First-principles investigation of the pressure-induced variation in the structural and physical properties of the ternary high-T_c superconductor LaBeH₈.

Authors

Siheng Li, Yuanyuan Jin, Xiangzhen Guan, Yuan Zhu, Yin Huang, Chuanzhao Zhang, Fangguang Kuang, Meng Ju

Published in

Physical chemistry chemical physics : PCCP. Jul 01, 2026. Epub Jul 01, 2026.

Abstract

A conspicuous ternary hydride Fm3̄m-LaBeH₈ superconductor with a particular Be-H alloy backbone was initially predicted in theory and subsequently synthesized experimentally with the measured superconducting critical temperature T_c of 110 K under the moderate pressure of 80 GPa. Previous investigations mainly aimed at deciphering its structural characteristics and superconductivity. Few explorations involved other physical and chemical properties, which are invaluable for its practical application. Herein, on the basis of the first-principles calculation, we comprehensively investigate the structural, bonding, mechanical, electronic, superconductive, thermophysical and optical properties for the cubic Fmm-LaBeH₈ structure under various pressures ranging from 20 to 120 GPa. The bonding essence in Fm3̄m-LaBeH₈ is theoretically predicted as the ionic La-H bond and the synthetic Be-H bond with the ionic and covalent characters, respectively. Moreover, the Fm3̄m-LaBeH₈ crystal is predicted to be thermodynamically, mechanically and dynamically stable within the considered pressures. A linear increase with the increasing pressure in elastic constants (C₁₁ and C₁₂) and bulk modulus B is achieved. More interestingly, the shear modulus G and Young's modulus E undergo a distinct and complicated variation process upon further compression, similar to those of the elastic constant C₄₄, transverse and mean sound velocities, Vickers hardness H_v and Debye temperature θ_D. The remarkable superconductivity originates from the high hydrogen-dominated electronic density of states around the Fermi energy and the overriding hydrogen contribution to the electron-phonon coupling strength. Notably, the high superconducting critical temperature T_c in the Fm3̄m-LaBeH₈ configuration stems from the combined effect of λ and ω_log. In addition, Fm3̄m-LaBeH₈ is an underlying absorbing material for the visible and UV light regions. These findings increase the understanding of the excellent superconductivity and the remaining physical properties of the LaBeH₈ superconductor, greatly stimulating enthusiasm for its synthesis for experimental researchers and broadening its practical applications.

PMID:
42383333
Bibliographic data and abstract were imported from PubMed on 01 Jul 2026.

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