In-situ infrared spectra of OH in rutile up to 1000 °C

Guo, Haihao

doi:10.1007/s00269-017-0881-6

Cited by 6 publications

(7 citation statements)

References 17 publications

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“…The use of a disordered model is supported by a range of experimental and theoretical work. The experimental results of Colasanti et al (2011) on solubility of OH in rutile are consistent with multi-site random mixing behavior as are in situ FTIR measurements of rutile that reveal a large degree of dissociation of OH from Ti 3+ and Al at elevated temperatures (Khomenko et al 1998;Guo 2017). First principles calculations have shown that hydrogen is expected to dissociate from Al even at low temperatures (Bjørheim et al 2010).…”

Section: Solution Modelsupporting

confidence: 71%

Aluminum solubility in rutile (TiO2)

Hoff

Watson

2021

Phys Chem Minerals

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The solubility of aluminum in rutile has been studied in the systems Al 2 O 3 -TiO 2 -H 2 O and Al 2 O 3 -SiO 2 -TiO 2 -H 2 O at 700-1200 °C and 0.075-3.3 GPa. Electron probe microanalysis (EPMA) measurements of rutile crystals grown in equilibrium with corundum show that the concentration of Al increases with increasing temperature, pressure, and oxygen fugacity. Solubility is enhanced by the addition of Nb and reduced by the addition of trivalent cations. These results are consistent with the substitution of Al 3+ for Ti 4+ on normal cation sites and the simultaneous incorporation of positively charged hydrous defects for charge compensation. Parameters for a thermodynamic model of Al substitution in rutile are calculated and the merits of using the model as a geochemical tool are discussed.

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Section: Solution Modelsupporting

confidence: 71%

Aluminum solubility in rutile (TiO2)

Hoff

Watson

2021

Phys Chem Minerals

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“…Always consult and cite the final, published document. See http:/www.minsocam.org or GeoscienceWorld the in situ FTIR spectra at elevated temperatures in this study, we do not find a coupled growth and decline of OH bands as in rutile, anorthoclase or talc (Zhang et al 2006;Yang et al , 2015Guo 2017). This suggests that protons do not transfer easily between sites in the clinopyroxenes with increasing temperature up to 1000 o C.…”

Section: Implications Hydrogen Speciation and Sites In The Clinopyroxmentioning

confidence: 46%

“…Yang and Keppler (2011) reported that hydrogen defects assigned to Si vacancies in olivine were unstable with increasing temperature. and Guo (2017) have reported that water speciation in rutile at room temperature is not representative of that at high temperatures relevant for subduction zones or upper mantle conditions. Yang et al (2015) and Liu et al (2018) found unquenchable transferring of hydrogen defects between sites in anorthoclase with increasing temperature.…”

Section: Introductionmentioning

confidence: 99%

Nature of hydrogen defects in clinopyroxenes from room temperature up to 1000 °C: Implication for the preservation of hydrogen in the upper mantle and impact on electrical conductivity

Yang

Ingrin

Xia

et al. 2019

American Mineralogist

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Water incorporated as hydrogenated defects in mantle minerals can influence physical properties of the mantle. Knowledge of hydrogen defects at high temperatures (T) is fundamental to understand and quantify their influence on mantle physical properties. Clinopyroxene contributes significantly to the upper mantle water budget. Here, we investigate the behavior of hydrogen defects in ten natural clinopyroxene crystals at temperatures up to 1000 o C, using in situ and quenched experiments. The in situ high T Fourier transform infrared (FTIR) spectra indicate no proton transfer between point defects, but the local environments of hydrogen defects vary. Dehydration rates at 1000 o C of the six samples with different chemical compositions are calculated based on the quenched experiments. These rates are not only slightly site-specific, but also increase with Fe and tetrahedrally coordinated Al contents. Indeed, the Near-FTIR spectra suggest that the dehydration of the samples in this study involves oxidation of Fe 2+. For two diopsides with a mantle affinity, the diffusivity is about 10 −12 m 2 /s at 1000 °C. The results mainly have the following implications: (1) the different local environments of hydrogen defects between high T and low T may be responsible for the different mechanism of water impact on This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title. American Mineralogist, in press.

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“…Syntheses of rutile under reducing conditions reveal that hydrogen couples to oxygen vacancies, forming OH. 5,10 Numerous infrared studies have demonstrated consistent OH bond polarization, 11−13 but a comprehensive description of the interaction between oxygen vacancies and hydrogen has not been reported. Ambiguity still surrounds the orientation of the OH bond with respect to crystal axes.…”

mentioning

confidence: 99%

“…Despite the importance of hydrogen to the defect chemistry and material properties of rutile, much remains unknown about the specifics surrounding the incorporation of hydrogen into rutile. Syntheses of rutile under reducing conditions reveal that hydrogen couples to oxygen vacancies, forming OH. , Numerous infrared studies have demonstrated consistent OH bond polarization, − but a comprehensive description of the interaction between oxygen vacancies and hydrogen has not been reported. Ambiguity still surrounds the orientation of the OH bond with respect to crystal axes.…”

mentioning

confidence: 99%

Structure, Energetics, and Spectra for the Oxygen Vacancy in Rutile: Prominence of the Ti–H_O–Ti Bond

Palfey

Rossman

Goddard

2021

J. Phys. Chem. Lett.

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Under reducing conditions, rutile TiO2 develops O vacancies (VO) coupled to Ti3+ centers. It is favorable for H atoms to enter this system, either forming OH groups or occupying vacancy sites (denoted HO) that bond to two Ti atoms next to the vacancy. OH defects are well documented by the presence of infrared modes at ∼3300 cm–1, while HO is relatively underinvestigated. We report the energies, geometries, and vibrational frequencies of hydrogen defects in rutile predicted from quantum mechanics calculations, focusing on the coexistence of OH and HO. We find that HO is more stable than OH by 1.42 eV, leading to an infrared mode at ∼1200 cm–1. Introducing a second H forms an OH bond with an infrared mode at ∼3300 cm–1. These results suggest that assessments of hydrogen storage in mantle phases of rutile and similar minerals based on OH bands may significantly underestimate H concentrations.

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In-situ infrared spectra of OH in rutile up to 1000 °C

Cited by 6 publications

References 17 publications

Aluminum solubility in rutile (TiO2)

Aluminum solubility in rutile (TiO2)

Nature of hydrogen defects in clinopyroxenes from room temperature up to 1000 °C: Implication for the preservation of hydrogen in the upper mantle and impact on electrical conductivity

Structure, Energetics, and Spectra for the Oxygen Vacancy in Rutile: Prominence of the Ti–H_O–Ti Bond

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In-situ infrared spectra of OH in rutile up to 1000 °C

Cited by 6 publications

References 17 publications

Aluminum solubility in rutile (TiO2)

Aluminum solubility in rutile (TiO2)

Nature of hydrogen defects in clinopyroxenes from room temperature up to 1000 °C: Implication for the preservation of hydrogen in the upper mantle and impact on electrical conductivity

Structure, Energetics, and Spectra for the Oxygen Vacancy in Rutile: Prominence of the Ti–HO–Ti Bond

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Structure, Energetics, and Spectra for the Oxygen Vacancy in Rutile: Prominence of the Ti–H_O–Ti Bond