bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of Fullerene in Solution with Free Electron Laser Irradiation
Authors: Iwata Nobuyuki , Iio Yasunori , Ando Shigo , Nokariya Ryo , Yamamoto Hiroshi
Published: April 2011

The free electron laser (FEL) of 450 or 500 nm was irradiated onto the pressed C60powder in vacuum. The grains with μm-order were observed showing the colors of blue, purple, yellow, and white in optical microscope images. The Ag(2) derived mode around 1460 cm−1in Raman spectra was observed from the grain, indicating the polymerization. The 100 μm-length grain was obtained just after dissolving the FEL irradiated specimens into the toluene and evaporating it. In order to expand the scale of C60polymer grains and to obtain an amorphous C60polymer, the FEL irradiation was carried out in solution to reduce the directivity for polymerization. Although polymerization was not promoted in C60precipitation in supersaturated solution due to low density of C60, the precipitation grown with the liquid-liquid interfacial precipitation (LLIP) method showed the 1454 cm−1Ag(2) derived mode in addition to the peaks around 1460 cm−1in toluene. In m-xylene with LLIP method, in a whole area of C60pillar-grains, polymerization was confirmed by the Raman analysis.
An AlGaAs/InGaAs HEMT Grown on Si Substrate with Ge/GexSi1-x Metamorphic Buffer Layers
Authors: Chang Edward , Lin Yueh-Chin , Hsiao Yu-Lin , Hsieh Y.C. , Chang Chia-Yuan , Kuo Chien-I , Luo Guang-Li
Published: April 2011

An AlGaAs/InGaAs HEMT grown on Si substrate with Ge/GexSi1−x buffer is demonstrated. The Ge/GexSi1−x metamorphic buffer layer used in this structure was only 1.0 μgm thick. The electron mobility in the In0.18Ga0.82 As channel of the HEMT sample was 3,550 cm2/Vs. After fabrication, the HEMT device demonstrated a saturation current of 150 mA/mm and a maximum transconductance of 155 mS/mm. The well behaved characteristics of the HEMT device on the Si substrate are believed to be due to the very thin buffer layer achieved and the lack of the antiphase boundaries (APBs) formation and Ge diffusion into the GaAs layers.
Epitaxial Growth of Single Crystalline Ge Films on GaAs Substrates for CMOS Device Integration
Authors: Chin Hock-Chun , Zhu Ming , Samudra Ganesh , Yeo Yee-Chia
Published: April 2011

We report a novel chemical vapor deposition (CVD) process for epitaxial growth of Ge film on GaAs substrate. The resultant layer exhibits device level quality, as shown by high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, high-resolution X-ray diffraction (HRXRD). In addition, atomic force microscopy (AFM) scanning indicates low RMS surface roughness of 5 Å. Secondary ion mass spectrometry (SIMS) reveals negligible out-diffusion of Ga and As into the Ge epilayer. By employing silane passivation, Ge p-MOSFET with TaN/HfO2 gate stack was fabricated on Ge/GaAs heterostructure for the first time, showing excellent output and pinch-off characteristics. A GaAs channel n-MOSFET was also fabricated, using similar SiH4 treatment during gate stack formation. These results reveal a potential solution to integrate Ge p-channel and GaAs n-channel MOSFET for advanced CMOS applications.
Effect of Au Nanocrystals Embedded in Conductive Polymer on Non-volatile Memory Window
Authors: Seung Hyun Min , Lee Jong Dae , Han Byeong-Il , Lee Gon-Sub , Park Jea-Gun
Published: April 2011

Recently, non-volatile polymer memories have been researched as a next generation of non-volatile memory because of its simple structure and easy fabrication process. We found that two types of non-volatile polymer memory have different I-V behavior. First Polymer non-volatile memory with metal / oxide / polymer / metal structure But Polymer non-volatile memory embedded Au Nano-crystal shows different I-V behavior. Polymer non-volatile memory shows NDR(Negative Differential Resistance) Region after threshold voltage and low to high current path at increasing positive and negative bias. We can observe NDR(Negative Differential Resistance) Region on Polymer non-volatile memory embedded Au Nano crystal. We fabricated devices three different type to confirm difference Polymer non-volatile memory with metal / polymer / metal structure, metal / oxide / polymer / metal structure and Au nano-crystal embedded Polymer non-volatile memory. First we fabricated Polymer non-volatile memory with metal / PVK(Poly-n-vinyl carbarzole) / metal structure. first type of device shows ohmic I-V behavior. Second type of polymer non-volatile memory has oxide layer between metal and polymer layer. Oxide layer made by O2 plasma treatment(100W RF power, 100SCCM O2 gas flow) after metal layer deposited. Second type of device has same structure as first device except oxide layer. Second type of device shows I-V behavior similar to Resistive Memory. Resistive non-volatile memory shows low to high current path at increasing positive bias and high to low current path at increasing negative bias. I-V behaviors of second device due to effect of oxide layer between metal and polymer layer. Third type of polymer non-volatile memory we embed Au nano-crystal layer in polymer layer. Au nano-crystal layer embedded by curing process. We deposit 5nm Au layer after spin coated PVK(Poly-n-vinyl carbarzole) layer and curing at 300¡É. We can observe NDR(Negative Differential Resistance) Region and different I-V behaviors with other type of device. Finally we fabricated polymer non-volatile memory embedded au nano-crystal by dispersion method to confirm effect of au nano-crystal. We report difference I-V behaviors polymer non-volatile memory with metal / polymer / metal structure and polymer non-volatile memory embedded au nano-crystals
Organic Field Effect Transistors Having Hundreds of Nanometers Long Channels
Authors: Shang Liwei , Liu Ming , Tu Deyu , Zhen Lijuan , Liu Ge , Liu Xinghua
Published: April 2011

