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1

Slag Metal Reactions in Binary CaF2-Metal Oxide Welding Fluxes  

E-print Network

) Slag Metal Reactions in Binary CaF2-Metal Oxide Welding Fluxes Some otherwise chemically stable fluxes may decompose into suboxides in the presence of welding arcs, thereby providing higher levels of 0 2 in weld metal than those oxides which do not form suboxides ABSTRACT. The stability of metal

Eagar, Thomas W.

2

Magnetic binary metal oxides affinity probe for highly selective enrichment of phosphopeptides.  

PubMed

In this work, for the first time, binary metal oxides ((Ti-Sn)O4) were integrated into one entity on an atomic scale on magnetic graphene as affinity probe for highly selective enrichment of phosphopeptides. The newly prepared Fe3O4/graphene/(Ti-Sn)O4 (magG/(Ti-Sn)O4) composites gathered the advantages of large specific surface area of graphene, superparamagnetism, and biocompatibility of iron oxide, and enhanced affinity properties of binary metal oxides. The phosphopeptide enrichment efficiency of the magG/(Ti-Sn)O4 composite was investigated, and the results indicated an ultralow detection limit (1 pg/?L or 4.0 × 10(-11) M) and an ultrahigh selectivity (weight ratio of ?-casein and BSA reached up to 1:1500). Compared with magnetic affinity probes with single metal oxide (magG/TiO2, magG/SnO2) or the simple physical mixture of magG/TiO2 and magG/SnO2, the magG/(Ti-Sn)O4 composite possessed stronger specificity, higher selectivity and better efficiency; and more importantly, it possessed the ability to enrich both the mono- and multi- phosophorylated peptides, demonstrating the notable features of the novel binary metal oxides affinity probe in the specific and selective enrichment of phosphopeptides. Additionally, by utilizing the magG/(Ti-Sn)O4 composites, a total number of 349 phosphorylation sites on 170 phosphopeptides including 66 monophosphopeptides and 104 multiphosphopeptides were captured and identified from mouse brain, indicating the great potential for their application in phosphoproteomics analysis in the future. PMID:24911384

Wang, Mengyi; Deng, Chunhui; Li, Yan; Zhang, Xiangmin

2014-07-23

3

Benzotriazole removal from water by Zn–Al–O binary metal oxide adsorbent: Behavior, kinetics and mechanism  

Microsoft Academic Search

In this study, a novel Zn–Al–O binary metal oxide adsorbent was prepared and used to remove the emerging polar contaminant benzotriazole from water. The adsorption behavior, kinetics and mechanism were systemically studied. Results showed that benzotriazole was rapidly and effectively adsorbed by the adsorbent. Instantaneous adsorption was observed under each studied condition, and the adsorption reached equilibrium within 30min. High

Bingbing Xu; Fengchang Wu; Xiaoli Zhao; Haiqing Liao

2010-01-01

4

Pseudosolid, shear-thinning gel formation in binary dispersions of metal oxide nanoparticles at low volume fractions.  

PubMed

Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy. PMID:25438086

Weston, J S; Venkataramani, D; Aichele, C P; Grady, B P; Harwell, J; Resasco, D

2014-12-16

5

Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate  

NASA Astrophysics Data System (ADS)

Tungsten is considered a promising plasma facing armor material for future fusion devices. An electrodeposited metallic tungsten coating from Na2WO4-WO3 binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and electro-crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%.

Liu, Y. H.; Zhang, Y. C.; Jiang, F.; Fu, B. J.; Sun, N. B.

2013-11-01

6

Development and Evaluation of Nanoscale Sorbents for Mercury Capture from Warm Fuel Gas. Evaluation of Binary Metal Oxides for Mercury Capture  

SciTech Connect

Gas Technology Institute (GTI), in collaboration with Nanoscale Materials, Inc. (NanoScale), is developing and evaluating several nanocrystalline sorbents for capture of mercury from coal gasifier (such as IGCC) warm fuel gas. The focus of this study is on the understanding of fundamental mechanism of interaction between mercury and nanocrystalline sorbents over a range of fuel gas conditions. Detailed chemical and structural analysis of the sorbents will be carried out using an array of techniques, such as XPS, SEM, XRD, N{sub 2}-adsorption, to understand the mechanism of interaction between the sorbent and mercury. The proposed nanoscale oxides have significantly higher reactivities as compared to their bulk counterparts, which is a result of high surface area, pore volume, and nanocrystalline structure. These metal oxides/sulfides will be evaluated for their mercury-sorption potential in an experimental setup equipped with state-of-the-art analyzers. Initial screening tests will be carried out in N{sub 2} atmosphere, and two selected sorbents will be evaluated in simulated fuel gas containing H{sub 2}, H{sub 2}S, Hg and other gases. The focus will be on development of sorbents suitable for higher temperature (420-640 K) applications. In this Task, several formulations of binary metal oxide-based sorbents were prepared and evaluated for capture of mercury (Hg) in simulated fuel gas (SFG) atmosphere at temperatures in the range 423-533 K. The binary metal oxides with high surface area were found to be more effective, confirming the role of sorbent surface in mercury capture. These binary sorbents were found to be effective in capturing Hg at 473 and 533 K, with Hg capture decreasing at higher temperature. Based on the desorption studies, physical adsorption was found to be the dominant capture mechanism with lower temperatures favoring capture of Hg.

Raja A. Jadhav; Howard Meyer

2006-04-01

7

Modeling selective intergranular oxidation of binary alloys.  

PubMed

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 ?m ahead of grain boundary crack tips was documented for Ni-5Cr binary alloy, in contrast to relatively moderate Al depletion for Ni-5Al (?100 s 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. PMID:25573575

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

2015-01-01

8

Modeling selective intergranular oxidation of binary alloys  

NASA Astrophysics Data System (ADS)

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 ?m ahead of grain boundary crack tips was documented for Ni-5Cr binary alloy, in contrast to relatively moderate Al depletion for Ni-5Al (˜100 s 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.

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

2015-01-01

9

Metal oxide films on metal  

DOEpatents

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.

Wu, Xin D. (Los Alamos, NM); Tiwari, Prabhat (Los Alamos, NM)

1995-01-01

10

Binary alloys for refractory-metal brazing  

NASA Technical Reports Server (NTRS)

Data on binary-metal eutectics and melting-point minimums have been assembled for use in selecting brazing filler compositions for refractory metals. Data are presented in four tables for ready reference. Brief discussion of problems and potentials of metallides is included in appendix.

Morris, J. F.

