Academic literature on the topic 'High Resolution Scanning Electron Microscopy (HRSEM)'
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Journal articles on the topic "High Resolution Scanning Electron Microscopy (HRSEM)"
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Apkarian, Robert P. "Comments on Cryo High Resolution Scanning Electron Microscopy." Microscopy Today 12, no. 1 (January 2004): 45. http://dx.doi.org/10.1017/s1551929500051841.
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Stephen Carmichael wrote about Cryoelectron Tomography in the May 2003 issue of Microscopy Today. Citing new preparation methods, small cells can be vitrified, observed frozen in the TEM and a series of digital images captured while the specimen is being rotated around the axis perpendicular to the electron beam producing a 3-D tomogram. Gina Sosinski and Maryann Martone wrote about imaging big and messy biological structures using cryo-electron Tomography in the July issue of Microscopy Today. Cryo-HRSEM now also seeks to provide 3-D information approaching the molecular level from frozen hydrated cell and molecular systems. Vitrification procedures for small specimens such as platelets and biomolecules on grids are accomplished by plunge freezing in liquefied etiiane as is done with cryo-TEM procedures. Bulk specimens such as organic hydrogels and tissues are routinely high pressure frozen (HPF) in 3mm gold planchets. Employing an in-lens cryostage, identical to those used in cryo-TEM, cryo-HRSEM provides 3-D high-resolution images because secondary electrons are efficiently collected above the lens in a single scan thus minimizing specimen irradiation.
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Vezie, Deborah L. "High-resolution scanning electron microscopy of carbon fiber." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 704–5. http://dx.doi.org/10.1017/s0424820100155499.
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As part of an extensive study of polyacrylonitrile (PAN) and mesophase pitch-based carbon fibers, high resolution scanning electron microscopy (HRSEM) is shown to provide additional insight into understanding and modelling microstructural origins of mechanical properties of carbon fiber. Although carbon fiber has been studied extensively, no sufficiently clear relationship between structure and mechanical properties such as elastic modulus and compressive strength has yet been developed from quantitative TEM and WAXS investigations.In this study, HRSEM data of selected carbon fibers is used to illustrate the power of HRSEM to elucidate structural differences likely accounting for changes in mechanical properties not sensitively probed either by TEM or WAXS. The three-dimensional nature of SEM imaging with accompanying high resolution permits a clearer visualization and more detailed examination of regional structures within carbon fiber over two-dimensional TEM and globally averaged WAXS data.The design of the high resolution, field emission SEM permits low voltage imaging of poorly conducting samples with resolution an order of magnitude greater than a conventional tungsten hairpin filament SEM under the same operating voltage and sample preparation conditions. Although carbon fiber is a relatively conductive material, charging effects can be seen in uncoated PAN fibers above 3.0 keV in a conventional SEM. Lower accelerating voltages are necessary for uncoated imaging of these fibers, but become impractical due to degradation of conventional SEM performance at these voltages. Uncoated sample imaging is preferred to prevent conventional evaporation or sputter coating techniques from obscuring or altering the sample surface, although charging effects may then be a problem. The high resolution, field emission SEM solves these competing voltage/ charging/ resolution issues for poorly conducting materials with the very nature of its design; the high brightness of the electron gun at low voltage coupled with the “in lens” sample placement and above the objective lens detector dramatically improve the resolution of these instruments, especially at low voltage.
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Cosandey, F. "High Spatial Resolution EBSD Study of Nanosized Epitaxial Particles." Microscopy and Microanalysis 3, S2 (August 1997): 559–60. http://dx.doi.org/10.1017/s1431927600009685.
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Traditionally, the structure and orientation relationship of individual catalyst particles on various oxide substrates have been studied by transmission electron microscopy. However, the combination of high resolution scanning electron microscopes (HRSEM) equipped with Schottky field emission sources with CCD cameras for recording electron backscatter diffraction (EBSD) paterns, it is now possible to obtain both morpholgy and orientation of individual particles with high spatial resolution. In this paper, we present results on the application of combined EBSD with HRSEM to determine the epitaxial orientation relationship of 80 nm Au particles on TiO2 (110). An evaluation of the spatial resolution limit of EBSD using Monte Carlo simulation of backscattered electron trajectories is also presented.The TiO2 (110) single crystal surfaces used in this study were prepared in UHV using surface science tools followed by in-situ metallization. After deposition of 15 nm Au at 300K followed by annealing at 800K, the samples were transferred in air to the Field Emission Scanning Electron microscope (LEO 982 Gemini) for high resolution imaging.
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Cosandey, F., L. Zhang, and T. E. Madey. "High Resolution Fesem Study of Au Particle Growth on TiO2." Microscopy and Microanalysis 3, S2 (August 1997): 405–6. http://dx.doi.org/10.1017/s1431927600008916.
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Transition metals supported on oxides have important catalytic properties and are also used in chemical gas sensors for increasing sensitivity and selectivity. In order to understand growth and reactivity in the Au/TiO2 system, we have performed surface studies on a model system consisting of ultrathin, discontinuous Au films on TiO2 (110) single crystals. In this paper we are presenting results obtained by high resolution scanning electron microscopy (HRSEM) on the effects of substrate temperature and average Au thickness on particle size, density and coverage.The TiO2 (110) single crystal surfaces used in this study were prepared in UHV using surface science tools followed by in-situ Au deposition for different substrate temperatures and for various film thicknesses. After deposition, the samples were transferred in air to the Field Emission Scanning Electron microscope (LEO 982 Gemini) for high resolution imaging.Typical high resolution scanning electron microscopy (HRSEM) images of Au films deposited at 300 K are shown in Fig. 1 for two film thicknesses of 0.22 and 1.0 nm.
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Chen, Ya, Geoffrey Letchworth, and John White. "Progress in high-resolution CRYO-SEM imaging of viral particles." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 818–19. http://dx.doi.org/10.1017/s0424820100166555.
