High-temperature crystal chemistry of calcite and magnesite

Markgraf, Steven A.; Reeder, Richard J.

doi:10.1107/s0108767384095556

Cited by 120 publications

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“…Previous studies on the crystal structure of carbonate minerals revealed that Mg and O form much more compact octahedra in magnesite than Ca and O do in calcite. As a result, the CO 3 groups in magnesite have far less freedom of motion than those in calcite, although the C-O interatomic distance is nearly uniform in the two minerals because of the stronger interactions between the Mg-O octahedra (56)(57)(58)(59)(60)(61). For example, the CO 3 group within the calcite structure can undergo translational, librational (i.e., rotational), or screw motions depending on the energy level of the environment (59), whereas only translational motion is allowed for the CO 3 group in magnesite (57).…”

Section: Resultsmentioning

confidence: 99%

“…As a result, the CO 3 groups in magnesite have far less freedom of motion than those in calcite, although the C-O interatomic distance is nearly uniform in the two minerals because of the stronger interactions between the Mg-O octahedra (56)(57)(58)(59)(60)(61). For example, the CO 3 group within the calcite structure can undergo translational, librational (i.e., rotational), or screw motions depending on the energy level of the environment (59), whereas only translational motion is allowed for the CO 3 group in magnesite (57). The enhanced lattice restriction in magnesite is also confirmed by the outcome of structural refinement for calcite and magnesite formed under different temperature/pressure conditions (57,(62)(63)(64)(65)(66)(67).…”

Section: Resultsmentioning

confidence: 99%

“…For example, the CO 3 group within the calcite structure can undergo translational, librational (i.e., rotational), or screw motions depending on the energy level of the environment (59), whereas only translational motion is allowed for the CO 3 group in magnesite (57). The enhanced lattice restriction in magnesite is also confirmed by the outcome of structural refinement for calcite and magnesite formed under different temperature/pressure conditions (57,(62)(63)(64)(65)(66)(67). Specifically, the C-O and O-O interatomic distances in the magnesite-CO 3 groups maintain a much higher stability when external conditions change, resulting in a lower overall distortion in the groups at higher temperature/pressure, presumably due to the stronger confinement by the highly compact and rigid Mg-O octahedra.…”

Section: Resultsmentioning

confidence: 99%

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Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems

Yan

Zhang

et al. 2013

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

146

134

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Dolomite and magnesite are simple anhydrous calcium and/or magnesium carbonate minerals occurring mostly at Earth surfaces. However, laboratory synthesis of neither species at ambient temperature and pressure conditions has been proven practically possible, and the lack of success was assumed to be related to the strong solvation shells of magnesium ions in aqueous media. Here, we report the synthesis of MgCO 3 and Mg x Ca (1−x) CO 3 (0 < x < 1) solid phases at ambient conditions in the absence of water. Experiments were carried out in dry organic solvent, and the results showed that, although anhydrous phases were readily precipitated in the water-free environment, the precipitates' crystallinity was highly dependent on the Mg molar percentage content in the solution. In specific, magnesian calcite dominated in low [Mg 2+ (1−x) CO 3 were formed. These findings exposed a previously unrecognized intrinsic barrier for Mg 2+ and CO 3 2− to develop long-range orders at ambient conditions and suggested that the long-held belief of cation-hydration inhibition on dolomite and magnesite mineralization needed to be reevaluated. Our study provides significant insight into the long-standing "dolomite problem" in geochemistry and mineralogy and may promote a better understanding of the fundamental chemistry in biomineralization and mineral-carbonation processes.sedimentary geology | carbon sequestration | nonaqueous solvent R arely is there a geological challenge that has endured as long a search for answers as the "dolomite problem" has. Identified more than 220 y ago by the French mineralogist Déodat de Dolomieu, the calcium magnesium carbonate mineral known as dolomite [CaMg(CO 3 ) 2 ] has since been synthesized repeatedly but exclusively at high-temperature and, in some instances, highpressure conditions (1-4). However, in many cases other than igneous-originated carbonatite and deep-burial dolomitization, the formation of dolomitic phases (e.g., microbial and cave deposits) are certainly not associated with such high-temperature and/or -pressure environments (5-8). This obvious discrepancy, compounded by the sharp contrast of massive ancient dolomite formations to the scarcity of modern observations, prompted an arduous search for answers for the past two centuries and, because of a lack of success, has been referred to as the dolomite problem (6, 9-16). Our inability to form dolomite at ambient conditions is hardly the only challenge in mineralogy; a similar situation exists in the case of pure magnesium carbonate [magnesite (MgCO 3 )], which has posed the same level of difficulty to nucleate and grow at room temperature and atmospheric pressure in laboratories but frequently occurs in natural sedimentary settings at earth (sub)surfaces. Interestingly, both dolomite and magnesite belong to the mineral class of anhydrous carbonates. Thus, it becomes logical to surmise that the dolomite problem and the magnesite problem probably share the same root, that is, the difficulty to incorporate unhydrated magnesium ions i...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems

