bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Variable-Emittance Radiator Based on a Metal-Insulator Transition of (La,Sr)MnO3
Authors: Shimakawa Yuichi , Yoshitake Tsutomu , Kubo Yoshimi , Machida Takahiko , Shinagawa Kiminari , Okamoto Akira , Nakamura Yasuyuki , Ochi Atsushi , Tachikawa Sumitaka , Ohnishi Akira 
Published: April 2011

ABSTRACTVariable-emittance radiators based on the metal-insulator transition of (La,Sr)MnO3 have been developed. The emittance property of the material was evaluated from infrared reflectance spectra; that is, (La,Sr)MnO3 shows low emittance at low temperature but high emittance at high temperature. Moreover, the emittance property significantly changes at the metal-insulator transition temperature, where the material changes from a highly reflective (i.e., low emissivity) metal to a less reflective (i.e., high emissivity) insulator. The (La,Sr)MnO3 thin-films fitted on a spacecraft surface can, therefore, be used to automatically control the emmisive heat transfer from the spacecraft without the need for electrical power. The developed (La,Sr)MnO3 thin-film radiator also greatly reduces the weight and production cost of the thermal control devices.
Open Framework and Microporous Transition Metal Silicates
Authors: Jacobson Allan J. , Wang Xiqu , Liu Lumei , Huang Jin 
Published: April 2011

ABSTRACTA family of microporous and open-framework microporous transition metal silicates have been prepared by hydrothermal synthesis at T ≤ 240 °C. The structures of the compound are based on a common principle in which anionic silicate components (layers, chains, or cluster anions) are connected by isolated transition metal polyhedra by sharing four corners in a square arrangement. Known examples of this class of compounds are reviewed and some recent progress on extending the syntheses to include organic templates are discussed.
A Novel Nanoparticle/Lamellar Oxide Hybrid: TiO2-pillared MoO3
Authors: Paek Seung-Min , Jung Hyun , Choy Jin-Ho 
Published: April 2011

ABSTRACTThe intercalation into MoO3 with TiO2 nanoparticles has been accomplished via the exfoliating-restacking route. The molybdenum oxide lithiated by LiBH4 is exfoliated in degassed and deionized water. And subsequent restacking of exfoliated MoO3 in the TiO2 nanoparticle solution results in TiO2-pillared MoO3. X-ray diffraction pattern indicates that the TiO2 nanoparticles are successfully intercalated in the interlayer of MoO3. The interlayer expansion of MoO3 with the Ad value of 11.2 Å is consistent with the size of TiO2 nanoparticle. Well-defined (00l) reflections reveal highly ordered lamellar character of TiO2-pillared MoO3. The pre-edge feature in the X-ray absorption spectrum of the TiO2-pillared MoO3 confirms that guest TiO2 in the interlayer of MoO3 is pillared in the form of anatase.
Synthesis and Characterization of Structure Controlled Nano-cobalt Particles
Authors: Hui Shiqiang , Wu Mingzhong , Ge Shihui , Yan Dajing , Zhang Y.D. , Xiao T.D. , Yacaman M. J. , Miki-Yoshida M. , Hines W. A. , Budnick J. I. 
Published: April 2011

ABSTRACTNanostructured cobalt particles with and without a ceramic coating have been synthesized using a wet chemical method. The structure and magnetic properties of synthesized powder were characterized using x-ray diffraction (“XRD”), high-resolution transmission electron microscopy (“HRTEM”), and a Quantum Design (SQUID) magnetometer. The cobalt nanoparticles are of either face-centered cubic (“fcc”) and/or hexagonally close-packed (“hcp”) crystalline structures. The average grain size is ∼14 nm for cobalt (either fcc or hcp) with an amorphous silica coating, and the average grain size is ∼9 nm for hcp cobalt and 26 nm for fcc cobalt without a silica coating. The effect of annealing temperature on grain size and magnetic properties are addressed.
Microscale Titania Shapes Grown Within Swollen PDMS
Authors: Brennan Daniel P. , Dobley Arthur D. , Oliver Scott R. J. 
Published: April 2011

