A series of oxides in the Mn 3 O 4-Fe 2 O 3 system have been synthesized at 1200℃ in air,followed by quenching to room temperature.Three solid solutions,Mn 3-3x Fe 3x O 4(0.00≤x≤0.278),Mn 3-3x Fe 3x O 4(0.291≤ x≤0.667),and Mn 2-2x Fe 2x O 3(0.89≤x≤1.00),have been identified by powder X-ray diffraction(XRD).Rietveld refinement of the XRD data show that the solids belong to the hausmannite phase with the space group I4 1 /amd,the spinel phase with the space group Fd3m,and the hematite phase with the space group R3c,respectively.Between these are two-phase regions.57 Fe Mssbauer spectra indicate that the valence state of Fe in the three solid solutions is+3;in addition,there are two crystallographically independent Fe 3+ ions in the unit cells of the hausmannite and spinel phases,and one Fe 3+ in the hematite phase.Analyses of 57 Fe Mssbauer spectra and X-ray photoelectron spectra(XPS)revealed that a formula of Mn 2+ 1-x Fex3+[Mnx2+Fe 3+ x Mn 3+ 2-3x ] O 4 describes the cation distribution of both the hausmannite and spinel phases,but that for the hematite phase is Mn 3+ 2-2x Fe 3+ 2x O 3.