Magnetic Behavior of the System Mn2O3–Fe2O3

Solid solutions of Fe2O3 and Mn2O3 with the bixbyite structure may be obtained to at least 50 mole % Fe2O3. Over the whole range, the lattice parameter is essentially constant. Mössbauer spectroscopy and susceptibility measurements indicate that these solid solutions become antiferromagnetic at much lower temperatures than does Mn2O3 itself. In fact, 2 mole % Fe2O3 causes a steep drop in TN, from ∼82° to ∼40°K. However, this value remains relatively unaffected by further increase in Fe2O3 concentration. The susceptibility measurements also indicate a second transition, at about 15°K below the antiferromagnetic ones, to apparently weak ferromagnetism with extremely low residual moments (∼0.01 μB/formula unit at 4.2°K). Mössbauer spectra of the 50 mole % powdered specimen at 55 kOe and at both 24° and 9°K exhibit a small polarization of the atomic spins, which in turn suggests either a small induced or small spontaneous moment.