bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Processing Parameters on Stability of (SOG) Files on Patterned Si Wafers
Authors: Shyu S. G. , Smith T. J. , Baskaran S. , Buchanan R. C. 
Published: March 2011

ABSTRACTPolymeric sols of SiO2 or siloxane polymers in n-propanol were investigated for use as dielectric and planarization layers on patterned silicon wafers for device application. Spin coating of the sol (SOG) resulted in rapid gelation through solvent evaporation but cracking often occurred on heating. This study examined the influence of SOG composition, deposition process and heating rate on film planarization and cracking. Planarization was found to be enhanced by layer thickness, but cracking stability was reduced. Sequential drying of the applied SOG layers and use of trlethano-lamine as a complexing base was found to significantly reduce cracking tendency in the films.
Optimization of Sol-Gel Film Properties
Authors: Melpolder Sharon M. , K. Coltrain Bradley 
Published: March 2011

ABSTRACTThe preparation and characterization of organic-modified and organic/ iorganic-modified silica sol-gel spin-coated thin films is presented as a function of thermal processing. The ability to alter the film's final refractive index, thermal expansion coefficient and the polar contribution to the film's surface energetic term is reported. The stability of the coating solution at elevated temperatures was studied by analyzing changes in molecular weight, viscosity and particle size during the sol-to-gel transition. Control of the sol-gel thin film properties allows the design of a film/substrate interface where both thermal mismatches and surface energetic differences are minimized. Decreased stresses should be induced during processing, resulting in increased adhesion between the coating and the substrate.
The Instability of Polycrystalline Thin Films: Experiment and Theory
Authors: Miller K. T. , Lange F. F. , Marshall D. B. 
Published: March 2011

ABSTRACTDense polycrystalline thin films of ZrO2 (3 and 8 mol% Y2O3) were produced by the pyrolysis of zirconium acetate precursor films, which were deposited on single crystal Al2O3 substrates by spin-coating solutions of zirconium acetate. With grain growth, these films broke into islands of ZrO2 grains. Thermodynamic calculations show that this break up lowers the free energy of the system. These calculations also predict the conditions needed for polycrystalline thin film stability.
Chemical Ways to YBa2Cu3O7−x Superconducting Materials
Authors: Bernier J. C. , Vilminot S. , El Hadigui S. , His C. , Guille J. , Dupin T. , Barral R. , Bouzat G. 
Published: March 2011

ABSTRACTYBa2Cu3O7−x has been synthesized by two chemical ways, one from oxalate coprecipitation, the other one from metalloorganic decomposition. Superconducting properties of the resulting samples have been checked by means of resistivity and magnetic measurements. Low temperature specific heat data allow to propose an explanation to the residual linear term.
The Introduction of Roman Ceramic Styles and Techniques into Roman Britain: A Case Study from the King Harry Lane Cemetery, St. Albans, Hertfordshire
Authors: Freestone Ian C. , Rigby Val 
Published: March 2011

AbstractSpecialised ceramics from Gaul were imported into late Iron Age Britain, and their forms copied in native techniques. Roman technology was introduced after the Conquest, and involved changes in paste preparation, surface coating and firing techniques that allowed increases in the scale, standardisation and quality of the production.
A Study of Ancient Roof Tiles Found in Pella, Greece
Authors: Kilikoglou Vassilis , Vassilaki-Grimani M. , Maniatis Y. , Grimanis A. P. 
Published: March 2011

AbstractThe ceramic specimens examined in this study were taken from roof tiles of the Hellenistic period found in Pella, northern Greece. They represent five chronologically successive tilings of two buildings. Neutron activation analysis results showed that a different clay was used for the construction of each roof. Results of technological analysis indicate a consistency in the manufacture of the tiles, except for the first tiling which seems to be technologically different and more advanced.
Electron-Microprobe Investigation of Early Irish Glass and Glass-making Practices
Authors: Henderson Julian 
Published: March 2011

