bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffraction contrast and defect symmetry
Authors: Katerbau K.-H. 
Published: June 2020

Symmetry rules for the bright-field images of lattice defects were derived by Howie and Whelan /1 /, and for the dark-field images by Pogany and Turner /2/. In both cases, only one of the N diffracted beams is considered, and no statement is made on how the intensities of the other beams are affected by defect symmetry. This question is studied in the present paper.We make use of the column approximation and assume a centro-symmetric crystal and N reflections gn (n=o,...N-1 with go=o), lying in the same reciprocal lattice plane.A cartesian coordinate system (x,y,z) is introduced with the x- and y-axes in this plane and the origin in the centre of the lattice defect, located at a distance zo below the upper foil surface, t is the foil thickness, R(x,y,z) the displacement field of the defect with the abbreviation. R(z) for the displacement field at the column (x,y), and k = (kx, ky ) is the component of the wave vector of the incident electron beam in the (x,y)- plane. k=-gj/2 means that g. is in the Bragg reflecting position.
On the optimisation of methods for the computation of many-beam structure images
Authors: Van Dyck D. 
Published: June 2020

The necessity to calculate structure images for the interpretation of high-resolution electron micrographs has often been emphasized However, when large unit cells and/or heavy atoms are involved, the number of beams used for the calculations has to be increased to the order of 1000-10000, whereas an accurate simulation of the beam divergence drastically augments the computing time [11], For these reasons the computational techniques used hitherto, require fairly high computer facilities.On the other hand because of the availability of mini laboratory computers [≤32k words] in most laboratories nowadays, an image calculation program that could be performed on such a computer with sufficient speed to allow direct feedback, would be very welcome. We searched in this work for optimal computational techniques that meet these requirements without loss of generality. The investigation was carried out in four distinct steps.1. Basic expressionIt was previously shown [5,6] that, when backscattered electrons are neglected, which is a valid assumption [7], all the existing dynamical diffraction formulations can be reduced to a formal expression for Φ[z], the vector of the diffraction amplitudes as a function of the crystal depth:with the boundary condition Φ(o) =T represents the diagonal propagation matrix with components T, where s is the excitation error.
Computer simulation of phase of contrast of cluster atoms on support film made by sputter deposition
Authors: Oikawa Tetsuo , Ishigaki Fumiko , Fukuyama Shuhei , Wakizaka Haruo , Hojou Kiichi , Kanaya Koichi 
Published: June 2020

Based on the image formation theory, the wave function of a single atom consisting of the complex scattering amplitude |f(0)|exp{-inj(0)} and phase shift γj of spherical aberration is rigorously obtained by the Kirchhoff diffraction integral in the Fraunhofer approximation as a function of defocus. Using of the wave function w(υj,γj) of a group of atoms, which is extended the wave function of a single atom, variations of imaging phase contrast of tungsten support film in through focal series made by sputter deposition are simulated. The contrast of tungsten support film and a gold cluster atoms on the substrate made by sputter depposition, which are very close with the experiment, are calculated by the Monte-Carlo method with the aid of the inter-atomic size distribution measured by electron diffraction pattern.The contrast g for cluster atoms has been calculated by integrating the scattering wave for coherent waves, and for incoherent waves the amplitude scattered outside the limiting angle α set by the aperture respectively,
Optical filtering of images of dislocation core
Authors: Desseaux J. , D'anterroches C. , Penisson J.M. , Renault A. 
Published: June 2020

The optical analysis of images obtained with electron microscopes has been widely developed for structural determination of periodic biological objects and for microscope aberration correction in images of periodic or non periodic objects.Our present purpose is to improve the signal to noise ratio of high resolution micrographs of crystal defects recorded at the Scherzer focalus with the 500 kV Kyoto electron microscope. It is not necessary to correct for sign reversals since the microscope transfer function has the same sign over the 0.13 Å-1 - 0.4 Å-1 spatial frequency domain. Our images are noisy due to photographic or electron processes and to object contamination. Thus a simple binary amplitude filter is placed in the optical Fourier transform plane of the object to remove the noise. As the mask shape has a great influence on the information contained in the reconstructed image we have tested the restoration of two nearly similar dislocation cores with two different masks.
Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM
Authors: Ishida Y. , Ishida H. , Kohra K. , Ichinose H. 
Published: June 2020

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.
A method for burgers vector characterization in minerals
Authors: Gandais M. , Willaime C. 
Published: June 2020

