bluuebunny/crossref_metadata_2025_split huggingface dataset:
Attachment of oral bacteria to titanium surfaces: An SEM study
Authors: Laffoon J. E. , Anderson R. L. , Keller J. C. , Wu-Yuan C. D. 
Published: June 2020

Titanium (Ti) dental implants have been used widely for many years. Long term implant failures are related, in part, to the development of peri-implantitis frequently associated with bacteria. Bacterial adherence and colonization have been considered a key factor in the pathogenesis of many biomaterial based infections. Without the initial attachment of oral bacteria to Ti-implant surfaces, subsequent polymicrobial accumulation and colonization leading to peri-implant disease cannot occur. The overall goal of this study is to examine the implant-oral bacterial interfaces and gain a greater understanding of their attachment characteristics and mechanisms. Since the detailed cell surface ultrastructure involved in attachment is only discernible at the electron microscopy level, the study is complicated by the technical problem of obtaining titanium implant and attached bacterial cells in the same ultra-thin sections. In this study, a technique was developed to facilitate the study of Ti implant-bacteria interface.Discs of polymerized Spurr’s resin (12 mm x 5 mm) were formed to a thickness of approximately 3 mm using an EM block holder (Fig. 1). Titanium was then deposited by vacuum deposition to a film thickness of 300Å (Fig. 2).
A new computer-powered TEM with unique imaging capabilities
Authors: Benner G. , Frey J. , Rosβ-Meβemer M. , Probst W. 
Published: June 2020

1. IntroductionA modern electron microscope designed for routine operation must provide user-friendly operation and a high degree of automation without compromising its imaging performance. Adequate computerization of the system is the way to achieve this goal. Up to now even the most advanced computer controlled microscopes can set important parameters like the magnification, the image brightness or the image orientation only in discrete steps. In the new Zeiss EM 906 continuous adjustment of these parameters has been realised for the first time by means of realtime computer interpolation of the lens excitations between the discrete lens current combinations corresponding to the discrete parameter settings.2. Computer architecture of the microscopeThe computer network comprises a DOS-compatible system (host) computer, four subsystems controlled by separate microprocessor and a flexible data and program memory. The integrated system computer controls the electron optics while the gun, the goniometer, the camera and the vacuum system are controlled and monitored by autonomous microprocessor systems, which are connected to the host computer for data transfer via interrupt-controlled parallel interfaces.
{10}<110> edge dislocations in YSZ films grown on (100)MgO by PLD
Authors: Heffelfinger Jason R. , Carter C. Barry 
Published: June 2020

Yttria-stabilized zirconia (YSZ) is currently used in a variety of applications including oxygen sensors, fuel cells, coatings for semiconductor lasers, and buffer layers for high-temperature superconducting films. Thin films of YSZ have been grown by metal-organic chemical vapor deposition, electrochemical vapor deposition, pulse-laser deposition (PLD), electron-beam evaporation, and sputtering. In this investigation, PLD was used to grow thin films of YSZ on (100) MgO substrates. This system proves to be an interesting example of relationships between interfaces and extrinsic dislocations in thin films of YSZ.In this experiment, a freshly cleaved (100) MgO substrate surface was prepared for deposition by cleaving a lmm-thick slice from a single-crystal MgO cube. The YSZ target material which contained 10mol% yttria was prepared from powders and sintered to 85% of theoretical density. The laser system used for the depositions was a Lambda Physik 210i excimer laser operating with KrF (λ=248nm, 1Hz repetition rate, average energy per pulse of 100mJ).
TEM studies of modified lead zirconate titanate ceramics
Authors: Viehland Dwight. , Xu Z. , Dai X. H. 
Published: June 2020

