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

Au with sp3 Hybridization in Li5AuP2

The achievement of new bonding patterns of atoms in compounds is of great importance, which usually induces interesting physical and chemical properties. Rich oxidation states, diverse bonding types, and unique aurophilic attraction endow gold (Au) as a distinctive element. Here we report that a pressure-induced Li₅AuP₂, identified by a swarm intelligence-based structural prediction, becomes the first example of Au with sp³ hybridization. The most remarkable feature of Li₅AuP₂ is that it contains various frameworks made by AuP₄, AuLi₄, LiP₄, and blende-like Li-P units, exhibiting noncentrosymmetry. The charge transfer from Li to Au makes Au 6p orbitals activate and hybridize with the 6s one. On the other hand, Li donating electrons to P and polar Au-P covalence make the constituent atoms satisfy the octet rule, rendering Li₅AuP₂ with a semiconducting character and a large second-order nonlinear optical response in the near-infrared region. Our work represents a significant step toward extending the understanding of gold chemistry.