bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Behavior of Spin-on Silicon Dioxide (SOX) in a Metal-Oxide-Semiconductor Structure
Authors: Lifshitz N. , Smolinsky G. , Andrews J. M. 
Published: March 2011

ABSTRACTWe studied the behavior of mobile charges, which we believe are hydrogen ions, in a novel spin-on oxide, SOX. Our analysis is based on the Triangular Voltage Sweep (TVS) technique, which is normally used to detect the presence of mobile alkali ions in silicon dioxides. We found that the TVS traces of protons exhibit several unique features that allow us to distinguish a proton signal from that of other common contaminants, such as sodium. We suggest a model to explain these unique features. We show that the presence of hydrogen in the SOX material is due to the high water retention of this porous oxide.
Catalysis of Electroless Copper Plating using Pd+2/Poly(Acryilc Acid) TIIIN Films
Authors: Jackson Robert L. 
Published: March 2011

ABSTRACTA new method is described for initiating electroless copper deposition onto dielectric substrates. The method employs a thin poly(acrylic acid) film, applied to the substrate by dip-coating, to bind Pd+2 from PdSO4 solution. Uptake of Pd+2 takes place by H+/Pd+2 ion exchange at the carboxylic acid sites of the polymer. Upon immersion of a substrate treated with Pd+2/poly(acrylic acid) into an electroless copper plating bath, reduction of Pd+2 to Pd0 takes place, forming an active catalyst for the initiation of electroless copper plating.
Low Temperature Transformation of the Surface of Copper Oxide Filled Ptfe Via Treatment in a Hydrogen Plasma
Authors: Goldman Dov B. 
Published: March 2011

ABSTRACTThe surface conductivity of PTFE-copper oxide filled composites containing between 10 and 25% of the oxides increases significantly after treatment in a low pressure hydrogen plasma at temperatures below 100°C. The plasma-reduction of copper oxides (CuO and CuO/Cu2O mixture) was investigated and compared with thermal reduction at different hydrogen partial pressures.
Degradation of the Polyimide/Copper Interface
Authors: Chakravorty K. K. , Loebs V. A. , Chambers S. A. 
Published: March 2011

ABSTRACTA comparative investigation of polyimide/Cu interface degradation has been carried out for ultrathin photosensitive, non-photosensitive, and preimidized polyimide precursor films cured while in contact with a Cu substrate. The role of curing byproducts and environmental conditions on interface degradation has been elucidated by means of X-ray photoelectron spectroscopy. Immediately after curing, we observed some oxidation of the Cu in contact with non-photosensitive and photosensitive polyimide overlayers. On the other hand, only negligible oxidation was observed for the preimidized polyimide/Cu interface. Experiments in which samples were stored in vacuum, air and a humidity chamber show a dependence of the oxidation kinetics on air/moisture exposure. Preimidized and photosensitive polyimide/Cu interfaces, stored in air, became more extensively oxidized with time relative to identical samples stored in vacuum. Moreover, all three polyimide/Cu interfaces exhibited significantly more oxidation after 3 days in a humidity chamber than after 19 days of storage in air. Taken together, these data clearly demonstrate that absorbed water and its interaction with curing byproducts are key factors in the extent of Cu oxidation at the interface.
Interaction of an Aromatic Molecule with a Surface
Authors: Vidali G. , Karimi M. 
Published: March 2011

ABSTRACTThe interaction between an aromatic molecule and the graphite basal plane is constructed using a Lennard-Jones 6–12 potential. The corrugation of the potential across the surface, the binding energies and vibrational frequencies of the aromatic molecules on the basal plane have been calculated and compared with experimental data. We have also calculated the interaction between a rare-gas atom and an aromatic molecule using two independent models, one based on the pairwise sum of the Lennard-Jones potential and the other on the Effective Medium Theory (EMT) for the repulsive part and a Van der Waals dispersion term for the attractive part. Our results are then compared with available experimental data.
New Organotellurium Precursors for the Pyrolytic and Photolytic Deposition of Hg1-xCdxTe
Authors: Gedridge Robert W. , Higa Kelvin T. , Nissan Robin A. 
Published: March 2011

