bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlocal Polarizabilities and the AB Initio Calculation of Surface Optical Properties of Gaas (110)
Authors: Wijers C.M.J. , De Boeij P.L. 
Published: April 2011

ABSTRACTWe have calculated the reflectance anisotropy for the GaAs (110) surface using the discrete cellular method. This method extends the range of application of standard discrete dipole calculations by incorporating nonlocal polarizabilitites. The method adds a second quantum mechanical channel of nonlocality, which turns out to be necessary and yields very good agreement between theory and experiment.
Effect of Fe on Sintering of Al2O3-MgO-Fe2O3 Spinel
Authors: Kharissova O.V. , Aguilar J.A. , Ortiz U. 
Published: April 2011

AbstractThe influence of Fe on the microstructure of Al2O3-MgO-Fe2O3 spinel is described in this work. Heating a mixture of initial oxides in an electric furnace at 1400°C for 15 hrs produced the spinel. A ternary diagram for concentration ranges: Al2O3 (5-75 mol%), MgO (10-80 mol%), and Fe2O3 (3-70 mol%) summarize the constitution of this spinel. Amount, composition and weight ratios of each phase were determined by X-rays powder diffraction.Microstructure of specimens was characterized by scanning electronic microscopy and Xray spectrometry. Distribution, size, shape of phases and pores were examined. Hardness measurements of spinel completed this study.
Phase Separation and Elastic Fields: Three Dimensional Simulations of a Phase Field Model
Authors: Orlikowski Daniel , Sagui Celeste , Somoza Andrds , Roland Christopher 
Published: April 2011

AbstractThe effects of long-range elastic fields on the phase separation process of three- dimensional binary alloy systems was investigated with large-scale Langevin simulations. The elastic effects incorporated in the model are the result of anisotropy and dilational misfits introduced via inhomogeneities in the elastic constants of the constituents. The domain morphology obtained is readily understandable in terms of selection criterion for the shape and/or orientation of the domains, and is based on the different shear moduli that are present in the system. Coarsening mechanisms were found to be a combination of the classical Ostwald ripening mechanism and the elastically-driven coalescence of domains. Other aspects of the coarsening process such as dynamic scaling of the structure function is presented.
Microdynamic Mechanisms of Crystal Growth Under Applied Electric Fields
Authors: Jiao Y.N. , Takamori S. , Ohsawa Y. , Arakane G. , Sato A. 
Published: April 2011

AbstractOn the basis of the model of atomic cluster jump theory, a microdynamical model of crystal growth rate was developed under an electric field. Theoretical analysis indicates that the crystal growth rate is dependent on not only the nature of the metal, the undercooling and so on but also the applied electric fields. Moreover, a novel model, which shows the effect of an applied electric field on the solute distribution, the constitutional undercooling and the temperature distribution at solid/liquid interface during unidirectional solidification, has been established theoretically. Analytical results show that the electrotransport of solute strongly influences the solute distribution and then changes the constitutional undercooling and the temperature distribution. But all changes are connected with the electric current direction of the applied electric field (positive or negative).
Growth of Lamellar Products During Discontinuous Solid State Reactions
Authors: Zieba P. , Gust W. 
Published: April 2011

AbstractThe nucleation, growth and dissolution of lamellar precipitates formed due to discontinuous solid state reactions like: discontinuous precipitation, coarsening and dissolution, are reviewed. Emphasis is given on recent studies based on analytical electron microscopy in describing the microchemistry, andin situelectron microscopy for revealing the morphological features of the reactions.
Formation and Evolution of Three Dimensional Structures in the Cu/Sn/Si(111) System
Authors: Hu Qin , Mitchell I. V. , Zinke-Allmang M. 
Published: April 2011

AbstractCopper is a prevalent contaminant in silicon device fabrication. Since Cu has high solubility in Sn, we are exploring the use of Sn to form Cu-Sn surface alloys as a means to inhibit Cu diffusion into Si substrates. Cu/Sn/Si (111) samples were prepared by MBE at 100°C, then annealed at temperatures between 300°C and 600°C. Resultant surface structures were imaged by AFM and SEM. AES and EDX were used to investigate the composition of two differently shaped clusters that formed after annealing. Etching with dilute HCI solutions was used to seek the chemical origin of various surface morphologies. The results are compared with those from Sn/Si and Cu/Si samples. A possible model for the evolution of 3-D structures in the Cu/Sn/Si(111) system will be presented.
Ion-Enhanced Dry Etching of Magnetic Multilayers: Post-Etch Cleaning and Effects of UV Illumination
Authors: Cho H. , Lee K. P. , Jung K. B. , Sharifi F. , Marburger J. , Pearton S. J. 
Published: April 2011

