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Sample records for binary metal oxides

  1. Atomic-Scale Tuning of Layered Binary Metal Oxides for High Temperature Moving Assemblies

    DTIC Science & Technology

    2015-06-01

    AFRL-OSR-VA-TR-2015-0166 Atomic -Scale Tuning of Layered Binary Metal OxideS ASHLIE MARTINI UNIVERSITY OF CALIFORNIA MERCED Final Report 06/01/2015...COVERED (From - To)      01-05-2012 to 30-04-2015 4.  TITLE AND SUBTITLE Atomic -Scale Tuning of Layered Binary Metal Oxides for High Temperature Moving...understand, at an atomic level, the material properties that influence the thermal, mechanical and tribological behavior of intrinsically layered binary

  2. Toxicity of binary mixtures of metal oxide nanoparticles to Nitrosomonas europaea.

    PubMed

    Yu, Ran; Wu, Junkang; Liu, Meiting; Zhu, Guangcan; Chen, Lianghui; Chang, Yan; Lu, Huijie

    2016-06-01

    Although the widely used metal oxide nanoparticles (NPs) titanium dioxide NPs (n-TiO2), cerium dioxide NPs (n-CeO2), and zinc oxide NPs (n-ZnO) have been well known for their potential cytotoxicities to environmental organisms, their combined effects have seldom been investigated. In this study, the short-term binary effect of n-CeO2 and n-TiO2 or n-ZnO on a model ammonia oxidizing bacterium, Nitrosomonas europaea were evaluated based on the examinations of cells' physiological, metabolic, and transcriptional responses. The addition of n-TiO2 mitigated the negative effect of more toxic n-CeO2 and the binary toxicity (antagonistic toxicity) of n-TiO2 and n-CeO2 was generally lower than the single NPs induced one. While the n-CeO2/n-ZnO mixture exerted higher cytotoxicity (synergistic cytotoxicity) than that from single NPs. The increased addition of the less toxic n-CeO2 exaggerated the binary toxicity of n-CeO2/n-ZnO mixture although the solubility of n-ZnO was not significantly affected, which excluded the contribution of the dissolved Zn ions to the enhancement of the combined cytotoxicity. The cell membrane disturbances and NP internalizations were detected for all the NP impacted cultures and the electrostatic interactions among the two distinct NPs and the cells were expected to play a key role in mediating their direct contacts and the eventual binary nanotoxicity to the cells.

  3. Sn-Mn binary metal oxides as non-carbon sorbent for mercury removal in a wide-temperature window.

    PubMed

    Xie, Jiangkun; Xu, Haomiao; Qu, Zan; Huang, Wenjun; Chen, Wanmiao; Ma, Yongpeng; Zhao, Songjian; Liu, Ping; Yan, Naiqiang

    2014-08-15

    A series of Sn-Mn binary metal oxides were prepared through co-precipitation method. The sorbents were characterized by powder X-ray diffraction (powder XRD), transmission electronic microscopy (TEM), H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) methods. The capability of the prepared sorbents for mercury adsorption from simulated flue gas was investigated by fixed-bed experiments. Results showed that mercury adsorption on pure SnO2 particles was negligible in the test temperature range, comparatively, mercury capacity on MnOx at low temperature was relative high, but the capacity would decrease significantly when the temperature was elevated. Interestingly, for Sn-Mn binary metal oxide, mercury capacity increased not only at low temperature but also at high temperature. Furthermore, the impact of SO2 on mercury adsorption capability of Sn-Mn binary metal oxides was also investigated and it was noted that the effect at low temperature was different comparing with that of high temperature. The mechanism was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs). Moreover, a mathematic model was built to calculate mercury desorption activation energy from Sn to Mn binary metal oxides.

  4. Novel regenerable sorbent based on Zr-Mn binary metal oxides for flue gas mercury retention and recovery.

    PubMed

    Xie, Jiangkun; Qu, Zan; Yan, Naiqiang; Yang, Shijian; Chen, Wanmiao; Hu, Lingang; Huang, Wenjun; Liu, Ping

    2013-10-15

    To capture and recover mercury from coal-fired flue gas, a series of novel regenerable sorbents based on Zr-Mn binary metal oxides were prepared and employed at a relatively low temperature. PXRD, TEM, TPR, XPS, and N2-adsorption methods were employed to characterize the sorbents. The Hg(0) adsorption performance of the sorbents was tested, and the effects of the main operation parameters and the gas components on the adsorption were investigated. Zr significantly improved the sorbent's mercury capacity, which was nearly 5mg/g for Zr0.5Mn0.5Oy. Furthermore, the spent sorbent could be regenerated by heating to 350°C, and the highly concentrated elemental mercury released could be facilely recycled. Therefore, a much greener process for mercury capture and recovery could be anticipated based on this regenerable sorbent.

  5. Modeling Selective Intergranular Oxidation of Binary Alloys

    SciTech Connect

    Xu, Zhijie; Li, Dongsheng; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-01-07

    Intergranular attack of alloys under hydrothermal conditions is a complex problem that depends on metal and oxygen transport kinetics via solid-state and channel-like pathways to an advancing oxidation front. Experiments reveal very different rates of intergranular attack and minor element depletion distances ahead of the oxidation front for nickel-based binary alloys depending on the minor element. For example, a significant Cr depletion up to 9 µm ahead of grain boundary crack tips were documented for Ni-5Cr binary alloy, in contrast to relatively moderate Al depletion for Ni-5Al (~100s of nm). We present a mathematical kinetics model that adapts Wagner’s model for thick film growth to intergranular attack of binary alloys. The transport coefficients of elements O, Ni, Cr, and Al in bulk alloys and along grain boundaries were estimated from the literature. For planar surface oxidation, a critical concentration of the minor element can be determined from the model where the oxide of minor element becomes dominant over the major element. This generic model for simple grain boundary oxidation can predict oxidation penetration velocities and minor element depletion distances ahead of the advancing front that are comparable to experimental data. The significant distance of depletion of Cr in Ni-5Cr in contrast to the localized Al depletion in Ni-5Al can be explained by the model due to the combination of the relatively faster diffusion of Cr along the grain boundary and slower diffusion in bulk grains, relative to Al.

  6. An Acidity Scale for Binary Oxides.

    ERIC Educational Resources Information Center

    Smith, Derek W.

    1987-01-01

    Discusses the classification of binary oxides as acidic, basic, or amphoteric. Demonstrates how a numerical scale for acidity/basicity of binary oxides can be constructed using thermochemical data for oxoacid salts. Presents the calculations derived from the data that provide the numeric scale values. (TW)

  7. Exploration of mid-temperature alkali-metal-ion extraction route using PTFE (AEP): transformation of α-NaFeO2-type layered oxides into rutile-type binary oxides.

    PubMed

    Ozawa, Tadashi C; Sasaki, Takayoshi

    2012-07-02

    Alkali-metal-ion extraction reactions using poly(tetrafluoroethylene) (PTFE; AEP reactions) were performed on two kinds of α-NaFeO(2)-type layered compounds: Na(0.68)(Li(0.68/3)Ti(1-0.68/3))O(2) and K(0.70)(Li(0.70/3)Sn(1-0.70/3))O(2). At 400 °C in flowing argon, these layered compounds were reacted with PTFE. By these reactions, alkali-metal ions in the layered compounds were successfully extracted, and TiO(2) and SnO(2) with rutile-type structure were formed. The structural similarity between the alkali-metal-ion-extracted layered compounds and the binary metal oxide products in these unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomic pair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ions from layered compounds, and AEP reaction is not limited to the previously reported γ-FeOOH-type layered titania K(0.8)(Li(0.27)Ti(1.73))O(4), but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, it was clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult to synthesize by other reactions.

  8. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites

    PubMed Central

    Ko, Kyung-Seok; Ha, Kyoochul; Kong, In Chul

    2015-01-01

    The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co3O4 and TiO2) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co3O4 > NiO > TiO2. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%–92% and 78%–82% of the control (p-value 0.0010) based on ATP content and 78%–95% and 72%–94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement. PMID:26610489

  9. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  10. Facile synthesis of multi-shell structured binary metal oxide powders with a Ni/Co mole ratio of 1:2 for Li-Ion batteries

    NASA Astrophysics Data System (ADS)

    Choi, Seung Ho; Park, Sun Kyu; Lee, Jung-Kul; Kang, Yun Chan

    2015-06-01

    Multi-shell structured binary transition metal oxide powders with a Ni/Co mole ratio of 1:2 are prepared by a simple spray drying process. Precursor powder particles prepared by spray drying from a spray solution of citric acid and ethylene glycol have completely spherical shape, fine size, and a narrow size distribution. The precursor powders turn into multi-shell powders after a post heat-treatment at temperatures between 250 and 800 °C. The multi-shell structured powders are formed by repeated combustion and contraction processes. The multi-shell powders have mixed crystal structures of Ni1-xCo2O4-x and NiO phases regardless of the post-treatment temperature. The reversible capacities of the powders post-treated at 250, 400, 600, and 800 °C after 100 cycles are 584, 913, 808, and 481 mA h g-1, respectively. The low charge transfer resistance and high lithium ion diffusion rate of the multi-shell powders post-treated at 400 °C with optimum grain size result in superior electrochemical properties even at high current densities.

  11. Study of the Energy Characteristics of Metallized Mixed Compositions Based on a Binary Oxidizer at Increased Pressures

    NASA Astrophysics Data System (ADS)

    Gorbenko, T. I.; Gorbenko, M. V.; Dyundin, E. O.; Zolotorev, N. N.

    2014-09-01

    Results of a thermodynamic calculation of the energy characteristics for mixed compositions containing aluminum powder are presented. The influence of the aluminum content in the mixed compositions on the adiabatic combustion temperature, specific impulse, and composition of the combustion products is considered. Results of an experimental study of combustion of metallized mixed compositions in the pressure range from 0.1 to 6 MPa are presented. The effect of the aluminum powder dispersity and the relative content of the components of the mixed composition on the pressure dependence of the burning rate is demonstrated.

  12. Stochastic learning in oxide binary synaptic device for neuromorphic computing.

    PubMed

    Yu, Shimeng; Gao, Bin; Fang, Zheng; Yu, Hongyu; Kang, Jinfeng; Wong, H-S Philip

    2013-01-01

    Hardware implementation of neuromorphic computing is attractive as a computing paradigm beyond the conventional digital computing. In this work, we show that the SET (off-to-on) transition of metal oxide resistive switching memory becomes probabilistic under a weak programming condition. The switching variability of the binary synaptic device implements a stochastic learning rule. Such stochastic SET transition was statistically measured and modeled for a simulation of a winner-take-all network for competitive learning. The simulation illustrates that with such stochastic learning, the orientation classification function of input patterns can be effectively realized. The system performance metrics were compared between the conventional approach using the analog synapse and the approach in this work that employs the binary synapse utilizing the stochastic learning. The feasibility of using binary synapse in the neurormorphic computing may relax the constraints to engineer continuous multilevel intermediate states and widens the material choice for the synaptic device design.

  13. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  14. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  15. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1994-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  16. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1997-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  17. Oxidation Behavior of Binary Niobium Alloys

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A.; Corey, James L.

    1960-01-01

    This investigation concludes a study to determine the effects of up to 25 atomic percent of 55 alloying additions on the oxidation characteristics of niobium. The alloys were evaluated by oxidizing in an air atmosphere for 4 hours at 1000 C and 2 hours at 1200 C. Titanium and chromium improved oxidation resistance at both evaluation conditions. Vanadium and aluminum improved oxidation resistance at 1000 C, even though the V scale tended to liquefy and the Al specimens became brittle and the scale powdery. Copper, cobalt, iron, and iridium improved oxidation resistance at 1200 C. Other investigations report tungsten and molybdenum are protective up to about 1000 C, and tantalum at 1100 C. The most important factor influencing the rate of oxidation was the ion size of the alloy additions. Ions slightly smaller than the Nb(5+) ion are soluble in the oxide lattice and tend to lower the compressive stresses in the bulk scale that lead to cracking. The solubility of the alloying addition also depends on the valence to some extent. All of the elements mentioned that improve the oxidation resistance of Nb fit this size criterion with the possible exception of Al, whose extremely small size in large concentrations would probably lead to the formation of a powdery scale. Maintenance of a crack-free bulk scale for as long as possible may contribute to the formation of a dark subscale that ultimately is rate- controlling in the oxidation process. The platinum-group metals, especially Ir, appear to protect by entrapment of the finely dispersed alloying element by the incoming Nb2O5 metal-oxide interface. This inert metallic Ir when alloyed in a sufficient amount with Yb appears to give a ductile phase dispersed in the brittle oxide. This scale would then flow more easily to relieve the large compressive stresses to delay cracking. Complex oxide formation (which both Ti and Zr tend to initiate) and valence effects, which probably change the vacancy concentration in the scale

  18. Extracting metals directly from metal oxides

    DOEpatents

    Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

    1997-01-01

    A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones, halogenated .beta.-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process.

  19. Extracting metals directly from metal oxides

    DOEpatents

    Wai, C.M.; Smart, N.G.; Phelps, C.

    1997-02-25

    A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of {beta}-diketones, halogenated {beta}-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs.

  20. New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems

    NASA Astrophysics Data System (ADS)

    Bluhm, P.; Jones, M. I.; Vanzi, L.; Soto, M. G.; Vos, J.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Olivares, F.; Mennickent, R. E.; Vučković, M.; Rojo, P.; Melo, C. H. F.

    2016-10-01

    We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions. The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between ~97-1600 days and eccentricities of between ~0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a different formation mechanism than planets. This result is confirmed by recent works showing that extrasolar planets orbiting giants are more frequent around metal-rich stars. Finally, we investigate the eccentricity as a function of the orbital period. We analyzed a total of 130 spectroscopic binaries, including those presented here and systems from the literature. We find that most of the binary stars with periods ≲30 days have circular orbits, while at longer orbital periods we observe a wide spread in their eccentricities. Based on observations collected at La Silla - Paranal Observatory under programs IDs IDs 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345, 096.A-9020 and through the Chilean Telescope Time under programs IDs CN2012A-73, CN2012B-47, CN2013A-111, CN2013B-51, CN2014A-52 and CN2015A-48.

  1. Novel Photocatalytic Metal Oxides

    SciTech Connect

    Smith, Robert W.; Mei, Wai-Ning; Sabirianov, Renat; Wang, Lu

    2012-08-31

    The principal short-term objective is to develop improved solid-state photocatalysts for the decomposition of water into hydrogen gas using ultraviolet and visible solar radiation. We will pursue our objective by modeling candidate metal oxides through computer simulations followed by synthesis of promising candidates. We will characterize samples through standard experimental techniques. The long-term objective is to provide a more efficient source of hydrogen gas for fixed-site hydrogen fuel cells, particularly for energy users in remote locations.

  2. Transparent metal oxide nanowire transistors

    NASA Astrophysics Data System (ADS)

    Chen, Di; Liu, Zhe; Liang, Bo; Wang, Xianfu; Shen, Guozhen

    2012-05-01

    With the features of high mobility, a high electric on/off ratio and excellent transparency, metal oxide nanowires are excellent candidates for transparent thin-film transistors, which is one of the key technologies to realize transparent electronics. This article provides a comprehensive review of the state-of-the-art research activities that focus on transparent metal oxide nanowire transistors. It begins with the brief introduction to the synthetic methods for high quality metal oxide nanowires, and the typical nanowire transfer and printing techniques with emphasis on the simple contact printing methodology. High performance transparent transistors built on both single nanowires and nanowire thin films are then highlighted. The final section deals with the applications of transparent metal oxide nanowire transistors in the field of transparent displays and concludes with an outlook on the current perspectives and future directions of transparent metal oxide nanowire transistors.

  3. Transparent metal oxide nanowire transistors.

    PubMed

    Chen, Di; Liu, Zhe; Liang, Bo; Wang, Xianfu; Shen, Guozhen

    2012-05-21

    With the features of high mobility, a high electric on/off ratio and excellent transparency, metal oxide nanowires are excellent candidates for transparent thin-film transistors, which is one of the key technologies to realize transparent electronics. This article provides a comprehensive review of the state-of-the-art research activities that focus on transparent metal oxide nanowire transistors. It begins with the brief introduction to the synthetic methods for high quality metal oxide nanowires, and the typical nanowire transfer and printing techniques with emphasis on the simple contact printing methodology. High performance transparent transistors built on both single nanowires and nanowire thin films are then highlighted. The final section deals with the applications of transparent metal oxide nanowire transistors in the field of transparent displays and concludes with an outlook on the current perspectives and future directions of transparent metal oxide nanowire transistors.

  4. Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

    DOEpatents

    Quinby, Thomas C.

    1978-01-01

    Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution leaving a molten urea solution containing the metal values. The molten urea solution is heated to above about 180.degree. C. whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles.

  5. Platinum nanoparticles decorated robust binary transition metal nitride-carbon nanotubes hybrid as an efficient electrocatalyst for the methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Zhan, Guohe; Fu, Zhenggao; Sun, Dalei; Pan, Zhanchang; Xiao, Chumin; Wu, Shoukun; Chen, Chun; Hu, Guanghui; Wei, Zhigang

    2016-09-01

    Titanium cobalt nitride (TiCoN)-CNTs hybrid support is prepared by a facile and efficient method, including a one-pot solvothermal process followed by a nitriding process, and this hybrid support is further decorated with Pt nanoparticles to catalyze the oxidation of methanol. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. Notably, Pt/CNTs@TiCoN catalyst exhibits a much higher mass activity and durability than that of the conventional Pt/C (JM) for methanol oxidation. The experimental data indicates that the CNTs@TiCoN hybrid support combines the merits of the CNTs's high conductivity and the superb corrosion resistance of external TiCoN coating.

  6. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  7. A red metallic oxide photocatalyst

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoxiang; Randorn, Chamnan; Efstathiou, Paraskevi; Irvine, John T. S.

    2012-07-01

    Light absorption across the bandgap in semiconductors is exploited in many important applications such as photovoltaics, light emitting diodes and photocatalytic conversion. Metals differ from semiconductors in that there is no energy gap separating occupied and unoccupied levels; however, it is still possible to excite electrons between bands. This is evidenced by materials with metallic properties that are also strongly coloured. An important question is whether such coloured metals could be used in light harvesting or similar applications. The high conductivity of a metal would preclude sufficient electric field being available to separate photocarriers; however, the high carrier mobility in a metal might also facilitate kinetic charge separation. Here we clearly demonstrate for the first time the use of a red metallic oxide, Sr1-xNbO3 as an effective photocatalyst. The material has been used under visible light to photocatalyse the oxidation of methylene blue and both the oxidation and reduction of water assisted by appropriate sacrificial elements.

  8. Metal oxide nanostructures with hierarchical morphology

    SciTech Connect

    Ren, Zhifeng; Lao, Jing Yu; Banerjee, Debasish

    2007-11-13

    The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

  9. METAL OXIDE NANOPARTICLES

    SciTech Connect

    FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

    2007-10-01

    This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

  10. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  11. Mesoporous metal oxide graphene nanocomposite materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  12. SINTERING METAL OXIDES

    DOEpatents

    Roake, W.E.

    1960-09-13

    A process is given for producing uranium dioxide material of great density by preparing a compacted mixture of uranium dioxide and from 1 to 3 wt.% of calcium hydride, heating the mixture to at least 675 deg C for decomposition of the hydride and then for sintering, preferably in a vacuum, at from 1550 to 2000 deg C. Calcium metal is formed, some uranium is reduced by the calcium to the metal and a product of high density is obtained.

  13. Methods for synthesizing metal oxide nanowires

    DOEpatents

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  14. Lithium metal reduction of plutonium oxide to produce plutonium metal

    DOEpatents

    Coops, Melvin S.

    1992-01-01

    A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used as a solvent metal to improve thermodynamics of the reduction reaction at lower temperatures. Lithium metal reduction enables plutonium oxide reduction without the production of huge quantities of CaO--CaCl.sub.2 residues normally produced in conventional direct oxide reduction processes.

  15. Method for plating with metal oxides

    SciTech Connect

    Silver, Gary L.; Martin, Frank S.

    1994-08-23

    A method of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate.

  16. Method for plating with metal oxides

    SciTech Connect

    Silver, G.L.; Martin, F.S.

    1994-08-23

    A method is disclosed of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate. 1 fig.

  17. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    DOEpatents

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  18. Electrotransport in binary iron-based metal melts

    NASA Astrophysics Data System (ADS)

    Tekuchev, V. V.; Kalinkin, D. P.; Ivanova, I. V.

    2016-12-01

    The mobility of ions in binary iron-based liquid metal systems is calculated for the first time, based on studies on the specific resistance and self-diffusion coefficient in a wide range of concentrations. It is established that iron ions move toward the anode in Fe-V and Fe-Mo systems, and toward the cathode in Fe-W and Fe-Pt systems; i.e., there is inversion of electrotransport for iron ions. When the concentration of a component is reduced, the mobility of its ions grows in modulus.

  19. Application of Fe-Cu binary oxide nanoparticles for the removal of hexavalent chromium from aqueous solution.

    PubMed

    Khan, Saif Ullah; Zaidi, Rumman; Hassan, Saeikh Z; Farooqi, I H; Azam, Ameer

    2016-01-01

    The adsorption process has been used as an effective technique for the removal of metal ions from aqueous solutions. Groundwater remediation by nanoparticles has received interest in recent years. In the present study, a binary metal oxide of Fe-Cu was prepared and used for the removal of hexavalent chromium from aqueous solution. Batch experiments were performed to investigate the effects of initial Cr (VI) concentration, dose of adsorbent, and pH of solution on the removal efficiency of Cr (VI). The prepared nanostructured Fe-Cu binary oxides were able to reduce the concentration of Cr (VI) in aqueous solution. Binary metal oxides nanoparticle exhibited an outstanding ability to remove Cr (VI) due to high surface area, low particle size, and high inherent activity. The percentage removal efficiency of Cr (VI) increased with nanoparticles doses (0.1 g L(-1)-2.5 g L(-1)), whereas it decreased with initial Cr (VI) concentration (1 mg L(-1)-25 mg L(-1)) and with pH (3-9). The Freundlich model was found to be the better fit for adsorption isotherm. The prepared nanomaterial was characterized using powder X-ray diffraction, scanning electron microscopy (SEM), and ultraviolet (UV)-visible spectroscopy. It showed that the Fe-Cu binary oxides were formed in single phase. SEM micrograph showed aggregates with many nano-sized particles. UV-visible spectroscopy showed quantum confinement effect.

  20. Self-assembly of metal nanostructures on binary alloy surfaces.

    PubMed

    Duguet, T; Han, Yong; Yuen, Chad; Jing, Dapeng; Unal, Barış; Evans, J W; Thiel, P A

    2011-01-18

    Deposition of metals on binary alloy surfaces offers new possibilities for guiding the formation of functional metal nanostructures. This idea is explored with scanning tunneling microscopy studies and atomistic-level analysis and modeling of nonequilibrium island formation. For Au/NiAl(110), complex monolayer structures are found and compared with the simple fcc(110) bilayer structure recently observed for Ag/NiAl(110). We also consider a more complex codeposition system, (Ni + Al)/NiAl(110), which offers the opportunity for fundamental studies of self-growth of alloys including deviations for equilibrium ordering. A general multisite lattice-gas model framework enables analysis of structure selection and morphological evolution in these systems.

  1. Molecular Level Coating for Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); Saint Clair, Terry L. (Inventor)

    2000-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar aprotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper, making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  2. Molecular Level Coating of Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); St.Clair, Terry L. (Inventor)

    2002-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar osmotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing, synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper. making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  3. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  4. Graphene-supported metal oxide monolith

    DOEpatents

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

    2017-01-10

    A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

  5. Retrospective hit-deconvolution of mixed metal oxides: spotting structure-property-relationships in gas phase oxidation catalysis through high throughput experimentation.

    PubMed

    Schunk, Stephan Andreas; Sundermann, Andreas; Hibst, Hartmut

    2007-01-01

    Complex multi-element lead structures of mixed metal oxides that may be identified as hits during high throughput experimentation (HTE) campaigns, can be deconvoluted retrospectively on the basis of simple binary and ternary oxides as illustrated in the current example of a hit found in an ammoxidation reaction. On the basis of the performance of the simple binary and ternary mixed metal oxides structure property relationships can be established, that give insight into the roles of the different components of the complex mixed metal oxides and may also help in establishing a reaction mechanism and converting the hit into a development candidate.

  6. Superiority of DFT+U with non-linear core correction for open-shell binary rare-earth metal oxides: a case study of native point defects in cerium oxides

    NASA Astrophysics Data System (ADS)

    Huang, Bolong

    2014-09-01

    We successfully proposed a newly corrected density functional theory plus Hubbard U parameter (DFT + U) based on partial core correction on the orbitals within norm-conserving lanthanide atomic pseudopotentials. A related and comprehensive investigation of native point defects in cerium oxides has also been performed as an examine by practice.

  7. Method of recovering volatile metals from material containing metal oxides

    SciTech Connect

    Santen, S.

    1984-12-18

    A method of reducing and recovering volatile metal from metal oxides comprising the steps of injecting metal oxide-containing material into a shaft reactor, simultaneously injecting reducing agent into said reactor, continuously maintaining said reactor substantially filled with coke, supplying thermal energy to the reactor, preferably by means of a plasma burner, such that at least some of the metal oxides are reduced to metal and melted or volatilized depending upon whether the metal is volatile. The melted metal is removed from the bottom of the reactor while the volatilized metal is permitted to flow upwardly through the shaft reactor in the form of metal vapor together with a gas flow. The coke in the shaft reactor through which the volatilized metal passes is maintained at a temperature in excess of 1000/sup 0/ C., thus screening the upper portion of the shaft reactor and the reactor top by means of the coke so as to prevent condensation of the volatilized metal.

  8. Making A Noble-Metal-On-Metal-Oxide Catalyst

    NASA Technical Reports Server (NTRS)

    Miller, Irvin M.; Davis, Patricia P.; Upchurch, Billy T.

    1989-01-01

    Catalyst exhibits superior performance in oxidation of CO in CO2 lasers. Two-step process developed for preparing platinum- or palladium-on-tin-oxide catalyst for recombination of CO and O2, decomposition products that occur in high-voltage discharge region of closed-cycle CO2 laser. Process also applicable to other noble-metal/metal-oxide combinations.

  9. Preparing oxidizer coated metal fuel particles

    NASA Technical Reports Server (NTRS)

    Shafer, J. I.; Simmons, G. M. (Inventor)

    1974-01-01

    A solid propellant composition of improved efficiency is described which includes an oxidizer containing ammonium perchlorate, and a powered metal fuel, preferably aluminum or beryllium, in the form of a composite. The metal fuel is contained in the crystalline lattice framework of the oxidizer, as well as within the oxidizer particles, and is disposed in the interstices between the oxidizer particles of the composition. The propellant composition is produced by a process comprising the crystallization of ammonium perchlorate in water, in the presence of finely divided aluminum or beryllium. A suitable binder is incorporated in the propellant composition to bind the individual particles of metal with the particles of oxidizer containing occluded metal.

  10. Ammonia release method for depositing metal oxides

    DOEpatents

    Silver, G.L.; Martin, F.S.

    1994-12-13

    A method is described for depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates. 1 figure.

  11. Ammonia release method for depositing metal oxides

    DOEpatents

    Silver, Gary L.; Martin, Frank S.

    1994-12-13

    A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

  12. Method for producing metal oxide nanoparticles

    DOEpatents

    Phillips, Jonathan; Mendoza, Daniel; Chen, Chun-Ku

    2008-04-15

    Method for producing metal oxide nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone into metal vapor. The metal vapor is directed away from the hot zone and into the cooler plasma afterglow where it oxidizes, cools and condenses to form solid metal oxide nanoparticles.

  13. Nanostructured transition metal oxides useful for water oxidation catalysis

    DOEpatents

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  14. Metal oxide-based transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Gillispie, Meagen Anne

    Transparent conducting oxides (TCOs) are important materials widely used for transparent contacts in flat panel displays, light emitting diodes, and solar cells. While Sn-doped In2O3 (ITO) continues to be the TCO of choice, the increasing cost of raw In has resulted in an increasing interest in developing In-free alternatives to ITO. In this work, two metal oxide systems were investigated for their viability as In-free TCO materials. First, Nb- or Ta-doped anatase TiO2 was selected due to the recent reports of high conductivity in pulse laser deposited (PLD) films. Thin films doped with either 15 mol% Nb or 20 mol% Ta were deposited on glass and SrTiO3 (STO) substrates using RF magnetron sputtering techniques. In all cases, maximum conductivity was achieved when the films crystallized in the anatase structure of TiO2. Films sputtered on STO possessed similar electrical and optical properties as PLD films on STO, yet at a much lower deposition temperature while films deposited on glass had much lower conductivity, due to dramatically reduced mobility. Two-dimensional x-ray diffraction analysis showed that doped TiO2 films sputter deposited on STO were biaxially textured along the (004) direction. This texturing was not observed in films deposited on glass, which were composed of randomly-oriented crystalline anatase. Biaxial texturing in the film helps to reduce grain boundary resistance, thereby increasing carrier mobility and further enhancing conductivity. The Cu-based delafossite system (CuBO2, B is a 3+ metal cation) was selected as the second TCO material system due to its natural p-type conductivity, a rarity among existing TCOs. Study of this system was two-pronged: (1) application of codoping techniques to achieve bipolar conductivity; and (2) investigate stability of mixed B cation delafossites. CuAlO2 and CuGaO2 were both codoped with varying ratios of donors and acceptors in an attempt to achieve bipolar conductivity. Very little change in the electrical

  15. Oxidation and reduction in irradiated binary crystals of resorcinol and progesterone

    SciTech Connect

    Box, H.C.; Budzinski, E.E.

    1985-12-01

    The binary single crystals of resorcinol and progesterone were x-irradiated at 4.2 K. The semiquinone of resorcinol was generated by radiation induced oxidation. The oxidation and reduction products were identified from ESR and ENDOR measurements. (AIP)

  16. Metal and metal oxide nanoparticle synthesis from metal organic frameworks (MOFs): finding the border of metal and metal oxides.

    PubMed

    Das, Raja; Pachfule, Pradip; Banerjee, Rahul; Poddar, Pankaj

    2012-01-21

    Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs.

  17. Metal oxide composite dosimeter method and material

    DOEpatents

    Miller, Steven D.

    1998-01-01

    The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

  18. The oxidation of metals and alloys

    NASA Technical Reports Server (NTRS)

    Scheil, Erich

    1952-01-01

    This paper reviews the various types of oxidation processes occurring with pure metals and gives explanations for the varying time-temperature-oxidation rate relations that exist for copper, tungsten, zinc, cadmium, and tantalum. The effect of shape and crystal structure on oxidation is discussed. Principles derived are applied to the oxidation of alloys.

  19. Metal oxides for optoelectronic applications.

    PubMed

    Yu, Xinge; Marks, Tobin J; Facchetti, Antonio

    2016-04-01

    Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

  20. Metal oxides for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Yu, Xinge; Marks, Tobin J.; Facchetti, Antonio

    2016-04-01

    Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

  1. Reduction of Metal Oxide to Metal using Ionic Liquids

    SciTech Connect

    Dr. Ramana Reddy

    2012-04-12

    A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode

  2. In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation

    PubMed Central

    2015-01-01

    The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt–nickel–iron oxides grown directly on the three-dimensional carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm–2, small Tafel slope of 37.6 mV dec–1, and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications. PMID:27162978

  3. High temperature, oxidation resistant noble metal-Al alloy thermocouple

    NASA Technical Reports Server (NTRS)

    Smialek, James L. (Inventor); Gedwill, Michael G. (Inventor)

    1994-01-01

    A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

  4. Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths.

    PubMed

    Soloviev, Sergiy O; Kapran, Andriy Y; Kurylets, Yaroslava P

    2015-02-01

    Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3≫NO2>H2O>NO>O2>CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem.

  5. Nanocomposite of graphene and metal oxide materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

    2013-10-15

    Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

  6. Nanocomposite of graphene and metal oxide materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

    2015-06-30

    Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

  7. Nanocomposite of graphene and metal oxide materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

    2012-09-04

    Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

  8. Photodegradation of chlorofluorocarbon alternatives on metal oxide

    SciTech Connect

    Tanaka, K.; Hisanaga, T. )

    1994-05-01

    HCFC and HFC were photodegraded on metal oxides. Degradation rate on several metal oxides was in the order: TiO[sub 2] > ZnO > Fe[sub 2]O[sub 3] > kaolin [ge] SiO[sub 2] [ge] Al[sub 2]O[sub 3]. Principal degradation products were CO[sub 2], Cl[sup [minus

  9. Adsorption of divalent metals to metal oxide nanoparicles: Competitive and temperature effects

    NASA Astrophysics Data System (ADS)

    Grover, Valerie Ann

    The presence of metals in natural waters is becoming a critical environmental and public health concern. Emerging nanotechnology and the use of metal oxide nanoparticles has been identified as a potential remediation technique in removing metals from water. However, practical applications are still being explored to determine how to apply their unique chemical and physical properties for full scale remediation projects. This thesis investigates the sorption properties of Cd(II), Cu(II), Pb(II) and Zn(II) to hematite (alpha-Fe2O3) and titanium dioxide (TiO2) nanoparticles in single- and binary-adsorbate systems. Competitive sorption was evaluated in 1L batch binary-metal systems with 0.05g/L nano-hematite at pH 8.0 and pH 6.0. Results indicate that the presence of a secondary metal can affect the sorption process depending upon the molar ratios, such as increased or reduced adsorption. Thermodynamic properties were also studied in order to better understand the effects of temperature on equilibrium and kinetic adsorption capabilities. Understanding the thermodynamic properties can also give insight to determine if the sorption process is a physical, chemical or ion exchange reaction. Thermodynamic parameters such as enthalpy (DeltaH), entropy (DeltaS), and Gibbs free energy (DeltaG) were evaluated as a function of temperature, pH, and metal concentration. Results indicate that Pb(II) and Cu(II) adsorption to nano-hematite was an endothermic and physical adsorption process, while Zn(II) and Cd(II) adsorption was dependent upon the adsorbed concentration evaluated. However, metal adsorptions to nano-titanium dioxide were all found to be endothermic and physical adsorption processes; the spontaneity of metal adsorption was temperature dependent for both metal oxide nanoparticles.

  10. Metallicity dependence of Type Ib/c and IIb supernova progenitors in binary systems

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-CHul

    2015-08-01

    Type Ib/c supernovae (SNe Ib/c) are characterized by the lack of prominent hydrogen lines in the spectra, implying that their progenitors have lost most of their hydrogen envelopes by the time of the iron core collapse. Binary interactions provide an important evolutionary chanel for SNe Ib/c, and recent observations indicate that the inferred ejecta masses of SNe Ibc are more consistent with the prediction of the binary scenario than that of the single star scenario that invokes mass loss as the key evolutionary factor for SNe Ib/c progenitors. So far, theoretical predictions on the detailed properties of SNe Ib/c progenitors in binary systems have been made mostly with models using solar metallicity. However, unlike the single star scenario, where SNe Ib/c are expected only for sufficiently high metallicity, hydrogen-deficent SN progenitors can be produced via binary interactions at any metallicity. In this talk, I will discuss theoretical predictions on the metallicity dependence of the SNe Ib/c progenitor structure, based on evolutionary models of massive binary stars. Sepefically, I will address how the ejecta masses of SNe Ib and Ic and the ratio of SN Ib/c to SN IIb as well as SN Ib to SN Ic would systematically change as a function of metallicity, and which new types of SNe are expected in binary systems at low metallicity.

  11. Surface protected lithium-metal-oxide electrodes

    DOEpatents

    Thackeray, Michael M.; Kang, Sun-Ho

    2016-04-05

    A lithium-metal-oxide positive electrode having a layered or spinel structure for a non-aqueous lithium electrochemical cell and battery is disclosed comprising electrode particles that are protected at the surface from undesirable effects, such as electrolyte oxidation, oxygen loss or dissolution by one or more lithium-metal-polyanionic compounds, such as a lithium-metal-phosphate or a lithium-metal-silicate material that can act as a solid electrolyte at or above the operating potential of the lithium-metal-oxide electrode. The surface protection significantly enhances the surface stability, rate capability and cycling stability of the lithium-metal-oxide electrodes, particularly when charged to high potentials.

  12. Three-Electrode Metal Oxide Reduction Cell

    DOEpatents

    Dees, Dennis W.; Ackerman, John P.

    2005-06-28

    A method of electrochemically reducing a metal oxide to the metal in an electrochemical cell is disclosed along with the cell. Each of the anode and cathode operate at their respective maximum reaction rates. An electrolyte and an anode at which oxygen can be evolved, and a cathode including a metal oxide to be reduced are included as is a third electrode with independent power supplies connecting the anode and the third electrode and the cathode and the third electrode.

  13. Method for making monolithic metal oxide aerogels

    DOEpatents

    Droege, M.W.; Coronado, P.R.; Hair, L.M.

    1995-03-07

    Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels. 6 figs.

  14. Method for making monolithic metal oxide aerogels

    DOEpatents

    Droege, Michael W.; Coronado, Paul R.; Hair, Lucy M.

    1995-01-01

    Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels.

  15. Three-electrode metal oxide reduction cell

    DOEpatents

    Dees, Dennis W.; Ackerman, John P.

    2008-08-12

    A method of electrochemically reducing a metal oxide to the metal in an electrochemical cell is disclosed along with the cell. Each of the anode and cathode operate at their respective maximum reaction rates. An electrolyte and an anode at which oxygen can be evolved, and a cathode including a metal oxide to be reduced are included as is a third electrode with independent power supplies connecting the anode and the third electrode and the cathode and the third electrode.

  16. Direct electrochemical reduction of metal-oxides

    DOEpatents

    Redey, Laszlo I.; Gourishankar, Karthick

    2003-01-01

    A method of controlling the direct electrolytic reduction of a metal oxide or mixtures of metal oxides to the corresponding metal or metals. A non-consumable anode and a cathode and a salt electrolyte with a first reference electrode near the non-consumable anode and a second reference electrode near the cathode are used. Oxygen gas is produced and removed from the cell. The anode potential is compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and the cathode potential is compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.

  17. Methods of producing adsorption media including a metal oxide

    DOEpatents

    Mann, Nicholas R; Tranter, Troy J

    2014-03-04

    Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

  18. Metal Oxide Solubility and Molten Salt Corrosion.

    DTIC Science & Technology

    1982-03-29

    METAL OXIDE SOLUBILITY AND MOLTEN SALT CORROSION.(U) MAR 82 K H STERN UNCLASSI E DL R L-4772NL EL .2. MICROCOPY RESOLUTION TEST CHART NATIONAL BURALU...METAL OXIDE SOLUBILITY AND MOLTEN SALT Interim report on a continuing CORROSION NRL problem. S. PERFORMING a4. REPORT NUMlER 7. AuTtwORr) S. CONTRACT OR...EQUILIBRIA AND OXIDE SOLUTION RELATIONS IN MOLTEN SALTS ............................................. 2 IV. METHODS FOR DETERMINING SOLUBILITIES

  19. Metal Oxide Reduction Linked to Anaerobic Methane Oxidation.

    PubMed

    Oni, Oluwatobi E; Friedrich, Michael W

    2017-02-01

    Microbial methanotrophy is important in mitigating methane emissions to the atmosphere. Geochemical evidence suggests the occurrence of anaerobic methane oxidation with metal oxides in natural environments. A study has now identified, for the first time, novel freshwater archaea of the order Methanosarcinales that can oxidize methane with Fe(III) and Mn(IV) minerals as electron acceptors.

  20. Impact of interactions between metal oxides to oxidative reactivity of manganese dioxide.

    PubMed

    Taujale, Saru; Zhang, Huichun

    2012-03-06

    Manganese oxides typically exist as mixtures with other metal oxides in soil-water environments; however, information is only available on their redox activity as single oxides. To bridge this gap, we examined three binary oxide mixtures containing MnO(2) and a secondary metal oxide (Al(2)O(3), SiO(2) or TiO(2)). The goal was to understand how these secondary oxides affect the oxidative reactivity of MnO(2). SEM images suggest significant heteroaggregation between Al(2)O(3) and MnO(2) and to a lesser extent between SiO(2)/TiO(2) and MnO(2). Using triclosan and chlorophene as probe compounds, pseudofirst-order kinetic results showed that Al(2)O(3) had the strongest inhibitory effect on MnO(2) reactivity, followed by SiO(2) and then TiO(2). Al(3+) ion or soluble SiO(2) had comparable inhibitory effects as Al(2)O(3) or SiO(2), indicating the dominant inhibitory mechanism was surface complexation/precipitation of Al/Si species on MnO(2) surfaces. TiO(2) inhibited MnO(2) reactivity only when a limited amount of triclosan was present. Due to strong adsorption and slow desorption of triclosan by TiO(2), precursor-complex formation between triclosan and MnO(2) was much slower and likely became the new rate-limiting step (as opposed to electron transfer in all other cases). These mechanisms can also explain the observed adsorption behavior of triclosan by the binary oxide mixtures and single oxides.

  1. Amorphorized tantalum-nickel binary films for metal gate applications

    SciTech Connect

    Ouyang, Jiaomin; Wongpiya, Ranida; Clemens, Bruce M.; Deal, Michael D.; Nishi, Yoshio

    2015-04-13

    Amorphous metal gates have the potential to eliminate the work function variation due to grain orientation for poly-crystalline metal gate materials, which is a leading contributor to threshold voltage variation for small transistors. Structural and electrical properties of TaNi alloys using co-sputtering with different compositions and multilayer structures with different thicknesses are investigated in this work. It is found that TaNi films are amorphous for a wide range of compositions as deposited, and the films stay amorphous after annealing at 400 °C in RTA for 1 min and up to at least 700 °C depending on the composition. The amorphous films eventually crystallize into Ni, Ta, and TaNi{sub 3} phases at high enough temperature. For multilayer Ta/Ni structures, samples with individual layer thickness of 0.12 nm and 1.2 nm are amorphous as deposited due to intermixing during deposition, and stay amorphous until annealed at 500 °C. The resistivity of the films as-deposited are around 200 μΩ·cm. The work function of the alloy is fixed at close to the Ta work function of 4.6 eV for a wide range of compositions. This is attributed to the segregation of Ta at the metal-oxide interface, which is confirmed by XPS depth profile. Overall, the excellent thermal stability and low resistivity makes this alloy system a promising candidate for eliminating work function variation for gate last applications, as compared to crystalline Ta or TiN gates.

  2. Activity and diffusion of metals in binary aluminum alloys

    SciTech Connect

    Jao, C. S.

    1980-12-01

    To determine the activity of zinc in Zn-Al alloys, the electromotive force (emf) of the cell: Zn/ZnCl/sub 2/-KC1 (eut)/Zn,Al was measured at temperatures between 569.5 K (296.5C) and 649.5 K (376.5C). The applicability of a two-suffix Margules equation was demonstrated, in good agreement with theoretical expectations. The diffusion coefficient of Zn in Al determined from a planar diffusion model for the experimental data was about 3 x 10/sup -10/ cm/sup 2//sec to 2 x 10/sup -9/ cm/sup 2//sec in the range of temperature studied. This is higher than that found in the literature. The most plausible reason appears to be the high alumina concentration in the working electrode because of partial oxidation. Oxidation of the alloying metals was the primary cause of poor alloying between calcium/or zinc and aluminum, thereby frustrating similar measurements at a Ca-Al/or Zn-Al alloy. The literature on the activity of calcium and zinc is aluminum is reviewed.

  3. Au/metal oxides for low temperature CO oxidation

    SciTech Connect

    Srinivas, G.; Wright, J.; Bai, C.S.; Cook, R.

    1996-12-31

    Oxidation of carbon monoxide is important for several operations including fuel cells and carbon dioxide lasers. Room temperature CO oxidation has been investigated on a series of Au/metal oxide catalysts at conditions typical of spacecraft atmospheres; CO = 50 ppm, CO{sub 2} = 7,000 ppm, H{sub 2}O = 40% (RH) at 25{degrees}C, balance = air, and gas hourly space velocities of 7,000-60,000 hr{sup -1}. The addition of Au increases the room temperature CO oxidation activity of the metal oxides dramatically. All the Au/metal oxides deactivate during the CO oxidation reaction, especially in the presence of CO{sub 2} in the feed. The stability of the Au/metal oxide catalysts decreases in the following order: TiO{sub 2} > Fe{sub 2}O{sub 3} > NiO > Co{sub 3}O{sub 4}. The stability appears to decrease with an increase in the basicity of the metal oxides. In situ FTIR of CO adsorption on Au/TiO{sub 2} at 25{degrees}C indicates the formation of adsorbed CO, carboxylate, and carbonate species on the catalyst surface.

  4. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.; Foran, M.T.

    1984-01-06

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150 to 260/sup 0/C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO/sub 4/ and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect. 3 tables.

