1
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Zeng M, Wang W, Yin Y, Zheng C. A simple coordinate transformation method for quickly locating the features of interest in TEM samples. Microscopy (Oxf) 2024; 73:381-387. [PMID: 38421047 DOI: 10.1093/jmicro/dfae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/16/2024] [Accepted: 02/07/2024] [Indexed: 03/02/2024] Open
Abstract
We developed a simple coordinate transformation method for quickly locating features of interest (FOIs) of samples in transmission electron microscope (TEM). The method is well suited for conducting sample searches in aberration-corrected scanning/transmission electron microscopes (S/TEM), where the survey can be very time-consuming because of the limited field of view imposed by the highly excited objective lens after fine-tuning the aberration correctors. For implementation, a digital image of the sample and the TEM holder was captured using a simple stereo-optical microscope. Naturally presented geometric patterns on the holder were referenced to construct a projective transformation between the electron and optical coordinate systems. The test results demonstrated that the method was accurate and required no electron microscope or specimen holder modifications. Additionally, it eliminated the need to mount the sample onto specific patterned TEM grids or deposit markers, resulting in universal applications for most TEM samples, holders and electron microscopes for fast FOI identification. Furthermore, we implemented the method into a Gatan script for graphical-user-interface-based step-by-step instructions. Through online communication, the script enabled real-time navigation and tracking of the motion of samples in TEM on enlarged optical images with a panoramic view.
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Affiliation(s)
- Mingzhi Zeng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Songhu Rd 2005, Yangpu District, Shanghai 200438, China
| | - Wenzhao Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Songhu Rd 2005, Yangpu District, Shanghai 200438, China
| | - Yang Yin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Songhu Rd 2005, Yangpu District, Shanghai 200438, China
| | - Changlin Zheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Songhu Rd 2005, Yangpu District, Shanghai 200438, China
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2
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Bijelić L, Ruiz-Zepeda F, Hodnik N. The role of high-resolution transmission electron microscopy and aberration corrected scanning transmission electron microscopy in unraveling the structure-property relationships of Pt-based fuel cells electrocatalysts. Inorg Chem Front 2024; 11:323-341. [PMID: 38235274 PMCID: PMC10790562 DOI: 10.1039/d3qi01998e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/05/2023] [Indexed: 01/19/2024]
Abstract
Platinum-based fuel cell electrocatalysts are structured on a nano level in order to extend their active surface area and maximize the utilization of precious and scarce platinum. Their performance is dictated by the atomic arrangement of their surface layers atoms via structure-property relationships. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) are the preferred methods for characterizing these catalysts, due to their capacity to achieve local atomic-level resolutions. Size, morphology, strain and local composition are just some of the properties of Pt-based nanostructures that can be obtained by (S)TEM. Furthermore, advanced methods of (S)TEM are able to provide insights into the quasi-in situ, in situ or even operando stability of these nanostructures. In this review, we present state-of-the-art applications of (S)TEM in the investigation and interpretation of structure-activity and structure-stability relationships.
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Affiliation(s)
- Lazar Bijelić
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- University of Nova Gorica Vipavska 13 Nova Gorica SI-5000 Slovenia
| | - Francisco Ruiz-Zepeda
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- Department of Physics and Chemistry of Materials, Institute for Metals and Technology IMT Lepi pot 11 1000 Ljubljana Slovenia
| | - Nejc Hodnik
- Laboratory for Electrocatalysis, Department of Materials Chemistry, National Insititute of Chemistry Hajdrihova 19 1000 Ljubljana Slovenia
- University of Nova Gorica Vipavska 13 Nova Gorica SI-5000 Slovenia
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3
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Li S, Lin J, Chen Y, Luo Z, Cheng H, Liu F, Zhang J, Wang S. Growth Anisotropy and Morphology Evolution of Line Defects in Monolayer MoS 2 : Atomic-Level Observation, Large-Scale Statistics, and Mechanism Understanding. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2303511. [PMID: 37749964 DOI: 10.1002/smll.202303511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/25/2023] [Indexed: 09/27/2023]
Abstract
Understanding the growth behavior and morphology evolution of defects in 2D transition metal dichalcogenides is significant for the performance tuning of nanoelectronic devices. Here, the low-voltage aberration-corrected transmission electron microscopy with an in situ heating holder and a fast frame rate camera to investigate the sulfur vacancy lines in monolayer MoS2 is applied. Vacancy concentration-dependent growth anisotropy is discovered, displaying first lengthening and then broadening of line defects as the vacancy densifies. With the temperature increase from 20 °C to 800 °C, the defect morphology evolves from a dense triangular network to an ultralong linear structure due to the temperature-sensitive vacancy migration process. Atomistic dynamics of line defect reconstruction on the millisecond time scale are also captured. Density functional theory calculations, Monte Carlo simulation, and configurational force analysis are implemented to understand the growth and reconstruction mechanisms at relevant time and length scales. Throughout the work, high-resolution imaging is closely combined with quantitative analysis of images involving thousands of atoms so that the atomic-level structure and the large-area statistical rules are obtained simultaneously. The work provides new ideas for balancing the accuracy and universality of discoveries in the TEM study and will be helpful to the controlled sculpture of nanomaterials.
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Affiliation(s)
- Shouheng Li
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Jinguo Lin
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Yun Chen
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Zheng Luo
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Haifeng Cheng
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China
| | - Feng Liu
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Jin Zhang
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Shanshan Wang
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410073, P. R. China
- School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
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4
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Liu M, Senga R, Koshino M, Lin YC, Suenaga K. Direct Observation of Locally Modified Excitonic Effects within a Moiré Unit Cell in Twisted Bilayer Graphene. ACS NANO 2023; 17:18433-18440. [PMID: 37682623 DOI: 10.1021/acsnano.3c06021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
Bilayer graphene, which forms moiré superlattices, possesses distinct electronic and optical properties owing to its hybridized energy band and the emergence of van Hove singularities depending on its twist angle. Extensive research has been conducted on the global characteristics of moiré superlattices induced by their long-range periodicity. However, the local properties, which differ owing to the variations in the three-dimensional atomic arrangement, within a moiré unit cell have been rarely explored. In this study, we demonstrate the highly localized excitation of carbon 1s electrons to unoccupied van Hove singularities in twisted bilayer graphene by electron energy loss spectroscopy using a monochromated transmission electron microscope. The core-level excitations associated with the van Hove singularities exhibit a systematic twist-angle dependence analogous to optical excitations. Furthermore, local variations in the core-level van Hove singularity peaks, which can originate from the core-exciton lifetimes and band modifications corresponding to the local stacking geometry within a moiré unit cell, are unambiguously corroborated.