AbstractPatterning of magnetic multilayer structures of the type used for MRAMs (e.g. NiFeCo/CoFe/Cu/CoFe/NiFeCo) is generally performed with ion milling, but this can degrade the coercivity of small (micron-size) MRAM elements and lead to sidewall redeposition. In high ion density reactive plasmas (Cl2/Ar) it is possible to produce ion-enhanced desorption of otherwise involatile halogenated reaction products, and achieve practical etch rates (∼600 Å/min) for the multilayers. However, removal of the chlorinated etch products from the feature sidewalls is critically important to avoid corrosion. We have used de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas for removal of these etch residues. Some slight degradation in magnetization was observed in O2 plasma treated structures, but the other cleaning procedures produced no change in magnetic properties and excellent long-term stability. UV illumination of the sample surface during etching is also found to enhance etch rates, as has been reported previously for room temperature etching of Cu.[1]
Kev Ion Beam Induced Surface Modification of Sic Hydrogen Sensor
Authors: Muntele C. I. , Ila D. , Williams E. K. , Poker D. B. , Hensley D. K. 
Published: April 2011

AbstractSilicon carbide, a wide-bandgap semiconductor, is currently used to fabricate an efficient high temperature hydrogen sensor. When a palladium coating is applied on the exposed surface of silicon carbide, the chemical reaction between palladium and hydrogen produces a detectable change in the surface chemical potential. Rather than applying a palladium film, we have implanted palladium ions into the silicon face of 6H, n-type SiC samples. The implantation energies and fluences, as well as the results obtained by monitoring the current through the sample in the presence of hydrogen are included below. The exposure to hydrogen of this kind of sensor while monitoring the current flow with respect to time, has revealed a completely different behavior than the samples that have Pd deposited as a surface layer.
Modeling Metal Thin Film Growth under IPVD Conditions using Molecular Dynamics Rates in a Level Set Approach
Authors: Hansen U. , Rodgers S. , Nemirovskaya M. , Jensen K. F. 
Published: April 2011

AbstractWe present a recently developed method for modeling ionized physical vapor deposition. Using molecular dynamics techniques we examine the surface adsorption, reflection and sputter reactions taking place during ionized physical vapor deposition. We predict their relative probabilities and combine the information obtained from molecular dynamics into a transport model incorporating all effects of re-emission and re-sputtering. This provides a complete growth rate model that allows the inclusion of energy and angular dependent surface reaction rates. As an example, the method is applied to growth of an aluminum film under different deposition conditions.
Novel Defects and Anisotropic Vacancy Diffusion on Reconstructed Surfaces
Authors: De La Fuente O. Rodríguez , González M. A. , Rojo J. M. 
Published: April 2011

AbstractSTM and molecular dynamics simulations are used to study Au(001) 5×25 reconstructed surfaces after Ar+ bombardment at 600 eV and ion doses from 0.05 to 1 ML+. Surface 2D dislocation dipoles, identified as such in a previous investigation, are shown to have dislocation properties and to be formed by anisotropic diffusion of surface vacancies along the ridges of the reconstructed topmost layer. A new vacancy diffusion mechanism involving intermediate states with de-localized vacancies is identified. Increasing ion fluences is shown to lead to the formation of vacancy islands that are nucleated at the dislocation dipoles.
Microcharacterization of Heterogeneous Specimens Containing Tire Dust
Authors: Camatini Marina , Corbetta GAI M , Crosta Giovanini F , Dolukhanyan Tigran , Giuiani Giampaolo , Sung Changmo 
Published: April 2011

