Abstract Using in-situ transmission electron microscopy and atomistic simulations, we report atomic-scale observations of segregation-induced structure changes in the surface and subsurface region of a Cu(Au) solid solution in both reductive and oxidative environments. In a H2 atmosphere, Au segregation induces the formation of a two-atomic-layer thick ordered surface alloy with an L10 terminated surface layer. By switching to an O2 atmosphere, the outermost surface develops into an Au-missing row reconstruction and simultaneously the second layer experiences an order-disorder transition via intralayer atomic exchanges. The chemical disordering then propagates to the outermost surface, driven by oxygen-adsorption induced Cu surface segregation. This transforms the L10 missing-row reconstruction into a non-reconstructed, oxygenated surface. These observations provide a mechanistic detail regarding the evolution of the surface and subsurface of this alloy in response to environmental stimuli, and are relevant to a wide range of technologically relevant processes.

中文翻译：

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Cu(Au)表面合金中偏析诱导的有序-无序转变

摘要 使用原位透射电子显微镜和原子模拟，我们报告了在还原和氧化环境中 Cu(Au) 固溶体的表面和亚表面区域的偏析诱导结构变化的原子尺度观察。在 H2 气氛中，Au 偏析诱导形成具有 L10 终止表面层的两原子层厚有序表面合金。通过切换到 O2 气氛，最外层表面发展为 Au 缺失行重建，同时第二层通过层内原子交换经历有序 - 无序转变。在氧吸附诱导的铜表面偏析的驱动下，化学无序然后传播到最外表面。这将 L10 缺失行重建转换为未重建的氧化表面。