bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations of Astrolabe Metallurgy Using Synchrotron Radiation
Authors: Stephenson G. Brian , Stephenson Bruce , Haeffner Dean R.
Published: February 2011

The planispheric astrolabe occupies a special place among early scientific instruments because of its mathematical sophistication, its elegant appearance, and its usefulness to astronomers in pre-telescopic times. The operation of the astrolabe is based on the mathematical properties of stereographic projection, concepts that were understood by the time of Ptolemy in the second century a.d., although surviving instruments are from much later periods.
From Opals to Optics: Colloidal Photonic Crystals
Authors: Colvin Vicki L.
Published: February 2011

Over a decade ago, theorists predicted that photonic crystals active at visible and near-infrared wavelengths would possess a variety of exciting optical properties. Only in the last several years, however, have experimentalists begun to build materials that realize this potential in the laboratory. This lag between experiment and theory is primarily due to the to the challenges associated with fabricating these unique materials. As the term “crystal” suggests, these samples must consist of highly perfect ordered arrays of solids. However, unlike conventional crystals, which exhibit order on the angstrom length scale, photonic crystals must have order on the submicrometer length scale. In addition, many of the most valuable properties of photonic crystals are only realized when samples possess a “full” photonic bandgap. For such systems, large dielectric contrasts and particular crystal symmetries create a range of frequencies over which light cannot propagate. Realizing the nanoscopic architectures required to form such systems is a challenge for experimentalists. As a result, fabrication schemes that rely on lithographic techniques or spontaneous assembly have been a focus in the development of the field.
Optical Probes inside Photonic Crystals
Authors: Vos W.L. , Polman A.
Published: February 2011

The spontaneous emission of an atom is not a property of the atom only; it also depends on the local optical surroundings. The simplest demonstration of this effect was provided by the early experiments of Drexhage, who studied the emission rate of luminescent europium ions close to a mirror. It was found that while the spectral distribution of the emission remained constant, the emission rate was dependent on the position of the Eu3+ ions relative to the mirror. This effect is due to interference of the optical modes incident to and reflected at the mirror. Since then, the modified spontaneous emission of atoms in cavities has been studied extensively. More recently, the control of spontaneous emission in solid-state systems has become of great interest because it enables the tailoring of the emission properties of optical materials. It was shown how the spontaneous-emission rate of optical probe ions or dyes inside dielectric films is modified by the presence of a dielectric interface, in a dielectric multilayer, or a microcavity. The dependence of the decay rate on the optical surroundings in these one-dimensional systems can be described in terms of Fermi's “golden rule,” which states that the decay rate is proportional to the local optical density of states (DOS). The spatial variation in the DOS is due to the interference of optical modes reflected and refracted at the dielectric interface(s).
Evidence for the Metallurgical Origins of Glass at Two Ancient Egyptian Glass Factories
Authors: Mass Jennifer L. , Wypyski Mark T. , Stone Richard E.
Published: February 2011

Studying the raw materials used by ancient glassmakers provides information about ancient glassmaking practices, the relationship between glassmaking and other craft technologies (silicate-based or non-silicate-based), and the trading patterns of specific cultures. Colored opaque glasses are of particular interest because they were among the first mass-produced and mass-distributed glasses.
Environmental Actinide Science
Authors: Silva Robert J. , Nitsche Heino
Published: February 2011

Considerable progress has been made in the study of environmental plutonium science in the last 30-plus years, driven to a large extent by concerns about the release and migration of large amounts of plutonium into the accessible geosphere. Plutonium has been introduced into the environment through several pathways. Environmental contamination has been caused by nuclear-weapons production and testing, nuclear-reactor accidents, and accidents during the transport of nuclear weapons. Above-ground testing of more than 420 nuclear weapons has produced large amounts of radionuclides through fission and neutron activation products. More than three metric tons of plutonium have been distributed on the earth's surface by global fallout. For example, the MAYAK plutonium production complex in the former Soviet Union is located in the southern Urals, about 70 km north of Chelyabinsk and 15 km east of Kyshtym. Between 1949 and 1951, about 76 million m3 of liquid radioactive waste with a total activity of 100 PBq (2.7 MCi) were discharged into the Techa River.
Science and Technology at the Nanometer Scale Using Vacuum-Deposited Organic Thin Films
Authors: Forrest Stephen
Published: February 2011

Organic thin films have been studied for their properties as active optoelectronic materials for at least 50 years. Yet, until recently, they have failed to make a significant impact in the commercial world. However, display products based on organic light emission are now available commercially, indicating that a major change in the acceptance of organic optoelectronics is in the offing. I would like to discuss some of the reasons for these developments from an engineering perspective.
Advances in Bi-Based High-Tc Superconducting Tapes and Wires
Authors: Kitaguchi Hitoshi , Kumakura Hiroaki
Published: February 2011