1974-01-01

11

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

12

Metal oxide sensors  

Microsoft Academic Search

New gas sensors based on novel semiconducting metal oxides are developed. In comparison to the sensors based on SnO2 their properties are improved in several items. The main improvements are the lower influence of humidity, the long-term stability, the ability to start measurement immediately after switch on and reduced unit spread. The sensors will be marketed within this year.

H. Meixner; U. Lampe

1996-01-01

13

Thermodynamic stability of binary oxides in contact With silicon  

Microsoft Academic Search

Using tabulated thermodynamic data, a comprehensive investigation of the thermodynamic stability of binary oxides in contact with silicon at 1000 K was conducted. Reactions between silicon and each binary oxide at 1000 K, including those involving ternary phases, were considered. Sufficient data exists to conclude that all binary oxides except the following are thermodynamically unstable in contact with silicon at

K. J. Hubbard; D. G. Schlom

1996-01-01

14

Stochastic learning in oxide binary synaptic device for neuromorphic computing  

PubMed Central

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. PMID:24198752

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

2013-01-01

15

Synthesis and characterization of binary titania-silica mixed oxides  

NASA Astrophysics Data System (ADS)

A series of binary titania-silica mixed oxides were synthesized by the sol-gel method at room temperature. The mixed oxides were prepared that involved the hydrolysis of titanium isopropoxide and tetraethylorthosilicate (TEOS) by co-solvent induced gelation usually in acidic media. The resulting gels were dried, calcined and then characterized by powder X-ray diffractometric studies, nitrogen sorption studies (at 77K), diffuse reflectance spectroscopy, Raman microscopy and transmission electron microscopic studies. The nitrogen sorption studies indicate that the specific surface areas, pore volume, pore diameter and pore size distribution of the mixed oxides were substantially enhanced when non-polar solvents such as toluene, p-xylene or mesitylene were added as co-solvents to the synthesis gel. Transmission electron microscopic (TEM) studies confirm the results obtained from the nitrogen sorption studies. Our results indicate that we can obtain binary metal oxides possessing high surface area and large pore volumes with tunable pore size distribution at room temperature. Photocatalytic evaluation of the mixed oxides is currently in progress.

Budhi, Sridhar

16

Oxidation Behavior of Binary Niobium Alloys  

NASA Technical Reports Server (NTRS)

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, are masked by the overriding tendency for a porous scale.

Barrett, Charles A.; Corey, James L.

1960-01-01

17

Simple Route to Gradient Concentric Metal and Metal Oxide Rings  

E-print Network

Simple Route to Gradient Concentric Metal and Metal Oxide Rings Suck Won Hong, Supratim Giri on metal and metal oxide have been reported. The rings organized in a concentric mode many offer systems.13 Herein, we report on a simple route to concentric rings of metals or metal oxide. The gradient

Lin, Zhiqun

18

Thin film hydrous metal oxide catalysts  

DOEpatents

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.

Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM)

1995-01-01

19

Synthesis, characterization and formation process of transition metal oxide nanotubes using carbon nanofibers as templates  

SciTech Connect

Mono and binary transition metal oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air. The transition metal oxide nanotubes were composed of nano-crystallites of metal oxides. The functional groups on the carbon nanofiber templates were essential for the coating of these templates: they acted as adsorption sites for the metal nitrates, ensuring a uniform metal oxide coating. During the removal of the carbon nanofiber templates by calcination in air, the metal oxide coatings promoted the combustion reaction between the carbon nanofibers and oxygen. - Graphical abstract: Mono and binary transition metal-oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air.

Ogihara, Hitoshi, E-mail: ogihara@cms.titech.ac.j [Catalysis Research Center, Hokkaido University, N21-W10 Kita-ku, Sapporo 001-002 (Japan); Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo 102-8472 (Japan); Masahiro, Sadakane [Catalysis Research Center, Hokkaido University, N21-W10 Kita-ku, Sapporo 001-002 (Japan); Nodasaka, Yoshinobu [Oral Functional Science, Graduate School of Dental Medicine, Hokkaido University, N13-W7 Kita-ku, Sapporo 060-8586 (Japan); Ueda, Wataru, E-mail: ueda@cat.hokudai.ac.j [Catalysis Research Center, Hokkaido University, N21-W10 Kita-ku, Sapporo 001-002 (Japan)

2009-06-15

20

Homogeneous crystal nucleation in binary metallic melts  

NASA Technical Reports Server (NTRS)

A method for calculating the homogeneous crystal nucleation frequency in binary metallic melts is developed. The free energy of crystallization is derived from regular solution models for the liquid and solid and is used, together with model-based estimates of the interfacial tension, to calculate the nucleation frequency from the classical theory. The method can account for the composition dependence of the maximum undercooling observed in a number of experiments on small droplet dispersions. It can also be used to calculate the driving force for crystal growth and to obtain more precise estimates of the homogeneous crystal nucleation frequency in glass-forming alloys. This method, although approximate, is simple to apply, and requires only knowledge of the phase diagram and a few readily available thermodynamic quantities as input data.

Thompson, C. V.; Spaepen, F.

1983-01-01

21

Diffusion and interdiffusion in binary metallic melts  

NASA Astrophysics Data System (ADS)

We discuss the dependence of self- and interdiffusion coefficients on temperature and composition for two prototypical binary metallic melts, Al-Ni and Zr-Ni, in molecular-dynamics computer simulations and the mode-coupling theory of the glass transition (MCT). Dynamical processes that are mainly entropic in origin slow down mass transport (as expressed through self-diffusion) in the mixture as compared to the ideal-mixing contribution. Interdiffusion of chemical species is a competition of slow kinetic modes with a strong thermodynamic driving force that is caused by nonentropic interactions. The combination of both dynamic and thermodynamic effects causes qualitative differences in the concentration dependence of self-diffusion and interdiffusion coefficients. At high temperatures, the thermodynamic enhancement of interdiffusion prevails, while at low temperatures, kinetic effects dominate the concentration dependence, rationalized within MCT as the approach to its ideal-glass transition temperature Tc. The Darken equation relating self- and interdiffusion qualitatively reproduces the concentration dependence in both Zr-Ni and Al-Ni, but quantitatively, the kinetic contributions to interdiffusion can be slower than the lower bound suggested by the Darken equation. As temperature is decreased, the agreement with Darken's equation improves, due to a strong coupling of all kinetic modes that is a generic feature predicted by MCT.

Kuhn, P.; Horbach, J.; Kargl, F.; Meyer, A.; Voigtmann, Th.

