Structure of ice crystallized from supercooled water

Area of Science:

• Physical Chemistry
• Materials Science
• Geophysics

Background:

• Water's phase transitions are crucial for diverse scientific fields, including atmospheric science and cryobiology.
• At ambient conditions, ice is typically classified into stable hexagonal ice and metastable cubic ice.
• Previous research on metastable ice I focused on specific conditions like mesopores or high-pressure recrystallization.

Purpose of the Study:

• To investigate the crystalline structure of ice formed through homogeneous crystallization of supercooled water.
• To determine if this ice conforms to known hexagonal or cubic structures.
• To re-evaluate existing literature on cubic ice based on new findings.

Main Methods:

• Utilized X-ray diffraction data for structural analysis.
• Employed Monte Carlo simulations to model ice crystallization.
• Reviewed and reinterpreted previous diffraction studies on ice phases.

Main Results:

• Homogeneously crystallized ice from supercooled water is not hexagonal or cubic.
• Identified a new phase: stacking-disordered ice I, with randomly stacked cubic and hexagonal layers.
• Demonstrated that previously identified cubic ice is likely stacking-disordered ice I.

Conclusions:

• Stacking-disordered ice I is a distinct phase formed under common freezing conditions.
• Existing literature on cubic ice requires reevaluation due to widespread stacking disorder.
• Further research is needed to understand the properties of stacking-disordered ice I.