TY - JOUR
T1 - A classical view on nonclassical nucleation
AU - Smeets, Paul J.M.
AU - Finney, Aaron R.
AU - Habraken, Wouter J.E.M.
AU - Nudelman, Fabio
AU - Friedrich, Heiner
AU - Laven, Jozua
AU - De Yoreo, James J.
AU - Rodger, P. Mark
AU - Sommerdijk, Nico A.J.M.
N1 - Funding Information:
Research Technology Platform (Warwick University), the MidPlus Regional e-Infrastructure Centre (Grant EP/K000128/1), and ARCHER, the UK national supercomputing service. The work of P.J.M.S. and N.A.J.M.S. is supported by a VICI grant of the Netherlands Organization for Scientific Research. The work of A.R.F. and P.M.R. was supported under Engineering and Physical Sciences Research Council Grant EP/I001514/1, and A.R.F. acknowledges support from the University of Sheffield under a Doctoral Prize Fellowship. The work of J.J.D.Y. was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering at the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the US Department of Energy under Contract DE-AC05-76RL01830. This work is dedicated to the memory of P.M.R., who sadly passed away on March 23, 2017.
Publisher Copyright:
© 2017, National Academy of Sciences. All rights reserved.
PY - 2017/9/19
Y1 - 2017/9/19
N2 - Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO3) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO3 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 CaCO3 in dilute aqueous solutions. We propose that a dense liquid phase (containing 4–7 H2O per CaCO3 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 CaCO3 in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca2+ + z CO32− → z CaCO3. 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.
AB - Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO3) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO3 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 CaCO3 in dilute aqueous solutions. We propose that a dense liquid phase (containing 4–7 H2O per CaCO3 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 CaCO3 in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca2+ + z CO32− → z CaCO3. 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.
KW - Calcium carbonate
KW - Cryo-electron microscopy
KW - Crystal growth
KW - Molecular simulation
KW - Nucleation
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U2 - 10.1073/pnas.1700342114
DO - 10.1073/pnas.1700342114
M3 - Article
C2 - 28874584
AN - SCOPUS:85029566679
SN - 0027-8424
VL - 114
SP - E7882-E7890
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 38
ER -