ABSTRACTA variety of titania microstructures have been synthesized using a swollen polymer matrix of polydimethylsiloxane (PDMS). The shapes and structures grown to date include spheres, ‘bowls’, ‘nets’ and ‘brain coral’ matrices. The PDMS polymer network can be swollen by one of a variety of organic solvents. These solvents create internal voids or spaces within the PDMS, of particular volume. These spaces can then be filled with metal alkoxide liquid. The metal alkoxide is then polymerized to form metal oxides, in a shape templated by the swollen PDMS polymer. The resultant product is a composite of metal oxide within a polymer. Some of the shapes can be removed mechanically or chemically. Methods of characterization include scanning electron microscopy (SEM) and optical microscopy. Potential applications of the shaped titania include catalysts, fillers, capsules, and chemical separators. The synthesis and characterization of these compounds will be discussed.
Electrochemical Deposition of Ba1-xSrxMoO4 Thin Films at Room Temperature
Authors: Gao D.J. , Xiao D.Q. , Bi J. , Yu P. , Zhang W. , Yu G L. , Zhu J.G 
Published: April 2011

ABSTRACTAseries of well crystallized Ba1-xSrxMoO4 (0≤×≤1) films were prepared on molybdenum substrates in electrolytes embodied Ba2+ and Sr2+ions by electrochemical deposition at room temperature. The composition x is controlled through the starting concentrations of Ba2+ and Sr2+ ions. The measurements of XRD, SEM and XPS for these materials were carried out. The XRD analyses show that the films are good crystalline with single tetragonal structure of scheelite-type, and the a and c axes of the unit cell parameters of the films decrease with the increasing of Sr2+ concentration in the starting electrolytes; the XPS analyses reveal that the composition of the Ba1-xSrxMoO4 films is in agreement with stoichiometry, and the SEM photographs show that the films are condensed deposited.
Sol-gel Synthesis, Magnetic and Structural Characterization of BaFe11.6–2xMxTixO19 (M=Co, Zn, Sn) Compounds.
Authors: Mendoza-Suárez G. , Fuentes A.F. , Escalante-García J.I. , Ayala-Valenzuela O.E. 
Published: April 2011

ABSTRACTSubstituted barium ferrites powders with Ti4+-M2+ (M = Co, Zn, Sn) cationic mixtures were prepared by a sol-gel route. The materials were heat-treated in the range 925–1000 °C and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results showed that the effect of the substitution, x was to lower the coercivity (Hc), owing to the decrease of the magnetocrystalline anisotropy of the magnetoplumbite structure of the BaM. In this regard Sn-Ti substitutions tended to decrease Hc more rapidly than Zn-Ti and Ti-Co substitutions, in that order. Regarding the saturation magnetization (Ms), Zn-Ti mixtures showed slightly better Ms than Ti-Co substitutions; however, the Sn-Ti showed a more marked decrease as x increased. As revealed by SEM, the effect of the heat-treatment temperature was to increase the volume of multi-domain particles, following a Hc decrease due to grain coarsening. Contrarily, as a result of the improved crystallinity of the samples, as observed from the XRD peaks, Ms enhancement was recorded. Crystallite sizes decreased below 100 nm as x increased, although it was also dependent on the cationic mixture. In this respect Sn-Ti substitutions needed higher treatment temperatures to yield materials with adequate crystallinity and phase constitution.
Design and Optical Properties of Rare Earth-Based Mixed-Anions (O, S, F) Compounds
Authors: Pauwels Damien , Demourgues Alain , Tressaud Alain 
Published: April 2011

ABSTRACTRare earth-based mixed-anions (O, S, F) compounds have been prepared by solid state route. The structures have been determined on the basis of powder diffraction (X-ray/neutrons) refinement and/or single crystal analysis. They have been described as a stacking of [Sx] 2x- layers and fluorite type blocks. The evaluation of the rare earth environment (bondlength, number of neighbors) can be directly related to the bandgap and to the UV-visible absorption in the La-based compounds.
Impedance/Dielectric Spectroscopy of Electroceramics in the Nanograin Regime
Authors: Kidner N. J. , Ingram B. J. , Homrighaus Z. J. , Mason T. O. , Garboczi E. J. 
Published: April 2011

