bluuebunny/crossref_metadata_2025_split huggingface dataset:
A High Stability Electrode Technology for Stacked SrBi2Ta2O2 Capacitors
Authors: Kudo J. , Nagata M. , Ogata N. , Yamazaki S. , Urashima H. , Okutoh A. , Miyoshi T. , Ishihara K. 
Published: April 2011

AbstractA high stability electrode technology with TaSiN as a barrier metal was used to fabricate a stacked SBT capacitor array on polySi plugs, and hysteresis characteristics and contact properties of the stacked capacitor were studied.
Piezoelectric Measurements with Atomic Force Microscopy
Authors: Christman J. A. , Maiwa H. , Kim S.-H. , Kingon A. I. , Nemanich R. J. 
Published: April 2011

AbstractAn atomic force microscope (AFM) is used to measure the magnitude of the effective longitudinal piezoelectric constant (d33) of thin films. Measurements are performed with a conducting diamond AFM tip in contact with a top electrode which is driven by an externally applied voltage. The interaction between the tip and electric field present is a potentially large source of error that is eliminated through the use of this configuration and the conducting diamond tips. Measurements yielded reasonable piezoelectric constants of X-cut single crystal quartz, thin film ZnO, Pb(Zr,Ti)O3 (Zr/Ti = 30/70), and nonpiezoelectric amorphous SiO2 thin films. The system was also used to measure d33 hysteresis loops for Pb(Zrx,Ti1−x)O3 thin films.
Analysis of Undoped and Ag-doped High-Tc YBCO Superconducting Bolometers Fabricated Using a Novel Anti-Reflective Coating and Photolithographic Technique
Authors: Moxey D. E. , Sharma A. , Narayan J. , Lee C. B. , Oktyabrsky S. , Muth J. 
Published: April 2011

AbstractSuperconducting transition edge bolometers have been fabricated on Ag-doped and undoped YBCO layers on Si(100) substrates using a YSZ buffer layer. We have also fabricated bolometer devices using a stacked-structure of undoped and Ag-doped YBCO material. These thin films were deposited using pulsed laser deposition (PLD). These devices were fabricated using a novel photolithographic/anti-reflective coating (ARC) process. The use of the anti-reflective coating shows no degradation in the overall quality of the superconducting film, but rather it serves as a barrier to moisture, and improves the overall optical collection efficiency of the bolometer device. At a bias of ImA, and chopping frequency of 100Hz, we have measured photoresponse as a function of device temperature, calculated responsivity, and estimated noise equivalent power (NEP) for each of the three device structures. Peak photoresponse, responsivity, and estimated NEP for the undoped bolometer device are 12μV, 0.6mV(W/cm2), and 2.03×103 W/cmHz1/2 respectively. Peak photoresponse, responsivity, and estimated NEP for the Ag-doped bolometer device are 50μV, 2.5mV(W/cm2), and 9.40×10−8 W/cmHz1/2 respectively. Peak photoresponse, responsivity, and estimated NEP for the stacked structure bolometer device are 70μV, 3.5mV(W/cm2), and 1.02× 10−7 W/cmHz1/2 respectively. These results are the first for Ag-doped YBCO bolometers, as well as for superconducting bolometers fabricated using our novel photoresist/anti-reflective coating method.
Humidity Effects and Aging Behavior in Granular Media
Authors: Restagno F. , Gayvallet H. , Bocquet L. , Charlaix E. 
Published: April 2011

AbstractWe present a study of humidity effects on the maximum stability angle in granular media. We show that a granular medium of small glass beads exhibits aging properties: the first avalanche angle increases logarithmically with the resting time of the pile. This aging behavior is found to depend on the relative humidity of the surrounding atmosphere. A short interpretation of this effect, based on a model of activated capillary condensation, is proposed.
Experimental Evidence for the Dominance of vuv Photons in Remote Hydrogen Plasma Treatments
Authors: Wilken R. , Hollander A. , Behnisch J. 
Published: April 2011

