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<p>Extended covalent compounds that contain gold are virtually unknown because Au prefers metallic or molecular coordination. Using crystal structure search combined with first-principles calculations at high pressure, we have identified a family of ternary compounds, M<sub>2</sub>AuB<sub>6</sub> (M = Na, K, Mg, Ca, and Sr), featuring Au-B covalent frameworks that satisfy a simple “push-pull” design rule: strongly electropositive cations donate charge that anchors Au in electron-deficient B<sub>6</sub> octahedra, thereby stabilizing Au–B σ bonds through Au <i>dsp</i><sup>2</sup> hybridization. The low enthalpy phases, Na<sub>2</sub>AuB<sub>6</sub> and K<sub>2</sub>AuB<sub>6</sub>, exhibit superconductivity, with Au-6<i>p</i><sub><i>x</i></sub>/6<i>p</i><sub><i>y</i></sub> and B-2<i>p</i> states contributing to Cooper pair formation, facilitated by low- and medium-frequency phonons arising from Au−B bond stretching. These pressure-induced structures and bonding configurations can be quenched to ambient pressure, demonstrating an effective approach to bypassing traditional electronegativity constraints. We propose M<sub>2</sub>AuB<sub>6</sub> compounds as realistic and chemically unique platforms for exploring gold-based superconductivity and for testing electron-donor-guided materials discovery.</p>

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Ambient-pressure superconductivity in covalent Au-B frameworks stabilized by electropositive metals

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年11月10日

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  • Shuai Han,
  • Xiaohua Zhang,
  • Li Zhu,
  • Sheng Wang,
  • Shicong Ding,
  • Eva Zurek,
  • Guochun Yang

摘要

Extended covalent compounds that contain gold are virtually unknown because Au prefers metallic or molecular coordination. Using crystal structure search combined with first-principles calculations at high pressure, we have identified a family of ternary compounds, M2AuB6 (M = Na, K, Mg, Ca, and Sr), featuring Au-B covalent frameworks that satisfy a simple “push-pull” design rule: strongly electropositive cations donate charge that anchors Au in electron-deficient B6 octahedra, thereby stabilizing Au–B σ bonds through Au dsp2 hybridization. The low enthalpy phases, Na2AuB6 and K2AuB6, exhibit superconductivity, with Au-6px/6py and B-2p states contributing to Cooper pair formation, facilitated by low- and medium-frequency phonons arising from Au−B bond stretching. These pressure-induced structures and bonding configurations can be quenched to ambient pressure, demonstrating an effective approach to bypassing traditional electronegativity constraints. We propose M2AuB6 compounds as realistic and chemically unique platforms for exploring gold-based superconductivity and for testing electron-donor-guided materials discovery.