Yan

Zhang

et al. 2013

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

146

134

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“…As Markgraf and Reeder (1985) first pointed out, an apparent decrease in the intramolecular C-O bond length in calcite occurs with increasing temperature in the conventional refinement. This is an artifact caused by the assumption that the constituent atoms are vibrating independently in a crystal.…”

Section: Resultsmentioning

confidence: 99%

“…Preceding Bragg's groundbreaking study, a phase transition of calcite at approximately 1243 ± 5 K had been reported by Boeke (1912). This high-temperature phase, which was named as Phase V by Mirwald (1976), has been a key controversial issue in the field of common minerals for over a hundred years (Tsuboi, 1927;Mirwald, 1979;Markgraf and Reeder, 1985;Dove and Powell, 1989;Hagen et al, 1992;Maslen et al, 1993;Dove et al, 2005;Antao et al, 2009). The structure of Phase V was finally determined in our previous study (Ishizawa et al, 2013), and is briefly reviewed here, in addition to the intermediate Phase IV that bridges Phases I and V.…”

Section: Introductionmentioning

confidence: 99%

Calcite V: a hundred-year-old mystery has been solved

Ishizawa

2014

Powder Diffr.

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Since Boeke's finding of a reversible phase transition of calcite (calcium carbonate, CaCO 3 ) at elevated temperatures [Boeke, H. E. (1912). Neues Jahrb. Mineral. 1, 91-121], and following W. L. Bragg's determination of the structure of the room-temperature Phase I [Bragg, W. L. (1914). Proc. R. Soc. Lond. A 89,, the high-temperature Phase V of calcite has been an enduring mystery. Here, we summarize a paper on the structure of Phase V [Ishizawa, N., Setoguchi, H. and Yanagisawa, K. (2013). Sci. Rep. 3, 2832], as well as the intermediate Phase IV which exists between Phases I and V, and add new aspects. An in situ single-crystal X-ray diffraction study revealed that the I-IV and IV-V transitions occurred reversibly at approximately 985 and 1240 K, respectively, in a carbon dioxide atmosphere. Phase V was stable only over a narrow temperature range between 1240 and 1275 K. The crystal decomposed immediately at temperatures above 1275 K, leaving a nanoporous calcium oxide reaction product which retained the shape of the parent calcite crystal. The I-IV transition can be described as an orientational order/disorder transition of the carbonate group, occurring within the same space group R 3c. In Phase V, the oxygen sublattice is melted. The joint-probability density function obtained from the anharmonic atomic displacement parameters of the oxygen atoms revealed that the oxygen triangles of the carbonate group in Phase V do not sit still at specified Wyckoff positions in the space group R 3m, but are instead distributed with equal probability along the undulated circular orbital about the central carbon. The carbonate group in Phase V is no longer flat on the basal plane when the oxygen triangle comes to troughs or peaks in the undulated orbital, but is instead deformed like an umbrella. Assuming that the oxygen triangle migrates about carbon, the carbonate group should repeat the umbrella inversion in Phase V as a function of time. Finally, possible thermal decomposition mechanisms of calcite are briefly discussed.

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A mechanistic growth model for inorganic crystals: Solid‐state interactions

Dandekar

Doherty

2014

AIChE Journal

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Growth shapes of inorganic crystalline solids govern material properties such as catalytic activity and selectivity, solar cell efficiency, and so forth. A systematic understanding of the crystal growth process and the solid‐state interactions within inorganic crystals should help to engineer crystal shapes. A general model that identifies periodic bond chains in inorganic crystals while accounting for the long‐range electrostatic interactions is presented. The variation in the electronic structure and the partial charges of growth units on the inorganic crystal surfaces has been captured using the bond valence model. The electrostatic interaction energies in the kink sites of inorganic crystals were calculated using a space partitioning method that is computationally efficient. This model provides a quantitative explanation for the asymmetric growth spirals formed on the (101¯4) surface of calcite. This methodology for studying solid‐state interactions can be used with a mechanistic growth model to predict the morphology of a wide variety of inorganic crystals. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3707–3719, 2014

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High-temperature crystal chemistry of calcite and magnesite

Cited by 120 publications

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Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems

Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems

Calcite V: a hundred-year-old mystery has been solved

A mechanistic growth model for inorganic crystals: Solid‐state interactions

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High-temperature crystal chemistry of calcite and magnesite

Cited by 120 publications

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Testing the cation-hydration effect on the crystallization of Ca–Mg–CO 3 systems

Testing the cation-hydration effect on the crystallization of Ca–Mg–CO 3 systems

Calcite V: a hundred-year-old mystery has been solved

A mechanistic growth model for inorganic crystals: Solid‐state interactions

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Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems

Testing the cation-hydration effect on the crystallization of Ca–Mg–CO ₃ systems