bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties and Control of “Stickies” in Paper Recycling
Authors: Doshi Mahendra R.
Published: August 2016

Large amounts of waste paper are generated every day and interest in its reuse has increased steadily due to environmental concerns and improved economics. In 1990 in the United States, for example, 28.9 million tons of recovered papers were collected for recycling. By 1995, that amount is expected to increase to almost 40 million tons with a collection rate of almost 40%. To facilitate the use of secondary fibers, sticky contaminants, or “stickies,” must be controlled.

Classification and Properties of Stickies

Recovered paper bales usually contain extraneous materials such as sand, glass, staples, nails, inks, coatings, plastic, styrofoam, wax, EVA (ethylene vinyl acetate), and SBR (styrene butadiene rubber). A particularly troublesome contaminant in recovered paper is “stickies” which, in their original state, were used as paper adhesives. Inks and coatings can also be a source of stickies. Inks are primarily composed of a pigment, liquid vehicle, binder, and modifier. Coating formulations contain several ingredients that can be classified as pigments, binders, and additives, such as plasticizers, thickeners, dispersants, dyes, preservatives, and defoamers. Note that both inks and coatings mixtures contain binders which contribute to the stickies problem. Common binders used in inks are hydrocarbon resins and rosin esters while those used in coating formulations include starch, soya protein, acrylics, and polyvinyl acetate. An overview of stickies was presented by Moreland.

Stickies can be classified into three categories: hot melts, pressure-sensitive adhesives, and latexes. Although wax can be a contaminant, it is not included separately because it is similar to and an important ingredient of most hot melts.Contaminants such as plastics and styrofoam are also excluded from this discussion because they are not stickies.
Filler Pigments Designed for Recyclability
Authors: Passaretti June D. , Young Trudy D. , Herman Mick J. , Evans D. Bruce
Published: August 2016

Printing and writing paper represents 30% by weight of all domestically made paper products. Today, however, less than 50% of that paper is recycled. The problem with waste paper from homes and offices is that it contains dyes, inks, and chemicals. If these additives are not removed properly—with no fiber degradation—the recycled paper will be of an inferior quality for writing and printing.

Recycling, however, is the future. In 1990, 28.9 million tons of paper were collected for recycling, representing a collection rate of 33.5%. By the year 1995, the collection rate goal is 40%, with favorable economics supporting increased utilization of recovered paper. For example, a ton of paper made from 100% waste paper saves 17 trees, 4,100 kWh of energy (approximately 6 months of power used by the average home), 7,000 gallons of water, 60 pounds of air-polluting effluents, and 3 cubic yards of landfill.

Two of the issues facing recycled fiber utilization are the cost and visual quality of the final sheet. Paper brightness, opacity, and printability are the industry's biggest concerns when comparing the quality of recycled fibers to that of virgin fibers. The common approach to increasing brightness is to add a white filler pigment such as precipitated calcium carbonate (PCC), ground limestone, clay, and/or titanium dioxide. Chemical optical brighteners have also been used, but their use will decline as consumers ask what impact the brightening chemicals have on the environment.
Up Close: Institute C. Sadron Takes a Comprehensive Approach to Polymer Blends
Authors: Weill Gilbert
Published: August 2016

If one defines a polymeric material as a piece of matter designed for a given and usable property, this property is not related simply to the chemical formula of the polymer. The chemical and stereochemical defects occurring during synthesis, structural organization, and processing must all be characterized, understood, and controlled.

Institute C. Sadron (ICS), established in 1954 by the French National Research organization (CNRS) as the Centre de Recherches sur les Macromolécules under the inspiration and direction of Prof. Ch. Sadron, has progressively shifted from polymer synthesis and characterization toward the understanding of the structure-property relationship in the sense just described. This has involved the creation of an engineering school staffed with equipment and research teams in rheology, processing, and mechanical properties. More than 60 permanent scientists and university professors work in the Institute; about 20 theses are submitted each year. ICS now covers a broad range of competencies, from synthesis to processing through most techniques of characterization and theoretical modeling at the molecular and macroscopic levels. This opens the way to a comprehensive research effort, which is illustrated here for polymer blends.
Pulsed Laser Deposition of High Tc Superconducting Thin Films for Electronic Device Applications
Authors: Chrisey Douglas B. , Inam Arun
Published: August 2016

The discovery of high transition temperature, Tc, superconductivity in copperoxide-based ceramics by Bednörz and Miiller, and the subsequent increase in Tc above the boiling point of liquid nitrogen (77 K), renewed interest in employing superconducting thin films in high-speed, low-power electronic device applications (e.g., compact high-quality factor filters, delay lines, and Josephson elements for high-speed, low-power switching). However, realization of these benefits requires well-controlled, reliable superconducting thin film technology which addresses not only the growth of superconducting thin films, but also the development of a multilayer device technology encompassing materials with metallic, semiconducting, and insulating properties.
An Overview of Industrial Waste Generation and Management Practices
Authors: Allen David T.
Published: August 2016

