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Zhao Q, Zhu Q, Zhang Z, Yin B, Gao H, Zhou H. A machine learning-based framework for mapping hydrogen at the atomic scale. Proc Natl Acad Sci U S A 2024; 121:e2410968121. [PMID: 39284065 PMCID: PMC11441556 DOI: 10.1073/pnas.2410968121] [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: 06/03/2024] [Accepted: 08/12/2024] [Indexed: 10/02/2024] Open
Abstract
Hydrogen, the lightest and most abundant element in the universe, plays essential roles in a variety of clean energy technologies and industrial processes. For over a century, it has been known that hydrogen can significantly degrade the mechanical properties of materials, leading to issues like hydrogen embrittlement. A major challenge that has significantly limited scientific advances in this field is that light atoms like hydrogen are difficult to image, even with state-of-the-art microscopic techniques. To address this challenge, here, we introduce Atom-H, a versatile and generalizable machine learning-based framework for imaging hydrogen atoms at the atomic scale. Using a high-resolution electron microscope image as input, Atom-H accurately captures the distribution of hydrogen atoms and local stresses at lattice defects, including dislocations, grain boundaries, cracks, and phase boundaries. This provides atomic-scale insights into hydrogen-governed mechanical behaviors in metallic materials, including pure metals like Ni, Fe, Ti and alloys like FeCr. The proposed framework has an immediate impact on current research into hydrogen embrittlement and is expected to have far-reaching implications for mapping "invisible" atoms in other scientific disciplines.
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Affiliation(s)
- Qingkun Zhao
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Center for X-mechanics, Zhejiang University, Hangzhou 310027, People's Republic of China
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Qi Zhu
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Zhenghao Zhang
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Center for X-mechanics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Binglun Yin
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Center for X-mechanics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
- Department of Engineering Mechanics, Mechano-X Institute, Applied Mechanics Laboratory, Tsinghua University, Beijing 100084, People's Republic of China
| | - Haofei Zhou
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Center for X-mechanics, Zhejiang University, Hangzhou 310027, People's Republic of China
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2
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Luo L, Liu X, Zhao X, Zhang X, Peng HJ, Ye K, Jiang K, Jiang Q, Zeng J, Zheng T, Xia C. Pressure-induced generation of heterogeneous electrocatalytic metal hydride surfaces for sustainable hydrogen transfer. Nat Commun 2024; 15:7845. [PMID: 39245756 PMCID: PMC11381543 DOI: 10.1038/s41467-024-52228-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 08/27/2024] [Indexed: 09/10/2024] Open
Abstract
Metal hydrides are crucial intermediates in numerous catalytic reactions. Intensive efforts have been dedicated to constructing molecular metal hydrides, where toxic precursors and delicate mediators are usually involved. Herein, we demonstrate a facile pressure-induced methodology to generate a cost-effective heterogeneous electrocatalytic metal hydride surface for sustainable hydrogen transfer. Taking carbon dioxide (CO2) electroreduction as a model system and zinc (Zn), a well-known carbon monoxide (CO)-selective catalyst, as a model catalyst, we showcase a homogeneous-type hydrogen atom transfer process induced by heterogeneous hydride surfaces, enabling direct hydrogenation pathways traditionally considered "prohibited". Specifically, the maximal Faradaic efficiency for formate is enhanced by ~fivefold to 83% under ambient conditions. Experimental and theoretical analyses reveal that unlike the distal hydrogenation route for CO2 to CO over pristine Zn, the Zn hydride surface enables direct hydrogenation at the carbon site of CO2 to form formate. This work provides a promising material platform for sustainable synthesis.
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Affiliation(s)
- Laihao Luo
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, Anhui, P. R. China
| | - Xinyan Liu
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
| | - Xinyu Zhao
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, Anhui, P. R. China
| | - Xinyan Zhang
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, Anhui, P. R. China
| | - Hong-Jie Peng
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, 313001, Huzhou, Zhejiang, P. R. China
| | - Ke Ye
- Interdisciplinary Research Center, Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, 200240, Shanghai, P. R. China
| | - Kun Jiang
- Interdisciplinary Research Center, Institute of Fuel Cells, School of Mechanical Engineering, Shanghai Jiao Tong University, 200240, Shanghai, P. R. China
| | - Qiu Jiang
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
| | - Jie Zeng
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, Anhui, P. R. China
- School of Chemistry & Chemical Engineering, Anhui University of Technology, 243002, Ma'anshan, Anhui, P. R. China
| | - Tingting Zheng
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China
| | - Chuan Xia
- School of Materials and Energy, University of Electronic Science and Technology of China, 611731, Chengdu, P. R. China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, 313001, Huzhou, Zhejiang, P. R. China.
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3
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Jiang Y, Niu J, Wang C, Xue D, Shi X, Gao W, Zhao S. Experimental demonstration of tunable hybrid improper ferroelectricity in double-perovskite superlattice films. Nat Commun 2024; 15:5549. [PMID: 38956065 PMCID: PMC11219787 DOI: 10.1038/s41467-024-49707-x] [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: 03/20/2024] [Accepted: 06/17/2024] [Indexed: 07/04/2024] Open
Abstract
Hybrid improper ferroelectricity can effectively avoid the intrinsic chemical incompatibility of electronic mechanism for multiferroics. Perovskite superlattices, as theoretically proposed hybrid improper ferroelectrics with simple structure and high technological compatibility, are conducive to device integration and miniaturization, but the experimental realization remains elusive. Here, we report a strain-driven oxygen octahedral distortion strategy for hybrid improper ferroelectricity in La2NiMnO6/La2CoMnO6 double-perovskite superlattices. The epitaxial growth mode with mixed crystalline orientations maintains a large strain transfer distance more than 90 nm in the superlattice films with lattice mismatch less than 1%. Such epitaxial strain permits sustainable long-range modulation of oxygen octahedral rotation and tilting, thereby inducing and regulating hybrid improper ferroelectricity. A robust room-temperature ferroelectricity with remnant polarization of ~ 0.16 μC cm-2 and piezoelectric coefficient of 2.0 pm V-1 is obtained, and the density functional theory calculations and Landau-Ginsburg-Devonshire theory reveal the constitutive correlations between ferroelectricity, octahedral distortions, and strain. This work addresses the gap in experimental studies of hybrid improper ferroelectricity for perovskite superlattices and provides a promising research platform and idea for designing and exploring hybrid improper ferroelectricity.
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Affiliation(s)
- Yaoxiang Jiang
- Inner Mongolia Key Lab of Nanoscience and Nanotechnology & School of Physical Science and Technology, Inner Mongolia University, Hohhot, PR China
| | - Jianguo Niu
- Inner Mongolia Key Lab of Nanoscience and Nanotechnology & School of Physical Science and Technology, Inner Mongolia University, Hohhot, PR China
| | - Cong Wang
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing, China.
| | - Donglai Xue
- Inner Mongolia Key Lab of Nanoscience and Nanotechnology & School of Physical Science and Technology, Inner Mongolia University, Hohhot, PR China
| | - Xiaohui Shi
- Inner Mongolia Key Lab of Nanoscience and Nanotechnology & School of Physical Science and Technology, Inner Mongolia University, Hohhot, PR China
| | - Weibo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Shifeng Zhao
- Inner Mongolia Key Lab of Nanoscience and Nanotechnology & School of Physical Science and Technology, Inner Mongolia University, Hohhot, PR China.
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4
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Baucom G, Hershkovitz E, Chojecki P, Nishida T, Tabrizian R, Kim H. Nanoscale Phase and Orientation Mapping in Multiphase Polycrystalline Hafnium Zirconium Oxide Thin Films Using 4D-STEM and Automated Diffraction Indexing. SMALL METHODS 2024:e2400395. [PMID: 38754074 DOI: 10.1002/smtd.202400395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/01/2024] [Indexed: 05/18/2024]
Abstract
Ferroelectric hafnium zirconium oxide (HZO) holds promise for nextgeneration memory and transistors due to its superior scalability and seamless integration with complementary metal-oxide-semiconductor processing. A major challenge in developing this emerging ferroelectric material is the metastable nature of the non-centrosymmetric polar phase responsible for ferroelectricity, resulting in a coexistence of both polar and non-polar phases with uneven grain sizes and random orientations. Due to the structural similarity between the multiple phases and the nanoscale dimensions of the thin film devices, accurate measurement of phase-specific information remains challenging. Here, the application of 4D scanning transmission electron microscopy is demonstrated with automated electron diffraction pattern indexing to analyze multiphase polycrystalline HZO thin films, enabling the characterization of crystallographic phase and orientation across large working areas on the order of hundreds of nanometers. This approach offers a powerful characterization framework to produce a quantitative and statistically robust analysis of the intricate structure of HZO films by uncovering phase composition, polarization axis alignment, and unique phase distribution within the HZO film. This study introduces a novel approach for analyzing ferroelectric HZO, facilitating reliable characterization of process-structure-property relationships imperative to accelerating the growth optimization, performance, and successful implementation of ferroelectric HZO in devices.
