Calcite Kinks Grow via a Multistep Mechanism

Area of Science:

• Crystallization science
• Surface chemistry
• Geochemistry

Background:

• Classical crystal growth models assume direct solute adsorption to lattice sites.
• This model simplifies the complex surface processes during mineral formation.

Purpose of the Study:

• To investigate alternative mechanisms of crystal growth beyond the classical model.
• To explore the role of intermediate adsorption sites in calcite kink growth.

Main Methods:

• Computation of free energy curves for calcium (Ca) and carbonate (CO3) ion adsorption.
• Analysis of a wide range of calcite kink types.
• Identification of growth mechanisms based on calculated free energy landscapes.

Main Results:

• Demonstrated a multistep growth mechanism for specific calcite kinks.
• Identified kinks that require sequential adsorption of two solutes to the crystal lattice.
• Found that kinks terminated by either Ca or CO3 ions can exhibit this multistep growth.

Conclusions:

• The classical model of crystal growth is insufficient to explain all observed growth phenomena.
• Multistep adsorption mechanisms play a significant role in the growth of certain mineral kinks.
• This finding has implications for understanding mineral formation in various geological and industrial settings.