The microstructural, structural, dielectric, and polarization properties of antiferroelectric PZST and PLZT ceramics have been studied as a function of Sn and La-contents, respectively. These materials are of interests for applications as antiferroelectric-ferroelectric phase switching actuators, however their transformational characteristics are currently unknown. In these systems, various ferroelectric and antiferroelectric phases have been reported over a narrow compositional range. These include: antiferroelectric orthorhombic, antiferroelectric tetragonal, rhombohedral ferroelectric, multi-cell cubic paraelectric, and single-cell cubic paraelectric. Dielectric anomalies are not observed at the ferroelectric to antiferroelectric or antiferroelectric to multicell cubic transformations. The maximum dielectric constant is found near the temperature of the formation of the multicell cubic state, which is ˜30°C above the transformation into the antiferroelectric tetragonal state. No macroscopic symmetry changes are observed near the temperature of the dielectric maximum.The compositional systems investigated in this study were (Pb1-xLax)(Zr1-yTiy)O3 (PLZT x/(1-y)/y) and Pb(0.98)Nb0.02[(Zr1-x,Snx)1-yTiy]1-zO3 (PZST x/y/2). The compositions chosen for study were PLZT 0/95/, 1/95/5, 2/95/5, 3/95/5 and 5/95, and PZST 45/0/2, 45/3/2, 45/6/2, and 45/9/2.
Epitaxial ferroelectric thin films
Authors: Ghonge S. G. , Goo E. , Ramesh R. , Haakenaasen R. , Fork D. K. 
Published: June 2020

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.
High-Resolution Electron Microscopy of condensed clusters in a potassium barium oxomolybdate
Authors: Ramlau R. , Schimek G. L. , McCarley R. E. , Simon A. 
Published: June 2020

The recently synthesized compound K0.19Ba3.81Mo22O34 is a representative of the ternary and quaternary reduced molybdenum oxides in which clusters built from molybdenum octahedra are arranged in layers of composition AxByMo4n+2O6n+4. The number of trans-edgesharing molybdenum octahedra in the cluster is represented by n. The general concept of cluster condensation is formulated and discussed elsewhere. For K0.19Ba3.81Mo22O34, n is equal to 5. A ternary representative, likewise with n = 5, is In6Mo22O34.By x-ray structure analysis, K0.19Ba3.81Mo22O34 proved to crystallize in space group P21/a with parameters a = 0.9908(2) nm, b = 0.9353(2) nm, c = 1.5951(3) nm, and β = 98.78(2)°. The potassium atoms were found to reside on the same sites as the barium atoms with an almost statistical distribution.We studied K0.19Ba3.81Mo22O34 by high-resolution electron microscopy (HREM). Small fragments of a crystal were investigated using a Philips CM30/ST microscope operating at 300 kV (point resolution 0.19 nm). At appropriate orientations of the crystal fragments, HREM images reveal domains of two ordered polytypes: a monoclinic and an orthorhombic one (Figs. 1 and 2).
Investigations using wide-angle electron diffraction on pair ordering mechanisms in FeTb alloys by thermal annealing
Authors: Tewes M. , Zweck J. , Hoffmann H. 
Published: June 2020

In our recent work we have shown that electron diffraction is a suitable and precise method to observe short range ordering in various amorphous FeTb alloys by calculating pair distribution functions (PDFs) from these data by means of a fourier inversion. A PDF g(r) is an autocorrelation function of the specimen’s density fluctuations: g(r) = 4πr(ϱ(r) - ϱo) with ϱ(r): autocorrelation of the local density in a distance r, and ϱo macroscopic density of the specimen. The spatial resolution that can be achieved is better than 0.02 nm, and the fine structure of the first coordination shell of the short range order has been described quantitatively with an isotropic structure model. The deviation between calculated and measured PDFs has been about 2%.However, the origin of the uniaxial perpendicular anisotropy in rare earth / transition metal amorphous alloys like FeTb is in general attributed to small anisotropic concentration fluctuations on an atomic scale as introduced in pair ordering, band orientation or stress induced anisotropy models.
Analysis of vacuum- and beam-sensitive pharmaceutical compounds in the EM
Authors: Neilly J. P. , Zaluzec N. J. , Meyer G. A. , Miller M. F. 
Published: June 2020

