Results 141 to 150 of about 1,474 (181)
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Measurement and control of oxygen fugacity during annealing
Review of Scientific Instruments, 1984We describe a simple analog electronic circuit to measure the voltages of a thermocouple and solid electrolyte sensor and calculate and diplay the temperature and log fO2. This circuit monitors conditions in a simple annealing system where the oxygen atmosphere is controlled by continuous flow of a gas buffer.
John P. Shepherd, Charles J. Sandberg
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Oxygen fugacity controls in the Earth's upper mantle
Nature, 1990DESPITE significant progress in recent years1–3, there is still considerable debate surrounding the oxygen fugacity (fo2) of the Earth's upper mantle and the chemical reactions that buffer it. Electrochemical measurements1,3 give heterogeneous oxidation states, with one group near the fayalite–magnetite–quartz (FMQ), and the other near the iron-wustite
C. Ballhaus, R. F. Berry, D. H. Green
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The effect of oxygen fugacity on the solubility of carbon-oxygen fluids in basaltic melt
Earth and Planetary Science Letters, 1992The solubility of CO2CO fluids in a mid-ocean ridge basalt (morb) has been measured at 1200°C, 500-1500 bar, and oxygen fugacities between NNO and NNO-4. High oxygen fugacities, and thus CO2-rich fluids, were produced by using a starting material equilibrated at NNO, and Ag2C2O4 as the fluid source. Low oxygen fugacities were achieved by using graphite
Pawley, Alison R. +2 more
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Equilibrium oxygen fugacity in zinc-titanium ferrites of ideal oxygen stoichiometry
Materials Research Bulletin, 1988Abstract A thermodynamic analysis is provided to specify the oxygen equilibrium pressures in the system Znx Tiy Fe3−x−yO4 for the special case of the ideal oxygen stoichiometry O ( Zn + Ti + Fe ) , 4 3 . The principal features of the results are briefly discussed.
P. Wang, J.M. Honig
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Kaersutitic and Ti-pargasitic amphiboles and oxygen fugacity
2008Since long time kaersutite and Ti-pargasite were studied because they are retained to be useful for the estimation of fO2 and fH2 conditions of their hosting rocks (especially for mantle derived rocks and nodules). These amphiboles have currently low hydrogen (even close to 0) content than the classical 2 a.p.f.u..
Iezzi G +3 more
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The effect of hydrogen, oxygen, and water fugacity on oxygen diffusion in alkali feldspar
Geochimica et Cosmochimica Acta, 1990Abstract Oxygen self-diffusion in adularia and albite single crystals was studied hydrothermally at 650°C from 5 to 1500 MPa confining pressure using a combination of hydrogen/oxygen buffers, a hydrogen ion buffer, and variable mole fractions of water (dilution with CO2).
John R. Farver, Richard A. Yund
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Oxygen fugacity control in piston-cylinder experiments
Contributions to Mineralogy and Petrology, 2012The main goal of this study was to develop and test a capsule assembly for use in piston-cylinder experiments where oxygen fugacity could be controlled in the vicinity of the QFM buffer without H2O loss or carbon contamination of the sample material. The assembly consists of an outer Pt-capsule containing a solid buffer (Ni–NiO or Co–CoO) plus H2O and ...
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Journal of Geophysical Research, 1973
Water fugacity and oxygen fugacity can be controlled concomitantly in solid-media high-pressure apparatus by using CO2-H2O vapors and the double-capsule technique with oxygen buffers. Calculations based on an ideal-solution model yield values of the fugacities of O2, H2, and H2O in the samples.
A. L. Boettcher +2 more
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Water fugacity and oxygen fugacity can be controlled concomitantly in solid-media high-pressure apparatus by using CO2-H2O vapors and the double-capsule technique with oxygen buffers. Calculations based on an ideal-solution model yield values of the fugacities of O2, H2, and H2O in the samples.
A. L. Boettcher +2 more
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The oxygen fugacity within carbonated eclogites
2011The subduction of carbon back into the mantle is an important natural form of carbon sequestration. Eclogitic nodules and CO2-rich metasomatic agents show evidence for the passage of carbon and carbonate (solid or melts) in the mantle. Further, diamonds from kimberlites occur in eclogite xenoliths more frequently than in peridotite xenoliths but the ...
STAGNO, VINCENZO, Frost, DJ, McCammon CA
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Records of Archean mantle oxygen fugacity
Goldschmidt2023 abstracts, 2023Elizabeth Cottrell +5 more
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