2014-07-01

22

Metal oxide analogue of metal alloy catalysts  

NASA Astrophysics Data System (ADS)

Because of ion size, valence and oxide structure, hafnium and zirconium mixed oxide catalysts are ideal for study as a metal alloy analogue. Furthermore, hafnium oxide and zirconium oxide exhibit quite different selectivity for the conversion of 2-alcohols to alkene products. The alkene selectivity changed abruptly from that of pure HfO 2 to that of pure ZrO 2 at a composition with ca. 90 mol% Zr. Characterization of the catalysts by ESCA, Auger, and ISS spectroscopy show that the surface composition is very similar to the bulk composition and, thus, changes uniformly throughout the composition range rather than abruptly as does the alkene selectivity. Pure ZrO 2 impregnated with Hf to produce catalysts with the full range of Hf-Zr surface compositions showed a catalytic selectivity that paralleled the selectivity of the bulk composition catalysts. Zr or Th impregnated onto alumina serve as catalyst poisons; however, these two metals alter the selectivity in a quite different manner. The data indicate that the catalytic selectivity of these mixed oxide catalysts is determined by ligand, rather than bulk electronic, effects.

Davis, Burtron H.

1984-11-01

23

Lithium metal reduction of plutonium oxide to produce plutonium metal  

DOEpatents

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.

Coops, Melvin S. (Livermore, CA)

1992-01-01

24

Method for plating with metal oxides  

SciTech Connect

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.

Silver, Gary L. (Centerville, OH); Martin, Frank S. (Farmersville, OH)

1994-08-23

25

Molecular Level Coating for Metal Oxide Particles  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

26

Molecular Level Coating of Metal Oxide Particles  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

27

Metals, toxicity and oxidative stress.  

PubMed

Metal-induced toxicity and carcinogenicity, with an emphasis on the generation and role of reactive oxygen and nitrogen species, is reviewed. Metal-mediated formation of free radicals causes various modifications to DNA bases, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Lipid peroxides, formed by the attack of radicals on polyunsaturated fatty acid residues of phospholipids, can further react with redox metals finally producing mutagenic and carcinogenic malondialdehyde, 4-hydroxynonenal and other exocyclic DNA adducts (etheno and/or propano adducts). Whilst iron (Fe), copper (Cu), chromium (Cr), vanadium (V) and cobalt (Co) undergo redox-cycling reactions, for a second group of metals, mercury (Hg), cadmium (Cd) and nickel (Ni), the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. Arsenic (As) is thought to bind directly to critical thiols, however, other mechanisms, involving formation of hydrogen peroxide under physiological conditions, have been proposed. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. Common mechanisms involving the Fenton reaction, generation of the superoxide radical and the hydroxyl radical appear to be involved for iron, copper, chromium, vanadium and cobalt primarily associated with mitochondria, microsomes and peroxisomes. However, a recent discovery that the upper limit of "free pools" of copper is far less than a single atom per cell casts serious doubt on the in vivo role of copper in Fenton-like generation of free radicals. Nitric oxide (NO) seems to be involved in arsenite-induced DNA damage and pyrimidine excision inhibition. Various studies have confirmed that metals activate signalling pathways and the carcinogenic effect of metals has been related to activation of mainly redox-sensitive transcription factors, involving NF-kappaB, AP-1 and p53. Antioxidants (both enzymatic and non-enzymatic) provide protection against deleterious metal-mediated free radical attacks. Vitamin E and melatonin can prevent the majority of metal-mediated (iron, copper, cadmium) damage both in vitro systems and in metal-loaded animals. Toxicity studies involving chromium have shown that the protective effect of vitamin E against lipid peroxidation may be associated rather with the level of non-enzymatic antioxidants than the activity of enzymatic antioxidants. However, a very recent epidemiological study has shown that a daily intake of vitamin E of more than 400 IU increases the risk of death and should be avoided. While previous studies have proposed a deleterious pro-oxidant effect of vitamin C (ascorbate) in the presence of iron (or copper), recent results have shown that even in the presence of redox-active iron (or copper) and hydrogen peroxide, ascorbate acts as an antioxidant that prevents lipid peroxidation and does not promote protein oxidation in humans in vitro. Experimental results have also shown a link between vanadium and oxidative stress in the etiology of diabetes. The impact of zinc (Zn) on the immune system, the ability of zinc to act as an antioxidant in order to reduce oxidative stress and the neuroprotective and neurodegenerative role of zinc (and copper) in the etiology of Alzheimer's disease is also discussed. This review summarizes recent findings in the metal-induced formation of free radicals and the role of oxidative stress in the carcinogenicity and toxicity of metals. PMID:15892631

Valko, M; Morris, H; Cronin, M T D

2005-01-01

28

A Search for Binary Stars at Low Metallicity  

E-print Network

We present initial results measuring the companion fraction of metal-poor stars ([Fe/H]$<-$2.0). We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects. The binary fraction of metal-poor stars provides important constraints on star formation in the early Galaxy (Carney et al. 2003). Although it has been shown that a majority of solar metallicity stars are in binaries, it is not clear if this is the case for metal-poor stars. Is there a metallicity floor below which binary systems do not form or become rare? To test this we are determining binary fractions at metallicities below [Fe/H]$=-2.0$. Our measurments are not as precise as the planet finders', but we are still finding errors of only 50 to 300 m/s, depending on the signal-to-noise of a spectrum and stellar atmosphere of the star. At this precision we can be much more complete than previous studies in our search for stellar companions.

David K. Lai; Sara Lucatello; Michael Bolte; Debra A. Fischer; Jennifer A. Johnson

2007-08-30

29

M-Dwarf Metallicity through Analysis of Binary Partner  

NASA Astrophysics Data System (ADS)

We present work on determining the metallicity of M-dwarfs through analysis of M-star containing binary pairs and discuss its potential use with regards to exoplanet host star population studies. It is notoriously difficult to directly measure the metallicity of M-dwarf stars via their spectra due to the complexity of their composition; by study of the spectra of M-dwarfs and their binary partners, a technique to determine the metallicity of M-dwarfs via spectra analysis can be developed. Assuming that the metallicity of two stars in a binary pair is similar, by studying the metal content of the more easily measured solar type star and correlating that to various spectra line indices in the accompanying M-dwarf, we can indirectly measure the metal content of the M-dwarf. We use both high and low resolution spectra of 50+ halo binary stars in the northern hemisphere collected at McDonald Observatory to perform this analysis.

Nagasawa, Daniel; Marshall, Jennifer L.; Li, Ting

2015-01-01

30

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

31

Nanostructured transition metal oxides useful for water oxidation catalysis  

DOEpatents

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.

Frei, Heinz M; Jiao, Feng

2013-12-24

32

Preparing oxidizer coated metal fuel particles  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

33

Ammonia release method for depositing metal oxides  

DOEpatents

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.