ABSTRACTIn the microcrystalline regime, the behavior of grain boundary-controlled electroceramics is well described by the “brick layer model” (BLM). In the nanocrystalline regime, however, grain boundary layers can represent a significant volume fraction of the overall microstructure and simple layer models are no longer valid. This work describes the development of a pixel-based finite-difference approach to treat a “nested cube model” (NCM), which more accurately calculates the current distribution in polycrystalline ceramics when grain core and grain boundary dimensions become comparable. Furthermore, the NCM approaches layer model behavior as the volume fraction of grain cores approaches unity (thin boundary layers) and it matches standard effective medium treatments as the volume fraction of grain cores approaches zero. Therefore, the NCM can model electroceramic behavior at all grain sizes, from nanoscale to microscale. It can also be modified to handle multi-layer grain boundaries and property gradient effects (e.g., due to space charge regions).
Surface properties of disordered γ MnO2 at the solid-electrolyte interface.
Authors: Prélot Bénédicte , Poinsignon Christiane , Thomas Fabien , Villiéras Frédéric 
Published: April 2011

ABSTRACTRelationships between lattice parameters of manganese dioxides (γ/ε-MD) and their surface properties at the solid-aqueous solution interface were investigated. The studied series ranged from orthorhombic ramsdellite to tetragonal pyrolusite and encompassed disordered MD samples. The structural model used takes into account two structural defects which affect the orthorhombic network of ramsdellite: Pr (rate of pyrolusite intergrowth) and Tw (rate of microtwinning). Water adsorption isotherms showed that the cross sectional surface area of water molecules is linearly correlated to Pr: from 6.3 Å2 (Pr=0.2) to 13.1 Å2 (Pr=1). Titration of their surface charge evidenced a linear relationship between PZC and Pr starting from ramsdellite (Pr = 0, Tw = 0, PZC = 1) to pyrolusite (Pr = 1, Tw = 0, PZC = 7.3). γ-MD with intermediate values of Pr (0.2 to 0.45) have increasing PZC values. For similar Pr values (0.45), high Tw percentage (0.3 and 1) makes the PZC to increase. The experimental results are compared with data collected in the literature for dioxides of transition elements with tetragonal structure. Surface titration leads to the determination of electrochemically active surface area at alkaline pH.
Development of new ceramic doped ionoconducting membranes for biomedical applications.
Authors: Romagnoli Paola , Vona Maria Luisa Di , Traversa Enrico , Narici Livio , Sannita Walter G. , Carozzo Simone , Trombetta Marcella , Licoccia Silvia 
Published: April 2011

ABSTRACTNew ionoconducting composite membranes to be used as an interface between the skin and the actual electrical instrumentation used to produce an electroencephalogram (EEG) have been developed. The gels are based on lithium salts and PMMA (polymethyl methacrylate) and have been doped with nanometric titanium oxide. The samples have been electrochemically characterized by means of impedance spectroscopy and their structure studied by ATR-FTIR and MAS NMR. Spectroscopic studies indicate interactions between the polymer and oxide dopant. The polymeric electrolytes allowed the registration of good electrophysiological cortical signals either spontaneous or stimulus-related.
Next Generation Positive Electrode Materials Enabled by Nanocomposites: -Metal Fluorides-
Authors: Badway F. , Pereira N. , Cosandey F. , Amatucci G. G. 
Published: April 2011

ABSTRACTThrough the use of nanostructures and nanocomposites, the electrochemical activity of metal fluoride materials was opened as potential candidates as next generation high energy density positive electrodes for Li batteries. This class of materials, utilizing FeF3 as an example, is shown to exhibit good reversible behavior of approximately 200 mAh/g in the 3V region. The specific capacity is extended to 600 mAh/g when the discharge is extended to take into account the additional specific capacity associated with a 2V plateau. Through the use of XRD, SAED and high resolution TEM, the 2V reaction mechanism was associated to a reversible metal fluoride conversion mechanism. It is shown that LiF + Fe nanocomposite can be utilized as initial components in order to make the technology suitable for Li-ion applications. Although exhibiting relatively poor rate capabilities at this initial stage, reversible conversion metal fluorides enable for the first time the utilization of all the redox states of the constituent metal in a reversible manner in the positive electrode. This translates to 4X the specific capacity and double the energy density of today's state of the art LiCoO2.
In SituElectrochemical Scanning Probe Microscopy of Lithium Battery Cathode Materials: Vanadium Pentoxide (V2O5)
Authors: Bullard Joseph W. , Smith Richard L. 
Published: April 2011

