1
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Coupin MJ, Wen Y, Lee S, Saxena A, Ophus C, Allen CS, Kirkland AI, Aluru NR, Lee GD, Warner JH. Mapping Nanoscale Electrostatic Field Fluctuations around Graphene Dislocation Cores Using Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM). NANO LETTERS 2023; 23:6807-6814. [PMID: 37487233 DOI: 10.1021/acs.nanolett.3c00328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Defects in crystalline lattices cause modulation of the atomic density, and this leads to variations in the associated electrostatics at the nanoscale. Mapping these spatially varying charge fluctuations using transmission electron microscopy has typically been challenging due to complicated contrast transfer inherent to conventional phase contrast imaging. To overcome this, we used four-dimensional scanning transmission electron microscopy (4D-STEM) to measure electrostatic fields near point dislocations in a monolayer. The asymmetry of the atomic density in a (1,0) edge dislocation core in graphene yields a local enhancement of the electric field in part of the dislocation core. Through experiment and simulation, the increased electric field magnitude is shown to arise from "long-range" interactions from beyond the nearest atomic neighbor. These results provide insights into the use of 4D-STEM to quantify electrostatics in thin materials and map out the lateral potential variations that are important for molecular and atomic bonding through Coulombic interactions.
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Affiliation(s)
- Matthew J Coupin
- Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yi Wen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Sungwoo Lee
- Department of Materials Science & Engineering, Seoul National University, Seoul 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Anshul Saxena
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 67, Berkeley, California 94720, United States
| | - Christopher S Allen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Science Imaging Centre, Diamond Light Source Ltd., Didcot OX11 0DE, U.K
| | - Angus I Kirkland
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Science Imaging Centre, Diamond Light Source Ltd., Didcot OX11 0DE, U.K
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Narayana R Aluru
- Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Gun-Do Lee
- Department of Materials Science & Engineering, Seoul National University, Seoul 08826, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea
| | - Jamie H Warner
- Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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2
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Ooe K, Seki T, Yoshida K, Kohno Y, Ikuhara Y, Shibata N. Direct imaging of local atomic structures in zeolite using optimum bright-field scanning transmission electron microscopy. SCIENCE ADVANCES 2023; 9:eadf6865. [PMID: 37531431 PMCID: PMC10396294 DOI: 10.1126/sciadv.adf6865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 06/28/2023] [Indexed: 08/04/2023]
Abstract
Zeolites are used in industries as catalysts, ion exchangers, and molecular sieves because of their unique porous atomic structures. However, direct observation of zeolitic local atomic structures via electron microscopy is difficult owing to low electron irradiation resistance. Subsequently, their fundamental structure-property relationships remain unclear. A low-electron-dose imaging technique, optimum bright-field scanning transmission electron microscopy (OBF STEM), has recently been developed. It reconstructs images with a high signal-to-noise ratio and a dose efficiency approximately two orders of magnitude higher than that of conventional methods. Here, we performed low-dose atomic-resolution OBF STEM observations of two types of zeolite, effectively visualizing all atomic sites in their frameworks. In addition, we visualized the complex local atomic structure of the twin boundaries in a faujasite (FAU)-type zeolite and Na+ ions with low occupancy in eight-membered rings in a Na-Linde Type A (LTA) zeolite. The results of this study facilitate the characterization of local atomic structures in many electron beam-sensitive materials.
