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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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2
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Bellomi S, Barlocco I, Chen X, Delgado JJ, Arrigo R, Dimitratos N, Roldan A, Villa A. Enhanced stability of sub-nanometric iridium decorated graphitic carbon nitride for H 2 production upon hydrous hydrazine decomposition. Phys Chem Chem Phys 2023; 25:1081-1095. [PMID: 36520142 DOI: 10.1039/d2cp04387d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Stabilizing metal nanoparticles is vital for large scale implementations of supported metal catalysts, particularly for a sustainable transition to clean energy, e.g., H2 production. In this work, iridium sub-nanometric particles were deposited on commercial graphite and on graphitic carbon nitride by a wet impregnation method to investigate the metal-support interaction during the hydrous hydrazine decomposition reaction. To establish a structure-activity relationship, samples were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The catalytic performance of the synthesized materials was evaluated under mild reaction conditions, i.e. 323 K and ambient pressure. The results showed that graphitic carbon nitride (GCN) enhances the stability of Ir nanoparticles compared to graphite, while maintaining remarkable activity and selectivity. Simulation techniques including Genetic Algorithm geometry screening and electronic structure analyses were employed to provide a valuable atomic level understanding of the metal-support interactions. N anchoring sites of GCN were found to minimise the thermodynamic driving force of coalescence, thus improving the catalyst stability, as well as to lead charge redistributions in the cluster improving the resistance to poisoning by decomposition intermediates.
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Affiliation(s)
- Silvio Bellomi
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, I-20133 Milano, Italy.
| | - Ilaria Barlocco
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, I-20133 Milano, Italy.
| | - Xiaowei Chen
- Departamento de Ciencia de los Materiales, Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Campus Río San Pedro, Puerto Real (Cádiz) E-11510, Spain
| | - Juan J Delgado
- Departamento de Ciencia de los Materiales, Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Campus Río San Pedro, Puerto Real (Cádiz) E-11510, Spain
| | - Rosa Arrigo
- School of Science, Engineering and Environment, University of Salford, M5 4WT, Manchester, UK
| | - Nikolaos Dimitratos
- Dipartimento di Chimica Industriale "Toso Montanari", Alma Mater Studiorum Università di Bologna, Viale Risorgimento 4, Bologna 40126, Italy.,Center for Chemical Catalysis-C3, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 4, Bologna 40136, Italy
| | - Alberto Roldan
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CF10 3AT, Cardiff, UK.
| | - Alberto Villa
- Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, I-20133 Milano, Italy.
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3
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Song Z, Li J, Davis KD, Li X, Zhang J, Zhang L, Sun X. Emerging Applications of Synchrotron Radiation X-Ray Techniques in Single Atomic Catalysts. SMALL METHODS 2022; 6:e2201078. [PMID: 36207288 DOI: 10.1002/smtd.202201078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Indexed: 06/16/2023]
Abstract
Single atom catalysts (SACs) can achieve a maximum atom utilization efficiency of 100%, which provides significantly increased active sites compared with traditional catalysts during catalytic reactions. Synchrotron radiation technology is an important characterization method for identifying single-atom catalysts. Several types of internal information, such as the coordination number, bond length and electronic structure of metals, can all be analyzed. This review will focus on the introduction of synchrotron radiation techniques and their applications in SACs. First, the fundamentals of synchrotron radiation and the corresponding techniques applied in characterization of SACs will be briefly introduced, such as X-ray absorption near edge spectroscopy and extended X-ray absorption fine structure spectroscopy and in situ techniques. The detailed information obtained from synchrotron radiation X-ray characterization is described through four routes: 1) the local environment of a specific atom; 2) the oxidation state of SACs; 3) electronic structures at different orbitals; and 4) the in situ structure modification during catalytic reaction. In addition, a systematic summary of synchrotron radiation X-ray characterization on different types of SACs (noble metals and transition metals) will be discussed.