In some minerals, little is known about slip systems ; then the characterization of dislocation Burgers vector is important in the study of their deformation. However, the classical method which involves extinction conditions = 0 with is often unrelevant : the diffracting vectors with a high structure factor which are used for two-beam case images, generally correspond to high indices so that in = 0 cases, the values are high (about 2 or 3), then the dislocation contrasts remain important.Contrast simulations of inclined dislocations through crystal foils, derived from HEAD method were performed. The determination of can be achieved through comparisons between a set of several -micrographs and a set of corresponding -simulations assuming different hypothesis upon . If the method is used without any crue, a lot of simulations are needed due to the generally strong dependance of contrast features upon parameters which cannot be measured with a good accuracy.
Electrochemical nucleation and growth of copper on iron and aluminum: A TEM study of industrial copper cementation
Authors: Murr L.E. , Annamalai V. 
Published: June 2020

Georgius Agricola in 1556 in his classical book, “De Re Metallica”, mentioned a strange water drawn from a mine shaft near Schmölnitz in Hungary that eroded iron and turned it into copper. This precipitation (or cementation) of copper on iron was employed as a commercial technique for producing copper at the Rio Tinto Mines in Spain in the 16th Century, and it continues today to account for as much as 15 percent of the copper produced by several U.S. copper companies.In addition to the Cu/Fe system, many other similar heterogeneous, electrochemical reactions can occur where ions from solution are reduced to metal on a more electropositive metal surface. In the case of copper precipitation from solution, aluminum is also an interesting system because of economic, environmental (ecological) and energy considerations. In studies of copper cementation on aluminum as an alternative to the historical Cu/Fe system, it was noticed that the two systems (Cu/Fe and Cu/Al) were kinetically very different, and that this difference was due in large part to differences in the structure of the residual, cement-copper deposit.
Surface study by UHV electron microscope
Authors: Yagi K. , Takayanagi K. , Kobayashi K. , Osakabe N. , Tanishiro Y. , Honjo G. 
Published: June 2020

Recent advances of UHV techniques, LEED, RHEED and AES, arose a surge of interest on the surface of solids. These techniques reveal structures and chemical compositions at the mono-atomic or mono-molecular level. All of them, however, are devoid of detailed topographic informations, although some efforts to introduce the scanning techniques have been done[l]. Transmission electron microscopy of high resolution should play a complementary role to these techniques. No attempt, however, has been done previously to use it to such a purpose. This was because it was difficult to get and keep clean surfaces in the poor vacuum at 1x10-5Torr level of the conventional electron microscope.The present paper reports observations of surface phenomena of one or two atomic layer level using a UHV JEM 100B electron microscope (10-8-10-10Torr), recently developed for insitu thin film growth studies[2]. Atomically flat (111) surfaces of Ag, Pd, Au and Cu were prepared by in- situ deposition at 150-350°C on M0S2, graphite and MgO. Air Cleaved thin films of MoS2 and graphite were preheated to 800°C to get clean surfaces[3].
Elucidation of block boundaries as the dissolution channels in hydrated cement
Authors: Belov N.V. , Papiashwili U.I. , Yudovich B.E. 
Published: June 2020

It has been almost universally adopted that dissolution of solids proceeds with development of uniform, continuous frontiers of reaction.However this point of view is doubtful / 1 /. E.g. we have proved the active role of the block (grain) boundaries in the main phases of cement, these boundaries being the areas of hydrate phases' nucleation / 2 /. It has brought to the supposition that the dissolution frontier of cement particles in water is discrete. It seems also probable that the dissolution proceeds through the channels, which serve both for the liquid phase movement and for the drainage of the incongruant solution products. These channels can be appeared along the block boundaries.In order to demonsrate it, we have offered the method of phase-contrast impregnation of the hardened cement paste with the solution of methyl metacrylahe and benzoyl peroxide. The viscosity of this solution is equal to that of water.
Localization of micropores in polymer films
Authors: Geymayer W.F. , Grasenick F. 
Published: June 2020

For studying corrosion problems, for the understanding of osmotic processes or generally for the investigation of reactions inside porous polymer films the knowledge of the frequency and the size of the pores as well as the registration of the course of penetrating pores is of high importance for the determination of the active pore-volume.In most of these processes at least one of the reactants is a fluid being in contact with the diaphragm through which it reacts with the medium on the other side. The fluid often begins to swell the polymer layer, a process that may even be necessary to develop the osmotic properties of the membrane.Thus it was an interesting problem, to find a way of detecting the pores in a possibly swollen organic diaphragm without altering it. Drying the specimens completely disturbs the original conditions, chemical dehydration with subsequent soaking the pores with a suitable monomer-mixture causes strong changes of the sensitive material by uncontrolled shrinkag.
Degradation of cellulose with high voltage electrons
Authors: Tucker P. A. , Hersh S. P. , Berry G. M. , Kerr N. , Mcelwain D. M. 
Published: June 2020