This work studied systemically the device characteristics when the OFETs' channels turn into hundreds of nm. Standard planar OFETs have been fabricated using electronic beam lithography. Copper phthalocyanine is used as the semiconductor materials. When reduce the L to about 300 nm will lead an abrupt degradation of device performance. The ratio of Ion/Ioff turns from several hundreds into couple of tens. And when change the L to about 100 nm, the mobility turns from 10−2 cm2/Vs into 10m5 cm2/Vs, and the threshold voltage turns from about 12 V into 36 V. These abrupt changes are due to the changes of interface between active layer and insulator layer caused by the reducing the L to close to the grain size.
Synthesis of Functional Materials by Means of Nitriding in Salts of Al2O3–Al, Al2O3–Ti and Al2O3–Fe Cermets
Authors: Miranda-Hernández José G. , Refugio-Garcia Elizabeth , Rocha-Rangel Enrique
Published: April 2011

In this work the synthesis of functional gradient materials (FGMs) through the nitriding in salts of previously fabricated cermets is carried out. The matrix for the preparation of the FGMs is made of an Al2O3-based cermet with a fine and homogeneous dispersions of metallic particles of Al, Ti and Fe, the final content of the metallic particles in the cermets is of 10 vol. %. These materials are synthesized by powders techniques, considering as variable of study the reinforcement metal in the cermet, previous to sinter, cylindrical samples of the corresponding cermet are uniaxially compacted using 200 MPa. Subsequently, all sintered cermets are characterized by microstructural observations with the help of light microscopy. Obtained cermets are then submitted to a nitriding process by immersion in ammoniac salts. The objective is to attain a compositional gradient of metal-nitrides at the surface. This is done through a chemical reaction between the metallic particles at the cermets' surface and the nitrogen released by the ammonia salts. Functional materials are obtained such as; Al2O3–Al–AlN and Al2O3–Ti–TiN.
Alumina Extraction from Mexican Fly Ash
Authors: López-Cuevas Jorge , Long-González David , Gutiérrez-Chavarría Carlos A. , Rodríguez-Galicia José L. , Pech-Canul Martín I.
Published: April 2011

Two alternative chemical methods are studied for the extraction of Al2O3 from Mexican Fly Ash (FA). Reaction of FA with H2SO4 at high temperature allows extracting ∼37% of the total Al2O3 contained in the FA as Al2(SO4)3, regardless of H2SO4 concentration, treatment time and temperature employed. This is partly due to the high chemical resistance of mullite (Al6Si2O13) contained in the FA. In contrast, reaction of FA with a CaCO3-Na2CO3 mixture at 1300°C/1h, followed by lixiviation with a Na2CO3 aqueous solution and precipitation of bohemite [AlO(OH)] by addition of either H2O2 or NH4HCO3, allows extracting ∼80% of the total Al2O3 contained in the FA as θ-alumina, after calcination of bohemite at 1200°C/1h.
Hot deformation behavior of low carbon advanced high strength steel (AHSS) microalloyed with boron
Authors: Mejía I. , González-Sala S. , Cabrera J.M.
Published: April 2011

This research work deals the influence of boron content on the high temperature deformation behavior of a low carbon advanced high strength steel (AHSS). For this purpose high temperature tensile and compression tests are carried out at different temperatures and constant true strain rates by using an Instron testing machine equipped with a radiant cylindrical furnace. Tensile tests are carried out at different temperatures (650, 750, 800, 900 and 1000°C) at a constant true strain rate of 0.001 s-1. Uniaxial hot compression tests are also performed over a wide range of temperatures (950, 1000, 1050 and 1100°C) and constant true strain rates (10-3, 10-2 and 10-1 s-1). In general, experimental results of hot tensile tests show an improvement of the hot ductility of the AHSS microalloyed with boron, although poor ductility at low temperatures (650 and 750°C). The fracture surfaces of the AHSS tested at temperatures showing the higher ductility (800, 900 and 1000°C) indicate that the fracture mode is a result of ductile failure, whereas in the region of poor ductility the fracture mode is of the ductile-brittle type failure. On the other hand, experimental results of hot compression tests show that both peak stress and peak strain tend to decrease in the AHSS microalloyed with boron, which indicates that boron generates a sort of solid solution softening effect in similar a way to other interstitial alloying elements in steel. Likewise, hot flow curves of the AHSS microalloyed with boron show an acceleration of the onset of dynamic recrystallization (DRX) and a delay of the recrystallization kinetics. Results are discussed in terms of boron segregation towards austenitic grain boundaries and second phase particles precipitation during plastic deformation and cooling.
Nanostructures Detected by Conductvity Spectroscopy
Authors: Funke K. , El—egili K. , Reichelt R. , Amrein M. , Cramer C.
Published: April 2011

Measurement of frequency dependent ionic conductivities is shown to be a simple and effective means for the detection and characterization of nanostructures in solid electrolytes. As an example, the conclusions drawn from the conductivity spectrum of a silveriodide/silver-borate glass are compared with scanning electron and scanning tunneling micrographs. The results consistently prove the existence of nanoscale heterogeneities about 25 nm in diameter.
Low Voltage Point Projection Microscopy and Time of Flight Stm - Two New Microscopies
Authors: Spence J.C.H. , Qian W. , Lo W. , Mo S. , Knipping U. , Zhang X.
Published: April 2011

