bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Tape: The Challenge of Reaching Hard-Disk-Drive Data Densities on Flexible Media
Authors: Dee Richard H.
Published: February 2011

By the end of 2006, the areal density of magnetic recording on tape will approach that seen in hard disk drives of the early to mid-1990s.These operating conditions are reviewed in relation to the operating conditions deemed necessary for the future of magnetic data storage on tape.What results is a clear set of tasks, encompassing both materials and systems architecture issues, to achieve very high-density data storage on magnetic tape, leading to 10 Tbyte tape cartridge capacities and higher.The key to achieving on tape the areal densities of tens to hundreds of Gbit in.2, common in hard disk drives (HDDs), lies primarily in the properties of the medium itself.As for volumetric density of the storage entity, HDDs and tape cartridges are roughly equivalent.The mechanical dimensional uncertainties that accompany the use of flexible, as opposed to rigid, media means that both the mechanical and magnetic properties of materials play a key role in the future of tape.The need for new architectures to overcome the track placement problem that results from increasing track density on flexible media are reviewed, as well as the “particles in a binder” concept that has served so well as the physical basis of tape media over the past 50 years.
Macroelectronics
Authors: Reuss Robert H. , Hopper Darrel G. , Park Jae-Geun
Published: February 2011

As revolutionary as microelectronics has been as a technology, there are functions that it does not address. Microelectronics focuses on ever-smaller integrated circuits (ICs) in ever-fewer square millimeters of space to increase clock speeds and decrease the power required for computer processing functions. However, applications requiring control, communications, computing, and sensing over a large area are difficult or costprohibitive to achieve because of the material incompatibilities of traditional ICs with structures, materials, and manufacturing technology. Macroelectronics addresses these applications with the aim of providing active control circuitry in situ over areas of many square meters for displays, solar panels, x-ray imagers, surface measurements, structural shape control, vehicle health monitoring, and other large-system applications. The materials challenges of macroelectronics integrated circuits (MEICs) reviewed in this issue include lightweight flexible substrates, thin-film transistors (TFTs) with IC or near-IC performance, modeling, and manufacturing technology. Compatible component materials, flexible substrates, processing conditions, host system composition, and functionality provide grand challenges that are just beginning to be addressed by researchers.
Development of High-Performance Organic Thin-Film Transistors for Large-Area Displays
Authors: Lee Sangyun , Koo Bonwon , Park Jae-Geun , Moon Hyunsik , Hahn Jungseok , Kim Jong Min
Published: February 2011

Organic thin-film transistors (OTFTs) are considered indispensable in applications requiring flexibility, large area, low processing temperature, and low cost. Key challenges to be addressed include developing solution-processable gate dielectric materials that form uniform films over large areas and exhibit excellent insulating properties, reducing contact resistance at interfaces between organic semiconductors and electrodes, and optimizing the patterning of organic semiconductors. High-performance pentacene-based OTFTs have been reported with polymeric gate dielectrics and indium tin oxide source/drain electrodes. Using such OTFT backplates, a 15-in. 1024 X 768 pixel full-color active-matrix liquid-crystal display (AMLCD) and a 4.5-in. 192 X64 pixel active-matrix organic light-emitting diode (AMOLED) have been fabricated.
Toward Manufacturing Low-Cost, Large-Area Electronics
Authors: Chason Marc , Gamota Daniel R. , Brazis Paul W. , Kalyanasundaram Krishna , Zhang Jie , Lian Keryn K. , Croswell Robert
Published: February 2011

Developments originally targeted toward economical manufacturing of telecommunications products have planted the seeds for new opportunities such as low-cost, large-area electronics based on printing technologies. Organic-based materials systems for printed wiring board (PWB) construction have opened up unique opportunities for materials research in the fabrication of modular electronic systems.

The realization of successful consumer products has been driven by materials developments that expand PWB functionality through embedded passive components, novel MEMS structures (e.g., meso-MEMS, in which the PWB-based structures are at the milliscale instead of the microscale), and microfluidics within the PWB. Furthermore, materials research is opening up a new world of printed electronics technology, where active devices are being realized through the convergence of printing technologies and microelectronics.
Materials Science of Supported Lipid Membranes
Authors: Parikh Atul N. , Groves Jay T.
Published: February 2011

Supported membranes represent an elegant route to designing well-defined fluid interfaces which mimic many physical-chemical properties of biological membranes. Recent years have witnessed rapid growth in the applications of physical and materials science approaches in understanding and controlling lipid membranes. Applying these approaches is enabling the determination of their structure-dynamics-function relations and allowing the design of membrane-mimetic devices. The collection of articles presented in this issue of MRS Bulletin illustrates the breadth of activity in this growing partnership between materials science and biophysics. Together, these articles highlight some of the key challenges of cellular membranes and exemplify their utility in fundamental biophysical studies and technological applications. The topics covered also confirm the importance of lipid membranes as an exciting example of soft condensed matter. We hope that this issue will serve readers by highlighting the intellectual scope and emerging opportunities in this highly interdisciplinary area of materials research.
Dynamical Heterogeneity in Supported Lipid Bilayers
Authors: Zhang Liangfang , Granick Steve
Published: February 2011

