Magnetic and Mössbauer Studies on Nanostructured CoCrFeO₄ (0 = x = 1) Spinel Ferrites Prepared by Sol-Gel Auto-Combustion Method.

Low temperature preparation of nanostructured CoCrFeO₄ (0<x <1) spinel ferrites has been successfully achieved via citric acid assisted sol-gel method at 350 °C. Phase purity and structural studies were investigated using XRD and IR spectroscopy. Lattice parameters of the spinel ferrites decrease with the progressive increase in Cr content (x) in CoCr FeO₄. IR bands at ~600 cm and ~400 cm confirm distinct metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. Average crystallite sizes and SEM particle sizes were found to be in the range of 25-13 nm and 86-117 nm for CoCrFeO₄ materials, respectively. The values of saturation magnetizations () and coercivities (H) decreases, i.e., from 73.8 emu/g to 16.8 emu/g and from 1467 Oe to 71 Oe, with the increase in the value of x, i.e., from = 0 to = 1.0, in CoCrFeO₄, respectively. The observed changes in magnetic properties have been explained on the basis of altered composition, magnetic structure, fine particle size, and surface effects. These results are also supported by our Mössbauer spectroscopic investigation.