ABSTRACTOrganometallic precursors with low decomposition temperatures are essential in the fabrication of high performance mercury cadmium telluride (Hg1-xCdxTe) infrared detectors by pyrolytic and photolytic metal-organic chemical vapor deposition (MOCVD). Film growth temperature is governed by the relative stability and/or reactivity of the organotellurium precursor, which is determined by the strength of the Te-C bonds. Since the rate-determining step in the pyrolysis of organometallic compounds involves bond breaking and free radical formation, we have concentrated on the synthesis of a variety of organotellurium precursors with substituents that possess low activation energies for the formation of hydrocarbon free radicals. The synthesis, characterization, and properties of methylallyltelluride, ethylallyltelluride, isopropylallyltelluride, tertiarybutylallyl-telluride, methylbenzyltelluride, and methylpentadienyltelluride are reported. These unsymmetrical tellurides were characterized by 1H, 13 C, and 125Te NMR spectroscopy. The potential applicability of these organotellurium precursors to lower film-growth temperatures in MOCVD is discussed.
The Synthesis of InP drom Indium Halides and Tris(Trimethylsilyl)Phosphine
Authors: Healy Matthew D. , Laibinis Paul E. , Stupik Paul D. , Barron Andrew R. 
Published: March 2011

ABSTRACTInP has been prepared by the reaction of InX3 (X = Cl, Br, I) with P(SiMe3)3. The intermediates and product have been characterized by XPS, elemental analysis and X-ray powder diffraction.
Coherent Anti-Stokes Raman Scattering Measurements of Group V Hydride and Trimethylgallium Decomposition in Organometallic Vapor Phase Epitaxy
Authors: Löckerath R. , Koss H. J. , Tommack P. , Richter W. , Balk P. 
Published: March 2011

ABSTRACTThe thermal decomposition of AsH3 and TMG is measured insitu under different experimental conditions. Simultaneously the production of H2, CH4 and C2H6 is observed. The data indicate a situation where AsH3 is only partially decomposed at the GaAs surface. The hydrogen released removes additional CH3 groups from the trimethyl-gallium (TMG) molecule, enhances the decomposition of TMG, and thereby forms methane.
Properties of Transparent Silica Gel - Pmma Composites
Authors: Pope Edward J. A. , Asami Minuo , Mackenzie John D. 
Published: March 2011

ABSTRACTTransparent silica gel - polymer composites have been prepared by the impregnation of porous silica gels with fluid organic monomer followed by in situ polymerization. These materials constitute an entirely new class of transparent composites.
Magnetic Properties Of Iron/Silica Gel Nanocomposites
Authors: Shull Robert D. , Ritter Joseph J. , Shapiro Alexander J. , Swartzendruber Lydon J. , Bennett Llawrence H. 
Published: March 2011

ABSTRACTHomogeneous gelled composites of iron and silica containing 5–30 wt. % Fe have been prepared by low temperature polymerization of aqueous solutions of ferric nitrate, tetraethoxysilane, and ethanol (with an HF catalyst). X-ray diffraction data, characterized by the presence of a diffuse scattering peak centered at 20≈24 degrees and the absence of any strong Bragg scattering from the iron-containing regions, indicates that these bulk materials are comprised of nanometer-sized regions of iron compounds embedded in a silica gel matrix. Scanning electron microscopy observations show that this matrix is characterized by the presence of many interconnected pores and that the size of these pores is related to the particle size of the Fe-containing regions. The paramagnetic nature of these materials at room temperature, as well as the small size of the iron-containing regions, is indicated by the appearance in many of the samples of only a high intensity central doublet in the 57Fe M6ssbauer spectra. The Mössbauer effect data demonstrates that the form of the iron can be changed by a subsequent treatment in an atmosphere of ammonia or hydrogen at elevated temperatures: for a 10 wt. % Fe sample treated with ammonia, only a central doublet was observed but with a much larger quadrupole splitting and isomer shift. Both of these subsequently treated materials became superparamagnetic at room temperature. In addition, magnetic susceptibility measurements indicate that the hydrogen treated material becomes a spin glass at low temperatures.
Synthesis, Characterization, and Properties of Nanophase Ceramics
Authors: Siegel R. W. , Eastman J. A. 
Published: March 2011

