Materials Science Aspects Research Articles

High-temperature superconducting microwave devices: Fundamental issues in materials, physics, and engineering

High-T c superconductivity has generated a great deal of interest because of the challenges it presents in the fields of material science, condensed matter physics, and electrical engineering, and because of the potential applications which may result from these research efforts. Thin-film passive microwave components may become the first high-temperature superconducting (HTS) devices available for widespread use and commercialization. In this article, we review aspects of material science, physics, and engineering which directly impact high-T c superconducting microwave devices and discuss issues which determine the performance of these devices. Methods of growing HTS thin films on large-area substrates, techniques for fabricating single-level HTS passive microwave components, and the relevant properties of high-T c superconducting films are discussed, with a focus on thin films of the HTS material YBa2Cu3O7−δ. Several known mechanisms for microwave loss in both the superconductor and the dielectric substrate are presented. An overview of the general classes of superconducting passive microwave devices is given, and representative microwave devices which have been recently demonstrated are described in detail. Examples of a select few HTS active microwave components are also presented. Potential microwave applications are illustrated with comparisons to current technology.

Materials Issues In X-Ray Mask Repair by Focused Ion Beams

AbstractIn x-ray mask repair high Z absorber features, such as gold or tungsten, must be removed or added. The main challenges are the small lateral dimensions (0.25 μm and below) and the thickness of the absorbers (˜ 0.5 μm) The focused ion beam appears to be the best tool developed to meet this challenge. Unwanted features are removed by ion milling while missing absorber is reconstructed using ion induced deposition from a locally piped-in precursor gas. The high aspect ratio of the features complicates both of these processes. Milling away 0.5 μm thick absorber can lead to redeposition of the sputtered material on neighboring features. The crystal grains of the absorber mill at different rates depending on orientation which results in nonuniform features. A possible alternative which only works with W absorber is to use ion assisted etching. In ion induced deposition a precursor gas such as dimethylgold hexafluoro acetylacetonate is provided by a capillary tube aimed at the region scanned by the ion beam. The incident Ga+ ions, usually at energies in the 25–100 keV range, dissociate the adsorbed precursor molecules leaving a deposit of gold mixed with carbon. The carbon content can approach 50 atomic % resulting in an x-ray attenuation which is about one half of that of pure gold. A number of unexplored materials science issues are associated with mask repair including: the reduction of the carbon content, redeposition both from milling and from induced deposition, milling as a function of crystal orientation and energy, and deposition of high aspect features. The technology is well enough developed so that mask repair of 0.25 μm features can be considered. However, a better understanding of the materials science aspects of x-ray mask repair will help to advance the state-of-the-art.

Graduate Education for Materials Scientists and Engineers: General, Special, or Fundamental?

What is an appropriate educational program for preparing a PhD to enter the general work force, particularly in materials science and engineering, but also more broadly in all science and engineering fields? The question can be proposed at two different levels: What is the character of the information, knowledge, and the training a student ought to store away and be able to use after leaving the academy, and what specific information or courses does someone need to be an expert?Since I do not have expertise in every aspect of materials science and engineering, and since the latter question can be handled through concerted effort of the appropriate experts, I will focus only on the first question.To paraphrase the first question more starkly, how much of a generalist should a PhD be and how much of a specialist? I will try to define the generalist and specialist in polar perspective, in the sense that I use them:1. A specialist must be grounded in that specialty, conversant with its literature and new findings, and able to converse with other specialists in the field to exchange information and perspectives.2. A generalist must be well-grounded in the fundamentals of numerous fields. It is not necessary to be a specialist in many fields, but a generalist must have access to and be able to find and digest the happenings and literature in these other fields.

Theory of Solid-State Defects

Serious studies of materials are often serious studies of defects, for control of properties of materials implies control of defects or impurities. Understanding defect phenomena is crucial, and both theoretical ideas and modeling are enhancing key areas of materials properties and processing. I shall review some of the ways theory contributes. Theory enters into all aspects of materials science, even if you don't always realize you are using it.Even self-styled practical people, for whom theory is a luxury, use theory routinely in its first main role, as a framework for the data they lovingly collect. Elasticity theory, electromagnetic theory, and thermodynamics are normal tools for working engineers. The simplest ideas about electronic and atomic structures of solids are now so standard that one can forget their original impact, just as one forgets those within living memory who objected even to the idea of atoms. It was theory which gave clear guidelines for solids to be metals or insulators, when the real-space ideas of crystal structures based on interacting atoms were complemented by the reciprocal space notions from band theory. Such rules had been far from obvious. The behavior of amorphous solids has forced analogous theory-led upheavals in understanding.

