As-Li electrides under high pressure: Superconductivity, plastic, and superionic states

Inorganic electrides are a new class of compounds catering to the interest of scientists due to the multiple usages exhibited by interstitial electrons in the lattice. However, the influence of the shape and distribution of interstitial electrons on physical properties and new forms of physical states is still unknown. In this work, crystal structure search algorithms are employed to explore the possibility of forming unique electrides in the As-Li system, where interstitial electrons behave as one-dimensional (1D) electron chains (1D electride) in the Pmmm phase of AsLi₇ and transform into zero-dimensional (0D) electron clusters (0D electride) in the P6/mmm phase at 80 GPa. The P6/mmm phase has relatively high superconductivity at 150 GPa (T_c = 38.4K) compared to classical electrides, even at moderate pressure with T_c = 16.6K. In addition, a Dirac cone in the band has been observed, expanding the sources of Dirac materials. The survival of AsLi₇ at room temperature is confirmed by molecular dynamics simulation at 300 K. At 1000 K, the As atoms in the system act like a solid, while a portion of the Li atoms cycle around the As atoms, and another portion of the Li atoms flow freely like a liquid, showing the unusual physical phenomenon of the coexistence of the plastic and superionic states. This suggests that the superionic and plastic states cannot only be found in hydrides but also in the electride. Our results indicate that superconducting electride AsLi₇ with superionic and plastic states can exist in Earth’s interior.