ABSTRACTUltrafine-grained ceramics have been synthesized by the production of ultrafine (2–20 nm) particles, using the gas-condensation method, followed by their in-situ, ultra-high vacuum consolidation at room temperature. These new nanophase ceramics have properties that are significantly improved relative to those of their coarser-grained, conventionally-prepared counterparts. For example, nanophase rutile (TiO2) with an initial mean grain diameter of 12 nm sinters at 400 to 600°C lower temperatures than conventional powders, without the need for compacting or sintering aids. The sintered nanophase rutile exhibits both improved microhardness and fracture characteristics. These property improvements result from the reduced scale of the grains and the increased cleanliness of the particle surfaces and the subsequently-formed grain boundaries. Research completed on the synthesis, characterization, and properties of nanophase ceramics is reviewed and the potential for using the nanophase synthesis method for engineering new and/or improved ceramics and composites is considered.
Ultrafine Composite Synthesis by Laser-Reactions and Rapid Condensation
Authors: Chow Gan-Moog , Strutt Peter R. 
Published: March 2011

ABSTRACTA new approach in ultrafine composite synthesis involves rapid condensation of metallic and non-metallic species, produced by laser-induced evaporation. A heated tungsten filament is simultaneously employed for codeposition of W via chemical transport mechanisms. This process occurs in a reducing environment of hydrogen gas, where evaporated species were produced by a laser-induced plume. Composite layers were formed on a Ni alloy substrate surface, at a rate of about 1Pm/sec. The matrix of the composite films was either Al or W, and the dispersed phase was amorphous silica fibers. The diameter of the fibers was between 25nm and 120nm, depending on the interaction times. Various analytical techniques have been employed to characterize the as-synthesized layers. Experimental evidences do not support the Vapor-Liquid-Solid model for fiber growth. An alternative fiber growth mechanism is proposed.
Fabrication of Ferromagnetic Fe/Mullite Composite Materials Via Sol-Gel Processing
Authors: Yamato Deanne P. , andis Abraham L. , Kuan Teh S. 
Published: March 2011

ABSTRACTThe sol-gel technique was used to fabricate α-Fe/mullite composite materials with iron concentrations ranging from 20–60 wt.% Fe. Microscopy studies showed the microstructure to consist of particulate α-Fe dispersed uniformly throughout a mullite matrix. Iron particle size, estimated by TEM, ranged from 20–500 nm. The materials exhibited ferromagnetic hysteresis with saturation magnetization Ms values as high as 115 EMU/g.
Material with Novel Compositions and Fine Microstructljres Produced Via the Mixalloy Process
Authors: Lee Arthur K. , Sanchez-Caldera Luis E. , Chun Jung-Hoon , Suh Nam P. 
Published: March 2011

ABSTRACTA new processing method, the Mixalloy process, has been developed to process alloys with novel microstructures and compositions. In this process, microstructural control is achieved through the use of turbulent mixing of liquid metals in addition to controlling solidification rate and chemical composition. Boride dispersion strengthened copper alloys were produced using the Mixalloy process. Thermally stable and fine (average less than 100 nm) boride dispersoids were formed by in-situ chemical reaction in the copper alloy matrices during mixing. The uniform mixture of the matrix and dispersoids was then rapidly solidified to maintain the fine microstructure. The consolidated material shows exceptional thermal stability and an excellent combination of strength, ductility, and electrical conductivity. Furthermore, the flexibility of the process allows the matrices of these dispersion strengthened coppers to be easily alloyed to fulfill specific needs. The versatility and simplicity of the Mixalloy process provide an economical alternative to other processing means in the manufacturing of high performance alloys such as dispersion strengthened alloys.
Alloy Modeling and Experimental Correlation for Ductility Enhancement in NiAl
Authors: Darolia R. , Lahrman D. F. , Field R. D. , Freeman A. J. 
Published: March 2011

ABSTRACTSingle crystals of stoichiometric NiAl and NiAl+V alloys were tested in compression and tension from room temperature to 871°C to determine deformation behavior. The dislocations were predominately <100> in the plastically deformed specimens. Attempts to ductilize NiAl by the addition of vanadium are described. The lowering of the anti-phase boundary energy by vanadium addition to NiAl, believed to promote the formation of <111> dislocations, was predicted by the all electron self consistent total electron band structure calculations. The vanadium additions caused considerable solid solution strengthening in NiAl, rendering the ternary alloys more brittle than stoichiometric NiAl.
Surface Energies of Planar Defects and Dislocation Processes in Al3Ti and Tial
Authors: Hug G. , Douin J. , Veyssiere P. 
Published: March 2011

