bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon Hydride Formation in Co-60 Irradiated Optical Fibers
Authors: Evans Bruce D. 
Published: March 2011

ABSTRACTDoping with hydrogen is shown to reduce the sensitivity of optical fibers to form optical attenuation bands as a result of ionizing radiation and to increase the recovery rate in the near infrared after the exposure. In this case silicon hydride is shown to form in low-OH, pure silica fibers upon Co-60 irradiation. The ratio of radiolytically induced changes in silicon hydride to silicon hydroxide is estimated to be greater than ten. The more numerous radiolytic formation of SiH species implies the participation of oxygen vacancy type defects in the radiolytic process.
Guided Wave Devices Based on III-V Heterojunctionand Quantum Well Structures
Authors: Yu P. K. L. , Chang W. S. C. , Pappert S. , Kellner A. L. , Lin S. C. 
Published: March 2011

ABSTRACTGuided wave technology based on III–V compound semiconductor materials is important for optical signal processing, fiber communication and sensor applications. The provision of heterojunction and quantum well materials by LPE, MBE, and MOCVD have led to new concepts and techniques in tailoring the properties of discrete devices and optoelectronic integrated circuits. This paper discusses the electro-optical properties of heterojunction, quantum well, superlattice based on two novel effects, the Franz-Keldysh effect in bulk materials and the quantum confined Stark effect in semiconductor quantum wells. The electroabsorption and electrorefraction properties resulted from these effects are utilized in the realization of some waveguide modulators. Materials based on InGaAsP/InP heterojunctions, InGaAs/GaAs strained layer quantum wells and InGaAs/InP quantum wells will be emphasized.
Formation and Properties of Thermosetting and High TgSystems
Authors: Gillham John K. 
Published: March 2011

AbstractA review of research in the author's laboratory on the conversion of reactive liquids to amorphous polymeric glasses is presented. Inter-relationships between reactants, reaction conditions, and subsequent material properties of thermosetting and high Tg polymers are discussed from the point of view of a generalized time-temperature-transformation (TTT) diagram.
Area-Selective Laser Processing Techniques for Multichip Interconnect
Authors: Liu Y.S. , Cole H. S. 
Published: March 2011

AbstractThe interest in laser processing technology has increased significantly in recent years because of increasing demands for application-specific IC design and fabrication, yield enhancement, circuit restructuring, and prototyping; all of these benefit from an adaptive processing technique using direct energy for improvement of precision, resolution, process automation, and turnaround time. This paper reviews several laser-patterned metallization techniques developed for high-density multichip interconnection applications. Key material and process requirements for developing a viable laser-direct-write interconnect technique on polyimide are addressed.
The Influence of Thermal and Solvent Cycling on the State of Stress in Polyimide Coatings
Authors: Sackinger Scott T. , Royan R. Van , Farris R. J. 
Published: March 2011

AbstractTo evaluate the influence of permeant and temperature exposure on the state of stress in polyimide coatings, uniaxial experiments on thin polyimide films held at constant length were performed. The uniaxially constrained poly(4,4′,-oxidiphenylene pyromellitimide) or PMDA-ODA films were exposed to methylene chloride while the stress was monitored. It was found that the stress was reduced to zero from a stress as high as 40 MPa by the swelling with methylene chloride. Attempts to remove the methylene chloride at room temperature with a nitrogen purge resulted in a stress increase of only 8 MPa. However, the remaining stress of an additional 20 Mpa was recovered when the sample was heated to 350°C and returned to room temperature. Temperature exposures of 150°C and 200°C resulted in a stress increases of only 14 MPa and 17 MPa, respectively. These observations suggest a strong coupling between the stress state, temperature and equilibrium swelling by permeants.
Applications of SIMS to Spatially Modified Polymer Film Characterization
Authors: Linton Richard W. , Judy Cheryl L. , Maybury Susan G. , Corcoran Sean F. 
Published: March 2011

