bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-Plane Thermoelectric Properties in Si/Ge Superlattices
Authors: Yang Bao , Liu Jian L. , Wang Kang L. , Chen Gang 
Published: April 2011

ABSTRACTIn this paper, a set of methods is developed to measure the Seebeck coefficient, electrical conductivity, and thermal conductivity in the cross-plane direction of thin films. The method employs microfabricated heaters, voltage and temperature sensors, and phase-lock amplifiers to determine the temperature and Seebeck voltage oscillation in the cross-plane direction of the samples, from which the thermal conductivity and Seebeck coefficient of thin films are determined simultaneously. The cross-plane electrical conductivity is also measured by a modified transmission line model. These methods are applied to Si/Ge superlattices grown by molecular beam epitaxy.
Thermoelectric structural composites and thermocouples using them
Authors: Wang Shoukai , Wen Sihai , Guerrero Victor H. , Chung D.D.L. 
Published: April 2011

ABSTRACTThe tailoring of the sign and magnitude of the absolute thermoelectric power was achieved in structural composites by the choice of the reinforcing fibers and of the particulate filler between laminae. The resulting thermoelectric structural composites included continuous carbon fiber polymer-matrix composites and short fiber cement-matrix composites. In addition, it resulted in thermocouples in the form of structural composites. The fibers and interlaminar filler impacted the thermoelectric behavior in the longitudinal and through-thickness directions respectively.
Classical Size Effect on In-plane Thermoelectric Transport at Low Dimension
Authors: Liu W. L. , Chen G. 
Published: April 2011

ABSTRACTPrevious models on low-dimensional thermoelectric investigation deal with the quasi twodimensional electron transport due to quantum confinement effect. The formation of sub-bands in quantum well requires that electron wave reflections or transmissions at the interface are strictly in the specular direction and the superimposed wave function keeps phase coherence. However, due to the interface non-ideality or roughness, electrons can lose coherence such that their transport will deviate from that described by two-dimensional quantum well limit theories. In this paper, we report a theoretical approach to investigate the classical size effect on in-plane thermoelectric transport at low dimensions. A theoretical model based on Boltzmann equation is established with interface scattering treated as partial specular and partial diffuse scattering boundary condition. With the infinite quantum well assumption, the classical size effect in the quantum-classical mixed regime is quantitatively demonstrated. Factors that affecting classical size effect, such as quantum well width and relaxation length, are discussed.
Nano Indentations Studies of WC/C and TiN/(Ti,Al)N Multilayer PVD Coatings Combined with Cross-sectional Electron Microscopy Observations
Authors: Carvalho N.J.M. , Hosson J.Th.M. De 
Published: April 2011

AbstractMultilayers of tungsten carbide/carbon (WC/C) with an amorphous structure and multilayers of titanium nitride/titanium-aluminum nitride (TiN/(Ti,Al)N) with a polycrystalline structure, prepared by physical vapor deposition, have been subjected to nanoindentation testing. The investigation has been aimed at establishing whether the load-displacement responses provides accurate information on the fracture mechanisms and whether such mechanisms can be characterized using a new technique for cross-sectional electron microscopy of the nanoindentations. Analysis of the load-displacement curves showed that they can be used to identify the cracking mechanisms occurring in the multilayers and that cross-sectioning of the nanoindentations is necessary if a more complete understanding of the multilayer coatings behavior is required.
High Quality Optical Film Formation with O2 Cluster Ion Assisted Deposition
Authors: Toyoda Noriaki , Shirai Kenichi , Terasawa Mititaka , Matsui Shinji , Yamada Isao 
Published: April 2011

AbstractHigh-quality Ta2O5/SiO2 were deposited with oxygen gas cluster ion assisted deposition at low-temperature for advanced optical filters. With gas cluster ion assisted deposition, high refractive index and very smooth surface of Ta2O5 films were realized. The optimum cluster ion energy and cluster ion current density for Ta2O5 films were found to be 7keV and 0.5μA/cm2, respectively. The structure of film was very uniform and no porous or columnar structures were observed. The surface or interfaces of Ta2O5/SiO2 films were also very flat by surface smoothing effect of cluster ion beams. Very smooth surface can be realized even though the bottom surface was rough. There was no significant wavelength shift after an environmental test, which indicates that dense oxide films were formed at low-temperature with O2 cluster ion assisted deposition.
Surface Phases of Metals on Silicon as Material for Surface Engineering
Authors: Saranin Alexander A. , Rizhkov Sergey V. , Tsukanov Dmitriy A. , Lifshits Victor G. , Zotov Andrey V. , Oura Kenjiro , Hasegawa Shuji 
Published: April 2011

