bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Problem of Maya Metallurgy in the Medium Grijalva, Central Guatemala, and the Yucatan Peninsula: Copper-Lead Alloy
Authors: Torres Luis M. , Franco Francisca V. , Navarrete Carlos C. 
Published: April 2011

ABSTRACTThe study of 4 metallic artifacts from the Medium Grijalva, two bells, a bipointed awl, and a needle, and one bell from Huehuetenango, Guatemala, were studied using of elemental analysis by flame atomic absorption spectroscopy (FAAS), metallographic examination and typological classification. Several problems arose, including the need to have a clearer definition of bell types, better knowledge of the technology of production of needles and awls, and problems with the Cu-Pb alloys, especially if a how high a lead content forms a Cu-Pb alloy solution.Early analyses made of bells and copper artifacts from the Maya area, Western Mexico and Southwest USA shows variable but important amounts of lead. The Cu-Pb phase diagram shows a monotectic reaction where the metals have poorcapability of alloying or mixing, forming a eutectic at very low lead concentrations. Few metalographic studies of these alloys are reported in papers about historic metals. However, some ternary Cu-Pb alloys are found in recent literature. Does the low arsenic content as in the analysis of the Cu-PbMayan bells influence the properties of the alloys? The importance of the distribution of types of bells made of Cu-Pb could clarify possible cultural connections and trade among the Maya area, western Mexico and southwest United States. The possible introduction of metallurgy from and trade with South America makes this search of even more importance.
ICP-MS Isotopic Signatures of Lead Ceramic Glazes, Rio Grande Valley, New Mexico, 1315–1700
Authors: Pingitore Nicholas E. , Hill David , Villalobos Joshua , Leach Jeff , Peterson John A. 
Published: April 2011

ABSTRACTICP-MS isotopie analysis of lead ceramic glazes suggests at least two sources were exploited by Ancestral Pueblo potters to obtain the lead raw material, presumably galena (PbS). Five Rio Grande lead glazeware sherds from the Sandia area and two found at Socorro share a common isotopie fingerprint. The temper of one of the Socorro sherds confirms an origin in the Sandia area; petrography of the temper of the second sherd does not tie to any known Socorro source rock. Two other glazeware sherds from Socorro have a distinctly different lead isotopie signature. A fifth Socorro glaze may be a mixture of the Sandia and Socorro lead source materials. The differences in lead isotopie signature thus accord well with mineralogical differences in the ceramic pastes. Lead isotopie signatures generated by ICP-MS analysis are a powerful new tool for grouping glazeware sherds, classifying individual samples, defining lead sources, and delineating trade routes.
In Situ Conservation of the Roman Mosaics at the Villa of Boscéaz (Orbe, Switzerland): Diagnosis of Risks Involved
Authors: Flatt R.J. , Girardet F.J. , Weidmann D.C. 
Published: April 2011

ABSTRACTIn order to maintain the archaeological integrity of the site of Boscéaz, one of the most remarkable north of the Alps because of the number and quality of its roman mosaics, it is intended to maintain these in situ and on their original support. This mode of conservation implies many risks, mainly linked to the climatic variations and to the presence of water and salts in the ground and the mosaics. The high degree of damage observed on these mosaics discovered more than 150 years ago illustrates this fact.The aim of this study has been to establish a diagnosis of the risks linked to the uncovering and the in situ conservation of a mosaic recently discovered (currently covered with protective materials). This diagnosis has been established on the basis of the measurement of the physical and chemical properties of the mosaic and the ground.It turned out that the rising of salts from the ground to the mosaic would be the major problem and that consequently a dessalaision will have to be carried out. Concerning the choice of the climatic conditions for conservation, the critical zone in which the salts present crystallize was determined. The thermal dilatation of the materials appeared relatively small, but might become damageable in the long term because of a possible hysteresis. The hydrie dilatation turned out to be negligible.
Polymers in Preservation and Restoration: Two Examples
Authors: Merrill E.W. 
Published: April 2011

