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Thermodynamic properties of alloys of gold-74/palladium-26 with variable amounts of iron and the use of Au-Pd-Fe alloys as containers for experimental petrology

Balta, Brian J. and Beckett, John R. and Asimow, Paul D. (2011) Thermodynamic properties of alloys of gold-74/palladium-26 with variable amounts of iron and the use of Au-Pd-Fe alloys as containers for experimental petrology. American Mineralogist, 96 (10). pp. 1467-1474. ISSN 0003-004X. https://resolver.caltech.edu/CaltechAUTHORS:20111101-091711413

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Abstract

Iron oxide-alloy equilibration experiments were conducted in H_2-CO_2 gas mixtures at 1 atm and 1125–1240 °C using strips of Au_(74)Pd_(26) (wt%) and produced Au-Pd-Fe alloys with 0.03–13 wt% iron. A thermodynamic calibration for the mixing of Au_(74)Pd_(26) with iron using an asymmetric regular solution leads to WG_(-Fe) = –45.0 ± 1.8 kJ/mol and WG_(-AuPd) = +19.5 ± 7.7 kJ/mol (1σ). Internal oxidation of iron was observed in a reversal experiment, suggesting that oxygen can be transferred across capsule boundaries during high-temperature experiments. This thermodynamic calibration is applicable to a wide range of oxygen fugacities and iron activities relevant to petrological and metallurgical applications at 1 atm and, as previous studies suggest excess volumes in this system are small, it can also be used to predict Fe activities in experiments at elevated pressure (up to 3 GPa). By pre-doping Au-Pd capsules to match Fe activities expected for the sample during an experiment, it is possible to maintain samples with little to no loss of iron. Pre-saturation of the capsule also provides a method for controlling the oxygen fugacity of samples if no formal oxygen buffer is available.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.2138/am.2011.3637DOIUNSPECIFIED
http://ammin.geoscienceworld.org/cgi/content/abstract/96/10/1467PublisherUNSPECIFIED
ORCID:
AuthorORCID
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2011 by Mineralogical Society of America. Manuscript received June 25, 2010. Manuscript accepted May 11, 2011. Manuscript handled by Charles Lesher. The authors thank J.K. Wicks and A.K. Matzen for their help with the 1 atm furnace experiments, and J.H. Jones and T.L. Grove for comments. This work was supported by the NSF Ocean Sciences Marine Geology and Geophysics program, Grant numbers OCE-0241716 and OCE-0550216, and NASA Grant number NNG04GG14G.
Funders:
Funding AgencyGrant Number
NSF Ocean Sciences Marine Geology and Geophysics programOCE-0241716
NSF Ocean Sciences Marine Geology and Geophysics programOCE-550216
NASANNG04GG14G
Subject Keywords:Gold-palladium, capsules, iron, internal oxidation
Issue or Number:10
Record Number:CaltechAUTHORS:20111101-091711413
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111101-091711413
Official Citation:Balta, J. Brian, Beckett, John R., Asimow, Paul D. Thermodynamic properties of alloys of gold-74/palladium-26 with variable amounts of iron and the use of Au-Pd-Fe alloys as containers for experimental petrology American Mineralogist 2011 96: 1467-1474
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27546
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:01 Nov 2011 16:37
Last Modified:03 Oct 2019 03:24

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