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DMPFIT: A Tool for Atomic-Scale Metrology via Nonlinear Least-Squares Fitting of Peaks in Atomic-Resolution TEM Images

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Nanomanufacturing and Metrology 2022年第2期5卷 101-111页

作者： Hongchu Du ernst ruska-Centre for microscopy and spectroscopy with electrons(ER-C2) Forschungszentrum Juelich GmbH52428JülichGermany Central Facility for Electron microscopy(GFE) RWTH Aachen University52074AachenGermany

Despite the wide availability and usage of Gatan’s DigitalMicrograph software in the electron microscopy community for image recording and analysis, nonlinear least-squares fitting in DigitalMicrograph is less straightforward. This work presents a ready-to-use tool, the DMPFIT software package, written in DigitalMicrograph script and C++ language, for nonlinear least-squares fitting of the intensity distribution of atomic columns in atomic-resolution transmission electron microscopy (TEM) images with a general two-dimensional (2D) Gaussian model. Applications of the DMPFIT software are demonstrated both in atomic-resolution conventional coherent TEM (CTEM) images recorded by the negative spherical aberration imaging technique and in high angle annular dark field (HAADF) scanning TEM (STEM) images. The implemented peak-finding algorithm based on the periodicity of 2D lattices enables reliable and convenient atomic-scale metrology as well as intuitive presentation of the resolved atomic structures.

关键词： Quantitative TEM Nonlinear least-squares fitting Image quantification Image analysis Atomic-scale metrology

Atomic-scale investigation of spinel Li Fe5O8 thin films on SrTiO3(001) substrates

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Journal of Materials Science & Technology 2020年第5期40卷 31-38页

作者： Kun Liu Ruyi Zhang Lu Lu Shaobo Mi Ming Liu Hong Wang Shengqiang Wu Chunlin Jia State Key Laboratory for Mechanical Behavior of Materials&School of Microelectronics Xi’an Jiaotong UniversityXi’an 710049China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China ernst ruska center for microscopy and spectroscopy with electrons Forschungszentrum Jülich52425 JülichGermany

Microstructural properties of spinel Li Fe5O8(LFO)films grown on(001)-oriented Sr TiO3(STO)substrates have been investigated at the atomic-scale by advanced electron microscopy *** types of orientation relationship(OR)between the LFO films and the STO substrates have been determined,cube-on-cube and(111)[ī10]LFO//(111)[1ī0]*** boundaries(APBs)and three types of twin boundaries(TBs)form within the LFO films,and the propagation of TBs and APBs results in their complex *** most cases,interactions between TBs and APBs change the type of TBs and terminate the propagation of APBs since the APBs introduce a displacement vector of(a/4)110 into the *** addition,the interactions between two coherent TBs are observed to generate the incoherent *** epitaxial strain of the LFO/STO(001)heterosystem can be released by the formation of TBs and APBs in the films and misfit dislocations at the *** that the magnetic coupling across the APBs and TBs can lead to novel physical properties,the appearance of APBs and TBs with a high density in the LFO films would affect the magnetic properties of the films.

关键词： Lithium ferrite Twin boundaries Antiphase boundaries Interactions Electron microscopy

Quantitative HRTEM and its application in the study of oxide materials

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Chinese Physics B 2018年第5期27卷 22-32页

作者： Chun-Lin Jia[[ Shao-Bo Mi Lei Jin ernst ruska-Centre (ER-C) for microscopy and spectroscopy with electrons Forschungszentrum Julich GmbH 52425 Julich Germany School of Microelectronics Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory for Mechanical Behaviour of Materials Xi'an Jiaotong University Xi'an 710049 China

On the basis of a state-of-the-art aberration-corrected transmission electron microscope, the spherical aberration coefficient CSof the objective lens can be tuned to either a positive or a negative value. The use of a negative value of CS combined with an overfocus setting of the objective lens leads to the development of the negative CSimaging（NCSI） technique. Images obtained using the NCSI technique show superior contrast and signal intensity at atomic column positions than the corresponding positive CSimages, especially for weakly scattering oxygen columns that are in close proximity to strongly scattering cation columns in oxides. Based on the images obtained under the NCSI condition, quantification of the image contrast allows measurements of the atom positions with a precision of a few picometers and the local chemistry on atomic scale. In the present review, we discuss firstly the benefits of the NCSI technique in studies of oxide materials,and then show a procedure for quantitative analysis of the image based on the absolute value of contrast. In the last part,examples are given for the application of the quantitative high-resolution transmission electron microscopy（HRTEM） to the study of electric dipoles of oxide ferroelectrics and atomic-scale chemistry of interfaces.

