Structure and Thermodynamics of Gaseous Oxides, Hydroxides, and Mixed Oxohydroxides of Chromium:  CrOm(OH)n(m,n= 0−2) and CrO3. A Computational Study

Espelid, Øystein; Børve, Knut J.; Jensen, Vidar R.

doi:10.1021/jp9830427

Cited by 21 publications

(24 citation statements)

References 54 publications

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“…Whether gas–liquid exchange between CrO 2(g) and CrO (l) can drive the condensed phase to isotopically light compositions requires knowledge of the force constants of Cr–O bonds in both CrO (l) and CrO 2(g), neither of which are available. To remedy this, we calculated the reduced partition function ratio of 53 Cr/ 52 Cr substitution in the diatomic molecule CrO (g) in the harmonic approximation ( 49 ), given the Cr–O vibrational frequency of 864 cm −1 ( 50 ). Then, bond valence theory was used in the electrostatic description of bonding with Born–Landé potentials ( 51 ) to predict the mean bond strength of CrO (g) .…”

Section: Isotopic Fractionation Of Chromium During Planetary Formatiomentioning

confidence: 99%

Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes

Sossi

Moynier

Zuilen

2018

Proc. Natl. Acad. Sci. U.S.A.

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SignificanceWith the exception of volatile elements, which are strongly depleted and isotopically fractionated, the Moon has chemical and isotopic signatures that are indistinguishable from Earth’s mantle. Reconciliation of these properties with Moon formation in a high-energy giant impact invokes evaporative loss of volatile elements, but at conditions that are poorly known. Chromium isotopic fractionation is sensitive to temperature variations and liquid–gas equilibration during evaporation. We measure an isotopic difference between Earth’s mantle and the Moon, consistent with the loss of a Cr-bearing, oxidized vapor phase in equilibrium with the proto-Moon. Temperatures of vapor loss required are much lower than predicted by recent models, implying that volatile elements were removed from the Moon following cooling rather than during a giant impact.

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Section: Isotopic Fractionation Of Chromium During Planetary Formatiomentioning

confidence: 99%

Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes

Sossi

Moynier

Zuilen

2018

Proc. Natl. Acad. Sci. U.S.A.

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“…While the Cr 2 O 3 -H 2 O-O 2 system has been studied extensively, the identity of the predominant volatile oxyhydroxide species was still uncertain and there was little agreement on the thermodynamic stability of these species. 29,34,37,38 A recent study clarifi es some of these issues. 39 Transpiration experiments were conducted at 600°C as a function of both water vapor and oxygen partial pressure at 0.1 MPa total pressure.…”

Section: Cr 2 O 3 + H 2 O(g)mentioning

confidence: 99%

“…Using Ebbinghaus' data the authors have calculated the equilibrium partial pressure of volatile Cr-O-H species from the reaction of chromia with 10 -2 MPa water vapor partial pressure and 10 -2 MPa oxygen partial pressure to show the complexity of the system as shown in Figure 4. Espelid et al 38 have made ab-initio calculations for a variety of Cr-O-H species. There is a considerable degree of uncertainty in these results, due to the large number of possible electronic states available to chromium, as is true for all transition metal compounds.…”

Section: Cr 2 O 3 + H 2 O(g)mentioning

confidence: 99%

Predicting oxide stability in high-temperature water vapor

Opila

Jacobson

Myers

et al. 2006

JOM

192

118

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High-Temperature Protection Research SummaryThe importance of understanding and predicting the interactions of oxides with water vapor at high temperatures is demonstrated in this article. Methods for observing volatilization phenomena and identifying the chemical formulae for volatile metal hydroxides are discussed. In addition, techniques for obtaining accurate thermodynamic data for gaseous metal hydroxide species are described. Detailed examples of the stability of the principle structural and/or protective oxides chromia (Cr 2 O 3 ), silica (SiO 2 ), and alumina (Al 2 O 3 ) in high-temperature water vapor are included.

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“…33 Gn-like variants have sparingly been used to compute energies of TM systems. [47][48][49] The philosophy behind creating the ccCA model chemistry is to efficiently provide energies in an easy-to-use "black box" manner akin to the Gn methods, but similar in accuracy to more expensive large basis coupled cluster approaches. The ccCA, calibrated against >375 main group energies, 35 has been shown to yield chemically accurate thermodynamic predictions for s-block metal complexes (compounds that can be difficult to model with Gn and Wn composite methods) 50,51 without the need to modify the ccCA scheme.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Computational Thermochemistry of Transition Metal Species

et al. 2007

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The correlation consistent Composite Approach (ccCA), which has been shown to achieve chemical accuracy ((1 kcal mol -1 ) for a large benchmark set of main group and s-block metal compounds, is used to compute enthalpies of formation for a set of 17 3d transition metal species. The training set includes a variety of metals, ligands, and bonding types. Using the correlation consistent basis sets for the 3d transition metals, we find that gas-phase enthalpies of formation can be efficiently calculated for inorganic and organometallic molecules with ccCA. However, until the reliability of gas-phase transition metal thermochemistry is improved, both experimentally and theoretically, a large experimental training set where uncertainties are near (1 kcal mol -1 (akin to commonly used main group benchmarking sets) remains an ambitious goal. For now, an average deviation of (3 kcal mol -1 appears to be the initial goal of "chemical accuracy" for ab initio transition metal model chemistries. The ccCA is also compared to a more robust but relatively expensive composite approach primarily utilizing large basis set coupled cluster computations. For a smaller training set of eight molecules, ccCA has a mean absolute deviation (MAD) of 3.4 kcal mol -1 versus the large basis set coupled-clusterbased model chemistry, which has a MAD of 3.1 kcal mol -1 . However, the agreement for transition metal complexes is more system dependent than observed in previous benchmark studies of composite methods and main group compounds.

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Structure and Thermodynamics of Gaseous Oxides, Hydroxides, and Mixed Oxohydroxides of Chromium: CrO_m(OH)_n(m,n= 0−2) and CrO₃. A Computational Study

Cited by 21 publications

References 54 publications

Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes

Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes

Predicting oxide stability in high-temperature water vapor

Quantitative Computational Thermochemistry of Transition Metal Species

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