Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures. Issue 38 (22nd September 2021)

• Record Type: Journal Article
• Authors: Zhang, Shoutao; Yang, Qiuping; Zhang, Xiaohua; Zhao, Kaixuan; Yu, Hong; Zhu, Li; Liu, Hanyu
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 38(2021)
• Page Start: 21544
• Page End: 21553
• Publication Date: 2021-09-22
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp02781f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The introduction of Li and F into a Au–H system induces the formation of unprecedented solid metallic Li–Au–H and nonmetallic F–Au–H compounds under compression, where Au–H bonds and superconductivity are discovered in some Li–Au–H compounds. 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, LiAu2 H, Li2 Au2 H, and Li6 AuH) are predicted to be stable under compression. Intriguingly, Au–H bonding is found in LiAuH, LiAu2 H, and Li2 Au2 H. As the gold content increases, Au atom arrangements exhibit diverse forms, from the chain in Li6 AuH, the square layer in LiAuH, the network in Li2 Au2 H, and eventually to the coexistence of square and pyramid layers in LiAu2 H. Additionally, Li6 AuH 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 F4 AuH and F6 AuH 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.