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Structures and formation mechanisms of dislocation-induced precipitates in relation to the age-hardening responses of Al-Mg-Si alloys

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Journal of Materials Science & Technology 2020年第6期41卷 127-138页

作者： Y.X.Lai W.Fan M.J.Yin C.L.Wu J.H.Chen Center for High-Resolution electron microscopy College of Materials Science&EngineeringHunan UniversityChangsha 410082China electron microscopy Center Shenzhen UniversityShenzhen 518060China

In the slightly deformed Al-Mg-Si alloys,dislocation-induced precipitates are frequently observed,and they usually line up,forming sophisticated precipitation *** atomic-resolution electron microscopy in association with hardness measurements,we systematically investigated these precipitates in relation to the age-hardening responses of the *** study reveals that the majority of dislocation-induced complex precipitates are actually short-range ordered while long-range disordered polycrystalline precipitates and multiphase composite precipitates,including polycrystalline U2 precipitates,B’/U2,B’-2/U2,B’/B’-2/U2 and’/U2 composite *** is suggested that the formation of these complex precipitates is mainly owing to a high nucleation rate and rapid growth of different precipitate phases parallel to the associated dislocation *** dislocation-induced precipitates consume more Mg than Si from the matrix and have a high formation kinetics,they will have different impacts on the matrix precipitation in different types of Al-Mg-Si *** results further demonstrate that for the"normally-β"-hardened"alloy,their formation leads to a coarser precipitate microstructure in the matrix,whereas for the"normally-β’-hardened"alloy,their formation reverses the precipitation pathway in the matrix,resulting in a reduced age-hardening potential of the former alloy and an improved age-hardening potential of the latter alloy.

关键词： Al-Mg-Si alloys Precipitation Dislocation Age-hardening electron microscopy

Helium droplet assisted synthesis of plasmonic Ag@ZnO core@shell nanoparticles

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Nano Research 2020年第11期13卷 2979-2986页

作者： Alexander Schiffmann Thomas Jauk Daniel Knez Harald Fitzek Ferdinand Hofer Florian Lackner Wolfgang E.Ernst Institute of Experimental Physics Graz University of TechnologyA-8010GrazAustria Institute of electron microscopy and Nanoanalysis&Graz Centre for electron microscopy Graz University of TechnologyA-8010GrazAustria

Plasmonic Ag@ZnO core@shell nanoparticles are formed by synthesis inside helium droplets with subsequent deposition and controlled *** particle size and shape can be controlled from spherical sub-10 nm particles to larger elongated *** advantage of the method is the complete absence of solvents,precursors,and other chemical *** obtained particle morphology and elemental composition have been analyzed by scanning transmission electron microscopy(STEM)and energy dispersive X-ray spectroscopy(EDS).The results reveal that the produced particles form a closed and homogeneous ZnO layer around a 2–3 nm Ag core with a uniform thickness of(1.33±0.15)nm and(1.63±0.31)nm for spherical and wire-like particles,*** results are supported by ultraviolet photoelectron spectroscopy(UPS),which indicates a fully oxidized shell layer for the particles studied by *** plasmonic properties of the produced spherical Ag@ZnO core@shell particles are investigated by two-photon photoelectron(2PPE)*** excitation of the localized surface plasmon resonance in Ag at around 3 eV,plasmonic enhancement leads to the liberation of electrons with high kinetic *** is observed for both Ag and Ag@ZnO particles,showing that even if a Ag cluster is covered by the ZnO layer,a plasmonic enhancement can be observed by photoelectron spectroscopy.

关键词： nanoparticle helium droplet plasmonics photoelectrons

Sulfolane‑Based Flame‑Retardant Electrolyte for High‑Voltage Sodium‑Ion Batteries

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Nano-Micro Letters 2025年第2期17卷 498-516页

作者： Xuanlong He Jie Peng Qingyun Lin Meng Li Weibin Chen Pei Liu Tao Huang Zhencheng Huang Yuying Liu Jiaojiao Deng Shenghua Ye Xuming Yang Xiangzhong Ren Xiaoping Ouyang Jianhong Liu Biwei Xiao Jiangtao Hu Qianling Zhang Graphene Composite Research Center College of Chemistry and Environmental EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China Center of electron microscopy State Key Laboratory of Silicon and Advanced Semiconductor MaterialsSchool of Materials Science and EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China GRINM(Guangdong)Research Institute for Advanced Materials and Technology FoshanGuangdong 528051People’s Republic of China College of Energy Engineering Zhejiang UniversityHangzhouZhejiang 310027People’s Republic of China School of Materials Science and Engineering Xiangtan UniversityXiangtan 411105People’s Republic of China Shenzhen Eigen-Equation Graphene Technology Co.Ltd Shenzhen 518000People’s Republic of China