  5. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

    1984-01-01

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

  6. Metallicity dependence of Type Ib/c and IIb supernova progenitors in binary systems

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Chul

    Type Ib/c supernovae (SNe Ib/c) are characterized by the lack of prominent hydrogen lines in thespectra, implying that their progenitors have lost most of their hydrogen envelopes by the time of the iron corecollapse. Binary interactions provide an important evolutionary chanel for SNe Ib/c, and recent observations indicatethat the inferred ejecta masses of SNe Ibc are more consistent with the prediction of the binary scenario than that ofthe single star scenario that invokes mass loss as the key evolutionary factor for SNe Ib/c progenitors. So far,theoretical predictions on the detailed properties of SNe Ib/c progenitors in binary systems have been made mostlywith models using solar metallicity. However, unlike the single star scenario, where SNe Ib/c are expected only forsufficiently high metallicity, hydrogen-deficent SN progenitors can be produced via binary interactions at anymetallicity. In this talk, I will discuss theoretical predictions on the metallicity dependence of the SNe Ib/c progenitorstructure, based on evolutionary models of massive binary stars. Sepefically, I will address how the ejecta masses ofSNe Ib and Ic and the ratio of SN Ib/c to SN IIb as well as SN Ib to SN Ic would systematically change as a function ofmetallicity, and which new types of SNe are expected in binary systems at low metallicity.

  7. Development of techniques for processing metal-metal oxide systems

    NASA Technical Reports Server (NTRS)

    Johnson, P. C.

    1976-01-01

    Techniques for producing model metal-metal oxide systems for the purpose of evaluating the results of processing such systems in the low-gravity environment afforded by a drop tower facility are described. Because of the lack of success in producing suitable materials samples and techniques for processing in the 3.5 seconds available, the program was discontinued.

  8. Multilevel metallization method for fabricating a metal oxide semiconductor device

    NASA Technical Reports Server (NTRS)

    Hollis, B. R., Jr.; Feltner, W. R.; Bouldin, D. L.; Routh, D. E. (Inventor)

    1978-01-01

    An improved method is described of constructing a metal oxide semiconductor device having multiple layers of metal deposited by dc magnetron sputtering at low dc voltages and low substrate temperatures. The method provides multilevel interconnections and cross over between individual circuit elements in integrated circuits without significantly reducing the reliability or seriously affecting the yield.

  9. Mesoporous Transition Metal Oxides for Supercapacitors

    PubMed Central

    Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

    2015-01-01

    Recently, transition metal oxides, such as ruthenium oxide (RuO2), manganese dioxide (MnO2), nickel oxides (NiO) and cobalt oxide (Co3O4), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors. PMID:28347088

  10. Cyclic catalytic upgrading of chemical species using metal oxide materials

    DOEpatents

    White, James H; Schutte, Erick J; Rolfe, Sara L

    2013-05-07

    Processes are disclosure which comprise alternately contacting an oxygen-carrying catalyst with a reducing substance, or a lower partial pressure of an oxidizing gas, and then with the oxidizing gas or a higher partial pressure of the oxidizing gas, whereby the catalyst is alternately reduced and then regenerated to an oxygenated state. In certain embodiments, the oxygen-carrying catalyst comprises at least one metal oxide-containing material containing a composition having the following formulas: (a) Ce.sub.xB.sub.yB'.sub.zB''O.sub..delta., wherein B=Ba, Sr, Ca, or Zr; B'=Mn, Co, and/or Fe; B''=Cu; 0.01binary metal oxides.

  11. Cyclic Catalytic Upgrading of Chemical Species Using Metal Oxide Materials

    NASA Technical Reports Server (NTRS)

    White, James H. (Inventor); Schutte, Erick J. (Inventor); Rolfe, Sara L. (Inventor)

    2013-01-01

    Processes are disclosure which comprise alternately contacting an oxygen-carrying catalyst with a reducing substance, or a lower partial pressure of an oxidizing gas, and then with the oxidizing gas or a higher partial pressure of the oxidizing gas, whereby the catalyst is alternately reduced and then regenerated to an oxygenated state. In certain embodiments, the oxygen-carrying catalyst comprises at least one metal oxide-containing material containing a composition having the following formulas: (a) Ce(sub x)B(sub y)B'(sub z)B''O(sub gamma; wherein B=Ba, Sr, Ca, or Zr; B'=Mn, Co, and/or Fe; B''=Cu; 0.01binary metal oxides.

  12. Ordered mesoporous metal oxides: synthesis and applications.

    PubMed

    Ren, Yu; Ma, Zhen; Bruce, Peter G

    2012-07-21

    Great progress has been made in the preparation and application of ordered mesoporous metal oxides during the past decade. However, the applications of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different methods for the preparation of ordered mesoporous metal oxides; we then review their applications in energy conversion and storage, catalysis, sensing, adsorption and separation. The correlations between the textural properties of ordered mesoporous metal oxides and their specific performance are highlighted in different examples, including the rate of Li intercalation, sensing, and the magnetic properties. These results demonstrate that the mesoporosity has a direct impact on the properties and potential applications of such materials. Although the scope of the current review is limited to ordered mesoporous metal oxides, we believe that the information may be useful for those working in a number of fields.

  13. Antimicrobial activity of the metals and metal oxide nanoparticles.

    PubMed

    Dizaj, Solmaz Maleki; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad Hossein; Adibkia, Khosro

    2014-11-01

    The ever increasing resistance of pathogens towards antibiotics has caused serious health problems in the recent years. It has been shown that by combining modern technologies such as nanotechnology and material science with intrinsic antimicrobial activity of the metals, novel applications for these substances could be identified. According to the reports, metal and metal oxide nanoparticles represent a group of materials which were investigated in respect to their antimicrobial effects. In the present review, we focused on the recent research works concerning antimicrobial activity of metal and metal oxide nanoparticles together with their mechanism of action. Reviewed literature indicated that the particle size was the essential parameter which determined the antimicrobial effectiveness of the metal nanoparticles. Combination therapy with the metal nanoparticles might be one of the possible strategies to overcome the current bacterial resistance to the antibacterial agents. However, further studies should be performed to minimize the toxicity of metal and metal oxide nanoparticles to apply as proper alternatives for antibiotics and disinfectants especially in biomedical applications.

  14. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    NASA Astrophysics Data System (ADS)

    Herklotz, A.; Dörr, K.; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, M. D.

    2015-03-01

    To have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Srn+1TinO3n+1 Ruddlesden-Popper phases are grown with good long-range order. This method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.

  15. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    SciTech Connect

    Herklotz, A.; Dörr, Kathrin; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, Michael D.

    2015-04-03

    In this paper, to have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr n +1Ti n O3 n +1 Ruddlesden-Popper phases are grown with good long-range order. Finally, this method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.

  16. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    DOE PAGES

    Herklotz, A.; Dörr, Kathrin; Ward, T. Z.; ...

    2015-04-03

    In this paper, to have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can bemore » utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr n +1Ti n O3 n +1 Ruddlesden-Popper phases are grown with good long-range order. Finally, this method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.« less

  17. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    SciTech Connect

    Herklotz, A.; Dörr, K.; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, M. D.

    2015-03-30

    To have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr{sub n+1}Ti{sub n}O{sub 3n+1} Ruddlesden-Popper phases are grown with good long-range order. This method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.

  18. Lithium metal oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Kim, Jeom-Soo; Johnson, Christopher S.

    2008-01-01

    An uncycled electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula Li.sub.(2+2x)/(2+x)M'.sub.2x/(2+x)M.sub.(2-2x)/(2+x)O.sub.2-.delta., in which 0.ltoreq.x<1 and .delta. is less than 0.2, and in which M is a non-lithium metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. Methods of preconditioning the electrodes are disclosed as are electrochemical cells and batteries containing the electrodes.

  19. Observational Constraints on the Age-Metallicity Relation from White Dwarf-Main Sequence Binaries

    NASA Astrophysics Data System (ADS)

    Rebassa-Mansergas, A.; Anguiano, B.; García-Berro, E.; Freeman, K. C.; Cojocaru, R.; Manser, C. J.; Pala, A. F.; Gänsicke, B. T.; Liu, X.-W.

    2017-03-01

    The age-metallicity relation (AMR) is a fundamental observational property to understand how the Galactic disc formed and evolved chemically in time. However, there is not yet a consensus on the observed properties of the AMR for the solar neighbourhood. This is due primarily to the difficulty of obtaining precise stellar ages for individual field stars. We have started an observational campaign to provide the much needed observational AMR by using white dwarf-main sequence (WDMS) binaries. White dwarfs are natural clocks and can be used to derive accurate ages. Metallicities can be obtained from the main sequence companions. Since white dwarfs and main sequence stars in these binary systems are coeval, these binaries provide an unique opportunity to observationally determine in a robust way the AMR. Here we present the AMR derived from the analysis of a sample of 23 WDMS binaries.

  20. High surface area, electrically conductive nanocarbon-supported metal oxide

    DOEpatents

    Worsley, Marcus A.; Han, Thomas Yong-Jin; Kuntz, Joshua D.; Cervantes, Octavio; Gash, Alexander E.; Baumann, Theodore F.; Satcher, Jr., Joe H.

    2015-07-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

  1. High surface area, electrically conductive nanocarbon-supported metal oxide

    SciTech Connect

    Worsley, Marcus A; Han, Thomas Yong-Jin; Kuntz, Joshua D; Cervanted, Octavio; Gash, Alexander E; Baumann, Theodore F; Satcher, Jr., Joe H

    2014-03-04

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

  2. Surface and redox properties of cobalt-ceria binary oxides: On the effect of Co content and pretreatment conditions

    NASA Astrophysics Data System (ADS)

    Konsolakis, Michalis; Sgourakis, Michalis; Carabineiro, Sónia A. C.

    2015-06-01

    Ceria-based transition metal catalysts have recently received considerable attention both in heterogeneous catalysis and electro-catalysis fields, due to their unique physicochemical characteristics. Their catalytic performance is greatly affected by the surface local chemistry and oxygen vacancies. The present study aims at investigating the impact of Co/Ce ratio and pretreatment conditions on the surface and redox properties of cobalt-ceria binary oxides. Co-ceria mixed oxides with different Co content (0, 20, 30, 60, 100 wt.%) were prepared by impregnation method and characterized by means of N2 adsorption at -196 °C, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The results shown the improved reducibility of Co/CeO2 mixed oxides compared to single oxides, due to a synergistic interaction between cobalt and cerium. Oxidation pretreatment results in a preferential localization of cerium species on the outer surface. In contrast, a uniform distribution of cobalt and cerium species over the entire catalyst surface is obtained by the reduction process, which facilitates the formation of oxygen vacancies though Co3+/Co2+ and Ce3+/Ce4+ redox cycles. Fundamental insights toward tuning the surface chemistry of cobalt-ceria binary oxides are provided, paving the way for real-life industrial applications.

  3. Process for etching mixed metal oxides

    DOEpatents

    Ashby, C.I.H.; Ginley, D.S.

    1994-10-18

    An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

  4. Process for etching mixed metal oxides

    DOEpatents

    Ashby, Carol I. H.; Ginley, David S.

    1994-01-01

    An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

  5. Aerosol-spray diverse mesoporous metal oxides from metal nitrates

    PubMed Central

    Kuai, Long; Wang, Junxin; Ming, Tian; Fang, Caihong; Sun, Zhenhua; Geng, Baoyou; Wang, Jianfang

    2015-01-01

    Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances. PMID:25897988

  6. Aerosol-spray diverse mesoporous metal oxides from metal nitrates.

    PubMed

    Kuai, Long; Wang, Junxin; Ming, Tian; Fang, Caihong; Sun, Zhenhua; Geng, Baoyou; Wang, Jianfang

    2015-04-21

    Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances.

  7. Study on Metal/Metal oxide/Graphene Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Feng, Ying; Khalid Zahir, Raja

    2013-03-01

    Metal/metal-oxide/graphene (Metal = Al, Ti, Hf, Zr) tunnel junctions were fabricated by transferring single-layer graphene grown by chemical vapor deposition on Cu onto metal strips by either a wet or dry approach. The metal strips were prepared by dc magnetron sputtering through a shadow mask and were exposed to air for about 10 minutes for native oxides to grow prior to the transfer. Good tunneling properties were observed for all the junctions fabricated by either means of graphene transfer. The zero-bias resistance of these junctions all increases with time to a final value, indicating continuing oxidation of the metals with a self-limited oxidation rate. Some junctions show the final area-normalized zero-bias resistances and self-limited oxidation time scales for Al, Ti, Hf, Zr are about 0.15, 0.2, 6000, 1000 k Ωcm2 and 25, 90, 6, 9 hour, respectively. The tunneling spectra were studied at various temperature down to 4.2 K and analyzed by the Brinkman-Dynes-Rowell model to get the height and width of the tunnel barriers, taking into account the electron structure of graphene. The junctions are good candidates for chemical sensing applications.

  8. Toxicity Assessment of Binary Metal Mixtures (Copper-Zinc) to Nitrification in Soilless Culture with the Extended Biotic Ligand Model.

    PubMed

    Liu, Aiju; Li, JinXin; Li, Menghong; Niu, Xiao Yin; Wang, Jun

    2017-02-01

    Metals are always found in the environment as mixtures rather than as solitary elements. Only a limited number of studies have developed appropriate models that incorporate bioavailability to estimate the toxicity of heavy-metal mixtures. In the present study, we explored the applicability of two extended biotic ligand model (BLM) approaches-BLM-f mix and BLM-toxicity unit (TU)-to predict and interpret mixture toxicity with the assumption that interactions between metal ions obey the BLM theory. Exposure assays of single and mixed metals were performed with inoculums of an ammonia-oxidizing bacterium SD5 isolated from soil. Nitrification of the cultures was the end point used to quantify the toxic response. The results indicated that the developed BLM-f mix approach could well estimate the single toxicity of Cu(2+) and Zn(2+) as well as their binary mixture toxicity to nitrification with >90% of toxicity variation explained. Assuming that metal ions compete with each other for binding at a single biotic ligand, the BLM-f mix approach (root-mean-square error [RMSE] = 19.66, R (2) = 0.8879) showed better predictive power than the BLM-TU approach (RMSE = 31.12, R (2) = 0.6892). The present study supports the use of the accumulation of metal ions at the biotic ligands as predictor of toxicity of single metals and metal mixtures.

  9. Method for making monolithic metal oxide aerogels

    DOEpatents

    Coronado, Paul R.

    1999-01-01

    Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The containment vessel is enclosed within an aqueous atmosphere that is above the supercritical temperature and pressure of the solvent of the metal alkoxide solution.

  10. Characterization of binary Uranuim oxides by infared spectroscopy

    SciTech Connect

    Allen, G.C.; Holmes, N.R.

    1994-04-01

    In this study, transmission infared spectra were recorded for 15 uranium oxides previously characterized by X-ray diffraction. The infared spectra obtained demonstrated that all the uranium oxides studied could be distinguished, even for the closely similiar structures of UO{sub 2} and U{sub 4}O{sub 9}. The infrared studies of U{sub 4}O{sub 9} near the temperature of the {alpha}-U{sub 4}O{sub 9} to {beta}-U{sub 4}O{sub 9} phase transition showed that an absorption at 670 cm{sup -1} could be related to the ordering of oxygen interstitials in the flourite lattice. A similiar absorption was observed for {beta}-U{sub 3}O{sub 7} but was found to be absent in {alpha}-U{sub 3}O{sub 7}. The local coordination of oxygen/metal clusters in {beta}-U{sub 4}O{sub 9} and {beta}-U{sub 3}O{sub 7} appeared to be similiar. 22 refs., 4 fig., 2 tab.

  11. Antitumor Activities of Metal Oxide Nanoparticles

    PubMed Central

    Vinardell, Maria Pilar; Mitjans, Montserrat

    2015-01-01

    Nanoparticles have received much attention recently due to their use in cancer therapy. Studies have shown that different metal oxide nanoparticles induce cytotoxicity in cancer cells, but not in normal cells. In some cases, such anticancer activity has been demonstrated to hold for the nanoparticle alone or in combination with different therapies, such as photocatalytic therapy or some anticancer drugs. Zinc oxide nanoparticles have been shown to have this activity alone or when loaded with an anticancer drug, such as doxorubicin. Other nanoparticles that show cytotoxic effects on cancer cells include cobalt oxide, iron oxide and copper oxide. The antitumor mechanism could work through the generation of reactive oxygen species or apoptosis and necrosis, among other possibilities. Here, we review the most significant antitumor results obtained with different metal oxide nanoparticles.

  12. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals.

    PubMed

    Singh, Dinesh Pratap; Srivastava, Onkar Nath

    2009-09-01

    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  13. Wide Binaries among High-Velocity and Metal-Poor Stars

    NASA Astrophysics Data System (ADS)

    Allen, C.; Herrera, M. A.; Poveda, A.

    The properties of old disk and halo binaries are of interest for the understanding of the processes of formation and early dynamical evolution of the Galaxy. The luminosity function of the components of wide binaries and multiples, their mass function, the fraction of halo or old disk stars that are members of wide binaries, and the distribution of its separations are some of the basic properties that are poorly understood, mainly because of the paucity of known wide binaries among halo and old disk stars. The present work is an attempt to ameliorate this situation. We have elaborated a list of 130 halo and old disk wide binaries by searching for common proper motion companions to the high-velocity and metal-poor stars studied by Schuster and Nissen (1988, 1993). Based on Stromgren photometry, these authors have derived distances, metallicities and ages for their stars. Since each star has a large and well determined proper motion it was possible to compare this value with that of NLTT stars of its vicinity. In this way we were able to identify 130 high-velocity and metal-poor common proper motion binary systems. Each system was carefully checked to avoid misidentifications, and when possible, distances were updated using the Hipparcos trigonometric parallaxes. We have determined the distribution of angular separations for our wide binaries. Reliable distances are available for all of our systems, so this distribution can be converted into a separation distribution in AU. We find that 12 systems have separations in excess of 10000 AU, and their existence poses interesting dynamical problems. Since many systems also have known radial velocities, space velocities for them can be determined, and galactic orbits have been computed and characterized. The secondaries of these wide binaries are interesting in themselves, since they represent a sampling of the faint end of the main sequence of old disk and halo stars.

  14. PLUTONIUM METAL: OXIDATION CONSIDERATIONS AND APPROACH

    SciTech Connect

    Estochen, E.

    2013-03-20

    Plutonium is arguably the most unique of all metals when considered in the combined context of metallurgical, chemical, and nuclear behavior. Much of the research in understanding behavior and characteristics of plutonium materials has its genesis in work associated with nuclear weapons systems. However, with the advent of applications in fuel materials, the focus in plutonium science has been more towards nuclear fuel applications, as well as long term storage and disposition. The focus of discussion included herein is related to preparing plutonium materials to meet goals consistent with non-proliferation. More specifically, the emphasis is on the treatment of legacy plutonium, in primarily metallic form, and safe handling, packaging, and transport to meet non-proliferation goals of safe/secure storage. Elevated temperature oxidation of plutonium metal is the treatment of choice, due to extensive experiential data related to the method, as the oxide form of plutonium is one of only a few compounds that is relatively simple to produce, and stable over a large temperature range. Despite the simplicity of the steps required to oxidize plutonium metal, it is important to understand the behavior of plutonium to ensure that oxidation is conducted in a safe and effective manner. It is important to understand the effect of changes in environmental variables on the oxidation characteristics of plutonium. The primary purpose of this report is to present a brief summary of information related to plutonium metal attributes, behavior, methods for conversion to oxide, and the ancillary considerations related to processing and facility safety. The information provided is based on data available in the public domain and from experience in oxidation of such materials at various facilities in the United States. The report is provided as a general reference for implementation of a simple and safe plutonium metal oxidation technique.

  15. Linear combination of XANES for quantitative analysis of Ti-Si binary oxides.

    PubMed

    Lee, J S; Kim, W B; Choi, S H

    2001-03-01

    A new method is demonstrated for the quantification of Ti-O-Si and Ti-O-Ti bonds in Ti-Si binary oxides. It is based on the linear combination of two reference X-ray absorption near-edge structure (XANES) spectra at the Ti K edge. The proper selection of a Ti-O-Si reference material is most important for the successful application of this method. Three Ti-Si binary oxide systems have been analysed by the new method: Ti-Si mixed oxides, titania supported on silica and Ti-substituted MCM-41 (crystalline mesoporous molecular sieve material invented by Mobil) with various Ti contents.

  16. Ab initio atomistic thermodynamics study on the oxidation mechanism of binary and ternary alloy surfaces

    SciTech Connect

    Liu, Shi-Yu; Liu, Shiyang; Li, De-Jun; Wang, Sanwu; Guo, Jing; Shen, Yaogen

    2015-02-14

    Utilizing a combination of ab initio density-functional theory and thermodynamics formalism, we have established the microscopic mechanisms for oxidation of the binary and ternary alloy surfaces and provided a clear explanation for the experimental results of the oxidation. We construct three-dimensional surface phase diagrams (SPDs) for oxygen adsorption on three different Nb-X(110) (X = Ti, Al or Si) binary alloy surfaces. On the basis of the obtained SPDs, we conclude a general microscopic mechanism for the thermodynamic oxidation, that is, under O-rich conditions, a uniform single-phase SPD (type I) and a nonuniform double-phase SPD (type II) correspond to the sustained complete selective oxidation and the non-sustained partial selective oxidation by adding the X element, respectively. Furthermore, by revealing the framework of thermodynamics for the oxidation mechanism of ternary alloys through the comparison of the surface energies of two separated binary alloys, we provide an understanding for the selective oxidation behavior of the Nb ternary alloy surfaces. Using these general microscopic mechanisms, one could predict the oxidation behavior of any binary and multi-component alloy surfaces based on thermodynamics considerations.

  17. Lithium metal oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil; Kang, Sun-Ho

    2010-06-08

    An uncycled preconditioned electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula xLi.sub.2-yH.sub.yO.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 in which 0metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. The xLi.sub.2-yH.sub.y.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 material is prepared by preconditioning a precursor lithium metal oxide (i.e., xLi.sub.2M'O.sub.3.(1-x)LiMO.sub.2) with a proton-containing medium with a pH<7.0 containing an inorganic acid. Methods of preparing the electrodes are disclosed, as are electrochemical cells and batteries containing the electrodes.

  18. Nanopowder Metal Oxide for Photoluminescent Gas Sensing

    NASA Astrophysics Data System (ADS)

    Zhyrovetsky, V. M.; Popovych, D. I.; Savka, S. S.; Serednytski, A. S.

    2017-02-01

    Gas sensing properties of metal oxide nanopowders (ZnO, TiO2, WO3, SnO2) with average diameters of 40-60 nm were analyzed by room-temperature photoluminescence spectroscopy. The influence of gas environment (O2, N2, H2, CO, CO2) on the emission intensity was investigated for metal oxide nanopowders with surface doped by impurities (Pt, Ag, Au, Sn, Ni or Cu). Established physicochemical regularities of modification of surface electronic states of initial and doped nanopowders during gas adsorption. The nature of metal oxide nanopowder gas-sensing properties (adsorption capacity, sensitivity, selectivity) has been established and the design and optimal materials for the construction of the multi-component sensing matrix have been selected.

  19. Cohesive energy and structural parameters of binary oxides of groups IIA and IIIB from diffusion quantum Monte Carlo

    DOE PAGES

    Santana, Juan A.; Krogel, Jaron T.; Kent, Paul R. C.; ...

    2016-05-03

    We have applied the diffusion quantum Monte Carlo (DMC) method to calculate the cohesive energy and the structural parameters of the binary oxides CaO, SrO, BaO, Sc2O3, Y2O3 and La2O3. The aim of our calculations is to systematically quantify the accuracy of the DMC method to study this type of metal oxides. The DMC results were compared with local and semi-local Density Functional Theory (DFT) approximations as well as with experimental measurements. The DMC method yields cohesive energies for these oxides with a mean absolute deviation from experimental measurements of 0.18(2) eV, while with local and semi-local DFT approximations themore » deviation is 3.06 and 0.94 eV, respectively. For lattice constants, the mean absolute deviation in DMC, local and semi-local DFT approximations, are 0.017(1), 0.07 and 0.05 , respectively. In conclusion, DMC is highly accurate method, outperforming the local and semi-local DFT approximations in describing the cohesive energies and structural parameters of these binary oxides.« less

  20. Cohesive energy and structural parameters of binary oxides of groups IIA and IIIB from diffusion quantum Monte Carlo

    SciTech Connect

    Santana, Juan A.; Krogel, Jaron T.; Kent, Paul R. C.; Reboredo, Fernando A.

    2016-05-03

    We have applied the diffusion quantum Monte Carlo (DMC) method to calculate the cohesive energy and the structural parameters of the binary oxides CaO, SrO, BaO, Sc2O3, Y2O3 and La2O3. The aim of our calculations is to systematically quantify the accuracy of the DMC method to study this type of metal oxides. The DMC results were compared with local and semi-local Density Functional Theory (DFT) approximations as well as with experimental measurements. The DMC method yields cohesive energies for these oxides with a mean absolute deviation from experimental measurements of 0.18(2) eV, while with local and semi-local DFT approximations the deviation is 3.06 and 0.94 eV, respectively. For lattice constants, the mean absolute deviation in DMC, local and semi-local DFT approximations, are 0.017(1), 0.07 and 0.05 , respectively. In conclusion, DMC is highly accurate method, outperforming the local and semi-local DFT approximations in describing the cohesive energies and structural parameters of these binary oxides.

  1. Cohesive energy and structural parameters of binary oxides of groups IIA and IIIB from diffusion quantum Monte Carlo

    NASA Astrophysics Data System (ADS)

    Santana, Juan A.; Krogel, Jaron T.; Kent, Paul R. C.; Reboredo, Fernando A.

    2016-05-01

    We have applied the diffusion quantum Monte Carlo (DMC) method to calculate the cohesive energy and the structural parameters of the binary oxides CaO, SrO, BaO, Sc2O3, Y2O3, and La2O3. The aim of our calculations is to systematically quantify the accuracy of the DMC method to study this type of metal oxides. The DMC results were compared with local, semi-local, and hybrid Density Functional Theory (DFT) approximations as well as with experimental measurements. The DMC method yields cohesive energies for these oxides with a mean absolute deviation from experimental measurements of 0.18(2) eV, while with local, semi-local, and hybrid DFT approximations, the deviation is 3.06, 0.94, and 1.23 eV, respectively. For lattice constants, the mean absolute deviations in DMC, local, semi-local, and hybrid DFT approximations are 0.017(1), 0.07, 0.05, and 0.04 Å, respectively. DMC is a highly accurate method, outperforming the DFT approximations in describing the cohesive energies and structural parameters of these binary oxides.

  2. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, Brian S.; Gupta, Raghubir P.

    2001-01-01

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

  3. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, Brian S.; Gupta, Raghubir P.

    1999-01-01

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

  4. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, B.S.; Gupta, R.P.

    1999-06-22

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream. 1 fig.

  5. PHASE ANALYSIS AND CRYSTAL STRUCTURE STUDIES ON BINARY ALLOYS OF ALUMINUM WITH TRANSITION METALS.

    DTIC Science & Technology

    In order to provide the necessary background for detailed crystal-chemistry studies in the field of binary aluminum - transition metal systems, extensive investigations have been carried out on the phase relations of a large number of such systems. The results of these studies are briefly summarized, as are also the results of crystal structure determinations of a few alumi num - transition metal phases. (Author)

  6. Regeneration of sulfated metal oxides and carbonates

    DOEpatents

    Hubble, Bill R.; Siegel, Stanley; Cunningham, Paul T.

    1978-03-28

    Alkali metal or alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate found in dolomite or limestone are employed for removal of sulfur dioxide from combustion exhaust gases. The sulfated carbonates are regenerated to oxides through use of a solid-solid reaction, particularly calcium sulfide with calcium sulfate to form calcium oxide and sulfur dioxide gas. The regeneration is performed by contacting the sulfated material with a reductant gas such as hydrogen within an inert diluent to produce calcium sulfide in mixture with the sulfate under process conditions selected to permit the sulfide-sulfate, solid-state reaction to occur.

  7. Metal Oxide Materials and Decontamination Methodology

    DTIC Science & Technology

    1991-01-15

    polyoxometalates as photocatalysts for oxidative degradation. The abstract for this paper, reference 15, is as follows. This paper is undergoing revision and...substrates catalyzed by representative semiconductor metal oxides (anatase TiO2 , SnO2, cubic W03, and CdS) and photoredox active early transition metal...326"] = k4,I[THT]/k[TNT] + kic) is consistent with this data and the observation of saturation kinetics in TNT. Upon addition of 02, TiO2 (with or

  8. Spinel-structured metal oxide on a substrate and method of making same by molecular beam epitaxy

    DOEpatents

    Chambers, Scott A.

    2006-02-21

    A method of making a spinel-structured metal oxide on a substrate by molecular beam epitaxy, comprising the step of supplying activated oxygen, a first metal atom flux, and at least one other metal atom flux to the surface of the substrate, wherein the metal atom fluxes are individually controlled at the substrate so as to grow the spinel-structured metal oxide on the substrate and the metal oxide is substantially in a thermodynamically stable state during the growth of the metal oxide. A particular embodiment of the present invention encompasses a method of making a spinel-structured binary ferrite, including Co ferrite, without the need of a post-growth anneal to obtain the desired equilibrium state.

  9. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

    Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

    2006-06-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

  10. Reduction of metal oxides through mechanochemical processing

    DOEpatents

    Froes, Francis H.; Eranezhuth, Baburaj G.; Senkov, Oleg N.

    2000-01-01

    The low temperature reduction of a metal oxide using mechanochemical processing techniques. The reduction reactions are induced mechanically by milling the reactants. In one embodiment of the invention, titanium oxide TiO.sub.2 is milled with CaH.sub.2 to produce TiH.sub.2. Low temperature heat treating, in the range of 400.degree. C. to 700.degree. C., can be used to remove the hydrogen in the titanium hydride.

  11. Advanced metal oxide varistor concepts

    NASA Astrophysics Data System (ADS)

    Philipp, H. R.; Mahan, G. D.; Levinson, L. M.

    1984-07-01

    Zinc oxide varistors are ZnO-based ceramic semiconductor devices with highly nonlinear current-voltage characteristics similar to back-to-back Zener diodes but with much greater current, voltage, and energy-handling capabilities. Zinc oxide varistors have proven useful in a variety of applications, particularly as high-quality voltage suppression devices for the protection of ac and dc electric power transmission systems against the effects of transient overvoltages due to switching surges and lightning strikes. Simple varistor systems that use Bi or Pr as the varistor-forming additive and Co or Mn as the varistor-performance ingredient were studied. Commercial varistor materials generally use Bi as the varistor-forming ingredient, and the sintering process in such material probably proceeds in the liquid phase. Varistor materials that use Pr as the varistor-forming ingredient are also produced commercially.

  12. Metal oxide electrocatalysts for alternative energy technologies

    NASA Astrophysics Data System (ADS)

    Pacquette, Adele Lawren

    This dissertation focuses on the development of metal oxide electrocatalysts with varying applications for alternative energy technologies. Interest in utilizing clean, renewable and sustainable sources of energy for powering the planet in the future has received much attention. This will address the growing concern of the need to reduce our dependence on fossil fuels. The facile synthesis of metal oxides from earth abundant metals was explored in this work. The electrocatalysts can be incorporated into photoelectrochemical devices, fuel cells, and other energy storage devices. The first section addresses the utilization of semiconductors that can harness solar energy for water splitting to generate hydrogen. An oxysulfide was studied in order to combine the advantageous properties of the stability of metal oxides and the visible light absorbance of metal chalcogenides. Bi 2O2S was synthesized under facile hydrothermal conditions. The band gap of Bi2O2S was smaller than that of its oxide counterpart, Bi2O3. Light absorption by Bi 2O2S was extended to the visible region (>600 nm) in comparison to Bi2O3. The formation of a composite with In 2O3 was formed in order to create a UV irradiation protective coating of the Bi2O2S. The Bi2O2S/In 2O3 composite coupled with a dye CrTPP(Cl) and cocatalysts Pt and Co3O4 was utilized for water splitting under light irradiation to generate hydrogen and oxygen. The second section focuses on improving the stability and light absorption of semiconductors by changing the shapes and morphologies. One of the limitations of semiconductor materials is that recombination of electron-hole pairs occur within the bulk of the materials instead of migration to the surface. Three-dimensional shapes, such as nanorods, can prevent this recombination in comparison to spherical particles. Hierarchical structures, such as dendrites, cubes, and multipods, were synthesized under hydrothermal conditions, in order to reduce recombination and improve

  13. Microbial-mediated method for metal oxide nanoparticle formation

    DOEpatents

    Rondinone, Adam J.; Moon, Ji Won; Love, Lonnie J.; Yeary, Lucas W.; Phelps, Tommy J.

    2015-09-08

    The invention is directed to a method for producing metal oxide nanoparticles, the method comprising: (i) subjecting a combination of reaction components to conditions conducive to microbial-mediated formation of metal oxide nanoparticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium suitable for sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible metal oxide component containing one or more reducible metal species, and one or more electron donors that provide donatable electrons to said metal-reducing microbes during consumption of the electron donor by said metal-reducing microbes; and (ii) isolating said metal oxide nanoparticles, which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide nanoparticle compositions produced by the inventive method.

  14. Gravitational Wave Background from Binary Mergers and Metallicity Evolution of Galaxies

    NASA Astrophysics Data System (ADS)

    Nakazato, Ken'ichiro; Niino, Yuu; Sago, Norichika

    2016-12-01

    The cosmological evolution of the binary black hole (BH) merger rate and the energy density of the gravitational wave (GW) background are investigated. To evaluate the redshift dependence of the BH formation rate, BHs are assumed to originate from low-metallicity stars, and the relations between the star formation rate, metallicity and stellar mass of galaxies are combined with the stellar mass function at each redshift. As a result, it is found that when the energy density of the GW background is scaled with the merger rate at the local universe, the scaling factor does not depend on the critical metallicity for the formation of BHs. Also taking into account the merger of binary neutron stars, a simple formula to express the energy spectrum of the GW background is constructed for the inspiral phase. The relation between the local merger rate and the energy density of the GW background will be examined by future GW observations.

  15. Metal oxide chemistry in solution: the early transition metal polyoxoanions.

    PubMed

    Day, V W; Klemperer, W G

    1985-05-03

    Many of the early transition elements form large polynuclear metal-oxygen anions containing up to 200 atoms or more. Although these polyoxoanions have been investigated for more than a century, detailed studies of structure and reactivity were not possible until the development of modern x-ray crystallographic and nuclear magnetic resonance spectroscopic techniques. Systematic studies of small polyoxoanions in inert, aprotic solvents have clarified many of the principles governing their structure and reactivity, and also have made possible the preparation of entirely new types of covalent derivatives such as CH(2)Mo(4)O(15)H(3-), C(5)H(5)TiMo(5)O(18)(3-), and (OC)(3)Mn(Nb(2)W(4)O(19))(3-). Since most early transition metal polyoxoanions have structures based on close-packed oxygen arrays containing interstitial metal centers, their chemistry offers a rare opportunity to study chemical transformations in detail on well-defined metal oxide surfaces.

  16. Multi-metal oxide ceramic nanomaterial

    SciTech Connect

    O'Brien, Stephen; Liu, Shuangyi; Huang, Limin

    2016-06-07

    A convenient and versatile method for preparing complex metal oxides is disclosed. The method uses a low temperature, environmentally friendly gel-collection method to form a single phase nanomaterial. In one embodiment, the nanomaterial consists of Ba.sub.AMn.sub.BTi.sub.CO.sub.D in a controlled stoichiometry.

  17. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.

    1994-01-01

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques.

  18. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, M.A.

    1994-05-03

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques. 2 figures.

  19. Liquid-metal binary cycles for stationary power

    NASA Technical Reports Server (NTRS)

    Gutstein, M.; Furman, E. R.; Kaplan, G. M.

    1975-01-01

    The use of topping cycles to increase electric power plant efficiency is discussed, with particular attention to mercury and alkali metal Rankine cycle systems that could be considered for topping cycle applications. An overview of this technology, possible system applications, the required development, and possible problem areas is presented.

  20. Immobilization of selenite in soil and groundwater using stabilized Fe-Mn binary oxide nanoparticles.

    PubMed

    Xie, Wenbo; Liang, Qiqi; Qian, Tianwei; Zhao, Dongye

    2015-03-01

    Stabilized Fe-Mn binary oxide nanoparticles were synthesized and tested for removal and in-situ immobilization of Se(IV) in groundwater and soil. A water-soluble starch or food-grade carboxymethyl cellulose (CMC) was used as a stabilizer to facilitate in-situ delivery of the particles into contaminated soil. While bare and stabilized nanoparticles showed rapid sorption kinetics, starch-stabilized Fe-Mn offered the greatest capacity for Se(IV). The Langmuir maximum capacity was determined to be 109 and 95 mg-Se/g-Fe for starch- and CMC-stabilized nanoparticles, respectively, and the high Se(IV) uptake was observed over the typical groundwater pH range of 5-8. Column breakthrough tests indicated that the stabilized nanoparticles were deliverable in a model sandy soil while non-stabilized particles were not. When a Se(IV)-spiked soil was treated in situ with the nanoparticles, >90% water leachable Se(IV) was transferred to the nanoparticle phase, and thereby immobilized as the particles were retained in the downstream soil matrix. The nanoparticle amendment reduced the TCLP (toxicity characteristic leaching procedure) leachability and the California WET (waste extraction test) leachability of Se(IV) by 76% and 71%, respectively. The technology holds the potential to fill a major technology gap in remediation of metals-contaminated soil and groundwater.

  1. Method for producing nanostructured metal-oxides

    DOEpatents

    Tillotson, Thomas M.; Simpson, Randall L.; Hrubesh, Lawrence W.; Gash, Alexander

    2006-01-17

    A synthetic route for producing nanostructure metal-oxide-based materials using sol-gel processing. This procedure employs the use of stable and inexpensive hydrated-metal inorganic salts and environmentally friendly solvents such as water and ethanol. The synthesis involves the dissolution of the metal salt in a solvent followed by the addition of a proton scavenger, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively. Using this method synthesis of metal-oxide nanostructured materials have been carried out using inorganic salts, such as of Fe.sup.3+, Cr.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, Hf.sup.4+, Sn.sup.4+, Zr.sup.4+, Nb.sup.5+, W.sup.6+, Pr.sup.3+, Er.sup.3+, Nd.sup.3+, Ce.sup.3+, U.sup.3+ and Y.sup.3+. The process is general and nanostructured metal-oxides from the following elements of the periodic table can be made: Groups 2 through 13, part of Group 14 (germanium, tin, lead), part of Group 15 (antimony, bismuth), part of Group 16 (polonium), and the lanthanides and actinides. The sol-gel processing allows for the addition of insoluble materials (e.g., metals or polymers) to the viscous sol, just before gelation, to produce a uniformly distributed nanocomposites upon gelation. As an example, energetic nanocomposites of Fe.sub.xO.sub.y gel with distributed Al metal are readily made. The compositions are stable, safe, and can be readily ignited to thermitic reaction.

  2. Apparatus enables accurate determination of alkali oxides in alkali metals

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.; Gahn, R. F.; Graab, J. W.; Maple, W. E.; Rosenblum, L.

    1966-01-01

    Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure.

  3. Wide Binaries among High-Velocity and Metal-Poor Stars

    NASA Astrophysics Data System (ADS)

    Allen, C.; Herrera, M. A.; Poveda, A.

    1998-11-01

    The properties of old disk and halo binaries are of interest for the understanding of the processes of formation and early dynamical evolution of the Galaxy. The luminosity function of the components of wide binaries and multiples, their mass function, the fraction of halo or old disk stars that are members of wide binaries, and the distribution of their separations are some of the basic properties that are poorly understood, mainly because of the paucity of known wide binaries among halo and old disk stars. The present work is an attempt to ameliorate this situation. We have elaborated a list of 133 wide binaries mostly belonging to the halo or high-velocity disk, by searching for common proper motion companions to the high-velocity and metal-poor stars studied by Schuster and collaborators (1988, 1993). Based on Stromgren photometry, these authors have derived distances, metallicities and ages for their stars. Since each star has a large and well determined proper motion, it was possible to compare this value with that of NLTT stars of its vicinity. In this way we were able to identify over 100 high-velocity and metal-poor common proper motion binary systems. Each system was carefully checked to avoid misidentifications; in most of the cases, distances were improved using the Hipparcos trigonometric parallaxes. We have determined the distribution of angular separations for our wide binaries. Reliable distances are available for all of our systems, so this distribution can be converted into a separation distribution in AU. We find 11 systems that have projected semiaxes in excess of 10000 AU, or 16 systems with expected semiaxes larger than 10000 AU, their existence poses interesting dynamical problems. Since many systems also have known radial velocities, space velocities for them can be determined, and galactic orbits have been computed and characterized. The secondaries of these wide binaries are interesting by themselves, since they represent a sampling of the

  4. Toxic effect of metal cation binary mixtures to the seaweed Gracilaria domingensis (Gracilariales, Rhodophyta).

    PubMed

    Mendes, Luiz Fernando; Stevani, Cassius Vinicius; Zambotti-Villela, Leonardo; Yokoya, Nair Sumie; Colepicolo, Pio

    2014-01-01

    The macroalga Gracilaria domingensis is an important resource for the food, pharmaceutical, cosmetic, and biotechnology industries. G. domingensis is at a part of the food web foundation, providing nutrients and microelements to upper levels. As seaweed storage metals in the vacuoles, they are considered the main vectors to magnify these toxic elements. This work describes the evaluation of the toxicity of binary mixtures of available metal cations based on the growth rates of G. domingensis over a 48-h exposure. The interactive effects of each binary mixture were determined using a toxic unit (TU) concept that was the sum of the relative contribution of each toxicant and calculated using the ratio between the toxicant concentration and its endpoint. Mixtures of Cd(II)/Cu(II) and Zn(II)/Ca(II) demonstrated to be additive; Cu(II)/Zn(II), Cu(II)/Mg(II), Cu(II)/Ca(II), Zn(II)/Mg(II), and Ca(II)/Mg(II) mixtures were synergistic, and all interactions studied with Cd(II) were antagonistic. Hypotheses that explain the toxicity of binary mixtures at the molecular level are also suggested. These results represent the first effort to characterize the combined effect of available metal cations, based on the TU concept on seaweed in a total controlled medium. The results presented here are invaluable to the understanding of seaweed metal cation toxicity in the marine environment, the mechanism of toxicity action and how the tolerance of the organism.

  5. The close binary frequency of Wolf-Rayet stars as a function of metallicity in M31 and M33

    SciTech Connect

    Neugent, Kathryn F.; Massey, Philip E-mail: phil.massey@lowell.edu

    2014-07-01

    Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the 'extra' WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ∼100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.

  6. Effects of Preparation on the Properties of Niobia-Alumina Binary Oxides

    DTIC Science & Technology

    1988-06-15

    acidity in binary oxides. • The characterization of oxides as model catalysts by the use of reactions such as 1 -butene isomerization. The following...Public Release; Distribution 2b. DECLASSIFICATION /DOWNGRADING SCHEDULE Unlimited 4 PERFORMING ORGANIZATION REPORT NUMBER(S) S MONITORING ORGANIZATION ...REPORT NUMBER(S) 6a NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a NAME OF MONITORiNG ORGANIZATION Carnegie Mellon University (If applicable

  7. 40 CFR 721.4610 - Mixed metal oxides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN...

  8. 40 CFR 721.10500 - Acrylated mixed metal oxides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acrylated mixed metal oxides (generic... Specific Chemical Substances § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance and... mixed metal oxides (PMN P-06-341) is subject to reporting under this section for the significant...

  9. 40 CFR 721.10006 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN...

  10. 40 CFR 721.5549 - Lithiated metal oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN...

  11. 40 CFR 721.10006 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN...

  12. 40 CFR 721.5549 - Lithiated metal oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN...

  13. 40 CFR 721.5549 - Lithiated metal oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN...

  14. 40 CFR 721.5549 - Lithiated metal oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN...

  15. 40 CFR 721.5548 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956)...

  16. 40 CFR 721.4610 - Mixed metal oxides (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN...

  17. 40 CFR 721.5548 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956)...

  18. 40 CFR 721.5548 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956)...

  19. 40 CFR 721.5548 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956)...

  20. 40 CFR 721.4610 - Mixed metal oxides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN...

  1. 40 CFR 721.10006 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN...

  2. 40 CFR 721.5549 - Lithiated metal oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN...

  3. 40 CFR 721.10006 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN...

  4. 40 CFR 721.10500 - Acrylated mixed metal oxides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Acrylated mixed metal oxides (generic... Specific Chemical Substances § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance and... mixed metal oxides (PMN P-06-341) is subject to reporting under this section for the significant...

  5. 40 CFR 721.5548 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956)...

  6. 40 CFR 721.4610 - Mixed metal oxides (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN...

  7. 40 CFR 721.4610 - Mixed metal oxides (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN...

  8. 40 CFR 721.10006 - Mixed metal oxide (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN...

  9. Reactor vessel using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.; Zeltner, Walter A.

    1992-08-11

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane.

  10. NMR in Copper-Oxide Metals

    SciTech Connect

    Varma, C.M.

    1996-10-01

    The anomalous part of the NMR relaxation rate of copper nuclei in the normal state of copper-oxide metals is calculated using the orbital magnetic parts of the fluctuations derived in a recent theory to explain the long wavelength transport anomalies. Oxygen and yttrium reside on lattice sites at which the anomalous contribution is absent at all hole densities. The frequency, momentum dependence, and the form factor of the fluctuations is predicted. {copyright} {ital 1996 The American Physical Society.}

  11. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

    1995-01-01

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm.sup.3 and greater than 0.27g/cm.sup.3. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods.

  12. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

    1995-04-25

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm{sup 3} and greater than 0.27g/cm{sup 3}. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods. 8 figs.

  13. Unimolecular precursors to binary metal sulfides: Mechanistic and structural correlations

    SciTech Connect

    Schluter, R.D.; Kraeuter, G.; Rees, W.S. Jr.

