Compressing the most hydrogen-rich inorganic ion

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Hydrogen-rich compounds are promising candidates for high-temperature superconductivity.
• Understanding pressure-induced structural transitions is crucial for discovering new superconducting materials.

Purpose of the Study:

• To theoretically investigate the high-pressure phases of the ionic salt Barium Rhenium Hydride (BaReH9).
• To explore the structural evolution and metallization pathways of BaReH9 under extreme pressure.

Main Methods:

• Theoretical exploration of high-pressure phases.
• Analysis of structural distortions and coordination number changes.
• Identification of the formation and role of discrete H(2) units.

Main Results:

• BaReH9 adapts to compression via structural distortions and increased coordination.
• Discrete H(2) units form and fill interspace gaps during compression.
• This H(2) evolution dramatically lowers the metallization pressure.

Conclusions:

• BaReH9 is predicted to become metallic at 51 GPa with the onset of the H(2)-containing phase.
• The formation of H(2) units is a key mechanism for metallization in this compound.
• BaReH9 presents a potential pathway towards high-temperature superconductivity in hydrogen-rich materials.