Planar-supported phospholipid bilayers are responsive surfaces that reconstruct when macromolecules adsorb. This review outlines the phenomenon of lipid diffusion “slaved” to or significantly controlled by that of macromolecular adsorbates. To elucidate such systems, we discuss the value of spatially resolved experiments at the few-molecule level, lipid diffusion compared in outer and inner leaflets of the supported bilayer, and a simple method to minimize defects by the strategy of “electrostatic stitching.”
Making Lipid Membranes Rough, Tough, and Ready to Hit the Road
Authors: Daniel Susan , Albertorio Fernando , Cremer Paul S.
Published: February 2011

Solid-supported lipid bilayers hold strong promise as bioanalytical sensor platforms because they readily mimic the same multivalent ligand-receptor interactions that occur in real cells. Such devices might be used to monitor air and water quality under real-world conditions. At present, however, supported membranes are considered too fragile to survive the harsh environments typically required for non-laboratory use. Specifically, they lack the resiliency to withstand air exposure and the thermal and mechanical stresses associated with device transport, storage, and continuous use over long periods of time. Several successful strategies are now emerging to make supported membranes tougher. These strategies incorporate mimics of the cytoskeleton and glycocalyx of real cell membranes. The promise of these more robust lipid bilayer architectures indicates that future materials should be designed to more fully resemble the actual structure of cell membranes.
Applications of Biomembranes in Drug Discovery
Authors: Fang Ye , Hong Yulong , Webb Brian , Lahiri Joydeep
Published: February 2011

Molecules in the cell membrane are key targets for therapeutic intervention. Technologies that enable the preservation of membrane-bound targets in their biomimetic and pharmacologically active states for screening of potential drug compounds are of great interest to bio-pharmaceutical companies. This review discusses emerging biomembrane technologies with a focus on biomembrane microarrays that enable the parallel analysis of multiple membrane-bound targets.
Characterization of Mechanical and Thermal Properties Using Ultrafast Optical Metrology
Authors: Antonelli G. Andrew , Perrin Bernard , Daly Brian C. , Cahill David G.
Published: February 2011

Ultrafast lasers have long been used to study the dynamics of fast optical, electronic, and chemical processes in materials. These tools can also be used in a variety of optical pump and probe spectroscopies to generate and detect acoustic signals with frequencies on the order of 100 GHz, and to generate and detect thermal waves with penetration depths on the scale of nanometers. The short wavelengths of these probes make them ideal for the study of the mechanical and thermal properties of thin films, their interfaces, and nanostructures. We describe the picosecond-laser acoustics technique and demonstrate how it can be used to extract the elastic constants and the adhesion of thin films and probe the normal modes of vibration of nanostructures. The thermal properties of thin films are also accessible through time-domain thermoreflectance. Since the mechanical and thermal properties can be obtained quickly on micrometer-scale regions of a sample, spatial mapping of the properties is also possible.
Ultrafast Imaging of Materials: Exploring the Gap of Space and Time
Authors: King Wayne E. , Armstrong Michael , Malka Victor , Reed Bryan W. , Rousse Antoine
Published: February 2011

The materials science community is poised to take advantage of new technologies that add unprecedented time resolution to already existing spatial-resolution capabilities. In the same way that chemists and biologists are using ultrafast optical, photon, and particle techniques to reveal transition pathways, materials scientists can expect to use variations of these methods to probe the most fundamental aspects of complex transient phenomena in materials. The combination of high-spatial-resolution imaging with high time resolution is critical because it enables the observation of specific phenomena that are important to developing fundamental understanding. Such a capability is also important because it enables experiments that are on the same time and length scales as recent high-performance computer simulations. This article describes several new techniques that have great potential for broader application in materials science, including electron, x-ray, and γ-ray imaging.
Ultrafast Processes for Bulk Modification of Transparent Materials
Authors: Itoh Kazuyoshi , Watanabe Wataru , Nolte Stefan , Schaffer Chris B.
Published: February 2011

When a femtosecond laser pulse is focused inside a transparent material, the optical intensity in the focal volume can become high enough to induce permanent structural modifications such as a refractive index change or the formation of a small vacancy. Thus, one can micromachine structures inside the bulk of a transparent material in three dimensions. We review the mechanisms of and techniques for bulk modification of transparent materials using femtosecond laser pulses and discuss the fabrication of photonic and other structures in transparent materials, including waveguides, couplers, gratings, diffractive lenses, optical data storage, and microfluidic channels.
Toward Computational Materials Design: The Impact of Density Functional Theory on Materials Research
Authors: Hafner Jürgen , Wolverton Christopher , Ceder Gerbrand
Published: February 2011

