Imaging and atomic structure engineering of quasi-two-dimensional materials encapsulated between graphene sheets

石墨烯片封装的准二维材料的成像和原子结构工程

• 批准号: 345789964
• 负责人: Professorin Dr. Ute Kaiser
• 金额: --
• 依托单位: Institut für Ionenstrahlphysik und Materialforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/345789964?language=en
• 关键词: Imaging; atomic; structure; engineering; quasi

Graphene sheets are mechanically robust and chemically inert membranes consisting of a single atomic layer. Owing to these properties, graphene has been proven to be an ideal substrate for imaging molecules and nanostructures using aberration-corrected transmission electron microscopy (AC-TEM). Experiments have shown that graphene reduces knock-on and electron-beam-induced ionization damage if the object is encapsulated between two sheets of graphene. This procedure enables the visualization of the atomic structure which otherwise is not possible. Because graphene and other two-dimensional (2D) materials, such as hexagonal BN and transition metal dichalcogenides, are impermeable for water and aqueous solutions, they can be used for confining liquid materials. Owing to this ability, the incident electrons can induce within the encapsulated materials the formation of new 2D phases which may not be stable otherwise.In this project, we aim to combine AC-high-resolution (HR) TEM experiments with atomistic simulations. This approach will enable us to unravel the formation process, the structure, and the properties of the new 2D materials between the sheets of graphene and other 2D materials. Since these encapsulated structures would otherwise be unstable, we call them quasi 2D materials. Specifically, water, aqueous solutions of salts, and metals with low melting temperature (mercury, gallium) will be encapsulated and studied using HRTEM in a wide range of temperatures and low electron voltages in the range of 20-80 kV. For the first time, we will use our newly developed SALVE machine, which provides exceptional resolution, because it is equipped with a spherical and chromatic aberration corrector. Since electron irradiation induces the formation of defects in the encapsulated materials through several mechanisms and chemical reactions, we will use the electron beam for engineering new confined nanostructures and quasi-2D crystals. To obtain complete understanding of the beam-induced transformations and the role of radiation-induced defects, multiscale atomistic simulations will be carried out. Specifically, we will develop new computational techniques based on the non-adiabatic Ehrenfest dynamics combined with time-dependent density-functional theory, implement them in the dedicated computer software (applicable also to bulk materials and bio systems), and connect them to the kinetic Monte-Carlo schemes to describe the evolution of the system on a macroscopic time scale. We will also carry out extensive calculations of the properties of the quasi-2D materials using standard techniques including DFT and analytical potential approaches. Our results should not only provide fundamental insights into the physics of confined low-dimensional systems on an atomic scale, but also enable us to explore promising avenues for engineering the structure and properties of novel encapsulated nanostructures.

石墨烯片是由单原子层组成的机械坚固且化学惰性的膜。由于这些特性，石墨烯已被证明是使用像差校正透射电子显微镜 (AC-TEM) 成像分子和纳米结构的理想基材。实验表明，如果物体被封装在两片石墨烯之间，石墨烯可以减少碰撞和电子束引起的电离损伤。这个过程使得原子结构的可视化成为可能，否则这是不可能的。由于石墨烯和其他二维（2D）材料，例如六方氮化硼和过渡金属二硫属化物，对水和水溶液是不可渗透的，因此它们可用于限制液体材料。由于这种能力，入射电子可以在封装材料内诱导形成新的二维相，否则该二维相可能不稳定。在这个项目中，我们的目标是将交流高分辨率 (HR) TEM 实验与原子模拟相结合。这种方法将使我们能够揭示石墨烯片和其他二维材料之间的新型二维材料的形成过程、结构和特性。由于这些封装结构否则会不稳定，因此我们将其称为准二维材料。具体来说，将使用 HRTEM 在宽温度范围和 20-80 kV 范围内的低电子电压下封装和研究水、盐的水溶液和低熔点金属（汞、镓）。我们将首次使用我们新开发的 SALVE 机器，它配备了球差和色差校正器，可提供卓越的分辨率。由于电子辐照通过多种机制和化学反应诱导封装材料中缺陷的形成，因此我们将使用电子束来设计新的受限纳米结构和准二维晶体。为了全面了解光束引起的转变和辐射引起的缺陷的作用，将进行多尺度原子模拟。具体来说，我们将开发基于非绝热埃伦菲斯特动力学与时间相关密度泛函理论相结合的新计算技术，在专用计算机软件中实现它们（也适用于散装材料和生物系统），并将它们与动力学蒙特卡罗方案连接起来，以描述系统在宏观时间尺度上的演化。我们还将使用包括 DFT 和分析势方法在内的标准技术对准二维材料的性能进行广泛的计算。我们的研究结果不仅应该为原子尺度上受限低维系统的物理学提供基本见解，而且还使我们能够探索设计新型封装纳米结构的结构和性能的有希望的途径。

项目成果

Layer-Dependent Band Gaps of Platinum Dichalcogenides

• DOI: 10.1021/acsnano.1c02971
• 发表时间: 2021-08-16
• 期刊: ACS NANO
• 影响因子: 17.1
• 作者: Li, Jingfeng;Kolekar, Sadhu;Batzill, Matthias
• 通讯作者: Batzill, Matthias

Alkali metals inside bi-layer graphene and MoS2: Insights from first-principles calculations

• DOI: 10.1016/j.nanoen.2020.104927
• 发表时间: 2020-09-01
• 期刊: NANO ENERGY
• 影响因子: 17.6
• 作者: Chepkasov, Ilya V.;Ghorbani-Asl, Mahdi;Krasheninnikov, Arkady V.
• 通讯作者: Krasheninnikov, Arkady V.

Quasi-two-dimensional NaCl crystals encapsulated between graphene sheets and their decomposition under an electron beam.

• DOI: 10.1039/d1nr04792b
• 发表时间: 2021-11
• 期刊: Nanoscale
• 影响因子: 6.7
• 作者: T. Lehnert;S. Kretschmer;Fredrik Bräuer;A. Krasheninnikov;U. Kaiser

Observation of charge density waves in free-standing 1T-TaSe2 monolayers by transmission electron microscopy

• DOI: 10.1063/1.5052722
• 发表时间: 2018-10
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: P. Börner;M. Kinyanjui;T. Björkman;T. Lehnert;A. Krasheninnikov;U. Kaiser

Defect Agglomeration and Electron-Beam-Induced Local-Phase Transformations in Single-Layer MoTe2

• DOI: 10.1021/acs.jpcc.1c02202
• 发表时间: 2021-06
• 期刊: The Journal of Physical Chemistry C
• 作者: J. Köster;M. Ghorbani-Asl;H. Komsa;T. Lehnert;S. Kretschmer;A. Krasheninnikov;U. Kaiser