bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomistic Studies of Intrinsic Crack-Tip Plasticity
Authors: Farkas Diana
Published: February 2011

One of the most interesting unsolved problems in fracture mechanics is the precise understanding of the energy-dissipation mechanisms that occur as a crack advances. In most cases, this energy-release rate is many times the surface energy created. One of the main reasons for this difference is the fact that plastic deformation can occur in the crack-tip region as dislocations nucleate and are emitted from the crack tip. Experimental studies provide little insight into the precise mechanisms for this process because they cannot reach the atomistic scale. For example, a crack that may seem experimentally sharp, and therefore indicative of brittle fracture, may not be sharp at the atomic level. Continuum mechanics has a similar limitation, since the assumptions of elasticity theory usually break down in the crack-tip region. Atomistic simulation studies provide researchers an opportunity to obtain precise atomic configurations in the crack-tip region under various loading conditions and to observe the basic energy-dissipation mechanisms.
From Simulation to Theory in the Physics of Deformation and Fracture
Authors: Falk M. L. , Langer J. S.
Published: February 2011

Fracture dynamics remains a challenging research topic in materials science, mechanical engineering, mathematics, and nonequilibrium physics. Despite nearly a century of intense investigation, several basic problems remain unsolved. In particular, there is still no fundamental understanding of the distinction between brittle and ductile failure; there is still no definitive explanation of how breaking stresses can be transmitted through plastic zones near crack tips, nor is there an adequate understanding of why the energy-release rate even in brittle fracture is often orders of magnitude larger than the rate at which surface energy is created. These difficulties seem to stem primarily from the lack of an adequate theory of deformation near crack tips, where stresses and strain rates are large.
Thermal-Wave Probing at Various Spatial Scales
Authors: Fournier Danièle
Published: February 2011

In recent years, high thermal conductivity has been found in materials with heterogeneous microstructures, that is, ceramics and films with granular microstructures having different phases. Understanding the thermal conductivities and microstructures of these materials is more difficult, however, than in the case of single-crystal materials because they consist of grains and grain boundaries.
Emerging Methods for Micro- and Nanofabrication
Authors: Mirkin Chad A. , Rogers John A.
Published: February 2011

New methods for micro- and nanofabrication will be essential to scientific progress in many areas of biology, physics, chemistry, and materials science. They will also form enabling technologies for applications ranging from microfluidic devices to micro-optical components to molecular diagnostics to plastic electronics to nanoelectromechanical systems. In many cases, advances will be aided by the highly engineered and spectacularly successful lithographic techniques that are used for microelectronics. These methods have certain drawbacks, however, that will limit their applicability to new devices and fields of study. For example, photolithographies cannot be used with many organic and biological materials due to their chemical incompatibility with typical photoresists and developers; they cannot easily pattern features with dimensions of less than ∼100 nm; they require expensive capital equipment and facilities; they have difficulty forming features on curved, uneven, or rough objects; they can only directly pattern a small set of specialized, photosensitive materials; they cannot reproduce features with complex, three-dimensional (3D) shapes; and they can only pattern small areas in a single step. This situation creates a need for research into alternative patterning methods with capabilities that can complement those of photolithography and other established approaches.
Nanoimprint Lithography and Lithographically Induced Self-Assembly
Authors: Chou Stephen Y.
Published: February 2011

Our ability to pattern nanostructures offers a unique path to discovery and innovation in science and technology. When nanostructures are smaller than a fundamental physical length scale, conventional theory may no longer apply, and new phenomena emerge.
Fabrication of Three-Dimensional Microfluidic Systems by Soft Lithography
Authors: Love J. Christopher , Anderson Janelle R. , Whitesides George M.
Published: February 2011

Two-dimensional (2D) methods for transferring patterns to planar substrates have enabled the technological revolution in microfabrication that has marked the last 40 years. The overall trend toward increased miniaturization has led to the development of new types of devices in areas unrelated to conventional microelectronics: analytical tools, chemical reactors, microelectromechanical systems (MEMS), optical systems, and sensors. The widespread use and high level of technological development associated with photolithography has also made the methodologies for microelectronics—patterning photosensitive polymers, etching and deposition of thin films, and liftoff—ubiquitous in the fabrication of these new classes of microsystems. These new systems have specialized requirements, however, and are not simple extensions of microelectronics technologies. They often require materials—especially organic polymers—that are not commonly used in microelectronic systems, they must have low cost, and they may need 3D structures in order to implement complex designs. These requirements have stimulated the development of new methods for microfabrication.
Dip-Pen Nanolithography: Automated Fabrication of Custom Multicomponent Sub-100-Nanometer Surface Architectures
Authors: Mirkin Chad A.
Published: February 2011

