bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Temperature Oxidation of Stainless Steels
Authors: Colson J.C. , Larpin J.P. 
Published: August 2016

The first stainless steels, mainly low carbon chromium-iron alloys, have been known since the beginning of this century. These steels show good resistance against wet corrosion and high-temperature corrosion. This article focuses on high-temperature corrosion, with emphasis on gaseous sulfidizing and oxidizing environments. The discussion is limited to these two gases since corrosion involving halogen-and/or carbon-containing gases involves other specific processes. The behavior of binary and ternary alloys will be successively examined, then the role of minor elements will be considered.Fundamental Mechanisms of High-Temperature Corrosion of Stainless SteelUsually, a dry corrosion process results in the formation of corrosion products, giving a simple or complex oxide or sulfide scale on a metallic substrate, separating it from the aggressive gaseous environment and, consequently, acting as a protective barrier. Scale growth is controlled by the conductivity of the reaction products which are solid electrolytes. Generally, the mechanism of scale growth is governed by outward cation or inward anion diffusion processes. This is the basis of the model originally put forward by Wagner for a single metal and subsequently developed for alloys, and particularly, for stainless steels. This one-way point-defect diffusion process is responsible for the observed parabolic scaling kinetics characterized by a parabolic rate constantkp. This model is well described in the literature.In the case of stainless steels, formation of a protective scale is required; this is possible if the oxide or sulfide products have a low diffusivity to cations or anions due to a low density of point defects in the crystal lattice. The protective characteristics of the corrosion products may be experimentally determined by measurement of their electrical conductivity, although the scales should also be effective against short-circuit transport of ions, atoms, or molecules. The best barriers consist of oxides, such as Al2O3, SiO2, and Cr2O3.
Bentonite as a Backfill Material in a High-Level Waste Repository
Authors: Grauer Rolf 
Published: August 2016

The concept for the disposal of high-level radioactive waste (HLW) in Switzerland is illustrated in Figure 1: the waste, solidified in a borosilicate glass matrix, is encapsulated in a 25-cm-thick steel canister which has a minimum life expectancy of 1,000 years. After this time, the heat produced by90Sr and137Cs will have dissipated and the repository will have adjusted to the host rock ambient temperature of around 60°C.The steel canisters will be placed in horizontal tunnels, 3.7 m in diameter, at a depth of around 1,000 m in the granite of northern Switzerland, and the tunnels then backfilled. The backfill material, an important link in the chain of engineered and natural safety barriers, satisfies both physical/mechanical and chemical requirements. The most important of these are:• Low hydraulic conductivity compared to the host rock;• Good swelling properties to seal construction-caused joints and rock fractures;• Plasticity to absorb rock movements and to distribute pressure homogeneously;• Good retention of radionuclides; and• Stability over a period of at least 106 years.Economic aspects and availability should also be considered: each canister requires 88 tons of backfill material, or of the order of 250,000 metric tons for the planned repository.
Surfaces, Interfaces, and Changing Shapes in Multilayered Films
Authors: Josell Daniel , Spaepen Frans 
Published: August 2016

It is generally recognized that the capillary forces associated with internal and external interfaces affect both the shapes of liquid-vapor surfaces and wetting of a solid by a liquid. It is less commonly understood that the same phenomenology often applies equally well to solid-solid or solid-vapor interfaces.The fundamental quantity governing capillary phenomena is the excess free energy associated with a unit area of interface. The microscopic origin of this excess free energy is often intuitively simple to understand: the atoms at a free surface have “missing bonds”; a grain boundary contains “holes” and hence does not have the optimal electronic density; an incoherent interface contains dislocations that cost strain energy; and the ordering of a liquid near a solid-liquid interface causes a lowering of the entropy and hence an increase in the free energy. In what follows we shall show how this fundamental quantity determines the shape of increasingly complex bodies: spheres, wires, thin films, and multilayers composed of liquids or solids. Crystal anisotropy is not considered here; all interfaces and surfaces are assumed isotropic.Consideration of the equilibrium of a spherical drop of radius R with surface free energy γ shows that pressure inside the droplet is higher than outside. The difference is given by the well-known Laplace equation:This result can be obtained by equating work done against internal and external pressure during an infinitesimal change of radius with the work of creating a new surface.
In Situ EXAFS Study of the Photoexcited State and Defects in Chalcogenide Glasses
Authors: Kolobov Alexander V. , Oyanagi Hiroyuki , Tanaka Kazunobu 
Published: August 2016

