bluuebunny/crossref_metadata_2025_split huggingface dataset:
Work Function Study for the Search of Efficient Target Materials for Use in Hyperthermal Surface Ionization Using a Scanning Kelvin Probe
Authors: Petermann U. , Baikie I.D. , Lägel B. , Dirscherl K.M. 
Published: April 2011

AbstractIn order to search for efficient target materials for use in Hyperthermal Surface lonisation (HSI), a new mass spectroscopy ionisation technique, we have performed a study of high and low work function (ø) surfaces as part of an ongoing project. HSI relies on high and low work function surfaces for the production of positive (pHSI) and negative (nHSI) ions, respectively.Using a novel UHV Scanning Kelvin Probe we have followed the oxidation kinetics of polycrystalline Re at different temperatures and examined the effects of oxidation, flash annealing and sputter-anneal cleaning cycles via high resolution work function topographies. Our results indicate that oxidised Re is the best candidate for pHSI in terms of ionisation efficiency and ø change. The peak work function change of 2.05 eV occurred at 900 K to 950K.For the nHSI materials Calcium exhibited the best performance with respect to the ionisation efficiency indicating a wf of 2.9 eV. We will present data in terms of mass fragmentation using an HSI-Time-of-Flight (TOF) system and time stability of the work function.
Volatile, Fluorine-Free β-Ketoiminate Precursors for MOCVD Growth of Lanthanide Oxide Thin Films
Authors: Edleman N.L. , Belot J.A. , Babcock J.R. , Metz A.W. , Metz M.V. , Stern C.L. , Marks T.J. 
Published: April 2011

AbstractLanthanide oxide thin films are of increasing scientific and technological interest to the materials science community. A new class of fluorine-free, volatile, low-melting lanthanide precursors for the metal-organic chemical vapor deposition (MOCVD) of these films has been developed. Initial results from a full synthetic study of these lanthanide-organic complexes are detailed.
Preparation and Characterization of Epitaxial Bi2WO6 Thin Films Prepared by a Sol-Gel Process
Authors: Nishio Keishi , Kudo Chikako , Nagahama Tsutomu , Manabe Takaaki , Yamaguchi Iwao , Watanabe Yuichi , Tsuchiya Toshio 
Published: April 2011

AbstractWe have succeeded in an epitaxial growth of bismuth tungstate (Bi2WO6, BWO) thin films, one of the bismuth layer-structure ferroelectrics (BLSF), on SrTiO3 (001) single crystal substrates by a spin coating process. BLSF are known to be one of the promising materials for ferroelectric random access memory (FeRAM) devices. A homogeneous coating solution was prepared with tungsten hexachloride and bismuth 2-ethylhexanoate as raw materials, and 2-(2-methoxyethoxy) ethanol and formamide as solvents. The as-coated thin films were sintered at temperatures from 500 to 800°C for lh in air. BWO crystallized at temperatures above 500°C. Any crystal phase was not observed in the thin films except for (001) phases of BWO in the XRD patterns. It was confirmed that the thin film was growing epitaxially by measurement of XRD pole figure. The crystallographic relationship of the film and substrate was BWO(001)//STO(001), BWO[110]//STO[100].
Effects of the Heat-Treatment Conditions on Microstructures of YbBa2Cu3O7-σ Superconducting Films Formed by the Dipping-Pyrolysis Process
Authors: Shibata J. , Yamagiwa K. , Hirabayashi I. , Hirayama T. , Ikuhara Y. 
Published: April 2011

AbstractYbBa2Cu3O7-σ(Yb123) films were formed on SrTiO3(STO)(001) and LaAlO3(LAO)(001) substrates by the dipping-pyrolysis process. Using transmission electron microscopy, we investigated effects of the heat-treatment conditions in the processes of the dipping-pyrolysis method on microstructures of these films. As a result, we found that the high heating rates at the initial and final heat-treatments are necessary for achieving the epitaxial growth of the superconducting films.
Micro Pattern of TiO2 Thin Film Formation by Direct Synthesis From Aqueous Solution and Transcription of Resist Pattern
Authors: Yao Takeshi , Uchimoto Yoshiharu , Yabe Hiroki 
Published: April 2011

