bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Boron-Rich Metal Borides and Their Thermoelectric Properties
Authors: Takeda Masatoshi , Domingo Ferrer , Miura Takahiro , Fukuda Tadahiro 
Published: April 2011

ABSTRACTPolycrystalline metal borides AlMgB14, CaB6, and MB2 (M: transition metals) were synthesized and their thermoelectric properties were examined. Single phase of orthorhombic AlMgB14, which contains B12 icosahedral clusters as building blocks, was obtained at sintering temperatures between 1573 K and 1823 K. Seebeck coefficient (α) and electrical conductivity (σ) of the phase were about 500 (μV/K) and 10−1 (1/Ωm) at room temperature, respectively. These values are comparable to those of metal-doped β- rhombohedral boron. Synthesized AlB2-type diborides (MB2; M=Ti, V, Cr, and Mn) exhibited metallic conduction. The MB2's α varied with number of valence electrons, and showed a maximum α in VB2. The variation was similar to that predicted for pseudogap system. The CaB6 also possessed metallic conduction, but the α of the phase was as large as 200 (μV/K) with negative sign.
A Consistent Rationale for the Superior Strength and Ultra-Hardness of Ceramic Nano-Composite Coatings
Authors: Argon A. S. , Veprek S. 
Published: April 2011

AbstractNano-structured composite ceramic coatings such as TiN with Si3N4 orT iSi2 prepared by variousforms of plasma assisted CVD, composed of crystalline components of equiaxed TiN of several nm diameter, surrounded by amorphous Si3N4 intercrystalline layers of roughly 0.2 volume fraction have exhibited hardnesses in the range of 70-100 GPa-quite commensurate with polycrystalline diamond layers, and thermal stability up to 1000C. Preliminary considerations indicate that such ultra-hardness, uninfluenced by the usual artifacts of nano-indentations are not governed by processes of crystal plasticity in the crystalline component but by the characteristic flow mechanisms of the often topologically continuous amorphous component exhibiting “liquid-like” behavior in the constrained spaces between the crystalline components.
Preparation of TiFe thin Films by Pulsed Ion Beam Evaporation
Authors: Suematsu Hisayuki , Saikusa Tsuyoshi , Suzuki Tsuneo , Jiang Weihua , Yatsui Kiyoshi 
Published: April 2011

AbstractThin films of titanium iron (TiFe) were prepared by a pulsed ion-beam evaporation (IBE) method. A pulsed ion beam of proton accelerated at 1 MV (peak) with a pulse width of 50 ns and a current of 70 kA was focused on TiFe alloy targets. Soda lime glass substrates were placed in front of the targets. Phases in the thin films were identified by X-ray diffraction (XRD). XRD results revealed that the thin films deposited on the glass substrates consist of a TiFe phase. Crystallized Ti-Fe thin films without oxides were successfully obtained. Surface roughness of the thin film was 0.16 m m.
Microstructure and Tribological Behavior of Cr-DLC Nanocomposite Films
Authors: Singh V. , Jiang J.C. , Meletis E.I. 
Published: April 2011

AbstractCr-diamondlike carbon (Cr-DLC) nanocomposite films with the Cr content varying up to 27 at. % were synthesized by reactive magnetron sputtering. Their microstructure and tribological properties were studied using transmission electron microscopy (TEM) and pin-on-disc experiments, respectively. Electron diffraction and high- resolution TEM studies show that the films, with ∼ 9 at. % Cr, deposited using low (−200 V) and high (−1000 V) specimen bias during processing are composed of nanocrystalline metallic Cr and face-centered cubic chromium carbide, respectively surrounded by an amorphous matrix. The Cr-DLC film deposited at high bias exhibited enhanced adhesion to Si substrate and wear resistance compared to those deposited at low bias with the same Cr content. Wear rate of the films deposited at high bias is relatively independent of Cr content up to about 10 at. % (of the order of 10−7 mm3/N-m) and then increases with increasing Cr content. The coefficient of friction for the films with a Cr content less than 19 at. % is low and remains between 0.1-0.16.
Characteristics of Cr-Al-N-O Thin Films Prepared by Pulsed Laser Deposition
Authors: Hirai Makoto , Saito Hajime , Suzuki Tsuneo , Suematsu Hisayuki , Jiang Weihua , Yatsui Kiyoshi 
Published: April 2011