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Affiliation(s)
- Ming Liu
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Ryosuke Senga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba 305-8565, Japan
| | - Masanori Koshino
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba 305-8565, Japan
| | - Yung-Chang Lin
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba 305-8565, Japan
| | - Kazu Suenaga
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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5
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Chari A, Stark H. Prospects and Limitations of High-Resolution Single-Particle Cryo-Electron Microscopy. Annu Rev Biophys 2023; 52:391-411. [PMID: 37159297 DOI: 10.1146/annurev-biophys-111622-091300] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Single particle cryo-electron microscopy (cryo-EM) has matured into a robust method for the determination of biological macromolecule structures in the past decade, complementing X-ray crystallography and nuclear magnetic resonance. Constant methodological improvements in both cryo-EM hardware and image processing software continue to contribute to an exponential growth in the number of structures solved annually. In this review, we provide a historical view of the many steps that were required to make cryo-EM a successful method for the determination of high-resolution protein complex structures. We further discuss aspects of cryo-EM methodology that are the greatest pitfalls challenging successful structure determination to date. Lastly, we highlight and propose potential future developments that would improve the method even further in the near future.
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Affiliation(s)
- Ashwin Chari
- Research Group for Structural Biochemistry and Mechanisms, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Holger Stark
- Department of Structural Dynamics, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany;
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6
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Bertoni G, Rotunno E, Marsmans D, Tiemeijer P, Tavabi AH, Dunin-Borkowski RE, Grillo V. Near-real-time diagnosis of electron optical phase aberrations in scanning transmission electron microscopy using an artificial neural network. Ultramicroscopy 2023; 245:113663. [PMID: 36566529 DOI: 10.1016/j.ultramic.2022.113663] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 10/17/2022] [Accepted: 12/17/2022] [Indexed: 12/23/2022]
Abstract
The key to optimizing spatial resolution in a state-of-the-art scanning transmission electron microscope is the ability to measure and correct for electron optical aberrations of the probe-forming lenses precisely. Several diagnostic methods for aberration measurement and correction have been proposed, albeit often at the cost of relatively long acquisition times. Here, we illustrate how artificial intelligence can be used to provide near-real-time diagnosis of aberrations from individual Ronchigrams. The demonstrated speed of aberration measurement is important because microscope conditions can change rapidly. It is also important for the operation of MEMS-based hardware correction elements, which have less intrinsic stability than conventional electromagnetic lenses.
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Affiliation(s)
- Giovanni Bertoni
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Via G. Campi 213/A, 41125 Modena, Italy.
| | - Enzo Rotunno
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Via G. Campi 213/A, 41125 Modena, Italy.
| | - Daan Marsmans
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, the Netherlands
| | - Peter Tiemeijer
- Thermo Fisher Scientific, PO Box 80066, 5600 KA Eindhoven, the Netherlands
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Vincenzo Grillo
- Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Via G. Campi 213/A, 41125 Modena, Italy
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7
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Muhammad Sajeer P, Simran, Nukala P, Manoj M. Varma. TEM based applications in solid state nanopores: From fabrication to liquid in-situ bio-imaging. Micron 2022; 162:103347. [DOI: 10.1016/j.micron.2022.103347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 08/23/2022] [Accepted: 08/23/2022] [Indexed: 10/31/2022]
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8
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Hennessy M, O'Connell EN, Auge M, Moynihan E, Hofsäss H, Bangert U. Quantification of Ion-Implanted Single-Atom Dopants in Monolayer MoS 2 via HAADF STEM Using the TEMUL Toolkit. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-10. [PMID: 35722923 DOI: 10.1017/s1431927622000757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In recent years, atomic resolution imaging of two-dimensional (2D) materials using scanning transmission electron microscopy (STEM) has become routine. Individual dopant atoms in 2D materials can be located and identified using their contrast in annular dark-field (ADF) STEM. However, in order to understand the effect of these dopant atoms on the host material, there is now the need to locate and quantify them on a larger scale. In this work, we analyze STEM images of MoS2 monolayers that have been ion-implanted with chromium at ultra-low energies. We use functions from the open-source TEMUL Toolkit to create and refine an atomic model of an experimental image based on the positions and intensities of the atomic columns in the image. We then use the refined model to determine the likely composition of each atomic site. Surface contamination stemming from the sample preparation of 2D materials can prevent accurate quantitative identification of individual atoms. We disregard atomic sites from regions of the image with hydrocarbon surface contamination to demonstrate that images acquired using contaminated samples can give significant atom statistics from their clean regions, and can be used to calculate the retention rate of the implanted ions within the host lattice. We find that some of the implanted chromium ions have been successfully integrated into the MoS2 lattice, with 4.1% of molybdenum atoms in the transition metal sublattice replaced with chromium.
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Affiliation(s)
- Michael Hennessy
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Eoghan N O'Connell
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Manuel Auge
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Eoin Moynihan
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Hans Hofsäss
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Ursel Bangert
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
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9
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Roitman D, Shiloh R, Lu PH, Dunin-Borkowski RE, Arie A. Shaping of Electron Beams Using Sculpted Thin Films. ACS PHOTONICS 2021; 8:3394-3405. [PMID: 34938823 PMCID: PMC8679091 DOI: 10.1021/acsphotonics.1c00951] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 10/31/2021] [Accepted: 11/04/2021] [Indexed: 05/04/2023]
Abstract
Electron beam shaping by sculpted thin films relies on electron-matter interactions and the wave nature of electrons. It can be used to study physical phenomena of special electron beams and to develop technological applications in electron microscopy that offer new and improved measurement techniques and increased resolution in different imaging modes. In this Perspective, we review recent applications of sculpted thin films for electron orbital angular momentum sorting, improvements in phase contrast transmission electron microscopy, and aberration correction. For the latter, we also present new results of our work toward correction of the spherical aberration of Lorentz scanning transmission electron microscopes and suggest a method to correct chromatic aberration using thin films. This review provides practical insight for researchers in the field and motivates future progress in electron microscopy.
