bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of Glasses of Geological Interest: Applying Spectroscopic Techniques
Authors: Hawthorne Frank C. 
Published: August 2016

Glasses are a minor fraction of Earth materials. However, all igneous processes within the Earth involve a melt phase (magma), and our understanding of the physical and chemical features of these processes is contingent upon an adequate understanding of the melt phase itself. In particular, we wish to relate the behavior of such melts to their composition and structure in the range of physical and chemical conditions in which they occur. The physical conditions of many of these processes are particularly difficult to reproduce in the laboratory, and the ability to predict behavior under such conditions is the goal. From a geological viewpoint, the primary interest is in silicate melts because of the composition of the Earth's lithosphere and mantle. There are significant experimental difficulties in looking at the behavior of silicate melts, so much work has focused on glasses as melt analogues since spectroscopic data on silicate glasses and melts (Figure 1) are similar.Silicate glasses are also of considerable industrial interest, and early work in the geological field borrowed heavily from materials science. However, the thrust to understand natural magmas led geologically based work into more complex chemical systems (e.g., hydrous alkali-alkaline-earth-aluminosilicates) and their behavior at high pressures.The structure of glasses is a complex issue, and many different experimental techniques are needed to resolve the details of their structure. Here I will focus on the following techniques: IR (infrared), Raman, Mössbauer, EXAFS (extended x-ray absorption fine structure) and XANES (x-ray absorption near-edge spectroscopy) spectroscopies.
Thin Film Processing of Complex Multilayer Structures of High-Temperature Superconductors
Authors: Ono Ronald H. 
Published: August 2016

The realization of a revolutionary generation of electronics based on high-temperature superconductors (HTS) crucially depends on the ability to make high-quality thin film microstructures. These will incorporate materials such as YBa2Cu3O7-δ (YBCO), TlBaCaCuO, or BiSrCaCuO in a fashion similar to the circuits and devices made of their low Tc counterparts Nb or NbN. Without exception, the most valuable structures will be composed of multiple layers of superconducting films and dielectrics, in some cases combined with normal metals, low-temperature superconductors, or a variety of semiconductors. Generically, these can be combined in two ways: in a hybrid design where specialized packages and bonding are used to attach dissimilar materials, or in a monolithic thin film structure such as the one seen in Figure 1.The division between hybrid and monolithic multilayers results from the historical development of electronic circuits. Hybrid designs typically require linewidths and alignment accuracy somewhat less demanding than those used in fully integrated circuits. The advantage of hybrid construction is the separation of incompatible processing steps onto different substrates or die. The monolithic integrated circuit, whether microelectronic, millimeter wave, or radio frequency, can be made in large batches with concomitant economy of scale and can be fabricated with fewer parasitic constraints. Superconducting integrated circuits have followed the semiconductor pattern of being developed in a hybrid fashion, then transferred to a fully integrated process.
Art and Technology
Authors: Vandiver Pamela , Druzik Jim 
Published: August 2016

Art has as many meanings as contexts in which it operates. It can mean surface decoration or the integral sum of parts and whole which a historian analyzes as structure using visual, musical, theatrical or other criteria. Art serves as decoration, but also serves to signal or sign a particular meaning. Art often confers an elite social status on its patrons or provides goods which support the power and prestige of a special group or person. Art is also used to describe the experience of viewers, usually as “aesthetic experience”; for instance, we experience art as beauty, as a shared emotional experience or empathetic understanding, or as interactive play or a process of performance by which we investigate or relate ideas, occurrences, or objects and give them meaning.Technology, in contrast, is usually defined as “praxis” and involves doing things, as a craft practice involving materials selection and refinement, followed by making those materials into useful things, artifacts, or objects which serve useful functions for individuals, a social group, class, or culture. The products of technology can be useful as tools that enable a task to be accomplished, or as products which satisfy subsistence needs, or devices, or even practical ideas. When put to use, they enable travel, communication, transportation of goods, or control of energy. But technology has another meaning which is often thought to be less useful, namely technical marvels—things which amaze or surprise us. Some examples are the mechanical automatons of the 17th and 18th centuries, the latest computer game, a special way of hearing or seeing, or even the gas and light spewing magic machines described as being used in Greek temples to get peoples' attention. Another example is the technology described by the 11th century monk Theophilus, used to equip a church, from bells and censors, to glass windows and painted walls. In these examples, doing technology or learning to use technological marvels is a way of almost magically extending our own power and understanding beyond ourselves.
AMS Radiocarbon Dating: Its Current and Future Role in Art Research
Authors: Stulik D.C. , Donahue D.J. 
Published: August 2016

