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Slice Thickness Optimization for the Focused Ion Beam-Scanning electron microscopy 3D Tomography of Hierarchical Nanoporous Gold

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Nanomanufacturing and Metrology 2022年第2期5卷 112-118页

作者： Alexander Shkurmanov Tobias Krekeler Martin Ritter electron microscopy Unit Hamburg University of Technology(TUHH)Eißendorfer Straße 4221073HamburgGermany

The combination of focused ion beam (FIB) with scanning electron microscopy (SEM), also known as FIB-SEM tomography, has become a powerful 3D imaging technique at the nanometer scale. This method uses an ion beam to mill away a thin slice of material, which is then block-face imaged using an electron beam. With consecutive slicing along the z-axis and subsequent imaging, a volume of interest can be reconstructed from the images and further analyzed. Hierarchical nanoporous gold (HNPG) exhibits unique structural properties and has a ligament size of 15–110 nm and pore size of 5–20 nm. Accurate reconstruction of its image is crucial in determining its mechanical and other properties. Slice thickness is one of the most critical and uncertain parameters in FIB-SEM tomography. For HNPG, the slice thickness should be at least half as thin as the pore size and, in our approach, should not exceed 10 nm. Variations in slice thickness are caused by various microscope and sample parameters, e.g., converged ion milling beam shape, charging effects, beam drift, or sample surface roughness. Determining and optimizing the actual slice thickness variation appear challenging. In this work, we examine the influence of ion beam scan resolution and the dwell time on the mean and standard deviation of slice thickness. After optimizing the resolution and dwell time to achieve the target slice thickness and lowest possible standard deviation, we apply these parameters to analyze an actual HNPG sample. Our approach can determine the thickness of each slice along the z-axis and estimate the deviation of the milling process along the y-axis (slow imaging axis). For this function, we create a multi-ruler structure integrated with the HNPG sample.

关键词： Focused ion beam Scanning electron microscopy Tomography Hierarchical nanoporous gold

Studies of Structure Evolution of Nanostructured Hf_(11)Ni_(89) Alloy

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Journal of Materials Science & Technology 1998年第3期14卷 205-210页

作者： Zhenfu DONG and Lianmao PENG(Beijing lab. of electron microscopy, Institute of Physics and Center for Condensed Matter Physics,Chinese Academy of Sciences, P.O.Box 2724, Beijing 100080, China)Ke LU and Zhuangqi HU(State Key lab. for RSA, Institute of Meta Beijing lab. of electron microscopy Institute of Physics and Center for Condensed Matter Physics Chinese Academy of Sciences Beijing 100080 P.O.Box 2724 China State Key lab. for RSA Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

A nanostructured Hf11Ni89 ribbon sample was prepared by melt-spinning. It was found that the as-quenched sample is composed of a major HfNi5 compound nanophase and an interfacial magnetic Ni(Hf) solid solution phase. The structure evolution of the sample was studied by using X-ray difFraction (XRD), transmission electron microscopy (TEM), difFerential scanning calorimetry (DSC), resistivity and magnetothermal analysis. Upon heating, a second precipitation process of the Ni(Hf) phase prior to grain growth wa5 detected by means of both structural analysis and physical property measurements. The measurement results are discussed based on the relationship between microstructure and physical properties.

关键词： Studies of Structure Evolution of Nanostructured Hf Alloy Ni

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Chemical Oxidation of La2CuO4 Epitaxial Thin Films Grown by Pulsed Laser Deposition

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Chinese Physics Letters 2007年第6期24卷 1674-1677页

作者：汪春昌闰允杰朱静 Beijing National Center for electron microscopy Tsinghua University Beijing 100084 laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084

Chemical oxidation is used to induce superconductivity in La2CuO4 expitaxial thin films fabricated by pulsed laser deposition technique. Details about the influence of oxidation time on structural, surface morphology, Raman spectra, and electrical properties have been investigated. The results convince that successful uptake of oxygen occurs in the oxidized films, and the content of the inserted oxygen increases with increasing oxidation interval. The possible mechanism for the excess oxygen insertion into the film is also discussed.