The dental amalgam issue. A review

Using an interdisciplinary approach, the current position in the dental amalgam controversy and the potential impact of amalgam mercury on human health are reviewed. Aspects of materials science, corrosion, mercury exposure, toxicology, neurology and immunology are included. New data on mercury exposure from corroded amalgam fillings in vivo are presented. The exposure can reach levels considerably over known threshold limit values. Also, measurements of mercury absorption from intraoral air are presented. The vital importance of avoiding a galvanic amalgam-gold coupling is emphasized. The symptomatology of a disabled patient, who recovered after amalgam removal, has been included. It is concluded that discussion of the dental amalgam issue has suffered from the lack of an interdisciplinary approach. It would be wise to learn from the lesson of acrodynia, and consider amalgam mercury among other possible factors in neurological and immunological diseases of unclear etiology.

Structural Concepts for Disordered Inorganic Solids. Modern NMR Approaches and Strategies. Invited Review

AbstractMany technologically interesting materials properties are caused by intrinsic structural or dynamic disorder phenomena in solids. For this reason, the structural characterization of disordered states constitutes a central aspect of materials science. Within the past decade, nuclear magnetic resonance techniques have made increasingly significant and detailed contributions to this subject. The present review will portray some of the more common methods employed and discuss several important applications to problems in various inorganic materials areas.

Identity of and Need for Undergraduate Materials Science and Engineering Education

A litany has recently emerged which proclaims materials science and engineering a primary enabling technology for most aspects of a modern high technology economy. More materials engineers have been called for, but employers and academia have not yet agreed on what job description or curricula should define a materials engineer. While the research or science aspects of materials science have been functioning well, manpower availability and industrial materials technology for commercial, military, environmental, and other societal needs lag behind our worldwide competitors.to nucleate the growth of a consensus and to create awareness and understanding of materials science and engineering begs an answer. In the absence of a consensus to help focus curriculum and increase awareness of materials science and engineering, the current diverse educational practices will remain, and a rare opportunity for professional development will be lost.

Material science aspects of SOFC technology with special reference to anode development

A model is presented for the development of alternative oxide anodes that can be optimised either for the complete or partial oxidation of methane. The model requires information about the kinetics of oxygen surface exchange and diffusion, and relevant data using 18O/ 16O isotopic exchange and SIMS measurements are summarised. Materials selection requires further information about the relevant defect chemistry and electronic conductivity and La 0.8Sr 0.2FeO 3− σ and CeO 2− x are used as examples of anode materials that can be used to electrochemically oxidise CH 4 to CO 2 and H 2O. The performance of these materials in solid oxide electrolyte fuel cells is analysed in terms of the parameters mentioned earlier, and a strategy is suggested for the development of alternative oxide anodes for both the complete and partial oxidation of CH 4.

