bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bonding of Cu wires by solid state sintering of Ag nanoparticles at low temperatures
Authors: Alarifi Hani , Hu Anming , Yavuz Mustafa , Zhou Y. 
Published: January 2010

AbstractSolid state sintering of Ag nanoparticles was used to bond Cu wires to Cu foils at temperatures less than 250°C. The Ag nanoparticles are coated with an organic shell to prevent sintering at room temperature. After annealing the nanoparticles at 200°C, the decomposition of the organic shell was confirmed using TGA and Raman spectroscopy. The joint strength was measured by tensile shear tests, which shows that the joint strength increases as the bonding temperature increases. Metallic bond between Ag nanoparticles and Cu was achieved with no contamination. Bonds formed by our method, was confirmed to withstand temperatures higher than the bonding temperatures.
Synthesis of Organic Capped Colloidal Zinc Oxide Quantum Dots and Their UV Dominant Emission Property
Authors: Omata Takahisa , Takahashi Kazuyuki , Hashimoto Shinichi , Maeda Yasuhiro , Nose Katsuhiro , Otsuka-Yao-Matsuo Shinya 
Published: January 2010

AbstractA novel synthesis route to organic-capped and colloidal ZnO quantum dots (QDs) has been developed. Specifically, zinc-di-butoxide was hydrolyzed with very dilute water (100˜600 mass ppm) dissolved in hydrophilic benzylamine and polymerized to ZnO by dehydration condensation. After formation of ZnO QDs with 2˜3 nm in diameter, growth of the QDs and exchange the surface capping ligand from hydroxyl groups and/or benzylamine to oleylamine were developed by heating the colloidal solution with oleylamine. The size of the ZnO QDs finally obtained was in the range 3˜5 nm in diameter. The QDs show high dispersibility in various organic solvents. Clear UV emission due to exciton recombination was observed; and its energy was varied according to the quantum size effect from 3.39 to 3.54 eV. By using lithium-free zinc-di-butoxide as a starting material, the defect-related VIS emission was successfully decreased and the UV emission becomes dominant. The influence of water concentration in benzylamine and oleylamine on UV emission intensity was also investigated.
Charge Storage and Optical Response of Hybrid Nanodots Floating Gate For Functional Memories
Authors: Miyazaki Seiichi , Morisama Naoya , Nakanishi Sho , Ikeda Mitsuhisa , Makihara Katsunori 
Published: January 2010

AbstractWe have proposed and fabricated a hybrid nanodots floating gate (FG), in which Si quantum dots (QDs) as charge injection/emission nodes and NiSi nanodots as charge storage nodes are stacked with an ultrathin SiO2 interlayer, to satisfy both large memory window and multivalued capability. In this study, Si-QDs with an areal density of ˜3×1011cm-2 were formed on ultrathin SiO2 layer by controlling SiH4 chemical vapor deposition (CVD) and NiSi nanodots were prepared by full-silicidation of Si-QDs promoted with remote H2-plasma exposure after Ni evaporation. From capacitance-voltage(C-V) characteristics of MOS capacitors with a NiSi nanodots/Si-QDs hybrid FG, stable storage of many charges in the deep potential well of each NiSi nanodot was confirmed. Also, by applying pulsed gate biases, stepwise charge injection to and emission from NiSi nanodots through discrete energy states in Si-QDs were demonstrated. In addition, by 1310nm (˜0.95eV) light irradiation, a distinct optical response in C-V characteristics was detected, which can be interpreted in terms of the shift of charge centroid in the hybrid FG stack due to transfer of photoexcited electrons from NiSi-nanodots to the Si-QDs.
Metal oxide rods and dots-based structures and devices: cost-effective fabrication and surface chemistry control
Authors: Vayssieres Lionel 
Published: January 2010