Silver, Gary L. (Centerville, OH); Martin, Frank S. (Farmersville, OH)

1994-12-13

34

Ammonia release method for depositing metal oxides  

DOEpatents

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.

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

1994-12-13

35

Method for producing metal oxide nanoparticles  

DOEpatents

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.

Phillips, Jonathan (Santa Fe, NM); Mendoza, Daniel (Santa Fe, NM); Chen, Chun-Ku (Albuquerque, NM)

2008-04-15

36

Spectroscopic Metallicity Determinations for W UMa-type Binary Stars  

NASA Astrophysics Data System (ADS)

This study is the first attempt to determine the metallicities of W UMa-type binary stars using spectroscopy. We analyzed about 4500 spectra collected at the David Dunlap Observatory. To circumvent problems caused by the extreme spectral line broadening and blending and by the relatively low quality of the data, all spectra were subject to the same broadening function (BF) processing to determine the combined line strength in the spectral window centered on the Mg I triplet between 5080 Å and 5285 Å. All individual integrated BFs were subsequently orbital-phase averaged to derive a single line-strength indicator for each star. The star sample was limited to 90 W UMa-type (EW) binaries with the strict phase-constancy of colors and without spectral contamination by spectroscopic companions. The best defined results were obtained for an F-type sub-sample (0.32 < (B - V)0 < 0.62) of 52 binaries for which integrated BF strengths could be interpolated in the model atmosphere predictions. The logarithmic relative metallicities, [M/H], for the F-type sub-sample indicate metal abundances roughly similar to the solar metallicity, but with a large scatter which is partly due to combined random and systematic errors. Because of the occurrence of a systematic color trend resulting from inherent limitations in our approach, we were forced to set the absolute scale of metallicities to correspond to that derived from the m 1 index of the Strömgren uvby photometry for 24 binaries of the F-type sub-sample. The trend-adjusted metallicities [M/H]1 are distributed within -0.65 < [M/H]1 < +0.50, with the spread reflecting genuine metallicity differences between stars. One half of the F-sub-sample binaries have [M/H]1 within -0.37 < [M/H]1 < +0.10, a median of -0.04 and a mean of -0.10, with a tail toward low metallicities, and a possible bias against very high metallicities. A parallel study of kinematic data, utilizing the most reliable and recently obtained proper motion and radial velocity data for 78 binaries of the full sample, shows that the F-type sub-sample binaries (44 stars with both velocities and metallicity determinations) have similar kinematic properties to solar-neighborhood, thin-disk dwarfs with space velocity component dispersions: ?U = 33 km s-1, ?V = 23 km s-1 and ?W = 14 km s-1. FU Dra with a large spatial velocity, V tot = 197 km s-1 and [M/H]1 = -0.6 ± 0.2, appears to be the only thick-disk object in the F-type sub-sample. The kinematic data indicate that the F-type EW binaries are typical, thin-disk population stars with ages about 3-5.5 Gyr. The F-type binaries that appear to be older than the rest tend to have systematically smaller mass ratios than most of the EW binaries of the same period. Based on observations obtained at the David Dunlap Observatory, University of Toronto.

Rucinski, Slavek M.; Pribulla, Theodor; Budaj, Ján

2013-09-01

37

The oxidation of metals and alloys  

NASA Technical Reports Server (NTRS)

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.

Scheil, Erich

1952-01-01

38

Reduction of Metal Oxide to Metal using Ionic Liquids  

SciTech Connect

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. Successful extraction of metal from metal oxide dissolved in Urea/ChCl (2:1) was accomplished. The current efficiencies were relatively high in both the metal deposition processes with current efficiency greater than 86% for lead and 95% for zinc. This technology will advance the metal oxide reduction process by increasing the process efficiency and also eliminate the production of CO2 which makes this an environmentally benign technology for metal extraction.

Dr. Ramana Reddy

2012-04-12

39

Nanocomposite of graphene and metal oxide materials  

DOEpatents

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.

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

2012-09-04

40

High temperature, oxidation resistant noble metal-Al alloy thermocouple  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

41

Catalytic oxidation of diesel particulates with base metal oxides  

Microsoft Academic Search

Reduction of emissions from diesel engines using novel flow-through oxidation catalysts containing base metal oxides has been demonstrated. The soluble organic fraction (SOF) of the particulates can be converted and gas phase hydrocarbons can be removed via the proper choice of oxides. Low levels of platinum on the catalysts also compliment HC and CO conversion without leading to “sulfate-make”. Catalyst

K. E. Voss; J. K. Lampert; R. J. Farrauto; G. W. Rice; A. Punke; R. Krohn

1995-01-01

42

Method of producing adherent metal oxide coatings on metallic surfaces  

DOEpatents

Provided is a process of producing an adherent synthetic corrosion product (sludge) coating on metallic surfaces. The method involves a chemical reaction between a dry solid powder mixture of at least one reactive metal oxide with orthophosphoric acid to produce a coating in which the particles are bound together and the matrix is adherent to the metallic surface.

Lane, Michael H. (Clifton Park, NY); Varrin, Jr., Robert D. (McLean, VA)

2001-01-01

43

Methods of producing adsorption media including a metal oxide  

DOEpatents

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.

Mann, Nicholas R; Tranter, Troy J

2014-03-04

44

A metal-oxide-semiconductor varactor  

Microsoft Academic Search

CMOS technology scaling opens up the possibility of designing variable capacitors based on a metal oxide semiconductor structure with improved tuning range and quality factor. This is due to an increase in the oxide capacitance and a reduction in the parasitic resistance. A prototype metal-oxide-semiconductor (MOS) variable capacitor of 3.1 pF nominal value has been realized in a 0.35-?m standard

F. Svelto; P. Erratico; S. Manzini; R. Castello

1999-01-01

45

Wettability of transition metal oxide surfaces  

Microsoft Academic Search

The wettability of transition metal oxide surfaces (TiO2, ZrO2 and HfO2) by water was investigated by measuring the contact angles using the sessile drop method. The oxide surfaces were prepared by thermal oxidation of polished metal foils of Ti, Zr and Hf, which had been polished to different levels of surface roughness. The surfaces were also characterized by optical microscopy,

Aiguo Feng; Benjamin J McCoy; Zuhair A Munir; Domenick Cagliostro

1998-01-01

46

Method for making monolithic metal oxide aerogels  

DOEpatents

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.

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

1995-03-07

47

Method for making monolithic metal oxide aerogels  

DOEpatents

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.

Droege, Michael W. (Livermore, CA); Coronado, Paul R. (Livermore, CA); Hair, Lucy M. (Livermore, CA)

1995-01-01

48

Three-electrode metal oxide reduction cell  

DOEpatents

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.