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Affiliation(s)
- Garrett Baucom
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Eitan Hershkovitz
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Paul Chojecki
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Toshikazu Nishida
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Roozbeh Tabrizian
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Honggyu Kim
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
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5
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Liu Z, Nakamura H, Akai T. In Situ TEM/STEM Investigation of Crystallization in Y 3Al 5O 12:Ce at High Temperatures Inside a Transmission Electron Microscope. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2308001. [PMID: 38100205 DOI: 10.1002/smll.202308001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/06/2023] [Indexed: 01/31/2024]
Abstract
Y3Al5O12:Ce (YAG:Ce) phosphors are extensively used in the field of white light-emitting diodes (LEDs) due to their efficient luminescent properties. To optimize the performance of YAG:Ce phosphors, a comprehensive understanding of their synthesis and structural evolution is essential. This paper presents a direct in situ transmission electron microscopy (TEM) /scanning TEM (STEM) investigation on the transformation process of a precursor comprising nanocrystalline CeO2 dispersed in an amorphous Y-Al oxide matrix into crystalline YAG:Ce particles. The study reveals that nanocrystalline CeO2 particles dissolve completely in the Y-Al oxide matrix at a temperature above 900 °C, while YAlO3 (YAP)-type crystalline particles with Al2O3 phase in grain boundaries are observed above 1000 °C. Finally, YAG:Ce-type crystalline particles are formed above 1180 °C. Atomic-resolution energy-dispersive X-ray spectroscopy (EDS) elemental mapping demonstrates that the doped cerium (Ce) atoms occupy the same atomic sites as yttrium (Y). Photoluminescence measurements validate the efficient luminescent properties of the obtained YAG:Ce phosphor.
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Affiliation(s)
- Zheng Liu
- Innovative Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 4-205 Sakurazaka, Moriyamaku, Nagoya, Aichi, 463-8560, Japan
| | - Hitomi Nakamura
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka, 563-8577, Japan
| | - Tomoko Akai
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka, 563-8577, Japan
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6
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Tsurusawa H, Uzuhashi J, Kozuka Y, Kimoto K, Ohkubo T. Robust Preparation of Sub-20-nm-Thin Lamellae for Aberration-Corrected Electron Microscopy. SMALL METHODS 2024:e2301425. [PMID: 38389181 DOI: 10.1002/smtd.202301425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/24/2024] [Indexed: 02/24/2024]
Abstract
Aberration-corrected scanning transmission electron microscopy (STEM) has been advancing resolution, sensitivity, and microanalysis due to the intense demands of atomic-level microstructural investigations. Recent STEM technologies require preparing a thin lamella whose thickness is ideally below 20 nm. Although focused-ion-beam/scanning-electron-microscopy (FIB/SEM) is an established method to prepare a high-quality lamella, nanometer-level controllability of lamella thickness remains a fundamental problem. Here, the robust preparation of a sub-20-nm-thin lamella is demonstrated by FIB/SEM with real-time feedback from thickness quantification. The lamella thickness is quantified by back-scattered-electron SEM imaging in a thickness range between 0 and 100 nm without any reference to numerical simulation. Using real-time feedback from the thickness quantification, the FIB/SEM terminates thinning a lamella at a targeted thickness. The real-time feedback system eventually provides 1-nm-level controllability of the lamella thickness. As a proof-of-concept, a near-10-nm-thin lamella is prepared from a SrTiO3 crystal by our methodology. Moreover, the lamella thickness is controllable at a target heterointerface. Thus, a sub-20-nm-thin lamella is prepared from a LaAlO3 /SrTiO3 heterointerface. The methodology offers a robust and operator-independent platform to prepare a sub-20-nm-thin lamella from various materials. This platform will broadly impact aberration-corrected STEM studies in materials science and the semiconductor industry.
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Affiliation(s)
- Hideyo Tsurusawa
- LQUOM Inc., 79-5, Tokiwadai, Hodogaya, Yokohama, 240-8501, Japan
| | - Jun Uzuhashi
- National Institute for Materials Science (NIMS), Research Center for Magnetic and Spintronic Materials, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - Yusuke Kozuka
- National Institute for Materials Science (NIMS), Research Center for Materials Nanoarchitectonics (MANA), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Koji Kimoto
- National Institute for Materials Science (NIMS), Center for Basic Research on Materials, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - Tadakatsu Ohkubo
- National Institute for Materials Science (NIMS), Research Center for Magnetic and Spintronic Materials, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
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7
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Won J, Bae J, Kim H, Kim T, Nemati N, Choi S, Jung MC, Kim S, Choi H, Kim B, Jin D, Kim M, Han MJ, Kim JY, Shim W. Polytypic Two-Dimensional FeAs with High Anisotropy. NANO LETTERS 2023. [PMID: 38048278 DOI: 10.1021/acs.nanolett.3c03324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
In the realm of two-dimensional (2D) crystal growth, the chemical composition often determines the thermodynamically favored crystallographic structures. This relationship poses a challenge in synthesizing novel 2D crystals without altering their chemical elements, resulting in the rarity of achieving specific crystallographic symmetries or lattice parameters. We present 2D polymorphic FeAs crystals that completely differ from bulk orthorhombic FeAs (Pnma), differing in the stacking sequence, i.e., polytypes. Preparing polytypic FeAs outlines a strategy for independently controlling each symmetry operator, which includes the mirror plane for 2Q-FeAs (I4/mmm) and the glide plane for 1Q-FeAs (P4/nmm). As such, compared to bulk FeAs, polytypic 2D FeAs shows highly anisotropic properties such as electrical conductivity, Young's modulus, and friction coefficient. This work represents a concept of expanding 2D crystal libraries with a given chemical composition but various crystal symmetries.
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Affiliation(s)
- Jongbum Won
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Jihong Bae
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Hyesoo Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Taeyoung Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Narguess Nemati
- Department of Mechanical and Production Engineering, Aarhus University, 8000 Aarhus C, Denmark
| | - Sangjin Choi
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Myung-Chul Jung
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Sungsoon Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Hong Choi
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Bokyeong Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Dana Jin
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Minjun Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
| | - Myung Joon Han
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Jong-Young Kim
- Icheon branch, Korea Institute of Ceramic Engineering and Technology, Icheon 17303, Korea
| | - Wooyoung Shim
- Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
- Center for Multi-Dimensional Materials, Yonsei University, Seoul 03722, Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul 03722, Korea
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8
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Zheng A, Yin K, Pan R, Zhu M, Xiong Y, Sun L. Research Progress on Metal-Organic Frameworks by Advanced Transmission Electron Microscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111742. [PMID: 37299645 DOI: 10.3390/nano13111742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/19/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023]
Abstract
Metal-organic frameworks (MOFs), composed of metal nodes and inorganic linkers, are promising for a wide range of applications due to their unique periodic frameworks. Understanding structure-activity relationships can facilitate the development of new MOFs. Transmission electron microscopy (TEM) is a powerful technique to characterize the microstructures of MOFs at the atomic scale. In addition, it is possible to directly visualize the microstructural evolution of MOFs in real time under working conditions via in situ TEM setups. Although MOFs are sensitive to high-energy electron beams, much progress has been made due to the development of advanced TEM. In this review, we first introduce the main damage mechanisms for MOFs under electron-beam irradiation and two strategies to minimize these damages: low-dose TEM and cryo-TEM. Then we discuss three typical techniques to analyze the microstructure of MOFs, including three-dimensional electron diffraction, imaging using direct-detection electron-counting cameras, and iDPC-STEM. Groundbreaking milestones and research advances of MOFs structures obtained with these techniques are highlighted. In situ TEM studies are reviewed to provide insights into the dynamics of MOFs induced by various stimuli. Additionally, perspectives are analyzed for promising TEM techniques in the research of MOFs' structures.
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Affiliation(s)
- Anqi Zheng
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
| | - Kuibo Yin
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
| | - Rui Pan
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
| | - Mingyun Zhu
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
| | - Yuwei Xiong
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
| | - Litao Sun
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
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9
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Krause FF, Schowalter M, Gerken B, Marquardt D, Grieb T, Mehrtens T, Mahr C, Rosenauer A. Dose efficient annular bright field contrast with the ISTEM method: A proof of principle demonstration. Ultramicroscopy 2023; 245:113661. [PMID: 36529039 DOI: 10.1016/j.ultramic.2022.113661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 11/21/2022] [Accepted: 12/03/2022] [Indexed: 12/13/2022]
Abstract
The ISTEM mode for TEM has been demonstrated to have several advantages in regard to resolution and precision. While previous works primarily focussed on the advantages due to the reduced spatial coherence, the actual image contrast, i.e. how bright or dark certain atom columns are imaged, has mostly been of secondary concern. The present work sets out to achieve the contrast of annular bright field STEM in ISTEM, producing the high contrast of light elements, for which this method is popular. It is shown from theoretical considerations that using an annular condenser aperture this aim can be realised. The optimal size of this aperture is found by simulative studies. It is then manufactured from platinum foil and installed in an image-aberration corrected microscope. ABF-like ISTEM images of strontium titanate in [100] projection are acquired. The pure oxygen columns are clearly resolved with significant contrast. The image pattern is indeed identical to what is achieved by ABF STEM. A close look at the image formation also shows that the dose needed for a given signal-to-noise ratio is at least a quarter smaller for ABF-like ISTEM compared to ABF STEM, assuming detectors of similar detective quantum efficiency.
