bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Elastic Constants of Restoration Mortars, Used on Historic Masonries Restoration Interventions, VIA Ultrasonic Technique and Correlation to their Mechanical and Microstructure Parameters
Authors: Moropoulou Antonia , Bakolas Asterios , Aggelakopoulou Eleni , Odatzidou Anastasia , Teas Christos , Papageorgiou Dimitris 
Published: April 2011

ABSTRACTEight syntheses of mortars used for restoration interventions in historic masonry were produced using the traditional materials of aerial lime and artificial pozzolanic additives. The mortars were aged over a 15-month period and then tested for properties related to chemical and mechanical stabilization using the following four analytical techniques: ultrasonic velocity propagation and the mortars' dynamic modulus of elasticity (Ed), mercury intrusion porosimetry for evaluation of microstructural characteristics (percentage open porosity, bulk density, average pore radius, total cumulative volume, and specific surface area), water capillary rise tests for the determination of total cumulative volume accessible to water and capillary rise coefficients of the mortars, and conventional mechanical tests for the determination of the mortars' flexural and compressive strength. Performance is correlated to the mortars' chemical composition, microstructural characteristics (as measure by average pore radius) and mechanical characteristics as measured by dynamic modulus of elasticity (Ed) and flexural and compressive strength (Fc).
Understanding Bronze Age Faience in Britain and Ireland
Authors: Sheridan Alison , Eremin Katherine , Shortland Andrew 
Published: April 2011

ABSTRACTAround 350 Bronze Age faience beads and pendants are known from Britain and Ireland, mostly from burials of cremated human bone. Their relationship with Near Eastern and Mediterranean faience has long been debated. A National Museums of Scotland (NMS) led international research project is investigating their origin, composition, manufacture and use (inter alia) for aCorpusof faience from Britain, Ireland and adjacent parts of mainland Europe. Non-destructive controlled-pressure scanning electron microscopy with energy dispersive microanalysis (CP-SEM-EDS), X-ray fluorescence (XRF) and binocular microscopy provide compositional and textural information without sampling or coating. Wavelength-dispersive electron microprobe (EMP) analysis of rare polished samples provides additional and more accurate compositional information. The results demonstrate that direct derivation from Egyptian or Mediterranean faience traditions can be ruled out. The beads and pendants were manufactured on a small-scale basis, using mostly a mixed alkali paste and glaze from plant ash sources (including seaweed) and a copper-based glaze colorant probably derived from bronze. Tin (or its oxide) seems to have been deliberately added. Various forming and glazing techniques were used. We have demonstrated, for the first time, that some beads were worn during cremation; and we have further investigated the effects of cremation on faience by experimentally cremating a pig wearing a newly-made faience necklace.
Technical Study of Pigments and Paintings in Archaeological Ceramics from Northwestern Argentine Region: An Archaeometric Approach and Implications for Their Conservation Through SEM-EDS.
Authors: De La Fuente Guillermo A. 
Published: April 2011

ABSTRACTThe ancient technology involved in the application of pigments and paintings used by potters to decorate ceramic vessels is one of the most interesting aspects of ceramic technology in the past. Potters have used in the past several sources (e.g. inorganic and organic) to decorate the vessels in order to achieve the colours desired and fix them in the vessels throughout the firing process. In this paper, we present the results of a technological and chemical characterisation of pigments and paintings through the application of Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) to ceramics from the Middle Period (ca. 650 AD – 900 AD) at Northwestern Argentine region.
Functionalization of Nanomaterials utilizing Pulse Thermal Processing
Authors: Kadolkar Puja B. , Ott Ronald D. , Blue Craig A. , Sabau Adrian S. 
Published: April 2011

ABSTRACTPulse Thermal Processing (PTP) using a High Density Infrared (HDI) Plasma Arc Lamp has been investigated as an enabling manufacturing tool for processing nanomaterials and thin-films. HDI is a single source lamp that offers unique capabilities of processing broad areas with power densities approaching those of a laser. The extremely high radiant energies delivered by the plasma arc lamp provides heating rates approaching 600, 000°C/s through a single pulse on a millisecond time frame, thus allowing controlled diffusion on nano-meter scale. The ability to design the functionality of nanomaterials offers tremendous potential to exploit this technology for a wide range of applications based on nanotechnology. This present article discusses application of PTP using high-density plasma arc lamp to perform; a) phase transformation in FePt nanoparticle system for magnetic media applications, and b) crystallization of amorphous Si (a-Si) for photovoltaic and thin-film transistor (TFT) applications.
Synthesis and Characterization of Magnetic Iron Oxide Nanoparticles
Authors: Wang Lingyan , Luo Jin , Maye Mathew M. , Fan Quan , Rendeng Qiang , Wang Jian Q. , Engelhard Mark H. , Wang Chongmin , Lin Yuehe , Altman Eric I. , Zhong Chuan-Jian 
Published: April 2011

