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Bromiley et al. 2004
Bromiley, G., Hilaret, N. and McCammon, C. (2004). Solubility of hydrogen and ferric iron in rutile and TiO2 (II): Implications for phase assemblages during ultrahigh-pressure metamorphism and for the stability of silica polymorphs in the lower mantle. Geophysical Research Letters 31: doi: 10.1029/2004GL019430. issn: 0094-8276.

The solubility of hydrogen in Fe2O3-doped rutile and TiO2 (II) at 1100¿C has been experimentally determined. H incorporation in rutile is coupled to substitution of Fe3+ onto the octahedral Ti4+ site. In contrast, TiO2 (II) contains no structurally-incorporated hydrogen. The dominant Fe3+ incorporation mechanism in both phases is unrelated to H content, and involves substitution of Fe3+ onto octahedral Ti4+ sites, charge-balanced by oxygen vacancies. Substitution of Fe2O3 into TiO2 (II) stabilizes the structure to much lower pressures than in the pure TiO2 system. Results indicate that Al-bearing stishovite could act as an important carrier of water in subducting oceanic crust, but that formation of the post-stishovite phase with the α-PbO2 structure would represent a significant dehydration event at the base of the lower mantle.

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Abstract

Keywords
Mineralogy and Petrology, Crystal chemistry, Mineral Physics, Defects, Mineral Physics, High-pressure behavior, Mineral Physics, Optical, infrared, and Raman spectroscopy, Tectonophysics, Planetary interiors (5430, 5724)
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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