Sodium-ion batteries hold great promise as next-generation energy storage ***,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of *** particular,an unstable cathode–electrolyte interphase(CEI)leads to successive electrolyte side reactions,transition metal leaching and rapid capacity decay,which tends to be exacerbated under high-voltage ***,constructing dense and stable CEIs are crucial for high-performance *** work reports localized high-concentration electrolyte by incorporating a highly oxidation-resistant sulfolane solvent with non-solvent diluent 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether,which exhibited excellent oxidative stability and was able to form thin,dense and homogeneous *** excellent CEI enabled the O3-type layered oxide cathode NaNi_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)to achieve stable cycling,with a capacity retention of 79.48%after 300 cycles at 1 C and 81.15%after 400 cycles at 2 C with a high charging voltage of 4.2 *** addition,its nonflammable nature enhances the safety of *** work provides a viable pathway for the application of sulfolane-based electrolytes on SIBs and the design of next-generation high-voltage electrolytes.

关键词： Sodium-ion batteries Sulfolane-based electrolyte High voltage Layered oxide cathode Flame retardant

Growth Mechanism and Optimized Parameters to Synthesize Nation-115 Nanowire Arrays with Anodic Aluminium Oxide Membranes as Templates

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Chinese Physics Letters 2008年第8期25卷 3056-3058页

作者：张鹭潘曹峰朱静 Beijing National Center for electron microscopy Lab of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084

Nation-115 nanowire arrays are synthesized with an extrusion method using AAO membranes as templates. It is indicated that the vacuum treating of AAO templates before surface decoration plays an important role in obtaining high filling rate of the Nation-115 nanowires in the AAO templates, vchile the concentration of Nafion-115 DMSO solutions does not affect the flling rate greatly. The optimized parameters to synthesize the Nation-115 nanowire arrays are studied. The filling rate of the Nadion-115 nanowires in the AAO templates synthesized with the optimized parameters is about 95% discussed to qualitatively explain the experimental results The growth mechanism of Nafion-115 nanowires is

关键词： the vacuum treating growth mechanism

Complex Precipitation Sequences of Al-Cu-Li-(Mg)Alloys Characterized in Relation to Thermal Ageing Processes

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 94-103页

作者： Zhen Gao Jiang-Hua Chen Shi-Yun Duan Xiu-Bo Yang Cui-Lan Wu Center for High-Resolution electron microscopy College of Materials Science and EngineeringHunan University

The A1-Cu-Li-（Mg） alloy is a high-performance lightweight material strengthened by complex coexisting precipitates that form in the alloy upon thermal ageing. Using high-resolution （scanning） transmission electron microscopy in association with first-principles energy calculations, we systematically studied the complex coexisting precipitates in the alloys and correlated their precipitation sequences with thermal ageing processes applied. The principal results are the following：（1） eight types of precipitates can be observed in the alloy; （2） of these precipitates, the Tl-phase is most stable. The S-phase precipitates with segregated Li atoms at their interfacial edges are unexpectedly more stable than the a-phase; （3） the Tl-phase has a characteristic precursor that plays the key role in its nucleation and growth.

关键词： AI-Cu-Li alloy electron microscopy Ageing Precipitation Strength

Gastrin and antral G cells in course of Helicobacter pylori eradication: Six months follow up study

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World Journal of Gastroenterology 2005年第27期11卷 4140-4147页

作者： Aleksandra Sokic-Milutinovic Vera Todorovic Tomica Milosavljevic Marjan Micev Neda Drndarevic Olivera Mitrovic Clinic for Gastroenterology and Hepatology Department of Imunohistochemistry and electron microscopy Pathology Department

