bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prehistoric Ceramics of Northern Afghanistan: Neolithic through the Iron Age
Authors: Kolb Charles C. 
Published: April 2011

AbstractFor nearly four millennia, Afghanistan has been at the crossroads of Eurasian commerce and remains ethnically and linguistically diverse, a mosaic of cultures and languages, especially in the north, where the Turkestan Plain is a conduit for the so-called Silk Route, a series of “roads” that connected far-flung towns and urban centers and facilitated the transfer of goods and services. The research reported herein involves the comparative analysis of archaeological ceramics from a series of archaeological sites excavated in northern Afghanistan in the mid-1960s by the late Louis Dupree and me. I served as the field director (1965-1966) and analyzed the ceramics excavated from all six archaeological sites. These were Aq Kupruk I, II, III, and IV located in Balkh Province (north-central Afghanistan) and Darra-i-Kur and Hazar Gusfand situated on the border between Badakshan and Tarkar Provinces (extreme northeastern Afghanistan). Ten of the 72 ceramic types from the Aq Kupruk area have been published [1, 2, 3] but none of the 53 wares from northeastern Afghanistan have been described. The majority of the Aq Kupruk materials are undecorated (plain ware) ceramics but there is a unique series of red-painted decorated ceramics (Red/Buff, numbered types 45 through 52) with early first millennium BCE designs but the pottery dates to the BCE-CE period. The results of ceramic typological, macroscopic, binocular and petrographic microscopy (thin-section analysis and point counting) are reported.
Study of Painting Materials and Techniques in the 18th Century St.Athanasius Church in Moschopolis, Albania
Authors: Pavlidou Eleni , Civici N. , Caushi E. , Anastasiou L. , Zorba T. , Hatzikraniotis E. , Paraskevopoulos K. M. 
Published: April 2011

AbstractIn this paper are presented the studies of the paint materials and the technique used in 18th century wall paintings, originated from the orthodox church of St Athanasius, in the city of Maschopolis, a flourishing economical and cultural center, in Albania. The church was painted in 1745 by Konstantinos and Athanasios Zografi, and during the last years, restoration activities are being performed at the church. Samples that included plasters and pigments of different colors were collected from important points of the wall paintings. Additionally, as some parts of the wall-paintings were over-painted, the analysis was extended to the compositional characterization of these areas. The identification of the used materials was done by using complementary analytical methods such as Optical Microscopy, Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM-EDS) and X-ray fluorescence (TXRF).The presence of calcite in almost all the pigments is indicative for the use of the fresco technique at the studied areas, while the detection of gypsum and calcium oxalate, indicates an environmental degradation along with a biodegradation. Common pigments used in this area at 15-16th centuries, such as cinnabar, green earth, manganese oxide, carbon black and calcite were identified.
Focused-Ion Beam and Electron Microscopy Analysis of Corrosion of Lead-Tin Alloys: Applications to Conservation of Organ Pipes
Authors: Oertel Catherine , Baker Shefford P. , Niklasson Annika , Johansson Lars-Gunnar , Svensson Jan-Erik 
Published: April 2011

AbstractAcross Europe, lead-tin alloy organ pipes are suffering from atmospheric corrosion. This deterioration can eventually lead to cracks and holes, preventing the pipes from producing sound. Organ pipes are found in compositions ranging from >99% Pb to >99% Sn. For very lead-rich (>99% Pb) pipes, organic acids emitted from the wood of organ cases have previously been identified as significant corrosive agents. In order to study the role of alloy composition in the susceptibility of pipes to organic acid attack, lead-tin alloys containing 1.2-15 at.% Sn were exposed to acetic acid vapors in laboratory exposure studies. Corrosion rates were monitored gravimetrically, and corrosion product phases were identified using grazing incidence angle X-ray diffraction. In a new method, focused-ion beam (FIB) cross-sections were cut through corrosion sites, and SEM and WDX were used to obtain detailed information about the morphology and chemical composition of the corrosion layers. The combination of FIB and SEM has made it possible to obtain depth information about these micron-scale layers, providing insight into the influence of acetic acid on alloys in the 1.2-15 at.% Sn range.
Synthesis of Porous Silica Nanotubes using Rosette Nanotubes as Templates
Authors: Danumah Christophe , Hemraz Usha D. , Fenniri Hicham 
Published: April 2011