As part of a larger study of the degradation of polymers, cotton cellulose is being intentionally degraded with high voltage electrons. The initial results were reported earlier (1). Because of the implications of this study to the electron microscopy of beam sensitive materials, special attention is being given to relating these studies to electron microscopy.Generally, the microscopist's main, and perhaps only, information on specimen degradation is that provided by diminution of the electron diffraction pattern. It will be shown in this paper that even though specimen diffraction patterns are only slightly altered, the mechanical and chemical properties are vastly changed.To produce degraded fabrics having strength losses of 75% or more, cotton fabrics were exposed to radiation doses of 50 and 100 Mrad at 550 kV in an electron accelerator manufactured by High Voltage Engineering Corporation. Properties of such cotton fabrics before (i.e., control) and after exposure to 50 and 100 Mrad dosages are presented in Table I.
Applications of scanning transmissionelectron microscopy in materials science
Authors: Bovey P.E. , Wardell I.R.M. , Williams P.M. 
Published: June 2020

Following the work of Crew and colleagues, considerable interest has been generated during recent years in the technique of scanning transmission electron microscopy (STEM). Employing a tungsten field emission source, a simple two lens electron optical column is capable of producing a beam of electrons incident on a thin sample with a gaussian FWHM of 5Å or less, which may be scanned to produce an image modulated in brightness by the transmitted electron intensity. It is then generally accepted that for a suitable detector geometry, such an image is formally equivalent on reciprocity grounds to that produced in a conventional TEM. Such equivalence is an essential prerequisite for the materials scientist who wishes to exploit the high brightness probe in STEM for analytical applications, but not at the expense of image clarity and ease of interpretation.Thus, figure 1, shows conventional dark field (la) and weak beam dark field (lb) images recorded for dislocations in a thin foil of an Al/ Zn/Mg alloy, following orientation of the foil using rocking beam selected area diffraction and direct viewing of the non-scanned diffraction pattern on a fluorescent screen introduced into the column of the HB5 dedicated STEM.
Cathodoluminescence studies of CaF2 crystals in the SEM
Authors: Sluev V.I. , Saparin G.V. , spivak G.V. , Orlov J.N. , Bogevolnov V.E. , Ivanov L.N. , Karelin V.V. 
Published: June 2020

Calcium fluoride is a base of single crystals with and without impurities and dust-shaped substances which are widely used in optical industry,laser technique,dosimetry,analitical chemistry etc.Central points of the study of processes which take place into the excited CaF2 crystals are the problem concerning to the nature and structure of irradiation centers.We studied the transfer of energy by ions of impurity in the CaF2 crystals,the problem of minimum concentration detected by the SEM ana also the dependence of spatial CL resolution upon dimensions of substance particles.Single crystals of CaF2 activated by europium and manganese and grown by the Bridgman method in an HF atmosphere in graphite crucibles have been investigated in the paper.Some consentration series of single crystals were synthetized: CaF2:Eu(0 to 5%):Mn(0 to 6%).We observed the CL topography of crystal surface and also measured the CL intensity vs. activator concentration at room temperature.These experiments were realized with help of cutoff optical filters placed before input window of the photomultiplier in the SEM.
Effects of backscattering on the resolution of scanning Auger Microscopy
Authors: Janssen A.P. , Venables J.A. 
Published: June 2020

We have previously shown that the combination of a UHV SEM with a field emmission gun and a CMA for Auger detection is a valuable tool for surface microanalysis /1,2 3/, and we have demonstrated 30nm resolution using conventional N'(E) detection /4/. Although Auger images can be produced in some circumstances with the resolution of the beam diameter, the size of the analysis volume is influenced by backscattered electrons, and this resolution limit has not previously been experimentally determined. In the present preliminary experiments we have observed Auger line scans across abrupt chemical boundaries as a function of incidence angle, ø, and beam energy, Ep. These intensity profiles show reasonable agreement with Monte Carlo calculations /5, 6, 7, 8/ of the spatial distribution of backscattered electrons. For near-normal incidence, most of the Auger current will be emitted from within the primary beam area.A polycrystalline tungsten surface was flashed clean by electron bombardment heating and 2-5pm diam
Prediction of X-ray spatial resolution for SEM and STEM specimens using Monte Carlo methods
Authors: Faulkner R.G. 
Published: June 2020