AbstractChromium aluminum oxynitride (Cr-Al-N-O) thin films have been successfully prepared by pulsed laser deposition (PLD). Experiments were carried out by changing surface area ratio of the targets (SR = SAlN / (S +SAlN)) from 0 to 100 %. The composition of the thin film prepared at SR = 75 % was determined to be Cr0.11Al0.39N0.25O0.25 by Rutherford backscattering spectroscopy (RBS). The hardness of the Cr-Al-N-O thin film was found to be above HV 4000 when the aluminum content in cations (x) was 25 at. %. The high hardness can be explained by solid solution hardening and/or increasing bulk modulus. The oxidation of the Cr-Al-N-O thin film occurred above 900°C. From the result of grazing angle X-ray diffractometry (GXRD), the oxidation resistance of the Cr-Al-N-O thin film was found to be improved due to the fact that Cr2O3 and -Al2O3 grains are formed at the outermost surface of the thin film.
Mechanical and Electrical Properties of Nanocrystalline and Epitaxial TiN Films
Authors: Wang H. , Kvit A. , Zhang X. , Koch C. C. 
Published: April 2011

AbstractHigh-temperature materials such as TiN have been successfully applied as wear corrosion protection, decorative coatings, electrical contacts and diffusion barriers in electronic devices. However the poor toughness and ductility have limited some of these applications. To alleviate some of these problems, reduction of grain size can enhance grain boundary sliding and grain boundary diffusion related creep phenomena. We have investigated mechanical and electrical properties of TiN as a function of microstructure varying from nanocrystalline to single crystal TiN films deposited on (100) silicon substrates. By varying the substrate temperature from 25oC to 700oC during pulsed laser deposition, the microstructure of TiN films changed from nanocrystalline (having uniform grain size of 8 nm) to a single crystal epitaxial film on the silicon (100) substrate. The microstructure and epitaxial nature of these films were investigated using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Hardness measurements were made using nanoindentation techniques. Resistivity measurements were performed by van der Pauw method. The nanocrystalline TiN contained numerous triple junctions without any presence of amorphous regions. The width of the grain boundary remained constant 1 nm as a function of boundary angle. Similarly the grain boundary structure did not change with grain size. The hardness of TiN films decreased with decreasing grain size in nanoscale. This behavior has been modeled recently involving grain boundary sliding which is particularly relevant in the case of hard materials such as TiN. The dependence of resistivity of TiN as a function of the substrate temperature is discussed and correlated with hardness results.
The Development of Surface Roughness and Implications for Cellular Attachment in Biomedical Applications
Authors: Banks Bruce , Miller Sharon , Groh Kim de , Chan Amy , Sahota Mandeep 
Published: April 2011

AbstractThe application of a microscopic surface texture produced by ion beam sputter texturing to the surfaces of polymer implants has been shown to result in significant increases in cellular attachment compared to smooth surface implants in animal studies. A collaborative program between NASA Glenn Research Center and the Cleveland Clinic Foundation has been established to evaluate the potential for improving osteoblast attachment to surfaces that have been microscopically roughened by atomic oxygen texturing. The range of surface textures that is feasible depends upon both the texturing process and the duration of treatment. To determine whether surface texture saturates or continues to increase with treatment duration, an effort was conducted to examine the development of surface textures produced by various physical and chemical erosion processes. Both experimental tests and computational modeling were performed to explore the growth of surface texture with treatment time. Surface texturing by means of abrasive grit blasting of glass, stainless steel and polymethylmethacrylate surfaces was examined to measure the growth in roughness with grit blasting duration by surface profilometry measurements. Laboratory tests and computational modeling was also conducted to examine the development of texture on Aclar® (chlorotrifluoroethylene) and Kapton® polyimide, respectively. For the atomic oxygen texturing tests of Aclar®, atomic force microscopy was used to measure the development of texture with atomic oxygen fluence. The results of all the testing and computational modeling support the premise that development of surface roughness obeys Poisson statistics. The results indicate that surface roughness does not saturate but increases as the square root of the treatment time.
Formation of Al Nanodot Array by the Combination of Nano-Indentation and Anodic Oxidation
Authors: Shingubara S. , Murakami Y. , Morimoto K. , Sakaue H. , Takahagi T. 
Published: April 2011

