Artykuły w czasopismach: „Atomic-resolution TEM”

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Bell, David C., Christopher J. Russo i Dmitry V. Kolmykov. "40keV atomic resolution TEM". Ultramicroscopy 114 (marzec 2012): 31–37. http://dx.doi.org/10.1016/j.ultramic.2011.12.001.

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Yagi, K., H. Sato, K. Kobayashi, Y. Nishiyama i Y. Tanaka. "TEM study of Si surfaces". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 1 (sierpień 1992): 280–81. http://dx.doi.org/10.1017/s0424820100121806.

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UHV TEM studies of surfaces have been successfully applied in surface science. Low resolution TEM can characterize surface atomic steps, monolayer adsorbate, reconstruction of surfaces and surface structure domains. TED from surfaces of thin films can be used to analyze surface atomic structure. On the other hand high resolution TEM can seen atomic structure of surfaces either in profile or in plan view modes. The profile mode is effective for surfaces with short periods along the beam direction and is sensitive to displacements of surface atoms normal to the surface and along a direction parallel to the surface and perpendicular to the beam direction. Image contrast of high resolution plan view images is very weak except cases of heavy adsorbed atoms on a substrate of light atoms. The present paper shortly reviews recent studies of Si surfaces done with use of a low resolution UHV TEM and high resolution TEM.

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Lee, Yangjin, Jun-Yeong Yoon, Hu Young Jeong i Kwanpyo Kim. "Atomic-Resolution TEM Imaging of Phosphorene Protected by Graphene". Microscopy and Microanalysis 25, S2 (sierpień 2019): 1696–97. http://dx.doi.org/10.1017/s1431927619009218.

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Hashimoto, Hatsujiro. "Contribution of Atomic-Level TEM to Resolution of Structure". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 1 (12.08.1990): 4–5. http://dx.doi.org/10.1017/s042482010017877x.

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Atomic Resolution Electron Microscopes are now producing useful results in many fields of science and technology. This success was obtained not only by the improvement of resolution of TEM but also through the developments of theories and experiments of diffraction crystallography, image formation and recording technique over the past 44 years. Boersch (1946-47) discussed the image of atoms and crystals by the phase object approximation; the image contrast is due to the phase shift of electron waves passing through them. Scherzer (1949) discussed the effect of the phase shift by the electron lens and proposed the phase contrast transfer function. He pointed out that the key to observe images of single atoms is by contrast enhancement, which might be possible by dark field images if resolution is improved. This proposal was attempted by improving the resolution using tilted-beam dark fields (Th atoms, Hg & Pt atoms 1971). Crystal lattice fringes were observed by Menter in 1956 who discussed the contrast by kinematical theory. The interpretation of lattice images by dynamical theories were carried out by Hashimoto et al. (Bethe theory) and Cowley (Multi-slice theory) in 1958-60 and noted the correct position of atoms is in neither black fringe regions nor white ones when the images are taken in the Bragg reflecting position. However Miyake et al in 1964, showed that black or white contrast peaks appear at atom positions if the crystal is in symmetry position. Two dimensional lattice structure images were first photographed in 1970-71, which stimulated strongly the application of electron microscopy to materials science, crystallography and engineering at many laboratories such as the National Center at Berkeley. For the identification of correct position of atoms, two types of image contrast calculation have been proposed (e.g. multi-slice 1972, Bethe method 1975). The partially coherent theory originally developed in optics was introduced into the contrast calculation in 1979-80. Around this time, many observations of defect structures have been carried out, some of which are shown in Table 1. In situ observation of moving atoms and atom columns in molecules and crystals have been carried out in 1978 by using a TV system, which enable us to see the transition phenomena with a speed of 1/30 or 1/60 seconds. More recently atomic imaging at 1.8 A-1.6 A played an important role in the structure research of new materials and phenomena such as superconducting materials (metallic A15, 1989, ceramic high Tc, 1988), metal ceramic interface (Nb/Al2O3 1984), superstructure (GaAs/AlAs/GaAs 1985) quasi crystals (1987) etc. Many subsequent observations are presented in this congress. In spite of these developments, there are still some problems to be solved, e.g. imaging of atoms in the correct positions and the identification of different kinds of atoms in the materials especially with unknown crystal structure.

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Cochrane, Heather D., John L. Hutchison i Donald White. "Surface studies of catalytic ceria using atomic-resolution tem". Ultramicroscopy 31, nr 1 (wrzesień 1989): 138–42. http://dx.doi.org/10.1016/0304-3991(89)90044-2.

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Krakow, William, David P. Divincenzo, Peter A. Bancel, Eric Cockayne i Veit Elser. "High-resolution TEM of Al-Cu-Fe quasicrystals". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 1 (sierpień 1992): 118–19. http://dx.doi.org/10.1017/s0424820100120990.

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High resolution electron microscopy and electron diffraction have always been key tools for the study of quasicrystals. The unique features of quasicrystals arc their long range oricntational order despite the absence of periodic translational order, and their non-crystallographic symmetry. The early work in electron microscopy and diffraction assessed the degree of perfection of these materials; microdo-mains with slightly different orientations, phason strains and dislocations were found which masked the fundamental atomic structure. A defect free material was sought to deduce the atomic arrangement of these materials and this was found in Al-Cu-Fe. Preliminary examinations of these materials using 20 at.% Cu and 15 at.% Fe indicated they are almost entirely free of phason strains when viewed in a 200kV microscope.At the time of these investigations the microscopes employed were limited in resolution and thus provide limited information about the atomic arrangements of these quasicrystals. Recently, studies were made using a more powerful microscope operating at 400kV where the point resolution is improved to 1.7Å. In that case, a Al-Mn-Si specimen was viewed along the five-fold axis under apparent optimum imaging conditions. These prior studies have interpreted various image features as being due to dynamical scattering processes and therefore little about the atomic arrangement of the quasicrystal is obtained. Our interpretation of the image feature is different and is due to modification of the phase contrast transfer function. Here clarification is given of the information contained in high resolution micrographs of quasicrystals.