When very small amounts of a chemical compound are available for analysis or the compound is impure, analytical electron microscopy may be the method of choice for studying its physical and chemical characteristics. Before a compound is analyzed in the transmission electron microscope (TEM) it is desirable to assess its behavior in die high vacuum and ionizing radiation of the microscope. In this paper we describe a systematic approach for determining the response of a pharmaceutical compound to the effects of high vacuum and ionizing electron radiation as well as techniques used to stabilize the material in the microscope.Vacuum stability of a hydrated compound was evaluated through weighing experiments to determine if the water of hydration was removed. Known amounts of the compound were placed in the specimen chamber of a Philips 501 SEM for periods of 0.25, 0.5, 1, 2, 5 and 17 hours. The powders were then removed, reweighed and changes in weight were recorded.
Orientation imaging microscopy: Monitoring residual stress profiles in single crystals using an image-quality parameter, IQ
Authors: Wardle S. T. , Lin L. S. , Cetel A. , Adams B. L. 
Published: June 2020

Residual stresses are routinely calculated in polycrystalline materials from the residual strains determined by x-ray diffraction (XRD) analysis. Using XRD to determine residual stresses is a well-established technique, however it cannot be used for single crystals. This investigation develops a technique that readily monitors residual deformation profiles in single crystals. The technique is of particular interest to the aerospace industry as it enables the effectiveness of shot-peening single crystal turbine blades to be monitored.Electron Back-Scattered Patterns (EBSPs) can readily be obtained from electropolished single crystals using a scanning electron microscope (SEM) in spot mode. EBSPs from cold worked metals will be of poorer quality than EBSPs from undeformed metal. Likewise the EBSPs obtained from an electropolished section cut perpendicular to a shot-peened surface will show an increase in image quality with increasing distance from the worked surface (Fig. 1). This trend could easily be monitored in single crystals by quantifying the image quality of the associated EBSPs using orientation imaging microscopy (OIM).
On the determination of stacking-fault energy from dislocation nodes observed by TEM
Authors: Ferreira Paulo J. 
Published: June 2020

A fundamental understanding of the mechanical and physical behaviour of metals requires a knowledge of the stacking-fault energy (SFE). This aspect is important because the possibility of cross-slip and thus plastic deformation is a function of the SFE of the material. Impurities may segregate to the faults and change the SFE, which may affect the mechanical behaviour. For low SFE’s materials, the SFE can be determined rather accurately from transmission electron microscopy evaluation of the radius of curvature of dislocation nodes formed by the attractive interaction of dislocations (Fig. 1).This work is directed towards applying the T.E.M. technique to determine the SFE of a 310S stable austenitic stainless steel. The specimens were observed in a JEOL 4000 microscope operated at an accelerating voltage of 200 kV, and equipped with a double tilt stage. Conventional two beam bright field images were used to determine the Burgers vector and line direction of the partial dislocations.
TEM examination of hardening and toughening phenomena in a ultrahigh-strength steel
Authors: Ayer Raghavan , Machmeier P. M. 
Published: June 2020

During the development of the popular ultrahigh strength AF1410 steel, Machmeier, et.al., observed that a small variation in the chromium content had a significant improvement on the toughness of the steel in the quenched and tempered condition. The present TEM study was directed at examining the microstructural basis for this toughness enhancement.The following samples of AF1410 type steels with two levels of chromium were examined:
Steel A: 0.16%C, 10.02%Ni, 2.97%Cr, 1.21 %Mo, 13.74%Co and bal. Fe
Steel B: 0.16%C, 10.15%Ni, 1.95%Cr, 0.98%Mo, 13.8% Co and bal. Fe.
Steel A represents the composition of AF1410 while steel B had the same base composition except for 1% higher chromium.Figure 1 shows the strength and toughness of steels A and B when tempered in the range of 400-600°C. The yield strengths of the two steels were comparable over most of the tempering range; however, the toughness of steel B, measured by Charpy V notch impact test, was superior in the range of 482 - 538°C.
Nanoanalysis of precipitation in a modified Inconel 718 alloy
Authors: Liu J. , Dong J. X. , Chen M. Z. , Xie X. S. 
Published: June 2020