AbstractThe control of nanoholes formed by anodic oxidation of aluminum (Al) was investigated using AFM nano-indentation on Al film prior to the anodic oxidation. It is well known that ordered trigonal nanohole arrays are formed under certain voltage conditions of anodic oxidation of Al. We succeeded in forming both tetragonal and trigonal arrays of alumina nanoholes on a SiO2/Si- substrate by using nano-indentation on the surface of sputtered pure Al film. The ordered array of nanoholes was obtained at indentation intervals that were close to the nearest neighbor distance of nanoholes in the self-organization condition. Furthermore, we fabricated tetragonal and hexagonal Al nanodot arrays by the selective removal of porous alumina film.
Micro- and Nanofabricating Lipid Patterns Using a Polymer-Based Wet Lift-Off
Authors: Orth Reid. N. , Hafez Ismail , Wu Min , Ilic Bojan , Baird Barbara , Clark Theodore G. , Craighead Harold G. 
Published: April 2011

AbstractAccurate placement of biomaterials at nanoscale resolution opens new capabilities for biological sensing, cell manipulation, and control of cellular transduction cascades. We demonstrate that lipid molecules can be patterned on silicon using a polymer lift-off technique. Patterned lipid bilayers serve as biomaterial patterning platforms useful for studies of cellular function. Submicron feature sizes were achieved using this templating technique which is suitable for delicate biomaterials1. Projection lithography and reactive ion etching were used to pattern a Parylene-coated surface. The patterned surface was subsequently exposed to 100 nm unilamellar lipid vesicles that bound to the native oxide surfaces of silicon and spread to form supported lipid bilayers. The nanoscale pattern is realized as the polymer is peeled away in deionized water. The versatility of this method is demonstrated by the successful preparation of functionalized lipid bilayer surfaces. Specific intermolecular interactions were demonstrated between supported membranes: DPPE-PE (2000) biotin/avidin, dinitrophenol (DNP)-conjugated lipids/anti-DNP IgE, and cationic lipid and M13 dsDNA:YOYO-1.
Patterning 2D Metallic Surfaces by Soft Lithography
Authors: Toprak M. , Kim D. K. , Mikhailova M. , Muhammed M. 
Published: April 2011

AbstractIn this study, we report on the development of a μCP technique, where the ink used on the surface of the stamp is made of aminopropyl trimethoxy silane (APTMS). The stamps for the μCP are prepared by polymerizing polydimethylsiloxane (PDMS) on photolithographically defined masters. Si wafers were used as the substrate on which a self assembled layer of APTMS was formed at the contact regions of the stamp. The regions of contact were subsequently used for the deposition of gold coated magnetite nanoparticles, resulting in 2D patterned metallic surfaces. The colloidal particles were analyzed by TEM and XRD, and the printed substrates were characterized by AFM.
Synthesis of Polyaniline Using Electrostatically Layered Hematin Assemblies
Authors: Ku Bon-Cheol , Lee Soo-Hyoung , Liu Wei , Kumar Jayant , Bruno Ferdinando F. , Samuelson Lynne A. 
Published: April 2011

ABSTRACTThe enzyme horseradish peroxidase has been recently used for the polymerization of water-soluble conductive polyaniline. Hematin, an ironporphyrin molecule that catalyzes the oxidative polymerization of aniline and phenol, is a robust and inexpensive biomimetic alternative to horseradish peroxidase. Composite thin film assemblies were fabricated by electrostatic layer-by-layer (ELBL) alternate deposition of a polyelectrolyte, poly(dimethyl diallylammonium chloride), and hematin. These multilayer assemblies were then used for the polymerization of aniline in the presence of a polystyrene sulfonate as a template. It was found that the polymerization rate depends on both pH and the concentration of hematin deposited and the polyaniline synthesis was possible both onto the ELBL surfaces and in solution. It was also discovered that it is possible to reuse the ELBL assembled hematin substrates for multiple aniline polymerizations.
Improved Thin Film Transistor (TFT) performance using fractionated Poly-3-hexylthiophene (P3HT)
Authors: Raja Munira , Lloyd Giles , Sedghi Naser , Lucrezia Rafaella di , Higgins Simon J. , Eccleston W. 
Published: April 2011

