57Fe Mossbauer study of CoCrxFe2-xO4 nano ferrite

We report sol gel auto-combustion synthesized CoCrxFe2-xO4 (x = 0.0 - 1.0) spinel ferrites, and use x-ray diffraction 'XRD', magnetic measurements, and Mossbauer spectroscopy to study the effect of Cr-content on their structural properties, magnetic properties, and correlation between them. Formation of single-phase nono spinel ferrite (grain size: 18.1 - 46.6 nm), is confirmed by XRD. Results show that with increasing Cr-content, lattice parameter decreases, and Cr3+ ions remain more populated on B-site, whereas Co2+ ions remains almost equally populated on both A, B site, show lower disorder, and modification of A-O - A, B- O - B, A-O - B super-exchange interaction. For Cr-content >= 0.75, Mossbauer measurements show presence of a non-magnetic doublet, and isomer shift values confirm that Fe has 3 + oxidation state. Observed structural changes, lead to reduction of saturation magnetization, coercivity.