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Affiliation(s)
- Zhongxin Song
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Junjie Li
- Department of Mechanical and Materials Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada
| | - Kieran Doyle Davis
- Department of Mechanical and Materials Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada
| | - Xifei Li
- Xi'an Key Laboratory of New Energy Materials and Devices, Institute of Advanced Electrochemical Energy & School of Materials Science and Engineering, Xi'an University of Technology, Xi'an, 710048, China
| | - Jiujun Zhang
- Institute for New Energy Materials and Engineering/College of Materials Science and Engineering, Fuzhou University, Fuzhou, 350108, China
- Institute for Sustainable Energy/College of Sciences, Shanghai University, Shanghai, 200444, China
| | - Lei Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xueliang Sun
- Department of Mechanical and Materials Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada
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4
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The effect of coordination environment on the activity and selectivity of single-atom catalysts. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214493] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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5
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Shi L, He L, Shangguan L, Zhou Y, Wang B, Zhang L, Yang Y, Teng C, Sun L. Revealing the Phase Segregation and Evolution Dynamics in Binary Nanoalloys via Electron Beam-Assisted Ultrafast Heating and Cooling. ACS NANO 2022; 16:921-929. [PMID: 35023713 DOI: 10.1021/acsnano.1c08500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gas-phase synthesized binary nanoparticles (NPs) possess ultraclean surfaces, which benefit versatile uses in sensors and catalysts. However, precise control of their configuration and properties is still a big challenge because the growth mechanism and phase evolution dynamics in these NPs are very hard to unveil. Here, we report a strategy to investigate the phase evolution dynamics in binary NPs by using e-beam assisted ultrafast local heating and cooling inside a transmission electron microscope. With this strategy, the phase segregation and corresponding shape evolution of PbBi NPs are in situ revealed. It is found that the as-prepared PbBi alloy NPs will transform into heterostructures under e-beam stimulated structural relaxation, leading to the formation of featured Janus configurations with faceted Bi polyhedron parts and intermetallic hemisphere parts. During phase segregation, Pb1Bi1 and Pb7Bi3 phases are captured and identified, and a model of phase and shape evolution of PbBi nanoalloys is developed and contrasted with that of their bulk counterparts. These findings benefit the understanding of the phase dynamics of binary NPs and can provide in-depth information for engineering their structures for practical applications.
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Affiliation(s)
- Lei Shi
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
- Centre for Advanced Materials and Manufacture, Joint Research Institute of Southeast University and Monash University, Suzhou, 215123, P. R. China
| | - Longbing He
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
- Centre for Advanced Materials and Manufacture, Joint Research Institute of Southeast University and Monash University, Suzhou, 215123, P. R. China
| | - Lei Shangguan
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
| | - Yilong Zhou
- Thermo Fisher Shanghai Nanoport, Thermo Fisher Electronic Technology Research and Development (Shanghai) Co., Ltd., Shanghai, 201203, P. R. China
| | - Binjie Wang
- Thermo Fisher Shanghai Nanoport, Thermo Fisher Electronic Technology Research and Development (Shanghai) Co., Ltd., Shanghai, 201203, P. R. China
| | - Lei Zhang
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
| | - Yufeng Yang
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
| | - Chunyu Teng
- China Aero-Polytechnology Establishment, Beijing, 100028, P. R. China
| | - Litao Sun
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096, P. R. China
- Centre for Advanced Materials and Manufacture, Joint Research Institute of Southeast University and Monash University, Suzhou, 215123, P. R. China
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6
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Chai Z. Light-Driven Alcohol Splitting by Heterogeneous Photocatalysis: Recent Advances, Mechanism and Prospects. Chem Asian J 2021; 16:460-473. [PMID: 33448692 PMCID: PMC7986840 DOI: 10.1002/asia.202001312] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/13/2021] [Indexed: 11/19/2022]
Abstract
Splitting of alcohols into hydrogen and corresponding carbonyl compounds, also called acceptorless alcohol dehydrogenation, is of great significance for both synthetic chemistry and hydrogen production. Light-Driven Alcohol Splitting (LDAS) by heterogeneous photocatalysis is a promising route to achieve such transformations, and it possesses advantages including high selectivity of the carbonyl compounds, extremely mild reaction conditions (room temperature and irradiation of visible light) and easy separation of the photocatalysts from the reaction mixtures. Because a variety of alcohols can be derived from biomass, LDAS can also be regarded as one of the most sustainable approaches for hydrogen production. In this Review, recent advances in the LDAS catalyzed by the heterogeneous photocatalysts are summarized, focusing on the mechanistic insights for the LDAS and aspects that influence the performance of the photocatalysts from viewpoints of metallic co-catalysts, semiconductors, and metal/semiconductor interfaces. In addition, challenges and prospects have been discussed in order to present a complete picture of this field.
