Metastable Room-Temperature Superconductivity in a Chemically Pre-Compressed Lithium- Magnesium-Boron Hydride Clathrate Li2 Mg B2H18

Abstract

Giustino Travaglini

The realization of room-temperature superconductivity at ambient pressure remains the ultimate goal of condensed matter physics. While high-pressure superhydrides (e.g., La H10) have achieved high critical temperatures (Tc), they lose stability upon decompression. Here, I predict a novel ternary clathrate structure, Li2 Mg B2H18, designed to maintain high-Tc superconductivity at 0GPa via a “kinetic locking” mechanism. First-principles calculations reveal that a rigid Boron-Magnesium host lattice can chemically confine dense hydrogen clusters, mimicking the effects of external pressure. I estimate a Tc of ~298 K driven by strong electron-phonon coupling (λ ≈2.6). Furthermore, I propose a cryogenic decompression protocol (“Cryo-Lock”) to synthesize and stabilize this metastable phase for ambient- pressure operation.

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