Mechanistic insights into the crystallization of amorphous calcium carbonate (ACC)

Pieter Bots, Liane G. Benning, Juan Diego Rodriguez-Blanco, Teresa Roncal-Herrero, Samuel Shaw

    Research output: Contribution to journalArticlepeer-review


    Many organisms use amorphous calcium carbonate (ACC) during crystalline calcium carbonate biomineralization, as a means to control particle shape/size and phase stability. Here, we present an in situ small- and wide-angle X-ray scattering (SAXS/WAXS) study of the mechanisms and kinetics of ACC crystallization at rapid time scales (seconds). Combined with offline solid and solution characterization, we show that ACC crystallizes to vaterite via a three-stage process. First, hydrated and disordered ACC forms, then rapidly transforms to more ordered and dehydrated ACC; in conjunction with this, vaterite forms via a spherulitic growth mechanism. Second, when the supersaturation of the solution with respect to vaterite decreases sufficiently, the mechanism changes to ACC dissolution and vaterite crystal growth. The third stage is controlled by Ostwald ripening of the vaterite particles. Combining this information with previous studies, allowed us to develop a mechanistic understanding of the abiotic crystallization process from ACC to vaterite and all the way to calcite. We propose this is the underlying abiotic mechanism for calcium carbonate biomineralization from ACC. This process is then augmented or altered by organisms (e.g., using organic compounds) to form intricate biominerals. This study also highlights the applicability of in situ time-resolved SAXS/WAXS to study rapid crystallization reactions. © 2012 American Chemical Society.
    Original languageEnglish
    Pages (from-to)3806-3814
    Number of pages8
    JournalCrystal Growth and Design
    Issue number7
    Publication statusPublished - 3 Jul 2012


    Dive into the research topics of 'Mechanistic insights into the crystallization of amorphous calcium carbonate (ACC)'. Together they form a unique fingerprint.

    Cite this