ABSTRACTTwo ‘families’ of polymers applicable to preservation and restoration are discussed: (i) polysiloxane networks generated by platinum catalyzed addition of vinyl silane precursors to hydrogenosilane precursors; and (ii) acrylic compositions generated by redox initiated polymerization of acrylic monomers in the presence of fine spherical acrylic polymer particles. In both cases the end result is achieved at temperatures between ambient and 60°C, and with negligible volumetric shrinkage.
Photoexcited Carrier Effect on Imaging of Organic Molecules On Si(100)2×l Surfaces
Authors: Maeda Y , Matsumoto T , Kawaj T. 
Published: April 2011

ABSTRACTPhotocurrent images of zinc-phthalocyanine (ZnPc) and coronene molecules adsorbed on Si(100)2×1 surface have been obtained by scanning tunneling microscopy. The ZnPc molecules are observed as bright images indicating large local density of state (LDOS) at the bias voltage. However, coronene molecules show wide variety of contrast in their images. This difference is the result of variations of LDOS on molecules which are attribute to the difference of energy gap between highest occupied and lowest unoccupied molecular orbitals
Atomic Force Microscopy Study of Stabilized Quasi-Amorphous Carbon in the Range of Thickness from 5 nm To 300 μm
Authors: Pollak Fred H. , Wan J. Z. , Dorfman Benjamin F. 
Published: April 2011

ABSTRACTA new hard sp2-sp3 carbon stabilized by non-stoichiometric silica SiOx has been fabricated which combines a graphite-like layered structure with diamond-like mechanical properties, thermal stability and a very low density (≈ 1.6 g/cm3). This substance, which we refer to a quasi-amorphous material (QUASAM), has considerable potential applications as either thin films or bulk material since it can be grown as thick as 300 μm. Not only is the fine surface structure of crucial importance for thin films, but also the steadiness of a smooth growth front is a key factor for bulk material synthesis. Using atomic force microscopy (AFM) we have undertaken study of the surfaces/interfaces of such material over a wide range of thicknesses (5 nm < tf < 300 μm), including two free standing films.
Surface atomie resolution microscopy of sulfated-zirconia and Fe/Mn promoted sulfated zirconia
Authors: Benaissa M. , Santiesteban J. G. , Diaz G. , José-Yacamán M. 
Published: April 2011

ABSTRACTBy using high-resolution transmission electron microscopy (HRTEM), it was possible to elucidate edge-on views of the surface atomic structure of sulfated zirconia and Fe/Mn promoted sulfated-zirconia catalysts. The results indicate that the presence of sulfate groups and Fe/Mn species not only stabilizes the tetragonal zirconia phase, but also induces the formation of well-faceted small zirconia crystallites. The shape of the sulfated zirconia crystallites exhibits two types of surfaces: long smooth and relatively few short rough planes, with the long smooth (110) plane being clearly predominant. HRTEM images of this plane revealed the presence of an adsorbed sulfate layer. On the other hand, the presence of Fe and Mn species were apparent on the (001) and (110) surfaces of zirconia particles.
The Importance of the Fringing Field Surrounding a Tem Foil to the Quantification of Phase Contrast at a P-N Junction
Authors: Dunin-Borkowski R. E. , Saxton W. O. 
Published: April 2011

ABSTRACTThe space charge contribution to the electrostatic potential both inside and outside a dielectric slab containing a p-n junction is calculated using classical electrostatics, with particular reference to the use of phase contrast techniques in transmission electron microscopy for the characterisation of the carrier distributions present at such layers.
Lattice Disorder Effects on The Vacancy-Oxygen Centre in Ion-Irradiated Silicon
Authors: Keskitalo N. , Hallén A. , Lalita J. , Svensson B. G. 
Published: April 2011

