The defect structure of divalent Mg-doped material was examined by means of the Rietveld structure refinement of X-ray powder diffraction data. The results showed that the Mg2+ ions occupied vacant interstitial octahedral sites as well as being substituted at 2 adjacent octahedral Fe3+ sites in the corundum-like oxide structure. The structure therefore involved a linear cluster of three Mg2+ ions which replaced two Fe3+ ions. Interatomic potential calculations indicated that this was the most energetically favorable defect cluster in this system.

Structural Characterization of Divalent Magnesium-Doped α-Fe2O3. F.J.Berry, A.Bohorquez, C.Greaves, J.McManus, E.A.Moore, M.Mortimer: Journal of Solid State Chemistry, 1998, 140[2], 428-30