More than 12 billion tons of industrial waste are generated annually in the United States. This is equivalent to more than 40 tons of waste for every man, woman and child in the country. The sheer magnitude of these numbers is cause for concern and drives us to identify the characteristics of the wastes, the industrial operations that are generating the waste, the manner in which the wastes are being managed and the potential for reducing wastes. This article will provide a brief overview of the information available on waste generation and management. A more comprehensive examination of this topic is provided in a recent issue of the journal Hazardous Waste and Hazardous Materials devoted entirely to inventories of waste generation and management. This article will begin by examining the sources of industrial waste. From an analysis of the sources of industrial waste, we will move to an examination of management methods. Finally, we will note changes in rates of waste generation over the past decade and close by highlighting critical gaps in existing data.
Introduction to Environmentally Conscious Manufacturing
Authors: Watkins Randall D. , Granoff Barry
Published: August 2016

Pollution prevention and the preservation of environmental quality are issues that can no longer be ignored. For years, environmental organizations have struggled, somewhat unsuccessfully, with U.S. industry and congressional legislators, focusing on local, national, and worldwide issues relating to environmental quality. Meanwhile, global pollutants such as acid rain (from sulfur oxide emissions), carbon dioxide, volatile organics (such as chlorofluorocarbons (CFCs) and benzene), metals (such as chromium, cadmium, mercury, and lead), dioxins, and pesticides continue to be introduced into the environment. Many consider global environmental effects potentially serious due to “partitioning,” a phenomenon where pollutants migrate to the media where they are most stable. The result is contamination in the air, water, and soil, creating a high potential for exposure to pollutants. Consider, for example, the depletion of the earth's stratospheric ozone layer, promoted by the annual emission of various CFCs equivalent to the emission of over 100 million pounds of equivalent CFC-11 worldwide (CFC-11 has an ozone depleting potential of 1.0 with other CFCs having ozone depleting potentials between zero and one). Consider also the heavily debated global warming/greenhouse effect, caused to a large degree by CO2 emissions from spent fossil fuels, one-fourth of which are consumed in the U.S. Many examples can be cited regarding the presence of toxic substances in remote lakes and streams throughout the world. Now, as the ill effects of our past and present actions are becoming visible and finally better understood, the pressure on U.S. manufacturers is increasing to take responsibility for products and processes contributing to the world's environmental degradation. This pressure will continue to rise until real solutions to these problems are developed and implemented.
Alternatives to CFCs and Global Warming: A Systems Approach to Evaluating Net Contributions
Authors: Fischer Steven K. , McFarland Mack
Published: August 2016

CFCs proved to be one of the more useful classes of compounds ever developed because of their many desirable properties. They promote worker and consumer safety because they are nonflammable, noncorrosive, and very low in toxicity. They are used in a wide variety of applications, such as refrigerants, foam blowing agents, and cleaning solvents, because of their desirable physical properties that enhance energy efficiency and product reliability.

However, some of the properties that make CFCs desirable from a worker and consumer safety and applications standpoint have led to global environmental concerns. Because of their chemical stability, CFCs have long environmental residence times, and emissions lead to accumulation in the lower atmosphere. CFCs slowly mix into the upper atmosphere where they dissociate, releasing chlorine atoms that can catalyze destruction of ozone. Recent scientific findings have clearly linked chlorine from CFCs and other man-made compounds and bromine from man-made and natural sources to the seasonal ozone losses over Antarctica, the Antarctic ozone hole, and have indicated that these compounds are probably causing ozone losses over populated areas of both the northern and southern hemispheres as well. Since ozone provides a screen against solar ultraviolet radiation (UV-B) and excess UV-B has a potential to contribute to health and environmental concerns, significant reductions in ozone should be avoided. This information provides a sound basis for the Montreal Protocol, an international agreement amended in 1990 requiring a total phaseout of CFC production and consumption by 2000.
Status of Low-Dose Implantation for VLSI
Authors: Seidel T.E. , Larson L.A.
Published: August 2016

This article describes the current status of implantation in silicon for ion doses up to but not including the onset of the amorphous state. Physical phenomena, applications to VLSI, and equipment issues are discussed and linked from the viewpoint of vertically integrated technologies (see Figure 1). In such a view, engineering applications are the customer of research on phenomena, and the equipment industry is the customer of both the research and applications community. The article highlights areas in phenomena, applications, and equipment requiring particular attention.