ABSTRACTRosette nanotubes (RNTs) were used as structure-directing agents for the synthesis of microporous and/or mesoporous silica nanotubes. The silica nanomaterials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and CO2 and nitrogen physisorptions. The results show that the mode of the obtained porous systems as well as the surface areas and volume of micro- and/or mesopores depend on the nature of the pendant attached to the rosette nanotubes surface.
Effects of Stress-relieving AlN Interlayers in GaN-on-Si Grown by Plasma-assisted Molecular Beam Epitaxy
Authors: Adikimenakis Adam , Sahonta Suman-Lata , Dimitrakopulos George , Domagala Jaroslav , Komninou Philomela , Georgakilas Alexander 
Published: April 2011

ABSTRACTThe insertion of an AlN interlayer for tensile strain relief in GaN thin films grown on Si (111) on-axis and vicinal substrates by nitrogen rf plasma source molecular beam epitaxy has been investigated. The 15 nm AlN interlayer was inserted between the bottom 0.5 micron GaN layer and the top 1.0 micron GaN layer. The interlayer was very effective to reduce the tensile stress in the overall 1.5 micron GaN/Si film to the level required for complete avoidance of microcracks, which were present in high densities in GaN/Si heterostructures grown without an AlN interlayer. The strain of the AlN interlayer, as well as the strain in all the layers of the entire GaN/Si heterostructure was analyzed by x-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Reciprocal space map in XRD indicated that the 15 nm AlN interlayer was coherently strained with the GaN films. However TEM observations revealed that the AlN interlayer was partially relaxed in local regions. The AlN interlayer was also observed to interfere with the GaN growth process. In particular, above morphological features such as V-defects, GaN was overgrown with a large density of threading dislocations and inversion domain boundaries.
Relaxation Behavior and Breakdown Mechanisms of Nanocrystals Embedded Zr-doped HfO2 High-k Thin Films for Nonvolatile Memories
Authors: Yang Chia-Han , Kuo Yue , Lin Chen-Han , Wan Rui , Kuo Way 
Published: April 2011

AbstractSemiconducting or metallic nanocrystals embedded high-k films have been investigated. They showed promising nonvolatile memory characteristics, such as low leakage currents, large charge storage capacities, and long retention times. Reliability of four different kinds of nanocrystals, i.e., nc- Ru, -ITO, -Si and -ZnO, embedded Zr-doped HfO2 high-k dielectrics have been studied. All of them have higher relaxation currents than the non-embedded high-k film has. The decay rate of the relaxation current is in the order of nc-ZnO > nc-ITO > nc-Si > nc-Ru. When the relaxation currents of the nanocrystals embedded samples were fitted to the Curie-von Schweidler law, the n values were between 0.54 and 0.77, which are much lower than that of the non embedded high-k sample. The nanocrystals retain charges in two different states, i.e., deeply and loosely trapped. The ratio of these two types of charges was estimated. The charge storage capacity and holding strength are strongly influenced by the type of material of the embedded nanocrystals. The nc-ZnO embedded film holds trapped charges longer than other embedded films do. The ramp-relax result indicates that the breakdown of the embedded film came from the breakdown of the bulk high-k film. The type of nanocrystal material influences the breakdown strength.
Synthesis of Nickel Disilicide Nanocrystal Monolayers for Nonvolatile Memory Applications
Authors: Yoon Jong-Hwan , Elliman Robert G. 
Published: April 2011

AbstractNickel silicide nanocrystals (NCs) were formed by thermally annealing SiOxNy films either implanted with Ni or coated with an evaporated Ni film. It is observed that the NCs grow into well-defined single crystalline structures embedded in a SiOxNy matrix, and that their size can be directly controlled by adjusting the concentrations of either silicon or nickel in the SiOxNy layer. The formation of well-defined NC monolayers was also demonstrated by depositing an ultra-thin Ni layer between two SiOxNy layers. These structures are shown to exhibit characteristic capacitance-voltage hysteresis suitable for nonvolatile memory applications.
Dependence on Organic Thickness of Electrical Characteristics Behavior in Low Molecular Organic Novolatile memory
Authors: Kim Yool Guk , Seo Sung Ho , Lee Gun Sub , Park Jea Gun , Kim Jin Kyu 
Published: April 2011