The design of a low voltage point-projection field-emission transmission electron microscope is described and images showing 0.7nm resolution at 100 volts are given. A scheme for low voltage reflection electron holography from bulk samples in UHV is outlined. A new STM is described which allows atomic clusters to be transferred onto the tip, then introduced into a time-of-flight analyser for species identification.
Trends in Atomic Resolution Electron Microscopy
Authors: Smith David J. , Mccartney M.R.
Published: April 2011

Structural information on the atomic scale is readily accessible from thin samples using the technique of high-resolution electron microscopy. Electron micrographs recorded under well-defined operating conditions can be directly interpreted in terms of atomic arrangements around defects of interest such as dislocations and interfaces. Digital image recording with slow-scan CCD cameras and quantitative comparisons with image simulations based on structural models are starting to lead to improved accuracy and reliability in structure determinations. Techniques based upon holographic methods are utilizing the superior illumination coherence of the field emission electron source to enhance resolution beyond the conventional extended Scherzer limit. Innovative methods for combining image and diffraction pattern information are also leading to improved levels of resolution for periodic objects. Care is needed to ensure that electron irradiation damage and surface cleanliness do not impose unnecessary restrictions on the details that can be extracted from recorded micrographs. It is proposed that the complex wavefunction emerging from the exit-surface of the sample should be considered as a basis for comparing the differences between experimental micrographs and image simulations.
Geometric Characterization of Electromigration Voids
Authors: Kime Yolanda J. , Grach Peter
Published: April 2011

The areas, perimeters, lengths, and widths of 998 electromigration induced voids on 38 test stripes have been measured by SEM and digital image analysis. Virtually all of the voids occurred along the passivation-conductor interface on the side of the stripe. Plots of number of voids or total void area versus time to failure do not extrapolate to zero voids at zero time to failure which suggests there is a certain number of active nucleation sites predisposed to voiding.
Electromigration Damage in Conductor Lines: Recent Progress in Microscopic Observation and Mechanistic Modelling
Authors: Arzt E. , Kraft O. , MÖckl U.E.
Published: April 2011

In this paper an overview of recent developments in understanding electromigration damage mechanisms is given. Based on our detailed studies, both ex-situ and in-situ, of damage in unpassivated near-bamboo lines, we develop a theoretical electromigration damage map. It explains why “slit-like” failure becomes predominant for narrow lines and low current densities. The mechanism of slit formation is discussed in the light of new analytical and numerical simulations of pore shape changes, which take stress effects into account. Possible implications for the rational design of improved metallization alloys are suggested.
Real-Time Thermo-Mechanical and Adhesive Property Evaluation of Thin Films and Multi-Layers
Authors: Rogers John A. , Nelson K. A.
Published: April 2011

We describe an experimental method useful for in-situ real-time evaluation of viscoelastic, thermal and adhesive properties of thin films and multi-layer structures. We demonstrate how the technique is used to quantify the elastic moduli, and in-plane thermal diffusivity. We also show how it can be used to “spot check” for dis-bonds and to generate dis-bond “maps”.
Adhesion Strength of Cu/Polyimide Interfaces by Micro-Wedge Scratching
Authors: Wang F. , Nelson J.C. , Huang H. , Swisher R. L. , Gerberich W.W.
Published: April 2011

The micro-wedge scratch technique was applied to characterize interfacial properties of copper fine lines on PMDA-ODA polyimide. A 20 pm wide, 0.1 μm radius wedge-shapeddiamond tip was used to mechanically debond Cu fine lines from polyimide substrate. Copper fine lines varies from 0.2 to 0.4 μm thick, and from 1.μm to 100 μm wide. Both cohesive and adhesive delaminations were obtained. Loaddisplacement curves were recorded and the scratch morphologies were observed by SEM. From a first order calculation, the fracture toughness of the polyimide and interfacial strength of Cu-PI were obtained.
Epitaxy of YBa2Cu3O7-xon Silicon on Sapphire: Possibilities and Limits
Authors: Copetti C. A. , Wang F. , Schubert J. , Schulz H. , Zander W. , Buchal Ch.
Published: April 2011

We present investigations of YBa2Cu3O7-x, thin films deposited on Silicon on Sapphire (SoS) substrates by pulsed laser deposition and dc sputtering. A compound buffer system consisting of YSZ and CeO2 is used for improved YBa2Cu3O7-x growth characteristics. The critical thickness of YBa2Cu3O7-x on CeO2/YSZ/SoS is determined to be 280 nm.
Epitaxial Oxide Films
Authors: Geballe Theodore H.
Published: April 2011

Some perspective concerning the capabilities and potential of epitaxial oxide films is gained by comparison with the field of semiconductor epitaxy. The specific epitaxial behavior of MgO, (ZrY)O2, and the layered cuprates is discussed. A suggestion is given for a method of searching for higher temperature superconductors by the use of epitaxial indusions in layered structures.
Structure and Magnetic Properties of Epitaxial NiFe2O4 Films
Authors: Dover R. B. van , Venzke S. , Gyorgy E. M. , Siegrist T. , Phillips J. M. , Marshall J. H. , Felder R. J.
Published: April 2011

