Abstract
The effect of non-magnetic Al3+ ion doping on the magnetic properties of MnFe2-2xAl2xO4 (0 <= x <= 0.4) spinel ferrites was studied using Mossbauer spectroscopy measurements at room temperature. From the Mossbauer study, it is observed that the resolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Mossbauer spectra indicates that Fe ions are in +3 state. A paramagnetic doublet is observed at degree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to the dilution of sublattice by Al3+ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral (A) and octahedral (B) with the increase in Al concentration.