AbstractThis work is focused on dust or debris produced by the wear of tire tread. Two problems are addressed, which are solved by analytical electron microscopy (AEM): characterization of tire debris and identification of tire debris particles in a heterogeneous specimen. The characteristic morphology, microstructure and elemental composition of tire debris can all be determined by AEM. The scanning electron microscope (SEM) shows that the surface of a tire debris particle has a typical, warped structure with pores. The characteristic elements of tire rubber are S and Zn, which are detected by energy dispersive X ray (EDX) spectroscopy. The identification of rubber particles in heterogeneous debris containing talc and produced by a laboratory abrader is possible by the analytical SEM. Transmission electron microscope images, EDX spectra and selected area electron diffraction patterns characterize tire debris at the sub–micron scale, where the material can no longer be treated as homogeneous.
Microdiffraction, EDS, and HREM Investigation for Phase Identification With the Electron Microscope
Authors: Ruterana P. , Redjaïmia A. 
Published: April 2011

AbstractAbstract: For micro or nanophase identification, the ideal method is electron microscopy which combines experimental technique and theoretical analysis in order to solve the problem which is typical in non homogeneous materials. In this work, two heterogeneous materials have been investigated: a Fe- 22Cr - 5Ni -0.3Mo - 0.03C (wt%) duplex stainless steel and a 6H-SiC reinforced Al-Cu alloy fabricated by the Ospray technique followed by extrusion and aging. This aging often gives rise to the precipitation of intermetallic compounds some of which can be new phases. Using microdiffraction, EDS and HREM, it was possible to identify two new phases: the orhorhombic τ phase in the heat treated duplex steel and the tetragonal Al7Cu3Zr2 in the reinforced aluminium copper alloy
A New Approach Towards Property Nanomeasurements Using In Situ TEM
Authors: Wang Z.L. , Poncharal P. , De Heer W.A. , Gao R.P. 
Published: April 2011

AbstractProperty characterization of nanomaterials is challenged by the small size of the structure because of the difficulties in manipulation. Here we demonstrate a novel approach that allows a direct measurement of the mechancial and electrical properties of individual nanotube-like structures by in-situ transmission electron microscopy (TEM). The technique is powerful in a way that it can directly correlate the atomic-scale microstructure of the carbon nanotube with its physical properties, providing an one-to-one correspondence in structure-property characterization. Applications of the technique will be demonstrated on mechanical properties, the electron field emission and the ballistic quantum conductance in individual nanotubes. A nanobalance technique is demonstrated that can be applied to measure the mass of a single tiny particle as light as 22 fg (1 f= 10−15).
Ion-Implanted Amorphous Silicon Studied by Variable Coherence TEM
Authors: Cheng J-Y. , Gibson J. M. , Voyles P. M. , Treacy M. M. J. , Jacobson D. C. 
Published: April 2011

AbstractAmorphous silicon formed by ion-implantation of crystalline silicon is investigated with the use of VC-TEM (variable-coherence transmission electron microscopy). This technique is sensitive to medium-range-order structures. The results from high-energy Si implanted samples showed a striking similarity to sputtered amorphous silicon. We found that both ion-implanted and sputtered samples have paracrystalline structures, rather than the expected continuous random network (CRN). We also observed the structural relaxation of the ion-implanted amorphous silicon after ex-situ thermal annealing towards the random network. The more disordered structures are favored and a large heat of relaxation is released as the temperature increases. Finally, we show some preliminary results on the structural variation with the sample depth.
Investigating Atomic Scale Phenomena at Materials Interfaces With Correlated Techniques in STEM/TEM
Authors: Browning N. D. , Nicholls A. W. , James E. M. , Arslan I. , Xin Y. , Kishida K. , Stemmer S. 
Published: April 2011

AbstractA complete understanding of the complexities behind the structure-property relationships at materials interfaces requires the structure, composition and bonding to be characterized on the fundamental atomic scale. This level of characterization is beyond the scope of a single imaging or microanalysis technique and so to solve practical interface problems, correlation between multiple techniques must be achieved. Here we describe recent advances in the JEOL 2010F 200kV field-emission STEM/TEM that now allow atomic resolution imaging and analysis to be obtained in both TEM and STEM mode and discuss two applications of these techniques
Characterization of Intergranular Phases in Doped Zirconia Polycrystals
Authors: Evans N. D. , Imamura P. H. , Bentley J. , Mecartney M. L. 
Published: April 2011

