Akita Ikumi, Ishida Yohei, Yonezawa Tetsu
Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
J Phys Chem Lett. 2020 May 7;11(9):3357-3361. doi: 10.1021/acs.jpclett.0c00758. Epub 2020 Apr 16.
Although aberration-corrected scanning transmission electron microscope (STEM) enables the atomic-scale visualization of ultrathin 2D materials such as graphene, imaging of electron-beam sensitive 2D materials with structural complexity is an intricate problem. We here report the first atomic-scale imaging of a free-standing monolayer clay mineral nanosheet via the annular dark field (ADF) STEM. The monolayer clay nanosheet was stably observed under optimal conditions, and we confirmed that the hexagonal contrast pattern with a pore of ∼4 Å corresponds to the atomic structure of clay mineral that consisted of adjacent Si, Al, Mg, and O atoms by comparison with simulations. The findings offer the usefulness of ADF-STEM techniques for the atomic scale imaging of clay minerals and various 2D materials having electron-beam sensitivity and structural complexity than few-atom-thick graphene analogues.
尽管像差校正扫描透射电子显微镜（STEM）能够对石墨烯等超薄二维材料进行原子尺度的可视化成像，但对具有结构复杂性的电子束敏感二维材料进行成像却是一个复杂的问题。我们在此报告通过环形暗场（ADF）STEM对独立单层粘土矿物纳米片进行的首次原子尺度成像。在最佳条件下稳定观察到了单层粘土纳米片，并且通过与模拟结果对比，我们证实了具有约4 Å孔隙的六边形对比度图案对应于由相邻的硅、铝、镁和氧原子组成的粘土矿物的原子结构。这些发现表明ADF-STEM技术对于粘土矿物以及比少原子厚的石墨烯类似物具有更高电子束敏感性和结构复杂性的各种二维材料的原子尺度成像很有用。