We have made NiFe2O4 films by rf sputtering using the 90 °off-axis geometry. Films grown at 600°C on SrTiO3 and Y.15Zr.85O2 substrates are single crystals with (100) and (110) texture, respectively, but exhibit a very large and unexpected random anisotropy. A postdeposition air anneal at ˜1000°C has little effect on the crystallinity of the films but almost completely eliminates the random anisotropy; the remaining anisotropy is consistent with expected (bulk) values. A decrease of the saturation magnetization, indicating degradation, was observed for films on SrTiO3 (but not Y.15Zr.85O2) annealed at 1300°C.
Common Themes in ther Epitaxial Growth of Oxides on Semiconductors
Authors: Tarsa E. J. , Mccormick K. L. , Speck J. S.
Published: April 2011

A review of the growth of oriented oxides on Si and Ill-V semiconductors provides insight into some of the common themes of oxide/semiconductor epitaxy. The nature and success of the epitaxy can be attributed to four primary factors: (i) semiconductor surface preparation; (ii) oxide/semiconductor reaction thermodynamics; (iii) surface and interfacial polarity; and (iv) structural matching (lattice matching, thermal expansion, and symmetry). Semiconductor surface preparation governs the initial stages of epitaxy for systems such as MgO/GaAs and In2O3/InAs. In these cases, the epitaxial development depends on the presence or absence of a native oxide layer prior to growth. Chemical reaction can also influence the epitaxial process, as is illustrated in the growth of gadolinium oxide on Si. In general, the initial stages of epitaxy reflect a thermodynamic competition between the formation of the desired oxide phase, oxidation of the semiconductor, and formation of intermediate phases such as silicides and silicates. An analysis of possible reactions is presented for selected binary and ternary oxides with Si and GaAs. Surface and interfacial energy can also play an important role in determining the morphology and orientation of oxides having polar low-index faces, as illustrated in the growth of fluorite and related bixbyite oxides such as CeO2, In2O3and Y2O3. The epitaxial relationships between the oxide and semiconductor may be rationalized in terms of either direct lattice matching or higher order epitaxy.
Investigation of Titanium Silicide Formation Using Secondary Ion Mass Spectrometry
Authors: Wee Andrew T.S. , Huan Alfred C.H. , Thian W.H. , Tan K.L. , Hogan Royston
Published: April 2011

Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) are used to investigate Ti silicide formation mechanisms on a series of Ti on Si thin films annealed in ultrahigh vacuum (UHV) at different temperatures and durations. The competition between oxygen diffusion and the silicide formation reaction (the socalled “snowplough” effect) is observed directly, as well as a Ti-Si-O layer. The results from these controlled experiments are compared with those from Ti silicide films formed under rapid thermal annealing (RTA) conditions in a production furnace, with and without a TiW barrier layer.
Speckle Techniques for Noncontact Temperature Measurement
Authors: Burckel D. , Zaidi S. H. , Lang M. K. , Frauenglass A. , Brueck S. R. J.
Published: April 2011

Two complementary speckle techniques for the measurement of temperature from the rough back surface of Si wafers during rapid thermal processing are demonstrated. Electronic speckle pattern interferometry is a full field intensity cross-correlation technique that provides a two-dimensional map of the surface temperature. Measurements are presented that demonstrate a resolution of ∼ ±2°C. A new speckle technique, sub-feature speckle interferometry is introduced. This technique provides a much more rapid and precise averaged temperature measurement by monitoring the strain between two points with interferometric precision usually associated with moird interferometry or holography rather than speckle. Preliminary measurements are presented that demonstrate the capability of the technique.
Selective Epitaxial Silicon and Selective Titanium Silicide in an Industrial Integrated Cluster Tool
Authors: Regolini J. L. , Margail J. , Morin C. , Gouy-Pailler P.
Published: April 2011

Integrated processes for IC manufacturing are today of prime importance for obtaining such high performance results as uniformity on large diameter wafers, reproducibility, throughput and reliability. Using an industrial integrated cluster reactor we have obtained selective epitaxial Si and selective TiSi2 deposition. This is a 200 mm reactor in which epitaxial silicon has been obtained with <1% (1σ) thickness uniformity and <2% over a 25 wafer batch. Full selectivity of Si on oxide has been obtained below a 20 Torr working pressure using the DCS/H2 gas system. No loading effect has been detected. The main characteristics of this system are described with the most relevant results like: sharp interfaces obtained in Si0.7Ge0.3/Si multilayer structures grown at 650°C, abruptly doped epitaxial layers and residual defect density.

TiSi2 has been selectively obtained with minimum substrate consumption using the H2/SiH4 (or DCS)/TiC14 chemistry. The elevated source & drain has also been successfully tested by selective Si epitaxy followed by “in situ” selective TiSi2 deposition to compensate for substrate consumption.
Optical, Electrical, and Mechanical Characterization of Rapid Thermal Oxidation
Authors: Yarling C. B. , Keenan W. A.
Published: April 2011

