bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of the microstructure of 600 Mev proton irradiated materials
Authors: Gotthardt R. , Horsewell A. , Paschoud F. , Proennecke S. , Victoria M. 
Published: June 2020

Fusion reactor materials will be damaged by an intense field of energetic neutrons. There is no neutron source of sufficient intensity at these energies available at present, so the material properties are being correlated with those obtained in irradiation with other irradiation sorces. Irradiation with 600 MeV protons produces both displacement damage and impurities due to nuclear reactions. Helium and hydrogen are produced as gaseous impurities. Other metallic impurities are also created . The main elements of the microstructure observed after irradiation in the PIREX facility, are described in the following paragraphs.A. Defect clusters at low irradiation doses: In specimens irradiated to very low doses (1021-1024 protons.m-2), so that there is no superimposition of contrast, small defect clusters have been observed by the weak beam technique. Detailed analysis of the visible contrast (>0.5 nm diameter) revealed the presence of stacking fault tetrahedra, dislocation loops and a certain number of unidentified clusters . Typical results in Cu and Au are shown in Fig. 1.
SEM study of diffusion bonded interfaces in Cu-Al(11,46)-Mn(6,62) and Cu-Al(6,94)- Zn(18,86) copper-based shape memory alloys
Authors: Calvo F.A. , Gómez de Salazar J.M. , Ureña A. , Méndez F.J. , Guilemany J.M. 
Published: June 2020

The copper-based alloys studied belong to the group of those materials showing Shape Memory Effect (SME). Diffusion Bonding (DB) procedure is an alternative joining method of welding copper-based Shape Memory Alloys, traditionally welded by techniques like electron bean welding (EBW). However EBW provides embrittlement to the joint. This situation has been corrected by DB as confirm the SEM-EDS study presented here.A material shows SME when once has been thermomechanically deformed, it is able to recover its original (as fabricated) shape by means of a simple heat-up. This pheno menom is possible only for those materials which have β phase prone to undergo martensitic transformation. DB technique estimulates diffusion processes betwen materials by the combination of pressure, temperature, time, surface materials roughness and atmosphere condition in the experimental unit with the aid, sometimes, of a third material, in foil or plated form, which is known by the name of interlayer. The parameter set and details of attaing diffusion bonding joints procedure are under a patent developed recently by the authors .
Microstructural studies of matrix and interface in ceramic fibre-reinforced aluminium alloys
Authors: Yang Ming , Scott V.D. 
Published: June 2020

This study is a part of an ongoing research programme aimed at optimising the properties of ceramic fibre reinforced aluminium alloys. It involves a detailed study of matrix and interface and an understanding of the overall mechanical behaviour of the composite. Here, we report an investigation of an Al-7wt%Si alloy reinforced with alumina fibres. A range of techniques including analytical electron microscopy are used to characterise the structure of the fibre matrix interface, the crystallography and morphology of matrix precipitates, and dislocation substructures.It is shown that the eutectic structure of the Al-Si alloy is markedly changed in the presence of fibres, with silicon showing a tendency to segregate on the fibres. Coarse silicon particles are characterised by twins having the twin the {111} silicon habit plane and related by a rotation of 180° about the [110] direction.The particles have a lamellar morphology with the longitudinal axis lying in the {111} habit plane, but show no evidence of any epitaxial relationship with the aluminium lattice.
Nucleating transformation in ZrO2
Authors: Ma L.T. 
Published: June 2020

To understand the michanism of transformation in ZrO2, the Al2O3/ZrO2 composite and Y-TZP have been studied. For the Y-TZP the nucleating transformation has been confirmed.For the Al2O3/ZrO2 composite the intragranular ZrO2, which is in tetragonal phase , has been studied. Fig. 1-2 show the interface between Al2O3 and ZrO2 Fig. 3 shows the nucleating transformation in the t-ZrO2 grain. Before nucleation it appears the stressing stripes. When the nucleation occurs the stripes are reduced. Then the nucleating transformation is formed. It means that for nucleation some stress was absorbed. So, in the t-ZrO2 whether in Y-TZP or in composite the nucleating transformation generally exists.At the early time, the untransformed t-ZrO2 phase has been found. From the viewpoint of nucleation the untransformed t-ZrO2 grain unexists, if the nucleating condition is satisfied.We also examine the nucleating necessary in Y-TZP. Under restraint of the neighbour grains the t-ZrO2 phase can be maintained in Y-TZP. If the nucleating condition is not satisfied, the t-ZrO2 can not be transformed to monoclinic phase, even though the restraint of the t-ZrO2 grain is reduced and the grain has enough size.
Effect of furnace atmosphere and silica content on the consolidation behaviour of magnesia partially stabilised zirconia
Authors: Drennan J. , Hannink R.H.J. , Clarke D.R. , Shaw T.M. 
Published: June 2020

