Fine Structure of α-Al2O3-Based Solid Solutions

The fine structure of solid solutions between isomorphic p-block and 3dtransition-metal oxides was investigated experimentally and theoretically in the technologically important systems α-Al2O3–M2O3(M = Ti, V, Cr, Fe). It was shown that the thermodynamic theory of isomorphic miscibility and conventional approaches to estimating solubility limits fail to explain and, at best, only predict the phase relations in the systems examined. The proposed magnetochemical method offers the possibility of studying in detail the M–M interactions in first-row oxides M2O3and (MxAl1 – x)2O3solid solutions, probing their homogeneity, and revealing their salient structural features. The marked difference in the solubilities of isomorphic M2O3oxides in α-Al2O3is interpreted in terms of the magnetic structure of the oxides.