AbstractAnalytical electron microscopy at high spatial resolution in a scanning-transmission mode has been used to investigate the effects of glassy or crystalline material additions on grain boundary chemistry in yttria-stabilized zirconia polycrystals. Powders of additive phase were mixed into 3-mol% yttria-stabilized tetragonal zirconia polycrystals (‘3Y-TZP’) or 8-mol% yttria-stabilized cubic zirconia polycrystals (‘8Y-CSZ’). Zirconias processed without additive phases were also examinedWithout additives, grain boundaries were depleted in zirconium and enriched in yttrium. In 3Y-TZP with I wt% borosilicate glass, silicon was observed only at triple points, but not in grain boundaries. In 3Y-TZP with 1 wt% barium silicate glass, barium was observed both along grain boundaries and at triple points, whereas silicon was detected only within the triple points. This suggests either the composition of the additive phase at the grain boundary is different from that at the triple points, or that barium ions segregate to grain boundaries during processing. In 8Y-CSZ with I wt% silica, silicon was observed in grain boundaries by an EDS spatial differencing technique. In 8Y-CSZ with 10 wt% alumina, EDS revealed aluminum at all grain boundaries examined
Electron Backscatter Diffraction: A Powerful Tool for Phase Identification in the SEM
Authors: Michael J. R. , Goehner R. P. 
Published: April 2011

AbstractEBSD in the SEM has been developed into a tool that can provide identification of unknown crystalline phases with a spatial resolution that is better than one micrometer. This technique has been applied to a wide range of materials. Use of the HOLZ rings in the EBSD patterns has enabled the reduced unit cell to be determined from unindexed EBSD patterns. This paper introduces EBSD for phase identification and illustrates the technique with examples from metal joining and particle analysis. Reduced unit cell determination from EBSD patterns is then discussed.
Analysis of the Atomic Scale Defect Chemistry in Oxygen Deficient Materials by STEM
Authors: Ito Y. , Stemmer S. , Klie R. F. , Browning N. D. , Sane A. , Mazanec T. J. 
Published: April 2011

AbstractThe high mobility of anion vacancies in oxygen deficient perovskite type materials makes these ceramics potential candidates for oxygen separation membranes. As a preliminary investigation of the defect chemistry in these oxides, we show here the analysis of SrCoO3−σ using atomic resolution Z-contrast imaging and electron energy loss spectroscopy in the scanning transmission electron microscope. In particular, after being subjected to oxidation/reduction cycles at high temperatures we find the formation of ordered microdomains with the brownmillerite structure.
Resonance Raman Scattering of Multi-Walled Carbon Nanotubes
Authors: Kataura H. , Achiba Y , Zhao X. , Ando Y 
Published: April 2011

ABSTRACTMulti-walled carbon nanotubes synthesized by the carbon arc in hydrogen gas have very thin core channels. We have measured resonance Raman scattering of some samples synthesized in different conditions, and have observed radial breathing mode (RBM) peaks from 200 to 500 cm−1. Resonance effect of each peak is similar to that of single-walled nanotube. However, the peak frequencies are about 5 % higher than those of single-walled nanotubes, which is probably due to the inter-layer interaction. Further, the highest RBM peak splits in three peaks. The result on the resonance effect and the zone-folding band calculation suggest that the thinnest core nanotube is (4,3) that have four candidates of second outer nanotubes. This suggests that the different outer nanotube gives different degree of the interlayer interaction.
Electronic Properties of Potassium-Doped Carbon Nanotube Lattice
Authors: Saito Susumu 
Published: April 2011

ABSTRACTWe study the electronic structure of potassium-doped crystalline lattice of so-called (10.10) carbon nanotubes in the framework of the density-finctional theory. Tie stoichiometrv of the material studied is K2C80 which was originally proposed in designing the superconducting doped nanotube material based on tile size of dopants and the charge transfer being favorable for superconductivity. Electronic band dispersions obtained are actually found to be very similar to those of the pristine (10,10) nanotube lattice with the upward shift of the Fermi energy by 1 eV above the second conduction-band miinimum. Tie system therefore possesses higher Fermi-level density of states than the pristine material with rather sinmple charge transfer from K to C sites, and is confirned to be a good candidate for a naxiotube superconductor.
Molecular Dynamics Simulations of Polymer-Nanotube Composites
Authors: Frankland S. J. V. , Brenner D. W. 
Published: April 2011