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Low-temperature high-resolution scanning electron microscopy (cryo-HRSEM) has been successfully utilized to image biological macromolecular complexes at nanometer resolution. Recently, imaging of individual viral particles such as reovirus using cryo-HRSEM or simian virus (SIV) using HRSEM, HV-STEM and AFM have been reported. Although conventional electron microscopy (e.g., negative staining, replica, embedding and section), or cryo-TEM technique are widely used in studying of the architectures of viral particles, scanning electron microscopy presents two major advantages. First, secondary electron signal of SEM represents mostly surface topographic features. The topographic details of a biological assembly can be viewed directly and will not be obscured by signals from the opposite surface or from internal structures. Second, SEM may produce high contrast and signal-to-noise ratio images. As a result of this important feature, it is capable of visualizing not only individual virus particles, but also asymmetric or flexible structures. The 2-3 nm resolution obtained using high resolution cryo-SEM made it possible to provide useful surface structural information of macromolecule complexes within cells and tissues. In this study, cryo-HRSEM is utilized to visualize the distribution of glycoproteins of a herpesvirus.
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Lea, P. J., and M. J. Hollenberg. "High-resolution scanning electron microscopy (HRSEM) of mitochondria from various rat tissues." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 14–15. http://dx.doi.org/10.1017/s0424820100102158.
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Our current understanding of mitochondrial ultrastructure has been derived primarily from thin sections using transmission electron microscopy (TEM). This information has been extrapolated into three dimensions by artist's impressions (1) or serial sectioning techniques in combination with computer processing (2). The resolution of serial reconstruction methods is limited by section thickness whereas artist's impressions have obvious disadvantages.In contrast, the new techniques of HRSEM used in this study (3) offer the opportunity to view simultaneously both the internal and external structure of mitochondria directly in three dimensions and in detail.The tridimensional ultrastructure of mitochondria from rat hepatocytes, retinal (retinal pigment epithelium), renal (proximal convoluted tubule) and adrenal cortex cells were studied by HRSEM. The specimens were prepared by aldehyde-osmium fixation in combination with freeze cleavage followed by partial extraction of cytosol with a weak solution of osmium tetroxide (4). The specimens were examined with a Hitachi S-570 scanning electron microscope, resolution better than 30 nm, where the secondary electron detector is located in the column directly above the specimen inserted within the objective lens.
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Bentley, J., N. D. Evans, and E. A. Kenik. "Measurement of Scanning Electron Microscope resolution." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 1044–45. http://dx.doi.org/10.1017/s0424820100172954.
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The resolution performance of a scanning electron microscope (SEM) is a primary specification of the instrument. For a high-resolution SEM (HRSEM) equipped with a field emission gun (FEG), image resolutions of less than 2 nm are commonly claimed. Generally, both manufacturers and customers identify image resolution as the single most important performance criterion. It is traditionally determined with specimens such as gold islands on bulk carbon supports, where the minimum apparent separation of two islands is claimed as the resolution. This procedure is highly subjective since the spacings are not known independently. Dodson and Joy have pointed out the paradox implicit in this approach-that “the resolution of a given instrument can be verified only after a better instrument is available to characterize the structure spacing.” By analogy to the now standard approach for high-resolution transmission electron microscopes (TEMs), Dodson and Joy investigated the use of Fourier Transforms (FT) of high-resolution SEM images for measuring resolution.
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Apkarian, Robert P. "Introduction: High Resolution Cryo-SEM in the Biological Sciences." Microscopy and Microanalysis 9, no. 4 (August 2003): 272. http://dx.doi.org/10.1017/s143192760303054x.
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What is cryogenic high resolution (in-lens) scanning electron microscopy (HRSEM), and do I need it? Structural cell biologists and bioorganic chemists will find this newly developed imaging mode to be an accurate and useful research tool for molecular level investigations in the hydrated state.
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Simmons, S. R., S. J. Eppell, R. E. Marchant, and R. M. Albrecht. "Correlative atomic-force microscopy and high-resolution scanning electron microscopy of proteins attached to platelet surfaces." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 230–31. http://dx.doi.org/10.1017/s0424820100146990.
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The atomic force microscope (AFM) has provided images at submolecular or atomic scale resolution of biological macromolecules attached to surfaces such as mica, graphite, or synthetic phospholipid membranes. Because the AFM can be operated with the sample in air, vacuum, or immersed in a liquid such as a biological buffer, it has the potential for high resolution imaging of the structure and organization of macromolecules on surfaces of cells in the hydrated or even living state. Realization of this potential would allow observation of molecular processes at the cell surface without the necessity for preparation of the sample for electron microscopy. To date, however, the AFM has yielded images of cell surfaces only at relatively low magnifications, and has not provided the atomic resolution achieved on hard, crystalline surfaces.Previously we have utilized correlative video-enhanced light microscopy, high voltage transmission electron microscopy, and low voltage, high resolution scanning electron microscopy (HRSEM)
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Sutrisno, H., E. D. Siswani, and K. S. Budiasih. "The effect of sintering temperatures of TiO2(B)-nanotubes on its microstructure." Science of Sintering 50, no. 3 (2018): 291–98. http://dx.doi.org/10.2298/sos1803291s.
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Titanium dioxide (TiO2)-nanotubes were prepared by a simple technique reflux. The morphologies and microstructures of nanotubes were characterized by high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (TEM), powder X-ray diffraction (XRD,) energy dispersive X-ray spectroscopy (EDS) and surface area analyzer. The microstructures of TiO2 phases obtained from the sintering process of TiO2-nanotubes for 1 hour at various temperatures from 100 to 1000?C at intervals of 50?C were investigated from the XRD diffractograms. The analyses of morphologies and microstructures from HRSEM and HRTEM images describe the sample as nanotubes. The nanotube is single phase exhibiting TiO2(B) structure. The XRD patterns show that TiO2(B)-nanotubes transform into anatase phase and then become rutile due to increasing sintering temperatures.
Dissertations / Theses on the topic "High Resolution Scanning Electron Microscopy (HRSEM)"
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Kolahdouz, Esfahani Mohammadreza. "Application of SiGe(C) in high performance MOSFETs and infrared detectors." Doctoral thesis, KTH, Integrerade komponenter och kretsar, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32049.