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Affiliation(s)
- Zhigang Chai
- Department of Chemistry – Ångström LaboratoryUppsala University75121UppsalaSweden
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7
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Yang J, Wang D, Li Y. Identifying the Types and Characterization of the Active Sites on M-X-C Single-Atom Catalysts. Chemphyschem 2020; 21:2486-2496. [PMID: 32986273 DOI: 10.1002/cphc.202000595] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/16/2020] [Indexed: 11/10/2022]
Abstract
Single atom catalysts (SACs) have attracted much attention in recent years. As an essential group in SACs, M-X-C (X=nonmetallic element) materials have been demonstrated to be efficient in many reactions. However, identifying the active sites on M-X-C, especially under working conditions, is still challenging, which is crucial for chemists to further understand the mechanism underlying the reaction and better design proper SACs for specific reactions. Herein, the types and characterization of M-X-C are comprehensively summarized and discussed in this review. In addition to the basic information above, the challenges and opportunities remaining in this field will be also proposed to present a perspective to the research on the next step.
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Affiliation(s)
- Jiarui Yang
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Dingsheng Wang
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yadong Li
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
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8
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Evaluation of different rectangular scan strategies for STEM imaging. Ultramicroscopy 2020; 215:113021. [PMID: 32485392 DOI: 10.1016/j.ultramic.2020.113021] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/03/2020] [Accepted: 05/07/2020] [Indexed: 11/24/2022]
Abstract
STEM imaging is typically performed by raster scanning a focused electron probe over a sample. Here we investigate and compare three different scan patterns, making use of a programmable scan engine that allows to arbitrarily set the sequence of probe positions that are consecutively visited on the sample. We compare the typical raster scan with a so-called 'snake' pattern where the scan direction is reversed after each row and a novel Hilbert scan pattern that changes scan direction rapidly and provides an homogeneous treatment of both scan directions. We experimentally evaluate the imaging performance on a single crystal test sample by varying dwell time and evaluating behaviour with respect to sample drift. We demonstrate the ability of the Hilbert scan pattern to more faithfully represent the high frequency content of the image in the presence of sample drift. It is also shown that Hilbert scanning provides reduced bias when measuring lattice parameters from the obtained scanned images while maintaining similar precision in both scan directions which is especially important when e.g. performing strain analysis. Compared to raster scanning with flyback correction, both snake and Hilbert scanning benefit from dose reduction as only small probe movement steps occur.
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9
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Resolving Dirac electrons with broadband high-resolution NMR. Nat Commun 2020; 11:1285. [PMID: 32152300 PMCID: PMC7062727 DOI: 10.1038/s41467-020-14838-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 02/07/2020] [Indexed: 11/20/2022] Open
Abstract
Detecting the metallic Dirac electronic states on the surface of Topological Insulators (TIs) is critical for the study of important surface quantum properties (SQPs), such as Majorana zero modes, where simultaneous probing of the bulk and edge electron states is required. However, there is a particular shortage of experimental methods, showing at atomic resolution how Dirac electrons extend and interact with the bulk interior of nanoscaled TI systems. Herein, by applying advanced broadband solid-state 125Te nuclear magnetic resonance (NMR) methods on Bi2Te3 nanoplatelets, we succeeded in uncovering the hitherto invisible NMR signals with magnetic shielding that is influenced by the Dirac electrons, and we subsequently showed how the Dirac electrons spread inside the nanoplatelets. In this way, the spin and orbital magnetic susceptibilities induced by the bulk and edge electron states were simultaneously measured at atomic scale resolution, providing a pertinent experimental approach in the study of SQPs. The detection of topological states is restricted to limited experimental tools. Here, the authors apply broadband solid-state 125Te nuclear magnetic resonance on Bi2Te3 nanoplatelets uncovering signals distinguishing edge Dirac electrons and bulk electrons.