Studies in physical phenomena associated with ion implantation are motivated by the need for very shallow junctions. The shallowness is limited by ion channeling effects in crystalline silicon (which directly affect the as-implanted impurity profile) and by diffusion (which occurs during implant activation and annealing of damage). The inventory of ion-damage induced defects includes point defects, cluster defects, and dislocations arising from the combination of damage and annealing. A recent survey by Schreutelkamp et al. of low-dose implantation describes advances in characterization of channeling effects, and the formation of dislocation damage which, in turn, impacts thermally processed profiles. These effects need to be understood in terms of modern MOS (metal-oxide-semiconductor) processes.
Subsurface Processing of Electronic Materials Assisted by Atomic Displacements
Authors: Williams J.S.
Published: August 2016

In the early years of doping of semiconductors by ion implantation, atomic displacements and residual lattice damage were considered undesirable byproducts of an otherwise controllable doping process. Steps were taken to minimize disorder during implantation and/or to remove it as completely as possible during a subsequent annealing process. In many cases, such as boron- or phosphorus-implanted silicon, annealing temperatures exceeding 900°C were necessary to achieve the desirable electrical properties. Indeed, removal of implantation damage remains a crucial issue, particularly as device dimensions shrink and the need has arisen for substantially lower processing temperatures. The advent of high-energy (MeV) implantation in specific processing steps and the increasing use of more complex (often multilayer) compound semiconductors has added further to the need to understand and control ion damage and its annealing in semiconductors.

Over the past decade, there has been a growing realization that implantation induced atomic displacements and defects can have significant advantages in processing. For example, it was realized early that ion damage, and resultant defect fluxes to and from lattice disruptions, can “getter” and trap undesirable impurities that would otherwise interfere with device operation. More recently, it has been possible to use ion beams to tailor damage structures and form amorphous-crystalline superlattices, to remove pre-existing damage and induce crystallization of amorphous layers at very low temperatures, to form ultrapure amorphous silicon for studying thermodynamic properties of this phase, or to mix films with semiconductors and form stable compounds such as silicides. Indeed, ion damage has been used to electrically isolate devices, to form optical waveguides and cavities, and to improve the junction properties of deeply doped layers. These issues are briefly reviewed in this article.
Why We Don't Have a Room-Temperature Superconductor—Yet: 1991 MRS Fall Von Hippel Award Address
Authors: Geballe T.H.
Published: August 2016

I would like to raise a question of interest to many of us here today: “Why have we not been able to find a room-temperature superconductor?” I have a scenario for why not that can be illustrated by projecting ahead 98 years. It is 2089, the tercentenary of the French Revolution. The revolt against science that started building up in the last decade of the 20th century has reached a crescendo and a revolutionary tribunal has erected a huge guillotine. Following in the tradition of Lavoisier's trial and execution, the presidents of the Materials Research Society, the American Chemical Society, and the American Physical Society have been found to be enemies of the people and have been sentenced to be guillotined. The president of the Materials Research Society steps up. In his final words, he says: “I have no regrets. We've supplied you with the pole vaults which have made possible a new world's record above 30 feet, we've given you automobile bumpers that prevent damage in crashes at 60 miles per hour, and we've given you tennis rackets that are big enough to allow you to cover from center court to the alley without having to take a step.” With that, he bravely puts his head on the block. Down crashes the knife but inexplicably it stops just before it reaches his neck. According to the rules he steps down a free man. Then the American Chemical Society president steps up and says: “I don't have any regrets either. We have given you body centered cubic diamond that makes it possible to build indestructible houses, we have given you disposable diapers that are biodegradable in 30 seconds, and we've reseeded the stratosphere with ozone. We have done our job.” She courageously puts her head on the block, and the guillotine comes down. Again it stops short and she walks away, a free woman. Then the president of the American Physical Society says: “I don't have any regrets either. We've circled the equator with our newest SSC and have given you the Higgs boson, we've given you light that you can squeeze until it hurts, and we've discovered over 100 theoretical models which should lead to room-temperature superconductors. We haven't given you any real ones because there aren't any—we've tested all the possibilities. But, by the way, while we've been standing here, I've done a back-of-the-envelope calculation and I've found out wha's wrong with this guillotine. If you give me a screwdriver I can fix it.”
High-Temperature Superconductors from the Grain Boundary Perspective
Authors: Babcock Susan E.
Published: August 2016

The high-transition-temperature superconductors (HTS) present a number of challenging materials science problems whose solutions must precede their use in applications. This article offers a view on our collective progress toward resolution of one central HTS issue, the “weak-link” character of high-angle grain boundaries.

Why Are HTS Grain Boundaries of Such Interest?

The properties of high-angle grain boundaries control the macroscopic electromagnetic character of all superconducting copper oxides that are produced in polycrystalline form. In particular, grain boundaries limit the transport critical current density (Jct) and determine its dependence on applied magnetic field (H) and temperature (T). Jct is the maximum macroscopic current density that the superconductor can support in the nondissipative state. H and T are the two most important environmental variables for applications of superconductivity. Thus, the Jct(H, T) characteristic largely dictates the types of applications for which a superconducting material can be used successfully.