Since the discovery of high-Tc superconductors (HTSs), especially the Bi-based oxide superconductors (Bi-HTSs) in 1989, much effort has been concentrated on the fabrication of Bi-HTS wires and tapes. Bi-HTSs are interesting materials from the viewpoint of practical applications. One of the interesting applications of Bi-HTSs is the cryogen-free conduction-cooled magnet. Besides having a high transition tem- perature (Tc), Bi-HTSs have high upper critical fields (Bc2) or high irreversibility fields (Birr) at temperatures below ∼30 K. Because ∼30 K can be efficiently main- tained by a cryocooler, a Bi-HTS magnet cooled with a cryocooler has great potential in many technological applications. Another promising application of Bi-HTSs is the high-field magnet. When the temperature is reduced to ∼5 K, Bi-HTSs show a much higher Bc2 or Birr than do conventional metallic superconductors (low-temperature superconductors, LTSs) such as Nb3Sn. This indicates that Bi-HTSs also have great potential for use in a high- field superconducting magnet if the magnet is operated at low temperature.
Multiscale-Multiphysics Modeling of Radiation-Damaged Materials: Embrittlement of Pressure-Vessel Steels
Authors: Odette G.R. , Wirth B.D. , Bacon D.J. , Ghoniem N.M.
Published: February 2011

Radiation damage, and its attendant effect on a wide spectrum of materials properties, is a central issue in many advanced technologies ranging from ion-beam processing to the development of fusion power. Indeed, the various challenges presented by irradiation effects are too numerous to discuss in this brief article.
Multiscale Problems in Polymer Science: Simulation Approaches
Authors: Kremer K. , Müller-Plathe F.
Published: February 2011

Polymer materials range from industrial commodities, such as plastic bags, to high-tech polymers used for optical applications, and all the way to biological systems, where the most prominent example is DNA. They can be crystalline, amorphous (glasses, melts, gels, rubber), or in solution. Polymers in the glassy state are standard materials for many applications (yogurt cups, compact discs, housings for technical equipment, etc.).
Tribology of MEMS
Authors: de Boer M.P. , Mayer T.M.
Published: February 2011

Because of large surface-to-volume ratios and low restoring forces, unwanted adhesion and friction can dominate the performance of microelectromechanical systems (MEMS) devices. To guarantee the function and reliability of MEMS devices, tribologists must understand the origins of adhesion, friction, and wear over a broad range of length scales from the macroscopic to the molecular. In this article, we present an overview of challenges, successes, and initial steps toward a fundamental understanding.
LIGA Technologies and Applications
Authors: Hruby Jill
Published: February 2011

LIGA, an acronym for the German words for lithography, electroplating, and molding, is a technique used to produce micro-electromechanical systems (MEMS) made from metals, ceramics, or plastics. The LIGA process utilizes x-ray synchrotron radiation as a lithographic light source. Highly collimated, high-energy x-rays from the synchrotron impinge on a patterned mask in proximity to an x-ray-sensitive photoresist, typically poly(methyl methacrylate) (PMMA).
Design and Properties of Hybrid Organic–Inorganic Nanocomposites for Photonics
Authors: Sanchez Clément , Lebeau Bénédicte
Published: February 2011

The possibility of combining the properties of organic and inorganic components in a unique composite material is an old challenge that dates to the beginning of the industrial era. Some of the earliest and most well-known organic–inorganic representatives are derived from the paint and polymer industries, where inorganic pigments or fillers are dispersed in organic components such as solvents, surfactants, and polymers to yield or improve optical and mechanical properties.
Commercial Applications of Sol-Gel-Derived Hybrid Materials
Authors: Arkles Barry
Published: February 2011

Sol-gel processing readily yields both inorganic and hybrid organic–inorganic materials. Commercial applications of solgel technology preceded the formal recognition of this technology as an important field of study. Likewise, successful commercial hybrid organic–inorganic polymers have been part of manufacturing technology since the 1950s.
Combinatorial Methods for Investigations in Polymer Materials Science
Authors: Carson Meredith J. , Karim Alamgir , Amis Eric J.
Published: February 2011

We review recent advances in the development of combinatorial methods for polymer characterization. Applied to materials research, combinatorial methodologies allow efficient testing of structure–property hypotheses (fundamental characterization) as well as accelerated development of new materials (materials discovery). Recent advances in library preparation and high-throughput screening have extended combinatorial methods to a wide variety of phenomena encountered in polymer processing. We first present techniques for preparing continuous-gradient polymer “libraries” with controlled variations in temperature, composition, thickness, and substrate surface energy. These libraries are then used to characterize fundamental properties such as polymer-blend phase behavior, thin-film dewetting, block-copolymer order–disorder transitions, and cell interactions with surfaces of biocompatible polymers.
Optical-Fiber Sensors: An Overview
Authors: Webb D. J.
Published: February 2011

This article provides an overview of the field of optical-fiber sensing, including a brief introduction to the properties of optical fibers that make them suitable for material characterization and monitoring. Some of the recent developments in the field are described, with an emphasis on Bragg grating sensors, multiplexed systems, and chemical sensing, as well as the new field of microstructured fiber.
Optical-Fiber Medical Sensors
Authors: Baldini Francesco , Mignani Anna Grazia
Published: February 2011

