Structural and Magnetic Studies on Pb4+ Substituted Cobalt Ferrite System

Abstract

The polycrystalline samples of Co_1+xPb_xFe_2-2xO₄ with x = 0.0,0.1,0.2,0.3,0.4, and 0.5 varying in the steps of 0.1 were prepared by using solid state reaction technique. The structural and magnetic properties have been investigated by means of X-ray diffraction, high field magnetization and a. c. susceptibility measurements. The X-ray analysis confirmed the single-phase formation of the samples. The distributions of divalent, trivalent and tetravalent cations among the tetrahedral (A) and octahedral (B) sites have been obtained from the observed and calculated intensity ratios. The X- ray intensity indicates that tetravalent Pb⁴⁺ ions occupy both A and B sites replacing iron ions. The added Co²⁺ ions also occupy at A sites with replacing iron ions for x = 0.0, 0.1 and 0.2 and there after very small amount of Co²⁺ migrate from A sites to B sites replacing Fe³⁺ ions for the composition x = 0.3, 0.4, 0.5. The variation of saturation magnetic moment per formula unit at room temperature with Pb⁴⁺ content is satisfactorily explained on the basis of Neel’s collinear spin ordering model for all the samples. The Curie temperatures decreases almost linearly with increase of Pb⁴⁺ content from x = 0.0 to 0.5.