High-angle grain boundaries are the immediate obstacle to further development of materials for applications that require large Jct values in high magnetic fields. The problem arises because most high-angle grain boundaries act like Josephson-coupled weak links. The characteristic properties of such junctions are a reduced zero-field Jct value and, more importantly, a strongly magnetic-field-dependent Jct that can decrease by more than an order of magnitude in even weak fields of a few millitesla (Fig. 1). Such Jct(H) characteristics are clearly a very serious problem for high-field magnet applications such as motors, generators, energy storage systems, and MRI machines.
Controlled Growth of High-Temperature Superconducting Thin Films on Polycrystalline Substrates
Authors: Shaw David T.
Published: August 2016

Since their discovery in 1987, significant progress has been made in the fabrication of high-quality, high-temperature superconducting (HTS) thin films. Films with reproducible properties can be routinely deposited on single crystal substrates by several well-established processing techniques. Single crystal substrates, however, are not suitable for many applications because of their cost, limitations in size and shape, and lack of flexibility. Hence, a great deal of effort has been directed at the fabrication of thin films on polycrystalline rather than single crystal substrates. For example, metallic substrates are expected to be useful for the fabrication of HTS conductors for such applications as generators, motors, and superconducting magnetic energy storage (SMES) devices. For polycrystalline thin-film applications, lattice matching for epitaxial growth of thin films is no longer possible. Microstructures of these films are generally more complex than those of single crystal films, primarily because of grain boundaries. As a result, the microstructure of polycrystalline films must be carefully controlled to ensure that the critical current density is high enough for practical applications.

Happily, progress in this respect has been substantial. There have been laboratory demonstrations of techniques for controlled processing of high-quality HTS thin films on polycrystalline substrates. Even though the technology development in this area is still in its infancy, many successful processing approaches have been developed to set the stage for the eventual use of HTS thin films in power device applications.
Will the Integration of Materials Science into Engineering Core Undergraduate Curricula Ever Be Complete? Is the “Chemistry” Right?
Authors: Ambrose John R.
Published: August 2016

Those in charge of creating and endorsing curricula for engineering colleges appear to generally agree that materials science should be included. More than jus an acceptance of ABET (Accreditation Board for Engineering and Technology) certification requirements, the consensus view is that engineers really need to know about the materials they will someday use Unfortunately, there appears to be some disagreement about where this exposure to materials science fits into the overal scheme of things (scheduling or course sequence, so to speak). There is also dis agreement as to what engineering students should know about materials and by inference, as to who is most knowledge able and best qualified to teach this information. As a result of these disagreements students at some engineering departments have had to take, during the final semester, an introductory materials course taugh by instructors whose professional experience lies outside materials science and engineering.
Initiating New Academic Programs in Materials Science
Authors: Mundschau M.
Published: August 2016

Materials science has come of age. The need now exists to establish programs in education and research in materials science at colleges and universities throughout the world. It is not realistic to expect that every university will receive funds to found entirely new programs. However, the infrastructure for materials science already exists at most universities that have offered traditional studies in the natural sciences. It is the purpose of this article to provide ideas and suggestions for initiating new academic programs in materials science by using existing resources. The major prerequisite for success is a faculty and staff who are willing and able to adapt to a rapidly advancing scientific environment and who have the individual initiative to seize and profit from the many new opportunities in materials science. This article reports an experiment in progress at Bowling Green State University, Ohio which uses the strengths of the Departments of Biology, Chemistry, Geology, Physics and Technology to develop a new program in materials science. I hope it will serve as a model for other universities.
Processes and Performance in Renaissance Painting
Authors: Alexander Ingrid C.
Published: August 2016

During the greater part of the 15th century, the Burgundian princes created a stable, unified center for industry and the flourishing of the arts in the Netherlands. Philip the Good became one of the most powerful and wealthy princes of the House of Burgundy in the period. Under his rule, the Netherlands became an important center for commerce. The port of Bruges, and later Antwerp, offered easy access to the important trade routes. The German merchants of the Hansa towns of Bremen, Danzig, Lübeck, and Hamburg and ships from England and the Baltic regions brought wares to be bought and sold in Flemish towns. The routes along the Atlantic and Mediterranean provided direct lines of communication between Italian merchants from Venice, Genoa, Florence, and Bruges.

The Netherlands soon became a center of a large part of the business activity in Europe and its prosperity grew. The concentration of trade, the presence of numerous banks, and the commission they charged contributed to the wealth of its bourgeois merchants and financiers. They soon became as rich and sometimes richer than the Burgundian princes. Thus they had the means to become important patrons of the arts so as to display their wealth. The acquisition of rare and exotic goods became an essential part of a society where exhibiting one's wealth was admired.