    1996-12-31

    The roles which ligand size and stability play in influencing solid-state thermolyses products and phases are developed for a group of metal thiolate compounds. The exploration includes Pb(SR){sub 2} [R = t-Bu, i-Bu, s-Bu], Cd(SR*){sub 2} [R* = i-Pr, t-Bu, Bz], ClHgSR** [R** = i-Pr, neo-Pent, Bz] and In(SR***){sub 3} [R*** = 2,4,6-(i-Pr){sub 3}C{sub 6}H{sub 2}, 2-CH{sub 3}O-5-CH{sub 3}C{sub 6}H{sub 3}, o-C{sub 6}H{sub 4}CH{sub 2}N(CH{sub 3}){sub 2}]. In several examples, the precursors have been characterized by single crystal X-ray diffraction. In most cases, solid-state decomposition products have been identified by XRPD, and volatile decomposition products have been identified by GC/MS. All precursors have been studied by TGA.

  14. Hydrous metal oxide catalysts for oxidation of hydrocarbons

    SciTech Connect

    Miller, J.E.; Dosch, R.G.; McLaughlin, L.I.

    1993-07-01

    This report describes work performed at Sandia under a CRADA with Shell Development of Houston, Texas aimed at developing hydrous metal oxide (HMO) catalysts for oxidation of hydrocarbons. Autoxidation as well as selective oxidation of 1-octene was studied in the presence of HMO catalysts based on known oxidation catalysts. The desired reactions were the conversion of olefin to epoxides, alcohols, and ketones, HMOs seem to inhibit autoxidation reactions, perhaps by reacting with peroxides or radicals. Attempts to use HMOs and metal loaded HMOs as epoxidation catalysts were unsuccessful, although their utility for this reaction was not entirely ruled out. Likewise, alcohol formation from olefins in the presence of HMO catalysts was not achieved. However, this work led to the discovery that acidified HMOs can lead to carbocation reactions of hydrocarbons such as cracking. An HMO catalyst containing Rh and Cu that promotes the reaction of {alpha}-olefins with oxygen to form methyl ketones was identified. Although the activity of the catalyst is relatively low and isomerization reactions of the olefin simultaneously occur, results indicate that these problems may be addressed by eliminating mass transfer limitations. Other suggestions for improving the catalyst are also made. 57 refs.

  15. Impact dynamics of oxidized liquid metal drops

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Brown, Eric; Jaeger, Heinrich M.

    2013-04-01

    With exposure to air, many liquid metals spontaneously generate an oxide layer on their surface. In oscillatory rheological tests, this skin is found to introduce a yield stress that typically dominates the elastic response but can be tuned by exposing the metal to hydrochloric acid solutions of different concentration. We systematically studied the normal impact of eutectic gallium-indium (eGaIn) drops under different oxidation conditions and show how this leads to two different dynamical regimes. At low impact velocity (or low Weber number), eGaIn droplets display strong recoil and rebound from the impacted surface when the oxide layer is removed. In addition, the degree of drop deformation or spreading during impact is controlled by the oxide skin. We show that the scaling law known from ordinary liquids for the maximum spreading radius as a function of impact velocity can still be applied to the case of oxidized eGaIn if an effective Weber number We is employed that uses an effective surface tension factoring in the yield stress. In contrast, no influence on spreading from different oxidations conditions is observed for high impact velocity. This suggests that the initial kinetic energy is mostly damped by bulk viscous dissipation. Results from both regimes can be collapsed in an impact phase diagram controlled by two variables, the maximum spreading factor Pm=R0/Rm, given by the ratio of initial to maximum drop radius, and the impact number K=We/Re4/5, which scales with the effective Weber number We as well as the Reynolds number Re. The data exhibit a transition from capillary to viscous behavior at a critical impact number Kc≈0.1.

  16. Method for inhibiting oxidation of metal sulfide-containing material

    DOEpatents

    Elsetinow, Alicia; Borda, Michael J.; Schoonen, Martin A.; Strongin, Daniel R.

    2006-12-26

    The present invention provides means for inhibiting the oxidation of a metal sulfide-containing material, such as ore mine waste rock or metal sulfide taiulings, by coating the metal sulfide-containing material with an oxidation-inhibiting two-tail lipid coating (12) thereon, thereby inhibiting oxidation of the metal sulfide-containing material in acid mine drainage conditions. The lipids may be selected from phospholipids, sphingolipids, glycolipids and combinations thereof.

  17. Ternary and coupled binary zinc tin oxide nanopowders: Synthesis, characterization, and potential application in photocatalytic processes

    SciTech Connect

    Ivetić, T.B.; Finčur, N.L.; Đačanin, Lj. R.; Abramović, B.F.; Lukić-Petrović, S.R.

    2015-02-15

    Highlights: • Mechanochemically synthesized nanocrystalline zinc tin oxide (ZTO) powders. • Photocatalytic degradation of alprazolam in the presence of ZTO water suspensions. • Coupled binary ZTO exhibits enhanced photocatalytic activity compared to ternary ZTO. - Abstract: In this paper, ternary and coupled binary zinc tin oxide nanocrystalline powders were prepared via simple solid-state mechanochemical method. X-ray diffraction, scanning electron microscopy, Raman and reflectance spectroscopy were used to study the structure and optical properties of the obtained powder samples. The thermal behavior of zinc tin oxide system was examined through simultaneous thermogravimetric-differential scanning calorimetric analysis. The efficiencies of ternary (Zn{sub 2}SnO{sub 4} and ZnSnO{sub 3}) and coupled binary (ZnO/SnO{sub 2}) zinc tin oxide water suspensions in the photocatalytic degradation of alprazolam, short-acting anxiolytic of the benzodiazepine class of psychoactive drugs, under UV irradiation were determined and compared with the efficiency of pure ZnO and SnO{sub 2}.

  18. Binary Blue Metal-poor Stars: Evidence for Asymptotic Giant Branch Mass Transfer

    NASA Astrophysics Data System (ADS)

    Sneden, Christopher; Preston, George W.; Cowan, John J.

    2003-07-01

    We present new abundance analyses of six blue metal-poor (BMP) stars with very low iron abundances ([Fe/H]<-2), based on new high-resolution echelle spectra. Three are spectroscopic binaries, and three have constant radial velocities. The chemical compositions of these two groups are very different, as the binary BMP stars have large enhancements of carbon and neutron-capture elements that are products of s-process nucleosynthesis. One star, CS 29497-030, has an extreme enhancement of lead, [Pb/Fe]=+3.7, the largest abundance in any star yet discovered. It probably also has an oxygen overabundance compared to the other BMP stars of our sample. The binary BMP stars must have attained their status via mass transfer during the asymptotic giant branch (AGB) evolutions of their companion stars, which are now unseen and most likely are compact objects. We have not found any examples of AGB mass transfer among BMP binaries with [Fe/H]>-2.

  19. High-resolution spectroscopy of extremely metal-poor stars from SDSS/Segue. II. Binary fraction

    SciTech Connect

    Aoki, Wako; Suda, Takuma; Beers, Timothy C.; Honda, Satoshi E-mail: takuma.suda@nao.ac.jp E-mail: honda@nhao.jp

    2015-02-01

    The fraction of binary systems in various stellar populations of the Galaxy and the distribution of their orbital parameters are important but not well-determined factors in studies of star formation, stellar evolution, and Galactic chemical evolution. While observational studies have been carried out for a large sample of nearby stars, including some metal-poor Population II stars, almost no constraints on the binary nature for extremely metal-poor (EMP; [Fe/H] <−3.0) stars have yet been obtained. Here we investigate the fraction of double-lined spectroscopic binaries and carbon-enhanced metal-poor (CEMP) stars, many of which could have formed as pairs of low-mass and intermediate-mass stars, to estimate the lower limit of the fraction of binary systems having short periods. The estimate is based on a sample of very metal-poor stars selected from the Sloan Digital Sky Survey and observed at high spectral resolution in a previous study by Aoki et al. That survey reported 3 double-lined spectroscopic binaries and 11 CEMP stars, which we consider along with a sample of EMP stars from the literature compiled in the SAGA database. We have conducted measurements of the velocity components for stacked absorption features of different spectral lines for each double-lined spectroscopic binary. Our estimate indicates that the fraction of binary stars having orbital periods shorter than 1000 days is at least 10%, and possibly as high as 20% if the majority of CEMP stars are formed in such short-period binaries. This result suggests that the period distribution of EMP binary systems is biased toward short periods, unless the binary fraction of low-mass EMP stars is significantly higher than that of other nearby stars.

  20. Sorption mechanisms of metals to graphene oxide

    NASA Astrophysics Data System (ADS)

    Showalter, Allison R.; Duster, Thomas A.; Szymanowski, Jennifer E. S.; Na, Chongzheng; Fein, Jeremy B.; Bunker, Bruce A.

    2016-05-01

    Environmental toxic metal contamination remediation and prevention is an ongoing issue. Graphene oxide is highly sorptive for many heavy metals over a wide pH range under different ionic strength conditions. We present x-ray absorption fine structure (XAFS) spectroscopy results investigating the binding environment of Pb(II), Cd(II) and U(VI) ions onto multi-layered graphene oxide (MLGO). Analysis indicates that the dominant sorption mechanism of Pb to MLGO changes as a function of pH, with increasing inner sphere contribution as pH increases. In contrast, the sorption mechanism of Cd to MLGO remains constant under the studied pH range. This adsorption mechanism is an electrostatic attraction between the hydrated Cd+2 ion and the MLGO surface. The U(VI), present as the uranyl ion, changes only subtly as a function of pH and is bound to the surface via an inner sphere bond. Knowledge of the binding mechanism for each metal is necessary to help in optimizing environmental remediation or prevention in filtration systems.

  1. Inhibiting Metal Oxide Atomic Layer Deposition: Beyond Zinc Oxide.

    PubMed

    Sampson, Matthew D; Emery, Jonathan D; Pellin, Michael J; Martinson, Alex B F

    2017-04-05

    Atomic layer deposition (ALD) of several metal oxides is selectivity inhibited on alkanethiol self-assembled monolayers (SAMs) on Au, and the eventual nucleation mechanism is investigated. The inhibition ability of the SAM is significantly improved by the in situ H2-plasma pretreatment of the Au substrate prior to the gas-phase deposition of a long-chain alkanethiol, 1-dodecanethiol (DDT). This more rigorous surface preparation inhibits even aggressive oxide ALD precursors, including trimethylaluminum and water, for at least 20 cycles. We study the effect that the ALD precursor purge times, growth temperature, alkanethiol chain length, alkanethiol deposition time, and plasma treatment time have on Al2O3 ALD inhibition. This is the first example of Al2O3 ALD inhibition from a vapor-deposited SAM. The inhibitions of Al2O3, ZnO, and MnO ALD processes are compared, revealing the versatility of this selective surface treatment. Atomic force microscopy and grazing-incidence X-ray fluorescence further reveal insight into the mechanism by which the well-defined surface chemistry of ALD may eventually be circumvented to allow metal oxide nucleation and growth on SAM-modified surfaces.

  2. Surface studies of gas sensing metal oxides.

    PubMed

    Batzill, Matthias; Diebold, Ulrike

    2007-05-21

    The relation of surface science studies of single crystal metal oxides to gas sensing applications is reviewed. Most metal oxide gas sensors are used to detect oxidizing or reducing gases and therefore this article focuses on surface reduction processes and the interaction of oxygen with these surfaces. The systems that are discussed are: (i) the oxygen vacancy formation on the surface of the ion conductor CeO(2)(111); (ii) interaction of oxygen with TiO(2) (both adsorption processes and the incorporation of oxygen into the TiO(2)(110) lattice are discussed); (iii) the varying surface composition of SnO(2)(101) and its consequence for the adsorption of water; and (iv) Cu modified ZnO(0001)-Zn surfaces and its interaction with oxygen. These examples are chosen to give a comprehensive overview of surface science studies of different kinds of gas sensing materials and to illustrate the potential that surface science studies have to give fundamental insight into gas sensing phenomena.

  3. Reduced graphene oxide-metal/metal oxide composites: facile synthesis and application in water purification.

    PubMed

    Sreeprasad, T S; Maliyekkal, Shihabudheen M; Lisha, K P; Pradeep, T

    2011-02-15

    This paper describes a versatile, and simple synthetic route for the preparation of a range of reduced graphene oxide (RGO)-metal/metal oxide composites and their application in water purification. The inherent reduction ability of RGO has been utilized to produce the composite structure from the respective precursor ions. Various spectroscopic and microscopic techniques were employed to characterize the as-synthesized composites. The data reveal that the RGO-composites are formed through a redox-like reaction between RGO and the metal precursor. RGO is progressively oxidized primarily to graphene oxide (GO) and the formed metal nanoparticles are anchored onto the carbon sheets. Metal ion scavenging applications of RGO-MnO(2) and RGO-Ag were demonstrated by taking Hg(II) as the model pollutant. RGO and the composites give a high distribution coefficient (K(d)), greater than 10 L g(-1) for Hg(II) uptake. The K(d) values for the composites are found to be about an order of magnitude higher compared to parent RGO and GO for this application. A methodology was developed to immobilize RGO-composites on river sand (RS) using chitosan as the binder. The as-supported composites are found to be efficient adsorbent candidates for field application.

  4. Process for producing metal compounds from graphite oxide

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2000-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  5. Process for Producing Metal Compounds from Graphite Oxide

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2000-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  6. The competing oxide and sub-oxide formation in metal-oxide molecular beam epitaxy

    SciTech Connect

    Vogt, Patrick; Bierwagen, Oliver

    2015-02-23

    The hetero-epitaxial growth of the n-type semiconducting oxides β-Ga{sub 2}O{sub 3}, In{sub 2}O{sub 3}, and SnO{sub 2} on c- and r-plane sapphire was performed by plasma-assisted molecular beam epitaxy. The growth-rate and desorbing flux from the substrate were measured in-situ under various oxygen to metal ratios by laser reflectometry and quadrupole mass spectrometry, respectively. These measurements clarified the role of volatile sub-oxide formation (Ga{sub 2}O, In{sub 2}O, and SnO) during growth, the sub-oxide stoichiometry, and the efficiency of oxide formation for the three oxides. As a result, the formation of the sub-oxides decreased the growth-rate under metal-rich growth conditions and resulted in etching of the oxide film by supplying only metal flux. The flux ratio for the exclusive formation of the sub-oxide (e.g., the p-type semiconductor SnO) was determined, and the efficiency of oxide formation was found to be the highest for SnO{sub 2}, somewhat lower for In{sub 2}O{sub 3}, and the lowest for Ga{sub 2}O{sub 3}. Our findings can be generalized to further oxides that possess related sub-oxides.

  7. Heavy metal removal from water/wastewater by nanosized metal oxides: a review.

    PubMed

    Hua, Ming; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

    2012-04-15

    Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs' preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance.

  8. The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

    ERIC Educational Resources Information Center

    Moore, Lewis Ryan

    2006-01-01

    The purpose of this research was to determine how metal oxide used in a thermite reaction can impact the production of nanoparticles. The results showed the presence of nanoparticles (less than 1 micron in diameter) of at least one type produced by each metal oxide. The typical particles were metallic spheres, which ranged from 300 nanometers in…

  9. Novel High-Throughput Screening Approach for Functional Metal/Oxide Interfaces.

    PubMed

    Neufeld, Ofer; Toroker, Maytal Caspary

    2016-04-12

    Metal/oxide interfaces have long been studied for their fundamental importance in material microstructure as well as their broad applicability in electronic devices. However, the challenge involved in characterizing the relation between structure and electron transport of a large number of metal/oxide combinations inhibits the search for interfaces with improved functionality. Therefore, we develop a novel high-throughput screening approach that combines computational and theoretical techniques. We use a Density Functional Theory + U (DFT+U) quantum mechanical formalism to produce effective Schrödinger equations, which are solved by wave packet propagation to simulate charge transport across the metal/oxide interface. We demonstrate this method on α-Fe2O3/Mt interfaces, for Mt = Ag, Al, Au, Ir, Pd, or Pt metals. We use this novel method to screen for binary alloys of these metals at the α-Fe2O3/Mt interface and perform a successful validation test of the methodology. Finally, we correlate the interface potential energy and the charge transport permeability through the interface. Counterintuitively, among the interfaces studied, we find that higher mismatch interfaces have better charge transport permeability. We anticipate that this method will be useful as a computationally tractable strategy to perform high-throughput screening for new metal/oxide interfaces.

  10. Joint toxic action of binary metal mixtures of copper, manganese and nickel to Paronychiurus kimi (Collembola).

    PubMed

    Son, Jino; Lee, Yun-Sik; Kim, Yongeun; Shin, Key-Il; Hyun, Seunghun; Cho, Kijong

    2016-10-01

    The joint toxic effects of binary metal mixtures of copper (Cu), manganese (Mn) and nickel (Ni) on reproduction of Paronhchiurus kimi (Lee) was evaluated using a toxic unit (TU) approach by judging additivity across a range of effect levels (10-90%). For all metal mixtures, the joint toxic effects of metal mixtures on reproduction of P. kimi decreased in a TU-dependent manner. The joint toxic effects of metal mixtures also changed from less than additive to more than additive at an effect level lower than or equal to 50%, while a more than additive toxic effects were apparent at higher effect levels. These results indicate that the joint toxicity of metal mixtures is substantially different from that of individual metals based on additivity. Moreover, the close relationship of toxicity to effect level suggests that it is necessary to encompass a whole range of effect levels rather than a specific effect level when judging mixture toxicity. In conclusion, the less than additive toxicity at low effect levels suggests that the additivity assumption is sufficiently conservative to warrant predicting joint toxicity of metal mixtures, which may give an additional margin of safety when setting soil quality standards for ecological risk assessment.

  11. Orbital physics in transition-metal oxides

    PubMed

    Tokura; Nagaosa

    2000-04-21

    An electron in a solid, that is, bound to or nearly localized on the specific atomic site, has three attributes: charge, spin, and orbital. The orbital represents the shape of the electron cloud in solid. In transition-metal oxides with anisotropic-shaped d-orbital electrons, the Coulomb interaction between the electrons (strong electron correlation effect) is of importance for understanding their metal-insulator transitions and properties such as high-temperature superconductivity and colossal magnetoresistance. The orbital degree of freedom occasionally plays an important role in these phenomena, and its correlation and/or order-disorder transition causes a variety of phenomena through strong coupling with charge, spin, and lattice dynamics. An overview is given here on this "orbital physics," which will be a key concept for the science and technology of correlated electrons.

  12. Chemical Sensors Based on Metal Oxide Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

    2006-01-01

    This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

  13. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    DOE PAGES

    Luo, Hongmei; Lin, Qianglu; Baber, Stacy; ...

    2010-01-01

    We demore » monstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta 2 O 5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses.« less

  14. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, M.A.; Webster, E.T.; Xu, Q.

    1994-08-30

    A method for formation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation. 4 figs.

  15. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, Marc A.; Webster, Elizabeth T.; Xu, Qunyin

    1994-01-01

    A method for permformation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation.

  16. Preferential orientation of metal oxide superconducting materials

    DOEpatents

    Capone, Donald W.; Poeppel, Roger B.

    1991-01-01

    A polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0

  17. Destructive Clustering of Metal Nanoparticles in Chalcogenide and Oxide Glassy Matrices.

    PubMed

    Shpotyuk, M V; Shpotyuk, O I; Cebulski, J; Kozyukhin, S

    2016-12-01

    The energetic χ-criterion is developed to parameterize difference in the origin of high-order optical non-linearity associated with metallic atoms (Cu, Ag, Au) embedded destructively in oxide- and chalcogenide glasses. Within this approach, it is unambiguously proved that covalent-bonded networks of soft semiconductor chalcogenides exemplified by binary As(Ge)-S(Se) glasses differ essentially from those typical for hard dielectric oxides like vitreous silica by impossibility to accommodate pure agglomerates of metallic nanoparticles. In an excellence according to known experimental data, it is suggested that destructive clustering of nanoparticles is possible in Cu-, Ag-, and Au-ion-implanted dielectric oxide glass media, possessing a strongly negative χ-criterion. Some recent speculations trying to ascribe equally this ability to soft chalcogenide glasses despite an obvious difference in the corresponding bond dissociation energies have been disclosed and criticized as inconclusive.

  18. Structure-Reactivity Relationships in Multi-Component Transition Metal Oxide Catalysts FINAL Report

    SciTech Connect

    Altman, Eric I.

    2015-10-06

    The focus of the project was on developing an atomic-level understanding of how transition metal oxide catalysts function. Over the course of several renewals the specific emphases shifted from understanding how local structure and oxidation state affect how molecules adsorb and react on the surfaces of binary oxide crystals to more complex systems where interactions between different transition metal oxide cations in an oxide catalyst can affect reactivity, and finally to the impact of cluster size on oxide stability and reactivity. Hallmarks of the work were the use of epitaxial growth methods to create surfaces relevant to catalysis yet tractable for fundamental surface science approaches, and the use of scanning tunneling microscopy to follow structural changes induced by reactions and to pinpoint adsorption sites. Key early findings included the identification of oxidation and reduction mechanisms on a tungsten oxide catalyst surface that determine the sites available for reaction, identification of C-O bond cleavage as the rate limiting step in alcohol dehydration reactions on the tungsten oxide surface, and demonstration that reduction does not change the favored reaction pathway but rather eases C-O bond cleavage and thus reduces the reaction barrier. Subsequently, a new reconstruction on the anatase phase of TiO2 relevant to catalysis was discovered and shown to create sites with distinct reactivity compared to other TiO2 surfaces. Building on this work on anatase, the mechanism by which TiO2 enhances the reactivity of vanadium oxide layers was characterized and it was found that the TiO2 substrate can force thin vanadia layers to adopt structures they would not ordinarily form in the bulk which in turn creates differences in reactivity between supported layers and bulk samples. From there, the work progressed to studying well-defined ternary oxides where synergistic effects between the two cations can induce

  19. Electrostatic potentials for metal-oxide surfaces and interfaces

    NASA Astrophysics Data System (ADS)

    Streitz, F. H.; Mintmire, J. W.

    1994-10-01

    As most technologically important metals will form oxides readily, any complete study of adhesion at real metal surfaces must include the metal-oxide interface. The role of this ubiquitous oxide layer cannot be overlooked, as the adhesive properties of the oxide or oxide-metal system can be expected to differ profoundly from the adhesive properties of a bare metal surface. We report on the development of a computational method for molecular-dynamics simulations, which explicitly includes variable charge transfer between anions and cations. This method is found to be capable of describing the elastic properties, surface energies, and surface relaxation of crystalline metal oxides accurately. We discuss in detail results using this method for α-alumina and several of its low-index faces.

  20. Method of making controlled morphology metal-oxides

    DOEpatents

    Ozcan, Soydan; Lu, Yuan

    2016-05-17

    A method of making metal oxides having a preselected morphology includes preparing a suspension that includes a solvent, polymeric nanostructures having multiplicities of hydroxyl surface groups and/or carboxyl surface groups, and a metal oxide precursor. The suspension has a preselected ratio of the polymeric nanostructures to the metal oxide precursor of at least 1:3, the preselected ratio corresponding to a preselected morphology. Subsequent steps include depositing the suspension onto a substrate, removing the solvent to form a film, removing the film from the substrate, and annealing the film to volatilize the polymeric nanostructures and convert the metal oxide precursor to metal oxide nanoparticles having the preselected morphology or to a metal oxide nanosheet including conjoined nanoparticles having the preselected morphology.

  1. Magnesium oxide for improved heavy metals removal

    SciTech Connect

    Schiller, J.E.; Khalafalla, S.E.

    1984-01-01

    To improve technology for treating process water, US Bureau of Mines research has shown that magnesium oxide (MgO) has many advantages over lime or caustic soda for precipitating heavy metals. Sludge produced by MgO occupies only 0.2-0.3 times as much volume as the precipitate made using a soluble base. While a settled, lime-formed precipitate is easily resuspended, the MgO-metal hydroxide sludge becomes cemented together on standing. Settling of the metal hydroxides from a dilute suspension is more complete than precipitates formed with other bases. Virtually any metal that can be precipitated by raising the pH can be treated using MgO. A three-fold to four-fold stoichiometric excess of solid reagent is added. The mixture is reacted for five to 10 minutes. Polymer is added, and settling or filtration completes the process. Because of the greater cost of MgO compared with lime, large-scale practice of this technology will probably be limited to water containing 50 mg/L (3 gr per gal) or less of dissolved metals. For such dilute solutions, chemicals are not a large fraction of total treatment costs, so more desirable sludge properties might justify higher chemical expenses. While the MgO process is technically suitable for widespread application, the extent to which it is adopted will probably be determined by a trade-off between the greater cost of MgO compared with lime and the superior properties of the precipitates and their corresponding ultimate disposal costs.

  2. Simple transition metal oxides (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Schuller, Ivan K.; Basaran, Ali C.; de la Venta, Jose; Ramirez, Juan Gabriel; Saerbeck, Thomas; Valmianski, Ilya; Wang, Siming

    2016-10-01

    Hybrid materials allow the engineering of new material properties by creative uses of proximity effects. When two dissimilar materials are in close physical proximity the properties of each one may be radically modified or occasionally a completely new material emerges. In the area of magnetism, controlling the magnetic properties of ferromagnetic thin films without magnetic fields is an on- going challenge with multiple technological implications for low- energy consumption memory and logic devices. Interesting possibilities include ferromagnets in proximity to dissimilar materials such as antiferromagnets or oxides that undergo metal-insulator transitions. The proximity of ferromagnets to antiferromagnets has given rise to the extensively studied Exchange Bias[1]. Our recent investigations in this field have addressed crucial issues regarding the importance of the antiferromagnetic [2-3] and ferromagnetic [4] bulk for the Exchange Bias and the unusual short time dynamics [5]. In a series of recent studies, we have investigated the magnetic properties of different hybrids of ferromagnets (Ni, Co and Fe) and oxides, which undergo metal-insulator and structural phase transitions. Both the static as well as dynamical properties of the ferromagnets are drastically affected. Static properties such as the coercivity, anisotropy and magnetization [6-8] and dynamical properties such as the microwave response are clearly modified by the proximity effect and give raise to interesting perhaps useful properties. Work supported by US-AFOSR and US-DOE

  3. Preparation and characterization of iron-copper binary oxide and its effective removal of antimony(III) from aqueous solution.

    PubMed

    Li, Yongchao; Geng, Bing; Hu, Xiaoxian; Ren, Bozhi; Hursthouse, Andrew S

    An Fe-Cu binary oxide was fabricated through a simple co-precipitation process, and was used to remove Sb(III) from aqueous solution. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and N2 adsorption-desorption measurements demonstrated that the Fe-Cu binary oxide consisted of poorly ordered ferrihydrite and CuO, and its specific surface area was higher than both iron oxide and copper oxide. A comparative test indicated that Fe/Cu molar ratio of prepared binary oxide greatly influenced Sb(III) removal and the optimum Fe/Cu molar ratio was about 3/1. Moreover, a maximum adsorption capacity of 209.23 mg Sb(III)/g Fe-Cu binary oxide at pH 5.0 was obtained. The removal of Sb(III) by Fe-Cu binary oxide followed the Freundlich adsorption isotherm and the pseudo-second-order kinetics in the batch study. The removal of Sb(III) was not sensitive to solution pH. In addition, the release of Fe and Cu ions to water was very low when the pH was greater than 6.0. X-ray photoelectron spectroscopy analysis confirmed that the Sb(III) adsorbed on the surface was not oxidized to Sb(V).

  4. Fluidized reduction of oxides on fine metal powders without sintering

    NASA Technical Reports Server (NTRS)

    Hayashi, T.

    1985-01-01

    In the process of reducing extremely fine metal particles (av. particle size or = 1000 angstroms) covered with an oxide layer, the metal particles are fluidized by a gas flow contg. H, heated, and reduced. The method uniformly and easily reduces surface oxide layers of the extremely fine metal particles without causing sintering. The metal particles are useful for magnetic recording materials, conductive paste, powder metallurgy materials, chem. reagents, and catalysts.

  5. One-dimensional metal oxide nanostructures for heterogeneous catalysis.

    PubMed

    Zhang, Qian; Wang, Hsin-Yi; Jia, Xinli; Liu, Bin; Yang, Yanhui

    2013-08-21

    Metal oxides are of paramount importance in heterogeneous catalysis as either supports or active phases. Controlled synthesis of one-dimensional (1D) metal oxide nanostructures has received enormous attention in heterogeneous catalysis due to the possibility of tailoring the properties of metal oxides by tuning their shapes, sizes, and compositions. This feature article highlights recent advances in shape controlled synthesis of 1D metal oxide nanostructures and their applications in heterogeneous catalysis, with the aim of introducing new insights into the heterogeneous catalyst design.

  6. Ultrasmall PdmMn1-mOx binary alloyed nanoparticles on graphene catalysts for ethanol oxidation in alkaline media

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad Shamsuddin; Park, Dongchul; Jeon, Seungwon

    2016-03-01

    A rare combination of graphene (G)-supported palladium and manganese in mixed-oxides binary alloyed catalysts (BACs) have been synthesized with the addition of Pd and Mn metals in various ratios (G/PdmMn1-mOx) through a facile wet-chemical method and employed as an efficient anode catalyst for ethanol oxidation reaction (EOR) in alkaline fuel cells. The as prepared G/PdmMn1-mOx BACs have been characterized by several instrumental techniques; the transmission electron microscopy images show that the ultrafine alloyed nanoparticles (NPs) are excellently monodispersed onto the G. The Pd and Mn in G/PdmMn1-mOx BACs have been alloyed homogeneously, and Mn presents in mixed-oxidized form that resulted by X-ray diffraction. The electrochemical performances, kinetics and stability of these catalysts toward EOR have been evaluated using cyclic voltammetry in 1 M KOH electrolyte. Among all G/PdmMn1-mOx BACs, the G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and incredible stability than that of pure Pd catalysts (G/Pd1Mn0Ox, Pd/C and Pt/C). The well dispersion, ultrafine size of NPs and higher degree of alloying are the key factor for enhanced and stable EOR electrocatalysis on G/Pd0.5Mn0.5Ox.

  7. Microwave properties of thermochromic metal oxide surfaces

    NASA Astrophysics Data System (ADS)

    Ousbäck, Jan-Olof; Kariis, Hans

    2006-09-01

    Thermochromic metal oxides with a Mott transition, such as vanadium dioxide (VO II) exhibit an extensive alteration in their infrared reflectivity when heated above the transition temperature. For VO II the infrared reflectivity increases as the material becomes more metal-like above the transition temperature at 68°C. Given these dynamic electromagnetic properties in the IR-range, it is interesting to study the reflection of the material also in other wavelength ranges. The microwave properties of VO II as a function of temperature have been investigated here. Measurements were made with an automated network analyzer combined with an electrical heating unit. Reflection properties of VO II in the microwave region were determined. Above the transition temperature, an increase in the reflection of the surface was observed. The VO II became more metal-like in the whole measured microwave frequency range, as in the infrared region. It is concluded that VO II not only can be used to adapt the thermal emissivity of a surface but also to control the microwave reflectivity. Possible applications are switchable radomes, switchable radarabsorbers and heat protection for antenna apertures.

  8. Method of producing solution-derived metal oxide thin films

    DOEpatents

    Boyle, Timothy J.; Ingersoll, David

    2000-01-01

    A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  9. Method of producing solution-derived metal oxide thin films

    SciTech Connect

    Boyle, T.J.; Ingersoll, D.

    2000-07-11

    A method is described for preparing metal oxide thin films by a solution method. A {beta}-metal {beta}-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  10. Effects of NOM on oxidative reactivity of manganese dioxide in binary oxide mixtures with goethite or hematite.

    PubMed

    Zhang, Huichun; Taujale, Saru; Huang, Jianzhi; Lee, Gang-Juan

    2015-03-10

    MnO2 typically coexists with iron oxides as either discrete particles or coatings in soils and sediments. This work examines the effect of Aldrich humic acid (AHA), alginate, and pyromellitic acid (PA) as representative natural organic matter (NOM) analogues on the oxidative reactivity of MnO2, as quantified by pseudo-first-order rate constants of triclosan oxidation, in mixtures with goethite or hematite. Adsorption studies showed that there was low adsorption of the NOMs by MnO2, but high (AHA and alginate) to low (PA) adsorption by the iron oxides. Based on the ATR-FTIR spectra obtained for the adsorbed PA on goethite or goethite + MnO2, the adsorption of PA occurred mainly through formation of outer-sphere complexes. The Fe oxides by themselves inhibited MnO2 reactivity through intensive heteroaggregation between the positively charged Fe oxides and the negatively charged MnO2; the low solubility of the iron oxides limited surface complexation of soluble Fe(3+) with MnO2. In ternary mixtures of MnO2, Fe oxides, and NOM analogues, the reactivity of MnO2 varied from inhibited to promoted as compared with that in the respective MnO2 + NOM binary mixtures. The dominant interaction mechanisms include an enhanced extent of homoaggregation within the Fe oxides due to formation of oppositely charged patches within the Fe oxides but an inhibited extent of heteroaggregation between the Fe oxide and MnO2 at [AHA] < 2-4 mg-C/L or [alginate/PA] < 5-10 mg/L, and an inhibited extent of heteroaggregation due to the largely negatively charged surfaces for all oxides at [AHA] > 4 mg-C/L or [alginate/PA] > 10 mg/L.

  11. Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials

    SciTech Connect

    Gash, A; Pantoya, M; Jr., J S; Zhao, L; Shea, K; Simpson, R; Clapsaddle, B

    2003-11-18

    In the field of composite energetic materials, properties such as ingredient distribution, particle size, and morphology, affect both sensitivity and performance. Since the reaction kinetics of composite energetic materials are typically controlled by the mass transport rates between reactants, one would anticipate new and potentially exceptional performance from energetic nanocomposites. We have developed a new method of making nanostructured energetic materials, specifically explosives, propellants, and pyrotechnics, using sol-gel chemistry. A novel sol-gel approach has proven successful in preparing metal oxide/silicon oxide nanocomposites in which the metal oxide is the major component. Two of the metal oxides are tungsten trioxide and iron(III) oxide, both of which are of interest in the field of energetic materials. Furthermore, due to the large availability of organically functionalized silanes, the silicon oxide phase can be used as a unique way of introducing organic additives into the bulk metal oxide materials. As a result, the desired organic functionality is well dispersed throughout the composite material on the nanoscale. By introducing a fuel metal into the metal oxide/silicon oxide matrix, energetic materials based on thermite reactions can be fabricated. The resulting nanoscale distribution of all the ingredients displays energetic properties not seen in its microscale counterparts due to the expected increase of mass transport rates between the reactants. The synthesis and characterization of these metal oxide/silicon oxide nanocomposites and their performance as energetic materials will be discussed.

  12. Reactive metal-oxide interfaces: A microscopic view

    NASA Astrophysics Data System (ADS)

    Picone, A.; Riva, M.; Brambilla, A.; Calloni, A.; Bussetti, G.; Finazzi, M.; Ciccacci, F.; Duò, L.

    2016-03-01

    Metal-oxide interfaces play a fundamental role in determining the functional properties of artificial layered heterostructures, which are at the root of present and future technological applications. Magnetic exchange and magnetoelectric coupling, spin filtering, metal passivation, catalytic activity of oxide-supported nano-particles are just few examples of physical and chemical processes arising at metal-oxide hybrid systems, readily exploited in working devices. These phenomena are strictly correlated with the chemical and structural characteristics of the metal-oxide interfacial region, making a thorough understanding of the atomistic mechanisms responsible of its formation a prerequisite in order to tailor the device properties. The steep compositional gradient established upon formation of metal-oxide heterostructures drives strong chemical interactions at the interface, making the metal-oxide boundary region a complex system to treat, both from an experimental and a theoretical point of view. However, once properly mastered, interfacial chemical interactions offer a further degree of freedom for tuning the material properties. The goal of the present review is to provide a summary of the latest achievements in the understanding of metal/oxide and oxide/metal layered systems characterized by reactive interfaces. The influence of the interface composition on the structural, electronic and magnetic properties will be highlighted. Particular emphasis will be devoted to the discussion of ultra-thin epitaxial oxides stabilized on highly oxidizable metals, which have been rarely exploited as oxide supports as compared to the much more widespread noble and quasi noble metallic substrates. In this frame, an extensive discussion is devoted to the microscopic characterization of interfaces between epitaxial metal oxides and the Fe(001) substrate, regarded from the one hand as a prototypical ferromagnetic material and from the other hand as a highly oxidizable metal.

  13. Synthesis and control of morphology, stoichiometry, and composition of transition metal oxides

    NASA Astrophysics Data System (ADS)

    Brier, Matthew Isaac

    Transition metal oxides (TMOs) are an important class of materials that have found uses in diverse applications, such as heterogeneous catalysts, sensors, and high temperature superconductors, due to their complex surface chemistry and high mobility of lattice oxygen atoms. Point defects such as oxygen and metal atom vacancies significantly perturb the electronic structure of TMOs and profoundly impact their electrical, optical, ferroelectric, photocatalytic, and other functional properties. As a result, significant research is being done to develop synthesis techniques that can produce metal oxides with controllable material properties. In this thesis, the use of hot wire chemical vapor deposition (HWCVD) was studied with the aim of precisely controlling the morphology, stoichiometry, and composition of TMOs. With molybdenum oxide as the model system, the control of morphology and stoichiometry was achieved by modulation of deposition parameters, such as filament power and gas phase composition. The study of HWCVD of MoOx led to the development of phase diagrams for the dependence of morphology and stoichiometry on deposition parameters. The knowledge gained studying the HWCVD of MoOx was then shown to translate to the deposition of other binary metal oxides by using tungsten, nickel, and vanadium metal filaments to synthesize their respective transition metal oxides. Additionally, NiMoO4 was synthesized as a proof-of-concept to show that HWCVD can be used to make ternary oxides. Nitridation of samples in an ammonia atmosphere was conducted to explore the potential for conversion of HWCVD grown TMOs to their respective metal nitrides, which are also reported to have catalytic properties. To examine the quality of TMOs grown by HWCVD, samples were electrochemically tested for their electrochromic properties and photoactivity with respect to splitting of water.

  14. Photocatalytic activity of nanostructured ZnO-ZrO2 binary oxide using fluorometric method

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. M.

    2015-06-01

    Evaluation of the photocatalytic activity of ZnO-ZrO2 nanomaterials using fluorescence based technique has rarely been reported. In the present work, ZnO-ZrO2 mixed oxides coupled with various ZnO dosages (0, 10, 30, 50, 70 wt%) were prepared by impregnation method. These nanomaterials were characterized by studying their structural, surface and optical properties. The photocatalytic activity in term of quantitative determination of the active oxidative species (radOH) produced on the surface of binary oxide was evaluated using fluorescent probe method. The interaction between ZnO and ZrO2 was affected on the photocatalytic efficiency of mixture. The results show that, the addition of ZnO to ZrO2 decreased the electron-hole recombination and increased the rate of radOH radicals formation. 50 wt% ZnO-ZrO2 photocatalyst exhibited much higher photocatalytic activity. The profound effect of binary oxide catalyst was generally considered due to the high surface area, small particle size, high monoclinic phase of ZrO2 content, low band gap and the presence of surface OH groups.

  15. Fluorine in carbon-enhanced metal-poor stars: a binary scenario

    NASA Astrophysics Data System (ADS)

    Lugaro, M.; de Mink, S. E.; Izzard, R. G.; Campbell, S. W.; Karakas, A. I.; Cristallo, S.; Pols, O. R.; Lattanzio, J. C.; Straniero, O.; Gallino, R.; Beers, T. C.

    2008-06-01

    Aims: A super-solar fluorine abundance was observed in the carbon-enhanced metal-poor (CEMP) star HE 1305+0132 ([F/Fe] = +2.90, [Fe/H] = -2.5). We propose that this observation can be explained using a binary model that involve mass transfer from an asymptotic giant branch (AGB) star companion and, based on this model, we predict F abundances in CEMP stars in general. We discuss wether F can be used to discriminate between the formation histories of most CEMP stars: via binary mass transfer or from the ejecta of fast-rotating massive stars. Methods: We compute AGB yields using different stellar evolution and nucleosynthesis codes to evaluate stellar model uncertainties. We use a simple dilution model to determine the factor by which the AGB yields should be diluted to match the abundances observed in HE 1305+0132. We further employ a binary population synthesis tool to estimate the probability of F-rich CEMP stars. Results: The abundances observed in HE 1305+0132 can be explained if this star accreted 3-11% of the mass lost by its former AGB companion. The primary AGB star should have dredged-up at least 0.2 {M}⊙ of material from its He-rich region into the convective envelope via third dredge-up, which corresponds to AGB models of Z ≃ 0.0001 and mass ≃2 {M}⊙. Many AGB model uncertainties, such as the treatment of convective borders and mass loss, require further investigation. We find that in the binary scenario most CEMP stars should also be FEMP stars, that is, have [F/Fe] > +1, while fast-rotating massive stars do not appear to produce fluorine. We conclude that fluorine is a signature of low-mass AGB pollution in CEMP stars, together with elements associated with the slow neutron-capture process.

  16. Analysis of self-propagating intermetallic reaction in nanoscale multilayers of binary metals

    NASA Astrophysics Data System (ADS)

    Kim, Kyoungjin

    2017-03-01

    Nanoscale multilayers of two different metals could exhibit super-fast intermetallic reaction wave that accompanies high level of exothermic heat release, while additional advantage is a very small ignition delay. They could be a promising candidate for the core technology in realizing micron-sized initiation device for explosives detonation or propellants ignition in various defense and civilian applications. This numerical investigation focuses on the numerical modeling and computations of the ignition and self-propagating reaction behaviors in nanoscale intermetallic multilayer structures made of alternating binary metal layers of boron and titanium. Due to thin film nature of metallic multilayers, intermetallic reaction propagation across the repeating bimetallic multilayers is approximated to the one-dimensional transient model of thermal diffusion and atomic species diffusion, and the intermetallic reaction between two metal species is assumed to follow Arrhenius dependence on temperature. The computational results show the details of ignition and propagation characteristics of intermetallic reaction wave by evaluating and discussing the effects of key parameters, such as multilayer thickness, excess of one metal species, and presence of atomic premixing at interface of boron and titanium layers, on ignition delay and propagation speed of self-sustaining reaction wave.

  17. The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

    NASA Astrophysics Data System (ADS)

    Carnes, Corrie Leigh

    The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

  18. The Intriguing Properties of Transition Metal Oxides

    NASA Astrophysics Data System (ADS)

    Hoch, Michael J. R.

    2007-05-01

    Since the discovery of high-temperature superconductivity in the cuprates twenty years ago, there has been a resurgence of interest in the transition metal oxides. Work on these systems has been driven both by the fascinating properties that these materials exhibit and by potential applications in technology. A brief general review of the perovskites and their electronic structures is given. This is followed by a discussion of the properties of magnetic oxide systems ABO3 (A=La; B=Mn or Co), specifically focusing on the doped manganites (e.g. La1-x SrxMnO3) and cobaltites (e.g. La1-xSrxCoO3), in which mixed valence states and double exchange are important. Competing electron localizing and delocalizing effects result in rich phase diagrams and interesting transport properties with large magnetoresistance effects. Nanoscale phase separation has been found for a range of x values using a variety of techniques, such as nuclear magnetic resonance and neutron scattering. These discoveries have provided an increased understanding of the role of the interacting magnetic, electronic and lattice structures in these systems.

  19. Influence of metal oxides on the adsorption characteristics of PPy/metal oxides for Methylene Blue.

    PubMed

    Chen, Jie; Feng, Jiangtao; Yan, Wei

    2016-08-01

    In this paper, the pure PPy and PPy/metal oxide composites including PPy/SiO2, PPy/Al2O3, and PPy/Fe3O4 as well as PPy coated commercial SiO2 and Al2O3 (PPy/SiO2(C) and PPy/Al2O3(C)) were successfully synthetized via chemical oxidative polymerization in acid aqueous medium to investigate the influence of metal oxides on adsorption capacity and their adsorption characteristics for Methylene Blue (MB). The composites were characterized by Zeta potential analysis, BET analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The results indicate that the metal oxides have great impact on textural properties, morphology, Zeta potential and PPy polymerization on their surface, further influence the adsorption capacity of their composites. The PPy/Al2O3(C) composite owns the highest specific surface area, rougher surface and most PPy content, and show the highest monolayer adsorption capacity reaching 134.77mg/g. In the adsorption characteristic studies, isotherm investigation shows an affinity order of PPy/metal oxides of PPy/Al2O3(C)>PPy/Al2O3>PPy/SiO2(C)>PPy/SiO2>PPy/Fe3O4>PPy, stating the affinity between PPy and MB was greatly improved by metal oxide, and Al2O3 owns high affinity for MB, followed by SiO2 and Fe3O4. Kinetic data of the composites selected (PPy/SiO2(C), PPy/Al2O3(C) and PPy/Fe3O4) were described more appropriately by the pseudo-second-order model, and the order of K2 is PPy/Al2O3>PPy/SiO2>PPy/Fe3O4, further showing a fast adsorption and good affinity of PPy/Al2O3(C) for MB. The regeneration method by HCl-elution and NaOH-activation was available, and the composites selected still owned good adsorption and desorption efficiency after six adsorption-desorption cycles.