Magnesia partially stabilised zirconia (Mg-PSZ) ceramics are renowned for their excellent nechanical properties. These are effected by processing conditions and purity of starting materials. It has been previously shown that small additions of strontia (SrO) have the effect of removing the major contaminant, silica (SiO2).The mechanism by which this occurs is not fully understood but the strontia appears to form a very mobile liquid phase at the grain boundaries. As the sintering reaches the final stages the liquid phase is expelled to the surface of the ceramic. A series of experiments, to examine the behaviour of the liquid grain boundary phase, were designed to produce compositional gradients across the ceramic bodies. To achieve this, changes in both silica content and furnace atmosphere were implemented. Analytical electron microscope techniques were used to monitor the form and composition of the phases developed. This paper describes the results of our investigation and the presentation will discuss the work with reference to liquid phase sintering of ceramics in general.
Unusually large magnetite (Fe3O4) crystals inside a magnetotatic bacterium
Authors: Farina Marcos , Lins Henrique G.P. , Esquivel Darci M.S. 
Published: June 2020

Magnetite crystals inside magnetotactic microorganisms have been shown to cover a wide range of dimensions and shapes. However in almost all cases reported until now, crystals width and length remain under the magnetic monodomai dimensions when using Butler and Banerjee theoretical curves. We report here one type of magnetotactic bacterium which produces very large magnetite crystals as compared with those described in the literature. In previous communication we had notified this fact, but without detail. Samples were collected from brakish water from ITAIPU lagoon near Rio de Janeiro (24º Southern hemisphere). In the same sample it was possible to find different magnetotactic microorganisms.After standard isolation treatments we obtained different groups of crystals identifyed as magnetite (Fe3O4) by electron diffraction. It was observed that larger crystals(> 1000 Aº in length) stayed always closely attached in linear chains differently from smaller ones appearing as rolled chains under the electron microscope (Fig.l).
Electron microscopy of diamond films grown by bias-controlled chemical vapor deposition
Authors: Ma G.-H. M. , Lee Y. H. , Glass J. T. 
Published: June 2020

The synthesis of diamond films by various low pressure methods has attracted much attention recently. The primary reasons for the great interest are diamond’s substantial potential as a high temperature semiconductor, heat sink, wear resistant coating, etc. Most recently reported research has been directed towards achieving better films quality and higher growth rates. In the present study, a biased hot filament chemical vapor deposition system (or Bias Controlled CVD, BCCVD) has been utilized to examine the role of charged species in the deposition of diamond. Utilizing this system, high quality diamond films which have the characteristics similar to the natural diamond have been achieved.Transmission Electron Microscopy (TEM) is employed to study the microstructure- processing relationships of diamond films deposited by BCCVD under different biasing conditions.Diamond films were deposited on Si (001) substrates under forward bias (more positive substrate potential relative to filament), zero bias (no potential difference between substrate and filament), and reverse bias (more negative substrate potential) conditions.
Morphological identification of ethylene-propylene block copolymer and polypropylene/polyethylene blend
Authors: Shaokun Lin , Peng Xia 
Published: June 2020

