bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incentives for Using LEIM in the Investigation of Corrosion Initiation on Organic Coated Alloys
Authors: Taylor S. R. , Mierisch A.M. 
Published: April 2011

AbstractLocal electrochemical impedance mapping and spectroscopy (LEIM/S) have become important tools for the investigation of local electrochemical breakdown events associated with the degradation of organically coated metals in aqueous environments. LEIM/S of organic coated metal substrates has revealed local degradation events that are distributed spatially and temporally. These observations provide support to a number of long-standing theories, as well as provide new insight into the damage process. The local changes in impedance observed at early stages of immersion support the presence of virtual pores, while the metastability of impedance peaks representing the local changes provide evidence of healing via corrosion product formation. Each of these are long-standing theories used to explain global electrochemical impedance measurements. This paper will provide an overview of some of the events observed using LEIM and examine these results in the context of recent analytical and numerical models. Models used to predict the electric field above an equipotential disk electrode support the interpretation of most experimental LEI data as being representative of chemical and physical phenomenon and not a result of measurement artifact. However, certain features may be an artifact of the finite nature of the experimental process. The interpretation of LEIM events in view of current experimental and modeling results will be discussed.
Structure and Electronic Properties of Diamond-Like Carbon and its Heat-Treatment Effect
Authors: Takai Kazuyuki , Oga Meigo , Sato Hirohiko , Enoki Toshiaki , Ohki Yoshimasa , Taomoto Akira , Suenaga Kazutomo , Iijima Sumio 
Published: April 2011

AbstractDiamond-Like Carbon (DLC) was gradually converted to the disordered graphite by means of heat-treatment (HT). According to Raman spectroscopy and x-ray diffraction (XRD), the disorder nature of the structure is modified from atomic scale sp2/sp3 disorder to disordered sp2-domain network by the migration of sp3-defects induced by HT at temperatures 200 - 400°C. The structural change increases conductivity and modifies the hopping conduction mechanism at low temperatures. The slight positive thermoelectric power for samples with graphitic domains is suggestive of carrier compensation by the competition of hole and electron carriers that originates from the inhomogeneous charge distribution caused by the difference of Fermi levels among the sp2-domains.
Microstructural Development and Properties of (1-x) wt% Ba0.55Sr0.45TiO3-x wt% MgO Bulk Ferroelectrics
Authors: Fountzoulas Costas G. 
Published: April 2011

AbstractA study was made of the relationship between the microstructure and electrical properties of the bulk ferroelectric composite materials: (100-x) wt% Ba0.55Sr0.45TiO3-x wt% MgO. The ferroelectric composites (x= 40, 60) were fabricated by dry pressing from two powder precursors: 1) Ba0.55Sr0.45TiO3 (BST) calcined in the solid state with sol-gel MgO (Sg-MgO), and 2) hydrothermal BST and MgO calcined in the solid state. The pellets were sintered at 1250, 1350 and 1450°C. The sintered microstructure, chemistry, and phase with crystallinity was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD), respectively. The density and porosity were determined by the Archimedes technique. Dielectric properties of permittivity and loss tangent were characterized by the parallel plate capacitor method.
Impedance Spectroscopy in Ferromagnetic Materials
Authors: Valenzuela Raul 
Published: April 2011

AbstractImpedance spectroscopy (IS) is a powerful characterization methodology for a wide range of electric materials such as ceramics, ferroelectrics, ion conductors, piezoelectrics, etc. In this paper, an extension of IS to the case of ferromagnetic materials is presented. In particular, the resolution of the most common magnetization processes (domain wall bulging, domain wall displacement and spin rotation) is analyzed. IS is applied to ferrites and giant magnetoimpedance in amorphous wires.
Scaling Effects in Al72Mn22Si6 Quasicrystals Deduced from the Pressure and Temperature Dependence of the Resistance
Authors: Vassiliou John K. , Otto Jens W. , Pothireddy A. , Simons E. A. 
Published: April 2011

