Electric Field-Controlled Crystallizing CaCO3 Nanostructures from Solution

Calcium carbonate: controlled synthesis, surface functionalization, and nanostructured materials

Calcium carbonate (CaCO₃) is an important inorganic mineral in biological and geological systems. Traditionally, it is widely used in plastics, papermaking, ink, building materials, textiles, cosmetics, and food. Over the last decade, there has been rapid development in the controlled synthesis and surface modification of CaCO₃, the stabilization of amorphous CaCO₃ (ACC), and CaCO₃-based nanostructured materials. In this review, the controlled synthesis of CaCO₃ is first examined, including Ca²⁺-CO₃^2- systems, solid-liquid-gas carbonation, water-in-oil reverse emulsions, and biomineralization. Advancing insights into the nucleation and crystallization of CaCO₃ have led to the development of efficient routes towards the controlled synthesis of CaCO₃ with specific sizes, morphologies, and polymorphs. Recently-developed surface modification methods of CaCO₃ include organic and inorganic modifications, as well as intensified surface reactions. The resultant CaCO₃ can then be further engineered via template-induced biomineralization and layer-by-layer assembly into porous, hollow, or core-shell organic-inorganic nanocomposites. The introduction of CaCO₃ into nanostructured materials has led to a significant improvement in the mechanical, optical, magnetic, and catalytic properties of such materials, with the resultant CaCO₃-based nanostructured materials showing great potential for use in biomaterials and biomedicine, environmental remediation, and energy production and storage. The influences that the preparation conditions and additives have on ACC preparation and stabilization are also discussed. Studies indicate that ACC can be used to construct environmentally-friendly hybrid films, supramolecular hydrogels, and drug vehicles. Finally, the existing challenges and future directions of the controlled synthesis and functionalization of CaCO₃ and its expanding applications are highlighted.

Hierarchical CaCO3 particles self-assembled from metastable vaterite and stable calcite during the decomposition of Ca(HCO3)2

When Ca(HCO₃)₂ solution is put at 80 °C, ACC initially formed grow into calcite, aragonite and vaterite particles. The trunk of snow-shaped particles are self-assembled from hexagonal vaterite particles by one or more steps, followed by the filling in the pores of snow-shaped particles by small crystals.

Molecular dynamics simulation for the impact of an electrostatic field and impurity Mg2+ions on hard water

A detailed analysis of the structural parameters and dynamic parameters of hard water solutions under an external electrostatic field was performed by molecular dynamics (MD) simulations with the presence of impurity Mg²⁺ions.