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.

石墨烯片是由单个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底。实验表明，如果物体被封装在两片石墨烯之间，石墨烯可以减少撞击和电子束诱导的电离损伤。该过程能够实现原子结构的可视化，这在其他情况下是不可能的。因为石墨烯和其他二维（2D）材料，例如六方BN和过渡金属二硫属化物，对于水和水溶液是不可渗透的，所以它们可以用于限制液体材料。由于这种能力，入射电子可以诱导形成新的2D相的封装材料，这可能是不稳定的otherwise.在这个项目中，我们的目标是结合联合收割机交流高分辨率（HR）TEM实验与原子模拟。这种方法将使我们能够解开石墨烯和其他2D材料之间的新2D材料的形成过程，结构和性质。由于这些封装的结构是不稳定的，我们称之为准2D材料。具体来说，水，盐水溶液，和金属与低熔点温度（汞，镓）将被封装和研究使用高分辨透射电子显微镜在宽范围的温度和低电子电压的范围为20-80千伏。我们将首次使用我们新开发的SALVE机器，它提供了卓越的分辨率，因为它配备了球面和色差校正器。由于电子辐照通过几种机制和化学反应诱导在封装材料中形成缺陷，因此我们将使用电子束来设计新的受限纳米结构和准2D晶体。为了获得完整的理解的光束诱导的转换和辐射引起的缺陷的作用，多尺度原子模拟将进行。具体来说，我们将开发新的计算技术的基础上的非绝热Escherichfest动力学与时间相关的密度泛函理论相结合，实现它们在专用的计算机软件（也适用于散装材料和生物系统），并将它们连接到动力学蒙特-卡罗计划来描述系统的宏观时间尺度上的演变。我们还将使用标准技术（包括DFT和分析势方法）对准二维材料的性质进行广泛的计算。我们的研究结果不仅可以为原子尺度上受限低维系统的物理学提供基本的见解，而且还可以使我们探索有前途的途径来设计新型封装纳米结构的结构和性能。

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