Thermodynamic properties in a multicomponent solid solution involving cation disorder: Fe3O4-MgFe2O4-FeAl2O4 -MgAl2 O4 spinels
The spinel quaternary Fe3O4-FeAl2O4-MgFe2O4-MgAl2O4 is petrologically important but difficult to deal with thermodynamically because of complex order-disorder relations. We have used our recent measurements of Fe2+ and Fe3+ site occupancies together with measured activity-composition relations, inte...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
| Published: |
1989
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| Summary: | The spinel quaternary Fe3O4-FeAl2O4-MgFe2O4-MgAl2O4 is petrologically important but difficult to deal with thermodynamically because of complex order-disorder relations. We have used our recent measurements of Fe2+ and Fe3+ site occupancies together with measured activity-composition relations, interphase cation distributions, and solvi to develop an internally consistent thermodynamic model for this sytem. The model is based on a second-degree Taylor series expansion of the vibrational part of the Gibbs free energy in terms of order and compositional parameters. It can readily be related to the familiar Margules parameters, WGij, and reciprocal interactions commonly used to represent activities in multisite solid solutions. -from Authors |
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