Effect of non-magnetic substitution on the structural and magnetic properties of spinel cobalt ferrite (CoFe_(2-x)Al_xO_4) ceramics

摘要

One set of CoFe_(2-x)Al_xO_4 (x = 0.1, 0.2, 0.3 and 0.4) ceramics in single domain range and another set in multi domain range were prepared by sintering at 400 and 800 ℃ respectively. Rietveld refinement of XRD patterns revealed that samples are mixed spinel structure and crystallize to Fd3m space group with cubic symmetry. The lattice constant and crystallite size decrease with the increase in Al~(3+) concentration. The Fourier transform infrared spectroscopy study confirms the spinel structure of the samples. Particle size distribution for all samples has been studied by field emission scanning electron microscopy. Moreover, thermogravimetric analysis was performed to determine the sintering temperature. The saturation magnetization has been analyzed by the "law of approach " technique. Saturation magnetization, coercivity and magnetocrystalline anisotropy constant are found to decrease with the increase in Al~(3+) ion concentration which is due to the non-magnetic impurity in the magnetic matrix.