1
|
Urbieta M, Barbry M, Koval P, Rivacoba A, Sánchez-Portal D, Aizpurua J, Zabala N. Footprints of atomic-scale features in plasmonic nanoparticles as revealed by electron energy loss spectroscopy. Phys Chem Chem Phys 2024; 26:14991-15004. [PMID: 38741574 DOI: 10.1039/d4cp01034e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
We present a first-principles theoretical study of the atomistic footprints in the valence electron energy loss spectroscopy (EELS) of nanometer-size metallic particles. Charge density maps of excited plasmons and EEL spectra for specific electron paths through a nanoparticle (Na380 atom cluster) are modeled using ab initio calculations within time-dependent density functional theory. Our findings unveil the atomic-scale sensitivity of EELS within this low-energy spectral range. Whereas localized surface plasmons (LSPs) are particularly sensitive to the atomistic structure of the surface probed by the electron beam, confined bulk plasmons (CBPs) reveal quantum size effects within the nanoparticle's volume. Moreover, we prove that classical local dielectric theories mimicking the atomistic structure of the nanoparticles reproduce the LSP trends observed in quantum calculations, but fall short in describing the CBP behavior observed under different electron trajectories.
Collapse
Affiliation(s)
- Mattin Urbieta
- Matematika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola (Eibarko Atala), University of the Basque Country UPV/EHU, 20018 Eibar, Spain.
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Marc Barbry
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Peter Koval
- Simune Atomistics S.L., Avenida de Tolosa 76, Donostia-San Sebastian 20018, Spain
| | - Alberto Rivacoba
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Daniel Sánchez-Portal
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Javier Aizpurua
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Department of Electricity and Electronics, FCT-ZTF, University of the Basque Country (UPV/EHU), Barrio Sarriena z/g, Leioa, Bizkaia 48940, Spain.
- Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia 48011, Spain
| | - Nerea Zabala
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Department of Electricity and Electronics, FCT-ZTF, University of the Basque Country (UPV/EHU), Barrio Sarriena z/g, Leioa, Bizkaia 48940, Spain.
| |
Collapse
|
2
|
Nguyen KX, Jiang Y, Lee CH, Kharel P, Zhang Y, van der Zande AM, Huang PY. Achieving sub-0.5-angstrom-resolution ptychography in an uncorrected electron microscope. Science 2024; 383:865-870. [PMID: 38386746 DOI: 10.1126/science.adl2029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 01/19/2024] [Indexed: 02/24/2024]
Abstract
Subangstrom resolution has long been limited to aberration-corrected electron microscopy, where it is a powerful tool for understanding the atomic structure and properties of matter. Here, we demonstrate electron ptychography in an uncorrected scanning transmission electron microscope (STEM) with deep subangstrom spatial resolution down to 0.44 angstroms, exceeding the conventional resolution of aberration-corrected tools and rivaling their highest ptychographic resolutions. Our approach, which we demonstrate on twisted two-dimensional materials in a widely available commercial microscope, far surpasses prior ptychographic resolutions (1 to 5 angstroms) of uncorrected STEMs. We further show how geometric aberrations can create optimized, structured beams for dose-efficient electron ptychography. Our results demonstrate that expensive aberration correctors are no longer required for deep subangstrom resolution.
Collapse
Affiliation(s)
- Kayla X Nguyen
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Yi Jiang
- Advanced Photon Source Facility, Argonne National Laboratory, Lemont, IL, USA
| | - Chia-Hao Lee
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Priti Kharel
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Yue Zhang
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Arend M van der Zande
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Pinshane Y Huang
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL, USA
| |
Collapse
|
3
|
Moradifar P, Liu Y, Shi J, Siukola Thurston ML, Utzat H, van Driel TB, Lindenberg AM, Dionne JA. Accelerating Quantum Materials Development with Advances in Transmission Electron Microscopy. Chem Rev 2023. [PMID: 37979189 DOI: 10.1021/acs.chemrev.2c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2023]
Abstract
Quantum materials are driving a technology revolution in sensing, communication, and computing, while simultaneously testing many core theories of the past century. Materials such as topological insulators, complex oxides, superconductors, quantum dots, color center-hosting semiconductors, and other types of strongly correlated materials can exhibit exotic properties such as edge conductivity, multiferroicity, magnetoresistance, superconductivity, single photon emission, and optical-spin locking. These emergent properties arise and depend strongly on the material's detailed atomic-scale structure, including atomic defects, dopants, and lattice stacking. In this review, we describe how progress in the field of electron microscopy (EM), including in situ and in operando EM, can accelerate advances in quantum materials and quantum excitations. We begin by describing fundamental EM principles and operation modes. We then discuss various EM methods such as (i) EM spectroscopies, including electron energy loss spectroscopy (EELS), cathodoluminescence (CL), and electron energy gain spectroscopy (EEGS); (ii) four-dimensional scanning transmission electron microscopy (4D-STEM); (iii) dynamic and ultrafast EM (UEM); (iv) complementary ultrafast spectroscopies (UED, XFEL); and (v) atomic electron tomography (AET). We describe how these methods could inform structure-function relations in quantum materials down to the picometer scale and femtosecond time resolution, and how they enable precision positioning of atomic defects and high-resolution manipulation of quantum materials. For each method, we also describe existing limitations to solve open quantum mechanical questions, and how they might be addressed to accelerate progress. Among numerous notable results, our review highlights how EM is enabling identification of the 3D structure of quantum defects; measuring reversible and metastable dynamics of quantum excitations; mapping exciton states and single photon emission; measuring nanoscale thermal transport and coupled excitation dynamics; and measuring the internal electric field and charge density distribution of quantum heterointerfaces- all at the quantum materials' intrinsic atomic and near atomic-length scale. We conclude by describing open challenges for the future, including achieving stable sample holders for ultralow temperature (below 10K) atomic-scale spatial resolution, stable spectrometers that enable meV energy resolution, and high-resolution, dynamic mapping of magnetic and spin fields. With atomic manipulation and ultrafast characterization enabled by EM, quantum materials will be poised to integrate into many of the sustainable and energy-efficient technologies needed for the 21st century.
Collapse
Affiliation(s)
- Parivash Moradifar
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Yin Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jiaojian Shi
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | | | - Hendrik Utzat
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aaron M Lindenberg
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | - Jennifer A Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Stanford University, Stanford, California 94305, United States
| |
Collapse
|
4
|
Sikora O, Sternik M, Jany BR, Krok F, Piekarz P, Oleś AM. Density functional theory study of Au-fcc/Ge and Au-hcp/Ge interfaces. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2023; 14:1093-1105. [PMID: 38025198 PMCID: PMC10679839 DOI: 10.3762/bjnano.14.90] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023]
Abstract
In recent years, nanostructures with hexagonal polytypes of gold have been synthesised, opening new possibilities in nanoscience and nanotechnology. As bulk gold crystallizes in the fcc phase, surface effects can play an important role in stabilizing hexagonal gold nanostructures. Here, we investigate several heterostructures with Ge substrates, including the fcc and hcp phases of gold that have been observed experimentally. We determine and discuss their interfacial energies and optimized atomic arrangements, comparing the theory results with available experimental data. Our DFT calculations for the Au-fcc(011)/Ge(001) junction show how the presence of defects in the interface layer can help to stabilize the atomic pattern, consistent with microscopic images. Although the Au-hcp/Ge interface is characterized by a similar interface energy, it reveals large atomic displacements due to significant mismatch. Finally, analyzing the electronic properties, we demonstrate that Au/Ge systems have metallic character, but covalent-like bonding states between interfacial Ge and Au atoms are also present.