AbstractThe predominant application of secondary ion mass spectrometry (SIMS) to organic polymeric solids has been the molecular monolayer analysis of thin films in the “static” mode. The primary emphasis in this paper, however, is the evaluation of SIMS for two or three-dimensional compositional mapping studies of spatially modified polymers. This often requires the use of the “dynamic” SIMS mode to provide lateral images, depth profiles, or 3-D image depth profiles. Selected applications are presented including SIMS studies of surface derivatized polymers, metal-doped conductive polymer films, and patterned polymeric materials or fibers. One analytical objective is to assess the extent to which compositional information is limited by primary beam damage. The outlook for SIMS instrumentation combining high lateral spatial resolution with minimal primary beam damage to surface molecules is summarized, for example the combination of microfocused liquid metal ion sources and time-of-flight mass spectrometry.
surface Enrichment in Polymer Blends: Simple Theory and an Experimental Test
Authors: Jones R.A.L. , Kramer E.J. , Rafailovich M.H. , Sokolov J. , Schwarz S.A. 
Published: March 2011

AbstractIf a polymer mixture which is in the bulk one-phase region is next to an interface - this may be with another polymer, with a non-polymeric solid, or with the air - the composition of the mixture at the interface will be different from the bulk [1–4]. There are two questions we would like to understand: what determines the composition of the mixture at the interface, and how does that composition increment decay back to the bulk value. This surface or interface segregation has important practical consequences; in the surface case such segregation will profoundly affect wettability, with consequences for the strength of adhesive joints and the biocompatibility of polymeric surgical implants, as well as influencing friction and wear; at interfaces with non-polymers segregation is important for the adhesion of mixed polymer phases to non-polymer phases such as reinforcing fibres or fillers. In this paper we describe some experiments on surface segregation in a very well characterised model system and we describe a recent theory that can be quantitatively tested by our data. We will consider the consequences of this new understanding of surface segregation in polymer mixtures, and we will argue that many of these conclusions may be carried over to the more general case of interface segregation, which opens up a number of interesting technological possibilities.
Characterization of Interfaces Between Polymers and Metals by Static SIMS
Authors: Ooij W.J. Van 
Published: March 2011

AbstractThe use of static Secondary Ion Mass Spectrometry (SIMS) in the characterization of polymer surfaces and interfaces between polymers and metals is described. Examples are given of the use of SIMS to study the effects of plasma treatments on polyimide surfaces and for the analysis of the interface in metallized polytetrafluoroethylene (PTFE).
XPS Identification of Al-PVA Complex
Authors: Akhter S. , Jo S.K. , Zhou X.-L. , White J.M. 
Published: March 2011

AbstractAluminum was deposited on a polyvinyl alcohol film surface by reaction with trimethyl aluminum at 300 K. XPS analysis indicated a carbon free deposition of a monolayer of Al. The Al forms an oxy-carbide complex, AlOC, which exhibits a stoichiometry of 1:1:1 for Al, O and C. Within this complex Al is bonded to both C and O resulting in the appearance of low binding energy peaks in C(ls) and O(ls) spectra. The complex is oriented such that Al forms the outer-most layer. The Al modified surface was hydrophobic compared to the hydrophilic PVA. A reaction mechanism is proposed based on XPS and mass spectrometric data.
Solvent and Curing Effects on Diffusion at Polyimide Interfaces
Authors: Tead S. F. , Kramer E. J. , Russell T. P. , Volksen W. 
Published: March 2011

AbstractInterdiffusion at interfaces between deuterated polyamic acid (d-PAA) and polyimide (PI) films was investigated with forward recoil spectrometry, an ion beam analysis technique. The PI films were prepared by spin – coating a solution of PAA on a silicon substrate, followed by an anneal at a temperature Ti, which produced partial or complete conversion of the PAA to PI. An overlayer of d-PAA was added in one set of samples by spin – coating from solution and in another set by transferring (in the absence of solvents) a dry d- PAA film onto the PI surface. The bilayer samples were then either annealed at a temperature Td or allowed to stand at room temperature. Bilayers prepared by spin – coating d-PAA from solution directly on partially cured PI films had interdiffusion distances w that decreased with increasing values of Ti to immeasurable levels by Ti = 200 °C. The decrease in w with increasing Ti is thought to be caused by a positive Flory parameter between PAA and PI which increases with the imide fraction in the PI film; the result is an increasing immiscibility between the swollen polymer layers. No interdiffusion occurred in the solventless – transfer samples for any combination of temperatures Ti or Td from room temperature up to 400 °C. Post – annealing of spin – coated bilayers at a temperature Td up to 400 °C was ineffective in producing any additional interdiffusion. Both of these results indicate that thermally activated interdiffusion (even for initially unimidized samples) does not exist in the absence of solvents, an effect attributed to the rapid increase of the glass transition temperature of the polymer with imidization.
Fluorinated Monomolecular Assemblies: Model Systems to Probe Chemical Interactions at the Polymer-Metal Interface
Authors: Chau Lai-Kwan , Porter Marc D. 
Published: March 2011

