bluuebunny/crossref_metadata_2025_split huggingface dataset:
The voids formation of Cu-1.5%Fe alloy during irradiation in HVEM
Authors: Ohnuki S. , Takahashi H. , Takeyama T. 
Published: June 2020

IntroductionThe high voltage electron microscope (HVEM) is a method useful for simulating the effects of fusion and fission reactor and has the advantage that direct observation can be made of the void and other defects of the specimen during irradiation. Also, the determination of the conditions under which voids can be nucleated and grown by electron irradiation ought to be helpful in separating the effects of the various parameters involved. This paper presents the effects of aging on void formation in Cu-Fe alloy during irradiation in the HVEM.Experimental ProcedureAlloy was quenched into water from 1263 K and aged at 973 K for 1 hr, 4hrs and 4 days. Electron irradiation was performed at 523 K by using a 650 kV HVEM in a flux of 3xl023e/m2 (9xl0-4 displacement/atom/s). The foil plane was a (110). For comparison with the alloy, pure Cu also irradiated under the same dcondition.
Defect clusters of molybdenum alloys bombarded by HVEM
Authors: Igata N. , Kohyama A. , Murakami H. , Itadani K. , Tsunakawa H. 
Published: June 2020

As a simulation study of heavy radiation damage by neutrons, in-situ observation of damage process in molybdenum alloys was performed by a high voltage electron microscope. The objectives of this study are to clarify the processes of defect cluster nucleation and growth, and the role of alloying elements on these in the temperature range from 300K to 1300K.The used molybdenum alloys were Mo-(150-1000)at.ppm.C, Mo-(0.06-0.6)at.%Nb, MO-0.29at.%Hf, MO-(0.026-26)at.%Re and Mo-0.56at.%Ni. The used materials were electron-beam melted and hot rolled at 200-400°C and annealing was performed in the vacuum of l×l0-7torr. at 1800°C for 1.0 hr. The standard irradiation conditions were as follows,Accelerating voltage: 1250KV, Beam intensity: l-6×l019e/cm2sec, Incident beam direction: <100>, g-vector: {110},The density of defect clusters was determined by the thickness gradient method.The logarithmic density of interstitial dislocation loops, logNi, increased with the reciprocal irradiation temperature, 1/T. The relation between logNiand 1/T was divided into two Arrhenius type relations above and below 500K.
Limits of AES microanalysis in SEM
Authors: Delong A. , KolaŘÍk V. 
Published: June 2020

Auger electron spectroscopy Is a well known method of chemical analysis of solid surfaces. For its application the following features are important:i) highest sensitivity when measuring small concetrationsii) smallest diameter of the analyzed areaIt is clear that these two requirements are contradictory. For many applications the second condition is predominant in spite of the fact that it is necessary to take into account the concentration of the element analyzed as high as nearly 100%. As the Auger electrons posses energies in the range of some tens to a few hundred eV, it can be supposed that the smallest surface area from which they can be generated due to scattering will not differ from the area involved in the emission of secondary electrons, i.e. it will not be larger than 100 Å.There are two other important conditions :i) the use of a very small electron probe (100 Å)ii) the attainment of very high current density in the probe
Microanalysis of amorphous semiconductor films
Authors: Schröder B. , Geiger J. , Müller H.W. 
Published: June 2020

In a previous paper /l/ it has been pointed out that electron energy loss spectroscopy in the infrared spectral region is a very sensitive tool for the study of structure and composition of thin films. Here as a further example the energy loss study of amorphous silicon films is presented. In the case of amorphous semiconductors where most of the optical and electrical properties are still strongly influenced by impurities an analytical test is substantial.Silicon films have been investigated which have been prepared by different methods and under different conditions: by evaporation, by decomposition of silane (SiH4) in a rf glow discharge and by sputtering. The influence of the substrate temperature has been studied for films produced by silane decomposition.Fig. 1 shows a typical spectrum of amorphous silicon prepared by the glow discharge method obtained by 30 keV electrons with a resolution of 3 to 4 meV.
On the problem of filtered images in chemical analysis
Authors: Zanchi G. , Sevely J. , Jouffrey B. 
Published: June 2020