  20. THE EFFECT OF STARBURST METALLICITY ON BRIGHT X-RAY BINARY FORMATION PATHWAYS

    SciTech Connect

    Linden, T.; Kalogera, V.; Sepinsky, J. F.; Prestwich, A.; Zezas, A.; Gallagher, J. S.

    2010-12-20

    We investigate the characteristics of young (<20 Myr) and bright (L{sub X} > 1 x 10{sup 36} erg s{sup -1}) high-mass X-ray binaries (HMXBs) and find the population to be strongly metallicity dependent. We separate the model populations among two distinct formation pathways: (1) systems undergoing active Roche lobe overflow (RLO) and (2) wind accretion systems with donors in the (super)giant stage, which we find to dominate the HMXB population. We find metallicity to primarily affect the number of systems which move through each formation pathway, rather than the observable parameters of systems which move through each individual pathway. We discuss the most important model parameters affecting the HMXB population at both low and high metallicities. Using these results, we show that (1) the population of ultra-luminous X-ray sources can be consistently described by very bright HMXBs which undergo stable RLO with mild super-Eddington accretion and (2) the HMXB population of the bright starburst galaxy NGC 1569 is likely dominated by one extremely metal-poor starburst cluster.

  1. Degradation mechanisms and stability forecasting and adhesion contacts of metal films with binary dielectric substrates

    SciTech Connect

    Stolyarova, S.; Nemirovsky, Y.; Simanovskis, A.

    1996-12-31

    In this paper the authors present their conception of degradation and stability on the adhesion contacts of metal films with binary nonmetallic crystals. There are numerous works devoted to the atomic scale determination of adhesion forces and development of adhesion interaction laws. But in the real life the kinetic processes, taking place on the adhesion contact, can lead to such dramatic changes in adhesion strength values that the initial adhesion characteristics do not worth much for practice. Sometimes, adhesion contact with a metal which supposed to be highly adhesive failes in a short period of aging time. What the authors have learned from their studies of the contact processes is that in many cases the aging could not be separately addressed to the individual properties of film metal or to those of the substrate material. It depends mainly on the relationships between the parameters of interacting pair. The question is: what parameters should be taken into account to explain degradation phenomena and to predict them? The purpose of the present work is to show how the relative chemical activity of film metal and substrate cation affects the contact degradation in a vacuum and in different environmental conditions.

  2. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1991-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  3. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1992-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  4. The close binary properties of massive stars in the Milky Way and low-metallicity Magellanic Clouds

    SciTech Connect

    Moe, Maxwell; Di Stefano, Rosanne

    2013-12-01

    In order to understand the rates and properties of Type Ia and Type Ib/c supernovae, X-ray binaries, gravitational wave sources, and gamma-ray bursts as a function of galactic environment and cosmic age, it is imperative that we measure how the close binary properties of O- and B-type stars vary with metallicity. We have studied eclipsing binaries with early B main-sequence primaries in three galaxies with different metallicities: the Large and Small Magellanic Clouds (LMC and SMC, respectively) and the Milky Way (MW). The observed fractions of early B stars that exhibit deep eclipses 0.25 < Δm (mag) < 0.65 and orbital periods 2 < P (days) < 20 in the MW, LMC, and SMC span a narrow range of (0.7-1.0)%, which is a model-independent result. After correcting for geometrical selection effects and incompleteness toward low-mass companions, we find for early B stars in all three environments (1) a close binary fraction of (22 ± 5)% across orbital periods 2 < P (days) < 20 and mass ratios q = M {sub 2}/M {sub 1} > 0.1, (2) an intrinsic orbital period distribution slightly skewed toward shorter periods relative to a distribution that is uniform in log P, (3) a mass-ratio distribution weighted toward low-mass companions, and (4) a small, nearly negligible excess fraction of twins with q > 0.9. Our fitted parameters derived for the MW eclipsing binaries match the properties inferred from nearby, early-type spectroscopic binaries, which further validates our results. There are no statistically significant trends with metallicity, demonstrating that the close binary properties of massive stars do not vary across metallicities –0.7 < log(Z/Z {sub ☉}) < 0.0 beyond the measured uncertainties.

  5. Laboratory studies of refractory metal oxide smokes

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.; Nelson, R. N.; Donn, Bertram

    1989-01-01

    Studies of the properties of refractory metal oxide smokes condensed from a gas containing various combinations of SiH4, Fe(CO)5, Al(CH3)3, TiCl4, O2 and N2O in a hydrogen carrier stream at 500 K greater than T greater than 1500 K were performed. Ultraviolet, visible and infrared spectra of pure, amorphous SiO(x), FeO(x), AlO(x) and TiO(x) smokes are discussed, as well as the spectra of various co-condensed amorphous oxides, such as FE(x)SiO(y) or Fe(x)AlO(y). Preliminary studies of the changes induced in the infrared spectra of iron-containing oxide smokes by vacuum thermal annealing suggest that such materials become increasingly opaque in the near infrared with increased processing: hydration may have the opposite effect. More work on the processing of these materials is required to confirm such a trend: this work is currently in progress. Preliminary studies of the ultraviolet spectra of amorphous Si2O3 and MgSiO(x) smokes revealed no interesting features in the region from 200 to 300 nm. Studies of the ultraviolet spectra of both amorphous, hydrated and annealed SiO(x), TiO(x), AlO(x) and FeO(x) smokes are currently in progress. Finally, data on the oxygen isotopic composition of the smokes produced in the experiments are presented, which indicate that the oxygen becomes isotopically fractionated during grain condensation. Oxygen in the grains is as much as 3 percent per amu lighter than the oxygen in the original gas stream. The authors are currently conducting experiments to understand the mechanism by which fractionation occurs.

  6. The MSFC complementary metal oxide semiconductor (including multilevel interconnect metallization) process handbook

    NASA Technical Reports Server (NTRS)

    Bouldin, D. L.; Eastes, R. W.; Feltner, W. R.; Hollis, B. R.; Routh, D. E.

    1979-01-01

    The fabrication techniques for creation of complementary metal oxide semiconductor integrated circuits at George C. Marshall Space Flight Center are described. Examples of C-MOS integrated circuits manufactured at MSFC are presented with functional descriptions of each. Typical electrical characteristics of both p-channel metal oxide semiconductor and n-channel metal oxide semiconductor discrete devices under given conditions are provided. Procedures design, mask making, packaging, and testing are included.

  7. Solder for oxide layer-building metals and alloys

    DOEpatents

    Kronberg, J.W.

    1992-09-15

    A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel is disclosed. The composition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than approximately 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300 C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

  8. Solder for oxide layer-building metals and alloys

    DOEpatents

    Kronberg, James W.

    1992-01-01

    A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel. The comosition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than aproximatley 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300.degree. C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

  9. First Principles Calculations of Transition Metal Binary Alloys: Phase Stability and Surface Effects

    NASA Astrophysics Data System (ADS)

    Aspera, Susan Meñez; Arevalo, Ryan Lacdao; Shimizu, Koji; Kishida, Ryo; Kojima, Kazuki; Linh, Nguyen Hoang; Nakanishi, Hiroshi; Kasai, Hideaki

    2017-03-01

    The phase stability and surface effects on binary transition metal nano-alloy systems were investigated using density functional theory-based first principles calculations. In this study, we evaluated the cohesive and alloying energies of six binary metal alloy bulk systems that sample each type of alloys according to miscibility, i.e., Au-Ag and Pd-Ag for the solid solution-type alloys (SS), Pd-Ir and Pd-Rh for the high-temperature solid solution-type alloys (HTSS), and Au-Ir and Ag-Rh for the phase-separation (PS)-type alloys. Our results and analysis show consistency with experimental observations on the type of materials in the bulk phase. Varying the lattice parameter was also shown to have an effect on the stability of the bulk mixed alloy system. It was observed, particularly for the PS- and HTSS-type materials, that mixing gains energy from the increasing lattice constant. We furthermore evaluated the surface effects, which is an important factor to consider for nanoparticle-sized alloys, through analysis of the (001) and (111) surface facets. We found that the stability of the surface depends on the optimization of atomic positions and segregation of atoms near/at the surface, particularly for the HTSS and the PS types of metal alloys. Furthermore, the increase in energy for mixing atoms at the interface of the atomic boundaries of PS- and HTSS-type materials is low enough to overcome by the gain in energy through entropy. These, therefore, are the main proponents for the possibility of mixing alloys near the surface.

  10. High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

    SciTech Connect

    Scalettar, Richard T.; Pickett, Warren E.

    2004-07-01

    This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

  11. High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

    SciTech Connect

    Richard T. Scalettar; Warren E. Pickett

    2005-08-02

    This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

  12. Selective Metallization Induced by Laser Activation: Fabricating Metallized Patterns on Polymer via Metal Oxide Composite.

    PubMed

    Zhang, Jihai; Zhou, Tao; Wen, Liang

    2017-02-28

    Recently, metallization on polymer substrates has been given more attention due to its outstanding properties of both plastics and metals. In this study, the metal oxide composite of copper-chromium oxide (CuO·Cr2O3) was incorporated into the polymer matrix to design a good laser direct structuring (LDS) material, and the well-defined copper pattern (thickness =10 μm) was successfully fabricated through selective metallization based on 1064 nm near-infrared pulsed laser activation and electroless copper plating. We also prepared polymer composites incorporated with CuO and Cr2O3; however, these two polymer composites both had very poor capacity of selective metallization, which has no practical value for LDS technology. In our work, the key reasons causing the above results were systematically studied and elucidated using XPS, UV-vis-IR, optical microscopy, SEM, contact angle, ATR FTIR, and so on. The results showed that 54.0% Cu(2+) in the polymer composite of CuO·Cr2O3 (the amount =5 wt %) is reduced to Cu(0) (elemental copper) after laser activation (irradiation); however, this value is only 26.8% for the polymer composite of CuO (the amount =5 wt %). It was confirmed that to achieve a successful selective metallization after laser activation, not only was the new formed Cu(0) (the catalytic seeds) the crucial factor, but the number of generated Cu(0) catalytic seeds was also important. These two factors codetermined the final results of the selective metallization. The CuO·Cr2O3 is very suitable for applications of fabricating metallic patterns (e.g., metal decoration, circuit) on the inherent pure black or bright black polymer materials via LDS technology, which has a prospect of large-scale industrial applications.

  13. Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems.

    PubMed

    Niu, Gang; Zoellner, Marvin Hartwig; Schroeder, Thomas; Schaefer, Andreas; Jhang, Jin-Hao; Zielasek, Volkmar; Bäumer, Marcus; Wilkens, Henrik; Wollschläger, Joachim; Olbrich, Reinhard; Lammers, Christian; Reichling, Michael

    2015-10-14

    Rare earth praseodymium and cerium oxides have attracted intense research interest in the last few decades, due to their intriguing chemical and physical characteristics. An understanding of the correlation between structure and properties, in particular the surface chemistry, is urgently required for their application in microelectronics, catalysis, optics and other fields. Such an understanding is, however, hampered by the complexity of rare earth oxide materials and experimental methods for their characterisation. Here, we report recent progress in studying high-quality, single crystalline, praseodymium and cerium oxide films as well as ternary alloys grown on Si(111) substrates. Using these well-defined systems and based on a systematic multi-technique surface science approach, the corresponding physical and chemical properties, such as the surface structure, the surface morphology, the bulk-surface interaction and the oxygen storage/release capability, are explored in detail. We show that specifically the crystalline structure and the oxygen stoichiometry of the oxide thin films can be well controlled by the film preparation method. This work leads to a comprehensive understanding of the properties of rare earth oxides and highlights the applications of these versatile materials. Furthermore, methanol adsorption studies are performed on binary and ternary rare earth oxide thin films, demonstrating the feasibility of employing such systems for model catalytic studies. Specifically for ceria systems, we find considerable stability against normal environmental conditions so that they can be considered as a "materials bridge" between surface science models and real catalysts.

  14. Effects of binary mixtures of benzo[a]pyrene, arsenic, cadmium, and lead on oxidative stress and toxicity in HepG2 cells.

    PubMed

    Muthusamy, Sasikumar; Peng, Cheng; Ng, Jack C

    2016-12-01

    Mixed contamination of benzo[a]pyrene (B[a]P), arsenic (As), cadmium (Cd), and lead (Pb) is a major environmental and human health concern. The mixture toxicity data on these co-contaminants are important for their risk assessment. In this study, we have determined the mixture toxicity of As, Cd and Pb, and B[a]P with As, Cd or Pb in HepG2 cells. The binary mixtures of Cd + As, Cd + Pb and As + Pb and B[a]P + metals (B[a]P + As, B[a]P + Cd and B[a]P + Pb) were evaluated for their interaction on the cytotoxicity using the MTS assay. A full factorial design (4 × 5) was used to determine the interaction toxicity and all the six mixtures showed significant interaction on the cytotoxicity. We further investigated the role of oxidative stress (reactive oxygen species (ROS) generation) and antioxidant defense mechanism (total glutathione (GSH) level) with the observed cytotoxicity. The mixtures of metals reduced the total GSH level and increased the ROS generation, respectively. In the case of mixtures of B[a]P and metals, both total GSH level and ROS generation were increased. Overall, the binary mixtures of metals and B[a]P with metals caused a dose dependent toxicity to HepG2 cells. The results also showed a significant contribution of oxidative stress to the observed toxicity and the potential protective role of the total GSH level against this mixture toxicity. The findings of interaction between B[a]P and metals might have an impact on the potential human health risk of this mixtures at contaminated sites.

  15. Technetium dichloride : a new binary halide containing metal-metal multiple bonds.

    SciTech Connect

    Poineau, F.; Malliakas, C. D.; Weck, P. F.; Scott, B. L.; Johnstone, E. V.; Forster, P. M.; Kim, E.; Kanatzidis, M. G.; Czerwinski, K. R.; Sattelberger, A. P.

    2011-06-15

    Technetium dichloride has been discovered. It was synthesized from the elements and characterized by several physical techniques, including single crystal X-ray diffraction. In the solid state, technetium dichloride exhibits a new structure type consisting of infinite chains of face sharing [Tc{sub 2}Cl{sub 8}] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) {angstrom}, a distance consistent with the presence of a Tc {triple_bond} Tc triple bond that is also supported by electronic structure calculations.

  16. Technetium Dichloride: A New Binary Halide Containing Metal-Metal Multiple Bonds

    SciTech Connect

    Poineau, Frederic; Malliakas, Christos D.; Weck, Philippe F.; Scott, Brian L.; Johnstone, Erik V.; Forster, Paul M.; Kim, Eunja; Kanatzidis, Mercouri G.; Czerwinski, Kenneth R.; Sattelberge, Alfred P.

    2011-10-19

    Technetium dichloride has been discovered. It was synthesized from the elements and characterized by several physical techniques, including single crystal X-ray diffraction. In the solid state, technetium dichloride exhibits a new structure type consisting of infinite chains of face sharing [Tc{sub 2}Cl{sub 8}] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) {angstrom}, a distance consistent with the presence of a Tc {triple_bond} Tc triple bond that is also supported by electronic structure calculations.

  17. Technetium dichloride: a new binary halide containing metal-metal multiple bonds.

    PubMed

    Poineau, Frederic; Malliakas, Christos D; Weck, Philippe F; Scott, Brian L; Johnstone, Erik V; Forster, Paul M; Kim, Eunja; Kanatzidis, Mercouri G; Czerwinski, Kenneth R; Sattelberger, Alfred P

    2011-06-15

    Technetium dichloride has been discovered. It was synthesized from the elements and characterized by several physical techniques, including single crystal X-ray diffraction. In the solid state, technetium dichloride exhibits a new structure type consisting of infinite chains of face sharing [Tc(2)Cl(8)] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) Å, a distance consistent with the presence of a Tc≡Tc triple bond that is also supported by electronic structure calculations.

  18. Micro- and Nanostructured Metal Oxide Chemical Sensors for Volatile Organic Compounds

    NASA Technical Reports Server (NTRS)

    Alim, M. A.; Penn, B. G.; Currie, J. R., Jr.; Batra, A. K.; Aggarwal, M. D.

    2008-01-01

    Aeronautic and space applications warrant the development of chemical sensors which operate in a variety of environments. This technical memorandum incorporates various kinds of chemical sensors and ways to improve their performance. The results of exploratory investigation of the binary composite polycrystalline thick-films such as SnO2-WO3, SnO2-In2O3, SnO2-ZnO for the detection of volatile organic compound (isopropanol) are reported. A short review of the present status of the new types of nanostructured sensors such as nanobelts, nanorods, nanotube, etc. based on metal oxides is presented.

  19. High Temperature Strength of YSZ Joints Brazed with Palladium Silver Copper Oxide Filler Metals

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2010-06-09

    The Ag-CuOx system is being investigated as potential filler metals for use in air brazing high-temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high temperature joint strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag-CuOx, and 15Pd-Ag-CuO. It was found that while the binary Ag-CuOx system exhibits stronger room temperature strength than the 15Pd system the strength is reduced to values equivalent of the 15Pd system at 800°C. The 15Pd system exhibits a lower ambient temperature strength that is retained at 800°C. In both systems the failure mechanism at high temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower temperatures to cause fracture of the YSZ substrate.

  20. Oxidized film structure and method of making epitaxial metal oxide structure

    DOEpatents

    Gan, Shupan [Richland, WA; Liang, Yong [Richland, WA

    2003-02-25

    A stable oxidized structure and an improved method of making such a structure, including an improved method of making an interfacial template for growing a crystalline metal oxide structure, are disclosed. The improved method comprises the steps of providing a substrate with a clean surface and depositing a metal on the surface at a high temperature under a vacuum to form a metal-substrate compound layer on the surface with a thickness of less than one monolayer. The compound layer is then oxidized by exposing the compound layer to essentially oxygen at a low partial pressure and low temperature. The method may further comprise the step of annealing the surface while under a vacuum to further stabilize the oxidized film structure. A crystalline metal oxide structure may be subsequently epitaxially grown by using the oxidized film structure as an interfacial template and depositing on the interfacial template at least one layer of a crystalline metal oxide.

  1. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  2. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  3. Recent applications of liquid metals featuring nanoscale surface oxides

    NASA Astrophysics Data System (ADS)

    Neumann, Taylor V.; Dickey, Michael D.

    2016-05-01

    This proceeding describes recent efforts from our group to control the shape and actuation of liquid metal. The liquid metal is an alloy of gallium and indium which is non-toxic, has negligible vapor pressure, and develops a thin, passivating surface oxide layer. The surface oxide allows the liquid metal to be patterned and shaped into structures that do not minimize interfacial energy. The surface oxide can be selectively removed by changes in pH or by applying a voltage. The surface oxide allows the liquid metal to be 3D printed to form free-standing structures. It also allows for the liquid metal to be injected into microfluidic channels and to maintain its shape within the channels. The selective removal of the oxide results in drastic changes in surface tension that can be used to control the flow behavior of the liquid metal. The metal can also wet thin, solid films of metal that accelerates droplets of the liquid along the metal traces .Here we discuss the properties and applications of liquid metal to make soft, reconfigurable electronics.

  4. Reduction of spalling in mixed metal oxide desulfurization sorbents by addition of a large promoter metal oxide

    DOEpatents

    Poston, James A.

    1997-01-01

    Mixed metal oxide pellets for removing hydrogen sulfide from fuel gas mixes derived from coal are stabilized for operation over repeated cycles of desulfurization and regeneration reactions by addition of a large promoter metal oxide such as lanthanum trioxide. The pellets, which may be principally made up of a mixed metal oxide such as zinc titanate, exhibit physical stability and lack of spalling or decrepitation over repeated cycles without loss of reactivity. The lanthanum oxide is mixed with pellet-forming components in an amount of 1 to 10 weight percent.

  5. Pulsations and metallicity of the pre-main sequence eclipsing spectroscopic binary RS Cha

    NASA Astrophysics Data System (ADS)

    Alecian, E.; Catala, C.; van't Veer-Menneret, C.; Goupil, M.-J.; Balona, L.

    2005-11-01

    We present new spectroscopic observations of the pre-main sequence eclipsing spectroscopic binary RS Cha. A sample of 174 spectra were obtained with the GIRAFFE spectrograph at the SAAO at 32 000 resolution. The radial velocity curves derived from these spectra were combined with previous observations spanning a period of about 30 years to correct the ephemeris of the system, and the result indicates that the orbital period is not constant. Residuals of the binary radial velocity curve for both components with amplitudes up to a few km s-1 and periods on the order of 1 h are clearly seen in our data, which we interpret as the signatures of delta-Scuti type pulsations. We revisited the masses of both components and determined the surface metallicity Z of both components of the RS Cha system by fitting synthetic spectra to observed spectra in a set of selected spectral regions. The synthetic spectra are calculated with the SYNTH code using stellar atmosphere models computed with the Kurucz ATLAS 9 code, along with a list of lines obtained from the VALD database. A selection of the best spectra and the most relevant spectral regions allowed us to determine Z = 0.028 ± 0.005. We also derived new values of v sin i: 64 ± 6 km s-1 and 70 ± 6 km s-1 for the primary and the secondary star, respectively. Finally, we observationally confirm that the RS Cha system is a synchronized and circularized system.

  6. Redox chemistry of a binary transition metal oxide (AB 2 O 4 ): a study of the Cu 2+ /Cu 0 and Fe 3+ /Fe 0 interconversions observed upon lithiation in a CuFe 2 O 4 battery using X-ray absorption spectroscopy

    DOE PAGES

    Cama, Christina A.; Pelliccione, Christopher J.; Brady, Alexander B.; ...

    2016-06-06

    Copper ferrite, CuFe2 O 4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe2 O 4. A phase pure tetragonal CuFe2 O 4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. We used ex situ X-ray absorption spectroscopy (XAS) measurements to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-raymore » absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(II) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(III) cations to octahedral positions previously occupied by copper(II). Then, upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(III) was achieved. Our results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.« less

  7. Redox chemistry of a binary transition metal oxide (AB 2 O 4 ): a study of the Cu 2+ /Cu 0 and Fe 3+ /Fe 0 interconversions observed upon lithiation in a CuFe 2 O 4 battery using X-ray absorption spectroscopy

    SciTech Connect

    Cama, Christina A.; Pelliccione, Christopher J.; Brady, Alexander B.; Li, Jing; Stach, Eric A.; Wang, Jiajun; Wang, Jun; Takeuchi, Esther S.; Takeuchi, Kenneth J.; Marschilok, Amy C.

    2016-06-06

    Copper ferrite, CuFe2 O 4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe2 O 4. A phase pure tetragonal CuFe2 O 4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. We used ex situ X-ray absorption spectroscopy (XAS) measurements to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(II) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(III) cations to octahedral positions previously occupied by copper(II). Then, upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(III) was achieved. Our results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.

  8. Cluster synthesis via ligand-arrested solid growth: triethylphosphine-capped fragments of binary metal chalcogenides.

    PubMed

    Crawford, Nathan R M; Hee, Allan G; Long, Jeffrey R

    2002-12-18

    A new and potentially highly generalizable technique for synthesizing molecular fragments of binary solids is demonstrated through application to selected transition metal chalcogenides. Employing a metal atom reactor, the solids are evaporated with a tungsten heating boat, and the resulting vapor is co-condensed with triethylphosphine. Major cluster products identified from a survey of first-row transition metal sulfides include the known species Cr6S8(PEt3)6, Co6S8(PEt3)6, and Cu12S6(PEt3)8, as well as the unprecedented species Fe4S4(PBun3)4, Ni4S4(PEt3)8, and Cu6S4(PEt3)4. Reactions utilizing Cu2Se resulted in the much larger clusters Cu26Se13(PEt3)14 and Cu70Se35(PEt3)21. The core of the former has a Th-symmetry structure featuring a body-centered icosahedron of Se2- anions, while the latter adopts a triangular structure based on three hexagonal closest packed layers of Se2- anions. In both cases, the Cu+ cations occupy distorted tetrahedral or trigonal planar sites similar to those encountered in Cu2Se; however, emergence of the face-centered cubic anion lattice of the bulk solid is not yet apparent at these cluster sizes.

  9. Nanoscale Metal Oxide Semiconductors for Gas Sensing

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

    2011-01-01

    A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical

  10. Binary rare earth element-Ni/Co metallic glasses with distinct β-relaxation behaviors

    SciTech Connect

    Zhu, Z. G.; Wang, Z.; Wang, W. H.

    2015-10-21

    We report the formation of a series of rare earth element (RE)-Ni/Co binary metallic glasses (MGs) with unusual distinct β-relaxation peak compared with that of most of the reported MGs which usually exhibit as an excess wing or a shoulder. The β-relaxation behavior of RE-Ni/Co MGs is sensitive to the composition and the atomic radii of the RE and can be tuned through changing the fraction of RE-Ni (or Co) atomic pairs. The novel RE-Ni/Co MGs with distinct β-relaxation can serve as model system to investigate the nature of the β-relaxation as well as its relations with other physical and mechanical properties of MGs.

  11. Redox mechanism in the binary transition metal phosphide Cu3P

    NASA Astrophysics Data System (ADS)

    Mauvernay, B.; Doublet, M.-L.; Monconduit, L.

    2006-05-01

    The electrochemical behaviour of the binary transition metal phosphide Cu3P towards lithium is investigated through galvano- and potentiostatic measurements. Obtained through high-temperature synthesis, this system shows a better volumetric capacity than graphite and a good capacity retention. In situ X-ray diffraction and first-principles electronic structure calculations are combined with the electrochemical results to show that the complete insertion of 3Li+ in the Cu3P electrode proceeds with the formation of three intermediate phases of lithium composition LixCu(3-x)P (x=1,2,3). The extra capacity previously observed in discharge is now clearly assigned to lithium insertion into the CuP2 impurity and to SEI reactions.

  12. Process for making a noble metal on tin oxide catalyst

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T. (Inventor); Davis, Patricia (Inventor); Miller, Irvin M. (Inventor)

    1989-01-01

    A quantity of reagent grade tin metal or compound, chloride-free, and high-surface-area silica spheres are placed in deionized water, followed by deaerating the mixture by boiling and adding an oxidizing agent, such as nitric acid. The nitric acid oxidizes the tin to metastannic acid which coats the spheres because the acid is absorbed on the substrate. The metastannic acid becomes tin oxide upon drying and calcining. The tin-oxide coated silica spheres are then placed in water and boiled. A chloride-free precious metal compound in aqueous solution is then added to the mixture containing the spheres, and the precious metal compound is reduced to a precious metal by use of a suitable reducing agent such as formic acid. Very beneficial results were obtained using the precious metal compound tetraammine platinum(II) hydroxide.

  13. Method for converting uranium oxides to uranium metal

    DOEpatents

    Duerksen, Walter K.

    1988-01-01

    A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

  14. Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries.

    PubMed

    Liu, Xue; Huang, Jia-Qi; Zhang, Qiang; Mai, Liqiang

    2017-02-03

    Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed.

  15. Binary Phase Diagram of the Manganese Oxide-Iron Oxide System

    SciTech Connect

    Crum, Jarrod V.; Riley, Brian J.; Vienna, John D.

    2009-10-01

    In this study, the MnOx-FeOx binary system was measured within a temperature range of 750 to 1590°C in an atmosphere of air. Multiple measurement methods were employed to accurately measure the phase boundaries, including isothermal heat-treatments followed by rapid quenching, dilatometery, differential thermal analyses with thermogravimetric analyses, and hot-stage X-ray diffraction (XRD). Phase assemblage in each sample was determined by XRD. Data were compared with literature, and a new, self consistent phase diagram was developed. The results are reported along with background information and a comparison with previously reported data.

  16. Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

    PubMed

    Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

    2013-12-01

    The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility.

  17. Polymer-assisted deposition of metal-oxide films.

    PubMed

    Jia, Q X; McCleskey, T M; Burrell, A K; Lin, Y; Collis, G E; Wang, H; Li, A D Q; Foltyn, S R

    2004-08-01

    Metal oxides are emerging as important materials for their versatile properties such as high-temperature superconductivity, ferroelectricity, ferromagnetism, piezoelectricity and semiconductivity. Metal-oxide films are conventionally grown by physical and chemical vapour deposition. However, the high cost of necessary equipment and restriction of coatings on a relatively small area have limited their potential applications. Chemical-solution depositions such as sol-gel are more cost-effective, but many metal oxides cannot be deposited and the control of stoichiometry is not always possible owing to differences in chemical reactivity among the metals. Here we report a novel process to grow metal-oxide films in large areas at low cost using polymer-assisted deposition (PAD), where the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of uniform metal-organic films. The latter feature makes it possible to grow simple and complex crack-free epitaxial metal-oxides.

  18. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  19. Anisotropy in binary metallic spin-glass alloys. I. Transition metals

    NASA Astrophysics Data System (ADS)

    Goldberg, Stephen M.; Levy, Peter M.; Fert, A.

    1986-01-01

    We derive the anisotropic pair interaction for binary spin-glass systems for the case where the ternary site which scatters electrons by means of the spin-orbit interaction is a magnetic site characterized by spin-split virtual bound states. We find that there are two distinctly different types of anisotropic Dzyaloshinsky-Moriya couplings. One depends only upon the magnitude of the third magnetic moment and has the vector coupling form familiar from ternary spin glasses: (R^i×R^j).(Si×Sj). The second type depends upon both the magnitude and direction of the third moment and has the coupling structure (R^i×R^j).S^k (Si×Sj).S^k. We define spin-dependent critical distances R+/-c in terms of which the coefficients of the two anisotropic interactions, acting relatively independently, take on preasymptotic or asymptotic forms according to whether the average interparticle spacings are less than or greater than the R+/-c. These critical distances are themselves variable, depending upon the separation of the virtual bound-state resonances from the Fermi surface. When the resonances are sufficiently close to EF, there will be large regions where the interactions exhibit preasymptotic behavior (1/R3). If the resonances are sufficiently far from EF, the interactions quickly reach their asymptotic forms. In the practical cases of CuMn and AuFe, we find that the critical distances are of the order of a nearest-neighbor distance so that the interactions fall off as 1/R4. This feature has great consequence in calculations of the macroscopic anisotropy energy.

  20. Improving Metal-Oxide-Metal (MOM) Diode Performance Via the Optimization of the Oxide Layer

    NASA Astrophysics Data System (ADS)

    Dodd, Linzi E.; Shenton, Samantha A.; Gallant, Andrew J.; Wood, David

    2015-05-01

    Small area metal-oxide-metal (MOM) diodes are being investigated in many research groups for the detection of THz frequency radiation. In order to create a high-speed rectifying device, the central oxide layer of the MOM structure must be thin and have known physical characteristics. The thickness, structure and uniformity of the oxide can be controlled during the fabrication process. In the work presented here, the effects of both oxygen plasma concentration and annealing temperature during fabrication of MOM diodes have been explored. It has been found that, by reducing the oxygen gas concentration from previous work, the layer can be more repeatable and uniform. Furthermore, for an anneal temperature up to a threshold temperature in the to range, the performance of the diodes is excellent, with a value of zero-bias curvature coefficient (CCZB) that can be up to . For higher temperature treatments, the value of CCZB decreases to a maximum of . Similar trends in AC tests can be seen for voltage and current responsivity values.

  1. Method and apparatus for the production of metal oxide powder

    DOEpatents

    Harris, M.T.; Scott, T.C.; Byers, C.H.

    1992-06-16

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed. 2 figs.

  2. Method and apparatus for the production of metal oxide powder

    DOEpatents

    Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

    1993-01-01

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

  3. Method and apparatus for the production of metal oxide powder

    DOEpatents

    Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

    1992-01-01

    The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

  4. Engineering Polarons at a Metal Oxide Surface

    NASA Astrophysics Data System (ADS)

    Yim, C. M.; Watkins, M. B.; Wolf, M. J.; Pang, C. L.; Hermansson, K.; Thornton, G.

    2016-09-01

    Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO2(110 ) , using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.

  5. Epitaxial Electrodeposition of Chiral Metal Oxide Films

    NASA Astrophysics Data System (ADS)

    Switzer, Jay

    2006-03-01

    Chirality is ubiquitous in Nature. One enantiomer of a molecule is often physiologically active, while the other enantiomer may be either inactive or toxic. Chiral surfaces offer the possibility of developing heterogeneous enantiospecific catalysts that can more readily be separated from the products and reused. Chiral surfaces might also serve as electrochemical sensors for chiral molecules- perhaps even implantable chiral sensors that could be used to monitor drug levels in the body. Our trick to produce chiral surfaces is to electrodeposit low symmetry metal oxide films with chiral orientations on achiral substrates (see, Nature 425, 490, 2003). The relationship between three-dimensional and two-dimensional chirality will be discussed. Chiral surfaces lack mirror or glide plane symmetry. It is possible to produce chiral surfaces of materials which do not crystallize in chiral space groups. We have deposited chiral orientations of achiral CuO onto single-crystal Au and Cu using both tartaric acid and the amino acids alanine and valine to control the handedness of the electrodeposited films. We will present results on the chiral recognition of molecules such as tartaric or malic acid and L-dopa on the chiral electrodeposited CuO. Initial work on the electrochemical biomineralization of chiral nanostructures of calcite will also be discussed.

  6. Computer modelling of metal - oxide interfaces

    NASA Astrophysics Data System (ADS)

    Purton, J.; Parker, S. C.; Bullett, D. W.

    1997-07-01

    We have used atomistic simulations to model oxide - metal interfaces. We have, for the first time, allowed the atoms on both sides of the interface to relax. The efficiency of the computational method means that calculations can be performed on complex interfaces containing several thousand atoms and do not require an arbitrary definition of the image plane to model the electrostatics across the dielectric discontinuity. We demonstrate the viability of the approach and the effect of relaxation on a range of MgO - Ag interfaces. Defective and faceted interfaces, as well as the ideal case, have been studied. The latter was chosen for comparison with previous theoretical calculations and experimental results. The wetting angle 0953-8984/9/27/004/img7 and work of adhesion 0953-8984/9/27/004/img8 for MgO{100} - Ag{100} are in reasonable agreement with experiment. As with ab initio electronic structure calculations the silver atoms have been shown to favour the position above the oxygen site.

  7. Stimulated oxidation of metals (laser, electric field, etc.): Comparative studies

    NASA Astrophysics Data System (ADS)

    Nánai, László; Füle, Miklós

    2014-11-01

    In this report we demonstrate the importance of metal oxides, e.g. thin films and nanostructures, in modern science and technology. The basic laws of oxide thickness on base of diffusion of specimens versus time in different circumstances (Cabrera-Mott and Wagner laws) under the influence of external fields, e.g. electromagnetic field, static electric and magnetic field, are demonstrated. We give experimental results for various metal oxide layers over a wide range of different metals. Theoretical explanations are provided as well for the most reliable circumstances.

  8. Metal Oxide Gas Sensors: Sensitivity and Influencing Factors

    PubMed Central

    Wang, Chengxiang; Yin, Longwei; Zhang, Luyuan; Xiang, Dong; Gao, Rui

    2010-01-01

    Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above. PMID:22294916

  9. CuO-CeO{sub 2} binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation

    SciTech Connect

    Hu, Chaoquan; Zhu, Qingshan; Chen, Lin; Wu, Rongfang

    2009-12-15

    This work reports the first synthesis of CuO-CeO{sub 2} binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO-CeO{sub 2} nanoplates calcined at 400 {sup o}C were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were exposed on the CuO-CeO{sub 2} nanoplate surface. The effect of the synthesis conditions on the structure of the product, as well as the growth process of the nanoplates, has been studied and discussed. The CuO-CeO{sub 2} nanoplates exhibited an excellent catalytic activity for benzene oxidation despite its relatively low surface area and could catalyze the complete oxidation of benzene at a temperature as low as 240 {sup o}C.

  10. Electromagnetic modes of the asymmetric metal-oxide-metal tunnel junction

    NASA Technical Reports Server (NTRS)

    Kurdi, B. N.; Hall, D. G.

    1984-01-01

    The characteristics of the modes of an Al-Al2O3-Ag tunnel junction are analyzed, and the way in which the field profiles, the propagation constant, and the attenuation depend on the thickness of the oxide layer is described. The significance of these results for investigations of light emission from metal-oxide-metal tunnel junctions is discussed.

  11. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    2000-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  12. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    2001-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  13. Metal thin film growth on multimetallic surfaces: From quaternary metallic glass to binary crystal

    SciTech Connect

    Jing, Dapeng

    2010-01-01

    The work presented in this thesis mainly focuses on the nucleation and growth of metal thin films on multimetallic surfaces. First, we have investigated the Ag film growth on a bulk metallic glass surface. Next, we have examined the coarsening and decay of bilayer Ag islands on NiAl(110) surface. Third, we have investigated the Ag film growth on NiAl(110) surface using low-energy electron diffraction (LEED). At last, we have reported our investigation on the epitaxial growth of Ni on NiAl(110) surface. Some general conclusions can be drawn as follows. First, Ag, a bulk-crystalline material, initially forms a disordered wetting layer up to 4-5 monolayers on Zr-Ni-Cu-Al metallic glass. Above this coverage, crystalline 3D clusters grow, in parallel with the flatter regions. The cluster density increases with decreasing temperature, indicating that the conditions of island nucleation are far-from-equilibrium. Within a simple model where clusters nucleate whenever two mobile Ag adatoms meet, the temperature-dependence of cluster density yields a (reasonable) upper limit for the value of the Ag diffusion barrier on top of the Ag wetting layer of 0.32 eV. Overall, this prototypical study suggests that it is possible to grow films of a bulk-crystalline metal that adopt the amorphous character of a glassy metal substrate, if film thickness is sufficiently low. Next, the first study of coarsening and decay of bilayer islands has been presented. The system was Ag on NiAl(110) in the temperature range from 185 K to 250 K. The coarsening behavior, has some similarities to that seen in the Ag(110) homoepitaxial system studied by Morgenstern and co-workers. At 185 K and 205 K, coarsening of Ag islands follows a Smoluchowski ripening pathway. At 205 K and 250 K, the terrace diffusion limited Ostwald ripening dominants. The experimental observed temperature for the transition from SR to OR is 205 K. The SR exhibits anisotropic island diffusion and the OR exhibits 1D decay of island

  14. Custom-designed nanomaterial libraries for testing metal oxide toxicity.

    PubMed

    Pokhrel, Suman; Nel, André E; Mädler, Lutz

    2013-03-19

    Advances in aerosol technology over the past 10 years have enabled the generation and design of ultrafine nanoscale materials for many applications. A key new method is flame spray pyrolysis (FSP), which produces particles by pyrolyzing a precursor solution in the gas phase. FSP is a highly versatile technique for fast, single-step, scalable synthesis of nanoscale materials. New innovations in particle synthesis using FSP technology, including variations in precursor chemistry, have enabled flexible, dry synthesis of loosely agglomerated, highly crystalline ultrafine powders (porosity ≥ 90%) of binary, ternary, and mixed-binary-and-ternary oxides. FSP can fulfill much of the increasing demand, especially in biological applications, for particles with specific material composition, high purity, and high crystallinity. In this Account, we describe a strategy for creating nanoparticle libraries (pure or Fedoped ZnO or TiO₂) utilizing FSP and using these libraries to test hypotheses related to the particles' toxicity. Our innovation lies in the overall integration of the knowledge we have developed in the last 5 years in (1) synthesizing nanomaterials to address specific hypotheses, (2) demonstrating the electronic properties that cause the material toxicity, (3) understanding the reaction mechanisms causing the toxicity, and (4) extracting from in vitro testing and in vivo testing in terrestrial and marine organisms the essential properties of safe nanomaterials. On the basis of this acquired knowledge, we further describe how the dissolved metal ion from these materials (Zn²⁺ in this Account) can effectively bind with different cell constituents, causing toxicity. We use Fe-S protein clusters as an example of the complex chemical reactions taking place after free metal ions migrate into the cells. As a second example, TiO₂ is an active material in the UV range that exhibits photocatalytic behavior. The induction of electron-hole (e⁻/h⁺) pairs followed by

  15. Multiscale model of metal alloy oxidation at grain boundaries

    SciTech Connect

    Sushko, Maria L. Alexandrov, Vitaly; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-06-07

    High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr{sub 2}O{sub 3}. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl{sub 2}O{sub 4}. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3–10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr{sub 2}O{sub 3} has a plate-like structure with 1.2–1.7 nm wide pores running along the grain boundary, while NiAl{sub 2}O{sub 4} has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular

  16. Toxicity of platinum, palladium and rhodium to Daphnia magna in single and binary metal exposure experiments.

    PubMed

    Zimmermann, Sonja; Wolff, Carolina; Sures, Bernd

    2017-02-17

    Mainly due to automobile traffic, but also due to other sources, the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) are introduced into aquatic biotopes where they accumulate in sediments of lakes and rivers. However, the toxicity of these noble metals to aquatic organisms is not well understood and especially toxicity studies under standardized condition are lacking. Thus, the toxicity of Pt, Pd and Rh to Daphnia magna was tested in single metal exposure experiments according to OECD guideline 202. Immobility and lethality was recorded after 24 h and 48 h of exposure and EC50 and LC50, respectively, were determined. As the nominal exposure concentration of Pd differed significantly from the quantified concentration, the control of the real exposure concentration by chemical analysis is mandatory, especially for Pd. The toxicity decreased in the order Pd > Pt ≫ Rh with e.g. LC50(48 h) values of 14 μg/L for Pd, 157 μg/L for Pt and 56,800 μg/L for Rh. The exposure period had a clear effect on the toxicity of Pt, Pd and Rh. For Pt and Rh the endpoint immobility was more sensitive than the endpoint lethality whereas Pd toxicity was similar for both endpoints. The Hill slopes, which are a measure for the steepness of the concentration-response curves, showed no significant discrepancies between the different metals. The binary metal exposure to Pt and Pd revealed a more-than-additive, i.e. a synergistic toxicity using the toxic unit approach. The present study is a start to understand the toxicity of interacting PGE. The modes of action behind the synergistic effect are unclear.

  17. Oxidation of tunnel barrier metals in magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Yang, J. Joshua; Ladwig, Peter F.; Yang, Ying; Ji, Chengxiang; Chang, Y. Austin; Liu, Feng X.; Pant, Bharat B.; Schultz, Allan E.

    2005-05-01

    The oxidation of an ultrathin metal layer (<1nm) to form an oxide tunnel barrier is of critical importance for the fabrication of magnetic tunnel junctions (MTJs) with low product of resistance and area (R×A). Nonuniform and excessive or insufficient oxidation will occur by using conventional plasma, air, or O2 and noble gas mixtures as oxidation methods. An oxidation method was investigated to oxidize only an ultrathin layer of metal (such as Y) without oxidizing adjacent ferromagnetic thin film layers. We have now demonstrated that a gas mixture of H2O/H2 with a fixed chemical potential of oxygen determined by the relative amounts of the two gases can oxidize Y and Ta thin layers while simultaneously keeping a Co ferromagnetic layer completely unoxidized. This universal method can be used to preferentially oxidize a host of other metals with high tendency to form oxides, such as Zr, Hf, Nb, rare earth metals, etc. and may allow us to access the feasible lower limit of barrier thickness in MTJs.

  18. An in situ oxidation route to fabricate graphene nanoplate-metal oxide composites

    SciTech Connect

    Chen Sheng; Zhu Junwu; Wang Xin

    2011-06-15

    We report our studies on an improved soft chemical route to directly fabricate graphene nanoplate-metal oxide (Ag{sub 2}O, Co{sub 3}O{sub 4}, Cu{sub 2}O and ZnO) composites from the in situ oxidation of graphene nanoplates. By virtue of H{sup +} from hydrolysis of the metal nitrate aqueous solution and NO{sub 3}{sup -}, only a small amount of functional groups were introduced, acting as anchor sites and consequently forming the graphene nanoplate-metal oxide composites. The main advantages of this approach are that it does not require cumbersome oxidation of graphite in advance and no need to reduce the composites due to the lower oxidation degree. The microstructures of as-obtained metal oxides on graphene nanoplates can be dramatically controlled by changing the reaction parameters, opening up the possibility for processing the optical and electrochemical properties of the graphene-based nanocomposites. - graphical abstract: An improved soft chemical route to directly fabricate graphene nanoplate-metal oxide composites is reported from the in situ oxidation of graphene nanoplates. Highlights: > An improved soft chemical route to directly fabricate graphene nanoplate-metal oxide composites. > The microstructures can be controlled by changing the reaction parameters. > It does not require oxidation of graphite in advance and no need to reduce the composites due to the lower oxidation degree.

  19. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  20. Method of physical vapor deposition of metal oxides on semiconductors

    DOEpatents

    Norton, David P.

    2001-01-01

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  1. Displacement method and apparatus for reducing passivated metal powders and metal oxides

    DOEpatents

    Morrell; Jonathan S. , Ripley; Edward B.

    2009-05-05

    A method of reducing target metal oxides and passivated metals to their metallic state. A reduction reaction is used, often combined with a flux agent to enhance separation of the reaction products. Thermal energy in the form of conventional furnace, infrared, or microwave heating may be applied in combination with the reduction reaction.

  2. Cryochemical method for forming spherical metal oxide particles from metal salt solutions

    DOEpatents

    Tinkle, M.C.

