Effects of Mn Substitution on Crystallographic and Magnetic Properties of Li-Zn-Cu Ferrites

The crystallographic and magnetic properties of gallium-substituted cobalt ferrite (CoGa x Fe 2-x O₄) were investigated. The new material was synthesized using conventional ceramic methods, with gallium substituted for ferrite in the range of x = 0.0 to 1.0, in steps of 0.2. X-ray diffraction and Mossbauer spectroscopy were used to confirm the presence of crystallized particles in the CoGa x Fe 2-x O₄ ferrite powders. All of the samples exhibited a single phase with a spinel structure, and the lattice parameters decreased as the gallium content increased. The particle size of the samples also decreased as gallium increased. For x ≤ 0.4, the Mossbauer spectra of CoGa x Fe 2-x O₄ could be fitted with two Zeeman sextets, which are the typical spinel ferrite spectra of Fe 3+ with A- and B-sites. However, for x ≥ 0.6, the Mossbauer spectra could be fitted with two Zeeman sextets and one doublet. The variation in the Mossbauer parameters and the absorption area ratio indicated a cation distribution of (Co 0.2-0.2x Ga x Fe 0.8-0.6x )[Co 0.8+0.2x Fe 1.2-0.4x ]O₄, and the magnetic behavior of the samples suggested that the increase in gallium content led to a decrease in the saturation magnetization and in the coercivity.