As was proposed in several recent review papers (for instance 1-3) it is interesting to use electron energy losses corresponding to inner shell excitations by incident electrons to perform chemical analysis. One of the main advantages of the inner shell excitation spectroscopy (ISES) is that it is essentially available for light elements, contrary to characteristic X ray emission spectroscopy.Two methods can be used :- energy analysis : energy loss spectra are obtained from selected projected area of the sample and elemental characteristic energy losses are detected;- image energy filtering : images are formed by selecting electrons in an energy loss range which contains a characteristic energy loss. They show a map of the distribution of a given element in the object with a high spatial resolution.Combining these two methods is quite essential to perform chemical analysis. Such studies can be achieved in CTEM by means of an energy filtering system preserving the imaging properties of the microscope.
Spatial resolution of X-ray microanalysis in thin foils
Authors: Hutchings R. , Jones I.P. , Loretto M.H. , Smallman R.E. 
Published: June 2020

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.
Large-angle-electron-channeling-pattern: generation and applications
Authors: Brunner M. , Erlenwein P. 
Published: June 2020

A tilting stage /1/ was used for obtaining large angle electron channeling patterns (ECP) /2/ (fig. 1). The stage is driven by two step motors and tilted in synchronism with the movement of an electron beam of a Vistascan storage device or of a light emitting diode, writing the pattern on a photographic film in an xy-recorder. An electron beam with a divergence of 0.03° is produced by a thermal cathode and two diaphragms. The backscattered electrons are registrated by two scintillation detectors which are mounted on opposite sides to reduce shadowing effects. After amplification and regulation the produced electronic signal controls the writing or storage device. This method allows to record ECPs from areas of 200 μm in diameter at a tilting range of ±75° in both directions with a resolution of 0.05°.This rocking crystal method has been applied already to investigations of the temperature dependence of the ECP-contrast /3/.
Heavy ion irradiation damages in crystals
Authors: Yoshida H. , Sakuramoto N. , Kawai K. 
Published: June 2020

Accelerator irradiations are recently of interest in the field of radiation damages, because of the simulation studies for high dose neutron irradiations as well as the fundamental studies for atomic collision processes. The characteristic phenomena associated with ion irradiation such as sputtering,blistering and flaking are considered to be very important for plasma walls of fusion reactors. Since the penetration depth of ions in materials is very small, highly dense lattice defects are produced by ion irradiation in the shallow regions from the surface, and also the projected ions may accumlate within the projected ranges except channelled ions. Such the phenomena can be detected by means of the pulse-thining technique for SEM and TEM observations. Electron channelling pattern (ECP) is also useful for studying about the phenomena, because of its sensitiveness to lattice distortion of the surface layer.The accelerator irradiations with inert gas and metal ions were performed for bcc, fcc and diamond crystals.
In situ study of collective dislocation movements in a Ni-Cr alloy
Authors: Clement N. , Caillard D. , Martin J.L. 
Published: June 2020

Properties of groups of moving dislocations have to be considered in various deformation processes especially those of concentrated alloys (1). Indeed, the strain rate dependence on stress and temperature of such materials cannot be interpreted in terms of simple models postulating homogeneous deformation. Nevertheless experimental studies of these dynamic properties are rare and consist mostly of etch pit studies of the sequences of dislocation pile ups at various stages of the stress strain curve (2) or the dynamic recording of macroscopic slip trace development by high speed cinematography (3).We report here some microscopic properties of moving groups of dislocations in a FCC Ni-30 wt%Cr alloy observed directly during deformation tests in the high voltage electron microscope. This alloy has a rather low stacking fault energy (γ/Gb≃3.5xlO-3) and exhibits short range order after 100 hours of annealing treatment at 600°C. Between 77 K and 400 K, conventional deformation tests lead to rather small activation volumes indepedent of strain and a high athermal stress, incompatible with the intersection mechanism (4).
Shock deformation twinning in molybdenum and a comparison of deformation twinning in shock-loaded BCC and FCC metals
Authors: Murr L.E. , Wongwiwat K. 
Published: June 2020

