Effects of Magnesium Ions and Water Molecules on the Structure of Amorphous Calcium Carbonate: A Molecular Dynamics Study

• Published in: The journal of physical chemistry. B Vol. 117; no. 47; pp. 14849 - 14856
• Main Authors: Tomono, Hidekazu, Nada, Hiroki, Zhu, Fangjie, Sakamoto, Takeshi, Nishimura, Tatsuya, Kato, Takashi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 27.11.2013
• Subjects: Additives; Amorphous semiconductors, metals, and alloys; Calcium carbonate; Condensed matter: structure, mechanical and thermal properties; Crystal structure; Disordered solids; Exact sciences and technology; Formations; Magnesium; Molecular dynamics; Molecular structure; Physics; Simulation; Structure of solids and liquids; crystallography; Water; Magnesium additions; Local structure; Calcium carbonate; Molecular dynamics method; Short-range order; Microstructure; Amorphous state structure; Distribution functions
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp407721x

Molecular dynamics simulations were conducted to elucidate the effects of Mg2+ and H2O additives on the structure of amorphous calcium carbonate (ACC). New potential parameters for Mg2+ ions were developed. The distribution function of the angle formed by three nearest-neighbor atoms was introduced to analyze the short-range local structure of ACC. The simulation indicated that ACC had a weakly ordered local structure resembling the local structure of a CaCO3 crystal. The local structure of pure ACC resembled that of vaterite. The formation of the vaterite-like local structure was hindered by Mg2+ ions, whereas H2O molecules did not significantly influence the structure of ACC when the fraction of H2O molecules was low. However, when the fraction of H2O was high, the formation of a monohydrocalcite-like local structure was promoted. The effects of the additives on the structure of ACC were verified using the size of the additives and the interaction between the additives and CaCO3. The simulated structure of ACC was compared with the structure of CaCO3 crystals nucleated through the formation of ACC particles in real systems.