bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and Energy of Grain Boundaries in Metals
Authors: Merkle K.L. , Wolf D. 
Published: August 2016

The investigation of structure-property correlations is a rather complex endeavor not only because interfacial Systems are intrinsically inhomogeneous, with chemical composition and physical properties differing from the surrounding bulk material, but also since three different aspects of the geometrical structure are involved — namely the macroscopic, microscopic, and atomic structures. As outlined in the Guest Editors' introduction, in addition to the choice of the materials which form the interface, five macroscopic and three microscopic degrees of freedom (DOFs) are needed to characterize a single bicrystalline interface. The importance of the atomic structure at the interface as well as the local interfacial chemistry, extrinsic (i.e., impurity segregation) or intrinsic (for example, via interfacial reactions or space-charge phenomena), greatly add to the task's complexity.Grain boundaries (GBs) in pure metals represent ideal model Systems for investigating the strictly geometrical aspects of structure-property correlations for the following three reasons. First, the complexity due to the myriad of possible choices of materials combinations forming the interface is avoided, enabling a focus on the different roles of the three distinct geometrical aspects of the structure. Second, because GBs are bulk interfaces, dimensional interface parameters (such as the modulation wavelength in strained-layer superlattices, or the thickness of epitaxial layers) do not enter into the problem. Finally, the GB energy is thought to play a central role in various GB properties, such as impurity segregation, GB mobility and fracture, GB diffusion and cavitation, to name a few. A better understanding of the correlation between the structure and energy of GBs, therefore, promises to offer insights into more complex structure-property correlations, as well.
Up Close: The Department of Materials, University of Mons, Belgium
Authors: Wautelet M. 
Published: August 2016

The State University of Mons was established in 1965, at the heart of an old industrial region of South Belgium. Since that time, the role of the University emerged as a source of new ideas for the region. The Department of Materials was founded in 1988, developing from the identification of various groups and their expertise in the materials science field. The goal of the Department of Materials is “to arrange and promote researches in this field. The Department will also work at improving education in Materials Science.” The Department will continue existing contacts and promote new contacts with regional, national, and international industries, and its experimental facilities are accessible to all interested researchers.The members of the Department of Materials belong to the Faculties of Science and Medicine of the State University of Mons. They form an interdisciplinary group, including physicists, chemists and biologists—experimentalists and theoreticians.Although some research activities involve more than one group, they can be arranged according to either the nature of materials (thin films, polymers, surfaces, quasi-one-dimensional conductors, bio-materials) or methods of preparation (laser irradiation, chemical vapor deposition, electron evaporation) and characterization (electron and x-ray diffraction, spectrophotometry, FTIR, micro-Raman, electrical conductivity, surface analytical techniques).
The Unique Electronic Properties of the Silver Halides
Authors: Brown Frederick C. 
Published: August 2016

The modern photographic emulsion is an extremely sensitive detector of light quanta. In fact, high speed black-and-white film (which consists mainly of microcrystalline grains of AgBr or AgBrI suspended in gelatin on an inert base) ranks with the photomultiplier tube as capable of detecting a very few individual light quanta. Exposure times can vary from minute fractions of a second to hours. Unlike the multiplier tube, the photographic emulsion also responds well to relatively high light flux, that is, film can have wide exposure latitude. In many respects such as sensitivity, latitude, resolution, etc., film sets the pace as new multiplier tubes and charge-coupled devices are developed.Of course, the high sensitivity of film comes about because light absorbed within an emulsion grain causes a latent image to be formed (usually on the surface), which then renders the entire grain developable. The tabular grains of a modern high speed emulsion are largely triangular or hexagonal single-crystal platelets approximately 10 ü across and 0.1 ü thick. Such a grain will contain about 109 silver atoms, and it can be sensitized by a few molecules of gold sulfide or other additives adsorbed on its surface.In the concentration speck theory of the latent image, light is absorbed throughout the grain, but this energy is transported by the motion of electrons to a sensitivity center usually on the surface where the latent image is formed.
The Improbability of the Photographic Process
Authors: Slifkin Lawrence 
Published: August 2016

The very high sensitivity of silver halide photographic emulsions is the result of a surprisingly high quantum efficiency in the formation of the latent image, combined with a large amplification of the stored optical signal upon photographic “development.” The efficient formation of the latent image can be traced to the effects of an unusual set of physical properties of silver bromide and silver chloride, involving the electron energy band structure, the dynamics of photoelectrons, the nature and mobilities of the ionic point defects, and the existence of a sub-surface electric field.Despite the current availability of a wide variety of optical recording systems, the standard silver halide photographic emulsion continues to offer a unique combination of sensitivity, resolution, tone quality, convenience, and economy. This article will outline the physical processes that operate in forming the image. It will emphasize the unusual set of properties of silver bromide and silver chloride that are involved, and that impart to the process its extraordinary efficiency. Only black-and-white images will be considered, but the same basic imaging process is involved in color photography as well.This discussion is, of necessity, brief and often qualitative, but more complete treatments of the scientific aspects of the photographic process can be found in the other articles in this issue of the MRS BULLETIN, as well as in the bibliography.
Microscopic Analysis in Archaeology
Authors: Stevenson C. , Prior C. 
Published: August 2016