AbstractThis paper discusses the largest bank of compositional data yet assembled for Early Christian (6th- 10th century AD) Irish glass. The material studied was transparent and opaque and was analysed using EPMA and SEM. The data for transparent glass offers the possibility of assessing the extent to which the glass was recycled. The crystalline inclusions in opaque glasses including those on glass-making crucibles have been studied using an SEM.
An Analytical Investigation of a Durable Second Millennium BC Glass Bead from Britain
Authors: Henderson Julian 
Published: March 2011

AbstractThis paper deals with a unique glass bead of probable second millennium BC date from Wilsford, Wiltshire in southern England. The date of the bead is probably Wessex II; c. 1400 – 1200 BC. It was first recognised as being glass [1] in print in 1812, but until recently [2] has been considered as being of stone rather than glass in line with its original description. Here the bead is described together with surface SEM studies, the replication work on glass of similar composition reported and its unusual chemical composition discussed in terms of its durability and comparable Bronze Age glass compositions. This paper is partly the result of a collaborative project involving the author, Margaret Guido, Michael Cable, Justine Bayley and Leo Biek.
Bronze Age Cauldrons in Atlantic Europe: Materials Selection and Design
Authors: Northover J. Peter , Gerloff Sabine 
Published: March 2011

AbstractThe cauldrons and buckets of the later Bronze Age in Atlantic Europe, produced from the 12th to the 6th century BC, were some of the most complex fabrications made in that period of prehistory. They show a steadily increasing understanding of the problems posed by their design and an increasing elegance in their solution. At the same time they demonstrate considerable awareness of materials properties and provide one of the clearest instances in the Bronze Age of materials selection for specific purposes.
Changes in Waterlogged Medieval Window Glass
Authors: Alten Helen I. 
Published: March 2011

AbstractSamples of wet 13th-14th c. Grisaille window glass, visually sorted according to their extent of corrosion, were examined for physical changes while air-drying and solvent-drying. Polished cross-sections of the samples were examined with a JEOL-35CF SEM with a LINK AN 10,000 dispersive x-ray analyzer. Elemental distribution maps showed distinct alterations in the positioning of elements according to the corroded nature of the glass.
A New Tool for Cellulose Degradation Studies
Authors: Arthur Jakoa E. , Jacksona J. P. , Arthurs E. , Schwalbe L. A. , Sega R. M. , Windisch D. E. , Long W. H. , Stappaerts E. A. 
Published: March 2011

AbstractWe describe a new technique for studying thermally-induced chemical transformations in cellulose. The apparatus consists of a carbon dioxide laser for heating, an infrared thermometer, and an optical reflectance spectrometer. To illustrate the technique, we present measurements from a single piece of sample linen along five isotherms in the range 200–290°C. The results are discussed in terms of first-order chemical rate theory and a fourstep model. From the measurements we derive the activation energies, Arrhenius constants, and reflectivities of the chromophoric states.
Application of Compositional Analysis to the Study of Materials and Objects of Art and Archaeology
Authors: Sayre Edward V. 
Published: March 2011

AbstractArchaeologists, art historians and art conservators are almost constantly concerned with the questions of where, when and by whom the objects within their care were made. Knowledge of the conditions under which the objects were found may not answer these questions, as the objects may have traveled extensively or have existed for some time before they arrived at sites where they were discovered. Stylistic considerations often can provide answers, but not infallibly, as styles were sometimes copied at locations and at times quite different from those for which they were most characteristic. Compositional analysis can often help provide answers to these questions because traditions in the use of particular materials have often persisted in and accordingly have been characteristic of particular regions, periods and even of particular workshops. For example, the deliberate alloying of copper with tin, arsenic, antimony, lead and/or zinc has varied greatly from region to region and from time to time.
Corrosion of Silicate Glasses: An Overview
Authors: Hench Larry L. 
Published: March 2011

ABSTRACTThe corrosion of silicate glasses is described in terms of four stages of surface attack which result in six types of surface conditions depending upon the glass composition and various environmental and physical factors. Type I and II surfaces correspond to durable glasses which have a very high surface SiO2 content whereas Type IV and V surfaces are unstable. Type IIIA surfaces include bioactive glasses which chemically bond to bone and Type IIIB surfaces are characteristic of the alkali borosilicate nuclear waste glasses which form multiple layers of precipitated surface films.
Developments in Quantification and Use of Environmental Cracking Mechanisms for Design and Lifetime Prediction
Authors: Andresen Peter L. , Ford F. Peter 
Published: March 2011