AbstractTo study structural and transport properties of the surface phases on silicon, a number of adsorbate/silicon systems on Si(100) and Si(111) surfaces has been investigated using scanning tunneling microscopy (STM), reflection-high-energy-electron diffraction (RHEED) and in-situ electrical resistance measurements. Results of investigations of formation and electrical properties of Si-Al, Si-Na, Si-Ag and Si-In surface structure are presented.
CVD Diamond Synthesis on WC-Co Cutting Tool via Electrophoretic Seeding Process
Authors: Tsubota Toshiki , Okada Naoki , Ida Shintaro , Nagata Masanori , Matsumoto Yasumichi , Yatsushiro Nobumitsu 
Published: April 2011

AbstractElectrophoretic deposition was effective for the synthesis of the film type CVD diamond on the WC cutting tool without removing cobalt on the surface, although the adhesion force of CVD diamond was insufficient for the application to a cutting tool. Heat treatment after electrophoretic deposition improved the adhesion force.
The Effects of Substrate Temperature and Bias on the Structural, Mechanical and Tribological Properties of TiC films deposited by Magnetron Assisted Pulsed Laser Deposition
Authors: Phani A.R. , Krzanowski J.E. , Nainaparampil J.J. 
Published: April 2011

AbstractTitanium carbide films have been deposited using a hybrid magnetron sputtering/ pulsed laser deposition technique. One set of films was deposited at substrate temperatures ranging from room temperature to 600oC with no substrate bias, and a second set was deposited at 400°C bias voltages up to -150V. X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy were employed for structural and compositional characterization of the films, and nano-indentation hardness testing and pin-on-disc wear tests were used to evaluate the mechanical and tribological properties. All the TiC films deposited without substrate bias were highly crystalline. The films deposited with bias had significantly reduced crystallinity and non-stoichiometric film compositions. The hardness of the TiC films increased with substrate temperature from 8 GPa at room temperature to 18 GPa at 600oC, whereas the biased films had a maximum hardness of 12 GPa. The wear test data showed significantly lower friction and longer wear life for the -150V biased film.
Polyoxometallate Containing Polymeric Materials for Nanolithography and Molecular Devices
Authors: Glezos N. , Argitis P. , Velessiotis D. , Koutsolelos P. , Diakoumakos C.D. , Tserepi A. , Beltsios K. 
Published: April 2011

AbstractIn this paper, molecular compounds that come from the class of tungsten or molybdenum polyoxometallates (POM) are examined as components of polymeric materials with potential use in nanolithography and molecular devices. In the past, POMs have been used as components of DUV resists with promising results, but the metallic compound presence and their unconventional processing demands discouraged their further use in microlithography. In this paper routes for the use of these compounds in e-beam nanolithography are investigated. Different resist formulations, where poly (vinyl alcohol) and poly (methyl methacrylate) are used as host polymers, will be discussed along with the related process issues.First results from the use of polyoxometallate compounds as active elements, or components, of molecular electronic nanodevices will be also presented. The electronic transport properties of the composite materials have been tested using planar devices with contact distances of 40μm, 5μm, 50nm and 25nm. Contacts were fabricated using electron beam lithography and a lift–off process. Even at room temperature conditions conductivity peaks appear in the case of distances smaller than 25nm. These peaks are related to the energy distance of the HOMO – LUMO levels of the active molecules and the work function of the electrode used. The position and the size of the peaks depend upon the mean distance of the molecules as well as the electrode distance. On the other hand when the contact is illuminated, conductivity increases even by two orders of magnitude. This is attributed to the photon excitation of electrons from the HOMO.
Novel Approaches to Nanopatterning: From Surface Monolayer Initiated Polymerization to Hybrid Organometallic-Organic Bilayers
Authors: Henderson Clifford L. , Barstow Sean , Jeyakumar Augustin , McCoy Kendra , Hess Dennis W. , Tolbert Laren M. 
Published: April 2011

