Superconducting dense lithium-based germanides with electride states

Lithium-based electrides with interstitial anionic electrons (IAEs) have recently garnered a great deal of attention, since these materials were found to host intriguing properties such as multiple IAE arrangements and potential superconductivity. In this study, we here conducted comprehensive simulations on the pressure-induced stable Li-abundant germanides leveraging the advanced first-principles structure predictions. As a consequence, our simulations identified several metallic Li-Ge electride phases with robust stability, i. e. , Li₅Ge, Li₆Ge, Li₇Ge, Li₈Ge, and Li₁₀Ge. Strikingly, the evolution from connected one-dimensional (1D) to zero-dimensional (0D) electride states of Li₅Ge was identified concurrent with an orthorhombic Cmcm to triclinic C2/c phase transition on account of compression-induced volume reduction, whereas Li₁₀Ge possesses the unusual coexistent 0D and 1D IAEs. Electron-phonon coupling (EPC) calculations uncover that the superconductivity of Cmcm Li₅Ge is superior to that of C2/c Li₅Ge at 50 GPa, which is due to the larger EPC strength, higher density of states at the Fermi level, and more pronounced softened phonon modes of Cmcm Li₅Ge. Remarkably, Li₁₀Ge was calculated to have the highest superconducting critical temperature (T₂) of 8. 5 K below 50 GPa compared to other lithium-carbon family electrides, which is ascribed to the fact that the Li 2p electron states near the Fermi energy are strongly coupled with phonon modes associated with the vibrations of Li atoms. Our findings provide insights into lithium-bearing electride systems with implications for the pursuit of distinguished electride superconductors.