ABSTRACTAtomic force microscopy was used to characterize the structural evolution of the V2O5(001) surface during the electrochemical cycling of lithium. With Li insertion, nanometer-scale pits develop at the V2O5(001) surface. The pits first appear as the composition of the crystal approaches Li0.0006V2O5. Pit nucleation and growth continue through further discharge, resulting in a micro-porous (001) surface morphology. During subsequent Li extraction, cracks develop along the V2O5<010> axis. Surface regions in the vicinity of these cracks “swell” during ensuing lithiation reactions, suggesting that the cracks locally facilitate Li uptake.
Sn and SnBi Foil as Anode Materials for Secondary Lithium Battery
Authors: Yang Shoufeng , Zavalij Peter Y. , Stanley Whittingham M. 
Published: April 2011

ABSTRACTIn order to better understand the cycling mechanism of metal alloy anodes, and to mitigate the capacity fade observed in lithium battery use a study of simple systems was initiated. Tin foil and tin-bismuth mixtures were chosen because there is no need for conductive diluents or binders so that the intrinsic behavior could be observed. A pure tin foil was found to react rapidly with lithium, ≥ 3 mA/cm2, and with no capacity fade for over 10 cycles. This is better than tin powder or electrodeposited tin. After the first cycle, the foil reacts with Li following a stepwise formation of different alloys as dictated by the thermodynamics. Incorporation of bismuth into the foil increased the capacity fade after the first few cycles, with the eutectic composition Sn0.57Bi0.43 having better capacity retention than the Sn0.5Bi0.5 composition. XRD and SEM-EDS shows that bismuth is rejected from the tin rich phase during lithium insertion and is not reincorporated on lithium removal, just as expected from the phase diagram.
Synthesis and sintering of Ce1-xGdxO2-x/2 nanopowders via chemical routes.
Authors: Sin Agusti , Aricò Antonino S. , Seregni Massimo , Gullo Laura , Rosa Daniela La , Siracusano Stefania , Antonucci Vincenzo , Tavares Ana , Dubitsky Yuri , Zaopo Antonio 
Published: April 2011

ABSTRACTGd-doped ceria (Ce0.80Gd0.20O1.90) obtained by several nanopowder synthesis processes are compared structurally, morphologically and electrochemically. The powders have been sintered into pellets and investigated by ac-impedance measurements. The electrochemical properties of the electrolytes have been correlated to the structural morphology of the sintered pellets. When the intergrain region exhibits an elevated interdiffusion, the observation of the grain boundaries becomes difficult while the electrochemical properties are improved. Acrylamide polymerization and oxalic co-precipitation techniques showed the best properties.
Preparation and Characterization of Metal Sulfide Electro-catalysts for PEM Fuel Cells
Authors: Zhang Hua , Verde-Gómez Ysmael , Jacobson Allan J. , Ramirez Alejandra , Chianelli Russell R. 
Published: April 2011

ABSTRACTRuthenium sulfide samples were prepared by flowing pure hydrogen sulfide into an aqueous solution of ruthenium chloride followed by further sulfidation in hydrogen sulfide. The final products were characterized by X-ray diffraction and crystallite-sizes were estimated from line broadening. The specific surface areas of catalysts were measured using the multipoint BET method and compositions were determined by thermogravimetric analysis. Ruthenium sulfide loaded gas diffusion electrodes were fabricated by a spraying technique and their electrochemical behavior studied. The electrochemical oxidation of hydrogen was investigated in a three -electrode cell using a ruthenium sulfide loaded gas diffusion electrode as the working electrode with humidified hydrogen containing small amounts of carbon monoxide. Results on the activity and the effects of carbon monoxide with reference to a standard platinum electrode measured at the same conditions show that ruthenium sulfide has a lower activity for hydrogen oxidation but is not susceptible to CO poisoning.
Corrosion-Resistant Tantalum Coatings for PEM Fuel Cell Bipolar Plates
Authors: Gladczuk Leszek , Joshi Chirag , Patel Anamika , Guiheen Jim , Iqbal Zafar , Sosnowski Marek 
Published: April 2011