AbstractThe extendability of conventional subtractive lithographic processing using spin-coated polymeric single layer resists (SLR) faces many challenges as feature sizes in microelectronics push below 100 nm. In addition, the opacity of the polymeric materials traditionally used as SLR resins to future exposure sources presents new challenges as the radiation penetration depth decreases (e.g. 157 nm, EUVL, low keV e-beam). One solution to these problems is the use of surface imaging materials and processes. In such surface imaging methods, exposure in only a thin surface layer is used to create a pattern in a substantially thicker etch barrier layer. Conventional surface imaging approaches have mainly focused on silylation techniques which have experienced a variety of problems. This paper presents an update on two novel surface imaging methods under investigation: (1) surface monolayer initiated polymerization (SMIP) and (2) organometallic-organic bilayer resists.The SMIP process involves using a monolayer that contains a polymerization initiator functionality. Exposure of the monolayer to radiation can deactivate the initiators in selected areas and the remaining initiators can subsequently be used to directly grow patterned polymer structures. This process allows complete decoupling of the imaging properties of the monolayer from the etch properties of the polymer etch barrier. In essence, the polymerization process is used to amplify the pattern initially formed in the monolayer. Recent results are presented that demonstrate the use of x-ray photoelectron spectroscopy in conjunction with dose array experiments to analyze the sensitivity of the initiators used for this process.The other novel surface imaging method presented in this work uses organometallic-organic bilayers. In these systems, thin films of radiation sensitive organometallic precursors are used as an imaging layer in conjunction with thick organic etch barrier layers. Upon exposure, the organometallic precursor film is selectively converted to metal oxide. After exposure, the unexposed regions of the film can be developed away. Subsequent dry pattern transfer in an oxygen plasma can be used to transfer the pattern defined in the thin oxide layer through the organic etch barrier layer. Organometallic precursor films with sensitivities on the order of 70 μC/cm2 are demonstrated which result in oxide films that possess an etch selectivity of 100:1 with respect to novolac in oxygen plasmas. 500 nm line-space patterns are demonstrated as a first lithographic imaging proof-of-concept.
Nanometric Surface Patterns for Tissue Engineering: Fabrication and Biocompatibility in Vitro
Authors: Riehle M , Dalby M , Johnstone H , Gallagher J , Wood M A , Casey B , McGhee K , Affrossman S , Wilkinson C D W , Curtis A S G 
Published: April 2011

AbstractThree fundamentally different methods were used to fabricate nanometric surface features on polymers or fused silica. Phase separation of binary polymer mixes resulted in randomly distributed features whose depth and shape could be tightly controlled over large areas. Colloidal resist patterned large areas randomly and uniformly with very fine spikes. In contrast e-beam and reactive ion etching were used to create a set of regular spaced pillars on an orthogonal pattern. Some of the surfaces were replicated by in situ polymerization, solvent casting, embossing or melt molding onto polystyrene (PS) or ε–poly caprolactone (ε–PCL). Nanometric features down to 60nm were imprinted onto the polymers with high fidelity. Cells were seeded onto the nanometric surfaces and adhesion, morphology and cytoskeleton investigated. Cells respond to regular features of 170/80nm (width/depth) with reduced adhesion and changes in overall morphology and cytoskeleton. Small nanofeatures (13nm, 35nm depth) made by phase separation on the other hand increased adhesion and promoted cytoskeletal differentiation. The responses of the cells are indicative that nanometric surface features are useful modifications on scaffolds for tissue engineering or on medical implants.
Surface Functionalization of Ceramic Nanoparticles: Application to Ion-Sensing and Gas-Sensing Devices
Authors: Baraton Marie-Isabelle 
Published: April 2011

AbstractThe consequences of surface functionalization by grafting molecules like hydroxysilane, chlorosilane, and hexamethyldisilazane (HMDS) are reviewed for different types of nanoparticles including Si3N4, TiO2, and SnO2. Fourier transform infrared spectrometry is used as primary investigation tool. In terms of physical properties, these surface chemical modifications lead to improvements of the ion-sensitive FET and gas sensors characteristics. The beneficial effect of hydroxy- and chlorosilane grafted on Si3N4 used as ion sensitive membranes will be demonstrated. Then, the reduction of humidity effects on HMDS-grafted TiO2 and SnO2 nanosized powders used for screen-printed CO sensors will be reported.
AFM Studies of Fracture Surfaces of Composition B Energetic Materials
Authors: Lanzerotti Y. D. , Sharma J. 
Published: April 2011