The development of modern materials science has led to a growing need to understand the phenomena determining the properties of materials and processes on an atomistic level. The interactions between atoms and electrons are governed by the laws of quantum mechanics; hence, accurate and efficient techniques for solving the basic quantum-mechanical equations for complex many-atom, many-electron systems must be developed. Density functional theory (DFT) marks a decisive breakthrough in these efforts, and in the past decade DFT has had a rapidly growing impact not only on fundamental but also industrial research. This article discusses the fundamental principles of DFT and the highly efficient computational tools that have been developed for its application to complex problems in materials science. Also highlighted are state-of-the-art applications in many areas of materials research, such as structural materials, catalysis and surface science, nanomaterials, and biomaterials and geophysics.
Applications of Density Functional Theory in the Geosciences
Authors: Brodholt John P. , Voĉadlo L
Published: February 2011

Although density functional theory (DFT) calculations have been widely used in many areas of the geosciences for the last 15 years, arguably the most successful application of these methods has been when they are used to understand the properties of minerals and melts in the Earth's pressures of the Earth's 6000 K and 360GPa) are so extreme that experiments under these conditions are very difficult. DFT calculations have been used to provide invaluable estimates of physical parameters that are fundamental to understanding the dynamics and evolution of the Earth. In particular, DFT calculations have helped provide estimates of the mineralogy and chemistry of the Earth's core, the high-temperature and pressure elasticity of the stable crystal phases in the mantle, the effect of defects on physical properties of mantle minerals, and, most recently, the discovery of a new phase of (Mg, Fe)SiO3just above the core. These and other applications of DFT in the geosciences are described and their implications discussed.
Realistic Modeling of Nanostructures Using Density Functional Theory
Authors: Marzari Nicola
Published: February 2011

The development of materials and devices at the nanoscale presents great challenges, from synthesis to assembly to characterization. Often, progress can only be made by complementing experimental work with electronic-structure modeling, harnessing the efficiency, predictive power, and atomic resolution of density functional theory to describe molecular architectures exactly at those scales (hundreds or thousands of atoms) where the most promising and undiscovered properties are to be engineered. Some of the next-generation technologies that will benefit first from first-principles simulations encompass areas as diverse as energy and information storage and retrieval, detection and sensing of biological and foreign contaminants, nanostructured catalysts, nanomechanical devices, hybrid organic-inorganic and biologically inspired materials, and novel computer technologies based on integrated optical and electronic platforms. This article reviews some of the recent successes and insights gained by electronic-structure modeling, ranging from carbon nanotubes to semiconducting nanoparticles, quantum dots, and self-assembled monolayers.
Carbon-Based Membranes
Authors: Pietraß Tanja
Published: February 2011

Inorganic carbon-based membranes for gas separation comprise materials that are fabricated through pyrolysis of a precursor material (often a synthetic polymer), and the more recently discovered carbon nanotubes. Fabrication, assembly into different architectures, and mechanism of operation are summarized for precursor-based carbon membranes, with a focus on selective surface flow and molecular sieving. Only preliminary work on carbon nanotube-based membranes for gas separation has been published. Their unusual transport properties, however, promise their use in gas separation in the future. In light of this application, structural properties and results relating to flow through these tubular structures are summarized.
Materials for Micro- and Nanofluidics
Authors: Kenis Paul J.A. , Stroock Abraham D.
Published: February 2011

Over the last two decades, our ability to create networks of fluidic channels of submillimeter or even sub-micrometer diameters has led to a wide range of microchemical applications. Whereas early efforts were directed toward the development of microanalysis systems, in more recent times the development of microreactors and tools for biotechnology and basic biological studies has emerged. This issue of MRS Bulletin highlights the many different ways in which material properties are crucial in the fabrication, assembly, and operation of micro- and nanofluidic systems. Choice-of-material considerations range from an assessment of whether a desired channel design can be microfabricated in a certain material to whether the material is compatible with the operating conditions (i.e., pressure, temperature) and the chemical composition (solvent, solutes) of the fluid used. Moreover, in certain cases, specific surface or bulk material properties can be used to the benefit of the application of the device. In the development of today's wide range of integrated micro- and nanofluidic applications, a common challenge emerges: meeting the often contradictory set of constraints imposed on the physical and chemical properties of materials by the envisioned applications. This issue reviews these challenges and their solutions and provides an outlook on how the ingenious use of existing and new materials can spur the development of ever more sophisticated micro- and nanofluidic systems.
The Digital Evolution
Authors: Barrett Craig R.
Published: February 2011

