Design of a 60.8 K superconducting hydride LiMgZr2H12 at ambient pressure via lithium substitutional doping

Abstract

High-pressure hydrogen-rich compounds have long been regarded as promising room-temperature superconductor candidates; however, their practical applications are limited by their reliance on extreme compression. This study explores hydrogen-rich superconductors that may be stable at ambient pressures. Inspired by recent investigations of the MgZrH_2n family, the LiMgZr₂H₁₂ structure with a Pmmm symmetry was constructed, and its thermodynamic, mechanical, and dynamical stability were evaluated using first-principles calculations. Electron–phonon coupling (EPC) analysis suggests that LiMgZr₂H₁₂ reaches a superconducting critical temperature (T_c) of 60.8 K at ambient pressure. Compared with MgZrH₆, the introduction of Li atoms significantly increases the contribution of hydrogen atoms to the electron density of states near the Fermi level and enhances the EPC constant (λ) of the LiMgZr₂H₁₂ structure. LiMgZr₂H₁₂ exhibits a superconducting figure of merit of 1.56, which is significantly greater than that of MgZrH₆, demonstrating its outstanding potential for practical applications. This work guides ambient-pressure design of high-T_c hydrides.