Optical-fiber sensors can be placed on the skin or inside the human body for the direct measurement of biomedical parameters. This article presents an overview of the most recent applications of optical-fiber sensors for biomedical purposes and those currently under development.
Optical-Fiber Sensors for the Detection of Acoustic Emission
Authors: Spillman William B. , Claus Richard O.
Published: February 2011

Acoustic emission (AE) is used as a means to anticipate the mechanical failure of critical materials and structures by detecting the release of energy caused by material rearrangement at the microlevel. Optical-fiber sensors have potential advantages over conventional tuned piezoelectric transducers and signal-processing methods for the detection of such types of ultrasonic acoustic wave events. A number of fiber Bragg grating techniques are presented, which in particular offer the potential to provide the high-speed signal processing and ability to multiplex numbers of AE sensors necessary to detect, quantify, and locate AE sources and thereby determine material properties and damage.
Applications of Fiber Bragg Grating Sensors in the Composite Industry
Authors: Ferdinand Pierre , Magne Sylvain , Dewynter-Marty Véronique , Rougeault Stéphane , Maurin Laurent
Published: February 2011

Optical-fiber sensors based on fiber Bragg gratings (FBGs) provide accurate, nonintrusive, and reliable remote measurements of temperature, strain, and pressure, and they are immune to electromagnetic interference. FBGs are extensively used in telecommunications, and their manufacture is now cost-effective. As sensors, FBGs find many industrial applications in composite structures used in the civil engineering, aeronautics, train transportation, space, and naval sectors. Tiny FBG sensors embedded in a composite material can provide in situ information about polymer curing (strain, temperature, refractive index) in an elegant and nonintrusive way. Great improvements in composite manufacturing processes such as resin transfer molding (RTM) and resin film infusion (RFI) have been obtained through the use of these sensors. They can also be used in monitoring the “health” of a composite structure and in impact detection to evaluate, for example, the airworthiness of aircraft. Finally, FBGs may be used in instrumentation as composite extensometers or strain rosettes, primarily in civil engineering applications.
Mechanical Properties in Small Dimensions
Authors: Vinci Richard P. , Baker Shefford P.
Published: February 2011

This brief article describes the content of the January 2002 issue of MRS Bulletin focusing on Mechanical Properties in Small Dimensions. Articles discuss the current understanding ofstressevolution during thin-film growth, elastic and anelastic behavior, dislocation-mediated plasticity, creep deformation, and fracture. Emphasis is placed on explaining the mechanisms that underlie thewell-known fact that length scale can play a significant role in mechanical behavior.
Self-Amplifying Semiconducting Polymers for Chemical Sensors
Authors: Swager Timothy M. , Wosnick Jordan H.
Published: February 2011

The ability of excited states (excitons) to migrate rapidly and efficiently through conjugated polymers makes these materials ideal for use in sensors based on fluorescence quenching or amplification of fluorescence signals. The structural features we are able to introduce into these polymers have allowed us both to design highly sensitive fluorescent sensors for specific analytes, such as the explosive trinitrotoluene (TNT), and to create assemblies that control energy transfer along a predetermined path. The principles involved have broad utility in the design of sensory materials as well as of electronic devices and display components based on electronic polymers.
Physical Origins of Intrinsic Stresses in Volmer–Weber Thin Films
Authors: Floro Jerrold A. , Chason Eric , Cammarata Robert C. , Srolovitz David J.
Published: February 2011

As-deposited thin films grown by vapor deposition often exhibit large intrinsic stresses that can lead to film failure. While this is an “old” materials problem, our understanding has only recently begun to evolve in a more sophisticated fashion. Sensitive real-time measurements of stress evolution during thin-film deposition reveal a generic compressive–tensile–compressive behavior that correlates with island nucleation and growth, island coalescence, and postcoalescence film growth. In this article, we review the fundamental mechanisms that can generate stresses during the growth of Volmer–Weber thin films. Compressive stresses in both discontinuous and continuous films are generated by surface-stress effects. Tensile stresses are created during island coalescence and grain growth. Compressive stresses can also result from the flux-driven incorporation of excess atoms within grain boundaries. While significant progress has been made in this field recently, further modeling and experimentation are needed to quantitatively sort out the importance of the different mechanisms to the overall behavior.
Elastic and Anelastic Behavior of Materials in Small Dimensions
Authors: Baker Shefford P. , Vinci Richard P. , Arias Tomás
Published: February 2011

Under certain circumstances, decreasing the dimensions of a material may lead to elastic or anelastic properties that diverge from bulk behavior. A distinction is made between elastic deformation, for which bond rearrangements are not required, and anelastic behavior, which involves reversible deformation due to defect motion. Elastic deformation (due to bond stretching) remains structure-insensitive down to near-atomic length scales, and only small deviations are expected (of the order of 10%). More significant deviations can be observed in special cases, which are described in the article. However, elastic moduli that are much lower than expected are sometimes seen, even in careful experiments. It now appears that this behavior may be explainable by time-dependent anelastic relaxation mechanisms. In contrast to purely elastic behavior, anelastic behavior is very sensitive to microstructure and is found to be common and often significant when things become small.
Quantum-Dot Vertical-Cavity Surface-Emitting Lasers
Authors: Bimberg D. , Ledentsov N.N. , Lott J.A.
Published: February 2011

