Materials in crystalline form possess translational symmetry (TS) when the unit cell is repeated in real space with long- and short-range orders. The periodic potential in the crystal regulates the electron wave function and results in unique band structures, which further define the physical properties of the materials. Amorphous materials lack TS due to the randomization of distances and arrangements between atoms, causing the electron wave function to lack a well-defined momentum. High entropy materials provide another way to break the TS by randomizing the potential strength at periodic atomic sites. The local elemental distribution has a great impact on physical properties in high entropy materials. It is critical to distinguish elements at the sub-nanometer scale to uncover the correlations between the elemental distribution and the material properties. Here, the use of synchrotron X-ray scanning tunneling microscopy (SX-STM) with sub-nm scale resolution in identifying elements on a high entropy alloy (HEA) surface is demonstrated. By examining the elementally sensitive X-ray absorption spectra with an STM tip to enhance the spatial resolution, the elemental distribution on an HEA's surface at a sub-nm scale is extracted. These results open a pathway towards quantitatively understanding high entropy materials and their material properties.

中文翻译：

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区分高熵合金表面亚纳米级元素

当晶胞在真实空间中以长程和短程有序重复时，晶体形式的材料具有平移对称性（TS）。晶体中的周期性电势调节电子波函数并产生独特的能带结构，这进一步定义了材料的物理特性。由于原子之间距离和排列的随机化，非晶材料缺乏 TS，导致电子波函数缺乏明确的动量。高熵材料提供了另一种打破 TS 的方法，即随机化周期性原子位点的势强度。局部元素分布对高熵材料的物理性质有很大影响。区分亚纳米尺度的元素对于揭示元素分布与材料特性之间的相关性至关重要。在这里，展示了使用具有亚纳米级分辨率的同步加速器 X 射线扫描隧道显微镜 (SX-STM) 来识别高熵合金 (HEA) 表面上的元素。通过使用 STM 尖端检查元素敏感的 X 射线吸收光谱以提高空间分辨率，可以提取 HEA 表面亚纳米级的元素分布。这些结果为定量理解高熵材料及其材料特性开辟了一条途径。