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Water Dynamics from THz Spectroscopy Reveal the Locus of a Liquid–Liquid Binodal Limit in Aqueous CaCO 3 Solutions
Author(s) -
Sebastiani Federico,
Wolf Stefan L. P.,
Born Benjamin,
Luong Trung Quan,
Cölfen Helmut,
Gebauer Denis,
Havenith Martina
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201610554
Subject(s) - binodal , nucleation , aqueous solution , chemical physics , chemistry , ion , metastability , liquid liquid , isothermal process , thermodynamics , phase (matter) , chromatography , organic chemistry , phase diagram , physics
Many phenomena depend on CaCO 3 nucleation where the role of water remains enigmatic. Changes in THz absorption during the early stages of CaCO 3 nucleation evidence altered coupled motions of hydrated calcium and carbonate ions. The direct link between these changes and the continuous development of the ion activity product reveals the locus of a liquid–liquid binodal limit. The data strongly suggest that proto‐structured amorphous CaCO 3 forms through solidification of initially liquid precursors. Furthermore, polycarboxylates, which stabilize liquid precursors of CaCO 3 , significantly enhance the kinetic stability of the metastable liquid–liquid state, but they do not affect the locus of the binodal limit. The importance of water network dynamics in phase separation mechanisms can be understood based on the notions of the pre‐nucleation cluster pathway, and is likely to be more general for aqueous systems.