GaAs-based continuous-wave quantum-dot vertical-cavity surface-emitting lasers (VCSELs) operating at 1.3 μm at 20°C with output power of 1.2 mW have been realized. Threshold currents approach 1–1.5 mA for 8-μm oxide apertures. Operating voltages are ∼2 V. Long operation lifetimes in excess of 5000 h at 50°C without degradation have been achieved. This article describes these breakthroughs, which are based on our development of complex self-organized growth technologies for defect-free stacked quantum dots.
Nanoscale Materials for Lithium-Ion Batteries
Authors: Sides Charles R. , Li Naichao , Patrissi Charles J. , Scrosati Bruno , Martin Charles R.
Published: February 2011

Template synthesis is a versatile nanomaterial fabrication method used to make monodisperse nanoparticles of a variety of materials including metals, semiconductors, carbons, and polymers. We have used the template method to prepare nanostructured lithium-ion battery electrodes in which nanofibers or nanotubes of the electrode material protrude from an underlying current-collector surface like the bristles of a brush. Nanostructured electrodes of this type composed of carbon, LiMn2O4, V2O5, tin, TiO2, and TiS2have been prepared. In all cases, the nanostructured electrode showed dramatically improved rate capabilities relative to thin-film control electrodes composed of the same material. The rate capabilities are improved because the distance that Li+must diffuse in the solid state (the current- and power-limiting step in Li-ion battery electrodes) is significantly smaller in the nanostructured electrode. For example, in a nanofiber-based electrode, the distance that Li+must diffuse is restricted to the radius of the fiber, which may be as small as 50 nm. Recent developments in template-prepared nanostructured electrodes are reviewed.
Metallic Hydrides I: Hydrogen Storage and Other Gas-Phase Applications
Authors: Bowman Robert C. , Fultz Brent
Published: February 2011

A brief survey is given of the various classes of metal alloys and compounds that are suitable for hydrogen-storage and energy-conversion applications. Comparisons are made of relevant properties including hydrogen absorption and desorption pressures, total and reversible hydrogen-storage capacity, reaction-rate kinetics, initial activation requirements, susceptibility to contamination, and durability during long-term thermal cycling. Selected applications are hydrogen storage as a fuel, gas separation and purification, thermal switches, and sorption cryocoolers.
Nanotopography Issues in Shallow Trench Isolation CMP
Authors: Boning Duane , Lee Brian
Published: February 2011

As advancing technologies increase the demand for planarity in integrated circuits, nanotopography has emerged as an important concern in shallow trench isolation (STI) on wafers polished by means of chemical–mechanical planarization (CMP). Previous work has shown that nanotopography—small surface-height variations of 10–100 nm in amplitude extending across millimeter-scale lateral distances on virgin wafers—can result in CMP-induced localized thinning of surface films such as the oxides or nitrides used in STI. A contact-wear CMP model can be employed to produce maps of regions on a given starting wafer that are prone to particular STI failures, such as the lack of complete clearing of the oxide in low spots and excessive erosion of nitride layers in high spots on the wafer. Stiffer CMP pads result in increased nitride thinning. A chip-scale pattern-dependent CMP simulation shows that substantial additional dishing and erosion occur because of the overpolishing time required due to nanotopography. Projections indicate that nanotopography height specifications will likely need to decrease in order to scale with smaller feature sizes in future IC technologies.
Development of the Precursor and Subsequent R-Phase Transformation
Authors: Shindo Daisuke , Murakami Yasukazu , Ohba Takuya
Published: February 2011

The following is a Web Extra expanding upon the article “Understanding Precursor Phenomena for the R-Phase Transformation in Ti-Ni-Based Alloys” by Daisuke Shindo, Yasukazu Murakami, and Takuya Ohba, published in MRS Bulletin27 (2002) pp. 121–127. It provides a closer examination of the domain structure evolution over a temperature range extended beyond that shown in Figure 5 in the article, along with intensity profiles of the electron diffraction.
Passive-Matrix Polymer Light-Emitting Displays
Authors: Haskal Eliav I. , Büchel Michael , Duineveld Paul C. , Sempel Aad , Weijer Peter van de
Published: February 2011

Organic light-emitting devices (OLEDs) have attracted considerable interest in the last five years and are now viewed as an important competitor with liquid crystals for a wide variety of display applications. Current research focuses on the use of small-molecule and polymer materials to make organic electroluminescent displays with both passive-and active-matrix technologies. This article will discuss work on the device architecture for a polymer passive-matrix display application, the stability of polymer light-emitting displays, and the use of ink-jet printing for high-resolution patterning of red, green, and blue light-emitting polymers.
Reflective Liquid-Crystal Displays
Authors: Uchida Tatsuo , Ishinabe Takahiro
Published: February 2011