In this study, 6-150mm p-type <100> wafers were cleaned, laser-scribed, and pre-process measured for stress. The wafers were then processed in a tungsten-halogen lamp RTP system with a target Rapid Thermal Oxidation (RTO) thickness of 100Å. Three categories of whole-wafer measurement techniques were used to characterize these wafers: optical, electrical, and mechanical. Optical inspection techniques included spectroscopic reflectometry (reflectivity), and a combination of beam profile reflectometry and beam profile ellipsometry (thickness). Electrical techniques included C-V plotting with a mercury probe (oxide thickness from Cmax, breakdown voltage, and interface trap density) as well as laser-induced photo-current scanning (minority carrier lifetime, minority-carrier diffusion-length). Mechanical inspection included wafer warpage and stress measurements as well as optical imaging inspection using the magic mirror method (damage and defects). Wafer measurements from these instruments (i.e., contour and 3-d maps) are used to characterize integrity of the RTO process.
Growth and Photoluminescence of Strained < 110 > Si/SilxGex/Si Quantum Wells Grown by Rapid Thermal Chemical Vapor Deposition
Authors: Liu C. W. , Sturm J.C. , Lacroix Y. R. J. , Thewalt M. L. W. , Perovic D. D.
Published: April 2011

We report the first chemical vapor deposition growth and systematic photoluminescence study of strained Si1–xGex alloy layers on < 110 > Si substrates. Compared to < 100 > Si substrates, the same growth conditions yielded a slightly lower Ge composition, but a much lower growth rate. For thick layers, the relaxation along [110] direction is insufficient and lead to predominantly uniaxial strain in the the films. From the photoluminescence, the bandgap of strained Si1–x.Gex on < 110 > Si for 0.16 ≤ x ≤ 0.43 is determined and compared to theory. A strong “no-phonon” emission process in photoluminescence spectra of strained < 110 > Si/Si1–x.Gex/Si was observed as compared with that observed in < 100 > layers. Finally, quantum confinement shift of Si/Si0.71 Ge0.29/Si wells with a confinement energy up to 110 meV has been observed by varying the well width from 133 Å to 17 Å.
Three-Dimensional Asymmetrical Modeling of Rapid Thermal Annealing of Silicon Wafers
Authors: Nagabushnam V. , Singh R.K.
Published: April 2011

We have developed an analytical tool to predict temperature variations occuring both across the wafer and down the thermal cycles, based on very simple 3-dimensional physical models depicting the heat transfer processes taking place during a typical rapid thermal processing (RTP) step. This model takes into account the convective and the radiative heat losses along with the thermal conduction within the wafer. An hybrid control volume formulation has been used to solve the heat conduction equation to yield numerical solutions of temperature variation, both on and within the wafer. The effect of ambient gas flow direction and the related asymmetric convective heat loss on the temperature non-uniformity across the wafer at different stages of the thermal cycle is well analyzed. Finally, the temperature non-uniformity across a wafer patterned with oxide is examined.
Analysis of Critical Parameters Affecting the Temperature Uniformity During Rapid Thermal Processing
Authors: Nagabushnam V. , Sing R.K. , Thakur R.P.S.
Published: April 2011

In this work we examine the effect of various system and wafer parameters such as the flowing ambient, the spatial distribution of incident energy flux, the slip-free ring and doping density on temperature non-uniformity occurring during rapid thermal processing (RTP). The effect of using two inert ambients, i.e. argon and nitrogen, on temperature non-uniformity occurring during RTP cycle is studied in detail. The importance of dynamic lamp power control in providing time dependent spatial variation of incident energy flux as a measure to improve the temperature uniformity is also examined. Finally the simulation studies are also done in the presence of a slip-free ring. The nature of photon capture by the silicon wafer and the correlation between doping density and the steady state temperature for any given open loop condition is discussed in detail. This analysis has been done using an analytical tool developed by us based on simple 3-dimensional physical models depicting a typical rapid thermal cycle[1].
Transition Metal-Promoted Oxygen Ion Conductors as Oxidation Catalyst
Authors: Liu Wei , Sarofim Adel , Flytzani-Stephanopoulos Maria
Published: April 2011

A novel metal oxide composite catalyst for the complete oxidation of carbon monoxide and hydrocarbons was prepared by combining oxygen ion conducting materials with active transition metals. The oxygen ion conductors used were typical fluorite-type oxides, such as ceria, zirconia, and others. Active base metal catalysts, such as copper, were used as additives to promote the catalytic properties of oxygen ion conductors. The intimate contact of the two kinds of materials gave rise to a highly active oxidation catalyst. On Cu-Ce-O composite catalysts, 95% of carbon monoxide was oxidized by air at ∼100 °C. Complete methane oxidation on the same catalyst took place at ∼550 °C. When the stoichiometric amount of sulfur dioxide was used to oxidize carbon monoxide, 96% of sulfur dioxide was reduced to elemental sulfur at temperatures above 460 °C with 99% of sulfur dioxide conversion. This type of composite catalyst also showed excellent resistance to water poisoning.
Deactivation of Alumina Supported Catalysts Due to Spinel Formation
Authors: Bolt P. H. , Van Ipenburg M. E. , Geus J. W. , Habraken F. H. P. M.
Published: April 2011

An important cause of deactivation of alumina supported transition metal (oxide) catalysts is a solid state reaction between the active component and the support. We therefore studied the hightemperature behavior of Me layers (Me = Co, Ni, Cu and Fe) on polycrystalline α-A12O3 and γ- Al2O3 substrates. The samples were first oxidized at moderate temperatures and then annealed at high temperatures (up to 1000 °C) in O2, N2, or N2/O2 mixtures. The interfacial reaction to MeA12O4 was assessed using Rutherford Backscattering Spectrometry and X-ray diffraction. The reaction rate strongly depends on the transition metal element Me: Fe < Ni < Co < Cu. Low oxygen pressures favour spinel formation. γ-A12O3 shows a much higher reactivity towards the MeOx overlayers than α-Al2O3.
Biodegradation of Polymer Coatings
Authors: Jones William R. , Walch Marianne , Jones-Meehan Joanne
Published: April 2011

Conventional paint removal methods include chemical stripping with VOCs, blasting with plastic media, and delamination with high pressure water. These methods have many limitations, in that they are labor intensive, pose human health risks, are relatively expensive and pose significant waste disposal problems. However, polymeric coatings are known to contain structural components, such as ester, amide and urea linkages, that can be degraded biologically. We are working to develop a stable, enzyme-based, non-toxic paint stripping strategy that will be environmentally safe and cost effective.