关键词： ELECTROCHEMICAL OXIDATION SPIN FLUCTUATIONS THERMAL-TREATMENT RAMAN-SCATTERING SUPERCONDUCTIVITY TEMPERATURE INDUCTION NACLO EFFUSION

Voltage-Induced Effect on Resistance of C:N/Si Heterojunctions

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Chinese Physics Letters 2012年第2期29卷 178-181页

作者： GAO Xi-Li ZHANG Xiao-Zhong WAN Cai-Hua WANG Ji-Min laboratory of Advanced Materials Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084 National Center for electron microscopy(Beijing) Tsinghua UniversityBeijing 100084

Nitrogen doped a-C/Silicon (a-C:N/Si) heterojunctions have been fabricated by using the pulsed laser deposition (PLD) technique and their current-voltage characteristics at various temperatures are *** reverse applied voltages,a-C:N/Si heterojunctions exhibit metal-insulator transition characteristics and the transition temperature can be controlled by the applied *** the excitation of repeated high reverse applied voltages,the current-voltage curves show obvious hysteresis behaviors at low *** hysteresis behaviors are reproducible and the ratio of the high/low resistance can be greater than 104.

关键词： hysteresis C:N Voltage

Application of cathodoluminescence to zircon in FEG-ESEM

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Progress in Natural Science:Materials International 2006年第9期16卷 919-924页

作者： CHEN Li , XU Jun and SU Li (electron microscopy laboratory, School of Physics, Peking University, Beijing 100871, China Geology Experimental Center, China University of Geoscience, Beijing 100083, China) electron microscopy laboratory School of Physics Peking University Beijing 100871 China Geology Experimental Center China University of Geoscience Beijing 100083 China

Cathodoluminescence (CL) image analysis of zircon is a key step of mineral micro-area compositional investigation and U-(Th)-Pb dating. We introduce a system consisting of field emission ESEM and high performance cathodoluminescence. This system has obvious advantages in imaging resolution and CL spectrum. We acquired some zircon CL images and spectra to demonstrate the ability of this system. Our results show that this system has a great potential application to characterize and identify the genesis of zircon.

关键词： zircon cathodoluminescence ESEM.

Application of three-dimensional electron diffraction in structure determination of zeolites

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Chinese Journal of Structural Chemistry 2024年第4期43卷 39-47页

作者： Yuhang Li Yang Ling Yanhang Ma School of Physical Science and Technology&Shanghai Key laboratory of High-resolution electron microscopy ShanghaiTech UniversityShanghai201210China

Zeolites have received great attention due to their wide applications in various fields such as catalysis,adsorp-tion/separation,ion exchange,*** the atomic crystal structure of zeolites is crucial to understanding their functions and exploring their *** to the difficulty of synthesizing large single crystals,the structures of many zeolites cannot be solved using conventional single-crystal X-ray diffraction(SCXRD)***-dimensional electron diffraction(3D ED)has witnessed rapid development during the past decade and has shown its powerful ability in the structure determination of *** this review,we will briefly introduce the history of 3D ED and summarize recent advances in the application of 3D ED for the analysis of zeolite structures,along with several typical examples in this research field.

关键词： electron diffraction Three-dimensional electron diffraction Zeolite Structure solution electron crystallography

Morphologies of Al_4Sr Intermetallic Phase and Its Modification Property upon A356 Alloys

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Journal of Materials Science & Technology 2012年第6期28卷 524-530页

作者： Chengwei Liao Jianchun Chun Yang Li Rui Tu Chunxu Pan School of Physics and Technology and Center for electron microscopy Wuhan UniversityWuhan 430072China Hunan Jinlianxing Specially Materials Technology Co.Ltd Yueyang 414005China

In general, the modification performance of AI-Sr master alloys is primarily dependent upon the morphologies and sizes of the AI4Sr intermetallic phase. In this paper, the crystal structure, morphologies, sizes, hardness and elastic modulus of AI4Sr in AI-Sr master alloys prepared from variant processes were studied by means of optical metallurgical microscope, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and nanoindentation system. The results revealed that the microstructures and modification performance of the AI4Sr phase were related to the preparation processes. That is to say, when a ＂direct reaction-hot extrusion＂ process was used, the AI4Sr phase exhibited a homogeneous distribution in the AI matrix with small size and roundish shapes, which ensured the AI-Sr master alloy wire advantages involving high recovery, good reproducibility, no delitescence of modification, no corrosion on equipments, and good workability. However, in the case of the traditional ＂direct reaction＂ process, the AI4Sr phase was in large size with shapes of rectangular stripe and plates, which limited the Sr content increasing due to the brittleness of the AI-Sr alloy. It was also found that the morphology and size of the AI4Sr phases changed during heat treatment at high temperature up to 600℃.

