bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Cerium Silicate Formation on the Structural and Electrical Properties of Pt/SrBi2Ta2O9/CeO2/Si Capacitors
Authors: Lee Ho Nyung , Shin Dong Suk , Kim Yong Tae , Chow Sung Ho 
Published: April 2011

AbstractWe have fabricated metal/ferroelectric/insulator/semiconductor (MEFIS) capacitors of Pt/SrBi2Ta2O9(SBT)/CeO2/Si and Pt/SBT/Ce-Si-O/Si. The cerium silicate (Ce-Si-O) layer is formed by reaction between CeO2 thin film and SiO2/Si substrate at 1100 °C. The SBT film on the cerium silicate layer is smoother than the SBT/CeO2. The memory window of the SBT/Ce-Si-O increases to 1.4 V at a sweep voltage of ±5 V, whereas the memory window of the SBT/CeO2 is 0.8 V at the same sweep voltage.
Improved properties of TaOx films doped with Al and N
Authors: van Dover R. B. , Schneemeyer L. F. , Fleming R. M. , Werder D. J. 
Published: April 2011

AbstractSimultaneous addition of Al and N to Ta-O thin films is found to significantly improve the dielectric properties of the films. Specifically, substitution of 10-40 at. % Al for Ta along with ∼2 at. % N for O is found to decrease the density of catastrophic defects in the films, resulting in high and statistically more uniform breakdown voltages. This conclusion is based on evaluation of ∼750 individual capacitors in each experiment.
Ferroelectric C-Axis Oriented Pb5Ge3O11 Thin Films for One Transistor Memory Application
Authors: Li Tingkai , Zhang Fengyan , Hsu Sheng Teng 
Published: April 2011

AbstractOne transistor memory devices have been proposed recently. To meet the needs of one transistor memory applications, C-axis oriented Pb5Ge3O11 (PGO) thin films were prepared using metalorganic chemical vapor deposition (MOCVD) and rapid thermal processing (RTP). It was found that the nucleation of C-axis Pb5Ge3O11 phase started at a deposition temperature below 400°C and grain growth dominated at 500°C or above. With increasing annealing temperature, the remanent polarization (Pr) and coercive field (Ec) values increased, and the hysteresis loops of the Pb5Ge3O11 films were well saturated and symmetrical after the post-annealing. The C-axis PGO thin film showed good ferroelectric properties at 5V: 2Pr and 2Ec values were 2.0 - 4.0 µC/cm2 and 90 - 110 kV/cm, respectively. The films also showed excellent fatigue characteristics: no fatigue was observed up to 1 × 109 switching cycles. The retention and imprint properties have also been studied. The leakage currents of the PGO films were 2 - 5 × 10−7 A/cm2 at 100 kV/cm and dielectric constants were 40 - 70. The high quality MOCVD Pb5Ge3O11 films can be used for single transistor ferroelectric memory devices.
Molecular Dynamics Simulations of Hexadecane/Silicalite Interfaces
Authors: Webb Edmund B. , Grest Gary S. 
Published: April 2011

AbstractThe interface between liquid hexadecane and the (010) surface of silicalite was studied by molecular dynamics. The structure of molecules in the interfacial region is influenced by the presence of pore mouths on the silicalite surface. For this surface, whose pores are the entrances to straight channels, the concentration profile for partially absorbed molecules is peaked around 10 monomers inside the zeolite. No preference to enter or exit the zeolite based on absorption length is observed except for very small or very large absorption lengths. We also found no preferential conformation of the unabsorbed tails for partially absorbed molecules.
Recent Advances in Plasma Deposition of Functional Coatings on Polymers
Authors: Martinu L. , Wertheimer M. R. , Klemberg-Sapieha J. E. 
Published: April 2011

AbstractPlasma enhanced chemical vapor deposition (PECVD) is increasingly being applied for the fabrication of functional coatings on polymeric substrates. This presentation briefly reviews the energetics of plasma-surface interactions leading to the deposition of films for different applications such as optical coatings, barriers against gas and vapor permeation, and protective coatings for space. Particular emphasis is placed on the formation and characterization of a relatively wide (tens of nm) interfacial region (“interphase”) between the coating and the polymer, its role in adhesion, and in optical, mechanical and other functional porperties of thin film systems on plastic substrates.
Plasma Treatment of Polymers for Improving Al Adhesion
Authors: Lamendola R. , Matarrese E. , Creatore M. , Favia P. , d'Agostino R. 
Published: April 2011