Reflective full-color liquid-crystal displays (LCDs) are attracting a great deal of interest as portable information systems because of their extremely low power consumption and light weight; also, the color does not wash out in outdoor use. In this article, reflective LCDs are classified into three types. Among them, the diffusing-reflector type and the front-diffusing film type are suitable for high-quality active-matrix displays. Diffusing-reflector LCDs have the advantage of uniform reflectance at the desired viewing angle due to the design of the surface microstructure of the reflector. Front-diffusing film LCDs using metallic mirrors and an optimally designed light-controlling film enable high contrast in a wide viewing-angle range and uniform reflectance with no blurring. Thus, both types have a high potential for achieving excellent color quality comparable to printed paper. In the near future, these reflective LCDs will likely be applied not only to portable systems, but also to high-performance wireless monitor displays and various other information systems.
Science and Technology of Shape-Memory Alloys: New Developments
Authors: Otsuka Kazuhiro , Kakeshita Tomoyuki
Published: February 2011

The martensitic (also called displacive or diffusionless) transformation is a classical cooperative phenomenon in solids similar to ferromagnetism. Although the displacement of each atom is not large, the transformation results in a macroscopic change in shape, since all of the atoms move in the same direction in a domain or variant. As a result, unique properties arise, such as the shape-memory effect and superelasticity, whose characteristics are quite distinct from those of normal metals and alloys. Because of these unique properties, shape-memory alloys (SMAs) have been used as new functional materials for applications such as couplings, sensors, actuators, and antennas for cellular phones. In this issue of MRS Bulletin, we present an overview of recent progress in this field. In this introductory article, we discuss fundamental notions, such as the mechanism of the shape-memory effect, the martensitic transformation, and superelasticity, along with examples of applications and other important recent topics not treated in the following articles. It will be shown that progress in the science and technology of shape-memory alloys has been achieved by the side-by-side development of fundamentals and applications.
Sputter-Deposited Shape-Memory Alloy Thin Films: Properties and Applications
Authors: Ishida Akira , Martynov Valery
Published: February 2011

Shape-memory alloy (SMA) thin films formed by sputter deposition have attracted considerable attention in the last decade. Current intensive research demonstrates that unique fine microstructures are responsible for the superior shape-memory characteristics observed in thin films as compared with bulk materials. Simultaneously, much effort has been undertaken to develop and fabricate micro devices actuated by SMA thin films. This article reviews the research to date on shape-memory behavior and the mechanical properties of SMA thin films in connection with their peculiar microstructures. Promising applications such as microvalves are demonstrated, along with a focused discussion on process-related problems. All of the results indicate that thin-film shape-memory actuators are ready to contribute to the development of microelectromechanical systems.
The Interaction of Point Defects with the Martensitic Transformation: A Prototype of Exotic Multiscale Phenomena
Authors: Ren Xiaobing , Otsuka Kazuhiro
Published: February 2011

The martensitic transformation has so far been studied without considering its interaction with point defects. In this article, we shall show that such interaction, which stems from a universal symmetry property of point defects, can create a rich spectrum of exotic multiscale phenomena in martensitic materials. These phenomena include unique short-range diffusion at the atomic or nano level, remarkable domain-pattern memory at the mesoscopic level, and peculiar rubber-like behavior and aging-induced two-way shape memory at the macroscopic level. Exotic multiscale phenomena may also be found in a wide range of transforming materials, such as ferroelastic, ferroelectric, and ferromagnetic materials. These novel effects may provide new opportunities for these important materials.
On the Electrical Characterization of High-ĸ Dielectrics
Authors: Degraeve R. , Cartier E. , Kauerauf T. , Carter R. , Pantisano L. , Kerber A. , Groeseneken G.
Published: February 2011

The continual scaling of complementary metal oxide semiconductor (CMOS) technologies has pushed the Si-SiO2 system to its very limits and has led to the consideration of a number of alternative high-ĸ gate dielectric materials. In the end, it will be the electrical properties of the new Si/high-ĸ system that will determine its usefulness in future CMOS generations. For this reason, the study of the electrical properties of high-ĸ gate insulators is crucial. We present an overview of some of the electrical characterization techniques and reliability tests used to evaluate possible high-ĸ gate materials. Most of these techniques are well known from the characterization of SiO2 layers, but there are some additional complications, such as the presence of several different layers within one gate stack or the use of different gate electrode materials. These make the interpretation and comparison of experimental results more troublesome.
Combinatorial Materials Science: What's New Since Edison?
Authors: Amis Eric J. , Xiang Xiao-Dong , Zhao Ji-Cheng
Published: February 2011