Collapse
Affiliation(s)
- Olga Sikora
- Faculty of Materials Engineering and Physics, Cracow University of Technology, Podchorążych 1, PL-30084 Kraków, Poland
| | - Małgorzata Sternik
- Institute of Nuclear Physics, Polish Academy of Sciences, W. E. Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Benedykt R Jany
- Marian Smoluchowski Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30348 Krakow, Poland
| | - Franciszek Krok
- Marian Smoluchowski Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30348 Krakow, Poland
| | - Przemysław Piekarz
- Institute of Nuclear Physics, Polish Academy of Sciences, W. E. Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Andrzej M Oleś
- Institute of Theoretical Physics, Jagiellonian University, Prof. Stanisława Łojasiewicza 11, PL-30348 Kraków, Poland
| |
Collapse
|
5
|
Chao HY, Venkatraman K, Moniri S, Jiang Y, Tang X, Dai S, Gao W, Miao J, Chi M. In Situ and Emerging Transmission Electron Microscopy for Catalysis Research. Chem Rev 2023. [PMID: 37327473 DOI: 10.1021/acs.chemrev.2c00880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Catalysts are the primary facilitator in many dynamic processes. Therefore, a thorough understanding of these processes has vast implications for a myriad of energy systems. The scanning/transmission electron microscope (S/TEM) is a powerful tool not only for atomic-scale characterization but also in situ catalytic experimentation. Techniques such as liquid and gas phase electron microscopy allow the observation of catalysts in an environment conducive to catalytic reactions. Correlated algorithms can greatly improve microscopy data processing and expand multidimensional data handling. Furthermore, new techniques including 4D-STEM, atomic electron tomography, cryogenic electron microscopy, and monochromated electron energy loss spectroscopy (EELS) push the boundaries of our comprehension of catalyst behavior. In this review, we discuss the existing and emergent techniques for observing catalysts using S/TEM. Challenges and opportunities highlighted aim to inspire and accelerate the use of electron microscopy to further investigate the complex interplay of catalytic systems.
Collapse
Affiliation(s)
- Hsin-Yun Chao
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
| | - Kartik Venkatraman
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
| | - Saman Moniri
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Yongjun Jiang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Xuan Tang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Sheng Dai
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China
| | - Wenpei Gao
- School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jianwei Miao
- Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Miaofang Chi
- Center for Nanophase Materials Sciences, One Bethel Valley Road, Building 4515, Oak Ridge, Tennessee 37831-6064, United States
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Prifti E, Buban JP, Thind AS, Klie RF. Variational Convolutional Autoencoders for Anomaly Detection in Scanning Transmission Electron Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205977. [PMID: 36651114 DOI: 10.1002/smll.202205977] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Identifying point defects and other structural anomalies using scanning transmission electron microscopy (STEM) is important to understand a material's properties caused by the disruption of the regular pattern of crystal lattice. Due to improvements in instrumentation stability and electron optics, atomic-resolution images with a field of view of several hundred nanometers can now be routinely acquired at 1-10 Hz frame rates and such data, which often contain thousands of atomic columns, need to be analyzed. To date, image analysis is performed largely manually, but recent developments in computer vision (CV) and machine learning (ML) now enable automated analysis of atomic structures and associated defects. Here, the authors report on how a Convolutional Variational Autoencoder (CVAE) can be utilized to detect structural anomalies in atomic-resolution STEM images. Specifically, the training set is limited to perfect crystal images , and the performance of a CVAE in differentiating between single-crystal bulk data or point defects is demonstrated. It is found that the CVAE can reproduce the perfect crystal data but not the defect input data. The disagreesments between the CVAE-predicted data for defects allows for a clear and automatic distinction and differentiation of several point defect types.
Collapse
Affiliation(s)
- Enea Prifti
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - James P Buban
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - Arashdeep Singh Thind
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| | - Robert F Klie
- Department of Physics, University of Illinois Chicago, 845 W Taylor Street, Chicago, IL, 60607, USA
| |
Collapse
|
8
|
Yang R, Mei L, Fan Y, Zhang Q, Liao HG, Yang J, Li J, Zeng Z. Fabrication of liquid cell for in situ transmission electron microscopy of electrochemical processes. Nat Protoc 2023; 18:555-578. [PMID: 36333447 DOI: 10.1038/s41596-022-00762-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 07/12/2022] [Indexed: 11/06/2022]
Abstract
Fundamentally understanding the complex electrochemical reactions that are associated with energy devices (e.g., rechargeable batteries, fuel cells and electrolyzers) has attracted worldwide attention. In situ liquid cell transmission electron microscopy (TEM) offers opportunities to directly observe and analyze in-liquid specimens without the need for freezing or drying, which opens up a door for visualizing these complex electrochemical reactions at the nano scale in real time. The key to the success of this technique lies in the design and fabrication of electrochemical liquid cells with thin but strong imaging windows. This protocol describes the detailed procedures of our established technique for the fabrication of such electrochemical liquid cells (~110 h). In addition, the protocol for the in situ TEM observation of electrochemical reactions by using the nanofabricated electrochemical liquid cell is also presented (2 h). We also show and analyze experimental results relating to the electrochemical reactions captured. We believe that this protocol will shed light on strategies for fabricating high-quality TEM liquid cells for probing dynamic electrochemical reactions in high resolution, providing a powerful research tool. This protocol requires access to a clean room equipped with specialized nanofabrication setups as well as TEM characterization equipment.
Collapse
Affiliation(s)
- Ruijie Yang
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Liang Mei
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Yingying Fan
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Qingyong Zhang
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Hong-Gang Liao
- State Key Lab of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Juan Yang
- School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Ju Li
- Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Zhiyuan Zeng
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China. .,Shenzhen Research Institute, City University of Hong Kong, Shenzhen, China.
| |
Collapse
|
9
|
Lindner J, Ross U, Roddatis V, Jooss C. Langmuir analysis of electron beam induced plasma in environmental TEM. Ultramicroscopy 2023; 243:113629. [DOI: 10.1016/j.ultramic.2022.113629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 08/22/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022]
|
10
|
Evidence of Delta Phase of Fe in MBE-Grown Thin Epitaxial Films on GaAs. COATINGS 2022. [DOI: 10.3390/coatings12060771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Fe/GaAs is an important system for the study of spin injection behavior that can vary with the nature and interfaces of Fe films. Here, we investigate the effect of interfacial strain on the microstructure, interfaces and phase-formation behavior in epitaxially grown Fe films. To vary the strain, we have characterized Fe films of various thicknesses ranging from 10 to 1000 nm which were grown using molecular beam epitaxy on GaAs (011) and AlGaAs (001) substrates. High resolution X-ray diffraction studies revealed that films with higher thicknesses exhibited an equilibrium α-Fe phase, while the films with less than 10 nm thicknesses indicated the presence of d-Fe. Transmission electron microscopy revealed the interface for 10-nm-thick films had strain lobes with no interfacial phase formation for films deposited at room temperature. At a higher deposition temperature of 175 °C, similar strain lobes were observed for a 10-nm-thick film. Extended annealing at 200 °C transformed the metastable d-Fe phase to an equilibrium α-Fe. However, at higher temperature, the interface contained an intermixing layer of (FeAl)GaAs. We demonstrate that the interfacial strain plays a major role in stabilizing the metastable d-Fe on GaAs.
Collapse
|
11
|
Curtis WA, Willis SA, Flannigan DJ. Single-photoelectron collection efficiency in 4D ultrafast electron microscopy. Phys Chem Chem Phys 2022; 24:14044-14054. [PMID: 35640169 DOI: 10.1039/d2cp01250b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In femtosecond (fs) 4D ultrafast electron microscopy (UEM), a tradeoff is made between photoelectrons per packet and time resolution. One consequence of this can be longer-than-desirable acquisition times for low-density packets, and particularly for low repetition rates when complete photothermal dissipation is required. Thus, gaining an understanding of photoelectron trajectories in the gun region is important for identifying factors that limit collection efficiency (CE; fraction of photoelectrons that enter the illumination system). Here, we continue our work on the systematic study of photoelectron trajectories in the gun region of a Thermo Fisher/FEI Tecnai Femto UEM, focusing specifically on CE in the single-electron regime. Using General Particle Tracer, calculated field maps, and the exact architecture of the Tecnai Femto UEM, we simulated the effects of fs laser parameters and key gun elements on CE. The results indicate CE strongly depends upon the laser spot size on the source, the (unbiased) Wehnelt aperture diameter, and the incident photon energy. The CE dispersion with laser spot size is found to be strongly dependent on aperture diameter, being nearly dispersionless for the largest apertures. A gun crossover is also observed, with the beam-waist position being dependent on the aperture diameter, further illustrating that the Wehnelt aperture acts as a simple, fixed electrostatic lens in UEM mode. This work provides further insights into the operational aspects of fs 4D UEM.
