The use of microtomography to study the structure and especially the deformation modes of cellular solids is reviewed in this article. First, the technique is described in detail. Examples illustrating the power of the coupling of in situ deformation with three-dimensional (3D) imaging, drawn from the recent literature and the authors' own work, are then given. The most detailed example is the study of the deformation modes of several samples made of different aluminum foams. Four kinds of closed-cell foams were investigated, corresponding to different routes available today for their manufacture. The initial macrostructure was quantified using the 3D images combined with 3D granulometry, allowing retrieval of pertinent information about the cell size and the wall and strut thicknesses. The global behavior exhibited by the foams during the in situ compression experiments was shown to vary from one brand of material to another. Some of these variations can be explained by differences in the known microstructure and the measured macrostructure of the samples.

This article approaches single-event upset (SEU) problems from the standpoint of experimental nuclear physics, with a focus on certain neutron experiments and neutron data essential for SEU studies. A review is given of some research programs, both basic and applied, that are strongly motivated by SEU applications. Some specific examples are presented from the The (short for Theodor) Svedberg Laboratory (TSL) in Uppsala, Sweden: First, using the quasi-monoenergetic neutron beam, SEU cross sections (of chips) are measured over the neutron energy range of 20–150 MeV. Data from the same technology generation, in general, can be fitted into a simple curve. Second, the particle origins of SEUs are discussed from the framework of neutron–nucleus spallation reactions.

Although adhesives, particularly those based on epoxy resins, are finding increasing use in structural applications, their utilization at elevated temperature (>150°C) has been limited by their relatively poor thermal and thermo-oxidative stability. As a result, significant effort has been directed in recent years toward the development of polymers exhibiting increased thermal resistance. Although a wealth of research conducted over several decades has resulted in a myriad of polymer types exhibiting, in some cases, impressive high-temperature performance, many systems have demonstrated poor processability Thus, much emphasis has been placed on developing high-temperature performance while providing processability characteristics that are similar, if not identical, to epoxies. This article considers the various approaches that have been shown to offer such dual capabilities. In addition, the results of various studies undertaken to investigate the effects of elevated temperature on the strength and fatigue resistance of bonded joints are reported.

This article reviews the most recent progress in the development of Nb-silicide-based in situ composites for potential applications in turbine engines with service temperatures of up to 1350°C. These composites contain high-strength Nb silicides that are toughened by a ductile Nb solid solution. Preliminary composites were derived from binary Nb-Si alloys, while more recent systems are complex and are alloyed with Ti, Hf, W, B, Ge, Cr, and Al. Alloying schemes have been developed to achieve an excellent balance of room-temperature toughness, fatigue-crack-growth behavior, high-temperature creep performance, and oxidation resistance over a broad range of temperatures. Nb-silicide-based composites are described with emphasis on processing, microstructure, and performance. Nb silicide composites have been produced using a range of processing routes, including induction skull melting, investment casting, hot extrusion, and powder metallurgy methods. Nb silicide composite properties are also compared with those of Ni-based superalloys.

Based on the concept of a microliquid process, we have developed an organic electroluminescent display using conductive polymers, including light-emitting polymers. The technology of inkjet printing has progressed enough to be used for the microliquid process. First, we describe the process used to form a patterned thin film. This involves inkjet-related technologies, the self-patterning behavior of a microliquid on the substrate, and the drying process that defines the thickness profile and film properties. Some microliquid behaviors and related phenomena, along with properties of the resulting film, were identified as distinct from those coming from a macroscopic liquid, as a result of size effects. By fully utilizing these unique properties of microliquids, we have succeeded in fabricating color-pixel arrays by direct patterning of polymer solutions. As a result, an organic electroluminescent display with a vivid full-color image has been developed.

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

Ferromagnetic materials that have Curie temperatures above room temperature, crystal structures and lattice matching compatible with compound semiconductors, and high spin polarizations show great promise for integration with semiconductor spintronics. Heusler alloys have crystal structures (fcc) and lattice parameters similar to many compound semiconductors, high spin polarization at the Fermi level, and high Curie temperatures. These properties make them particularly attractive for injectors and detectors of spin-polarized currents. This review discusses the progress and issues related to integrating full and half Heusler alloys into ferromagnetic compound semiconductor heterostructures.

Current issues in the development of organic materials for photonic applications are reviewed. Organic light-emitting diodes, which are a main focus of industrial research at the moment, are given special emphasis. Other applications in optical communications technology, including organic solid-state lasers, optical switching devices, and data storage, are also covered.

Metallic foams have become an attractive research field both from a scientific viewpoint and the prospect of industrial applications. Various methods for making such foams are available. Some techniques start from specially prepared molten metals with adjusted viscosities. Such melts can be foamed by injecting gases or by adding gas-releasing blowing agents that decompose in situ, causing the formation of bubbles. Another method is to prepare supersaturated metal–gas systems under high pressure and initiate bubble formation by pressure and temperature control. Yet a further class of techniques begins with solid precursors containing a blowing agent. These can be prepared by mixing metal powders with a blowing agent, compacting the mix, and then foaming the compacted mix by melting. Alternatively, casting routes can be used to make such precursors. The unique properties of foams offer promise in a variety of applications ranging from lightweight construction and impact-energy absorption to various types of acoustic damping and thermal insulation.

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

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.