As physical processes for generating miniaturized structures increase in resolution, the types of scientific questions one can ask and answer become increasingly refined. Indeed, if one had the capability to control surface architecture on the 1–100-nm length scale with reasonable speed and accuracy, one could ask and answer some of the most important questions in science and, in the process, develop technologies that could allow for major advances in surface science, chemistry, biology, and human health. This length scale, which is exceedingly difficult to control, comprises the length scale of much of chemistry and most of biology. Indeed, chemical and biochemical recognition events are essentially sophisticated examples of pattern-recognition processes. Therefore, if one could pattern on this length scale with control over feature size, shape, registration, and composition, one could systematically uncover the secrets of recognition processes involving extraordinarily complex molecules. Arecent invention, dip-pen nanolithography (DPN), may provide access to this type of control over surface architecture and entry into a new realm of structure-versus-function studies for chemists, biologists, physicists, and materials scientists.
High-Resolution Ink-Jet Printing of All-Polymer Transistor Circuits
Authors: Sirringhaus H. , Kawase T. , Friend R.H.
Published: February 2011

Impressive advances in vapor-phase deposition and photolithographic patterning techniques have been fueling the silicon microelectronics revolution over the last 40 years. However, for many interesting classes of materials, including biological materials or functional synthetic polymers, vacuum deposition and photolithography are not the techniques of choice for producing ordered structures and devices. Many of these materials selfassemble into well-ordered microstructures when deposited from solution, and patterning may be more readily achieved by solution-based selective deposition and direct-printing techniques. It is appealing to consider novel ways of manufacturing functional circuits and devices based on techniques that are similar to printing visual information onto paper.
Two- and Three-Dimensional Photonic Crystals Built with VLSI Tools
Authors: Lin Shawn-Yu , Fleming J.G. , Chow E.
Published: February 2011

The drive toward miniature photonic devices has been hindered by our inability to tightly control and manipulate light. Moreover, photonics technologies are typically not based on silicon and, until recently, only indirectly benefited from the rapid advances being made in silicon processing technology. In the first part of this article, the successful fabrication of three-dimensional (3D) photonic crystals using silicon processing will be discussed. This advance has been made possible through the use of integrated-circuit (IC) fabrication technologies (e.g., very largescale integration, VLSI) and may enable the penetration of Si processing into photonics. In the second part, we describe the creation of 2D photonic-crystal slabs operating at the λ = 1.55 μm communications wavelength. This class of 2D photonic crystals is particularly promising for planar on-chip guiding, trapping, and switching of light.
Photonic Crystals Made by Holographic Lithography
Authors: Turberfield A.J.
Published: February 2011

A photonic crystal is a periodically structured composite material, with a unit cell whose dimensions are of the order of an optical wavelength, made from constituents whose refractive indices differ greatly (Δn is of the order of 2). Three-dimensional (3D) photonic crystals typically consist of interpenetrating networks of dielectric material and air. Holographic lithography is a technology for the fabrication of photonic crystals in which the initial step is to define the 3D microstructure by interference of coherent light in a photosensitive precursor.
The Complex World of Plutonium Science
Authors: Hecker Siegfried S.
Published: February 2011

Plutonium symbolizes everything we associate with the nuclear age. It evokes the entire gamut of emotions from good to evil, from hope to despair, and from the salvation of humanity to its utter destruction. No other element bears such a burden. Its discovery in 1941, following the discovery of fission in 1938, unlocked the potential and fear of the nuclear age. During the Cold War, the primary interest in plutonium was to provide triggers for thermonuclear weapons that formed the basis of nuclear deterrence. Beginning in the 1950s, plutonium also became an integral part of the quest for nearly limitless electrical power. The end of the Cold War has dramatically altered the military postures of the United States and Russia, allowing each to reverse the engines fueling the nuclearweapons buildup. Now, both countries face the challenge of keeping the remaining stockpile of nuclear weapons safe and reliable without nuclear testing, as well as cleaning up nuclear contamination and preventing the spread of nuclear weapons and terrorism. Moreover, current concerns about energy availability and global warming have rekindled interest in nuclear power.
Understanding Actinides through the Role of 5f Electrons
Authors: Gouder T. , Wastin F. , Rebizant J. , Lander G.H.
Published: February 2011

Studies of the actinide elements and compounds were (and are) motivated by the need to characterize their structural and thermodynamic properties for the development of nuclear fuels and the treatment of waste, whether it be for long-term storage or ideas involving transmutation in high-powered accelerators. For the most part, tables giving these data exist, although the data for transuranium compounds are rather sparse. A much more difficult task is to understand the data and develop theories that have predictive power in this part of the periodic table. In doing this, however, we are confronted with the extremely complicated electronic structure of the 5f shell and the great paucity of high-quality data on materials containing transuranium isotopes.
Plutonium in Crystalline Ceramics and Glasses
Authors: Muller Isabelle , Weber William J.
Published: February 2011