Dees, Dennis W. (Downers Groves, IL); Ackerman, John P. (Downers Grove, IL)

2008-08-12

49

40 CFR 721.4610 - Mixed metal oxides (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Mixed metal oxides (generic). 721.4610 Section 721...Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance...substance identified generically as mixed metal oxides (PMN P-98-0002) is subject...

2012-07-01

50

40 CFR 721.4610 - Mixed metal oxides (generic).  

... 2014-07-01 false Mixed metal oxides (generic). 721.4610 Section 721...Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance...substance identified generically as mixed metal oxides (PMN P-98-0002) is subject...

2014-07-01

51

40 CFR 721.5548 - Mixed metal oxide (generic).  

... 2014-07-01 false Mixed metal oxide (generic). 721.5548 Section...Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical...identified generically as a mixed metal oxide (PMN P-97-956) is...

2014-07-01

52

40 CFR 721.5549 - Lithiated metal oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Lithiated metal oxide. 721.5549 Section 721...Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and...identified generically as lithiated metal oxide (LiNiO2 ) (PMN...

2013-07-01

53

40 CFR 721.4610 - Mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Mixed metal oxides (generic). 721.4610 Section...Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical...identified generically as mixed metal oxides (PMN P-98-0002) is...

2013-07-01

54

40 CFR 721.5548 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Mixed metal oxide (generic). 721.5548 Section...Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical...identified generically as a mixed metal oxide (PMN P-97-956) is...

2012-07-01

55

40 CFR 721.5549 - Lithiated metal oxide.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Lithiated metal oxide. 721.5549 Section 721...Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and...identified generically as lithiated metal oxide (LiNiO2 ) (PMN...

2010-07-01

56

40 CFR 721.4610 - Mixed metal oxides (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Mixed metal oxides (generic). 721.4610 Section...Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical...identified generically as mixed metal oxides (PMN P-98-0002) is...

2010-07-01

57

Direct electrochemical reduction of metal-oxides  

DOEpatents

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.

Redey, Laszlo I. (Downers Grove, IL); Gourishankar, Karthick (Downers Grove, IL)

2003-01-01

58

High dielectric constant gate oxides for metal oxide Si transistors  

Microsoft Academic Search

The scaling of complementary metal oxide semiconductor transistors has led to the silicon dioxide layer, used as a gate dielectric, being so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (kappa) or 'high K' gate oxides such as hafnium oxide

John Robertson

2006-01-01

59

Universality in surface mixing rule of adsorption strength for small adsorbates on binary transition metal alloys.  

PubMed

Understanding the adsorption phenomena of small adsorbates involved in surface reactions on transition metals is important because their adsorption strength can be a descriptor for predicting the catalytic activity. To explore adsorption energies on a wide range of binary transition metal alloys, however, tremendous computational efforts are required. Using density functional theory (DFT) calculations, here we suggest a "surface mixing rule" to predict the adsorption energies of H, O, S, CO and OH on bimetallic alloys, based on the linear interpolation of adsorption energies on each pure surface. As an application, the activity of CO oxidation on various bimetallic alloys is predicted from the adsorption energies of CO and O easily obtained by the surface mixing rule. Our results provide a useful tool for rapidly estimating adsorption energies, and furthermore, catalytic activities on multi-component metal alloy surfaces. PMID:25515855

Ko, Jeonghyun; Kwon, Hyunguk; Kang, Hyejin; Kim, Byung-Kook; Han, Jeong Woo

2015-02-01

60

Ultrafine metal oxides dismantle chlorinated organics  

SciTech Connect

Researchers at Kansas State University (Manhattan) have developed a low-temperature, noncatalytic process that destroys chlorinated organic compounds without creating harmful byproducts. The process, dubbed destructive adsorption, uses ultrafine particles of several common metal oxides to convert chlorocarbon molecules into metal chlorides and carbon oxides. To date, the process has only been demonstrated for the bench-scale decomposition of carbon tetrachloride (CCl{sub 4}). However, Colorado-based NanTech has recently been awarded a grant to develop the process for commercialization. Certain metal oxides, such as CaO and MgO, react favorably with many of the chlorinated organics commonly found in industrial exhaust streams, and in the organics-laden vapors commonly recovered during soil and groundwater remediation. In the presence of chlorinated compounds such as carbon tetrachloride (CCl{sub 4}), chloroform (CHCl{sub 3}), tetrachloroethylene (C{sub 2}Cl{sub 4}) and chlorobenzene (C{sub 6}H{sub 5}Cl), these metal oxides adsorb chlorine atoms to form metal chlorides (MgCl{sub 2} or CaCl{sub 2}), and their oxygen atoms combine with carbon in the organics to form CO and CO{sub 2}. While these reactions are favorable from a thermodynamic standpoint (all are mildly exothermic), reaction rates are kinetically limited, because they involve solid-gas or solid-liquid reactions. As the metal chloride forms on the surface of the metal oxide, the resulting salt buildup gradually impedes--and eventually prevents--the reaction between the metal oxide and the chlorocarbon compound. To overcome this obstacle, the Kansas State researchers experimented with extremely small particles of metal oxides--less than 25 nanometers dia.--to maximize overall surface area. This increased the reactivity and the capacity of the metal oxide particles.

NONE

1995-07-01

61

Catalytic production of metal carbonyls from metal oxides  

DOEpatents

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.

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

1984-01-06

62

Memristive switching mechanism for metal\\/oxide\\/metal nanodevices  

Microsoft Academic Search

Nanoscale metal\\/oxide\\/metal switches have the potential to transform the market for nonvolatile memory and could lead to novel forms of computing. However, progress has been delayed by difficulties in understanding and controlling the coupled electronic and ionic phenomena that dominate the behaviour of nanoscale oxide devices. An analytic theory of the ‘memristor’ (memory-resistor) was first developed from fundamental symmetry arguments

J. Joshua Yang; Matthew D. Pickett; Xuema Li; Douglas A. A. Ohlberg; R. Stanley Williams; Duncan R. Stewart

2008-01-01

63

High surface area, electrically conductive nanocarbon-supported metal oxide  

DOEpatents

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.

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

64

Ordered mesoporous metal oxides: synthesis and applications.  

PubMed

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. PMID:22653082

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

2012-07-21

65

Lithium metal oxide electrodes for lithium batteries  

DOEpatents

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.

Thackeray, Michael M. (Naperville, IL); Kim, Jeom-Soo (Naperville, IL); Johnson, Christopher S. (Naperville, IL)

2008-01-01

66

Process for etching mixed metal oxides  

DOEpatents

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.