ABSTRACTThis paper describes the results of an investigation of modified synthetic protocols to produce monodispersed magnetic ferrite nanoparticles, γ-Fe2O3 and Fe3O4, and their magnetic properties. The synthesis involved thermal decomposition of organometallic precursors followed by oxidation or reduction. In the synthesis of γ-Fe2O3, iron pentacarbonyl was used as the precursor and trimethylamine oxide as the oxidant. In the synthesis of Fe3O4, iron (III) acetylacetonate was reduced by 1, 2-hexadecanediol. The particle sizes ranged from 5–15 nm with high monodispersity. Results from TEM, XPS, and SQUID characterizations of these iron oxide nanoparticles are discussed.
Direct Measurements of Fracture Toughness and Crack Growth in Polysilicon MEMS
Authors: Chasiotis I. , Cho S.W. , Jonnalagadda K. 
Published: April 2011

ABSTRACTDirect measurements of Mode-I critical stress intensity factor and crack tip displacements were conducted in the vicinity of atomically sharp edge cracks in polycrystalline silicon MEMS using our in situ Atomic Force Microscopy (AFM)/Digital Image Correlation (DIC) method. The average Mode-I critical stress intensity factor for various fabrication runs was 1.00 ± 0.1 MPa√m. The experimental crack tip displacement fields were in very good agreement with linear elastic fracture mechanics solutions. By means of an AFM, direct experimental evidence of incremental crack growth in polycrystalline silicon was obtained for the first time via spatially resolved crack growth measurements. The incremental crack growth in brittle polysilicon is attributed to its locally anisotropic polycrystalline structure which also results in different local and macroscopic (apparent) stress intensity factors.
Temperature Dependence of Stress Distribution in Depth for Cu Thin Films
Authors: Himuro Tokuji , Takayama Shinji 
Published: April 2011

ABSTRACTThe stress distribution of (111) textured Cu films with depth was measured by using a GIXS method. We derived the equation to correct a scattering diffraction angle with depth, measured in the GIXS Seemann-Bohlin geometry, to obtain the actual scattering angle. It was revealed after the correction of the measured scattering angles that the internal stresses of (111) grains, on the whole, tend to increase almost linearly with increasing film depth from the free surface toward the substrate. It was suggested that these results were opposite to the results of the elastic calculation reported, and hence that a large stress relaxation took place during and/or after deposition and annealing. After annealing at various temperatures, these stress distribution profiles are almost unchanged, and are simply shifted uniformly in magnitude.
Microstructure Evolution Across Interfaces of Heterogeneous Metal Systems Under Ultrasonic Impact
Authors: Li Youhong , Ashkenazy Yinon , Averback Robert S. 
Published: April 2011

ABSTRACTLarge-scale Molecular Dynamics (MD) studies on heterogeneous, model metal systems subjected to intense shock loading by a flyer plate were carried out. Of interest here is the effect of structural defects on interfacial strength under these extreme conditions. The metal target and flyer were essentially single crystals of Cu, but an interface layer was created by varying the mass of the Cu atoms in part of the sample. Interfacial defects in the form of vacancies, and at different concentrations, were introduced into the interfacial region. In addition to microstructural evolution of damage in this system, the shock induced temperature and pressure changes were also analyzed.
Confinement Effects in Nanoscale Anodic Alumina Structures on Silicon
Authors: Griffin Patrick J. , Carpick Robert W. , Stone Donald S. 
Published: April 2011

