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in situ tem observations and molecular dynamics simulations of deformation defect activities in Mg via nanoindentation

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Journal of Magnesium and Alloys 2023年第12期11卷 4513-4524页

作者： Yi-Cheng Lai Yubin Ying Digvijay Yadav Jose Guerrero Yong-Jie Hu Kelvin Y.Xie Department of Materials Science and Engineering Texas A&M UniversityCollege StationTX 77845USA Department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA 19104USA

In this work, we performed in situ nanoindentation in tem to capture the real-time dislocation and twinning activities in pure Mg during loading and unloading. We demonstrated that the screw component of dislocations glides continuously, while the edge components rapidly become sessile during loading. The twin tip propagation is intermittent, whereas the twin boundary migration is more continuous. During unloading, we observed the elastic strain relaxation causes both dislocation retraction and detwinning. Moreover,we note that the plastic zone comprised of dislocations in Mg is well-defined, which contrasts with the diffused plastic zones observed in face-centered cubic metals under the nanoindentation impressions. Additionally, molecular dynamics simulations were performed to study the formation and evolution of deformation-induced crystallographic defects at the early stages of indentation. We observed that,in addition to dislocations, the I1stacking fault bounded with a Frank loop can be generated from the plastic zone ahead of the indenter, and potentially serve as a nucleation source for abundant dislocations observed experimentally. These new findings are anticipated to provide new knowledge on the deformation mechanisms of Mg, which are difficult to obtain through conventional ex situ approaches. These observations may serve as a baseline for simulation work that investigate the dynamics of dislocation slip and twinning in Mg and alloys.

关键词： in situ tem Molecular dynamics simulation Dislocation Twinning Mg Nanoindentation

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Confining TiO_2 Nanotubes in PECVD-Enabled Graphene Capsules Toward Ultrafast K-Ion Storage: in situ tem/XRD Study and DFT Analysis

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Nano-Micro Letters 2020年第9期12卷 310-323页

作者： Jingsheng Cai Ran Cai Zhongti Sun Xiangguo Wang Nan Wei Feng Xu Yuanlong Shao Peng Gao Shixue Dou Jingyu Sun College of Energy Soochow Institute for Energy and Materials InnovationS(SIEMIS)Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou 215006JiangsuPeople’s Republic of China SEU‑FEI Nano‑Pico Center Key Laboratory of MEMS of Ministry of EducationSoutheast UniversityNanjing 210096People’s Republic of China Beijing Graphene Institute(BGI) Beijing 100095People’s Republic of China Electron Microscopy Laboratory International Centre for Quantum MaterialsSchool of PhysicsPeking UniversityBeijing 100871People’s Republic of China Institute for Superconducting and Electronic Materials University of WollongongWollongongNSW 2522Australia

Titanium dioxide(TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity,wide availability,and environmental benignity.Nevertheless,the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate capability.Here,we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor deposition.Such conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/depotassiation.When paired with an activated carbon cathode,the graphene-armored TiO2 nanotubes allow the potassium-ion hybrid capacitor full cells to harvest an energy/power density of 81.2 Wh kg-1/3746.6 W kg-1.We further employ in situ transmis sion electron microscopy and ope rando X-ray diffraction to probe the potassium-ion storage behavior.This work offers a viable and versatile solution to the anode design and in situ probing of potassium storage technologies that is readily promising for practical applications.

关键词： TiO2 Potassium storage in situ tem Plasma-enhanced CVD Graphene

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Exploration of Strong Metal-Support Interaction in Heterogeneous Catalysts by in situ Transmission Electron Microscopy

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Chinese Journal of Chemistry 2024年第9期42卷 1004-1008页

作者： Yongjun Jiang Sheng Dai Key Laboratoryfor Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center Institute of Fine ChemicalsSchool of Chemistry&Molecular EngineeringEast China Universityof Science and TechnologyShanghai 200237China

The phenomenon of strong metal-support interaction(SMSI)observed in supported metal catalysts,usually accompanied by the formation of the encapsulation layer on metal nanoparticles,has attracted extensive research attention due to its significance in heterogeneous catalysis.Notably,great progress has been made in recent years in investigating SMSI by in situ transmission electron microscopy(tem),along with an enhanced comprehension of the underlying mechanisms governing SMSI formation.This emerging topic summarizes recent progress utilizing in situ tem to study the interaction between metal and support and the relationship between the structure and performance of the supported catalyst under reaction conditions.A brief perspective about the use of in situ tem for further study of SMSI is also presented,showing prospects in this field that will stimulate further upsurging research in promoting the catalytic efficiency of supported catalysts.

