Structural and Magnetic Properties of Nanocrystalline Mg-Co Ferrites

Mg-Co nano crystalline ferrites having the general formula Mg1-x Co (x) Fe2O4 (x=0, 0.05, 0.1, 0.15, 0.2, 0.25) were prepared by the sol-gel method. X-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) were carried out to investigate the structural properties of the samples. X-ray powder diffraction patterns indicated the formation of a spinel structure of the prepared compounds. Fourier Transform Infrared (FTIR) spectroscopy of the samples confirmed the XRD results. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as a function of cobalt concentration. The dielectric constant (epsilon (r) ), dielectric loss tangent (tan delta) and ac electrical conductivity (sigma (ac)) of nanocrystalline Mg-Co ferrites were investigated as a function of frequency and Co concentration. The frequency dependence of epsilon (r) , tan delta and sigma (ac) is in accordance with the Maxwell-Wagner model. The effect of Co doping on dielectric and electric properties was explained on the basis of cations distribution in the crystal structure. The saturation magnetization M-S, remanent magnetization M-r and coercivity H-C of all samples were explained as a function of cobalt concentration on the basis of N,el's two-lattice model.