ABSTRACTAnodic aluminum oxide (AAO) has long been considered a viable material for templated growth of nanomaterials for electronic, magnetic and optical applications due to the ability to form self-organized, high aspect-ratio nanochannels. More recently these porous materials have been incorporated with silicon to create a template for nanostructured materials on a semiconducting substrate. However, there has been no investigation into how pore growth is affected by confining the pre-anodized aluminum dimensions to the nanometer scale. We have used electron beam lithography to pattern 200 nm thick aluminum structures on Si with lateral features ranging from 100 nm to several microns in size. Structures consisting of 1 – 10 individual pores 10 – 15 nm in diameter are routinely fabricated. Confinement effects in the narrowest features assist in pore ordering in the porous structures without the use of pre-patterning or a two step anodization.
Stress Stability of Poly-SiGe and Various Oxide Films in Humid Environments
Authors: Low Carrie W. , Bircumshaw Brian L. , Dorofeeva Tatiana , Solomon Gelila , King Tsu-Jae , Howe Roger T. 
Published: April 2011

ABSTRACTThis paper presents the stress stability of thin films for MEMS structural and sacrificial layers. The average residual stresses of the thin films were monitored via wafer curvature measurement over a long period of time. Poly-Si, poly-SiGe, poly-Ge and thermally growth SiO2films are found to be stable in humid environments. Moisture makes LPCVD and TEOS-based PECVD SiO2films more compressive over time. Multi-layer thin film stress is modeled with the same methodology used to derive the Stoney Equation [1].
Stability and Structural Transition of Gold Nanowires under Their Own Surface Stresses
Authors: Gall Ken , Haftel Michael , Diao Jiankuai , Dunn Martin L. , Bernstein Noam , Mehl Michael J. 
Published: April 2011

ABSTRACTFirst-principle, tight binding, and semi-empirical embedded atom calculations are used to investigate a tetragonal phase transformation in gold nanowires. As wire diameter is decreased, tight binding and modified embedded atom simulations predict a surface-stress-induced phase transformation from a face-centered-cubic (fcc) <100> nanowire into a body-centered-tetragonal (bct) nanowire. In bulk gold, all theoretical approaches predict a local energy minimum at the bct phase, but tight binding and first principle calculations predict elastic instability of the bulk bct phase. The predicted existence of the stable bct phase in the nanowires is thus attributed to constraint from surface stresses. The results demonstrate that surface stresses are theoretically capable of inducing phase transformation and subsequent phase stability in nanometer scale metallic wires under appropriate conditions.
In situ TEM Observations of Grain Growth in Nanograined Thin Films
Authors: Hattar K. , Gregg J. , Han J. , Saif T. , Robertson I. M. 
Published: April 2011

ABSTRACTIn situ transmission electron microscopy analysis is used to study the stability of nanograined and ultra-fine grained thin films at elevated temperatures. In the free-standing Au and Cu films, grain growth was dependent on annealing temperature and time with growth observed in both materials at temperatures greater than 373K. Both materials exhibited abnormal grain growth although it was more prevalent in Au than in Cu, which may be a consequence of pinning of the Cu grain boundaries by impurities. The formation and destruction of twins was observed to play a critical role in the grain growth, with the twins retarding the growth in gold, but not in Cu. In constrained Au films no grain growth was observed on annealing at temperatures below 636 K. At 636 K, the eutectic temperature, the microstructure transformed to the eutectic structure with the first stage being the annihilation of the grain structure.
Morphology and Microstructure Evolution of Multilayer Au/Cr/Si Thin Films Subject to Annealing
Authors: Miller David , Herrmann Cari , Maier Hans , George Steve , Stoldt Conrad , Gall Ken 
Published: April 2011

ABSTRACTAu/Cr/Si microcantilevers were studied in their as-deposited condition and annealed state, with emphasis on a thermal treatment of 225 °C for 24 hours. Change in beam curvature was monitored during isothermal hold as a function of time. Secondary grain growth was observed in the gold, which contained non-uniformly distributed twins and dislocation defects. Diffusional transport of the chromium layer was observed during annealing. Nodules arranged in the “rolling hill” topography were observed at the free surface, both before and after annealing. Nanometer thick coatings of alumina grown by atomic layer deposition improved the uniformity of both microstructure evolution and curvature evolution during high-temperature annealing.
Thickness-dependent Structural Relaxation of Plasma-Enhanced Chemical Vapor Deposited Silicon Oxide Films during Thermal Processing
Authors: Cao Zhiqiang , Zhang Xin 
Published: April 2011

