Magnetic Ordering and Mn3+ Ion Surroundings in (Mn1−xFex)2O3

The crystal structures of α-Mn2O3 and (Mn1−xFex)2O3, x=0.017 and 0.63, have been refined from single crystal x-ray data. Interatomic distances and angles in (cubic) (Mn0.983Fe0.017)2O3 are equal to the analogous average distances and angles in α-Mn2O3. There is significantly less distortion of the oxygen polyhedra about 24(d) sites in (Mn0.37Fe0.63)2O3 than in (Mn0.983Fe0.017)2O3. Evidence based on these results and on magnetic studies of systems (Mn1−xMx)2O3, M≡Fe3+, Sc3+, Ga3+, Cr3+ supports the suggestion that the antiferromagnetic ordering temperatures depend on the allowed distortion of the Mn3+ ion surroundings. The paper entitled ``Structures of α-Mn2O3, (Mn0.983Fe0.017)2O3 and (Mn0.37Fe0.63)2O3 and Relation to Magnetic Ordering'' from which this has been taken will be published in Acta Crystallographica (probably in the first half of 1971). Two other especially pertinent references are: R. W. Grant, S. Geller, J. A. Cape, and G. P. Espinosa, Phys. Rev. 175, 686 (1968); S. Geller and G. P. Espinosa, Phys. Rev. 131, 3763 (1970).