The bulk behavior of materials is often controlled by minor impurities that create nonperiodic localized defect structures due to ionic size, symmetry, and charge balance mismatches. Here, we used transmission electron microscopy (TEM) of atom-resolved dynamics to directly map the topology of Fe vacancy clusters surrounding structurally incorporated U⁶⁺ in nanohematite (α-Fe₂O₃). Ab initio molecular dynamic simulations provided additional independent constraints on coupled U, Fe, and vacancy mobility in the solid. A clearer understanding of how such an apparently incompatible element can be accommodated by hematite emerged. The results were readily interpretable without the need for sophisticated data reconstruction methods, model structures, or ultrathin samples, and with the proliferation of aberration-corrected TEM facilities, the approach is accessible. Given sufficient z-contrast, the ability to observe impurity-vacancy structures by means of atom hopping can be used to directly probe the association of impurities and such defects in other materials, with promising applications across a broad range of disciplines.

中文翻译：

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使用原子动力学绘制纳米赤铁矿中杂质周围的缺陷结构图

材料的整体性能通常由微量杂质控制，这些杂质由于离子尺寸，对称性和电荷平衡失配而产生非周期性的局部缺陷结构。在这里，我们使用透射电子显微镜（TEM）原子分辨动力学直接映射的Fe空位簇的周围的拓扑结构上并入ü ⁶⁺在nanohematite（的α-Fe ₂ ö ₃）。从头算分子动力学模拟为耦合的U，Fe和固体中的空位迁移率提供了其他独立约束。对赤铁矿如何容纳这种看似不相容的元素有了更清晰的认识。无需复杂的数据重建方法，模型结构或超薄样品，并且随着像差校正的TEM设施的普及，该方法易于理解。给定足够的z对比度，通过原子跳跃观察杂质空位结构的能力可用于直接探测杂质与其他材料中此类缺陷的关联，在广泛的学科中具有广阔的应用前景。