Smeets, PJM;
Finney, AR;
Habraken, WJEM;
Nudelman, F;
Friedrich, H;
Laven, J;
De Yoreo, JJ;
... Sommerdijk, NAJM; + view all
(2017)
A classical view on nonclassical nucleation.
Proceedings of the National Academy of Sciences of the United States of America
, 114
(38)
E7882-E7890.
10.1073/pnas.1700342114.
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Abstract
Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO_{3}) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO_{3} nucleation is still a topic of intense discussion, with new pathways for its growth from ions in solution proposed in recent years. These new pathways include the so-called nonclassical nucleation mechanism via the assembly of thermodynamically stable prenucleation clusters, as well as the formation of a dense liquid precursor phase via liquid–liquid phase separation. Here, we present results from a combined experimental and computational investigation on the precipitation of CaCO_{3} in dilute aqueous solutions. We propose that a dense liquid phase (containing 4–7 H_{2}O per CaCO_{3} unit) forms in supersaturated solutions through the association of ions and ion pairs without significant participation of larger ion clusters. This liquid acts as the precursor for the formation of solid CaCO_{3} in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca^{2+} + zCO_{3}^{2−} → z CaCO_{3}. The results show that all steps in this process can be explained according to classical concepts of crystal nucleation and growth, and that long-standing physical concepts of nucleation can describe multistep, multiphase growth mechanisms.
| Type: | Article |
|---|---|
| Title: | A classical view on nonclassical nucleation |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1073/pnas.1700342114 |
| Publisher version: | https://doi.org/10.1073/pnas.1700342114 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher's terms and conditions. |
| Keywords: | calcium carbonate, nucleation, crystal growth, cryo-electron microscopy, molecular simulation |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10120675 |
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