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Affiliation(s)
- Florian F Krause
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany.
| | - Marco Schowalter
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Beeke Gerken
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Dennis Marquardt
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Tim Grieb
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Thorsten Mehrtens
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Christoph Mahr
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Andreas Rosenauer
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
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10
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Pu Y, He B, Niu Y, Liu X, Zhang B. Chemical Electron Microscopy (CEM) for Heterogeneous Catalysis at Nano: Recent Progress and Challenges. RESEARCH (WASHINGTON, D.C.) 2023; 6:0043. [PMID: 36930759 PMCID: PMC10013794 DOI: 10.34133/research.0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 12/18/2022] [Indexed: 01/12/2023]
Abstract
Chemical electron microscopy (CEM), a toolbox that comprises imaging and spectroscopy techniques, provides dynamic morphological, structural, chemical, and electronic information about an object in chemical environment under conditions of observable performance. CEM has experienced a revolutionary improvement in the past years and is becoming an effective characterization method for revealing the mechanism of chemical reactions, such as catalysis. Here, we mainly address the concept of CEM for heterogeneous catalysis in the gas phase and what CEM could uniquely contribute to catalysis, and illustrate what we can know better with CEM and the challenges and future development of CEM.
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Affiliation(s)
- Yinghui Pu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.,School of Materials Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang 110016, China
| | - Bowen He
- School of Chemistry and Chemical Engineering, In-situ Center for Physical Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yiming Niu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.,School of Materials Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang 110016, China
| | - Xi Liu
- School of Chemistry and Chemical Engineering, In-situ Center for Physical Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bingsen Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.,School of Materials Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang 110016, China
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11
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Susi T. Identifying and manipulating single atoms with scanning transmission electron microscopy. Chem Commun (Camb) 2022; 58:12274-12285. [PMID: 36260089 PMCID: PMC9632407 DOI: 10.1039/d2cc04807h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/28/2022] [Indexed: 08/25/2023]
Abstract
The manipulation of individual atoms has developed from visionary speculation into an established experimental science. Using focused electron irradiation in a scanning transmission electron microscope instead of a physical tip in a scanning probe microscope confers several benefits, including thermal stability of the manipulated structures, the ability to reach into bulk crystals, and the chemical identification of single atoms. However, energetic electron irradiation also presents unique challenges, with an inevitable possibility of irradiation damage. Understanding the underlying mechanisms will undoubtedly continue to play an important role to guide experiments. Great progress has been made in several materials including graphene, carbon nanotubes, and crystalline silicon in the eight years since the discovery of electron-beam manipulation, but the important challenges that remain will determine how far we can expect to progress in the near future.
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Affiliation(s)
- Toma Susi
- University of Vienna, Faculty of Physics, Boltzmanngasse 5, 1090 Vienna, Austria.
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12
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Dynamic hetero-metallic bondings visualized by sequential atom imaging. Nat Commun 2022; 13:2968. [PMID: 35624108 PMCID: PMC9142510 DOI: 10.1038/s41467-022-30533-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 04/28/2022] [Indexed: 11/16/2022] Open
Abstract
Traditionally, chemistry has been developed to obtain thermodynamically stable and isolable compounds such as molecules and solids by chemical reactions. However, recent developments in computational chemistry have placed increased importance on studying the dynamic assembly and disassembly of atoms and molecules formed in situ. This study directly visualizes the formation and dissociation dynamics of labile dimers and trimers at atomic resolution with elemental identification. The video recordings of many homo- and hetero-metallic dimers are carried out by combining scanning transmission electron microscopy (STEM) with elemental identification based on the Z-contrast principle. Even short-lived molecules with low probability of existence such as AuAg, AgCu, and AuAgCu are directly visualized as a result of identifying moving atoms at low electron doses. The dynamic assembly and disassembly of atoms and molecules is challenging to characterize in real time, with atomic resolution and elemental identification. Here, the authors report direct observation of more than twenty homo and hetero-metallic compounds, including labile Ag-Cu dimers and Au-Ag-Cu trimers.
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13
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Nan P, Liang Z, Zhang Y, Liu Y, Song D, Ge B. Fast determination of sample thickness through scanning moiré fringes in scanning transmission electron microscopy. Micron 2022; 155:103230. [DOI: 10.1016/j.micron.2022.103230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 11/25/2022]
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14
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de la Mata M, Molina SI. STEM Tools for Semiconductor Characterization: Beyond High-Resolution Imaging. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:337. [PMID: 35159686 PMCID: PMC8840450 DOI: 10.3390/nano12030337] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/13/2022] [Accepted: 01/18/2022] [Indexed: 12/10/2022]
Abstract
The smart engineering of novel semiconductor devices relies on the development of optimized functional materials suitable for the design of improved systems with advanced capabilities aside from better efficiencies. Thereby, the characterization of these materials at the highest level attainable is crucial for leading a proper understanding of their working principle. Due to the striking effect of atomic features on the behavior of semiconductor quantum- and nanostructures, scanning transmission electron microscopy (STEM) tools have been broadly employed for their characterization. Indeed, STEM provides a manifold characterization tool achieving insights on, not only the atomic structure and chemical composition of the analyzed materials, but also probing internal electric fields, plasmonic oscillations, light emission, band gap determination, electric field measurements, and many other properties. The emergence of new detectors and novel instrumental designs allowing the simultaneous collection of several signals render the perfect playground for the development of highly customized experiments specifically designed for the required analyses. This paper presents some of the most useful STEM techniques and several strategies and methodologies applied to address the specific analysis on semiconductors. STEM imaging, spectroscopies, 4D-STEM (in particular DPC), and in situ STEM are summarized, showing their potential use for the characterization of semiconductor nanostructured materials through recent reported studies.
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Affiliation(s)
- María de la Mata
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorganica, IMEYMAT, Universidad de Cádiz, 11510 Puerto Real, Spain;
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15
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Zou YC, Mogg L, Clark N, Bacaksiz C, Milovanovic S, Sreepal V, Hao GP, Wang YC, Hopkinson DG, Gorbachev R, Shaw S, Novoselov KS, Raveendran-Nair R, Peeters FM, Lozada-Hidalgo M, Haigh SJ. Ion exchange in atomically thin clays and micas. NATURE MATERIALS 2021; 20:1677-1682. [PMID: 34446864 DOI: 10.1038/s41563-021-01072-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
The physical properties of clays and micas can be controlled by exchanging ions in the crystal lattice. Atomically thin materials can have superior properties in a range of membrane applications, yet the ion-exchange process itself remains largely unexplored in few-layer crystals. Here we use atomic-resolution scanning transmission electron microscopy to study the dynamics of ion exchange and reveal individual ion binding sites in atomically thin and artificially restacked clays and micas. We find that the ion diffusion coefficient for the interlayer space of atomically thin samples is up to 104 times larger than in bulk crystals and approaches its value in free water. Samples where no bulk exchange is expected display fast exchange at restacked interfaces, where the exchanged ions arrange in islands with dimensions controlled by the moiré superlattice dimensions. We attribute the fast ion diffusion to enhanced interlayer expandability resulting from weaker interlayer binding forces in both atomically thin and restacked materials. This work provides atomic scale insights into ion diffusion in highly confined spaces and suggests strategies to design exfoliated clay membranes with enhanced performance.
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Affiliation(s)
- Yi-Chao Zou
- School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou, P. R. China
- Department of Materials, The University of Manchester, Manchester, UK
| | - Lucas Mogg
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
- Department of Engineering, University of Cambridge, Cambridge, UK
| | - Nick Clark
- Department of Materials, The University of Manchester, Manchester, UK
- National Graphene Institute, The University of Manchester, Manchester, UK
| | - Cihan Bacaksiz
- Departement Fysica, Universiteit Antwerpen, Antwerp, Belgium
- Bremen Center for Computational Material Science (BCCMS), Bremen, Germany
- Shenzhen JL Computational Science and Applied Research Institute, Shenzhen, China
| | | | - Vishnu Sreepal
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | - Guang-Ping Hao
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Yi-Chi Wang
- Department of Materials, The University of Manchester, Manchester, UK
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, P. R. China
| | - David G Hopkinson
- Department of Materials, The University of Manchester, Manchester, UK
- National Graphene Institute, The University of Manchester, Manchester, UK
| | - Roman Gorbachev
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Science, The University of Manchester, Manchester, UK
| | - Kostya S Novoselov
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK
| | - Rahul Raveendran-Nair
- National Graphene Institute, The University of Manchester, Manchester, UK
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | | | - Marcelo Lozada-Hidalgo
- National Graphene Institute, The University of Manchester, Manchester, UK.
- Department of Physics and Astronomy, The University of Manchester, Manchester, UK.
| | - Sarah J Haigh
- Department of Materials, The University of Manchester, Manchester, UK.
- National Graphene Institute, The University of Manchester, Manchester, UK.
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16
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Tsurusawa H, Nakanishi N, Kawano K, Chen Y, Dutka M, Van Leer B, Mizoguchi T. Robotic fabrication of high-quality lamellae for aberration-corrected transmission electron microscopy. Sci Rep 2021; 11:21599. [PMID: 34732755 PMCID: PMC8566590 DOI: 10.1038/s41598-021-00595-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 10/14/2021] [Indexed: 11/09/2022] Open
Abstract
Aberration-corrected scanning transmission electron microscopy (STEM) is widely used for atomic-level imaging of materials but severely requires damage-free and thin samples (lamellae). So far, the preparation of the high-quality lamella from a bulk largely depends on manual processes by a skilled operator. This limits the throughput and repeatability of aberration-corrected STEM experiments. Here, inspired by the recent successes of "robot scientists", we demonstrate robotic fabrication of high-quality lamellae by focused-ion-beam (FIB) with automation software. First, we show that the robotic FIB can prepare lamellae with a high success rate, where the FIB system automatically controls rough-milling, lift-out, and final-thinning processes. Then, we systematically optimized the FIB parameters of the final-thinning process for single crystal Si. The optimized Si lamellae were evaluated by aberration-corrected STEM, showing atomic-level images with 55 pm resolution and quantitative repeatability of the spatial resolution and lamella thickness. We also demonstrate robotic fabrication of high-quality lamellae of SrTiO3 and sapphire, suggesting that the robotic FIB system may be applicable for a wide range of materials. The throughput of the robotic fabrication was typically an hour per lamella. Our robotic FIB will pave the way for the operator-free, high-throughput, and repeatable fabrication of the high-quality lamellae for aberration-corrected STEM.