Collapse
Affiliation(s)
- Wyatt A Curtis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Simon A Willis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA. .,Minnesota Institute for Ultrafast Science, University of Minnesota, Minneapolis, MN 55455, USA
| |
Collapse
|
12
|
Firoozabadi S, Kükelhan P, Beyer A, Lehr J, Volz K. Quantitative composition determination by ADF-STEM at a low angular regime: a combination of EFSTEM and 4DSTEM. Ultramicroscopy 2022; 240:113550. [DOI: 10.1016/j.ultramic.2022.113550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/26/2022] [Accepted: 05/04/2022] [Indexed: 10/18/2022]
|
13
|
Li C, Hassan A, Palmai M, Snee P, Baveye PC, Darnault CJG. Colloidal stability and aggregation kinetics of nanocrystal CdSe/ZnS quantum dots in aqueous systems: Effects of ionic strength, electrolyte type, and natural organic matter. SN APPLIED SCIENCES 2022. [DOI: 10.1007/s42452-022-04948-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
AbstractUnderstanding the stability and aggregation of nanoparticles in aqueous milieu is critical for assessing their behavior in the natural and engineered environmental systems and establishing their threat to human and ecosystems health. In this study, the colloidal stability and aggregation kinetics of nanocrystal quantum dots (QDs) —CdSe/ZnS QDs—were thoroughly explored under a wide range of aqueous environmental conditions. The z-average hydrodynamic diameters (z-avg. HDs) and zeta potential (ξ potential) of CdSe/ZnS QDs were measured in monovalent electrolyte (NaCl) and divalent electrolyte (CaCl2) solutions in both the absence and presence of natural organic matter (NOM)—Suwannee River natural organic matter, SRNOM to assess the dynamic growth of these nanoaggregate-QD-complexes, and the evaluation of their colloidal stability. Results show that CaCl2 was more effective to destabilize the QDs compared to NaCl at similar concentrations. An increase in NaCl concentration from 0.01 to 3.5 M increased the z-avg. HD of QD aggregates from 61.4 nm to 107.2 nm. The aggregation rates of QDs increased from 0.007 to 0.042 nm·s−1 with an increase in ionic strength from 0.5 to 3.5 M NaCl solutions, respectively. In the presence of Na+ cations, the aggregation of QDs was limited as steric forces generated by the original surface coating of QDs prevailed. In the presence of CaCl2, the aggregation of QDs was observed at a low concentration of CaCl2 (0.0001 M) with a z-avg. HD of 74.2 nm that significantly increased when the CaCl2 was higher than 0.002 M. Larger sizes of QD aggregates were observed at each level of CaCl2 concentration in suspensions of 0.002–0.1 M, as the z-avg. HDs of QDs increased from 125.1 to 560.4 nm, respectively. In the case of CaCl2, an increase in aggregation rates occurred from 0.035 to 0.865 nm·s−1 with an increase in ionic strength from 0.0001 M to 0.004 M, respectively. With Ca2+ cations, the aggregation of QDs was enhanced due to the bridging effects from the formation of complexes between Ca2+ cations in solution and the carboxyl group located on the surface coating of QDs. In the presence of SRNOM, the aggregation of QDs was enhanced in both monovalent and divalent electrolyte solutions. The degree of aggregation formation between QDs through cation-NOM bridges was superior for Ca2+ cations compared to Na+ cations. The presence of SRNOM resulted in a small increase in the size of the QD aggregates for each of NaCl concentrations tested (i.e., 0.01 to 3.5 M, except 0.1 M), and induced a monodispersed and narrower size distribution of QDs suspended in the monovalent electrolyte NaCl concentrations. In the presence of SRNOM, the aggregation rates of QDs increased from 0.01 to 0.024 nm 1 with the increase of NaCl concentrations from 0.01 to 2 M, respectively. The presence of SRNOM in QDs suspended in divalent electrolyte CaCl2 solutions enhanced the aggregation of QDs, resulting in the increase of z-avg. HDs of QDs by approximately 19.3%, 42.1%, 13.8%, 1.5%, and 24.8%, at CaCl2 concentrations of 0.002, 0.003, 0.005, 0.01, and 0.1 M, respectively. In the case of CaCl2, an increase in aggregation rates occurred from 0.035 to 0.865 nm·s−1 with an increase in ionic strength from 0.0001 to 0.004 M, respectively. Our findings demonstrated the colloidal stability of QDs and cations-NOM-QD nanoparticle complexes under a broad spectrum of conditions encountered in the natural and engineered environment, indicating and the potential risks from these nanoparticles in terms of human and ecosystem health.
Collapse
|
14
|
STEM Tools for Semiconductor Characterization: Beyond High-Resolution Imaging. NANOMATERIALS 2022; 12:nano12030337. [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] [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.
Collapse
|
15
|
Wang Z, Xia H, Wang P, Zhou X, Liu C, Zhang Q, Wang F, Huang M, Chen S, Wu P, Chen Y, Ye J, Huang S, Yan H, Gu L, Miao J, Li T, Chen X, Lu W, Zhou P, Hu W. Controllable Doping in 2D Layered Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104942. [PMID: 34569099 DOI: 10.1002/adma.202104942] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/03/2021] [Indexed: 06/13/2023]
Abstract
For each generation of semiconductors, the issue of doping techniques is always placed at the top of the priority list since it determines whether a material can be used in the electronic and optoelectronic industry or not. When it comes to 2D materials, significant challenges have been found in controllably doping 2D semiconductors into p- or n-type, let alone developing a continuous control of this process. Here, a unique self-modulated doping characteristic in 2D layered materials such as PtSSe, PtS0.8 Se1.2 , PdSe2 , and WSe2 is reported. The varying number of vertically stacked-monolayers is the critical factor for controllably tuning the same material from p-type to intrinsic, and to n-type doping. Importantly, it is found that the thickness-induced lattice deformation makes defects in PtSSe transit from Pt vacancies to anion vacancies based on dynamic and thermodynamic analyses, which leads to p- and n-type conductance, respectively. By thickness-modulated doping, WSe2 diode exhibits a high rectification ratio of 4400 and a large open-circuit voltage of 0.38 V. Meanwhile, the PtSSe detector overcomes the shortcoming of large dark-current in narrow-bandgap optoelectronic devices. All these findings provide a brand-new perspective for fundamental scientific studies and applications.
Collapse
Affiliation(s)
- Zhen Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Xia
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peng Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaohao Zhou
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chunsen Liu
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
- Frontier Institute of Chip and System, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Fang Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Menglin Huang
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Shiyou Chen
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
| | - Peisong Wu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunfeng Chen
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiafu Ye
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shenyang Huang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai, 200433, China
| | - Hugen Yan
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai, 200433, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jinshui Miao
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 330106, China
| | - Tianxin Li
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
| | - Xiaoshuang Chen
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 330106, China
| | - Wei Lu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 330106, China
| | - Peng Zhou
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai, 200433, China
- Frontier Institute of Chip and System, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Institute of Optoelectronics, Fudan University, Shanghai, 200433, China
| | - Weida Hu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 330106, China
| |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- Jingyue Jimmy Liu
- Department of Physics, Arizona State University, Tempe, AZ85287, USA
| |
Collapse
|
17
|
Markevich A, Hudak BM, Madsen J, Song J, Snijders PC, Lupini AR, Susi T. Mechanism of Electron-Beam Manipulation of Single-Dopant Atoms in Silicon. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:16041-16048. [PMID: 34354792 PMCID: PMC8327312 DOI: 10.1021/acs.jpcc.1c03549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/25/2021] [Indexed: 05/10/2023]
Abstract
The precise positioning of dopant atoms within bulk crystal lattices could enable novel applications in areas including solid-state sensing and quantum computation. Established scanning probe techniques are capable tools for the manipulation of surface atoms, but at a disadvantage due to their need to bring a physical tip into contact with the sample. This has prompted interest in electron-beam techniques, followed by the first proof-of-principle experiment of bismuth dopant manipulation in crystalline silicon. Here, we use first-principles modeling to discover a novel indirect exchange mechanism that allows electron impacts to non-destructively move dopants with atomic precision within the silicon lattice. However, this mechanism only works for the two heaviest group V donors with split-vacancy configurations, Bi and Sb. We verify our model by directly imaging these configurations for Bi and by demonstrating that the promising nuclear spin qubit Sb can be manipulated using a focused electron beam.