The papers in this edition of the MRS BULLETIN were among those presented during a workshop entitled “SAS Interfaces '87: Microscopy for the Archaeologist.” The workshop was sponsored by the Society for Archaeological Sciences at the 52nd annual meeting of the Society for American Archaeology held in Toronto, Ontario, May 1987. The Society for Archaeological Sciences is an interdisciplinary professional society for researchers involved in the broad spectrum of physical science applications to archaeology in order to promote interaction among scientists interested in different aspects of common research problems.Archaeometry, i.e., “archaeological science,” is concerned with the physical analysis of archaeological materials and the application of techniques from the laboratory sciences to the objectives and needs of archaeology. It includes such activities as compositional analysis, reconstruction of past technologies and processes, remote sensing, paleo-environmental reconstruction, and of course, isotopic and other chronometric dating methods. Such techniques alone, however, yield results that mean little without appropriate application to anthropological problems. The chief concern of archaeologists is to choose the most appropriate analysis method to achieve results that are useful in interpreting cultural behavior. To that end, laboratory analysts need to be aware of the interests and concerns of archaeologists, and archaeologists need to be able to understand the technical advances in archaeometry to incorporate them into their research.
Expert Vision Systems in Archaeometry
Authors: Russ John C. , Rovner Irwin 
Published: August 2016

In the analysis of object or material form and structure, especially micro-structure, correlations of material properties with their microstructure, and of structures with their production history and function, are at the heart of much of artifact and fossil analysis in archaeometry. Presently, a great deal of such examination of archaeomaterials is either:∎ qualitative, descriptive and anecdotal, comparing “representative” specimens to illustrate the differences of mean, typical, or normative structures, and forms; or∎ limited to measurement of parameters which oversimplify the structure or are easily measured by hand, e.g., length, width, and thickness.These do not differentiate shape variation or describe irregular shapes effectively. Hand measurements, even simple ones, are often difficult to derive on microstructures or on irregular macroscopic-sized objects and normally involve too few data points for statistical interpretation. Images of tesselated mosaics and multiphase microstructures in materials such as metals or ceramics are often chaotic and irregular in form, size variation and distribution of elements, inclusions and phases. Because of this, they are difficult to quantify precisely or accurately. Moreover, analysis is often limited more by the need to minimize destruction to an irreplacable artifact or art object than by a method's ability to generate significant data. Sample size is often held at the minimum threshold of significance or adequacy. Thus, any method which enhances the quality and quantity of such data should be welcome in archaeometric research.
Up Close: Advanced Light Source at Lawrence Berkeley Laboratory
Authors: Robinson A. L. 
Published: August 2016

A marriage of the new and the old is under way at the Lawrence Berkeley Laboratory (LBL), Berkeley, California. The new is the Advanced Light Source (ALS), a facility for generating laser-like, partially coherent beams of x-ray and ultraviolet (collectively, the XUV) synchrotron radiation of unprecedented spectral brightness. (See Figure 1.) The old is the domed hall that has sheltered the historic 184-inch cyclotron, a nuclear accelerator built 46 years ago by the laboratory's founder E.O. Lawrence. The ALS is to reside in an enlarged version of the old hall, a familiar landmark in the Berkeley-San Francisco area whose architectural features are to be preserved.Another sign of the marriage is an increased emphasis on materials research. Though by no means forsaking its nuclear science origins, LBL has seen its budget for materials research grow steadily in recent years, especially with the establishment of the Center for Advanced Materials and the construction of two new laboratories to house its activities. [See the April 1988 MRS BULLETIN, p. 54, for an Up Close article on LBL's National Center for Electron Microscopy.] With its focus on the use of electromagnetic radiation for structural and spectroscopic studies of physical, chemical, and biological systems, including those investigated by materials researchers, the ALS fits neatly into this new emphasis. In fact, funding for the $98.7 million ALS comes to LBL through the Division of Materials Sciences of the U.S. Department of Energy (DOE).
Physics of Thermal Wave NDE of Semiconductor Materials and Devices
Authors: Opsal Jon , Rosencwaig Allan 
Published: August 2016