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Affiliation(s)
- Hideyo Tsurusawa
- Thermo Fisher Scientific, FEI Japan Ltd., 4-12-2, Higashi-Shinagawa, Shinagawa-ku, Tokyo, 140-0002, Japan.
| | - Nobuto Nakanishi
- Thermo Fisher Scientific, FEI Japan Ltd., 4-12-2, Higashi-Shinagawa, Shinagawa-ku, Tokyo, 140-0002, Japan
| | - Kayoko Kawano
- Thermo Fisher Scientific, FEI Japan Ltd., 4-12-2, Higashi-Shinagawa, Shinagawa-ku, Tokyo, 140-0002, Japan
| | - Yiqiang Chen
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, The Netherlands
| | - Mikhail Dutka
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, The Netherlands
| | - Brandon Van Leer
- Thermo Fisher Scientific, 5350 NE Dawson Creek Drive, Hillsboro, OR, 97124, USA
| | - Teruyasu Mizoguchi
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
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17
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Ribet SM, Murthy AA, Roth EW, Dos Reis R, Dravid VP. Making the Most of your Electrons: Challenges and Opportunities in Characterizing Hybrid Interfaces with STEM. MATERIALS TODAY (KIDLINGTON, ENGLAND) 2021; 50:100-115. [PMID: 35241968 PMCID: PMC8887695 DOI: 10.1016/j.mattod.2021.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Inspired by the unique architectures composed of hard and soft materials in natural and biological systems, synthetic hybrid structures and associated soft-hard interfaces have recently evoked significant interest. Soft matter is typically dominated by fluctuations even at room temperature, while hard matter (which often serves as the substrate or anchor for the soft component) is governed by rigid mechanical behavior. This dichotomy offers considerable opportunities to leverage the disparate properties offered by these components across a wide spectrum spanning from basic science to engineering insights with significant technological overtones. Such hybrid structures, which include polymer nanocomposites, DNA functionalized nanoparticle superlattices and metal organic frameworks to name a few, have delivered promising insights into the areas of catalysis, environmental remediation, optoelectronics, medicine, and beyond. The interfacial structure between these hard and soft phases exists across a variety of length scales and often strongly influence the functionality of hybrid systems. While scanning/transmission electron microscopy (S/TEM) has proven to be a valuable tool for acquiring intricate molecular and nanoscale details of these interfaces, the unusual nature of hybrid composites presents a suite of challenges that make assessing or establishing the classical structure-property relationships especially difficult. These include challenges associated with preparing electron-transparent samples and obtaining sufficient contrast to resolve the interface between dissimilar materials given the dose sensitivity of soft materials. We discuss each of these challenges and supplement a review of recent developments in the field with additional experimental investigations and simulations to present solutions for attaining a nano or atomic-level understanding of these interfaces. These solutions present a host of opportunities for investigating and understanding the role interfaces play in this unique class of functional materials.
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Affiliation(s)
- Stephanie M Ribet
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
| | - Akshay A Murthy
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- International Institute of Nanotechnology, Northwestern University, Evanston, IL
| | - Eric W Roth
- The NUANCE Center, Northwestern University, Evanston, IL
| | - Roberto Dos Reis
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- The NUANCE Center, Northwestern University, Evanston, IL
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL
- International Institute of Nanotechnology, Northwestern University, Evanston, IL
- The NUANCE Center, Northwestern University, Evanston, IL
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18
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19
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Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden-Popper phases. Nat Commun 2021; 12:5527. [PMID: 34545102 PMCID: PMC8452630 DOI: 10.1038/s41467-021-25889-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 09/03/2021] [Indexed: 11/08/2022] Open
Abstract
As the physical properties of ABX3 perovskite-based oxides strongly depend on the geometry of oxygen octahedra containing transition-metal cations, precise identification of the distortion, tilt, and rotation of the octahedra is an essential step toward understanding the structure-property correlation. Here we discover an important electrostatic origin responsible for remarkable Jahn-Teller-type tetragonal distortion of oxygen octahedra during atomic-level direct observation of two-dimensional [AX] interleaved shear faults in five different perovskite-type materials, SrTiO3, BaCeO3, LaCoO3, LaNiO3, and CsPbBr3. When the [AX] sublayer has a net charge, for example [LaO]+ in LaCoO3 and LaNiO3, substantial tetragonal elongation of oxygen octahedra at the fault plane is observed and this screens the strong repulsion between the consecutive [LaO]+ layers. Moreover, our findings on the distortion induced by local charge are identified to be a general structural feature in lanthanide-based An + 1BnX3n + 1-type Ruddlesden-Popper (RP) oxides with charged [LnO]+ (Ln = La, Pr, Nd, Eu, and Gd) sublayers, among more than 80 RP oxides and halides with high symmetry. The present study thus demonstrates that the local uneven electrostatics is a crucial factor significantly affecting the crystal structure of complex oxides.
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20
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Liu JJ. Advances and Applications of Atomic-Resolution Scanning Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:1-53. [PMID: 34414878 DOI: 10.1017/s1431927621012125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Although scanning transmission electron microscopy (STEM) images of individual heavy atoms were reported 50 years ago, the applications of atomic-resolution STEM imaging became wide spread only after the practical realization of aberration correctors on field-emission STEM/TEM instruments to form sub-Ångstrom electron probes. The innovative designs and advances of electron optical systems, the fundamental understanding of electron–specimen interaction processes, and the advances in detector technology all played a major role in achieving the goal of atomic-resolution STEM imaging of practical materials. It is clear that tremendous advances in computer technology and electronics, image acquisition and processing algorithms, image simulations, and precision machining synergistically made atomic-resolution STEM imaging routinely accessible. It is anticipated that further hardware/software development is needed to achieve three-dimensional atomic-resolution STEM imaging with single-atom chemical sensitivity, even for electron-beam-sensitive materials. Artificial intelligence, machine learning, and big-data science are expected to significantly enhance the impact of STEM and associated techniques on many research fields such as materials science and engineering, quantum and nanoscale science, physics and chemistry, and biology and medicine. This review focuses on advances of STEM imaging from the invention of the field-emission electron gun to the realization of aberration-corrected and monochromated atomic-resolution STEM and its broad applications.
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Affiliation(s)
- Jingyue Jimmy Liu
- Department of Physics, Arizona State University, Tempe, AZ85287, USA
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21
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Atomic-scale unveiling of multiphase evolution during hydrated Zn-ion insertion in vanadium oxide. Nat Commun 2021; 12:4599. [PMID: 34326335 PMCID: PMC8322084 DOI: 10.1038/s41467-021-24700-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 07/05/2021] [Indexed: 12/21/2022] Open
Abstract
An initial crystalline phase can transform into another phases as cations are electrochemically inserted into its lattice. Precise identification of phase evolution at an atomic level during transformation is thus the very first step to comprehensively understand the cation insertion behavior and subsequently achieve much higher storage capacity in rechargeable cells, although it is sometimes challenging. By intensively using atomic-column-resolved scanning transmission electron microscopy, we directly visualize the simultaneous intercalation of both H2O and Zn during discharge of Zn ions into a V2O5 cathode with an aqueous electrolyte. In particular, when further Zn insertion proceeds, multiple intermediate phases, which are not identified by a macroscopic powder diffraction method, are clearly imaged at an atomic scale, showing structurally topotactic correlation between the phases. The findings in this work suggest that smooth multiphase evolution with a low transition barrier is significantly related to the high capacity of oxide cathodes for aqueous rechargeable cells, where the crystal structure of cathode materials after discharge differs from the initial crystalline state in general. The detailed understanding of the structural variations during cycling in cathodes for Zn-ion aqueous rechargeable batteries is still limited. Here, the authors utilize atomic-column-resolved scanning transmission electron microscopy to elucidate multiphase evolution during hydrated Zn-Ion insertion in vanadium oxide.
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22
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Accuracy and precision of position determination in ISTEM imaging of BaTiO 3. Ultramicroscopy 2021; 227:113325. [PMID: 34045084 DOI: 10.1016/j.ultramic.2021.113325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 11/21/2022]
Abstract
In this paper we study the effect of lens aberrations (spherical aberration and astigmatism), beam tilt, contamination and shot noise on the accuracy and precision of position determination in imaging scanning transmission electron microscopy (ISTEM) on the example of BaTiO3. ISTEM images are simulated as a function of sample thickness and defocus starting from a nearly perfect microscope setting. A defocus range was identified, in which atom column positions were reliably visible and could be decently measured. By averaging over this defocus and thickness range a figure of merit was defined and used to study the influence of above mentioned disturbing effects as a function of their strength. It turned out that column positions might become inaccurate, but distances are measured accurately. These were used to obtain recommendations for the experimental setup to measure the atomic arrangement that induces ferroelectric switching of BaTiO3.