Collapse
Affiliation(s)
- Alexander Markevich
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Bethany M. Hudak
- Naval
Research Laboratory, Material Sciences and Technology, 4555 Overlook Ave SW, Washington, District of Columbia 20375, United States
| | - Jacob Madsen
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Jiaming Song
- School
of Physics, Northwest University, 1 Xuefu Avenue, Xi’an, Shaanxi 710127, China
| | - Paul C. Snijders
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Andrew R. Lupini
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Toma Susi
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| |
Collapse
|
18
|
Identification and correction of temporal and spatial distortions in scanning transmission electron microscopy. Ultramicroscopy 2021; 229:113337. [PMID: 34298205 DOI: 10.1016/j.ultramic.2021.113337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 06/03/2021] [Accepted: 06/09/2021] [Indexed: 11/23/2022]
Abstract
Scanning transmission electron microscopy (STEM) has become the technique of choice for quantitative characterization of atomic structure of materials, where the minute displacements of atomic columns from high-symmetry positions can be used to map strain, polarization, octahedra tilts, and other physical and chemical order parameter fields. The latter can be used as inputs into mesoscopic and atomistic models, providing insight into the correlative relationships and generative physics of materials on the atomic level. However, these quantitative applications of STEM necessitate understanding the microscope induced image distortions and developing the pathways to compensate them both as part of a rapid calibration procedure for in situ imaging, and the post-experimental data analysis stage. Here, we explore the spatiotemporal structure of the microscopic distortions in STEM using multivariate analysis of the atomic trajectories in the image stacks. Based on the behavior of principal component analysis (PCA), we develop the Gaussian process (GP)-based regression method for quantification of the distortion function. The limitations of such an approach and possible strategies for implementation as a part of in-line data acquisition in STEM are discussed. The analysis workflow is summarized in a Jupyter notebook that can be used to retrace the analysis and analyze the reader's data.
Collapse
|
19
|
García de Abajo FJ, Konečná A. Optical Modulation of Electron Beams in Free Space. PHYSICAL REVIEW LETTERS 2021; 126:123901. [PMID: 33834791 DOI: 10.1103/physrevlett.126.123901] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 02/16/2021] [Indexed: 05/21/2023]
Abstract
We exploit free-space interactions between electron beams and tailored light fields to imprint on-demand phase profiles on the electron wave functions. Through rigorous semiclassical theory involving a quantum description of the electrons, we show that monochromatic optical fields focused in vacuum can be used to correct electron beam aberrations and produce selected focal shapes. Stimulated elastic Compton scattering is exploited to imprint the required electron phase, which is proportional to the integral of the optical field intensity along the electron path and depends on the transverse beam position. The required light intensities are attainable in currently available ultrafast electron microscope setups, thus opening the field of free-space optical manipulation of electron beams.
Collapse
Affiliation(s)
- F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Andrea Konečná
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| |
Collapse
|
20
|
Wong LJ, Rivera N, Murdia C, Christensen T, Joannopoulos JD, Soljačić M, Kaminer I. Control of quantum electrodynamical processes by shaping electron wavepackets. Nat Commun 2021; 12:1700. [PMID: 33731697 PMCID: PMC7969958 DOI: 10.1038/s41467-021-21367-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/14/2021] [Indexed: 01/31/2023] Open
Abstract
Fundamental quantum electrodynamical (QED) processes, such as spontaneous emission and electron-photon scattering, encompass phenomena that underlie much of modern science and technology. Conventionally, calculations in QED and other field theories treat incoming particles as single-momentum states, omitting the possibility that coherent superposition states, i.e., shaped wavepackets, can alter fundamental scattering processes. Here, we show that free electron waveshaping can be used to design interferences between two or more pathways in a QED process, enabling precise control over the rate of that process. As an example, we show that free electron waveshaping modifies both spatial and spectral characteristics of bremsstrahlung emission, leading for instance to enhancements in directionality and monochromaticity. The ability to tailor general QED processes opens up additional avenues of control in phenomena ranging from optical excitation (e.g., plasmon and phonon emission) in electron microscopy to free electron lasing in the quantum regime.
Collapse
Affiliation(s)
- Liang Jie Wong
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
| | - Nicholas Rivera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chitraang Murdia
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thomas Christensen
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - John D Joannopoulos
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Marin Soljačić
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ido Kaminer
- Department of Electrical Engineering, Technion, Haifa, Israel.
| |
Collapse
|
21
|
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.
Collapse
Affiliation(s)
- Zhigang Chai
- Department of Chemistry – Ångström LaboratoryUppsala University75121UppsalaSweden
| |
Collapse
|
22
|
Zhang X, Zhang X, Yuan B, Liang C, Yu Y. Atomic-scale study of nanocatalysts by aberration-corrected electron microscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:413004. [PMID: 32666936 DOI: 10.1088/1361-648x/ab977c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Aberration-corrected electron microscopy (AC-EM) including transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) has become one of the most powerful technologies in the studies of nanocatalysts. With the current spatial resolution of sub-0.5 Å and energy resolution of 10 meV, AC-EM can quantificationally articulate the connection between catalytic properties and atomic configurations of nanocatalysts. However, the restricted irradiation sensitive characteristics of specimens pose an obstacle to solve their intrinsic structure. Low-dose imaging should be applied to overcome this problem. In addition, the choice of appropriate imaging method is also crucial to tackle specific structural problems of nanocatalysts. On the basis of careful management of electron dose and selection of suitable imaging method,in situgas and liquid S/TEM are able to reveal the structure evolution of nanocatalysts in real-time. Further combination with residual gas analysis would deepen the understanding of the catalytic reaction.
Collapse
Affiliation(s)
- Xun Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Xiuli Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Biao Yuan
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Chao Liang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Yi Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| |
Collapse
|
23
|
Abstract
For decades, differentially pumped environmental transmission electron microscopy has been a powerful tool to study dynamic structural evolution of catalysts under a gaseous environment. With the advancement of micro-electromechanical system-based technologies, windowed gas cell became increasingly popular due to its ability to achieve high pressure and its compatibility to a wide range of microscopes with minimal modification. This enables a series of imaging and analytical technologies such as atomic resolution imaging, spectroscopy, and operando, revealing details that were unprecedented before. By reviewing some of the recent work, we demonstrate that the windowed gas cell has the unique ability to solve complicated catalysis problems. We also discuss what technical difficulties need to be addressed and provide an outlook for the future of in situ environmental transmission electron microscopy (TEM) technologies and their application to the field of catalysis development.
Collapse
|
24
|
Affiliation(s)
- Dongdong Xiao
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- School of physical sciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
| |
Collapse
|
25
|
Li C, Zhang Q, Mayoral A. Ten Years of Aberration Corrected Electron Microscopy for Ordered Nanoporous Materials. ChemCatChem 2020. [DOI: 10.1002/cctc.201901861] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Chengmin Li
- Center for High-resolution Electron Microscopy (CħEM) School of Physical Science and TechnologyShanghaiTech University 393 Middle Huaxia Road Shanghai 201210 P. R. China
| | - Qing Zhang
- Center for High-resolution Electron Microscopy (CħEM) School of Physical Science and TechnologyShanghaiTech University 393 Middle Huaxia Road Shanghai 201210 P. R. China
| | - Alvaro Mayoral
- Center for High-resolution Electron Microscopy (CħEM) School of Physical Science and TechnologyShanghaiTech University 393 Middle Huaxia Road Shanghai 201210 P. R. China
| |
Collapse
|
26
|
Insight into long-period pattern by depth sectioning using aberration-corrected scanning transmission electron microscope. Ultramicroscopy 2019; 209:112885. [PMID: 31722280 DOI: 10.1016/j.ultramic.2019.112885] [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: 08/07/2019] [Revised: 10/28/2019] [Accepted: 11/03/2019] [Indexed: 11/23/2022]
Abstract
Long-period patterns (LPPs) are widely observed by transmission electron microscopy (TEM) in the study of nanoscale materials. Identifying the origin of LPPs is of significant importance when interpreting TEM images, and for an in-depth understanding of material characteristics. However, the two most common LPP categories, modulated structure and moiré patterns, are not easily differentiated by conventional TEM (CTEM). In this work, an LPP was observed in Cu2-xSe nanoplates by CTEM. And then the depth sectioning with an aberration-corrected scanning transmission electron microscope (AC STEM) has been performed to determine the LPP type. Two misorientated layers were recognized from the depth-series of atomic resolution images of an LPP region, confirming the LPP is a moiré pattern caused by two twisted stacked crystal flakes which commonly exists in nanosized materials. This depth sectioning method is generally applicable for structural characterization of layered systems, and is a powerful approach for the in-situ structural probe of nanomaterials. It is promising to be extended to fast three-dimensional (3D) reconstruction.