AbstractPET and Kapton thin films have been plasma processed in order to increase sputtered aluminum adhesion. The effect of different plasma feedings, such as NH3, O2, and He, has been evaluated on polymer/metal adhesion and on chemical modifications of polymer surface at different plasma power and treatment time. The chemistry at polymer/metal interface has been studied in order to find the suitable experimental conditions for transferring the plasma process to industrial scale.The role of acid-base reactions in promoting Polymer/Aluminum adhesion has been investigated. Surface composition has been investigated by X-ray Photoelectron Spectroscopy; adhesion measurements have been accomplished by 180° Peel Test.
Inner Pore of Porous Fluoropolymer to Hydrophilic by using UV Light and H20 Vapor
Authors: Ito Shinsuke , Murahara Masataka 
Published: April 2011

AbstractInner pores of porous PTFE was modified photochemically by using ArF excimer laser for improvement of water permeability. In this study, two modification methods are described. One is using ethanol solution, and another is H20 vapor as a reaction gas. These reaction sources were employed for modification of inner pores. In the case of using ethanol solution, the modified sample indicates both hydrophilication and oleophilication. On the contrary, the hydrophilic groups are substituted into the inner pore with H20 vapor. The hydrophilication of modified samples were evaluated by the measurement of contact angle with water and water permeability. The substituted OH radicals were inspected by ATR-FTIR measurement.
Gravitational Effects on Mercuric Iodide Crystal Growth
Authors: Steiner Bruce , Berg Lodewijk Van Den , Laor Uri 
Published: April 2011

AbstractGravity can affect the physical vapor growth of mercuric iodide in two distinct ways. First, gravity will induce convection during growth, which strongly mixes residual impurities and any elementary gases resulting from imperfect stoichiometry, either of which can then form precipitates in the growing crystal. Second, gravity loads the resulting crystal, which is particularly soft while still hot, especially in the absence of precipitates. We have investigated the effects of these processes on the resulting crystalline regularity and the effects of various types of irregularity, in turn, on performance.High resolution synchrotron x-radiation diffraction imaging of three generations of crystals, grown both in microgravity and in full gravity, provide graphic evidence of the influence of gravity on mercuric iodide crystal growth. These images tie together the results of other characterization studies, identifying the crystallographic sources of the observed property enhancement in microgravity. The first process, convection, is found to be particularly important, both in its influence on observed crystalline regularity and in the resulting electronic performance of detectors made from these crystals.As a result of these investigations, the crystalline regularity and performance of terrestrial crystals has been substantially improved, although the resulting crystals have not yet achieved parity with the performance of crystals grown in microgravity. We propose new experiments in microgravity for property optimization.
Zeolite Crystal Growth in Space
Authors: Sacco A. , Bac N. , Warzywoda J. , Rossetti G. , Valcheva-Traykova M. 
Published: April 2011

AbstractThe extensive use of zeolites and their impact on the world's economy has resulted in many efforts to characterize their structure and improve the knowledge base for nucleation and growth of these crystals. Zeolite crystal growth (ZCG) experiments have been conducted in space by many researchers. The results have been varied with little overall constancy with respect to the types of zeolites grown, the procedures used, and methodologies employed for comparison of terrestrial and microgravity processed crystals. Results from this laboratory have indicated that solutions must be mixed in space, and that the nucleation mechanism as well as the growth mechanism is affected by the “suppression” of fluid motion. Earlier flight experiments (STS-43, STS-50 and STS- 57) indicated that by controlling the nucleation event, the size of the crystals could be increased with improved structural quality compared to the ground-based controls. This was hypothesized to be the result of hindrance of the solution/dissolution mechanism caused by reduced fluid motion. USML-2 (STS-73) zeolite experiments were designed to further enhance the understanding of nucleation and growth of zeolite crystals, while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, and Silicalte were grown during the 16-day United States Microgravity Laboratory number 2 (USML-2) mission. All zeolites were successfully grown in the 16 day mission. The zeolite A and X crystals were in general larger in dimension (10-50%), but not substantially different in crystal perfection as measured by their lattice parameters. However, They were significantly smoother as indicated by AFM. Zeolite β as well as Silicalite were only slightly larger in size but, appear to have different distributions of Aluminum atoms as determined by selective catalytic reactions.
A Testbed for Testing Materials Properties in Space
Authors: Landis Geoffrey A. , Bailey Sheila G. , Sextont Andrew 
Published: April 2011