AbstractMonomolecular assemblies of n-perfluorocarboxylic acids [CF3(CF2)nCOOH, n=6, 7, and 8] have been adsorbed at silver by spontaneous adsorption from dilute alcoholic solutions. Infrared reflection spectroscopy indicates that the monolayers form by the reactive chemisorption of the carboxylic acid to a carboxylate salt. Ellipsometrically-determined film thicknesses increase linearly with an increase in the perfluorocarbon chain length. Contact angle measurements indicate that the packing density of the films increases with increasing chain length, resulting in an interface with a low surface free energy. The structure and properties of these interfaces are compared to those for monolayers of n-alkanoic acids. The potential utility of such assemblies to probe fundamental chemical and physical interactions at polymer-metal interfaces are also discussed.
XPS Study of the Interface of Polyimide on Cr And Ni.
Authors: Garilli Marco , Marletta Giovanni , Puglisi Orazio , Oliveri Carmelo , Magro Carmelo , Ferla Giuseppe 
Published: March 2011

AbstractThe paper presents a study of three polyimide-oxide interfaces. The Cr-oxide-PI interface seems to undergo a drastic topographical structural rearrangement. The case of the Ni surface is indicative of heavy decomposition of the Ni oxide which induces the decomposition of the polymer film. On the contrary the stabilized Ni surface behaves in a normal manner indicating that the driving force for the decomposition is the instability of the oxide.
Conducting Polymer Films by Ion Implantation
Authors: Lu P.H. , Moody R.A. , Loh I.H. 
Published: March 2011

AbstractInsulating polymeric sheets were made electrically conductive by ion implantation. The effects of implantation parameters, such as ion species, dose, energy, beam current density, and substrate temperature, on the resultant sheet resistivities were investigated. Surface structural changes of implanted polymers were evaluated by X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and Fourier transform infared spectroscopy (FTIR). Electron spin resonance (ESR) and temperature dependent resistivity measurements were performed to explore the conduction mechanisms of implanted polymers. The results indicate that ion beam modification of polymers proceeds via a similar mechanism as high temperature pyrolysis. The resultant carbon-enriched materials which can be described by the conducting grain model.
Measureme of Soiderability Performance of IC Lead/Leadfinish Sysrems Using the Weiting Baiance
Authors: Wittmershaus Janice , Grayeli N. , Siemimann J. , Vickers E. 
Published: March 2011

AbstractA critical investigation of the use of the wetting balance to characterize leadfinish solderability is described. The wetting force vs. time curves for matte tin and solder plated copper coupons which have been subjected to well controlled environmental conditions, such as steam and high temperature bakes have been analyzed. Steam exposure was shown to impact greatly the shape of the wetting force curve, with the major effect observed after one hour of exposure and with no significant changes upon further exposure. The high temperature exposure (bake) and associated intermetallic compound formation had little effect on the force-time curve as long as it was protected from oxidation. Results show that when the wetting balance is used in conjunction with SEM and microanalysis tools, it is an excellent diagnostic tool for determining sources of solderability changes.
Passive Thermal Management of Excess Heat from Electronic Devices
Authors: Glatz John J. , Leon Juan F. 
Published: March 2011

AbstractThermal management in the packaging of electronic components is fast becoming an enabling technology in the development of reliable electronics for a range of applications. The objective of the paper is to assess the feasibility of using advance high thermal conductivity pitch fiber (HTCPF) as a solution to some of the packaging problems. The general scope will include the following: identification of the candidate material and its potential applications; thermal management of the chip to board interface; thermal management of the heat within the multi-layer interconnect board (MIB); thermal management of the standard electronic module-format E (SEME); and heat transfer thru the enclosure to a remote heatsink/heat exchanger.
Ceramic Fiber - Fluoropolymer Composites for Electronic Packaging Materials
Authors: Bolt John D. 
Published: March 2011

