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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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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 *** 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 ***,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 ***,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 *** 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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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 ***,the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate ***,we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor *** conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/*** 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 *** further employ in situ transmis sion electron microscopy and ope rando X-ray diffraction to probe the potassium-ion storage *** 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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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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Real-time in situ tem studying the fading mechanism of tin dioxide nanowire electrodes in lithium ion batteries

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Science China(Technological Sciences) 2013年第11期56卷 2630-2635页

作者： WANG LiFen XU Zhi YANG ShiZe TIAN XueZeng WEI JiaKe WANG WenLong BAI XueDong Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Fading mechanism of tin dioxide （SnO2） electrodes in lithium ion batteries has attracted much attentions, which is of great importance for the battery applications. In this paper, electrochemical lithiation-delithiation cycles of individual SnO2 nanowires were conducted in situ in a high-resolution transmission electron microscopy （tem）. Major changes in volume with expan- sions of 170%~300% on SnO2 nanowire electrodes were observed during the first lithiation process in electrochemical cycling, including conversion reaction of SnO2 precursor to Li20 matrix and active lithium host Sn, and alloying of Sn with Li to form brittle Li-Sn alloy. SnO2 nanowire electrodes were inclined to suffer from thermal runaway condition in the first two cycles. During cycling, morphology and composition evolution of SnO2 nanowire electrodes were recorded. Cyclic lithiation and del- ithiation of the electrode demonstrated the phase transition between Lii3Sn5 and Sn. Metallic Sn clusters were formed and their sizes enlarged with increasing cycle times. Detrimental aggregation of Sn clusters caused pulverization in SnO2 nanowire elec- trodes, which broke the conduction and transport path for electrons and lithium ions. The real-time in situ tem revealed fading mechanism provides important guidelines for the viable design of the SnO2 nanowire electrodes in lithium ion batteries.

关键词： lithium ion battery tin dioxide nanowire electrode fading mechanism tin aggregation in situ tem

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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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A thick yet dense silicon anode with enhanced interface stability in lithium storage evidenced by in situ tem observations

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Science Bulletin 2020年第18期65卷 1563-1569,M0004页

作者： Junwei Han Dai-Ming Tang Debin Kong Fanqi Chen Jing Xiao Ziyun Zhao Siyuan Pan Shichao Wu Quan-Hong Yang Nanoyang Group State Key Laboratory of Chemical EngineeringSchool of Chemical Engineering and TechnologyCollaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin UniversityTianjin 300350China International Center for Materials Nanoarchitectonics(WPI-MANA) National Institute for Materials Science(NIMS)Namiki 1-1Tsukubalbaraki 305-0044Japan CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207China

Increasing the density and thickness of electrodes is required to maximize the volumetric energy density of lithium-ion batteries for practical ***,dense and thick electrodes,especially highmass-content(>50 wt%) silicon anodes,have poor mechanical stability due to the presence of a large number of unstable interfaces between the silicon and conducting components during *** we report a network of mechanically robust carbon cages produced by the capillary shrinkage of graphene hydrogels that can contain the silicon nanoparticles in the cages and stabilize the silicon/carbon *** situ transmission electron microscope characterizations including compression and tearing of the structure and lithiation-induced silicon expansion experiments,have provided insight into the excellent confinement and buffering ability of this interface-strengthened graphene-caged silicon nanoparticle anode ***,a dense and thick silicon anode with reduced thickness fluctuations has been shown to deliver both high volumetric(>1000 mAh cm^-3) and areal(>6 mAh cm^-2)capacities together with excellent cycling capability.

关键词： Lithium-ion battery Silicon anode Interface stability in situ tem Dense and thick electrodes

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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 *** 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 *** 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 *** results can be used to generate donut-shaped *** a scanning electron beam,line structures with both branched and unbranched morphologies were also *** 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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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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Synergistic coupling of amorphous carbon and graphitic domains toward high-rate and long-life K^(+) storage

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Journal of Energy Chemistry 2022年第10期31卷 533-541,I0013页

作者： Hehe Zhang Wangqin Li Jianhai Pan Zhefei Sun Bensheng Xiao Weibin Ye Chengzhi Ke Haowen Gao Yong Cheng Qiaobao Zhang Ming-Sheng Wang State Key Laboratory of Physical Chemistry of Solid Surfaces College of MaterialsXiamen UniversityXiamen 361005FujianChina Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials(Xiamen University) Xiamen 361005FujianChina

Amorphous carbon materials hold great potential for practical use in potassium-ion batteries(PIBs)due to their abundant resources,low cost and high structural ***,given the challenge of sluggish potassiation kinetics,the rate performance of amorphous carbon is severely ***,amorphous carbon compounded with graphitic domains(HG-CNTs)was proposed as an advanced anode for *** directly verified by in situ transmission electron microscopy(tem),the graphitic domains guarantee fast K-ions transport in the carbon composite at a high current density,while the amorphous carbon shells ensure the structural integrity during potassiation,thus boosting its fast and durable K^(+)*** a PlB anode,the HG-CNTs electrode exhibits not only a super-stable long-term cyclability(191.6 mAh g^(-1)at 1 A g^(-1)with almost no capacity decay over 3000 cycles),but also an outstanding rate performance(184.5 mAh g^(-1)at 2 A g^(-1)).Ex situ Raman and tem results further suggest that the highly reversible structure of HG-CNTs is responsible for its superior electrochemical *** work provides helpful insights into the development of carbonaceous electrodes with both high rate capability and long cycle life for PIBs.

关键词： Potassium-ion batteries Amorphous carbon Graphitic domains Synergistic effect in situ tem

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