Since the development of14C dating by W.F. Libby in the 1940s and 1950s, the method has proved to be the best absolute method for chronometric dating of organic and some carbon-containing inorganic materials. It has become an essential research tool for both archaeologists and geologists. Even broader application horizons have been opened to radiocarbon dating by use of the accelerator mass spectrometer, which allows routine analysis of submilligram samples. Art curatorship and art conservation directly benefit from this development.There are pronounced similarities between application of radiocarbon dating in archaeology and art research but there are also major differences which make it difficult to simply take a methodology developed for archaeological research and apply it directly to radiocarbon dating of art objects.In both fields the application of dating techniques focuses on dating an object of unknown age or cross-checking the age of an object previously dated by other methods.
Fracture Behavior of Cement-Based Materials
Authors: Shah S.P. , Ouyang C. , Lange D.A. 
Published: August 2016

The characterization of fracture behavior is a continuing challenge to the cement and concrete community. The performance of a material can be evaluated by its stress-strain response. For an ideally brittle material, elastic response is terminated when stress suddenly drops to zero, as shown in Figure 1a. However, cement-based materials are considered quasi-brittle because they respond nonlinearly prior to peak stress, and their stress gradually decreases after reaching a peak, as indicated in Figure 1b.To make cement-based materials stronger and tougher, one needs to understand the fracture mechanisms associated with nonlinear stress-strain behavior and to characterize material fracture properties based on these fracture mechanisms. Three novel techniques are being used at the Center for Advanced Cement-Based Materials (ACBM) to detect the quasi-brittle nature of cement-based materials. These three techniques are laser holographic interferometry, acoustic emission, and microscopic surface analysis. This article summarizes both the fracture mechanisms in cement-based materials and the application of the three techniques to characterize and measure fracture properties.
In Situ Ellipsometry in Microelectronics
Authors: Irene E.A. , Woollam J.A. 
Published: August 2016

Ellipsometry has been used in microelectronics since the early 1960s when it became necessary to measure the thickness of transparent films on reflective substrates. Ellipsometry is an old technique but with the increasing technological importance of thin films, particularly in microelectronics, and with the availability of faster computers for calculations, ellipsometry is in a renaissance. In principle it is a simple technique (don't confuse simple with easy!) that relies primarily on the physical optics of stratified media. Excellent treatments of ellipsometry exist (e.g., a book, recent reviews), and it is not the intent here to try to improve upon them. Rather, this article is intended to briefly discuss the essential ideas and then to show a few examples of in situ ellipsometry applied to modern materials-research problems. The emphasis here is on in situ ellipsometry, because it is one of the few techniques that can accurately monitor thin-film processes while they occur, yielding both fundamental properties and process information about the system under measurement. In addition it is now possible to use feedback to affect control of thickness, composition, and temperature, for example.We first consider some basic questions: What is ellipsometry, what does it measure, and how well? Next, we discuss hardware for in situ ellipsometry, and finally we show a few examples.
Analysis of Growing Films of Complex Oxides by RHEED
Authors: Bozovic Ivan , Eckstein J.N. 
Published: August 2016

The majority of sophisticated ultra-high-vacuum (UHV) systems for deposition of thin films, such as molecular beam epitaxy (MBE) machines, contain some kind of electron diffraction apparatus which is used to scrutinize the surface structure of the film while it is grown. Reflection high energy electron diffraction (RHEED) is probably the most frequently employed configuration. An excellent introduction to RHEED, including a treatment of electron diffraction, reciprocal-space description, reflection from imperfect surfaces, etc., was recently published in the MRS Bulletin by Lagally and Savage. Hence, we will not review these basics here. Rather, we will assume the reader to be familiar with that article, and will refer to it as LS.The materials discussed in LS include Si, Ge on Si, and GaAs. The applications of MBE for synthesis of semiconductor thin films and heterostructures are widely recognized. MRS has recently bestowed its greatest honor, the Von Hippel Award, to Alfred Y. Cho for his pioneering work on MBE synthesis of GaAs and its application to new devices.In contrast, here we focus on complex oxides—cuprates, titanates, manganates, etc. This is a relatively new area of application for both MBE and RHEED. Actually, it was only after the discovery of high-temperature superconductivity (HTS) that many MBE systems were designed and built specifically for metallic oxide deposition. More recently, some of these machines have also been employed to synthesize other interesting oxides, for example, ferroelectrics and ferromagnets. In all these studies, RHEED has been the principal diagnostic tool and source of information about the growing film surface.
Biomaterials: New Polymers and Novel Applications
Authors: Langer Robert 
Published: August 2016