ABSTRACTFollowing a long period of qualitative assessment of environmental cracking phenomenology, there has been recent emphasis on developing quantitative, mechanistically-based predictive models. This focus is driven by scientific and engineering concerns. For example, neither pressure vessel design nor evaluation codes incorporate the contribution of environmental cracking understaticloading, nor do they differentiate between the large possible variations in both environment and material chemistry. Similarly, while numerous scientific hypotheses have been proposed to explain the crack advance process and related, contributing phenomena, ultimately their validity must withstand the scrutiny of quantification and comparison to measured cracking kinetics and observed component lifetimes.The benefits and approaches involved in predicting environmental cracking based on mechanistic modeling of crack advance and its underlying phenomena are discussed. The benefits and approaches involved in predicting environmental cracking based on mechanistic modeling of crack advance and the underlying phenomena are discussed. The formulation of a quantitative model from fundamental mechanisms has progressed most rapidly for the film rupture / slip dissolution mechanism of environmental crack advance. Specifically, for iron and nickel base alloys in high temperature water, identification, quantification and integration of the important underlying parameters has led to algorithms which predict crack growth rates over a wide continuum in static and dynamic stressing, metallurgical microstructure and solution chemistry applicable to light water reactors. For widely studied systems, e.g., stainless and low alloy steels in 288°C water, the predictions are within a factor of 2–3 for 90% of the data which span “initiation”, the possible roles of contributing, “secondary” crack advance processes in oxidation-based mechanisms, such as environmentally enhanced cleavage, spontaneous oxidation, etc.Similar efforts to identify and quantify the critical parameters and underlying processes in crack advance mechanisms involving hydrogen embrittlement, environmentally assisted cleavage, etc. are summarized. Conceptual approaches to and progress toward integrating these models with in-situ chemical and crack monitoring devices, with the goal of providing on-line evaluation, control and lifetime prediction of environmental cracking, are also discussed.
Quxatitative Theory of Seasitization
Authors: Devine Thomas M. 
Published: March 2011

ABSTRACTThe chromium composition along the grain boundaries of sensitized austenitic stainless steel are calculated using several different quantitative theories of sensitization. The results of the calculations are compared to measured values of the chromium composition along the grain boundary in an effort to assess the validity of the various theories. The experimental results point out two facts not previously emphasized in prior studies: (1) the amount of carbide precipitation required to sensitize austenitic stainless steel is small; (2) significant de-sensitization does not occur until after large amountsof carbide precipitation have occurred.
An Empirical Model for Environmental Damage at the Crack Tip
Authors: Chang K. -M. 
Published: March 2011

ABSTRACTAn experimental method that is able to verify and to characterize the damage zone developed in front of crack tip under time-dependent fatigue crack propagation has been established. The crack growth rate was found to decrease exponentially in the damaged zone. Such a crack growth behavior can be described by a mathematical model which only requires three parameters: initial crack growth rate, (da/dN)q; normal crack growth rate (da/dN)o; and damaged zone size, D. An analyticat relationship has been developed to correlate the temperature and the time of sustained loading to the size of the induced damaged zone.
Stress Corrosion Cracking of Magnesium Die Casting Alloys
Authors: Miller William K. 
Published: March 2011

ABSTRACTContrary to limited published information on the subject, magnesium die casting alloys are shown to be susceptible to stress corrosion cracking (SCC), requiring only partial immersion in distilled water. Also described is evidence that this SCC results from a cathodic process, with perhaps hydrogen-assisted cracking and film rupture both playing roles.
Advanced Metal Matrix Composites
Authors: Crowe C. Robert 
Published: March 2011

ABSTRACTAdvanced metal matrix composites are emerging as materials of construction for high performance aerospace applications. The thrust is to develop high specific strength and high specific modulus ultra-lightweight composites using Al or Mg as matrix materials for space structure applications, and for higher temperature applications, to develop materials using various aluminides as matrix materials. This paper presents an overview of the methodology used to develop advanced MMC's and discusses the problems and limitations faced in achieving the composite materials development goals.
Glass Hydration Mechanisms with Application to Obsidian Hydration Dating
Authors: White William B. 
Published: March 2011