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Zhang, Xiao Feng, i Takeo Kamino. "Imaging Gas-Solid Interactions in an Atomic Resolution Environmental TEM". Microscopy Today 14, nr 5 (wrzesień 2006): 16–19. http://dx.doi.org/10.1017/s1551929500058600.

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It is well known that analysis using transmission electron microscopes (TEM) yields very high resolution images of thin specimens. However, the applicability of TEM analysis is not universal due to the requirement that a high internal vacuum is required. This high vacuum precludes the TEM study of living specimens or specimens in a gas or liquid environment. In order to tackle this problem, L. Marton of Universite Libre in Brussels, Belgium was the first to design an environmental cell (E-cell) in 1935 that was sealed in the tip of a TEMsample holder [1]. Marton's design included two 0.5 μm aluminum foils as upper and lower windows sandwiching a biological sample to sustain a living environment. The electron transparent windows permitted the confined biological objects to be imaged in TEMmode. Since then, environmental TEM (E-TEM) has received increasing attention from biological scientists and eventually from materials scientists as well.

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Kujawa, S., B. Freitag i D. Hubert. "An Aberration Corrected (S)TEM Microscope for Nanoresearch". Microscopy Today 13, nr 4 (lipiec 2005): 16–21. http://dx.doi.org/10.1017/s1551929500053608.

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The continued focus on improving materials, combined with the fact that it is now commonly understood that material properties are affected by characteristics at the atomic level, give rise to the need to characterize and image at the best resolutions possible. The (Scanning) Transmission Electron Microscope ((S)TEM) has the capability to image structures with atomic resolution and provides, at the same time, information on the chemical composition, bonding and electronic structure of the material. The nanoresearcher's continued need for the ultimate resolution has accelerated the development of next generation electron optics and technology.

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Zhang, Xiao Feng. "Enabling Lab-in-Gap Transmission Electron Microscopy at Atomic Resolution". Microscopy Today 24, nr 1 (styczeń 2016): 24–29. http://dx.doi.org/10.1017/s1551929515000930.

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Abstract: Hitachi Lab-in-Gap transmission electron microscopy (TEM) technologies are introduced. The term Lab-in-Gap refers to a special function that allows in situ and in operando TEM studies of materials in gas or liquid environments while stimulations, such as thermal or electrical fields, are applied to the specimen sitting in the pole piece gap in a TEM system. Physical or chemical process can be activated and imaged in real time using TEM or other imaging modes. The new generation environmental TEM platform with large pole piece gap and advanced aberration correctors opens wide possibilities for integrating multiple stimuli sources as well as large-area, sub-Å resolution live imaging for dynamic structural changes.

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Hasegawa, Tsuyoshi, Kunio Kobayashi, Nobuyuki Ikarashi, Kunio Takayanagi i Katsumichi Yagi. "Atomic Resolution TEM Images of the Au(001) Reconstructed Surface". Japanese Journal of Applied Physics 25, Part 2, No. 5 (20.05.1986): L366—L368. http://dx.doi.org/10.1143/jjap.25.l366.

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Takeda, Seiji, i Hideto Yoshida. "Atomic-resolution environmental TEM for quantitativein-situmicroscopy in materials science". Microscopy 62, nr 1 (16.01.2013): 193–203. http://dx.doi.org/10.1093/jmicro/dfs096.

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Kohno, Y., S. Morishita i N. Shibata. "New STEM/TEM Objective Lens for Atomic Resolution Lorentz Imaging". Microscopy and Microanalysis 23, S1 (lipiec 2017): 456–57. http://dx.doi.org/10.1017/s1431927617002963.

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Suenaga, K., T. Sasaki i H. Sawada. "Low-Voltage TEM/STEM for Atomic Resolution Imaging and Spectroscopy". Microscopy and Microanalysis 19, S2 (sierpień 2013): 1220–21. http://dx.doi.org/10.1017/s143192761300809x.

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O'Keefe, MA, LF Allard, SJ Pennycook i DA Blom. "Transcending the One-Ångström Atomic Resolution Barrier in the TEM". Microscopy and Microanalysis 12, S02 (31.07.2006): 162–63. http://dx.doi.org/10.1017/s1431927606069625.

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Tai, Kuo-Lun, Guan-Min Huang, Chun-Wei Huang, Tsung-Chun Tsai, Shih-Kuang Lee, Ting-Yi Lin, Yu-Chieh Lo i Wen-Wei Wu. "Observing phase transformation in CVD-grown MoS2via atomic resolution TEM". Chemical Communications 54, nr 71 (2018): 9941–44. http://dx.doi.org/10.1039/c8cc05129a.

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Kisielowski, Christian. "What Are Present Limits of Quantitative High Resolution Tem?" Microscopy and Microanalysis 3, S2 (sierpień 1997): 935–36. http://dx.doi.org/10.1017/s1431927600011569.

