Cavity Formation in Confined Growing Crystals

Area of Science:

• Crystallography
• Materials Science
• Physical Chemistry

Background:

• Crystal growth in confined environments is crucial for understanding natural geological processes and industrial applications.
• The formation of complex crystal morphologies is often influenced by interactions with surrounding surfaces.
• Previous studies have not fully elucidated the mechanisms behind cavity formation during crystal growth against a wall.

Purpose of the Study:

• To investigate the phenomenon of cavity formation when crystals grow adjacent to a surface.
• To identify the conditions and mechanisms leading to cavity appearance during crystal growth.
• To characterize the nonequilibrium conditions governing cavity formation and its impact on crystal morphology.

Main Methods:

• Optical microscopy was used to observe sodium chlorate (NaClO_{3}) crystals growing near a glass surface.
• Thin film modeling was employed to simulate the crystal growth process in confined geometries.
• A nonequilibrium morphology diagram was constructed to map the conditions for cavity formation.

Main Results:

• Cavities form in the contact region between growing crystals and a wall when nutrient supply is insufficient in the center.
• The observed cavity formation in sodium chlorate crystals aligns with simulation results from the thin film model.
• A nonequilibrium morphology diagram successfully characterizes the conditions under which cavities appear.

Conclusions:

• Cavity formation is a general phenomenon during crystal growth against a wall, driven by limited solute transport.
• This cavity formation mechanism is fundamental to the development of growth rims observed in various experimental settings.
• The findings provide critical insights into the limitations for achieving compact crystal growth in confined spaces.