Ab initio surface phase diagram of the {104} calcite surface

Area of Science:

• Geochemistry
• Materials Science
• Surface Chemistry

Background:

• Calcite surfaces are critical in geological and industrial processes.
• Understanding calcite surface termination is key to predicting its reactivity.
• Previous studies have not fully explored calcite surface behavior under varying environmental conditions.

Purpose of the Study:

• To investigate the surface termination of the {104} calcite surface.
• To determine how temperature, pressure, and gas composition affect calcite surface structure.
• To explore the potential for nonstoichiometric terminations under atmospheric conditions.

Main Methods:

• Utilized electronic structure calculations at the density functional theory level.
• Generated a surface phase diagram to map termination changes.
• Simulated calcite surface interactions with water and carbon dioxide.

Main Results:

• Identified conditions under which nonstoichiometric calcite terminations can form.
• Demonstrated that high relative humidity can induce nonstoichiometric surfaces.
• The {104} calcite surface is susceptible to changes in termination.

Conclusions:

• Nonstoichiometric calcite surfaces can form under ambient atmospheric conditions.
• These nonstoichiometric surfaces likely play a significant role in calcite surface chemistry.
• The findings have implications for understanding mineral weathering and carbon capture technologies.