AbstractDirect synthesis from aqueous solution (DSAS) is the method for synthesizing ceramic oxides in crystalline state directly from aqueous solution at ordinary temperature and ordinary pressure. DSAS is advantageous because of the applicability to making films with wide areas and/or complicated shapes with no requirement of vacuum or high temperature. Micro patterning of materials having high dielectric constant is important for manufacturing electronic devices such as dynamic random access memory, ferroelectric random access memory and so on. By using DSAS, TiO2 thin film was formed on the glass plate surface where micro pattern had been printed by commercial organic photoresist material. Then the resist material was dissolved off by acetone or ethanol with the TiO2 thin film just on. From SEM observation, it is indicated that micro pattern of TiO2 thin film transcribing the resist pattern with minimum line width of I νm was obtained. This method will be applicable to the construction of highly integrated dielectric devices.
New Structure Model for Lithium Nickel Batteries
Authors: Monge M.A. , Gutiérrez-Puebla E. , Rasines I. , Campa J.A. 
Published: April 2011

AbstractAfter growing black colored single crystals of LixNi1−xO (x = 0.27) and solving its crystal structure, a model is proposed as an alternative to the structural type admitted for LixNi1−xO. The new rhombohedral cell consists of a cubic close packing of oxygens in which the alternation of two kind of mixed layers containing Li and Ni in different ratios can be detected along the c direction. This model implies a Li order incompatible with the alternation of Ni layers, one of them pure and the other containing some Li. The results of magnetization measurements look consistent with the new structural type, and reveal that LixNi1−xO behaves as mictomagnetic.
Materials Design for the Low-Resistivity in p-Type ZnO and Transparent Ferromagnet With Transition Metal Atom Doped ZnO: Prediction vs. Experiment
Authors: Sato K. , Katayama-Yoshida H. , Yamamoto T. 
Published: April 2011

AbstractWe propose a new valence control method of codoping with doping Ga (or In, Al) donor and N acceptor at the same time for the fabrication of a low-resistivity p-type ZnO based upon the ab initio calculation. We compare our predicted materials design to fabricate a low resistivity p-type ZnO with the recent successful codoping. Based upon the success in the valence control of ZnO, we propose a materials design to fabricate the ferromagnetic Mn-doped p-type ZnO upon codoping. It is shown that the anti-ferromagnetic state is more stable than the ferromagnetic ones due to the anti-ferromagnetic super-exchange interaction, if we have no mobile holes. Upon codoping with the mobile holes, it is shown that the ferromagnetic state becomes more stable than the anti-ferromagnetic ones due to the ferromagnetic double-exchange interaction. However, it is shown that the anti-ferromagnetic state is more stable upon electron doping due to the anti-ferromagnetic super-exchange interaction. We calculate the chemical trends of the magnetic state in V-, Cr-, Fe-, Co-, and Ni-doped (25 at%) in ZnO, and predict that all of these materials show the ferromagnetic ground states without electron and hole doping.
Laser Direct Write of Conducting and Insulating Tracks in Silicon Carbide
Authors: Sengupta D.K. , Quick N.R. , Kar A. 
Published: April 2011

ABSTRACTConventional direct write processes are multi-step requiring at least one additional process to change conductive properties. A direct conversion technique that uses lasers to irradiate silicon carbide, providing tracks which are highly conductive has been demonstrated. It was found that laser irradiation of insulating silicon carbide films could cause a drop from 1011 to 10−4 ohm-cm in a 4-point resistance test. However, in the presence of pure oxygen, laser-irradiated silicon carbide conductor and semiconductor samples exhibit insulating characteristics. Pattern formation was achieved by a computer program controlled galvo-mirror. The pads, 0.4 cm × 0.7 cm were formed by beam rastering with an overlap of 30% of the 0.025 cm beam diameter. This computer assisted processing allows the design of patterns using conventional CAD/CAE technologies and smart material behavior via selective and controlled electrical property transitions by laser irradiation
Focused Electron Beam Induced Deposition of Gold and Rhodium
Authors: Hoffmann P. , Utke I. , Cicoira F. , Dwir B. , Leifer K. , Kapon E. , Doppelt P. 
Published: April 2011