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In recent years quantitative high resolution electron microscopy (HREM) became a reliable tool to investigate physical processes at an atomic scale. Certainly, there is no unique approach to quantify the information content from lattice images. However, specific methods like Chemical Imaging^ and QUANTITEM were established that allow to investigate the atomic structure of crystalline solids quantitatively and almost routinely.Nevertheless, there are limits to the application of these methods and they are of principle and of practical nature. Obviously, the resolution of quantitative HRTEM is limited by the point resolution of modern microscopes that has reached 0.1 mn. However, the quantification of the information from lattice images requires two important steps, namely, the application of a pattern recognition procedure and the extraction of changes of the electron scattering potential from the lattice images. The application of the pattern recognition procedure influences the lateral resolution of the method because a lattice image has to be broken up into unit cells of identical size (figure 1).

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Boyes, E. D., J. Ringnalda, M. A. J. van der Stam, T. F. Fliervoet i E. Van Cappellen. "A 2-2-2 200kv Field Emission STEM/TEM System". Microscopy and Microanalysis 7, S2 (sierpień 2001): 232–33. http://dx.doi.org/10.1017/s1431927600027239.

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In many new application areas it is necessary to combine atomic resolution imaging with atomic level chemical and crystallographic analysis. The new applications include microbiology, nanotubes, smart materials and sensor initiatives, and the myriad semiconductor fields. Along with these there are many other valuable applications in older and more established technologies such as chemicals, catalysis, pigments and construction materials for chemical plants, airplanes, pipelines, power generation, and other aspects of societal infrastructure. Analysis down to the atomic level will help to solve recalcitrant problems and open up some reluctant opportunities in these fields. They can be very effective in resolving important and long standing issues with huge potential monetary and societal costs and benefits. Key aspects of environmentally sensitive corrosion and pollution control may also require the support of similarly sophisticated imaging and microanalysis.We think the capabilities of a new generation high performance instrument should include atomic resolution coherent TEM imaging and also incoherent atomic number (Z) contrast high angle annular dark field (HAADF) STEM imaging.

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José-Yacamán, M., M. Marín-Almazo i J. A. Ascencio. "High Resolution TEM Studies On Palladium, Rhodium Nanoparticles". Microscopy and Microanalysis 7, S2 (sierpień 2001): 1100–1101. http://dx.doi.org/10.1017/s1431927600031573.

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The field of catalysis is one of the most important areas of the nano-sciences for many years. in deed the goal of having a catalyst, with the maximum active area exposed to a chemical reaction, has produced enormous amount of research in nanoparticles. Particularly, the metal nanoparticles study is a very important field in catalysis. Electron Microscopy is one of the techniques that have played a mayor role on studding nanoparticles. Since bright field images, dark field techniques, to the high-resolution atomic images of nanoparticles and more recently the High Angle Annular dark field images or Z-contrast. However this technique provides only indirect evidence of the atomic arrangements on the particles. High Resolution Electron Microscopy (HREM) still appears as a very powerful technique to study nanoparticles and their internal structure. Among the most interesting metals to study is the palladium, which acts for instance as excellent catalyst for hydrogenation of unsaturated hydrocarbons and has many other applications such as environmental catalysts.

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Howe, J. M. "High-resolution tem of transformation interfaces in metals". Proceedings, annual meeting, Electron Microscopy Society of America 45 (sierpień 1987): 284–87. http://dx.doi.org/10.1017/s0424820100126287.

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The advent of medium and high-voltage transmission electron microscopes with point-to-point resolutions below 0.2 nm has made it possible to study transformation interfaces in metals at the atomic level. Understanding the atomic structures of these interfaces is critical to understanding microstructural development and the resulting physical and mechanical properties of metals. One area of transformation interfaces in metals that has been investigated by high- resolution transmission electron microscopy (HRTEM), is the structures of interphase boundaries of metastable aging precipitates in Al alloys. The presence of these precipitates is largely responsible for the high strengths of many Al alloys and the low atomic number of Al alloys makes them ideally suited for study by HRTEM. The results from HRTEM Investigations of transformation Interfaces in Al-2%LI-1%Cu and Al-4%Ag alloys which follow, illustrate the wealth of information that HRTEM can provide about transformation interfaces in metals.

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Murakoshi, H., M. Ichihashi i H. Kakibayashi. "A 300-kV field-emission Transmission Electron Microscope". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 936–37. http://dx.doi.org/10.1017/s0424820100129310.

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For the ultimate resolution of 0.1 nm, we have developed a 300 kV field-emission TEM (FE-TEM). Atomic resolution requires conventional TEM to have an accelerating voltage to 1MV or higher, if a thermionic electron gun is used. On the other hand, an FE-TEM allows atomic resolution at a medium accelerating voltage. A 200 kV FE-TEM with a (310)-oriented cold W field emitter has already been developed and commercially released as the Hitachi HF-2000. Its information limit is 0.155 nm.To improve the resolution of an FE-TEM, we increased the accelerating energy E from 200 keV to 300 keV to reduce the electron wavelength and the energy fraction ΔE/E. A ten-stage accelerator tube was designed to maintain stable operation at 300 kV. The external view of the accelerator tube is shown in Figure 1. It is shielded by three layers of electrodes made of permalloy to lessen the influence of the stray magnetic field.

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Mehraeen, Shareghe, Joseph T. McKeown, Pushkarraj V. Deshmukh, James E. Evans, Patricia Abellan, Pinghong Xu, Bryan W. Reed, Mitra L. Taheri, Paul E. Fischione i Nigel D. Browning. "A (S)TEM Gas Cell Holder with Localized Laser Heating forIn SituExperiments". Microscopy and Microanalysis 19, nr 2 (4.03.2013): 470–78. http://dx.doi.org/10.1017/s1431927612014419.