The investigation of plutonium in glasses (amorphous ceramics lacking long-range order), in crystalline ceramics, and in composite materials composed of multiple crystalline or glass and crystalline phases, relieson multidisciplinary studies of physics, chemistry, and materials science. It involves the study of the plutonium atoms in materials with only short-range periodicity, as in glasses, to materials with long-range periodicity, as in crystals. The materials studied over the past 30 years include simple binary crystals, used to investigate the electronic structure of plutonium, to complex glasses and ceramics selected not only for the safety and durability that they provide for the immobilization of nuclear waste and plutonium, but also for the high flexibility they offer in composition. The lack of long-range order at the atomic level in glasses permits the inclusion of abroad range of waste elements, but it renders more difficult the interpretation of data from many commonly used experimental techniques. Regardless of the challenge, much of the research conducted in this field over the past few decades has been motivated by the use of plutonium as a surrogate for all nuclear-waste actinides or on its own in immobilization studies, in order to develop a durable glass or ceramic matrix that can resist leaching and mobilization of the plutonium on a geologic time scale.
Prospects for Molecular-Scale Electronics
Authors: Reed Mark A.
Published: February 2011

Scientific consideration of how to scale electronics down to the molecular level started in the mid-1970s. Unfortunately, at the time, researchers did not have the adequate analytical tools to perform the experiments. That has changed drastically, and therefore interest in this field has been renewed, especially over the last few years.
Multiscale Modeling of Thin-Film Deposition: Applications to Si Device Processing
Authors: Baumann F.H. , Chopp D.L. , de la Rubia T. Díaz , Gilmer G.H. , Greene J.E. , Huang H. , Kodambaka S. , O'Sullivan P. , Petrov I.
Published: February 2011

Metallization is the back end of the integrated-circuit (IC) fabrication process where the transistor interconnections are formed. Figure 1 shows the metallized part of a static random-access memory chip. Metal lines for electrical connections (Al and Cu) in Si devices are deposited as blanket films and then etched or polished away to define the conducting lines.
Crystal Plasticity from Dislocation Dynamics
Authors: Bulatov Vasily V. , Tang Meijie , Zbib Hussein M.
Published: February 2011

The strength of a material is its ability to withstand an applied load without breaking or changing its shape. The strength of an ideal, defect-free crystal can be very high, but except for rather exotic materials such as micrometer-sized whiskers, crystals will fracture and/or deform plastically under stresses that are well below their ideal strength limits.
On-Chip Testing of Mechanical Properties of MEMS Devices
Authors: Kahn H. , Heuer A.H. , Ballarini R.
Published: February 2011

The field of microelectromechanical systems (MEMS) involves the interaction of the physical environment with electrical signals through the use of microbatchfabricated devices. MEMS is a growing technology, and commercial MEMS products are becoming commonplace.
Microsystems Technology (MST) and MEMS Applications: An Overview
Authors: Elders Job , Spiering Vincent , Walsh Steve
Published: February 2011

Microelectromechanical systems (MEMS), microsystems technology (MST), and micromachines are roughly synonymous terms applied in the United States, Europe, and Japan, respectively, for manufacturing technologies that are enabling miniaturization and the development of useful products.
Defense Applications of MEMS
Authors: Tang William C. , Lee Abraham P.
Published: February 2011

The infusion of advanced technology into defense systems is accelerating, by necessity, to keep pace with the exponential growth in information accessibility. Critical to national security and global stability, military forces must sustain their technological edge over potential adversaries. It is obvious that such an advantage cannot be maintained by sole reliance on protecting access to high-tech information.
MEMS for Light-Wave Networks
Authors: Giles C. Randy , Bishop David , Aksyuk Vladimir
Published: February 2011

As demonstrated in this issue, the emerging field of microelectromechanical systems (MEMS) is beginning to impact almost every area of science and technology. MEMS have the potential to revolutionize light-wave systems. Microdevices such as optical switches, variable attenuators, active equalizers, add/drop multiplexers (ADMs), optical cross-connects (OXCs), gain tilt equalizers, data transmitters, and many others are beginning to find ubiquitous application in advanced light-wave systems.
Bridged Polysilses-quioxanes: Molecular Engineering of Hybrid Organic–Inorganic Materials
Authors: Shea K.J. , Loy D.A.
Published: February 2011

Hybrid materials lie at the interface of the organic and inorganic realms. These materials offer exceptional opportunities not only to combine important properties from both worlds, but also to create entirely new compositions with truly unique properties.
New Preparation Methods for Organic–Inorganic Polymer Hybrids
Authors: Chujo Yoshiki , Tamaki Ryo
Published: February 2011

Nano-ordered composite materials consisting of organic polymers and inorganic compounds have been attracting attention for their use in creating high-performance or high-functionality polymeric materials. The term “polymer hybrid” describes blends of organic and inorganic components with molecular-level dispersions.
Optical-Fiber Sensors
Authors: Fernando G. F. , Webb D. J. , Ferdinand Pierre
Published: February 2011