Surface etching technique and scanning electron microscopy were used to identify the morphology of ethylene-propylene block copolymer (EPC, ethylene content 30%) and iso-polypropylene/low density polyethylene blend (iPP/LDPE, 70/30). Fractured surfaces of EPC and iPP/LDPE, obtained from notch wedge impact at room temperature were examined with SEM also. A Hitachi S-520 SEM was employed in these experiments.Samples of EPC and iPP/LDPE for surface etching were prepared by melt crystallization at 230°C for 15 minutes and then were kept at 180°C for 20 minutes in nitrogen atmosphere. The etching procedure was carried out by immersing the samples into an aqueous solution of H2SO4-CrO3 mixture (H2SO4: CrO3 : H2O = 22:30:48), with a little amount of emulsifying agent at 80°C for 10-12 minutes. Prior to this process, the samples were treated with a 10% emulsion of diamylene at 80°C for 3-5 minutes. All of the samples for SEM examination were coated with gold in an Eiko IB-3 ion coater.
A SEM study of the macro-crystalline structure of 2-(2 ,4-dinitrobenzyl) pyridine
Authors: Ware Jacqueline , Hammond Ernest C. 
Published: June 2020

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the Scanning Electron Microscope (SEM). The structure of these crystals was compared with the macro-structure of the crystals of 2-(2,4- dinitrobenzyl) pyridinium bromide, a salt of the compound which was also synthesized in the laboratory. A Scanning Electron Microscopy crystal study was combined with a study of the principle of the electron microscope.Sandy colored crystals of 2-(2,4-dinitrobenzyl) pyridine have the interesting property of turning a deep blue color in sunlight, which then, reverts again to the sandy color in the dark. The phenomenon is explained by the formation of a tautomeric form by the action of light. Study of the macro-structure of these unique and tiny crystals, as well as a comparison study of the macro-structure of a salt derivative is possible because of the excellent resolving power of the electron microscope, as opposed to the optical microscope.
Molecular images of crystal domain structure and new phase in [M(Pc)O]n polymer
Authors: Bensan Zou , Junhua Wu , Ziang Pan , Xiao Zhou , Xueli Du 
Published: June 2020

The samples, thin crystalline films of metallophthalocyanines polymer, have been prepared epetaxially by condensation polymerization of the monomer sublimed onto a newly-cleaved and degassed face of NaCl single crystal,at a constant temperature 440°C and in a dynamic vacuum about several Pa. The polymerization reaction equation is as follow;nM(Pc)(OH)2—[M(Pc)O]n+ nH2O where M=Si ,Ge.[M(Pc)O]n are a row-dimensional electronic conductive polymer. Its electrical conductivity can he as high as several (Ωcm)-1 after iodine-doping. This make it possibly become a hopeful functional polymer material which meet some special need. The crystal data were determined X-Ray diffraction; The investigation indicate that phthalocyanine rings tend to stack themselves up in the way in which they are parallel to each other and form molecular columns of rigid chains in [001] direction during the process of crystal growth.
Instrumentation and Computation
Authors: Hirsch P.B. 
Published: June 2020

The benefit to society arising from developments in instrumentation and computation can be judged primarily by the advances in knowledge and understanding generated by their application in different branches of science, covered in the other papers in this symposium. Without advances in instrumentation none of these advances is possible; developments in instrumentation and in image interpretation are therefore fundamental to and precede scientific advances in fields in which knowledge of structure is important. There is little doubt that the revolutionary first step was the development of the transmission electron microscope (TEM) in 1931 by Ernst Ruska; a second was the development of the scanning electron microscope (SEM); and the third the introduction of the scanning tunnelling microscope (STM) for high resolution surface imaging, by Binnig and Rohrer.The TEM and SEM have undergone continuous developments over the last 50 years or so, and have had a far-reaching impact in a wide range of disciplines; the STM is a relative newcomer but no doubt it too will have an increasing impact in furthering our understanding of solids and surfaces in particular. Once the basic instruments became available subsequent developments have been driven by the demands of the scientific disciplines in which these instruments have been applied. Many of the new developments in instrumentation and interpretation have been pioneered by the users themselves, and these in turn have led to modifications in commercial instruments to make such advances in technique available to the user community as a whole. Other developments have been initiated directly by the manufacturers as a result of a perceived need. There has been and continues to be a close interaction between the developers of hardware (not only of electron microscopes but also of ancillary equipment, e.g. microanalysis attachments, image processing equipment, specialist specimen stages, and specimen preparation facilities) and the users, leading to extensions in the range of applications and the types of information which can be obtained by electron microscopy. The following examples from the developments of electron microscopy in Materials Science illustrate these interactions and the particular advances arising from specific developments:
Contribution of Electron Microscopy to Structural Materials
Authors: Hornbogen Erhard 
Published: June 2020

