Preparation of Ni1−xMnxFe2O4 ferrites by sol–gel method and study of their cation distribution

The spinel ferrite nanoparticles of the system Ni1−xMnxFe2O4 with x=0.0, 0.1, 0.3, 0.5, 0.7 and 0.9 were prepared by sol–gel auto combustion technique using chlorides of Ni, Mn and Fe as a source with citric acid as chelating agent. The structure of the ferrite materials and the particle size were determined by XRD, it was observed that the structure was a single phase, face centered cubic with lattice parameter ranging from 8.365 Å to 8.394 Å and the particle size ranging from 23.86 Å to 38.30 Å. The lattice parameter showed a linear dependence on concentration in accordance with the Vegardʹs law. By analyzing XRD patterns, the cation distribution over A and B-sites was estimated through the R-Factor method. The magnetic moment for each sample was determined from cation distribution on the two sites. An enhancement in the net magnetic moment was observed with gradual increase in the Mn content.