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Affiliation(s)
- Dolev Roitman
- School
of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Roy Shiloh
- Physics
Department, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Peng-Han Lu
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter
Grünberg Institute, Forschungszentrum
Jülich, Jülich 52428, Germany
- RWTH
Aachen University, Aachen 52062, Germany
| | - Rafal E. Dunin-Borkowski
- Ernst
Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter
Grünberg Institute, Forschungszentrum
Jülich, Jülich 52428, Germany
| | - Ady Arie
- School
of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
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10
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Ortega E, Boothroyd C, de Jonge N. The influence of chromatic aberration on the dose-limited spatial resolution of transmission electron microscopy. Ultramicroscopy 2021; 230:113383. [PMID: 34450389 DOI: 10.1016/j.ultramic.2021.113383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/11/2021] [Accepted: 08/15/2021] [Indexed: 11/15/2022]
Abstract
The effect of chromatic aberration (CC) on the spatial resolution in transmission electron microscopy (TEM) was studied in thick specimens in which the sample becomes the limiting factor in the resolution. The sample influences the energy spread of the electron beam, allows only a limited electron dose, and modulates electron scattering events. The experimental set-up consisted of a thin silicon nitride membrane and a silicon wedge containing gold nanoparticles. The resolution was measured as a function of electron dose and sample thickness for different sample configurations and for different microscopy modalities including regular TEM, energy filtered TEM (EFTEM) and CC-corrected TEM. Comparison with an analytical model aided the understanding of the experimental data applied over varied conditions. The general trend for all microscopy modalities was a transition from a noise-limited resolution at low electron dose to a CC-limited resolution at high-dose in the absence of beam blurring. EFTEM required an accurate energy slit offset and an optimal energy spread to energy-slit width ratio to surpass regular TEM. The key advantage of CC correction appeared to be the best possible resolution for larger sample thickness at low electron dose outperforming EFTEM by about fifty percent. Several hypothetical sample configurations relevant to liquid phase electron microscopy were evaluated as well to demonstrate the capabilities of the analytical model and to determine the most optimal microscopy modality for this type of experiment. The analytical model included an automated optimization of the EFTEM settings and may aid in optimizing the sample-limited resolution for experimental analysis and planning.
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Affiliation(s)
- Eduardo Ortega
- INM-Leibniz Institute for New Materials, Saarbrücken 66123, Germany
| | - Chris Boothroyd
- Facility for Analysis Characterisation Testing and Simulation and School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore
| | - Niels de Jonge
- INM-Leibniz Institute for New Materials, Saarbrücken 66123, Germany; Department of Physics, Saarland University, Saarbrücken 66123, Germany.
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11
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Juneau M, Liu R, Peng Y, Malge A, Ma Z, Porosoff MD. Characterization of Metal‐zeolite Composite Catalysts: Determining the Environment of the Active Phase. ChemCatChem 2020. [DOI: 10.1002/cctc.201902039] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Mitchell Juneau
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
| | - Renjie Liu
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
| | - Yikang Peng
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
| | - Akhilesh Malge
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
| | - Zhiqiang Ma
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
| | - Marc D. Porosoff
- Department of Chemical EngineeringUniversity of Rochester Rochester NY-14627 USA
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12
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Chen Q, Dwyer C, Sheng G, Zhu C, Li X, Zheng C, Zhu Y. Imaging Beam-Sensitive Materials by Electron Microscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907619. [PMID: 32108394 DOI: 10.1002/adma.201907619] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/20/2019] [Indexed: 05/15/2023]
Abstract
Electron microscopy allows the extraction of multidimensional spatiotemporally correlated structural information of diverse materials down to atomic resolution, which is essential for figuring out their structure-property relationships. Unfortunately, the high-energy electrons that carry this important information can cause damage by modulating the structures of the materials. This has become a significant problem concerning the recent boost in materials science applications of a wide range of beam-sensitive materials, including metal-organic frameworks, covalent-organic frameworks, organic-inorganic hybrid materials, 2D materials, and zeolites. To this end, developing electron microscopy techniques that minimize the electron beam damage for the extraction of intrinsic structural information turns out to be a compelling but challenging need. This article provides a comprehensive review on the revolutionary strategies toward the electron microscopic imaging of beam-sensitive materials and associated materials science discoveries, based on the principles of electron-matter interaction and mechanisms of electron beam damage. Finally, perspectives and future trends in this field are put forward.
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Affiliation(s)
- Qiaoli Chen
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Christian Dwyer
- Department of Physics, Arizona State University, Tempe, AZ, 85287-1504, USA
| | - Guan Sheng
- Advanced Membranes and Porous Materials Center, Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Chongzhi Zhu
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Xiaonian Li
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Changlin Zheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200438, China
| | - Yihan Zhu
- Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China
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13
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Chen J, Jung GS, Ryu GH, Chang RJ, Zhou S, Wen Y, Buehler MJ, Warner JH. Atomically Sharp Dual Grain Boundaries in 2D WS 2 Bilayers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902590. [PMID: 31448580 DOI: 10.1002/smll.201902590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/25/2019] [Indexed: 06/10/2023]
Abstract
It is shown that tilt grain boundaries (GBs) in bilayer 2D crystals of the transition metal dichalcogenide WS2 can be atomically sharp, where top and bottom layer GBs are located within sub-nanometer distances of each other. This expands the current knowledge of GBs in 2D bilayer crystals, beyond the established large overlapping GB types typically formed in chemical vapor deposition growth, to now include atomically sharp dual bilayer GBs. By using atomic-resolution annular dark-field scanning transmission electron microscopy (ADF-STEM) imaging, different atomic structures in the dual GBs are distinguished considering bilayers with a 3R (AB stacking)/2H (AA' stacking) interface as well as bilayers with 2H/2H boundaries. An in situ heating holder is used in ADF-STEM and the GBs are stable to at least 800 °C, with negligible thermally induced reconstructions observed. Normal dislocation cores are seen in one WS2 layer, but the second WS2 layer has different dislocation structures not seen in freestanding monolayers, which have metal-rich clusters to accommodate the stacking mismatch of the 2H:3R interface. These results reveal the competition between maintaining van der Waals bilayer stacking uniformity and dislocation cores required to stitch tilted bilayer GBs together.
