. Substitution of the nonmagnetic Zn 2 + ions considerably changes the magnetic properties. Néel's model fails to explain the observed magnetic behavior above x = 0.2 . For x ≥ 0.2 the Yafet-Kittel model can be fitted. AC susceptibility measurements confirm the decrease in Curie temperature.