ABSTRACTThe Vacancy-Oxygen (VO) centre is one of the most prominent defects appearing in silicon after irradiation with energetic particles and gamma rays. It is formed when migrating vacancies are trapped by interstitial oxygen atoms. It gives rise to a deep level in the upper part of the silicon bandgap at 0.164 eV below the conduction band edge that can be conveniently studied by deep level transient spectroscopy (DLTS). It is furthermore a very important defect from a technological point of view since it normally controls the charge carrier lifetimes in silicon power devices at high injection levels.Various doped n-type float zone Si samples have been irradiated with MeV ions at low doses. DLTS measurements of the charge carrier capture kinetics reveal lower capture rates if heavier ions, i.e. larger collision cascades, have been used to generate the defects. This effect can be interpreted as a local lowering of the Fermi level following lattice disorder in regions with a high elastic energy deposition. It will be shown that the VO is also very sensitive to lattice disorder in a similar way as previously reported for the divacancy centre.In the DLTS spectra another defect, originating from an interstitial-carbon—substitutional-carbon pair (Cj-Cs), overlaps with the VO-peak. The Ci-Cs pair has been observed to posses bistable properties and in this paper we will further elucidate the various contributions from the two defects to the Ec-0.164 eV peak. In particular, the temperature dependence of the electron capture cross section of the Cj-Cs level will be discussed.
Influence of The Local Microstructure on The Macroscopic Properties of Si1–x–yGexCy, Alloys
Authors: Windl W. , Kress J. D. , Voter A. F. , Menéndez J. , Sankey O. F. 
Published: April 2011

ABSTRACTWe performed a theoretical study of the microscopic arrangement of the C atoms in Si1–x–yGexCy, alloys using the Sankey local-orbital density-functional formalism. Our first-principles calculations show that in the dilute limit, the lattice constant in Si1–yCy, alloys decreases much more (by about 2/3) with concentration than predicted by Vegard's law. We show thatthis result is consistent with Raman and infrared experiments and with previous empiricalcalculations. As the C concentration increases, the interactions between the C atoms become important: Interstitial C becomes more abundant and increases the lattice constant, and the substitutional C atoms array under appropriate growth conditions. The effect of this ordering on the lattice constant is small, but it can be seen in the Raman spectra of layer-by-layer grown samples.
The Influence of Cavities and Point Defects on Cu Gettering and B'Diffusion in Si
Authors: Wong-Leung J. , Williams J. S. , Petravić M. 
Published: April 2011

ABSTRACTCavities, formed in Si by hydrogen implantation and subsequent annealing, can provide ideal gettering sites for metal impurities. In this study, we have observed large differences in the accumulation of Cu at cavities depending on whether Cu was introduced into Si during cavity formation or into wafers with pre-formed cavities. The observed behaviour is consistent with a high flux of Si interstitials emitted during cavity formation which induce the dissolution of Cu3Si and the enhanced transport of Cu to cavities. In further studies, boron implantation was carried out into wafers containing pre-formed cavities and transient enhanced diffusion (TED) of boron was suppressed duringsubsequent annealing.
Atomistic Mechanisms of Dislocation Mobility in Silicon
Authors: Justo J. F. , Bulatov V. V. , Yip S. 
Published: April 2011

ABSTRACTWe study the leading mechanisms of kink mobility of 30° and 90°-partial dislocations in the glide set {111} of silicon. The calculations are performed using a new empirical potential for Si, which has been shown to give an accurate description of core properties of partial dislocations [1], to study mechanisms of kink formation and migration. In the case of 30°-partial dislocation, two kinds of kinks are identified, left and right, which have different structures, formation energies, and mobilities.
Extracting the Grain Boundary Character/Free Energy Relationship from the Microstructure: Pure <100> and <111> Tilt Boundaries
Authors: Adams B. , Kinderlehrer D. , Ta'asan S. , Mullins W.W. , Costiner S. 
Published: April 2011

ABSTRACTAnalysis is described to extract the excess free energy of grain boundaries from the mesotexture of well-equilibrated polycrystalline samples. The approach is based upon the force and torque balances at triple junctions described in the classical work of Herring [1]. The main advantage of the approach is that the free energy function is obtained over the full fundamental zone of grain boundary types. For the purposes of exposition, the method is described for specified two-parameter hypersurfaces in the fundamental zone for cubic polycrystals (the sets of pure <100> and <111> tilt boundaries) and the free energy is assumed to depend only upon the lattice misorientation. Results from testbed simulations are presented.
Stress and Stability of Sputter Deposited A-15 and BCC Crystal Structure Tungsten Thin Films
Authors: O'keefe M. J. , Stutz C. E. 
Published: April 2011