AbstractThe necessity of materials development which is not limited to materials that can achieve their theoretical limits, but makes it possible to raise theoretical limits by changing the fundamental underlying physics and chemistry while keep the fabrication cost to a minimum is crucial. Materials nanotechnologies based on chemical fabrication approaches is one of the immediate answer to the enormous need for cost-effective new materials for energy, environment, and health. R&D exploiting chemical nanoscience and nanotechnology has the greatest potential to efficiently contribute to such challenging goals. Indeed, the creation of new materials with higher performance and improved stability achieved by atomic, molecular and nanostructural design and control using unique nanoscale phenomena such as quantum confinements is the key. A synthesis involving the aqueous condensation of metal ions from solutions of metal salts for the low-cost fabrication of engineered arrays consisting of oriented nanorods of metal oxides orientations onto various substrates as well as the ability to control the surface acidity of quantum dots from acidic to neutral to basic by size effect are presented.
Porous ultrathin silicon membranes for purification of nanoscale materials
Authors: Striemer Christopher C , Gaborski Thomas R , Fang David Z , Snyder Jessica L , McGrath James L , Fauchet Philippe M 
Published: January 2010

AbstractA new class of porous membrane has been fabricated that is unique in its combination of nanoscale thickness (<50 nm) with macroscopic, yet robust, millimeter-scale lateral dimensions and tunable pore size in the range of ˜5nm to ˜100nm. The membrane material is porous nanocrystalline Si (pnc-Si)1, and is being scaled-up to commercial volumes by a startup company, SiMPore, Inc. Standard commercial separation membranes with pores in this size regime are polymeric materials (poly ether sulphone, cellulose, etc.), microns in thickness, leading to pore morphologies that resemble long narrow tubes or tortuous-path 3-D matrices. As pnc-Si membrane thickness approaches the pore diameters, a simplified structure of holes in a thin sheet results, greatly enhancing both diffusive and forced flow transport through the membrane, as predicted by classical transport theories2. Pnc-Si has confirmed these theoretical predictions, demonstrating record-breaking transport rates, in addition to precise size-separation of nanoparticles, viruses, proteins, and nucleic acids.
Applications for this highly precise silicon-based membrane range from highly efficient separations and purification of biomolecules, complexes, and nanoparticles, to substrates for microscopy to cell culture and co-culture. SiMPore is focused on navigating this application space with the goal of quickly introducing products that will allow the company to become self-sustaining and profitable though direct sales or partnerships with market leaders. Key product development drivers include potential competitive performance advantages and perceived value to a particular market, the IP landscape, development costs of the membrane and the device package/interface, and alignment with existing in-house capabilities.
Large Scale Nanomaterial Production Using Microfluidizer High Shear Processing
Authors: Chomistek Kenneth John , Panagiotou Thomai 
Published: January 2010

AbstractLarge Scale Nanomaterial Production Using Microfluidizer High Shear Processing
Kenneth. J. Chomistek and Thomai Panagiotou, Ph.D.
Microfluidics Corporation, 30 Ossipee Rd., Newton, MA 02464, USA
Microfluidics has developed scalable and low cost award winning technologies, capable of producing nanomaterials with desirable properties for a wide variety of applications. The industries served are pharmaceuticals and biotech, energy, specialty chemicals, cosmetics and nutraceuticals. Microfluidics approach is based on an in-depth understanding of applications, unique design of high shear fluid processors, and development of processes tailored for each individual application.
The understanding of the requirements and ecosystem of specific applications includes the desired end properties of the material, the production environment requirements, time and cost restrictions. Pharmaceutical and biotech applications include the development and the production of FDA approved nanotechnology drugs such as vaccines, cancer drugs, anesthetics, controlled delivery systems that include polymers drugs and proteins, etc. Chemical applications include inkjet inks, fuel cell and battery electrodes, and carbon nanotube dispersion. Cosmetics include nanoencapsulation of oxygen carriers and nutrients, and collagen processing. Nutraceuticals include nanoencapsulation of fish oil for protection of omega-3 fatty acids and odor control, nanoemulsions that contain plant sterols and vitamins.
Two main methods are used for production of nanomaterials: (a) the “top down”, particle size reduction method, and (b) the “bottom up”, Microfluidics reaction Technology (MRT) for production of nanoparticles through chemical reactions and physical processes, such as crystallization. This technology received the Nano50 Award in 2007. Both technologies are continuous and can be used in line with upstream or downstream processes such as premixing, filtration, etc., and are consistent with process intensification principals.
The heart of the technology is the interaction chamber which consists of “fixed geometry” microchannels. Flow through the chamber is characterized by high fluid velocities (up to 500 m/s) and subsequent impingement of fluid jets to the chamber walls or to one another. The unique “fixed geometry” feature combined with the high shear rates ensure that varied formulations (emulsions, liposomes and dispersions) achieve the smallest particle size and the narrowest particle size distribution when compared to other particle reduction techniques.
The technology is fully scalable and has been used extensively from lab scale to production of market drugs, nutraceuticals and inks, among others. Microfluidizer® processors offer a variety of options, such as steam sterility, cleanability and data acquisition capabilities, so they are cGMP compliant, CE certified, ATEX and explosion proof, and therefore are suitable for a variety of manufacturing environments.
Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness
Authors: Sanghavi Rahul Pankaj , Nandasiri Manjula , Kuchibhatla Satyanarayana , Nachimuthu Ponnusamy , Engelhard Mark H. , Shutthanandan Vaithiyalingam , Jiang Weilin , Thevuthasan Suntharampillai , Kayani Asghar , Prasad Shalini 
Published: January 2010