AbstractRecently, organic nonvolatile memory of nonvolatile memories have attracted attention because application as next generation memory devices. In effort for realizing low-molecular organic nonvolatile memory, the dependence of organic thickness on electrical characteristic behavior in low-molecular organic nonvolatile memory was investigated. We developed an low-molecular organic nonvolatile memory fabricated with the device structure of Al/Alq3 (Aluminum tris(8-hydroxyquinoline))/Ni nanocrystals/Alq3/Al. Four different organic thicknesses, i.e., 30, 40, 50, and 100 nm, with fixing middle layer thickness were deposited by using a high vacuum thermal deposition method. The reason we chose Ni for middle metal layer is that Ni has smaller grain boundary which is benefit for scaling down and larger work function (∼5.15 eV) that can make a deep quantum well in energy band diagram, compared with those of Al. We confirmed that, as an organic thickness increases, a current level linearly decreases by an order of magnitude in a log-scale except for the 100 nm sample case. That is, Ion of 30-nm-thick sample was about 1 mA and 50-nm-thick sample was about 10 ¥ìA. The reason why the decrease in the current with increasing an organic thickness can be attributed to that electron transfer occurs less frequently because of the decrease in the hopping frequency. In addition, a 100-nm-thick sample was not shown the electrical characteristic of low-molecular organic nonvolatile memory. Meanwhile, the switching characteristics of our device showed that Vth of 2V, Vp(program) of 4V, Ve(erase) of 7V, and Ion (after programming)/Ioff (after erasing) of ~6x103. In addition, the interesting behavior of those characteristics is that the switching voltages (e.g; Vth, Vp, Ve Ion/Ioff) were not much changed with a varying an organic thickness. Therefore, we can conclude that an organic thickness does not affect significantly to the switching characteristics but current level. In addition, it was confirmed that a 30-nm-thick organic thickness was the best process condition in realizing low-molecular organic nonvolatile memory fabrication process.
Nonvolatile resistive switching characteristics of HfO2 with Cu doping
Authors: Guan Weihua , Long Shibing , Liu Ming , Wang Wei 
Published: April 2011

AbstractIn this work, resistive switching characteristics of hafnium oxide (HfO2) with Cu doping prepared by electron beam evaporation are investigated for nonvolatile memory applications. The top metal electrode/ hafnium oxide doped with Cu/n+ Si structure shows two distinct resistance states (high-resistance and low-resistance) in DC sweep mode. By applying a proper bias, resistance switching from one state to the other state can be achieved. Though the ratio of high/low resistance is less than an order, the switching behavior is very stable and uniform with nearly 100% device yield. No data loss is found upon continuous readout for more than 104 s. The role of the intentionally introduced Cu impurities in the resistive switching behavior is investigated. HfO2 films with Cu doping are promising to be used in the nonvolatile resistive switching memory devices.
Temperature Dependence of Electrical Properties of NiO Thin Films for Resistive Random Access Memory
Authors: Suzuki Ryota , Suda Jun , Kimoto Tsunenobu 
Published: April 2011

AbstractTemperature dependence of electrical properties in NiO thin films for ReRAM applications has been investigated. I-V measurements have been carried out in the temperature range from 100K to 523K. The resistance in the high resistance state (HRS) is almost independent of temperature below 250K, whereas it decreases with an activation energy of 300 meV above 250K. Hopping conduction and band conduction may be dominant in the low- and high-temperature range, respectively. Admittance spectroscopy on the NiO/n+-Si structure¡¡reveals the existence of a high density of traps, which may contribute to the conduction in HRS. In the low resistance state (LRS), however, the resistance slightly increased in the whole temperature range and the trend is similar to that of metallic Ni film, indicating the metallic Ni defects is related to the conduction in LRS. The Pt/NiO/Pt structure demonstrated stable resistance switching even at temperature as high as 250°C or higher. Since other competitive nonvolatile memories will face severe difficulty in high-temperature operation, the present ReRAM shows promise for high-temperature application.
Large-domain Organic Crystalline Films for Field-effect Transistors
Authors: Tominari Y. , Uno M. , Yamagishi M. , Suzuki Y. , Wakamiya A. , Yamaguchi S. , Takeya J. 
Published: April 2011