ABSTRACTMagnetron sputter deposition was used to fabricate body centered cubic (bec) and A-15 crystal structure W thin films. Previous work demonstrated that the as-deposited crystal structure of the films was dependent on the deposition parameters and that the formation of a metastable A-15 structure was favored over the thermodynamically stable bec phase when the films contained a few atomic percent oxygen. However, the A-15 phase was shown to irreversibly transform into the bec phase between 500°C and 650°C and that a significant decrease in the resistivity of the metallic films was measured after the transformation. The current investigation of 150 nm thick, sputter deposited A-15 and bec tungsten thin films on silicon wafers consisted of a series of experiments in which the stress, resistivity and crystal structure of the films was measured as a function of temperature cycles in a Flexus 2900 thin film stress measurement system. The as-deposited film stress was found to be a function of the sputtering pressure and presputter time; under conditions in which the as-deposited stress of the film was ∼ 1.5 GPa compressive delamination of the W film from the substrate was observed. Data from the thermal studies indicated that bec film stress was not affected by annealing but transformation of the A-15 structure resulted in a large tensile increase in the stress of the film, regardless of the as-deposited stress of the film. In several instances, complete transformation of the A-15 structure into the bec phase resulted in ≥ 1 GPa tensile increase in film stress.
An X-ray Photoelectron Spectroscopie Study of B-N-Ti system
Authors: Seal Sudipta , Barr Tery L. , Sobczak Natalie , Benko Ewa , Morgiel J. 
Published: April 2011

ABSTRACTComposite nitrides (such as BN, TiN) are widely used in various industrial applications because of their extreme wear and corrosion resistance, thermal and electrical properties. In order to obtain composite materials with mese optimal properties, it is important to elucidate whether any chemical reactions occur at nitride/metal interfaces, e.g., those involving BN-Ti/TiN. Materials of interest include the deposition by PVD of Ti and TiN on BN substrates. Some of these systems were then subjected to varying degrees of physical and thermal alteration. Detailed X-ray photoelectron spectroscopy (XPS) has merefore been rendered of these interfaces using cross-sectional display and sputter etching. Resulting structural and morphological features have been investigated with transmission electron microscopy (TEM) and X-ray diffraction (XRD). Diffusion of the nitridation, oxynitride formation and interfacial growth are of general interest.
Microstructural Observations of LPCVD Double Layer Polysilicon Thin Film Tensile Specimens
Authors: Legros M. , Kumar M. , Jayaraman S. , Hemker K. J. , Sharpe W. N. 
Published: April 2011

ABSTRACTThe vast majority of micro electro-mechanical systems fabricated today depend on polycrystalline silicon thin films for structural support. Studies involving the mechanical performance of these thin films have progressed to the point where the elastic properties and tensile strength of the films can routinely be measured using a specially designed microsample tensile testing machine. However, a fundamental understanding to predict the mechanical behavior of the polycrystalline silicon films requires that these experimental measurements be complemented with detailed observations of the underlying thin film microstructure. This paper describes some of the plan view and cross-section transmission electron microscope observations that have been performed on different deposition runs of double layer polycrystalline films obtained from the Microelectronics Center of North Carolina. The emphasis has been placed on determining the flatness and dimensions of the polycrystalline films, grain morphology and distribution, texture, and dislocation substructure and microtwinning in the undeformed films.
Automated Crystal Orientation Mapping (ACOM) of Thin Metallization Layers and Interconnects
Authors: Schwarzer R.A. 
Published: April 2011

ABSTRACTA system for acquisition and interpretation of Kikuchi patterns with computer-controlled electron microscopes is presented. It enables interactive as well as fully automated determination of individual grain orientations. Special features for automated crystal orientation mapping (ACOM) with the scanning electron microscope (SEM) are digital beam scan, autocalibration and dynamic focus controlled by the computer. With the present setup about three orientations per second can be measured unattendedly. In the transmission electron microscope (TEM) the on-line determination of Burgers vectors and identification of deformation systems are based on crystal orientation measurement. The characterization of dislocations is facilitated by the simulation of diffraction patterns on the computer as a function of specimen tilt.Crystal orientation maps are obtained by assigning to the raster points in the image a color specific for the grain orientation, the misorientation or character of the grain boundary. The dala set of grain orientations is used to calculate the Schmid factors grain by grain, the orientation distribution function (ODF) and the correlated as well as the uncorrelated misorientation distribution functions (MODF) which characterize crystallographic texture in a statistical sense.Applications of individual grain orientation measurement are:. Thermomechanical hillocks in aluminum metallization layers on silicon substrates. Stress-induced grain growth in aluminum metallization layers on silicon substrates. Electromigration voids and hillocks in aluminum interconnectsA working hypothesis for electromigration failure, based on experimental findings, is discussed
Highly Conductive and Optically Transparent Polycrystalline Iridium Oxide Thin Films Grown by Reactive Pulsed Laser Deposition
Authors: El Khakani M.A. , Chaker M. 
Published: April 2011