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AbstractThe advent of aberration correction for transmission electron microscopy has transformed atomic resolution imaging into a nearly routine technique for structural analysis. Now an emerging frontier in electron microscopy is the development ofin situcapabilities to observe reactions at atomic resolution in real time and within realistic environments. Here we present a newin situgas cell holder that is designed for compatibility with a wide variety of sample type (i.e., dimpled 3-mm discs, standard mesh grids, various types of focused ion beam lamellae attached to half grids). Its capabilities include localized heating and precise control of the gas pressure and composition while simultaneously allowing atomic resolution imaging at ambient pressure. The results show that 0.25-nm lattice fringes are directly visible for nanoparticles imaged at ambient pressure with gas path lengths up to 20 μm. Additionally, we quantitatively demonstrate that while the attainable contrast and resolution decrease with increasing pressure and gas path length, resolutions better than 0.2 nm should be accessible at ambient pressure with gas path lengths less than the 15 μm utilized for these experiments.

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Balmes, Olivier, Jan-Olle Malm, Niklas Pettersson, Gunnel Karlsson i Jan-Olov Bovin. "Imaging Atomic Structure in Metal Nanoparticles Using High-Resolution Cryo-TEM". Microscopy and Microanalysis 12, nr 2 (9.12.2005): 145–50. http://dx.doi.org/10.1017/s1431927606060119.

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It has been shown, by imaging gold (200) planes, that it is possible to achieve better than 0.20-nm structural resolution in cryo-transmission electron microscopy (cryo-TEM). This has been done using commercially available cryo equipment and using a 300-kV field emission gun (FEG) TEM. The images of 15-nm gold particles embedded in amorphous frozen water clearly show the (111) planes (separated by 0.235 nm) in gold. Fourier transform demonstrates the presence of (200) planes in the image, proving a resolution of better than 0.20 nm. The experimental results are supported by image simulations using the multislice method. These simulations suggest that it should be possible to achieve the same resolution even in smaller particles and particles of lighter elements. The crucial experimental problem to overcome is keeping the thickness of the amorphous film low and to work at low electron dose conditions.

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Kim, S., W. Wang, J. Phillips i X. Pan. "Atomic Resolution TEM Study on Quantum Dots in ZnSe/ZnTe Heterostructure". Microscopy and Microanalysis 17, S2 (lipiec 2011): 1646–47. http://dx.doi.org/10.1017/s143192761100910x.

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Hashimoto, Ai, Hideki Sako, Junichiro Sameshima, Masayuki Nakamura, Takayuki Kobayashi, Shinichi Motoyama i Yuji Otsuka. "Structural Characterization of a Ga₂O₃Epitaxial Layer Grown on a Sapphire Substrate Using Cross-Sectional and Plan-View TEM/STEM Analysis". Materials Science Forum 1004 (lipiec 2020): 505–11. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.505.

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Ga2O3 is a hopeful wide-band-gap semiconductor material for a next-generation power semiconductor. We performed crystal structure analysis on Ga2O3 film on sapphire substrate using cross-sectional transmission electron microscope (TEM) and atomic resolution plan-view scanning transmission electron microscopy (STEM). The TEM analysis suggested that the main Ga2O3 film is composed of κ-Ga2O3 or mixed crystal of κ-Ga2O3 and ε-Ga2O3. But, it is difficult to distinguish these two possibilities only by cross-sectional TEM. Contrast modulation of Ga atomic columns in the atomic resolution HAADF-STEM image showed that the main part of the Ga2O3 film was κ-Ga2O3 monolayer grown along the c-axis direction, and twins are formed.

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Schamp, C. T. "High-Resolution Metrology in the TEM". Microscopy Today 20, nr 3 (maj 2012): 46–49. http://dx.doi.org/10.1017/s1551929512000363.

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The transmission electron microscope (TEM) is well known as the technique of choice for visualization and measurement of features at near-atomic length scales, particularly for semiconductor devices. For example, a critical measurement of interest may be the thickness of the gate oxide in a transistor. The accuracy of these measurements is based on calibrated distances at each magnification. The term accuracy conveys the extent to which the measurement minimizes the difference between the measured value and the true value. The associated term precision is the closeness of agreement in a series of measurements locating the end-points of a measurement line. This article describes a method that increases the accuracy of metrology measurements applied to a high-resolution TEM image.

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Klie, Robert F., Craig Johnson i Yimei Zhu. "Atomic-Resolution STEM in the Aberration-Corrected JEOL JEM2200FS". Microscopy and Microanalysis 14, nr 1 (3.01.2008): 104–12. http://dx.doi.org/10.1017/s1431927608080136.

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We report on the performance of our aberration-corrected JEOL-JEM2200FS electron microscope. This high-resolution field-mission TEM/STEM is equipped with a Schottky field-emission gun operated at 200 kV, a CEOS probe corrector, and an in-column energy filter. We focus on the performance of the probe corrector and show that the Si [110] dumbbell structure can be routinely resolved in STEM mode with the power spectrum indicating a probe size of ~1 Å. Ronchigram analysis suggests that the constant phase area is extended from 15 mrad to 35 mrad after corrector tuning. We also report the performance of our newly installed JEOL-JEM2200MCO, an upgraded version of the JEM2200FS, equipped with two CEOS aberration correctors (and a monochromator), one for the probe-forming lens and the other for the postspecimen objective lens. Based on Young's fringe analysis of Au particles on amorphous Ge, initial results show that the information limit in TEM mode with the aberration correction (Cs= −3.8 μm) is ~0.12 nm. Materials research applications using these two instruments are described including atomic-column-resolved Z-contrast imaging and electron energy-loss spectroscopy of oxide hetero-interfaces and strain mapping of a SrTiO3tilt-grain boundary. The requirements for a high-precision TEM laboratory to house an aberration-corrected microscope are also discussed.