ABSTRACTElectron beam induced deposition with two noble metal precursors (Rhodium and Gold) having the same halogeno and trifluorophosphine ligands is presented. The deposit geometry of lines and freestanding bridges is discussed with respect to electron energy, beam shape, and backscattered electron distribution. Electron beam heating effects are estimated to be negligible in our deposition conditions. Using PF3AuCl, lines of percolating gold grains were deposited with electrical resistivities as low as 22μωcm at room temperature (Au: 2.2μωcm). Auger electron analysis shows about 60at% Rh in deposits obtained with [RhCI(PF3)2]2, however the resistivity of 1ωcm is high compared to 4.5μωcm of pure Rh.
Computational Modeling of Direct Print Microlithography
Authors: Darhuber A. A. , Miller S. M. , Troian S. M. , Wagner S. 
Published: April 2011

ABSTRACTUsing a combination of experiment and simulations, we have studied the equilibrium shapes of liquid microstructures on flat but chemically heterogeneous substrates. The surface patterns, which define regions of different surface energy, induce deformations of the liquid-solid contact line, which in turn can either promote or impede capillary break-up and bulge formation. We study numerically the influence of the adhesion energies on the hydrophilic and hydrophobic surface areas, the pattern geometry and the deposited fluid volume on the liquid surface profiles
Deposition of Ceramic Materials Using Powder and Precursor Vehicles Via Direct Write Processing
Authors: Rack P.D. , Fitz-Gerald J.M. , Geiculescu A.C. , Rack H.J. , Piqué A. , Auyeung R.C.Y. , Chrisey D.B. 
Published: April 2011

ABSTRACTDry powder and sol gel ceramic films were deposited using a Matrix Assisted Pulsed Laser Evaporation Direct Write (MAPLE-DW) technique developed at NRL for optical and electrical device applications. The MAPLE-DW technique uses a high-energy focussed photon source in combination with a “ribbon” to fabricate materials onto a range of substrates at room temperature without material degradation. Two different classes of materials were processed in this research, (1) ceramic dry powder materials and (2) sot gel precursor materials. Cathodoluminescent measurements demonstrated that the efficiencies of the transferred phosphor materials were not degraded during the laser transfer process. Scanning electron microscopy and 3-D surface profilometry of the ribbon after the MAPLE-DW process revealed a 90–95% transfer efficiency for the dry powders. Scanning electron microscopy and energy dispersive spectroscopy revealed that the sol gel materials also transferred with an efficiency in the 90-95% range. Three distinct regions were identified on the so gel ribbon after the laser transfer process. The regions suggest that the matrix absorbing layer and the sol gel materials are completely removed for the areas irradiated by the laser pulse, and in a second so-called “heat affected region,” only the sol gel material is ejected from the ribbon.
Material Systems Used by Micro Dispensing and Ink Jetting Technologies
Authors: Zhang Jie , Shmagin Irina , Skinner James , Szczech John , Gamota Daniel 
Published: April 2011

ABSTRACTIn today's electronic industry, manufacturers are continuously improving capital utilization, developing flexible manufacturing processes, reduce changeover time and improving yield and throughput. Interest in rapid prototyping and 3-D fabrication capabilities are rapidly increasing, and a number of candidate direct writing technologies are in development to meet these demands.This work studies material systems used by data driven materials deposition (DDMD) technologies for potential low temperature reel-to-reel high volume manufacturing on low cost substrates. Characterization results of fabricated discrete and RF devices using commercially available micro dispensing and ink jet systems will be discussed. Material rheological properties, deposition process characterization, deposition repeatability, fabricated device reliability and electrical performance will be presented. The test vehicles contain resistors and capacitors, transmission lines, open and short series stub filters, and half-wavelength resonators. The material/substrate compatibility will be demonstrated through environmental conditioning of the test vehicles. In addition, a cost estimate for using micro dispensing technologies was conducted to compare current manufacturing technologies to DDMD.
Laser Direct-Write of Materials for Microelectronics Applications
Authors: Rahman K. M. A. , Wells D. N. , Duignan M. T. 
Published: April 2011

ABSTRACTWe demonstrate a laser direct-write method, a maskless process that transfers material directly from a ribbon to a substrate. This process offers the promise of fabricating passive electronic micro-components at a high speed with high spatial resolution. We are developing a workstation implementing this direct-write method, which integrates deposition, direct laser sintering, and micromachining capability on a single machine. Using this workstation we have deposited micro-patterns of conducting lines and resistors on alumina and polyimide substrates under ambient conditions that exhibit good electrical properties and substrate adhesion. From preliminary studies of laser sintering it was found that a wide range of sintering conditions may be used to arrive at silver conducting lines (∼60 µm × 10 µm) on alumina substrate with resistivity in the range of 5 to 10 times the resistivity of bulk silver. Preliminary results also indicate direct laser sintering of cermet resistor material can yield reproducible resistance values.
Calculation of Hamaker Constants in Nonaqueous Fluid Media
Authors: Bell Nelson , Dimos Duane 
Published: April 2011