Verbraak reported deformation twins to have been formed in shock-loaded molybdenum from observations by optical metallography. Attempts to verify the existence of deformation twins in shock-loaded molybdenum by Murr, et al. were unsuccessful at pressures ranging up to 21 GPa (210 kbars) at a constant pulse duration of 2 μs. Since the conditions under which Verbraak originally observed deformation twins were not well documented, a study was undertaken to reinvestigate the shock deformation of molybdenum in a range of pressures and pulse durations.Molybdenum sheets (0.0025 cm thick and 0.025 cm thick) were annealed to produce several grain sizes and shock loaded in molybdenum sandwiches and assemblies (spall plates and momentum traps) by impacting them with stainless steel flyer plates as outlined previously. Pressure experiments were performed at 140, 260, and 350 kbars (corrected pressure values using impedance matching techniques) at a constant pulse duration of 2 μs while two additional experiments were conducted at 260 kbars by shock loading test assemblies at pulse durations of 0.5 μs and 8 μs.
Aspects of intergranular fracture of CuBi studied in the scanning electron microscope
Authors: Biggin S. 
Published: June 2020

IntroductionKossel X-ray diffraction within the SEM can be used to obtain orientation relationships (to 0.2° routinely) and crystal perfection information from microvolumes (5μm)3, this being the principal feature of the technique1. A study of the cracking behaviour of CuBi alloys has been made in an attempt to understand the mechanism by which intergranular fracture occurs due to the addition of down to 0.001at.% Bi2. Orientation relationships (angle/axis pairs) were needed for cracked boundaries but can only be found from Kossel patterns from annealed materials. Thus orientation work was done on annealed material, which was then deformed in a 4-point bending machine. Observations of changes in crystal perfection were made at various strains, as cracks appeared, at positions within grains and at boundaries. Finally, optical study of slip lines at boundaries and fracture surfaces was made.A Cu0.02 wt.% Bi sample was given a maximum embrittlement heat treatment (1073K,10min,air-cooled; 773K, 4h, furnace-cooled) which caused a large percentage of the Bi to segregate to the boundaries.
Dislocations in alumina deformed by prismatic slip
Authors: Cadoz J. , Castaing J. , Philibert J. 
Published: June 2020

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).
In situ investigation of the primary recrystallization of alpha titanium in HVEM
Authors: Naka S. , Penelle R. , Valle R. 
Published: June 2020

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.
The “rediscovery” of polyethylene glycol, and its use as an embedding matrix
Authors: Wolosewick J. J. 
Published: June 2020

Polyethylene glycols are liquid or solid polymers of the general formula H(OCH2CH2)nOH, where n is greater than or equal to 4. They are readily miscible in water and in a variety of solvents and are nontoxic. The higher molecular weight polymers (e.g., PEG 4000, 6000) are brittle and melt at 55°-65°C, while the lower molecular weight polymers are soft gummy solids or liquids. These polymers have been used as embedding matrices for light and electron microscopy since the 1940's, although their use has been overshadowed by the now standard embedments (e.g., paraffin and epoxy resins).The procedures for embedding in PEG have been described in detail. Briefly, specimens are fixed according to standard procedures, washed in an appropriate buffer, dehydrated either in PEG-H2O solutions, or in ethyl alcohol. For embedding, the specimens are transferred to capsules filled with the pure polymer and solidified at room temperature, or by rapid cooling in liquid nitrogen. The blocks are mounted onto suitable stubs (e.g., Epon blanks), trimmed and sectioned “dry” on glass or diamond knives. The sections are mounted onto polylysine-coated slides or Forrmvar-coated grids in the same manner as are frozen sections.
Ultrastructural immunocytochemistry in diagnostic pathology
Authors: Huang Shao-nan 
Published: June 2020

The objectives of this communication include the following: (1) to illustrate some aspects of practical ultrastructural immunocytochemistry, thus examplifying its value in diagnostic pathology, and (2) to compare the sensitivity, specificity and technical complexity of the three methods, i.e., protein Agold (PAG), immunoferritin (IFe) and peroxidase-antiperoxidase (PAP).For the immunogold method, monodispersed gold particles were obtained with the use of sodium citrate as the reducing agent on chloroauric acid solution. The PAG complex was then prepared according to the method described by Horisberger. The efficacy of PAG is assessed by its ability to bind the preformed immune complexes, such as shown in FIG.1, a smear preparation of hepatitis B core antigen (HBcAg) immune complex. A high degree of specific labelling with PAG would ascertain its high efficacy in immunocytochemical staining. Prior treatment of the immune complexes with protein A blocks the subsequent labelling with PAG, thus indicating specificity.
Imaging of platinum-shadowed macromolecular complexes in dark field
Authors: Andrews D.W. , Ottensmeyer F.P. 
Published: June 2020