ABSTRACTTantalum is a tough, corrosion resistant metal, which would be suitable for use as bipolar plates for proton exchange membrane (PEM) fuel cells, if it was not for its high weight and price. Relatively thin tantalum coatings, however, can be deposited on other inexpensive and lighter weight metals, such as aluminum and steel, providing a passive protection layer on these easily formed substrates. We have successfully deposited, high quality α (body-centered-cubic, bcc) and β (tetragonal) phase tantalum coatings that were a few micrometers thick by dc magnetron sputtering on steel and aluminum. The growth of the thermodynamically preferred body-centered-cubic (bcc) tantalum phase was induced by a choice of deposition conditions and substrate surface treatment. The microstructure and corrosion resistance of the α-phase in an environment approximately simulating the electrochemical conditions used in a PEM fuel cell were investigated under potentiodynamic conditions. Preliminary potentiostatic measurements of a β-phase sample are also presented.
A Numerical Study of Compaction of Dry Granular Material
Authors: Sulsky Deborah 
Published: April 2011

ABSTRACTThe material-point method is used to examine numerically the macroscopic stress-strain response of a granular sample under compression. The simulations reproduce experimental observations of the large stiffening that occurs as the granular bed becomes packed. We also show the network of force chains that forms and how the character of contacts between grains changes for large deformations. Finally, we examine the probability distribution of forces and observe exponential distributions above the mean with a small peak at the mean for small deformations, and a transition to a larger peak at larger deformations.
The NSF NSDL GREEN Digital Library:

G

reen's Functions

R

esearch And

E

ducation

E

nhancement

N

etwork
Authors: Bartolo Laura M. , Powell Adam C. , Shreve Gregory M. , Tewary Vinod K. 
Published: April 2011

ABSTRACTGreen's functions are powerful mathematical tools with strong pedagogical value providing not only solutions to difficult problems but also visualization for understanding phenomena. The majority of upper division engineering and materials science students receive very little exposure to Green's functions and the boundary element method. The Green's Functions Research and Education Enhancement Network (GREEN) Digital Library which the authors are developing will, therefore, play an important role in undergraduate and graduate education. The National Science Foundation has launched the National Science, Mathematics, Engineering, and Technology Education Digital Library (NSDL) program to stimulate and sustain continual improvements in the quality of science, mathematics, engineering, and technology education. The NSDL Program is a major digital library initiative and the GREEN Digital Library is a collaboration of the Center for Theoretical and Computational Materials Science of the Materials Science and Engineering Laboratory at the National Institute of Standards and Technology, Kent State University, and the Massachusetts Institute of Technology. This paper describes the primary components of the GREEN Digital Library, an organized collection of educational materials integrating research, education, and application of Green's functions to serve undergraduate and graduate communities:1. Problem Bank: A bank of available “real-world” problems, introduced by industrial participants.2. Code Bank: Working code for solved Green's functions routines.3. Archive: A list of citations to relevant literature, and published / unpublished works subject to copyright restrictions, with links elsewhere for additional information.4. Teaching Bank: A collection of lecture / course notes from existing university courses, as well as providing a forum for discussion of approaches to teaching this material.
Web-Based Data Analysis and Feedback for General Chemistry Laboratory: Improving Analysis with Timely, Distance Feedback
Authors: Lomax Joseph F. , Dillner Debra K. , Teichert Melonie A. 
Published: April 2011

ABSTRACTIn a general chemistry course, while the hands-on experience of the laboratory is important, the goals of the laboratory are not fulfilled until the calculations and analysis are complete. Quite often students are capable of following laboratory instructions and generating excellent data, only to fail in the data analysis, which rarely occurs in the confines of the laboratory or the presence of the instructor. All too often, students are unable to learn important information from the interpretation of experimental results and draw correct conclusions because they make calculational errors, which are most often discovered by the instructor in the grading process. There is an opportunity for distance learning to help bridge the gap between collection of data and its correct analysis. At the United States Naval Academy (USNA), we have developed a Web-based system where the students input their data and calculational results into a web form with immediate feedback. The students are then allowed to correct their errors and resubmit. This system has been in successful use for 5 years. A description of a typical experiment will be discussed along with an assessment of student and faculty satisfaction with the program.