The following article is an edited transcript based on the plenary address given by Craig R. Barrett, chair of the board of Intel Corp., on April 19, 2006, at the 2006 Materials Research Society Spring Meeting in San Francisco. Since before the industrial revolution, technology has changed lives, opportunities, and economies. Similarly, the digital evolution has touched nearly every aspect of modern life and is reshaping economies around the world. As more and more of the world's people engage in the digital economy, both competition and opportunities will grow. Competitiveness in the global economy will be determined by how people and nations position themselves in the digital evolution. What lies ahead for us in the next 10 years? What new technologies will alter the technology landscape? What are the opportunities going forward, and how do we prepare? How can materials research and development help us to move forward faster?
Materials Matter in Microfluidic Devices
Authors: Zhang Xunli , Haswell Stephen J.
Published: February 2011

As more micro- and nanofluidic methodologies are developed for a growing number of diverse applications, it becomes increasingly apparent that the choice of substrate material can have a profound effect on the eventual performance of a device. This is due mostly to the high surface-to-volume ratio that exists within such small structures. In addition to the obvious limitations related to the choice of solvent, operating temperatures, and pressure, the method of fluidic pumping—in particular, an electrokinetics-based methodology using a combination of electro-osmotic and electrophoresis flows—can further complicate material choice. These factors, however, are only part of the problem; once chemicals or biological materials (e.g., proteins or cells) are introduced into a microfluidic system, surface characteristics will have a profound influence on the activity of such components, which will subsequently influence their performance. This article reviews the common types of materials that are currently used to fabricate microfluidic devices and considers how these materials may influence the overall performance associated with chemical and biological processing. Consideration will also be given to the selection of materials and surface modifications that can aid in exploiting the high surface properties to enhance process performance.
Data-Mining-Driven Quantum Mechanics for the Prediction of Structure
Authors: Ceder G. , Morgan D. , Fischer C. , Tibbetts K. , Curtarolo S.
Published: February 2011

The prediction of crystal structure is a key outstanding problem in materials science and one that is fundamental to computational materials design. We argue that by combining the predictive accuracy of quantum mechanics with data mining tools to extract knowledge from a large body of historical experimental or computational results, this problem can be successfully addressed.
Electronic-Structure-Based Design of Ordered Alloys
Authors: Bligaard Thomas , Andersson Martin P. , Jacobsen Karsten W. , Skriver Hans L. , Christensen Claus H. , Nørskov Jens K.
Published: February 2011

We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational design of other materials as well. A central problem is how to treat the huge number of compounds that can be envisioned by varying the concentrations and the number of the elements involved. We discuss various strategies for approaching this problem and show how one strategy has led to the computational discovery of a promising catalytic metal alloy surface with high reactivity and low cost.
Engineering Materials Informatics
Authors: Cebon D. , Ashby M.F.
Published: February 2011

This article discusses the need for materials data and materials data management software during product development. Key issues are the changing materials data needs (from general to specific) as the design process proceeds, as well as the requirements for software systems that can automate the key data management tasks: capture, analysis, deployment, and maintenance. Specific issues requiring attention are flexibility of data management, change control, version control, quality control, and traceability of information.
Paradigm Shift in Data Content and Informatics Infrastructure Required for Generalized Constitutive Modeling of Materials Behavior
Authors: Arnold S.M.
Published: February 2011

Materials property information such as composition and thermophysical/mechanical properties abound in the literature. Oftentimes, however, the corresponding response curves from which these data are determined are missing or at the very least difficult to retrieve. Further, the paradigm for collecting materials property information has historically centered on (1) properties for materials comparison/selection purposes and (2) input requirements for conventional design/analysis methods. However, just as not all materials are alike or equal, neither are all constitutive models (and thus design/analysis methods) equal; each model typically has its own specific and often unique required materials parameters, some directly measurable and others indirectly measurable. Therefore, the type and extent of materials information routinely collected is not always sufficient to meet the current, much less future, needs of the materials modeling community.

Informatics has been defined as the science concerned with gathering, manipulating, storing, retrieving, and classifying recorded information. A key aspect of informatics is its focus on understanding problems and applying information technology as needed to address those problems. The primary objective of this article is to highlight the need for a paradigm shift in materials data collection, analysis, and dissemination so as to maximize the impact on both practitioners and researchers. Our hope is to identify and articulate what constitutes “sufficient” data content (i.e., quality and quantity) for developing, characterizing, and validating sophisticated nonlinear time- and history-dependent (hereditary) constitutive models. Likewise, the informatics infrastructure required for handling the potentially massive amounts of materials data will be discussed.
Materials Aspects in Micro- and Nanofluidic Systems Applied to Biology
Authors: Bakajin Olgica , Fountain Eric , Morton Keith , Chou Stephen Y. , Sturm James C. , Austin Robert H.
Published: February 2011

