Predicted Superconductivity in the Electride Li<sub>5</sub>C
Zenner S. Pereira, Giovani M. Faccin, E. Z. da Silva
Abstract
Superconductivity under pressure is a very important research path for finding new superconductors, and electrides have been shown to present superconductivity under pressure. In the present work, using density functional theory (DFT) in association with the particle swarm search method (PSO), we discovered a remarkable electride superconductor Li5C with P6/mmm symmetry. This newly predicted material has stability in the range from 50 to 210 GPa, confirmed by phonon analysis and ab initio molecular dynamics. This electride has a two-dimensional (2D) hexagonal anionic electron topology, creating connected electronic channels in the interstitial sites of the crystal. We also show that Li5C has a significant conventional electron–phonon coupling with superconducting critical temperatures (Tc) estimated up to 48.3 K at 210 GPa, which is the highest Tc value already reported for lithium–carbon compounds and one of the highest known transition temperatures predicted for electrides. Even at moderate pressure (50 GPa), this material shows a relatively high Tc value (14.2 K).