The primary aim of this issue of MRS Bulletin is to present an overview of the deployment of optical-fiber sensors in a selected range of applications. The topics covered include a general introduction to optical fibers; a review of the sensing mechanisms that are available to monitor strain, temperature, pressure, chemical species, damage, and acoustic emission; and the use of optical-fiber sensors in medical applications. This introductory article presents a brief discussion of the advantages and disadvantages of optical-fiber sensors.
Optical-Fiber Sensors: Temperature and Pressure Sensors
Authors: Grattan K. T. V. , Sun T.
Published: February 2011

This article gives a brief review of advances in optical-fiber temperature and pressure sensors. Developments over the last two decades have seen enhancements in utility and performance, as more advanced techniques are applied. Applications to industrial problems are highlighted.
The Application of Gain Theory to Vertical-Cavity Surface-Emitting Lasers
Authors: Chow Weng W. , Schneider Hans Christian
Published: February 2011

The development of vertical-cavity surface-emitting lasers (VCSELs) relies on an understanding of gain-medium physics, more so than in edge-emitting lasers. An important tool in the investigation of semiconductor gain behavior is a theory that provides a systematic account of the interaction between the laser field and the electron–hole plasma, the influence of the band structure, and the many-body effects due to Coulomb interactions among carriers. This article describes a semiclassical approach that is based on the semiconductor Bloch equations, with carrier correlation effects described at the level of quantum kinetic theory. To illustrate its application, we discuss research activities involving the development of gain media for long-wavelength VCSELs.
Scattering Studies of “Real” Materials
Authors: Moss Simon C.
Published: February 2011

The following article is based on the presentation given by Simon C. Moss (University of Houston), recipient of the 2001 MRS Von Hippel Award, the Materials Research Society's highest honor, at the 2001 MRS Fall Meeting on November 28 in Boston. Moss was cited for “consistently timely and essential contributions to identifying and understanding the atomic-level structure of almost every new type of material discovered in the last 30 years.” The main unifying thread in his work is the use of diffuse scattering of x-rays and neutrons from disordered and defective solids to study their structure as well as the effects that defects have on phase transitions, whose intrinsic disorder makes them both “real” and challenging.
Diffusional Creep: Stresses and Strain Rates in Thin Films and Multilayers
Authors: Josell D. , Weihs T. P. , Gao H.
Published: February 2011

In this article, we discuss creep deformation as it relates to thin films and multilayer foils. We begin by reviewing experimental techniques for studying creep deformation in thin-film geometries, listing the pros and cons of each; then we discuss the use of deformation-mechanism maps for recording and understanding observed creep behavior. We include a number of cautionary remarks regarding the impact of microstructural stability, zero-creep stresses, and transient-creep strains on stress–strain rate relationships, and we finish by reviewing the current state of knowledge for creep deformation in thin films. This includes both thin films that are heated on substrates as well as multilayer films that are tested as freestanding foils.
Portable Power: Advanced Rechargeable Lithium Batteries
Authors: Sadoway Donald R. , Mayes Anne M.
Published: February 2011

The full potential of wireless devices remains unattainable due to limitations in battery performance. It is the thesis of the guest editors and contributing authors of this issue of MRS Bulletin that there is much room for improvement, that we are still far from the practical limits of the technology, and that materials research has the capability to pave the way for a new generation of rechargeable batteries that will offer a dramatic improvement in power delivery over anything available today. The basics of battery operation, including the relevant electrochemistry, are reviewed, unsolved problems are enumerated, and prospective solutions are indicated.
Developments in Polymer Electrolytes for Lithium Batteries
Authors: Wright Peter V.
Published: February 2011

Recent developments in polymer electrolyte materials for lithium batteries are reviewed in this article. Four general classifications are recognized: (1) solvent-containing systems in which a liquid electrolyte solution either is fully miscible with a single-phase swollen polymer matrix (gel) or is a two-phase system in which “free” liquid occupies micropores within a swollen polymer network (hybrid), and conductivity (≥∼1 mS cm-1 at ambient temperature) is essentially independent of the polymer segmental motion (the thermal motion of segments of atoms along the backbone of a flexible polymer chain); (2) solvent-free, ion-coupled systems (typically polyether–Li salt complexes) in which both anions and cations are mobile within an amorphous, rubbery phase (conductivity ≤0.1 mS cm-1 at ambient temperature); (3) “single-ion” systems with anions fixed to the polymer backbone or systems with anion mobilities reduced by incorporation within larger molecules or by associations with the chain (conductivity ∼10-5 Scm-1 at ambient temperature); and (4) decoupled systems in which ionic mobility through channeled structures involves minimal local segmental displacements (conductivity 0.1–1 mS cm-1 at ambient temperature).
Layered Li(Ni, M)O2Systems as the Cathode Material in Lithium-Ion Batteries
Authors: Delmas C. , Croguennec L.
Published: February 2011

