First-principles investigation of the pressure-induced variation in the structural and physical properties of the...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Ternary hydride superconductor Fm3̄m-LaBeH8 was theoretically predicted and experimentally synthesized.
• Superconducting critical temperature (Tc) of 110 K at 80 GPa was previously measured.
• Limited exploration of physical and chemical properties beyond structure and superconductivity.

Purpose of the Study:

• Comprehensively investigate structural, bonding, mechanical, electronic, superconductive, thermophysical, and optical properties of Fm3̄m-LaBeH8.
• Analyze the material's behavior under varying pressures (20–120 GPa).
• Provide insights for practical applications of this superconductor.

Main Methods:

• First-principles calculations were employed.
• Systematic investigation of material properties under pressure.
• Analysis of bonding characteristics, stability, and electronic structure.

Main Results:

• Fm3̄m-LaBeH8 exhibits ionic La-H bonds and Be-H bonds with mixed ionic-covalent character.
• The crystal is thermodynamically, mechanically, and dynamically stable across the studied pressure range.
• Elastic constants, bulk modulus, shear modulus, Young's modulus, hardness, and Debye temperature show complex pressure dependencies.
• Superconductivity is attributed to high hydrogen-dominated electronic density of states and electron-phonon coupling.
• The material shows absorption in visible and UV light regions.

Conclusions:

• First-principles calculations confirm the stability and diverse properties of Fm3̄m-LaBeH8.
• The study elucidates the origins of its high superconducting critical temperature.
• Findings expand the understanding of LaBeH8, encouraging further experimental synthesis and application exploration.