AbstractThe current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 0.001 Torr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed.
A Novel Polymeric Approach by Utilizing Functionalized Poly(ether ether ketone) for Hydrogen Storage Applications
Authors: Pedicini Rolando , Squadrito Gaetano , Giacoppo Giosuè , Saccà Ada , Passalacqua Enza 
Published: January 2010

AbstractHydrogen is a reliable energy vector and its storage is strongly connected to the costs, performance and level of safety of the storage system components. Several materials for physical and chemical hydrogen storage have been proposed, but few research works were devoted to polymers, that generally are low cost and weight materials, easy to be managed and manufactured. In this work, a functionalised Poly(ether ether ketone) (PEEK) polymer was studied and chosen as a base polymeric matrix with the aim to produce both a low cost and low weight hydrogen storage material. The polymer was in situ functionalised starting from a manganese oxide precursor. The obtained oxide, bonded to the polymer chain, allows the hydrogen storage. In this work, the functionalisation process and preliminary results of the hydrogen storage capability are reported.From Scanning Electron Microscopy (SEM) and surface area measurements (BET), it has been verified that the metallic compound introduction modifies the morphology of the material, supplies an increased surface area for hydrogen chemisorption, revealing a 1.2%wt/wt hydrogen adsorption capability at 77 K. Preliminary results by Gravimetric Hydrogen Absorption measurements show that by increasing the temperature, the hydrogen storage capability is reduced and a value of 0.3%wt/wt at 50°C and 80 absolute bar was obtained. The reversibility cycles of hydrogen adsorption-desorption seem to be confirmed. For this reason such approach has been considered as a promising pathway and deeper studies are in progress.
On-site sodium metal production with electrolysis by offshore wind or solar cell power generation for hydrogen generation
Authors: Murahara Masataka , Seki Kazuichi , Sato Yuji , Fujiwara Etsuo 
Published: January 2010

AbstractSodium metal reacts with water explosively to generate hydrogen. Therefore, sodium metal can have an important role as a hydrogen storage material. Seawater contains water most and sodium second. Seawater is electrolyzed by offshore wind or solar cell power generation to produce sodium; which is transported to a thermoelectric power plant on land and then is reacted with water to produce hydrogen for electric power generation. Sodium hydroxide, a by-product, is used as a raw material for soda industries. In the sodium production process, many by-products such as fresh water, magnesium, sodium hydroxide, hydrochloric acid, and sulfuric acid are produced. Thus, sodium metal is an economical, renewable, and sustainable fuel that discharges neither CO2 nor radioactivity.
Phase Formation and Hydrogen Ordering in Yttrium-Hydrogen System
Authors: Wang Ke , Hattrick-Simpers Jason , Bendersky Leonid 
Published: January 2010