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Affiliation(s)
- Jun Chen
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Gang Seob Jung
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
| | - Gyeong Hee Ryu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Ren-Jie Chang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Si Zhou
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Yi Wen
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
- Center for Computational Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA, 02139, USA
| | - Jamie H Warner
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
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14
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Fang S, Wen Y, Allen CS, Ophus C, Han GGD, Kirkland AI, Kaxiras E, Warner JH. Atomic electrostatic maps of 1D channels in 2D semiconductors using 4D scanning transmission electron microscopy. Nat Commun 2019; 10:1127. [PMID: 30850616 PMCID: PMC6408534 DOI: 10.1038/s41467-019-08904-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/01/2019] [Indexed: 11/16/2022] Open
Abstract
Defects in materials give rise to fluctuations in electrostatic fields that reflect the local charge density, but imaging this with single atom sensitivity is challenging. However, if possible, this provides information about the energetics of adatom binding, localized conduction channels, molecular functionality and their relationship to individual bonds. Here, ultrastable electron-optics are combined with a high-speed 2D electron detector to map electrostatic fields around individual atoms in 2D monolayers using 4D scanning transmission electron microscopy. Simultaneous imaging of the electric field, phase, annular dark field and the total charge in 2D MoS2 and WS2 is demonstrated for pristine areas and regions with 1D wires. The in-gap states in sulphur line vacancies cause 1D electron-rich channels that are mapped experimentally and confirmed using density functional theory calculations. We show how electrostatic fields are sensitive in defective areas to changes of atomic bonding and structural determination beyond conventional imaging. Imaging electrostatic field around individual atoms or defective areas in monolayer 2D materials is crucial to understand their structural coordination. Here, the authors report local changes in specific atomic bonds and provide in-depth structural information of complex defective monolayer MoS2 and WS2 systems by 4D STEM.
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Affiliation(s)
- Shiang Fang
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Yi Wen
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Christopher S Allen
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK.,Electron Physical Sciences Imaging Center, Diamond Light Source Ltd., Didcot, Oxfordshire, OX11 0DE, UK
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, 94720, CA, USA
| | - Grace G D Han
- Department of Chemistry, Brandeis University, Waltham, 02453, MA, USA
| | - Angus I Kirkland
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK.,Electron Physical Sciences Imaging Center, Diamond Light Source Ltd., Didcot, Oxfordshire, OX11 0DE, UK
| | - Efthimios Kaxiras
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA. .,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
| | - Jamie H Warner
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK.
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15
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Chen J, Zhou S, Wen Y, Ryu GH, Allen C, Lu Y, Kirkland AI, Warner JH. In situ high temperature atomic level dynamics of large inversion domain formations in monolayer MoS 2. NANOSCALE 2019; 11:1901-1913. [PMID: 30644498 DOI: 10.1039/c8nr08821g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Here we study the high-temperature formation and dynamics of large inversion domains (IDs) that form in monolayer MoS2 using atomic-resolution annular dark-field scanning transmission electron microscopy (ADF-STEM) with an in situ heating stage. We use temperatures above 700 °C to thermally activate rapid S vacancy migration and this leads to a formation mechanism of IDs that differs from the one at room temperature, where S vacancy migration is limited. We show that at high temperatures the formation of IDs occurs from intersected networks of long S vacancy line defects, whose strain fields are non-orthogonal and trigger large scale atomic reconstructions. Once formed, the IDs are influenced by the dynamic behaviour of nearby line defects and voids. With Mo and S atoms undergoing movement, the two types of ID grain boundaries can shift to allow further expansion of the ID area along the adjoining line defects. We reveal that IDs serve as metastable configurations between line defect rearrangements and eventual void formation under electron beam irradiation during heating. The formation of voids near to the IDs causes them to revert back to pristine lattice, which has the effect of restricting the ID domain size to a certain range (e.g. 3-5 nm in our observation) instead of continuously enlarging. This study provides insights into how the MoS2 IDs form and evolve at high temperature and can benefit the tailoring of electronic properties of two dimensional materials by structural manipulation.
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Affiliation(s)
- Jun Chen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
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16
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Zhou S, Wang S, Shi Z, Sawada H, Kirkland AI, Li J, Warner JH. Atomically sharp interlayer stacking shifts at anti-phase grain boundaries in overlapping MoS 2 secondary layers. NANOSCALE 2018; 10:16692-16702. [PMID: 30155545 DOI: 10.1039/c8nr04486d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
When secondary domains nucleate and grow on the surface of monolayer MoS2, they can extend across grain boundaries in the underlying monolayer MoS2 and form overlapping sections. We present an atomic level study of overlapping antiphase grain boundaries (GBs) in MoS2 monolayer-bilayers using aberration-corrected annular dark field scanning transmission electron microscopy. In particular we focus on the antiphase GB within a monolayer and track its propagation through an overlapping bilayer domain. We show that this leads to an atomically sharp interface between 2H and 3R interlayer stacking in the bilayer region. We have studied the micro-nanoscale "meandering" of the antiphase GB in MoS2, which shows a directional dependence on the density of 4 and 8 member ring defects, as well as sharp turning angles 90°-100° that are mediated by a special 8-member ring defect. Density functional theory has been used to explore the overlapping interlayer stacking around the antiphase GBs, confirming our experimental findings. These results show that overlapping secondary bilayer MoS2 domains cause atomic structure modification to underlying anti-phase GB sites to accommodate the van der Waals interactions.
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Affiliation(s)
- Si Zhou
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK.
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17
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Wang S, Sawada H, Han X, Zhou S, Li S, Guo ZX, Kirkland AI, Warner JH. Preferential Pt Nanocluster Seeding at Grain Boundary Dislocations in Polycrystalline Monolayer MoS 2. ACS NANO 2018; 12:5626-5636. [PMID: 29762015 DOI: 10.1021/acsnano.8b01418] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We show that Pt nanoclusters preferentially nucleate along the grain boundaries (GBs) in polycrystalline MoS2 monolayer films, with dislocations acting as the seed site. Atomic resolution studies by aberration-corrected annular dark-field scanning transmission electron microscopy reveal periodic spacing of Pt nanoclusters with dependence on GB tilt angles and random spacings for the antiphase boundaries ( i.e., 60°). Individual Pt atoms are imaged within the dislocation core sections of the GB region, with various positions observed, including both the substitutional sites of Mo and the hollow center of the octahedral ring. The evolution from single atoms or small few atom clusters to nanosized particles of Pt is examined at the atomic level to gain a deep understanding of the pathways of Pt seed nucleation and growth at the GB. Density functional theory calculations confirm the energetic advantage of trapping Pt at dislocations on both the antiphase boundary and the small-angle GB rather than on the pristine lattice. The selective decoration of GBs by Pt nanoparticles also has a beneficial use to easily identify GB areas during microscopic-scale observations and track long-range nanoscale variances of GBs with spatial detail not easy to achieve using other methods. We show that GBs have nanoscale meandering across micron-scale distances with no strong preference for specific lattice directions across macroscopic ranges.
