Liquid Structure of Tantalum under Internal Negative Pressure

Area of Science:

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

Background:

• Understanding the behavior of materials under extreme conditions is crucial for various scientific and industrial applications.
• Shock compression experiments provide insights into material properties at high pressures and temperatures.
• Classical nucleation theory describes the formation of new thermodynamic phases, such as liquid-gas mixtures.

Purpose of the Study:

• To investigate the liquid structure of tantalum shock released from high pressures.
• To determine the tensile stress supported by liquid tantalum.
• To provide direct experimental evidence for classical nucleation theory in high-surface-tension liquids.

Main Methods:

• In situ femtosecond x-ray diffraction measurements were employed to probe the structure of shocked tantalum.
• Ab initio molecular dynamics simulations were performed to model the behavior of liquid tantalum.
• Experiments were conducted on nanosecond timescales for shock-released tantalum from several hundred gigapascals.

Main Results:

• Liquid tantalum was found to support an internal negative pressure of -5.6 (0.8) GPa.
• Evidence of a liquid-gas mixing state due to cavitation was observed.
• The results align with predictions of classical nucleation theory for liquids with high surface tension.

Conclusions:

• The study provides the first direct experimental proof of classical nucleation theory.
• High-surface-tension liquids, like tantalum, can sustain gigapascal tensile stress.
• Cavitation in shock-released tantalum indicates a transition to a liquid-gas mixed phase.