Influence of Na doping on the magnetic relaxation processes of magnetite

Abstract The relaxation of the initial magnetic permeability was measured in polycrystalline Na-doped magnetite samples, with nominal composition NaxFe3−xO4 (x ranging from 0 to 0.05), by means of the magnetic disaccommodation (DA) technique. We found that the increasing amount of Na ions modifies the DA spectra and a very different behaviour depending on the sintering atmosphere. These results were discussed in terms of the presence of Na ions in the magnetite lattice, giving rise to certain modifications in their neighbourhood.