The specific objectives are to identify and characterize microbial systems capable of degrading polymeric coatings, to develop a quantitative degradation assay and to optimize activity levels for subsequent purification and concentration of the biological products required for rapid degradation of coatings.

A water-dispersed colloid of an ester-based polyurethane polymer has been used in solid growth medium to screen about 100 different bacteria for microbial degradation activity. Those with demonstrable activity have been grown in the presence of epoxypolyamide paint- and polyester polyurethane paint-coated aluminum coupons. We have demonstrated delamination under certain conditions and have developed a spectrophotometric method for quantitating degradation activity as a function of dye release.
Plasma Enhanced Chemical Vapor Deposition of Silicon Nitride from Novel Organosilanes
Authors: Grow J. M. , Levy R. A. , Yu Y. , Shih K. T.
Published: April 2011

The environmentally benign precursors diethylsilane and di-t-butylsilane were used with NH3 to synthesize silicon nitride films by plasma enhanced chemical vapor deposition. The growth kinetics and film properties were examined as a function of deposition temperature, total pressure, and NH3/organosilane ratio. The growth rate was observed to decrease with higher temperature and higher NH3/organosilane ratio while increasing with higher total pressure. Values of index of refraction, film stress, hardness, and Young's modulus were measured as a function of processing variables and related to film density and resulting film composition. Oxidation of the films was noted to occur at high pressures, low temperatures, and low NH3/organosilane ratios. Carbon incorporation was present for all deposits and appeared not to be dependent on processing conditions.
Characterization of Sol-Gel Derived Composite Silica Carbon
Electrodes
Authors: Gun Genia , Tsionsky Michael , Lev Ovadia
Published: April 2011

Sol-gel derived composite silica-carbon electrodes exhibit favorable
electrochemical characteristics. The electrodes benefit from the
conductivity and electrochemical advantages of the carbon powder, from the
favorable properties of the ceramic network and from the versatility of the
sol-gel process. Hydrophobie composite electrodes reject water, only their
outermost surface is wetted and they exhibit good signal to background
currents. A comparison of several types of carbon powders reveals that
higher carbon loading and larger surface area electrodes can be attained by
incorporation of dense graphite powder. When high surface area, small size
carbon-black powder is used, a homogeneous distribution of microelectrodes,
separated by insulating modified silica is formed. This ensemble of
microelectrodes increases the sensitivity of the CCEs by more than two
orders of magnitude as compared to glassy carbon electrode and graphite
CCEs.
Sol-Gel Glasses as New Waveguides for Optical
Immunosensors
Authors: Collino R. , Therasse J. , Chaput F. , Boilot J-P. , Levy Y.
Published: April 2011

In order to develop an optical immunosensor based on Surface Plasmon
Resonance (SPR) and guided waves propagation, the sol-gel process has
been used to prepare thin films of amorphous silica, deposited by spin
coating on a gold-coated glass slide, and possessing chemically active
functional groups (SH, NH2...). After activation of the sol-gel film in
aqueous buffers by a bifunctional coupling agent, biological molecules
such as antibodies could be covalently bonded on or inside the sol-gel
film. Therefore, the behaviour of the functionalized silica thin films in
aqueous solutions has been analyzed by SPR and guided waves propagation.
The matrix hydrophilicity has been studied with different mixtures of
functionalized silicon precursors forming organic-inorganic hybrid films.
Immunoassays outline the possibility of obtaining covalent binding of
antibodies to the sol-gel matrix with optimal stability and biological
activity.
Preparation of Stabilized Zirconia Using A Mixture of Rare Earth Oxides as Dopant
Authors: Santos Adelina P. , Fernandes Rosana Z. D.
Published: April 2011

The present work deals with the effect of the rare earth nature and the content of the oxide dopants on the stabilization process of zirconia based ceramics. There are two main interests in our work. The first is to verify the possibility of stabilizing a cubic structure of zirconia using a natural mixture of rare earth elements as dopant, and second, to study and to characterize its basic physical-chemical properties such as phase diagrams, zirconia stabilization models and dopant distribution.
Mechanical and Microstructural Properties of Two-Step Acid-Base
Catalyzed Silica Gels
Authors: Meyers D. E. , Kirkbir F. , Murata H. , chaudhuri S. Ray , Sarkar A.
Published: April 2011

The mechanical and microstructural properties of two-step acid-base
catalyzed silica gels were examined as functions of aging time, catalyst
concentration, and hydrolysis time. Cylindrical gels were prepared using
Si(OC2H5)4,
C2H5OH, and H2O, with HCl followed by
NH3 as catalysts. Mechanical properties were obtained from
three-point bend tests, and the microstructures of dried gels were analyzed
using nitrogen adsorption/desorption techniques. Gel strength initially
increased with aging time at 70 °C, then leveled off after about one week.
When the sol was hydrolyzed for less than two hours, there were significant
differences in the properties of gels catalyzed with relative molar amounts
of 0.0001 and 0.0002 HCl. However, as the hydrolysis time was increased, the
gels all had similar properties, independent of the amount of HC1. The
amount of NH3 influenced gelation time and to a lesser extent, the strength,
but had no observable effect on pore size. The two-step catalysis procedure
produced gels with strength and pore size combinations intermediate to those
of either single acid or base-catalyzed gels.
Spectroscopic Studies of Chemical Reactions and Dynamics in
Sol-Gel Matrices
Authors: Akbarian F. , Dunnt B. , Fuquat P.D. , Mckiernan J. , Simoni E. , Zink J.I.
Published: April 2011

