THERMODYNAMIC DATA FOR FE-BEARING PHASES OBTAINED USING NOBLE METAL ALLOYS AS REDOX SENSORS
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dc.contributor.author | Woodland A.B. | |
dc.contributor.author | O'Neill H.S.C. | |
dc.date.accessioned | 2020-12-17T04:11:32Z | |
dc.date.available | 2020-12-17T04:11:32Z | |
dc.date.issued | 1997 | |
dc.identifier | https://elibrary.ru/item.asp?id=275022 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 1997, , 20, 4359-4366 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/20967 | |
dc.description.abstract | The technique of using noble metal alloys as redox sensors has been adapted for use in hydrothermal experiments in the piston-cylinder apparatus at the reduced conditions of the iron-wustite (IW) buffer. The required high fH2 was maintained for several days using thick-walled (0.5 mm) Ag outer capsules. Such conditions permit the Gibbs free energy of Fe2+-bearing phases to be obtained from the composition of the co-existing alloy. The Ir-Fe system is more amenable than either Pt-Fe or Pd-Fe since only one phase (γ-fcc) is stable in this system over a large temperature range, and the solubility of Ag (capsule material) in Ir is negligible.Experiments with the assemblage fayalite-quartz-Fe (in alloy) (QFI) were used as a test of the method by comparison with the electrochemical measurements of O'Neill (1987a). The resulting agreement demonstrates the utility of the method between 700 and 1000°C at ~ 10 kbar. Further experiments with FeSiO3-bearing assemblages (ferrosilite-quartz-iron, PYQI, and ferrosilite-fayalite-iron, PYFAI) indicate the method is viable up to 20 kbar and between 700°C and 1000°C. However, small systematic deviations of about 1-2 kJ per mole of O2 in the quartz-saturated experiments are interpreted to indicate that the high solubility of SiO2 at high pressures may result in a lowering of the H2O activity in the co-existing supercritical fluid phase. | |
dc.title | THERMODYNAMIC DATA FOR FE-BEARING PHASES OBTAINED USING NOBLE METAL ALLOYS AS REDOX SENSORS | |
dc.type | Статья |
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