Importance of quantitative trace analysis in industry today

Trace analysis in the industrial analytical laboratory represents a substantial portion of the overall lab workload. This paper will explore some of the kinds of analyses that are done, why they are done, and what the limitations are to our current capabilities. Industry represents the full diversity of analytical problems, and even within one company, such as BP America, important trace quantitation problems can arise from petroleum products, ceramics, minerals, biological materials, chemicals, catalysts, and, of course, environmental samples relating to all of these. It would be impossible to review all of the trace analytical methods used for such a diverse set of samples, to compare relative merits, or to in any way survey the field of trace analysis in industry. Rather, this paper looks at certain major themes that are driving the entire area, overlapping many techniques in each case. For all of the diversity of quantitative industrial trace analysis, three motivational themes seem to dominate: samples where the trace quantity provides the value to a product; samples where trace species degrade the value of a product; and, samples where trace species represent a potential hazard to human, animal or plant life. In suggesting these categories, and in the subsequent discussion, I am removing from the realm of trace analysis problems in which the analyte is in high concentration but small quantity. For some techniques these may present the same problem as low concentration trace analysis, but increasingly, we find that instrumentation has evolved considerably in the ability to handle small samples. The first category, trace quantities as key to product value, is probably most noticeable in importance today for the electronics industry. While classical chemistry recognized the importance of certain trace elements or compounds, it was the electronics industry, beginning in the earliest days of the transistor and continuing to the present, that turned this into a picoscience. Examples in other aspects of chemistry and materials science abound. Modern heterogeneous catalysts have derived selectivity and activity from trace elements. Metallurgists, ceramists, and polymer scientists can bring about significant improvements in material properties by adding trace quantities of appropriate substances. The analytical challenge here has been considerable. In many cases we are asked to analyze very low levels, with a high degree of quantitation, and on solid phases. It is the latter point that probably has provided the greatest challenges and the most innovative solutions. The triumphs of SIMS, an industrial innovation, despite its being a destructive technique, are to be particularly noted in this field. Many advances have also come from Fourier transform techniques, in NMR, IR, and mass spectrometry. Even in such well developed areas as atomic spectroscopy, the introduction of low temperature plasma ashing and acid digestion using sealed Teflon vessels has permitted dissolution of solids with almost no loss or contamination. There still remains much to be done. While SIMS provides some depth profiling, we continue to be challenged by deep interfaces. These are of great importance, but analytical methodology for reaching and analyzing them is decades behind our ability to deal with surfaces. The second area is also a well established problem in the electronics industry, but pervades much of the rest of chemistry. While some trace elements provide catalyst selectivity, others are potent catalyst poisons. Relatively low levels of metals in coke (iron, nickel, vanadium) result in substantial drops

ChemInform Abstract: Material Science Aspects of Seignette‐Magnetism Problem

ChemInformVolume 19, Issue 4 Reviews ChemInform Abstract: Material Science Aspects of Seignette-Magnetism Problem YU. N. VENEVTSEV, YU. N. VENEVTSEV L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this authorV. V. GAGULIN, V. V. GAGULIN L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this authorI. D. ZHITOMIRSKII, I. D. ZHITOMIRSKII L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this author YU. N. VENEVTSEV, YU. N. VENEVTSEV L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this authorV. V. GAGULIN, V. V. GAGULIN L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this authorI. D. ZHITOMIRSKII, I. D. ZHITOMIRSKII L. Ya. Karpov Inst. Phys. Chem., Moscow 107120, USSRSearch for more papers by this author First published: January 26, 1988 https://doi.org/10.1002/chin.198804380Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue4January 26, 1988 RelatedInformation

Quality Assurance in Manufacturing High-Performance Ceramics

Quality assurance of ceramic components during various processing stages is an important ingredient in assuring the reliability in engineering applications. The current advances which are made in advanced nondestructive evaluation of finished components have been very useful. However, the importance of in-process quality control in closed-loop iterative process and product development has to be understood in terms of materials science aspects. This paper addresses some of the tools in nondestructive evaluation which are available in ceramic manufacture and gives illustrations of successful implementation of those techniques in two categories of ceramic applications, current and advanced. Further research and development needs in the NDE are also briefly addressed.

Ferroelectric oxides and related substances: Growth and study of single crystals

Known varieties of ferroelectrics have been characterized and their possible applications considered in particular as single crystals. Some materials-science aspects of the ferroelectric problem have been treated. Results of a search for ferroelectric oxides, including some results on growing and studying their single crystals, are described. Perspectives of further search and applications of ferroelectric organic and inorganic substances including ferroelectric metal oxides are discussed.

Solid state nuclear track detectors

The materials science aspects of the use of both polymeric and inorganic solids as detectors for energetic particles are reviewed. The various models proposed to explain the formation of an etchable track by a penetrating particle are discussed, as is the nature and the geometric consequences of the etching process itself. An account is given of the wide-ranging applications of solid state detectors in science and technology.

