Li-F polarity-driven stabilization of -VII oxidation state of gold at high pressure.

Zhang, Xiaohua; Wang, Sheng; Bergara, Aitor; Du, Xin; Yang, Guochun · Nat Commun · 2025

basic_science · Level V

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Abstract

The exploration of unconventional oxidation states is pivotal for expanding fundamental bonding paradigms and accessing exotic matter. Achieving highly negative oxidation states in transition metals remains a significant challenge. Here, we propose a dual-driven strategy combining a strong reductant (Li) and oxidant (F) under high pressure, stabilizing the oxidation state -VII of gold (Au) in a ternary electride Li<sub>10</sub>AuF. This insulating phase hosts paired interstitial anionic electrons and features an Au center nominally isoelectronic with the noble gas radon, governed by F-enhanced charge polarization, pressure-induced orbital reshuffling, and p-d hybridization that lowers the energy of Au 6p orbitals. Replacing F with I or P progressively reduces Au charge and interstitial electron localization, transforming semiconducting Li<sub>10</sub>AuF into semimetallic Li<sub>10</sub>AuI and ultimately superconducting Li<sub>10</sub>AuP. These results demonstrate how chemically polarized element combinations under compression can unlock unexpected oxidation states and charge distributions, guiding the design of quantum materials with emergent functionalities.