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Affiliation(s)
- Shanshan Wang
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
- Science and Technology on Advanced Ceramic Fibers & Composites Laboratory , National University of Defense Technology , Changsha 410073 , Hunan Province , China
| | - Hidetaka Sawada
- JEOL Ltd. , 3-1-2 Musashino , Akishima, Tokyo 196-8558 , Japan
| | - Xiaoyu Han
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Si Zhou
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Sha Li
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Zheng Xiao Guo
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Angus I Kirkland
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
- Electron Physical Sciences Imaging Center , Diamond Light Source Ltd. , Didcot OX11 0DE , United Kingdom
| | - Jamie H Warner
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
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18
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4D-Data Acquisition in Scanning Confocal Electron Microscopy for Depth-Sectioned Imaging. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2018. [DOI: 10.1380/ejssnt.2018.247] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Hamaoka T, Jao CY, Takeguchi M. Annular dark-field scanning confocal electron microscopy studied using multislice simulations. Microscopy (Oxf) 2018; 67:4995666. [PMID: 29762753 DOI: 10.1093/jmicro/dfy023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 04/25/2018] [Indexed: 11/13/2022] Open
Abstract
Annular dark-field scanning confocal electron microscopy (ADF-SCEM) has been studied using multislice simulations. Thermal diffuse scattering was considered in the calculations. Geometric aberrations of the lenses were introduced. A finite-sized pinhole was taken into consideration, in addition to an ideal point pinhole. ADF-SCEM images of Al crystals aligned along a zone-axis exhibit elongated contrast along the optic axis. Results of simulations suggest that if geometric aberrations of an imaging lens are corrected, depth resolution in ADF-SCEM can be improved by employing a large collection semi-angle of an annular aperture, even with a finite pinhole.
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Affiliation(s)
- Takumi Hamaoka
- Transmission Electron Microscopy Station, National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Chih-Yu Jao
- Transmission Electron Microscopy Station, National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Masaki Takeguchi
- Transmission Electron Microscopy Station, National Institute for Materials Science, Tsukuba 305-0047, Japan
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20
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Morishita S, Ishikawa R, Kohno Y, Sawada H, Shibata N, Ikuhara Y. Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector. Microscopy (Oxf) 2018; 67:46-50. [PMID: 29309606 DOI: 10.1093/jmicro/dfx122] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/25/2017] [Indexed: 11/13/2022] Open
Abstract
The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga-Ga atomic columns of GaN observed along [212] direction.
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Affiliation(s)
| | - Ryo Ishikawa
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
| | - Yuji Kohno
- JEOL Ltd, 3-1-2 Musashino, Akishima, Tokyo196-8558, Japan
| | | | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
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21
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Morishita S, Kohno Y, Hosokawa F, Suenaga K, Sawada H. Evaluation of residual aberration in fifth-order geometrical aberration correctors. Microscopy (Oxf) 2018; 67:156-163. [DOI: 10.1093/jmicro/dfy009] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 01/29/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Yuji Kohno
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Fumio Hosokawa
- BioNet Laboratory Inc., 2-3-28 Nishiki-chou, Tachikawa, Tokyo 190-0022, Japan
| | - Kazu Suenaga
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
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22
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Transmission Electron Microscopy of Carbon: A Brief History. C — JOURNAL OF CARBON RESEARCH 2018. [DOI: 10.3390/c4010004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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23
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Linck M, Ercius PA, Pierce JS, McMorran BJ. Aberration corrected STEM by means of diffraction gratings. Ultramicroscopy 2017. [DOI: 10.1016/j.ultramic.2017.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Wang S, Sawada H, Chen Q, Han GGD, Allen C, Kirkland AI, Warner JH. In Situ Atomic-Scale Studies of the Formation of Epitaxial Pt Nanocrystals on Monolayer Molybdenum Disulfide. ACS NANO 2017; 11:9057-9067. [PMID: 28806068 DOI: 10.1021/acsnano.7b03648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pt-nanocrystal:MoS2 hybrid materials have promising catalytic properties for hydrogen evolution, and understanding their detailed structures at the atomic scale is crucial to further development. Here, we use an in situ heating holder in an aberration-corrected transmission electron microscope to study the formation of Pt nanocrystals directly on the surface of monolayer MoS2 from a precursor on heating to 800 °C. Isolated single Pt atoms and small nanoclusters are observed after in situ heating, with two types of preferential alignment between the Pt nanocrystals and the underlying monolayer MoS2. Strain effects and thickness variations of the ultrasmall Pt nanocrystal supported on MoS2 are studied, revealing that single atomic planes are formed from a nonlayered face-centered cubic bulk Pt configuration with a lattice expansion of 7-10% compared to that of bulk Pt. The Pt nanocrystals are surrounded by an amorphous carbon layer and in some cases have etched the local surrounding MoS2 material after heating. Electron beam irradiation also initiates Pt nanocrystal etching of the local MoS2, and we study this process in real time at atomic resolution. These results show that the presence of carbon around the Pt nanocrystals does not affect their epitaxial relationship with the MoS2 lattice. Single Pt atoms within the carbon layer are also immobilized at high temperature. These results provide important insights into the formation of Pt:MoS2 hybrid materials.