AbstractThe Photovoltaic Engineering Testbed (PET) is a facility to fly on the International Space Station to test advanced solar cell types in the space environment. The purpose is to reduce the cost of validating new technologies and bringing them to spaceflight readiness by measuring them in the in-space environment. The facility is scheduled to be launched in 2002.
High-Temperature Deformation of Uniaxially Aligned Lamellar TiAl/Ti3Al
Authors: Heinrich H. , Abbächerdi V. , J. D. , Kostorz G. 
Published: April 2011

ABSTRACTUniaxially aligned polysynthetically twinned two-phase TiAl/Ti3Al material is produced by induction zone melting and deformed in uniaxial compression. Above 1000 K the strain rate sensitivity is independent of the lamellar orientation and increases strongly with increasing deformation temperature. Results for the strain rate sensitivity parameters are somewhat lower than those obtained for γ-TiAl single- and polycrystals. If the lamellae are oriented parallel or perpendicular to the deformation axis, the flow stress decreases with increasing strain. After plastic deformation the dislocation density in the lamellae is remarkably low indicating recovery processes. At the lamellar interfaces misfit dislocations and periodic arrangements of dislocations with Burgers vectors inclined to the lamellar boundaries are found. In contrast to deformation at lower temperatures, deformation twinning is rare.
Elastic and Plastic Properties of Gamma + Laves Phase In-situ Composite Alloys Using Nanoindentation Techniques
Authors: Weaver M. L , Stevenson M. E , Shamsuzzoha M. , Ott R. D. , Brady M. P 
Published: April 2011

ABSTRACTIn the present study, the local elastic and plastic properties of the γ- TiAl and the Laves phases have been investigated in a series of γ + Laves alloys using room-temperature compression, Vickers microhardness, and nanoindentation with an emphasis on elucidating the local property changes in γ + Laves alloys deformed at room temperature. This study shows that nanoindentation can be used to provide useful information on plastic flow in multiphase intermetallic alloys.
The Character of Steps on Gamma/Alpha-2 Interfaces in a Low Misfit Lamellar TiAl-Based Alloy
Authors: Shang P. , Cheng T.T. , Aindow M. 
Published: April 2011

ABSTRACTThe defect character of steps on lamellar γ/α2 interfaces in a quinternary TiAl-based alloy has been studied using high resolution transmission electron microscopy. The interfaces consisted of atomically flat coherent terraces separated by interfacial steps across equal even numbers of {111}γ and (0002)α2 planes. Circuit mapping was used to identify the Burgers vectors of these steps from lattice images obtained at [101]γ and [110]γ zone axes. It was found that the Burgers vectors exhibited by the two-layer steps are different from those reported previously and are consistent with those expected for perfect disconnections as described by Pond's topological theory of interfacial defects, and not with the usual partial dislocation model.
The Mechanical Properties of FeAl
Authors: Baker I. , George E. P. 
Published: April 2011

ABSTRACTIn the last few years, considerable progress been made in obtaining reproducible mechanical properties data for binary FeAl alloys. Two sets of observations are the foundation of this progress. The first is that the large equilibrium vacancy concentrations that exist in FeAl at high temperature are easily retained during cooling, and that these strongly affect the low-temperature mechanical properties. The second is that room-temperature ductility is adversely affected by water vapor. The purpose of this paper is to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed from the discovery of the above two effects.
High Temperature Corrosion of Spray-Atomized FeAl (40at.%) Based Alloys:Immersed in a Molten Salt Mixture of V2O5-Na2SO4
Authors: Amaya M. , Lavernia E. J. , Martinez L. 
Published: April 2011