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Kryshtab, T., H. A. Calderon i A. Kryvko. "Microstructure Characterization of Metal Mixed Oxides". MRS Advances 2, nr 64 (2017): 4025–30. http://dx.doi.org/10.1557/adv.2017.591.

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ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

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Radmilovic, Velimir, i Michael A. O'Keefe. "Fresnel effect in high-resolution TEM imaging of small particles". Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 564–65. http://dx.doi.org/10.1017/s0424820100139196.

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It is established that analysis of Fresnel contrast visible at the edges of nanoparticles in the high resolution electron microscope provides a valuable tool for determining the size of the particles with near atomic spacing accuracy.Methods based on the Fresnel effect are enjoying increased use in the study of flat precipitates, multilayers, and grain boundaries. In profile imaging studies of solid surfaces, Fresnel effects have been observed by Marks, and by O'Keefe et al. who showed that image structure within Fresnel fringes from MgO cubes can produce “ghost” atoms far outside the specimen surface. However, consequences of the Fresnel effect appear not to have been included in the study of small particles at atomic resolution. In this work, we have used HRTEM image simulation to explore the changes in images of a nanoparticle under various imaging conditions, in particular to relate the model particle size and its apparent size as derived from the HRTEM image.

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Cho, Philip, Aihua Wood, Krishnamurthy Mahalingam i Kurt Eyink. "Defect Detection in Atomic Resolution Transmission Electron Microscopy Images Using Machine Learning". Mathematics 9, nr 11 (27.05.2021): 1209. http://dx.doi.org/10.3390/math9111209.

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Point defects play a fundamental role in the discovery of new materials due to their strong influence on material properties and behavior. At present, imaging techniques based on transmission electron microscopy (TEM) are widely employed for characterizing point defects in materials. However, current methods for defect detection predominantly involve visual inspection of TEM images, which is laborious and poses difficulties in materials where defect related contrast is weak or ambiguous. Recent efforts to develop machine learning methods for the detection of point defects in TEM images have focused on supervised methods that require labeled training data that is generated via simulation. Motivated by a desire for machine learning methods that can be trained on experimental data, we propose two self-supervised machine learning algorithms that are trained solely on images that are defect-free. Our proposed methods use principal components analysis (PCA) and convolutional neural networks (CNN) to analyze a TEM image and predict the location of a defect. Using simulated TEM images, we show that PCA can be used to accurately locate point defects in the case where there is no imaging noise. In the case where there is imaging noise, we show that incorporating a CNN dramatically improves model performance. Our models rely on a novel approach that uses the residual between a TEM image and its PCA reconstruction.

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Zhang, Daliang, Yihan Zhu, Lingmei Liu, Xiangrong Ying, Chia-En Hsiung, Rachid Sougrat, Kun Li i Yu Han. "Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials". Science 359, nr 6376 (18.01.2018): 675–79. http://dx.doi.org/10.1126/science.aao0865.

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High-resolution imaging of electron beam–sensitive materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with extremely low beam doses, the time-constrained search for crystal zone axes, the precise image alignment, and the accurate determination of the defocus value. We develop a suite of methods to fulfill these requirements and acquire atomic-resolution TEM images of several metal organic frameworks that are generally recognized as highly sensitive to electron beams. The high image resolution allows us to identify individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers. We also apply our methods to other electron beam–sensitive materials, including the organic-inorganic hybrid perovskite CH3NH3PbBr3.

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Martis, Joel, Ze Zhang, Hao-Kun Li, Ann Marshall, Roy Kim i Arun Majumdar. "Design and Construction of an Optical TEM Specimen Holder". Microscopy Today 29, nr 5 (wrzesień 2021): 40–44. http://dx.doi.org/10.1017/s1551929521001103.

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Abstract:Electron microscopy has enabled atomic resolution imaging of matter. However, unlike optical spectroscopic imaging, traditional electron microscopes provide limited spectroscopic information in terms of their energy resolution. Only recently, owing to advances in monochromated STEM-EELS, have transmission electron microscopes (TEMs) been able to attain a high energy resolution. We recently proposed combining spectrally selective photoexcitation with HRTEM to achieve sub-nanometer scale optical imaging, a technique we called photoabsorption microscopy using electron analysis (PAMELA). To realize PAMELA-TEM experimentally, we constructed a TEM holder with an optical feedthrough, capable of photoexciting materials with different wavelengths. In this article, we describe our process for designing and fabricating an optical TEM specimen holder, highlighting important aspects of the design.

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Zhang, Zhenyu, Junfeng Cui, Bo Wang, Haiyue Jiang, Guoxin Chen, Jinhong Yu, Chengte Lin i in. "In situ TEM observation of rebonding on fractured silicon carbide". Nanoscale 10, nr 14 (2018): 6261–69. http://dx.doi.org/10.1039/c8nr00341f.

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A novel approach is developed using an eyebrow hair to pick up and transfer nanowires (NWs), in order to obtain in situ transmission electron microscope (TEM) images of the rebonding and self-matching of SFs at atomic resolution.

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Takeguchi, M., T. Honda, Y. Ishida, M. Kersker, M. Tanaka i K. Furuya. "Ultrahigh-Vacuum Field-Emission Electron Microscope as Applied to Observation and Analysis of Crystal Surface". Microscopy and Microanalysis 3, S2 (sierpień 1997): 597–98. http://dx.doi.org/10.1017/s1431927600009879.