Combinatorial methods are high-efficiency methods to create large composition “libraries” of materials, for example, continuous composition variations, and test those compositions systematically in parallel for specific properties of interest, in contrast to the time-consuming one-composition-at-a-time approach. These methods have captured the attention of the materials industry with the promise of providing new discoveries “faster, better, and cheaper.” However, in the academic community, combinatorial methods often meet with less enthusiasm, perhaps due to the perception of combinatorial methodology as an Edisonian approach to science. The facts are quite to the contrary. In addition to impressive successes arising from the application of combinatorial methods to materials discovery, results coming out of systematic high-throughput investigations of complex materials phenomena (which would be too time-consuming or expensive to undertake) provide data leading to improvement in theories and models of materials chemistry and physics. Indeed, combinatorial methods provide a new paradigm for advancing a central scientific goal—the fundamental understanding of structure–property relationships of materials behavior.
Organic Materials for Photonic Devices
Authors: Fuhrmann Thomas , Salbeck Josef
Published: February 2011

Current issues in the development of organic materials for photonic applications are reviewed. Organic light-emitting diodes, which are a main focus of industrial research at the moment, are given special emphasis. Other applications in optical communications technology, including organic solid-state lasers, optical switching devices, and data storage, are also covered.
Designing Soft Reactive Adhesives by Controlling Polymer Chemistry
Authors: Aymonier Agnès , Papon Eric
Published: February 2011

Soft reactive adhesives (SRAs) are polymer-based materials (e.g., polyurethanes, polysiloxanes, polydienes) designed to be further vulcanized or slightly cross-linked through external activation (heat, moisture, oxygen, UV–visible irradiation, etc.), either at the time of their application or within a subsequent predefined period. They are used mainly as mastics, or sealing compounds, in a wide range of industrial and commercial fields such as construction, footwear, and the automotive industry. Generally deposited as thick films, SRAs behave as structural adhesives; their low elastic moduli accommodate large strains between the bonded parts without incurring permanent damage. Other outstanding attributes of SRAs are their resistance to solvents, their ability to withstand aggressive environments, and their ease of use. This article discusses examples of SRAs and, more specifically, shows how the cross-linking chemistry, mainly through step-growth polymerization, provides their primary advantages.
Hot-Melt Adhesives
Authors: Paul C. W.
Published: February 2011

Hot-melt adhesives facilitate fast production processes because the adhesives set simply by cooling. Formulations contain polymers to provide strength and hot tack (resistance to separation while adhesive is hot), and tackifiers and/or oils to dilute the polymer entanglement network, adjust the glass-transition temperature, lower the viscosity, and improve wet-out (molecular contact of the adhesive with the substrate over the entire bonding area). Some adhesives also contain waxes to speed setting, lower viscosity, and improve heat resistance. Obtaining adequate strength and heat resistance from nonreactive hot melts requires that some component of the hot melt separate out into a dispersed but interconnected hard-phase network upon cooling. The hard phases are commonly either glassy styrene domains (for adhesives based on styrenic block copolymers) or organic crystallites (for adhesives based on waxes, olefinic copolymers, or ethylene copolymers). This article will describe first the material properties relevant to the processing and performance of hot-melt adhesives, then the chemistry and function of the specific raw materials used in hot melts, and will conclude with illustrative application examples and corresponding formulations.
Critical Aspects of High-Performance Microprocessor Packaging
Authors: Atluri Vasudeva P. , Mahajan Ravi V. , Patel Priyavadan R. , Mallik Debendra , Tang John , Wakharkar Vijay S. , Chrysler Gregory M. , Chiu Chia-Pin , Choksi Gaurang N. , Viswanath Ram S.
Published: February 2011

Historically, the primary function of microprocessor packaging has been to facilitate electrical connectivity of the complex and intricate silicon microprocessor chips to the printed circuit board while providing protection to the chips from the external environment. However, as microprocessor performance continues to follow Moore's law, the package has evolved from a simple protective enclosure to a key enabler of performance. The art and science of semiconductor packaging has advanced radically over the past few decades as faster and more powerful microprocessors with tens of millions of transistors continue to be available, which require more signal and power input/output connections as well as greater power-dissipation capabilities. Key drivers for the development of packaging technologies include power delivery, thermal management, and interconnect scaling, in which the space transformation from fine-featured silicon interconnects to the relatively coarse features seen on motherboards has to be enabled by the package. These drivers, under constant market-driven cost pressure, have led to increased demands on new materials and new package architectures to enable silicon performance. Significant advances have already been made in the areas of heat dissipation, power delivery, high-speed signaling, and high-density interconnects. It is expected that the future evolution of microprocessors will be increasingly challenging in these areas. This article focuses on providing a broad perspective view of the evolution of microprocessor packaging and discusses future challenges.
Materials for 3D Packaging of Electronic and Optoelectronic Systems
Authors: Ozguz Volkan H. , Yamaguchi James
Published: February 2011

Advanced three-dimensional (3D) packaging techniques for electronic components are promising for the realization of “systems-in-packages.” Three-dimensional packages require the use of a variety of materials within a small physical size range. Materials selection is therefore critical from electrical, optical, mechanical, structural, thermal, and manufacturability viewpoints. The materials combination depends also on the intended application for the 3D packaged modules. This article reviews 3D packaging approaches, materials classes, and examples. Three-dimensional packaged systems using judiciously selected materials offer performance advantages that cannot be provided by planar implementation.
Packaging Options for MEMS Devices
Authors: Jung Erik
Published: February 2011