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23
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Tieu P, Yan X, Xu M, Christopher P, Pan X. Directly Probing the Local Coordination, Charge State, and Stability of Single Atom Catalysts by Advanced Electron Microscopy: A Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006482. [PMID: 33624398 DOI: 10.1002/smll.202006482] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/18/2020] [Indexed: 06/12/2023]
Abstract
The drive for atom efficient catalysts with carefully controlled properties has motivated the development of single atom catalysts (SACs), aided by a variety of synthetic methods, characterization techniques, and computational modeling. The distinct capabilities of SACs for oxidation, hydrogenation, and electrocatalytic reactions have led to the optimization of activity and selectivity through composition variation. However, characterization methods such as infrared and X-ray spectroscopy are incapable of direct observations at atomic scale. Advances in transmission electron microscopy (TEM) including aberration correction, monochromators, environmental TEM, and micro-electro-mechanical system based in situ holders have improved catalysis study, allowing researchers to peer into regimes previously unavailable, observing critical structural and chemical information at atomic scale. This review presents recent development and applications of TEM techniques to garner information about the location, bonding characteristics, homogeneity, and stability of SACs. Aberration corrected TEM imaging routinely achieves sub-Ångstrom resolution to reveal the atomic structure of materials. TEM spectroscopy provides complementary information about local composition, chemical bonding, electronic properties, and atomic/molecular vibration with superior spatial resolution. In situ/operando TEM directly observe the evolution of SACs under reaction conditions. This review concludes with remarks on the challenges and opportunities for further development of TEM to study SACs.
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Affiliation(s)
- Peter Tieu
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Xingxu Yan
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
| | - Mingjie Xu
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
- Irvine Materials Research Institute (IMRI), University of California, Irvine, CA, 92697, USA
| | - Phillip Christopher
- Department of Chemical Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Xiaoqing Pan
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
- Irvine Materials Research Institute (IMRI), University of California, Irvine, CA, 92697, USA
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
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24
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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: 9] [Impact Index Per Article: 3.0] [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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25
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Bak J, Heo Y, Yun TG, Chung SY. Atomic-Level Manipulations in Oxides and Alloys for Electrocatalysis of Oxygen Evolution and Reduction. ACS NANO 2020; 14:14323-14354. [PMID: 33151068 DOI: 10.1021/acsnano.0c06411] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As chemical reactions and charge-transfer simultaneously occur on the catalyst surface during electrocatalysis, numerous studies have been carried out to attain an in-depth understanding on the correlation among the surface structure and composition, the electrical transport, and the overall catalytic activity. Compared with other catalysis reactions, a relatively larger activation barrier for oxygen evolution/reduction reactions (OER/ORR), where multiple electron transfers are involved, is noted. Many works over the past decade thus have been focused on the atomic-scale control of the surface structure and the precise identification of surface composition change in catalyst materials to achieve better conversion efficiency. In particular, recent advances in various analytical tools have enabled noteworthy findings of unexpected catalytic features at atomic resolution, providing significant insights toward reducing the activation barriers and subsequently improving the catalytic performance. In addition to summarizing important surface issues, including lattice defects, related to the OER and ORR in this Review, we present the current status and discuss future perspectives of oxide- and alloy-based catalysts in terms of atomic-scale observation and manipulation.
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Affiliation(s)
- Jumi Bak
- Department of Materials Science and Engineering and KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Yoon Heo
- Department of Materials Science and Engineering and KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Tae Gyu Yun
- Department of Materials Science and Engineering and KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Sung-Yoon Chung
- Department of Materials Science and Engineering and KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
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26
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Lin B, Wu X, Xie L, Kang Y, Du H, Kang F, Li J, Gan L. Atomic Imaging of Subsurface Interstitial Hydrogen and Insights into Surface Reactivity of Palladium Hydrides. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Bingqing Lin
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Xi Wu
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Lin Xie
- Department of Physics Southern University of Science and Technology Shenzhen 518055 China
| | - Yongqiang Kang
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Hongda Du
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Feiyu Kang
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Jia Li
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
| | - Lin Gan
- Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
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27
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Lin B, Wu X, Xie L, Kang Y, Du H, Kang F, Li J, Gan L. Atomic Imaging of Subsurface Interstitial Hydrogen and Insights into Surface Reactivity of Palladium Hydrides. Angew Chem Int Ed Engl 2020; 59:20348-20352. [PMID: 32621778 DOI: 10.1002/anie.202006562] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/15/2020] [Indexed: 11/07/2022]
Abstract
Resolving interstitial hydrogen atoms at the surfaces and interfaces is crucial for understanding the mechanical and physicochemical properties of metal hydrides. Although palladium (Pd) hydrides hold important applications in hydrogen storage and electrocatalysis, the atomic position of interstitial hydrogen at Pd hydride near surfaces still remains undetermined. We report the first direct imaging of subsurface hydrogen atoms absorbed in Pd nanoparticles by using differentiated and integrated differential phase contrast within an aberration-corrected scanning transmission electron microscope. In contrast to the well-established octahedral interstitial sites for hydrogen in the bulk, subsurface hydrogen atoms are directly identified to occupy the tetrahedral interstices. DFT calculations show that the amount and the occupation type of subsurface hydrogen atoms play an indispensable role in fine-tuning the electronic structure and associated chemical reactivity of the Pd surface.
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Affiliation(s)
- Bingqing Lin
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Xi Wu
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Lin Xie
- Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yongqiang Kang
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Hongda Du
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Feiyu Kang
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Jia Li
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
| | - Lin Gan
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China
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Kim JR, Jang J, Go KJ, Park SY, Roh CJ, Bonini J, Kim J, Lee HG, Rabe KM, Lee JS, Choi SY, Noh TW, Lee D. Stabilizing hidden room-temperature ferroelectricity via a metastable atomic distortion pattern. Nat Commun 2020; 11:4944. [PMID: 33009380 PMCID: PMC7532175 DOI: 10.1038/s41467-020-18741-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 09/10/2020] [Indexed: 11/09/2022] Open
Abstract
Nonequilibrium atomic structures can host exotic and technologically relevant properties in otherwise conventional materials. Oxygen octahedral rotation forms a fundamental atomic distortion in perovskite oxides, but only a few patterns are predominantly present at equilibrium. This has restricted the range of possible properties and functions of perovskite oxides, necessitating the utilization of nonequilibrium patterns of octahedral rotation. Here, we report that a designed metastable pattern of octahedral rotation leads to robust room-temperature ferroelectricity in CaTiO3, which is otherwise nonpolar down to 0 K. Guided by density-functional theory, we selectively stabilize the metastable pattern, distinct from the equilibrium pattern and cooperative with ferroelectricity, in heteroepitaxial films of CaTiO3. Atomic-scale imaging combined with deep neural network analysis confirms a close correlation between the metastable pattern and ferroelectricity. This work reveals a hidden but functional pattern of oxygen octahedral rotation and opens avenues for designing multifunctional materials.
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Affiliation(s)
- Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Jinhyuk Jang
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea
| | - Kyoung-June Go
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea
| | - Se Young Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea.
- Department of Physics, Soongsil University, Seoul, 07027, Korea.
| | - Chang Jae Roh
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - John Bonini
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854-8019, USA
| | - Jinkwon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Han Gyeol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Karin M Rabe
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854-8019, USA
| | - Jong Seok Lee
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea.
| | - Daesu Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
- Asia Pacific Center for Theoretical Physics, Pohang, 37673, Korea.
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29
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Nguyen T, Bui V, Thai A, Lam V, Raub CB, Chang LC, Nehmetallah G. Virtual organelle self-coding for fluorescence imaging via adversarial learning. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200126RR. [PMID: 32996300 PMCID: PMC7522603 DOI: 10.1117/1.jbo.25.9.096009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
SIGNIFICANCE Our study introduces an application of deep learning to virtually generate fluorescence images to reduce the burdens of cost and time from considerable effort in sample preparation related to chemical fixation and staining. AIM The objective of our work was to determine how successfully deep learning methods perform on fluorescence prediction that depends on structural and/or a functional relationship between input labels and output labels. APPROACH We present a virtual-fluorescence-staining method based on deep neural networks (VirFluoNet) to transform co-registered images of cells into subcellular compartment-specific molecular fluorescence labels in the same field-of-view. An algorithm based on conditional generative adversarial networks was developed and trained on microscopy datasets from breast-cancer and bone-osteosarcoma cell lines: MDA-MB-231 and U2OS, respectively. Several established performance metrics-the mean absolute error (MAE), peak-signal-to-noise ratio (PSNR), and structural-similarity-index (SSIM)-as well as a novel performance metric, the tolerance level, were measured and compared for the same algorithm and input data. RESULTS For the MDA-MB-231 cells, F-actin signal performed the fluorescent antibody staining of vinculin prediction better than phase-contrast as an input. For the U2OS cells, satisfactory metrics of performance were archieved in comparison with ground truth. MAE is <0.005, 0.017, 0.012; PSNR is >40 / 34 / 33 dB; and SSIM is >0.925 / 0.926 / 0.925 for 4',6-diamidino-2-phenylindole/hoechst, endoplasmic reticulum, and mitochondria prediction, respectively, from channels of nucleoli and cytoplasmic RNA, Golgi plasma membrane, and F-actin. CONCLUSIONS These findings contribute to the understanding of the utility and limitations of deep learning image-regression to predict fluorescence microscopy datasets of biological cells. We infer that predicted image labels must have either a structural and/or a functional relationship to input labels. Furthermore, the approach introduced here holds promise for modeling the internal spatial relationships between organelles and biomolecules within living cells, leading to detection and quantification of alterations from a standard training dataset.