ABSTRACTAluminum nitride (AIN), alumina and aramid fibers have been incorporated into epoxy and fluoropolymer matrices. The fluoropolymer composites have dielectric constants less than 3.4 and losses below 0.3%, measured out-of-plane. In-plane and out-of-plane thermal conductivities of the AIN-fluoropolymer composites averaged 5.2 and 1.3 W/mK, respectively, at fiber volume fractions of 0.26 to 0.29. In-plane thermal conductivities of woven fabric composites were accurately predicted by mixing rules; for non-woven and short fiber composites, thermal conductivities were less than predicted. These composites had higher out-of-plane thermal conductivities due to out-of-plane components of the fiber orientations.
Removal of Processing Aids from Ceramic/Polymer Composites
Authors: Stangle Gregory C. , Rhee Dong-Joo , Aksay Ilhan A. 
Published: March 2011

ABSTRACTFundamental issues in the removal of processing aids from ceramic compacts prior to sintering have been investigated, both experimentally and theoretically. A general theoretical model has been developed that couples simultaneous momentum, heat, and mass transfer phenomena in disordered porous materials with the mechanical response predicted by an appropriate poroelasticity theory for partially saturated porous granular materials. The kinetics of pyrolytic degradation of organic processing aids were studied using a thermogravimetric analysis-mass spectrometry (TGA-MS) system.
The Effects of Aluminum Alkoxides on the Synthesis of Composite Powders of Alumina and Titania
Authors: Harris Michael T. , Byers Charles H. , Brunson Ronald R. 
Published: March 2011

ABSTRACTThe synthesis of mixed oxide ceramic powders that consist of very fine (submicron)-monodisperse particles with uniform composition is desirable in the improvement of existing ceramics and the development of new ceramic materials. Metal alkoxide hydrolysis is a very attractive method for the synthesis of ultrapure composite powders at low temperatures by the sol-gel process.The present study investigates the effects of the hydrolysis of aluminum alkoxides and the condensation products on the growth kinetics and morphology of composite particles containing alumina and titania. Alkoxides of titanium and aluminum are employed; therefore, powders of high purity are produced. Since various solvents are used as media for powder synthesis, the effect of the solvent on particle morphology will also be discussed.
Rapid Omnidirectional Compaction of Y2O3 Stabilized Tetragonal Zirconia
Authors: Pechenik Alexander , Pyzik Aleksander J. , Beaman Donald R. 
Published: March 2011

ABSTRACTThe Rapid Omnidirectional Compaction (ROC) technique has been applied successfully to the densification of TZP (3 mole % yttria) ceramics at 1260°C. The combination of high pressure (830 MPa) and temperature results in the plastic deformation of the ceramic particles. The extent of deformation, and consequently, the ROCing temperature, can be determined by using hot hardness of the ceramic material as an approximation of the ceramic's yield stress. The materials ROCed at 1260°C are characterized by a grain size of 0.15 gim, a flexure strength of 1300 MPa, a hardness of 1340 kg/mm2, and a fracture toughness of 5.0 MPa m1/2.
Densification of Particulate Ceramic Composites: The Role of Heterogeneities
Authors: Jonghe Lutgard C. De , Rahaman Mohamed N. 
Published: March 2011

ABSTRACTInert p articulate inclusions in ceramic powder compacts can obstruct densification behavior significantly. The factors that are the causes of this decrease in the sinterability are reviewed. It is concluded that the origin of the sintering difficulty resides in defects that processes such as die compaction introduce during the initial forming of the composite powder compact. Alternative processing methods are suggested that should minimize the negative effects of the dispersed inclusion phase on densification.
Sol-Gel Processing of Advanced Dielectric Ceramics for Microwave Applications
Authors: Schnoeller M. , Wersing W. 
Published: March 2011

ABSTRACTHighly dielectric ceramics make it possible to markedly miniaturize passive microwave components. We have successfully synthesized ceramic powders of the most important microwave ceramic systems (ZrTiSn)O2, Ba(TiNiZnTa)O3 and Ba(MgTa)O3 by using the sol-gel process. Nonaqueous solutions of metal organics together with different inorganic metal salts were used as precursors. The gels derived from these solutions are homogeneous and transparent. Different drying procedures were investigated in order to optimize powder morphology. Thermoanalytic methods and high -temperature x-ray diffraction were used to study the decomposition of xerogels and the formation of crystal phases, respectively. The calcination process was found to be complete at temperatures well below 750 °C.For the production of barium-containing powders, wet milling must be avoided because this washes out barium and thus causes undesired phases to appear. A dry milling step of the xerogel solves this problem. The prepared (ZrTiSn)O2 and Ba(TiNiZnTa)O3 already equal or surpass the quality of conventionally prepared ceramics.
Rheological Characterization of a Sol-Gel Process for the Preparation of High Tc Superconductors
Authors: Khan S. A. , Bagley B. G. , Barboux P. , Torres F. E. 
Published: March 2011