ABSTRACTThis paper presents a microstructure-based mechanism which elucidates seams as a source of density change and voids as a source of plastic deformation, accompanied by a viscous flow. This theory was then applied to explain a series of experimental results that are related to thermal cycling of amorphous dielectric films, such as plasma-enhanced physical vapor deposited (PECVD) silicon oxide (SiOx) films, including stress hysteresis generation and reduction and coefficient of thermal-expansion changes. In particular, the thickness effect was examined; PECVD SiOx films with a thickness varying from 1 to 40 m were studied, as certain demanding applications in Microelectromechanical Systems (MEMS) require such thick films serving as heat/electrical insulation layers.
Development of Magnetostrictive Fe-Ga and Fe-Pd Thin Films
Authors: Okazaki Teiko , Watanabe Satoru , Okanisi Norimasa , Ono Toshiro , Furuya Yasubumi , Michigami Munemi , Sakisaka Yasuo , Takeuchi Ichiro , Wuttig Manfred 
Published: April 2011

ABSTRACTThe giant magnetostrictive films exhibit promising device applications for micro-machines and sensor systems due to high response velocity and huge stress created by the magnetostriction. We developed magnetostrictive bimorph-type Fe70Pd30 or Fe83Ga17 (positive magnetostriction)/Al/Ni(negative magnetostriction) thin films by magnetron sputtering. Magnetostriction of these films measured by a bending cantilever beam method has reached 250–300 ppm in the small magnetic field of 1.0 kOe and exhibits little hysteresis. Moreover, the magnetostrictive characteristics do not change under low alternating magnetic field. The magnetoelastic coefficient of these films is 25∼30 MPa, which is comparable to the coefficient of the PbTiO3-PbZrO3 system. These metallic sensor/actuator materials are useful for applications in magnetostrictive 2D- scanners and remote-interrogated tire sensors.
Thermomechanics of the Shape Memory Effect in Polymers
Authors: Liu Yiping , Gall Ken , Dunn Martin L , Greenberg Alan R 
Published: April 2011

ABSTRACTShape memory polymers (SMPs) have the capacity to store and recover relatively large strains when subjected to a unique thermomechanical cycle. In this study, the thermomechanics of strain storage and strain/stress recovery are investigated in a shape memory polymer deformed under uniaxial tension and compression. During heated recovery, three cases of constraint are examined: unconstrained (free) strain recovery, stress recovery under pre-strain constraint, and stress recovery under fixed-strain constraint. Based on the experimental results, a one-dimensional SMP constitutive model is developed, which is motivated by the shape memory mechanism of the polymer network. The foundation of the model is that the entropy change is gradually stored during cooling and released during reheating as free recovery strain or constrained recovery stress. When fit to free strain recovery data, the model can predict the trends of the stress evolution during shape fixation and constrained strain/stress recovery under various thermomechanical conditions.
Enhanced Raman signal of CH3 on carbon nanotubes
Authors: Bassil A. , Puech P. , Landa G. , Bacsa W. , Hubel H. , Dunstan D. J. , Barrau S. , Demont Ph. , Lacabanne C. , Perez E. , Flahaut E. , Bacsa R. , Peigney A. , Laurent Ch. 
Published: April 2011

ABSTRACTWe find that functionalized SWCNT and DWCNT's (mainly double wall carbon nanotubes) in composites, DWCNTs under hydrostatic pressure and blue illuminated DWCNTs in methanol show the same up shift of the Raman G band and the appearance of a new band at 1455cm−1. This is attributed to the interaction of the CH3 group of the amphiphilic molecule in composites or the CH3 group of alcohol with the outer tube of DWCNT's and indicates that laser heating of DWCNT's in methanol can induce the chemical adsorption of CH3 onto the CNT (carbon nanotube) surface.
Growth, Nitrogen Doping and Characterization of Isolated Single-Wall Carbon Nanotubes using Liquid Precursors
Authors: Keskar Gayatri , Rao Rahul , Luo Jian , Hudson Joan , Rao Apparao M. 
Published: April 2011

ABSTRACTIsolated single wall carbon nanotubes (SWNTs) were prepared on bare quartz and SiO2/ Si substrates using chemical vapor deposition (CVD) in which a liquid precursor, such as xylene, was used as the carbon source. The coverage of isolated SWNTs on the substrates was controlled by adjusting the concentration of iron (III) nitrate nonahydrate/2-propanol solution which provided the Fe seed catalyst particles. Micro-Raman spectra were obtained using the 514.5 nm excitation which showed the typical tangential band around 1590 cm−1 for semiconducting nanotubes. The radial breathing mode (RBM) frequencies ranged between 150 to 240 cm−1 and the estimated tube diameters are in good agreement with those obtained from atomic force microscope (AFM) images. In our synthesis approach controlled doping of isolated SWNTs with nitrogen was achieved by mixing appropriate amount of acetonitrile with xylene. As the nitrogen concentration in the feed was increased from 0 – 33 at. %, the RBM intensity decreased dramatically while the intensity of the D-band increased gradually relative to that of the G-band. Interestingly, the D' band was observed for the first time in the Raman spectrum of carbon nanotubes when the nitrogen concentration reached ∼2–3 at. %.
Arc-Discharge Evaporation of Silver-Plated Graphite Rods
Authors: Vaziri M. 
Published: April 2011