Structural materials are expected to fulfil mechanical functions, for example in bridges, crank shafts, turbine blades, or medical implants. In use, high strength is aspired at low materials weight. The structure should be safe and the costs of the material, semi—finished products, or parts should be low. The term strength implies the resistance of a material against plastic deformation, as well as against propagation of cracks (i. e. toughness). Safety is connected with the control of various mechanisms of crack growth such as rupture, fatigue, and stress corrosion cracking. Finally, interaction of surfaces will induce a frictional shear stress, which may cause wear. The life of structures is usually limited by mechanical failure, which may become catastrophic, if it is unexpected due to lack of understanding of structural materials.The specific weight of materials predominantly stems from the kind of atoms from which the material is built. The properties implied in strength are mainly related to microstructure. There are only two types of phases of which materials are built: crystals and glasses (if the quasicrystals are neglected, for which applications have not yet been found). Metals are usually crystalline. Their strength is closely related to the properties of crystal dislocations. Transmission electron microscopy (TEM) is the major tool for their investigation. Resistance against plastic deformation (i. e. yield stress) is controlled by elements of the microstructure, which act as obstacles against their motion. These microstructural features and their interaction with dislocations can also be analysed by TEM. It is reasonable to classify microstructural objects according to their geometrical dimensions 0 ≤ d ≤ 3. They become hardening mechanisms which are the ways by which the yield strength (i. e. load carrying ability of a material canb be raised).
High-Resolution Bright-Field and Dark-Field Hollow Cone Illumination
Authors: Herring R.A. , Twigg M.E. 
Published: June 2020

Hollow cone illumination using a large C2 blocked-aperture (bl apt) in the conventional TEM (CTEM) can remove the beams within the zero-order Laue zone (ZOLZ) thereby making lattice images more simply interpretable. Dark-field (DF) hollow cone illumination has the added advantage of enhancing the Z-contrast within the lattice image, since the electrons contributing to the image must be scattered over a large angle (approximately 10 mrad). Both of these imaging methods have been explored, using a 600 um C2 bl apt and objective aperture sizes of 70, 20 and 10 um, and are reported in this paper.Much interest has been generated by the report of Pennycook [1] on STEM Z-contrast imaging using annular dark-field. In earlier work ,it was noted that CTEM hollow cone imaging and STEM annular dark-field imaging are related via reciprocity [2] (Fig. 1). In addition, Zernike has shown the advantages of hollow cone illumination in optical phase-contrast microscopy [3]. The electron-optical analogues to these optical techniques are now possible because of the low Cs values achieved in modern TEMs.
Structural Transformation of a Germanium Σ=13 (510) [001] Tilt Grain Boundary under the Electron Beam
Authors: Rouvière Jean-Luc , Bourret Alain 
Published: June 2020

The possible structural transformations during the sample preparations and the sample observations are important issues in electron microscopy. Several publications of High Resolution Electron Microscopy (HREM) have reported that structural transformations and evaporation of the thin parts of a specimen could happen in the microscope. Diffusion and preferential etchings could also occur during the sample preparation.Here we report a structural transformation of a germanium Σ=13 (510) [001] tilt grain boundary that occurred in a medium-voltage electron microscopy (JEOL 400KV).Among the different (001) tilt grain boundaries whose atomic structures were entirely determined by High Resolution Electron Microscopy (Σ = 5(310), Σ = 13 (320), Σ = 13 (510), Σ = 65 (1130), Σ = 25 (710) and Σ = 41 (910), the Σ = 13 (510) interface is the most interesting. It exhibits two kinds of structures. One of them, the M-structure, has tetracoordinated covalent bonds and is periodic (fig. 1). The other, the U-structure, is also tetracoordinated but is not strictly periodic (fig. 2). It is composed of a periodically repeated constant part that separates variable cores where some atoms can have several stable positions. The M-structure has a mirror glide symmetry. At Scherzer defocus, its HREM images have characteristic groups of three big white dots that are distributed on alternatively facing right and left arcs (fig. 1). The (001) projection of the U-structure has an apparent mirror symmetry, the portions of good coincidence zones (“perfect crystal structure”) regularly separate the variable cores regions (fig. 2).
The Contribution of Phonon-Scattered Electrons to High-Resolution Electron Micrographs of Crystals
Authors: Kohl H. 
Published: June 2020