ABSTRACTWe studied the high temperature corrosion of spray atomized and deposited FeAl40at% based intermetallic alloys immersed in a molten salt mixture of 80%V2O 5+20%Na2SO4 (wt%) over the temperature range of 600–900°C. Experiments were realized by the weight loss method and the potentiodynamic polarization electrochemical technique in three different samples: FeA140at%, FeA140+0.lat%B and FeA140+0.lat%B+10at%A12O3. Measurements of weight loss and corrosion current density as a function of the molten salts temperature were obtained and discussed in terms of the passive layer morphology and corrosion products formed during the tests. It was found that the iron aluminide doped with boron and reinforced with alumina particulate was more corrosion resistant in the test temperature range. The weight loss experiments revealed that at 700°C all alloys developed maximum corrosion rate. This behavior was related with the dissolution of protective oxide layer on metal base due the formation of vanadate phases which are highly corrosive at this temperature.
Direct Measurement of Dislocation Exhaustion Rates During Plastic Deformation of Ni3Al Compounds
Authors: Matterstock B. , Martin J. L. , Bonneville J. , Kruml T. 
Published: April 2011

ABSTRACTTwo methods of repeated transients (stress relaxation and creep) which can be performed during straining at a constant strain rate are recalled together with the way the results are interpreted. The repeated creep method has been adapted to Ni3A1 compounds for which the amount of creep strain during the second creep could not be detected so far. Because of a small stress increase between creeps, it is possible to measure microscopic activation volumes, dislocation exhaustion rates and strain hardening coefficients. Results in Ni3A1 polycrystals and Ni3(AI,Hf) single crystals are presented. Orders of magnitude of dislocation exhaustion rates are given. They are particularly high in Ni3A1 as compared with other materials. They compare well with the work hardening coefficient and with total dislocation densities measured by electron microscopy.
Constitutional and Thermal Defects in Nickel Aluminides
Authors: Korzhavyi P. A. , Abrikosov I. A. , Johansson B. 
Published: April 2011

ABSTRACTThe formation energies of intrinsic point defects and the interaction energies of possible defect pairs in NiA1 are calculated from first principles within an order-N, locally self-consistent Green's function method in conjunction with the multipole electrostatic corrections to the atomic sphere approximation. The theory correctly reproduces the ground-state properties of the off-stoichiometric NiAl alloys. The constitutional defects (antisite Ni atoms in Ni-rich and Ni vacancies in Al-rich NiAl) are shown to form ordered structures in the ground state, in which the defects of the same kind tend to avoid each other at the shortest separation distance on their sublattice. A mean-field theory is applied to calculate the equilibrium concentrations of thermal defects. The statistics of thermal defects is interpreted in terms of dominant composition-conserving complex defects which are shown to be triple defects in Ni-rich and nearly stoichiometric NiAl. In the Al-rich region a novel thermal excitation dominates where two constitutional Ni vacancies are replaced by one antisite Al atom. The number of vacancies, as well as the total number of point defects decrease with temperature in Al-rich NiAl. The boundary between the two regions is treated analytically. The vacancy concentration exhibits a minimum in its temperature dependence at the boundary. Similar analysis is applied to study constitutional and thermal defects in Ni3Al. The calculated effective vacancy formation energy in Ni3Al as a function of concentration is in excellent agreement with recent experimental data.
Ideal Cleavage Fracture of Transition-Metal Silicides: A Comparison Analysis
Authors: Yoo M. H. , Yoshimi K. 
Published: April 2011

ABSTRACTA simple empirical model for the ideal cleavage energy, resulting from a rigid-body separation, is proposed in terms of four variables, viz., the elastic stiffness constant, the interplanar spacing, and two adjustable length parameters. The ratio of these parameters is assessed based on the available results of ab-initio slab-supercell calculations. Ideal cleavage energies and stress intensity factors of transition-metal silicides are estimated, and the available fracture toughness data are discussed.
Microsample Testing of Single Crystalline Ti-52 at%Al and Ti-55.5 at%Al
Authors: Zupan Marc , Dimiduk D. M. , Hemker K. J. 
Published: April 2011

