Phase Transition of Cubic Ice to Hexagonal Ice during Growth and Decomposition

Area of Science:

• Materials Science
• Crystallography
• Physical Chemistry

Background:

• Ice exhibits diverse polymorphism, with hexagonal ice (Ih), cubic ice (Ic), and stacking-disordered ice (Isd) being the most studied.
• Understanding ice phase transitions is critical for cloud science, climate modeling, and cryogenic technology.
• The molecular mechanisms governing ice formation and phase changes are not fully understood.

Purpose of the Study:

• To investigate ice formation at different temperatures using cryogenic transmission electron microscopy.
• To explore the role of crystal defects in ice polymorphic phase transitions.
• To elucidate the size-dependent phase shift from cubic ice (Ic) to stacking-disordered ice (Isd).

Main Methods:

• Cryogenic transmission electron microscopy (cryo-TEM) was employed to observe ice formation.
• Ice samples were studied at two distinct temperatures to analyze phase behavior.
• Electron beam radiation was used to induce and study phase transitions.

Main Results:

• A size-dependent phase shift from cubic ice (Ic) to stacking-disordered ice (Isd) was observed at different temperatures.
• A metastable cubic phase within Isd transitioned to a hexagonal phase under electron beam irradiation.
• Perfect crystalline Ic did not undergo phase transition, highlighting the role of defects in transitions.

Conclusions:

• Crystal defects play a crucial role in facilitating polymorphic phase transitions in ice.
• Findings offer novel insights into controlling ice phase during growth and cubic-to-hexagonal transitions.
• This research advances the understanding of ice's complex behavior under varying conditions.