ON EFFECTS OF PARTIAL SUBSTITUTION OF FE BY GA IN SRFE12O19

The saturation magnetization σ and the Mössbauer γ-absorption for Ga substituted ferrites having composition SrFe12-x Ga x O19 have been measured. The obtained data allowed us to choose between different hypotheses about the order of substitution of Fe3+ ions by Ga3+ ions in various iron sublattices. By applying a model of calculation which takes into account the influence of the substitution on the superexchange interactions between the nonsubstituted Fe3+ ions we have deduced a theoretical curve of σ vs. x in agreement with the measured σ values. A discrepancy between the experimental values of σ and those deduced from our data on the hyperfine magnetic fields at the iron nuclei suggested the hypothesis of the existence of angles between the orientation of the Fe3+ magnetic moments. The Mössbauer spectra have also shown that in the Ga substituted strontium ferrites, the Fe3+ ions in 12 K sublattice do not have the same magnetic moment. We given an interpretation of this fact. © 1968 Società Italianadi Fisica.