Flemish artists' corporations were well organized, not unlike modern businesses. They were well-known locally and abroad and had significant influence on the art of the period. Works of art were created in workshops where a long apprenticeship afforded the artists guidance and expert training in their craft. High standards which contributed to the good reputation of the art of Flanders, were maintained by setting the quality of the materials and establishing the techniques used. The painters' guild controlled the production of paintings and took measures to control the supply of materials to keep down prices and to control competition. Also, contracts between artist and patron would sometimes stipulate the type of materials to be used.
Up Close: Materials Science in Spain—Its Dynamic Growth
Authors: Ortiz C. , Gonzalez D.
Published: August 2016

The year 1992 is very special for Spain: 500 years have passed since the discovery of the American continent. That discovery helped make Spain the most powerful country in the world in the 16th century. In time, though, Spain lost its influence to England, and materials processing played a surprising role in this transfer. It has been shown that one of the main reasons Spain's “Invincible Armada” was defeated by the English Navy was that the Spanish ships used faulty cannon balls. The balls were of such poor quality that, once fired, they disintegrated before they could damage enemy warships. Faulty material technology—low compactness or degree of sintering—caused the disintegration.

As we approach the 21st century, the Spanish scientific community has reached a high level of expertise in materials science. A decade ago, Spain's R&D activities were poorly funded and research was carried out without the necessary infrastructure. In 1986, the government established a national R&D strategy which included a dedicated Program for New Materials. In addition, the Regional Communities (Autonomias) have reinforced these nationally planned and funded R&D activities. And as a member of the European Community (EC), Spain has also begun integration into European R&D. After three years, Spanish scientists are already achieving success in the Brite/Euram Program at a level comparable to more scientifically and technologically advanced countries. Figure 1 shows the Spanish government's total R&D budget in materials science from 1985 to 1991, and additions from the EC since 1989. Clearly, financial support for materials science has increased dramatically in the last few years.
Theory and Practice in the Prediction of New Materials
Authors: Rabe K.M.
Published: August 2016

The prediction of new materials is, in theory, a completely straightforward problem. The fundamental equations of quantum mechanics for solids are well-established and can be numerically solved, at least approximately, by powerful first-principles methods developed over the last decade. It remains, then, only to examine the solutions to find those systems that will exhibit the properties desired.

The number of possibilities to be considered and sorted is many orders of magnitude larger than can be managed in a case-by-case first-principles analysis. Therefore, in practice, the approach to theoretical prediction of new materials is to establish easy-to-apply rules for screening large numbers of candidate stoichiometrics (which might or might not be known compounds). These rules are based on physical understanding of the occurrence of the structure or property, inference from known examples, and general principles governing chemical trends in the structure and stability of known compounds. Data from the scientific literature on the occurrence and structure of crystalline compounds are now organized into a number of crystallographic databases, providing a unique opportunity to investigate, from a global perspective, the factors that influence structure and stability. To display, access, and extract general principles from this enormous amount of information, a graphical method such as the “quantum diagram” method is essential, and can be thought of as providing a convenient “roadmap” for navigation around the database. Useful conclusions about individual compounds or small sets of compounds can also be drawn from this type of analysis. These conclusions form the basis for rules for predicting new representatives that direct attention to special regions on the roadmap, as illustrated on the cover of this issue. Systems that satisfy these rules are the most likely to reward experimental investigation.
Prediction of Inorganic Compounds: Experiences and Perspectives
Authors: Kiselyova N.N.
Published: August 2016

There have been many achievements in the last decade in the development of materials science, chemistry, and physics (experimental and theoretical). However, the most difficult problem—calculating the intrinsic properties of multicomponent compounds starting from the knowledge of their constituent components' properties—still remains unsolved. Calculations or predictions based on only the properties of constituent components (or simply, properties) are called a priori calculations or predictions. These difficulties are due to the solution of mathematical problems arising in the quantum mechanical calculations of multi-electronic systems. As a result, scientists make use of many empirical prediction methods that use existing regularities from a variety of property data. Some of the empirical criteria for the formation of compounds with predefined properties use the rules of Hume-Rothery, Laves, Mathias, Goldschmidt, Villars, and Darken-Gurry.
Computational Materials Science of Cement-Based Materials
Authors: Garboczi E.J. , Bentz D.P.
Published: August 2016

Cement-based materials are random composite materials over many length scales. In common with any random material, the two main problems that must be solved to obtain quantitative theoretical understanding of microstructure-property relationships are: (1) what actually is the microstructure, and (2) given enough knowledge of a micro-structure, how can properties be calculated?

