Immiscibility in the Fe3O4-FeCr2O4 spinel binary |
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Authors: | Stephen E Ziemniak Roy A Castelli |
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Institution: | Lockheed Martin Corporation, KAPL Inc., P.O. Box 1072, Schenectady, NY 12301-1072, USA |
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Abstract: | A recent thermodynamic model of mixing in spinel binaries, based on changes in cation disordering (x) between tetrahedral and octahedral sites Am. Mineral. 68 (1983) 18, 69 (1984) 733], is investigated for applicability to the Fe3O4-FeCr2O4 system under conditions where incomplete mixing occurs. Poor agreement with measured consolute solution temperature and solvus N. Jb. Miner. Abh. 111 (1969) 184] is attributed to neglect of: (1) ordering of magnetic moments of cations in the tetrahedral sublattice antiparallel to the moments of those in the octahedral sublattice and (2) pair-wise electron hopping between octahedral site Fe3+ and Fe2+ ions. Disordering free energies (ΔGD), from which free energies of mixing are calculated, are modeled by |
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Keywords: | A Magnetic materials A Oxides D Phase equilibria D Thermodynamic properties |
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