ABSTRACTThe structure and mechanical properties of nanocomposites composed of (10,10) carbon nanotubes in an amorphous polyethylene matrix have been modeled with molecular dynamics simulations. Two systems were studied, an infinite nanotube (via periodic boundaries) and a finite capped nanotube 6 nm in length. In the infinite case the modulus in the direction of the nanotube is given by the upper bound of the rule of mixtures, as expected under isostrain conditions for a well-aligned fiber-reinforced composite. In the finite case, no load transfer is observed at low strain, consistent with the weak nanotube-polymer adhesion and a subcritical nanotube length. The simulations predict that regions of amorphous polymer close to the bulk density remain around the nanotubes at relatively large strains, and that the density decrease during strain results primarily from chain disentanglement and alignment in regions between nanotubes.
Low Threshold Field Emission From Nanocluster Carbon Films
Authors: Milne W.I. , Satyanarayana B.S. , Robertson J. 
Published: April 2011

ABSTRACTCarbon films with variable sp3/sp2 bonding ratio can be deposited on a variety of substrates at room temperature, using the cathodic vacuum arc deposition process. The variation in their surface morphology as a function of He and N2partial pressure during growth have been investigated and it has been shown that the morphology of the films can be varied from the mirror like smooth tetrahedrally bonded carbon (ta-C) films through nanocluster to fibrous type carbon. This paper reviews the work carried out on Field Emission from these various carbon films. Threshold fields as low as 1 V/μm for emission current densities of 1 μA/cm2 and emission site densities of up to 104 -105/cm2 have been obtained.
Low Temperature Growth of Ultra-Nanocrystalline Diamond on Glass Substrates for Field Emission Applications
Authors: Corrigan T. D. , Krauss A. R. , Gruen D. M. , Auciello O. , Chang R. P. H. 
Published: April 2011

ABSTRACTRecent studies of field emission from diamond have focused on the feasibility of growing diamond films on glass substrates, which are the preferred choice for cost-effective, large area flat panel displays. However, diamond growth on glass requires temperatures < 500 °C, which is much lower than the temperature needed for growing conventional microwave plasma chemical vapor deposition (CVD) diamond films. In addition, it is desirable to minimize the deposition time for cost-effective processing. We have grown ultrananocrystalline diamond (UNCD) films using a unique microwave plasma technique that involves CH4-Ar gas mixtures, as opposed to the conventional CH4-H2 plasma CVD method. The growth species in the CH4-Ar CVD method are C2 dimers, resulting in lower activation energies and consequently the ability to grow diamond at lower temperatures than conventional CVD diamond processes. For the work discussed here, the UNCD films were grown with plasma-enhanced chemical vapor deposition (PECVD) at low temperatures on glass substrates coated with Ti thin films. The turn-on field was as low as 3 V/μm for a film grown at 500 °C with a gas chemistry of l%CH4/99%Ar at 100 Torr, and 7 V/μm for a film grown at 350 °C. UV Raman spectroscopy revealed the presence of high quality diamond in the films.
Rapid Photo-Thermal Chemical Vapor Deposition of Amorphous Carbon From Diiodomethane
Authors: Lindstam M. , Boman M. , Piglmayer K. 
Published: April 2011

ABSTRACTA novel approach to deposit amorphous carbon from the precursor CH2I2 at low cost and high efficiency is reported. The combination of thermal and quantum photo effects shows new interesting growth behaviour. The radiation of a halogen-lamp was used to heat the substrate material and to split photolytically the precursor molecules above the substrate surface. The deposition process was investigated as a function of lamp power, gas phase partial pressures and substrate materials. The films were analysed by Raman spectroscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray photon spectroscopy, transmission electron microscopy and atomic force microscopy.
Oriented Graphitic Carbon Film Grown by Mass-Selected Ion Beam Deposition at Elevated Temperatures
Authors: Kulik J. , Lempert G. , Grossman E. , Lifshitz Y. 
Published: April 2011

ABSTRACTMass-selected ion-beam deposition using 120 eV C+ ions has been used to grow a carbon film on a Si substrate held at 200° C. The structure of the film has been characterized by transmission electron microscopy and electron energy loss spectroscopy. The film is graphitic and highly oriented with the c-axis lying parallel to the substrate. Moreover, the film is under significant biaxial stress such that the graphitic layer spacing is reduced by 4% from that of ambient pressure graphite. This oriented structure evolves due to the mobility of the carbon atoms at 200 °C. The material is sufficiently crystalline on the nanometer scale so as to produce Bragg diffraction discs in a convergent beam electron diffraction pattern using a 2.5 nm probe.