The role of pH and Mg on the stability and crystallization of amorphous calcium carbonate

J.D. Rodriguez-Blanco, S. Shaw, P. Bots, T. Roncal-Herrero, L.G. Benning

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Abstract

The effects of pH and Mg on the crystallization of amorphous calcium carbonate (ACC) to vaterite and/or calcite were studied using a combination of in situ time resolved synchrotron-based techniques and electron microscopy. The experiments showed that Mg increased the stability of ACC and favoured the formation of calcite over vaterite. A neutral (∼7) starting pH during mixing promoted the transformation of ACC into calcite via a dissolution/ reprecipitation mechanism. Conversely, when ACC formed in a solution that started with a high initial pH (∼11.5), the transformation to calcite occurred via metastable vaterite, which formed via a spherulitic growth mechanism. In a second stage this vaterite transformed to calcite via a surface-controlled dissolution and recrystallization mechanism. These crystallization pathways can be explained as a consequence of the pH-dependent composition, local structure, stability and dissolution rates of ACC. © 2011 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)S477-S479
Number of pages3
JournalJournal of Alloys and Compounds
Volume536
Issue numberSuppl.1
DOIs
Publication statusPublished - 25 Sep 2012

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Keywords

  • amorphous materials
  • crystal growth
  • nanostructured materials
  • synchrotron radiation

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