AbstractThe flux of vacuum ultraviolet (VUV) and ultraviolet (UV) photons from a hydrogen plasma was detected by fluorescence measurements of sodium salicylate sheets with and without a MgF2 window. In order to expose the samples to the same photon flux in all experiments, the power input to the microwave plasma source was adjusted. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were treated with VUV radiation or with a remote hydrogen plasma. The mass loss and the CH-absorption loss were recorded by in situ quartz crystal micro balance and by in situ IR reflection absorption spectroscopy, respectively. The VUV irradiation and plasma treatment caused similar effects in the case of PE, PP showed an increased polymer ablation in plasma treatments, and for PS a negligible loss in mass and CH absorption was detected in plasma and VUV treatments.
Arf Excimer Laser and Xe2· Excimer Lamp Induced Photochemical Fluorination of Polyimide Film
Authors: Ikegame T. , Murahara M. 
Published: April 2011

AbstractOnly one weak point of all aromatic group polyimide surface was changed to water repellency. Polyimide surface was photo-chemically modified to be fluorinate with ArF excimer laser and Xe2 · excimer lamp irradiation. To promote the photo- chemical reaction, Xe2· excimer lamp was employed to produce CFn. radical from CF4 gas. Simultaneously, ArF excimer laser was irradiated on the polyimide surface to dissociate C-H bond. Dangling bond of C was reacted with CF, radical and produced C-CF, on the polyimide surface. By this modification, polyimide surface was changed to water repellency. As a result, polyimide surface was photo-chemically modified to fluorinate with CF4 gas pressure of 100Torr, the Xe2 excimer lamp of 7mW/cm2, and the ArF excimer laser of 30mJ/cm2, 10Hz and 3000shots, the contact angle with water was 134 degrees. And chemical composition of the photo-modified polyimide surface was inspected by ATR-FTIR spectra measurement.
Effect of ion Bombardment in Polymer Surface Modification: Comparison of Pulsed High Frequency Plasma and ion Beam
Authors: Zabeida O. , Klemberg-Sapieha J. E. , Martinu L. , Morton D. 
Published: April 2011

AbstractThe energy and the flux of impinging ions are important factors which determine the properties of deposited films and of exposed surfaces (microstructure, density, hardness, roughness, stress, chemical structure, adhesion etc.). In the present work, we use a multigrid retarding field analyzer to study ion bombardment characteristics in two different systems: a pulsed microwave plasma reactor, and a cold cathode ion source. We have found that the ion energy distribution functions (IEDF) possess specific features for each mode of operation: we evaluate the shape and the maximum and the mean ion energies of the IEDF for different gases such as Ar and N2. These ion characteristics are correlated with surface restructuring of differently treated polymers (polycarbonate and polyethylene terephthalate), analyzed by XPS.
Thermophysical Properties of Fluids Measured Under Microgravity Conditions
Authors: Fecht H.-J. , Wunderlich R.K. 
Published: April 2011

AbstractThe analysis of nucleation and growth processes relies mostly on circular arguments since basic thermophysical properties necessary, such as the Gibbs free energy (enthalpy of crystallization, specific heat), the density, emissivity, thermal conductivity (diffusivity), diffusion coefficients, surface tension, viscosity, interfacial crystal / liquid tension, etc. are generally unknown with sufficient precision and therefore often deduced from insufficient linear interpolations from the elements. The paucity of thermophysical property data for commercial materials as well as research materials is mostly a result of the experimental difficulties arising from the unwanted convection and reactions of melts with containers at high temperatures. An overview will be given on the results of thermophysical property measurements during several different space flights using containerless processing methods. Furthermore, a perspective on a future measurement program of thermophysical properties supported by the European Space Agency is described. In this regard, the International Space Station is considered as the ideal laboratory for high precision measurements of thermophysical properties of fluids which help to improve manufacturing processes for a number of key industries.
Microgravity Processing of Biopolymer/Metal Composites for NLO Applications
Authors: Cuttle C.M. , Cattaneo M.V. , Gresser J.D. , Wise D.L. , Frazier D.O. , Aranda F. , Trantolo D.J. 
Published: April 2011