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Affiliation(s)
- Thanh Nguyen
- The Catholic University of America, Electrical Engineering and Computer Science Department, Washington, DC, United States
| | - Vy Bui
- The Catholic University of America, Electrical Engineering and Computer Science Department, Washington, DC, United States
| | - Anh Thai
- The Catholic University of America, Electrical Engineering and Computer Science Department, Washington, DC, United States
| | - Van Lam
- The Catholic University of America, Biomedical Engineering Department, Washington, DC, United States
| | - Christopher B. Raub
- The Catholic University of America, Biomedical Engineering Department, Washington, DC, United States
| | - Lin-Ching Chang
- The Catholic University of America, Electrical Engineering and Computer Science Department, Washington, DC, United States
| | - George Nehmetallah
- The Catholic University of America, Electrical Engineering and Computer Science Department, Washington, DC, United States
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Brown HG, Ciston J. Atomic Resolution Imaging of Light Elements in a Crystalline Environment using Dynamic Hollow-Cone Illumination Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2020; 26:623-629. [PMID: 32519630 DOI: 10.1017/s1431927620001658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Multiple electron scattering and the nonintuitive nature of image formation with coherent radiation complicate the interpretation of conventional transmission electron microscopy images. Precession of the illuminating beam in transmission electron microscopy (TEM) can lead to more robust and interpretable images with some penalty to image contrast, a technique known as dynamic hollow-cone illumination TEM. We demonstrate direct and robust imaging of light and heavy atoms in a crystalline environment with this technique. This method is similar to the annular bright-field technique in scanning transmission electron microscopy, via the principle of reciprocity. Dynamic hollow-cone illumination TEM is challenging in practice due to sensitivity to the misalignment of the precession axis, microscope objective aperture, and crystal zone axis.
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Affiliation(s)
- Hamish G Brown
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jim Ciston
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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31
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Li L, Self EC, Darbar D, Zou L, Bhattacharya I, Wang D, Nanda J, Wang C. Hidden Subsurface Reconstruction and Its Atomic Origins in Layered Oxide Cathodes. NANO LETTERS 2020; 20:2756-2762. [PMID: 32119550 DOI: 10.1021/acs.nanolett.0c00380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Structural transformations near surfaces of solid-state materials underpin functional mechanisms of a broad range of applications including catalysis, memory, and energy storage. It has been a long-standing notion that the outermost free surfaces, accompanied by broken translational symmetry and altered atomic configurations, are usually the birthplace for structural transformations. Here, in a layered oxide cathode for Li-ion batteries, we for the first time observe the incipient state of the well-documented layered-to-spinel-like structural transformation, which is surprisingly initiated from the subsurface layer, rather than the very surface. Coupling atomic level scanning transmission electron microscopy imaging with electron energy loss spectroscopy, we discover that the reconstructed subsurfaces, featuring a mix of discrete patches of layered and spinel-like structures, are associated with selective atomic species partition and consequent nanoscale nonuniform composition gradient distribution at the subsurface. Our findings provide fundamental insights on atomic-scale mechanisms of structural transformation in layered cathodes.
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Affiliation(s)
- Linze Li
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States
| | - Ethan C Self
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Devendrasinh Darbar
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
- Department of Electrical and Computer Engineering, Tennessee Technological University, Cookeville, Tennessee 38505, United States
| | - Lianfeng Zou
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States
| | - Indranil Bhattacharya
- Department of Electrical and Computer Engineering, Tennessee Technological University, Cookeville, Tennessee 38505, United States
| | - Donghai Wang
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jagjit Nanda
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Chongmin Wang
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States
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32
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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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33
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Kim D, Jung HJ, Park IJ, Larson BW, Dunfield SP, Xiao C, Kim J, Tong J, Boonmongkolras P, Ji SG, Zhang F, Pae SR, Kim M, Kang SB, Dravid V, Berry JJ, Kim JY, Zhu K, Kim DH, Shin B. Efficient, stable silicon tandem cells enabled by anion-engineered wide-bandgap perovskites. Science 2020; 368:155-160. [DOI: 10.1126/science.aba3433] [Citation(s) in RCA: 259] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/12/2020] [Indexed: 01/18/2023]
Abstract
Maximizing the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells that can exceed the Shockley-Queisser single-cell limit requires a high-performing, stable perovskite top cell with a wide bandgap. We developed a stable perovskite solar cell with a bandgap of ~1.7 electron volts that retained more than 80% of its initial PCE of 20.7% after 1000 hours of continuous illumination. Anion engineering of phenethylammonium-based two-dimensional (2D) additives was critical for controlling the structural and electrical properties of the 2D passivation layers based on a lead iodide framework. The high PCE of 26.7% of a monolithic two-terminal wide-bandgap perovskite/silicon tandem solar cell was made possible by the ideal combination of spectral responses of the top and bottom cells.
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Affiliation(s)
- Daehan Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hee Joon Jung
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Ik Jae Park
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | | | - Sean P. Dunfield
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Chuanxiao Xiao
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Jekyung Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Jinhui Tong
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Passarut Boonmongkolras
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Su Geun Ji
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Fei Zhang
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Seong Ryul Pae
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Minkyu Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Seok Beom Kang
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Vinayak Dravid
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Joseph J. Berry
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jin Young Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Kai Zhu
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Dong Hoe Kim
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Byungha Shin
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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Mundet B, Hartman ST, Guzman R, Idrobo JC, Obradors X, Puig T, Mishra R, Gázquez J. Local strain-driven migration of oxygen vacancies to apical sites in YBa 2Cu 3O 7-x. NANOSCALE 2020; 12:5922-5931. [PMID: 32108218 DOI: 10.1039/d0nr00666a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
It is well known that in the high-temperature superconductor YBa2Cu3O7-x (YBCO), oxygen vacancies (VO) control the carrier concentration, its critical current density and transition temperature. In this work, it is revealed that VO also allows the accommodation of local strain fields caused by large-scale defects within the crystal. We show that the nanoscale strain associated with Y2Ba4Cu8O16 (Y124) intergrowths-that are common defects in YBCO-strongly affect the venue and concentration of VO. Local probe measurements in conjunction with density-functional-theory calculations indicate a strain-driven reordering of VO from the commonly observed CuO chains towards the bridging apical sites located in the BaO plane and bind directly to the superconducting CuO2 planes. Our findings have strong implications on the physical properties of the YBCO, as the presence of apical VO alters the transfer of carriers to the CuO2 planes, confirmed by changes in the Cu and O core-loss edge probed using electron energy loss spectroscopy, and creates structural changes that affect the Cu-O bonds in the superconducting planes. In addition, the revelation of apical VO also has implications on modulating critical current densities and enhancing vortex pinning.
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Affiliation(s)
- Bernat Mundet
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - Steven T Hartman
- Institute of Materials Science and Engineering, Washington University in St Louis, St Louis, Missouri 63130, USA
| | - Roger Guzman
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - Juan C Idrobo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Xavier Obradors
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - Teresa Puig
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - Rohan Mishra
- Department of Mechanical Engineering and Materials Science, Washington University in St Louis, St Louis, Missouri 63130, USA.
| | - Jaume Gázquez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, 08193 Barcelona, Spain.
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Luan J, He X, Jiang Z, Kong Y, Wang S, Liu C. Speckle-illuminated Fourier ptychography: analysis of diffuser roughness and reconstruction aperture on imaging performance. APPLIED OPTICS 2020; 59:2201-2210. [PMID: 32225747 DOI: 10.1364/ao.385261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/05/2020] [Indexed: 06/10/2023]
Abstract
With a fundamentally modified structural illumination algorithm, the recently proposed speckle-illuminated Fourier ptychography can be a promising superresolution imaging technique with a large field of view. However, its imaging performance, including image resolution and signal-to-noise ratio, has been discussed less, limiting its further applications. Thus, an in-depth study of this new imaging technique is highly required. In this paper, with theoretical analysis, numerical simulations, and experiments, the influence of both diffuser roughness in the experimental setup and numerical aperture size in iterative reconstruction on the imaging performance of speckle-illuminated Fourier ptychography was studied in detail, and the result explained why a rougher diffuser and larger reconstruction aperture can generate a higher-resolution image with more noise and showed how to get optimized diffuser roughness and reconstruction aperture size by considering the trade-off between imaging resolution and signal-to-noise ratio. This work may be a good reference for high-quality imaging using speckle-illuminated Fourier ptychography.
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36
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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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de Graaf S, Momand J, Mitterbauer C, Lazar S, Kooi BJ. Resolving hydrogen atoms at metal-metal hydride interfaces. SCIENCE ADVANCES 2020; 6:eaay4312. [PMID: 32064349 PMCID: PMC6994207 DOI: 10.1126/sciadv.aay4312] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/22/2019] [Indexed: 05/21/2023]
Abstract
Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also be detrimental to metals, causing embrittlement. Understanding fundamental behavior of hydrogen at the atomic scale is key to improve the properties of metal-metal hydride systems. However, currently, there is no robust technique capable of visualizing hydrogen atoms. Here, we demonstrate that hydrogen atoms can be imaged unprecedentedly with integrated differential phase contrast, a recently developed technique performed in a scanning transmission electron microscope. Images of the titanium-titanium monohydride interface reveal stability of the hydride phase, originating from the interplay between compressive stress and interfacial coherence. We also uncovered, 30 years after three models were proposed, which one describes the position of hydrogen atoms with respect to the interface. Our work enables previously unidentified research on hydrides and is extendable to all materials containing light and heavy elements, including oxides, nitrides, carbides, and borides.
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Affiliation(s)
- Sytze de Graaf
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
- Corresponding author. (S.d.G.); (B.J.K.)
| | - Jamo Momand
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
| | | | - Sorin Lazar
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, Netherlands
| | - Bart J. Kooi
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
- Corresponding author. (S.d.G.); (B.J.K.)