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Epitaxially grown SiGe(C) materials have a great importance for many device applications. In these applications, (strained or relaxed) SiGe(C) layers are grown either selectively on the active areas, or on the entire wafer. Epitaxy is a sensitive step in the device processing and choosing an appropriate thermal budget is crucial to avoid the dopant out–diffusion and strain relaxation. Strain is important for bandgap engineering in (SiGe/Si) heterostructures, and to increase the mobility of the carriers. An example for the latter application is implementing SiGe as the biaxially strained channel layer or in recessed source/drain (S/D) of pMOSFETs. For this case, SiGe is grown selectively in recessed S/D regions where the Si channel region experiences uniaxial strain.The main focus of this Ph.D. thesis is on developing the first empirical model for selective epitaxial growth of SiGe using SiH2Cl2, GeH4 and HCl precursors in a reduced pressure chemical vapor deposition (RPCVD) reactor. The model describes the growth kinetics and considers the contribution of each gas precursor in the gas–phase and surface reactions. In this way, the growth rate and Ge content of the SiGe layers grown on the patterned substrates can be calculated. The gas flow and temperature distribution were simulated in the CVD reactor and the results were exerted as input parameters for the diffusion of gas molecules through gas boundaries. Fick‟s law and the Langmuir isotherm theory (in non–equilibrium case) have been applied to estimate the real flow of impinging molecules. For a patterned substrate, the interactions between the chips were calculated using an established interaction theory. Overall, a good agreement between this model and the experimental data has been presented. This work provides, for the first time, a guideline for chip manufacturers who are implementing SiGe layers in the devices.The other focus of this thesis is to implement SiGe layers or dots as a thermistor material to detect infrared radiation. The result provides a fundamental understanding of noise sources and thermal response of SiGe/Si multilayer structures. Temperature coefficient of resistance (TCR) and noise voltage have been measured for different detector prototypes in terms of pixel size and multilayer designs. The performance of such structures was studied and optimized as a function of quantum well and Si barrier thickness (or dot size), number of periods in the SiGe/Si stack, Ge content and contact resistance. Both electrical and thermal responses of such detectors were sensitive to the quality of the epitaxial layers which was evaluated by the interfacial roughness and strain amount. The strain in SiGe material was carefully controlled in the meta–stable region by implementingivcarbon in multi quantum wells (MQWs) of SiGe(C)/Si(C). A state of the art thermistor material with TCR of 4.5 %/K for 100×100 μm2 pixel area and low noise constant (K1/f) value of 4.4×10-15 is presented. The outstanding performance of these devices is due to Ni silicide contacts, smooth interfaces, and high quality of multi quantum wells (MQWs) containing high Ge content.The novel idea of generating local strain using Ge multi quantum dots structures has also been studied. Ge dots were deposited at different growth temperatures in order to tune the intermixing of Si into Ge. The structures demonstrated a noise constant of 2×10-9 and TCR of 3.44%/K for pixel area of 70×70 μm2. These structures displayed an improvement in the TCR value compared to quantum well structures; however, strain relaxation and unevenness of the multi layer structures caused low signal–to–noise ratio. In this thesis, the physical importance of different design parameters of IR detectors has been quantified by using a statistical analysis. The factorial method has been applied to evaluate design parameters for IR detection improvements. Among design parameters, increasing the Ge content of SiGe quantum wells has the most significant effect on the measured TCR value.QC 20110405
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Schroeder-Reiter, Elizabeth. "High resolution analysis of mitotic metaphase chromosomes with scanning electron microscopy." Diss., lmu, 2004. http://nbn-resolving.de/urn:nbn:de:bvb:19-27942.
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Haibo, E. "Quantitative analysis of core-shell nanoparticle catalysts by scanning transmission electron microscopy." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:19c3b989-0ffb-487f-8cb3-f6e9dea83e63.
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This thesis concerns the application of aberration corrected scanning transmission electron microscopy (STEM) to the quantitative analysis of industrial Pd-Pt core-shell catalyst nanoparticles. High angle annular dark field imaging (HAADF), an incoherent imaging mode, is used to determine particle size distribution and particle morphology of various particle designs with differing amounts of Pt coverage. The limitations to imaging, discrete tomography and spectral analysis imposed by the sample’s sensitivity to the beam are also explored. Since scattered intensity in HAADF is strongly dependent on both thickness and composition, determining the three dimensional structure of a particle and its bimetallic composition in each atomic column requires further analysis. A quantitative method was developed to interpret single images, obtained from commercially available microscopes, by analysis of the cross sections of HAADF scattering from individual atomic columns. This technique uses thorough detector calibrations and full dynamical simulations in order to allow comparison between experimentally measured cross section to simulated ones and is shown to be robust to many experimental parameters. Potential difficulties in its applications are discussed. The cross section approach is tested on model materials before applying it to the identification of column compositions of core-shell nanoparticles. Energy dispersive X-ray analysis is then used to provide compositional sensitivity. The potential sources of error are discussed and steps towards optimisation of experimental parameters presented. Finally, a combination of HAADF cross section analysis and EDX spectrum imaging is used to investigate the core-shell nanoparticles and the results are correlated to findings regarding structure and catalyst activity from other techniques. The results show that analysis by cross section combined with EDX spectrum mapping shows great promise in elucidating the atom-by-atom composition of individual columns in a core-shell nanoparticle. However, there is a clear need for further investigation to solve the thickness / composition dualism.
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Kawano, Kayoko. "Application of the ultra high resolution, low voltage scanning electron microscopy in the materials science." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/application-of-the-ultra-high-resolution-low-voltage-scanning-electron-microscopy-in-the-materials-science(341c7955-1da7-49be-9dd3-a3f3248bae05).html.
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The efficiency of low voltage scanning electron microscopy, which presents near-surface information, has been well known for a long time. However, it is not widely known that the high resolution capability can only be achieved when the surface reveals the original characteristics of the materials without any deterioration due contamination. Therefore, initial attention in this study is directed at clarifying the efficient use of the ultra high resolution, low voltage SEM (UHRLV SEM), (Ultra55, Zeiss). The SEM images and the selected electrons for detection, and damage that occurs through UHRVL SEM observation are also researched. Subsequently, the most efficient specimen preparation technique, which is appropriate for the characteristics of the individual materials, is investigated for galvanized steel, ultrasonically welded alloys of Al6111 and AZ31 alloy, Ti6Al4V alloy honeycomb structure and a ceramic sensor. The outcomes of appropriate specimen preparation technique and use of the extremely Low-Voltage below 2.0 kV, are presented in the results section. The study also presented the challenge of improving the low compositional contrast for the dissimilar materials of aluminium and magnesium, and to reduce charging effects in an insulating material comprising a ceramic sensor. As an application of the surface prepared by the process in this study, 3D tomography is also introduced.