ABSTRACTReactive pulsed laser deposition has been used to deposit IrO2 thin films on both SiO2 and fused quartz substrates, by ablating a metal iridium target in oxygen atmosphere. At a KrF laser intensity of about 1.7 × 109 W/cm2, IrO2 films were deposited at substrate deposition temperatures ranging from room-temperature to 700 °C under an optimum oxygen ambient pressure of 200 mTorr. The structure, morphology, electrical resistivity and optical transmission of the deposited films were characterized as a function of their deposition temperature (Td). High quality IrO2 films are obtained in the 400–600 °C deposition temperature range. They are polycrystalline with preferred orientations, depending on the substrate, and show a dense granular morphology. At a Td as low as 400 °C, highly conductive IrO2 films with room-temperature resistivities as low as (42±6) μΩ cm are obtained. Over the 300–600 °C Td range, the IrO2 films were found to exhibit a maximum optical transmission at 450 °C (∼ 45 % at 500 nm for 80 nm-thick films).
Free-Energy Barrier to Crystallite Nucleation in Solid-Phase Crystallized Poly-Silicon Thin Films
Authors: Kumomi Hideya , Shi Frank G. 
Published: April 2011

ABSTRACTWe introduce a non-Arrhenius method for measuring free-energy barrier to nucleation, W*, directly from size distribution of crystallites. W* is determined independent of any model for the nucleation barrier and independent of energy barrier to growth. The method is applicable to three-dimensionally growing crystallites, planar crystallites in thin films, and both compact and fractal crystallites. We apply the method to dendritic crystallites obtained by solid-phase crystallization of amorphous Si thin films into which Si+ ions are implanted at various conditions prior to the isothermal annealing. The ion implantation suppresses the nucleation of the crystallites and enhances the crystallite size of the resulting polycrystalline films. The directly measured W* increases as the accelerating energy or the dose of the Si+ ions increases. This result suggests that the observed suppression of the nucleation could not be accounted for simply by the amor-phization of the preexisting crystallites by the ion bombardment.
Hot Water Etching of Silicon Surfaces: New Insights of
Mechanistic understanding and Implications to Device
Fabrication
Authors: Rosamilia J. M. , Boone T. , Sapjeta J. , Raghavachari K. , Higashi G. S. , Liu Q. 
Published: April 2011

ABSTRACTOver the recent years, many new approaches in wafer cleaning have utilized
hot water rinsing. Benefits of hot water rinsing are (1) it aids the removal
of residual chemicals and (2) it improves the performance of the dry, e.g.
TREBOR hydrodry. However, there have been a number of significant
disadvantages documented with regard to device performance. Earlier work
done at this laboratory showed that the use of DI rinse water at elevated
temperatures can cause etching of the Si surface producing unwanted surface
topography and microroughness. The surface erosion created under these
conditions had a negative device impact which led to product yield loss. In
this paper, we provide a fundamental understanding of the mechanism by which
Si is etched during hot water rinsing. To this end, we have explored the
interaction of dissolved oxygen concentration, water temperature, and rinse
time as it relates to the attack/dissolution of H-terminated silicon.
Contact angle measurements, surface roughness measurements, and etch rate
data from TEM measurements as a function of water temperature, rinse time,
and dissolved oxygen concentration have been made. The etch rate data
strongly correlates with the rinse water temperature, however little
dependence was observed with dissolved oxygen concentration. A mechanism to
explain the etching will be discussed.