Scanning-induced growth on single crystal calcite with an atomic force microscope

Area of Science:

• Materials Science
• Surface Science
• Crystallography

Background:

• Calcite (CaCO3) crystal growth is crucial for geological and biological processes.
• Understanding crystal growth mechanisms, especially at the nanoscale, is essential for materials engineering.
• Surface defects and growth kinetics influence the properties of crystalline materials.

Purpose of the Study:

• To investigate the effect of atomic force microscope (AFM) scanning on localized crystal growth of CaCO3.
• To explore the relationship between solution supersaturation and tip-enhanced deposition.
• To demonstrate the role of ledge diffusion in calcite crystal formation.

Main Methods:

• In situ atomic force microscopy (AFM) was used to scan the (1014) surface of single-crystal CaCO3 in supersaturated solutions.
• Controlled contact forces and varying supersaturation levels were employed during AFM scanning.
• Growth patterns and deposition rates were analyzed at different scanning conditions.

Main Results:

• AFM scanning significantly enhanced CaCO3 deposition along existing steps at low contact forces.
• Enhanced deposition increased with solution supersaturation, enabling the filling of etch pits.
• Tip-induced growth produced defect-free surfaces at AFM resolution, unlike high supersaturation conditions without scanning.

Conclusions:

• AFM scanning is a powerful tool for controlling and enhancing localized crystal growth.
• Tip-induced deposition highlights the critical role of ledge diffusion in calcite crystal growth.
• This technique offers a method to create defect-free surfaces and study crystal growth mechanisms at the nanoscale.