Compared with LiCoO2, the dominant cathode material in today's lithium batteries, lithium nickel oxide derivatives [Li(Ni, M)O2, where M – Co, Fe, Al, Mg] offer a higher specific energy at a lower cost. The synthesis and structure of these materials are described. The electrochemical performances of the pure nickel compound and a number of multicomponent systems are assessed. The goals of these fundamental studies are to optimize the synthesis conditions and material composition to achieve good electrochemical reversibility, decrease capacity loss upon cycling, and enhance thermal stability in the deintercalated state in order to improve cell safety.
Nuclear Magnetic Resonance Studies of Lithium-Ion Battery Materials
Authors: Grey Clare P. , Greenbaum Steve G.
Published: February 2011

Solid-state nuclear magnetic resonance (NMR) spectroscopy has been employed to characterize a variety of phenomena that are central to the functioning of lithium and lithium-ion batteries. These include Li insertion and de-insertion mechanisms in carbonaceous and other anode materials and in transition-metal oxide cathodes, and ion-transport mechanisms in polymer and gel electrolytes. Investigations carried out over the last several years by the authors and other groups are reviewed in this article. Results for lithium manganese oxide spinel cathodes, carbon-based and SnO anodes, and polymer and gel electrolytes are discussed.
Computational Modeling and Simulation for Rechargeable Batteries
Authors: Ceder Gerbrand , Doyle Marc , Arora Pankaj , Fuentes Yuris
Published: February 2011

Computational modeling is playing an increasingly important role in materials research and design. At the system level, the impact of cell design, electrode thickness, electrode morphology, new packaging techniques, and numerous other factors on battery performance can be predicted with battery simulators based on complex electrochemical transport equations. Such simulation tools have allowed the battery industry to optimize the power and energy density that can be achieved with a given set of electrode and electrolyte materials. At the materials level, first-principles calculations, which can be used to predict properties of previously unknown materials ab initio, have now made it possible to design materials for higher capacity and better stability. The state of the art in computational modeling of rechargeable batteries is reviewed.
Hydrogen as a Fuel and Its Storage for Mobility and Transport
Authors: Schlapbach Louis
Published: February 2011

This brief article describes the content of this issue of MRS Bulletin on Hydrogen Storage. Hydrogen is a powerful, clean, synthetic fuel with the inconvenient property of being an ideal gas under ambient conditions. In order to use hydrogen efficiently as a fuel, compacting it for mobile storage is a key issue. As an introduction to the following seven contributions on different storage techniques and their potential, we start with a description of the technical and socioeconomic aspects of the mobility and transport issues involved and present an overview of volumetric and gravimetric storage densities for hydrogen.
Hydrogen Storage: High-Pressure Gas Containment
Authors: Irani R.S.
Published: February 2011

This review outlines the prospects for gaseous hydrogen, stored in high-pressure cylinders, as a fuel for automotive applications. Following an initial description of hydrogen embrittlement problems encountered in the past in steel cylinders, the article explores the use of other types of gas cylinders, including the recent examples of hoop-wound and fully wound composites. Central to the article is the concept of the volume of hydrogen transported for the minimum amount of container weight. Finally, the role of international standards in developing safe and efficient cylinders for this application is emphasized.
Liquid-Hydrogen Technology for Vehicles
Authors: Wolf Joachim
Published: February 2011

This survey focuses on the use of liquid hydrogen as an automotive fuel in comparison with the use of compressed gaseous hydrogen. The energy penalties associated with liquefaction versus gas compression are compared, followed by an examination of the weight of hydrogen relative to carrier weight for the two alternative approaches. The optimum form and design of LH2 tanks are discussed, followed by the important topic of how to achieve quick and easy transfer of LH2 from a storage tank to a vehicle.
Hydrogen in Nanostructured, Carbon-Related, and Metallic Materials
Authors: Züttel Andreas , Orimo Shin-ichi
Published: February 2011

Recent developments in hydrogen interaction with carbonaceous materials are reviewed in this article. The interaction is based on van der Waals attractive forces (physisorption), or the overlap of the highest occupied molecular orbitals of carbon with the hydrogen electron, overcoming the activation-energy barrier for hydrogen dissociation (chemisorption). While the physisorption of hydrogen limits the hydrogen-to-carbon ratio to less than one hydrogen atom per two carbon atoms (i.e., 4.2 mass%), in chemisorption, a ratio of two hydrogen atoms per one carbon atom is realized (e.g., in polyethylene). However, the materials with large hydrogen-to-carbon ratios only liberate the hydrogen at elevated temperature. No evidence, apart from theoretical calculations, was found for a new hydrogen-adsorption phenomenon on carbon nanotubes (CNTs), as compared with high-surface-area graphite. The curvature of CNTs and fullerenes increases the reactivity of these materials with hydrogen and leads more easily to the formation of hydrocarbons, as compared with graphite. Nanocrystalline or amorphous carbon exhibits an intermediate state for hydrogen between physisorption and chemisorption and absorbs up to one hydrogen atom per carbon atom. Nanostructured carbonaceous and metallic materials offer a large potential for hydrogen storage and must therefore be investigated in more detail.
Advances in Chemical-Mechanical Planarization
Authors: Singh Rajiv K. , Bajaj Rajeev
Published: February 2011