The nickel-base superalloy Inconel 718 (IN718) is strengthened primarily by precipitation of two types of intermetallic phases in the austenite (γ) matrix: metastable γ' (cubic Ll2 structure) and γ" (tetragonal D022 structure) precipitates. Minor changes of the chemistry of the IN718 alloy can significantly affect its mechanical properties at high temperatures. It has been found that the microstructural stability of the precipitates and the high temperature performance of IN718 depend critically on the (Ti+Al)/Nb and Al/Ti ratios. The small sizes of these intermetallic phases and the fact that γ' precipitates are frequently associated with γ" precipitates in modified IN718 make it difficult to determine their composition. In this study, nanometer resolution analytical electron microscopy techniques have been used to characterize the structure, the morphology and the composition of the precipitated phases.The fabrication and the heat treatment of the modified IN718 alloy and its high temperature mechanical properties have been reported elsewhere.
Alignment mark materials for projection electron lithography
Authors: Farrow R. C. , Liddle J. A. , Berger S. D. , Huggins H. A. , Kraus J. S. , Camarda R. M. , Tarascon R. G. , Fetter L. 
Published: June 2020

Recent advances in projection electron lithography have led to the development of a non-imaging mark detection scheme for alignment and registration that uses backscatter electron (BSE) contrast. The detection scheme is referred to as the beamlet method and uses the measured BSE emission to detect the correct alignment condition when the image of a mask mark is scanned over a corresponding wafer mark When applied to a SCALPEL system (i.e. SCattering with Angular Limitation in Projection Electron Lithography) mark detection accuracy of better than 10 nm has been reported. Incident electrons with approximately 100 keV energy will be used in a practical SCALPEL lithography tool. In this study we compare theoretical BSE ratios with quantitative measurements in a prototype SCALPEL machine. From these results we are able to predict the suitability of materials used for conductive links in very large scale integrated (VLSI) circuits.The theory for BSE emission from thin deposited films has been developed from work on thin self supporting films.
Quantitative HREM using non-linear least-squares methods
Authors: King Wayne E. , O’Keefe Michael A. , Campbell Geoffrey H. 
Published: June 2020

Non-linear least-squares methods have been coupled with high resolution image simulation to determine the critical electron microscopic imaging parameters, such as thickness and defocus, from an experimental image. The method has been extended to include the optimization of atomic column positions and occupancy to determine atomic structure. As an example, the method has been applied to the refinement of the atomic structure of a Σ5(310)/[001] grain boundary in Nb.In the past, high resolution electron microscopy has been applied in a primarily qualitative manner through the visual comparison of experimental images with simulated images. The potential for more quantitative analysis has been pointed out and recently, increasing attention is being given to more quantitative matching of experiment with simulation. Emphasis is being placed on the deduction of imaging parameters and/or the refinement of atomic structures from experimental images.In this paper, we describe an approach to the optimization of the critical electron-optical imaging parameters of an experimental image and the atomic structure of a crystalline defect, namely a grain boundary.
Quantitative HREM analysis of planar defects in high-pressure synthesized infinite-layer superconductor
Authors: Zhang Hong , Marks L. D. , Wang Y. Y. , Zhang H. , Dravid V. P. , Han P. , Payne D. A. 
Published: June 2020