AbstractThe overall objective of this project is the development of NLO-active materials with optical clarity and mechanical strength. These materials are intended for laser eye protection. By combining χ2 and χ3 optical properties, the intensity of incident laser radiation may be efficiently reduced. Using an in-plane poling technique, aligned films of liquid crystal poly(benzyl-Lglutamate), PBLG, were made which showed higher second harmonic generation (SHG) values compared to quartz. Silver sols in the 10-90 nm diameter size range were complexed with tricyanovinyl aniline, TCVA, resulting in composite PBLG/Ag Sol films with higher than at least an order of magnitude of χ3 values materials such as polydiacetylenes and nitroanilines. These polymeric NLO materials offer definite advantages in terms of easy processability into films for the manufacture of the optical elements necessary for laser eye protection.
AC Modulation Calorimetry of Undercooled Liquid Ti34Zr11Cu47Ni8 and Zr57Nb5Ni12.6Al10Cu15.4: An MSL-1 Experiment Using TEMPUS
Authors: Glade S.C. , Lee D.S. , Wunderlich R. , Johnson W.L. 
Published: April 2011

AbstractAn AC modulation calorimetry (ACMC) experiment was performed on two bulk metallic glass forming alloys, Ti34Zr11CU47Ni8 (VIT 101) and Zr57Nb5Ni12.6Al10Cu15.4(VIT 106) on the recent MSL-1 shuttle flight using the TEMPUS hardware. VIT 106 exhibited a maximum undercooling of 140 K in free radiative cooling, while VIT 101 exhibited a smaller undercooling of 50 K. Specific heat measurements were done in both the stable and undercooled liquid regions. These results will be combined with further ground-based measurements in an electrostatic levitator for modeling the nucleation kinetics of these alloys and for calculation of the free energies and entropies of the undercooled liquids in these systems.
Materials for Shielding Astronauts from the Hazards of Space Radiations
Authors: Wilson J. W. , Cucinotta F. A. , Miller J. , Shinn J. L. , Thibeault S. A. , Singleterry R. C. , Simonsen L. C. , Kim M. H. 
Published: April 2011

AbstractOne major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle (SEP) events was of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated exposures can be high. Because cancer induction rates increase behind low to rather large thickness of aluminum shielding according to available biological data on mammalian exposures to GCR like ions, the shield requirements for a Mars mission are prohibitively expensive in terms of mission launch costs. Preliminary studies indicate that materials with high hydrogen content and low atomic number constituents are most efficient in protecting the astronauts. This occurs for two reasons: the hydrogen is efficient in breaking up the heavy GCR ions into smaller less damaging fragments and the light constituents produce few secondary radiations (especially few biologically damaging neutrons). An overview of the materials related issues and their impact on human space exploration will be given.
Impurity Characterization of Solar Wind Collectors for the Genesis Discovery Mission by Resonance Ionization Mass Spectrometry
Authors: Calaway W. F. , McCann M. P. , Pellin M. J. 
Published: April 2011

AbstractNASA's Genesis Discovery Mission is designed to collect solar matter and return it to earth for analysis. The mission consists of launching a spacecraft that carries high purity collector materials, inserting the spacecraft into a halo orbit about the L1 sun-earth libration point, exposing the collectors to the solar wind for two years, and then returning the collectors to earth. The collectors will then be made available for analysis by various methods to determine the elemental and isotopic abundance of the solar wind. In preparation for this mission, potential collector materials are being characterized to determine baseline impurity levels and to assess detection limits for various analysis techniques. As part of the effort, potential solar wind collector materials have been analyzed using resonance ionization mass spectrometry (RIMS). RIMS is a particularly sensitivity variation of secondary neutral mass spectrometry that employs resonantly enhanced multiphoton ionization (REMPI) to selectively postionize an element of interest, and thus discriminates between low levels of that element and the bulk material. The high sensitivity and selectivity of RIMS allow detection of very low concentrations while consuming only small amounts of sample. Thus, RIMS is well suited for detection of many heavy elements in the solar wind, since metals heavier than Fe are expected to range in concentrations from 1 ppm to 0.2 ppt. In addition, RIMS will be able to determine concentration profiles as a function of depth for these implanted solar wind elements effectively separating them from terrestrial contaminants. RIMS analyses to determine Ti concentrations in Si and Ge samples have been measured. Results indicate that the detection limit for RIMS analysis of Ti is below 100 ppt for 106 averages. Background analyses of the mass spectra indicate that detection limits for heavier elements will be similar. Furthermore, detection limits near 1 ppt are possible with higher repetition rate lasers where it will be possible to increase signal averaging to 108 laser shots.
Orientation Dependent Strength and Cross-Slip Structure of Ordinary Dislocations in Single Crystal γ-Ti-56A1
Authors: Feng Q. , H. S. 
Published: April 2011