In the past few decades, physicists and chemists have studied microstructure/property relationships for atomically disordered materials like semiconductor and metallic glasses, while mechanical engineers have done the same for continuum problems of macroscopic inclusions of one material distributed in a matrix of a second material. With the large memories and fast computational speeds of late 20th-century computers, it is now possible to attack problems that lie between these two extremes, namely random grain problems like those of cement-based and ceramic materials. For these kinds of materials, the important randomness for most problems is at the grain or particle level, not the atomic level, and is complicated by the fact that their microstructure changes markedly on time scales of hours and days, either due to sintering (ceramics), or hydration reactions (cement-based materials). The following sections of this paper describe how microstructures are simulated and properties like electrical conductivity and elastic moduli are computed-mostly for cement-based materials, but with some mention of parallel work on ceramic materials.
From Wood Mechanical Measurements to Composite Materials for Musical Instruments: New Technology for Instrument Makers
Authors: Besnainou Charles
Published: August 2016

Several authors have conducted research to characterize the woods used for musical instruments. The principle of such studies is that acoustical qualities of musical instruments are linked to modal properties of the resonator, especially to the soundboard. Therefore, by knowing the mechanical parameters of materials, it is easy to deduce the frequencies of the eigen modes of a vibrating structure. Equation 1 requires only the geometrical dimension of a plate, the density, and Young's modulus to define a material:

where l is length, b is width, d is thickness, E is Young's modulus, I (= bd3/12) is inertial momentum, ρ is density, n is partial number, and fn, is frequency mode(n).

But, how do we choose the values of each parameter, since woods are variable materials with a large distribution of values-for samples coming from the same tree?
Bass Handbells of Aluminum
Authors: Rossing Thomas D. , Gangadharan Deepak , Mansell Edward R. , Malta Jacob H.
Published: August 2016

Handbells have become very popular musical instruments, especially in schools and churches; about 40,000 hand-bell choirs have been reported in the United States alone. Tuned handbells are generally made of cast bronze, which has been the traditional bell material for many centuries.

Demand for handbells of lower and lower pitches has led to the development of bass bells as low as G0 (fundamental frequency of 24.5 Hz). Unfortunately, these large bass bells radiate inefficiently, especially the bells made of bronze. This is because the speed of bending waves in these bells is considerably lower than the speed of sound in air, a condition known as “being below the coincidence frequency.”

In order to obtain a higher radiation efficiency and thereby enhance the sound of bass bells, the Malmark Company has created a new bell design using aluminum rather than bronze. These bells are larger in diameter, and they have lower coincidence frequencies, both of which lead to more efficient radiation of bass notes. In addition, they are considerably lighter in weight, and thus are much more easily handled by bell ringers.

In this article, the acoustical properties of two G1 handbells, one of aluminum and one of bronze, are compared. The aluminum handbell has a diameter of 48.5 cm, a height of 34 cm, and a wall thickness from 4 to 5 mm. The bronze bell has a diameter of 38.5 cm, a height of 28.5 cm, and a wall thickness from 3 to 4 mm.
Absolute Magnetometry Using Electron Holography: Magnetic Superlattices and Small Particles
Authors: Mankos Marian , Cowley J.M. , Scheinfein M.R.
Published: August 2016

Synthesized magnetic structures are of interest due to their unique and unusual properties, which are governed by their micromagnetic structure. For example, giant-magnetoresistance (GMR) multilayer structures composed of magnetic layers separated by nonmagnetic spacers, and granular GMR films composed of magnetic and nonmagnetic metals exhibit phenomena whose interpretation requires knowledge of both the physical and micromagnetic structure at nanometer-length scales. Techniques for magnetic-microstructure imaging are based on the interaction between a probe and either the magnetic microstructure itself (magnetization) or a physical quantity related to the magnetization distribution (e.g., magnetostriction, magnetic induction). Transmission methods are sensitive to bulk magnetic microstructure averaged along the direction of the incident probe; surface structure is lost. Reflection techniques interact with the near-surface region and no information is obtained about the bulk structure aside from those properties that can be inferred from appropriate boundary conditions.

Electron-optical methods represent the widest class of high-spatial-resolution, magnetic-domain imaging techniques. The most advanced techniques provide the highest contrast, sensitivity, and point resolution (1 nm). Electron holography offers quantitative micromagnetic information at high spatial resolution, a feature missing in most magnetic-imaging techniques. Quantitative information can be extracted from the absolutely calibrated electron wavelength and a knowledge of electron phase shifts in electromagnetic fields. High sensitivity, nanometer spatial resolution, and absolute calibration make electron holography a powerful tool for examining magnetic microstructure. In electron holography, both the amplitude and phase of the transmitted electron waves can be recovered in contrast to conventional electron microscopy where only the intensity is available. The phase, containing information about the local distribution of electromagnetic fields, can be retrieved from an electron hologram.
Mechanical Stress in VLSI Interconnections: Origins, Effects, Measurement, and Modeling
Authors: Flinn Paul A.
Published: August 2016