AbstractWe report a method to fabricate thin films of large-domain organic semiconductor single crystals dispersed over the whole surface of centimeter-scale substrates for field-effect transistors. Growing less than 500-nm thick film-like organic crystals of sub-millimeter sizes densely in a furnace independently of substrates by physical vapor transport, the collection of the single crystals is mechanically attached to the surface of gate dielectric layers. The organic transistors made of large-domain benzo-annulated pentathienoacene crystals exhibited pronounced transistor performances with mobility values of ∼ 0.2-2 cm2/Vs, which is as high as devices of one-piece crystals. The result demonstrates that the above technique provides a method to apply high performance of organic single crystal transistors to real circuitry devices on large-area substrates.
Effect of Polymer Gate Dielectric Surface Viscoelasticity on Pentacene Thin-Film Transistor Performance
Authors: Kim Choongik , Facchetti Antonio , Marks Tobin J. 
Published: April 2011

AbstractPentacene is one of the most studied semiconductor for organic thin-film transistors (OTFTs), and enhanced understanding of pentacene-based TFTs has significantly advanced the organic electronics. We report here the crucial effect of the polymer gate dielectric glass transition temperature (Tg) on pentacene film growth mode, microstructure, and the resulting TFT performance. Nanoscopically-confined thin polymer films are known to exhibit reduced glass-transition temperatures versus the corresponding bulk values, and we demonstrate here that pentacene films grown on polymer gate dielectrics at temperatures well below their bulk Tg exhibit morphological/microstructural transitions and OTFT performance discontinuities at well-defined growth temperatures [defined as the surface Tg, or Tg(s)] characteristic of the underlying polymer structure and independent of the film thickness. The results argue that realistic OTFT response must take into account this fundamental polymer property, and that TFT measurements represent a new probe of polymer surface thermal properties.
Thermoelectric Power Changes of Low Strength Steel Induced by Hydrogen Embrittlement Tests
Authors: Mohamed-Noriega N. , López Cuéllar E. , de la Cruz A. Martinez 
Published: April 2011

ABSTRACTThis work reports the thermoelectric characterization of a hydrogen embrittlement (HE) of low strength steel. Two sets of tests are performed in an electrochemical cell of H2SO4, with and without applied stress, lasting from 2 to 94 hours. Thermoelectric power (TEP) measurements are matched with ductility measurements (%RA and %EL) of samples tested in tension, as well as with microhardness measurements. Results indicate that TEP is sensitive to HE of low strength steels; the maximum variation of TEP is of ∼80nV/°C for samples tested without stress.
Application of High Spatial Resolution Electron Diffraction Techniques to the Study of Local Properties of Crystalline Solids
Authors: Steeds J W , Duan X F , Midgley P A , Spellward P , Vincent R 
Published: April 2011

ABSTRACTThe addition of a Gatan imaging parallel electron-energy loss spectrometer (IPEELS) to a Hitachi HF 2000 cold field emission TEM has allowed us to produce high quality energy-filtered coherent electron diffraction patterns and electron holograms from a wide variety of materials. In this paper we review the recent achievements and make an assessment of the use of coherent electron diffraction in solving problems at high spatial resolution in materials science.
Atomic Resolution Electronic Structure Using Spatially Resolved Electron Energy Loss Spectroscopy
Authors: Batson P.E. 
Published: April 2011

ABSTRACTElectronic structure in small areas is obtainable by inspection of near edge fine structure of core excitations. We can accomplish this today with near atomic resolution, using EELS at high energy. At IBM, we have obtained results using a sub-0.2nm probe at 120KeV with enough current to allow 200meV resolution studies at the Si L2,3 edge. It is especially crucial for Si-based structures that this allows us to obtain Z-contrast dark field images of the Si lattice at an acceleration voltage that is low enough to minimize radiation damage, but with a high enough current to allow good quality spectra to be obtained. A review of instrumental requirements, spectral interpretation, and applications to Si-Ge alloys is presented.
Quantitative X-Ray Microanalysis for the Study of Nanometer-Scale Phases in the Aem
Authors: Anderson Ian M. , Bentley Jim , Carter C. Barry 
Published: April 2011

ABSTRACTSecondary excitation can be a large source of inaccuracy in quantitative X-ray microanalysis of inhomogeneous specimens in the AEM. The size of the secondary excitation component in the measured X-ray spectrum is sensitive to the geometry of the thin foil specimen. Secondary excitation has been examined in a self-supporting disc specimen of composition NiO-20 wt.% TiO2 which has been partially masked by a gold slot washer. The ratio of the intensities of the characteristic Kα peaks of Ti and Ni in X-ray spectra from a periclase-structured phase, of nominal composition NiO, has been measured to be NTi / NNi ≈ 0.005. There is no apparent Ti L2,3 signal in the corresponding electron energy-loss spectrum. The secondary excitation contribution to the characteristic Ti K≈a-peak from all sources can therefore be no larger than 0.5%. It should be possible to reduce this modest level of secondary excitation still further with a better masking arrangement.
Determination of the Number of Molecules Bonded to a CdSe Nanocrystallite Surface
Authors: Majetich Sara , Newbury Jennifer , Newbury Dale 
Published: April 2011