Materials science aspects of reliability of fuel elements of water-cooled power reactors

Materials science aspects of reliability of fuel elements of water-cooled power reactors

Aspects of materials science of interest to tectonic studies

Of The current research trends in tectonophysics, the study of deformation mechanisms and of relations quantifying their characteristic stress-strain-time behaviour (constitutive equations) should produce some of the most significant improvements in the interpretation of the structures and fabrics of deformed rocks. Such studies can shed light on phenomena as widely disparate in scale as the extent to which geologically significant flow occurs in the Earth's mantle, and the nature of preferred orientation in tectonites. They deal with phenomena that are of fundamental importance in attempts to model the structural evolution of the Earth's crust, either by computer studies or by scaled physical analogues of rock behaviour. In model studies the behaviour of real rock is assumed to follow a specific constitutive equation, i.e. a deformation mechanism is assumed. Yet many geologists are unfamiliar with the physics and chemistry of deformation processes, and even those researching these fields rarely have the time to take full advantage of the enormous quantities of pertinent literature produced by materials scientists. Geologists and materials scientists both face similar problems in studying the phenomena of flow and fracture. Moreover, the increasing industrial concern with ceramics as new engineering materials means that scientists working in these two fields are interested in the deformation properties of often very similar materials. Meetings designed to promote an exchange of ideas can thus be of benefit to both disciplines. An important role of such meetings is to serve as the extent to which geologically significant flow occurs in the Earth's mantle,

Materials science and materials engineering education

The report deals with the complex of problems concerning education of materials scientists and materials engineers. The development of materials science is described. It is attempted to estimate the future demand for materials scientists and materials engineers. Educational and organizational aspects of materials science and materials engineering in higher education are discussed. A selection of topics forming a possible core for materials science and materials engineering studies is presented. Finally, university-industry relations in the field of materials are discussed. A survey of materials programs in 133 higher education establishments in 13 countries has been made. The results of this survey are not included in the report, but they are available from OECD on request.

Le rôle de la diffraction des rayons X dans la science des matériaux

A review is given of the applications of X-ray diffraction to various aspects of Materials Science e.g. phase identification and quantitative analysis in micro-crystallised solids, determination of textures, detection of defects by X-ray topography and the study of periodicity defects in solid solutions. Emphasis is put on the fact that the experimental methods must be often more refined in applied researches than in fundamental ones.

New porous biomaterials by replication of echinoderm skeletal microstructures.

AN important aspect of materials science is the development of new porous solids for prosthetic applications, especially for synthetic teeth and bone replacement. To be acceptable, such biomaterials must meet some rather demanding specifications, among which are high strength and compatibility with-body fluids or tissues. The structure of the porous medium is important as the pores must be both interconnected and have the proper size, shape and uniformity to permit ingrowth and attachment of body tissue. The problem lies in attaining the optimum combination of these properties to yield a high strength to weight ratio material, with a microstructure which best facilitates firm attachment of tissue. Ideally these materials should be easily machined or fashioned into particular shapes for different individual implants, and should be relatively inexpensive.

Introduction to Dislocations

In materials science, dislocations are irregularities within the crystal structure or atomic scale of engineering materials, such as metals, semi-conductors, polymers, and composites. Discussing this specific aspect of materials science and engineering, Introduction to Dislocations is a key resource for students. The book provides students and practitioners with the fundamental principles required to understand dislocations. Comprised of 10 chapters, the text includes advanced computer modeling and very high-resolution electron microscopy to help readers better understand the structure of atoms close to the core of dislocations. It shows that atomic arrangement has a significant effect on the formation of dislocations and thereby on the properties of solids. The first two chapters of the book present an overview of dislocations. The crystal structures and the various defects and dislocations are discussed, and methods of observation and diagnosis of dislocations are covered. Chapters 3 to 5 discuss the behavior of dislocations and explain how changes in the structure and arrangement of atoms can affect the behavior of dislocations. The three chapters also discuss the mechanical properties of dislocations. The remaining chapters offer a detailed discussion of the mechanisms of dislocations and the mechanical strength of crystalline solids. The book is written for undergraduate- and graduate-level students in both materials science and mechanical engineering. Non-experts and novices working on mechanical properties, mechanisms of deformation and fracture, and properties of materials, as well as industrial and academic researchers, will find this book invaluable. * Long-established academic reference by an expert author team, highly regarded for their contributions to the field.* Uses minimal mathematics to present theory and applications in a detailed yet easy-to-read manner, making this an understandable introduction to a complex topic.* Unlike the main competition, this new edition includes recent developments in the subject and up-to-date references to further reading and research sources.