Femtosecond diffraction studies of solid and liquid phase changes in shock-compressed bismuth

Area of Science:

• Condensed Matter Physics
• Materials Science
• High-Pressure Physics

Background:

• Bismuth (Bi) is a model material for studying high-pressure phase transitions and melting.
• The lattice-level response of Bi to rapid (shock) compression remains poorly understood.
• The relationship between dynamically and statically compressed structures is unclear.

Purpose of the Study:

• To determine the structural response of shock-compressed Bi to 68 GPa.
• To reveal the phase transition sequence and equation-of-state under dynamic compression.
• To compare dynamic compression behavior with static compression data.

Main Methods:

• Utilized femtosecond X-ray diffraction to probe shock-compressed Bismuth.
• Achieved pressures up to 68 GPa.
• Directly measured structural changes in solid and liquid phases.

Main Results:

• Observed a marked departure from equilibrium behavior in shocked Bi.
• The incommensurate Bi-III phase was not observed; a new metastable phase formed.
• The Bi-V phase formed at significantly lower pressures than in static studies.
• Directly measured structural changes in shocked liquid Bi for the first time.

Conclusions:

• Shocked Bi exhibits unique solid-phase behavior not seen under static compression.
• Liquid Bi shows novel structural changes under shock compression.
• Findings highlight the importance of considering dynamic effects and offer insights into static vs. dynamic dataset validity.