Control and monitoring of oxygen fugacity in piston cylinder experiments
We present a newly developed capsule design that resolves some common problems associated with the monitoring and control of oxygen fugacity ( f O 2 ) in high-pressure piston cylinder experiments. The new f O 2 control assembly consists of an AuPd outer capsule enclosing two inner capsules: one of A...
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Veröffentlicht in: | Contributions to mineralogy and petrology 2015-01, Vol.169 (1), p.1, Article 9 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We present a newly developed capsule design that resolves some common problems associated with the monitoring and control of oxygen fugacity (
f
O
2
) in high-pressure piston cylinder experiments. The new
f
O
2
control assembly consists of an AuPd outer capsule enclosing two inner capsules: one of AuPd capsule containing the experimental charge (including some water), and the other of Pt containing a solid oxygen buffer plus water. The inner capsules are separated by crushable alumina. The outer capsule is surrounded by a Pyrex sleeve to simultaneously minimise hydrogen loss from the cell and carbon infiltration from the graphite furnace. Controlled
f
O
2
experiments using this cell design were carried out at 1.0 GPa and 1,000 °C. We used NiPd, CoPd and (Ni, Mg)O
f
O
2
sensors, whose pressure sensitivity is well calibrated, to monitor the redox states achieved in experiments buffered by Re–ReO
2
, Ni–NiO and Co–CoO, respectively. Results for the
f
O
2
sensors are in good agreement with the intended
f
O
2
established by the buffer, demonstrating excellent control for durations of 24–48 h, with uncertainties less than ± 0.3 log bar units of
f
O
2
. |
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ISSN: | 0010-7999 1432-0967 |
DOI: | 10.1007/s00410-015-1105-z |