One of the key problems in microfabrication and especially nanofabrication applied to biology is materials selection. Proper materials must have mechanical stability and the ability to hermetically bond to other surfaces, yet not bind biological molecules. They must also be wettable by water and have good optical properties. In this article, we review some of the attempts to find materials for micro- and nanofluidic systems in biological applications that satisfy these rather conflicting constraints.We discuss the materials properties that make poly (dimethylsiloxane) or non-elastomeric materials more or less suitable for particular applications in biology. We also explore the effects and the importance of surface treatments for integrating biological objects into microfabricated and nanofabricated fluidic devices.
The Development of Polymeric Devices as Dielectrophoretic Separators and Concentrators
Authors: Simmons Blake A. , McGraw Gregory J. , Davalos Rafael V. , Fiechtner Gregory J. , Fintschenko Yolanda , Cummings Eric B.
Published: February 2011

Efficient and reliable particle separators and concentrators are needed to support a wide range of analytical functions including pathogen detection, sample preparation, high-throughput particle sorting, and biomedical diagnostics. The advent of lab-on-a-chip devices based on the phenomenon of dielectrophoresis offers advantages that can meet several of the challenges associated with cell sorting and detection. The majority of the devices presented in the scientific literature have used glass-based devices for these applications, but there has been recent activity that indicates that polymer-based devices can operate as effectively as their glass progenitors. Processing and operational advantages motivate the transition from glass and silicon to polymer microdevices: mechanical robustness, economy of scale, ease of thermoforming and mass manufacturing, and the availability of numerous innate chemical polymer compositions for tailoring performance. We present here a summary of the developments toward, and results obtained from, these polymeric dielectrophoretic devices in the selective trapping, concentration, and gated release of a range of biological organisms and particles.
Aspects of Thin-Film Superlattice Thermoelectric Materials, Devices, and Applications
Authors: Böttner Harald , Chen Gang , Venkatasubramanian Rama
Published: February 2011

Superlattices consist of alternating thin layers of different materials stacked periodically.The lattice mismatch and electronic potential differences at the interfaces and resulting phononand electron interface scattering and band structure modifications can be exploited to reduce phonon heat conduction while maintaining or enhancing the electron transport.This article focuses on a range of materials used in superlattice form to improve the thermoelectric figure of merit.
Thermoelectric Materials for Space and Automotive Power Generation
Authors: Yang Jihui , Caillat Thierry
Published: February 2011

Historically, thermoelectric technology has only occupied niche areas, such as the radioisotope thermoelectric generators for NASA's spacecrafts, where the low cooling coefficient of performance (COP) and energy-conversion efficiency are outweighed by the application requirements.Recent materials advances and an increasing awareness of energy and environmental conservation issues have rekindled prospects for automotive and other applications of thermoelectric materials.This article reviews thermoelectric energy-conversion technology for radioisotope space power systems and several proposed applications of thermoelectric waste-heat recovery devices in the automotive industry.
Up Close: Nanoscale Science Research Centers
Authors: Phillips Julia M.
Published: February 2011

Nanoscience has, in many ways, grown up in parallel with the Materials Research Society. Although “nanoscience” and “nanotechnology” are buzzwords that were “discovered” in Washington, D.C., and in the capitals of countries around the world a number of years ago, nanoscience has actually been developing for several decades. The emergence of nanoscience as a fascinating and fruitful area of research has occurred primarily for two reasons: (1) materials have new and unpredictable properties at the nanoscale; and (2) it is now possible to make things controllably on the nanoscale and to see them.
Materials Issues in Blue Recording
Authors: Kuiper A.E.T. , van Pieterson L.
Published: February 2011

In the development of materials for blue recording, the issues for rewritable discs relate to speed and lifetime stability. Both aspects are connected with the properties of the phase-change recording layer. Higher data rates require faster erasure (i.e., recrystallization) of previously written marks. Increasing the Sb concentration or adding specific dopants to the phase-change material appears to accelerate the crystallization rate. Faster erasure rates should, however, not promote spontaneous recrystallization at room temperature, as this would adversely affect the lifetime stability. This roomtemperature stability can be estimated from an activation energy analysis. Excellent lifetime stability proves attainable by a judicious selection of the composition of the phase-change material.

For write-once discs, the choice of the recording material is between a spin-coated dye, a phase-change layer, and an inorganic alloy. While suitable dye materials for blue wavelengths are now being developed, research into the alternative of inorganic bilayers has yielded encouraging results. Thus far, good write-once recording performance has been demonstrated with Cu/Si as the recording medium.The mechanism of mark formation in such a bilayer will be addressed. Promising results obtained with optimized Cu/Si stacks illustrate the attractiveness of this type of write-once material for blue recording.
Materials for Magneto-Optical Recording
Authors: Kaneko Masahiko
Published: February 2011

This article describes the characteristics and development of materials for magnetooptical (MO) recording. Magneto-optical recording is derived from thermomagnetic recording and readout by the magneto-optical effect. Rare-earth/transition-metal alloys, mostly Tb-Fe-Co, have been used for recording materials in MO discs. MO discs were first put on the market in 1988. Magnetic-field modulation for recording was introduced in MiniDisc (MD) systems in 1992. MO discs have an advantage in durability and achievability, because recording by magnetization reversal is not accompanied by any atomic movement. Magnetically induced super-resolution (MSR), reported in 1991, enabled resolving powers that are higher than the optical limit. MO discs based on MSR were commercialized as 3.5–in. discs for data recording and as 2–in. discs for digital cameras.