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Affiliation(s)
- Shanshan Wang
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Hidetaka Sawada
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd, Harwell Science and Innovation Campus , Didcot, Oxfordshire OX11 0DE, United Kingdom
- JEOL UK Ltd. , Silver Court Watchmead, Welwyn Garden City, Hertfordshire AL7 1LT, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Grace G D Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Christopher Allen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd, Harwell Science and Innovation Campus , Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd, Harwell Science and Innovation Campus , Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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25
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Wang S, Sawada H, Allen CS, Kirkland AI, Warner JH. Orientation dependent interlayer stacking structure in bilayer MoS 2 domains. NANOSCALE 2017; 9:13060-13068. [PMID: 28837199 DOI: 10.1039/c7nr03198j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have studied the atomic structure of small secondary domains that nucleate on monolayer MoS2 grown by chemical vapour deposition (CVD), which form the basis of bilayer MoS2. The small secondary bilayer domains have a faceted geometry with three-fold symmetry and adopt two distinct orientations with 60° rotation relative to an underlying monolayer MoS2 single crystal sheet. The two distinct orientations are associated with the 2H and 3R stacking configuration for bilayer MoS2. Atomic resolution images have been recorded using annular dark field scanning transmission electron microscopy (ADF-STEM) that show the edge termination, lattice orientation and stacking sequence of the bilayer domains relative to the underlying monolayer MoS2. These results provide important insights that bilayer MoS2 growth from 60° rotated small nuclei on the surface of monolayer MoS2 could lead to defective boundaries when merged to form larger continuous bilayer regions and that pure AA' or AB bilayer stacking may be challenging unless from a single seed.
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Affiliation(s)
- Shanshan Wang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
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26
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Picometer-scale atom position analysis in annular bright-field STEM imaging. Ultramicroscopy 2017; 184:177-187. [PMID: 28934631 DOI: 10.1016/j.ultramic.2017.09.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/05/2017] [Accepted: 09/10/2017] [Indexed: 11/23/2022]
Abstract
We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and sample drift induced image distortion. We find that under a typical experimental condition a small specimen tilt (∼6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ∼3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends on the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of atomic structure as well as the properties such as oxygen octahedral distortion/shift.
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27
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Aberration measurement of the probe-forming system of an electron microscope using two-dimensional materials. Ultramicroscopy 2017; 182:195-204. [PMID: 28709084 DOI: 10.1016/j.ultramic.2017.06.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/27/2017] [Accepted: 06/19/2017] [Indexed: 11/22/2022]
Abstract
The geometric and chromatic aberration coefficients of the probe-forming system in an aberration corrected transmission electron microscope have been measured using a Ronchigram recorded from monolayer graphene. The geometric deformations within individual local angular sub-regions of the Ronchigram were analysed using an auto-correlation function and the aberration coefficients for the probe forming lens were calculated. This approach only requires the acquisition of a single Ronchigram allowing rapid measurement of the aberration coefficients. Moreover, the measurement precision for defocus and two-fold astigmatism is improved over that which can be achieved from analysis of Ronchigrams recorded from amorphous films. This technique can also be applied to aberration corrected STEM imaging of any hexagonal two-dimensional material.
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28
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Wang S, Li H, Sawada H, Allen CS, Kirkland AI, Grossman JC, Warner JH. Atomic structure and formation mechanism of sub-nanometer pores in 2D monolayer MoS 2. NANOSCALE 2017; 9:6417-6426. [PMID: 28463370 DOI: 10.1039/c7nr01127j] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We use electron-beam nanofabrication to create sub-nanometer (sub-nm) pores in 2D monolayer MoS2 with fine control over the pore size down to 0.6 nm, corresponding to the loss of a single Mo atom and surrounding S atoms. The sub-nm pores are created in situ with 1 nm spatial precision in the MoS2 lattice by control of the angstrom sized probe in an aberration corrected scanning transmission electron microscope with real time tracking of the pore creation. Dynamics of the sub-nm pore creation are captured at the atomic scale and reveal the mechanism of nanopore formation at accelerating voltages of 60 and 80 kV to be due to displacing a Mo atom from the lattice site onto the surface of the MoS2. This process is enabled by the destabilization of the Mo bonding from localized electron beam induced S atom loss. DFT calculations confirm the energetic advantage of having the ejected Mo atom attach on the sheet surface rather than being expelled into vacuum, and indicate sensitivity of the nanopore potential as a function of the adsorption position of the ejected Mo atom. These results provide detailed atomic level insights into the initial process of single Mo loss that underpins the nucleation of a nanopore and explains the formation mechanism of sub-nm pores in MoS2.
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Affiliation(s)
- Shanshan Wang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
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29
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Chang WY, Chen FR. Development of compact Cs corrector for desktop electron microscope. Ultramicroscopy 2017; 179:94-99. [PMID: 28460267 DOI: 10.1016/j.ultramic.2017.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 04/09/2017] [Accepted: 04/14/2017] [Indexed: 10/19/2022]
Abstract
The desktop Electron Microscopes (desktop EMs) have been commercialized in the recent years, offering a spatial resolution around 1nm in scanning-transmission mode in a routine operation. For the purpose of further improvement in spatial resolution and signal / noise, one may need an aberration corrector with a compact form in order to fit into a desktop EM. In this paper, the permanent magnets with tunable coil are implemented as a transfer lens doublet to realize a compact hexapole corrector for a desktop EM. It will be shown that, with a proper design of permanent magnet transfer lens doublet and hexapole lens, we can generate a negative Cs and avoid the second-order axial astigmatism to reduce the final spot size at the sample plane to be better than 0.5nm for a field emission source. To fulfill with the required condition of a hexapole corrector, a tunable lens is implemented to adjust the magnetic field for compensating the practical error from the permanent magnet.
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Affiliation(s)
- Wei-Yu Chang
- Engineering and System Science Department, National Tsing Hua University, Hsinchu 30013, Taiwan ROC
| | - Fu-Rong Chen
- Engineering and System Science Department, National Tsing Hua University, Hsinchu 30013, Taiwan ROC.
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30
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Li H, Wang S, Sawada H, Han GGD, Samuels T, Allen CS, Kirkland AI, Grossman JC, Warner JH. Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS 2. ACS NANO 2017; 11:3392-3403. [PMID: 28256826 DOI: 10.1021/acsnano.7b00796] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We have studied atomic level interactions between single Pt atoms and the surface of monolayer MoS2 using aberration-corrected annular dark field scanning transmission electron microscopy at an accelerating voltage of 60 kV. Strong contrast from single Pt atoms on the atomically resolved monolayer MoS2 lattice enables their exact position to be determined with respect to the MoS2 lattice, revealing stable binding sites. In regions of MoS2 free from surface contamination, the Pt atoms are localized in S vacancy sites and exhibit dynamic hopping to nearby vacancy sites driven by the energy supplied by the electron beam. However, in areas of MoS2 contaminated with carbon surface layers, the Pt atoms appear at various positions with respect to the underlying MoS2 lattice, including on top of Mo and in off-axis positions. These variations are due to the Pt bonding with the surrounding amorphous carbon layer, which disrupts the intrinsic Pt-MoS2 interactions, leading to more varied positions. Density functional theory (DFT) calculations reveal that Pt atoms on the surface of MoS2 have a small barrier for migration and are stabilized when bound to either a single or double sulfur vacancies. DFT calculations have been used to understand how the catalytic activity of the MoS2 basal plane for hydrogen evolution reaction is influenced by Pt dopants by variation of the hydrogen adsorption free energy. This strong dependence of catalytic effect on interfacial configurations is shown to be common for a series of dopants, which may provide a means to create and optimize reaction centers.