Thermal wave physics is playing an ever increasing role in the on-line characterization of semiconductor materials and devices. This is especially true for thermal wave methods that employ laser beams for both the generation and detection of thermal waves. For the modulated reflectance method discussed here, the pump and probe beams are focused on the same spot. They therefore achieve the noncontact advantage of optical methods in addition to the optimum condition for high spatial resolution, a necessary condition for thermal wave measurements on product wafers.When a material is excited with an intensity-modulated laser beam or pump, a thermal wave is generated in the material and in the air above the sample. The material within this heated region will undergo a thermal expansion which can be detected with a probe beam interferometer or by deflecting the probe beam from the thermoelastic deformation of the surface. Since the complex refractive index of most materials depends on temperature, a modulated temperature will also induce a corresponding modulation in the refractive index and consequently a modulation on a probe beam passing anywhere near the thermal wave. A probe beam directed along the heated surface of the sample, for example, will be deflected as it passes through the heated region above the surface. This mirage effect can also be observed within the sample by directing a transmitting probe through the heated region beneath the surface. Likewise, using a probe beam directed onto the sample surface one can observe a modulation in reflection, transmission, or scattering. A related noncontact method is the photothermal measurement of infrared radiation emitted from the material's heated region. Note that with all these detection methods, thermal wave measurements can be, and most often are, done in air and at room temperature.
Real-Time X-Ray Diffraction For Materials Process Control
Authors: Green R.E. 
Published: August 2016

As useful as classical x-ray diffraction techniques have been, the ability to obtain x-ray diffraction images with extremely short exposure rimes opens up new opportunities for materials scientists, including real-time materials process control. This article briefly describes state-of-the-art systems for obtaining extremely rapid and real-time x-ray diffraction images and gives several examples of their applications for materials process control.Two generic electro-optical methods permit real-time viewing and recording of x-ray diffraction images. The first uses a low-intensity conventional x-ray tube source leading to a low-intensity diffraction image, which requires a high-gain electro-optical imaging system. The second uses either a high-intensity rotating anode, synchrotron, or flash x-ray source. Such a high-intensity source produces a high-intensity diffraction image, permitting use of a low-gain high-resolution electro-optical imaging system.Figure 1 schematically shows two types of image intensifier tubes which have been most often used to view x-ray diffraction images. By cascading three individual first generation image tube stages (Figure 1a), light gains as high as several million can be obtained. The second generation microchannel-plate image intensifier tube (Figure 1b) is similar to a single-stage first generation device except for the extremely important addition of a microchannel plate.
High-Performance Polymer Fibers
Authors: Adams W. Wade , Eby R. K. 
Published: August 2016

Since the pioneering work of Carothers which led to the introduction of strong nylon fibers by DuPont in the 1930s, polymer scientists have pursued the development of high-performance fibers to replace natural or metallic products, both to improve mechanical properties and to reduce weight. That development was relatively slow and evenly paced until DuPont again revolutionized the field with the release of Kevlar™, an aromatic polyamide with unprecedented mechanical properties. Since then, the field has literally boomed with new developments, and now organic fibers are available with properties that compete with the best inorganics and are far superior to metal fibers.Strong motivation for the invention of new organic fibers comes from the aerospace industry, which seeks fibers to use in reinforced composite structural materials. Composites bring new advances in stiffness (airplane wings can't bend too much!) in weight savings (every kilogram saved in the structure of an airplane saves $120 over its lifetime, and in a spacecraft $10,000), and in radically new ideas, such as radar-invisibility (stealth)5 and mission-adaptive wings (in-flight variable-shape wings). Hence, for a variety of specialty applications, otherwise commercially indefensible materials become viable.It may be somewhat counter intuitive to materials scientists unfamiliar with polymers to expect polymer mechanical properties to be greater than in the best metals. The origin of high strength and stiffness in a polymer fiber is the covalent bond, especially when aligned in an ordered array of long chain molecules.
Current Research Issues in Silicon Nitride Structural Ceramics
Authors: Pasto Arvid E. 
Published: August 2016

Ceramics have long been known for their refractoriness, or ability to bear loads at elevated temperatures. However, until the 1960s, the predominant refractory ceramics were oxide-based materials such as silica, zirconia, alumina, mullite, magnesia, and their combinations, including silicates. These ceramics were, and still are, used for firebrick furnace linings, crucibles and liquid metal carrier liners, regenerators, and recuperators.However, these materials all possess some characteristic which precludes their use for very high stress, high temperature applications. Typically, the silicates form viscous liquids which allow creep, while zirconia and alumina suffer from poor thermal shock resistance, and magnesia possesses a large thermal expansion coefficient. Consequently, for heat engine applications which involve high temperatures, high stresses, sudden temperature changes (e.g., startup), and may involve the maintenance of tight operating tolerances, a new family of materials is required. The requisite properties for heat engine applications may be found in certain non-oxide materials, namely silicon nitride and silicon carbide. They possess high strength even at high temperatures, low thermal expansion coefficient, and excellent thermal shock resistance. These materials are not thermodynamically stable in air at elevated temperatures and will eventually react to form oxides. Nonetheless, they possess excellent oxidation resistance by virtue of protective silica-based glass oxidation layers.
Multilayers: A Research Tool for Mechanical Property and Alloy Phase Stability Investigations
Authors: Jankowski A.F. 
Published: August 2016