Amorphous chalcogenides, of which selenium is the simplest representative, exhibit a number of unique properties such as the ability to undergo various transformations under the action of the bandgap light. On illumination, the absorption edge shifts to lower energies, and subsequent annealing near the glass-transition temperature leads to a recovery of the initial parameters as demonstrated in Figure 1. Such a photo-induced change could not be observed either in amorphous group IV semiconductors or a-As or in crystalline chalcogenides. A good review of the initial stage of these studies was made by de Neufville.Reversible photodarkening can also be observed in pure chalcogens, but this process can be achieved only at lower temperatures, which is understandable if one takes into account that the glass-transition temperature of selenium is just above room temperature. This result indicates that there is a correlation between the temperature at which photodarkening is annealed out and the flexibility of the glassy network.Reversible changes in the optical absorption are accompanied by (reversible) changes in electrical and photoelectric properties, volume, microhardness, glass-transition temperature, and dissolution rate in various solvents, to name a few. The totality of these changes has led investigators to the conclusion that the photoinduced changes in optical absorption are caused by changes in structure.
Application of Novel Biomaterials in Colloidal Drug Delivery Systems
Authors: Garnett M.C. , Stolnik S. , Dunn S.E. , Armstrong I. , Lin Wu , Schacht E. , Ferutti P. , Vert M. , Davies M.C. , Illum L. , Davis S.S. 
Published: August 2016

The development of biomaterials to treat, repair, or reconstruct the human body is an increasingly important component of materials research. Collaboration between materials researchers and their industrial and clinical partners is essential for the development of this complex field. To demonstrate the importance of these interactions, two articles in this issue focus on advances in biomaterials relating to the use of colloidal systems for transport, drug delivery, and other medical applications. These articles were coordinated by Dominique Muster (Université Louis Pasteur, Strasbourg) and Franz Burny (Hôpital Erasme, Brussels). The following is the second of these two articles.There are two important objectives in drug delivery research. The first is to maximize the effectiveness of drugs by increasing the amount of drug reaching the target tissue while sparing other tissues the deleterious effects of the drug. The second is to control the release of a drug, so that the period of optimal drug concentration in the target tissue is maximized. A numbe r of different Systems have been investigated to achieve these objectives, including soluble polymeric delivery Systems and a range of colloidal drug delivery forms such as liposomes, emulsions, micelles, microcapsules, microparticles, and nanoparticles. This article focuses on polymeric materials for the production of micro- or nanoparticle Systems for dru g delivery by injection, and their characterization and Performance in vivo.Colloidal particles have a number of advantages as drug delivery Systems; they are easy to prepare, have the potential for high drug loading, and release of the drug can be controlled. However, without surface modification, colloidal particles are difficult to target because they are directed largely to the liver and spieen after intravenous injection. The reasons for this can be found in the context of the body's defenses. In order to protect against disease, the body has a complex System to ensure that invading microorganisms are identified and neutralized at the earliest possible opportunity. Most parasitic or invading organisms which pose a threat are particulate in form, and thus any colloidal drug delivery System will have to evade detection by these mechanisms in order to reach its target.
Photonic Applications of Rare-Earth-Doped Materials
Authors: Steckl Andrew J. , Zavada John M. 
Published: August 2016

The elements of the lanthanide series, from Ce (atomic number 58) to Yb (atomic number 70), form a group of chemically similar elements that have in common a partially filled 4f shell. These so-called “rare earth” (RE) elements usually take on a 3+ ionic state (RE3+). Because the 4f electronic-energy levels of each lanthanide ion are shielded from external fields by 5s2 and 5p6 outer-shell electrons, RE3+ energy levels are predominantly independent of their surroundings.The characteristic energy levels of 4f electrons of the trivalent RE elements have been investigated in detail by Gerhard Heinrich Dieke and co-workers and were reported approximately 30 years ago. The Dieke diagram showing RE3+ energy levels is a familiar tool of scientists and engineers working with RE elements. However, the history of RE elements goes back to the year 1787 in the small Swedish town of Ytterby near Stockholm and to the gifted amateur mineralogist and military man Lt. Carl Axel Arrhenius. Arrhenius discovered an unusual black mineral in Ytterby (perceived initially as much rarer in occurrence and in concentration than the common ores or earths of aluminum, calcium, etc.). Many new elements were discovered by various chemists upon analysis of this black stone and others like it. The names given to these elements are variations of the location where the first discovery was made: yttrium, ytterbium, terbium, and erbium. The history of RE elements is fascinating and involves many other famous names in science: Berzelius, Gadolin, Bunsen.The properties of these elements and their multifaceted applications to science and industry are equally fascinating and have remained important to this day. Commercial applications of RE elements began after World War II, when their available quantity and purity were greatly enhanced by improved separation techniques developed as a part of the Manhattan Project. Until fairly recently, the main industrial application of RE elements has been in permanent magnets. The unpaired 4f electrons result in some RE elements having the highest magnetic moments of any element. The development and applications of RE magnets are reviewed in a very interesting article by Livingston3 in a previous MRS Bulletin issue. In this issue of MRS Bulletin, we have taken as our aim to review some of the properties and applications of RE elements relevant to photonics.
Antisite Defects and Nonequilibrium Phase Transition in Intermetallics
Authors: Martin G. , Bellon P. 
Published: August 2016