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Affiliation(s)
- Huashan Li
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Shanshan Wang
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Hidetake Sawada
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
- JEOL Ltd. , 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
- Electron Physical Sciences Imaging Center, Diamond Light Source Ltd , Didcot, Oxfordshire, OX11 0DE, United Kingdom
| | - Grace G D Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Thomas Samuels
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Christopher S Allen
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Ltd , Didcot, Oxfordshire, OX11 0DE, United Kingdom
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Ltd , Didcot, Oxfordshire, OX11 0DE, United Kingdom
| | - Jeffrey C Grossman
- Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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31
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Wadell C, Inagaki S, Nakamura T, Shi J, Nakamura Y, Sannomiya T. Nanocuvette: A Functional Ultrathin Liquid Container for Transmission Electron Microscopy. ACS NANO 2017; 11:1264-1272. [PMID: 28135067 DOI: 10.1021/acsnano.6b05007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Advances in TEM techniques have spurred a renewed interest in a wide variety of research fields. A rather recent track within these endeavors is the use of TEM for in situ imaging in liquids. In this article, we show the fabrication of a liquid cell for TEM observations which we call the nanocuvette. The structure consists of a nanohole film sandwiched by carbon films, sealing liquid in the holes. The hole film can be produced using a variety of materials, tailored for the desired application. Since the fabrication is based on self-assembly, it is both cheap and straightforward. Compared to previously reported liquid cells, this structure allows for thinner liquid layers with better controlled cell structures, making it possible to achieve a high resolution even at lower acceleration voltages and electron doses. We demonstrate a resolution corresponding to an information transfer up to ∼2 nm at 100 kV for molecular imaging. Apart from the advantages arising from the thin liquid layer, the nanocuvette also enables the possibility to study liquid-solid interfaces at the side walls of the nanoholes. We illustrate the possibilities of the nanocuvette by studying several model systems: electron beam induced growth dynamics of silver nanoparticles in salt solution, polymer deposition from solution, and imaging of nonstained antibodies in solution. Finally, we show how the inclusion of a plasmonically active gold layer in the nanocuvette structure enables optical confirmation of successful liquid encapsulation prior to TEM studies. The nanocuvette provides an easily fabricated and flexible platform which can help further the understanding of reactions, processes, and conformation of molecules and atoms in liquid environments.
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Affiliation(s)
- Carl Wadell
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
| | - Satoshi Inagaki
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
| | - Tomiro Nakamura
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
| | - Ji Shi
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
| | - Yoshio Nakamura
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
| | - Takumi Sannomiya
- Department of Materials Science and Engineering, School of Materials and Chemical Technologies, Tokyo Institute of Technology , 4259 Nagatsuta, Midoriku, Yokohama 226-8503 Japan
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Oxley MP, Lupini AR, Pennycook SJ. Ultra-high resolution electron microscopy. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:026101. [PMID: 28008874 DOI: 10.1088/1361-6633/80/2/026101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The last two decades have seen dramatic advances in the resolution of the electron microscope brought about by the successful correction of lens aberrations that previously limited resolution for most of its history. We briefly review these advances, the achievement of sub-Ångstrom resolution and the ability to identify individual atoms, their bonding configurations and even their dynamics and diffusion pathways. We then present a review of the basic physics of electron scattering, lens aberrations and their correction, and an approximate imaging theory for thin crystals which provides physical insight into the various different imaging modes. Then we proceed to describe a more exact imaging theory starting from Yoshioka's formulation and covering full image simulation methods using Bloch waves, the multislice formulation and the frozen phonon/quantum excitation of phonons models. Delocalization of inelastic scattering has become an important limiting factor at atomic resolution. We therefore discuss this issue extensively, showing how the full-width-half-maximum is the appropriate measure for predicting image contrast, but the diameter containing 50% of the excitation is an important measure of the range of the interaction. These two measures can differ by a factor of 5, are not a simple function of binding energy, and full image simulations are required to match to experiment. The Z-dependence of annular dark field images is also discussed extensively, both for single atoms and for crystals, and we show that temporal incoherence must be included accurately if atomic species are to be identified through matching experimental intensities to simulations. Finally we mention a few promising directions for future investigation.