AbstractX-ray diffraction and resistivity measurements on the Al72Mn22Si6 (Al-Mn-Si) rapidly quenched alloy are reported. The x-ray pattern shows that the alloy is essentially single phase, with a little mixture of unreacted Al. The peaks can be indexed using icosahedral vectors in the six dimensional space Z6. The resistance of thin ribbons of Al72Mn22Si6 quasicrystals has been measured as a function of temperature between 1.4 and 300 K at fixed pressures in the range 0 to 15 Kbar. Below 40 K, the resistance increases with decreasing temperature, and below 14 K, the conductivity varies as T1/2. This result is in agreement with the scaling and localization models in which spatial disorder and electron-electron correlation effects determine the electronic transport properties of the material. The value of the magnetoresistance measured at 60 KGauss and 0.34 K agrees qualitatively with the predictions of the above models. The pressure dependence of the correlation gap and the resistivity suggests that the system is in the strong coupling limit. In this regime, the functional dependence of the correlation energy on resistivity is Δ ~ ρ-2.
Electrically Active Deep Levels in ScN
Authors: Perjeru Florentina , Bai Xuewen , Kordesch Martin E. 
Published: April 2011

AbstractWe report the electronic characterization of n-ScN in ScN-Si heterojunctions using Deep Level Transient Spectroscopy of electrically active deep levels. ScN material was grown by plasma assisted physical vapor deposition and by reactive sputtering on commercial p+ Si substrates. Deep level transient spectroscopy of the junction grown by plasma assisted physical vapor deposition shows the presence of an electronic trap with activation energy EC-ET= 0.51 eV. The trap has a higher concentration (1.2–1.6 1013cm−3) closer to the ScN/Si interface. Junctions grown by sputtering also have an electronic trap, situated at about EC-ET= 0.90 eV.
Refractory Thin-Film Metallizations with Controlled Stress and Electrical Resistivity
Authors: Golecki Ilan , Eagan Margaret 
Published: April 2011

AbstractRhodium and iridium are refractory metals which possess intrinsically high electrical conductivity, and their chemical inertness enables their use at relatively high temperatures in microelectronics. However, due to the high Young's modulus of these materials, a residual tensile stress of hundreds of MPa is measured in evaporated thin films. New data is presented, demonstrating control over both the magnitude and the sign of the residual stress in such refractory thin films formed by means of ion-beam-enhanced physical vapor deposition on oxidized Si substrates. The electrical resistivity and stress are determined by controlling the substrate temperature, deposition rate and ion beam parameters. Thicker films are achieved in this manner, including films with near-zero residual stress.
Radio-Frequency Impedance Analysis of Anodic Tantalum Pentoxide Thin Films
Authors: Due~as S. , Castãn H. , Barbolla J. , Kola R.R. , Sullivan P.A. 
Published: April 2011

AbstractAnodic tantalum pentoxide is studied up to 3 GHz by using for the first time the Radio-Frequency Impedance Analysis. Over this broad frequency range we extract a better knowledge on the very physical nature of this dielectric. From impedance analysis we obtain the value of the leakage conductance in parallel to the pure capacitance. At frequencies higher than 1 MHz capacitance vanishes to zero. This behaviour appears for all the samples, independently of thickness, anodization precursor or electrode metals, suggesting that it should be due to some intrinsic property of the dielectric. The electrical response of amorphous tantalum oxide is due to dipole oscillations characterized by a constant time; when frequency is high enough, dipoles do not have time to follow the field oscillations and, as a consequence, there is not any capacitive behaviour.
Influence of Confinement on Molecular Reorientational Dynamics of Liquid Crystals: Broadband Dielectric Spectroscopy Investigations
Authors: Aliev Fouad M. 
Published: April 2011

AbstractBroadband dielectric spectroscopy has been applied for investigations of the dynamic behavior of liquid crystals (LCs) confined in porous matrices with random pores as well as in parallel cylindrical pores. We observed deep supercooling of LC in random pores. The relaxation times of the process due to the molecular rotation in deeply supercooled state are slower than at the temperatures corresponding to nematic phase by a factor of 106. This slowing down is accompanied by anomalous broadening of the dielectric spectra. For LC confined in cylindrical pores with homeotropic orientation on the pore walls we have investigated the relaxation of the librational mode. The dynamics of this mode is different from the behavior observed in investigations of relaxation due to reorientation of molecules around their short axis. The interpretation of the temperature dependencies of relaxation times of the librational mode needs the involvement of the temperature dependence of orientational order parameter. The investigations of the relaxation in thin LC layers formed on cylindrical pore walls show that the process due to rotation of molecules around their short axis (with single relaxation time for bulk LC) is the process with a distribution of relaxation times in thin layers and this process broadens with decreasing thickness of the layers.
The use of XANES and ELNES for the Characterisation of Stabilised Zirconia
Authors: McComb David W. , Ostanin Sergei , Vlachos Dimitris , Craven Alan J. , Finnis Michael W. , Paxton Anthony T. , Alavi Ali 
Published: April 2011