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Cosgriff, Eireann Catherine. "Image formation mechanisms in three-dimensional aberration-corrected scanning transmission electron microscopy." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:e7ddeaf7-4d16-47d3-9248-3b2cfa7d0a6b.
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This thesis considers the theory and calculations of image formation mechanisms for various modes of three-dimensional imaging in aberration-corrected scanning transmission electron microscopy. Discrete tomography is used to determine and refine the three-dimensional structure of molecular nanowire bundles. The structure determination is expedited by the use of annular dark-field imaging, an incoherent imaging mode which provides directly interpretable images. The development of spherical aberration correctors and the subsequent reduction in probe sizes, including the depth of field, has made optical depth sectioning a feasible technique. The localisation in three dimensions of substitutional impurity atoms in zone-axis imaging is discussed. Both the channelling of the probe and the pre-focussing effect of the atomic column play an important role in determining the depth response of the impurity atom. Interband scattering within a sample is shown to be influential in imaging crystals containing dislocations and optical depth sectioning is explored as a possible option for overcoming surface relaxation effects in the imaging of screw dislocations end-on. The possibility of extending the optical depth sectioning approach using aberration-corrected scanning confocal electron microscopy is discussed. The coherent and incoherent imaging modes, involving elastically and inelastically scattered electrons respectively, are investigated.
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Knaub, Nikolai [Verfasser], and Kerstin [Akademischer Betreuer] Volz. "Structural analysis of dilute bismide alloys by means of high resolution scanning transmission electron microscopy / Nikolai Knaub ; Betreuer: Kerstin Volz." Marburg : Philipps-Universität Marburg, 2016. http://d-nb.info/1115332031/34.
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Moon, Bill. "Employment of Crystallographic Image Processing Techniques to Scanning Probe Microscopy Images of Two-Dimensional Periodic Objects." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/699.
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Thin film arrays of molecules or supramolecules are active subjects of investigation because of their potential value in electronics, chemical sensing, catalysis, and other areas. Scanning probe microscopes (SPMs), including scanning tunneling microscopes (STMs) and atomic force microscopes (AFMs) are commonly used for the characterization and metrology of thin film arrays. As opposed to transmission electron microscopy (TEM), SPMs have the advantage that they can often make observations of thin films in air or liquid, while TEM requires highly specialized techniques if the sample is to be in anything but vacuum. SPM is a surface imaging technique, while TEM typically images a 2D projection of a thin 3D sample. Additionally, variants of SPM can make observations of more than just topography; for instance, magnetic force microscopy measures nanoscale magnetic properties. Thin film arrays are typically two-dimensionally periodic. A perfect, infinite two-dimensionally periodic array is mathematically constrained to belong to one of only 17 possible 2D plane symmetry groups. Any real image is both finite and imperfect. Crystallographic Image Processing (CIP) is an algorithm that Fourier transforms a real image into a 2D array of complex numbers, the Fourier coefficients of the image intensity, and then uses the relationship between those coefficients to first ascertain the 2D plane symmetry group that the imperfect, finite image is most likely to possess, and then adjust those coefficients that are symmetry-related so as to perfect the symmetry. A Fourier synthesis of the symmetrized coefficients leads to a perfectly symmetric image in direct space (when accumulated rounding and calculation errors are ignored). The technique is, thus, an averaging technique over the direct space experimental data that were selected from the thin film array. The image must have periodicity in two dimensions in order for this technique to be applicable. CIP has been developed over the past 40 years by the electron crystallography community, which works with 2D projections from 3D samples. Any periodic sample, whether it is 2D or 3D has an "ideal structure" which is the structure absent any crystal defects. The ideal structure can be considered one average unit cell, propagated by translation into the whole sample. The "real structure" is an actual sample containing vacancies, dislocations, and other defects. Typically the goal of electron and other types of microscopy is examination of the real structure, as the ideal structure of a crystal is already known from X-ray crystallography. High resolution transmission electron microscope image based electron crystallography, on the other hand, reveals the ideal crystal structure by crystallographic averaging. The ideal structure of a 2D thin film cannot be easily in a spatially selective fashion examined by grazing incidence X-ray or low energy electron diffraction based crystallography. SPMs straightforwardly observe thin films in direct space, but SPM accuracy is hampered by blunt or multiple tips and other unavoidable instrument errors. Especially since the film is often of a supramolecular system whose molecules are weakly bonded (via pi bonds, hydrogen bonds, etc.) both to the substrate and to each other, it is relatively easy for a molecule from the film to adhere to the scanning tip during the scan and become part of the tip during subsequent observation. If the thin film array has two-dimensional periodicity, CIP is a unique and effective tool both for image enhancement (determination of ideal structure) and for the quantification of overall instrument error. In addition, if a sample of known 2D periodicity is scanned, CIP can return information about the contribution of the instrument itself to the image. In this thesis we show how the technique is applied to images of two dimensionally periodic samples taken by SPMs. To the best of our knowledge, this has never been done before. Since 2D periodic thin film arrays have an ideal structure that is mathematically constrained to belong to one of the 17 plane symmetry groups, we can use CIP to determine that group and use it for a particularly effective averaging algorithm. We demonstrate that the use of this averaging algorithm removes noise and random error from images more effectively than translational averaging, also known as "lattice averaging" or "Fourier filtering". We also demonstrate the ability to correct systematic errors caused by hysteresis in the scanning process. These results have the effect of obtaining the ideal structure of the sample, averaging out the defects crystallographically, by providing an average unit cell which, when translated, represents the ideal structure. In addition, if one has recorded a scanning probe image of a 2D periodic sample of known symmetry, we demonstrate that it is possible to use the Fourier coefficients of the image transform to solve the inverse problem and calculate the point spread function (PSF) of the instrument. Any real scanning probe instrument departs from the ideal PSF of a Dirac delta function, and CIP allows us to quantify this departure as far as point symmetries are concerned. The result is a deconvolution of the "effective tip", which includes any blunt or multiple tip effects, as well as the effects caused by adhesion of a sample molecule to the scanning tip, or scanning irregularities unrelated to the physical tip. We also demonstrate that the PSF, once known, can be used on a second image taken by the same instrument under approximately the same experimental conditions to remove errors introduced during that second imaging process. The preponderance of two-dimensionally periodic samples as subjects of SPM observation makes the application of CIP to SPM images a valuable technique to extract a maximum amount of information from these images. The improved resolution of current SPMs creates images with more higher-order Fourier coefficients than earlier, "softer" images; these higher-order coefficients are especially amenable to CIP, which can then effectively magnify the resolution improvement created by better hardware. The improved resolution combined with the current interest in supramolecular structures (which although 3D usually start building on a 2D periodic surface) appears to provide an opportunity for CIP to significantly contribute to SPM image processing.