    1973-12-01

    A method is described of preparing small metal oxide spheres cryochemically utilizing metal salts (e.g., nitrates) that cannot readily be dried and calcined without loss of sphericity of the particles. Such metal salts are cryochemically formed into small spheres, partially or completely converted to an insoluble salt, and dried and calcined. (Official Gazette)

  3. Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials

    SciTech Connect

    Clapsaddle, B; Gash, A; Plantier, K; Pantoya, M; Jr., J S; Simpson, R

    2004-04-27

    In the field of composite energetic materials, properties such as ingredient distribution, particle size, and morphology affect both sensitivity and performance. Since the reaction kinetics of composite energetic materials are typically controlled by the mass transport rates between reactants, one would anticipate new and potentially exceptional performance from energetic nanocomposites. We have developed a new method of making nanostructured energetic materials, specifically explosives, propellants, and pyrotechnics, using sol-gel chemistry. A novel sol-gel approach has proven successful in preparing metal oxide/silicon oxide nanocomposites in which the metal oxide is the major component. By introducing a fuel metal, such as aluminum, into the metal oxide/silicon oxide matrix, energetic materials based on thermite reactions can be fabricated. Two of the metal oxides are tungsten trioxide and iron(III) oxide, both of which are of interest in the field of energetic materials. In addition, due to the large availability of organically functionalized silanes, the silicon oxide phase can be used as a unique way of introducing organic additives into the bulk metal oxide materials. These organic additives can cause the generation of gas upon ignition of the materials, therefore resulting in a composite material that can perform pressure/volume work. Furthermore, the desired organic functionality is well dispersed throughout the composite material on the nanoscale with the other components, and is therefore subject to the same increased reaction kinetics. The resulting nanoscale distribution of all the ingredients displays energetic properties not seen in its microscale counterparts due to the expected increase of mass transport rates between the reactants. The synthesis and characterization of iron(III) oxide/organosilicon oxide nanocomposites and their performance as energetic materials will be discussed.

  4. Precise atmospheric parameters for the shortest-period binary white dwarfs: gravitational waves, metals, and pulsations

    SciTech Connect

    Gianninas, A.; Kilic, Mukremin; Dufour, P.; Bergeron, P.; Brown, Warren R.; Hermes, J. J.

    2014-10-10

    We present a detailed spectroscopic analysis of 61 low-mass white dwarfs and provide precise atmospheric parameters, masses, and updated binary system parameters based on our new model atmosphere grids and the most recent evolutionary model calculations. For the first time, we measure systematic abundances of He, Ca, and Mg for metal-rich, extremely low mass white dwarfs and examine the distribution of these abundances as a function of effective temperature and mass. Based on our preliminary results, we discuss the possibility that shell flashes may be responsible for the presence of the observed He and metals. We compare stellar radii derived from our spectroscopic analysis to model-independent measurements and find good agreement except for white dwarfs with T {sub eff} ≲ 10,000 K. We also calculate the expected gravitational wave strain for each system and discuss their significance to the eLISA space-borne gravitational wave observatory. Finally, we provide an update on the instability strip of extremely low mass white dwarf pulsators.

  5. Electrolytic separation of crystals of transition-metal oxides

    NASA Technical Reports Server (NTRS)

    Arnott, R. J.; Feretti, A.; Kunnamann, W.

    1969-01-01

    Versatile flux system grows large, well-formed, stoichiometric single crystals of mixed oxides of the transition-metal elements. These crystals have important uses in the microwave field, and applications as lasers and masers in communications.

  6. Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

    PubMed Central

    Kanan, Sofian M.; El-Kadri, Oussama M.; Abu-Yousef, Imad A.; Kanan, Marsha C.

    2009-01-01

    A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented. PMID:22408500

  7. Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis

    NASA Astrophysics Data System (ADS)

    Jin, Zhao

    Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO2, ZrO2, Al 2O3) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular

  8. Silicon Metal-Oxide-Semiconductor Quantum Devices

    NASA Astrophysics Data System (ADS)

    Nordberg, Eric

    This thesis presents stable quantum dots in a double gated silicon metal-oxide-semiconductor (MOS) system with an open-lateral geometry. In recent years, semiconductor lateral quantum dots have emerged as an appealing approach to quantum computing. Silicon offers the potential for very long electron spin decoherence times in these dots. Several important steps toward a functioning silicon-based electron spin qubit are presented, including stable Coulomb blockade within a quantum dot, a tunable double quantum dot, and integrated charge sensing. A fabrication process has been created to make low-disorder constrictions on relatively high mobility Si-MOS material and to facilitate essentially arbitrary gate geometries. Within this process, changes in mobility and charge defect densities are measured for critical process steps. This data was used to guide the fabrication of devices culminating, in this work, with a clean, stable quantum dot in a double-gated MOS system. Stable Coulomb-blockade behavior showing single-period conductance oscillations was observed in MOS quantum dots. Measured capacitances within each device and capacitances calculated via modeling are compared, showing that the measured Coulomb-blockade is consistent with a lithographically defined quantum dot, as opposed to a disorder dot within a single constriction. A tunable double dot is also observed. Laterally coupled charge sensing of quantum dots is highly desirable because it enables measurement even when conduction through the quantum dot itself is suppressed. Such charge sensing is demonstrated in this system. The current through a point contact constriction located near a quantum dot shows sharp 2% changes corresponding to charge transitions between the dot and a nearby lead. The coupling capacitance between the charge sensor and the quantum dot is extracted and agrees well with a capacitance model of the integrated sensor and quantum dot system.

  9. Structure, Bonding and Surface Chemistry of Metal Oxide Nanoclusters

    DTIC Science & Technology

    2015-06-23

    AFRL-OSR-VA-TR-2015-0191 Structure , Bonding and Surface Chemistry of Metal Oxide Nanoclusters Michael Duncan UNIVERSITY OF GEORGIA RESEARCH...2015 4. TITLE AND SUBTITLE Structure , Bonding and Surface Chemistry of Metal Oxide Nanoclusters 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1...Back (Rev. 8/98) DISTRIBUTION A: Distribution approved for public release. Final Report Project title: Structure , Bonding and Surface Chemistry of

  10. Plutonium metal and oxide container weld development and qualification

    SciTech Connect

    Fernandez, R.; Horrell, D.R.; Hoth, C.W.; Pierce, S.W.; Rink, N.A.; Rivera, Y.M.; Sandoval, V.D.

    1996-01-01

    Welds were qualified for a container system to be used for long-term storage of plutonium metal and oxide. Inner and outer containers are formed of standard tubing with stamped end pieces gas-tungsten-arc (GTA) welded onto both ends. The weld qualification identified GTA parameters to produce a robust weld that meets the requirements of the Department of Energy standard DOE-STD-3013-94, ``Criteria for the Safe Storage of Plutonium Metals and Oxides.``

  11. Process for Making a Noble Metal on Tin Oxide Catalyst

    NASA Technical Reports Server (NTRS)

    Davis, Patricia; Miller, Irvin; Upchurch, Billy

    2010-01-01

    To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

  12. Oxygen-deficient metal oxide nanostructures for photoelectrochemical water oxidation and other applications.

    PubMed

    Wang, Gongming; Ling, Yichuan; Li, Yat

    2012-11-07

    This review presents highlights of the latest results of studies directed at developing oxygen-deficient metal oxides, including TiO(2), WO(3), and α-Fe(2)O(3), nanostructures as electrode materials, which show significantly enhanced performance in applications for photoelectrochemical water oxidation. The enhanced photoelectrochemical performance is attributed to improved electrical conductivities by controlled incorporation of oxygen vacancies as shallow donors for metal oxides. We also discuss the potential of these oxygen-deficient metal oxides for other energy conversion and storage applications, such as photocatalytic reactions and charge storage.

  13. Alkoxy-Siloxide Metal Complexes: Precursors to Metal Silica, Metal Oxide Silica, and Metal Silicate Materials.

    NASA Astrophysics Data System (ADS)

    Terry, Karl William

    The alkoxy-siloxide complexes M (OSi(O ^{rm t}Bu)_3 ]_4 (M = Ti(1), Zr(2), Hf(3)), were prepared by reaction with their respective metal diethylamides. These compounds readily undergo low-temperature decomposition to their respective metal oxide silica materials rm(MO_2{cdot}4SiO_2). The volatile products of the thermolysis of 2 (ca. 200 ^circC) were isobutylene (11.7 equiv) and water (5.4 equiv). The rm ZrO _2{cdot}4SiO_2 material from the decomposition of 2 at 400^circ C was amorphous until ca. 1100^ circC where crystallization of t-ZrO _2 occurred. After thermolysis to 1500 ^circC, t-ZrO_2 and cristobalite were the major products with minor amounts of m-ZrO_2. The rm HfO_2{cdot}4SiO_2 material from the decomposition of 3 at 400^ circC was amorphous until ca. 1000 ^circC where crystallization of c/t -HfO_2 was observed. Thermolysis to 1460^circC yielded c/t -HfO_2, m-HfO_2, and minor amounts of cristobalite. The crystallization of anatase in the rm TiO_2{cdot }4SiO_2 material from decomposed 1 at 400^circC was apparent after thermolysis to 1000^circC. Thermolysis to 1400^circC gave a mixture of anatase, rutile, and cristobalite. Compound 2 was decomposed in xylenes and yielded a transparent gel which was isolated as a white powder upon drying in vacuuo. The compounds [ Me _2AlOSi(O^{t}Bu)_3] _2 (4) and [( ^{t}BuO)MeAlOSi(O^{t}Bu) _3]_2 (5) were structurally characterized and contain bent and planar rm Al_2O_2 four membered rings, respectively. Both 4 and 5 yield isobutylene upon thermolysis (ca. 200 ^circC) and the crystallization of mullite occurs at 1034^circC and 1017^circC, respectively (by DTA). The solution thermolysis of 4 in refluxing toluene yields an opaque white gel. The crystallization of mullite occurs at 1029^circC (by DTA). The compounds [ CuOSi(O ^{t}Bu)_3]_{n } (6) and [ CuOSi(O ^{t}Bu)_2Ph]_4 (7) were prepared by reaction with [ CuO^{t}Bu]_4. The thermolysis of 6 at 1000^circ C under argon gave Cu^circ and amorphous silica and thermolysis under

  14. Photochemical route for accessing amorphous metal oxide materials for water oxidation catalysis.

    PubMed

    Smith, Rodney D L; Prévot, Mathieu S; Fagan, Randal D; Zhang, Zhipan; Sedach, Pavel A; Siu, Man Kit Jack; Trudel, Simon; Berlinguette, Curtis P

    2013-04-05

    Large-scale electrolysis of water for hydrogen generation requires better catalysts to lower the kinetic barriers associated with the oxygen evolution reaction (OER). Although most OER catalysts are based on crystalline mixed-metal oxides, high activities can also be achieved with amorphous phases. Methods for producing amorphous materials, however, are not typically amenable to mixed-metal compositions. We demonstrate that a low-temperature process, photochemical metal-organic deposition, can produce amorphous (mixed) metal oxide films for OER catalysis. The films contain a homogeneous distribution of metals with compositions that can be accurately controlled. The catalytic properties of amorphous iron oxide prepared with this technique are superior to those of hematite, whereas the catalytic properties of a-Fe(100-y-z)Co(y)Ni(z)O(x) are comparable to those of noble metal oxide catalysts currently used in commercial electrolyzers.

  15. Development of metal oxide impregnated stilbite thick film ethanol sensor

    NASA Astrophysics Data System (ADS)

    Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

    2016-05-01

    This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

  16. CS 22873-139: A very metal-poor main-sequence spectroscopic binary with colors indicative of intermediate age

    NASA Astrophysics Data System (ADS)

    Preston, George W.

    1994-12-01

    CS 22873-139, a metal-deficient ((Fe/H) = -3.1), high-velocity (Vrad = +243 km/s) star with observed UBV colors (B-V = 0.37, U-B = -0.22) that locate it near the main-sequence turnoff of an old metal-poor population (Preston et al. (1991); Beers et al. (1992)), is, in fact, a double-lined spectroscopic binary with a period of 19.16 days, eccentricity e = 0.26, and a mass ratio of approximately 0.88. The observed colors, corrected for reddening, can be matched by those for a family of artificial binaries constructed by use of colors and luminosities taken from isochrones for ages between 3 and 13 Gy, but the strengths of metal lines in the primary and secondary spectra require that the age of the system be less than approximately 8 Gy. The inferred unreddened colors of the primary, (B-V)0,p = 0.30, (U-B)0,p = -0.19, lie blueward of any globular cluster turnoff and near the low-abundance (upper) U-B boundary of BMP stars in the UBV two-color diagram, as discussed by Preston et al. (1994). Were the primary product of binary merger in an initial triple star system, Harrington's (1977) stability criterion requires for the initial close binary a1 less than 5.2 solar radii and P less than 1.5 days. According to Vilhu (1982) such a system will merge in about 109 years, a time much shorter than the main-sequence age deduced for this system, so even if binary merger had taken place the conclusion that CS 22873-139 must be a relatively young metal-poor star is preserved.

  17. Multiscale model of metal alloy oxidation at grain boundaries

    SciTech Connect

    Sushko, Maria L.; Alexandrov, Vitali Y.; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-06-07

    High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model at experimentally relevant length scales is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr2O3. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl2O4. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3–10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr2O3 has a plate-like structure with 1.2 - 1.7 nm wide pores running along the grain boundary, while NiAl2O4 has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular

  18. Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas

    PubMed Central

    Tanaka, Manabu; Kageyama, Takuya; Sone, Hirotaka; Yoshida, Shuhei; Okamoto, Daisuke; Watanabe, Takayuki

    2016-01-01

    Lithium metal oxide nanoparticles were synthesized by induction thermal plasma. Four different systems—Li–Mn, Li–Cr, Li–Co, and Li–Ni—were compared to understand formation mechanism of Li–Me oxide nanoparticles in thermal plasma process. Analyses of X-ray diffractometry and electron microscopy showed that Li–Me oxide nanoparticles were successfully synthesized in Li–Mn, Li–Cr, and Li–Co systems. Spinel structured LiMn2O4 with truncated octahedral shape was formed. Layer structured LiCrO2 or LiCoO2 nanoparticles with polyhedral shapes were also synthesized in Li–Cr or Li–Co systems. By contrast, Li–Ni oxide nanoparticles were not synthesized in the Li–Ni system. Nucleation temperatures of each metal in the considered system were evaluated. The relationship between the nucleation temperature and melting and boiling points suggests that the melting points of metal oxides have a strong influence on the formation of lithium metal oxide nanoparticles. A lower melting temperature leads to a longer reaction time, resulting in a higher fraction of the lithium metal oxide nanoparticles in the prepared nanoparticles.

  19. Complexed metals in hazardous waste: Limitations of conventional chemical oxidation

    SciTech Connect

    Diel, B.N.; Kuchynka, D.J.; Borchert, J.

    1994-12-31

    In the management of hazardous waste, more is known regarding the treatment of metals than about the fixation, destruction and/or immobilization of any other hazardous constituent group. Metals are the only hazardous constituents which cannot be destroyed, and so must be converted to their least soluble and/or reactive form to prevent reentry into the environment. The occurrence of complexed metals, e.g., metallocyanides, and/or chelated metals, e.g., M{center_dot}EDTA in hazardous waste streams presents formidable challenges to conventional waste treatment practices. This paper presents the results of extensive research into the destruction (chemical oxidation) of metallocyanides and metal-chelates, defines the utility and limitations of conventional chemical oxidation approaches, illustrates some of the waste management difficulties presented by such species, and presents preliminary data on the UV/H{sub 2}O{sub 2} photodecomposition of chelated metals.

  20. Nanostructured iron(III)-copper(II) binary oxide: a novel adsorbent for enhanced arsenic removal from aqueous solutions.

    PubMed

    Zhang, Gaosheng; Ren, Zongming; Zhang, Xiwang; Chen, Jing

    2013-08-01

    To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3 mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration.

  1. Integrated photo-responsive metal oxide semiconductor circuit

    NASA Technical Reports Server (NTRS)

    Jhabvala, Murzban D. (Inventor); Dargo, David R. (Inventor); Lyons, John C. (Inventor)

    1987-01-01

    An infrared photoresponsive element (RD) is monolithically integrated into a source follower circuit of a metal oxide semiconductor device by depositing a layer of a lead chalcogenide as a photoresistive element forming an ohmic bridge between two metallization strips serving as electrodes of the circuit. Voltage from the circuit varies in response to illumination of the layer by infrared radiation.

  2. Metal-oxide-based energetic materials and synthesis thereof

    DOEpatents

    Tillotson, Thomas M. , Simpson; Randall L.; Hrubesh, Lawrence W.

    2006-01-17

    A method of preparing energetic metal-oxide-based energetic materials using sol-gel chemistry has been invented. The wet chemical sol-gel processing provides an improvement in both safety and performance. Essentially, a metal-oxide oxidizer skeletal structure is prepared from hydrolyzable metals (metal salts or metal alkoxides) with fuel added to the sol prior to gelation or synthesized within the porosity metal-oxide gel matrix. With metal salt precursors a proton scavenger is used to destabilize the sol and induce gelation. With metal alkoxide precursors standard well-known sol-gel hydrolysis and condensation reactions are used. Drying is done by standard sol-gel practices, either by a slow evaporation of the liquid residing within the pores to produce a high density solid nanocomposite, or by supercritical extraction to produce a lower density, high porous nanocomposite. Other ingredients may be added to this basic nanostructure to change physical and chemical properties, which include organic constituents for binders or gas generators during reactions, burn rate modifiers, or spectral emitters.

  3. Thermochemical analyses of the oxidative vaporization of metals and oxides by oxygen molecules and atoms

    NASA Technical Reports Server (NTRS)

    Kohl, F. J.; Leisz, D. M.; Fryburg, G. C.; Stearns, C. A.

    1977-01-01

    Equilibrium thermochemical analyses are employed to describe the vaporization processes of metals and metal oxides upon exposure to molecular and atomic oxygen. Specific analytic results for the chromium-, platinum-, aluminum-, and silicon-oxygen systems are presented. Maximum rates of oxidative vaporization predicted from the thermochemical considerations are compared with experimental results for chromium and platinum. The oxidative vaporization rates of chromium and platinum are considerably enhanced by oxygen atoms.

  4. Selective Growth of Noble Gases at Metal/Oxide Interface.

    PubMed

    Takahashi, Keisuke; Oka, Hiroshi; Ohnuki, Somei

    2016-02-17

    The locations and roles of noble gases at an oxide/metal interface in oxide dispersed metal are theoretically and experimentally investigated. Oxide dispersed metal consisting of FCC Fe and Y2Hf2O7 (Y2Ti2O7) is synthesized by mechanical alloying under a saturated Ar gas environment. Transmission electron microscopy and density functional theory observes the strain field at the interface of FCC Fe {111} and Y2Hf2O7 {111} whose physical origin emerges from surface reconstruction due to charge transfer. Noble gases are experimentally observed at the oxide (Y2Ti2O7) site and calculations reveal that the noble gases segregate the interface and grow toward the oxide site. In general, the interface is defined as the trapping site for noble gases; however, transmission electron microscopy and density functional theory found evidence which shows that noble gases grow toward the oxide, contrary to the generally held idea that the interface is the final trapping site for noble gases. Furthermore, calculations show that the inclusion of He/Ar hardens the oxide, suggesting that material fractures could begin from the noble gas bubble within the oxides. Thus, experimental and theoretical results demonstrate that noble gases grow from the interface toward the oxide and that oxides behave as a trapping site for noble gases.

  5. Metal-oxide-metal point contact junction detectors. [detection mechanism and mechanical stability

    NASA Technical Reports Server (NTRS)

    Baird, J.; Havemann, R. H.; Fults, R. D.

    1973-01-01

    The detection mechanism(s) and design of a mechanically stable metal-oxide-metal point contact junction detector are considered. A prototype for a mechanically stable device has been constructed and tested. A technique has been developed which accurately predicts microwave video detector and heterodyne mixer SIM (semiconductor-insulator-metal) diode performance from low dc frequency volt-ampere curves. The difference in contact potential between the two metals and geometrically induced rectification constitute the detection mechanisms.

  6. Sol-gel metal oxide and metal oxide/polymer multilayers applied by meniscus coating

    SciTech Connect

    Britten, J.A.; Thomas, I.M.

    1993-10-01

    We are developing a meniscus coating process for manufacturing large-aperture dielectric multilayer high reflectors (HR`s) at ambient conditions from liquid suspensions. Using a lab-scale coater capable of coating 150 mm square substrates, we have produced several HR`s which give 99% + reflection with 24 layers and with edge effects confined to about 10 mm. In calendar 1993 we are taking delivery of an automated meniscus coating machine capable of coating substrates up to 400 mm wide and 600 mm long. The laser-damage threshold and failure stress of sol-gel thin films can be substantially increased through the use of soluble polymers which act as binders for the metal oxide particles comprising the deposited film. Refractive index control of the film is also possible through varying the polymer/oxide ratio. Much of our present effort present is in optimizing oxide particle/binder/solvent formulations for the high-index material. Films from colloidal zirconia strengthened with polyvinylpyrollidone (PVP) have given best results to date. An increase in the laser damage threshold (LDT) for single layers has been shown to significantly increase with increased polymer loading, but as yet the LDT for multilayer stacks remains low.

  7. Design and Preparation of MnO2/CeO2-MnO2 Double-Shelled Binary Oxide Hollow Spheres and Their Application in CO Oxidation.

    PubMed

    Zhang, Jian; Cao, Yidan; Wang, Chang-An; Ran, Rui

    2016-04-06

    Herein, we designed an extremely facile method to prepare well-defined MnO2@CeO2-MnO2 ball-in-ball binary oxide hollow spheres by employing carbon spheres (CSs) as sacrificial templates. The synthesis process involves a novel self-assembled approach to prepare core-shell CSs@CeO2 precursor, which would directly react with KMnO4 aqueous solution to form yolk-shell CSs@MnO2/CeO2-MnO2 precursor in the following step. Well-dispersed Ce-Mn binary oxide with double-shelled hollow sphere structure could be achieved after annealing the precursor in air. The evolution process and formation mechanism of this novel structure were thoroughly studied in this paper. Especially the as-prepared double-shell MnO2/CeO2-MnO2 hollow spheres exhibited enhanced catalytic activity for CO oxidation compared with the pure MnO2 hollow spheres and pure CeO2 hollow spheres. We believe the high surface area, hierarchical porous structures, and strong synergistic interaction between CeO2 and MnO2 contribute to the excellent catalytic activity. Most importantly, this method could be extended to prepare other transition metal oxides. As an example, triple-shelled Co-Mn composite hollow spheres assembled by ultrathin nanoplates were successfully prepared.

  8. Interaction of Metal Oxides with Biomolecules: Implication in Astrobiology

    NASA Astrophysics Data System (ADS)

    Kamaluddin; Iqubal, Md. Asif

    2014-08-01

    Steps of chemical evolution have been designated as formation of biomonomers followed by their polymerization and then to modify in an organized structure leading to the formation of first living cell. Polymerization of biomonomers could have required some catalyst. In addition to clay, role of metal ions and metal complexes as prebiotic catalyst in the synthesis and polymerization of biomonomers cannot be ruled out. Metal oxides are important constituents of Earth crust and that of other planets. These oxides might have adsorbed organic molecules and catalyzed the condensation processes, which may have led to the formation of first living cell. Different studies were performed in order to investigate the role of metal oxides (especially oxides of iron and manganese) in chemical evolution. Iron oxides (goethite, akaganeite and hematite) as well as manganese oxides (MnO, Mn2O3, Mn3O4 and MnO2) were synthesized and their characterization was done using IR, powder XRD, FE-SEM and TEM. Role of above oxides was studied in the adsorption of ribose nucleotides, formation of nucleobases from formamide and oligomerization of amino acids. Above oxides of iron and manganese were found to have good adsorption affinity towards ribose nucleotides, high catalytic activity in the formation of several nucleobases from formamide and oligomerization of glycine and alanine. Characterization of products was performed using UV, IR, HPLC and ESI-MS techniques. Presence of hematite-water system on Mars has been suggested to be a positive indicator in the chemical evolution on Mars.

  9. Oxidation of metal nanoparticles with the grain growth in the oxide

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.

    2017-04-01

    Oxidation of metals can be influenced by the presence of electric field, lattice strain, rearrangement of the oxide structure, and formation of cracks in an oxide. The understanding of the interplay of these factors is still incomplete. We focus on the scenario including the oxide-grain growth. The model used implies that the whole process is limited by diffusion of metal or oxygen atoms along the grain boundaries as it was originally proposed by Fehlner and Mott for macroscopic samples. For nanoparticles, the model predicts a transition from the power-law oxide growth at low conversion to slower growth at high conversion.

  10. Generation of singlet oxygen on the surface of metal oxides

    NASA Astrophysics Data System (ADS)

    Kiselev, V. M.; Kislyakov, I. M.; Burchinov, A. N.

    2016-04-01

    Generation of singlet oxygen on the surface of metal oxides is studied. It is shown that, under conditions of heterogeneous photo-catalysis, along with the conventional mechanism of singlet oxygen formation due to the formation of electron-hole pairs in the oxide structure, there is an additional and more efficient mechanism involving direct optical excitation of molecular oxygen adsorbed on the oxide surface. The excited adsorbate molecule then interacts with the surface or with other adsorbate molecules. It is shown that, with respect to singlet oxygen generation, yttrium oxide is more than an order of magnitude more efficient than other oxides, including titanium dioxide.

  11. Ultraviolet-induced erasable photochromism in bilayer metal oxide films

    NASA Astrophysics Data System (ADS)

    Terakado, Nobuaki; Tanaka, Keiji; Nakazawa, Akira

    2011-09-01

    We demonstrate that the optical transmittance of bilayer samples consisting of pyrolytically coated amorphous Mg-Sn-O and metal oxide films such as In 2O 3 and SnO 2 decreases upon ultraviolet illumination, but can be recovered by annealing in air at ˜300 ∘C. Spectral, structural, and compositional studies suggest that this photochromic phenomenon is induced by photoelectronic excitation in the Mg-Sn-O film, electron injection into the metal oxide, which becomes negatively charged, and subsequent formation of metallic particles, which absorb and/or scatter visible light.

  12. Interactions of Hydrogen Isotopes and Oxides with Metal Tubes

    SciTech Connect

    Glen R. Longhurst

    2008-08-01

    Understanding and accounting for interaction of hydrogen isotopes and their oxides with metal surfaces is important for persons working with tritium systems. Reported data from several investigators have shown that the processes of oxidation, adsorption, absorption, and permeation are all coupled and interactive. A computer model has been developed for predicting the interaction of hydrogen isotopes and their corresponding oxides in a flowing carrier gas stream with the walls of a metallic tube, particularly at low hydrogen concentrations. An experiment has been constructed to validate the predictive model. Predictions from modeling lead to unexpected experiment results.

  13. Strategies to Suppress Cation Vacancies in Metal Oxide Alloys: Consequences for Solar Energy Conversion

    SciTech Connect

    Toroker, Maytal; Carter, Emily A.

    2015-09-01

    First-row transition metal oxides (TMOs) are promising alternative materials for inexpensive and efficient solar energy conversion. However, their conversion efficiency can be deleteriously affected by material imperfections, such as atomic vacancies. In this work, we provide examples showing that in some iron-containing TMOs, iron cation vacancy formation can be suppressed via alloying. We calculate within density functional theory+U theory the iron vacancy formation energy in binary rock-salt oxide alloys that contain iron, manganese, nickel, zinc, and/or magnesium. We demonstrate that formation of iron vacancies is less favorable if we choose to alloy iron(II) oxide with metals that cannot readily accept vacancy-generated holes, e.g., magnesium, manganese, nickel, or zinc. Since there are less available sites for holes and the holes are forced to reside on iron cations, the driving force for iron vacancy formation decreases. These results are consistent with an experiment observing a sharp drop in cation vacancy concentration upon alloying iron(II) oxide with manganese.

  14. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  15. Internal zone growth method for producing metal oxide metal eutectic composites

    DOEpatents

    Clark, Grady W.; Holder, John D.; Pasto, Arvid E.

    1980-01-01

    An improved method for preparing a cermet comprises preparing a compact having about 85 to 95 percent theoretical density from a mixture of metal and metal oxide powders from a system containing a eutectic composition, and inductively heating the compact in a radiofrequency field to cause the formation of an internal molten zone. The metal oxide particles in the powder mixture are effectively sized relative to the metal particles to permit direct inductive heating of the compact by radiofrequency from room temperature. Surface melting is prevented by external cooling or by effectively sizing the particles in the powder mixture.

  16. Fuel management studies of small metal and oxide LMR's

    SciTech Connect

    Khalil, H.; Fujita, E.K.; Yang, S.; Orechwa, Y.

    1986-01-01

    Fuel-cycle analyses performed at Argonne National Laboratory to evaluate and compare the neutronic performance characteristics of small oxide- and metal-fueled LMR's are described. Specific consideration is given to those analyses concerned with optimization of core and blanket configurations, selection of fuel residence time and refueling interval, determination of control rod worths and requirements, development of in-core fuel management strategy, and evaluation of performance characteristics both for startup cycles and for the equilibrium state reached via repeated recycle of discharged fuel. Differences in the computed performance parameters of oxide and metal cores, arising from basic differences in their neutronic characteristics, are identified and discussed. Metal-fueled cores are shown to offer some important performance advantages over oxide cores for small LMR's because of their harder spectrum, superior neutron economy, and greater breeding capacity. These advantages include smaller fissile and heavy metal loadings, lower control-system requirements, and greater adaptability to changes in fuel management scenarios.

  17. Emerging Applications of Liquid Metals Featuring Surface Oxides

    PubMed Central

    2014-01-01

    Gallium and several of its alloys are liquid metals at or near room temperature. Gallium has low toxicity, essentially no vapor pressure, and a low viscosity. Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface. The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance. Here, we show that this solid oxide “skin” enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects. PMID:25283244

  18. Role of oxidative stress in transformation induced by metal mixture.

    PubMed

    Martín, Silva-Aguilar; Emilio, Rojas; Mahara, Valverde

    2011-01-01

    Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.

  19. Functional Metal Oxide Nanostructures: Their Synthesis, Characterization, and Energy Applications

    NASA Astrophysics Data System (ADS)

    Iyer, Aparna

    This research focuses on studying metal oxides (MnO 2, Co3O4, MgO, Y2O3) for various applications including water oxidation and photocatalytic oxidation, developing different synthesis methodologies, and presenting detailed characterization studies of these metal oxides. This research consists of three major parts. The first part is studying novel applications and developing a synthesis method for manganese oxide nanomaterials. Manganese oxide materials were studied for renewable energy applications by using them as catalysts for water oxidation reactions. In this study, various crystallographic forms of manganese oxides (amorphous, 2D layered, 1D 2 x 2 tunnel structures) were evaluated for water oxidation catalysis. Amorphous manganese oxides (AMO) were found to be catalytically active for chemical and photochemical water oxidation compared to cryptomelane type tunnel manganese oxides (2 x 2 tunnels; OMS2) or layered birnessite (OL-1) materials. Detailed characterization was done to establish a correlation between the properties of the manganese oxide materials and their catalytic activities in water oxidation. The gas phase photocatalytic oxidation of 2-propanol under visible light was studied using manganese oxide 2 x 2 tunnel structures (OMS-2) as catalysts (Chapter 3). The reaction is 100% selective to acetone. As suggested by the photocatalytic and characterization data, important factors for the design of active OMS-2 photocatalysts are synthesis methodology, morphology, mixed valency and the release of oxygen from the OMS-2 structure. Manganese oxide octahedral molecular sieves (2 x 2 tunnels; OMS-2) with self-assembled dense or hollow sphere morphologies were fabricated via a room temperature ultrasonic atomization assisted synthesis (Chapter 4). The properties and catalytic activities of these newly developed materials were compared with that of OMS-2 synthesized by conventional reflux route. These materials exhibit exceptionally high catalytic activities

  20. REFINED METALLICITY INDICES FOR M DWARFS USING THE SLoWPoKES CATALOG OF WIDE, LOW-MASS BINARIES

    SciTech Connect

    Dhital, Saurav; Stassun, Keivan G.; Bastien, Fabienne A.; West, Andrew A.; Massey, Angela P.; Bochanski, John J.

    2012-03-15

    We report the results from spectroscopic observations of 113 ultra-wide, low-mass binary systems, largely composed of M0-M3 dwarfs, from the SLoWPoKES catalog of common proper motion pairs identified in the Sloan Digital Sky Survey. Radial velocities of each binary member were used to confirm that they are comoving and, consequently, to further validate the high fidelity of the SLoWPoKES catalog. Ten stars appear to be spectroscopic binaries based on broad or split spectral features, supporting previous findings that wide binaries are likely to be hierarchical systems. We measured the H{alpha} equivalent width of the stars in our sample and found that components of 81% of the observed pairs have similar H{alpha} levels. The difference in H{alpha} equivalent width among components with similar masses was smaller than the range of H{alpha} variability for individual objects. We confirm that the Lepine et al. {zeta}-index traces iso-metallicity loci for most of our sample of M dwarfs. However, we find a small systematic bias in {zeta}, especially in the early-type M dwarfs. We use our sample to recalibrate the definition of {zeta}. While representing a small change in the definition, the new {zeta} is a significantly better predictor of iso-metallicity for the higher-mass M dwarfs.

  1. Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

    PubMed

    Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

    2016-01-01

    Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces.

  2. Application of a mixed metal oxide catalyst to a metallic substrate

    NASA Technical Reports Server (NTRS)

    Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

    2009-01-01

    A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

  3. Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes

    SciTech Connect

    Wang, Feng; Robert, Rosa; Chernova, Natasha A.; Pereira, Nathalie; Omenya, Fredrick; Badway, Fadwa; Hua, Xiao; Ruotolo, Michael; Zhang, Ruigang; Wu, Lijun; Volkov, Vyacheslav; Su, Dong; Key, Baris; Whittingham, M. Stanley; Grey, Clare P.; Amatucci, Glenn G.; Zhu, Yimei; Graetz, Jason

    2015-10-15

    Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast

  4. A high throughput approach to quantify protein adsorption on combinatorial metal/metal oxide surfaces using electron microprobe and spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Byrne, T.; Lohstreter, L.; Filiaggi, M. J.; Bai, Zhijun; Dahn, J. R.

    2008-09-01

    Although metallic biomaterials are widely used, systematic studies of protein adsorption onto such materials are generally lacking. Combinatorial binary films of Al 1-xTi x and Al 1-xNb x (0 ⩽ x ⩽ 1) and corresponding pure element films were produced on glass substrates using a unique magnetron sputtering technique. Fibrinogen and albumin adsorption amounts were measured by wavelength-dispersive spectroscopy (WDS) and spectroscopic ellipsometry (SE) equipment, both high throughput techniques with automated motion stage capabilities. X-ray diffraction revealed that the binary films have crystalline phases present near the ends of the compositional gradient with an amorphous region throughout the interior of the gradient. X-ray photoelectron spectroscopy provided the surface chemistry along the binary films and showed that Al 2O 3 preferentially formed at the surface. Protein adsorption onto these films was found to be closely correlated to the alumina surface fraction, with high alumina content at the surface leading to low amounts of adsorbed fibrinogen and albumin. Protein adsorption amounts obtained with WDS and SE were in excellent agreement for all films. This suggests that this combinatorial materials approach combined with these state-of-the-art, automated high throughput instruments provides a novel way to accurately monitor protein adsorption taking place at the surfaces of these metal/metal oxide materials.

  5. Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

    PubMed Central

    Sun, Yu-Feng; Liu, Shao-Bo; Meng, Fan-Li; Liu, Jin-Yun; Jin, Zhen; Kong, Ling-Tao; Liu, Jin-Huai

    2012-01-01

    Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called “small size effect”, yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given. PMID:22736968

  6. Is Neurotoxicity of Metallic Nanoparticles the Cascades of Oxidative Stress?

    NASA Astrophysics Data System (ADS)

    Song, Bin; Zhang, YanLi; Liu, Jia; Feng, XiaoLi; Zhou, Ting; Shao, LongQuan

    2016-06-01

    With the rapid development of nanotechnology, metallic (metal or metal oxide) nanoparticles (NPs) are widely used in many fields such as cosmetics, the food and building industries, and bio-medical instruments. Widespread applications of metallic NP-based products increase the health risk associated with human exposures. Studies revealed that the brain, a critical organ that consumes substantial amounts of oxygen, is a primary target of metallic NPs once they are absorbed into the body. Oxidative stress (OS), apoptosis, and the inflammatory response are believed to be the main mechanisms underlying the neurotoxicity of metallic NPs. Other studies have disclosed that antioxidant pretreatment or co-treatment can reverse the neurotoxicity of metallic NPs by decreasing the level of reactive oxygen species, up-regulating the activities of antioxidant enzymes, decreasing the proportion of apoptotic cells, and suppressing the inflammatory response. These findings suggest that the neurotoxicity of metallic NPs might involve a cascade of events following NP-induced OS. However, additional research is needed to determine whether NP-induced OS plays a central role in the neurotoxicity of metallic NPs, to develop a comprehensive understanding of the correlations among neurotoxic mechanisms and to improve the bio-safety of metallic NP-based products.

  7. Shape-controlled syntheses of metal oxide nanoparticles by the introduction of rare-earth metals.

    PubMed

    Song, Hyo-Won; Kim, Na-Young; Park, Ji-Eun; Ko, Jae-Hyeon; Hickey, Robert J; Kim, Yong-Hyun; Park, So-Jung

    2017-02-23

    Here, we report the size- and shape-controlled synthesis of metal oxide nanoparticles through the introduction of rare-earth metals. The addition of gadolinium oleate in the synthesis of iron oxide nanoparticles induced sphere-to-cube shape changes of nanoparticles and generated iron oxide nanocubes coated with gadolinium. Based on experimental investigations and density functional theory (DFT) calculations, we attribute the shape change to the facet-selective binding of undecomposed gadolinium oleates. While many previous studies on the shape-controlled syntheses of nanoparticles rely on the stabilization of specific crystal facets by anionic surfactants or their decomposition products, this study shows that the interaction between growing transition metal oxide nanoparticles and rare-earth metal complexes can be used as a robust new mechanism for shape-controlled syntheses. Indeed, we demonstrated that this approach was applicable to other transition metal oxide nanoparticles (i.e., manganese oxide and manganese ferrite) and rare earth metals (i.e., gadolinium, europium, and cerium). This study also demonstrates that the nature of metal-ligand bonding can play an important role in the shape control of nanoparticles.

  8. Methods of making metal oxide nanostructures and methods of controlling morphology of same

    DOEpatents

    Wong, Stanislaus S; Hongjun, Zhou

    2012-11-27

    The present invention includes a method of producing a crystalline metal oxide nanostructure. The method comprises providing a metal salt solution and providing a basic solution; placing a porous membrane between the metal salt solution and the basic solution, wherein metal cations of the metal salt solution and hydroxide ions of the basic solution react, thereby producing a crystalline metal oxide nanostructure.

  9. Synthesis of Nanoporous Metals, Oxides, Carbides, and Sulfides: Beyond Nanocasting.

    PubMed

    Luc, Wesley; Jiao, Feng

    2016-07-19

    Nanoporous metal-based solids are of particular interest because they combine a large quantity of surface metal sites, interconnected porous networks, and nanosized crystalline walls, thus exhibiting unique physical and chemical properties compared to other nanostructures and bulk counterparts. Among all of the synthetic approaches, nanocasting has proven to be a highly effective method for the syntheses of metal oxides with three-dimensionally ordered porous structures and crystalline walls. A typical procedure involves a thermal annealing process of a porous silica template filled with an inorganic precursor (often a metal nitrate salt), which converts the precursor into a desired phase within the silica pores. The final step is the selective removal of the silica template in either a strong base or a hydrofluoric acid solution. In the past decade, nanocasting has become a popular synthetic approach and has enabled the syntheses of a variety of nanoporous metal oxides. However, there is still a lack of synthetic methods to fabricate nanoporous materials beyond simple metal oxides. Therefore, the development of new synthetic strategies beyond nanocasting has become an important direction. This Account describes new progress in the preparation of novel nanoporous metal-based solids for heterogeneous catalysis. The discussion begins with a method called dealloying, an effective method to synthesize nanoporous metals. The starting material is a metallic alloy containing two or more elements followed by a selective chemical or electrochemical leaching process that removes one of the preferential elements, resulting in a highly porous structure. Nanoporous metals, such as Cu, Ag, and CuTi, exhibit remarkable electrocatalytic properties in carbon dioxide reduction, oxygen reduction, and hydrogen evolution reactions. In addition, the syntheses of metal oxides with hierarchical porous structures are also discussed. On the basis of the choice of hard template, nanoporous

  10. Formation of metallic and metal hydrous oxide dispersions

    NASA Technical Reports Server (NTRS)

    Matijevic, E.; Sapieszko, R. S.

    1979-01-01

    The formation, via hydrothermally induced precipitation from homogeneous solution, of a variety of well-defined dispersions of metallic and hydrous metal in the conditions under which the particles are produced (e.g., pH and composition of the growth medium, aging temperature, rate of heating, or degree of agitation) can be readily discerned by following changes in the mass, composition, and morphology of the final solid phase. The generation of colloidal dispersions in the absence of gravity convection or sedimentation effects may result in the appearance of morphological modifications not previously observed in terrestrially formed hydrosols.

  11. Metal-oxide Nanowires for Toxic Gas Detection

    SciTech Connect

    Devineni, D. P.; Stormo, S.; Kempf, W.; Schenkel, J.; Behanan, R.; Lea, Alan S.; Galipeau, David W.

    2007-01-02

    The feasibility of using Electric field enhanced oxidation (EFEO) to fabricate metal-oxide nanowires for sensing toxic gases was investigated. The effects of fabrication parameters such as film thickness, ambient relative humidity, atomic force microscope (AFM) tip bias voltage, force, scan speed and number of scans on the growth of nanowires were determined. The chemical composition of indium-oxide nanowires was verified using Auger electron spectroscopy. It was found that oxygen to indium ration was 1.69, 1.72, 1.71 and 1.84 at depths of 0, 1.3, 2.5, and 3.8 nm, which was near the 1.5:1 expected for stoichiometric indium-oxide film. Future work will include characterizing the electrical and gas sensing properties of the metal-oxide nanowires.

  12. Ethanol oxidation on metal oxide-supported platinum catalysts

    SciTech Connect

    L. M. Petkovic 090468; Sergey N. Rashkeev; D. M. Ginosar

    2009-09-01

    Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on the standard three-way catalysts, the conversion of unburned ethanol is low because both ethanol and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles

  13. The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries

    NASA Astrophysics Data System (ADS)

    Rebassa-Mansergas, A.; Anguiano, B.; García-Berro, E.; Freeman, K. C.; Cojocaru, R.; Manser, C. J.; Pala, A. F.; Gänsicke, B. T.; Liu, X.-W.

    2016-12-01

    The age-metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR for the solar neighbourhood, primarily due to the difficulty in obtaining accurate stellar ages for individual field stars. We have started an observational campaign for providing the much needed observational input by using wide white-dwarf-main-sequence (WDMS) binaries. White dwarfs are `natural' clocks and can be used to derive accurate ages. Metallicities can be obtained from the main-sequence companions. Since the progenitors of white dwarfs and the main-sequence stars were born at the same time, WDMS binaries provide a unique opportunity to observationally constrain in a robust way the properties of the AMR. In this work we present the AMR derived from analysing a pilot sample of 23 WDMS binaries and provide clear observational evidence for the lack of correlation between age and metallicity at young and intermediate ages (0-7 Gyr).

  14. Green nanochemistry: metal oxide nanoparticles and porous thin films from bare metal powders.

    PubMed

    Redel, Engelbert; Petrov, Srebri; Dag, Omer; Moir, Jonathon; Huai, Chen; Mirtchev, Peter; Ozin, Geoffrey A

    2012-01-09

    A universal, simple, robust, widely applicable and cost-effective aqueous process is described for a controlled oxidative dissolution process of micrometer-sized metal powders to form high-purity aqueous dispersions of colloidally stable 3-8 nm metal oxide nanoparticles. Their utilization for making single and multilayer optically transparent high-surface-area nanoporous films is demonstrated. This facile synthesis is anticipated to find numerous applications in materials science, engineering, and nanomedicine.

  15. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications

    NASA Astrophysics Data System (ADS)

    He, Jie; Liu, Yijing; Hood, Taylor C.; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-05-01

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  16. Chemistry of precious metal oxides relevant to heterogeneous catalysis.

    PubMed

    Kurzman, Joshua A; Misch, Lauren M; Seshadri, Ram

    2013-10-01

    The platinum group metals (PGMs) are widely employed as catalysts, especially for the mitigation of automotive exhaust pollutants. The low natural abundance of PGMs and increasing demand from the expanding automotive sector necessitates strategies to improve the efficiency of PGM use. Conventional catalysts typically consist of PGM nanoparticles dispersed on high surface area oxide supports. However, high PGM loadings must be used to counter sintering, ablation, and deactivation of the catalyst such that sufficient activity is maintained over the operating lifetime. An appealing strategy for reducing metal loading is the substitution of PGM ions into oxide hosts: the use of single atoms (ions) as catalytic active sites represents a highly atom-efficient alternative to the use of nanoparticles. This review addresses the crystal chemistry and reactivity of oxide compounds of precious metals that are, or could be relevant to developing an understanding of the role of precious metal ions in heterogeneous catalysis. We review the chemical conditions that facilitate stabilization of the notoriously oxophobic precious metals in oxide environments, and survey complex oxide hosts that have proven to be amenable to reversible redox cycling of PGMs.

  17. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications.

    PubMed

    He, Jie; Liu, Yijing; Hood, Taylor C; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-06-21

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  18. Metal-Catalyzed Oxidation and Photo-oxidation of Glucagon.

