Novel superconducting structures of BH₂ under high pressure

Area of Science:

• Condensed matter physics
• Materials science
• Computational chemistry

Background:

• Boron hydrides are complex compounds with diverse structures.
• Understanding their behavior under extreme pressure is crucial for materials science.

Purpose of the Study:

• To predict novel boron hydride structures at high pressures (50-400 GPa).
• To investigate the electronic and superconducting properties of predicted phases.

Main Methods:

• Utilized the genetic algorithm (GA) for structure prediction.
• Employed first-principles density functional theory (DFT) for electronic structure calculations.
• Performed electron-phonon coupling calculations to assess superconductivity.

Main Results:

• BH4 and BH5 were found to be thermodynamically unstable.
• Two new BH2 structures (Cmcm and C2/c symmetries) were identified, featuring 2D boron sheets.
• The Cmcm-BH2 phase showed small band gaps at 50-150 GPa.
• The C2/c-BH2 phase exhibited metallic behavior at 200-400 GPa.
• Superconducting critical temperatures (Tc) for C2/c-BH2 were estimated between 28.18-37.31 K at 250 GPa.

Conclusions:

• High pressure stabilizes novel boron hydride structures.
• The C2/c-BH2 phase is a promising candidate for high-temperature superconductivity.
• Computational methods are effective for discovering new materials under extreme conditions.