关键词： Heterogeneous catalysis in situ tem Strong metal-support interaction Structure changes Interfaces Structural evolution

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Effects Associated with Nanostructure Fabrication Using In situ Liquid Cell tem Technology

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Nano-Micro Letters 2015年第4期7卷 385-391页

作者： Xin Chen Lihui Zhou Ping Wang Hongliang Cao Xiaoli Miao Feifei Wei Xia Chen Shanghai Key Laboratory of Advanced Polymeric Materials and Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and EngineeringEast China University of Science and Technology State Key Laboratory of Functional Materials for Informatic Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences East China University of Science and Technology State Key Laboratory of Bioreactor Engineering Biomedical Nanotechnology Center East China University of Science and Technology

We studied silicon,carbon,and SiC xnanostructures fabricated using liquid-phase electron-beam-induced deposition technology in transmission electron microscopy systems.Nanodots obtained from fixed electron beam irradiation followed a universal size versus beam dose trend,with precursor concentrations from pure Si Cl4to 0%SiC l4in CH2Cl2,and electron beam intensity ranges of two orders of magnitude,showing good controllability of the deposition.Secondary electrons contributed to the determination of the lateral sizes of the nanostructures,while the primary beam appeared to have an effect in reducing the vertical growth rate.These results can be used to generate donut-shaped nanostructures.Using a scanning electron beam,line structures with both branched and unbranched morphologies were also obtained.The liquid-phase electron-beaminduced deposition technology is shown to be an effective tool for advanced nanostructured material generation.

关键词： Electron-beam-induced deposition in situ tem Nanostrucutre Semiconductor Nanolithography

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Revealing the structure design of alloyed based electrodes for alkali metal ion batteries with in situ tem

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Journal of Energy Chemistry 2021年第8期30卷 405-418,I0009页

作者： Huawen Huang Ran Bi Jie Cui Ming-Ming Hu Li Tian Xianfeng Yang Lei Zhang School of Chemistry&Chemical Engineering Guangdong Provincial Key Laboratory of Advanced Energy Storage MaterialsSouth China University of TechnologyGuangzhou 510640China Analytical and Testing Centre South China University of TechnologyGuangzhou 510640China School of Materials Science and Engineering Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and ConversionHunan University of Science and TechnologyXiangtan 411201China

Alloyed based anode materials with high theoretical specific capacity and low reaction potential are considered to be highly potential high-energy density anode materials for alkali metal ion batteries(AMIBs).Thus,the design of alloyed based materials with high electrochemical performance has attracted great attention.Among the numerous characterization methods for guiding electrode materials design,in situ transmission electron microscopy(tem)gradually plays an irreplaceable role due to its high temporal and spatial resolution in directly observing the change of morphology,crystal structure and element evolutions.Herein,we reviewed the two current research hotspots and mainly focused on the structure design of alloyed based electrode material under the guidance of in situ tem.Specifically,various nanostructure designs of alloyed based electrode materials with guidance of in situ tem were employed to solve the key scientific issues of the violent volume change during alloying/dealloying processes for enhanced electrochemical performances.Mainly through introducing buffer space in the electrode material to reduce volume change to improve structural stability,including porous structure(0 D),nanotube structure(1 D),simple hollow structure,yolk-shell structure and some hybrid hollow structures(3 D).Furthermore,the direct guidance of in situ tem is expected for creating new opportunities to nextgeneration electrode material design for AMIBs.

关键词： in situ tem Alloyed based anode Nanostructure design Alkali metal ion batteries

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Influence of Annealing temperature on the Properties of TiO_2 Films Annealed by ex situ and in situ tem

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Journal of Wuhan University of Technology(Materials Science) 2012年第6期27卷 1014-1019页

作者：彭堂超 XIAO Xiangheng REN Feng XU Jinxia ZHOU Xiaodong MEI Fei 蒋昌忠 School of Physics and Technology Wuhan University Huazhong Institute of Electro-Optics-Wuhan National Laboratory for Optoelectronics School of Electrical&Electronic Engineer Hubei University of TechnologyWuhan 430068China

TiO2 thin films were deposited on quartz substrates by DC reactive magnetron sputtering of a pure Ti target in Ar/O2 plasma at room temperature. The TiO2 films were annealed at different temperatures ranging from 300 to 800 ℃ in a tube furnace under flowing oxygen gas for half an hour each. The effect of annealing temperatures on the structure, optical properties, and morphologies were presented and discussed by using X-ray diffraction, optical absorption spectrura, and atomic force microscope. The films show the presence of diffraction peaks from the （101）, （004）, （200） and （105） lattice planes of the anatase TiO2 lattice. The direct band gap of the annealed films decreases with the increase of annealing temperature. While, the roughness of the films increases with the increases of annealing temperature, and some significant roughness changes of the TiO2 film surfaces were observed after the annealing temperature reached 800 ℃. Moreover, the influences of annealing on the microstructures of the TiO2 film were investigated also by in situ observation in transmission electron microscope.