Problems with mechanical stress in very large-scale integration (VLSI) interconnections appeared quite early in the history of the industry. Failures were observed in the dielectric itself, in the die, and in metal lines. Various process and design changes were made to fix the problems, but the continuing shrinking of dimensions and increased complexity of interconnection structures have resulted in recurrence of old problems, the appearance of new ones, and increasing difficulty in developing fixes. The choices for interconnection materials and processes have become increasingly constrained. The shift from hermetic to plastic packaging reduces the choices for passivation materials. The reduced dimensions for the active devices and the corresponding shortening of diffusion distances limit the “thermal budget”; interconnection processing must be carried out quickly and at relatively low temperatures. The reduced space available for interconnections has resulted in the use of high aspect ratios, multiple layers of metal, and the need for planarization. These all lead to further constraints on materials and processes. An additional complicating factor is the continuing effort to reduce the time from initial design to marketing the product. Since many mechanical-stress-induced problems are wear-out reliability problems, they may require extensive testing for detection. If a problem is not found until late in the product cycle, the economic consequences may be severe. To avoid costly late detection of problems and frantic scrambles for fixes, it is essential to have a clear understanding of the various origins of mechanical stress, the behavior of various materials and interfaces under stress, and the potential failure mechanisms.
Order and Disorder in Semiconductors
Authors: Queisser Hans J.
Published: August 2016

The pervasive impetus of modern semiconductor technology has become an accepted fact. Scientific mastering of materials and processes has increased tremendously within a short time frame. Technological control has been derived from this scientific base. An industry with more than $100 billion worth of silicon devices per annum in 1994 as well as incredibly high growth rates of production and applications is an economic reality in addition to being a matter of international industrial policy. The materials aspect of using perfected single crystals and applying local doping control provides the basis of this unusual success. Earlier usage of materials differed remarkably. Bronze and steel are used for their specific bulk properties. Shaping and connecting pieces is at the heart of iron-age or bronze-age technologies. Integration inside a regular spatial array of a host crystal is the semiconductor principle. The “Royal Road” to modern microelectronics consists of initially procuring a perfected single-crystal host, then locally establishing electrical and optical properties inside the host by specific replacements of host atoms by foreign “dopants.” The somewhat disparaging expression of defect as a generic term for all deviations from the host perfection does not really convey the power of this “doping doctrine” for semiconducting materials. The early pioneers of germanium and silicon however, placed great emphasis on the experimental verification that n-type and p-type doping by elements of the adjacent columns in the periodic table were accompanied by changes in the lattice parameter with atomic substitution of the host atoms as the guiding principle.
Solution Deposition of Ferroelectric Thin Films
Authors: Tuttle B.A. , Schwartz R.W.
Published: August 2016

Solution deposition has been used by almost every electroceramic research-and-development organization throughout the world to evaluate thin films. Ferrite, high-temperature-superconductor, dielectric, and antireflection coatings are among the electroceramics for which solution deposition has had a significant impact. Lithium niobate, lithium tantalate, potassium niobate, lead scandium tantalate, lead magnesium niobate, and bismuth strontium tantalate are among the ferroelectric thin films processed by solution deposition. However, lead zir-conate titanate (PZT) thin films have received the most intensive study and will be emphasized in this article.

Solution deposition facilitates stoichiometric control of complex mixed oxides better than other techniques such as sputter deposition and metalorganic chemical vapor deposition (MOCVD). Solution deposition is a fast, cost-efficient method to survey extensive ranges of film composition. Further it is a process compatible with many semiconductor-fabrication technologies, and it may be the deposition method of choice for applications that do not require conformal depositions and that have device dimensions of 2 μm or greater. Specific applications for which solution deposition is commercially viable include decoupling capacitors, uncooled pyroelectric infrared detectors, piezoelectric micromotors, and chemical microsensors based on surface-acoustic-wave technology. Reviews of some of the more fundamental aspects of solution-deposition processing may be found in the scientific literature.
Process Integration for Nonvolatile Ferroelectric Memory Fabrication
Authors: Jones Robert E. , Desu Seshu B.
Published: August 2016

The remanent-polarization states of ferroelectric capacitors have long been of interest for nonvolatile storage of digital data. A simple memory array can be formed by perpendicular rows and columns of conductors with a ferroelectric capacitor at each crosspoint. In the simplest geometry, these conductors also are the capacitor electrodes on either side of a ferroelectric layer. Each capacitor represents one bit of digital data. If a voltage of V0 is required to write a capacitor, then data can be written to a specific bit by applying V0/2 and –V0/2 to the appropriate row and column. Such ferroelectric memory arrays were constructed as early as the 1950s. However, due to the breath of the ferroelectric transition, they were not successful because during the write of a specific capacitor, the V0/2 voltage signals disturb the polarization in other capacitors. This is in contrast to the successful use of the analogous ferromagnetic crosspoint arrays, which are familiar as the core memories of early computer technology.
Pair Potentials in Atomistic Computer Simulations
Authors: Vitek V.
Published: August 2016