The following is an edited transcript of the plenary lecture presented by Robert Langer at the 1995 MRS Spring Meeting on April 17, 1995 in San Francisco.Over the last 21 years I have been involved in examining and studying, and in some cases synthesizing new polymers and biomaterials, looking at how they might be able to solve two problems. One set of problems involves drug delivery; a second involves creating new tissues.Controlled drug release is a relatively young field that has involved a fundamental change in the way drugs are delivered. Transdermal drug delivery, for example, uses five layers of polymers, yet the whole system is 0.2 mm thick. One such polymer contains nitroglycerine, which is slowly released for one day from a patch through the skin into the blood circulation. This process provided a novel way to treat angina for patients with chest pains. First introduced in 1982, such drug-delivery systems saw a usage rate of over 500 million last year.Norplant systems, which are silicone capsules placed under the forearm, slowly release a birth-control drug for over 2,000 days, or five years, from what are actually six small implants about the size of match sticks. These two examples illustrate that drugs can be made to slowly diffuse through polymers over a long period of time.
Surface Magnetism and Kerr Spectroscopy
Authors: Qiu Z.Q. , Bader S.D. 
Published: August 2016

Magneto-optic effects were first discovered in 1845 by Michael Faraday, but these effects continue to make a major impact on the materials community to this day. The need for new magnetic information-storage media has stimulated new approaches and opened new scientific opportunities in the exploration of thin-film and surface magnetism. This article provides background to some of these developments and highlights examples of contemporary issues that provide a focus for the field. In the Faraday effect, the polarization plane of linearly polarized light rotates when a magnetic field is applied in the propagation direction. The analogous phenomenon was subsequently discovered by the Rev. John Kerr in 1877 for light reflected from opaque materials. The works of Faraday and Kerr serve as cornerstones for our present understanding of magneto-optic effects in magnetic materials. Magnetooptics is presently described in the context of either microscopic quantum theory or macroscopic dielectric theory. Microscopically, the coupling between the electric field of the propagating light and the electron spin in a magnetic medium occurs through the spin-orbit interaction. Macroscopically, magneto-optic effects arise from the antisymmetric, off-diagonal elements in the dielectric tensor, as discussed in the next section.Magneto-optic characterizations of surface magnetism began only a decade ago. The first surface magneto-optic Kerr-effect study, better known by its acronym SMOKE, concerned the magnetichysteresis loops for ultrathin Fe films grown epitaxially on Au(100). Since then, SMOKE has emerged as a premier surface-magnetism technique. SMOKE has been applied to various topics in low-dimensional magnetism, ranging from the detection of magnetic order to the characterization of critical behavior, magnetic surface anisotropies, and the oscillatory antiferromagnetic coupling exhibited by giant-magnetoresistanceheterostructures. Additional interest in SMOKE has been generated by the recent commercialization of high-density, magneto-optic information-storage media, and especially by the next-generation candidate material based on Co/Pt superlattices.
Micromagnetic Modeling: Theory and Applications in Magnetic Thin Films
Authors: Zhu Jian-Gang 
Published: August 2016

Micromagnetic theory concerns detailed magnetization configurations and the magnetization-reversal processes in a ferromagnetic system. By combining the original micromagnetic theory with a dynamic description of magnetization orientations, one can simulate complete magnetization processes and calculate important properties such as magnetic hysteresis and magnetic switching dynamics. Not only can micromagnetic simulation predict complex magnetic-domain configurations in a ferromagnetic system, it also can generate transient pictures showing how a complex domain configuration forms. Very important among these systems are ferromagnetic thin films, particularly those used in sensors and recording devices. Micromagnetic modeling not only has enriched our understanding of existing magnetic films but has also been used to successfully predict the magnetic properties of new film microstructures created for particular applications.In this article, a brief introduction of micromagnetic-modeling theory will be given. Modeling of soft and hard magnetic films will be discussed separately through two examples illustrating the essence of micromagnetic-magnetization processes in these films.
Chemical Vapor Deposition of TiN for Sub-0.5 μm ULSI Circuits
Authors: Eizenberg M. 
Published: August 2016

Titanium nitride (TiN) has been recognized as an excellent barrier material in various metallization structures of advanced microelectronic devices. TiN serves as a nucleation/glue layer as well as a barrier against WF6 attack in W plug filling. It serves as a diffusion barrier during or after high-temperature Al reflow processing for contact and via filling. TiN is considered as a diffusion-barrier material for Cu metallization as well. In addition, it is utilized as an antireflection coating layer, especially on top of Al, an application that will not be discussed in this article.TiN films must conform to the extreme topographies used in devices in order to guarantee void-free plug formation as well as Jow junction leakage. This should be achieved with the thinnest films possible in order to reduce interconnect stack thickness and to lower contact or via resistance. (The TiN resistivity is higher than that of the other components of the metallization—Ti, Al, or W.) In addition, the good barrier properties must be retained following various thermal cycles used in multilevel metallization. Finally, the metallization must be manufacturing-worthy, namely, it should be reliable and reproducible, it should have a very low particle content, and it should have a low cost of ownership.At present, TiN is mainly deposited by physical vapor deposition (PVD) via reactive sputtering. However, the poor conformality of sputtered TiN films over extreme topography limits the use of this deposition technique for deep sub-0.5 μm applications, especially those with features that have high aspect ratios.
Swift, Heavy Ions in Insulating and Conducting Oxides: Tracks and Physical Properties
Authors: Provost J. , Simon Ch. , Hervieu M. , Groult D. , Hardy V. , Studer F. , Toulemonde M. 
Published: August 2016

