Magnetic and Moessbauer spectral studies of nano crystalline cobalt substituted magnesium ferrites (MgxCo1-xFe2O4)

Nano size MgxCo1-xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) ferrites have been prepared using sol gel method and characterized using i.r., TEM, XRD, magnetic and Moessbauer spectral studies. The particle size of as obtained samples was found to be ∼6 nm, which increases up to ∼80 nm after annealing at 1,000oC. The saturation magnetization decreases from 80.0-27.5 emu/g on increasing the Mg2+ ions after annealing at 1,000oC due to the diamagnetic behaviour of the Mg2+ ions. Room temperature (RT) Moessbauer spectra (MS) of as obtained samples exhibit a broad doublet, suggesting super paramagnetic nature of the sample. However, annealed samples exhibited a broad sextet, resolved into two sextets, corresponding to tetrahedrally and octahedrally coordinated Fe cations.