AbstractPhase transformations in epitaxial yttrium films grown on (0001)Ti//(0001)Al2O3 Ti-buffered sapphire substrates and hydrogenated for 10 min were characterized using transmission electron microscopy. After hydrogen charging, dense twin lamellae form during α(Y(H))-to-β(YH2) phase transition with twin boundaries predominately parallel to the interface between Y and a substrate. High densities of Shockley partial dislocations are present at the twin boundaries, their glides during phase transformation are responsible for the formation of twin lamellae. Electron diffraction from YH2 phase shows superlattice reflections, which suggests a new type of ordering on octahedral interstitial sites.
Novel Ultrathin Mg Nanoblades for Hydrogen Storage
Authors: Tang Fu , Wang Gwo Ching , Lu Toh-Ming 
Published: January 2010

AbstractWe describe the growth of novel ultrathin Mg crystalline nanoblades by oblique angle vapor deposition. These nanoblades were then coated with catalyst Pd and hydrogenated into magnesium hydride MgH2. In situ thermal desorption spectroscopy study showed a low H desorption temperature at ∼365 K. In situ reflection high energy electron diffraction patterns were used to study the temperature dependent structure and composition changes during the de-hydrogenation of Pd coated MgH2 nanoblades. The diffraction rings reveal the formation of alloys of Pd and Mg when the temperature is over ∼480 K. Transmission electron microscopy diffraction also supports the formation of Pd and Mg alloys. This alloying reduces the cycling capability of Mg hydride. The de-hydrogenation of MgH2 introduces a strain at the bilayer interface between MgH2 and Mg resultant from 30% volume reduction from MgH2 to Mg and formed curved nanoblades as evident by scanning electron microscopy images. Designing factors of recyclable simple hydrides will be discussed.
Molecular Vibrations as the Origin of Solid State Effects in Borohydrides
Authors: Borgschulte Andreas , Gremaud Robin , Buchter Florian , Lodziana Zbigniew , Züttel Andreas , Ramirez-Cuesta Timmy , Bardaji Miriam , Lohstroh Wiebke , Fichtner Max 
Published: January 2010

AbstractIn this proceeding, we discuss measurements of the vibrational properties of hydrides using inelastic neutron scattering (INS) and the impact of the vibrational modes on the thermodynamic properties. We compare the heat capacity of PdH0.63 and LiBH4 as measured calorimetrically to that derived form INS spectra. We show that the vibrational properties of Ca(BH4)2 depend on the specific phase and hitherto determine their stability.
Development of Combined Optical Cell and Sieverts-type Apparatus for in-situ Measurement of Hydrogen Storage Materials
Authors: Chiu Chun , Hattrick-Simpers Jason , Heilweil Edwin , Bendersky Leonid 
Published: January 2010

AbstractA parallel high-sensitivity hydrogen sorption, and in situ Raman/IR emissivity measurement system has been developed using a stainless-steel sample cell with a sapphire window to act as a bridge between the PCT and optical measurements. The cell can be pressurized up to 4.5 MPa and heated up to 723 K. The system can measure small changes in hydrogen content, down to 0.5 μg, allowing for characterization of small quantities of powers and thin films. Hydrogen desorption in LiNH2 - LiBH4 - MgH2 nanocomposites has been studied by in-situ Raman and PCT measurement, while that of MgH2 powers and thin films has been studied by in-situ PCT and IR emissivity. In powder samples, qualitative trend is observed between changes in the Raman peak intensity/IR emissivity and the amount of hydrogen absorbed or desorbed.
Structure and Stability of Hydrogen Clathrates of Ammonia Borane
Authors: Abramov Alexander , Gutowski Maciej 
Published: January 2010

AbstractStructural rules have been formulated for the molecular crystal of ammonia borane (AB, NH3BH3) and clathrates thereof. These rules are similar to the “ice rules” in water. Periodic structures of possible clathrates of AB have been predicted. A rigorous analysis of the uniform space filling tessellations of 3D space has been performed resulting in the identification of two promising structures for AB clathrates. Additional five structures have been identified exploiting features and properties of AB molecules. The screening, or evaluation, of proposed periodic structures has been performed on the basis of their stability determined at the density functional level of theory. Hydrogen capacity of the most stable periodic structure (cantitruncated cubic honeycomb) is estimated to be 21 wt%, 19% chemically bound in AB and 2 wt% of H2 physisorbed in the cages of AB.
Towards the Rational Design of Supported-Bimetallic Nanoparticle Catalysts
Authors: Dash Priyabrat , Scott Robert W. J. 
Published: January 2010