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Akhtar, Sultan. "Transmission Electron Microscopy of Graphene and Hydrated Biomaterial Nanostructures : Novel Techniques and Analysis." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171991.
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Transmission Electron Microscopy (TEM) on light element materials and soft matters is problematic due to electron irradiation damage and low contrast. In this doctoral thesis techniques were developed to address some of those issues and successfully characterize these materials at high resolution. These techniques were demonstrated on graphene flakes, DNA/magnetic beads and a number of water containing biomaterials. The details of these studies are given below. A TEM based method was presented for thickness characterization of graphene flakes. For the thickness characterization, the dynamical theory of electron diffraction is used to obtain an analytical expression for the intensity of the transmitted electron beam as a function of thickness. From JEMS simulations (experiments) the absorption constant λ in a low symmetry orientation was found to be ~ 208 nm (225 ± 9 nm). When compared to standard techniques for thickness determination of graphene/graphite, the method has the advantage of being relatively simple, fast and requiring only the acquisition of bright-field (BF) images. Using the proposed method, it is possible to measure the thickness change due to one monolayer of graphene if the flake has uniform thickness over a larger area. A real-space TEM study on magnetic bead-DNA coil interaction was conducted and a statistical analysis of the number of beads attached to the DNA-coils was performed. The average number of beads per DNA coil was calculated around 6 and slightly above 2 for samples with 40 nm and 130 nm beads, respectively. These results are in good agreement with magnetic measurements. In addition, the TEM analysis supported an earlier hypothesis that 40 nm beads are preferably attached interior of the DNA-coils while 130 nm beads closer to the exterior of the coils. A focused ion-beam in-situ lift-out technique for hydrated biological specimens was developed for cryo-TEM. The technique was demonstrated on frozen Aspergillus niger spores which were frozen with liquid nitrogen to preserve their cellular structures. A thin lamella was prepared, lifted out and welded to a TEM grid. Once the lamella was thinned to electron transparency, the grid was cryogenically transferred to the TEM using a cryo-transfer bath. The structure of the cells was revealed by BF imaging. Also, a series of energy filtered images was acquired and C, N and Mn elemental maps were produced. Furthermore, 3 Å lattice fringes of the underlying Al support were successfully resolved by high resolution imaging, confirming that the technique has the potential to extract structural information down to the atomic scale. The experimental protocol is ready now to be employed on a large variety of samples e.g. soft/hard matter interfaces.
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Severs, John. "Microstructural characterisation of novel nitride nanostructures using electron microscopy." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:6229b51e-70e7-4431-985e-6bcb63bd99d1.
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Novel semiconductor nanostructures possess a range of notable properties that have the potential to be harnessed in the next generation of optical devices. Electron microscopy is uniquely suited to characterising the complex microstructure, the results of which may be related to the growth conditions and optical properties. This thesis investigates three such novel materials: (1) GaN/InGaN core/shell nanowires, (2) n-GaN/InGaN/p-GaN core/multi-shell microrods and (3) Zn3N2 nanoparticles, all of which were grown at Sharp Laboratories of Europe. GaN nanowires were grown by a Ni-catalysed VLS process and were characterised by various techniques before and after InGaN shells were deposited by MOCVD. The majority of the core wires were found to have the expected wurtzite structure and completely defect free – reflected in the strong strain-free photoluminescence peak –with a- and m- axis orientations identified with shadow imaging. A small component, <5%, were found to have the cubic zinc-blende phase and a high density of planar faults running the length of the wires. The deposited shells were highly polycrystalline, partially attributed to a layer of silicon at the core shell interface identified through FIB lift-out of cross section samples, and accordingly the PL was very broad likely due to recombination at defects and grain boundaries. A high throughput method of identifying the core size indirectly via the catalyst particle EDX signal is described which may be used to link the shell microstructure to core size in further studies. An n-GaN/InGaN/p-GaN shell structure was deposited by MOCVD on the side walls of microrods etched from c-axis GaN film on sapphire, which offers the possibility of achieving non-polar junctions without the issues due to non-uniformity found in nanowires. Threading dislocations within the core related to the initial growth on sapphire were shown to be confined to this region, therefore avoiding any harmful effect on the junction microstructure. The shell defect density showed a surprising relationship to core size with the smaller diameter rods having a high density of unusual 'flag' defects in the junction region whereas the larger diameter sample shells appeared largely defect free, suggesting the geometry of the etched core has an impact on the strain in the shell layers. The structure of unusual 'flag' defects in the m-plane junctions was characterised via diffraction contrast TEM, weak beam and atomic resolution ADF STEM and were shown to consist of a basal plane stacking faults meeting a perfect or partial dislocation loop on a pyramidal plane, the latter likely gliding in to resolve residual strain due to the fault formed during growth. Zn3N2 has the required bandgap energy to be utilised as a phosphor with the additional advantage over conventional materials of its constituent elements not being toxic or scarce. The first successful synthesis of Zn3N2 nanoparticles appropriate to this application was confirmed via SAD, EDX and HRTEM, with software developed to fit experimental polycrystalline diffraction patterns to simulated components suggesting a maximum Zn3N2 composition of ~30%. There was an apparent decrease in crystallinity with decreasing particle size evidenced in radial distribution function studies with the smallest particles appearing completely amorphous in 80kV HRTEM images. A rapid change in the particles under the electron beam was observed, characterised by growth of large grains of Zn3N2 and ZnO which increased with increasing acceleration voltage suggesting knock-on effects driving the change. PL data was consistent with the bandgap of Zn3N2 blue shifted from 1.1eV to around 1.8eV, confirming the potential of the material for application as a phosphor.