Microelectromechanical systems (MEMS) devices can be delicate structures sensitive to damage from handling or environmental influences. Their functionality may furthermore depend on sealing out the environment or being in direct contact with it. Stress, thermal load, and contaminants may change their characteristics. Here, packaging technology is challenged to extend from microelectronics toward MEMS and optoelectronic MEMS (MOEMS). Today's approaches rely on modified single-chip packages derived from the microelectronics industry, wafer-level capping to enable the device to be packaged like an integrated circuit, or highly specialized packages designed to complement the function of the MEMS device itself. Selecting the proper packaging method may tip the scale toward a product success or a product failure. Choosing the right technology, therefore, is a crucial part of the product design.
Smart Textiles: Wearable Electronic Systems
Authors: Park Sungmee , Jayaraman Sundaresan
Published: February 2011

Protection and aesthetics are the two common dimensions or attributes typically associated with textiles as clothing. However, with the rapidly changing needs of today's consumers, a third dimension is emerging—that of “intelligence”—that is being integrated into fabrics to produce interactive textiles, or i-textiles. This new class of wearable electronic systems is being designed to meet new and innovative applications in the military, public safety, healthcare, space exploration, sports, and consumer fitness fields. In this article, the concept of i-textiles is presented, along with the building blocks for its realization. This is followed by an overview of the design and development of the Smart Shirt, an “intelligent” garment that provides an extremely versatile framework for the incorporation of sensing, monitoring, and information-processing devices. The key applications of the Smart Shirt technology and their impact in transforming healthcare are discussed. Finally, the need to advance this paradigm and identify opportunities to transform passive textiles into the new generation of interactive, or “smart,” textiles is discussed.
Concepts for Energy-Interactive Textiles
Authors: Kim Yong K. , Lewis Armand F.
Published: February 2011

This review examines textile fibers and fabrics in the context of their interaction with various forms of energy, such as electromagnetic (photolytic), electrical, magnetic, thermal, chemical, and mechanical. This interaction can involve conversion, storage, or management of energy. Examples are described suggesting some new material configurations that could be incorporated into textiles to create special energy-interactive textile (EITX) structures. Areas discussed are the management of electron flow (electrical resistivity) and the absorption of mechanical energy in textile fibers and fabrics. Surface resistance studies on carbon nanotubes and conductive carbon-black-filled films of poly(methyl methacrylate) (PMMA) and paraffin wax show that the electrical conductivity of these materials depends upon the matrix material type and the amount of charge-carrying particles in the matrix. PMMA films filled with carbon nanotubes are found to be more electrically conductive than matrices filled with conductive carbon black. Mechanical-energy interactions of flocked textile surfaces show that in compression, they exhibit unique, gradual load-deflection behavior. This effect should be useful in applications requiring impact-energy absorption. Finally, the functional steps in an integrated energy-interactive textile system are discussed.
Ultrahigh-Temperature Materials for Jet Engines
Authors: Zhao J.-C. , Westbrook J. H.
Published: February 2011

This introductory article provides the background for the September 2003 issue ofMRS Bulletinon Ultrahigh-Temperature Materials for Jet Engines. It covers the need for these materials, the history of their development, and current challenges driving continued research and development. The individual articles that follow review achievements in four different material classes (threein situcomposites—based on molybdenum silicide, niobium silicide, and silicon carbide, respectively—and high-melting-point platinum-group-metal alloys), as well as advances in coating systems developed both for oxidation protection and as thermal barriers. The articles serve as a benchmark to illustrate the progress made to date and the challenges ahead for ultrahigh-temperature jet-engine materials.
Chip-to-Module Interconnections Using “Sea of Leads” Technology
Authors: Bakir Muhannad S. , Reed Hollie A. , Mulé Anthony V. , Jayachandran Joseph Paul , Kohl Paul A. , Martin Kevin P. , Gaylord Thomas K. , Meindl James D.
Published: February 2011

The drive toward higher density and higher performance in integrated circuits creates a need to keep interconnects short and eliminate layers of packaging. In this article, we propose a novel, ultrahigh-density (exceeding 104leads per cm2), compliant, wafer-level, input/output interconnection technology called “sea of leads” as a key enabling technology for future high-performance microsystems. The mechanical compliance is addressed through slippery leads (leads released from the surface) and embedded air gaps. The ability to fabricate embedded air gaps has enabled the integration of optical interconnects with high index-of-refraction mismatches between the core and cladding.
Development of Platinum-Group-Metal Superalloys for High-Temperature Use
Authors: Cornish L. A. , Fischer B. , Völkl R.
Published: February 2011

