Universal diamond edge Raman scale to 0.5 terapascal and implications for the metallization of hydrogen

Area of Science:

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

Background:

• Generating static pressures up to terapascal (TPa) levels enables the study of novel material properties.
• Accurate pressure evaluation above approximately 0.3 TPa remains a significant experimental challenge.
• Understanding extreme pressure effects is crucial for fields like high-temperature superconductivity and hydrogen metallization.

Purpose of the Study:

• To establish a universal high-pressure scale for accurate pressure measurements up to 0.5 TPa.
• To provide a reliable method for pressure evaluation without requiring a separate pressure sensor.
• To re-evaluate existing high-pressure data, particularly concerning the metallization of hydrogen.

Main Methods:

• Development of a high-pressure scale based on the Raman edge shift of stressed diamond anvils.
• Correlation of the Raman shift with the established equation of state for gold (Au).
• Application of the new scale to existing high-pressure experimental data, including hydrogen.

Main Results:

• A universal high-pressure scale is established, extending reliable pressure measurements up to approximately 0.5 TPa.
• The new scale indicates pressure values are approximately 20% lower at 0.5 TPa compared to extrapolations of existing scales.
• Corrected data using the new scale show consistency in the onset of proposed molecular hydrogen metallization across different studies.

Conclusions:

• The developed universal high-pressure scale provides a more accurate method for terapascal-level pressure determination.
• This new scale facilitates more reliable comparisons between experimental findings and theoretical predictions for materials under extreme pressure.
• The findings contribute to a better understanding of phenomena such as hydrogen metallization and high-temperature superconductivity.