AbstractThe electron energy-loss near-edge structure (ELNES) and x-ray absorption near-edge structure (XANES) at the oxygen K-edge has been investigated in a range of yttria-stabilised zirconia (YSZ) materials. Analysis of near-edge structure reveals that both the crystallographic phase and the metal fraction of yttrium present can be determined directly from the oxygen K-edge data. Simulation of the ELNES/XANES was achieved using a pseudopotential based method to obtain the relaxed atomic coordinates combined with full-potential LMTO method to calculate the electronic structure.
Impedance spectroscopy study of ionic diffusion in polycrystalline ZrO2:Y2O3 solid solution
Authors: Fonseca Fábio C. , Muccillo Eliana N. S. , Muccillo R. 
Published: April 2011

AbstractThe ZrO2:Y2O3 solid solution formation has been followed by impedance spectroscopy and X-ray analysis. The experimental sequence, after mixing 8 mol% Y2O3 to ZrO2, was: attrition milling the mixture, drying, weighing, cold pressing, thermally treating at several different temperatures and times, performing the X-ray diffraction measurements at room temperature, applying metallic electrodes, and performing the impedance spectroscopy measurements in the 300°C-600°C temperature range. A good correlation was found between the decrease of the yttria main diffraction line and the increase of the stabilized zirconia main diffraction line, showing that solid solution is attained at the expenses of yttria, as expected. The impedance spectroscopy data Z(ω, T, t) show that the bulk response follows a t1/2 law, an evidence of yttrium diffusion to zirconia. Moreover, a relationship is found between the bulk resistivity and the elimination of ion blockers for increasing sintering times. The result allowed for the determination of the activation energy for the diffusion of the slowest diffusing species (Zr4+) in ZrO2:Y2O3.
The influence of filler properties on the strong PTC effect of resistivity in polymer based conducting composites
Authors: Glatz-Reichenbach Joachim , Strümpler Ralf 
Published: April 2011

AbstractPolymer based composites are very attractive materials for a plurality of technical applications. For electrical purposes the resistivity of such materials can be tuned over many orders of magnitude from highly insulating (1014&cm) to well conducting (10-3&cm) states. One particular class of polymer based composites even show a strong non-linear reversible change in resistivity with temperature between conduction and insulation. Such a pronounced effect of positive temperature coefficient of resistivity (PTCR) can be technically used, for example, in self regulating heating devices, for temperature sensing or, as a very challenging and important task, for current (i.e. over- as well as short-circuit currents) limiting and interrupting devices. The PTCR-devices act similar like fuses but repetitively, which offers technical and economical benefits.In the present work we investigate how the physical properties of the conducting filler influence the switching characteristics of the PTC material. Experimental results on resistivity and its change under active heating by Joule's losses during current flow are presented and discussed for different composites, compounded with fillers like carbon black, Ni/Ag, TiB2 or WC/Co. The strong resistance change caused by break-off and separation of particle-particle micro-contacts is driven by the very different thermal expansion coefficients of filler and matrix. It is in particular demonstrated how the heat capacity of filler-particles influences the dynamics of the micro-contact separation.
Combinatorial Molecular Layer Epitaxy of Hf Based Phosphor Oxides
Authors: Arai N. , Kim T. W. , Kubota H. , Matsumoto Y. , Koinuma H. 
Published: April 2011