Superalloys based on platinum-group metals are being developed for high-temperature applications. These alloys have two-phase structures comprising either ordered precipitates in a matrix analogous to the nickel-based superalloys or a fine dispersion of oxide particles in a matrix analogous to oxide-dispersion-strengthened nickel-based alloys. Currently, alloys based on iridium, rhodium, and platinum have been obtained. This article reviews the rationale of developments and the progress made in this area. Oxidation and compression tests as well as characterization with scanning electron microscopy and transmission electron microscopy were undertaken. These tests showed encouraging results, and further work is being done on new alloying additions and tensile testing.
Emerging Materials Challenges in Microelectronics Packaging
Authors: Frear D. R. , Thomas S.
Published: February 2011

Introduction

The trend for microelectronic devices has historically been, and will continue to be, toward a smaller feature size, faster speeds, more complexity, higher power, and lower cost. The driving force behind these advances has traditionally been microprocessors. With the tremendous growth of wireless telecommunications, rf applications are beginning to drive many areas of microelectronics that traditionally were led by developments in microprocessors. An increasingly dominant factor in rf microelectronics is electronic packaging, and the materials needed to create the package, because the package materials strongly affect the performance of the electronics. Many challenges remain for the packaging of microprocessors as well. These challenges include increased speed, the number of input/output interconnects, decreased pitch, and decreased cost. This article highlights the key issues facing the packaging of high-performance digital and rf electronics.
New Possibilities for Ferromagnetic Semiconductors
Authors: Chambers Scott A. , Farrow Robin F.C.
Published: February 2011

New candidate ferromagnetic semiconductors have recently been grown by doping semiconducting transition-metal oxides with magnetic impurities. Some of these exhibit ferromagnetism at and above room temperature. The critical question is why? In many cases, complex solid-state chemistry is involved in the synthesis and drives the resulting properties. The observation of room-temperature ferromagnetism in these materials must be accompanied by a careful identification of the phases and structures present in order to accurately identify the origin of the magnetism.
Combinatorial Investigation of Spintronic Materials
Authors: Matsumoto Y. , Koinuma H. , Hasegawa T. , Takeuchi I. , Tsui F. , Yoo Young K.
Published: February 2011

High-throughput synthesis and characterization techniques have been effective in discovering new materials and performing rapid mapping of phase diagrams. The application of the combinatorial strategy to explore doped transition-metal oxides has led to the discovery of a transparent room-temperature ferromagnetic oxide in Co-doped anatase TiO2. The discovery has triggered a wave of studies into other metal oxide systems in pursuit of diluted magnetic semiconductors. In this article, we describe recent combinatorial studies of magnetic transition-metal oxides, germanium-based magnetic semiconductors, and Heusler alloys.
Drop-on-Demand Printing of Protein Biochip Arrays
Authors: Zaugg Frank G. , Wagner Peter
Published: February 2011

Protein biochips have recently gained a lot of attention as bioanalytical tools in the life sciences. The creation of such biochips has been made possible by the integration of scientific approaches and methodologies in microfabrication, organic interface chemistry, protein engineering, detection physics, and—last but not least—advances in microarrays and microfluidic dispensing technologies. This article reviews some of the current drop-on-demand technologies developed for printing biomolecular arrays, with an emphasis on proteins and the technical challenges associated with them.
Applications of Neutron Reflectivity Measurements to Nanoscience: Thin Films and Interfaces
Authors: Ankner John F. , Zabel Hartmut
Published: February 2011

Neutron reflectivity has matured in recent years from an exotic method used only by a few experts to an essential tool for the investigation of thin films and interfaces on the nanoscale. In contrast to x-ray reflectivity, which provides electron density profiles, neutron reflectivity reveals the nuclear density profile. This is an essential difference when exploring hydrogenous materials such as polymers, Langmuir–Blodgett films, and membranes. Furthermore, neutrons carry a magnetic moment that interacts with the magnetic induction of the film, revealing, in addition to the nuclear density profile, the magnetic density profile in layers and superlattices. Recent developments in the analysis of off-specular neutron reflectivity data enable the characterization of chemical and magnetic correlations within the film plane on nanometer to micron length scales. A new generation of pulsed neutron sources, featuring flux enhancements of factors of 10–100 over existing sources, will make these types of measurements even more exciting, while kinetic studies, pump-probe, and small-sample experiments will become feasible, opening new windows onto nanoscale materials science.
Single-Event Upsets in Microelectronics
Authors: Tang Henry H.K. , Olsson Nils
Published: February 2011

This article introduces the February 2003 issue of MRS Bulletin on “Single-Event Upsets (SEUs) in Microelectronics.” These radiation effects in devices and circuits have been recognized in recent years as a key reliability concern for many current and future silicon-based technologies. This introduction sets the scope for critical discussions on this subject. The articles in the issue reflect the interdisciplinary nature of SEU research. The contributing authors include experts from several specializations: technology reliability, materials science, device physics, circuit designs, and theoretical and experimental nuclear physics. We review the current understanding of SEU problems from the perspectives of radiation physics, circuit design issues, and global technology developments. The discussions cover the key areas of modeling, circuit analyses, accelerator tests and experiments, basic nuclear data, and environmental neutron measurements.