The synthesis of sol-gel glasses containing organic and organometallic
molecular dopants has been well established as an approach for creating new
optical materials. Some of these properties are dependent upon chemical
reactions which occur in porous xerogel matrices during the sol-gel process
or when encapsulated molecules are exposed to other molecules in solution.
In this paper, the study of two different types of chemical reactions in the
pores of xerogel matrices is reported. In one case copper phthalocyanine is
used to characterize dimerization within the pores. The results show that
dimer formation is most likely to occur towards the end of the drying stage
as the dye concentration in the pores increases from solvent evaporation. A
second example involves the use of a pump-probe technique to determine the
rate of proton recombination inside the pores of silica monoliths. The
behavior of sols and gels is similar to aqueous solution while recombination
of protons in the xerogel seems to be affected by the walls of the
pores.
Additive-Coated Si3N4 Powder Prepared By
The Sol-Gel Method
Authors: Ge Manzheng , Kan Honghua , Yang Hui , Qiao Jianmin , Jiang Zhonghua
Published: April 2011

The Y2O3-La2O3 additive-coated
Si3N4 powders of about 1.5 μm in size were prepared
by the sol-gel method. X-ray diffraction, X-ray photoelectron spectroscopy,
differential thermal analysis, thermogravimetric analysis, electron
microscopies, and particle size analysis were used to study the coating on
the Si3N4 particles. The results show that properties
of the bulk Si3N4 powder are not affected by using the
sol-gel coating and the powders are homogeneously coated by a thin layer of
the Y2O3-La2O3 additives. The
structure of the Y2O3-La2O3
coating layer is amorphous or microcrystalline with a submicron thickness.
The coated powders are then more sinterable, and the mechanical properties
of the ceramics prepared from such powders are improved.
Electronic Properties and Formation Mechanism of Metallo-Carbohedrenes
Authors: Kawazoe Yoshiyuki , Gu Bing-Lin , van Schilfgaarde Mark , Yu Jing-Zhi , Ohno Kaoru
Published: April 2011

We have calculated the structure and electronic properties of several metallo-carbohedrenes within the local density-functional approximation, using both methods of a linear combination of atomic orbitals and full-potential muffin-tin orbitals. The calculated density of states and Mulliken population of double cage Ti14C21and triple cage Ti18C29are quite similar to that of single cage Ti8C12. There is no additional cohesion in multicage structure, which may explain why there is not a strong tendency to form larger, multi-cage structures. A new stable structure for Ti8C12is also proposed and structures Ti10C12+x(x=1, 2, 3, 4, 5) have also been discussed.
A Study on the Purification methods of Carbon Nanotubes and Stm Imaging of the Carbon Nanotubes
Authors: Yumura Motoo , Uchida Kunio , Niino Hiroyuki , Ohshima Satoshi , Kuriki Yasunori , Yase Kiyoshi , Ikazaki Fumikazu
Published: April 2011

Abstracts

Purification process to obtain nanotubes out of the cathode product mostly including fragments of graphitic sheet and/or amorphous carbon has been established. Structures and electronic properties of carbon nanotubes were studied. By the Raman scattering measurement, only one peak at 1581 cm−1 akin to that of graphite was found out. It was confirmed by STM observation of purified nanotubes. Purified nanotubes was semiconductor or semimetal.
Measurements of the Conductivity of Individual 10 Nm Carbon Nanotubes
Authors: Whitesides George M. , Weisbecker Carl S.
Published: April 2011

Catalytically grown carbon fibers approximately 10 nm in diameter and several microns long were characterized by transmission electron microscopy and determined to be multiple-walled nanotubes, and a technique was developed to measure the conductivity of an individual nanotube. Nanotubes were dispersed in solvents and precipitated onto lithographically defined gold contacts to make a ‘nano-wire’ circuit. Non-contact AFM was used to image the nano-wires, and a resistance of 11.4 (± 1.0) MΩ was measured through a single nanotube at 23°C. A resistivity of 9.5×10−5 Ω m was estimated for carbon conducting along the axis of a fiber. Local heating of nanotubes appeared to occur at high current densities. The nanotubes could sustain currents on the order of 10 μA per fiber, but application of currents on the order of 100 μA per fiber resulted in rapid decomposition in air and breaking of the circuit.
Optical Properties of Amorphous Carbon Doped with Copper
Authors: Ivanov-Omskii Vladimir I. , Abaev M.I. , Yastrebov S.G.
Published: April 2011

We report the optical properties of amorphous C:Cu films produced by co-sputtering of graphite and copper targets in an argon plasma. Ellipsometric measurements at 632.8 nm were performed to evaluate dielectric permittivity vs copper content. We have observed a pronounced peculiarity of imaginary and real parts of the dielectric function at a copper content of about 14%. A correlation between the concentration dependence of the DC conductivity and that of the imaginary part of permittivity is clearly demonstrated. This correlation points to the existence of a less-conductive phase with the stoichiometric formula CuC6.
Aspects of the Mechanical Properties of Electrodeposits
Authors: Weil Rolf
Published: April 2011

