Abstract
Infrared spectra of magnesite, MgCO3, have been measured in the diamond anvil cell from 0 to 60 GPa at 300 K. Mode shifts were determined for the in-plane bend, the asymmetric-stretch, and the out-of-plane bend of the carbonate group, as well as a magnesium ion translational mode. The in-plane bend shows a small positive shift and ultimately merges with the out-of-plane bend, exhibiting an accidental degeneracy by 60 GPa. The asymmetric stretch exhibits highly nonlinear behavior, shifting monotonically to pressures of ~30 GPa, at which point its shift markedly decreases to ~50 GPa. At 50 GPa, it again shifts strongly with pressure. We calculate force constants for the carbonate group under pressure from our data, and correlate these with the C-O bond length. Our data are consistent with a slight lengthening (~0.01 Å) of the C-O bond between 30 and 50 GPa to a maximum bond distance of ~1.27 Å. Although our finding of bond lengthening is in general agreement with previously published Rietveld refinements of X-ray diffraction data for magnesite under pressure, our data indicate that the lengthening is likely substantially smaller than previously proposed. The expansion of the C-O bond in magnesite can be produced by rotations of the MgO6 octahedra, and such non-ionic crystalchemical effects may be a key contributor to the remarkable stability of R3̅c-structured carbonates to very high pressures.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- Absolute quantification by powder X-ray diffraction of complex mixtures of crystalline and amorphous phases for applications in the Earth sciences
- Detrital illite crystals identified from crystallite thickness measurements in siliciclastic sediments
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- The effect of zoned garnet on metapelite pseudosection topology and calculated metamorphic P-T paths
- Low-pressure and low-temperature K-bearing kosmochloric diopside from the Osayama serpentinite mélange, SW Japan
- Dehydration of natural stilbite: An in situ FTIR study
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- Letter: An infrared study of carbon-oxygen bonding in magnesite to 60 GPa
- Letter: Metals in quartz-hosted melt inclusions: Natural facts and experimental artifacts
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Articles in the same Issue
- Presidential Address To The Mineralogical Society Of Amrica, Boston, November 6, 2001: Some Precambrian Banded Iron-Formations (BiIFs) From Around The World: Their Age, Geologic Setting, Mineralogy, Metamorphism, Geochemistry, And Origin
- Effects of high pressure and high temperature on cation ordering in magnesioferrite, MgFe2O4, using in situ synchrotron X-ray powder diffraction up to 1430 K and 6 GPa
- Raman spectroscopy and vibrational analyses of albite: From 25 °C through the melting temperature
- A new occurrence of xitieshanite [Fe3+(SO4)Cl⋅6H2O] crystals in acid-mine seepways, Green Valley, Vigo County, Indiana, U.S.A.
- Effect of A-site cation radius on ordering of BX6 octahedra in (K,Na)MgF3 perovskite
- Crystal chemistry of NaMgF3 perovskite at high pressure and temperature
- Hyperfine electric field gradient tensors at Fe2+ sites in octahedral layers: Toward understanding oriented single-crystal Mössbauer spectroscopy measurements of micas
- Does the bazhenovite structure really contain a thiosulfate group? A structural and spectroscopic study of a sample from the type locality
- Light-induced degradation dynamics in realgar: in situ structural investigation using single-crystal X-ray diffraction study and X-ray photoelectron spectroscopy
- Absolute quantification by powder X-ray diffraction of complex mixtures of crystalline and amorphous phases for applications in the Earth sciences
- Detrital illite crystals identified from crystallite thickness measurements in siliciclastic sediments
- High-temperature density of lanthanide-bearing Na-silicate melts: Partial molar volumes for Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, and Yb2O3
- Coupled dichotomies of apatite and fluid composition during contact metamorphism of siliceous carbonate rocks
- The effect of zoned garnet on metapelite pseudosection topology and calculated metamorphic P-T paths
- Low-pressure and low-temperature K-bearing kosmochloric diopside from the Osayama serpentinite mélange, SW Japan
- Dehydration of natural stilbite: An in situ FTIR study
- Structural changes accompanying the phase transformation between leadhillite and susannite: A structural study by means of in situ high-temperature single-crystal X-ray diffraction
- Optic properties of centimeter-sized crystals determined in air with the spindle stage using EXCALIBRW
- Zoltaiite, a new barium-vanadium nesosubsilicate mineral from British Columbia: Description and crystal structure
- Mn-tourmaline from island of Elba (Italy): Crystal chemistry
- Letter: An infrared study of carbon-oxygen bonding in magnesite to 60 GPa
- Letter: Metals in quartz-hosted melt inclusions: Natural facts and experimental artifacts
- Letter: A high-pressure phase transition of calcite-III
- Letter: Experimental observation of an interface-controlled pseudomorphic replacement reaction in a natural crystalline pyrochlore
- Letter: A natural scandian garnet