EXPERIMENTAL DETERMINATION OF THE ACTIVITY OF CHROMITE IN MULTICOMPONENT SPINELS
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dc.contributor.author | Kessel R. | |
dc.contributor.author | Beckett J.R. | |
dc.contributor.author | Stolper E.M. | |
dc.date.accessioned | 2021-12-28T06:33:21Z | |
dc.date.available | 2021-12-28T06:33:21Z | |
dc.date.issued | 2003 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=4703919 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2003, 67, 16, 3033-3044 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/33861 | |
dc.description.abstract | We determined activity-composition relationships in Pt-Cr and Pt-Fe-Cr alloys at 1300°C experimentally and used the results to constrain the thermodynamic properties of chromite-picrochromite spinels. The Pt-Cr binary is characterized by strong negative deviations from ideality throughout the investigated composition range and the activity-composition relationship can be fit by a four-suffix asymmetric regular solution with three binary interaction parameters. The ternary alloy was modeled as a four-suffix asymmetric regular solution; the three ternary interaction parameters in this model were constrained by combining interaction parameters for the three bounding binaries taken from this and previous work with results for a set of experiments in which the activity of Cr in Pt-Fe-Cr-alloys was fixed by coexisting Cr2O3 at known fO2.The free energy of formation of FeCr2O4 at 1300°C was determined using the activities of Fe and Cr in Pt-alloys in equilibrium with oxide mixes of FeCr2O4 and Cr2O3. The free energy of formation of chromite from Fe+Cr2O3+O2 is -202.7 +/- 0.4 kJ/mol (1σ), indistinguishable from literature values. The corresponding free energy of formation of FeCr2O4 from the elements is -923.5 +/- 2.1 kJ/mol (1σ), and the enthalpy of formation at 298 K is -1438 kJ/mol. The activity-composition relationship for the chromite component in (Fe,Mg)Cr2O4 solid solutions was determined from a set of experiments in which Pt-alloys were equilibrated with spinel + Cr2O3. (Fe,Mg)Cr2O4 spinels are nearly ideal at 1300°C; modeling our data with a one-site symmetric regular solution yields an interaction parameter of +2.14 +/- 0.62 kJ/mol (1σ), similar to values based on data from the literature. | |
dc.subject | spinel | |
dc.title | EXPERIMENTAL DETERMINATION OF THE ACTIVITY OF CHROMITE IN MULTICOMPONENT SPINELS | |
dc.type | Статья |
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