AbstractThe characteristics of TNT (trinitrotoluene) crystals in Composition B have been studied using atomic force microscopy (AFM). The size of TNT crystals has been examined by analyzing the surface structure that is exhibited after mechanical failure of the Composition B. The mechanical failure occurs when the material is subjected to high acceleration (highg)inan ultracentrifuge and. the shear or tensile strength is exceeded. AFM examination of the topography of the Composition B fracture surface reveals fracture across columnar grains of the TNT. The width of the columnar TNT grains ranges in size from ~ 1 μm to~2 μm. Their height ranges in size from ~ 50 nm to ~ 300 nm.
Electric Field Induced Patterning of Polymer Films
Authors: Bucknall David G. , Andrew G. , Briggs D. 
Published: April 2011

AbstractBy confining a polymer film between two electrodes one of which is solid but thin enough to be flexible, a characteristic lateral morphology is produced when a strong electric field is applied across the film. A simple model to describe the observed behaviour is presented which accounts for the length scales of the observed morphology. This model demonstrates that feature sizes ranging from microns to nanometers can be obtained through selective choice of key parameters.
New organic nonlinear optical materials: dithienylethylenes
Authors: Sahraoui B. , Pluciński K.J. , Kityk I. V. , Paci B. , Baldeck P. , Nunzi J-M. , Frère P. , Roncali J. 
Published: April 2011

ABSTRACTMeasurements of the third-order susceptibilities of new dithienylethylenes in solutions using a degenerate four wave mixing technique at λ=532 nm in picosecond regime were made. From these measurements we deduced the second order hyperpolarizabilities. Optical power limiting properties of the mentioned compounds using nanosecond laser pulses in the visible range are evaluated. The dispersion of nonlinear absorption coefficients is obtained. The appropriate quantum chemical calculations are carried out.
Surface Structure and Electrochemical Polymerization of Mixed, Thiophene-Capped Monolayers
Authors: Kang Jung F. , Harrison Katherine , Kilbey S. Michael 
Published: April 2011

ABSTRACTWe have investigated the growth of polythiophene from self-assembled monolayers (SAMs) that contain pendant thiophene groups using electrochemistry and atomic force microscopy. The SAMs are formed on indium tin-oxide (ITO) by coadsorption of 11-(3-thienyl)undecyltrichlorosilane (3TUTS) and undecyltrichlorosilane (UTS). By altering the composition of the underlying monolayers we can manipulate the onset of electrochemical polymerization and affect the surface topography of the resultant polythiophene layer. Films made on SAMs that have high loadings of 3TUTS have small, distinct grains, but as the monolayers become enriched in UTS, the grain size increases; however, these films are neither as rough nor as diffuse as films formed on ITO without an underlying SAM. These experiments suggest that the electrochemical growth and structure of the polythiophene layer can be manipulated by tuning the underlying SAM.
Time-Resolved Spectral Measurement of Dendrimer Molecular Films with Rhodamine B Core
Authors: Zhou M. , Otomo A. , Yokoyama S. , Mashiko S. 
Published: April 2011

ABSTRACTWe investigated molecular thin films fabricated using novel organic materials, such as dendrimers with a rhodamine B (Rh-B) core, by a pump-probe measurement for ultrafast time-resolved spectroscopy with a time resolution of approximately 160 fs. The photon energy transfer caused by the interaction of the dendrimer molecules was measured in terms of absorbance. The wavelength of the pump light was 550 nm and a white continuum light spanning from 450 nm to 750 nm was used as a probe light. A spin-coated molecular film made of dendrimer molecules with Rh-B core has a relatively high molecular density. We measured a strong stimulated emission at a wavelength of 612 nm, whose fast decay was assumed to be caused by intermolecular interactions between the dendrimer molecules with Rh-B core. The lifetime of the molecules in the excited state was measured to be as short as 10 ps. Several types of molecular films with different molecular densities were compared, and cases with different pump energies were also discussed.
Light pulse propagation in three-dimensional photonic crystals
Authors: Kitano H. , Minami F. , Sawada T. , Yamaguchi S. , Ohtaka K. 
Published: April 2011