High-Resolution Electron Microscopy is able to determine structures of crystals and interfaces with a spatial resolution of somewhat less than 2 Å. As the image is strongly dependent on instrumental parameters, notably the defocus and the spherical aberration, the interpretation of micrographs necessitates a comparison with calculated images. Whereas one has often been content with a qualitative comparison of theory with experiment in the past, one is currently striving for quantitative procedures to extract information from the images [1,2]. For the calculations one starts by assuming a static potential, thus neglecting inelastic scattering processes.We shall confine the discussion to periodic specimens. All electrons, which have only been elastically scattered, are confined to very few directions, the Bragg spots. In-elastically scattered electrons, however, can be found in any direction. Therefore the influence of inelastic processes on the elastically (= Bragg) scattered electrons can be described as an attenuation [3]. For the calculation of high-resolution images this procedure would be correct only if we had an imaging energy filter capable of removing all phonon-scattered electrons. This is not realizable in practice. We are therefore forced to include the contribution of the phonon-scattered electrons.
High-Resolution Image Simulation of a Tilted Crystal
Authors: Hetherington C. J. D. 
Published: June 2020

Most high resolution images are not directly interpretable but must be compared with simulations based on model atomic structures and appropriate imaging conditions. Typically, the only parameters that are adjusted, in addition to the structure models, are crystal thickness and microscope defocus. Small tilts of the crystal away from the exact zone axis have only rarely been considered. It is shown here that, in the analysis of an image of a silicon twin intersection, the crystal tilt could be accurately estimated and satisfactorily included in the simulations.The micrograph shown in figure 1 was taken as part of an HREM study of indentation-induced hexagonal silicon. In this instance, the intersection of two twins on different habit planes has driven the silicon into hexagonal stacking. However, in order to confirm this observation, and in order to investigate other defects in the region, it has been necessary to simulate the image taking into account the very apparent crystal tilt. The inability to orientate the specimen at the exact [110] zone was influenced by i) the buckling of the specimen caused by strains at twin intersections, ii) the absence of Kikuchi lines or a clearly visible Laue circle in the diffraction pattern of the thin specimen and iii) the avoidance of radiation damage (which had marked effects on images taken a few minutes later following attempts to realign the crystal.) The direction of the crystal tilt was estimated by observing which of the {111} planes remained close to edge-on to the beam and hence strongly imaged. Further refinement of the direction and magnitude of the tilt was done by comparing simulated images to experimental images in a through-focal series. The presence of three different orientations of the silicon lattice aided the unambiguous determination of the tilt. The final estimate of a 0.8° tilt in the 200Å thick specimen gives atomic columns a projected width of about 3Å.
Application of a Superconducting Cryo-Electron Microscope to the Physics and Material Science of Ceramics
Authors: Sugiyama Masaaki , Kubo Hiroshi , Fukushima Kurio 
Published: June 2020

Superconducting cryo-electron microscope (SCM) has been mainly applied to the biological field, due to the advantages such as reduction of radiation damage and the possibility of a perfectly contamination-free environment. From the material science view point, microstructural characterization at liquid helium temperature is an attractive technique. In this presentation, some topics concerning the low temperature physics of ceramics will be discussed on the basis of the data obtained using high resolution SCM.The principle of the superconducting lens (SCL) was first described by the Dietrich Group of Siemens AG, West Germany in 1966, following this by fitting a SCL as the objective lens of a 200kV electron microscope, a new type of electron microscope, the JEM-2000SCM, was developed by JEOL LTD, Japan. A detailed cross-sectional diagram of the SCL is shown in Fig.1. A spherical aberration coefficient of 1.2mm was obtained.