Determinations of spatial X-ray resolution in conventional microanalysis in electron probe microanalysers where the beam is perpendicular to a smooth surface are now quite straightforward. However, SEM's and STEM'S are becoming increasingly used methods for performing microanalysis. The specimen arrangement for this sort of work often involves both inclined beam and detector geometries. Under these conditions X-ray correction constants have to be altered due to the changed average path length for the emerging X-rays. The spatial resolution and correction constants peculiar to the new geometry can be physically studied using a Monte Carlo computer method which simulates the trajectories of many electrons as they interact with the specimen.Another attempt to predict resolution and effective take-off angle using single electron scattering theory has been made for thin films. This over estimates the X-ray source size at large foil thicknesses and under estimates at small foil thicknesses. Experimental methods have been devised utilising edges and small, spherical particles.
Interaction between small particles of cobalt, iron and nickel
Authors: Hansson I. , Tholen A. 
Published: June 2020

A growing interest has recently been shown in small (< 100 nm) metal particles. Such particles are conveniently made by evaporation in an inert gas atmosphere (see eg. 1,2) and the average particle size is empirically found to increase both with pressure and evaporation temperature.A detailed study was presented earlier on the interaction between single particles of gold (3). The surface energy was found to be the driving force for the whole series of possible adhesion events which include elastic deformation with strain fields visible in the electron microscope (4), plastic deformation with twinning, relative particle rotation and sliding. Nobody has, however, convincingly reported at which position relative to the evaporation source and at what temperature the particle formation and interaction occur. It is the aim with this investigation to start elucidating these processes by using various ferromagnetic materials with different Curie temperatures. These particles have then, in a way, a memory of the actual processes.
Development of substructure in 1100 aluminum during cold rolling
Authors: Rohr D.L. , Hecker S.S. 
Published: June 2020

The plastic response of metals at very large plastic strains is of considerable interest for practical and academic reasons. The question of the existence of a saturation stress remains largely unanswered because most experiments are not carried out to sufficiently large strains. In this paper we report our preliminary findings on the development of substructure in 1100 aluminum during rolling to reductions of 99.8%. This is part of a comprehensive study of microstructure and mechanical response of metals to large uniaxial and biaxial deformations.Commercially pure (1100) aluminum plates, annealed at 500°C, were rolled at room temperature from various starting thicknesses to a final thickness of 0.127 mm in a 2-high laboratory rolling mill. Sheets with final reductions ranging from 9.1 to 99.8% were examined by transmission electron microscopy. Thin foils were prepared directly from the 0.127-mm thick sheets by electropolishing with a 50cc-50cc-2cc HNO3-CH3OH-HCl solution in a jet polisher.
Combined TEM, FIM, atom probe analysis of a nickel based superalloy
Authors: Beaven P.A. , Delargy K.M. , Miller M.K. , Smith G.D.W. 
Published: June 2020

We have recently reported the first combined use of electron microscopy (TEM), field ion microscopy (FIM) and Atom Probe microanalysis for the study of alloy element partitioning between the γ and γ' phases in a nickel-based superalloy, IN939 (l). The distribution of the major alloying elements Co, Cr, Al, and Ti was determined, and the ordered structure of the γ' phase was investigated directly by monitoring the nature of the ions field evaporated from successive atom layers of a superlattice plane. In the present paper, we report several extensions to this work, including investigation of the ultra-fine secondary precipitates formed during the final low temperature stage of heat treatment of the alloy, and a study of the detailed composition of the primary carbide phase.The alloy studied was a cast, high-chromium superalloy, supplied by Inco (Europe) Ltd. Research Laboratories. The composition of the alloy (in atomic %) is as follows.
Investigation of biogenic magnetite particles by high-resolution electron microscope
Authors: Matsuda T. , Endo J. , Osakabe N. , Tonomura A. , Arii T. 
Published: June 2020

In 1975, Blakemore found aquatic bacteria that swim along earth's magnetic lines of force [1]. They have permanent magnets of iron-rich fine particles within them. Such particles were found by Mössbauer analysis to consist of magnetite in the case of magnetospirilla [2]. In addition, Towe et al confirmed by electron diffraction that the particles were crystalline [3]. The purpose of the present investigation is to determine the crystal and magnetic structure of these particles by both high-resolution lattice imaging and electron holography; however only the former is reported here.Magnetotactic bacteria were gathered in a fresh-water pond. The specimens were peanut-shaped, and approximately 3um in length. Transmission electron micrographs, such as that shown in Fig. 1, reveal that approximately 30 fine particles are aligned within each bacterium.
Identification of calcium oxalate crystals in dried or fixed tobacco leaf
Authors: Baliga Vicki L. , Counts Mary Ellen 
Published: June 2020

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.