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10
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Chen T, Ellis I, Hooper TJN, Liberti E, Ye L, Lo BTW, O'Leary C, Sheader AA, Martinez GT, Jones L, Ho PL, Zhao P, Cookson J, Bishop PT, Chater P, Hanna JV, Nellist P, Tsang SCE. Interstitial Boron Atoms in the Palladium Lattice of an Industrial Type of Nanocatalyst: Properties and Structural Modifications. J Am Chem Soc 2019; 141:19616-19624. [PMID: 31747756 DOI: 10.1021/jacs.9b06120] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
It is well-established that the inclusion of small atomic species such as boron (B) in powder metal catalysts can subtly modify catalytic properties, and the associated changes in the metal lattice imply that the B atoms are located in the interstitial sites. However, there is no compelling evidence for the occurrence of interstitial B atoms, and there is a concomitant lack of detailed structural information describing the nature of this occupancy and its effects on the metal host. In this work, we use an innovative combination of high-resolution 11B magic-angle-spinning (MAS) and 105Pd static solid-state NMR nuclear magnetic resonance (NMR), synchrotron X-ray diffraction (SXRD), in situ X-ray pair distribution function (XPDF), scanning transmission electron microscopy-annular dark field imaging (STEM-ADF), electron ptychography, and electron energy loss spectroscopy (EELS) to investigate the B atom positions, properties, and structural modifications to the palladium lattice of an industrial type interstitial boron doped palladium nanoparticle catalyst system (Pd-intB/C NPs). In this study, we report that upon B incorporation into the Pd lattice, the overall face centered cubic (FCC) lattice is maintained; however, short-range disorder is introduced. The 105Pd static solid-state NMR illustrates how different types (and levels) of structural strain and disorder are introduced in the nanoparticle history. These structural distortions can lead to the appearance of small amounts of local hexagonal close packed (HCP) structured material in localized regions. The short-range lattice tailoring of the Pd framework to accommodate interstitial B dopants in the octahedral sites of the distorted FCC structure can be imaged by electron ptychography. This study describes new toolsets that enable the characterization of industrial metal nanocatalysts across length scales from macro- to microanalysis, which gives important guidance to the structure-activity relationship of the system.
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Affiliation(s)
- Tianyi Chen
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom.,Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Ieuan Ellis
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom.,Johnson Matthey , Blount's Court, Sonning Common , Reading RG4 9NH , United Kingdom
| | - Thomas J N Hooper
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Emanuela Liberti
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Lin Ye
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom
| | - Benedict T W Lo
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom
| | - Colum O'Leary
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Alexandra A Sheader
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Gerardo T Martinez
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Lewys Jones
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Ping-Luen Ho
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom.,Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Pu Zhao
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom
| | - James Cookson
- Johnson Matthey , Blount's Court, Sonning Common , Reading RG4 9NH , United Kingdom
| | - Peter T Bishop
- Johnson Matthey , Blount's Court, Sonning Common , Reading RG4 9NH , United Kingdom
| | - Philip Chater
- Diamond Light Source Ltd. , Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE , United Kingdom
| | - John V Hanna
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Peter Nellist
- Department of Materials , University of Oxford , Oxford OX1 3PH , United Kingdom
| | - Shik Chi Edman Tsang
- Wolfson Catalysis Center, Department of Chemistry , University of Oxford , Oxford OX1 3QR , United Kingdom
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11
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Shim JH, Kang H, Kim YM, Lee S. In Situ Observation of the Effect of Accelerating Voltage on Electron Beam Damage of Layered Cathode Materials for Lithium-Ion Batteries. ACS APPLIED MATERIALS & INTERFACES 2019; 11:44293-44299. [PMID: 31687809 DOI: 10.1021/acsami.9b15608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electron beam damage from transmission electron microscopy of layered lithium transition-metal oxides is a threshold phenomenon that depends on the electron beam energy, which we demonstrate in this study by varying the accelerating voltage of a scanning transmission electron microscope. The electron beam irradiation experiment shows that Ni in LiNiO2 has much lower threshold energy for displacement than Co in LiCoO2, which is supported by DFT calculations predicting that Ni has lower migration energy. The transition-metal ions are reduced from the oxidation state of +3 to +2 during migration from their original positions to the lithium sites, and Ni is more easily reduced than Co because of its electronic configuration. In addition, the high-energy electron beam induces oxygen release, which is another symptom of degradation of materials that occurs more strongly in Ni-containing materials with ion displacement.