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38
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Zheng H, Cao F, Zhao L, Jiang R, Zhao P, Zhang Y, Wei Y, Meng S, Li K, Jia S, Li L, Wang J. Atomistic and dynamic structural characterizations in low-dimensional materials: recent applications of in situ transmission electron microscopy. Microscopy (Oxf) 2019; 68:423-433. [PMID: 31746339 DOI: 10.1093/jmicro/dfz038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/14/2019] [Accepted: 09/16/2019] [Indexed: 11/14/2022] Open
Abstract
In situ transmission electron microscopy has achieved remarkable advances for atomic-scale dynamic analysis in low-dimensional materials and become an indispensable tool in view of linking a material's microstructure to its properties and performance. Here, accompanied with some cutting-edge researches worldwide, we briefly review our recent progress in dynamic atomistic characterization of low-dimensional materials under external mechanical stress, thermal excitations and electrical field. The electron beam irradiation effects in metals and metal oxides are also discussed. We conclude by discussing the likely future developments in this area.
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Affiliation(s)
- He Zheng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Fan Cao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.,Hubei Key Lab of Ferro- and Piezo-electric Materials and Devices, Faculty of Physics & Electronic Sciences, Hubei University, Wuhan 430062, China
| | - Ligong Zhao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Renhui Jiang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Peili Zhao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Ying Zhang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Yanjie Wei
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Shuang Meng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Kaixuan Li
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Shuangfeng Jia
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Luying Li
- Center for Nanoscale Characterization and Devices, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jianbo Wang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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39
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Li L, Xie L, Pan X. Real-time studies of ferroelectric domain switching: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:126502. [PMID: 31185460 DOI: 10.1088/1361-6633/ab28de] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ferroelectric materials have been utilized in a broad range of electronic, optical, and electromechanical applications and hold the promise for the design of future high-density nonvolatile memories and multifunctional nano-devices. The applications of ferroelectric materials stem from the ability to switch polarized domains by applying an electric field, and therefore a fundamental understanding of the switching dynamics is critical for design of practical devices. In this review, we summarize the progress in the study of the microscopic process of ferroelectric domain switching using recently developed in situ transmission electron microscopy (TEM). We first briefly introduce the instrumentation, experimental procedures, imaging mechanisms, and analytical methods of the state-of-the-art in situ TEM techniques. The application of these techniques to studying a wide range of complex switching phenomena, including domain nucleation, domain wall motion, domain relaxation, domain-defect interaction, and the interplay between different types of domains, is demonstrated. The underlying physics of these dynamic processes are discussed.
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Affiliation(s)
- Linze Li
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697, United States of America
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40
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Li H, Lou F, Wang Y, Zhang Y, Zhang Q, Wu D, Li Z, Wang M, Huang T, Lyu Y, Guo J, Chen T, Wu Y, Arenholz E, Lu N, Wang N, He Q, Gu L, Zhu J, Nan C, Zhong X, Xiang H, Yu P. Electric Field-Controlled Multistep Proton Evolution in H x SrCoO 2.5 with Formation of H-H Dimer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901432. [PMID: 31637170 PMCID: PMC6794722 DOI: 10.1002/advs.201901432] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/16/2019] [Indexed: 05/30/2023]
Abstract
Ionic evolution-induced phase transformation can lead to wide ranges of novel material functionalities with promising applications. Here, using the gating voltage during ionic liquid gating as a tuning knob, the brownmillerite SrCoO2.5 is transformed into a series of protonated H x SrCoO2.5 phases with distinct hydrogen contents. The unexpected electron to charge-neutral doping crossover along with the increase of proton concentration from x = 1 to 2 suggests the formation of exotic charge neutral H-H dimers for higher proton concentration, which is directly visualized at the vacant tetrahedron by scanning transmission electron microscopy and then further supported by first principles calculations. Although the H-H dimers cause no change of the valency of Co2+ ions, they result in clear enhancement of electronic bandgap and suppression of magnetization through lattice expansion. These results not only reveal a hydrogen chemical state beyond anion and cation within the complex oxides, but also suggest an effective pathway to design functional materials through tunable ionic evolution.
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Affiliation(s)
- Hao‐Bo Li
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Feng Lou
- Key Laboratory of Computational Physical Sciences (Ministry of Education)State Key Laboratory of Surface Physics, and Department of PhysicsFudan UniversityShanghai200433China
| | - Yujia Wang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Yang Zhang
- National Center for Electron Microscopy in BeijingKey Laboratory of Advanced Materials (MOE)Beijing100084China
- State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing100190China
- Collaborative Innovation Center of Quantum MatterBeijing100084China
| | - Dong Wu
- Collaborative Innovation Center of Quantum MatterBeijing100084China
- International Center for Quantum MaterialsSchool of PhysicsPeking UniversityBeijing100871China
| | - Zhuolu Li
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Meng Wang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
- Collaborative Innovation Center of Quantum MatterBeijing100084China
| | - Tongtong Huang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Yingjie Lyu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Jingwen Guo
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Tianzhe Chen
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Yang Wu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
- Department of Mechanical EngineeringTsinghua UniversityBeijing100084China
| | - Elke Arenholz
- Advanced Light SourceLawrence Berkeley National LaboratoryBerkeley94720CAUSA
| | - Nianpeng Lu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
| | - Nanlin Wang
- International Center for Quantum MaterialsSchool of PhysicsPeking UniversityBeijing100871China
| | - Qing He
- Department of PhysicsDurham UniversityDurhamDH13LEUK
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing100190China
- Collaborative Innovation Center of Quantum MatterBeijing100084China
- School of Physical SciencesUniversity of Chinese Academy of SciencesBeijing100049China
| | - Jing Zhu
- National Center for Electron Microscopy in BeijingKey Laboratory of Advanced Materials (MOE)Beijing100084China
- State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China
| | - Ce‐Wen Nan
- State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China
| | - Xiaoyan Zhong
- National Center for Electron Microscopy in BeijingKey Laboratory of Advanced Materials (MOE)Beijing100084China
- State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education)State Key Laboratory of Surface Physics, and Department of PhysicsFudan UniversityShanghai200433China
- Collaborative Innovation Center of Advanced MicrostructuresNanjing210093China
| | - Pu Yu
- State Key Laboratory of Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBeijing100084China
- Collaborative Innovation Center of Quantum MatterBeijing100084China
- RIKEN Center for Emergent Matter Science (CEMS)Saitama351‐0198Japan
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Zachman MJ, Hachtel JA, Idrobo JC, Chi M. Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902993] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Michael J. Zachman
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Jordan A. Hachtel
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Juan Carlos Idrobo
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Miaofang Chi
- Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge TN 37831 USA
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Zachman MJ, Hachtel JA, Idrobo JC, Chi M. Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials. Angew Chem Int Ed Engl 2019; 59:1384-1396. [PMID: 31081976 DOI: 10.1002/anie.201902993] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 05/01/2019] [Indexed: 11/10/2022]
Abstract
Interfaces play a fundamental role in many areas of chemistry. However, their localized nature requires characterization techniques with high spatial resolution in order to fully understand their structure and properties. State-of-the-art atomic resolution or in situ scanning transmission electron microscopy and electron energy-loss spectroscopy are indispensable tools for characterizing the local structure and chemistry of materials with single-atom resolution, but they are not able to measure many properties that dictate function, such as vibrational modes or charge transfer, and are limited to room-temperature samples containing no liquids. Here, we outline emerging electron microscopy techniques that are allowing these limitations to be overcome and highlight several recent studies that were enabled by these techniques. We then provide a vision for how these techniques can be paired with each other and with in situ methods to deliver new insights into the static and dynamic behavior of functional interfaces.
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Affiliation(s)
- Michael J Zachman
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Jordan A Hachtel
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Juan Carlos Idrobo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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43
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Jung HJ, Bao JK, Chung DY, Kanatzidis MG, Dravid VP. Unconventional Defects in a Quasi-One-Dimensional KMn 6Bi 5. NANO LETTERS 2019; 19:7476-7486. [PMID: 31512881 DOI: 10.1021/acs.nanolett.9b03237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quasi-one-dimensional (Q1D) structures comprising a compact array of indefinitely long 1D nanowires (NWs) are scarce, especially in a bulk device-scale showing metallic and semiconducting behaviors along different axes. Unlike plentiful observations of nature of defects in three-/two-dimensional materials, there is a notable paucity of such reports in Q1D. Herein we present unconventional motific defects and their properties in a bulk Q1D KMn6Bi5 crystal, in which an individual NW motif acts as one body. We discovered motific inter- and intra-NW defects, such that a linear set of 1D motifs are displaced. Stress generates two domains with altered inter-NW spacings and a Bi-Mn solid solution grain, leading to a local bulk plasmon shift due to NW array reconfiguration as well as atomic rearrangement. The observation of such exotic defects and associated phenomena in this Q1D may provide guidance on overall defect mechanism in other Q1D systems and their collective anisotropic properties.