AbstractHeterogeneous catalysts consisting of nanoparticles dispersed on an oxide support are a mainstay in industrial reactions, and are often made via thermal reduction of metal salts dispersed onto a pre-synthesized support. Herein we document a route towards the design of xerogel-supported nanoparticle catalysts by trapping compositionally-tuned polymer-stabilized nanoparticle precursors into sol-gel matrices. Such a route allows in principle for the tuning of the size, composition, architecture, and electronic properties of nanoparticle catalysts, which allows for the development of highly efficient and selective catalysts. As proof of concept we detail the synthesis of co-reduced PdAu nanoparticles in titania supports. The final materials are well-characterized by HRTEM and energy dispersive spectroscopy (EDS), which confirm the compositional uniformity of the nanoparticles. The importance of controlling calcination conditions in order to retain designed nanoparticle compositions is stressed; high temperature calcination conditions lead to a large degree of sintering and loss of compositional uniformity, while mild calcination temperatures can be used to retain nanoparticle compositions and sizes.
CO Oxidation Catalyzed by Pd-doped BaCeO3: Coexistence of Langmuir-Hinshelwood and BaCeO3-mediated Mechanisms
Authors: Ouyang Xiaoying , Scott Susannah 
Published: January 2010

AbstractThe rate law for CO oxidation over Pd-substituted BaCeO3 was studied. Under CO-rich conditions over a range of pressures and temperatures, changing reaction orders for both CO and O2 suggest the coexistence of both Langmuir-Hinshelwood and BaCeO3-mediated mechanisms. The latter dominates at high P(CO)/P(O2), while both mechanisms contribute significantly at low P(CO)/P(O2). Under CO-lean conditions, the Langmuir-Hinshelwood mechanism dominates the kinetics. The importance of the BaCeO3-mediated mechanism increases with temperature. Steady-state isotopic transient kinetic analysis (SSITKA) using 18O2 confirmed the participation of labile lattice oxygen, thus BaCeO3 behaves as a BaO-stabilized form of CeO2.
Steam Reforming of Methane on Ru and Pt Promoted Nanocomposites for SOFC Anodes
Authors: Mezentseva Natalia , Alikina Galina , Bunina Rimma , Pelipenko Vladimir , Ischenko Arcady , Smirnova Alevtina , Smorygo Oleg , Sadykov Vladislav A 
Published: January 2010

AbstractNanocomposite cermet materials comprised of NiO/YSZ (20-90 wt. %) co-promoted with SmPrCeZrO or LaPrMnCrO complex oxides and Pt, Pd or Ru were synthesized by Pechini method. These materials were characterized by BET, TEM with EDX, and CH4 TPR. The catalytic properties were studied for the steam reforming (SR) of CH4 at short contact times. Factors controlling performance of these composites in CH4 SR (Ni content, interaction between components in composites as dependent upon their chemical composition) were determined. Ru-promoted composite supported on Ni-Al foam demonstrated a high (up to 75%) methane conversion at 650° in the feed containing 20% CH4 and 40% H2O in Ar
Theoretical Analysis of the CO Oxidation Process on Neutral and Single Ionized Au18 Clusters
Authors: Castro Jorge , Soto Jorge , Molina Bertha , Calles Alipio 
Published: January 2010

AbstractExperiments on the reactivity of CO for Au nanoclusters have shown a local maximum in the adsorption of the first molecule for Au18 and its cation, whereas O2 adsorption has been observed in Au18-1. In this work we present a theoretical analysis of the preferential sites for the adsorption of the CO and O2 molecules on neutral and single ionized Au18 clusters with C2v symmetry, which has been shown both theoretical and experimentally, to be the most stable isomer of the Au18 cluster. We report the results of the calculation for the binding energies of CO and O2 for non-equivalent sites and compare with the available experimental values. The oxidation mechanism is studied in first instance by the subsequent adsorption of the CO on the O2 molecule, which was previously adsorbed on the respective gold cluster. The study is based on a DFT-GGA calculation with the PW91 functional.