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Affiliation(s)
- Jae-Hyun Shim
- Department of Advanced Materials and Energy Engineering , Dongshin University , Naju 58245 , Republic of Korea
| | - Hyosik Kang
- Department of Nanochemistry , Gachon University , Seongnam 13120 , Republic of Korea
| | - Young-Min Kim
- Department of Energy Science , Sungkyunkwan University (SKKU) , Suwon 16419 , Republic of Korea
| | - Sanghun Lee
- Department of Nanochemistry , Gachon University , Seongnam 13120 , Republic of Korea
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12
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13
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Nanoparticles and Single Atoms in Commercial Carbon-Supported Platinum-Group Metal Catalysts. Catalysts 2019. [DOI: 10.3390/catal9020134] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Nanoparticles of platinum-group metals (PGM) on carbon supports are widely used as catalysts for a number of chemical and electrochemical conversions on laboratory and industrial scale. The newly emerging field of single-atom catalysis focuses on the ultimate level of metal dispersion, i.e. atomically dispersed metal species anchored on the substrate surface. However, the presence of single atoms in traditional nanoparticle-based catalysts remains largely overlooked. In this work, we use aberration-corrected scanning transmission electron microscope to investigate four commercially available nanoparticle-based PGM/C catalysts (PGM = Ru, Rh, Pd, Pt). Annular dark-field (ADF) images at high magnifications reveal that in addition to nanoparticles, single atoms are also present on the surface of carbon substrates. Scanning electron microscopy, X-ray diffraction and size distribution analysis show that the materials vary in nanoparticle size and type of carbon support. These observations raise questions about the possible ubiquitous presence of single atoms in conventional nanoparticle PGM/C catalysts and the role they may play in their synthesis, activity, and stability. We critically discuss the observations with regard to the quickly developing field of single atom catalysis.
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14
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Affiliation(s)
| | - Philippe Serp
- LCC CNRS-UPR 8241 ENSIACET Université de Toulouse Toulouse France
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15
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van Omme JT, Zakhozheva M, Spruit RG, Sholkina M, Pérez Garza HH. Advanced microheater for in situ transmission electron microscopy; enabling unexplored analytical studies and extreme spatial stability. Ultramicroscopy 2018; 192:14-20. [DOI: 10.1016/j.ultramic.2018.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/09/2018] [Accepted: 05/16/2018] [Indexed: 10/16/2022]
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16
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Potapov P, Svistunova EL, Gulyaev AA. Mapping Chemical Bonds in Semiconductor Devices by Monitoring the Shifts of EELS Edges. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2017; 23:926-931. [PMID: 28849753 DOI: 10.1017/s1431927617012508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) can deliver information about variations of bonding at the nm scale. This is typically performed by analyzing the electron-loss near edge structure (ELNES) of given EELS edges. The present paper demonstrates an alternative way of a bonding examination through monitoring the EELS onset positions. Two conditions are essential for their accurate measurement. One (hardware) is using the dual EELS instrumentation that provides near simultaneous acquisition of low-loss and core-loss spectra. Another (software) is the least-square fitting of observed spectra to a reference spectrum. The combination of these hardware and software techniques reveals the positions of EELS onsets with the precision sufficient for mapping tiny variations of bonding. The paper shows that the method is capable of helping to solve practical tasks of nanoscale engineering like the analysis of modern CMOS devices.
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Affiliation(s)
- Pavel Potapov
- GLOBALFOUNDRIES Dresden, Wilschdorfer Landstraße 101, 01109 Dresden, Germany
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17
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The impact of STEM aberration correction on materials science. Ultramicroscopy 2017; 180:22-33. [DOI: 10.1016/j.ultramic.2017.03.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/04/2017] [Accepted: 03/16/2017] [Indexed: 11/22/2022]
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18
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Tavakkoli M, Holmberg N, Kronberg R, Jiang H, Sainio J, Kauppinen EI, Kallio T, Laasonen K. Electrochemical Activation of Single-Walled Carbon Nanotubes with Pseudo-Atomic-Scale Platinum for the Hydrogen Evolution Reaction. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00199] [Citation(s) in RCA: 229] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mohammad Tavakkoli
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Nico Holmberg
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Rasmus Kronberg
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Hua Jiang
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Jani Sainio
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Esko I. Kauppinen
- Department
of Applied Physics, Aalto University, School of Science, P.O. Box 15100, FI 00076 Aalto, Finland
| | - Tanja Kallio
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Kari Laasonen
- Department
of Chemistry, Aalto University, School of Chemical Technology, P.O. Box 16100, FI-00076 Aalto, Finland
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Oxley MP, Lupini AR, Pennycook SJ. Ultra-high resolution electron microscopy. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:026101. [PMID: 28008874 DOI: 10.1088/1361-6633/80/2/026101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The last two decades have seen dramatic advances in the resolution of the electron microscope brought about by the successful correction of lens aberrations that previously limited resolution for most of its history. We briefly review these advances, the achievement of sub-Ångstrom resolution and the ability to identify individual atoms, their bonding configurations and even their dynamics and diffusion pathways. We then present a review of the basic physics of electron scattering, lens aberrations and their correction, and an approximate imaging theory for thin crystals which provides physical insight into the various different imaging modes. Then we proceed to describe a more exact imaging theory starting from Yoshioka's formulation and covering full image simulation methods using Bloch waves, the multislice formulation and the frozen phonon/quantum excitation of phonons models. Delocalization of inelastic scattering has become an important limiting factor at atomic resolution. We therefore discuss this issue extensively, showing how the full-width-half-maximum is the appropriate measure for predicting image contrast, but the diameter containing 50% of the excitation is an important measure of the range of the interaction. These two measures can differ by a factor of 5, are not a simple function of binding energy, and full image simulations are required to match to experiment. The Z-dependence of annular dark field images is also discussed extensively, both for single atoms and for crystals, and we show that temporal incoherence must be included accurately if atomic species are to be identified through matching experimental intensities to simulations. Finally we mention a few promising directions for future investigation.