AbstractA series of MHfO3: Tm (M =Ca, Sr and Ba) composition spread films and superlattices (SLs) were quickly fabricated on SrTiO3 (001) substrate in the molecular layer-by-layer growth using combinatorial pulsed laser deposition (PLD) under in-situ reflection high-energy electron diffraction (RHEED) monitoring. Crystal structures and luminescence properties of composition-spread and SLs were evaluated by the concurrent X-ray diffractometer and cathode luminescence (CL), respectively. CL properties of the films were found strongly dependent on their composition and stacking sequence. Possible effect of the stress due to the film-substrate interaction on the CL property is discussed.
Combinatorial Search for Transparent Oxide Diluted Magnetic Semiconductors
Authors: Fukumura T. , Kawasaki M. , Jin Zhengwu , Kimura H. , Yamada Y. , Haemori M. , Matsumoto Y. , Inaba K. , Murakami M. , Takahashi R. , Hasegawa T. , Koinuma H. 
Published: April 2011

AbstractDiluted magnetic semiconductor (DMS) possesses charge and spin degrees of freedom leading to their interplay promising for novel devices. DMSs based on II-VI and III-V compound semiconductors have been extensively studied so far. Recently, the oxide semiconductors doped with transition metal magnetic impurity have attracted much attention for the possible high ferromagnetic Curie temperature. Here, we overview recent studies of the transparent oxide based DMSs, ZnO, TiO2, and SnO2 doped with 3d transition metals, by using the combinatorial materials synthesis and the high throughput screening.
High Throughput X-ray Diffractometer for Combinatorial Epitaxial Thin Films
Authors: Ohtani M. , Fukumura T. , Ohtomo A. , Kikuchi T. , Omote K. , Koinuma H. , Kawasaki M. 
Published: April 2011

AbstractWe report on the development of a high throughput x-ray diffractometer that concurrently measures spatially resolved x-ray diffraction (XRD) spectra of epitaxial thin films integrated on a substrate. A convergent x-ray is focused into a stripe on a substrate and the diffracted beam is detected with a two-dimensional x-ray detector, so that the snapshot image represents a mapping of XRD intensity with the axes of the diffraction angle and the position in the sample. High throughput characterization of crystalline structure is carried out for a BaxSr1-xTiO3 composition-spread film on a SrTiO3 substrate. Not only the continuous spread of the composition (x), but also the continuous spread of the growth temperature (T) are given to the film by employing a special heating method. The boundary between the strained lattice and relaxed lattice is visualized by the concurrent XRD as functions of x and T in a high throughput fashion.
Information-rich High-Throughput Screening of Curing Formulations Via the Large Sample Array Calorimeter
Authors: Stirn Pamela J. , Hofelich Tom C. , Tamilarasan Ramasamy R. 
Published: April 2011

AbstractThis paper describes the use of an automated Large Sample Array Differential Scanning Calorimeter (LSA-DSC or LSA) for process optimization. The LSA was designed specifically for screening studies of multi-variable arrays where a large number of samples need to be examined simultaneously. It is ideal for kinetic evaluation of both biological and chemical reactions. The LSA can be used in either a temperature scanning (DSC) or isothermal (IMC) mode. An example where this equipment was used to optimize epoxy formulations will be presented. These formulations were prepared with high throughput techniques and evaluated using the LSA-DSC to determine the cure kinetics.
Combinatorial Mapping of Polymer Film Wettability On Gradient Energy Surfaces
Authors: Ashley Karen , Sehgal A. , Amis Eric J. , Raghavan D. , Karim A. 
Published: April 2011

AbstractCombinatorial methods were used for studying dewetting of thin hydrophobic polystyrene (PS) and hydrophilic poly(DL-lactic acid) (PDLA) films on chemically modified gradient energy surfaces. Substrate libraries were prepared by immersing passivated Si (Si-H surface functionality) in Piranha solution (H2SO4/H2O2/H2O) at acontrolled rate, yielding a systematic variation of solvent contact angles across the surface. Additionally, chlorosilane-treated Si surfaces were exposed to UV radiation in a gradient fashion under ozone atmosphere such that a range from hydrophobic to hydrophilic conditions was obtained across the surface (≈ 3 cm). Solvent droplet contact angles of water and diiodo methane were used to quantify the spatial variation of surface energy along one axis across the surface. Libraries of thin films of PS or PDLA coatings on gradient energy surfaces orthogonal to gradients in film thickness were screened for dewetting behavior using automated optical microscopy. Contrasting trends in the wettability of PS and PDLA were visibly apparent as a function of surface energy of the substrate. The number density of polygons of the dewet PS films was found to obey a power law relationship with both film thickness and substrate surface hydrophilicity.
Flash Photolysis of Polystyrene with Laser
Authors: Hongwei Ma , Yongjian Tang , Baoshun Cui , wende Gao , Weiming Liu , Shouwen Wang , Hong Ma 
Published: April 2011