ABSTRACTBy using the Trznadel method, it has been possible to increase molecular weight, the regio-regularity, and probably to decrease the residual catalyst of poly-3-hexylthiophene thin films. The drift mobility of holes, normal to the surface of cast films, in air, has been found using Schottky diodes, and field-effect mobility has been measured with Thin-Film Transistors. Three types of film have been studied using the two methods of assessing mobility. The as-synthesised films are compared with those that have been fractionated. The third set of films involves doping with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The doped films show a field effect mobility of 0.2 cm2V-1s-1: all others being lower. Field effect mobility is approximately two orders of magnitude greater than that in the bulk normal to the plane of the film. Doping levels in the films are found to be similar, probably because of the process conditions.
Simulation of chirally-induced excitonic optical effects in biscyanine dye with shiff base (optical and molecular structure simulations)
Authors: Andraud C. , Plucinski K.J. , Kityk I.V. 
Published: April 2011

ABSTRACTFor the first time simulations of chirally-induced excitons have been carried out, using molecular dynamic simulations and self-consistent quantum chemical calculations within the RHF [Restricted Hartree-Fock ] and DFT [Density Functional Theory] approaches. We found that the DFT approach gave substantially better agreement than the RHF. Comparison of theoretical and experimental results for biscyanine dye with a Shiff base showed a sufficiently good level of agreement.
Chemical modification of indium-tin-oxide electrodes by surface molecular design
Authors: Ganzorig Chimed , Fujihira Masamichi 
Published: April 2011

ABSTRACTIndium-tin-oxide (ITO) is the most widely used material as a transparent electrode due to its excellent transparency and high conductivity. The devices based on bare ITO, however, exhibited inefficient hole injection due to insufficient high work function and required high drive voltages. Thus, various surface treatments of ITO have been attempted to change the work function of ITO in order to reduce the hole injection barrier height. Electroluminescent (EL) characteristics of devices were improved dramatically using ITO chemically modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By the use of reactive -COCl groups, ITO surfaces were modified quickly and the work function of the modified ITO was changed widely depending upon the permanent dipole moments introduced in p-position of benzoyl chloride. We also compared the performance of the EL devices with ITO modified with different binding groups (-SO2Cl, -COCl, and -PO2Cl2) of p-chlorobenzene derivatives. Finally, we examined the correlation between the change in the work function and the performance of the EL devices by the chemical modification and found that the enormous increase in ITO work function up to 0.9 eV is possible using phenylphosphoryl dichloride with a CF3-terminal group in p-position.
Photoelectric Response from Nanofibous Membranes
Authors: Senecal Kris J. , Ziegler David P. , He Jinan , Mosurkal Ravi , Schreuder-Gibson Heidi , Samuelson Lynne A. 
Published: April 2011

ABSTRACTElectrospinning has been used to prepare nanofibrous composite membranes of semi-conducting particles (TiO2) and photovoltaic dyes. Electrospinning is a relatively simple technique where electrical forces are used on polymeric solutions to produce nanoscale fibers. The resulting nanofibrous membranes have surface areas that are roughly one to two orders of magnitude higher than conventional thin films. It is believed that this higher surface will allow for more efficient light harvesting in photovoltaic devices. Our research has focused on the fabrication of organic/inorganic hybrid solar cells featuring dye sensitized nanocrystalline semiconductor particles using electrospinning. Phthalocyanine and N3 (cisdi(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate) ruthenium(II)) photoactive dyes were electrospun with semi-conductive TiO2 nanoparticles into a matrix polymer, polyacrylonitrile (PAN). Electron microscopy and elemental analysis of the electrospun membranes shows that each component is present and uniformly dispersed in the nanofibrous membranes. In general, the dye membranes electrospun with the TiO2 nanoparticles exhibited a greater photoelectric response than the membranes with dye only. The N3 dye membranes however showed the greatest photoresponse in comparison to the phthalocyanine dyes, with or without the TiO2 nanoparticles. Photoelectric responses on the order of 30 μA and 280 mV were achieved with dye-sensitized membranes and are believed to be the first demonstration of a photoelectric response from an electrospun nanofibrous membrane.
Integrated Analysis for Long-Term Degradation of Waste Package at the Potential Yucca Mountain Repository for High-Level Nuclear Waste Disposal
Authors: Lee Joon H. , Mon Kevin G. , Longsine Dennis E. , Bullard Bryan E. , Moniba Ahmed M. 
Published: April 2011