    PubMed

    Zhang, Jian

    2016-08-01

    The oxidation of glucagon by the H2O2/Cu(2+) system and by simulated sunlight was studied using HPLC-MS methodologies. It was found that copper ion-catalyzed oxidation is much faster in the residue 1-12 region than in photo-oxidation, but it is slower than photo-oxidation in the residue 18-29 region. This difference is due to the unique feature of the primary sequence of glucagon. The residue 1-12 region contains His-1 and Asp-9 that can bind to Cu(2+) ions and catalyze the oxidation of His-1 and Tyr-10, while the residue 18-29 region lacks these charged residues near the liable Met-27 and Trp-25 and hence no catalysis by the neighboring groups occurs. Fragment (residue 13-17) was more stable than the other regions of the peptide toward photo-oxidation because it contains only one oxidizable residue, Tyr-13. These findings may help explain the mechanism of action of glucagon and provide some hints for the development of effective anti-diabetic drug molecules and stable glucagon formulations.

  19. Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors

    PubMed Central

    Ozawa, Tadashi C; Kauzlarich, Susan M

    2008-01-01

    Layered d-metal pnictide oxides are a unique class of compounds which consist of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into nine structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed. PMID:27877997

  20. ON THE ORIGIN OF THE METALLICITY DEPENDENCE IN DYNAMICALLY FORMED EXTRAGALACTIC LOW-MASS X-RAY BINARIES

    SciTech Connect

    Ivanova, N.; Avendano Nandez, J. L.; Sivakoff, G. R.; Fragos, T.; Kim, D.-W.; Fabbiano, G.; Lombardi, J. C.; Voss, R.

    2012-12-01

    Globular clusters (GCs) effectively produce dynamically formed low-mass X-ray binaries (LMXBs). Observers detect {approx}100 times more LMXBs per stellar mass in GCs compared to stars in the fields of galaxies. Observationally, metal-rich GCs are about three times more likely to contain an X-ray source than their metal-poor counterparts. Recent observations have shown that this ratio holds in extragalactic GCs for all bright X-ray sources with L{sub X} between 2 Multiplication-Sign 10{sup 37} and 5 Multiplication-Sign 10{sup 38} erg s{sup -1}. In this Letter, we propose that the observed metallicity dependence of LMXBs in extragalactic GCs can be explained by the differences in the number densities and average masses of red giants in populations of different metallicities. Red giants serve as seeds for the dynamical production of bright LMXBs via two channels-binary exchanges and physical collisions-and the increase of the number densities and masses of red giants boost LMXB production, leading to the observed difference. We also discuss a possible effect of the age difference in stellar populations of different metallicities.

  1. Advances in metal-induced oxidative stress and human disease.

    PubMed

    Jomova, Klaudia; Valko, Marian

    2011-05-10

    Detailed studies in the past two decades have shown that redox active metals like iron (Fe), copper (Cu), chromium (Cr), cobalt (Co) and other metals undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biological systems. Disruption of metal ion homeostasis may lead to oxidative stress, a state where increased formation of reactive oxygen species (ROS) overwhelms body antioxidant protection and subsequently induces DNA damage, lipid peroxidation, protein modification and other effects, all symptomatic for numerous diseases, involving cancer, cardiovascular disease, diabetes, atherosclerosis, neurological disorders (Alzheimer's disease, Parkinson's disease), chronic inflammation and others. The underlying mechanism of action for all these metals involves formation of the superoxide radical, hydroxyl radical (mainly via Fenton reaction) and other ROS, finally producing mutagenic and carcinogenic malondialdehyde (MDA), 4-hydroxynonenal (HNE) and other exocyclic DNA adducts. On the other hand, the redox inactive metals, such as cadmium (Cd), arsenic (As) and lead (Pb) show their toxic effects via bonding to sulphydryl groups of proteins and depletion of glutathione. Interestingly, for arsenic an alternative mechanism of action based on the formation of hydrogen peroxide under physiological conditions has been proposed. A special position among metals is occupied by the redox inert metal zinc (Zn). Zn is an essential component of numerous proteins involved in the defense against oxidative stress. It has been shown, that depletion of Zn may enhance DNA damage via impairments of DNA repair mechanisms. In addition, Zn has an impact on the immune system and possesses neuroprotective properties. The mechanism of metal-induced formation of free radicals is tightly influenced by the action of cellular antioxidants. Many low-molecular weight antioxidants (ascorbic acid (vitamin C), alpha

  2. Metal Iodides in Polyiodide Networks: Synthesis and Structure of Binary Metal Iodide-Iodine Compounds Stable under Ambient Conditions.

    PubMed

    Svensson, Per H.; Kloo, Lars

    1999-07-12

    The reaction between HgI(2)(C(6)N(4)H(12)) and HI in ethanol solution results in the binary metal iodide-iodine complexes [C(6)N(4)H(13)](2)(Hg(2)I(6))(1/2)(HgI(3)).(1)/(2)I(2), which are stable under ambient conditions. The structure consists of C(6)N(4)H(13)(+) cations, discrete trigonal HgI(3)(-) ions, and.Hg(2)I(6)(2)(-).I(2).Hg(2)I(6)(2)(-). chains in the crystallographic b direction, which are formed by I(2) molecules connecting the bridging iodines of the Hg(2)I(6)(2)(-) dimers. The intra- and intermolecular I-I distances of iodine in the chain are 2.7402(15) and 3.438(1) Å, respectively. The Raman spectrum of [C(6)N(4)H(13)](2)(Hg(2)I(6))(1/2)(HgI(3)).(1)/(2)I(2) confirms the interaction between the iodine molecules and Hg(2)I(6)(2)(-) ions. The structure of [NH(4)](HgI(3)).H(2)O, obtained during the synthesis of [C(6)N(4)H(13)](2)(Hg(2)I(6))(1/2)(HgI(3)).(1)/(2)I(2), is also reported. Crystal data for [C(6)N(4)H(13)](2)(Hg(2)I(6))(1/2)(HgI(3)).(1)/(2)I(2): a = 14.275(3) Å, b = 19.721(4) Å, c = 10.416(2) Å, orthorhombic space group Pbam; Z = 4. Crystal data for [NH(4)](HgI(3)).H(2)O: a = 8.7246(4) Å, b = 9.7860(3) Å, c = 11.1103(4) Å, orthorhombic space group Ama2; Z = 4.

  3. CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.

    1990-01-01

    Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

  4. Tuning Ferritin's Band Gap through Mixed Metal Oxide Nanoparticle Formation.

    PubMed

    Olsen, Cameron; Embley, Jacob; Hansen, Kameron; Henrichsen, Andrew; Peterson, J; Colton, John S; Watt, Richard

    2017-03-23

    This study uses the formation of a mixed metal oxide inside ferritin to tune the band gap energy of the ferritin mineral. The mixed metal oxide is composed of both Co and Mn, and is formed by reacting aqueous Co2+ with MnO4- in the presence of apoferritin. Altering the ratio between the two reactants allowed for controlled tuning of the band gap energies. All minerals formed were indirect band gap materials, with indirect band gap energies ranging from 0.52 to 1.30 eV. The direct transitions were also measured, with energy values ranging from 2.71 to 3.11 eV. Tuning the band gap energies of these samples changes the wavelengths absorbed by each mineral, increasing ferritin's potential in solar-energy harvesting. Additionally, the success of using MnO4- in ferritin mineral formation opens the possibility for new mixed metal oxide cores inside ferritin.

  5. Ion exchange properties of novel hydrous metal oxide materials

    SciTech Connect

    Gardner, T.J.; McLaughlin, L.I.

    1996-12-31

    Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.

  6. Nanophase transition metal oxides show large thermodynamically driven shifts in oxidation-reduction equilibria.

    PubMed

    Navrotsky, Alexandra; Ma, Chengcheng; Lilova, Kristina; Birkner, Nancy

    2010-10-08

    Knowing the thermodynamic stability of transition metal oxide nanoparticles is important for understanding and controlling their role in a variety of industrial and environmental systems. Using calorimetric data on surface energies for cobalt, iron, manganese, and nickel oxide systems, we show that surface energy strongly influences their redox equilibria and phase stability. Spinels (M(3)O(4)) commonly have lower surface energies than metals (M), rocksalt oxides (MO), and trivalent oxides (M(2)O(3)) of the same metal; thus, the contraction of the stability field of the divalent oxide and expansion of the spinel field appear to be general phenomena. Using tabulated thermodynamic data for bulk phases to calculate redox phase equilibria at the nanoscale can lead to errors of several orders of magnitude in oxygen fugacity and of 100 to 200 kelvin in temperature.

  7. Photocatalytic Water Oxidation over Metal Oxide Nanosheets Having a Three-Layer Perovskite Structure.

    PubMed

    Oshima, Takayoshi; Eguchi, Miharu; Maeda, Kazuhiko

    2016-02-19

    Metal oxide nanosheets having a three-layer perovskite structure were studied as photocatalysts for water oxidation in the presence of IO3 (-) as a reversible electron acceptor. This work examined the effects of the lateral dimensions and composition of the nanosheets as well as metal oxide co-catalysts deposited on the restacked nanosheets. Depositing metal oxides capable of promoting reduction reactions on the nanosheets were found to promote the water oxidation activity. In contrast, the lateral dimensions and the degree of crystallinity of the nanosheets had little effect on the activity. Experimental results demonstrated that the reduction of IO3 (-) is the rate-limiting step in this reaction and that nanosheets with less distorted structures are advantageous with regard to increasing both light absorption and the mobility of photoexcited charge carriers.

  8. Anaerobic Nitrate-Dependent Metal Bio-Oxidation

    NASA Astrophysics Data System (ADS)

    Weber, K.; Knox, T.; Achenbach, L. A.; Coates, J. D.

    2007-12-01

    Direct biological oxidation of reduced metals (Fe(II) and U(IV)) coupled to nitrate reduction at circumneutral pH under anaerobic conditions has been recognized in several environments as well as pure culture. Several phylogentically diverse mesophilic bacteria have been described as capable of anaerobic, nitrate-dependent Fe(II) oxidation (NFOx). Our recent identification of a freshwater mesophilic, lithoautotroph, Ferrutens nitratireducens strain 2002, capable of growth through NFOx presents an opportunity to further study metal bio- oxidation. Continuing physiological studies revealed that in addition to Fe(II) oxidation, strain 2002 is capable of oxidizing U(IV) (4 μM) in washed cell suspensions with nitrate serving as the electron acceptor. Pasteurized cultures exhibited abiotic oxidation of 2 μM U(IV). Under growth conditions, strain 2002 catalyzed the oxidation of 12 μM U(IV) within a two week period. Cultures amended with sodium azide, an electron transport inhibitor, demonstrated limited oxidation (7 μM) similar to pasteurized cultures, supporting the direct role of electron transport in U(IV) bio-oxidation. The oxidation of U(IV) coupled denitrification at circumneutral pH would yield enough energy to support anaerobic microbial growth (ΔG°'= -460.36 kJ/mole). It is currently unknown whether or not strain 2002 can couple this metabolism to growth. The growth of F. nitratireducens strain 2002 utilizing Fe(II) as the sole electron donor was previously demonstrated. The amount of U(IV) (~12 μM) that strain 2002 oxidized under similar autotrophic growth conditions yields 0.0019 kJ, enough energy for the generation of ATP (5.3 x 10-20 kJ ATP-1), but not enough energy for cell replication as calculated for nitrate-dependent Fe(II) oxidizing conditions (0.096 kJ) assuming a similar metabolism. In addition to F. nitratireducens strain 2002, a nitrate-dependent Fe(II) oxidizing bacterium isolated from U contaminated groundwater, Diaphorobacter sp. strain

  9. Promoting Photochemical Water Oxidation with Metallic Band Structures.

    PubMed

    Liu, Hongfei; Moré, René; Grundmann, Henrik; Cui, Chunhua; Erni, Rolf; Patzke, Greta R

    2016-02-10

    The development of economic water oxidation catalysts is a key step toward large-scale water splitting. However, their current exploration remains empirical to a large extent. Elucidating the correlations between electronic properties and catalytic activity is crucial for deriving general and straightforward catalyst design principles. Herein, strongly correlated electronic systems with abundant and easily tunable electronic properties, namely La(1-x)Sr(x)BO3 perovskites and La(2-x)Sr(x)BO4 layered perovskites (B = Fe, Co, Ni, or Mn), were employed as model systems to identify favorable electronic structures for water oxidation. We established a direct correlation between the enhancement of catalytic activity and the insulator to metal transition through tuning the electronic properties of the target perovskite families via the La(3+)/Sr(2+) ratio. Their improved photochemical water oxidation performance was clearly linked to the increasingly metallic character. These electronic structure-activity relations provide a promising guideline for constructing efficient water oxidation catalysts.

  10. The mechanism of electroforming of metal oxide memristive switches.

    PubMed

    Joshua Yang, J; Miao, Feng; Pickett, Matthew D; Ohlberg, Douglas A A; Stewart, Duncan R; Lau, Chun Ning; Williams, R Stanley

    2009-05-27

    Metal and semiconductor oxides are ubiquitous electronic materials. Normally insulating, oxides can change behavior under high electric fields--through 'electroforming' or 'breakdown'--critically affecting CMOS (complementary metal-oxide-semiconductor) logic, DRAM (dynamic random access memory) and flash memory, and tunnel barrier oxides. An initial irreversible electroforming process has been invariably required for obtaining metal oxide resistance switches, which may open urgently needed new avenues for advanced computer memory and logic circuits including ultra-dense non-volatile random access memory (NVRAM) and adaptive neuromorphic logic circuits. This electrical switching arises from the coupled motion of electrons and ions within the oxide material, as one of the first recognized examples of a memristor (memory-resistor) device, the fourth fundamental passive circuit element originally predicted in 1971 by Chua. A lack of device repeatability has limited technological implementation of oxide switches, however. Here we explain the nature of the oxide electroforming as an electro-reduction and vacancy creation process caused by high electric fields and enhanced by electrical Joule heating with direct experimental evidence. Oxygen vacancies are created and drift towards the cathode, forming localized conducting channels in the oxide. Simultaneously, O(2-) ions drift towards the anode where they evolve O(2) gas, causing physical deformation of the junction. The problematic gas eruption and physical deformation are mitigated by shrinking to the nanoscale and controlling the electroforming voltage polarity. Better yet, electroforming problems can be largely eliminated by engineering the device structure to remove 'bulk' oxide effects in favor of interface-controlled electronic switching.

  11. Method for continuous synthesis of metal oxide powders

    DOEpatents

    Berry, David A.; Haynes, Daniel J.; Shekhawat, Dushyant; Smith, Mark W.

    2015-09-08

    A method for the rapid and continuous production of crystalline mixed-metal oxides from a precursor solution comprised of a polymerizing agent, chelated metal ions, and a solvent. The method discharges solution droplets of less than 500 .mu.m diameter using an atomizing or spray-type process into a reactor having multiple temperature zones. Rapid evaporation occurs in a first zone, followed by mixed-metal organic foam formation in a second zone, followed by amorphous and partially crystalline oxide precursor formation in a third zone, followed by formation of the substantially crystalline mixed-metal oxide in a fourth zone. The method operates in a continuous rather than batch manner and the use of small droplets as the starting material for the temperature-based process allows relatively high temperature processing. In a particular embodiment, the first zone operates at 100-300.degree. C., the second zone operates at 300-700.degree. C., and the third operates at 700-1000.degree. C., and fourth zone operates at at least 700.degree. C. The resulting crystalline mixed-metal oxides display a high degree of crystallinity and sphericity with typical diameters on the order of 50 .mu.m or less.

  12. Solution synthesis of metal oxides for electrochemical energy storage applications.

    PubMed

    Xia, Xinhui; Zhang, Yongqi; Chao, Dongliang; Guan, Cao; Zhang, Yijun; Li, Lu; Ge, Xiang; Bacho, Ignacio Mínguez; Tu, Jiangping; Fan, Hong Jin

    2014-05-21

    This article provides an overview of solution-based methods for the controllable synthesis of metal oxides and their applications for electrochemical energy storage. Typical solution synthesis strategies are summarized and the detailed chemical reactions are elaborated for several common nanostructured transition metal oxides and their composites. The merits and demerits of these synthesis methods and some important considerations are discussed in association with their electrochemical performance. We also propose the basic guideline for designing advanced nanostructure electrode materials, and the future research trend in the development of high power and energy density electrochemical energy storage devices.

  13. Sonochemical water splitting in the presence of powdered metal oxides.

    PubMed

    Morosini, Vincent; Chave, Tony; Virot, Matthieu; Moisy, Philippe; Nikitenko, Sergey I

    2016-03-01

    Kinetics of hydrogen formation was explored as a new chemical dosimeter allowing probing the sonochemical activity of argon-saturated water in the presence of micro- and nano-sized metal oxide particles exhibiting catalytic properties (ThO2, ZrO2, and TiO2). It was shown that the conventional sonochemical dosimeter based on H2O2 formation is hardly applicable in such systems due to catalytic degradation of H2O2 at oxide surface. The study of H2 generation revealed that at low-frequency ultrasound (20 kHz) the sonochemical water splitting is greatly improved for all studied metal oxides. The highest efficiency is observed for relatively large micrometric particles of ThO2 which is assigned to ultrasonically-driven particle fragmentation accompanied by mechanochemical water molecule splitting. The nanosized metal oxides do not exhibit particle size reduction under ultrasonic treatment but nevertheless yield higher quantities of H2. The enhancement of sonochemical water splitting in this case is most probably resulting from better bubble nucleation in heterogeneous systems. At high-frequency ultrasound (362 kHz), the effect of metal oxide particles results in a combination of nucleation and ultrasound attenuation. In contrast to 20 kHz, micrometric particles slowdown the sonolysis of water at 362 kHz due to stronger attenuation of ultrasonic waves while smaller particles show a relatively weak and various directional effects.

  14. Exposure characterization of metal oxide nanoparticles in the workplace.

    PubMed

    Curwin, Brian; Bertke, Steve

    2011-10-01

    This study presents exposure data for various metal oxides in facilities that produce or use nanoscale metal oxides. Exposure assessment surveys were conducted at seven facilities encompassing small, medium, and large manufacturers and end users of nanoscale (particles <0.1 μm diameter) metal oxides, including the oxides of titanium, magnesium, yttrium, aluminum, calcium, and iron. Half- and full-shift sampling consisting of various direct-reading and mass-based area and personal aerosol sampling was employed to measure exposure for various tasks. Workers in large facilities performing handling tasks had the highest mass concentrations for all analytes. However, higher mass concentrations occurred in medium facilities and during production for all analytes in area samples. Medium-sized facilities had higher particle number concentrations in the air, followed by small facilities for all particle sizes measured. Production processes generally had the highest particle number concentrations, particularly for the smaller particles. Similar to particle number, the medium-sized facilities and production process had the highest particle surface area concentration. TEM analysis confirmed the presence of the specific metal oxides particles of interest, and the majority of the particles were agglomerated, with the predominant particle size being between 0.1 and 1 μm. The greatest potential for exposure to workers occurred during the handling process. However, the exposure is occurring at levels that are well below established and proposed limits.

  15. CATALYTIC OXIDATION OF DIMETHYL SULFIDE WITH OZONE: EFFECT OF PROMOTER AND PHYSICO-CHEMICAL PROPERTIES OF METAL OXIDE CATALYSTS

    EPA Science Inventory

    This study reports improved catalytic activities and stabilities for the oxidation of dimethyl sulfide (DMS), a major pollutant of pulp and paper mills. Ozone was used as an oxidant and Cu, Mo, V, Cr and Mn metal oxides, and mixed metal oxides support on y-alumina as catalysts ov...

  16. Galvanic Exchange in Colloidal Metal/Metal-Oxide Core/Shell Nanocrystals

    PubMed Central

    2016-01-01

    While galvanic exchange is commonly applied to metallic nanoparticles, recently its applicability was expanded to metal-oxides. Here the galvanic exchange is studied in metal/metal-oxide core/shell nanocrystals. In particular Sn/SnO2 is treated by Ag+, Pt2+, Pt4+, and Pd2+. The conversion dynamics is monitored by in situ synchrotron X-ray diffraction. The Ag+ treatment converts the Sn cores to the intermetallic AgxSn (x ∼ 4) phase, by changing the core’s crystal structure. For the analogous treatment by Pt2+, Pt4+, and Pd2+, such a galvanic exchange is not observed. This different behavior is caused by the semipermeability of the naturally formed SnO2 shell, which allows diffusion of Ag+ but protects the nanocrystal cores from oxidation by Pt and Pd ions. PMID:27635186

  17. Metal current collect protected by oxide film

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

    2004-05-25

    Provided are low-cost, mechanically strong, highly electronically conductive current collects and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical devices having as current interconnects a ferritic steel felt or screen coated with a protective oxide film.

  18. Simultaneous photoreductive removal of copper (II) and selenium (IV) under visible light over spherical binary oxide photocatalyst.

    PubMed

    Aman, Noor; Mishra, T; Hait, J; Jana, R K

    2011-02-15

    Waste water of copper mines and copper processing plant contains both copper and selenium ions with other contaminants. In this paper simultaneous photoreductive removal of copper (II) and selenium (IV) is studied for the first time using spherical binary oxide photocatalysts under visible light. All the synthesized materials are found to be mesoporous in nature with reasonably high surface area. Among a range of hole scavengers, only EDTA (ethylene diamine tetraacetic acid) and formic acid are found to be the most active for the reduction reaction. A comparative study is carried out using both the hole scavengers varying reaction time, concentration, pH etc. For a single contaminant, EDTA is found to be the best for Cu(II) reduction whereas formic acid is the best for Se(IV) reduction. In a mixed solution both EDTA and formic acid perform very well under visible light irradiation. Highest photocatalytic reduction in a mixed solution is observed at pH 3. Among all the synthesized materials, TiZr-10 performs as the best photocatalyst for both Cu(II) and Se(IV) reduction. However under UV light, Degussa P25 performs slightly better than TiZr-10. Present study shows that 100 ppm of mixed solution can be removed under visible light in 40 min of reaction using TiZr-10 as catalyst. Photodeposited material is found to be copper selenide rather than pure copper and selenium metal. This indicates that the waste water containing copper and selenium ions can be efficiently treated under visible or solar light.

  19. A Green Strategy to Prepare Metal Oxide Superstructure from Metal-Organic Frameworks

    PubMed Central

    Song, Yonghai; Li, Xia; Wei, Changting; Fu, Jinying; Xu, Fugang; Tan, Hongliang; Tang, Juan; Wang, Li

    2015-01-01

    Metal or metal oxides with diverse superstructures have become one of the most promising functional materials in sensor, catalysis, energy conversion, etc. In this work, a novel metal-organic frameworks (MOFs)-directed method to prepare metal or metal oxide superstructure was proposed. In this strategy, nodes (metal ions) in MOFs as precursors to form ordered building blocks which are spatially separated by organic linkers were transformed into metal oxide micro/nanostructure by a green method. Two kinds of Cu-MOFs which could reciprocally transform by changing solvent were prepared as a model to test the method. Two kinds of novel CuO with three-dimensional (3D) urchin-like and 3D rods-like superstructures composed of nanoparticles, nanowires and nanosheets were both obtained by immersing the corresponding Cu-MOFs into a NaOH solution. Based on the as-formed CuO superstructures, a novel and sensitive nonenzymatic glucose sensor was developed. The small size, hierarchical superstructures and large surface area of the resulted CuO superstructures eventually contribute to good electrocatalytic activity of the prepared sensor towards the oxidation of glucose. The proposed method of hierarchical superstructures preparation is simple, efficient, cheap and easy to mass production, which is obviously superior to pyrolysis. It might open up a new way for hierarchical superstructures preparation. PMID:25669731

  20. Effects of binary mixtures of inducers (toluene analogs) and of metals on bioluminescence induction of a recombinant bioreporter strain.

    PubMed

    Kong, In Chul

    2014-10-13

    This paper investigated the effects of binary mixtures of bioluminescence inducers (toluene, xylene isomers, m-toluate) and of metals (Cu, Cd, As(III), As(V), and Cr) on bioluminescence activity of recombinant (Pm-lux) strain KG1206. Different responses and sensitivities were observed depending on the types and concentrations of mixtures of inducers or metals. In the case of inducer mixtures, antagonistic and synergistic modes of action were observed, whereas metal mixtures showed all three modes of action. Antagonistic mode of action was most common for mixtures of indirect inducers, which showed bioluminescence ranging from 29% to 62% of theoretically expected effects (P(E)). On the other hand, synergistic mode of action was observed for mixtures of direct and indirect inducers, which showed bioluminescence between 141% and 243% of P(E). In the case of binary metal mixtures, bioluminescence activities were ranged from 62% to 75% and 113% to 164% of P(E) for antagonistic and synergistic modes of action, respectively (p-values 0.0001-0.038). Therefore, mixture effects could not be generalized since they were dependent on both the types and concentrations of chemicals, suggesting that biomonitoring may constitute a better strategy by investigating types and concentrations of mixture pollutants at contaminated sites.

  1. Plasma electrolytic oxide coatings on valve metals and their activity in CO oxidation

    NASA Astrophysics Data System (ADS)

    Lukiyanchuk, I. V.; Rudnev, V. S.; Tyrina, L. M.; Chernykh, I. V.

    2014-10-01

    Two approaches have been examined for obtaining titanium- or aluminum-supported catalysts with transition and noble metals using the plasma electrolytic oxidation (PEO) technique. Elemental compositions, distribution of active elements and catalytic activity in CO oxidation have been compared for composites formed by one-stage PEO technique and those obtained as a result of modification of PEO coatings by impregnation.

  2. Mesoporous amorphous binary Ru-Ti oxides as bifunctional catalysts for non-aqueous Li-O2 batteries.

    PubMed

    Kim, Jisu; Jo, HeeGoo; Wu, Mihye; Yoon, Dae-Ho; Kang, Yongku; Jung, Ha-Kyun

    2017-04-07

    Mesoporous amorphous binary Ru-Ti oxides were prepared as bifunctional catalysts for non-aqueous Li-O2 batteries, and their electrochemical performance was investigated for the first time. A Li-O2 battery with mesoporous amorphous binary Ru-Ti oxides exhibited a remarkably high capacity of 27100 mAh g(-1) as well as a reduced overpotential. A GITT analysis suggested that the introduction of amorphous TiO2 to amorphous RuO2 was responsible for the enhanced kinetics toward both the oxygen reduction reaction and oxygen evolution reaction. Excellent cyclic stability up to 230 cycles was achieved, confirming the applicability of the new bifunctional catalyst in non-aqueous Li-O2 batteries.

  3. Mesoporous amorphous binary Ru–Ti oxides as bifunctional catalysts for non-aqueous Li–O2 batteries

    NASA Astrophysics Data System (ADS)

    Kim, Jisu; Jo, HeeGoo; Wu, Mihye; Yoon, Dae-Ho; Kang, Yongku; Jung, Ha-Kyun

    2017-04-01

    Mesoporous amorphous binary Ru–Ti oxides were prepared as bifunctional catalysts for non-aqueous Li–O2 batteries, and their electrochemical performance was investigated for the first time. A Li–O2 battery with mesoporous amorphous binary Ru–Ti oxides exhibited a remarkably high capacity of 27100 mAh g‑1 as well as a reduced overpotential. A GITT analysis suggested that the introduction of amorphous TiO2 to amorphous RuO2 was responsible for the enhanced kinetics toward both the oxygen reduction reaction and oxygen evolution reaction. Excellent cyclic stability up to 230 cycles was achieved, confirming the applicability of the new bifunctional catalyst in non-aqueous Li–O2 batteries.

  4. All-alkoxide synthesis of strontium-containing metal oxides

    DOEpatents

    Boyle, Timothy J.

    2001-01-01

    A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

  5. A novel microstructured metal-supported solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Fernández-González, R.; Hernández, E.; Savvin, S.; Núñez, P.; Makradi, A.; Sabaté, N.; Esquivel, J. P.; Ruiz-Morales, J. C.

    2014-12-01

    An innovative design, alternative to the conventional metal supported fuel cells (MSC) is proposed. This new design of Solid Oxide Fuel Cell (SOFC), comprises a 200 μm layer of a honeycomb-metallic framework with hexagonal cells which supports a 250 μm layer of electrolyte. Each hexagonal cell is further functionalized with a thin 5-10 μm of Ni-YSZ anode. This new design allows a reduction of ∼65% of the metallic supporting material, rendering performances over 300 mW cm-2 under pure hydrogen at 850 °C, with an OCV of ∼1.1 V.

  6. Fluoride removal from aqueous solution by Al(III)-Zr(IV) binary oxide adsorbent

    NASA Astrophysics Data System (ADS)

    Zhu, Jiuya; Lin, Xiaoyan; Wu, Pengwei; Zhou, Qiusheng; Luo, Xuegang

    2015-12-01

    In this study, a novel binary oxide adsorbent of Al2O3-ZrO2 was prepared via coprecipitation followed by calcination method, and the calcination temperatures were investigated. The adsorbent was characterized by XRD, EDX and XPS. The batch adsorption experiments were carried out at different parameters, such as solution pH, adsorbent dose, contact time, initial fluoride concentration and adsorption temperature, to evaluate the fluoride removal performance. The results showed that the adsorption isotherm was better described by the linear Langmuir model, and a maximum adsorption capacity was 114.54 mg/g. The adsorption kinetics was well fitted by the linear pseudo-second-order, and the correlation coefficient value (R2) was 0.997. The thermodynamic parameters of ΔH0, ΔS0 and ΔG0 were calculated, which showed that the fluoride adsorption process was spontaneous and exothermic. And the possible adsorption mechanism of the adsorbent for fluoride could involve the ligand-exchange and ion-exchange based on the results in the study.

  7. Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

    SciTech Connect

    Tarakci, Mehmet

    2011-12-15

    The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

  8. Direct chemical reduction of neptunium oxide to neptunium metal using calcium and calcium chloride

    NASA Astrophysics Data System (ADS)

    Squires, Leah N.; Lessing, Paul

    2016-04-01

    A process of direct reduction of neptunium oxide to neptunium metal using calcium metal as the reducing agent is discussed. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can be easily removed upon cooling. The direct reduction technique consistently produces high purity (98%-99% pure) neptunium metal.

  9. Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

    DOEpatents

    Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

    2010-07-13

    Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

  10. Laboratory SIP signatures associated with oxidation of disseminated metal sulfides.

    PubMed

    Placencia-Gómez, Edmundo; Slater, Lee; Ntarlagiannis, Dimitrios; Binley, Andrew

    2013-05-01

    Oxidation of metal sulfide minerals is responsible for the generation of acidic waters rich in sulfate and metals. When associated with the oxidation of sulfide ore mine waste deposits the resulting pore water is called acid mine drainage (AMD); AMD is a known environmental problem that affects surface and ground waters. Characterization of oxidation processes in-situ is challenging, particularly at the field scale. Geophysical techniques, spectral induced polarization (SIP) in particular, may provide a means of such investigation. We performed laboratory experiments to assess the sensitivity of the SIP method to the oxidation mechanisms of common sulfide minerals found in mine waste deposits, i.e., pyrite and pyrrhotite, when the primary oxidant agent is dissolved oxygen. We found that SIP parameters, e.g., phase shift, the imaginary component of electrical conductivity and total chargeability, decrease as the time of exposure to oxidation and oxidation degree increase. This observation suggests that dissolution-depletion of the mineral surface reduces the capacitive properties and polarizability of the sulfide minerals. However, small increases in the phase shift and imaginary conductivity do occur during oxidation. These transient increases appear to correlate with increases of soluble oxidizing products, e.g., Fe(2+) and Fe(3+) in solution; precipitation of secondary minerals and the formation of a passivating layer to oxidation coating the mineral surface may also contribute to these increases. In contrast, the real component of electrical conductivity associated with electrolytic, electronic and interfacial conductance is sensitive to changes in the pore fluid chemistry as a result of the soluble oxidation products released (Fe(2+) and Fe(3+)), particularly for the case of pyrrhotite minerals.

  11. Ammonia sensors based on metal oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Sekhar Rout, Chandra; Hegde, Manu; Govindaraj, A.; Rao, C. N. R.

    2007-05-01

    Ammonia sensing characteristics of nanoparticles as well as nanorods of ZnO, In2O3 and SnO2 have been investigated over a wide range of concentrations (1 800 ppm) and temperatures (100 300 °C). The best values of sensitivity are found with ZnO nanoparticles and SnO2 nanostructures. Considering all the characteristics, the SnO2 nanostructures appear to be good candidates for sensing ammonia, with sensitivities of 222 and 19 at 300 °C and 100 °C respectively for 800 ppm of NH3. The recovery and response times are respectively in the ranges 12 68 s and 22 120 s. The effect of humidity on the performance of the sensors is not marked up to 60% at 300 °C. With the oxide sensors reported here no interference for NH3 is found from H2, CO, nitrogen oxides, H2S and SO2.

  12. Synthesis of Oxides Containing Transition Metals

    DTIC Science & Technology

    1990-07-09

    prepare a number of vanadium spinels by electrolyzing melts of | ) sodium tetraborate and sodium fluoride in which were dissolved the appropriate... sodium hydroxide melts contained in alumina crucibles. Electrodes of iron, cobalt or nickel were used, depending on the desired composition of the final...product. Crystals of tungsten and molybdenum oxide "bronzes" have been grown by electrolytic reduction of tungstate or molybdate melts. Extensive

  13. Interactive effects of waterborne metals in binary mixtures on short-term gill-metal binding and ion uptake in rainbow trout (Oncorhynchus mykiss).

    PubMed

    Niyogi, Som; Nadella, Sunita R; Wood, Chris M

    2015-08-01

    Metal binding to fish gills forms the basis of the biotic ligand model (BLM) approach, which has emerged as a useful tool for conducting site-specific water quality assessments for metals. The current BLMs are designed to assess the toxicity of individual metals, and cannot account for the interactive effects of metal mixtures to aquatic organisms including fish. The present study was designed mainly to examine the interactive effects of waterborne metals (Cd, Zn, Cu, Ag, and Ni) in specific binary combinations on short-term (3h) gill-metal binding and essential ion (Ca(2+) and Na(+)) uptake (a physiological index of toxicity) in fish, using juvenile freshwater rainbow trout (Oncorhynchus mykiss) as the model species. We hypothesized that binary mixtures of metals that share a common mode of uptake and toxicity (e.g., Cd and Zn - Ca(2+) antagonists, Cu and Ag - Na(+) antagonists) would reduce the gill binding of each other via competitive interactions and induce less than additive effects on ion transport. In addition, the mixture of metals that have different modes of uptake and toxicity (e.g., Cd and Cu, or Cd and Ni) would not exhibit any interactive effects either on gill-metal binding or ion transport. We found that both Zn and Cu reduced gill-Cd binding and vice versa, however, Ni did not influence gill-Cd binding in fish. Surprisingly, Ag was found to stimulate gill-Cu binding especially at high exposure concentrations, whereas, Cu had no effect on gill-Ag binding. The inhibitory effect of Cd and Zn in mixture on branchial Ca(2+) uptake was significantly greater than that of Cd or Zn alone. Similarly, the inhibitory effect of Cu and Ag in mixture on branchial Na(+) uptake was significantly greater than that of Cu or Ag alone. The inhibitory effects of Cd and Zn mixture on Ca(2+) uptake as well as Cu and Ag mixture on Na(+) uptake were found to follow the principles of simple additivity. In contrast, no significant additive effect on either Ca(2+) or Na

  14. Lithium metal oxide electrodes for lithium cells and batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil; Kim, Jaekook

    2006-11-14

    A lithium metal oxide positive electrode for a non-aqueous lithium cell is disclosed. The cell is prepared in its initial discharged state and has a general formula xLiMO.sub.2.(1-x)Li.sub.2M'O.sub.3 in which 0oxidation state and with at least one ion being Ni, and where M' is one or more ions with an average tetravalent oxidation state. Complete cells or batteries are disclosed with anode, cathode and electrolyte as are batteries of several cells connected in parallel or series or both.

  15. Activation of carbon dioxide on metal and metal oxide surfaces

    SciTech Connect

    Tan, C.D.; Chuang, S.S.C.

    1995-12-31

    The environmental concern about the impact of CO{sub 2} has grown recently due to its rapidly increasing concentration. Deforestation strongly affects the natural reduction of CO{sub 2} by water into carbohydrates by photosynthesis. Industrial utilization of CO{sub 2} by heterogeneous catalytic reactions can be one of the effective ways to cut the CO{sub 2} level. The first step in catalytic reaction of CO{sub 2} is the adsorption. The objective of this study is to investigate the adsorption of CO{sub 2} on the Rh/Al{sub 2}O{sub 3} surfaces. Rh is selected for this study because of its unique activity to catalyze a number of CO{sub 2} related reactions. In situ infrared results show that CO{sub 2} adsorbed on the alumina oxide support as bidentate carbonate and non-coordinated carbon which are the dominant species during the CO{sub 2} adsorption.

  16. Influence of gadolinium content on the tetragonal to cubic phase transition in zirconia-silica binary oxides

    SciTech Connect

    Behera, Pallavi Suhasinee; Vasanthavel, S.; Ponnilavan, V.; Kannan, S.

    2015-05-15

    The present study reports the effect of gadolinium (Gd{sup 3+}) in zirconia-silica (ZrO{sub 2}-SiO{sub 2}) binary oxides. The pure ZrO{sub 2}-SiO{sub 2} synthesized at 1100 °C was tetragonal. The addition of Gd{sup 3+} in the concentration range of 5%–10% resulted in the formation of t-ZrO{sub 2}, whereas higher contents of Gd{sup 3+} led to the formation of cubic ZrO{sub 2} (c-ZrO{sub 2}). The presence of Gd{sup 3+} also affected the lattice parameters of both t-ZrO{sub 2} and c-ZrO{sub 2}. Magnetic studies confirmed a steady increase in the paramagnetic behaviour with increasing content of Gd{sup 3+}. - Graphical abstract: t-ZrO{sub 2} to c-ZrO{sub 2} phase transition influenced by Gd{sup 3+} content. - Highlights: • Sol-gel synthesis of Gd{sup 3+} added SiO{sub 2}-ZrO{sub 2} binary oxides. • Significant role of Gd{sup 3+} content in the tetragonal and cubic stabilization of ZrO{sub 2}. • Phase stability of either tetragonal or cubic stabilization till 1100 °C. • Gd{sup 3+} additions ensured additional paramagnetic behaviour in SiO{sub 2}-ZrO{sub 2} binary oxide.

  17. Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

    SciTech Connect

    Jernigan, Glenn Geoffrey

    1994-10-01

    Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu2O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu2O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/mol < Cu2O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N2 and CO2. At the end of each reaction, the catalyst was found to be Cu2O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.

  18. Porous metal oxide microspheres from ion exchange resin

    NASA Astrophysics Data System (ADS)

    Picart, S.; Parant, P.; Caisso, M.; Remy, E.; Mokhtari, H.; Jobelin, I.; Bayle, J. P.; Martin, C. L.; Blanchart, P.; Ayral, A.; Delahaye, T.

    2015-07-01

    This study is devoted to the synthesis and the characterization of porous metal oxide microsphere from metal loaded ion exchange resin. Their application concerns the fabrication of uranium-americium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Those mixed oxide ceramics are one of the materials envisaged for americium transmutation in sodium fast neutron reactors. The advantage of such microsphere precursor compared to classical oxide powder is the diminution of the risk of fine dissemination which can be critical for the handling of highly radioactive powders such as americium based oxides and the improvement of flowability for the filling of compaction chamber. Those millimetric oxide microspheres incorporating uranium and americium were synthesized and characterizations showed a very porous microstructure very brittle in nature which occurred to be adapted to shaping by compaction. Studies allowed to determine an optimal heat treatment with calcination temperature comprised between 700-800 °C and temperature rate lower than 2 °C/min. Oxide Precursors were die-pressed into pellets and then sintered under air to form regular ceramic pellets of 95% of theoretical density (TD) and of homogeneous microstructure. This study validated thus the scientific feasibility of the CRMP process to prepare bearing americium target in a powder free manner.

  19. Positron studies of metal-oxide-semiconductor structures

    SciTech Connect

    Au, H.L.; Asoka-Kumar, P.; Nielsen, B.; Lynn, K.G. )

    1993-03-15

    Positron annihilation spectroscopy provides a new probe to study the properties of interface traps in metal-oxide semiconductors (MOS). Using positrons, we have examined the behavior of the interface traps as a function of gate bias. We propose a simple model to explain the positron annihilation spectra from the interface region of a MOS capacitor.

  20. The Extraction of Metals from Their Oxides and Sulphides.

    ERIC Educational Resources Information Center

    Price, Alun H.

    1980-01-01

    Briefly describes the application of thermodynamics (system at equilibrium) to the study of the extraction of metals from their oxides (dynamic situation). It is more relevant to study the temperature variation of the equilibrium constants of the reaction than to study the free energy approach. (Author/SK)

  1. High-temperature Complementary Metal Oxide Semiconductors (CMOS)

    NASA Technical Reports Server (NTRS)

    Mcbrayer, J. D.

    1981-01-01

    The results of an investigation into the possibility of using complementary metal oxide semiconductor (CMOS) technology for high temperature electronics are presented. A CMOS test chip was specifically developed as the test bed. This test chip incorporates CMOS transistors that have no gate protection diodes; these diodes are the major cause of leakage in commercial devices.

  2. Metal complexes of substituted Gable porphyrins as oxidation catalysts

    DOEpatents

    Lyons, J.E.; Ellis, P.E. Jr.; Wagner, R.W.

    1996-01-02

    Transition metal complexes of Gable porphyrins are disclosed having two porphyrin rings connected through a linking group, and having on the porphyrin rings electron-withdrawing groups, such as halogen, nitro or cyano. These complexes are useful as catalysts for the oxidation of organic compounds, e.g. alkanes.

  3. Metal complexes of substituted Gable porphyrins as oxidation catalysts

    DOEpatents

    Lyons, James E.; Ellis, Jr., Paul E.; Wagner, Richard W.

    1996-01-01

    Transition metal complexes of Gable porphyrins having two porphyrin rings connected through a linking group, and having on the porphyrin rings electron-withdrawing groups, such as halogen, nitro or cyano. These complexes are useful as catalysts for the oxidation of organic compounds, e.g. alkanes.

  4. Control of cerium oxidation state through metal complex secondary structures

    SciTech Connect

    Levin, Jessica R.; Dorfner, Walter L.; Carroll, Patrick J.; Schelter, Eric J.

    2015-08-11

    A series of alkali metal cerium diphenylhydrazido complexes, Mx(py)y[Ce(PhNNPh)4], M = Li, Na, and K, x = 4 (Li and Na) or 5 (K), and y = 4 (Li), 8 (Na), or 7 (K), were synthesized to probe how a secondary coordination sphere would modulate electronic structures at a cerium cation. The resulting electronic structures of the heterobimetallic cerium diphenylhydrazido complexes were found to be strongly dependent on the identity of the alkali metal cations. When M = Li+ or Na+, the cerium(III) starting material was oxidized with concomitant reduction of 1,2-diphenylhydrazine to aniline. Reduction of 1,2-diphenylhydrazine was not observed when M = K+, and the complex remained in the cerium(III) oxidation state. Oxidation of the cerium(III) diphenylhydrazido complex to the Ce(IV) diphenylhydrazido one was achieved through a simple cation exchange reaction of the alkali metals. As a result, UV-Vis spectroscopy, FTIR spectroscopy, electrochemistry, magnetic susceptibility, and DFT studies were used to probe the oxidation state and the electronic changes that occurred at the metal centre.

  5. Control of cerium oxidation state through metal complex secondary structures

    DOE PAGES

    Levin, Jessica R.; Dorfner, Walter L.; Carroll, Patrick J.; ...

    2015-08-11

    A series of alkali metal cerium diphenylhydrazido complexes, Mx(py)y[Ce(PhNNPh)4], M = Li, Na, and K, x = 4 (Li and Na) or 5 (K), and y = 4 (Li), 8 (Na), or 7 (K), were synthesized to probe how a secondary coordination sphere would modulate electronic structures at a cerium cation. The resulting electronic structures of the heterobimetallic cerium diphenylhydrazido complexes were found to be strongly dependent on the identity of the alkali metal cations. When M = Li+ or Na+, the cerium(III) starting material was oxidized with concomitant reduction of 1,2-diphenylhydrazine to aniline. Reduction of 1,2-diphenylhydrazine was not observedmore » when M = K+, and the complex remained in the cerium(III) oxidation state. Oxidation of the cerium(III) diphenylhydrazido complex to the Ce(IV) diphenylhydrazido one was achieved through a simple cation exchange reaction of the alkali metals. As a result, UV-Vis spectroscopy, FTIR spectroscopy, electrochemistry, magnetic susceptibility, and DFT studies were used to probe the oxidation state and the electronic changes that occurred at the metal centre.« less

  6. Metal oxide charge transport material doped with organic molecules

    DOEpatents

    Forrest, Stephen R.; Lassiter, Brian E.

    2016-08-30

    Doping metal oxide charge transport material with an organic molecule lowers electrical resistance while maintaining transparency and thus is optimal for use as charge transport materials in various organic optoelectronic devices such as organic photovoltaic devices and organic light emitting devices.

  7. OXIDATION-RESISTANT COATING ON ARTICLES OF YTTRIUM METAL

    DOEpatents

    Wilder, D.R.; Wirkus, C.D.

    1963-11-01

    A process for protecting yttrium metal from oxidation by applying thereto and firing thereon a liquid suspension of a fritted ground silicate or phosphate glass plus from 5 to 35% by weight of CeO/sub 2/ is presented. (AEC)

  8. Oxidation resistant filler metals for direct brazing of structural ceramics

    DOEpatents

    Moorhead, Arthur J.