The strengths and ductility of electrochemically deposited metals generally are different from those of the corresponding ones produced by other means. The difference is due to the growth mechanism of the deposits, that they can contain substances which are unstable at elevated temperature and the presence of various crystal defects. The effects on the mechanical properties of electrodeposits of dislocations, twins, voids, codeposited foreign materials, surface crevices, subgrain and grain boundaries, internal stresses and textures are discussed. The ways polarization, current form, solution temperature and agitation affect the mechanical properties of deposits are reviewed. A discussion of the relationships between hardness, the tensile and the fatigue properties is also included. Annealing effects and those of special structures on the properties are also considered.
W/Si Schottky Diodes: Effect of Metal Deposition Conditions on the Barrier Height
Authors: Mamor M. , Finkman E. , Meyer F. , Bouziane K.
Published: April 2011

The Schottky barrier heights (ΦB) for W/Si Schottky diodes have been determined from I–V measurements. The effects of the sputter deposition conditions of the W-films were studied. X-ray diffraction was used to examine the structure and the lattice parameters of the W-films while the stress was determined by using a profilometer from the measurement of the curvature of the substrate after metallization. The resistivity is determined by using a four-point probe. A compressive-to-tensile stress transition is associated with the transformation of the ±—W-phase into the (β—W-phase as the working gas pressure is increased. These effects, which are frequently observed, coïncide with a significant increase of the W-film resistivity and a change (△ΦB≈50 meV) in the Schottky barrier height on n-type. On the other hand, the barrier height on the p-type remains constant under all the experimental conditions investigated. These results are discussed in terms of effects of strain and structure of W-films on the work function of the W, as well as in terms of modification of the pinning position of the Fermi level or else change in the value of the Richardson constant.
Stress and Density of Thin TiO2 Films Produced by Different Methods
Authors: Ottermann C. R. , Heming M. , Bange K.
Published: April 2011

Stress, density and refractive behavior are analyzed for TiO2 layers deposited by reactive evaporation (RE), ion plating (IP), plasma impulse chemical vapour deposition (PICVD) and spin coating (SP) from bending of the substrate and by means of Rutherford Backscattering Spectroscopy (RBS), respectively. Densities between 2.7 gem-3 and 3.8 gem-3 are obtained depending on coating techniques and coating conditions. Refractive index depends linear on density. A correlation between film stress and density is observed which is independent from coating process, production parameters and crystal structure of the as-deposited films. Stress is tensile at low densities and compressive for films with densities of the order of the crystal phase of anatase (3.84 gem-3). The phase transition from amorphous to anatase due to annealing induces an increase in stress. Film density determines the transition temperature, and the magnitude of stress increase.
Structure and Mechanical Properties of Nitrogen Incorporated Diamond-Like Carbon Films
Authors: Lee Kwang-Ryeol , Eun Kwang Yong , Rhee Jae-Seong
Published: April 2011

Nitrogen incorporated diamond-like carbon (DLC) films were deposited by r.f. plasma assisted chemical vapor deposition (r.f.-PACVD) method. Mixtures of benzene and ammonia or nitrogen were used as the reaction gases for the deposition. Composition, atomic bond structure and mechanical properties of the film were investigated when the fraction of nitrogen source increases from 0 to 0.79. All films were deposited at fixed negative bias voltage of the cathode (-500 V) and the deposition pressure (10 mTorr). While ammonia addition reduces both residual stress and hardness of the film from 1.7 to 1 GPa and from 2750 to 1700 Kgf/mm2 respectively, the mechanical properties are not significantly varied by nitrogen addition. Deposition rate, composition and atomic bond structure are also dependent on the nitrogen source gases. Observed behavior of mechanical properties is discussed in terms of the content of inter-links of sp2 clusters. In addition to hydrogen, C≡N bonds in the film are also terminated sites of three dimensional atomic bond network. By considering the hydrogen concentration and the C≡N bonds, it can be shown that the mechanical properties of nitrogen incorporated DLC films are determined by the content of inter-links of sp2 clusters.
Role of Dislocation Interactions in Decreasing Mobile Threading Dislocation Density and Limiting Strain Relaxation in Si1-xGex Heteroepitaxial Films
Authors: Gillard Veronique T , Nix William D
Published: April 2011

In situ substrate curvature measurements obtained during isothermal annealing of Si1-xGex films grown on (001) Si substrates allow determination of the evolution of strain versus time in these films. By coupling the strain relaxation measurements with previous measurements of dislocation velocities in this system, the mobile threading dislocation density and its evolution in the course of strain relaxation can be determined. The results indicate that in the late stage of strain relaxation, the mobile threading dislocation density decreases significantly. Results obtained with samples of two different sizes show that this decrease in mobile dislocation density is not primarily associated with dislocations running out at the edges of the film but with dislocation interactions impeding their further motion. Furthermore, for films thinner than 500 nm the residual strains after annealing are significantly higher than the values predicted by the equilibrium theory of misfit dislocations. The measured residual strains are compared with predictions based on Freund’s treatment of the blocking of a moving threading segment by an orthogonal misfit dislocation in its path. We find that the blocking criterion gives a very good account of the residual strain in Si1-xGex films and that blocking of threading dislocations by other misfit dislocations appears to play an important role in the late stage of strain relaxation.