Among the many point defects in crystalline solids, antisite defects play a key role in the stability of intermetallics. Such defects are either thermal equilibrium defects or are introduced by some external forcing.There are, indeed, many examples where intermetallics or compound semiconductors are “driven,” i.e., sustained in nonequilibrium configurations by external forcing. Good examples include the following:∎ Intermetallics in alloys under irradiation, like FeZr2 in Zircalloy used as a cladding material in pressurized water nuclear reactors, or any of the compounds produced by ion implantation or ion beam mixing (atoms are continuously forced to change lattice sites because of replacement collsions). See, for example, Reference 1.∎ Intermetallics in superalloys under cyclic fatigue (γ′ precipitates in persistent slip bands undergo sustained shearing, and sometimes redissolves).∎ Intermetallics during high-energy ball milling, a promising technique to stabilize nonequilibrium phases.∎ Ordered compounds when formed by vapor phase deposition.In such compounds, atoms are forced to leave their optimum local surroundings by nuclear collisions, shearing, fracturing, and welding respectively, or land on a surface at a random position, while thermal jumps tend to restore some degree of local atomic order. For simplicity, we call such compounds “driven systems” or “driven intermetallics.” Indeed, such systems are driven away from the usual thermodynamic equilibrium by a permanent dynamical forcing (nuclear collisions, plastic shear, etc.).
Bioceramics
Authors: Hench Larry L. , Wilson June 
Published: August 2016

The innovative use of specially designed ceramics to repair and reconstruct diseased or damaged parts of the body has improved the quality of life, and in some cases the length of life, for thousands of people. Ceramics used for this purpose are termed “bioceramics” and can be single crystals (sapphire), polycrystalline (alumina or hydroxylapatite), glass (Bioglass®), glass-ceramics (Ceravital® or A/W glassceramic), or composites (stainless-steel fiber-reinforced Bioglass or polyethylene-hydroxylapatite).Ceramics and glasses have long been used in the health care industry for eye glasses, diagnostic instruments, chemical ware, thermometers, tissue culture flasks, and fiber optics for endoscopy. Insoluble porous glasses have been used as carriers for enzymes, antibodies, and antigens. Ceramics are also widely used in dentistry as restorative materials, gold porcelain crowns, glass-filled ionomer cements, and dentures.This review describes bioceramics used as implants to repair parts of the body, usually hard tissues such as bones or teeth, but also to replace heart valves. Dozens of ceramic compositions have been tested, but few have achieved human clinical application. Clinical success requires the simultaneous achievement of a stable interface with tissue and a match of the mechanical behavior of the implant with the tissue to be replaced.The mechanism of tissue attachment depends on the type of tissue response at the implant interface (Table I).
Elastic Anomalies in Superlattices
Authors: Schuller Ivan K. , Fartash A. , Grimsditch M. 
Published: August 2016

The presence and origin of elastic anomalies in superlattices, interfaces, composites, and nanocrystalline materials has been a subject of much interest and controversy in recent years. In particular, superlattices are being used as model systems to study the effect of interfaces on the mechanical properties of novel materials. Early claims of anomalously large enhancements of the biaxial and flexural moduli of Au/Ni and Cu/Ni superlattices (“supermodulus effect”) created considerable controversy and contradictory reports in the experimental and theoretical literature. To understand the mechanical properties of superlattices and their implication for other types of nanofabricated materials, it is important to look critically at the field.Superlattices have been fabricated in different laboratories by a variety of preparation methods and have been characterized structurally and elastically to various degrees. Because of this, before addressing any sophisticated theoretical issues regarding elastic anomalies, it is important to understand in detail the experimental techniques and the possible pitfalls in the experimental determination of mechanical properties of thin films. Once the presence or absence of the effect is ascertained, the need arises to understand any possible experimental correlations with other structural and/or physical properties. These correlations can be used to address issues regarding the possible origins of the effect and their theoretical basis. It will be apparent from this article that slight changes in structural properties are correlated with relatively large elastic anomalies. Consequently, this points to the importance of precise, comprehensive, and detailed structural characterization. With our present understanding of the physics of superlattices, qualitative studies are no longer sufficient!
Effects of Atomic-Level Disorder at Solid Interfaces
Authors: Phillpot Simon R. , Wolf Dieter , Yip Sidney 
Published: August 2016

