Effect of Cation Distribution on the Structural and Magnetic Properties of Mg Substituted Nanosized Manganese Ferrites

In the present investigation, A series of Mg-Mn ferrite nanopowders with composition MgxMn1-xFe2O4 (with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by the co-precipitation method. Thereafter, the obtained powders were pressed separately to form pellets, and sintered at 1250 degrees C for 3 h at air atmosphere. Finally, the samples were characterized by X-ray Diffraction (XRD) technique, Scanning Transmission Electron Microscopy (STEM), Alternating Gradient Force Magnetometer (AGFM) and Curie temperature measuring instrument. The lattice constant and distribution of cation in the tetrahedral and octahedral sites have been deduced through XRD data analysis. The XRD pattern confirmed the existence of single phase of cubic spinel crystal structure with the lattice parameter ranging from 8.49 angstrom (for MnFe2O4) to 8.35 angstrom (for MgFe2O4). This behavior was attributed to the ionic radii. STEM micrographs exhibit that the particles are spherically shaped and agglomerated with particle size ranging 50-90 nm quite consistent with particle size obtained from XRD data. The average crystallite size was 70 nm. Magnetization decreases with increasing Mg concentration except for x = 0.2, where it shows increasing trend. Curie temperature measurements exhibit increasing trend with increase in magnesium content. The variation of the saturation magnetization and Curie temperature with increasing concentration of the Mg2+ ions can be explained on the basis of cation distribution, strengthening A-B interaction and Neel's two sub-lattice.