AIM： To assess long-term effects of Helicobacter pylori （H pylon} eradication on antral G cell morphology and function in patients with and without duodenal ulcer （DU）.METHODS： Consecutive dyspeptic patients referred to the endoscopy entered the study. Out of 39 Hpylori positive patients, 8 had DU （Hpylori ＋DU） and 31 gastritis （Hpylori＋G）. Control groups consisted of 11 uninfected dyspeptic patients （CG1） and 7 healthy volunteers （CG2）. Basal plasma gastrin （PGL）, antral tissue gastrin concentrations （ATGC）, immunohistochemical and electron microscopic characteristics of G cells were determined, prior to and 6 mo after ***： We-demonstrated elevated PGL in infected patients compared to uninfected controls prior to *** PGL were registered in all Hpylori＋patients （Hpylori＋DU： 106.78＋22.72 pg/mL, Hpylori＋G： 74.95＋15.63,CGI： 68.59＋17.97, CG2：39.24＋5.59 pg/mL, P〈0.01）.Successful eradication （e） therapy in Hpylori＋patients lead to significant decrease in PGL （Hpylori＋DU： 59.93＋9.40 and Hpylori＋Ge： 42.36＋10.28 pg/mL, P〈0.001）. ATGC at the beginning of the study were similar in infected and uninfected patients and eradication therapy lead to significant decrease in ATGC in Hpylori＋gastritis, but not in DU patients. In the Hpylori＋DU patients, the mean number of antral G cells was significantly lower in comparison with all other groups （P〈0.01）, but after successful eradication was close to normal values found in controls. By contrast, G cell number and volume density were significantly decreased （P〈0.01） in Hpylori＋Ge group after successful eradication therapy （294＋32 and 0.31＋0.02,respectively）, in comparison to values before eradication （416~40 and 0.48~0.09）. No significant change of the G cell/total endocrine cell ratio was observed during the 6 mo of follow up in any of the groups. A reversible increase in G cell secretory function was seen in all infected individuals, demonstrated by a more prominent secretory apparatus. However, differences b

关键词： Gastrin G cell Duodenal ulcer Gastritis He/icobacter py/ori

Optimal design of self-propagating high temperature one-dimensional nano-SnO_2 synthesis

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Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 321-325页

作者： Nian LIU Guodonq ZHANG Department of Materials Engineering and Center for electron microscopy Wuhan UniversityWuhan 430072 China

The success in synthesizing high purity SnO2 nanobelts via self-propagating high tem- perature synthesis was achieved. According to the experimental results, a relationship between the residual heat of the reaction system at 2848 K and SnO2 nanobelts yield was identified. The most appropriate formula for this self-propagating high tempera- ture synthesis method is turned out to be composed of Sn powder and thermite with weight ratio of 1：1.

关键词： Optimal design Self-propagating high temperature synthesis Nano-Sn02

Preparation of size controllable copper nanocrystals for nonvolatile memory applications

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Chinese Physics B 2010年第10期19卷 593-596页

作者：王利孙红芳周惠华朱静 Beijing National Center for electron microscopy Department of Materials Science and Engineering Tsinghua University

A method of fabricating Cu nanocrystals embedded in SiO2 dielectric film for nonvolatile memory applications by magnetron sputtering is introduced in this paper. The average size and distribution density of Cu nanocrystal grains are controlled by adjusting experimental parameters. The relationship between nanocrystal floating gate micro-structure and its charge storage capability is also discussed theoretically.

关键词： nanocrystal grain nonvolatile memory Coulomb blockade effect magnetron sputtering

Structure and Growth Mechanism of V/Ag Multilayers with Different Periodic Thickness Fabricated by Magnetron Sputtering Deposition

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Journal of Materials Science & Technology 2014年第10期30卷 1012-1019页

作者： Hongxiu Zhang Feng Ren Mengqing Hong Xiangheng Xiao Guangxu Cai Changzhong Jiang School of Physics and Technology Center for Ion Beam Applicationand Center for Electron MicroscopyWuhan University

V/Ag multilayers with different periodic thicknesses were fabricated by magnetron sputtering deposition. The columnar structure and the orientation relationship of the multilayers were investigated by transmission electron microscopy, high resolution transmission electron microscopy, selected-area electron diffraction and X-ray diffraction. It was found that the multilayered structure became flatter as increasing individual layer thickness from 2 to 6 nm, and then became waved as the individual layer thickness increases to 8 nm. At the beginning of the growth, the morphology of the multilayers with small periodic thickness was influenced mainly by thermodynamic instabilities, and the morphology of the multilayers with larger periodic thickness was mainly influenced mainly by the columnar growth of V. When the waved interfaces were formed, the continuum growth of the multilayers was also influenced by the shadowing effect and the finite atomic size effect. All of these factors resulted in the columnar structure of the multilayers. Multilayers with small periodic thickness presented strong orientation relationship. Nano-hardness tests indicated that multilayers with flat sublayer morphology and clear interfaces exhibited larger hardness.

关键词： Multilayers Interfaces Columnar structure Transmission electron microscopy