Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
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Nathalie Bolfan-Casanova
,
Hans Keppler
Abstract
Hydrous MgSiO3 akimotoite (ilmenite-type structure), containing 350 ppm wt H2O as hydroxyl, was synthesized at 19 GPa and 1300 °C in a multi-anvil apparatus. Polarized Fourier-transform infrared spectra show bands at 3300 and 3320 cm-1 due to hydroxyl groups oriented nearly perpendicular to the c axis as well as a strong band at 3390 cm-1 caused by OH molecules aligned nearly parallel to c. Unpolarized infrared measurements performed up to 13.8 GPa in a diamond anvil cell show that the bands shift to lower frequencies with increasing pressure, which is consistent with hydrogen bonding. At ~9 GPa, the bands initially at 3300 and 3320 cm-1 merge, suggesting that these two bands represent the same type of hydroxyl group. The compression behavior of the infrared bands shows that the pressure derivative of the frequency, dʋ/dP, decreases with increasing initial wavenumber, ʋio, and this decrease is not linear. These observations are consistent with the compression mechanism of akimotoite, as previously published. The data indicate that the relative compressibility of the hydrogen bonds within a structure (i.e., the sign of dʋ/dP vs. ʋio) is governed by a combination of the directionality of the hydrogen bonds and the anisotropy of compression, whereas the rate of compression (i.e., the slope of dʋ/dP vs. ʋio) is a function of the bulk modulus.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Formation of secondary pyrite and carbonate minerals in the Lower Williams Lake tailings basin, Elliot Lake, Ontario, Canada
- Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
- High-pressure IR-spectra and the thermodynamic properties of chloritoid
- Infrared and Raman study of interlayer anions CO32–, NO3–, SO42– and ClO4– in Mg/Al-hydrotalcite
- Effect of Fe oxidation state on the IR spectra of Garfield nontronite
- High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d →I4̅3d symmetry at 5 GPa
- The high-temperature P21/c-C2/c phase transition in Fe-free pyroxene (Ca0.15Mg1.85Si2O6): Structural and thermodynamic behavior
- Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite)
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- Surface structures, stabilities, and growth of magnesian calcites: A computational investigation from the perspective of dolomite formation
- Spinels and other oxides in Mn-rich rocks from the Hutter Mine, Pittsylvania County, Virginia, U.S.A.: Implications for miscibility and solvus relations among jacobsite, galaxite, and magnetite
- An occurrence of igneous orthorhombic amphibole, Eriksberg gabbro, southern Sweden
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- The crystal structures of cesanite and its synthetic analogue—A comparison
- Disordered distribution of Cu in the crystal structure of leightonite, K2Ca2Cu(SO4)4 · 2H2O
- Neustädtelite and cobaltneustädtelite, the Fe3+ - and Co2+ -analogues of medenbachite
- Ciprianiite and mottanaite-(Ce), two new minerals of the hellandite group from Latium (Italy)
- Re-definition, nomenclature and crystal-chemistry of the hellandite group
- The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite
- Letters. Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt
- Experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite
- Quantifying surface areas of clays by atomic force microscopy
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