关键词： Intermetallics Modification Hot extrusion Heat treatment Microstructure

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CNTs/TiO2 composites and its electrochemical properties after UV light irradiation

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Progress in Natural Science:Materials International 2013年第2期23卷 164-169页

作者： Bin Zhang Rui Shi Yupeng Zhang Chunxu Pan School of Physics and Technology and MOE Key Laboratory of Artificial Micro-and Nano-structures Wuhan University Center for electron microscopy Wuhan University

Due to the unique structure and special physical and chemical properties, carbon nanotubes (CNTs) have potential applications in supercapacitors. Recently, CNTs and their composites as a kind of supercapacitor electrode material have been made many achievements. In this paper, a CNTs/TiO2 composite was prepared successfully with hydrothermal method, and was used as a supercapacitor electrode material. After the tests on surface chemistry and electrochemical property, it was found that: (1) the capacitance of the CNTs/TiO2 composite electrode increased by 56%, compared with pure CNTs electrode, (2) after UV light irradiation pretreatment, due to the special photoelectric effect of TiO2 which improves the interfacial property and electrochemical property of the composite electrode, the capacitance further increased by 53% when compared with the electrode without the pretreatment, and meanwhile, the cycle life also increased significantly, i.e., the capacitance was up to 97%, after 100 cycles of charge and discharge, (3) due to the improvement of the interfacial property, the ion transport in the composite electrode became smoother, and the pore utilization was also effectively enhanced during high-current charge and discharge, and (4) due to the generation of a large amount of oxygen-containing groups on the TiO 2 surface after UV pretreatment, the CNTs/TiO2 composite electrode earned extra large pseudo capacitance, and therefore the capacitance of the composite electrode was further increased. Based on the experimental results in the present study a new process to improve surface character and electrochemicalproperty of the electrode has been developed by using a metal oxide as both pseudo capacitive material and surface modification material of the composites with a UV light irradiation.

关键词： Carbon nanotubes (CNTs) TiO2 Composite Supercapacitor

Synthesis and Characterization of Electroless Ni-P/Ni-Mo-P Duplex Coating with Different Thickness Combinations

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Acta Metallurgica Sinica(English Letters) 2017年第10期30卷 1008-1016页

作者： Gong-Sheng Song Shuo Sun Zhong-Chi Wang Cheng-Zhi Luo Chun-Xu Pan School of Physics and Technology and MOE Key Laboratory of Artificial Micro- and Nano-StructuresWuhan University School of Science Shenyang University of Technology Center for electron microscopy Wuhan University

In this work, a novel duplex Ni-P/Ni-Mo-P coating upon the aluminum（Al） substrate was synthesized via an electroless plating, i.e., the binary Ni-P coating as a transition layer and the ternary Ni-Mo-P coating on the top. It was found that the duplex coating was of a high hardness,large elastic modulus,low porosity and excellent corrosion resistance. In addition, experimental results revealed that for a total 20 μm coating thickness, the duplex coating with a 7 μm of the Ni-Mo-P coating exhibited the best corrosion resistance in 0.5 mol/L sulfuric acid solution, which was attributed to its compact structure and low porosity. This duplex Ni-P/Ni-Mo-P coating with a thin ternary Ni-Mo-P layer is expected to solve the problem of low deposition rate of ternary alloy coating and thereby may expand applications of Al and its alloys in the fields of machine manufacture and corrosion environment.

关键词： Electroless plating Aluminum (Al) Porosity Ni-P/Ni-Mo-P duplex coating Corrosion resistance

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