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UHV(ultrahigh-vacuum) TEM has long been used as a powerful tool for studying crystal surfaces, particularly for both the direct imaging of the surface structure and for in-situ observation of surface reaction processes with atomic resolution.This paper reports a newly developed 200kV UHV TEM equipped with a field emission gun(FEG). The instrument is designed to obtain information about elemental or bonding states of surfaces in addition to observation of surface atomic structure with high contrast. Basic performances of the UHV FE-TEM includes a specimen vacuum of 2.0X10-8Pa, probe size less than 1.0nm Ø with 0.5nA probe current, point-to-point resolution of 0.21 nm, and a lattice resolution of 0.10nm.A UHV Energy Dispersive X-ray Spectrometer (EDS) originally developed by JEOL Ltd. and a Parallel Electron Energy Loss Spectrometer (PEELS) are attached to the UHV FE-TEM, which combined with a fine focused probe of 1.Onm Ø allows atomic scale spectroscopy of surfaces.

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Lee, M. R. "Transmission electron microscopy (TEM) of Earth and planetary materials: A review". Mineralogical Magazine 74, nr 1 (luty 2010): 1–27. http://dx.doi.org/10.1180/minmag.2010.074.1.1.

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AbstractUsing high intensity beams of fast electrons, the transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) enable comprehensive characterization of rocks and minerals at micrometre to sub-nanometre scales. This review outlines the ways in which samples of Earth and planetary materials can be rendered sufficiently thin for TEM and STEM work, and highlights the significant advances in site-specific preparation enabled by the focused ion beam (FIB) technique. Descriptions of the various modes of TEM and STEM imaging, electron diffraction and X-ray and electron spectroscopy are outlined, with an emphasis on new technologies that are of particular relevance to geoscientists. These include atomic-resolution Z-contrast imaging by high-angle annular dark-field STEM, electron crystallography by precession electron diffraction, spectrum mapping using X-rays and electrons, chemical imaging by energy-filtered TEM and true atomic-resolution imaging with the new generation of aberration-corrected microscopes. Despite the sophistication of modern instruments, the spatial resolution of imaging, diffraction and X-ray and electron spectroscopy work on many natural materials is likely to remain limited by structural and chemical damage to the thin samples during TEM and STEM.

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Linck, Martin, Peter Hartel, Stephan Uhlemann, Frank Kahl, Heiko Müller, Joachim Zach, Johannes Biskupek, Marcel Niestadt, Ute Kaiser i Max Haider. "Performance of the SALVE-microscope: Atomic-resolution TEM Imaging at 20 kV". Microscopy and Microanalysis 22, S3 (lipiec 2016): 878–79. http://dx.doi.org/10.1017/s1431927616005237.

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Schabes-Retchkiman, P. S., i L. Rendon. "Observation of catalytic Cu in methanol synthesis catalysts by atomic-resolution TEM". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 4 (sierpień 1990): 284–85. http://dx.doi.org/10.1017/s0424820100174552.

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Much effort has been done for the characterization of catalysts in which CuO is found together with ZnO and ZnO/alumina, since these combinations constitute catalysts for the synthesis of methanol by the hydrogenation of carbon monoxide. Active catalysts are obtained after reduction in hydrogen at pressures between 50-100 atm and 225° to 275° C. The activity of the catalyst is largely due to the strong interaction between the CuO and ZnO phases. It is clear however that it is copper in various valence states, that is responsible for the catalytic activity, with the ZnO probably acting as both a structural and chemical promoter. However there is still controversy regarding the active sites for catalysis. Several hypotesis have been put forward: 1) The reaction occurs at isolated Cu(I) cations dissolved in the ZnO lattice. 2) The reaction occurs primarily on the metallic Cu component of the catalysts.

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Gao, Wenpei, Jianbo Wu, Xiaofeng Zhang, Aram Yoon, J. Mabon, W. Swiech, W. L. Wilson, H. Yang i Jian-Min Zuo. "Surface Atomic Diffusion Processes Observed at Milliseconds Time Resolution using Environmental TEM". Microscopy and Microanalysis 20, S3 (sierpień 2014): 1590–91. http://dx.doi.org/10.1017/s1431927614009684.

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Van Aert, S., A. J. den Dekker i D. Van Dyck. "How to optimize the experimental design of quantitative atomic resolution TEM experiments?" Micron 35, nr 6 (sierpień 2004): 425–29. http://dx.doi.org/10.1016/j.micron.2004.01.007.

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Jinschek, Joerg R., Emrah Yucelen, Bert Freitag, Hector A. Calderon i Andy Steinbach. "Still “Plenty of Room at the Bottom” for Aberration-Corrected TEM". Microscopy Today 19, nr 3 (28.04.2011): 10–14. http://dx.doi.org/10.1017/s155192951100023x.

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In his now-famous 1959 speech on nanotechnology, Richard Feynman proposed that it should be possible to see the individual atoms in a material, if only the electron microscope could be made 100 times better. With the development of aberration correctors on transmission electron microscopes (TEMs) over the last decade, this dream of microscopists to directly image structures atom-by-atom has come close to an everyday reality. Figure 1 shows such a high-resolution transmission electron microscope (HR-TEM) image of a single-wall carbon nanotube obtained with an aberration-corrected TEM. Now that atomic-resolution images have become possible with aberration-corrector technology in both TEM and STEM, we can ask ourselves if we truly have achieved the goal of seeing individual atoms. Most aberration-corrected images exhibiting atomic resolution are not distinguishing individual atoms, but columns of a small number of atoms, so despite this remarkable achievement, there is still “plenty of room at the bottom” in order to move toward seeing, counting, and quantifying individual atoms. In fact, there never has been a more exciting time for electron microscopists.