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Jamshidi, Zavaraki Asghar. "Engineering Multicomponent Nanostructures for MOSFET, Photonic Detector and Hybrid Solar Cell Applications." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177609.
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Silicon technologyhas been seekingfor a monolithic solution for a chip where data processing and data communication is performed in the CMOS part and the photonic component, respectively. Traditionally, silicon has been widely considered for electronic applications but not for photonic applications due to its indirect bandgap nature. However, band structure engineering and manipulation through alloying Si with Ge and Sn has opened new possibilities. Theoretical calculations show that it is possible to achieve direct transitions from Ge ifit is alloyed with Sn. Therefore, a GeSn system is a choice to get a direct bandgap. Extending to ternary GeSnSi and quaternary GeSnSiCstructures grown on Si wafers not only makes the bandgap engineering possible but also allowsgrowing lattice matched systems with different strain and bandgaps located in the infrared region. Different heterostructures can be designed and fabricated for detecting lightas photonic sensing oremitting the light as lasers. Alloying not only makes engineering possible but it also induces strain which plays an important role for electronic applications. Theoretical and experimental works show that tensile strain could increase the mobility, which is promising for electronic devices where high mobility channels for high performance MOSFETs is needed to speed up the switching rate. On the other hand, high n-doping in tensile strains in p-i-n structures makesΓ band transitions most probable which is promising for detection and emission of the light. As another benefit of tensile strain, the direct bandgap part shrinks faster than the indirect one if the strain amount is increased. To get both electronic and photonic applications of GeSn-based structures, two heterostructures (Ge/GeSn(Si)/GeSi/Ge/Si and Ge/GeSn/Si systems), including relaxed and compressive strained layers used to produce tensile strained layers, were designed in this thesis. The low temperature growth is of key importance in this work because the synthesis of GeSn-based hetrostructures on Si wafers requires low thermal conditions due tothe large lattice mismatch which makes them metastable. RPCVD was used to synthesize theseheterostructures because not only it offers a low temperature growth but also because it is compatible with CMOS technology. For utilization of these structures in devices, n-type and p-type doping of relaxed and compressive strained layers were developed. HRRLMs, HRTEM, RBS, SIMS, and FPP techniques were employed to evaluatestrain, quality, Sn content and composition profile of the heterostructures. The application of GeSn-based heterostructures is not restricted to electronics and photonics. Another application investigated in this work is photovoltaics. In competition with Si-based solar cells, which have, or areexpected to have,high stability and efficiency, thirdgeneration solar cells offer the use of low cost materials and production and can therefore be an alternative for future light energy conversion technology. Particularly, quantum dot sensitized solar cells are associated with favorable properties such as high extrinsic coefficients, size dependent bandgaps and multiple exciton generation and with a theoretical efficiencyof 44%. In this work, two categories of QDs, Cd-free and Cd-based QDs were employed as sensitizers in quantum dot sensitized solar cells (QDSSCs). Cd-based QDs have attracted large interest due to high quantum yield,however, toxicityremains still totheir disadvantage. Mn doping as a bandgap engineering tool for Cd-based type IIZnSe/CdS QDs wasemployed to boostthe solar cell efficiency. Theoretical and experimental investigations show that compared to single coreQDSSCs,typeII core-shells offer higher electron-hole separation due to efficient band alignment where the photogenerated electrons and holes are located in the conduction band of the shell and valence band of the core, respectively. This electron-hole separation suppresses recombination and by carefully designing the band alignment in the deviceit can increase the electron injection and consequently the power conversion efficiency of the device. Considering eco-friendly and commercialization aspects, three different “green” colloidal nanostructures having special band alignments, which are compatible for sensitized solar cells, were designed and fabricated by the hot injection method. Cu2GeS3-InP QDs not only can harvest light energy up to the infraredregion but can also be usedastypeII QDs. ZnS-coating was employed as a strategy to passivate the surface of InP QDs from interaction with air and electrolyte. In addition, ZnS-coating and hybrid passivation was applied for CuInS2QDs to eliminate surface traps.QC 20151125
Books on the topic "High Resolution Scanning Electron Microscopy (HRSEM)"
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Vang, R. T., S. Wendt, and F. Besenbacher. Nanocatalysis. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.12.
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This article discusses nanocatalysis and especially the interrelation between the structure, composition and properties of catalysts. It begins with a review of techniques that have been developed and employed for surface characterization, which can be divided intothree main areas: spectroscopy, diffraction, and microscopy. After describing the nanocharacterization tools, the article considers the theoretical underpinnings of catalysts and catalytic processes. It also examines how detailed atomic-scale insight into elementary surface processes relevant to catalysis can be obtained mainly by means of high-resolution scanning tunnelling microscope studies on single-crystal surfaces. More specifically, it explores the surface structure, adsorption, dissociation and diffusion, and surface chemical reactions of catalysts. The article also looks at the design of new catalysts from first principles and concludes with an assessment of nanocatalysts and transmission electron microscope studies of nanoclusters on high surface area supports.
Book chapters on the topic "High Resolution Scanning Electron Microscopy (HRSEM)"
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Lyman, Charles E., Joseph I. Goldstein, Alton D. Romig, Patrick Echlin, David C. Joy, Dale E. Newbury, David B. Williams, et al. "High-Resolution SEM Imaging." In Scanning Electron Microscopy, X-Ray Microanalysis, and Analytical Electron Microscopy, 61–66. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0635-1_11.
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Lyman, Charles E., Joseph I. Goldstein, Alton D. Romig, Patrick Echlin, David C. Joy, Dale E. Newbury, David B. Williams, et al. "High-Resolution SEM Imaging." In Scanning Electron Microscopy, X-Ray Microanalysis, and Analytical Electron Microscopy, 242–50. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0635-1_40.
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Goldstein, Joseph I., Dale E. Newbury, Joseph R. Michael, Nicholas W. M. Ritchie, John Henry J. Scott, and David C. Joy. "High Resolution Imaging." In Scanning Electron Microscopy and X-Ray Microanalysis, 147–64. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-6676-9_10.
