Effect of Zn substitution on magnetic properties of nanocrystalline cobalt ferrite

The Zn substituted cobalt ferrite nanoparticles having the generic formula Co1-xZnxFe2O4 (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 degrees C to remove water molecules and then annealed at 725 degrees 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 Zn2+ ions considerably changes the magnetic properties. Neel'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. (C) 2010 American Institute of Physics. [doi:10.1063/1.3499346]