ABSTRACTThe temperature as well as orientation dependence in anomalous hardening occurs in single crystal Ti-56AI between 673K and 1073K under single slip of ordinary dislocations. The ordinary dislocations (1/2<110]) are gliding not only on (111) plane but also on (110) plane in the temperature range where the anomalous hardening occurs in single crystal Ti-56A1. The TEM study shows that the (110) cross-slip of ordinary dislocations is a double cross-slip in nature in which first, the dislocations cross-slip from the primary (111) slip plane to (110) plane followed by cross-slipping again onto another primary slip plane. This double cross-slip leaves a pair of edge segments 'superjogs' in (110) planes. It appears that these superjogs are immobile in the forward direction and act as pinning points. Furthermore, these pinning points would act as a Frank-Read source for the double cross-slipped dislocations, which generate dislocation loops as well as dislocation dipoles. The pinning structure, multiplane dislocation loops, and dipoles of double cross-slip origin all contribute to anomalous hardening at high temperatures in this material.
Size Scaling in the Self-Immortalization of Superdislocations in the L12 Compounds Displaying the Yield Strength Anomaly
Authors: Chrzan D. C. , Uchic M. D. , Nix W. D. 
Published: April 2011

ABSTRACTA simple statistical analysis of the distribution of superkinks along a single superdislocation is presented. This analysis is then used to estimate the rate of self-immobilization of superdislocations. The self-immobilization rate decreases exponentially with increasing superdislocation length. The implications for experiment are discussed.
Processing and Characterization of Al2Ti/Al 3Ti Two-Phase Alloys
Authors: Lukitsch M. J. , Benci J. E. 
Published: April 2011

ABSTRACTSeveral buttons of each of three binary Ti-Al alloys containing nominally 70, 71 and 72 at.% Al were prepared from elemental Ti and Al by plasma arc-melting. One button of each composition was then either solution heat-treated, subjected to a two-step heat treatment, or hot forged. Each composition and material condition was then characterized using SEM/EDS and microhardness testing. The results show that while all three compositions have a predominantly two-phase, coarse microstructure in the as-cast condition, it is possible to produce an essentially single phase material through an appropriate solution heat treatment for the two lower Al content alloys. A fine two-phase microstructure can be achieved through an additional, lower temperature heat treatment step. The microhardness results show that the solution heat treatment reduced the hardness for all three compositions compared to the as-cast condition while hot forging as-cast samples increased hardness. The 70% Al alloy has the highest hardness for all four material conditions studied while the 71% Al alloy has the lowest hardness in three of the four material conditions.
Role of the Interfaces on the Activation of Slip Systems in The PST TiAl Alloy
Authors: Zghal Slim , Inui Haruyuki , Yamaguchi Masaharu , Couret Alain 
Published: April 2011

ABSTRACTThe operative slip systems in the so-called PST alloy are determined by transmission electron microscopy. Both post-mortem analyses and in situ observations are presented. It is shown that glide of ordinary dislocations and twinning are the most easily deformation modes activated at yield. The role of the interfaces on the activation of these operative slip systems is then examined and discussed.
Ab initio Simulation of Vacancy Processes in Ni3Al
Authors: Schweiger H. , Moroni E. , Wolf W. , Püischl W. , Pfeiler W. , Podloucky R. 
Published: April 2011

ABSTRACTProperties of point defects such as antisites and vacancies in Ni3A1 are studied by means of ab initio calculations for supercells. Temperature dependent quantitities such as defect formation energies are derived by means of a grandcanonical ensemble. Stimulated by experiments of residual resistivities suggesting an outstandingly large activation energy of 4.6 eV due to Al vacancies, several models for point like defects are treated in combination with calculated migration barriers for nearest neighbor jumps and also the six-jump model.
Progress in adapting the Investment Casting of NiAl
Authors: Scheppe F. , Rothe H. , Sahm P. R. 
Published: April 2011