关键词： quantitative high-resolution transmission electron microscopy (HRTEM) negative Cs imaging(NCSI) aberration-correction functional oxides

Structural and Electronic Properties of BaO/MgO(001)-type Interface Studied via Aberration-corrected Transmission Electron microscopy and First-principles Calculations

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Journal of Materials Science & Technology 2015年第2期31卷 205-209页

作者： Lei Deng Shaobo Mi Dong Chen Yuanming Wang Xiuliang Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences International center for Dielectric Research (ICDR) Xi'an Jiaotong University Institute of Solid State Research and ernst ruska Centre for microscopy and spectroscopy with electrons Forschungszentrum JülichJülich D-52425Germany

The properties of BaO/MgO-type interface in the BaZrO3/MgO(001) heterostructure are studied by aberrationcorrected high-resolution transmission electron microscopy combined with first-principles *** evidence demonstrates that cation displacement and vacancies occur at the interface. Our firstprinciple calculations show that cation displacement results from the electrostatic potential effect at the interface,and cation vacancies could lower the interfacial work of separation and enhance the interfacial stability of BaO/MgO-type interface. The results highlight that the effect of interfacial defects should be taken into account in understanding the film growth kinetics and properties in oxide heteroepitaxy.

关键词： Thin films Interface Transmission electron microsc

Twin crystal structured Al-10 wt.% Mg alloy over broad velocity conditions achieved by high thermal gradient directional solidification

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Journal of Materials Science & Technology 2021年第12期71卷 152-162页

作者： Luyan Yang Shuangming Li Kai Fan Yang Li Yanhui Chen Wei Li Deli Kong Pengfei Cao Haibo Long Ang Li Institute of Microstructure and Properties of Advanced Materials Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing100124China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China ernst ruska-Centre for microscopy and spectroscopy with electrons Forschungszentrum Jülich52428JülichGermany

Twin crystal structured Al-10 wt.% Mg alloys that were grown over a broad solidification velocity range were prepared and studied for the first *** high thermal gradient(G)and growth velocity(V)of directional solidification resulted in the dominant solidification of twins:the twinned dendrite trunks at constant high Vs curved in the G direction with large angles in 7 mm diameter crucibles and invaded regular columnar grains because of a distinct kinetics growth *** deceleration experiments were designed to produce twin crystals that evolved with lower values of V(100,10,and 0.5μm/s)and had a structural coarsening *** cell growth in the absence of arms occurred at a growth velocity of 10μm/s.A coherency loss was observed at a growth velocity of 0.5μm/s with straight coherent twin boundaries turning into curved incoherent *** theoretical analyses were performed to understand the structural evolution of the *** results demonstrate the possibility of producing dense and controlled twin crystals in the Al-Mg system under most industrial production conditions;thus,this approach can be a new structural choice for designing Al-Mg-based alloys that have widespread commercial applications.

关键词： Directional solidification Aluminum alloy Microstructural evolution Feathery crystals Twinned dendrites

Influences of perfluorooctanoic acid on the aggregation of multi-walled carbon nanotubes

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Journal of Environmental Sciences 2013年第3期25卷 466-472页

作者： Chengliang Li Andreas Schffer Harry Vereecken Marc Heggen Rong Ji Erwin Klumpp College of Resources and Environment Shandong Agricultural University National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources Biology 5-Environmental Biology and Chemodynamics RWTH Aachen University Agrosphere Institute (IBG-3) Forschungszentrum Jlich GmbH ernst ruska-Centre for microscopy and spectroscopy with electrons Forschungszentrum Jlich State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing University Institute for Climate and Global Change Research Nanjing University

The aggregation of multi-walled carbon nanotubes （MWCNTs） in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and *** role of surfactants at low concentration in the aggregation of MWCNTs has been studied,however the effect of perfluorinated surfactants at low concentration is *** understand this interfacial phenomenon,the influences of perfluorooctanoic acid （PFOA）,and sodium dodecyl sulfate （SDS） as a control,on MWCNT aggregation in the aqueous phase were examined by the UV absorbency *** of pH and cationic species on the critical coagulation concentration （CCC） value were *** CCC values were dependent on the concentration of PFOA,however a pronounced effect of SDS concentration on the CCC values was not *** CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl 2 solutions,which suggested pronounced differences in the effects of Na＋ and Ca2＋ ions on the aggregation of the *** presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl *** aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.

关键词： perfluorooctanoic acid aggregation multi-walled carbon nanotubes

The effect of Laves phases and nano-precipitates on the electrochemical corrosion resistance of Mg-Al-Ca alloys under alkaline conditions

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Journal of Magnesium and Alloys 2024年第6期12卷 2447-2461页

作者： Markus Felten Veronika Chaineux Siyuan Zhang Ali Tehranchi Tilmann Hickel Christina Scheu Joshua Spille Marta Lipińska-Chwałek Joachim Mayer Benjamin Berkels Marcus Hans Imke Greving Silja Flenner Sandra Sefa Daniela Zander Chair of Corrosion and Corrosion Protection RWTH Aachen UniversityAachen 52072 Germany Max-Planck-Institut für Eisenforschung GmbH Düsseldorf 40237 Germany Central Facility for Electron microscopy RWTH Aachen UniversityAachen 52074 Germany ernst ruska-Centre for microscopy and spectroscopy with electrons Forschungszentrum Jülich GmbHJülich 52428Germany Mathematical Image and Signal Processing Aachen Institute for Advanced Study in Computational Engineering ScienceRWTH Aachen UniversityAachen 52062 Germany Materials Chemistry RWTH Aachen UniversityAachen 52074 Germany Institute of Materials Physics Helmholtz-Zentrum HereonGeesthacht 21502 Germany

