Thermodynamics of the Redox Equilibria and the Site Preference in(Fe1−yAly)3−δO4
- 1 April 1979
- journal article
- research article
- Published by Oxford University Press (OUP) in Bulletin of the Chemical Society of Japan
- Vol. 52 (4) , 1019-1026
- https://doi.org/10.1246/bcsj.52.1019
Abstract
In order to elucidate the defect model in the spinel ferrites, the nonstoichiometry in magnetite and its solid solutions, (Fe1−yAly)3−δO4, (y=0.0, 0.25, 0.33), was determined at temperatures between 1300 and 1550 °C. The redox equilibria between Fe2+ and Fe3+ and the site preference of Fe2+, Fe3+, and Al3+ ions and cation vacancies were investigated and sixteen kinds of models were examined. The “best” model was chosen using the criteria that the dependence of the equilibrium constant on δ and y should be as small as possible. In the selected model, Fe2+ ions on B-sites are regarded as electron donors in a narrow 3-d band formed by Fe ions in B-sites. The following expression for the defect equilibrium was found:Keywords
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