Ternary superconducting hydrides stabilized via Th and Ce elements at mild pressures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• High-pressure hydrides like H3S and LaH10 show high superconducting critical temperatures (Tc).
• Their application is limited by extremely high pressures (above 150 GPa).
• Achieving room-temperature superconductivity near ambient pressure remains a significant challenge.

Purpose of the Study:

• To computationally design novel ternary hydrides.
• To stabilize superconducting phases of beryllium hydrides (Be-H) near ambient pressure.
• To investigate the potential of heavy metals (Th, Ce) for pre-compression.

Main Methods:

• Theoretical calculations of chemically "pre-compressed" Be-H systems using heavy metals Thorium (Th) and Cerium (Ce).
• Prediction of thermodynamic stability and superconducting properties.
• Solution of anisotropic Migdal-Eliashberg equations to determine critical temperatures (Tc).

Main Results:

• Prediction of a stable fluorite-type structure for ThBeH8 and CeBeH8 at high pressures (69 GPa and 76 GPa, respectively).
• Calculated Tc of 113 K for ThBeH8 and 28 K for CeBeH8 at near-ambient pressures (7 GPa and 13 GPa, respectively).
• Identification of the crucial role of Be-H vibrations in electron-phonon coupling and structural stability.

Conclusions:

• ThBeH8 and CeBeH8 are promising candidates for high-temperature superconductors at significantly reduced pressures.
• The "pre-compression" strategy using heavy metals effectively stabilizes superconductivity.
• Findings provide guidance for experimental synthesis of ternary hydride superconductors under milder conditions.