The primary aim of this issue of MRS Bulletin is to present an overview of the materials issues in chemical–mechanical planarization (CMP), also known as chemical–mechanial polishing, a process that is used in the semiconductor industry to isolate and connect individual transistors on a chip. The CMP process has been the fastest-growing semiconductor operation in the last decade, and its future growth is being fueled by the introduction of copper-based interconnects in advanced microprocessors and other devices. Articles in this issue range from providing a fundamental understanding of the CMP process to the latest advancements in the field. Topics covered in these articles include an overview of CMP, fundamental principles of slurry design, understanding wafer–pad–slurry interactions, process integration issues, the formulation of abrasive-free slurries for copper polishing, understanding surface topography issues in shallow trench isolation, and emerging applications.
The Future of CMP
Authors: Evans David
Published: February 2011

Chemical–mechanical polishing, or planarization (CMP), is one of several advanced microfabrication processes that provide complementary capabilities for constructing advanced electronic devices. At the current state of the art, CMP demonstrates significant advantages due to its high degree of process flexibility, particularly in the chemical formulation of polishing solutions and slurries. This article explores some possible future applications of CMP using new advanced materials other than silicon, silicon oxide, and silicon nitride. Such materials may include refractory and noble metals, high-κ insulators, and mixed metal oxide perovskites. Although no one can predict future applications with absolute certainty, it seems safe to conclude that CMP will remain a key microfabrication technology for the foreseeable future.
On the Road to an Atomic- and Molecular-Level Understanding of Friction
Authors: Mathew Mate C.
Published: February 2011

The following article is an edited transcript based on the MRS Medal presentation given by C. Mathew Mate of IBM Almaden Research Center on November 29, 2001, at the Materials Research Society Fall Meeting in Boston. Mate received the Medal for his “pioneering studies of friction at the atomic and molecular levels.” This presentation describes some of his efforts at understanding friction at the atomic level. The starting point for the author was the invention of the friction force microscope and the first observation of atomic-scale friction in 1987. Soon afterward came other applications of force microscopy, leading toward a greater understanding of friction, lubrication, and wear. These studies also have had an impact on the understanding of lubricant films in disk drives and are now aiding the development of nanoscale devices such as the “molecular raft,” an 8-Å-thick island of squalane floating on a thicker squalane film that could potentially be used to transport nanoscale objects.
Reverse Engineering: Learning from Proteins How to Enhance the Performance of Synthetic Nanosystems
Authors: Vogel Viola
Published: February 2011

Proteins are nature's workhorses. They enable living systems to use available energy sources and convert energy from one form into another. Understanding the underlying design principles of how proteins have evolved to fulfill the necessary functions of life can provide researchers with new insights into how to enhance the performance of synthetic nanosystems with far greater sophistication. This review summarizes the relationship between various protein functions and the underlying engineering principles of their overall structures. For example, proteins can specifically recognize other biomolecules with a selectivity and affinity several orders of magnitude superior to their synthetic counterparts. Mimicking a protein binding site with a structurally fixed synthetic analogue is insufficient, since structural changes in the active sites enhance molecular recognition and the catalytic activity of proteins. Recent data also show that protein function can be switched by stretching proteins into nonequilibrium states under physiological conditions. Schemes by which the exposure and structure of recognition sites are switched can be implemented in the design of mechanically responsive synthetic and hybrid systems. Motor proteins, finally, are the jewel in nature's crown, as they can convert one free-energy form into another to generate mechanical force. It is thus of considerable interest to integrate the chemically powered engines into synthetic materials and devices. Finally, we have to advance our ability to assemble nanocomponents into functional systems. Again, lessons can be learned from how biology solves the challenge of systems integration.
Ancient and Modern Steels and Laminated Composites Containing Steels
Authors: Wadsworth Jeffrey
Published: February 2011

A class of steels (ultrahigh-carbon steels, or UHCSs) containing high levels of carbon (i.e., ∼1–2 wt%) were originally developed for their superplastic characteristics. In combination with excellent room-temperature properties, the steels were developed for their commercial potential starting in the mid-1970s and continuing to the present time. The compositional similarities between these modern steels and ancient Damascus steels led to a revisiting of the history and metallurgy of Damascus and related steels. Also, as part of the development of UHCSs, modern laminated composites containing them have been designed and manufactured that have unique toughness characteristics. These laminated composites also have similarities to a range of laminated materials of historical interest. Finally, some comments are made on the utility of radiocarbon dating to determine the age of ancient irons and steels. Ten sidebars supplement this article as Web Extras on the MRS Bulletin Web site at www.mrs.org/publications/bulletin/2002/dec/.
Giant Magnetostriction in Ferromagnetic Shape-Memory Alloys
Authors: Kakeshita Tomoyuki , Ullakko Kari
Published: February 2011