Collapse
|
27
|
Chirita Mihaila AI, Susi T, Kotakoski J. Influence of temperature on the displacement threshold energy in graphene. Sci Rep 2019; 9:12981. [PMID: 31506494 PMCID: PMC6736860 DOI: 10.1038/s41598-019-49565-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 08/24/2019] [Indexed: 11/09/2022] Open
Abstract
The atomic structure of nanomaterials is often studied using transmission electron microscopy. In addition to image formation, the energetic electrons impinging on the sample may also cause damage. In a good conductor such as graphene, the damage is limited to the knock-on process caused by elastic electron-nucleus scattering. This process is determined by the kinetic energy an atom needs to be sputtered, i.e. its displacement threshold energy Ed. This is typically assumed to have a fixed value for all electron impacts on equivalent atoms within a crystal. Here we show using density functional tight-binding simulations that the displacement threshold energy is affected by thermal perturbations of atoms from their equilibrium positions. This effect can be accounted for in the estimation of the displacement cross section by replacing the constant threshold energy value with a distribution. Our refined model better describes previous precision measurements of graphene knock-on damage, and should be considered also for other low-dimensional materials.
Collapse
Affiliation(s)
| | - Toma Susi
- University of Vienna, Faculty of Physics, Boltzmanngasse 5, 1090, Vienna, Austria
| | - Jani Kotakoski
- University of Vienna, Faculty of Physics, Boltzmanngasse 5, 1090, Vienna, Austria.
| |
Collapse
|
28
|
Ziatdinov M, Dyck O, Li X, Sumpter BG, Jesse S, Vasudevan RK, Kalinin SV. Building and exploring libraries of atomic defects in graphene: Scanning transmission electron and scanning tunneling microscopy study. SCIENCE ADVANCES 2019; 5:eaaw8989. [PMID: 31598551 PMCID: PMC6764837 DOI: 10.1126/sciadv.aaw8989] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/04/2019] [Indexed: 05/24/2023]
Abstract
The presence and configurations of defects are primary components determining materials functionality. Their population and distribution are often nonergodic and dependent on synthesis history, and therefore rarely amenable to direct theoretical prediction. Here, dynamic electron beam-induced transformations in Si deposited on a graphene monolayer are used to create libraries of possible Si and carbon vacancy defects. Deep learning networks are developed for automated image analysis and recognition of the defects, creating a library of (meta) stable defect configurations. Density functional theory is used to estimate atomically resolved scanning tunneling microscopy (STM) signatures of the classified defects from the created library, allowing identification of several defect types across imaging platforms. This approach allows automatic creation of defect libraries in solids, exploring the metastable configurations always present in real materials, and correlative studies with other atomically resolved techniques, providing comprehensive insight into defect functionalities.
Collapse
Affiliation(s)
- Maxim Ziatdinov
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Ondrej Dyck
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Xin Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Bobby G. Sumpter
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Stephen Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Rama K. Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Sergei V. Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| |
Collapse
|
29
|
Qian Q, Wu AX, Chi WS, Asinger PA, Lin S, Hypsher A, Smith ZP. Mixed-Matrix Membranes Formed from Imide-Functionalized UiO-66-NH 2 for Improved Interfacial Compatibility. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31257-31269. [PMID: 31362491 PMCID: PMC6727620 DOI: 10.1021/acsami.9b07500] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/31/2019] [Indexed: 05/31/2023]
Abstract
Mixed-matrix membranes (MMMs) formed by dispersing metal-organic framework (MOF) particles in polymers have attracted significant attention because these composite systems can potentially surpass the separation performance of pure polymers alone. However, performance improvements are often unrealized because of poor interfacial compatibility between the MOF and the polymer, which results in interfacial defects. From a practical perspective, strategies are needed to address these defects so that MMMs can be deployed in real-world separation processes. From a fundamental perspective, strategies are needed to reliably form defect-free MMMs so that transport models can be applied to estimate pure MOF property sets, thereby enabling the development of robust structure-property relationships. To address these interfacial challenges, we have developed a method to surface-functionalize a UiO-66-NH2 MOF with a nanoscopic shell of covalently tethered 4,4'-(hexafluoroisopropylidene)diphthalic anhydride-Durene oligomers. When combined with a high-molecular-weight polymer of identical chemical structure to that of the imide-functional MOF surface, defect-free MMMs with uniform particle dispersions can be formed. With this technique, both permeabilities and selectivities of select gases in the MMMs were improved at loadings ranging from 5 to 40 wt %. At a 40 wt % loading, CO2 permeability and CO2/CH4 selectivity were enhanced by 48 and 15%, respectively. Additionally, pure MOF permeabilities for H2, N2, O2, CH4, and CO2 were predicted by the Maxwell model.
Collapse
|
30
|
Qiu Y, Wen Z, Jiang C, Wu X, Si R, Bao J, Zhang Q, Gu L, Tang J, Guo X. Rational Design of Atomic Layers of Pt Anchored on Mo 2 C Nanorods for Efficient Hydrogen Evolution over a Wide pH Range. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900014. [PMID: 30838758 DOI: 10.1002/smll.201900014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/14/2019] [Indexed: 06/09/2023]
Abstract
Transition metal carbide compound has been extensively investigated as a catalyst for hydrogenation, for example, due to its noble metal-like properties. Herein a facile synthetic strategy is applied to control the thickness of atomic-layer Pt clusters strongly anchored on N-doped Mo2 C nanorods (Pt/N-Mo2 C) and it is found that the Pt atomic layers modify Mo2 C function as a high-performance and robust catalyst for hydrogen evolution. The optimized 1.08 wt% Pt/N-Mo2 C exhibits 25-fold, 10-fold, and 15-fold better mass activity than the benchmark 20 wt% Pt/C in neutral, acidic, and alkaline media, respectively. This catalyst also represents an extremely low overpotential of -8.3 mV at current density of 10 mA cm-2 , much better than the majority of reported electrocatalysts and even the commercial reference catalyst (20 wt%) Pt/C. Furthermore, it exhibits an outstanding long-term operational durability of 120 h. Theoretical calculation predicts that the ultrathin layer of Pt clusters on Mo-Mo2 C yields the lowest absolute value of ΔGH* . Experimental results demonstrate that the atomic layer of Pt clusters anchored on Mo2 C substrate greatly enhances electron and mass transportation efficiency and structural stability. These findings could provide the foundation for developing highly effective and scalable hydrogen evolution catalysts.
Collapse
Affiliation(s)
- Yu Qiu
- Key Lab of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, and the College of Chemistry and Materials Science of Northwest University, Xi'an, 710069, P. R. China
| | - Zhilin Wen
- Hefei National Laboratory of Physical Sciences at the Microscale, School of Chemistry of Materials Sciences, Synergetic Innovation of Quantum Information & Quantum Technology, CAS Key Lab of Materials for Energy Conversion, and CAS Excellent Center in Nanoscience, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Chaoran Jiang
- Department of Chemical Engineering, UCL, Torrington Place, London, WC1E 7JE, UK
| | - Xiaojun Wu
- Hefei National Laboratory of Physical Sciences at the Microscale, School of Chemistry of Materials Sciences, Synergetic Innovation of Quantum Information & Quantum Technology, CAS Key Lab of Materials for Energy Conversion, and CAS Excellent Center in Nanoscience, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Rui Si
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai, 201800, P. R. China
| | - Jun Bao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Qinghua Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Lin Gu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Junwang Tang
- Department of Chemical Engineering, UCL, Torrington Place, London, WC1E 7JE, UK
| | - Xiaohui Guo
- Key Lab of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, and the College of Chemistry and Materials Science of Northwest University, Xi'an, 710069, P. R. China
| |
Collapse
|
31
|
Yang SZ, Sun W, Zhang YY, Gong Y, Oxley MP, Lupini AR, Ajayan PM, Chisholm MF, Pantelides ST, Zhou W. Direct Cation Exchange in Monolayer MoS_{2} via Recombination-Enhanced Migration. PHYSICAL REVIEW LETTERS 2019; 122:106101. [PMID: 30932633 DOI: 10.1103/physrevlett.122.106101] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 12/04/2018] [Indexed: 06/09/2023]
Abstract
In addition to their unique optical and electronic properties, two-dimensional materials provide opportunities to directly observe atomic-scale defect dynamics. Here we use scanning transmission electron microscopy to observe substitutional Re impurities in monolayer MoS_{2} undergo direct exchanges with neighboring Mo atoms in the lattice. Density-functional-theory calculations find that the energy barrier for direct exchange, a process that has only been studied as a diffusion mechanism in bulk materials, is too large for either thermal activation or energy directly transferred from the electron beam. The presence of multiple sulfur vacancies next to the exchanged Re-Mo pair, as observed by electron microscopy, does not lower the energy barrier sufficiently to account for the observed atomic exchange. Instead, the calculations find that a Re dopant and surrounding sulfur vacancies introduce an ever-changing set of deep levels in the energy gap. We propose that these levels mediate an "explosive" recombination-enhanced migration via multiple electron-hole recombination events. As a proof of concept, we also show that Re-Mo direct exchange can be triggered via controlled creation of sulfur vacancies. The present experimental and theoretical findings lay a fundamental framework towards manipulating single substitutional dopants in two-dimensional materials.