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Affiliation(s)
- Mark P Oxley
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Robertson AW, Lin YC, Wang S, Sawada H, Allen CS, Chen Q, Lee S, Lee GD, Lee J, Han S, Yoon E, Kirkland AI, Kim H, Suenaga K, Warner JH. Atomic Structure and Spectroscopy of Single Metal (Cr, V) Substitutional Dopants in Monolayer MoS 2. ACS NANO 2016; 10:10227-10236. [PMID: 27934090 DOI: 10.1021/acsnano.6b05674] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dopants in two-dimensional dichalcogenides have a significant role in affecting electronic, mechanical, and interfacial properties. Controllable doping is desired for the intentional modification of such properties to enhance performance; however, unwanted defects and impurity dopants also have a detrimental impact, as often found for chemical vapor deposition (CVD) grown films. The reliable identification, and subsequent characterization, of dopants is therefore of significant importance. Here, we show that Cr and V impurity atoms are found in CVD grown MoS2 monolayer 2D crystals as single atom substitutional dopants in place of Mo. We attribute these impurities to trace elements present in the MoO3 CVD precursor. Simultaneous annular dark field scanning transmission electron microscopy (ADF-STEM) and electron energy loss spectroscopy (EELS) is used to map the location of metal atom substitutions of Cr and V in MoS2 monolayers with single atom precision. The Cr and V are stable under electron irradiation at 60 to 80 kV, when incorporated into line defects, and when heated to elevated temperatures. The combined ADF-STEM and EELS differentiates these Cr and V dopants from other similar contrast defect structures, such as 2S self-interstitials at the Mo site, preventing misidentification. Density functional theory calculations reveal that the presence of Cr or V causes changes to the density of states, indicating doping of the MoS2 material. These transferred impurities could help explain the presence of trapped charges in CVD prepared MoS2.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Yung-Chang Lin
- Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST) , AIST Central 5, Tsukuba 305-8564, Japan
| | - Shanshan Wang
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Hidetaka Sawada
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- JEOL Limited, 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Christopher S Allen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Sungwoo Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Joohee Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Seungwu Han
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Heeyeon Kim
- Convergence Materials Laboratory, Korea Institute of Energy Research , 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea
| | - Kazu Suenaga
- Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST) , AIST Central 5, Tsukuba 305-8564, Japan
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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Image transfer with spatial coherence for aberration corrected transmission electron microscopes. Ultramicroscopy 2016; 167:11-20. [DOI: 10.1016/j.ultramic.2016.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 11/20/2022]
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Hosokawa F, Shinkawa T, Arai Y, Sannomiya T. Benchmark test of accelerated multi-slice simulation by GPGPU. Ultramicroscopy 2015; 158:56-64. [PMID: 26183007 DOI: 10.1016/j.ultramic.2015.06.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/22/2015] [Accepted: 06/28/2015] [Indexed: 10/23/2022]
Abstract
A fast multi-slice image simulation by parallelized computation using a graphics processing unit (GPU) has been developed. The image simulation contains multiple sets of computing steps, such as Fourier transform and pixel-to-pixel operation. The efficiency of GPU varies depending on the type of calculation. In the effective case of utilizing GPU, the calculation speed is conducted hundreds of times faster than a central processing unit (CPU). The benchmark test of parallelized multi-slice was performed, and the results of contents, such as TEM imaging, STEM imaging and CBD calculation are reported. Some features of the simulation software are also introduced.
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Affiliation(s)
| | | | - Yoshihiro Arai
- Terabese Ltd, Hane-nishi 3-5-1-102, Okazaki 444-0838 Japan
| | - Takumi Sannomiya
- Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503, Japan
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Sawada H, Sasaki T, Hosokawa F, Suenaga K. Atomic-Resolution STEM Imaging of Graphene at Low Voltage of 30 kV with Resolution Enhancement by Using Large Convergence Angle. PHYSICAL REVIEW LETTERS 2015; 114:166102. [PMID: 25955058 DOI: 10.1103/physrevlett.114.166102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Indexed: 06/04/2023]
Abstract
Atomic resolution at a low accelerating voltage with aberration correction is required to reduce the electron irradiation damage in scanning transmission electron microscopy imaging. However, the reduction in resolution caused by the diffraction limit becomes severe with increasing electron wavelength at low accelerating voltages. The developed aberration corrector can compensate for higher-order aberration in scanning transmission electron microscopy to expand the uniform phase angle. The resolution for imaging graphene at 30 kV is evaluated by changing the convergence angle for a probe-forming system with a higher-order aberration corrector. A single-carbon atom on graphene is successfully imaged at atomic resolution with a cold-field emission gun by dark-field imaging at an accelerating voltage of 30 kV.
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Affiliation(s)
- H Sawada
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - T Sasaki
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - F Hosokawa
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - K Suenaga
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
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The correction of electron lens aberrations. Ultramicroscopy 2015; 156:A1-64. [PMID: 26025209 DOI: 10.1016/j.ultramic.2015.03.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 03/07/2015] [Accepted: 03/12/2015] [Indexed: 11/23/2022]
Abstract
The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague.
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Ishikawa R, Lupini AR, Hinuma Y, Pennycook SJ. Large-angle illumination STEM: Toward three-dimensional atom-by-atom imaging. Ultramicroscopy 2015; 151:122-129. [DOI: 10.1016/j.ultramic.2014.11.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/30/2014] [Accepted: 11/06/2014] [Indexed: 11/29/2022]
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Sawada H, Shimura N, Hosokawa F, Shibata N, Ikuhara Y. Resolving 45-pm-separated Si–Si atomic columns with an aberration-corrected STEM. Microscopy (Oxf) 2015; 64:213-7. [DOI: 10.1093/jmicro/dfv014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 03/08/2015] [Indexed: 11/12/2022] Open
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Sasaki T, Sawada H, Hosokawa F, Sato Y, Suenaga K. Aberration-corrected STEM/TEM imaging at 15 kV. Ultramicroscopy 2014; 145:50-5. [DOI: 10.1016/j.ultramic.2014.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 04/01/2014] [Accepted: 04/14/2014] [Indexed: 11/17/2022]
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Mukai M, Kim JS, Omoto K, Sawada H, Kimura A, Ikeda A, Zhou J, Kaneyama T, Young NP, Warner JH, Nellist PD, Kirkland AI. The development of a 200 kV monochromated field emission electron source. Ultramicroscopy 2014; 140:37-43. [PMID: 24657419 DOI: 10.1016/j.ultramic.2014.02.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/24/2014] [Accepted: 02/25/2014] [Indexed: 11/26/2022]
Abstract
We report the development of a monochromator for an intermediate-voltage aberration-corrected electron microscope suitable for operation in both STEM and TEM imaging modes. The monochromator consists of two Wien filters with a variable energy selecting slit located between them and is located prior to the accelerator. The second filter cancels the energy dispersion produced by the first filter and after energy selection forms a round monochromated, achromatic probe at the specimen plane. The ultimate achievable energy resolution has been measured as 36 meV at 200 kV and 26 meV at 80 kV. High-resolution Annular Dark Field STEM images recorded using a monochromated probe resolve Si-Si spacings of 135.8 pm using energy spreads of 218 meV at 200 kV and 217 meV at 80 kV respectively. In TEM mode an improvement in non-linear spatial resolution to 64 pm due to the reduction in the effects of partial temporal coherence has been demonstrated using broad beam illumination with an energy spread of 134 meV at 200 kV.
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Affiliation(s)
- Masaki Mukai
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
| | - Judy S Kim
- University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH, UK
| | - Kazuya Omoto
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | | | - Atsushi Kimura
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Akihiro Ikeda
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Jun Zhou
- JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | | | - Neil P Young
- University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH, UK
| | - Jamie H Warner
- University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH, UK
| | - Peter D Nellist
- University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH, UK
| | - Angus I Kirkland
- University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH, UK
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