Transition metal oxides belong to the class of iono-covalent materials in which electrons are, to first order, localized in tight metal-oxygen bonds. They appear to be quite different from classical metals in which electrons are assumed to be delocalized in a free electron gas. Nevertheless, due to exchange interactions and hybridization of atomic orbitals, oxides exhibit many interesting physical properties like magnetic ordering and various electron transport properties that extend from wide gap insulators to narrow band conductors and high-temperature superconducting (HTS) superconductors. This class of materials appears well-suited to the study of the damage induced by heavy ion irradiation and its consequence on physical properties like electrical resistivity.In this article, we will describe the results of heavy ion irradiations in magnetic oxides, exhibiting a wide palette of electron transport properties from insulators to metals through hopping semiconductors and in HTS copper oxides that are narrow-band metals aboveTc. We will show that heavy ion irradiation, in addition to disordering matter, can induce changes in some physical properties like magnetic ordering and orientation of magnetic fields, and can produce large increases of the critical current. To account for these results, the thermal spike model will be considered as a possible way to understand the damage creation in iono-covalent compounds.
Chemical Dynamics and Bond-Order Potentials
Authors: Brenner Donald W. 
Published: August 2016

Tremendous advances in computing speed, increasingly clever algorithms, and more accurate interatomic-force models have made atomistic simulation a powerful tool in many areas of materials science and engineering. Indeed, from traditional areas such as the study of grain boundaries, fracture, and point defects to somewhat less traditional areas such as nanometer-scale engineering and device fabrication, atomistic simulations are providing exciting new data and insights that cannot be obtained in any other way. Central to the success of an atomistic simulation is the use of an appropriate force model. For simulations requiring large systems and/or long times, the computational efficiency offered by classical potential-energy functions is necessary. However, obtaining quantitative results requires a model that can both accurately describe an appropriate database of physical properties and that is transferable to structures and dynamics beyond those to which it is fit. The latter property is especially critical if an atomistic simulation is to have useful predictive capabilities. While an extensive and well-chosen database from which parameters are determined is important, transferability ultimately depends on the chosen functional form. The definitive mathematical form, however, has yet to be developed.This article covers my attempts to develop classical potential-energy functions based on an empirical bond-order formalism that put qualitative and semiquantitative features of chemistry into large-scale condensed-phase simulations. To help explain this work, the next section gives a brief tutorial of the “chemistry” of few-body potentialenergy surfaces. Although familiar to chemists, the concepts discussed in this section may not be as familiar to mate rials scientists and engineers. A discussion of the bond-order formalism and how it can be related to both solid-state structure and chemical dynamics follows. The article ends with a discussion of two applications of this formalism, modeling chemical dynamics near a shock front and the reactive chemistry of diamond deposition.
Biocatalytic Synthesis of Polyesters Using Enzymes
Authors: Morrow Cary J. 
Published: August 2016

Plants and animals have been exploited as sources of materials for centuries but, as our ability to analyze and fractionate them has progressed, the extraordinary range of properties available from materials produced by living systems has continued to grow. Doi, in another article in this issue of theMRS Bulletin, presents a discussion of a group of naturally occurring polyesters related to poly(beta-hydroxybutyrate). These polyesters are formedin vivoby several microorganisms as part of an energy storage scheme. Research on these systems has allowed growth conditions to be found that can lead, in a controlled fashion, to a number of copolymers. Useful materials based on these bacterial polyesters appear to be at hand.Thein-vivoformation of polyesters in microorganisms also illustrates several of the important reasons for examining biocatalytic polymer synthesis. First, unlike most industrial syntheses of polyesters, the poly(beta-hydroxybutyrate) biosynthesis occurs at a near-ambient temperature using a carbohydrate feedstock. Second, and perhaps most importantly, the stored polyesters are readily biodegraded by the bacteria that manufacture them, so materials based on these polyesters should also be biodegradable. Third, although there are side chains along the polymer backbone, they are introduced in a highly stereo-specific fashion duringin-vivosynthesis, leading to an entirely stereoregular polyester. However, along with these advantages, there are also significant limitations to bacterial polyester synthesis. First, there are some substrates that are not incorporated into the polyester by the bacteria. Second, normal metabolism leads to the polyester, always incorporating a fraction of hydroxybutyrate monomers. Third, the backbone is always comprised of four-atom, A-B type 3-hydroxy acid repeat units with variations appearing in the side chain at carbon-3.