Planar defects in the infinite-layer (Sr1-xCax)1-yCuO2 structure (planar CuO2 sheets separated by single Sr and Ca cations) have been suggested to be responsible for superconductivity with Tc up to about 110K. It is therefore important to understand the details of these defects at the atomic scale. In this work, we have used high resolution transmission electron microscopy to identify these defects and χ2 minimizations to best fit the experimental images; an optimized structure model from these studies is proposed.Thin samples of the infinite layer superconductor with the nominal chemical formula (Sr1-xCax)1-y CuO2 (x=0 and 0.3; y=0.9, 1.0 and 1.1) synthesized by high pressure treatment were prepared using a combination of mechanical polishing, dimpling and ion milling techniques. Through focal (10 nm steps) [100] HREM images of the defects (Fig. 1) were obtained on a 300kV Hitachi H-9000 microscope. HREM image simulations were carried out using NUMIS software and these were quantitatively compared against the experimental images using conventional χ2 minimizations with SEMPER software.
HREM analysis of a Σ5 (210) grain boundary in rutile
Authors: Paciornik S. , Dahmen U. , Solorzano I. G. , Vandersande J. B. 
Published: June 2020

The present investigation combines HREM with image processing and simulation to determine both the atomic and the step structure of a near-Σ5 (210) symmetrical grain boundary in TiO2 (rutile), produced by melt growth from an oriented bicrystal seed.Figure 1a shows a HREM image of the boundary taken near -69nm defocus (dark atomic columns). The boundary makes an angle of about 5° with the horizontal symmetry plane . In this view five flat terraces separated by steps are apparent. The atomic structure within an individual terrace is shown at higher magnification in figure 2a. From this image it is clear that the terrace is a (210) 53.1° [001] symmetrical tilt boundary of the Σ5 coincident site lattice. In figure 2a two structural unit patterns are outlined. These patterns are distinctly different from either crystal and thus characteristic of the interface. To find similar units and to measure their degree of similarity and location, a cross correlation (CC) map between figure 2a and each of the patterns was calculated using a real-space template matching technique.
Characterization of GaAs/AlGaAs quantum wells and quantum wires by chemical lattice imaging
Authors: Carlsson A. , Malm J.-O. , Gustafsson A. 
Published: June 2020

In this study a quantum well/quantum wire (QW/QWR) structure grown on a grating of V-grooves has been characterized by a technique related to chemical lattice imaging. This technique makes it possible to extract quantitative information from high resolution images.The QW/QWR structure was grown on a GaAs substrate patterned with a grating of V-grooves. The growth rate was approximately three monolayers per second without growth interruption at the interfaces. On this substrate a barrier of nominally Al0.35 Ga0.65 As was deposited to a thickness of approximately 300 nm using metalorganic vapour phase epitaxy . On top of the Al0.35Ga0.65As barrier a 3.5 nm GaAs quantum well was deposited and to conclude the structure an additional approximate 300 nm Al0.35Ga0.65 As was deposited. The GaAs QW deposited in this manner turns out to be significantly thicker at the bottom of the grooves giving a QWR running along the grooves. During the growth of the barriers an approximately 30 nm wide Ga-rich region is formed at the bottom of the grooves giving a Ga-rich stripe extending from the bottom of each groove to the surface.
Investigations on electric charging by electron holography
Authors: Frost B. , Joy D. C. , Voelkl E. 
Published: June 2020

The electric charging of latex spheres was investigated by electron holography using a Hitachi HF-2000 field emission electron microscope. In order to get fringe spacings smaller than 1/20 of the diameter of the spheres (0.264 μm and 2.68 μm) and interference widths of at least twice the sphere diameter, we used different magnification modes. The low magnification mode was achieved by switching off the objective lens and imaging the specimen by the intermediate lens. For higher magnifications the specimen was imaged by the objective lens which operated as an electron optical magnifier, i.e. the front focal plane was situated above the specimen.For easiest interpretation of the reconstructed phase distributions, a high symmetry of the sample is of advantage. Therefore we eliminated any unknown electric interaction between a supporting film and the charged sphere by placing the sphere at the edge of a bar of the copper grid. In that case the charge image method can be used as a simple model to evaluate the distribution of the electric potential.
Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films
Authors: Lee J. L. , Weiss C. A. , Buhrman R. A. , Silcox J. 
Published: June 2020

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.