ABSTRACTInformation on APB energy in ordered alloys is important not only to understand their mechanical properties but also to analyse conditions for phase transformation. APB surface energies are determined from dissociation distances of superdislocations both in TiAl and Al3Ti Medium and high APB energy anisotropies are found in TiAl and Al3Ti respectively. These results are consistent with phase diagram studies which predict that the APB energy vanishes in the (001) plane near the Al3Ti composition. Examples of decompositions of perfect dislocations into perfect dislocations are discussed.
Examination of Dislocation Cores in Ni3Al Using High Resolution Electron Microscopy
Authors: Crimp Martin A. , Hazzledine P. M. 
Published: March 2011

ABSTRACTHigh resolution electron microscopy has been used to study the core structure of a/2[101] and a/3<112> dislocations in Ni3Al deformed in the range of increasing strength with temperature. a/3<112> coupled SISFs were found to lie on (111) and their structure agreed well with theoretical predictions. a/2[101] superpartials were always dissociated on (111) or (111) planes while the APB plane was found to be (010). Computer simulation of dislocation core structures were found to agree well with the observed dissociations. The APB width was found to increase significantly with increasing deformation temperature near the peak yield strength temperature.
Deformation Twinning in Ordered Intermetallic Compounds
Authors: Yoo M. H. , Fu C. L. , Lee J. K. 
Published: March 2011

ABSTRACTMechanistic understanding of deformation twinning in ordered superlattice structures is reviewed, and the inter-relationships between twinning and generalized plastic flow or fracture toughness are discussed. While general discussions refer to all the fcc-based and bcc-based cubic and noncubic ordered intermetallic alloys, specific calculations of the energetic and kinetic aspects of deformation twinning are made for TiAl. The importance of the twin-slip conjugate relationship on high temperature mechanical properties is emphasized. Discussion is given of possible effects of macro- and micro-alloying on twinning propensity.
The Effect of Prestrain on Deformation of Ni3Al Single Crystals
Authors: Dowling W. E. , Gibala R. 
Published: March 2011

ABSTRACTPrestrain of bcc metals at temperatures T>0.2Tm decreases the flow stress at lower temperatures (T<O.15Tm) where the yield strength has a large negative temperature dependence. This investigation has examined the influence of prestrain on the flow stress of Ni3A1, for which the yield strength has a large positive temperature dependence above 25°C. Nickel-rich Ni3Al single crystals with axial orientations near <001> or <123> were prestrained in compression up to 20% shear strain at -196°C and subsequently compression tested at 550°C. Specimens near the <123> axial orientation were also prestrained at 550°C and then tested at -196°C. The initial flow stress of samples prestrained at - 196°C and tested 550°C was reduced up to 50% compared to samples solely compression tested at 550°C. The magnitude of the reduced flow stress and its extent as a function of plastic strain were dependent upon the amount of prestrain and orientation. Prestraining at 550°C and subsequent testing at -196°C increased the flow stress by as much as 60% over samples solely tested at -196°C. Dislocation substructures obtained from selected samples coupled with arguments based on dislocation dynamics and obstacle strengthening are used to explain the results.
Electron Microscopy Study of Fatigue Crack Initiation in Ni3Al Single Crystals
Authors: Hsiung L. M. , Stoloff N. S. 
Published: March 2011

ABSTRACTTransmission electron microscopy of single-slip oriented Ni3Al single crystals cyclically deformed at room temperature revealed a high density of dislocation dipoles and point defect clusters. The majority of the defect clusters were identified by weak-beam TEM to be of vacancy type. The observations of circular perfect dislocation loops, Frank loops, and spherical voids revealed the evidence of vacancy condensation during fatigue cycling at room temperature. Together with SEM observations of surface topography, it is suggested that fatigue crack initiation in Ni3Al single crystals can be rationalized by formation of microvoids at PSB/matrix interfaces.
The Creep Behavior of Cr Modified Ni3 Al Single Crystals
Authors: Hsu S. E. , Tong C. H. , Lee T. S. , Liu T. S. 
Published: March 2011