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Affiliation(s)
- Kousuke Ooe
- Institute of Engineering Innovation, School of Engineering, the University of Tokyo, Yayoi 2-11-16, Bunkyo, Tokyo 113-0032, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Mutsuno 2-4-1, Atsuta, Nagoya 456-8587, Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering, the University of Tokyo, Yayoi 2-11-16, Bunkyo, Tokyo 113-0032, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Kaname Yoshida
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Mutsuno 2-4-1, Atsuta, Nagoya 456-8587, Japan
| | - Yuji Kohno
- JEOL Ltd., 1-2-3 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, the University of Tokyo, Yayoi 2-11-16, Bunkyo, Tokyo 113-0032, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Mutsuno 2-4-1, Atsuta, Nagoya 456-8587, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, the University of Tokyo, Yayoi 2-11-16, Bunkyo, Tokyo 113-0032, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Mutsuno 2-4-1, Atsuta, Nagoya 456-8587, Japan
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3
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Savitzky BH, Zeltmann SE, Hughes LA, Brown HG, Zhao S, Pelz PM, Pekin TC, Barnard ES, Donohue J, Rangel DaCosta L, Kennedy E, Xie Y, Janish MT, Schneider MM, Herring P, Gopal C, Anapolsky A, Dhall R, Bustillo KC, Ercius P, Scott MC, Ciston J, Minor AM, Ophus C. py4DSTEM: A Software Package for Four-Dimensional Scanning Transmission Electron Microscopy Data Analysis. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:712-743. [PMID: 34018475 DOI: 10.1017/s1431927621000477] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Scanning transmission electron microscopy (STEM) allows for imaging, diffraction, and spectroscopy of materials on length scales ranging from microns to atoms. By using a high-speed, direct electron detector, it is now possible to record a full two-dimensional (2D) image of the diffracted electron beam at each probe position, typically a 2D grid of probe positions. These 4D-STEM datasets are rich in information, including signatures of the local structure, orientation, deformation, electromagnetic fields, and other sample-dependent properties. However, extracting this information requires complex analysis pipelines that include data wrangling, calibration, analysis, and visualization, all while maintaining robustness against imaging distortions and artifacts. In this paper, we present py4DSTEM, an analysis toolkit for measuring material properties from 4D-STEM datasets, written in the Python language and released with an open-source license. We describe the algorithmic steps for dataset calibration and various 4D-STEM property measurements in detail and present results from several experimental datasets. We also implement a simple and universal file format appropriate for electron microscopy data in py4DSTEM, which uses the open-source HDF5 standard. We hope this tool will benefit the research community and help improve the standards for data and computational methods in electron microscopy, and we invite the community to contribute to this ongoing project.
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Affiliation(s)
- Benjamin H Savitzky
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Steven E Zeltmann
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Lauren A Hughes
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Hamish G Brown
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Shiteng Zhao
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Philipp M Pelz
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Thomas C Pekin
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489Berlin, Germany
| | - Edward S Barnard
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Jennifer Donohue
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Luis Rangel DaCosta
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI48109, USA
| | - Ellis Kennedy
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Yujun Xie
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | | | | | | | | | | | - Rohan Dhall
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Karen C Bustillo
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Peter Ercius
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Mary C Scott
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Jim Ciston
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
| | - Andrew M Minor
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA94720, USA
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA
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4
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Seki T, Ikuhara Y, Shibata N. Toward quantitative electromagnetic field imaging by differential-phase-contrast scanning transmission electron microscopy. Microscopy (Oxf) 2021; 70:148-160. [PMID: 33150939 DOI: 10.1093/jmicro/dfaa065] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/26/2020] [Accepted: 10/30/2020] [Indexed: 11/14/2022] Open
Abstract
Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is a technique to directly visualize local electromagnetic field distribution inside materials and devices at very high spatial resolution. Owing to the recent progress in the development of high-speed segmented and pixelated detectors, DPC STEM now constitutes one of the major imaging modes in modern aberration-corrected STEM. While qualitative imaging of electromagnetic fields by DPC STEM is readily possible, quantitative imaging by DPC STEM is still under development because of the several fundamental issues inherent in the technique. In this report, we review the current status and future prospects of DPC STEM for quantitative electromagnetic field imaging from atomic scale to mesoscopic scale.
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Affiliation(s)
- Takehito Seki
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan.,Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-8656, Japan.,Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan.,Quantum-Phase Electronics Center (QPEC), The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan
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5
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Bürger J, Riedl T, Lindner JKN. Influence of lens aberrations, specimen thickness and tilt on differential phase contrast STEM images. Ultramicroscopy 2020; 219:113118. [PMID: 33126186 DOI: 10.1016/j.ultramic.2020.113118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 07/30/2020] [Accepted: 09/13/2020] [Indexed: 12/01/2022]
Abstract
Differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM) allows for measuring electric and magnetic fields in solids on scales ranging from picometres to micrometres. The DPC technique mainly uses the direct beam, which is deflected by the electric and magnetic fields of the specimen and measured with a beam position sensitive detector. The beam deflection and thus the DPC signal is strongly influenced by specimen thickness, specimen tilt and lens aberrations. Understanding these influences is critical for a solid interpretation and quantification of contrasts in DPC images. To this end, the present study employs DPC-STEM image simulations of SrTiO3 [001] at atomic resolution to analyse the influence of lens aberrations, specimen tilt and thickness and also to give a guideline for the detection of parameters affecting the contrast by performing an analysis of associated scattergrams. Simulations are obtained using the multislice algorithm implemented in the Dr. Probe software with conditions corresponding to a JEOL ARM200F microscope equipped with an octa-segmented annular detector, but results should be similar for other microscopes. Simulations show that due to a non-rigid shift of the detected intensity distribution correct values of projected potentials of specimens thicker than one unit-cell cannot be determined. Regarding the impact of residual lens aberrations, it is found that the shape of the lens aberration phase function determines the symmetry and features in the DPC image. Specimen tilt leads to an elongation of features perpendicular to the tilt axis. The results are confirmed by comparing simulated with experimental DPC images of Si [110] yielding good agreement. Overall, a high sensitivity of DPC-STEM imaging to lens aberrations, specimen tilt and diffraction effects is evidenced.