As extensions of MSR, DWDD (domain-wall displacement detection) and MAMMOS (magnetic amplifying magneto-optical system) have been proposed, in which the marks are expanded during readout for a large signal. DWDD technology has been used in Hi-MDs (high-density MiniDiscs), which were commercialized in 2004 with storage capacities of 1 Gbyte per 64-mm-diameter disc.
The Role of Standards in Optical Recording Media
Authors: Glinka Werner
Published: February 2011

Recordable CDs and DVDs have become household items, and business depends on optical recording technologies for data interchange and archiving. This broad use of optical recording media has been enabled by the development of compatibility standards. Compliance with these standards enables data interchange between products from different manufacturers and between products of different vintages.

This article will discuss what optical recording standards are and describe the standard development organizations that exist to create them. Further, it will provide an overview of the most common standards development process for removable optical recording media. The article will conclude with a discussion of how optical recording media standards enable asset protection and how new optical recording media standards meet the market demand for higher capacities.
Automotive Materials: Technology Trends and Challenges in the 21st Century
Authors: Taub Alan I.
Published: February 2011

The following article is an edited transcript based on the plenary talk given by Alan I. Taub of General Motors Corp. on November 28, 2005, at the Materials Research Society Fall Meeting in Boston.

Fuel economy requirements, emissions regulations, and the push for energy independence are key factors driving the auto industry to increase vehicle efficiency. The main avenues to efficiency improvement are powertrain enhancements and mass reduction. This presentation details how General Motors is developing advanced propulsion systems and using lightweight materials to achieve greater vehicle efficiency. Taub, who is executive director of General Motors Research and Development, outlines GM's strategy for advancing propulsion technology, from improvements in the internalcombustion engine to hybridization to full vehicle electrification. He then describes the company's efforts to use lightweight materials such as aluminum and magnesium alloys, high-strength steels, and composites to reduce vehicle weight. Also highlighted is GM's success in employing novel materials in the development of advanced vehicle and powertrain systems to achieve additional efficiencies. One example is the application of smart materials, which enable new features and functions by way of mechamatronic solutions (the integration of smart materials with mechanical systems and electronics). Key technical hurdles that must be overcome to increase the use of these materials by the automotive industry are also discussed.
Materials for Magnetic Data Storage: The Ongoing Quest for Superior Magnetic Materials
Authors: Coufal Hans , Dhar Lisa , Mee C. Denis
Published: February 2011

From its inception until today, and for the foreseeable future, magnetic data storage on disks and tape has provided constantly increased storage density.This has required not only constant innovation, but also major breakthroughs in magnetic materials, both for the media and the read head. Today's disk and tape drives take advantage of novel nanoengineered composite magnetic materials and quantum mechanical processes.In this issue of MRS Bulletin, we present a number of review articles by some of the leaders in this rapidly moving field that highlight the key materials science accomplishments that have enabled the tremendous progress in hard disk drive and magnetic tape technologies.Individual articles describe the materials involved in state-of-the-art magnetic recording, advanced media for perpendicular magnetic recording, the materials challenges of achieving high performance in flexible media such as magnetic tape, the materials issues of read heads, and future avenues for magnetic storage beyond magnetic recording, such as nanowires and spintronics.
State-of-the-Art Magnetic Hard Disk Drives
Authors: McFadyen I.R. , Fullerton E.E. , Carey M.J.
Published: February 2011

Magnetic recording has progressed dramatically over the last 50 years, with an increase of almost eight orders of magnitude in the amount of information stored per unit area of disk space.Two key enablers of this progress have been the recording medium and the read-back head.This article reviews the current state of the art in multilayer thin-film longitudinal recording media and giant magnetoresistive (GMR) read heads, with particular emphasis on the nanostructured magnetic materials that are key to today's high-performance hard disk drives.
Media for Magnetic Recording Beyond 100 Gbit/in.2
Authors: Richter H.J. , Harkness S.D.
Published: February 2011

The requirements for media for high-density magnetic recording are reviewed, particularly with respect to the emerging technology of perpendicular magnetic recording.It is discussed in general how suitable properties of the recording films can be achieved in practice.Several approaches to extend the thermal limit of magnetic recording technology are outlined.
Materials for Multiphoton 3D Microfabrication
Authors: Marder Seth R. , Brédas Jean-Luc , Perry Joseph W.
Published: February 2011