Collapse
Affiliation(s)
- Shi-Ze Yang
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Weiwei Sun
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Yu-Yang Zhang
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
- School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongji Gong
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Mark P Oxley
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Andrew R Lupini
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Pulickel M Ajayan
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Matthew F Chisholm
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sokrates T Pantelides
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
- School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wu Zhou
- Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
32
|
Composition determination of semiconductor alloys towards atomic accuracy by HAADF-STEM. Ultramicroscopy 2019; 200:84-96. [PMID: 30844539 DOI: 10.1016/j.ultramic.2019.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 12/21/2018] [Accepted: 02/12/2019] [Indexed: 11/23/2022]
Abstract
This paper presents a comprehensive investigation of an extended method to determine composition of materials by scanning transmission electron microscopy (STEM) high angle annular darkfield (HAADF) images and using complementary multislice simulations. The main point is to understand the theoretical capabilities of the algorithm and address the intrinsic limitations of using STEM HAADF intensities for composition determination. A special focus is the potential of the method regarding single-atom accuracy. All-important experimental parameters are included into the multislice simulations to ensure the best possible fit between simulation and experiment. To demonstrate the capabilities of the extended method, results for three different technical important semiconductor samples are presented. Overall the method shows a high lateral resolution combined with a high accuracy towards single-atom accuracy.
Collapse
|
33
|
Song J, Allen CS, Gao S, Huang C, Sawada H, Pan X, Warner J, Wang P, Kirkland AI. Atomic Resolution Defocused Electron Ptychography at Low Dose with a Fast, Direct Electron Detector. Sci Rep 2019; 9:3919. [PMID: 30850641 PMCID: PMC6408533 DOI: 10.1038/s41598-019-40413-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 02/14/2019] [Indexed: 01/16/2023] Open
Abstract
Electron ptychography has recently attracted considerable interest for high resolution phase-sensitive imaging. However, to date studies have been mainly limited to radiation resistant samples as the electron dose required to record a ptychographic dataset is too high for use with beam-sensitive materials. Here we report defocused electron ptychography using a fast, direct-counting detector to reconstruct the transmission function, which is in turn related to the electrostatic potential of a two-dimensional material at atomic resolution under various low dose conditions.
Collapse
Affiliation(s)
- Jiamei Song
- College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Christopher S Allen
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.,Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd., Didcot, OX11 0DE, UK
| | - Si Gao
- College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Chen Huang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.,Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd., Didcot, OX11 0DE, UK
| | - Hidetaka Sawada
- JEOL Ltd, 1-2 Mushashino, 3-Chome, Akishima, Tokyo, 196, Japan
| | - Xiaoqing Pan
- Department of Materials Science and Engineering, and Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Jamie Warner
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Peng Wang
- College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210093, People's Republic of China.
| | - Angus I Kirkland
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.,Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd., Didcot, OX11 0DE, UK
| |
Collapse
|
34
|
Jeong JS, Song H, Held JT, Mkhoyan KA. Subatomic Channeling and Helicon-Type Beams in SrTiO_{3}. PHYSICAL REVIEW LETTERS 2019; 122:075501. [PMID: 30848623 DOI: 10.1103/physrevlett.122.075501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/28/2018] [Indexed: 06/09/2023]
Abstract
Inspired by recent experimental subatomic measurements using analytical aberration-corrected scanning transmission electron microscopes, we study electron probe propagation in crystalline SrTiO_{3} at the subatomic length scale. Here, we report the existence of subatomic channeling and the formation of a helicon-type beam at this scale. The results of beam propagation simulations, which are performed at various crystal temperatures, STEM probe convergence angles (10-50 mrad), and beam energies (80-300 keV), showed that reducing the ambient temperature can enhance the subatomic channeling and STEM probe parameters can be used to control the features of helicon-type beams.
Collapse
Affiliation(s)
- Jong Seok Jeong
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Hosup Song
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Jacob T Held
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - K Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| |
Collapse
|
35
|
Susi T, Madsen J, Ludacka U, Mortensen JJ, Pennycook TJ, Lee Z, Kotakoski J, Kaiser U, Meyer JC. Efficient first principles simulation of electron scattering factors for transmission electron microscopy. Ultramicroscopy 2019; 197:16-22. [DOI: 10.1016/j.ultramic.2018.11.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/29/2018] [Accepted: 11/06/2018] [Indexed: 11/25/2022]
|
36
|
|
37
|
Zhao X, Ning S, Fu W, Pennycook SJ, Loh KP. Differentiating Polymorphs in Molybdenum Disulfide via Electron Microscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802397. [PMID: 30160317 DOI: 10.1002/adma.201802397] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 05/31/2018] [Indexed: 06/08/2023]
Abstract
The presence of rich polymorphs and stacking polytypes in molybdenum disulfide (MoS2 ) endows it with a diverse range of electrical, catalytic, optical, and magnetic properties. This has stimulated a lot of interest in the unique properties associated with each polymorph. Most techniques used for polymorph identification in MoS2 are macroscopic techniques that sample averaged properties due to their limited spatial resolution. A reliable way of differentiating the atomic structure of different polymorphs is needed in order to understand their growth dynamics and establish the correlation between structure and properties. Herein, the use of electron microscopy for identifying the atomic structures of several important polymorphs in MoS2 , some of which are the subjects of mistaken assignment in the literature, is discussed. In particular, scanning transmission electron microscopy-annular dark field imaging has emerged as the most effective and reliable approach for identifying the different phases in MoS2 and other 2D materials because its images can be directly correlated to the atomic structures. Examples of the identification of polymorphs grown under different conditions in molecular beam epitaxy or chemical vapor deposition, for example, 3R, 1T, 1T'-phases, and 1T'-edges, are presented, including their atomic structures, fascinating properties, growth methods, and corresponding thermodynamic stabilities.
Collapse
Affiliation(s)
- Xiaoxu Zhao
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, 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
| | - Shoucong Ning
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore
| | - Wei Fu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - 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, 117543, 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
| |
Collapse
|
38
|
Song B, Ding Z, Allen CS, Sawada H, Zhang F, Pan X, Warner J, Kirkland AI, Wang P. Hollow Electron Ptychographic Diffractive Imaging. PHYSICAL REVIEW LETTERS 2018; 121:146101. [PMID: 30339441 DOI: 10.1103/physrevlett.121.146101] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Indexed: 06/08/2023]
Abstract
We report a method for quantitative phase recovery and simultaneous electron energy loss spectroscopy analysis using ptychographic reconstruction of a data set of "hollow" diffraction patterns. This has the potential for recovering both structural and chemical information at atomic resolution with a new generation of detectors.