Ashby, Carol I. H. (Edgewood, NM); Ginley, David S. (Evergreen, CO)

1994-01-01

67

Process for etching mixed metal oxides  

DOEpatents

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.

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

1994-10-18

68

Multilevel metallization method for fabricating a metal oxide semiconductor device  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

69

Development of techniques for processing metal-metal oxide systems  

NASA Technical Reports Server (NTRS)

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.

Johnson, P. C.

1976-01-01

70

Cyclic Catalytic Upgrading of Chemical Species Using Metal Oxide Materials  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

71

Antimicrobial activity of the metals and metal oxide nanoparticles.  

PubMed

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. PMID:25280707

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

2014-11-01

72

Self-assembly of metal nanostructures on binary alloy surfaces  

PubMed Central

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. PMID:21097706

Duguet, T.; Han, Yong; Yuen, Chad; Jing, Dapeng; Ünal, Bar??; Evans, J. W.; Thiel, P. A.

2011-01-01

73

Self-assembly of metal nanostructures on binary alloy surfaces.  

PubMed

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. PMID:21097706

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

2011-01-18

74

Exploiting Covalency to Enhance MetalOxide and OxideOxide Adhesion at Heterogeneous Interfaces  

E-print Network

protec- tion, and protection against hot oxidation/corrosion are especially vital properties the aluminum content in the bond-coat alloy, since alumina (Al2O3) provides a slow-growing oxideExploiting Covalency to Enhance Metal­Oxide and Oxide­Oxide Adhesion at Heterogeneous Interfaces

Carter, Emily A.

75

Properties of binary transition-metal arsenides (TAs)  

NASA Astrophysics Data System (ADS)

We present thermodynamic and transport properties of transition-metal (T) arsenides, TAs, with T = Sc to Ni (3d), Zr, Nb, Ru (4d), Hf and Ta (5d). Characterization of these binaries is carried out with powder x-ray diffraction, temperature- and field-dependent magnetization and resistivity, temperature-dependent heat capacity, Seebeck coefficient, and thermal conductivity. All binaries show metallic behavior except TaAs and RuAs. TaAs, NbAs, ScAs and ZrAs are diamagnetic, while CoAs, VAs, TiAs, NiAs and RuAs show approximately Pauli paramagnetic behavior. FeAs and CrAs undergo antiferromagnetic ordering below TN ? 71 K and TN ? 260 K, respectively. MnAs is a ferromagnet below TC ? 317 K and undergoes hexagonal-orthorhombic-hexagonal transitions at TS ? 317 K and 384 K, respectively. For TAs, Seebeck coefficients vary between + 40 and - 40 ?V K-1 in the 2-300 K range, whereas thermal conductivity values stay below 18 W m-1 K-1. The Sommerfeld coefficients ? are less than 10 mJ K-2 mol-1. At room temperature with application of 8 T magnetic field, large positive magnetoresistance is found for TaAs (˜25%), MnAs (˜90%) and NbAs (˜75%).

Saparov, Bayrammurad; Mitchell, Jonathan E.; Sefat, Athena S.

2012-08-01

76

Oxidation and reduction in irradiated binary crystals of resorcinol and progesterone  

SciTech Connect

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)

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

1985-12-01

77

PLUTONIUM METAL: OXIDATION CONSIDERATIONS AND APPROACH  

SciTech Connect

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.

Estochen, E.

2013-03-20

78

Metals, Toxicity and Oxidative Stress  

Microsoft Academic Search

Metal-induced toxicity and carcinogenicity, with an emphasis on the generation and role of reactive oxygen and nitrogen species, is reviewed. Metal-mediated formation of free radicals causes various modifications to DNA bases, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Lipid peroxides, formed by the attack of radicals on polyunsaturated fatty acid residues of phospholipids , can further react with

M. Valko; H. Morris; M. T. D. Cronin

2005-01-01

79

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

PubMed

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. PMID:25662252

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

2015-02-01

80

Solution synthesis of nanoparticular binary transition metal antimonides.  

PubMed

The preparation of nanoengineered materials with controlled nanostructures, for example, with an anisotropic phase segregated structure or a regular periodicity rather than with a broad range of interparticle distances, has remained a synthetic challenge for intermetallics. Artificially structured materials, including multilayers, amorphous alloys, quasicrystals, metastable crystalline alloys, or granular metals, are mostly prepared using physical gas phase procedures. We report a novel, powerful solution-mediated approach for the formation of nanoparticular binary antimonides based on presynthesized antimony nanoparticles. The transition metal antimonides M-Sb (M = Co, Ni, Cu(2), Zn) were obtained with sizes ranging from 20 and 60 nm. Through careful control of the reaction conditions, single-phase nanoparticular antimonides were synthesized. The nanophases were investigated by powder X-ray diffraction and (high resolution) electron microscopy. The approach is based on activated metal nanoparticles as precursors for the synthesis of the intermetallic compounds. X-ray powder diffraction studies of reaction intermediates allowed monitoring of the reaction kinetics. The small particle size of the reactants ensures short diffusion paths, low activation barriers, and low reaction temperatures, thereby eliminating solid-solid diffusion as the rate-limiting step in conventional bulk-scale solid-state synthesis. PMID:21736318

Kieslich, Gregor; Birkel, Christina S; Stewart, Andrew; Kolb, Ute; Tremel, Wolfgang

2011-08-01

81

THEORY OF MOTTTRANSITION : APPLICATION S TO TRANSITION METAL OXIDES  

E-print Network

125 THEORY OF MOTTTRANSITION : APPLICATION S TO TRANSITION METAL OXIDES M. CYROT Institut Laue discuss the relevance of the theory to transition metal oxides. The main qualitative features in transition metal oxides. These oxides form a very interesting class of materials [1]. Their electrical

Paris-Sud XI, Université de

82

Interfacial Reactions between Oxide Films and Refractory Metal Substrates  

E-print Network

Interfacial Reactions between Oxide Films and Refractory Metal Substrates X. Xu, W. S. Oh, and D. W,thelatterbeingencapsulatedbythemolybdenum oxides. Above 1200 K, both metallic nickel and molybdenum oxides are evolved from the surface-grown oxide thin films on various metal substrates [for example, NiO/Mo(100), MgO/Mo(100) and Al2O3/Ta(110

Goodman, Wayne

83

Mathematical modeling of microsegregation in binary metallic alloys  

NASA Astrophysics Data System (ADS)

A mathematical model was developed to calculate microsegregation in binary metallic alloys. This model utilized the mathematical techniques of the method of lines combined with invariant imbedding (MOL/II) to solve the problem of combined heat and mass transfer during and after solidification. Model predictions were compared to experimental measurements in the Al-Cu system and to other microsegregation models. The MOL/II model predicted nonequilibrium second-phase contents within ±3 pct at low and intermediate cooling rates, when dendrite-arm coarsening was included in the model. It also was able to reproduce concentration profiles reasonably well. The analytical models commonly used (equilibrium cooling, Scheil equation, Brody/ Flemings model, Clyne/Kurz model, Solari/Biloni model, and Basaran equation) in micro-segregation calculations were shown to be considerably less accurate than the numerical models (MOL/II and the Ogilvy/Kirkwood model).