ABSTRACTThe phase characteristics of transmitted optical pulses in three-dimensional photonic crystals were investigated in the frequency and time domain by using the spectrally resolved cross-correlation technique. The temporal evolution of femtosecond pulses passing through polystyrene colloidal crystals exhibits a large phase distortion near the stop bands. The phase discontinuity around the band gap was observed in the frequency-domain. The phase of the transmitted pulses is found to change by φ across the band gap. The dispersion curve estimated from the phase shift shows good correspondence with those calculated from a photonic band calculation. The group velocity significantly slows down near the stop bands. A large change of the group velocity dispersion is also observed near the band edges. These results are in good agreement with the band theory.
Waste Package Environment for the Yucca Mountain Site Characterization Project
Authors: Gdowski G.E. , Wolery T.J. , Rosenberg N.D. 
Published: April 2011

ABSTRACTEnvironmental parameters that would affect the degradation of engineered materials, including waste packages and drip shields, in the potential high level nuclear waste repository at Yucca Mountain, Nevada are being characterized as part of the Yucca Mountain Project. These parameters include: temperature, relative humidity, range of water chemistry, deliquescence of salts, pH, and electrochemical potential (Eh). The likelihood of various brine compositions forming on the engineered components under repository conditions, and the implications, is discussed. Relative humidity controls the ionic strength and composition of the aqueous solutions, and hence strongly influences the corrosion processes that could occur. Studies are underway to more fully characterize the redox state of aqueous solutions in contact with engineered system components.
Gas Contaminant Mobility at Subsurface Disposal Area
Authors: Downs Wayne C. , Oh Chang H. , Housley Todd , Sondup Jeff 
Published: April 2011

ABSTRACTBeginning in 1952, waste materials, including volatile organic compounds (VOCs)contaminated with transuranic radionuclides, were generated during the fabrication, assembly, and processing of nuclear weapons components in the US Department of Energy (DOE) weapons productions complex at the Rocky Flats Plant (RFP). Following processing and containerization, drums were shipped to the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). During 1968 approximately 9,691 drums were buried there.In subsequent years, observations made during drum retrieval studies indicated that many of the drums were compromised on impact or suffered physical damage by compaction equipment shortly after burial. Corrosion also appears significant on drums buried for a few years. A large vadose-zone contaminant plume composed of solvents buried in the drums has been found beneath the burial area.Phase partitioning calculations show it unlikely that separate-phase solvent has leaked from the compromised drums deep into the soil profile or that solvents have dissolved into infiltrating water. Rather, it appears that the solvents are evaporating out of the barrels into the air phase and further partitioning from there throughout the subsurface.This paper describes the history of mixed wastes buried at the SDA, phase partitioning, and preliminary computer simulation results on gas contaminant mobility in the vadose zone.
Effect of ZrO2 on the glass durability
Authors: Lobanova M. , Ledieu A. , Barboux P. , Devreux F. , Spalla O. , Lambard J. 
Published: April 2011

ABSTRACTBorosilicate glasses were prepared with the molar composition 70 SiO2-15 Na2O-15B2O3-n ZrO2 with n ranging from 0 to 10. The glasses were studied by conventional static dissolution tests of powders at 90°C in pure water and in buffered solutions for long times (months) and short times (minutes). During the first minutes of alteration in a buffered solution, sodium is rapidly leached until its loss becomes controlled by the silicon hydrolysis. The experimental data show that the introduction of zirconium drastically reduces the initial dissolution rate (Vo) of the glass. Zirconium strengthens the silica network but also strongly modifies the porous layer morphology. In the case of glasses with small Zr contents (less than 2%), the silica dissolution rate decreases but the formation of a passivating alteration layer is also delayed. As a result, small amounts of zirconium paradoxically decrease the loss of silica but increase the final loss of sodium and boron in the static leaching tests. Larger zirconium contents (above 5%) increase the durability of the glass regarding the initial dissolution rate and the final concentration of all elements.