Collapse
Affiliation(s)
- Biying Song
- National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Zhiyuan Ding
- National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Christopher S Allen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Centre, Diamond Lightsource Ltd., Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Hidetaka Sawada
- JEOL Ltd, 1-2 Musashino, 3-Chome, Akishima, Tokyo 196, Japan
| | - Fucai Zhang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Xiaoqing Pan
- Department of Chemical Engineering and Materials Science and Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Jamie Warner
- 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 Centre, Diamond Lightsource Ltd., Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Peng Wang
- National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| |
Collapse
|
39
|
Sánchez-Santolino G, Lugg NR, Seki T, Ishikawa R, Findlay SD, Kohno Y, Kanitani Y, Tanaka S, Tomiya S, Ikuhara Y, Shibata N. Probing the Internal Atomic Charge Density Distributions in Real Space. ACS NANO 2018; 12:8875-8881. [PMID: 30074756 DOI: 10.1021/acsnano.8b03712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Probing the charge density distributions in materials at atomic scale remains an extremely demanding task, particularly in real space. However, recent advances in differential phase contrast-scanning transmission electron microscopy (DPC-STEM) bring this possibility closer by directly visualizing the atomic electric field. DPC-STEM at atomic resolutions measures how a sub-angstrom electron probe passing through a material is affected by the atomic electric field, the field between the nucleus and the surrounding electrons. Here, we perform a fully quantitative analysis which allows us to probe the charge density distributions inside atoms, including both the positive nuclear and the screening electronic charges, with subatomic resolution and in real space. By combining state-of-the-art DPC-STEM experiments with advanced electron scattering simulations we are able to map the spatial distribution of the electron cloud within individual atomic columns. This work constitutes a crucial step toward the direct atomic scale determination of the local charge redistributions and modulations taking place in materials systems.
Collapse
Affiliation(s)
- Gabriel Sánchez-Santolino
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Nathan R Lugg
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Takehito Seki
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Ryo Ishikawa
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Scott D Findlay
- School of Physics and Astronomy , Monash University , Clayton , Victoria 3800 , Australia
| | - Yuji Kohno
- Electron Optics Division JEOL Limited, Tokyo 196-8558 , Japan
| | - Yuya Kanitani
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Shinji Tanaka
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Shigetaka Tomiya
- Advanced Technology Research Division, SONY Corporation, 4-14-1, Asahi , Atsugi-shi , Kanagawa 243-0014 , Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno , Atsuta-ku, Nagoya 456-8587 , Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, School of Engineering , The University of Tokyo , 2-11-16 Yayoi , Bunkyo-ku, Tokyo 113-8656 , Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, 2-4-1 Mutsuno , Atsuta-ku, Nagoya 456-8587 , Japan
| |
Collapse
|
40
|
Hachtel JA, Idrobo JC, Chi M. Sub-Ångstrom electric field measurements on a universal detector in a scanning transmission electron microscope. ADVANCED STRUCTURAL AND CHEMICAL IMAGING 2018; 4:10. [PMID: 30221126 PMCID: PMC6132373 DOI: 10.1186/s40679-018-0059-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 08/09/2018] [Indexed: 11/25/2022]
Abstract
Scanning transmission electron microscopy (STEM) excels in accessing atomic-scale structure and chemistry. Enhancing our ability to directly image the functionalities of local features in materials has become one of the most important topics in the future development of STEM. Recently, differential phase contrast (DPC) imaging has been utilized to map the internal electric and magnetic fields in materials from nanoscale features such as p-n junctions, skyrmions, and even from individual atoms. Here, we use an ultra-low noise SCMOS detector in as the diffraction plane camera to collect four-dimensional (4D) datasets. The high angular resolution, efficient high-SNR acquisition, and modifiability of the camera allow it to function as a universal detector, where STEM imaging configurations, such as DPC, bright field, annular bright field, and annular dark field can all be reconstructed from a single 4D dataset. By examining a distorted perovskite, DyScO3, which possesses projected lattice spacings as small as 0.83 Å, we demonstrate DPC spatial resolution almost reaching the information limit of a 100 keV electron beam. In addition, the perovskite has ordered O-coordinations with alternating octahedral tilts, which can be quantitatively measured with single degree accuracy by taking advantage of DPC's sensitivity to light atoms. The results, acquired on a standard Ronchigram camera as opposed to a specialized DPC detector, open up new opportunities to understand and design functional materials and devices that involve lattice and charge coupling at nano- and atomic-scales.
Collapse
Affiliation(s)
- 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
| |
Collapse
|
41
|
Exploring the capabilities of monochromated electron energy loss spectroscopy in the infrared regime. Sci Rep 2018; 8:5637. [PMID: 29618757 PMCID: PMC5884780 DOI: 10.1038/s41598-018-23805-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 03/19/2018] [Indexed: 11/09/2022] Open
Abstract
Monochromated electron energy loss spectroscopy (EELS) is one of the leading techniques to study materials properties that correspond to low (<5 eV) energy losses (i.e. band-gaps, plasmons, and excitons) with nanoscale spatial resolution. Recently a new generation of monochromators have become available, opening regimes and unlocking excitations that were previously unobservable in the electron microscope. The capabilities of these new instruments are still being explored, and here we study the effect of monochromation on various aspects of EELS analysis in the infrared (<1 eV) regime. We investigate the effect of varying levels of monochromation on energy resolution, zero-loss peak (ZLP) tail reduction, ZLP tail shape, signal-to-noise-ratio, and spatial resolution. From these experiments, the new capabilities of monochromated EELS are shown to be highly promising for the future of localized spectroscopic analysis.
Collapse
|
42
|
de Jonge N. Theory of the spatial resolution of (scanning) transmission electron microscopy in liquid water or ice layers. Ultramicroscopy 2018; 187:113-125. [DOI: 10.1016/j.ultramic.2018.01.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/02/2018] [Accepted: 01/17/2018] [Indexed: 01/29/2023]
|
43
|
Xin P, Li J, Xiong Y, Wu X, Dong J, Chen W, Wang Y, Gu L, Luo J, Rong H, Chen C, Peng Q, Wang D, Li Y. Revealing the Active Species for Aerobic Alcohol Oxidation by Using Uniform Supported Palladium Catalysts. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201801103] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Pingyu Xin
- Department of Chemistry Tsinghua University Beijing 100084 China
| | - Jia Li
- Institute of Advanced Materials, Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China
| | - Yu Xiong
- Department of Chemistry Tsinghua University Beijing 100084 China
- College of Chemistry and Chemical Engineering Central South University Hunan 410083 China
| | - Xi Wu
- Institute of Advanced Materials, Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China
| | - Juncai Dong
- Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences China
| | - Wenxing Chen
- Department of Chemistry Tsinghua University Beijing 100084 China
| | - Yu Wang
- Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Science Shanghai 100049 China
| | - Lin Gu
- Institute of Physics Chinese Academy of Science Beijing 100190 China
| | - Jun Luo
- Center for Electron Microscopy Tianjin University of Technology Tianjin 300384 China
| | - Hongpan Rong
- Department of Chemistry Tsinghua University Beijing 100084 China
| | - Chen Chen
- Department of Chemistry Tsinghua University Beijing 100084 China
| | - Qing Peng
- 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
| |
Collapse
|
44
|
Xin P, Li J, Xiong Y, Wu X, Dong J, Chen W, Wang Y, Gu L, Luo J, Rong H, Chen C, Peng Q, Wang D, Li Y. Revealing the Active Species for Aerobic Alcohol Oxidation by Using Uniform Supported Palladium Catalysts. Angew Chem Int Ed Engl 2018; 57:4642-4646. [DOI: 10.1002/anie.201801103] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Pingyu Xin
- Department of Chemistry; Tsinghua University; Beijing 100084 China
| | - Jia Li
- Institute of Advanced Materials, Graduate School at Shenzhen; Tsinghua University; Shenzhen 518055 China
| | - Yu Xiong
- Department of Chemistry; Tsinghua University; Beijing 100084 China
- College of Chemistry and Chemical Engineering; Central South University; Hunan 410083 China
| | - Xi Wu
- Institute of Advanced Materials, Graduate School at Shenzhen; Tsinghua University; Shenzhen 518055 China
| | - Juncai Dong
- Beijing Synchrotron Radiation Facility; Institute of High Energy Physics; Chinese Academy of Sciences; China
| | - Wenxing Chen
- Department of Chemistry; Tsinghua University; Beijing 100084 China
| | - Yu Wang
- Shanghai Synchrotron Radiation Facility; Shanghai Institute of Applied Physics; Chinese Academy of Science; Shanghai 100049 China
| | - Lin Gu
- Institute of Physics; Chinese Academy of Science; Beijing 100190 China
| | - Jun Luo
- Center for Electron Microscopy; Tianjin University of Technology; Tianjin 300384 China
| | - Hongpan Rong
- Department of Chemistry; Tsinghua University; Beijing 100084 China
| | - Chen Chen
- Department of Chemistry; Tsinghua University; Beijing 100084 China
| | - Qing Peng
- 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
| |
Collapse
|
45
|
Morishita S, Ishikawa R, Kohno Y, Sawada H, Shibata N, Ikuhara Y. Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector. Microscopy (Oxf) 2018; 67:46-50. [PMID: 29309606 DOI: 10.1093/jmicro/dfx122] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/25/2017] [Indexed: 11/13/2022] Open
Abstract
The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga-Ga atomic columns of GaN observed along [212] direction.
