First-Principles Prediction of New Electrides with Nontrivial Band Topology Based on One-Dimensional Building Blocks

We introduce a new class of electrides with nontrivial band topology by coupling materials database searches and first-principles-calculations-based analysis. Cs₃O and Ba₃N are for the first time identified as a new class of electrides, consisting of one-dimensional (1D) nanorod building blocks. Their crystal structures mimic β-TiCl₃ with the position of anions and cations exchanged. Unlike the weakly coupled nanorods of β-TiCl₃, Cs₃O and Ba₃N retain 1D anionic electrons along the hollow interrod sites; additionally, a strong interrod interaction in C₃O and Ba₃N induces band inversion in a 2D superatomic triangular lattice, resulting in Dirac-node lines. The new class of electrides can serve as a prototype for new electrides with a large cavity space that can be utilized for various applications such as gas storage, ion transport, and metal intercalation.