Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures

Shoutao Zhang; Qiuping Yang; Xiaohua Zhang; Kaixuan Zhao; Hong Yu; Li Zhu; Hanyu Liu

doi:10.1039/D1CP02781F

Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures†

Shoutao Zhang,

*^a Qiuping Yang,

^a Xiaohua Zhang,

^a Kaixuan Zhao,

^a Hong Yu,

^a Li Zhu

*^d and Hanyu Liu*^bc

Author affiliations

* Corresponding authors

^a Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China
E-mail: zhangst966@nenu.edu.cn

^b International Center for Computational Method & Software and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
E-mail: hanyuliu@jlu.edu.cn

^c Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education),College of Physics, Jilin University, Changchun 130012, China

^d Department of Physics, Rutgers University, Newark, NJ 07102, USA
E-mail: li.zhu@rutgers.edu

Abstract

The investigations on gold science have been capturing research interest due to its diverse physical and chemical properties. Gold hydrides in the solid state, as a member of the Au compound family, are rare since the reaction of Au with H is hindered in terms of their similar electronegativity. It is expected that Li and F can provide electrons and holes, respectively, to help stabilize gold hydrides under high pressure. Herein, by means of a crystal structural search based on particle swarm optimization methodology accompanied by first-principles calculations, four hitherto unknown Li–Au–H compounds (i.e., LiAuH, LiAu₂H, Li₂Au₂H, and Li₆AuH) are predicted to be stable under compression. Intriguingly, Au–H bonding is found in LiAuH, LiAu₂H, and Li₂Au₂H. As the gold content increases, Au atom arrangements exhibit diverse forms, from the chain in Li₆AuH, the square layer in LiAuH, the network in Li₂Au₂H, and eventually to the coexistence of square and pyramid layers in LiAu₂H. Additionally, Li₆AuH has a unique cage-type lithium structure. Furthermore, electron–phonon coupling calculations show that these Li–Au–H phases are phonon-modulated superconductors with a superconducting critical temperature of 1.3, 0.06, and 0.02 K at 25 GPa and 2.79 K at 100 GPa. In contrast, we also identified two solid F₄AuH and F₆AuH phases with unexpected semiconductivity. They have structural configurations of H-bridged AuF₄ quasi-square components and distorted AuF₆ octahedrons, respectively, and have no gold-to-hydrogen bonds. Our current results indicate that electron doping at suitable concentrations under pressure can stabilize unique gold hydrides, and provide deep insights into the structures, electron properties, bonding behavior, and stability mechanism of ternary Li–Au–H and F–Au–H compounds.

This article is part of the themed collection: 2021 PCCP HOT Articles

Physical Chemistry Chemical Physics

Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures†

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Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures

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