ABSTRACTElectron excited energy dispersive X-ray spectrometry (EDS) was used to determine the atomic species present in 35 Å diameter CdSe nanocrystallites. Both theoretical modeling and experimental calibration with standard materials were used to relate the relative X-ray intensities to the atomic fractions present in the sample. The EDS results were normalized to those found by elemental analysis, which also detects light elements. With different surface models, and the atomic fractions found by EDS, the number of surface groups per nanocrystallite was determined.
Eels Imaging of Biological Materials
Authors: Leapman R.D. , Sun S. , Hunt J.A. , Andrews S.B. 
Published: April 2011

ABSTRACTParallel-detection electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope provides a very sensitive means of detecting specific elements in biological systems. By analyzing EELS spectrum-image data recorded from rapidly-frozen and cryosectioned tissue it is possible to map quantitatively the distribution of the biologically important element, calcium, which is typically present at concentrations of only a few parts per million in cellular structures some tens of nanometers in diameter. A significant improvement (factor of four) in calcium detectability has been demonstrated for EELS compared with energy-dispersive x-ray spectroscopy. The spectrum-imaging technique has also been applied to map water distributions in hydrated biological specimens by utilizing the valence electron excitations.
Visualizing Langmuir-Blodgett Films with the Atomic Force Microscope
Authors: Viswanathan Ravi , Schwartz D.K. , Madsen L.L. , Zasadzinski J.A. 
Published: April 2011

ABSTRACTThe Atomic Force Microscope (AFM) has created exciting new possibilities for imaging thin organic films under ambient conditions at length scales ranging from tens of microns to the sub - molecular scale. We present images of thin organic films prepared by the Langmuir-Blodgett (LB) technique that demonstrate the possibilities of the AFM.
Structural and Magnetic Properties of Epitaxially Grown Fcc Fe/Cu(100) and Fe/CaF2/Si(111)
Authors: Scheinfein M.R. , Healy S.D. , Heim K.R. , Yang Z.J. , Drucker J.S. , Hembree G.G. 
Published: April 2011

ABSTRACTWe have used nanometer spatial resolution secondary electron and Auger electron imaging in an ultra-high vacuum scanning transmission electron microscope to characterize microstructure in ultrathin films of Fe/Cu(100) grown at room temperature and Fe/CaF2/Si(111) grown at room temperature and 150 C. Thin film microstructure was correlated in situ with magnetic properties by using the surface magneto-optic Kerr effect.
Atomic Scale Characterization of (NH4)2Sx-Treated GaAs (100) Surface
Authors: Yokoi Naoki , Andoh Hiroya , Takai Mikio 
Published: April 2011

ABSTRACTThe geometric structure of GaAs (100) surfaces, treated in a (NH4)2Sx solution and annealed in N2 environment, has been studied in an atomic scale using high-resolution Rutherford backscattering (RBS), X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM). RBS analysis using medium energy ion scattering (MEIS) could provide the thickness of the sulfur layer on the GaAs surface of about 1.5 monolayers. RBS channeling spectra indicated that the disorder of atoms in the surface region of S-terminated samples was smaller than that of untreated one. XPS spectra showed that S atoms on the surface bonded only As atoms. STM observation revealed that S atoms had a periodicity of 4 Å corresponding to that of Ga or As atoms in the (100) plane.
Size-effect Stabilization of the Low-T Ferroelectric Phase in Nanocrystalline WO3
Authors: Bi Xiang-Xin , Lee W. T. , Wang Kai-An , Collins D. F. , Bandow S. , Eklund P. C. 
Published: April 2011

ABSTRACTUsing a CO2 laser to drive the pyrolysis of W(CO)6 and O2, we have synthesized nanocrystalline WO3-x particles. These nanopowders are found to exhibit a narrow size distribution with an average particle size produced in the range 5 to 10 nm, depending on the experimental conditions. Typical production rates are ∼ 2 g/h. Results from a Raman scattering study on WO3 nanopowder samples annealed in O2 indicate that a smaller particle size appears to stabilize the low-T ferroelectric phase ( < -40 °C) at room temperature.