Battle, Thomas P.; Pehlke, Robert D.

1990-04-01

84

Reduction of metal oxides through mechanochemical processing  

DOEpatents

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.

Froes, Francis H. (Moscow, ID); Eranezhuth, Baburaj G. (Moscow, ID); Senkov, Oleg N. (Moscow, ID)

2000-01-01

85

Role of metal oxides in chemical evolution  

NASA Astrophysics Data System (ADS)

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. Formation of small molecules like amino acids, organic bases, sugar etc. could have occurred in the reducing atmosphere of the primitive Earth. Polymerization of these small molecules 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.

Kamaluddin

2013-06-01

86

Differential cytotoxicity of metal oxide nanoparticles  

Microsoft Academic Search

Concerns about the potential health hazards of nanomaterials are growing. To determine the potential toxicity of metal oxide nanoparticles, human SH-SY5Y neuroblastoma and H4 neuroglioma cells were exposed to Fe2O3, CuO and ZnO nanoparticles and their metal ion counterparts (Fe, Cu and Zn) at a concentration range of 0.01–100 µM for 48 h, under the cell culture conditions: 95% O2,

Jian Chen; Jinmin Zhu; Hyun-Hee Cho; Kemi Cui; Fuhai Li; Xiaobo Zhou; Jack T. Rogers; Stephen T. C. Wong; Xudong Huang

2008-01-01

87

Orbital Physics in Transition-Metal Oxides  

Microsoft Academic Search

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

Y. Tokura; N. Nagaosa

2000-01-01

88

Microwave properties of thermochromic metal oxide surfaces  

Microsoft Academic Search

Thermochromic metal oxides with a Mott transition, such as vanadium dioxide (VO2) exhibit an extensive alteration in their infrared reflectivity when heated above the transition temperature. For VO2 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

Jan-Olof Ousbäck; Hans Kariis

2006-01-01

89

Quantum Criticality in Transition-Metal Oxides  

Microsoft Academic Search

We report on experiments of the bulk susceptibility ?(T), heat capacity C(T)\\/T, resistivity ?(T) and nuclear resonances (NMR and NQR) in order to review evidence of quantum critical behaviour in some metallic transition-metal\\u000a oxides. In analogy to the conventional 4f- and 5f-electron based heavy-fermion compounds, the prerequisites of quantum criticality, i.e. a magnetic phase transition at T=0 accompanied by non-Fermi

N. Büttgen; H.-A. Krug von Nidda; W. Kraetschmer; A. Günther; S. Widmann; S. Riegg; A. Krimmel; A. Loidl

2010-01-01

90

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

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.

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

1999-06-22

91

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

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.

Turk, Brian S. (Durham, NC); Gupta, Raghubir P. (Durham, NC)

1999-01-01

92

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

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.

Turk, Brian S. (Durham, NC); Gupta, Raghubir P. (Durham, NC)

2001-01-01

93

Morphology engineering of high performance binary oxide electrodes.  

PubMed

Advances in materials have preceded almost every major technological leap since the beginning of civilization. On the nanoscale and microscale, mastery over the morphology, size, and structure of a material enables control of its properties and enhancement of its usefulness for a given application, such as energy storage. In this review paper, our aim is to present a review of morphology engineering of high performance oxide electrode materials for electrochemical energy storage. We begin with the chemical bonding theory of single crystal growth to direct the growth of morphology-controllable materials. We then focus on the growth of various morphologies of binary oxides and their electrochemical performances for lithium ion batteries and supercapacitors. The morphology-performance relationships are elaborated by selecting examples in which there is already reasonable understanding for this relationship. Based on these comprehensive analyses, we proposed colloidal supercapacitor systems beyond morphology control on the basis of system- and ion-level design. We conclude this article with personal perspectives on the directions toward which future research in this field might take. PMID:25406718

Chen, Kunfeng; Sun, Congting; Xue, Dongfeng

2014-12-10

94

Pressure-Induced Electronic Phase Transitions Transition Metal Oxides and Rare Earth Metals  

E-print Network

Pressure-Induced Electronic Phase Transitions in Transition Metal Oxides and Rare Earth Metals Metal Oxides and Rare Earth Metals by Brian Ross Maddox Electron correlation can affect profound changes transition in a transition metal monoxide. iv #12;The lanthanides (the 4f metals also known as rare-earths

Islam, M. Saif

95

Synthesis and applications of metal oxide nanowires  

NASA Astrophysics Data System (ADS)

The one-dimensional nanostructured materials have attracted much attention because of their superior properties from the deducing size in the nanometer range. Among them, metal oxide materials provide a wide diversity and functionality in both theoretical study and applications. This work focused on the synthesis of metal oxide nanowires, and further investigated possible applications of nanostructured metal oxide materials. High quality ZnO nanowires have been synthesized by catalyst-assisted molecular beam epitaxy. The control of initial Au or Ag film thickness and subsequent annealing conditions is shown to provide an effective method for controlling the size and density of nucleation sites for catalyst-driven growth of ZnO nanowires. For gas sensing applications, it is found that the sensitivity for detecting hydrogen is greatly enhanced by sputter-depositing metal catalysts (Pt and Pt) on surface. The sensors are shown to detect ppm hydrogen at room temperature using <0.4 mW of power when using multiple nanowires. A comparison study of the hydrogen-sensing characteristics of ZnO thin films with different thickness and ZnO nanowires was studied. The Pt-coated single nanowires show a current response by approximately a factor of 3 larger at room temperature. Both types of sensors are shown to be capable of the detection of ppm hydrogen at room temperature with nW power levels, but the nanowires show different recovery characteristics, consistent with the expected higher surface coverage of adsorbed hydrogen. The feasibility of a number of metal oxide nanowires has been synthesized by a high-pressure assisted pulsed laser deposition. The high density well-aligned metal oxide nanowires can be directly grown on substrate without metal catalysts. The results suggest the possibility of growing complex metal oxide nanostructures, including tailored heterostructures and aligned heterojunction arrays with PLD technique. The growth of epitaxial SnO2 on c-sapphire using pulsed laser deposition is examined. X-ray diffraction analysis shows that the films are highly a-axis oriented SnO2 with the rutile structure. The effects of Ga doping on SnO2 films were studied. The Hall data showed p-type behavior occurs only at specific growth condition, but converted back to n-type and degraded as time proceeds.