关键词： TiO2 films DC reactive magnetron sputtering anatase in situ tem annealing

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A Study of Nano Materials and Their Reactions in Liquid Using in situ Wet Cell tem Technology

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Chinese Journal of Chemistry 2012年第12期30卷 2839-2843页

作者： Chen Xin Zhou Lihui Wang Ping Zhao Chongjun Miao Xiaoli Key Laboratory for Ultrafine Materials of Min&try of Education and Shanghai Key Laboratory of Advanced Polymeric Materials School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 China Department of Materials Science andEngineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA East China University of Science and Technology Shanghai 200237 China State Key Laboratory of Bioreactor Engineering Biomedical Nanotechnology Center East China University of Science and Technology Shanghai 200237 China

Several nano material and reaction systems were in situ monitored with an electrochemical tem wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition （EBID） method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.

关键词： in situ tem nano material electrochemical reaction electron beam induced deposition semiconductor

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in situ tem STUDY ON THE R-PHASE TRANSFORMATION IN TiNi ALLOY

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Acta Metallurgica Sinica(English Letters) 1996年第3期9卷 157-163页

作者： CHEN Qing WU Xingfang and C. J. Humphreys(Department of Materials Physics, University of Science and Technology Beijing, Beijing 100083, China)(Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CBZ 3QZ, U. K.)

The R-phase transformation process in selected TiNi alloys has been studied in great detail by using in situ tem technique. The R-phase transformation was found to be a reversible thermoelastic displacive transformation with a nucleation and growth process. The R-phase nucleates at the precipitate/matrix interface in aged specimens and grows by moving the coherent R/matrix interfaces. The stress field of Ti3Ni4 precipitates plays a much more important role in the formation of the R-phase than dislocations in aged TiNi alloy. The microstructure of the R-phase has also been studied.

关键词： R-phase transformation TiNi alloy in situ tem

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Porous bismuth nanocrystals with advanced sodium ion storage property

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Progress in Natural Science:Materials International 2023年第1期33卷 92-99页

作者： Yun Li Yaqing Guo Kun You Chi Guo Chenghang Li Xuemei Zeng Wei Wang Qing Tang Yifei Yuan College of Chemistry and Materials Engineering Wenzhou University Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education School of Optoelectronic Materials & Technology Jianghan University

Bismuth-based materials are ideal electrodes for sodium-ion batteries(SIBs) due to their high capacity and low cost. However, conventional solid bismuth materials still suffer from severe volume expansion during the reaction process, which hinders its application. Herein, single-crystal bismuth nanospheres with diameters in the range of200–400 nm were successfully prepared with the Na–Bi alloying mechanism studied using in-situ XRD, which confirms a stepwise process of Bi→NaBi→Na3Bi with large volume variation. To address the volume change issue,we introduce a porous structure into the bulk of Bi crystals, which alleviated its volume expansion and suppressed its cyclic failure. An in-situ tem experiment is further carried out to verify this effective structure-modification strategy, demonstrating its applicable feature for electrode design and performance enhancement.

关键词： in situ tem Bismuth anode Alloying mechanism Sodium-ion battery

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Atomic insights into heterogeneous nucleation and growth kinetics of Al on TiB_(2) particles in undercooled Al-5Ti-1B melt

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Journal of Materials Science & Technology 2023年第25期156卷 72-82页

作者： Jing Feng Yanfeng Han Xiaocang Han Xiaodong Wang Shuangxi Song Baode Sun Mingwei Chen Pan Liu Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Engineering Johns Hopkin UniversityBaltimoreMD 21218USA

Titanium diboride(TiB_(2))is an effective grain refiner of Al alloys in the industry that facilitates casting processes by forming uniformly refined microstructures.Although our understanding of the underlying refinement mechanisms has advanced,the atomic kinetics of heterogeneous nucleation of Al on TiB2 remains unknown.Here,we report atomic-scale observations of the heterogeneous nucleation and growth kinetics of Al on self-formed TiB_(2) particles by in situ heating of undercooled Al-5Ti-1B films.We demonstrate that an ordered Al monolayer forms on the Ti-terminated{0001}TiB_(2) surface;then,the surrounding Al atoms are initiated to form an island-shaped Al nucleus with face-centered cubic{111}stacking without the assistance of a Ti-rich buffer layer.The interfacial lattice mismatch between{111}Al and{0001}TiB_(2) causes remarkable out-of-plane strain that decreases gradually with Al nucleus layers increasing to 6 atomic layers.The elastic strain energy originating from this interfacial strain increases the free energy of the Al/TiB2 heterostructure,hence impeding the rapid growth of the Al nucleus.We found that TiB2 particles stabilize the Al nuclei rather than activating their free growth into grains when the experimental undercoolingΔT is lower than the onset undercoolingΔT fg in Greer's free growth model.Our findings provide an atomic-scale physical image of the heterogeneous nucleation and growth mechanisms of Al with inoculator participation and elucidate the strain-dependent growth kinetics of Al nuclei.

关键词： in situ tem Heterogeneous nucleation Lattice strain Aluminum TiB2 particles

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