ABSTRACTThe technical basis for Site Recommendation (SR) of the potential repository for high-level nuclear waste at Yucca Mountain, Nevada has been completed. Long-term containment of the waste and subsequent slow release of radionuclides from the engineered barrier system (EBS) into the geosphere will rely on a robust waste package (WP) design, among other EBS components as well as the natural barrier system. The WP and drip shield (DS) degradation analyses for the total system performance assessment (TSPA) baseline model for the SR have shown that, based on the current corrosion models and assumptions, both the DSs and WPs do not fail within the regulatory compliance time period (10,000 years). From the perspective of initial WP failure time, the analysis results are encouraging because the upper bounds of the baseline case are likely to represent the worst case combination of key corrosion model parameters that significantly affect long-term performance of WPs in the potential repository. The estimated long life-time of the WPs in the current analysis is attributed mostly to the following two factors that delay the onset of stress corrosion cracking (SCC): (1) the stress mitigation to substantial depths from the outer surface in the dual closure-lid weld regions; and (2) the very low general-corrosion rate applied to the closure-lid weld regions to corrode the compressive stress zones. Uncertainties are associated with the current WP SCC analysis. These are stress mitigation on the closure-lid welds, characterization of manufacturing flaws applied to SCC, and general corrosion rate applied to the closurelid weld regions. These uncertainties are expected to be reduced as additional data and analyses are developed.
Thermodynamic Functions of Zirconolite and their Uses in Computer Simulation
Authors: Bergman George A. , Navrotsky Alexandra , Ojovan Michael I. , Klimov Vsevolod L. , Karlina Olga K. , Pavlova Galina Yu. 
Published: April 2011

ABSTRACTThe enthalpy of melting and the heat capacity of liquid zirconolite (CaZrTi2O7) are estimated as equal to 200 ± 20 kJ·dmol−1 and 350 ± 50 J·mol−1·K−1, respectively. Thermodynamic functions of solid and liquid zirconolite are calculated based on these estimated data and the results of Navrotsky et al. On the basis of these thermodynamic functions, computational thermodynamic simulation is performed on the thermochemical synthesis of zirconolite-bearing materials. Demonstration indicates that synthesis of zirconolite-like matrix materials is possible using the self-sustaining exothermic reaction.
Preliminary Studies of the Disposition of Cesium in a Glass-Bonded Sodalite Waste form
Authors: Lambregts Marsha J. , Frank Steven M. 
Published: April 2011

ABSTRACTArgonne National Laboratory has developed an electrometallurgical treatment for DOE spent metallic nuclear fuel. Fission products are immobilized in a durable glass bonded sodalite ceramic waste form (CWF) suitable for long term storage in a geological repository. Cesium is estimated to be in the waste form at approximately 0.1 wt.%. The exact disposition of cesium was uncertain and it was believed to be uniformly distributed throughout the waste form. A correlation of X-ray diffractometry (XRD), electron microscopy (EM), and nuclear magnetic resonance spectroscopy (NMR) performed on surrogate ceramic waste forms with high cesium loadings found a high cesium content in the glass phase and in several non-sodalite aluminosilicate phases. Cesium was not detected in the sodalite phase.
Accommodation of Uranium into the Garnet Structure
Authors: Yudintsev Sergey V. , Lapina Marya I. , Ptashkin Alexander G. , Ioudintseva Tatiana S. , Utsunomiya Satoshi , Wang Lumin M. , Ewing Rodney C. 
Published: April 2011

ABSTRACTOne promising host for actinide wastes is garnet-type phases of general formula AVIII3BVI 2[XO4]3. To determine the isomorphic capacity of garnet for uranium, the CaO – Fe2O3 – Al2O3 – SiO2 – ZrO2 – Gd2O3 – UO2 system was studied. Experiments were performed in air medium at 1400 – 1500 °C and 1 atm. The garnets have high capacity for Gd and Zr, while incorporation of U was found to be greatly dependent on the phase composition. Uranium content decreased from 18 wt.% in Ca-Zr-Fe garnet to 0.6 wt.% in Si-doped phases. Heavy ion irradiation (1.0 MeV Kr++) experiments were carried out for a garnet with maximal U content, (Ca2.7U0.3)VIII(Zr1.7Fe0.3)VI(Al1.1Fe1.9)IVO12. Amorphization dose of the phase was equal to 1.63×1014 ions/cm2 that is close to the other actinide hosts, such as pyrochlore Gd2Ti2O7.