ABSTRACTSuperconducting thick films of yttrium-based cuprates can be prepared using a sol-gel technique. Rheological measurements on the precursors are used to identify processing parameters that can lead to better film properties. Steady and dynamic experiments reveal a direct correlation between the properties of the precursor, the final product, and the “age” of the yttrium component used in the precursor. Measurements support a proposed mechanism relating the “age” of the yttrium to the other properties and help to establish a processing methodology to obtain effective superconducting properties.
Synthesis and Structure of Novel Cuprates in the Ba-Y/Ca-Cu-O Systems
Authors: Sunshine Steven A. , Siegrist T. , Schneemeyer L. F. , Marsh P. 
Published: March 2011

ABSTRACTTwo new compounds in the Ba-Y/Ca-Cu-O systems have been grown as single crystals from a Ba(OH)2H2O flux. The compounds Ba3(Y/Ca, Cu)2O7−δ and Ba(Ca, Cu)O3−δ have the Sr3Ti2O7 and the perovskite structure, respectively.
Structural Studies of La2−xBaxCuO4 Between 11–293 K
Authors: Cox D. E. , Zolliker P. , Axe J. D. , Moudden A. H. , Moodenbaugh A. R. , Xu Y. 
Published: March 2011

ABSTRACTNeutron powder diffraction data have been collected from samples of La1.9Ba0.1CuO4 and La1.85Ba0.15CuO4 in the temperature range 11–293 K. The first material undergoes a phase transition from the tetragonal K2NiF4-type structure (space group 14/mmm) to the orthorhombic La2CuO4-type structure (space group Bmab) at about 280 K, and then a second transition to another type of tetragonal (or near-tetragonal) structure with probable space group P42/ncm. The latter transition occurs predominantly between 50–40 K, but about 10% of the orthorhombic phase persists down to 15 K. Rietveld refinement was carried out at selected temperatures in the different structural regions. The differences among the low temperature structures can be cb acterized by tilting of the CuO6 octahedra about different rotation axes on the basis of the simple X-Y model previously proposed by Axe and coworkers. The tilt angle, which is a measure of the long-range order parameter, is about 3.5° at 15 K.Data sets were also collected from La1.85Ba0.15CuO4 at 293, 90 and 11K. At the two latter temperatures there was some peak broadening consistent with the distortions observed in previous high resolution neutron [Paul and co-workers] and x-ray [Axe and co-workers] powder studies. Rietveld analysis of the data indicated the presence of local octahedral displacements, but it was not possible to determine the nature of the correlations.
Growth of Superconducting La2−xSrxCuO4 Single Crystals
Authors: Kojima Hironao , Tanaka Isao 
Published: March 2011

ABSTRACTHigh quality large single crystals of La2−xSrxCuO4 were grown by the traveling solvent floating zone method(TSFZ method). The crystals up to about 6 mm diameter and 40 mm length were obtained. The composition of the grown crystals was uniform and was determined to be La1.86Sr0.14Cu0.97O3.89. The single crystals were superconductors with Tc=37.5K and δ Tc=1.1K, and had a significant anisotropy of the electrical resistivities at the non-superconducting state.
High Tc Superconductors using Solution Techniques
Authors: Barboux P. , Valente I. , Tarascon J.M. , Khan S. , Shokoohi F. , Henry M. , Morineau R. , Bagley B.G. 
Published: March 2011

ABSTRACTWe have investigated different solution techniques to synthesize the Cu-based superconductors in the thick film form. Thick films of YBa2Cu3O7 have been produced using controlled precipitation techniques. Bi-based and Tl-based materials have been deposited by spraying of ionic solutions. The numerous difficulties encountered during each process are analyzed in order to propose new synthesis procedures such as a new method, based on the precipitation of hydroxides only, which is described as a prospective for lowering the synthesis temperature and shortening the reaction time.