Effect of yttrium doping on structure, magnetic and electrical properties of nanocrystalline cobalt ferrite

Tailoring of properties by changing morphology or by doping is very much required for the suitable application of any materials. Here we report the effect of yttrium doping on microstructure, magnetic and electrical properties of cobalt ferrite nanoparticles prepared through citrate auto-ignition method. Rietveld refinement analysis of X-ray diffraction pattern confirms the growth of pure and single phase cobalt ferrite nanoparticles which corroborates with transmission electron microscopy (TEM) study. Microstructural parameters, obtained from Rietveld analysis showed that oxygen vacancy is maximum and inter-ionic bond lengths and bond angles attain optimum values for 15 mol% yttrium doped sample. An observed value of saturation magnetization indicates the existence of spin canting phenomenon which was explained by Yafet-Kittel model. Magnetic parameters such as anisotropy constant, anisotropy field have been estimated using Law of Approach (L.A.) formalism. Existence of interparticle dipolar interaction (IPDI) in the system was established with the help of M_r/M_s ratio around room temperature. Maximum electrical conductivity has been observed for the 15 mol% doped sample as estimated from Mott's 3-D V.R.H. model, which can be attributed to the optimum values of microstructural parameters at this composition.