Emergence of superconductivity and superionicity in the electride Li6La under extreme conditions
Wen Xu, Qinfang Wang, Qing‐Xin Zeng, Xue Li, Jingming Shi, Jian Hao, Wenwen Cui, Yinwei Li
Abstract
Superconducting electrides, a unique type of conventional superconductors, have recently attracted considerable attention. Inspired by the discovery of high critical temperature ( T c ) in lanthanum hydrides and the feasibility of forming electrides in lithium-based compounds, we have conducted a systematic investigation the phase diagram and superconductivity of Li-La alloys under high pressure. Using the crystal structure prediction method and first-principles calculations, we uncovered three pressure-stabilized compounds with stoichiometries LiLa 3 , LiLa 2 and Li 6 La. All three compounds exhibit metallic behavior with electrons transferred from Li to La atoms. Notably, Li 6 La emerges as a prototypical superconducting electride with T c of 11.6 K at 350 GPa, which increases to 16.3 K as pressure decreases to 200 GPa. Electron–phonon analysis reveal that the enhancement of superconductivity mainly originates from the coupling between the increased interstitial quasiatoms (ISQs) and low-frequencies phonons. Additionally, akin to lanthanum hydrides, Li 6 La is predicted to enter a superionic phase characterized by high lithium diffusion coefficients under high pressure and temperature. Our findings indicate the coexistence of superconductivity and superionicity in the electride Li 6 La, which may prompt further experimental investigations.