Effect of La3+ substitution on the structural and magnetocrystalline anisotropy of nanocrystalline cobalt ferrite (CoFe2-xLaxO4)

CoFe2-xLaxO4 (x = 0.0, 0.025, 0.05, 0.075 and 0.1) samples with different crystallite sizes have been synthesized by the citrate precursor method. All the XRD patterns could be analyzed by the Rietveld refinement technique using the Fd (3) over barm space group. The cations distribution between the tetrahedral (A-site) and octahedral sites (B-site) has been estimated by Rietveld analysis. The refinement results show that La3+ ions have strong preference for octahedral sites (B-sites). The presence of Co, Fe, La and O ions in the sample has been obtained by energy dispersive spectroscopy (EDS) with the help of Field Emission Scanning Electron Microscopy (FE-SEM). The saturation magnetization has been analyzed by the "Law of Approach (LA)" technique. The saturation magnetization, magnetic coercivity and magnetocrystalline anisotropy constants are found to decrease with the increase of La3+ concentration. The saturation magnetization, coercivity and magnetocrystalline anisotropy constants increase with the increase of crystallite size. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.