The following article is based on a presentation given as part of Symposium X—Frontiers of Materials Research on December 4, 2002, at the 2002 Materials Research Society Fall Meeting. The cinema is just over 100 years old. From the beginning of motion pictures in the mid-1890s, the materials used for films have been at the heart of cinema technology. The material first used was cellulose nitrate film—unrivaled in its mechanical, physical, and aesthetic qualities, and also dangerously flammable. In the 1950s, cellulose nitrate was replaced, for safety reasons, by cellulose triacetate. Today, polyester film is widely used; nevertheless, the fact remains that the majority of the world's film heritage exists on two main material formats, cellulose nitrate and cellulose triacetate, both of which decay over time. Film archivists are engaged in a race to save historic film footage from being lost forever. Digital technology, now widely used in cinema, does not resolve the issue of the long-term preservation of films because digital formats are still evolving. This article discusses the materials used in motion-picture technology over the years, the mechanisms active in film decomposition, and international efforts to preserve and restore historic films.

High-performance fibers, used in fabric applications ranging from bulletproof vests to trampolines, must have a sufficient number of chemical and physical bonds for transferring the stress along the fiber. To limit their deformation, the fibers should possess high stiffness and strength. Stiffness is brought about by the degree to which the chemical bonds are aligned along the fiber axis. In fiber-reinforced composites, the fibers are the load-bearing element in the structure, and they must adhere well to the matrix material. An ideal reinforcing fiber must have high tensile and compressive moduli, high tensile and compressive strength, high damage tolerance, low specific weight, good adhesion to the matrix materials, and good temperature resistance. This article reviews and compares the properties and behavior of novel high-performance fiber materials including polyethylene, aramid, polybenzobisoxazole, M5, and carbon fibers.

New candidate ferromagnetic semiconductors have recently been grown by doping semiconducting transition-metal oxides with magnetic impurities. Some of these exhibit ferromagnetism at and above room temperature. The critical question is why? In many cases, complex solid-state chemistry is involved in the synthesis and drives the resulting properties. The observation of room-temperature ferromagnetism in these materials must be accompanied by a careful identification of the phases and structures present in order to accurately identify the origin of the magnetism.

Historically, radiation-induced corruption of data in high-speed complementary metal oxide semiconductor designs has been limited to on-board static random-access memory in various memory caches. Successive generations of scaling, however, have resulted in capacitance reductions in key logic circuits, increasing their vulnerability to these “soft errors.” Charge delivered by radiation events now carries a substantial probability of inducing upsets, not only in bistable elements, but in logic evaluation circuits as well. This article introduces the reader to common logic-circuit topologies in high-speed microprocessors, radiation circuit response mechanisms that can compromise logic evaluation integrity, and existing techniques that mitigate this exposure.

SiC-matrix composites consist of ceramic fibers embedded in a silicon carbide matrix produced by gas-, liquid-, or solid-phase routes, yielding materials that differ in matrix crystallinity, residual porosity, and thermal properties. These composites can be highly engineered in terms of the nature of the reinforcement, the interphase used to control the fiber-matrix bonding, the matrix, and the seal coating used. SiC-matrix composites are refractory ceramics displaying outstanding mechanical and thermal properties at high temperature. Their durability in oxidizing atmospheres and under load exceeds 1000 h at temperatures of up to ∼1200°C. They have been used to fabricate different components of the hot zone of jet engines with significant weight savings and an increase in performance. This article reviews the state of the art in the processing, materials design, and properties of these composites as well as their applications in advanced jet engines.

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.

We present a process for manufacturing printable thin-film transistors (TFTs) that is based on solution processing and direct inkjet printing of polymer semiconductors, dielectrics, and conductors, as well as inorganic nanoparticle conductors. We show that the high device yield, uniformity, and resolution required for thin-film electronic applications can be achieved by using a substrate that contains a surface energy pattern to control the flow and spreading of inkjet droplets. This technique overcomes many of the limitations of current inkjet printing technology related to its limited droplet placement accuracy. We demonstrate the potential of this printing-based TFT manufacturing process with the fabrication of 50 dpi active-matrix, polymer dispersed liquid-crystal and Gyricon Smartpaper electronic paper displays.

This article gives an overview of current neutron-scattering facilities and illustrates the capabilities of third-generation sources that are now under development. The new science that is driving this development has been illustrated in the articles in this issue of MRS Bulletin and in a previous issue published in 1999 [MRS Bull.24 (12) (1999) p. 14]. The scale of these facilities is such that only three of them are envisaged worldwide, in the Asia Pacific region, Europe, and America. Two construction projects, the spallation neutron sources in the United States (SNS) and in Japan (J-PARC), are now well under way, while the European proposal for a spallation source (ESS) is still awaiting a decision to start construction.

This article reviews recent progress in the deposition of thick, adherent, cubic boron nitride (c-BN) films. Most of the previous work applied ion-assisted physical vapor deposition methods to deposit c-BN films. The ion impact was successful in nucleating c-BN crystallites, but it resulted in a very small crystallite size and introduced stress, which caused the delamination of films thicker than 100 nm. Recent efforts to reduce the stress and obtain thicker films are described. The limited success of these attempts motivated us to explore chemical vapor deposition methods based on fluorine chemistry. We review this work, detailing the success of depositing thick (>20 μ), stress-free, adherent films with a larger crystallite size and significantly better crystalline quality.