ABSTRACTChemical analysis of typical obsidians place them with a group of silica- and alumina-rich glasses constructed of a three dimensional framework of silica and alumina tetrahedra with nearly all tetrahedra sharing corners. Raman and infrared spectra of unweathered obsidians confirm the high degree of polymerization as well as some additional structural disorder. Analysis of dissolution rates of various glasses shows obsidian to be among the most stable, comparable to the most durable synthetic glasses. Surface layers on glasses can be chemically characterized by depth-profiling techniques such as SIMS and SIPS that give depth-concentration profiles for individual elements. Hydration rinds on glasses can be structurally characterized by infrared spectroscopy which shows both hydration and re-polymerization as the rinds age. Because obsidians are already completely polymerized glasses, their hydration rinds are mainly a result of hydrolysis and alkali exchange.
Diffusion Cells for Integrating Temperature and Humidity Over Long Periods of Time
Authors: Trembour Fred , Smith Franklin L. , Friedman Irving 
Published: March 2011

ABSTRACTThe rate of many processes, including the diffusion of water into rhyolitic volcanic glass (obsidian), as well as the racemization of amino acids is temperature dependent, and a knowledge of temperatures integrated over time periods of at least a year is necessary to quantify these processes. The construction and properties of simple devices consisting of small plastic containers that change weight at a rate that is a function of temperature and the activity of water will be described. The cells function because water diffuses through the plastic across a constant vapor-pressure gradient. This vapor-pressure gradient is maintained constant between the substances within the cell and the materials outside the cell. The plastic cells are usually filled with water and surrounded by a dehydrating agent, such as silica gel. A better arrangement is to fill the cell with a mixture of solid sodium chloride (NaCl) and a saturated solution of NaCl, and to surround the cell with pure water. A number of plastics have been investigated, including polycarbonate, polystyrene, tefzel, polyallomer, and methacrylate. The cells have been sealed by various methods including screw caps, room-temperature vulcanizing silicone rubber sealant, and rubber stoppers. The final design consists of a small cell made of a polycarbonate plastic centrifuge tube containing solid NaCl plus NaCl-saturated solution sealed with a rubber stopper and placed in a polypropylene tube containing pure water. Our aim has been to develop cells that are sufficiently sensitive to yield a precision of ±0.2°C when exposed for one year at temperatures that range from 0° to 40°, and that will fit into metal fittings that can be screwed into standard 3/4-inch plastic water pipe (approximately 1 inch outside diameter).
Changes in Waterlogged Medieval Window Glass
Authors: Alten Helen I. 
Published: March 2011

ABSTRACTSamples of wet 13th-14th c. Grisaille window glass, visually sorted according to their extent of corrosion, were examined for physical changes while air-drying and solvent-drying. Polished cross-sections of the samples were examined with a JEOL-35CF SEM with a LINK AN 10,000 dispersive x-ray analyzer. Elemental distribution maps showed distinct alterations in the positioning of elements according to the corroded nature of the glass.
Technological Prospects for Germanium Silicide Epitaxy
Authors: Bean John C. 
Published: March 2011

ABSTRACTThis paper describes preliminary device work on GexSi1−x, based devices and examines progress towards the realization of a silicon based heterostructure technology. Target areas for further work are identified including: An enhanced understanding of metastable-growth processes; The need for defect confinement in discommensurate epitaxy; Elimination of manufacturing barriers caused by particulate induced defects in MBE and low growth rates in low temperature CVD.Over the last five years, studies of GexSi1−x have yielded an understanding of crystal growth mechanisms and information on electrical and optical properties such as bandstructure and heterojunction band alignment. These in turn lead to a number of preliminary device applications including optical detectors, modulation doped transistors and heterojunction bipolar transistors. In this paper, I will try to answer the question posed by the symposium organizers: In the germanium silicide system, has our understanding and experience reached the point that we have the basis for a technology, and if not, where must further work be done?
Characteristics of all-OMCVD Grown GaAs MESFETS on Si Substrates
Authors: Lee Jhang Woo , McCullough R. M. , Morrison R. H. 
Published: March 2011