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Brodusch, Nicolas, Hendrix Demers, and Raynald Gauvin. "Electron Detection Strategies for High Resolution Imaging: Deceleration and Energy Filtration." In Field Emission Scanning Electron Microscopy, 13–35. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4433-5_3.
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Tacke, Sebastian, Falk Lucas, Jeremy D. Woodward, Heinz Gross, and Roger Wepf. "High-Resolution Cryo-Scanning Electron Microscopy of Macromolecular Complexes." In Biological Field Emission Scanning Electron Microscopy, 265–97. Chichester, UK: John Wiley & Sons, Ltd, 2019. http://dx.doi.org/10.1002/9781118663233.ch12.
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Barton, Deborah A., and Robyn L. Overall. "Imaging Plasmodesmata with High-Resolution Scanning Electron Microscopy." In Methods in Molecular Biology, 55–65. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1523-1_3.
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Hosson, J. Th M., M. Haas, and D. H. J. Teeuw. "High Resolution Scanning Electron Microscopy Observations of Nano-Ceramics." In Impact of Electron and Scanning Probe Microscopy on Materials Research, 109–34. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4451-3_5.
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Chen, Ya, and James B. Pawley. "High Resolution Low Voltage Scanning Electron Microscopy: Reduced Radiation Damage on Cryo-specimens." In Multidimensional Microscopy, 171–90. New York, NY: Springer New York, 1994. http://dx.doi.org/10.1007/978-1-4613-8366-6_10.
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Jiang, Hao, S. S. Patnaik, P. Haaland, D. L. Vezie, T. Bunning, J. Williams, and W. Wade Adams. "Image Contrast Mechanisms and Topology of Polyethylene Single Crystals: Low-Voltage, High-Resolution Scanning Electron Microscopy and Atomic Force Microscopy." In Atomic Force Microscopy/Scanning Tunneling Microscopy, 153–65. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9322-2_16.
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Hosson, J. Th M., H. B. Groen, B. J. Kooi, and W. P. Velinga. "Metal-Ceramic Interfaces Studied with High Resolution Transmission Electron Microscopy." In Impact of Electron and Scanning Probe Microscopy on Materials Research, 135–59. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4451-3_6.
Full textConference papers on the topic "High Resolution Scanning Electron Microscopy (HRSEM)"
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Raza, Rizwan, Ghazanfar Abbas, and Bin Zhu. "GDC-Y2O3 Oxide Based Two Phase Nanocomposite Electrolytes." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33322.
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An oxide based two phase nanocomposite electrolyte (Ce0.9Gd0.1O2) was synthesized by a co-precipitation method and coated with Yttrium oxide (Y2O3). The nanocomposite electrolyte showed the significant performance of power density 750mW/cm2 and higher conductivities at relatively low temperature 550°C. Ionic conductivities were measured with electrochemical impedance spectroscopy (EIS) and DC (4 probe method). The structural and morphological properties of the prepared electrolyte were investigated by means of High Resolution Scanning Electron Microscopy (HRSEM). The thermal stability was determined with Differential Scanning Calorimetry (DSC). The particle size was calculated with Scherrer formula and compare with SEM results, 15–20 nm is in a good agreement with the SEM and X-ray diffraction (XRD) results. The purpose of the study to introduce the functional nanocomposite materials, for advanced fuel cell technology (NANOCOFC) to meet the challenges of solid oxide fuel cell (SOFC).
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Wang, Yafei, Songyan Hu, Guangxu Cheng, Zaoxiao Zhang, and Jianxiao Zhang. "Influence of Quenching-Tempering on the Carbide Precipitation of 2.25Cr-1Mo-0.25V Steel Used in Reactor Pressure Vessels." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93054.
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Abstract The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.
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Srinivasan, S. S., N. Kislov, Yu Emirov, D. Y. Goswami, and E. K. Stefanakos. "Investigation of ZnFe2O4 Nanoparticles Prepared by High Energy Milling." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11573.
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Nanoparticles of Zinc Ferrite (ZnFe2O4) prepared by both wet- and dry- high-energy ball milling (HEBM), have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), surface area and pore size distribution (BET) and wavelength-dependent diffuse reflectance and scattering turned into absorption coefficient estimation using the Kubelka-Munk theory. It was found that after 72 hours of HEBM, the particle size was decreased from 220 nm for the initial material to 16.5 nm and 9.4 nm for the wet- and dry-milled samples, respectively. The optical absorption analysis revealed that the energy gap is increased (blue shift) by 0.45 eV for wet-milled and decreased (“anomalous” red shift) by 0.15 eV for dry-milled samples of ZnFe2O4 as the particle size decreased.
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Ghose, S., K. A. Watson, D. M. Delozier, D. C. Working, J. W. Connell, J. G. Smith, Y. P. Sun, and Y. Lin. "Thermal Conductivity of Ultem™/Carbon Nanofiller Blends." In ASME 2006 Multifunctional Nanocomposites International Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/mn2006-17017.
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In an effort to improve polymer thermal conductivity (TC), Ultem™ 1000 was compounded with nano-fillers of carbon allotropes. As-received and modified multiwalled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNF) and expanded graphite (EG) were investigated. Functionalization of MWCNTs was performed to improve the TC compatibility between the resin and MWCNTs. It was postulated that this may provide an improved interface between the MWCNT and the polymer which would result in enhanced TC. The nano-fillers were mixed with Ultem™ 1000 in the melt and in solution at concentrations ranging from 5 to 40 wt%. Ribbons were extruded from the blends to form samples where the nano-fillers were aligned to some degree in the extrusion direction. Samples were also fabricated by compression molding resulting in random orientation of the nano-fillers. Thermal properties of the samples were evaluated by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analyzer (TGA). Tensile properties of aligned samples were determined at room temperature. As expected, increased filler loading led to increased modulus and decreased elongation with respect to the neat polymer. The degree of dispersion and alignment of the nanofillers was determined by high-resolution scanning electron microscopy (HRSEM). HRSEM of the ribbons revealed that the MWCNTs and CNFs were predominantly aligned in the flow direction. The TC of the samples was measured using a Nanoflash™ instrument. Since the MWCNTs and CNF are anisotropic, the TC was expected to be different in the longitudinal (parallel to the nanotube and fiber axis) and transverse (perpendicular to the nanotube and fiber axis) directions. The largest TC improvement was achieved for aligned samples when the measurement was performed in the direction of MWCNT and CNF alignment (i.e. longitudinal axis). Unaligned samples also showed a significant improvement in TC and may be potentially useful in applications when it is not possible to align the nano-filler. The results of this study will be presented.