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Affiliation(s)
- Julius Bürger
- Paderborn University, Department of Physics, Warburger Str. 100, 33098 Paderborn, Germany; Center for Optoelectronics and Photonics Paderborn CeOPP, Paderborn University, 33098 Paderborn, Germany; Institute of Lightweight Design with Hybrid Materials ILH, Paderborn University, 33098 Paderborn, Germany.
| | - Thomas Riedl
- Paderborn University, Department of Physics, Warburger Str. 100, 33098 Paderborn, Germany; Center for Optoelectronics and Photonics Paderborn CeOPP, Paderborn University, 33098 Paderborn, Germany; Institute of Lightweight Design with Hybrid Materials ILH, Paderborn University, 33098 Paderborn, Germany.
| | - Jörg K N Lindner
- Paderborn University, Department of Physics, Warburger Str. 100, 33098 Paderborn, Germany; Center for Optoelectronics and Photonics Paderborn CeOPP, Paderborn University, 33098 Paderborn, Germany; Institute of Lightweight Design with Hybrid Materials ILH, Paderborn University, 33098 Paderborn, Germany.
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6
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Zhang C, Feng Y, Han Z, Gao S, Wang M, Wang P. Electrochemical and Structural Analysis in All-Solid-State Lithium Batteries by Analytical Electron Microscopy: Progress and Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903747. [PMID: 31660670 DOI: 10.1002/adma.201903747] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/14/2019] [Indexed: 06/10/2023]
Abstract
Advanced scanning transmission electron microscopy (STEM) and its associated instruments have made significant contributions to the characterization of all-solid-state (ASS) Li batteries, as these tools provide localized information on the structure, morphology, chemistry, and electronic state of electrodes, electrolytes, and their interfaces at the nano- and atomic scale. Furthermore, the rapid development of in situ techniques has enabled a deep understanding of interfacial dynamic behavior and heterogeneous characteristics during the cycling process. However, due to the beam-sensitive nature of light elements in the interphases, e.g., Li and O, thorough and reliable studies of the interfacial structure and chemistry at an ultrahigh spatial resolution without beam damage is still a formidable challenge. Herein, the following points are discussed: (1) the recent contributions of advanced STEM to the study of ASS Li batteries; (2) current challenges associated with using this method; and (3) potential opportunities for combining cryo-electron microscopy and the STEM phase contrast imaging techniques.
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Affiliation(s)
- Chunchen Zhang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Yuzhang Feng
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Zhen Han
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Si Gao
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Meiyu Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Peng Wang
- National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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7
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Toyama S, Seki T, Anada S, Sasaki H, Yamamoto K, Ikuhara Y, Shibata N. Quantitative electric field mapping of a p-n junction by DPC STEM. Ultramicroscopy 2020; 216:113033. [PMID: 32570133 DOI: 10.1016/j.ultramic.2020.113033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/09/2020] [Accepted: 05/24/2020] [Indexed: 10/24/2022]
Abstract
Local electromagnetic fields in a specimen is measured at high spatial resolutions using differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). According to previous studies, DPC signals can be quantified by measuring the center of mass of the diffraction pattern intensity and/or performing a deconvolution method based on a phase contrast transfer function (PCTF). However, when using a segmented detector, the field strength has been considerably underestimated for a very thick specimen. The main cause of the underestimation is assumed to be inelastic scattering, mainly bulk plasmon scattering. In this study, we develop a method to remove this inelastic scattering effect from segmented detector DPC signals by modifying the PCTF deconvolution method. Field quantification results using this new technique are compared with those using pixelated detector DPC and electron holography, and all results indicated good agreement within an error margin.