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Affiliation(s)
- Mark P Oxley
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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20
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Sachan R, Zarkadoula E, Lang M, Trautmann C, Zhang Y, Chisholm MF, Weber WJ. Insights on dramatic radial fluctuations in track formation by energetic ions. Sci Rep 2016; 6:27196. [PMID: 27250764 PMCID: PMC4890171 DOI: 10.1038/srep27196] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 05/16/2016] [Indexed: 11/18/2022] Open
Abstract
We report on unexpected dramatic radial variations in ion tracks formed by irradiation with energetic ions (2.3 GeV (208)Pb) at a constant electronic energy-loss (~42 keV/nm) in pyrochlore-structured Gd2TiZrO7. Though previous studies have shown track formation and average track diameter measurements in the Gd2TixZr(1-x)O7 system, the present work clearly reveals the importance of the recrystallization process in ion track formation in this system, which leads to more morphological complexities in tracks than currently accepted behavior. The ion track profile is usually considered to be diametrically uniform for a constant value of electronic energy-loss. This study reveals the diameter variations to be as large as ~40% within an extremely short incremental track length of ~20 nm. Our molecular dynamics simulations show that these fluctuations in diameter of amorphous core and overall track diameter are attributed to the partial substitution of Ti atoms by Zr atoms, which have a large difference in ionic radii, on the B-site in pyrochlore lattice. This random distribution of Ti and Zr atoms leads to a local competition between amorphous phase formation (favored by Ti atoms) and defect-fluorite phase formation (favored by Zr atoms) during the recrystallization process and finally introduces large radial variations in track morphology.
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Affiliation(s)
- Ritesh Sachan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Eva Zarkadoula
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Maik Lang
- Department of Nuclear Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Christina Trautmann
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse, 1, Darmstadt, 64291, Germany
- Materialwissenschaft, Technische Universität Darmstadt, Darmstadt, 64287, Germany
| | - Yanwen Zhang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Matthew F. Chisholm
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - William J. Weber
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, 37996, USA
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21
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Han CW, Iddir H, Uzun A, Curtiss LA, Browning ND, Gates BC, Ortalan V. Migration of Single Iridium Atoms and Tri-iridium Clusters on MgO Surfaces: Aberration-Corrected STEM Imaging and Ab Initio Calculations. J Phys Chem Lett 2015; 6:4675-9. [PMID: 26544015 DOI: 10.1021/acs.jpclett.5b01884] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
To address the challenge of fast, direct atomic-scale visualization of the migration of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ∼0.1 s per frame) to visualize the migration of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir3 cluster on MgO(110). Sequential Z-contrast images elucidate the surface transport mechanisms. Density functional theory (DFT) calculations provided estimates of the migration energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow visualization and fundamental understanding of surface migration phenomena pertaining to supported catalysts and other materials.