Two-photon/multiphoton lithography (MPL) has emerged as a versatile technique for the fabrication of complex 3D polymeric, hybrid organic/inorganic, and metallic structures. This article reviews some recent advances in the development of molecules and materials that enable two-photon and multiphoton 3D micro- and nanofabrication. Materials that exhibit high sensitivity for the generation of reactive intermediates are described, as are various materials systems that enable functional devices to be made and in some cases enable structures to be replicated. The combination of advances illustrates the opportunities for MPL to have a significant impact in the areas of photonics, microelectromechanical systems, and biomedical technologies.
Bulk Metallic Glasses: At the Cutting Edge of Metals Research
Authors: Greer A. L. , Ma E.
Published: February 2011

Glassy alloys (metallic glasses) are currently the focus of intense research in the international metals community. Setting aside elevated-temperature applications, these amorphous metals have exciting potential for structural applications. When metallic glasses were first widely studied in the 1960s, the alloy compositions then known to be quenchable into the glassy state from the liquid required high cooling rates on the order of 106 K s−1 and were consequently restricted to thin sections. The current interest in metallic glasses has its origin mainly in the increasing range of compositions that can now be cast into glasses at much lower cooling rates, permitting minimum sections of 1 mm to 1 cm or even larger. These bulk metallic glasses (BMGs) are the focus of the articles in this issue of MRS Bulletin. Our goal is to illustrate the major materials issues for BMGs, from processing to structures to properties and from the fundamental science of glasses to viable industrial applications. We hope that the articles, in providing a snapshot of a rapidly moving field, show why BMGs are attracting such intense interest and serve to highlight some challenging issues awaiting resolution.
Thermodynamics and Kinetics of Bulk Metallic Glass
Authors: Busch R. , Schroers J. , Wang W. H.
Published: February 2011

Bulk metallic glasses (BMGs) are multicomponent alloys with typically three to five components with large atomic size mismatch and a composition close to a deep eutectic. Packing in BMG liquids is very dense, with a low content of free volume resulting in viscosities that are several orders of magnitude higher than in pure metal melts. The dense packing accomplished by structural and chemical atomic ordering also brings the BMG-forming liquid energetically and entropically closer to its corresponding crystalline state. These factors lead to slow crystallization kinetics and consequentially to high glass-forming ability. This article highlights the thermodynamic and kinetic properties of BMGs and their contributions to extraordinarily high glass-forming ability. Some possible links with mechanical properties are also suggested.
Structural Aspects of Metallic Glasses
Authors: Miracle Daniel B. , Egami Takeshi , Flores Katharine M. , Kelton Kenneth F.
Published: February 2011

A recent structural model reconciles apparently conflicting features of randomness, short-range order, and medium-range order that coexist in metallic glasses. In this efficient cluster packing model, short-range order can be described by efficiently packed solute-centered clusters, producing more than a dozen established atomic clusters, including icosahedra. The observed preference for icosahedral short-range order in metallic glasses is consistent with the theme of efficient atomic packing and is further favored by solvent-centered clusters. Driven by solute—solute avoidance, medium-range order results from the organization in space of overlapping, percolating (via connected pathways), quasi-equivalent clusters. Cubic-like and icosahedral-like organization of these clusters are consistent with measured medium-range order. New techniques such as fluctuation electron microscopy now provide more detailed experimental studies of medium-range order for comparison with model predictions. Microscopic free volume in the efficient cluster packing model is able to represent experimental and computational results, showing free volume complexes ranging from subatomic to atomic-level sizes. Free volume connects static structural models to dynamic processes such as diffusion and deformation. New approaches dealing with “free” and “anti-free” microscopic volume and coordinated atomic motion show promise for modeling the complex dynamics of structural relaxations such as the glass transition. Future work unifying static and dynamic structural views is suggested.
Porous and Foamed Amorphous Metals
Authors: Brothers Alan H. , Dunand David C.
Published: February 2011

This article reviews the state of the art in the field of porous amorphous metals by describing current processing techniques, mechanical properties, and potential applications. In addition to the reduction in density, the main benefit of introducing porosity in amorphous metals is the improvement in compressive ductility and energy absorption. This ductilizing effect is explained by: (1) shear-band interruption by individual pores at low porosities and (2) stable plastic bending of thin struts at higher porosities, with cellular amorphous metals displaying compressive ductilities of up to 80%.
Rheology and Ultrasonic Properties of Metallic Glass-Forming Liquids: A Potential Energy Landscape Perspective
Authors: Johnson William L. , Demetriou Marios D. , Harmon John S. , Lind Mary L. , Samwer Konrad
Published: February 2011