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Affiliation(s)
- Satoko Toyama
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Satoshi Anada
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Hirokazu Sasaki
- Advanced Technologies R&D Laboratories, Furukawa Electric Co., Ltd., Yokohama 220-0073, Japan
| | - Kazuo Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan.
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8
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Campanini M, Erni R, Rossell MD. Probing local order in multiferroics by transmission electron microscopy. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2019-0068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The ongoing trend toward miniaturization has led to an increased interest in the magnetoelectric effect, which could yield entirely new device concepts, such as electric field-controlled magnetic data storage. As a result, much work is being devoted to developing new robust room temperature (RT) multiferroic materials that combine ferromagnetism and ferroelectricity. However, the development of new multiferroic devices has proved unexpectedly challenging. Thus, a better understanding of the properties of multiferroic thin films and the relation with their microstructure is required to help drive multiferroic devices toward technological application. This review covers in a concise manner advanced analytical imaging methods based on (scanning) transmission electron microscopy which can potentially be used to characterize complex multiferroic materials. It consists of a first broad introduction to the topic followed by a section describing the so-called phase-contrast methods, which can be used to map the polar and magnetic order in magnetoelectric multiferroics at different spatial length scales down to atomic resolution. Section 3 is devoted to electron nanodiffraction methods. These methods allow measuring local strains, identifying crystal defects and determining crystal structures, and thus offer important possibilities for the detailed structural characterization of multiferroics in the ultrathin regime or inserted in multilayers or superlattice architectures. Thereafter, in Section 4, methods are discussed which allow for analyzing local strain, whereas in Section 5 methods are addressed which allow for measuring local polarization effects on a length scale of individual unit cells. Here, it is shown that the ferroelectric polarization can be indirectly determined from the atomic displacements measured in atomic resolution images. Finally, a brief outlook is given on newly established methods to probe the behavior of ferroelectric and magnetic domains and nanostructures during in situ heating/electrical biasing experiments. These in situ methods are just about at the launch of becoming increasingly popular, particularly in the field of magnetoelectric multiferroics, and shall contribute significantly to understanding the relationship between the domain dynamics of multiferroics and the specific microstructure of the films providing important guidance to design new devices and to predict and mitigate failures.
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9
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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: 43] [Impact Index Per Article: 8.6] [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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10
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Affiliation(s)
| | - Mark P Oxley
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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11
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Sánchez-Santolino G, Lugg NR, Seki T, Ishikawa R, Findlay SD, Kohno Y, Kanitani Y, Tanaka S, Tomiya S, Ikuhara Y, Shibata N. Probing the Internal Atomic Charge Density Distributions in Real Space. ACS NANO 2018; 12:8875-8881. [PMID: 30074756 DOI: 10.1021/acsnano.8b03712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Probing the charge density distributions in materials at atomic scale remains an extremely demanding task, particularly in real space. However, recent advances in differential phase contrast-scanning transmission electron microscopy (DPC-STEM) bring this possibility closer by directly visualizing the atomic electric field. DPC-STEM at atomic resolutions measures how a sub-angstrom electron probe passing through a material is affected by the atomic electric field, the field between the nucleus and the surrounding electrons. Here, we perform a fully quantitative analysis which allows us to probe the charge density distributions inside atoms, including both the positive nuclear and the screening electronic charges, with subatomic resolution and in real space. By combining state-of-the-art DPC-STEM experiments with advanced electron scattering simulations we are able to map the spatial distribution of the electron cloud within individual atomic columns. This work constitutes a crucial step toward the direct atomic scale determination of the local charge redistributions and modulations taking place in materials systems.
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Affiliation(s)
- Gabriel Sánchez-Santolino
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Nathan R Lugg
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Ryo Ishikawa
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Scott D Findlay
- School of Physics and Astronomy , Monash University , Clayton , Victoria 3800 , Australia
| | - Yuji Kohno
- Electron Optics Division JEOL Limited, Tokyo 196-8558 , Japan
| | - Yuya Kanitani
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Shinji Tanaka
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Shigetaka Tomiya
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno , Atsuta-ku, Nagoya 456-8587 , Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno , Atsuta-ku, Nagoya 456-8587 , Japan
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