The Li-F-H Ternary System at High Pressures

Abstract

Evolutionary crystal structure prediction searches have been employed to explore the ternary Li-F-H system at 300 GPa. Metastable phases were uncovered within the static lattice approximation, with LiF${}_3$H${}_2$, LiF${}_2$H, Li${}_3$F${}_4$H, LiF${}_4$H${}_4$, Li${}_2$F${}_3$H and LiF${}_3$H lying within 50 meV/atom of the 0 K convex hull. All of these phases contain H${}_n$F${}_{n+1}^{-}$ ($n$ = 1; 2) anions, and Li${}^{+}$ cations. Other structural motifs such as LiF slabs, H${}_3^{+}$ molecules, and F${}^{\delta -}$ ions are present in some of the low enthalpy Li-F-H structures. The bonding within the H${}_n$F${}_{n+1}^{-}$ molecules, which may be bent or linear, symmetric or asymmetric, is analyzed. The five phases closest to the hull are insulators, while LiF${}_3$H is metallic and predicted to have a vanishingly small superconducting critical temperature. This study lays the foundation for future investigations of the role of temperature and anharmonicity on the stability and properties of compounds and alloys in the Li-F-H ternary system.

11 pages, 4 figures, 1 table

References in corpus (3)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Electronic structure and optical properties of lightweight metal hydrides
• A Metastable CaSH${}_3$ Phase Composed of HS Honeycomb Sheets that is Superconducting Under Pressure

Cited by in corpus (1)

• Materials under high pressure: A chemical perspective