ABSTRACTNiAl alloys offer significant advantages as structral materials in gas turbine applications due to a unique range of physical and mechanical properties. The high melting point and low RT plasticity of NiAl alloys present special problems for mold materials. Typical shell molds for advanced superalloys are very close to there application limits. On the one hand it is necessary to keep the SiO2 level as low as possible, but on the other hand the mold has to be strong enough for the cast process and weak enough to allow for the contraction of the metal during the solidification. The result of this research is the application of a SiO2 shell mold for a heat shield. To scale up these results to production and quantities will be the further work.
Deformation Behavior of Polycrystalline MoSi2 Between 495°C and 1250°C
Authors: Junker L. , Bartsch M. , Messerschmidt U. 
Published: April 2011

ABSTRACTIn order to study the deformation processes of reaction-sintered and hot pressed MoSi2, compression tests have been performed and the microstructure of the deformed samples has been investigated by optical, scanning and transmission electron microscopy. At a low strain rate of 2.5× 10−7 S−1 permanent deformation has been achieved at 1250°C. The deformation behaviour is controlled by different microprocesses within different temperature ranges. Below 1000°C, hardening occurs beyond the upper and lower yield points. Inside the grains, dislocations glide at sufficiently high stresses in a homogeneous way as well as in localized slip bands. A plateau in the dependence of the yield stress on temperaturecorresponds to the flow stress anomaly of easy slip systems in single crystals. However, since there are not enough independent slip systems to satisfy the van Mises criterion, the material does not deform homogeneously in all grains. Intergranular and intragranular cracks, which are formed after the yield point, carry an increasing part of strain at decreasing temperatures. Above 1000°C, softening occurs after the yield point. A grain boundary phase flows viscously and carries most of the deformation. Since the grains do not deform themselves, intergranular cracks develop also at high temperatures.
Tensile and Creep Rupture Properties of Co + Co3AIC0.5 Two-Phase Alloys
Authors: Ishibashi R. , Nakamura S. , Aono Y. , Miura S. , Mishima Y. 
Published: April 2011

ABSTRACTIt is expected that the κ-phase of the intermetallic compound Co3A1C0.5 would strengthen Cobase alloys used at high temperatures like the γ' -phase of Ni-base superalloys. Tensile and creep rupture properties of Co+κ two-phase alloys with κ-phase volume fractions up to 0.75 were investigated. Alloy samples made by directional solidification casting were annealed at 1573 K for 3.6 ks and at 1373 K for 28.8 ks in vacuum, followed by Ar gas cooling. Tensile tests at RT and 1073 K and creep rupture tests at 1089 K under a stress of 172 MPa were conducted with the tensile axis parallel to the solidification direction. In alloys with low κ-phase volume fraction, cuboidal K-precipitates with average particle diameters of 0.4 to 1.0 μm were observed. They were coherent with the Co(fcc) matrix with misfits of about 3%. As the κ-phase volume fraction increased, tensile strength also increased. The alloy with κ-phase volume fraction of 0.4 had a 0.2% proof stress of 817MPa, tensile strength of 1047 MPa at RT, creep rupture life of 1.43 Ms, and tensile strain higher than 10%. These strengths are better than those of the conventional Co-base alloys. However, ductility of alloys with κ-phase volume fraction larger than 0.4 decreased due to large eutectic and primary κ-phase particles.
Dislocation Dynamics Studied by Mechanical Loss in a Ni3(AI, Ta) Single Crystal at Intermediate Temperatures
Authors: Cheng B. L. , Carreño-Morelli E. , Baluc N. , Bonneville J. , Schaller R. 
Published: April 2011

ABSTRACTDislocation dynamics in Ni3AI intermetallic single crystals has been studied by mechanical spectroscopy between 300 and 700 K. It has been found that in the anomaly domain of the flow stress, which is characteristic of this material, the mechanical loss of predeformed specimens is strongly dependent on strain amplitude, predeformation level, annealing temperature and time. The results can be interpreted as a combination of two phenomena which simultaneously occur as temperature is increased from 300 K to about 500 K: exhaustion of the mobile dislocation segments (superkinks) and pinning of the screw dislocation segments via cross-slip from the (111) onto the (010) planes.