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Lechner, Lorenz, Johannes Biskupek i Ute Kaiser. "Improved Focused Ion Beam Target Preparation of (S)TEM Specimen—A Method for Obtaining Ultrathin Lamellae". Microscopy and Microanalysis 18, nr 2 (21.03.2012): 379–84. http://dx.doi.org/10.1017/s1431927611012499.

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AbstractSpecimen quality is vital to (scanning) transmission electron microscopy (TEM) investigations. In particular, thin specimens are required to obtain excellent high-resolution TEM images. Conventional focused ion beam (FIB) preparation methods cannot be employed to reliably create high quality specimens much thinner than 20 nm. We have developed a method forin situtarget preparation of ultrathin TEM lamellae by FIB milling. With this method we are able to routinely obtain large area lamellae with coplanar faces, thinner than 10 nm. The resulting specimens are suitable for low kV TEM as well as scanning TEM. We have demonstrated atomic resolution byCs-corrected high-resolution TEM at 20 kV on a FIB milled Si specimen only 4 nm thick; its amorphous layer measuring less than 1 nm in total.

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Gai, PL. "Atomic Resolution In-situ Environmental (Scanning) TEM (ES/TEM) for Probing Gas-Solid Reactions: Applications and Opportunities". Microscopy and Microanalysis 12, S02 (31.07.2006): 48–49. http://dx.doi.org/10.1017/s1431927606069546.

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Chen, James. "Advancing Single-Particle EM towards Atomic Resolution". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C854. http://dx.doi.org/10.1107/s2053273314091451.

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Recent advances in single-particle electron microscopy (EM) have enabled the structural elucidation of several macromolecular complexes at near-atomic resolution. These achievements have been assisted by both well-ordered molecular specimens and rapid improvements in the direct-electron-detection technology. However, substantial challenges remain as the research field pushes the single-particle EM imaging technique towards even higher resolution, especially on smaller and dynamic molecular assemblies. Facilitated by the state-of-the-art electron microscopes at the OHSU-FEI Living Lab, I have been conducting research on effective approaches to cryo-EM data acquisition and data analysis. For the data acquisition, the central aim is to record TEM images of minimally damaged molecular specimens (due to the high-energy electron beam) on the detector. For the data analysis, my goal is to extract the maximal amount of information from the data images (at very low signal-to-noise ratio) for unbiased particle 2D classification and 3D reconstruction. I will discuss my research effort in these areas in the context of structural biology studies.

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Isabell, T., J. Brink, M. Kawasaki, B. Armbruster, I. Ishikawa, E. Okunishi, H. Sawada i in. "Development of a 200kV Atomic Resolution Analytical Electron Microscope". Microscopy Today 17, nr 3 (maj 2009): 8–11. http://dx.doi.org/10.1017/s1551929500050045.

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Few electron optical inventions have revolutionized the TEM/ STEM as profoundly as the spherical aberration (Cs) corrector has. Characterization of technologically important materials increasingly needs to be done at the atomic or even sub-atomic level. This characterization includes determination of atomic structure as well as structural chemistry. With Cs correctors, the sub-Angstrom imaging barrier has been passed, and fast atomic scale spectroscopy is possible. In addition to improvements in resolution, Cs correctors offer a number of other significant improvements and benefits.

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Yu, Rong, Wei Zhan, Mo-Rigen He, Sirong Lu i Jing Zhu. "Direct Atomic Imaging of Oxide Surfaces". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C1614. http://dx.doi.org/10.1107/s2053273314083855.

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Surfaces of metal oxides are of crucial importance for a variety of technological applications such as heterogeneous catalysis, thin film growth, gas sensing, and corrosion prevention [1]. Due to the complexities of oxides in crystal structure and electronic structure, however, the surface science of oxides lags far behind that of metals or semiconductors. Conventional surface-science techniques, typically scanning tunneling microscopy (STM) and low energy electron diffraction (LEED), are usually limited to surfaces of single crystals with relatively simple structures. Metal oxides are usually good insulators, either band insulators or Mott insulators, making them not suitable for STM, LEED, and most of spectroscopic methods using low energy electrons as probes. On the other hand, the complex atomic structures of oxides results in too many structural parameters to be determined by spectroscopy or diffraction methods. Recent developments in high-resolution transmission electron microscopy (TEM) provide us opportunities to overcome the above difficulties. With the realization of aberration-correction, the point resolution of TEM has been improved into the milestone 1 Angstrom scale. In addition, the correction of the spherical aberration has almost eliminated the contrast delocalization in high-resolution images. Therefore, high resolution TEM becomes an even more powerful tool than before for materials research at a truly atomic-scale. Here, we will present our recent works on atomic and electronic structure of oxide surfaces [2-3]. We will show that the structure and dynamics of oxide surfaces can be directly imaged and measured at the sub-angstrom scale with an accuracy of picometers, comparable to that obtained by conventional surface science techniques on single crystals.

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Krakow, William. "In situ evaporation in a high-resolution TEM". Proceedings, annual meeting, Electron Microscopy Society of America 49 (sierpień 1991): 446–47. http://dx.doi.org/10.1017/s0424820100086532.

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In recent years there has been a growing interest in the structure and stability of small particles at the atomic resolution level. In a number of cases, metal clusters were prepared ex situ and placed in a HREM which allowed significant contamination to be present. The one successful application to in situ work has been achieved by Takayanagi and his associates who have used a narrow gap pole piece 200 kV microscope modified to UHV conditions which achieves pressures in the 10-9 Torr range. Studies with this microscope have shown small gold clusters of a few tens of atoms extending over edges of graphite surfaces and small clusters 20-30Å in lateral extent.