Collapse
Affiliation(s)
| | - Ryo Ishikawa
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
| | - Yuji Kohno
- JEOL Ltd, 3-1-2 Musashino, Akishima, Tokyo196-8558, Japan
| | | | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo113-8656, Japan
| |
Collapse
|
46
|
de Jonge N, Verch A, Demers H. The Influence of Beam Broadening on the Spatial Resolution of Annular Dark Field Scanning Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:8-16. [PMID: 29485023 DOI: 10.1017/s1431927618000077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The spatial resolution of aberration-corrected annular dark field scanning transmission electron microscopy was studied as function of the vertical position z within a sample. The samples consisted of gold nanoparticles (AuNPs) positioned in different horizontal layers within aluminum matrices of 0.6 and 1.0 µm thickness. The highest resolution was achieved in the top layer, whereas the resolution was reduced by beam broadening for AuNPs deeper in the sample. To examine the influence of the beam broadening, the intensity profiles of line scans over nanoparticles at a certain vertical location were analyzed. The experimental data were compared with Monte Carlo simulations that accurately matched the data. The spatial resolution was also calculated using three different theoretical models of the beam blurring as function of the vertical position within the sample. One model considered beam blurring to occur as a single scattering event but was found to be inaccurate for larger depths of the AuNPs in the sample. Two models were adapted and evaluated that include estimates for multiple scattering, and these described the data with sufficient accuracy to be able to predict the resolution. The beam broadening depended on z 1.5 in all three models.
Collapse
Affiliation(s)
- Niels de Jonge
- 1INM-Leibniz Institute for New Materials,66123 Saarbrücken,Germany
| | - Andreas Verch
- 1INM-Leibniz Institute for New Materials,66123 Saarbrücken,Germany
| | - Hendrix Demers
- 3Department of Materials Engineering,McGill University,Montreal,QC H3A 0C5,Canada
| |
Collapse
|
47
|
Thomas JM. Providing sustainable catalytic solutions for a rapidly changing world: a summary and recommendations for urgent future action. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0068. [PMID: 29175987 DOI: 10.1098/rsta.2017.0068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/16/2017] [Indexed: 06/07/2023]
Abstract
In addition to summarizing the main thrusts of each paper presented at this Discussion, other urgent issues involving the role (and characterization) of new catalysts for eliminating oxides of nitrogen, for using CO2 liberated from steel mills, for fuel cells and the need for rapid decarbonization of fossil fuels are outlined.This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.
Collapse
Affiliation(s)
- John Meurig Thomas
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK
| |
Collapse
|
48
|
Liu Y, Wang YJ, Zhu YL, Lei CH, Tang YL, Li S, Zhang SR, Li J, Ma XL. Large Scale Two-Dimensional Flux-Closure Domain Arrays in Oxide Multilayers and Their Controlled Growth. NANO LETTERS 2017; 17:7258-7266. [PMID: 29125773 DOI: 10.1021/acs.nanolett.7b02615] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ferroelectric flux-closures are very promising in high-density storage and other nanoscale electronic devices. To make the data bits addressable, the nanoscale flux-closures are required to be periodic via a controlled growth. Although flux-closure quadrant arrays with 180° domain walls perpendicular to the interfaces (V-closure) have been observed in strained ferroelectric PbTiO3 films, the flux-closure quadrants therein are rather asymmetric. In this work, we report not only a periodic array of the symmetric flux-closure quadrants with 180° domain walls parallel to the interfaces (H-closure) but also a large scale alternative stacking of the V- and H-closure arrays in PbTiO3/SrTiO3 multilayers. On the basis of a combination of aberration-corrected scanning transmission electron microscopic imaging and phase field modeling, we establish the phase diagram in the layer-by-layer two-dimensional arrays versus the thickness ratio of adjacent PbTiO3 films, in which energy competitions play dominant roles. The manipulation of these flux-closures may stimulate the design and development of novel nanoscale ferroelectric devices with exotic properties.
Collapse
Affiliation(s)
- Ying Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Yu-Jia Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Yin-Lian Zhu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Chi-Hou Lei
- Department of Aerospace and Mechanical Engineering, Saint Louis University , Saint Louis, Missouri 63103-1110, United States
| | - Yun-Long Tang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Shuang Li
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Si-Rui Zhang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
| | - Jiangyu Li
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , University Town of Shenzhen, Shenzhen, Guangdong 518055, China
- Department of Mechanical Engineering, University of Washington , Seattle, Washington 98195-2600, United States
| | - Xiu-Liang Ma
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China
- School of Materials Science and Engineering, Lanzhou University of Technology , 730050 Lanzhou, China
| |
Collapse
|
49
|
Choudhuri D, Srinivasan SG, Gibson MA, Zheng Y, Jaeger DL, Fraser HL, Banerjee R. Exceptional increase in the creep life of magnesium rare-earth alloys due to localized bond stiffening. Nat Commun 2017; 8:2000. [PMID: 29222427 PMCID: PMC5722870 DOI: 10.1038/s41467-017-02112-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 11/07/2017] [Indexed: 11/25/2022] Open
Abstract
Several recent papers report spectacular, and unexpected, order of magnitude improvement in creep life of alloys upon adding small amounts of elements like zinc. This microalloying effect raises fundamental questions regarding creep deformation mechanisms. Here, using atomic-scale characterization and first principles calculations, we attribute the 600% increase in creep life in a prototypical Mg-rare earth (RE)-Zn alloy to multiple mechanisms caused by RE-Zn bonding-stabilization of a large volume fraction of strengthening precipitates on slip planes, increase in vacancy diffusion barrier, reduction in activated cross-slip, and enhancement of covalent character and bond strength around Zn solutes along the c-axis of Mg. We report that increased vacancy diffusion barrier, which correlates with the observed 25% increase in interplanar bond stiffness, primarily enhances the high-temperature creep life. Thus, we demonstrate that an approach of local, randomized tailoring of bond stiffness via microalloying enhances creep performance of alloys.
Collapse
Affiliation(s)
- Deep Choudhuri
- Department of Materials Science and Engineering, University of North Texas, Denton, TX, 76201, USA.
- Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton, TX, 76207, USA.
| | | | - Mark A Gibson
- CSIRO Manufacturing, Private Bag 10, Clayton South, Clayton, VIC, 3169, Australia
- School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, VIC, 3053, Australia
- Department of Materials Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Yufeng Zheng
- Center for Accelerated Maturation of Materials, Department of Materials Science and Engineering, The Ohio State University, Columbus, 43210, OH, USA
| | - David L Jaeger
- Materials Research Facility, University of North Texas, Denton, TX, 76201, USA
| | - Hamish L Fraser
- Center for Accelerated Maturation of Materials, Department of Materials Science and Engineering, The Ohio State University, Columbus, 43210, OH, USA
| | - Rajarshi Banerjee
- Department of Materials Science and Engineering, University of North Texas, Denton, TX, 76201, USA.
- Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton, TX, 76207, USA.
- Materials Research Facility, University of North Texas, Denton, TX, 76201, USA.
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore.
| |
Collapse
|
50
|
Mizoguchi T, Miyata T, Olovsson W. Excitonic, vibrational, and van der Waals interactions in electron energy loss spectroscopy. Ultramicroscopy 2017; 180:93-103. [DOI: 10.1016/j.ultramic.2017.03.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/21/2017] [Accepted: 03/01/2017] [Indexed: 11/16/2022]
|