Thermal behaviors of amorphous calcium carbonates prepared in aqueous and ethanol media

Koga, Nobuyoshi; Yamane, Yuko

doi:10.1007/s10973-008-9110-3

Cited by 46 publications

(73 citation statements)

References 59 publications

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“…These data support previous studies (18,19) indicating that ACC is indeed metastable with respect to any of the crystalline calcium carbonate phases. Both hydrated and dehydrated ACC are high-energy metastable phases and there is a big energetic driving force for their crystallization.…”

Section: Discussionsupporting

confidence: 92%

“…1). Two diffuse maxima centered at 20 and 45°2θ are common features for the ACC phase and were previously observed (19,20). The variable temperature powder XRD patterns of the synthetic ACC-1, 4, and 5 samples indicate that ACC persists up to 330°C (see Fig.…”

Section: Resultssupporting

confidence: 71%

“…Abiotically, ACC is easily formed by mixing aqueous solutions at or below room temperature. These solutions can be totally inorganic or they can contain small organic species which affect the formation and persistence of ACC (13)(14)(15)(16)(17)(18)(19)(20). Increasing interest in CO 2 sequestration has led to proposals and pilot projects in which large plumes of supercritical carbon dioxide would be introduced into deep saline aquifers (21)(22)(23)(24)(25).…”

mentioning

confidence: 99%

“…Two forms, anhydrous transient ACC and a hydrated ACC containing about 1 mol of water that persists for longer time periods exist in biogenic sources (4,9,10,27). The chemically precipitated ACC is also variable in particle size and water content and transforms to a less hydrated or anhydrous form upon heating before crystallization sets in (18,19,28). A central question, which the present work addresses, is the nature of the compositional, structural, and energetic similarities and differences among different ACC samples (both chemically and biologically produced) and their transformations with heating.…”

mentioning

confidence: 99%

“…Wan et al observed two calorimetric peaks corresponding to formation of a transient ACC and its transformation to a crystalline phase. In addition, there are three reports of thermally induced crystallization of ACC to calcite at approximately 320°C using differential scanning calorimetry (DSC) (18,19,38).…”

mentioning

confidence: 99%

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Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Radha

Forbes

Killian

et al. 2010

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

422

449

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Amorphous calcium carbonate (ACC) is a metastable phase often observed during low temperature inorganic synthesis and biomineralization. ACC transforms with aging or heating into a less hydrated form, and with time crystallizes to calcite or aragonite. The energetics of transformation and crystallization of synthetic and biogenic (extracted from California purple sea urchin larval spicules, Strongylocentrotus purpuratus) ACC were studied using isothermal acid solution calorimetry and differential scanning calorimetry. Transformation and crystallization of ACC can follow an energetically downhill sequence: more metastable hydrated ACC → less metastable hydrated ACC ⇒ anhydrous ACC ∼ biogenic anhydrous ACC ⇒ vaterite → aragonite → calcite. In a given reaction sequence, not all these phases need to occur. The transformations involve a series of ordering, dehydration, and crystallization processes, each lowering the enthalpy (and free energy) of the system, with crystallization of the dehydrated amorphous material lowering the enthalpy the most. ACC is much more metastable with respect to calcite than the crystalline polymorphs vaterite or aragonite. The anhydrous ACC is less metastable than the hydrated, implying that the structural reorganization during dehydration is exothermic and irreversible. Dehydrated synthetic and anhydrous biogenic ACC are similar in enthalpy. The transformation sequence observed in biomineralization could be mainly energetically driven; the first phase deposited is hydrated ACC, which then converts to anhydrous ACC, and finally crystallizes to calcite. The initial formation of ACC may be a first step in the precipitation of calcite under a wide variety of conditions, including geological CO 2 sequestration. amorphous calcium carbonate (ACC) | calorimetry | crystallization enthalpy | sea urchin larval spicules | synthetic and biogenic ACC

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Section: Discussionsupporting

confidence: 92%

Section: Resultssupporting

confidence: 71%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Radha

Forbes

Killian

et al. 2010

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

422

449

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Amorphous Calcium Carbonate is Stabilized in Confinement

Stephens

Ladden

Meldrum

et al. 2010

Adv Funct Materials

174

208

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Biominerals typically form within localized volumes, affording organisms great control over the mineralization process. The influence of such confinement on crystallization is studied here by precipitating CaCO3 within the confines of an annular wedge, formed around the contact point of two crossed half‐cylinders. The cylinders are functionalized with self‐assembled monolayers of mercaptohexadecanoic acid on gold. This configuration enables a systematic study of the effects of confinement since the surface separation increases continuously from zero at the contact point to macroscopic (mm) separations. While oriented rhombohedral calcite crystals form at large (>10 µm) separations, particles with irregular morphologies and partial crystallinity are observed as the surface separation approaches the dimensions of the unconfined crystals (5–10 µm). Further increase in the confinement has a significant effect on the crystallization process with flattened amorphous CaCO3 (ACC) particles being formed at micrometer separations. These ACC particles show remarkable stability when maintained within the wedge but rapidly crystallize on separation of the cylinders. A comparison of bulk and surface free‐energy terms shows that ACC cannot be thermodynamically stable at these large separations, and the stability is attributed to kinetic factors. This study therefore shows that the environment in which minerals form can have a significant effect on their stability and demonstrates that ACC can be stabilized with respect to the crystalline polymorphs of CaCO3 by confinement alone. That ACC was stabilized at such large (micrometer) separations is striking, and demonstrates the versatility of this strategy, and its potential value in biological systems.

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Wasser: Wie beeinflusst es die CaCO₃‐Bildung?

Amstad

2019

Angewandte Chemie

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Nature produces biomineral‐based materials with a fascinating set of properties using only a limited number of elements. This set of properties is obtained by closely controlling the structure and local composition of the biominerals. We are far from achieving the same degree of control over the properties of synthetic biomineral‐based composites. One reason for this inferior control is our incomplete understanding of the influence of the synthesis conditions and additives on the structure and composition of the forming biominerals. In this Review, we provide an overview of the current understanding of the influence of synthesis conditions and additives during different formation stages of CaCO3, one of the most abundant biominerals, on the structure, composition, and properties of the resulting CaCO3 crystals. In addition, we summarize currently known means to tune these parameters. Throughout the Review, we put special emphasis on the role of water in mediating the formation of CaCO3 and thereby influencing its structure and properties, an often overlooked aspect that is of high relevance.

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Thermal behaviors of amorphous calcium carbonates prepared in aqueous and ethanol media

Cited by 46 publications

References 59 publications

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Amorphous Calcium Carbonate is Stabilized in Confinement

Wasser: Wie beeinflusst es die CaCO₃‐Bildung?

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Thermal behaviors of amorphous calcium carbonates prepared in aqueous and ethanol media

Cited by 46 publications

References 59 publications

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

Amorphous Calcium Carbonate is Stabilized in Confinement

Wasser: Wie beeinflusst es die CaCO3‐Bildung?

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Wasser: Wie beeinflusst es die CaCO₃‐Bildung?