title: Stable prenucleation calcium carbonate clusters.
abstract: Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate in fact contains stable prenucleation ion clusters forming even in undersaturated solution. The cluster formation can be characterized by means of equilibrium thermodynamics, applying a multiple-binding model, which allows for structural preformation. Stable clusters are the relevant species in calcium carbonate nucleation. Such mechanisms may also be important for the crystallization of other minerals.
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Research Campus Golm, Am Mühlenberg 1, D-14424 Potsdam, Germany.
authors.forename: Denis
authors.initials: D
authors.lastname: Gebauer
authors.forename: Antje
authors.initials: A
authors.lastname: Völkel
authors.forename: Helmut
authors.initials: H
authors.lastname: Cölfen
mesh_terms: D002113:Calcification, Physiologic; D002118:Calcium / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008956:Models, Chemical; D015394:Molecular Structure; D012996:Solutions; D013816:Thermodynamics
chemical_list: D002254:Carbonates; D007477:Ions; D012996:Solutions; D002119:Calcium Carbonate; D002118:Calcium