AbstractCalculations of the Hamaker constants representing the van der Waals interactions between conductor, resistor and dielectric materials are performed using Lifshitz theory. The calculation of the parameters for the Ninham-Parsegian relationship for several non-aqueous liquids has been derived based on literature dielectric data. Discussion of the role of van der Waals forces in the dispersion of particles is given for understanding paste formulation. Experimental measurements of viscosity are presented to show the role of dispersant truncation of attractive van der Waals forces.
Modeling and Optimization of Novel Actuators Produced by Solid Freeform Fabrication
Authors: Cheeseman B.A. , Ruan X.P. , Safari A. , Danforth S.C. , Chou T.W. 
Published: April 2011

AbstractThe ability of Solid Freeform Fabrication (SFF) to produce complex piezoceramic architectures has enabled the development of novel designs for PZT actuators. Recently, it has been shown that through the intelligent application of actuator geometry, poling direction, piezoelectric material, and electric field direction, the force and displacement output of a piezoelectric actuator could be optimized. The current investigation examines several piezoceramic actuator geometries, including dome, spiral and a telescoping shaped actuators. Using finite element analysis (FEA), parametric studies are performed to identify some key issues in the optimization of actuator performance. Results of the dome study indicate that an actuator having a tangentially alternating poling direction and applied electric field exhibits a much larger displacement when compared to dome actuators having either a through-the-thickness or tangential poling direction. Analysis of spiral actuators indicates that the spiral geometry results in pronounced displacement amplification when compared to the displacement of an equivalent length piezoelectric strip. In summary, some remarks will be made on the optimal use of piezoelectric material properties and actuator geometry in actuator design.
Automated Fabrication of Ceramic Electronic Packages by Stereo-Photolithography
Authors: Zimbeck W.R. , Jang J. H. , Schulze W. , Rice R. W. 
Published: April 2011

AbstractSignificant cost and timesavings can be realized by applying automated freeform fabrication techniques to the fabrication of ceramic electronic packaging. The widely used thick film/screen printing approach for ceramic packaging involves multiple separate processing stations to build up a multilayer package with embedded electrical connectivity. The current process steps include tape casting, conductor pattern screen-printing, punching/filling of vias, dicing, alignment and lamination. The development of low and high temperature co-fire ceramic systems (LTCC and HTCC) has streamlined the firing process, but significant inefficiencies remain in constructing the green state package, such that prototyping of ceramic packages is often very expensive with substantial lead times. This paper describes an integrated approach that combines the automated three-dimensional capabilities of stereolithography of ceramics and metals with the high resolution and precision of advanced photolithography systems. The process utilizes photocureable resins filled with sinterable ceramic and metal particles, which are applied layer-by-layer and photopatterned to build up a multilayer package. Materials development has focused on a glass-ceramic dielectric, a silver conductor and a barium titanate dielectric. Resin rheology and photocuring characteristics, thermal processing and sintered properties of the materials are described. A breadboard processing system was constructed and the results of fabricating test circuits are presented.
Microstructural Study of Laser Formed Ti-6Al-4V
Authors: Kelly S.M. , Kampe S.L. , Crowe C.R. 
Published: April 2011

AbstractA microstructural evaluation of as-deposited LasformedSM Ti-6Al-4V, a Laser Additive Manufacturing (LAM) process, is the subject of the current work. Distinct features of the macrostructure include: large columnar prior-β grains (the initial solid to form upon cooling from the melt) have grown through multiple deposited layers due to epitaxial growth from previously solidified layers; a well defined heat affected zone; the presence of “layer bands,” which are speculated to be a result of macrosegregation in the solidifying melt puddle and/or the complex thermal history that the part received as it was built, layer by layer. The microstructure of the layer band consists of larger colonies of acicular α outlined in transformed β, whereas the adjacent material consists of smaller colonies having the same type of structure.
Processing-Structure-Property Relations of Polymer-Polymer Composites Formed by Cryogenic Mechanical Alloying for Selective Laser Sintering Applications
Authors: Schultz J. P. , Martin J. P. , Kander R. G. , Suchicital C. T. A. 
Published: April 2011