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Qian, M., M. Sarikaya i E. A. Stern. "Local Temperature Determination Using Elfs Spectroscopy". Microscopy and Microanalysis 3, S2 (sierpień 1997): 997–98. http://dx.doi.org/10.1017/s1431927600011879.

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ELFS spectroscopy (energy loss fine structure) is used to obtain local atomic structure information It can outperform XAFS (x-ray absorption fine structure) not only because of its low Z element sensitivity, but also because of its high spatial resolution and the capability of combining other high resolution TEM measurements. Although TEM continues to gain importance as an indispensable and unique tool to study nanoscale phenomena by providing simultaneous imaging, diffraction, and spectroscopy information, direct observation and quantitative measurements of physical phenomena are also desirable. This paper gives a first-time demonstration of such a measurement, namely local temperature determination in a TEM sample by ELFS.The principle is simple and as follows. One can measure, with ELFS, the atomic distances up to ±0.01 Å accuracy for the fist shell (typically around 2 Å ) and the second shell (around 3-4 Å). Atomic distances in a sample will change when its temperature changes, the phenomena that are coupled by the macroscopic temperature dependent lattice expansion.

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Carlino, Elvio. "In-Line Holography in Transmission Electron Microscopy for the Atomic Resolution Imaging of Single Particle of Radiation-Sensitive Matter". Materials 13, nr 6 (20.03.2020): 1413. http://dx.doi.org/10.3390/ma13061413.

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In this paper, for the first time it is shown how in-line holography in Transmission Electron Microscopy (TEM) enables the study of radiation-sensitive nanoparticles of organic and inorganic materials providing high-contrast holograms of single nanoparticles, while illuminating specimens with a density of current as low as 1–2 e−Å−2s−1. This provides a powerful method for true single-particle atomic resolution imaging and opens up new perspectives for the study of soft matter in biology and materials science. The approach is not limited to a particular class of TEM specimens, such as homogenous samples or samples specially designed for a particular TEM experiment, but has better application in the study of those specimens with differences in shape, chemical composition, crystallography, and orientation, which cannot be currently addressed at atomic resolution.

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Ishida, Y., Y. Bando, Y. Kitami, T. Tomita i M. Kersker. "Development of a 300 kV field emission TEM". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1.08.1993): 1080–81. http://dx.doi.org/10.1017/s0424820100151234.

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The 300 kV analytical electron microscope, as compared with the 100 to 200 kV instruments, have excellent features such as the high resolution of TEM images, high P/B ratio of EDS and PEELS, and high spacial resolution in analysis.We hereby report the principal specifications of an ultrahigh sensitivity and ultrahigh resolution field emission type electron microscope, which, capable of giving full play to the above-mentioned features of the 300 kV analytical instrument, allows elemental analysis at the single atomic layer level (nm regions).Its electron gun, simply operated by CPU control, allows emission current to be obtained at the touch of a single button. As the emitter, a W (100)-TF emitter, which can be used simply, stably, and for a long period of time, is employed. After build-up, this emitter can obtain about 10 times the angular current density of the W (310) emitter. Around the emitter are provided three electrodes to make emission current variation and electrostatic lens function independent of each other.

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DeRose, J. A., i J. P. Revel. "Examination of Atomic (Scanning) Force Microscopy Probe Tips with the Transmission Electron Microscope". Microscopy and Microanalysis 3, nr 3 (maj 1997): 203–13. http://dx.doi.org/10.1017/s143192769797015x.

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Abstract: We have developed a method for the examination of atomic force microscopy (scanning force microscopy) tips using a high-resolution transmission electron microscope (TEM). The tips can be imaged in a nondestructive way, enabling one to observe the shape of an atomic force microscope probe in the vicinity of the apex with high resolution. We have obtained images of atomic force microscopy probes with a resolution on the order of 1 nm. The tips can be imaged repeatedly, so one can examine tips before and after use. We have found that the tip can become blunted with use, the rate of wear depending upon the sample and tip materials and the scanning conditions. We have also found that the tips easily accrue contamination. We have studied both commercially produced tips, as well as tips grown by electron beam deposition. Direct imaging in the TEM should prove useful for image deconvolution methods because one does not have to make any assumptions concerning the general shape of the tip profile.

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Deng, Yu, Ruopeng Zhang, Jim Ciston, Karen C. Bustillo, Colin Ophus i Andrew Minor. "Atomic-resolution Probing of Anion Migration in Perovskites with In-situ (S)TEM". Microscopy and Microanalysis 27, S1 (30.07.2021): 170–71. http://dx.doi.org/10.1017/s1431927621001215.

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ABSTRACTPerovskites are promising functional materials for their optoelectronic properties and anion migration plays a key role in their functional performance [1-3]. By using in-situ (S)TEM mechanical and electrical testing in conjunction with 4D-STEM [4,5], we directly observed/probed anion migration in perovskites at atomic resolution (see Figure 1). Here, we studied the mechanism for the anion migration in perovskites such as (PbZr)TiO3 and BaTiO3, which is induced under the mechnaicl/electrical loading. To avoid the influence of the electron beam, we carried out the in-situ (S)TEM study at 60kv with low dose. And to avoid the possible strong size effect and the substrate (interface) influence, we prepared free-standing sub-micrometer single-crystalline structures to perform the experiments. Corresponding EDS and EELS examinations were performed to measure the local chemical change with applied stress and electrical currents. Our observations revealed the coexistence of multiple phase structures and hierarchical domain structures, as well as the greatly enhanced anion drifting and diffusion at the charged domain walls (Figure 2) and phase boundaries. The complex interaction between the local domain evolution and phase transition has been discussed. Based on above investigations, a model for anion migration in perovskire under mechanical/electrical loading has been presented.

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