In the potential energy landscape theory of liquids, the energetic configurational landscape of a liquid is modeled using a potential energy function comprising a population of stable potential energy minima called inherent states, which represent the stable atomic configurations of the liquid. These configurations are separated by saddle points that represent barriers for configurational hopping between the inherent states. In this article, we survey recent progress in understanding metallic glass-forming liquids from a potential energy landscape perspective. Flow is modeled as activated hopping between inherent states across energy barriers that are assumed to be, on average, sinusoidal. This treatment gives rise to a functional relation between viscosity and isoconfigurational shear modulus, leading to rheological laws describing the Newtonian and non-Newtonian viscosity of metallic glass-forming liquids over a broad range of rheological behavior. High-frequency ultrasonic data gathered within the supercooled-liquid region are shown to correlate well with rheological data, thus confirming the validity of the proposed treatment. Variations in shear modulus induced either by thermal excitation or mechanical deformation can be correlated to variations in the measured stored enthalpy or equivalently to the configurational potential energy of the liquid. This shows that the elastic and rheological properties of a liquid or glass are uniquely related to the average potential energy of the occupied inherent states.
New Bulk Metallic Glasses for Applications as Magnetic-Sensing, Chemical, and Structural Materials
Authors: Inoue Akihisa , Nishiyama Nobuyuki
Published: February 2011

Since 1988, it has been demonstrated that metallic glasses can be made in bulk form with diameters larger than several millimeters. At present, several alloy systems with maximum diameters for glass formation exceeding 1 cm are known. As a result, Zr-, Ti-, Fe-, Co-, Ni-, and Cu-based bulk metallic glasses (BMGs) are already in use for magnetic-sensing, chemical, and structural applications. In this article, recently developed BMGs with critical diameters of more than 1 cm are summarized, and some of their industrial applications are reviewed.
The Symbiosis of Light and Matter: Laser-Engineered Materials for Photo-Functionality
Authors: Livingston F. E. , Helvajian H.
Published: February 2011

Current technology trends imply that further miniaturization and integration of systems are anticipated, and one approach to realizing the next generation of systems integration is the development of materials that are protean, or capable of taking on various properties; in essence, the materials properties can be selectively altered via laser excitation. The objective is that a common substrate material can be used for multiple functions. Laser direct-write material processing, because of its maskless patterning flexibility, is inherently suitable for producing localized changes in materials properties and thereby fabricating linked, integrated devices on a common substrate. The enabling of this new form of materials processing requires a light-activated protean material along with a scheme for the dynamic regulation of the laser energy for optimum laser processing on the scale of the laser spot size and for patterning speeds on the order of meters per second. The “protean material” concept and a high-fidelity laser amplitude-modulation scheme are the focus of this article.
The Collapse of the World Trade Center Towers: A Metallurgist's View
Authors: Gayle Frank W.
Published: February 2011

This article is based on an edited transcript of a presentation given by Frank W. Gayle (National Institute of Standards and Technology) on April 12, 2007, in Symposium X at the Materials Research Society Spring Meeting in San Francisco.

The NIST investigation of the World Trade Center disaster addressed many aspects of the catastrophe, from occupant egress to factors affecting the ability of the Twin Towers to remain standing after being hit by the airplanes, with the goal of gaining valuable information for future best practices in building materials, building design, and emergency response. The presentation addressed the structure of the towers, the analysis of the recovered steel, and special issues faced during the investigation. The probable collapse sequence for each of the towers was also discussed.
Importance of Nanosensors: Feynman's Vision and the Birth of Nanotechnology
Authors: Devreese Jozef T.
Published: February 2011

In his visionary 1959 lecture at Caltech, Richard P. Feynman foresaw the potential of the ability to manipulate matter at the atomic scale. In this article, adapted from Integrated Nanosensors, MRS Symposium Proceedings Volume 952E, edited by I.K. Schuller, Y. Bruynseraede, L.M. Lechuga, and E. Johnson (2007), Jozef T. Devreese (University of Antwerp) discusses implementations of Feynman's vision in the field of nanosensors and perspectives of its further development and applications.

Nanoparticles are unique tools as sensors. Particles with sizes at the nanoscale reveal physical properties that do not exist in bulk materials; these properties can operate well inside living cells. Nanosensors possess unique physical characteristics. Their sensitivity can be orders of magnitude better than that of conventional devices. Nanosensors possess such performance advantages as fast response and portability. State-of-the-art nanosensors are based on various advanced materials (quantum dots, nanoshells, nanopores, carbon nanotubes, etc.). Nanosensors furthermore allow for building an entirely new class of integrated devices that provide the elemental base for “intelligent sensors” capable of data processing, storage, and analysis. Advances can open unprecedented perspectives for the application of nanosensors in various fields, for example, as molecular-level diagnostic and treatment instruments in medicine and as networks of nanorobots for real-time monitoring of physiological parameters of a human body.