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Affiliation(s)
- Chang Wan Han
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States
| | - Hakim Iddir
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
| | - Alper Uzun
- Department of Chemical and Biological Engineering, Koç University , Sariyer, Istanbul 34459, Turkey
| | - Larry A Curtiss
- Materials Science Division, Argonne National Laboratory , Lemont, Illinois 60439, United States
| | - Nigel D Browning
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States
| | - Bruce C Gates
- Department of Chemical Engineering & Materials Science, University of California , Davis, California 95616, United States
| | - Volkan Ortalan
- School of Materials Engineering, Purdue University , West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States
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22
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Gámez-Mendoza L, Resto O, Martínez-Iñesta M. Effect of using polyimide capillaries during thermal experiments on the particle size distribution of supported Pt nanoparticles. J Appl Crystallogr 2015. [DOI: 10.1107/s1600576715015083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Kapton HN-type polyimide capillaries are commonly used as sample holders for transmission X-ray experiments at temperatures below 673 K because of their thermal stability, high X-ray transmittance and low cost. Using high-angle annular dark field scanning high-resolution transmission electron microscopy and thermogravimetric analysis, this work shows that using polyimide capillaries leads to the overgrowth of supported Pt nanoparticles during reduction at temperatures below the glass transition temperature (Tg= 658 K) owing to an outgassing of water from the polyimide. Quartz capillaries were also studied and this overgrowth was not observed.
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23
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Kundu S, Kundu P, Van Tendeloo G, Ravishankar N. Au2S(x)/CdS nanorods by cation exchange: mechanistic insights into the competition between cation-exchange and metal ion reduction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:3895-3900. [PMID: 24889074 DOI: 10.1002/smll.201400524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/08/2014] [Indexed: 06/03/2023]
Abstract
It is well known that metals with higher electron affinity like Au tend to undergo reduction rather than cation-exchange. It is experimentally shown that under certain conditions cation-exchange is dominant over reduction. Thermodynamic calculation further consolidates the understanding and paves the way for better predictability of cation-exchange/reduction reactions for other systems.
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Affiliation(s)
- Subhajit Kundu
- Materials Research Centre, Indian Institute of Science, C.V. Raman Avenue, Bangalore, 560012, India
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24
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Jones L, Nellist PD. Identifying and correcting scan noise and drift in the scanning transmission electron microscope. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:1050-1060. [PMID: 23673234 DOI: 10.1017/s1431927613001402] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The aberration-corrected scanning transmission electron microscope has great sensitivity to environmental or instrumental disturbances such as acoustic, mechanical, or electromagnetic interference. This interference can introduce distortions to the images recorded and degrade both signal noise and resolution performance. In addition, sample or stage drift can cause the images to appear warped and leads to unreliable lattice parameters being exhibited. Here a detailed study of the sources, natures, and effects of imaging distortions is presented, and from this analysis a piece of image reconstruction code has been developed that can restore the majority of the effects of these detrimental image distortions for atomic-resolution data. Example data are presented, and the performance of the restored images is compared quantitatively against the as-recorded data. An improvement in apparent resolution of 16% and an improvement in signal-to-noise ratio of 30% were achieved, as well as correction of the drift up to the precision to which it can be measured.
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Affiliation(s)
- Lewys Jones
- Department of Materials, University of Oxford, 13 Parks Road, Oxford OX13PH, UK.
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25
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26
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Krumeich F, Müller E, Wepf R. Phase-contrast imaging in aberration-corrected scanning transmission electron microscopy. Micron 2013; 49:1-14. [DOI: 10.1016/j.micron.2013.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/17/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
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27
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Linck M. Optimum aberration coefficients for recording high-resolution off-axis holograms in a Cs-corrected TEM. Ultramicroscopy 2013; 124:77-87. [DOI: 10.1016/j.ultramic.2012.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/10/2012] [Accepted: 08/14/2012] [Indexed: 10/28/2022]
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28
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Kadkhodazadeh S. High resolution STEM of quantum dots and quantum wires. Micron 2013; 44:75-92. [DOI: 10.1016/j.micron.2012.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/07/2012] [Accepted: 10/08/2012] [Indexed: 11/29/2022]
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29
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Pennycook S. Seeing the atoms more clearly: STEM imaging from the Crewe era to today. Ultramicroscopy 2012; 123:28-37. [DOI: 10.1016/j.ultramic.2012.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 05/07/2012] [Accepted: 05/12/2012] [Indexed: 10/28/2022]
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30
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Krumeich F, Müller E, Wepf R, Conrad M, Reich C, Harbrecht B, Nesper R. The structure of dodecagonal (Ta,V)1.6Te imaged by phase-contrast scanning transmission electron microscopy. J SOLID STATE CHEM 2012. [DOI: 10.1016/j.jssc.2012.04.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Vaz CAF. Electric field control of magnetism in multiferroic heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:333201. [PMID: 22824827 DOI: 10.1088/0953-8984/24/33/333201] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.