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Affiliation(s)
- Hee Joon Jung
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Jin-Ke Bao
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Duck Young Chung
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Mercouri G Kanatzidis
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
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44
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Li X, Dyck O, Jesse S, Lupini AR, Kalinin SV, Oxley MP. Structure retrieval from four-dimensional scanning transmission electron microscopy: Statistical analysis of potential pitfalls in high-dimensional data. Phys Rev E 2019; 100:023308. [PMID: 31574620 DOI: 10.1103/physreve.100.023308] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Indexed: 11/07/2022]
Abstract
Four-dimensional (4D) scanning transmission electron microscopy is one of the most rapidly growing modes of electron microscopy imaging. The advent of fast pixelated cameras and the associated data infrastructure have greatly accelerated this process. Yet conversion of the 4D datasets into physically meaningful structure images in real space remains an open issue. In this work, we demonstrate that it is possible to systematically create filters that will affect the apparent resolution or even qualitative features of the real-space structure image, reconstructing artificially generated patterns. As initial efforts, we explore statistical model selection algorithms, aiming for robustness and reliability of estimated filters. This statistical model selection analysis demonstrates the need for regularization and cross validation of inversion methods to robustly recover structure from high-dimensional diffraction datasets.
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Affiliation(s)
- Xin Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Ondrej Dyck
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Stephen Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Andrew R Lupini
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Sergei V Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Mark P Oxley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
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45
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Wen Y, Ophus C, Allen CS, Fang S, Chen J, Kaxiras E, Kirkland AI, Warner JH. Simultaneous Identification of Low and High Atomic Number Atoms in Monolayer 2D Materials Using 4D Scanning Transmission Electron Microscopy. NANO LETTERS 2019; 19:6482-6491. [PMID: 31430158 DOI: 10.1021/acs.nanolett.9b02717] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Simultaneous imaging of individual low and high atomic number atoms using annular dark field scanning transmission electron microscopy (ADF-STEM) is often challenging due to substantial differences in their scattering cross sections. This often leads to contrast from only the high atomic number species when imaged using ADF-STEM such as the Mo and 2S sites in monolayer MoS2 crystals, without detection of lighter atoms such as C, O, or N. Here, we show that by capturing an array of convergent beam electron diffraction patterns using a 2D pixelated electron detector (2D-PED) in a 4D STEM geometry enables identification of individual low and high atomic number atoms in 2D materials by multicomponent imaging. We have used ptychographic phase reconstructions, combined with angular dependent ADF-STEM reconstructions, to image light elements at lateral (nanopores) and vertical interfaces (surface dopants) within 2D monolayer MoS2. Differential phase contrast imaging (Div(DPC)) using quadrant segmentation of the 2D pixelated direct electron detector data not only qualitatively matches the ptychographic phase reconstructions in both resolution and contrast but also offers the additional potential for real time display. Using 4D-STEM, we have identified surface adatoms on MoS2 monolayers and have separated atomic columns with similar total atomic number into their relative combinations of low and high atomic number elements. These results demonstrate the rich information present in the data obtained during 4D-STEM imaging of ultrathin 2D materials and the ability of this approach to extract unique insights beyond conventional imaging.
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Affiliation(s)
- Yi Wen
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry , Lawrence Berkeley National Laboratory , 1 Cyclotron Road , Berkeley , California 94720 , United States
| | - 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
| | | | - Jun Chen
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , 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
| | - Jamie H Warner
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
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Ooe K, Seki T, Ikuhara Y, Shibata N. High contrast STEM imaging for light elements by an annular segmented detector. Ultramicroscopy 2019; 202:148-155. [DOI: 10.1016/j.ultramic.2019.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/18/2019] [Indexed: 11/25/2022]
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47
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Zamani RR, Arbiol J. Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy. NANOTECHNOLOGY 2019; 30:262001. [PMID: 30812017 DOI: 10.1088/1361-6528/ab0b0a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transmission electron microscopy (TEM) offers an ample range of complementary techniques which are able to provide essential information about the physical, chemical and structural properties of materials at the atomic scale, and hence makes a vast impact on our understanding of materials science, especially in the field of semiconductor one-dimensional (1D) nanostructures. Recent advancements in TEM instrumentation, in particular aberration correction and monochromation, have enabled pioneering experiments in complex nanostructure material systems. This review aims to address these understandings through the applications of the methodology for semiconductor nanostructures. It points out various electron microscopy techniques, in particular scanning TEM (STEM) imaging and spectroscopy techniques, with their already-employed or potential applications on 1D nanostructured semiconductors. We keep the main focus of the paper on the electronic and optoelectronic properties of such semiconductors, and avoid expanding it further. In the first part of the review, we give a brief introduction to each of the STEM-based techniques, without detailed elaboration, and mention the recent technological and conceptual developments which lead to novel characterization methodologies. For further reading, we refer the audience to a handful of papers in the literature. In the second part, we highlight the recent examples of application of the STEM methodology on the 1D nanostructure semiconductor materials, especially III-V, II-V, and group IV bare and heterostructure systems. The aim is to address the research questions on various physical properties and introduce solutions by choosing the appropriate technique that can answer the questions. Potential applications will also be discussed, the ones that have already been used for bulk and 2D materials, and have shown great potential and promise for 1D nanostructure semiconductors.
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Affiliation(s)
- Reza R Zamani
- Department of Physics, Chalmers University of Technology, Gothenburg, SE-41296, Sweden. Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
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48
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Bak J, Bin Bae H, Chung SY. Atomic-scale perturbation of oxygen octahedra via surface ion exchange in perovskite nickelates boosts water oxidation. Nat Commun 2019; 10:2713. [PMID: 31221958 PMCID: PMC6586858 DOI: 10.1038/s41467-019-10838-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 06/04/2019] [Indexed: 01/15/2023] Open
Abstract
A substantial amount of interest has been focused on ABO3-type perovskite oxides over the past decade as oxygen electrocatalysts. Despite many studies on various compositions, the correlation between the structure of the oxygen octahedra and electrocatalytic property has been overlooked, and there accordingly have been a very limited number of attempts regarding control of atomistic structure. Utilizing epitaxial LnNiO3 (Ln = La, Pr, Nd) thin films, here we demonstrate that simple electrochemical exchange of Fe in the surface region with several-unit-cell thickness is notably effective to boost the catalytic activity for the oxygen evolution reaction by different orders of magnitude. Furthermore, we directly establish that strong distortion of oxygen octahedra at the angstrom scale is readily induced during the Fe exchange, and that this structural perturbation permits easier charge transfer. The findings suggest that structural alteration can be an efficient approach to achieve exceptional electrocatalysis in crystalline oxides. While perovskite oxides are well-studied for their oxygen electrocatalysis performances, the impact of oxygen octahedra is less studied. Here, authors show electrochemical exchange of lanthanide nickelate surfaces to distort oxygen octahedra, facilitating charge transfer and improving catalysis.
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Affiliation(s)
- Jumi Bak
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea
| | - Hyung Bin Bae
- KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea
| | - Sung-Yoon Chung
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea.
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49
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Hwang YH, Yun WS, Cha GB, Hong SC, Han SW. Thermally driven homonuclear-stacking phase of MoS 2 through desulfurization. NANOSCALE 2019; 11:11138-11144. [PMID: 31107488 DOI: 10.1039/c9nr01369e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Engineering phase transitions or finding new polymorphs offers tremendous opportunities for developing functional materials. We reveal that the thermally driven desulfurization of single-crystalline MoS2 samples improves transport properties by reducing the band gap and further induces metallization. Semi-desulfurization, i.e., removal of the topmost S layer, results in the placement of the exposed Mo layers directly on top of the following sub-layers, together with the bottom S layer of the top layer. This homonuclear (AA) stacking derived from the AA' stacking of the hexagonal (2H) phase is retained even after further desulfurization of the remaining bottom S layer, i.e., full desulfurization of the top layer. Our findings fundamentally explain why the 2H phase of TMDs is characterized by AA' stacking.
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Affiliation(s)
- Young Hun Hwang
- Department of Physics and Energy Harvest-Storage Research Center (EHSRC), University of Ulsan, Ulsan 44610, Republic of Korea.
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50
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Zhao X, Sun W, Geng D, Fu W, Dan J, Xie Y, Kent PRC, Zhou W, Pennycook SJ, Loh KP. Edge Segregated Polymorphism in 2D Molybdenum Carbide. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1808343. [PMID: 30785651 DOI: 10.1002/adma.201808343] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/03/2019] [Indexed: 05/26/2023]
Abstract
Molybdenum carbide (Mo2 C), a class of unterminated MXene, is endowed with rich polymorph chemistry, but the growth conditions of the various polymorphs are not understood. Other than the most commonly observed T-phase Mo2 C, little is known about other phases. Here, Mo2 C crystals are successfully grown consisting of mixed polymorphs and polytypes via a diffusion-mediated mechanism, using liquid copper as the diffusion barrier between the elemental precursors of Mo and C. By controlling the thickness of the copper diffusion barrier layer, the crystal growth can be controlled between a highly uniform AA-stacked T-phase Mo2 C and a "wedding cake" like Mo2 C crystal with spatially delineated zone in which the Bernal-stacked Mo2 C predominate. The atomic structures, as well as the transformations between distinct stackings, are simulated and analyzed using density functional theory (DFT)-based calculations. Bernal-stacked Mo2 C has a d band closer to the Fermi energy, leading to a promising performance in catalysis as verified in hydrogen evolution reaction (HER).
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Affiliation(s)
- Xiaoxu Zhao
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 17543, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 13 Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore, 117456, Singapore
| | - Weiwei Sun
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Dechao Geng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 17543, Singapore
| | - Wei Fu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 17543, Singapore
| | - Jiadong Dan
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 13 Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore, 117456, Singapore
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Yu Xie
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Paul R C Kent
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Wu Zhou
- School of Physical Sciences and CAS Centre for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Stephen J Pennycook
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 13 Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore, 117456, Singapore
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 17543, Singapore
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