    1986-01-01

    A method of joining ceramics and metals to themselves and to one another is described using essentially pure trinickel aluminide and trinickel aluminide containing small amounts of carbon. This method produces strong joints that can withstand high service temperatures and oxidizing environments.

  9. CMOS array design automation techniques. [metal oxide semiconductors

    NASA Technical Reports Server (NTRS)

    Ramondetta, P.; Feller, A.; Noto, R.; Lombardi, T.

    1975-01-01

    A low cost, quick turnaround technique for generating custom metal oxide semiconductor arrays using the standard cell approach was developed, implemented, tested and validated. Basic cell design topology and guidelines are defined based on an extensive analysis that includes circuit, layout, process, array topology and required performance considerations particularly high circuit speed.

  10. Detection of Specific Gases by Metal Oxide Catalysis

    DTIC Science & Technology

    2008-06-28

    good results. IR screening techniques hold significant promise for catalyst library screening , but were not useful within the scope of this project...compounds that are more responsive to a particular gas than the oxide of a single metal. Catalyst library screening by means of IR area thermography

  11. Metal-accelerated oxidation in plant cell death

    SciTech Connect

    Czuba, M. )

    1993-05-01

    Cadmium and mercury toxicity is further enhanced by external oxidizing conditions O[sub 3] or inherent plant processes. Lepidium sativum L, Lycopersicon esculentum Mill., or Phaseolus vulgaris L, were grown inpeat-lite to maturity under continuous cadmium exposure followed by one oxidant (O[sub 3]-6 hr. 30 pphm) exposure, with or without foliar calcium pretreatments. In comparison, Daucus carota, L and other species grown in a 71-V suspension, with or without 2,4-D were exposed continuously to low levels of methylmercury during exponential growth and analyzed in aggregates of distinct populations. Proteins were extracted and analyzed. Mechanisms of toxicity and eventual cell death are Ca-mediated and involve chloroplast, stomatal-water relations and changes in oxidant-anti-oxidant components in cells. Whether the metal-accelerated oxidative damage proceeds to cell death, depends on the species and its differential biotransformation system and cell association component.

  12. Actinomycetes mediated biogenic synthesis of metal and metal oxide nanoparticles: Progress and challenges.

    PubMed

    Manimaran, Manickavelu; Kannabiran, Krishnan

    2017-03-07

    Actinomycetes mediated biogenic synthesis of metal nanoparticles and their antimicrobial activities are well documented. Actinomycetes facilitate both intracellular and extracellular metal nanoparticles synthesis and are efficient candidates for the production of polydispersed, stable and ultra-small size metal nanoparticles. Secondary metabolites and new chemical entities derived from actinomycetes have not been extensively studied for the synthesis of metal/ metal oxide nanoparticles. The present review focuses on biogenic synthesis of metal nanoparticles from actinomycetes and the scope for exploring actinomycetes derived compounds (enzymes, organics acids and bioactive compounds) as metal and metal oxide reducing agents for the synthesis of desired nanoparticles. This review also focuses on challenges faced in the applications nanoparticles and the methods to synthesise biogenic metal nanoparticles with desired physiochemical properties such as ultra-small size, large surface to mass ratio, high reactivity etc. Methods to evade their toxicity and unique interactions with biological systems to improve their chance as an alternative therapeutic agent in medical and pharmaceutical industry are also discussed. This article is protected by copyright. All rights reserved.

  13. Perspectives on the metallic interconnects for solid oxide fuel cells.

    PubMed

    Zhu, Wei-Zhong; Yan, Mi

    2004-12-01

    The various stages and progress in the development of interconnect materials for solid oxide fuel cells (SOFCs) over the last two decades are reviewed. The criteria for the application of materials as interconnects are highlighted. In-terconnects based on lanthanum chromite ceramics demonstrate many inherent drawbacks and therefore are only useful for SOFCs operating around 1000 degrees C. The advance in the research of anode-supported flat SOFCs facilitates the replacement of ceramic interconnects with metallic ones due to their significantly lowered working temperature. Besides, interconnects made of metals or alloys offer many advantages as compared to their ceramic counterpart. The oxidation response and thermal expansion behaviors of various prospective metallic interconnects are examined and evaluated. The minimization of contact resistance to achieve desired and reliable stack performance during their projected lifetime still remains a highly challenging issue with metallic interconnects. Inexpensive coating materials and techniques may play a key role in pro-moting the commercialization of SOFC stack whose interconnects are constructed of some current commercially available alloys. Alternatively, development of new metallic materials that are capable of forming stable oxide scales with sluggish growth rate and sufficient electrical conductivity is called for.

  14. Physicochemical of pillared clays prepared by several metal oxides

    NASA Astrophysics Data System (ADS)

    Rinaldi, Nino; Kristiani, Anis

    2017-03-01

    Natural clays could be modified by the pillarization method, called as Pillared Clays (PILCs). PILCs have been known as porous materials that can be used for many applications, one of the fields is catalysis. PILCs as two dimensional materials are interesting because their structures and textural properties can be controlled by using a metal oxide as the pillar. Different metal oxide used as the pillar causes different properties results of pillared clays. Usually, natural smectite clays/bentonites are used as a raw material. Therefore, a series of bentonite pillared by metal oxides was prepared through pillarization method. Variation of metals pillared into bentonite are aluminium, chromium, zirconium, and ferro. The physicochemical properties of catalysts were characterized by using X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analysis, and Fourier transform infrared spectroscopy (FTIR) measurement. Noteworthy characterization results showed that different metals pillared into bentonite affected physical and chemical properties, i.e. basal spacing, surface area, pore size distribution, thermal stability and acidity.

  15. Metal-Polycyclic Aromatic Hydrocarbon Mixture Toxicity in Hyalella azteca. 2. Metal Accumulation and Oxidative Stress as Interactive Co-toxic Mechanisms.

    PubMed

    Gauthier, Patrick T; Norwood, Warren P; Prepas, Ellie E; Pyle, Greg G

    2015-10-06

    Mixtures of metals and polycyclic aromatic hydrocarbons (PAHs) are commonly found in aquatic environments. Emerging reports have identified that more-than-additive mortality is common in metal-PAH mixtures. Individual aspects of PAH toxicity suggest they may alter the accumulation of metals and enhance metal-derived reactive oxygen species (ROS). Redox-active metals (e.g., Cu and Ni) are also capable of enhancing the redox cycling of PAHs. Accordingly, we explored the mutual effects redox-active metals and PAHs have on oxidative stress, and the potential for PAHs to alter the accumulation and/or homeostasis of metals in juvenile Hyalella azteca. Amphipods were exposed to binary mixtures of Cu, Cd, Ni, or V, with either phenanthrene (PHE) or phenanthrenequinone (PHQ). Mixture of Cu with either PAH produced striking more-than-additive mortality, whereas all other mixtures amounted to strictly additive mortality following 18-h exposures. We found no evidence to suggest that interactive effects on ROS production were involved in the more-than-additive mortality of Cu-PHE and Cu-PHQ mixtures. However, PHQ increased the tissue concentration of Cu in juvenile H. azteca, providing a potential mechanism for the observed more-than-additive mortality.

  16. Metal oxide semiconductor thin-film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  17. Reaction and spectroscopic study of supported metal oxide catalysts

    NASA Astrophysics Data System (ADS)

    Ramani, Narayanan C.

    The role of surface structure, cation reducibility, surface acidity and the effect of the support was examined in the reaction of 1-butene over well characterized, supported metal oxide catalysts. Cr, Mo and W oxides supported on SiOsb2 were used to study the effect of structure, surface acidity and cation reducibility in the isomerization and selective oxidation of 1-butene. Supported oxides of Mo on TiOsb2,\\ Alsb2Osb3 and SiOsb2 were used to understand the role of the support in the selective oxidation of 1-butene. The surface acidity of SiOsb2 supported Cr, Mo, W and V oxide catalysts was examined by pyridine adsorption. Existing theoretical models of acidity were compared against experimental data. Over Mo(VI)/SiOsb2 and W(VI)/SiOsb2, isomerization through both a Bronsted catalyzed pathway and an allylic pathway were observed, while only the allylic pathway was observed over Cr(VI)/SiOsb2. The greater reducibility of the Cr cation compared to Mo and W cations was identified as the reason for the allylic pathway being dominant over Cr(VI)/SiOsb2. Cation reducibility was again seen to play an important role in the selective oxidation of 1-butene over SiOsb2 supported metal oxides. The turn over frequencies for 1,3-butadiene formation followed the trend in red-ox ability, with Cr > Mo > W. The activity to 1,3-butadiene formation did not change with increasing weight loading of Mo over TiOsb2 and Alsb2Osb3 supports. An analysis of the turn over frequencies of the supports and the supported cations revealed that a support effect, through the bridging oxygen ligand, dominated the intrinsic cation reducibility of Mo for these catalysts. The existence of Bronsted acidity over SiOsb2 supported Cr, Mo and V oxides was shown by an analysis of the OH region of the infrared spectrum, and by the adsorption of 1-butene and pyridine. Existing theoretical models for Bronsted acidity over supported metal oxides were shown to be inadequate to describe the observed results over

  18. Unravelling Small-Polaron Transport in Metal Oxide Photoelectrodes.

    PubMed

    Rettie, Alexander J E; Chemelewski, William D; Emin, David; Mullins, C Buddie

    2016-02-04

    Transition-metal oxides are a promising class of semiconductors for the oxidation of water, a process that underpins both photoelectrochemical water splitting and carbon dioxide reduction. However, these materials are limited by very slow charge transport. This is because, unlike conventional semiconductors, material aspects of metal oxides favor the formation of slow-moving, self-trapped charge carriers: small polarons. In this Perspective, we seek to highlight the salient features of small-polaron transport in metal oxides, offer guidelines for their experimental characterization, and examine recent transport studies of two prototypical oxide photoanodes: tungsten-doped monoclinic bismuth vanadate (W:BiVO4) and titanium-doped hematite (Ti:α-Fe2O3). Analysis shows that conduction in both materials is well-described by the adiabatic small-polaron model, with electron drift mobility (distinct from the Hall mobility) values on the order of 10(-4) and 10(-2) cm(2) V(-1) s(-1), respectively. Future directions to build a full picture of charge transport in this family of materials are discussed.

  19. Metal-Organic Frameworks as Catalysts for Oxidation Reactions.

    PubMed

    Dhakshinamoorthy, Amarajothi; Asiri, Abdullah M; Garcia, Hermenegildo

    2016-06-06

    This Concept is aimed at describing the current state of the art in metal-organic frameworks (MOFs) as heterogeneous catalysts for liquid-phase oxidations, focusing on three important substrates, namely, alkenes, alkanes and alcohols. Emphases are on the nature of active sites that have been incorporated within MOFs and on future targets to be set in this area. Thus, selective alkene epoxidation with peroxides or oxygen catalyzed by constitutional metal nodes of MOFs as active sites are still to be developed. Moreover, no noble metal-free MOF has been reported to date that can act as a general catalyst for the aerobic oxidation of primary and secondary aliphatic alcohols. In contrast, in the case of alkanes, a target should be to tune the polarity of MOF internal pores to control the outcome of the autooxidation process, resulting in the selective formation of alcohol/ketone mixtures at high conversion.

  20. Acute tellurium toxicity from ingestion of metal-oxidizing solutions.

    PubMed

    Yarema, Mark C; Curry, Steven C

    2005-08-01

    Tellurium is an element used in the vulcanization of rubber and in metal-oxidizing solutions to blacken or tarnish metals. Descriptions of human toxicity from tellurium ingestion are rare. We report the clinical course of 2 children who ingested metal-oxidizing solutions containing substantial concentrations of tellurium. Clinical features included vomiting, black discoloration of the oral mucosa, and a garlic odor to the breath. One patient developed corrosive injury to the esophagus secondary to the high concentration of hydrochloric acid in the solution. Both patients recovered without serious sequelae, which is typical of tellurium toxicity. An awareness of situations in which children may be exposed to tellurium and its clinical presentation may assist clinicians in the diagnosis of this rare poisoning.

  1. Surface oxidation of metals by oxygen ion bombardment

    NASA Astrophysics Data System (ADS)

    Alov, Nikolai V.

    2007-03-01

    Surface oxidation of molybdenum, tungsten, niobium and tantalum by low-energy oxygen ion beams is investigated using X-ray photoelectron spectroscopy (XPS). Oxygen ion bombardment of molybdenum and tungsten surfaces leads to the formation of thin oxide films containing metals in oxidation states 4+, 5+ and 6+. At the initial stage of irradiation, rapid surface oxidation of molybdenum and tungsten was observed. At higher fluences the oxidation reaches saturation and the surface composition remains almost unchanged with increasing fluence. Oxygen ion bombardment of niobium and tantalum surfaces leads to the formation of thin oxide films containing niobium and tantalum in oxidation states 2+, 4+ and 5+. At the initial stage of irradiation, again rapid surface oxidation of niobium and tantalum was observed. At higher fluences the population of Nb2+ and Nb4+, Ta2+ and Ta4+ reaches a maximum and then begins to decrease. The population of Nb5+ and Ta5+ continues to increase and finally the entire oxide films consists of only Nb5+ and Ta5+, respectively.

  2. Biocidal properties of metal oxide nanoparticles and their halogen adducts

    NASA Astrophysics Data System (ADS)

    Haggstrom, Johanna A.; Klabunde, Kenneth J.; Marchin, George L.

    2010-03-01

    Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (Δ Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores. The procedure consists of a membrane method. Transmission electron micrographs are used to compare nanoparticle-treated and untreated cells and spores. It is proposed that the abrasive character of the particles, the oxidative power of the halogens/interhalogens, and the electrostatic attraction between the metal oxides and the biological material are responsible for high biocidal activities. While some activity was demonstrated, bacterial endospores were more resistant to nanoparticle treatment than the vegetative bacteria.

  3. Nanoscale limitations in metal oxide electrocatalysts for oxygen evolution.

    PubMed

    Viswanathan, Venkatasubramanian; Pickrahn, Katie L; Luntz, Alan C; Bent, Stacey F; Nørskov, Jens K

    2014-10-08

    Metal oxides are attractive candidates for low cost, earth-abundant electrocatalysts. However, owing to their insulating nature, their widespread application has been limited. Nanostructuring allows the use of insulating materials by enabling tunneling as a possible charge transport mechanism. We demonstrate this using TiO2 as a model system identifying a critical thickness, based on theoretical analysis, of about ∼4 nm for tunneling at a current density of ∼1 mA/cm(2). This is corroborated by electrochemical measurements on conformal thin films synthesized using atomic layer deposition (ALD) identifying a similar critical thickness. We generalize the theoretical analysis deriving a relation between the critical thickness and the location of valence band maximum relative to the limiting potential of the electrochemical surface process. The critical thickness sets the optimum size of the nanoparticle oxide electrocatalyst and this provides an important nanostructuring requirement for metal oxide electrocatalyst design.

  4. Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

    PubMed

    Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

    2015-11-16

    Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy.

  5. Oxide/ metal/oxide nanolaminate structures for application of transparent electrodes

    NASA Astrophysics Data System (ADS)

    Dikov, Hr; Ivanova, T.; Vitanov, P.

    2016-10-01

    Transparent and conductive oxide/ metal/ oxide nanolaminate structures were deposited on glass and polymer substrate by RF magnetron sputtering without substrate heating. The Ag nanoparticles with different size and distance between neighboring particles were located on the interface of two thin oxide layers. This sputtering configuration allows obtaining thin films with homogeneous thickness. The three targets give the opportunity to deposit successively three different layers without opening the chamber. The developed process for transparent conducting coating is a low temperature and it is suitable for application on organic materials as substrate and foils. The experiment with different substrates manifest that the optical transparency of the conducting coating depends on substrate material. The obtained results have demonstrated that the nanolaminate structures oxide/metal/oxide (OMO) as TCO coating are especially suitable for applications in flexible electronics and optoelectronics

  6. Volatile organometallic complexes suitable for use in chemical vapor depositions on metal oxide films

    DOEpatents

    Giolando, Dean M.

    2003-09-30

    Novel ligated compounds of tin, titanium, and zinc are useful as metal oxide CVD precursor compounds without the detriments of extreme reactivity yet maintaining the ability to produce high quality metal oxide coating by contact with heated substrates.

  7. Self-Organized Growth, Structure, and Magnetism of Monatomic Transition-Metal Oxide Chains

    NASA Astrophysics Data System (ADS)

    Ferstl, Pascal; Hammer, Lutz; Sobel, Christopher; Gubo, Matthias; Heinz, Klaus; Schneider, M. Alexander; Mittendorfer, Florian; Redinger, Josef

    2016-07-01

    We report on the self-organized growth of monatomic transition-metal oxide chains of (3 ×1 ) periodicity and unusual M O2 stoichiometry (M =Ni , Co, Fe, Mn) on Ir(100). We analyze their structural and magnetic properties by means of quantitative LEED, STM, and density functional theory (DFT) calculations. LEED analyses reveal a fascinating common atomic structure in which the transition-metal atoms sit above a missing-row structure of the surface and are coupled to the substrate only via oxygen atoms. This structure is confirmed by DFT calculations with structural parameters deviating by less than 1.7 pm. The DFT calculations predict that the NiO2 chains are nonmagnetic, CoO2 chains are ferromagnetic, while FeO2 and MnO2 are antiferromagnetic. All structures show only weak magnetic interchain coupling. Further, we demonstrate the growth of oxide chains of binary alloys of Co and Ni or Fe on Ir(100), which allows us to produce well-controlled ensembles of ferromagnetic chains of different lengths separated by nonmagnetic or antiferromagnetic segments.

  8. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    NASA Astrophysics Data System (ADS)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  9. Formation of porous metal oxides in the anodization process.

    PubMed

    Sample, C; Golovin, A A

    2006-10-01

    A theory of the formation of nanoscale porous structures in oxides of metals grown by anodization is developed. It is shown that a growing oxide layer can become unstable which yields the formation of a spatially irregular array of pores. The instability is shown to result from a nonlinear dependence of electrochemical kinetics at the metal-oxide and oxide-electrolyte interfaces on the overpotential which is governed by the Butler-Volmer relation. The conditions for the instability of the oxide layer are found. The dependence of the oxide conductivity on the electric field is taken into account and is shown to have a destabilizing effect. A weakly nonlinear analysis is performed and it shows that the system evolution near the instability threshold is described by the Kuramoto-Sivashinsky equation. Farther from threshold, in the long-wave approximation, a system of strongly nonlinear equations is derived and solved numerically; this system describes the formation of deep irregular pores. In a particular case, a self-similar solution describing the propagation of a pore with a paraboloidal shape is found.

  10. Degradation of C-hordein by metal-catalysed oxidation.

    PubMed

    Huang, Xin; Kanerva, Päivi; Salovaara, Hannu; Sontag-Strohm, Tuula

    2016-04-01

    C-hordein is a monomeric prolamin protein in barley. The unusual primary structure of C-hordein has highly repetitive sequences and forms a secondary structure of beta-turns. C-hordein structure is similar to that of collagen protein, whose degradation by metal-catalysed oxidation has been intensively studied. No information exists on the metal catalysed oxidation of C-hordein, however. In this study, copper-catalysed hydrogen peroxide induced oxidation of C-hordein caused substantial degradation and formed some insoluble compounds. The use of a gliadin standard in R5 ELISA determinations causes an overestimation of hordeins in a sample. A C-hordein standard was therefore directly used as a standard, thus allowing the C-hordein to be analysed as its oxidised prolamin product. After 48 h of oxidation, the prolamin concentration of oxidised C-hordein decreased to 20% of its original amount for competitive ELISA, and to 3% for sandwich ELISA methods. Carbonyl groups were formed during the oxidation. Backbone fragmentation and side-chain modification suggested structural changes of R5 epitopes in C-hordein. Oxidation is an alternative to enzymatic hydrolysis when degrading and modifying C-hordein.

  11. Mechanistic aspects of photooxidation of polyhydroxylated molecules on metal oxides.

    SciTech Connect

    Shkrob, I. A.; Marin, T. M.; Sevilla, M. D.; Chemerisov, S.

    2011-03-24

    Polyhydroxylated molecules, including natural carbohydrates, are known to undergo photooxidation on wide-gap transition-metal oxides irradiated by ultraviolet light. In this study, we examine mechanistic aspects of this photoreaction on aqueous TiO{sub 2}, {alpha}-FeOOH, and {alpha}-Fe{sub 2}O{sub 3} particles using electron paramagnetic resonance (EPR) spectroscopy and site-selective deuteration. We demonstrate that the carbohydrates are oxidized at sites involved in the formation of oxo bridges between the chemisorbed carbohydrate molecule and metal ions at the oxide surface. This bridging inhibits the loss of water (which is the typical reaction of the analogous free radicals in bulk solvent) promoting instead a rearrangement that leads to elimination of the formyl radical. For natural carbohydrates, the latter reaction mainly involves carbon-1, whereas the main radical products of the oxidation are radical arising from H atom loss centered on carbon-1, -2, and -3 sites. Photoexcited TiO{sub 2} oxidizes all of the carbohydrates and polyols, whereas {alpha}-FeOOH oxidizes some of the carbohydrates, and {alpha}-Fe{sub 2}O{sub 3} is unreactive. These results serve as a stepping stone for understanding the photochemistry on mineral surfaces of more complex biomolecules such as nucleic acids.

  12. Solubility Behavior and Phase Stability of Transition Metal Oxides in Alkaline Hydrothermal Environments

    SciTech Connect

    S.E. Ziemniak

    2000-05-18

    The solubility behavior of transition metal oxides in high temperature water is interpreted by recognizing three types of chemical reaction equilibria: metal oxide hydration/dehydration, metal oxide dissolution and metal ion hydroxocomplex formation. The equilibria are quantified using thermodynamic concepts and the thermochemical properties of the metal oxides/ions representative of the most common constituents of construction metal alloys, i.e., element shaving atomic numbers between Z = 22 (Ti) and Z = 30 (Zn), are summarized on the basis of metal oxide solubility studies conducted in the laboratory. Particular attention is devoted to the uncharged metal ion hydrocomplex, M{sup Z}(OH){sub Z}(aq), since its thermochemical properties define minimum solubilities of the metal oxide at a given temperature. Experimentally-extracted values of standard partial molal entropy (S{sup 0}) for the transition metal ion neutral hydroxocomplex are shown to be influenced by ligand field stabilization energies and complex symmetry.

  13. Lithium vanadium oxide: A heavy fermion transition metal oxide

    NASA Astrophysics Data System (ADS)

    Kondo, Shinichiro

    LiVsb2Osb4 has the face-centered-cubic normal-spinel structure and is a metal. The preparative method and characterization of high-purity polycrystalline samples are herein reported. The intrinsic susceptibility chi, electronic heat capacity Csbe, nuclear magnetic resonance and thermal expansion measurements revealed that LiVsb2Osb4 shows a crossover from high temperature T localized magnetic moment behavior to low-T heavy Fermi liquid behavior. chi follows the Curie-Weiss law above ˜50 K with a Curie constant corresponding to a V S=1/2 spin and g-factor ˜2. The Weiss temperature indicates antiferromagnetic interactions between V local moments. chi becomes nearly T independent below ˜30K with a shallow broad maximum at T≈16K. Field-cooled and zero-field-cooled magnetization measurements in low applied magnetic fields H=10{-}100 G from 1.8 to 50 K showed no evidence for spin-glass ordering. The small amounts of paramagnetic impurities (S=3/2 to 4) in the samples were characterized using low-T isothermal magnetization Mspobs(H) measurement data. The observed electronic heat capacity coefficient gammaequiv Csbe/T≈0.42 J/mol Ksp2 at 1 K is extraordinarily large for a transition metal compound, the Wilson ratio ≈1.7, and the Korringa ratio ≈0.5. X-ray and neutron diffraction measurements down to 4 K found no distortion from the cubic structure. Neutron diffraction and dilatometry measurements indicate a strong enhancement of the thermal expansion coefficient and Gruneisen parameter below ˜20 K. Muon spin relaxation for a magnetically pure sample showed no evidence of static magnetic ordering above 0.02 K. Superconductivity was not observed above 0.01 K. All these measurements are consistent with a heavy Fermi liquid (HF) interpretation at low T. Theories which apply to some conventional f-electron HF compounds, the Kondo and Coqblin-Schrieffer models, fail to self-consistently explain chi(T) and Csbe(T) of LiVsb2Osb4. Geometric frustration inherent in the V

  14. Coupling characteristics of thin-film metal-oxide-metal diodes at 10.6 microns

    NASA Technical Reports Server (NTRS)

    Wang, S. Y.; Gustafson, T. K.; Izawa, T.

    1975-01-01

    Direct detection experiments have demonstrated the coherent coupling of 10.6 micrometer radiation into photolithographically fabricated metal-oxide-metal tunnel junctions. A CO2 laser beam mechanically chopped at 1 KHz was focused at a variable angle of incidence with a power density of about 10 W/sq cm at the diodes. Diodes in which the junction resistance was much greater than the lead resistance displayed angular characteristics dominated by coherent antenna coupling.

  15. Surface plasmon dispersion analysis in the metal-oxide-metal tunnel diode

    NASA Technical Reports Server (NTRS)

    Donohue, J. F.; Wang, E. Y.

    1987-01-01

    A detailed model of surface plasmon dispersion in the metal-oxide-metal tunnel diode is presented in order to clarify the spectral emission from this diode. The model predicts the location of the spectral peaks and the emission between the peaks by considering the effects of retardation on the surface plasmon. A nonradiative mode is found to play a major role in the transition from the visible to UV peaks in the diode spectra.

  16. Electrocatalysis using transition metal carbide and oxide nanocrystals

    NASA Astrophysics Data System (ADS)

    Regmi, Yagya N.

    Carbides are one of the several families of transition metal compounds that are considered economic alternatives to catalysts based on noble metals and their compounds. Phase pure transition metal carbides of group 4-6 metals, in the first three periods, were synthesized using a common eutectic salt flux synthesis method, and their electrocatalytic activities compared under uniform electrochemical conditions. Mo2C showed highest hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) activities among the nine metal carbides investigated, but all other metal carbides also showed substantial activities. All the metal carbides showed remarkable enhancement in catalytic activities as supports, when compared to traditional graphitic carbon as platinum support. Mo2C, the most active transition metal carbide electrocatalyst, was prepared using four different synthesis routes, and the synthesis route dependent activities compared. Bifunctional Mo 2C that is HER as well as oxygen evolution reaction (OER) active, was achieved when the carbide was templated on a multiwalled carbon nanotube using carbothermic reduction method. Bimetallic carbides of Fe, Co, and Ni with Mo or W were prepared using a common carbothermic reduction method. Two different stoichiometries of bimetallic carbides were obtained for each system within a 60 °C temperature window. While the bimetallic carbides showed relatively lower electrocatalytic activities towards HER and ORR in comparison to Mo2C and WC, they revealed remarkably higher OER activities than IrO2 and RuO2, the state-of-the-art OER catalysts. Bimetallic oxides of Fe, Co, and Ni with Mo and W were also prepared using a hydrothermal synthesis method and they also revealed OER activities that are much higher than RuO2 and IrO2. Additionally, the OER activities were dependent on the degree and nature of hydration in the bimetallic oxide crystal lattice, with the completely hydrated, as synthesized, cobalt molybdate and nickel

  17. Trap-limited photovoltage in ultrathin metal oxide layers

    NASA Astrophysics Data System (ADS)

    Dittrich, Th.; Duzhko, V.; Koch, F.; Kytin, V.; Rappich, J.

    2002-04-01

    Photovoltage signals were observed at ultrathin metal oxide (TiO2,Cu2O, ZnO)/ metal structures by transient and spectral photovoltage (PV) techniques. The sign, the spectral behavior and the time-dependent relaxation of the PV are determined by the nature of the traps in the metal oxide layers. At lower temperatures, the relaxation of the PV signal in TiO2 layers is controlled by recombination due to the overlap of the wave functions of the spatially separated electrons and holes. At higher temperatures, thermal emission accelerates the recombination process. The Bohr radius of trapped holes, the tail of the exponential approximation of electronic states distribution above the valence band, the density of states at the valence band edge were obtained for TiO2 layers by using the proposed model of trap limited PV. The concept of trap limited PV gives a general tool for the investigation of excess carrier separation in ultrathin metal oxide or semiconductor layers with trap states.

  18. Impact of metallic and metal oxide nanoparticles on wastewater treatment and anaerobic digestion.

    PubMed

    Yang, Yu; Zhang, Chiqian; Hu, Zhiqiang

    2013-01-01

    Metallic and metal oxide nanomaterials have been increasingly used in consumer products (e.g. sunscreen, socks), the medical and electronic industries, and environmental remediation. Many of them ultimately enter wastewater treatment plants (WWTPs) or landfills. This review paper discusses the fate and potential effects of four types of nanoparticles, namely, silver nanoparticles (AgNPs), nano ZnO, nano TiO2, and nano zero valent iron (NZVI), on waste/wastewater treatment and anaerobic digestion. The stabilities and chemical properties of these nanoparticles (NPs) result in significant differences in antimicrobial activities. Analysis of published data of metallic and metal oxide NPs suggests that oxygen is often a prerequisite for the generation of reactive oxygen species (ROS) for AgNPs and NZVI, while illumination is necessary for ROS generation for nano TiO2 and nano ZnO. Furthermore, such nanoparticles are capable of being oxidized or dissolved in water and can release metal ions, leading to metal toxicity. Therefore, AgNPs and nano TiO2 are chemically stable NPs that have no adverse effects on microbes under anaerobic conditions. Although the toxicity of nanomaterials has been studied intensively under aerobic conditions, more research is needed to address their fate in anaerobic waste/wastewater treatment systems and their long-term effects on the environment.

  19. Impurity diffusion in transition-metal oxides

    SciTech Connect

    Peterson, N.L.

    1982-06-01

    Intrinsic tracer impurity diffusion measurements in ceramic oxides have been primarily confined to CoO, NiO, and Fe/sub 3/O/sub 4/. Tracer impurity diffusion in these materials and TiO/sub 2/, together with measurements of the effect of impurities on tracer diffusion (Co in NiO and Cr in CoO), are reviewed and discussed in terms of impurity-defect interactions and mechanisms of diffusion. Divalent impurities in divalent solvents seem to have a weak interaction with vacancies whereas trivalent impurities in divalent solvents strongly influence the vacancy concentrations and significantly reduce solvent jump frequencies near a trivalent impurity. Impurities with small ionic radii diffuse more slowly with a larger activation energy than impurities with larger ionic radii for all systems considered in this review. Cobalt ions (a moderate size impurity) diffuse rapidly along the open channels parallel to the c-axis in TiO/sub 2/ whereas chromium ions (a smaller-sized impurity) do not. 60 references, 11 figures.

  20. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  1. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  2. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  3. 40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reaction products with mixed metal oxides (generic). 721.10574 Section 721.10574 Protection of Environment... reaction products with mixed metal oxides (generic). (a) Chemical substance and significant new uses... reaction products with mixed metal oxides (PMN P-09-48) is subject to reporting under this section for...

  4. 40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... reaction products with mixed metal oxides (generic). 721.10574 Section 721.10574 Protection of Environment... reaction products with mixed metal oxides (generic). (a) Chemical substance and significant new uses... reaction products with mixed metal oxides (PMN P-09-48) is subject to reporting under this section for...

  5. 40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Metal oxide, modified with alkyl and... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10044 Metal oxide, modified with alkyl... to reporting. (1) The chemical substance identified generically as metal oxide, modified with...

  6. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for...

  7. 40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Metal oxide, modified with alkyl and... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10044 Metal oxide, modified with alkyl... to reporting. (1) The chemical substance identified generically as metal oxide, modified with...

  8. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for...

  9. 40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Metal oxide, modified with alkyl and... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10044 Metal oxide, modified with alkyl... to reporting. (1) The chemical substance identified generically as metal oxide, modified with...

  10. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for...

  11. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for...

  12. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  13. 40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for...

  14. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  15. Influence of uranium hydride oxidation on uranium metal behaviour

    SciTech Connect

    Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

    2013-07-01

    This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

  16. Experimental bandstructure of the 5 d transition metal oxide IrO2

    NASA Astrophysics Data System (ADS)

    Kawasaki, Jason; Nie, Yuefeng; Uchida, Masaki; Schlom, Darrell; Shen, Kyle

    2015-03-01

    In the 5 d iridium oxides the close energy scales of spin-orbit coupling and electron-electron correlations lead to emergent quantum phenomena. Much research has focused on the ternary iridium oxides, e.g. the Ruddlesden-Poppers An + 1BnO3 n + 1 , which exhibit behavior from metal to antiferromagnetic insulator ground states, share common features with the cuprates, and may host a number of topological phases. The binary rutile IrO2 is another important 5 d oxide, which has technological importance for spintronics due to its large spin Hall effect and also applications in catalysis. IrO2 is expected to share similar physics as its perovskite-based cousins; however, due to bond-length distortions of the IrO6 octahedra in the rutile structure, the extent of similarities remains an open question. Here we use angle-resolved photoemission spectroscopy to perform momentum-resolved measurements of the electronic structure of IrO2 . IrO2 thin films were grown by molecular beam epitaxy on TiO2 (110) substrates using an Ir e-beam source and distilled ozone. Films were subsequently transferred through ultrahigh vacuum to a connected ARPES system. Combined with first-principles calculations we explore the interplay of spin-orbit coupling and correlations in IrO2 .

  17. Single, binary and multi-component adsorption of some anions and heavy metals on environmentally friendly Carpobrotus edulis plant.

    PubMed

    Chiban, Mohamed; Soudani, Amina; Sinan, Fouad; Persin, Michel

    2011-02-01

    A low-cost adsorbent and environmentally friendly adsorbent from Carpobrotus edulis plant was used for the removal of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions from single, binary and multi-component systems. The efficiency of the adsorbent was studied using batch adsorption technique under different experimental conditions by varying parameters such as pH, initial concentration and contact time. In single component systems, the dried C. edulis has the highest affinity for Pb(2+), followed by NO(3)(-), Cd(2+) and H(2)PO(4)(-), with adsorption capacities of 175mg/g, 125mg/g, 28mg/g and 26mg/g, respectively. These results showed that the adsorption of NO(3)(-) and H(2)PO(4)(-) ions from single and binary component systems can be successfully described by Langmuir and Freundlich isotherms. Freundlich adsorption model, showed the best fit to the single and binary experimental adsorption data. These results also indicated that the adsorption yield of Pb(2+) ion was reduced by the presence of Cd(2+) ion in binary metal mixture. The competitive adsorption of NO(3)(-), H(2)PO(4)(-), Pb(2+) and Cd(2+) ions on dried C. edulis plant shows that NO(3)(-) and H(2)PO(4)(-) anions are able to adsorb on different free binding sites and Pb(2+) and Cd(2+) cations are able to adsorb on the same active sites of C. edulis particles. The dried C. edulis was found to be efficient in removing nitrate, phosphate, cadmium and lead from aqueous solution as compared to other adsorbents already used for the removal of these ions.

  18. Binary Synergy Strengthening and Toughening of Bio-Inspired Nacre-like Graphene Oxide/Sodium Alginate Composite Paper.

    PubMed

    Chen, Ke; Shi, Bin; Yue, Yonghai; Qi, Juanjuan; Guo, Lin

    2015-08-25

    A crucial requirement for most engineering materials is the excellent balance of strength and toughness. By mimicking the hybrid hierarchical structure in nacre, a kind of nacre-like paper based on binary hybrid graphene oxide (GO)/sodium alginate (SA) building blocks has been successfully fabricated. Systematic evaluation for the mechanical property in different (dry/wet) environment/after thermal annealing shows a perfect combination of high strength and toughness. Both of the parameters are nearly many-times higher than those of similar materials because of the synergistic strengthening/toughening enhancement from the binary GO/SA hybrids. The successful fabrication route offers an excellent approach to design advanced strong integrated nacre-like composite materials, which can be applied in tissue engineering, protection, aerospace, and permeable membranes for separation and delivery.

  19. Custom-designed nanomaterial libraries for testing metal oxide toxicity

    PubMed Central

    Pokhrel, Suman; Nel, André E.; Mädler, Lutz

    2014-01-01

    Conspectus Advances in aerosol technology over the past 10 years have provided methods that enable the generation and design of ultrafine nanoscale materials for different applications. The particles are produced combusting a precursor solution and its chemical reaction in the in the gas phase. Flame spray pyrolysis (FSP) is a highly versatile technique for single step and scalable synthesis of nanoscale materials. New innovations in particle synthesis using FSP technology and its precursor chemistry have enabled flexible dry synthesis of loosely-agglomerated highly crystalline ultrafine powders (porosity ≥ 90%) of binary, ternary and mixed binary or ternary oxides. The flame spray pyrolysis lies at the intersection of combustion science, aerosols technology and materials chemistry. The interdisciplinary research is not only inevitable but is becoming increasingly crucial in the design of nanoparticles (NPs) made in the gas phase. The increasing demand especially in the bio-applications for particles with specific material composition, high purity and crystallinity can be often fulfilled with the fast, single step FSP technique. PMID:23194152

  20. Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.

    PubMed

    Abrahamson, John

    2002-01-15

    The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact.

  1. Defects and ferromagnetism in transition metal doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Thapa, Sunil

    Transition metal doped zinc oxide has been studied recently due to its potential application in spintronic devices. The magnetic semiconductor, often called Diluted Magnetic Semiconductors (DMS), has the ability to incorporate both charge and spin into a single formalism. Despite a large number of studies on ferromagnetism in ZnO based DMS and the realization of its room temperature ferromagnetism, there is still a debate about the origin of the ferromagnetism. In this work, the synthesis and characterization of transition metal doped zinc oxide have been carried out. The sol-gel method was used to synthesize thin films, and they were subsequently annealed in air. Characterization of doped zinc oxide films was carried out using the UV-visible range spectrometer, scanning electron microscopy, superconducting quantum interference device (SQUID), x-ray diffraction(XRD) and positron annihilation spectroscopy. Hysteresis loops were obtained for copper and manganese doped zinc oxide, but a reversed hysteresis loop was observed for 2% Al 3% Co doped zinc oxide. The reversed hysteresis loop has been explained using a two-layer model.

  2. Nearly free electrons in a 5d delafossite oxide metal

    PubMed Central

    Kushwaha, Pallavi; Sunko, Veronika; Moll, Philip J. W.; Bawden, Lewis; Riley, Jonathon M.; Nandi, Nabhanila; Rosner, Helge; Schmidt, Marcus P.; Arnold, Frank; Hassinger, Elena; Kim, Timur K.; Hoesch, Moritz; Mackenzie, Andrew P.; King, Phil D. C.

    2015-01-01

    Understanding the role of electron correlations in strong spin-orbit transition-metal oxides is key to the realization of numerous exotic phases including spin-orbit–assisted Mott insulators, correlated topological solids, and prospective new high-temperature superconductors. To date, most attention has been focused on the 5d iridium-based oxides. We instead consider the Pt-based delafossite oxide PtCoO2. Our transport measurements, performed on single-crystal samples etched to well-defined geometries using focused ion beam techniques, yield a room temperature resistivity of only 2.1 microhm·cm (μΩ-cm), establishing PtCoO2 as the most conductive oxide known. From angle-resolved photoemission and density functional theory, we show that the underlying Fermi surface is a single cylinder of nearly hexagonal cross-section, with very weak dispersion along kz. Despite being predominantly composed of d-orbital character, the conduction band is remarkably steep, with an average effective mass of only 1.14me. Moreover, the sharp spectral features observed in photoemission remain well defined with little additional broadening for more than 500 meV below EF, pointing to suppressed electron-electron scattering. Together, our findings establish PtCoO2 as a model nearly-free–electron system in a 5d delafossite transition-metal oxide. PMID:26601308

  3. Reactions of metal ions at surfaces of hydrous iron oxide

    USGS Publications Warehouse

    Hem, J.D.

    1977-01-01

    Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

  4. For cermet inert anode containing oxide and metal phases useful for the electrolytic production of metals

    DOEpatents

    Ray, Siba P.; Liu, Xinghua; Weirauch, Douglas A.

    2002-01-01

    A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe.sub.2 O.sub.3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

  5. A molecular catalyst for water oxidation that binds to metal oxide surfaces

    PubMed Central

    Sheehan, Stafford W.; Thomsen, Julianne M.; Hintermair, Ulrich; Crabtree, Robert H.; Brudvig, Gary W.; Schmuttenmaer, Charles A.

    2015-01-01

    Molecular catalysts are known for their high activity and tunability, but their solubility and limited stability often restrict their use in practical applications. Here we describe how a molecular iridium catalyst for water oxidation directly and robustly binds to oxide surfaces without the need for any external stimulus or additional linking groups. On conductive electrode surfaces, this heterogenized molecular catalyst oxidizes water with low overpotential, high turnover frequency and minimal degradation. Spectroscopic and electrochemical studies show that it does not decompose into iridium oxide, thus preserving its molecular identity, and that it is capable of sustaining high activity towards water oxidation with stability comparable to state-of-the-art bulk metal oxide catalysts. PMID:25757425

  6. Activated Metal Oxide Surfaces as Highly Reactive Environments

    DTIC Science & Technology

    1990-08-03

    underway. " Synthesis of Ultra-High Surface Area Fe203 by Precipitation Methods Yong-Xi Li A series of precipitations of Fe(OH) 3 (from FeCl 3) at...Progress was also made on developing new aerogel procedures for synthesis of ultra-high surface area magnesium oxide. Finally,’ome metal oxide molecules...were studied in chemical reactions and by theoretical methods .-) Three students earned Ph.D. degrees and one an M.S. degree. A visiting professor and

  7. Microelectronic components and metallic oxide studies and applications

    NASA Technical Reports Server (NTRS)

    Williams, L., Jr.

    1976-01-01

    The project involved work in two basic areas: (1) Evaluation of commercial screen printable thick film conductors, resistors, thermistors and dielectrics as well as alumina substrates used in hybird microelectronics industries. Results of tests made on materials produced by seven companies are presented. (2) Experimental studies on metallic oxides of copper and vanadium, in an effort to determine their electrochemical properties in crystalline, powder mixtures and as screen printable thick films constituted the second phase of the research effort. Oxide investigations were aimed at finding possible applications of these materials as switching devices memory elements and sensors.

  8. Metal/oxide interfacial effects on the selective oxidation of primary alcohols

    NASA Astrophysics Data System (ADS)

    Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

    2017-01-01

    A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O-H and C-H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged.

  9. Metal/oxide interfacial effects on the selective oxidation of primary alcohols

    PubMed Central

    Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

    2017-01-01

    A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O–H and C–H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged. PMID:28098146

  10. Effect of metal catalyzed oxidation in recombinant viral protein assemblies

    PubMed Central

    2014-01-01

    Background Protein assemblies, such as virus-like particles, have increasing importance as vaccines, delivery vehicles and nanomaterials. However, their use requires stable assemblies. An important cause of loss of stability in proteins is oxidation, which can occur during their production, purification and storage. Despite its importance, very few studies have investigated the effect of oxidation in protein assemblies and their structural units. In this work, we investigated the role of in vitro oxidation in the assembly and stability of rotavirus VP6, a polymorphic protein. Results The susceptibility to oxidation of VP6 assembled into nanotubes (VP6NT) and unassembled VP6 (VP6U) was determined and compared to bovine serum albumin (BSA) as control. VP6 was more resistant to oxidation than BSA, as determined by measuring protein degradation and carbonyl content. It was found that assembly protected VP6 from in vitro metal-catalyzed oxidation. Oxidation provoked protein aggregation and VP6NT fragmentation, as evidenced by dynamic light scattering and transmission electron microscopy. Oxidative damage of VP6 correlated with a decrease of its center of fluorescence spectral mass. The in vitro assembly efficiency of VP6U into VP6NT decreased as the oxidant concentration increased. Conclusions Oxidation caused carbonylation, quenching, and destruction of aromatic amino acids and aggregation of VP6 in its assembled and unassembled forms. Such modifications affected protein functionality, including its ability to assemble. That assembly protected VP6 from oxidation shows that exposure of susceptible amino acids to the solvent increases their damage, and therefore the protein surface area that is exposed to the solvent is determinant of its susceptibility to oxidation. The inability of oxidized VP6 to assemble into nanotubes highlights the importance of avoiding this modification during the production of proteins that self-assemble. This is the first time that the role of

  11. Fabrication of porous materials (metal, metal oxide and semiconductor) through an aerosol-assisted route

    NASA Astrophysics Data System (ADS)

    Sohn, Hiesang

    Porous materials have gained attraction owing to their vast applications in catalysts, sensors, energy storage devices, bio-devices and other areas. To date, various porous materials were synthesized through soft and hard templating approaches. However, a general synthesis method for porous non-oxide materials, metal alloys and semiconductors with tunable structure, composition and morphology has not been developed yet. To address this challenge, this thesis presents an aerosol method towards the synthesis of such materials and their applications for catalysis, hydrogen storage, Li-batteries and photo-catalysis. The first part of this thesis presents the synthesis of porous metals, metal oxides, and semiconductors with controlled pore structure, crystalline structure and morphology. In these synthesis processes, metal salts and organic ligands were employed as precursors to create porous metal-carbon frameworks. During the aerosol process, primary metal clusters and nanoparticles were formed, which were coagulated/ aggregated forming the porous particles. Various porous particles, such as those of metals (e.g., Ni, Pt, Co, Fe, and Ni xPt(1-x)), metal oxides (e.g., Fe3O4 and SnO2) and semiconductors (e.g., CdS, CuInS2, CuInS 2x-ZnS(1-x), and CuInS2x-TiO2(1-x)) were synthesized. The morphology, porous structure and crystalline structure of the particles were regulated through both templating and non-templating methods. The second part of this thesis explores the applications of these materials, including propylene hydrogenation and H2 uptake capacity of porous Ni, NiPt alloys and Ni-Pt composites, Li-storage of Fe3O4 and SnO2, photodegradation of CuInS2-based semiconductors. The effects of morphology, compositions, and porous structure on the device performance were systematically investigated. Overall, this dissertation work unveiled a simple synthesis approach for porous particles of metals, metal alloys, metal oxides, and semiconductors with controlled

  12. Synthesis of metal-metal oxide catalysts and electrocatalysts using a metal cation adsorption/reduction and adatom replacement by more noble ones

    DOEpatents

    Adzic, Radoslav; Vukmirovic, Miomir; Sasaki, Kotaro

    2010-04-27

    The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen. The invention also relates to methods of making the metal-metal oxide composites.