Shape-memory alloys are now widely used because they exhibit a large recoverable strain, which is caused by the conversion of variants in the martensite phase. The conversion of variants is usually promoted by the application of external stress. Recently, however, it was found that the conversion of variants can also be promoted by the application of a magnetic field to induce the martensitic state in ferromagnetic Ni2MnGa shape-memory alloys. Since then, the research in this field has focused considerable attention on applications for using the materials as actuators and sensors because their response to a magnetic field is much faster than their response to heating or cooling. Furthermore, the mechanism of the conversion of variants by the magnetic field has attracted academic interest from many researchers. In this article, we show giant magnetostrictive behavior in three ferromagnetic shape-memory alloys—Ni2MnGa, Fe-Pd, and Fe3Pt—and review the investigations performed so far by many researchers, including the present authors.
New Directions in Photopolymerizable Biomaterials
Authors: Anseth Kristi S. , Burdick Jason A.
Published: February 2011

This article is based on the Outstanding Young Investigator Award presentation given by Kristi S. Anseth at the 2001 MRS Spring Meeting on April 17, 2001, in San Francisco. Anseth was recognized for “innovative work in polymeric biomaterials for drug delivery, bone and cartilage repair, and tissue engineering, and for outstanding leadership potential in this interdisciplinary field of materials research.”

Photopolymerization provides many advantages as a technique for the fabrication of biomaterials. Temporal and spatial control, along with the diversity in material properties found with photopolymerizable materials, are advantageous in the biomaterials industry. For instance, multifunctional anhydride monomers form highly cross-linked surface-eroding networks directly in bone defects. These networks have good mechanical properties that are maintained with degradation and have the potential to restore tissue-like properties to bone during the healing process. Additionally, cartilage-forming cells photoencapsulated in hydrogel networks secrete an extracellular matrix as the hydrogel is resorbed and may provide a treatment alternative for cartilage defects that do not heal spontaneously. Finally, transdermal polymerization (photopolymerization through the skin) of multifunctional monomers is a noninvasive technique that is being developed for tissue regeneration and wound-healing applications.
Alternative Gate Dielectrics for Microelectronics
Authors: Wallace Robert M. , Wilk Glen
Published: February 2011

This brief article sets the context for the March 2002 issue of MRS Bulletin focusing on Alternative Gate Dielectrics for Microelectronics. Contributors are several experts from industry and academia engaged in the search for manufacturable solutions for a suitable alternative gate dielectric to SiO2 using high-dielectric-constant (high-ĸ) materials. Issues discussed in the articles include thermodynamics criteria for materials selection, materials interactions in the construction of the transistor gate stack, characterization of alternative materials, determination of suitable band offsets for candidate dielectrics, and integration of these alternative gate dielectrics in a manufacturable environment.
Compatibility Challenges for High-ĸ Materials Integration into CMOS Technology
Authors: Guha Supratik , Gusev Evgeni , Copel Matthew , Ragnarsson Lars-Åke , Buchanan Douglas A.
Published: February 2011

In addition to meeting the formidable challenges of replacing the nearly perfect SiO2 dielectric, a new dielectric ideally needs to replace SiO2 with minimal rearrangement of the complementary metal oxide semiconductor (CMOS) process flow. In this article, we outline the essential materials-integration issues that arise out of the technical requirements for minimizing changes to future process technologies. These include interfacial layer formation, film microstructure, deposition technologies, and electrical performance challenges such as trapped charge and the mobility degradation associated with any replacement material. Integration of the high-ĸ materials currently under consideration presents a significant challenge for materials scientists and engineers in industry and academia.
Combinatorial Screening and Optimization of Luminescent Materials and Organic Light-Emitting Devices
Authors: Sun Ted X. , Jabbour G.E.
Published: February 2011

The rapid development of modern photonic technologies—for example, mercury-free lamps, flat-panel displays, and solid-state lamps—demands the timely discovery of advanced phosphors. A combinatorial process has been developed to dramatically accelerate the experimental search for such phosphors. High-density phosphor “libraries” containing from 100 to over 1000 discrete chemical compositions on a 1 in. × 1 in. substrate have been made in thin-film or powder form using selective vapor deposition and liquid-dispensing techniques, respectively. In this article, the existing methods of combinatorial synthesis and screening of phosphors will be reviewed with examples. These methods may also be used to screen organic-based solid-state materials and optimize their device properties. In this regard, combinatorial and spreading techniques have been utilized to study and rapidly optimize organic light-emitting devices (OLEDs).
Continuous Phase Diagramming of Epitaxial Films
Authors: Yoo Young K. , Tsui Frank
Published: February 2011

High-throughput and systematic studies of complex materials systems using the approach of “continuous phase diagramming” (CPD) are described in this article. The discussions focus on the techniques of epitaxial film synthesis of CPD and mapping physical and structural properties, using two different material systems as examples: doped perovskite manganese oxides and magnetic alloys. In doped perovskite manganese oxides, a highly correlated system, mapping the optical, electrical, and magnetic properties, reveals surprising evidence of electronic phase transitions that correlate with the low-temperature magnetic order. In magnetic alloys, application of CPD, particularly using real-time characterization during epitaxial growth, makes it possible to examine structure–property relations systematically.
Material Aspects of Standard Transmission Optical Fibers
Authors: Guenot P.
Published: February 2011