Computer modeling of crystal defects ranges at present from generic empirical investigations to first-principle quantum-mechanical calculations (see, for example, References 1–4). Descriptions of atomic interactions in terms of pair potentials dominated such studies until the early 1980s, and many fundamental features of lattice defects and interfaces were revealed in these calculations. The generic results of these studies withstood the test of time, and calculations employing more sophisticated schemes usually confirmed their validity. An early example goes back to the late 1950s when Vineyard and co-workers pioneered the very first computer simulations in their studies of radiation damage. Empirical pair potentials were used in these investigations in which many fundamental, generic aspects of the effect of irradiation of crystalline materials by energetic particles were discovered.

Such simple treatments of atomic interactions may appear totally inadequate from the point of view of pure physics. However, it must be recognized that the purpose of the majority of atomistic studies of lattice defects has been to elucidate atomic structure and atomic-level properties in materials with given: (a) crystal structure, (b) elastic properties and possibly phonon spectra, (c) values of certain material parameters such as vacancy formation energies and stacking fault energies, and (d) in alloys, alloying and ordering energies, and possibly antiphase boundary energies. This is in contrast with ab initio studies, the objective of which is to determine all these properties from first principles. These goals of atomistic studies are, of course, the same for all semi-empirical approaches discussed in this collection of articles. In general, the validity of the structural features of lattice defects found in calculations using empirical schemes is best guaranteed if they can be related to fitted material properties and are not sensitively dependent on the deails of the fittings and functional forms employed.
Tight-Binding Theory and Computational Materials Synthesis
Authors: Sutton A.P. , Godwin P.D. , Horsfield A.P.
Published: August 2016

At the heart of any atomistic simulation is a description of the atomic interactions. A whole hierarchy of models of atomic interactions has been developed over the last twenty years or so, ranging from ab initio density-functional techniques, to simple empirical potentials such as the embedded-atom method and Finnis-Sinclair potentials in metals, valence force fields in covalently bonded materials, and the somewhat older shell model in ionic systems. Between the ab initio formulations and empirical potentials lies the tight-binding approximation: It involves the solution of equations that take into account the electronic structure of the system, but at a small fraction of the cost of an ab initio simulation, because those equations contain simplifying approximations and parameters that are usually fitted empirically.

Tight binding may be characterized as the simplest formulation of atomic interactions that incorporates the quantum-mechanical nature of bonding. The particular features that it captures are as follows: (1) the strength of a bond being dependent not only on the interatomic separation but also on the angles it forms with respect to other bonds, which arises fundamentally from the spatially directed characters of p and d atomic orbitals, (2) the filling of bonding (and possibly antibonding) states with electrons, which controls the bond strengths, and (3) changes in the energy distribution of bonding and antibonding states as a result of atomic displacements. These features enable one to obtain considerable improvements in accuracy compared to the simple “glue models” of bonding since use is made of the physics and chemistry of bonding.
Biomineralization: Biomimetic Potential at the Inorganic-Organic Interface
Authors: Mann Stephen , Archibald Douglas D. , Didymus Jon M. , Heywood Brigid R. , Meldrum Fiona C. , Wade Vanessa J.
Published: August 2016

The impetus for a biomimetic approach to mineralization stems from the need for increasingly sophisticated materials showing greater efficiency, specialization, and optimization—properties that ultimately depend on the control of molecular and supramolecular structure, and hence on methods of predictive chemical fabrication. Biomineralization is of central importance to the development of new approaches in materials science because, as discussed in the preceding article by Fink, the formation of bioinorganic materials, such as bones, shells, and teeth is highly regulated and responsive to the surrounding environment in a manner not achieved by conventional synthetic routes. Some possible areas of overlap are shown in Figure 1. As in the other areas of biomaterials discussed in this and next month's issue of theMRS Bulletin, there are two potential connections between the natural processes of biomineralization and the synthetic demands of materials science; first, the commercial exploitation of biologically derived, tailored materials, and second, the assimilation and adaptation of biological concepts and mechanisms into “artificial” materials design and synthesis. The former is an extension of biotechnology, by which microbial systems could be utilized to produce mineral powders. Some of the possible processes have been discussed elsewhere. In general, the use of biological sources is only applicable where the high production costs are offset by a marketable specialty product. While this is feasible for organic-based products such as polyhydroxybutyrate (see next month'sMRS Bulletin) it imposes a severe limitation when we transfer the approach to biomineralization.