  13. Thin water film formation on metal oxide crystal surfaces.

    PubMed

    Gilbert, Benjamin; Katz, Jordan E; Rude, Bruce; Glover, T E; Hertlein, Marcus P; Kurz, Charles; Zhang, Xiaoyi

    2012-10-09

    Reactions taking place at hydrated metal oxide surfaces are of considerable environmental and technological importance. Surface-sensitive X-ray methods can provide structural and chemical information on stable interfacial species, but it is challenging to perform in situ studies of reaction kinetics in the presence of water. We have implemented a new approach to creating a micrometer-scale water film on a metal oxide surface by combining liquid and gas jets on a spinning crystal. The water films are stable indefinitely and sufficiently thin to allow grazing incidence X-ray reflectivity and spectroscopy measurements. The approach will enable studies of a wide range of surface reactions and is compatible with interfacial optical-pump/X-ray-probe studies.

  14. Noble Metal-Iron Oxide Hybrid Nanomaterials: Emerging Applications.

    PubMed

    Leung, Ken Cham-Fai; Xuan, Shouhu

    2016-02-01

    This account provides an overview of current research activities that focus on the synthesis and applications of nanomaterials from noble metal (e.g., Au, Ag, Pd) and iron oxide (Fe3O4) hybrids. An introduction to the synthetic strategies that have been developed for generating M-Fe3O4 nanomaterials with different novel structures is presented. Surface functionalization and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. The utilization of the advantageous properties of both noble metals and iron oxide for a variety of applications, such as theranostics, gene delivery, biosensing, cell sorting, bioseparation, and catalysis, is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. The fundamental requirements underpinning the effective preparation of M-Fex Oy hybrid nanomaterials shed light on the future development of heterogeneous catalysts, nanotheranostics, nanomedicines, and other chemical technologies.

  15. Taurine inhibition of metal-stimulated catecholamine oxidation.

    PubMed

    Dawson, R; Baker, D; Eppler, B; Tang, E; Shih, D; Hern, H; Hu, M

    2000-01-01

    Taurine is an abundant amino acid found in mammalian tissues and it has been suggested to have cytoprotective functions. The aim of the present study was to determine if taurine had the potential to reduce oxidative stress associated with metal-stimulated catecholamine oxidation. Taurine and structural analogs of taurine were tested for their ability to inhibit metal-stimulated quinone formation from dopamine or L-dopa. Oxidative damage to proteins and lipids were also assessed in vitro and the effects of taurine were determined. Taurine (20 mM) was found to decrease significantly ferric iron (50-500 microM)- and manganese (10 microM)-stimulated L-dopa or dopamine oxidation. Taurine had no effect on zinc-induced dopamine oxidation and slightly potentiated copper- and NaIO(4)-stimulated quinone formation. Ferric iron-stimulated lipid peroxidation was not affected by taurine (1-20 mM). Protein carbonyl formation induced by ferric iron (500 microM) and L-dopa (500 microM) was significantly reduced by 10 mM taurine. The cytotoxicity of L-dopa (250 microM) and ferric chloride (75 microM) to LLC-PK(1) cells was attenuated by 10 mM taurine or hypotaurine. Homotaurine alone stimulated L-dopa oxidation and potentiated the cytotoxic effects of ferric iron. Homotaurine was found to be cytotoxic when combined with L-dopa or L-dopa/iron. In contrast, hypotaurine inhibited quinone formation and protected LLC-PK(1) cells. These studies suggest that taurine may exhibit cytoprotective effects against the oxidation products of catecholamines by acting as a scavenger for free radicals and cytotoxic quinones.

  16. Time- and energy-efficient solution combustion synthesis of binary metal tungstate nanoparticles with enhanced photocatalytic activity.

    PubMed

    Thomas, Abegayl; Janáky, Csaba; Samu, Gergely F; Huda, Muhammad N; Sarker, Pranab; Liu, J Ping; van Nguyen, Vuong; Wang, Evelyn H; Schug, Kevin A; Rajeshwar, Krishnan

    2015-05-22

    In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the most significant effects are highlighted. Each sample's photocatalytic activity towards methyl orange degradation was studied and benchmarked against their respective commercial oxide sample obtained by solid-state ceramic synthesis. Based on the results herein, we conclude that SCS is a time- and energy-efficient method to synthesize crystalline binary tungstate nanomaterials even without additional excessive heat treatment. As many of these photocatalysts possess excellent photocatalytic activity, the discussed synthetic strategy may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation.

  17. Metal oxide-encapsulated dye-sensitized photoanodes for dye-sensitized solar cells

    SciTech Connect

    Hupp, Joseph T.; Son, Ho-Jin

    2016-01-12

    Dye-sensitized semiconducting metal oxide films for photoanodes, photoanodes incorporating the films and DSCs incorporating the photoanodes are provided. Also provided are methods for making the dye sensitized semiconducting metal oxide films. The methods of making the films are based on the deposition of an encapsulating layer of a semiconducting metal oxide around the molecular anchoring groups of photosensitizing dye molecules adsorbed to a porous film of the semiconducting metal oxide. The encapsulating layer of semiconducting metal oxide is formed in such a way that it is not coated over the chromophores of the adsorbed dye molecules and, therefore, allows the dye molecules to remain electrochemically addressable.

  18. Performance of metal and oxide fuel cores during accidents in large liquid-metal-cooled reactors

    SciTech Connect

    Royl, P.H.; Kussmaul, G. ); Cahalan, J.E.; Wigeland, R.A. ); Friedel, G. ); Moreau, J. ); Perks, M. )

    1992-02-01

    This paper reports on a cooperative effort among European and U.S. analysts, which is an assessment of the comparative safety performance of metal and oxide fuels during accidents in a 3500-MW (thermal), pool-type, liquid-metal-cooled reactor (LMR) is performed. The study focuses on three accident initiators with failure to scram: the unprotected loss-of-flow (ULOF), the unprotected transient overpower, and the unprotected loss-of-heat-sink (ULOHS). Core designs with a similar power output that have been previously analyzed in Europe under ULOF accident conditions are also included in this comparison. Emphasis is placed on identification of design features that provide passive, self-limiting responses to postulated accident conditions and quantification of relative safety margins. The analyses show that in ULOF and ULOHS sequences, metal-fueled LMRs with pool-type primary systems provide larger temperature margins to coolant boiling than do oxide-fueled reactors of the same design.

  19. Performance of metal and oxide fuels during accidents in a large liquid metal cooled reactor

    SciTech Connect

    Cahalan, J.; Wigeland, R. ); Friedel, G. , Bergisch Gladbach ); Kussmaul, G.; Royl, P. ); Moreau, J. ); Perks, M.

    1990-01-01

    In a cooperative effort among European and US analysts, an assessment of the comparative safety performance of metal and oxide fuels during accidents in a large (3500 MWt), pool-type, liquid-metal-cooled reactor (LMR) was performed. The study focused on three accident initiators with failure to scram: the unprotected loss-of-flow (ULOF), the unprotected transient overpower (UTOP), and the unprotected loss-of-heat-sink (ULOHS). Emphasis was placed on identification of design features that provide passive, self-limiting responses to upset conditions, and quantification of relative safety margins. The analyses show that in ULOF and ULOHS sequences, metal-fueled LMRs with pool-type primary systems provide larger temperature margins to coolant boiling than oxide-fueled reactors of the same design. 3 refs., 4 figs.

  20. Recent Developments of Metal and Metal Oxide Nanocatalysts in Organic Synthesis.

    PubMed

    Makawana, Jigar A; Sangani, Chetan B; Yao, Yong-Fang; Duan, Yong-Tao; Lv, Peng-Cheng; Zhu, Hai-Liang

    2016-01-01

    Recently, various nanomaterials have been used in many organic transformations as efficient catalysts. The development of new catalysts by nanoscale design has emerged as a fertile field for research and innovation. The ability of nanotechnology to enhance catalytic activity opens the potential to replace expensive catalysts with lower amounts of inexpensive nanocatalysts. Besides, development of efficient and environmentally friendly synthetic methodologies for the synthesis of compound libraries of medicinal scaffolds is an attractive area of research in both academic and pharmaceutical industry. According to above reports and needs, this review deals with applications of nanoparticles as catalysts in various organic syntheses. We detail the topic of organic transformations using nanoparticles: Metal Nanoparticles and Metal Oxide Nanoparticles. In the latter part, different Metal Oxide Nanoparticles, such as ZnO Nanoparticle, TiO2 Nanoparticle, and CuO Nanoparticle are discussed.

  1. Metal inhibition on the reactivity of manganese dioxide toward organic contaminant oxidation in relation to metal adsorption and ionic potential.

    PubMed

    Jiang, Jing; Wang, Zhuopu; Chen, Yang; He, Anfei; Li, Jianliang; Sheng, G Daniel

    2017-03-01

    Coexisting metal ions may significantly inhibit the oxidative reactivity of manganese oxides toward organic contaminants in metal-organic multi-pollutant waters. While the metal inhibition on the oxidation of organic contaminants by manganese oxides has previously been reported, the extent of the inhibition in relation to metal properties has not been established. Six alkali, alkaline, and transition metals, as well as two testing metals were evaluated for their abilities to inhibit the reactivity of birnessite. Regardless of the pathways of phenol and diuron oxidation (polymerization vs. breakdown), the extent of metal inhibition depended mainly on the metal itself and its concentration. The observed metal inhibition efficiency followed the order of Mn(2+) > Co(2+) > Cu(2+) > Al(3+) > Mg(2+) > K(+), consistent with metal adsorption on birnessite. The first-order organic oxidation rate constant (kobs) was linearly negatively correlated with metal adsorption (qe) on birnessite. These observations demonstrated that the metal inhibition efficiency was determined by metal adsorption on birnessite. The slopes of the kobs-qe varied among metals and followed the order of K(+) > Ca(2+) > Mg(2+) > Mn(2+) > Cd(2+) > Co(2+) > Cu(2+) > Al(3+). These slopes defined intrinsic inhibitory abilities of metals. As metals were adsorbed hydrated on birnessite, the intrinsic inhibitory ability was significantly linearly correlated with ionic potentials of metals, leading to a single straight line. Metals with multiple d electrons in the outermost orbit with polarizing energy that promotes hydrolysis sat slightly below the line, and vice versa.

  2. Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring

    PubMed Central

    Fine, George F.; Cavanagh, Leon M.; Afonja, Ayo; Binions, Russell

    2010-01-01

    Metal oxide semiconductor gas sensors are utilised in a variety of different roles and industries. They are relatively inexpensive compared to other sensing technologies, robust, lightweight, long lasting and benefit from high material sensitivity and quick response times. They have been used extensively to measure and monitor trace amounts of environmentally important gases such as carbon monoxide and nitrogen dioxide. In this review the nature of the gas response and how it is fundamentally linked to surface structure is explored. Synthetic routes to metal oxide semiconductor gas sensors are also discussed and related to their affect on surface structure. An overview of important contributions and recent advances are discussed for the use of metal oxide semiconductor sensors for the detection of a variety of gases—CO, NOx, NH3 and the particularly challenging case of CO2. Finally a description of recent advances in work completed at University College London is presented including the use of selective zeolites layers, new perovskite type materials and an innovative chemical vapour deposition approach to film deposition. PMID:22219672

  3. Optical properties of transition metal oxide quantum wells

    SciTech Connect

    Lin, Chungwei; Posadas, Agham; Choi, Miri; Demkov, Alexander A.

    2015-01-21

    Fabrication of a quantum well, a structure that confines the electron motion along one or more spatial directions, is a powerful method of controlling the electronic structure and corresponding optical response of a material. For example, semiconductor quantum wells are used to enhance optical properties of laser diodes. The ability to control the growth of transition metal oxide films to atomic precision opens an exciting opportunity of engineering quantum wells in these materials. The wide range of transition metal oxide band gaps offers unprecedented control of confinement while the strong correlation of d-electrons allows for various cooperative phenomena to come into play. Here, we combine density functional theory and tight-binding model Hamiltonian analysis to provide a simple physical picture of transition metal oxide quantum well states using a SrO/SrTiO{sub 3}/SrO heterostructure as an example. The optical properties of the well are investigated by computing the frequency-dependent dielectric functions. The effect of an external electric field, which is essential for electro-optical devices, is also considered.

  4. Optical properties of transition metal oxide quantum wells

    NASA Astrophysics Data System (ADS)

    Lin, Chungwei; Posadas, Agham; Choi, Miri; Demkov, Alexander A.

    2015-01-01

    Fabrication of a quantum well, a structure that confines the electron motion along one or more spatial directions, is a powerful method of controlling the electronic structure and corresponding optical response of a material. For example, semiconductor quantum wells are used to enhance optical properties of laser diodes. The ability to control the growth of transition metal oxide films to atomic precision opens an exciting opportunity of engineering quantum wells in these materials. The wide range of transition metal oxide band gaps offers unprecedented control of confinement while the strong correlation of d-electrons allows for various cooperative phenomena to come into play. Here, we combine density functional theory and tight-binding model Hamiltonian analysis to provide a simple physical picture of transition metal oxide quantum well states using a SrO/SrTiO3/SrO heterostructure as an example. The optical properties of the well are investigated by computing the frequency-dependent dielectric functions. The effect of an external electric field, which is essential for electro-optical devices, is also considered.

  5. [Oxidative stress in plants exposed to heavy metals].

    PubMed

    Rucińiska-Sobkowiak, Renata

    2010-01-01

    Oxidative stress has been involved in the toxicity of heavy metals in different plant species. Exposure to metal ions can intensify the production of reactive oxygen species (ROS) such as: superoxide radicals, hydroxyl radicals or hydrogen peroxide. These species can react with cellular components (lipids, proteins, nucleic acids) and cause lipid peroxidation, membrane damage and inactivation of enzymes thus affect many physiological processes as well as cell viability. Plants have evolved a complex array of mechanisms to maintain low ROS level and avoid the detrimental effects of excessively high ROS concentrations. This antioxidant network includes numerous soluble (ascorbate, glutathione) and membrane (tocopherol) compounds as well as enzymes involved in ROS scavenging (superoxide dismutase, catalase, ascorbate peroxidase). ROS must be efficiently detoxified to ameliorate the harmful effects of heavy metals in the cells. However they cannot be eliminated completely because plants use ROS as second messengers in signal transduction cascades in diverse physiological processes.

  6. Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

    SciTech Connect

    Krogel, Jaron T.; Santana Palacio, Juan A.; Reboredo, Fernando A.

    2016-02-22

    Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high-quality pseudopotentials that are both accurate in QMC and compatible with major plane-wave electronic structure codes. We have generated a set of neon-core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentials to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudopotentials. Our QMC pseudopotential results compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.

  7. Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

    DOE PAGES

    Krogel, Jaron T.; Santana Palacio, Juan A.; Reboredo, Fernando A.

    2016-02-22

    Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high-quality pseudopotentials that are both accurate in QMC and compatible with major plane-wave electronic structure codes. We have generated a set of neon-core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentialsmore » to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudopotentials. Our QMC pseudopotential results compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.« less

  8. Uranium Metal to Oxide Conversion by Air Oxidation –Process Development

    SciTech Connect

    Duncan, A

    2001-12-31

    Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

  9. Reusable oxidation catalysis using metal-monocatecholato species in a robust metal-organic framework.

    PubMed

    Fei, Honghan; Shin, JaeWook; Meng, Ying Shirley; Adelhardt, Mario; Sutter, Jörg; Meyer, Karsten; Cohen, Seth M

    2014-04-02

    An isolated metal-monocatecholato moiety has been achieved in a highly robust metal-organic framework (MOF) by two fundamentally different postsynthetic strategies: postsynthetic deprotection (PSD) and postsynthetic exchange (PSE). Compared with PSD, PSE proved to be a more facile and efficient functionalization approach to access MOFs that could not be directly synthesized under solvothermal conditions. Metalation of the catechol functionality residing in the MOFs resulted in unprecedented Fe-monocatecholato and Cr-monocatecholato species, which were characterized by X-ray absorption spectroscopy, X-band electron paramagnetic resonance spectroscopy, and (57)Fe Mössbauer spectroscopy. The resulting materials are among the first examples of Zr(IV)-based UiO MOFs (UiO = University of Oslo) with coordinatively unsaturated active metal centers. Importantly, the Cr-metalated MOFs are active and efficient catalysts for the oxidation of alcohols to ketones using a wide range of substrates. Catalysis could be achieved with very low metal loadings (0.5-1 mol %). Unlike zeolite-supported, Cr-exchange oxidation catalysts, the MOF-based catalysts reported here are completely recyclable and reusable, which may make them attractive catalysts for 'green' chemistry processes.

  10. Adsorptive removal of Cu(II) and Ni(II) from single-metal, binary-metal, and industrial wastewater systems by surfactant-modified alumina.

    PubMed

    Khobragade, Moni U; Pal, Anjali

    2015-01-01

    Batch adsorption was carried out to investigate the possibility of utilizing surfactant-modified alumina (SMA) as an adsorbent for the removal of Cu(II) and Ni(II) from single-metal and binary-metal solutions. Scanning electron microscopic (SEM) images of SMA before and after metal removal from single-metal matrix, showed no significant changes, whereas energy dispersive X-ray (EDX) studies confirmed the incorporation of Cu(II) (∼ 0.74 atomic%) and Ni(II) (∼ 0.64 atomic%) on the adsorbent surface. The removal of Cu(II) and Ni(II), using SMA depends on contact time, adsorbent dose and medium pH. The sorption kinetics followed pseudo-second-order model for Cu(II). However, for Ni(II), either pseudo-first-order or pseudo-second-order model is applicable. The batch experimental data were fitted to Langmuir and Freundlich isotherm, and based on the correlation coefficient value (R(2)), the adsorption could be described more precisely by the Freundlich isotherm. The maximum adsorption capacity from Langmuir isotherm of Cu(II) was 9.34 mg g(-1) and for Ni(II) 6.87 mg g(-1). In a synthetic binary mixture of Cu(II) and Ni(II), having a concentration of 10 mg L(-1) each, removal of Cu(II) was better. The treatment method was further applied to real wastewater from an electroplating industry. The batch experiment results showed that SMA was effective in the simultaneous removal of Cu(II) and Ni(II) to a significant extent, with additional improvement of water quality of the industrial effluent considered.

  11. Hydrocracking and hydroisomerization of long-chain alkanes and polyolefins over metal-promoted anion-modified transition metal oxides

    SciTech Connect

    Venkatesh, Koppampatti R.; Hu, Jianli; Tierney, John W.; Wender, Irving

    1996-12-01

    A method is described for cracking a feedstock by contacting the feedstock with a metal-promoted anion-modified metal oxide catalyst in the presence of hydrogen gas. The metal oxide of the catalyst is one or more of ZrO{sub 2}, HfO{sub 2}, TiO{sub 2} and SnO{sub 2}, and the feedstock is principally chains of at least 20 carbon atoms. The metal-promoted anion-modified metal oxide catalyst contains one or more of Pt, Ni, Pd, Rh, Ir, Ru, (Mn and Fe) or mixtures of them present between about 0.2% to about 15% by weight of the catalyst. The metal-promoted anion-modified metal oxide catalyst contains one or more of SO{sub 4}, WO{sub 3}, or mixtures of them present between about 0.5% to about 20% by weight of the catalyst.

  12. Hydrocracking and hydroisomerization of long-chain alkanes and polyolefins over metal-promoted anion-modified transition metal oxides

    DOEpatents

    Venkatesh, Koppampatti R.; Hu, Jianli; Tierney, John W.; Wender, Irving

    2001-01-01

    A method of cracking a feedstock by contacting the feedstock with a metal-promoted anion-modified metal oxide catalyst in the presence of hydrogen gas. The metal oxide of the catalyst is one or more of ZrO.sub.2, HfO.sub.2, TiO.sub.2 and SnO.sub.2, and the feedstock is principally chains of at least 20 carbon atoms. The metal-promoted anion-modified metal oxide catalyst contains one or more of Pt, Ni, Pd, Rh, Ir, Ru, (Mn & Fe) or mixtures of them present between about 0.2% to about 15% by weight of the catalyst. The metal-promoted anion-modified metal oxide catalyst contains one or more of SO.sub.4, WO.sub.3, or mixtures of them present between about 0.5% to about 20% by weight of the catalyst.

  13. Orbital reconstruction in nonpolar tetravalent transition-metal oxide layers

    NASA Astrophysics Data System (ADS)

    Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Romhányi, Judit; Yushankhai, Viktor; Kataev, Vladislav; Büchner, Bernd; van den Brink, Jeroen; Hozoi, Liviu

    2015-06-01

    A promising route to tailoring the electronic properties of quantum materials and devices rests on the idea of orbital engineering in multilayered oxide heterostructures. Here we show that the interplay of interlayer charge imbalance and ligand distortions provides a knob for tuning the sequence of electronic levels even in intrinsically stacked oxides. We resolve in this regard the d-level structure of layered Sr2IrO4 by electron spin resonance. While canonical ligand-field theory predicts g||-factors less than 2 for positive tetragonal distortions as present in Sr2IrO4, the experiment indicates g|| is greater than 2. This implies that the iridium d levels are inverted with respect to their normal ordering. State-of-the-art electronic-structure calculations confirm the level switching in Sr2IrO4, whereas we find them in Ba2IrO4 to be instead normally ordered. Given the nonpolar character of the metal-oxygen layers, our findings highlight the tetravalent transition-metal 214 oxides as ideal platforms to explore d-orbital reconstruction in the context of oxide electronics.

  14. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    NASA Astrophysics Data System (ADS)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  15. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  16. A versatile sol-gel synthesis route to metal-silicon mixed oxide nanocomposites that contain metal oxides as the major phase

    SciTech Connect

    Clapsaddle, B J; Sprehn, D W; Gash, A E; Satcher, J H; Simpson, R L

    2003-12-08

    The general synthesis of metal-silicon mixed oxide nanocomposite materials, including a variety of both main group and transition metals, in which the metal oxide is the major component is described. In a typical synthesis, the metal oxide precursor, MCl{sub x}{times}{sub y}H{sub 2}O (x=3-6, y=0-7), was mixed with the silica precursor, tetramethylorthosilicate (TMOS), in ethanol and gelled using an organic epoxide. The successful preparation of homogeneous, monolithic materials depended on the oxidation state of the metal as well as the epoxide chosen for gelation. The composition of the resulting materials was varied from M/Si=1-5 (mol/mol) by adjusting the amount of TMOS added to the initial metal oxide precursor solution. Supercritical processing of the gels in CO{sub 2} resulted in monolithic, porous aerogel nanocomposite materials with surface areas ranging from 100 - 800 m{sup 2}/g. The bulk materials are composed of metal oxide/silica particles that vary in size from 5 - 20 nm depending on the epoxide used for gelation. Metal oxide and silica dispersion throughout the bulk material is extremely uniform on the nanoscale. The versatility and control of the synthesis method will be discussed as well as the properties of the resulting metal-silicon mixed oxide nanocomposite materials.

  17. Lithium metal oxide electrodes for lithium cells and batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil

    2008-12-23

    A lithium metal oxide positive electrode for a non-aqueous lithium cell is disclosed. The cell is prepared in its initial discharged state and has a general formula xLiMO.sub.2.(1-x)Li.sub.2M'O.sub.3 in which 0oxidation state and with at least one ion being Mn or Ni, and where M' is one or more ion with an average tetravalent oxidation state. Complete cells or batteries are disclosed with anode, cathode and electrolyte as are batteries of several cells connected in parallel or series or both.

  18. Dual-environment effects on the oxidation of metallic interconnects

    SciTech Connect

    Holcomb, G.R.; Ziomek-Moroz, M.; Covino, B.S., Jr.; Bullard, S.J.

    2006-08-01

    Metallic interconnects in solid oxide fuel cells are exposed to a dual environment: fuel on one side (i.e., H2 gas) and oxidizer on the other side (i.e., air). It has been observed that the oxidation behavior of thin stainless steel sheet in air is changed by the presence of H2 on the other side of the sheet. The resulting dual-environment scales are flaky and more friable than the single-environment scales. The H2 disrupts the scale on the air side. A model to explain some of the effects of a dual environment is presented where hydrogen diffusing through the stainless steel sheet reacts with oxygen diffusing through the scale to form water vapor, which has sufficient vapor pressure to mechanically disrupt the scale. Experiments on preoxidized 316L stainless steel tubing exposed to air-air, H2-air, and H2-Ar environments are reported in support of the model.

  19. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, J.E.; Kelly, T.F.

    1999-06-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains. 20 figs.

  20. Thermodynamic properties of some metal oxide-zirconia systems

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    1989-01-01

    Metal oxide-zirconia systems are a potential class of materials for use as structural materials at temperatures above 1900 K. These materials must have no destructive phase changes and low vapor pressures. Both alkaline earth oxide (MgO, CaO, SrO, and BaO)-zirconia and some rare earth oxide (Y2O3, Sc2O3, La2O3, CeO2, Sm2O3, Gd2O3, Yb2O3, Dy2O3, Ho2O3, and Er2O3)-zirconia system are examined. For each system, the phase diagram is discussed and the vapor pressure for each vapor species is calculated via a free energy minimization procedure. The available thermodynamic literature on each system is also surveyed. Some of the systems look promising for high temperature structural materials.

  1. The Development of Metal Oxide Chemical Sensing Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, G. W.; VanderWal,R. L.; Xu, J. C.; Evans, L. J.; Berger, G. M.; Kulis, M. J.

    2008-01-01

    This paper discusses sensor development based on metal oxide nanostructures and microsystems technology. While nanostructures such as nanowires show significant potential as enabling materials for chemical sensors, a number of significant technical challenges remain. This paper discusses development to address each of these technical barriers: 1) Improved contact and integration of the nanostructured materials with microsystems in a sensor structure; 2) Control of nanostructure crystallinity to allow control of the detection mechanism; and 3) Widening the range of gases that can be detected by fabricating multiple nanostructured materials. A sensor structure composed of three nanostructured oxides aligned on a single microsensor has been fabricated and tested. Results of this testing are discussed and future development approaches are suggested. It is concluded that while this work lays the foundation for further development, these are the beginning steps towards realization of repeatable, controlled sensor systems using oxide based nanostructures.

  2. High-Temperature Oxidation of Plutonium Surrogate Metals and Alloys

    SciTech Connect

    Sparks, Joshua C.; Krantz, Kelsie E.; Christian, Jonathan H.; Washington, II, Aaron L.

    2016-07-27

    The Plutonium Management and Disposition Agreement (PMDA) is a nuclear non-proliferation agreement designed to remove 34 tons of weapons-grade plutonium from Russia and the United States. While several removal options have been proposed since the agreement was first signed in 2000, processing the weapons-grade plutonium to mixed-oxide (MOX) fuel has remained the leading candidate for achieving the goals of the PMDA. However, the MOX program has received its share of criticisms, which causes its future to be uncertain. One alternative pathway for plutonium disposition would involve oxidizing the metal followed by impurity down blending and burial in the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. This pathway was investigated by use of a hybrid microwave and a muffle furnace with Fe and Al as surrogate materials. Oxidation occurred similarly in the microwave and muffle furnace; however, the microwave process time was significantly faster.

  3. Lithium Metal Oxide Electrodes For Lithium Cells And Batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil; Kim, Jaekook

    2004-01-20

    A lithium metal oxide positive electrode for a non-aqueous lithium cell is disclosed. The cell is prepared in its initial discharged state and has a general formula xLiMO.sub.2.(1-x)Li.sub.2 M'O.sub.3 in which 0oxidation state and with at least one ion being Mn or Ni, and where M' is one or more ion with an average tetravalent oxidation state. Complete cells or batteries are disclosed with anode, cathode and electrolyte as are batteries of several cells connected in parallel or series or both.

  4. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, John E.; Kelly, Thomas F.

    1999-01-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

  5. Two-Dimensional Polaronic Behavior in the Binary Oxides m-HfO2 and m-ZrO2

    SciTech Connect

    Mckenna, Keith P.; Wolf, Matthew J.; Shluger, Alexander L.; Lany, Stephan; Zunger, Alex

    2012-03-14

    We demonstrate that the three-dimensional (3D) binary monoclinic oxides HfO2 and ZrO2 exhibit quasi-2D polaron localization and conductivity, which results from a small difference in the coordination of two oxygen sublattices in these materials. The transition between a 2D large polaron into a zerodimensional small polaron state requires overcoming a small energetic barrier. These results demonstrate how a small asymmetry in the lattice structure can determine the qualitative character of polaron localization and significantly broaden the realm of quasi-2D polaron systems.

  6. CATALYTIC OXIDATION OF DIMETHYL SULFIDE WITH OZONE: EFFECTS OF PROMOTER AND PHYSICO-CHEMICAL PROPERTIES OF METAL OXIDE CATALYSTS

    EPA Science Inventory

    This study reports improved catalytic activities and stabilities for the oxidation of dimethyl sulfide (DMS), a major pollutant of pulp and paper mills. Ozone was used as an oxidant and activities of Cu, Mo, Cr and Mn oxides, and mixed metal oxides supported on -alumina, were tes...

  7. Unveiling the complex electronic structure of amorphous metal oxides

    PubMed Central

    Århammar, C.; Pietzsch, Annette; Bock, Nicolas; Holmström, Erik; Araujo, C. Moyses; Gråsjö, Johan; Zhao, Shuxi; Green, Sara; Peery, T.; Hennies, Franz; Amerioun, Shahrad; Föhlisch, Alexander; Schlappa, Justine; Schmitt, Thorsten; Strocov, Vladimir N.; Niklasson, Gunnar A.; Wallace, Duane C.; Rubensson, Jan-Erik; Johansson, Börje; Ahuja, Rajeev

    2011-01-01

    Amorphous materials represent a large and important emerging area of material’s science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today’s integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5–10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.

  8. Probing M subdwarf metallicity with an esdK5+esdM5.5 binary

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.; Zhang, Z. H.; Gálvez-Ortiz, M. C.; Kushniruk, I. O.; Jones, H. R. A.

    2015-10-01

    Context. We present a spectral analysis of the binary G 224-58 AB, which consists of the coolest M extreme subdwarf (esdM5.5) and a brighter primary (esdK5). This binary may serve as a benchmark for metallicity measurement calibrations and as a test bed for atmospheric and evolutionary models for esdM objects. Aims: We perform the analysis of optical and infrared spectra of both components to determine their parameters. Methods: We determine abundances primarily using high-resolution optical spectra of the primary. Other parameters were determined from the fits of synthetic spectra computed with these abundances to the observed spectra from 0.4 to 2.5 microns for both components. Results: We determine Teff = 4625 ± 100 K, log g = 4.5 ± 0.5 for the A component and Teff = 3200 ± 100 K, log g = 5.0 ± 0.5, for the B component. We obtained abundances of [ Mg / H ] = + - 1.51 ± 0.08, [Ca/H] = - 1.39 ± 0.03, [Ti/H] = - 1.37 ± 0.03 for alpha group elements and [CrH] = - 1.88 ± 0.07, [Mn/H] = - 1.96 ± 0.06, [ Fe / H ] = - 1.92 ± 0.02, [Ni/H] = - 1.81 ± 0.05 and [Ba/H] = - 1.87 ± 0.11 for iron group elements from fits to the spectral lines observed in the optical and infrared spectral regions of the primary. We find consistent abundances with fits to the secondary albeit at lower signal to noise. Conclusions: Abundances of different elements in G 224-58 A and G 224-58 B atmospheres cannot be described by one metallicity parameter. The offset of ˜0.4 dex between the abundances derived from alpha element and iron group elements corresponds with our expectation for metal-deficient stars. We thus clarify that some indices used to date to measure metallicities for establishing esdM stars, based on CaH, MgH, and TiO band system strength ratios in the optical and H2O in the infrared, relate to abundances of alpha-element group rather than to iron peak elements. For metal deficient M dwarfs with [ Fe / H ] < - 1.0, this provides a ready explanation for apparently

  9. Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates.

    PubMed

    Zhang, Miao; Frei, Heinz

    2017-02-22

    Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis. Expected final online publication date for the Annual Review of Physical Chemistry Volume 68 is April 20, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  10. Metal/metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems

    DOEpatents

    Park, Paul W.

    2004-03-16

    A lean NOx catalyst and method of preparing the same is disclosed. The lean NOx catalyst includes a ceramic substrate, an oxide support material, preferably .gamma.-alumina, deposited on the substrate and a metal promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium, cerium, vanadium, oxides thereof, and combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between about 80 to 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.

  11. Generation and behavior of metal oxide colloids in PWR steam systems

    SciTech Connect

    Varsanik, R.G.

    1984-10-01

    This work reviews the curently available literature and research work on the generation and behavior of metal oxide colloids in PWR steam systems. The work of E. Matijevic et al on the generation and adhesion of iron and copper oxides is described. The role of colloid chemistry in the control of plant sludge and corrosion products is described. Factors affecting the adherence and re-entrainment of colloidal metal oxides along with possible methods for the control of metal oxide deposition are reviewed.

  12. A metallic interconnect for a solid oxide fuel cell stack

    NASA Astrophysics Data System (ADS)

    England, Diane Mildred

    A solid oxide fuel cell (SOFC) electrochemically converts the chemical energy of reaction into electrical energy. The commercial success of planar, SOFC stack technology has a number of challenges, one of which is the interconnect that electrically and physically connects the cathode of one cell to the anode of an adjacent cell in the SOFC stack and in addition, separates the anodic and cathodic gases. An SOFC stack operating at intermediate temperatures, between 600°C and 800°C, can utilize a metallic alloy as an interconnect material. Since the interconnect of an SOFC stack must operate in both air and fuel environments, the oxidation kinetics, adherence and electronic resistance of the oxide scales formed on commercial alloys were investigated in air and wet hydrogen under thermal cycling conditions to 800°C. The alloy, Haynes 230, exhibited the slowest oxidation kinetics and the lowest area-specific resistance as a function of oxidation time of all the alloys in air at 800°C. However, the area-specific resistance of the oxide scale formed on Haynes 230 in wet hydrogen was unacceptably high after only 500 hours of oxidation, which was attributed to the high resistivity of Cr2O3 in a reducing atmosphere. A study of the electrical conductivity of the minor phase manganese chromite, MnXCr3-XO4, in the oxide scale of Haynes 230, revealed that a composition closer to Mn2CrO4 had significantly higher electrical conductivity than that closer to MnCr 2O4. Haynes 230 was coated with Mn to form a phase closer to the Mn2CrO4 composition for application on the fuel side of the interconnect. U.S. Patent No. 6,054,231 is pending. Although coating a metallic alloy is inexpensive, the stringent economic requirements of SOFC stack technology required an alloy without coating for production applications. As no commercially available alloy, among the 41 alloys investigated, performed to the specifications required, a new alloy was created and designated DME-A2. The oxide scale

  13. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    PubMed

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

  14. Transtion metal oxides for solar water splitting devices

    NASA Astrophysics Data System (ADS)

    Smith, Adam M.

    Although the terrestrial flux of solar energy is enough to support human endeavors, storage of solar energy remains a significant challenge to large-scale implementation of solar energy production. One route to energy storage involves the capture and conversion of sunlight to chemical species such as molecular hydrogen and oxygen via water splitting devices. The oxygen evolution half-reaction particularly suffers from large kinetic overpotentials. Additionally, a photoactive material that exhibits stability in oxidizing conditions present during oxygen evolution represents a unique challenge for devices. These concerns can be potentially addressed with a metal oxide photoanode coupled with efficient water oxidation electrocatalysts. Despite decades of research, structure-composition to property relationships are still needed for the design of metal oxide oxygen evolution materials. This dissertation investigates transition metal oxide materials for the oxygen evolution portion of water splitting devices. Chapter I introduces key challenges for solar driven water splitting. Chapter II elucidates the growth mechanism of tungsten oxide (WOX) nanowires (NWs), a proposed photoanode material for water splitting. Key findings include (1) a planar defect-driven pseudo-one-dimensional growth mechanism and (2) morphological control through the supersaturation of vapor precursors. Result 1 is significant as it illustrates that common vapor-phase syntheses of WOX NWs depend on the formation of planar defects through NWs, which necessitates reconsideration of WOX as a photoanode. Chapter III presents work towards (1) single crystal WOX synthesis and characterization and (2) WOX NW device fabrication. Chapter IV makes use of the key result that WOX NWs are defect rich and therefore conductive in order to utilize them as a catalyst scaffold for oxygen evolution in acidic media. Work towards utilizing NW scaffolds include key results such as stability under anodic potentials and

  15. Method for manufacturing metal from fine-grain metal-oxide material

    SciTech Connect

    Edstrom, J.O.; Gorling, K.G.

    1984-02-28

    A method for producing fine-grain iron-containing metal oxide material, the method comprising a first reduction stage wherein the oxide material is at least partially reduced in a fluidized state at a temperature of approximately 1025/sup 0/-1275/sup 0/ K. by a reducing gas which is carbon monoxide or carbon monoxide mixed with hydrogen, followed by a smelting and final reduction stage to form a metal melt, the reducing gas used for the first reduction stage obtained from the smelting and final reduction stage. Prior to the first reduction stage, relatively large cakes or shaped pieces are formed from the fine-grain metal-oxide material in the presence of moisture and a hydraulic binder and the cakes or pieces caused to harden. The hardened oxide material is disintegrated and classified to form the starting material for the first reduction stage and is given a particle size distribution such that the material forms a fluidized bed which is substantially stationary at the considerable gas velocity required to carrying out the reduction process without bogging at the temperature selected for the first reduction stage.

  16. Phonon-coupled trap-assisted charge injection in metal-nitride-oxide-silicon/silicon-oxide-nitride-oxide-silicon structures

    NASA Astrophysics Data System (ADS)

    Nasyrov, K. A.; Shaimeev, S. S.; Gritsenko, V. A.; Han, J. H.

    2009-06-01

    A phonon-coupled trap model is proposed for trap-assisted injection mechanism in silicon-oxide-nitride-oxide-silicon (SONOS)/metal-nitride-oxide-silicon (MNOS) structures at low voltages. On the basis of this model, a theory of charge injection in SONOS/MNOS has been developed. Charge injection experimental data was fitted by this theory. Obtained trap parameters are close to those previously reported [K. A. Nasyrov et al., J. Appl. Phys. 96, 4293 (2004)], where the current dependence on temperature and electric field was investigated in MNOS.

  17. Synthesis and NMR characterization of ligand-capped metal and metal-oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh

    Ligand-capped metal and metal-oxide nanoparticles (NPs) have some interesting and useful physical properties that are not present in their respective bulk materials. These properties are of research interest in many applications such as catalysis, drug delivery, biological imaging, and plasmonics. In such applications, it is critical to understand the surface structure of NPs and the roles played by the surface bound ligands. To characterize surface environment, ligand dynamics, and exchange kinetics, ligand-capped metal and metal-oxide NPs are synthesized and studied by multinuclear NMR. Phosphines and phosphonic acids are used to passivate metal (gold and silver) and metal-oxide (tin dioxide) NPs in different sizes (1-5 nm) by following published procedures or original synthesis methods. In both solution and solid state NMR, the 31P chemical shift of surface-bound ligands are distinctly different from those observed for free ligands. Additionally, NMR line widths in surface-bound ligands are highly broadened compared to those of free ligands. The lines are broadened due to both homogeneous and inhomogeneous broadening mechanisms, determined through hole burning NMR and spin-spin relaxation measurements. In small particles (< 2 nm), the main source of line broadening is inhomogeneous and originates due to structural heterogeneity and underlying chemical shift distributions. In large particles (> 2 nm), both inhomogeneous and homogeneous line broadening mechanisms are present. When the particles' sizes increase from small to large, the homogeneous broadening mechanism becomes dominant due to strong nuclear-electron interaction and reintroduction of residual dipolar coupling as shown by a combination of 1H, 13C and 31P NMR. Results from a series of ligand exchange experiments in silver and gold NPs further indicate the presence of Au(I) and Ag(I) on the particle surfaces.

  18. Adsorption of antimony(V) onto Mn(II)-enriched surfaces of manganese-oxide and FeMn binary oxide.

    PubMed

    Liu, Ruiping; Xu, Wei; He, Zan; Lan, Huachun; Liu, Huijuan; Qu, Jiuhui; Prasai, Tista

    2015-11-01

    Manganese(IV) oxide [Mn(IV)] potentially oxidizes antimony(III) [Sb(III)] to antimony(V) [Sb(V)] and improves Sb removal by FeMn binary oxide (FMBO) through an oxidation-adsorption mechanism. This study focused on the effect of Mn(IV) reductive dissolution by potassium sulfite (K2SO3) on Sb(V) adsorption onto manganese oxide (Mn-oxide) and FMBO. The maximum Sb(V) adsorption (Qmax,Sb(V)) increased from 1.0 to 1.1 mmol g(-1) for FMBO and from 0.4 to 0.6 mmol g(-1) for Mn-oxide after pretreatment with 10 mmol L(-1) K2SO3. The addition of 2.5 mmol L(-1) Mn(2+) also significantly improved Sb(V) adsorption, and the observed Qmax,Sb(V) increased to 1.4 and 1.0 mmol g(-1) for FMBO and Mn-oxide, respectively, with pre-adsorbed Mn(2+). Neither K2SO3 nor Mn(2+) addition had any effect on Sb(V) adsorption onto iron oxide (Fe-oxide). Mn(2+) introduced by either Mn(IV) dissolution or addition tended to form outer-sphere surface complexes with hydroxyl groups on Mn-oxide surfaces (MnOOH). Mn(2+) at 2.5 mmol L(-1) shifted the isoelectric point (pHiep) from 7.5 to 10.2 for FMBO and from 4.8 to 9.2 for Mn-oxide and hence benefited Sb(V) adsorption. The adsorption of Sb(V) onto Mn(2+)-enriched surfaces contributed to the release of Mn(2+), and the X-ray photoelectron spectra also indicated increased binding energy of Mn 2p3/2 after the adsorption of Sb(V) onto K2SO3-pretreated FMBO and Mn-oxide. Sb(V) adsorption involved the formation of inner-sphere complexes and contributed to the release of Mn(2+). In the removal of Sb(III) by Mn-based oxides, the oxidation of Sb(III) to Sb(V) by Mn(IV) oxides had an effect; however, Mn(IV) dissolution and Mn(2+)-enrichment also played an important role.

  19. THE X-RAY LUMINOSITY FUNCTION OF LOW MASS X-RAY BINARIES IN EARLY-TYPE GALAXIES, THEIR METAL-RICH, AND METAL-POOR GLOBULAR CLUSTERS

    SciTech Connect

    Peacock, Mark B.; Zepf, Stephen E.

    2016-02-10

    We present the X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) in the globular clusters (GCs) and fields of seven early-type galaxies. These galaxies are selected to have both deep Chandra observations, which allow their LMXB populations to be observed to X-ray luminosities of 10{sup 37}–10{sup 38} erg s{sup −1}, and Hubble Space Telescope optical mosaics that enable the X-ray sources to be separated into field LMXBs, GC LMXBs, and contaminating background and foreground sources. We find that at all luminosities the number of field LMXBs per stellar mass is similar in these galaxies. This suggests that the field LMXB populations in these galaxies are not effected by the GC specific frequency, and that properties such as binary fraction and the stellar initial mass function are either similar across the sample or change in a way that does not affect the number of LMXBs. We compare the XLF of the field LMXBs to that of the GC LMXBs and find that they are significantly different with a p-value of 3 × 10{sup −6} (equivalent to 4.7σ for a normal distribution). The difference is such that the XLF of the GC LMXBs is flatter than that of the field LMXBs, with the GCs hosting relatively more bright sources and fewer faint sources. A comparison of the XLF of the metal-rich and metal-poor GCs hints that the metal-poor clusters may have more bright LMXBs, but the difference is not statistically significant.

  20. Systematics of compaction for porous metal and metal-oxide systems

    NASA Astrophysics Data System (ADS)

    Fredenburg, D. A.; Lang, J. M.; Coe, J. D.; Scharff, R. J.; Dattelbaum, D. M.; Chisolm, E. D.

    2017-01-01

    The effects of particle morphology and initial density is examined with respect to the shock densification response of initially porous metal (Cu) and metal-oxide (CeO2) materials. Specifically, the ability of a continuum-level compaction model to capture the measured densification trends as a function of initial density and particle morphology are investigated. Particle morphology is observed to have little effect on the densification response of both Cu and CeO2, while initial density appears to have a stronger effect. In terms of continuum-level compaction strength, Cu and CeO2 exhibit dissimilar trends.