ABSTRACTWe present DC characteristics of all-OMCVD grown GaAs MESFET structures on Si substrates with unintentionally doped GaAs or AlGaAs buffer layers. MESFETs fabricated in two and three inch GaAs on Si wafers pinch off well and exhibit reasonably high transconductances up to 110 mS/mm for 1 μm gate devices. The reverse Schottky breakdown voltage of the MESFET gate is as high as 15 V and the forward turn on voltage is ∼0.65 V. The ohmic isolation is comparable to the typical homoepitaxial layer with a leakage current of 100 nA at a 1 V bias. The low background doping levels of unintentionally doped GaAs buffer layers is the key factor for this successful MESFET operation.
Low Pressure MOCVD Growth and Characterization of GaAs and InP on Silicon Substrates
Authors: Razeghi M. , Defour M. , Omnes F. , Nagle J. , Maurel P. , Acher O. , Huber A. , Mijuin D. 
Published: March 2011

ABSTRACTHigh quality GaAs and InP have been grown on silicon substrates, using low pressure metalorganic chemical vapor deposition technique. The growth temperature is 550°C and the growth rate 100 A/min.Photoluminescence, X-ray diffraction and electrochemical profiling verified the high quality of these layers. The use of superlattices as buffer layers, (GaAs/GaInP) in the case of GaAs/Si and (GaInAsP/InP) in the case of InP/Si, decreased the amount of misfit dislocations in the epitaxial layer. Carrier concentrations as low as 5.1015 cm−3 have been measured by electrochemical profiling.
Ion Implantation and RTA in III-V Materials
Authors: Streetman B. G. , Dodabalapur A. 
Published: March 2011

ABSTRACTWe review the applications of ion implantation in several III-V materials, and rapid thermal annealing techniques to activate the implant and remove the crystalline damage. Ion implantation has become the preferred technique when selective area doping is necessary. It has been used successfully to fabricate n, n+, p, p+, and semi-insulating regions in III-V binary, ternary, and quaternary compounds, and multilayer structures. Ion implantation has also been used to produce layer mixing in multilayer structures, and superlattice disordering. The annealing step necessary to activate the implant and remove the crystalline damage is complicated by several factors such as incongruent evaporation of the group V element, layer mixing, and dopant redistribution. Rapid thermal annealing techniques, which typically employ anneal times between 1 second and 100 seconds, are generally more suitable than conventional furnace annealing. The short annealing times result in much less dopant redistribution, and reduced layer mixing in multilayer structures. Even for short annealing times, it is necessary to employ a protection scheme to suppress the loss of the group V element. Several such methods are discussed, including dielectric encapsulation, proximity techniques, and controlled ambient techniques.
Activation Mechanisms in Ion-Implanted GaAs
Authors: Morris N. , Sealy B. J. 
Published: March 2011

ABSTRACTRapid thermal annealing has been used to study the electrical activation mechanisms for magnesium and selenium implants in GaAs. By analysing the changes in electrical activity as a function of annealing time and temperature, a model has been developed which accurately predicts the electrical properties following the post-implant annealing stage. The model has been used to study the activation of other ions, particularly zinc, beryllium, tin and sulphur, the results of which will be compared with those of magnesium and selenium. The results suggest that the mechanism for electrical activation is dominated by the diffusion of gallium, arsenic or vacancies. The paper will present the model and discuss the activation mechanisms of the ions.
Ion Implantation Processing of III-V Strained-Layer Semiconductors
Authors: Myers David R. 
Published: March 2011

ABSTRACTIon implantation has had a strong impact on the development of III-V strained-layer semiconductor (SLS) materials and device technologies. Implantation studies have helped delineate the present understanding of strained-layer stability and metastability limits. Resulting ion beam technologies have led to improvements in a variety of SLS discrete devices, including optoelectronic emitters, photodetectors, and field-effect transistors. Both SLS stability criteria and implanted SLS devices are reviewed with respect to future applications in optoelectronics.