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.
Localization of bombesin at the electron microscope level employing the modified ABC method in the rat neostriatum
Authors: Bradley Ronald H. 
Published: June 2020

Bombesin was originally isolated from frog skin (1) and it has been recently localized with the CNS (2). Bombesin has been shown to bind certain pharmacological drugs such as diazepams within the CNS (3). Recent investigations by our lab have been successful in localizing other putative neurotransmitter candidates such as methionine enkephalin, leucine enkephalin, substance P and GAD with the modified avidin-biotin complex technique within rat neostriatum (4). The present study was designed to localize bombesin in somata of neostriatal neurons in rats that were treated with colchicine to increase somatal neurotransmitter concentrations.The increase of somatal bombesin, a putative neurotransmitter, was accomplished by bilateral stereotaxic intraventricular injections of 15 µ1 (10 µ1/µg) colchicine per ventricle. Following a 48 hr survival time, the rats were intracardially perfused with our modified immunocytochemical buffer (3) which contains 1% glutaraldehyde, 1% paraformaldehyde in a microtubule stabilizing buffer (MSB) at pH 7.1 (37°C).
SEM evaluation of the TEM cold-stage double-film specimen
Authors: Bellare Jayesh 
Published: June 2020

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.
Ultrastructural study of tobacco mosaic virus-infected chloroplasts
Authors: Henry Egbert W. 
Published: June 2020

There have been several reports on the effects of tobacco mosaic virus (TMV) infection in Nicotiana tabacum leaf tissue. TMV infection does not appear to have an exact or precise infective selectivity, with respect to particular tissues. The tissue abnormalities such as lignification, suberization, vein banding, and vein clearing, may not be direct tissue responses to TMV infection. However, it has been suggested that plasmodesmata and possibly ectodesmata, may represent the actual sites of TMV infection, especially the plasmodesmata of the basal septum.TMV infection has also been implicated in host resistance vs. the levels of phenolic-type enzymes. A rise in oxidative metabolism has been associated with TMV infection, thus causing an increase in the, activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase. In addition, TMV infection may cause a lowering of o-dihydric phenols such as chlorogenic acid in some tissues.
Electron microscopy of high performance PBO and ABPBO polymers
Authors: Krause S. J. , Haddock T. , Adams W. W. 
Published: June 2020

Recent developments in the synthesis and preparation of high molecular weight polymers have resulted in the generation of two new aromatic heterocyclic polymers with excellent mechanical properties. The polymers are the rigid rod poly-p-phenylene benzobisoxazole (PBO) and the flexible coil poly 2,5(6) benzoxazole (ABPBO). The purpose of this study was to characterize the morphology of PBO and ABPBO in as-spun (AS) and annealed (AN) conditions by the use of transmission electron microscopy (TEM) imaging and diffraction techniques, and to compare the results with other high performance polymers.Samples were prepared for TEM by detachment replication. A JEOL 100CX was operated at 120 kV. Dark field images were formed from the first, second, and third equatorial reflections in the case of PBO, and from the first and second equatorial reflections for ABPBO. In order to minimize beam damage artifacts, the areas of the sample used for dark field imaging were adjacent to those used for locating and focusing.
The void lattice in α-Al2O3
Authors: Lee W.E. , Jenkins M.L. , Pells G.P. 
Published: June 2020

Alignment of irradiation-induced voids along specific crystallographic directions has been observed in many monatomic bcc, fee and cph metals. Observations of void alignment in diatomic materials, however, have been limited to just three cases: electron-irradiated CaF2 and SrF2 and neutron or heavy-ion irradiated α-Al2O3. We describe here a study of the evolution of the void lattice with increasing dose in heavy-ion irradiated α-Al2O3.Thin (∽50μm) polished, single crystals of α-Al2O3 were irradiated with 4MeV Ne+ and Ar+ ions to doses up to 30dpa over a range of temperatures from 500-900°C. Specimens were progressively backthinned through the damage profile by ion-beam milling and were examined at various stages in a Philips EM400 STEM. Voids were imaged using phase (defocused) contrast techniques.