The magic of multilayer structures — comprised of a regular repeating pattern of alternating layers that vary in thickness from less than 1 nm to more than several micrometers — is present today in nearly every facet of materials science.A technological gamut of issues has been approached through the use of multilayer structures. Material systems have been routinely investigated, ranging from simple binary through complex quaternary and including nearly every element of the periodic table. Applications include thin-film semiconductor devices in the form of strained-layer superlattices; protective coatings for improved surface hardness and wear resistance of conventional alloys (tribology); and reflective and transmissive x-ray optical devices. Multilayer structures have also provided an experimental means to investigate the interdiffusion and stability of alloy phases; the relationship between the presence, lack, or variations of crystallinity with magnetism (and most recently superconductivity); and the role of interfaces in adhesion and elastic/plastic behavior.
Materials Analysis with High Energy Ion Beams Part II: Channeling and Other Techniques
Authors: Gossmann H-J. , Feldman L.C. 
Published: August 2016

AbstractThis article discusses uses of high energy ion beam scattering for materials analysis, including channeling, particle induced x-ray emission (PIXE), and nuclear reaction analysis (NRA). These additional capabilities used in conjunction with RBS equipment provide capabilities for crystalline defect studies and light element detection.
Materials Analysis with High Energy Ion Beams Part III: Elastic Recoil Detection
Authors: Dunselman C.P.M. , Bik W.M. Arnold , Habraken F.H.P.M. , der Weg W.F. van 
Published: August 2016

AbstractThe fundamentals of the high energy ion beam technique Elastic Recoil Detection are presented. The potential of this analysis technique for the depth-resolved determination of light elements in a heavy matrix is illustrated with examples from semiconductor technology.
Chalcogenide Glasses
Authors: Taylor P. Craig 
Published: August 2016

Although there are some significant exceptions, most important glass-forming systems contain elements from the sixth, or chalcogenide, column of the periodic table (oxygen, sulfur, selenium, or tellurium). The glasses which contain oxygen are typically insulators, while those which contain the heavier chalcogen elements are usually semiconductors. Even though oxygen is technically a chalcogen element, the term “chalcogenide glass” is commonly used to denote those largely covalent, semiconducting glasses which contain sulfur, selenium, or tellurium as one of the constituents.The chalcogenide glasses are called semiconducting glasses because of their electrical properties. The electrical conductivity in these glasses depends exponentially on the temperature with an activation energy which is approximately one half of the optical gap. In this sense these glasses exhibit electrical properties similar to those in intrinsic crystalline semiconductors. The analogy is by no means perfect. The mobilities for the charge carriers in these glasses are very low (< 10 cm2/V-s) compared to crystalline semiconductors, and there are even discrepancies in determining the sign of the charge carriers from measurements of the Hall effect and the Seebeck effect.The first detailed studies of the chalcogenide glasses were performed about 30 years ago. For many years the prototype compositions have been selenium (Se), arsenic triselenide (As2Se3) or arsenic trisulfide (As2S3), and germanium diselenide (GeSe2) or germanium disulfide (GeS2).
Synchrotron X-Ray Powder Diffraction
Authors: Cox D.E. 
Published: August 2016

X-ray powder diffraction is one of the most widely used techniques by scientists engaged in the synthesis, analysis, and characterization of solids. It is estimated that there are now about 25,000 users throughout the world, of which about one third are in the United States. Any single-phase polycrystalline material gives an x-ray pattern which can be regarded as a unique “fingerprint,” and modern automated search-and-match techniques used in conjunction with the Powder Diffraction File (maintained by the International Center for Diffraction Data, Swarthmore, PA) allow routine analysis of samples in minutes. From an x-ray pattern of good quality it is possible to determine unit cell parameters with high accuracy and impurity concentrations of 1-5%, so that powder techniques are extremely valuable in phase equilibrium studies and residual stress measurements, for example. In addition, a detailed analysis of line shapes gives information about physical properties such as the size and shape of the individual crystallites, microscopic strain, and stacking disorder.In the early days of crystallography many simple (and some not-so-simple) structures were solved from x-ray powder diffraction patterns, but the obvious limitations to the number of individual reflection intensities which can be estimated and the increasing sophistication of single-crystal techniques resulted in a decline in the importance of this application in the 1950s and 1960s.