AbstractCryogenic mechanical alloying (CMA) has been shown to be an effective means for producing composite powders for selective laser sintering (SLS). Unlike composite particles made by a coating process, both phases are continuous throughout the particles formed by CMA. Consolidation of these composite particles via SLS offers the possibility of forming parts with a co-continuous microstructure. In this research, the microstructure of mechanically alloyed polymer-polymer composites for use in the SLS process is investigated using transmission electron microscopy. By varying the charge ratio and milling time of the CMA process, the phase domain size of the resulting composite powder can be manipulated. This ongoing work explores the microstructural evolution as the composite powders are consolidated via SLS into macroscopic parts, as well as the relationships between microstructure and bulk properties.
Mechanical Spectroscopy of Nanocrystalline Metals
Authors: Bonetti E. , Pasquini L. , Savini L. 
Published: April 2011

ABSTRACTThe mechanical behavior of nanocrystalline iron and nickel prepared by mechanical attrition and inert gas condensation was investigated using mechanical spectroscopy techniques in the quasi static-and low frequency dynamic stress-strain regimes. The measures were performed on samples previously stabilized by thermal annealing at low homologous temperatures. The results of elastic energy dissipation, creep, and creep recovery measurements performed in the low strain regime (ε = 10−5−10−3) allowed to trace a phenomenological picture of the anelastic and viscoplastic behavior of nanocrystalline Ni and Fe in the 300-450 K range with different grain sizes and interfaces disorder degree. Activation energies of the thermally activated anelastic and plastic mechanisms responsible for the mechanical behavior have been evaluated.
Dislocations in Submicron Grain Size and Nanocrystalline Copper
Authors: Ungár T. , Tichy G. , Sanders P. G. , Weertman J. R. 
Published: April 2011

ABSTRACTUsing the dislocation model of strain anisotropy in X-ray diffraction peak profile analysis it is shown that in nanocrystalline copper produced by inert gas condensation dislocations are present, at least, down to average grain sizes of the order of 20 nm. Based on the analysis of the dislocation contrast factors it is suggested that with decreasing grain size the proportion of Lomer-Cottrell type dislocations increases.
Logarithmic Relaxation of Resistance in Time of Annealed and Plastically Deformed Au80Fe20
Authors: Allia P. , Baricco M. , Bosco E. , Coisson M. , Falletti D. , Selvaggini V. , Tiberto P. , Vinai F. 
Published: April 2011

ABSTRACTRapidly solidified Au80Fe20 ribbons were prepared either by melt spinning or by solidstate quenching of a homogenised master alloy. The as-quenched sample displays a paramagnetic behavior indicating a perfect solid solution of Fe in the Au matrix. Subsequent anneals have been performed to induce the precipitation of Fe particles. X-ray diffraction technique have been exploited to determine the alloy microstructure. The structural stability have been studied by measuring electrical properties in isothermal and tempering condition. The variation of magnetisation and electrical resistance have been measured after submitting the samples to plastic deformation. A logarithmic relaxation of the electrical resistance is observed in all studied samples after deformation. Magnetic hysteresis loops have been measured in as-quenched and annealed samples at different temperatures. X-ray diffraction and magnetic measurements indicate that thermal treatments have been successful in inducing the precipitation of both bcc and fcc Fe clusters.
Monte Carlo Simulations of Grain Boundary Sliding and Migration: Effect of Temperature and Vacancy
Authors: Ballo P. , Kioussis N. , Lu Gang 
Published: April 2011

ABSTRACTWe have carried out Monte Carlo (MC) simulations using the embedded atom potential to study the sliding and migration of the σ5 [001] (210) tilt grain boundary (GB) in aluminum and the effect of vacancies on the sliding properties. We find that the simulated annealing allows the system to gradually anneal to a global-minimum configuration, thus increasing the number of migrations and reducing the GB sliding energy barriers to about a factor of three compared to the corresponding “static” values. The distribution of atomic energies as a function of GB displacement, provide insight into which atoms are responsible for the GB migration. The vacancy formation energy is found to be lower when the vacancy is placed on the first layer to the boundary, in excellent agreement with ab initio electronic structure calculations. The sliding and migration properties depend very sensitively on the position of the vacancy in the GB core.