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Affiliation(s)
- C A F Vaz
- SwissFEL, Paul Scherrer Institut, Villigen PSI, Switzerland.
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32
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Kotula PG, Klenov DO, von Harrach HS. Challenges to quantitative multivariate statistical analysis of atomic-resolution X-ray spectral. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2012; 18:691-698. [PMID: 22849798 DOI: 10.1017/s1431927612001201] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A new aberration-corrected scanning transmission electron microscope equipped with an array of Si-drift energy-dispersive X-ray spectrometers has been utilized to acquire spectral image data at atomic resolution. The resulting noisy data were subjected to multivariate statistical analysis to noise filter, remove an unwanted and partially overlapping non-sample-specific X-ray signal, and extract the relevant correlated X-ray signals (e.g., channels with L and K lines). As an example, the Y₂Ti₂O₇ pyrochlore-structured oxide (assumed here to be ideal) was interrogated at the [011] projection. In addition to pure columns of Y and Ti, at this projection, there are also mixed 50-50 at. % Y-Ti columns. An attempt at atomic-resolution quantification is presented. The method proposed here is to subtract the non-column-specific signal from the elemental components and then quantify the data based upon an internally derived k-factor. However, a theoretical basis to predict this non-column-specific signal is needed to make this generally applicable.
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Affiliation(s)
- Paul G Kotula
- Sandia National Laboratories, P.O. Box 5800, MS 0886, Albuquerque, NM 87185-0886, USA.
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33
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High-Resolution Scanning Transmission Electron Microscopy (HRSTEM) Techniques: High-Resolution Imaging and Spectroscopy Side by Side. Chemphyschem 2012; 13:437-43. [DOI: 10.1002/cphc.201100729] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Indexed: 11/07/2022]
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McDaniel H, Oh N, Shim M. CdSe–CdSexTe1−x nanorod heterostructures: tuning alloy composition and spatially indirect recombination energies. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31464a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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35
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Pennycook SJ, Varela M. New views of materials through aberration-corrected scanning transmission electron microscopy. Microscopy (Oxf) 2011; 60 Suppl 1:S213-23. [DOI: 10.1093/jmicro/dfr030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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36
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Identification of active atomic defects in a monolayered tungsten disulphide nanoribbon. Nat Commun 2011; 2:213. [PMID: 21364552 DOI: 10.1038/ncomms1224] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 02/02/2011] [Indexed: 11/09/2022] Open
Abstract
Edge structures and atomic defects can significantly affect the physical and chemical properties of low-dimensional materials, such as nanoribbons, and therefore merit a thorough investigation at the atomic scale. Here, we successfully discriminate single atoms on a monolayered tungsten disulphide nanoribbon by means of time-resolved annular dark-field imaging and spatially resolved electron energy-loss spectroscopy. We unambiguously identify and successfully visualize in motion atomic defects, such as vacancies and edge atoms, using scanning transmission electron microscopy. We also report a direct observation of slip deformation in the nanoribbons and present evidence demonstrating that the deformation process involves the migration of vacancies and rearrangement of tungsten atoms. Single-atom defects are successfully observed for the first time during plastic deformation.
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37
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Single-atom catalysis of CO oxidation using Pt1/FeOx. Nat Chem 2011; 3:634-41. [DOI: 10.1038/nchem.1095] [Citation(s) in RCA: 3802] [Impact Index Per Article: 292.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 06/15/2011] [Indexed: 11/09/2022]
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38
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Zhang B, Zhang W, Su DS. Towards a More Accurate Particle Size Distribution of Supported Catalyst by using HAADF-STEM. ChemCatChem 2011. [DOI: 10.1002/cctc.201100096] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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40
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Sales DL, Varela M, Pennycook SJ, Galindo PL, González L, González Y, Fuster D, Molina SI. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy. NANOTECHNOLOGY 2010; 21:325706. [PMID: 20647625 DOI: 10.1088/0957-4484/21/32/325706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of [114] or [118], ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed.
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Affiliation(s)
- D L Sales
- Departamento de Ciencia de los Materiales e I M y Q I, Universidad de Cádiz, Puerto Real, Cádiz, Spain.
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Cockayne D, Kirkland AI, Nellist PD, Bleloch A. New possibilities with aberration-corrected electron microscopy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:3633-3635. [PMID: 19687057 DOI: 10.1098/rsta.2009.0135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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