The electrochemical corrosion mechanisms of Mg alloys were extensively studied in previous investigations of different chemical com-positions,modified surface states and various electrolyte ***,recent research focused on the active state of Mg dissolution,leading to unresolved effects of secondary phases adjacent to a stableα-solid solution passive *** present study investigates the fundamental electrochemical corrosion mechanisms of three different Laves phases with varying phase morphologies and phase fractions in the passive state of Mg-Al-Ca *** microstructure was characterized by(transmission-)electron microscopy and synchrotron-based transmission X-ray *** electrochemical corrosion resistance was determined with a standard three-electrode setup and advanced in-situ flow cell measurements.A new electrochemical activity sequence(C15>C36>α-Mg>C14)was obtained,as a result of a stable passive layer formation on theα-solid ***,nm-scale Mg-rich precipitates were identified within the Laves phases,which tend to inhibit the corrosion kinetics.

关键词： Laves phase STEM Magnesium Corrosion Passive layer

Linear-regioselective hydromethoxycarbonylation of styrene using Ru-clusters/CeO2 catalyst

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Chinese Journal of Catalysis 2020年第6期41卷 963-969页

作者： Jinghua An Yehong Wang Zhixin Zhang Jian Zhang Martin Gocyla Rafal EDunin-Borkowski Feng Wang State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China ernst ruska Centre for microscopy and spectroscopy with electrons and Peter Grünberg Institute Forschungszentrum Juelich GmbHJuelich 52425Germany

Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters(L) and branched esters(B) is a challenging project for researchers working in this reaction. Although most of the attention has been paid to control the regioselectivity through ligand design in homogeneous catalytic systems, study in the area is still limited. Herein, Ru-clusters/CeO2 is employed as a heterogeneous catalyst for the hydromethoxycarbonylation of styrene without any additives. After optimization of the reaction conditions, the conversion of styrene is > 99% with 83% and 12% regioselectivity of linear and branched ester, respectively. By using different supports(CeO2(nanoparticle), CeO2-rod, and CeO2-cube), three catalysts including Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube are prepared and applied in the reaction. Structural characterizations demonstrate that the L/B ratio is related to the Ru size of supported Ru catalysts. Further Raman characterization and NH3-TPD demonstrate that the metal-support interaction and the concentration of oxygen vacancy of the catalyst have a great influence on the Ru size. The mechanism and kinetic analysis for this reaction are also investigated in this work.

关键词： Regioselectivity Ru-clusters/CeO2 Ester Hydromethoxycarbonylation Olefins Heterogeneous catalysis

Three-dimensional magnetization reconstruction from electron optical phase images with physical constraints

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 122-132页

作者： Boyao Lyu Shihua Zhao Yibo Zhang Weiwei Wang Fengshan Zheng Rafal E.Dunin-Borkowski Jiadong Zang Haifeng Du Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices High Magnetic Field LaboratoryHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Science Island Branch Graduate School of University of Science and Technology of ChinaHefei 230026China Department of Physics and Astronomy University of New HampshireDurham 03824USA Department of Physics The City College of New YorkNew York 10031USA Physics Program Graduate Center of the City University of New YorkNew York 10016USA Department of Chemistry University of New HampshireDurham 03824USA Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China Spin-X Institute Center for Electron MicroscopySchool of Physics and OptoelectronicsState Key Laboratory of Luminescent Materials and DevicesGuangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional MaterialsSouth China University of TechnologyGuangzhou 511442China ernst ruska-Centre for microscopy and spectroscopy with electrons Forschungszentrum JülichJülich 52425Germany

The ability to characterize three-dimensional(3D)magnetization distributions in nanoscale magnetic materials and devices is essential to fully understand their static and dynamic magnetic *** contrast techniques in the transmission electron microscope(TEM),such as electron holography and electron ptychography,can be used to record two-dimensional(2D)projections of the in-plane magnetic induction of 3D nanoscale *** the 3D magnetic induction can in principle be reconstructed from one or more tilt series of such 2D projections,conventional tomographic reconstruction algorithms do not recover the 3D magnetization within a sample ***,we use simulations to describe the basis of an improved model-based algorithm for the tomographic reconstruction of a 3D magnetization distribution from one or more tilt series of electron optical phase images recorded in the *** algorithm allows a wide range of physical constraints,including a priori information about the sample geometry and magnetic parameters,to be *** also makes use of minimization of the micromagnetic energy in the loss *** demonstrate the reconstruction of the 3D magnetization of a localized magnetic soliton—a hopfion ring—and discuss the influence of noise,choice of magnetic constants,maximum tilt angle and number of tilt axes on the *** algorithm can in principle be adapted for other magnetic contrast imaging techniques in the TEM,as well as for other magnetic characterization techniques,such as those based on X-rays or neutrons.

关键词： three-dimensional magnetization vector field tomography differentiable programming electron holography micromagnetism