The importance of interface materials is based largely on their inherent inhomogeneity, i.e., that the chemical composition and physical properties at or near an interface can differ dramatically from those of the nearby bulk material. For example, the propagation of a crack along an interface — rather than through the surrounding bulk material — indicates a different mechanical strength near the interface. Also, the elastic response and thermal behavior near an interface can be highly anisotropic in an otherwise isotropic material, and can differ by orders of magnitude from those of the adjacent bulk regions. Typically, these gradients extend over only a few atomic distances.Because relatively few atoms control the properties in the interfacial region, the inherent difficulty in the experimental investigation of buried interfaces is actually an advantage in the atomic-level study of solid interfaces by means of computer-simulation techniques. While the limitations of such simulations are well known, this article will attempt to demonstrate the unique insights they can provide on some aspects of the mechanical behavior of both buried and thin-film interfaces. While to date, relatively little simulation work has focused directly on the observation of crack extension, we will discuss two types of phenomena with particular relevance in the fracture behavior of interface materials, namely their elastic and high-temperature properties. We will conclude with an outlook, too optimistic perhaps, on how the complementary capabilities of continuum-elastic theory, atomic-level computer simulation, and experiment could (and probably should) be combined in a new strategy for tackling the difficult problem of interface fracture to elucidate the underlying complex interplay between elasticity, plasticity, and temperature.
Fine Particles Part II: Formation Mechanisms and Applications
Authors: Matijević Egon 
Published: August 2016

The original intention was to publish one special issue on the materials science of fine particles. As a Guest Editor, I approached a number of specialists with specific interests in this field, soliciting contributions. Normally, an editor expects a number of requests to be declined. In this particular instance the response was overwhelming, which indicated both the enthusiasm of the people active in fine particle science and the timeliness of the topics. Thus, the MRS BULLETIN decided to dedicate two issues to this subject, December 1989 and January 1990.The December 1989 issue dealt essentially with the procedures and principles for preparing finely dispersed matter consisting of particles of different chemical composition, shape, and size. This issue treats the problems of the mechanisms of formation of well-defined dispersions and offers examples of applications in two areas — ceramics and adhesion. Only the limitations in space prevented the editor from including other topics relevant to fine particle science and technology, which are both fascinating and useful.
Chemical Synthesis of Fine Powders
Authors: Livage J. , Henry M. , Jolivet J.P. , Sanchez C. 
Published: August 2016

Interest in the synthesis of submicron monodispersed powders is increasing. Such powders find applications in the ceramic industry when high performance materials are required. Sintering time and temperature can be significantly reduced with powders of narrow particle-size distribution. Fine colloidal particles can be made by a variety of methods, from the vapor phase or the liquid phase.The sol gel process offers new approaches to the synthesis of fine powders. Starting from molecular precursors, such as metal alkoxides or aqueous solutions, an oxide network is obtained via inorganic polymerization reactions. These reactions occur in solution, and the term “sol-gel processing” is often used to describe the synthesis of inorganic oxides by wet chemical methods. It offers many advantages compared to the conventional powder route. One unique advantage is the ability to go all the way from the molecular precursor to the solid material, permitting better control of the entire process and allowing synthesis of “tailor-made” powders.
Behavior of Block Copolymers in Thin Films
Authors: Russell T.P. , Deline V.R. , Wakharkar V.S. , Coulon G. 
Published: August 2016

The uses of polymeric materials in today's world are vast. Polymers are finding applications in the microelectronics industry as dielectric insulators and photoresists, in the aerospace and automobile industry as lightweight substitutes for metals, and in biotechnology as replacement components for bone, heart, and other organs. These are just a few of the many end uses of polymers.Often, a polymer may have a particular, desirable property but processing of the polymer is difficult or the polymer's surface characteristics are undesirable. To circumvent such shortcomings there are several options. The first is to synthesize a new material, which is quite costly and time consuming. Alternatively, two polymers with complimentary properties can be mixed. Unfortunately, most polymer pairs are immiscible unless there are specific interactions (e.g., hydrogen bonding) between the two components. Consequently, coarse phase separation is often observed, leading to an ill-defined material. Finally, two chemically distinct homopolymers can be joined together at one point, forming a block copolymer. While phase separation may occur, the scale of the domains is restricted to the sizes of the individual homopolymers, which is typically on the tens of nanometers scale. The added advantage of this approach is that the size of the different blocks can be altered, varying the concentration of the different components. For copolymers that “microphase” separate, this variation in composition leads to a variation of the morphology of the microdomains ranging from spherical to cylindrical to lamellar.