AbstractThis paper describes the photolysis of polystyrene with 1.06μm laser. The laser dissociation is measured with mass spectrum method. It gives the mean mass value of particles, quantum value and percentage of m/e=104 vs time.
Going through Rough Times: from Non-Equilibrium Surface Growth to Algorithmic Scalability
Authors: Korniss G. , Novotny M.A. , Rikvold P.A. , Guclu H. , Toroczkai Z. 
Published: April 2011

AbstractEffcient and faithful parallel simulation of large asynchronous systems is a challenging computational problem. It requires using the concept of local simulated times and a synchronization scheme. We study the scalability of massively parallel algorithms for discrete-event simulations which employ conservative synchronization to enforce causality. We do this by looking at the simulated time horizon as a complex evolving system, and we identify its universal characteristics. We find that the time horizon for the conservative parallel discrete-event simulation scheme exhibits Kardar-Parisi-Zhang-like kinetic roughening. This implies that the algorithm is asymptotically scalable in the sense that the average progress rate of the simulation approaches a non-zero constant. It also implies, however, that there are diverging memory requirements associated with such schemes.
Atomistic Modeling of III-V Semiconductors: Thermodynamic Equilibrium and Growth Kinetics
Authors: Grosse Frank , Barvosa-Carter William , Zinck Jennifer J. , Gyure Mark F. 
Published: April 2011

ABSTRACTGrowth kinetics and thermodynamic equilibrium can both be determining factors at different stages of III-V semiconductor heteroepitaxy. We study their interplay, employing kinetic Monte Carlo simulations for the InAs(001) surface. The simulation contains atomistic details of both species, including the stability of different reconstructions and their kinetics. The behavior of the surface in thermodynamic equilibrium, including different reconstructions, is determined exclusively by extensive total energy calculations employing ab initio density functional theory. The continuous phase transition between the α2(2x4) and β2(2x4), predicted by theory, is confirmed by experiment. At full layer coverage, a recovery of the stable reconstruction is observed. The different time scales associated with As2 and In are discussed with respect to equilibrium and kinetics.
Value-In-Use of Composite Reinforcing Fibers
Authors: Wallenberger Frederick T. 
Published: April 2011

ABSTRACTThis paper analyzes the value-in-use of advanced fibers, especially of those, which are used to reinforce polymer matrix composites. Of particular interest in this regard are some recent fibers, such as (1) pure silica fibers derived from water glass, (2) oxynitride glass fibers, having the same high elastic modulus as SM carbon fibers, and (3) Kenaf, as well as other natural plant fibers, which are beginning to find commercial use in selected automotive composites.
Glass Fibers from High and Low Viscosity Melts
Authors: Wallenberger Frederick T. , Weston Norman E. 
Published: April 2011

ABSTRACTTypical commercial and experimental oxide glass fibers are made from silicate melts, which have viscosities of log 2.5 to log 3.0 poise at the forming temperatures. But, strong fibers were recently also made from melts having viscosities of 0.5 to 2.0 poise, and a sharp melting point rather than a viscosity that gradually changes with temperature. This paper analyzes the various mechanisms of fiber formation, and proposes an answer to the apparent inconsistencies. In this context, the present paper bridges recent advances in the disciplines of advanced inorganic fibers [1], composite reinforcing fibers [2, 3, 4], and fiber glass reinforcements [5].
Theory and Simulation of Texture Formation in Mesophase Carbon Fibers
Authors: Yan J. , Rey A. D. 
Published: April 2011

ABSTRACTCarbonaceous mesophases are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a range of fiber textures whose origins are not well understood. Planar polar (PP) and planar radial (PR) textures are two ubiquitous ones. A model that describes the formation process of the PP texture based on the Landau-de Gennes mesoscopic theory for discotic liquid crystals, including defect nucleation, defect migration, and overall texture geometry, is presented, solved, and validated. The computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, is presented to establish the processing conditions and geometric factors that lead to the selection of these textures. The influence of elastic anisotropy to the textures formation and structure is also characterized.