ABSTRACTNi-Al-Cr single crystals with 4 at% Cr and different levels of aluminum content are grown in a directional solidification facility. The crystals are creep tested at temperatures from 760°C to 860°C. Steady state, as well as transient, creep rates are measured. The results show that Cr modified Ni3 A1, when tested along the <100> direction, exhibit remarkably high values of activation energy for creep. Along with evidence from dislocation structures, it is likely that there is a change in the dislocation core structure upon Cr addition.
Fracture Modes in Ll2 Compounds
Authors: Briant C. L. , Taub A. I. 
Published: March 2011

ABSTRACTThis paper reports a study of grain boundary segregation and fracture modes in Ll2 intermetallic compounds. Data obtained on Ni3A1, Ni3Si, Ni3Ga, Ni3Ge, and Pt3Ga will be presented. It will be shown that the amount of boron segregation and its ability to improve cohesion depends on the total composition of the compound. The beneficial effects of boron can be counteracted by the presence of borides on the grain boundaries. Carbon additions also produce some improvement in ductility in Ni3Si.
Ductility and Fracture Behavior of Single Crystalline Ni3Al with Boron Additions
Authors: Heredia F. E. , Pope D. P. 
Published: March 2011

ABSTRACTLow and high temperature tensile tests were performed on single crystals of pure Ni3Al and Ni3Al+B in order to determine the effect of B additions on the ductility and fracture behavior. Tests were carried out in air at a constant strain rate of 1.3 × 10−3 s−1. The orientations tested were [001] for which the yield stress in tension is always greater than in compression, and those for which the tension/compression asymmetry is zero ([T=C]) for each particular composition. At room temperature, the results show a positive effect of B additions on both the fracture stress and on the ductility. The ductility at 800K appears to decrease monotonically with B additions. The largest ductilities are found for [T=C] at room temperature where an improvement of about 26% (resolved strain) for an addition of 0.2 at% B was obtained. However, the most dramatic increase in ductility occurs for the [001] oriented samples at room temperature where a 55% improvement was measured over that of pure Ni3Al. Fracture surfaces show a combination of massive slip, some cleavage, and heavily dimpled areas. These observations show that B additions not only increase the ductility of polycrystalline Ni3Al, as has been previously observed by many investigators, but also that of the already-ductile single crystalline material, indicating that a “bulk effect” should be added to the grain boundary strengthening effect of B when explaining the improvement in ductility of polycrystalline Ni3Al due to B additions.
Identification of Cleavage Planes in an Al3Ti-Base Alloy by Electron Channeling in the SEM
Authors: George E. P. , Porter W. D. , Joy D. C. 
Published: March 2011

ABSTRACTSelected area electron channeling patterns were used to identify the cleavage planes in a polycrystalline Al3Ti-base alloy having the L12 structure. In order to do this unambiguously in the scanning electron microscope (SEM), one needs to know that the cleavage facet from which any given channeling pattern is obtained is indeed normal to the electron beam. We accomplished this by utilizing a recently-developed technique in which an optical microscope with a short depth of focus is inserted in the SEM column and used to measure the elevations of several points on the cleavage facets. By appropriately tilting and rotating the sample, and using the optical microscope to measure elevations, it was possible to orient the facets normal to the beam. The cleavage planes in a cast and extruded alloy having an equiaxed grain structure were compared with those in a directionally-solidified (DS) alloy of the same composition. Of the eight cleavage facets examined in the DS material, six were of the {110} type and two were of the {111} type. Of the six facets examined in the cast and extruded material, two each were of the {110} and {111} types, and one each were of the {100} and {013} types. Although it cannot be said that all possible cleavage planes have been identified in this alloy, the availability of several low-strength cleavage planes apparently exacerbates its brittleness.
Directions in High Temperature Intermetallics Research
Authors: Dimiduk Dennis M. , Miracle Daniel B. 
Published: March 2011

ABSTRACTStructural intermetallic materials have undergone an evolutionary process whereby some of the materials could provide major payoffs in gas turbine engines. This maturation of select intermetallic systems has provided significant hope for making still greater advances in turbine performance through further developments in other intermetallic materials. The same maturation process has highlighted specific limitations and requirements which are key to the utilization of intermetallic systems. This paper briefly reviews some critical ground rules for high temperature intermetallics development and identifies research directions being pursued by the Air Force for advancing intermetallic materials.