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Thangapandian, N., S. Balasivanandha Prabu, and R. Paskaramoorthy. "Synthesis and Characterization of High Performance Polymer Nanocomposite Using Carbon Nanotubes as Fillers." In ASME 2013 International Manufacturing Science and Engineering Conference collocated with the 41st North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/msec2013-1251.
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In this work, the chemical vapour deposition (CVD) method is used for the production of carbon nanotubes (CNTs). The catalyst, Fe/MgO, was prepared through sonication technique. It was heated to 600 °C for 6 hours and this was used as the template for growing the CNTs using acetylene as carbon precursor. The deposited CNTs were separated by acid treatment followed by air oxidation. The purified CNTs were examined by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The CNTs were observed to have a multi-wall structure with the diameter in the range of 10–20 nm. These multiwalled carbon nanotubes (MWCNTs) were used as filler material in an epoxy matrix. Sonication technique was used to achieve uniform dispersion of CNTs within the matrix. The CNT/epoxy nanocomposite was cured at a temperature of 100 °C for 3 hours. Tensile strength, flexural strength, fire retardant properties and surface conductivity were studied. The results reveal that addition of MWCNTs to the epoxy promotes substantial improvement to the above mentioned properties.
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Abbas, Ghazanfar, Rizwan Raza, Muhammad Ashraf Chaudhry, and Bin Zhu. "Preparation and Characterization of Nanocomposite Calcium Doped Ceria Electrolyte With Alkali Carbonates (NK-CDC) for SOFC." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33325.
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The entire world’s challenge is to find out the renewable energy sources due to rapid depletion of fossil fuels because of their high consumption. Solid Oxide Fuel Cells (SOFCs) are believed to be the best alternative source which converts chemical energy into electricity without combustion. Nanostructured study is required to develop highly ionic conductive electrolyte for SOFCs. In this work, the calcium doped ceria (Ce0.8Ca0.2O1.9) coated with 20% molar ratio of two alkali carbonates (CDC-M: MCO3, where M = Na and K) electrolyte was prepared by co-precipitation method in this study. Ni based electrode was used to fabricate the cell by dry pressing technique. The crystal structure and surface morphology was characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM). The particle size was calculated in the range of 10–20nm by Scherrer’s formula and compared with SEM and TEM results. The ionic conductivity was measured by using AC Electrochemical Impedance Spectroscopy (EIS) method. The activation energy was also evaluated. The performance of the cell was measured 0.567W/cm2 at temperature 550°C with hydrogen as a fuel.
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Pan, Liming, Ben Dawson, Jacqueline Krim, Colin Baker, James Pearson, Mohammed Zikry, and Andrey Vovoedin. "Nanoscale Design of Adaptive Tribological Coatings." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71196.
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We report a joint theoretical and experimental study of the tribological properties of gold-yttrium stabilized zirconia (YSZ) based nanocomposite coatings, with a focus on the role of nanocrystalline grain size. Nanocomposites hold great promise for space and ambient applications, on account of their ability to adapt to and exhibit low friction and wear rates in constantly varying environmental conditions. Their internal structure has been the topic of prior literature, but the impact of grain size on tribological performance has heretofore not been considered, and the surface topology has not been reported. As such, we have performed both experimental and theoretical studies, to model the impact of grain size on film stress and wear attributes, and to document surface region grain size distributions through scanning tunneling microscopy (STM) measurements of self-affine fractal scaling properties. Nanocrystalline gold crystal sizes, as determined from STM and x-ray diffraction (XRD) data are consistent with those inferred from high resolution transmission electron microscopy (HRTEM) measurements. Our modeling results associate smaller grain sizes with lower wear rates, consistent with experiments. The findings show promise for nanoscale customization of coatings so as to tailor them at the nanoscale in an application specific manner.
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Franco, Egberto Gomes, Paulo Lucas Dantas Filho, Carlos Eduardo Rollo Ribeiro, Geraldo Francisco Burani, and Marcelo Linardi. "Proton Exchange Membrane Fuel Cell Catalyst: Synthesis and Characterization." In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65068.
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Fuel cells are a promising technology to deal with energy sustainability, especially for mobility purposes the Proton Exchange Membrane Fuel Cell and hydrogen produced from biomass could be coupled to overcome the amount of CO2 emissions. In order to improve fuel cells performances the search for new electrocatalysts has a great importance in this technology the challenge for a fuel cell catalyst that is less poisoned by CO is one of the most important field in low temperature fuel cell developments that use alcohol and hydrocarbons as primary fuels. In this work PtSm, PtTb, PtDy, PtU, PtRuMo and PtRuDy systems have been synthesized by the colloid method, investigated by the following techniques: X-rays fluorescence analysis (XFA), X-rays powder diffraction (XRD), X-rays photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV) and polarization curves (Exi). The results obtained in this work shows that PtRuMo is the best choice for direct methanol oxidation. For direct ethanol oxidation the higher activity was found in PtRuDy system. PtU system was investigated and showed an interesting behaviour in ethanol oxidation. After two cycles of H2/O2 and ethanol/O2 the catalyst was able to reach the initial figures on hydrogen/oxygen oxidation which means that no degradation of the catalyst was indentified.
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Young, Richard, Sander Henstra, Jarda Chmelik, Trevor Dingle, Albert Mangnus, Gerard van Veen, and Ingo Gestmann. "XHR SEM: enabling extreme high resolution scanning electron microscopy." In SPIE Scanning Microscopy, edited by Michael T. Postek, Dale E. Newbury, S. Frank Platek, and David C. Joy. SPIE, 2009. http://dx.doi.org/10.1117/12.824749.
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Roussel, Laurent Y., Debbie J. Stokes, Ingo Gestmann, Mark Darus, and Richard J. Young. "Extreme high resolution scanning electron microscopy (XHR SEM) and beyond." In SPIE Scanning Microscopy, edited by Michael T. Postek, Dale E. Newbury, S. Frank Platek, and David C. Joy. SPIE, 2009. http://dx.doi.org/10.1117/12.821826.
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