ABSTRACTIn this work, several silver-plated graphite rods have been evaporated using the dc-arc discharge technique in the presence of helium quenching gas. The evaporated materials deposited on the cathode and the chamber walls were characterized. It was found that the inner core of the deposited materials contains no encapsulated silver but unusually long bundles of carbon nanotubes. In addition, the soot removed from the walls presents evidence for encapsulated nanocrystalline silver as well as low-mass fullerene cages.
Electrical Conductivity and Electromagnetic Interference Shielding of Multi-walled Carbon Nanotube Filled Polymer Composites
Authors: Yang Yonglai , Gupta Mool C. , Dudley Kenneth L. , Lawrence Roland W. 
Published: April 2011

ABSTRACTMulti-walled carbon nanotube (MWNT) filled polystyrene (PS) composites were synthesized for electromagnetic interference (EMI) shielding applications. SEM images of composites showed the formation of the conducting networks through MWNTs within the PS matrix. The measured DC conductivity of composites increased with increasing MWNT loading, showing a typical percolation behavior. EMI shielding characteristics of MWNT-PS composites were investigated in the frequency range of 8.2–12.4 GHz (X-band). It was observed that the shielding effectiveness (SE) of such composite increased with the increase of MWNT loading. The SE of the composite containing 7 wt% MWNTs could reach more than 26 dB in the measured frequency region.
First-Principles Study of Epitaxial Growth of Zinc-Blende CrAs on GaAs Substrates
Authors: Mukose Kiichiro , Kusakabe Koichi , Suzuki Naoshi 
Published: April 2011

ABSTRACTWe study the epitaxial growth mechanisms of the zinc-blende CrAs on the GaAs substrates theoretically, from the first principles using the pseudopotential method. We assume some model structures containing various numbers of Cr adatoms or CrAs films on the GaAs (001) substrates, and compare the structural stabilities of them. We found that Cr adatoms may make some interstitial defects in the GaAs substrate in low coverage, but they can create a complete Cr layer in high coverage.
From Atomistic to Continuum Descriptions of Morphological Evolution
Authors: Haselwandter Christoph A. , Vvedensky Dimitri D. 
Published: April 2011

ABSTRACTLattice Langevin equations are derived from the rules of lattice growth models. These provide an exact mathematical description that is suitable for direct analysis, such as the passage to the continuum limit, as well as a computational alternative to kinetic Monte Carlo simulations. This approach is applied to ballistic deposition and a model for conditional deposition, both of which yield the Kardar–Parisi– Zhang equation in the continuum limit, and a model of strain relaxation during heteroepitaxy.
“Enhanced Layer Coverage of Thin Films by Oblique Angle Deposition”
Authors: Karabacak Tansel , Wang Gwo-Ching , Lu Toh-Ming 
Published: April 2011

ABSTRACTThe characteristics of nucleation and island growth in oblique angle deposition with substrate rotation have recently attracted interest due to the formation of novel 3D nanostructures by a physical self-assembly process. In this study, we present the results of a solid-on-solid growth simulation by a kinetic Monte Carlo algorithm that explores the layer coverage evolution of thin films during oblique angle deposition. The simulations accounted for oblique incidence flux, shadowing effect, surface diffusion, and substrate rotation. The layer coverage, the ratio of average island volume to average island size, and root-mean-square (RMS) roughness values are reported for the initial stages of island growth from submonolayer thicknesses up to a few monolayers. RMS roughness was also investigated for later stages of the growth. Our results show that, for small deposition angles and with limited or no surface diffusion included, the average growth rate of islands is faster in lateral directions that results in enhanced layer coverages and smoother films. This is due to that the sides of the islands can be exposed to the incident flux more effectively at small deposition angles. On the other hand, normal incidence and high oblique angle depositions give poorer layer coverages and much rougher films due to the slower growth rates in lateral directions.