ABSTRACTDislocation activity in two-phase commercial TiAl alloys occurs most readily in the γ-TiAl phase, and measurements of the CRSS of single crystalline γ-TiAl provides a solid foundation for understanding the mechanical performance of these alloys. Single crystals of γ-TiAl with greater than 54.5 at%Al have been grown using the optical float zone crystal growing technique, but single crystals with lower Al content, closer to that of commercial alloys, have not. In the present study, polycrystalline ingots of Ti-52 at%Al have been heat treated to form very large grains, and microsample tensile specimens, which have a nominal gage cross-section of 250μm × 300μm, a gage length of 250μm and an overall length of 3 mm, have been machined from within single grains. Microsample high-temperature stress-strain curves for Ti-55.5 at%Al single crystals oriented along the [001] and [010] are presented. Tensile tests results for Ti-52 at%Al tested at 1073K along the [237], [173] and [344] orientations will also be discussed.
Changes in the Degree of LRO in B2-Ordered Intermetallic FeAl
Authors: Rohrhofer K. , Lang H. , Rosenkranz P. , Kozubski R. , Püschl W. , Pfeiler W. 
Published: April 2011

ABSTRACTChanges in the degree of long-range order (LRO) have been investigated in B2-ordered intermetallicFe-44.8at%Al by electrical resistivity measurement (resistometry). Order variations were observed during isochronal annealing for different states of initial thermal treatment. A complicated behaviour of resistivity changes with temperature is observed when starting with a small degree of disorder. Very slight re-ordering is found already at about 470K and is surprisingly followed by a slight disordering above 530K. Only for very long annealing times the expected ordering tendency is observed in this temperature range. Above 710K re-ordering is continued and reversible equilibrium changes of order with temperature are observed above 830K.
Point Defect Characterization in CoAl Using Positron Annihilation
Authors: Puff Werner , Logar Bernd , Balogh Adam G. 
Published: April 2011

ABSTRACTVacancy-like defects in CoAl in the composition range 48.5 at.-% <Cco, < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. The values of the positron lifetime and the S-parameter decrease with increasing Co concentration. After quenching from 1400°C or 1600°C an increase in the positron parameters isobserved. Long-time annealing of the Co-rich sample shows a dramatic decrease of the positron lifetime to the expected bulk lifetime.
High-Temperature Creep of Nb-Al-V Alloys
Authors: Rong Tie-Sheng , Aindow Mark 
Published: April 2011

ABSTRACTNb-15A1-20V alloys with about 45% by volume of an A15 phase in a B2 matrix have been subjected to creep deformation at temperatures between 1000°C and 1200°C and stresses from 80 MPa to 240 MPa in vacuum. The creep curves show a rapid transition from primary to steady-state creep with a well-defined activation energy. Microstructural observations show that the creep deformation occurs mainly in the B2 matrix and is controlled by dislocation mechanisms. Samples which had been coldrolled and annealed to reduce the size of A 15 precipitates and increase the yield strength were found to have lower creep resistance than those with unrefined microstructures. The significance of these observations for the creep mechanisms is discussed.
An Investigation of Point Defects in NiAl Using Positron Annihilation Techniques
Authors: Puff Werner , Logar Bernd , Balogh Adam G. 
Published: April 2011

ABSTRACTVacancy-like defects in NiAl in the composition range 47 at.-% < CNi < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. Isochronal annealing of samples quenched at 1600°C and after proton irradiation show that the induced defects are quite different.
Phason Strain In AL70NI10CO20 Decagonal Quasicrystal
Authors: Matsuo Y , Yamamoto K , Ohshima K , Ishii Y 
Published: April 2011

AbstractThe peak broadening and peak positions of Bragg reflections in a single-phase decagonal Al70Ni10Co20 quasicrystal has been studied by the synchrotron X-ray diffraction technique at SPring-8. Full-widths at half-maximum (FWHM) of the Bragg reflections along the longitudinal direction (L) and transverse direction (TI) which is perpendicular to L-direction in an aperiodic plane have linear Q⊥, dependence. This means that the Al70Ni10Co20 decagonal phase has random phason strains. On the other hand, another transverse direction (T2), which is perpendicular to the aperiodic plane, have linear Q, dependence. So the single crystal has some distortion of mosaics to the periodic layer stacking. Notable peak shifts from ideal Bragg peak positions were not observed.