This article reviews loss components of standard transmission silica optical fibers and their connections to glass structure and manufacturing parameters. Loss-reduction possibilities are described. In particular, the Rayleigh scattering component, which is the main contributor to fiber losses within the transmission window, can be significantly reduced by lowering the fictive temperature (the temperature at which the liquid structure is “frozen” during cooling) and tuning the glass composition. The issue of a compromise between manufacturing productivity and minimization of excess loss is also addressed.
Materials Science of Adhesives: How to Bond Things Together
Authors: Creton Costantino , Papon Eric
Published: February 2011

This issue of MRS Bulletin provides an overview of the state of the art and emerging trends in the area of adhesives. An adhesive is basically defined by its function, which is to assemble two surfaces together. In order to fulfill this function, the properties of an adhesive must include easy positioning at the interface, rapid and complete bond formation and subsequent hardening, and a bond strength adapted to the specific application (structural, permanent, removable, rigid, or soft). A variety of solutions exist in practice, and their application requires an understanding both of polymer chemistry and materials science. The main families of adhesives, their properties, and their basic design principles will be discussed in the articles in this issue, while this introductory article presents an overview of the functions required of adhesives and future trends.
Pressure-Sensitive Adhesives: An Introductory Course
Authors: Creton Costantino
Published: February 2011

Self-adhesive materials are called, in the adhesives trade, “pressure-sensitive adhesives” (PSAs). PSAs are designed to stick on almost any surface by simple contact under light pressure. This special class of adhesives does not undergo any physical transformation or chemical reaction during the bonding process. Because of this, the rheological properties of the adhesive must be finely tuned for the application, combining a carefully chosen polymer architecture and monomer composition with the proper addition of small molecules called tackifying resins. PSAs are soft, deformable solids and, depending on the formulation, easily form bridging fibrils between two surfaces upon debonding. They are safe to use and easy to handle and thus are increasingly replacing more conventional types of adhesives. In this article, we review both the primary material characteristics of PSAs and the main physical principles that make them work effectively.
Nanoscale Science and Technology: Building a Big Future from Small Things
Authors: Lieber Charles M.
Published: February 2011

The following article is an edited transcript based on the MRS Medalist presentation given by Charles M. Lieber of Harvard University on December 4, 2002, at the Materials Research Society Fall Meeting in Boston. Lieber received the Medal “for controlled synthesis of nanowire and nanotube materials.” This presentation begins with an introduction to the bottom-up paradigm of nanoscience and nanotechnology. The key concepts of this paradigm are explored through studies outlining progress toward meeting the challenge of nanocomputing through the assembly of functional nanowire elements. The richness of the bottom-up paradigm and nanowire building blocks is then illustrated with the development of chemical and biological nanosensors. Finally, the uniqueness of nanowires is exemplified through discussion of the assembly of nanophotonic devices, including the demonstration of multicolor and addressable nanoscale light-emitting diodes, nanowire injection lasers, and assembled arrays of these nanophotonic sources. Challenges and goals for realizing nanotechnologies in the future are discussed in the conclusion.
The Art and Materials Science of 190-mph Superbikes
Authors: Falco Charles M.
Published: February 2011

The following article is an edited transcript of a talk presented in Symposium X—Frontiers of Materials Research at the 2002 Materials Research Society Fall Meeting in Boston on December 2, 2002. From Bessemer steel used on the first motorized bicycle in 1871 to sintered aluminum ceramic composites and TiN thin-film coatings used on standard production machines today, motorcycles have been at the forefront of the use of high-performance materials. Thanks to developments in materials technology, relatively inexpensive mass-produced motorcycles are now capable of achieving speeds of >190 mph.
Chemical and Biological Protection and Detection in Fabrics for Protective Clothing
Authors: Schreuder-Gibson Heidi L. , Truong Quoc , Walker John E. , Owens Jeffery R. , Wander Joseph D. , Jones Wayne E.
Published: February 2011

Military, firefighter, law enforcement, and medical personnel require high-level protection when dealing with chemical and biological threats in many environments ranging from combat to urban, agricultural, and industrial. Current protective clothing is based on full barrier protection, such as hazardous materials (HAZMAT) suits, or permeable adsorptive protective overgarments, such as those used by the U.S. military. New protective garment systems are envisioned that contain novel features, such as the capability to selectively block toxic chemicals, to chemically destroy toxic materials that contact the fabric, and to detect hazardous agents on the surface of the fabric. New technologies being built into advanced fabrics for enhanced chemical and biological protection include selectively permeable membranes, reactive nanoparticles, reactive nanofibers, biocidal fabric treatments, and conductive-polymer indicators on optical fibers.