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.
- amorphous materials
- crystal growth
- nanostructured materials
- synchrotron radiation
Rodriguez-Blanco, J. D., Shaw, S., Bots, P., Roncal-Herrero, T., & Benning, L. G. (2012). The role of pH and Mg on the stability and crystallization of amorphous calcium carbonate. Journal of Alloys and Compounds, 536(Suppl.1), S477-S479. https://doi.org/10.1016/j.jallcom.2011.11.057