A novel crystallization pathway for SiGe alloy rapid cooling

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Understanding the solidification of covalent systems is crucial for developing comprehensive theories.
• Rapid cooling processes significantly influence the structural evolution of materials.

Purpose of the Study:

• To investigate the crystallization process of silicon-germanium (SiGe) alloys under rapid cooling.
• To elucidate the underlying mechanisms of phase transitions in covalent systems.

Main Methods:

• Molecular dynamics simulations were employed to model the crystallization of SiGe alloys.
• Analysis focused on bond saturation, orientation, and atomic rearrangement during cooling.

Main Results:

• Three distinct phase transitions were observed during SiGe crystallization.
• A novel critical-nuclei crystalline (CNC) phase was identified, characterized by increasing local diamond structures.
• The CNC phase is stable and its temperature range depends on cooling rate and atomic composition.

Conclusions:

• The study reveals a new crystallization pathway involving the CNC phase, applicable to materials like carbon.
• This pathway explains the formation of diamond under conditions without high pressure.
• Findings advance the understanding of phase transitions in covalently bonded materials.