Tien, Li-Chia

96

Complexity in Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

Recent computational results in the context of models for manganites and cuprates will be briefly discussed. It is argued that correlations in quenched disorder -- needed to mimic cooperative Jahn-Teller effects -- are important to have colossal magnetoresistance in 3D. A related recently discussed metal-insulator transition induced by disorder in a one-orbital model with cooperative phonons is intuitively explained [1]. In addition, it is argued that colossal effects should be far more common than currently known, and they may appear in cuprate superconductors as well [2]. [1] J. Burgy et al., cond-mat/0308456; C. Sen, G. Alvarez, and E. Dagotto, preprint. [2] See also Adriana Moreo, invited talk, March APS 04; G. Alvarez, M. Mayr et al., preprint.

Dagotto, Elbio; Alvarez, Gonzalo; Moreo, Adriana

2004-03-01

97

Transition metal oxide nanowires synthesized by heating metal substrates  

SciTech Connect

Highlights: {center_dot} This paper describes a simple and general method to synthesize 3d metal oxide nanowires. {center_dot} Self-catalysis growth mechanism was proposed to explain the growth of the nanowires. {center_dot} The temperature range for the growth of nanowires was estimated by taking into account the Gibbs free energy of reaction. {center_dot} This synthesis approach could be applied to synthesize other one-dimensional structures, such as FeSe and Bi{sub 2}Te{sub 3} nanowires. -- Abstract: Here we reported a simple method to synthesize transition metal oxide nanowires. Copper oxide (CuO), zinc oxide (ZnO), and cobalt oxide (Co{sub 3}O{sub 4}) nanowires were synthesized by heating the copper, zinc, and cobalt substrates under atmosphere condition. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the morphology and microstructure of the nanowires. According to our experimental results, self-catalysis growth mechanism was proposed to explain the growth of the nanowires. The temperature window for the growth of nanowires was estimated by taking into account the Gibbs free energy of reaction. The synthesis approach observed in our experiment could be applied to synthesize other one-dimensional structures, such as FeSe and Bi{sub 2}Te{sub 3} nanowires.

Yan, Hui; Sun, Yi [Department of Physics, Beijing Normal University, 100875 Beijing (China)] [Department of Physics, Beijing Normal University, 100875 Beijing (China); He, Lin, E-mail: helin@bnu.edu.cn [Department of Physics, Beijing Normal University, 100875 Beijing (China)] [Department of Physics, Beijing Normal University, 100875 Beijing (China); Nie, Jia-Cai [Department of Physics, Beijing Normal University, 100875 Beijing (China)] [Department of Physics, Beijing Normal University, 100875 Beijing (China)

2011-11-15

98

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Acrylated mixed metal oxides (generic). 721.10500 Section... § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance...identified generically as acrylated mixed metal oxides (PMN P-06-341) is subject to...

2013-07-01

99

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

...2014-07-01 false Acrylated mixed metal oxides (generic). 721.10500 Section... § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance...identified generically as acrylated mixed metal oxides (PMN P-06-341) is subject to...

2014-07-01

100

40 CFR 721.5548 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Mixed metal oxide (generic). 721.5548 Section 721...Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance...identified generically as a mixed metal oxide (PMN P-97-956) is subject to...

2010-07-01

101

40 CFR 721.5549 - Lithiated metal oxide.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Lithiated metal oxide. 721.5549 Section 721.5549 ...Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant...identified generically as lithiated metal oxide (LiNiO2 ) (PMN P-96-19;...

2011-07-01

102

40 CFR 721.10006 - Mixed metal oxide (generic).  

... 2014-07-01 false Mixed metal oxide (generic). 721.10006 Section 721...Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance...substance identified generically as mixed metal oxide (PMN P-99-511) is subject to...

2014-07-01

103

40 CFR 721.10006 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Mixed metal oxide (generic). 721.10006 Section 721...Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance...substance identified generically as mixed metal oxide (PMN P-99-511) is subject to...

2012-07-01

104

40 CFR 721.5548 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Mixed metal oxide (generic). 721.5548 Section 721...Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance...identified generically as a mixed metal oxide (PMN P-97-956) is subject to...

2013-07-01

105

"Metal-oxide gas sensors have been around for  

E-print Network

Publishing "Metal-oxide gas sensors have been around for over 40 years, but only now we have: Surface Studies of Gas Sensing Metal Oxides 21 February 2007 1. Could you explain the significance of your article to the non-specialist? Metal oxide-gas sensors are practical devices used in a variety of every

Diebold, Ulrike

106

40 CFR 721.5549 - Lithiated metal oxide.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Lithiated metal oxide. 721.5549 Section 721.5549 ...Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant...identified generically as lithiated metal oxide (LiNiO2 ) (PMN P-96-19;...

2012-07-01

107

40 CFR 721.5549 - Lithiated metal oxide.  

...2014-07-01 false Lithiated metal oxide. 721.5549 Section 721.5549 ...Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant...identified generically as lithiated metal oxide (LiNiO2 ) (PMN P-96-19;...

2014-07-01

108

40 CFR 721.5548 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Mixed metal oxide (generic). 721.5548 Section 721...Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance...identified generically as a mixed metal oxide (PMN P-97-956) is subject to...

2011-07-01

109

MATERIALS THEORY From transition metal oxides to cosmic strings  

E-print Network

MATERIALS THEORY From transition metal oxides to cosmic strings (and how electronic structure Transition metal oxides Thursday, September 20, 2012 6D-MATL / Materials Theory Compounds containing and competing interactions! Energy scale ~ 1eV #12;MATERIALS THEORY Where do transition metal oxides fit

110

Comparison of single and binary oxide MoO 3, TiO 2 and WO 3 sol–gel gas sensors  

Microsoft Academic Search

A systematic comparison of sol–gel prepared titanium dioxide (TiO2), WO3, and MoO3 single metal oxide based gas sensors was conducted. Process variables such as solution concentration, deposition parameters, gelling time, annealing time and temperature, remained constant. Sensors based on binary compound MoO3–TiO2 and MoO3–WO3 were also investigated to determine if the performance is superior to their single oxide constituents. The

K. Galatsis; Y. X. Li; W. Wlodarski; E Comini; G Sberveglieri; C Cantalini; S Santucci; M Passacantando

2002-01-01

111

DEVELOPMENTAL PHYTOTOXICITY OF METAL OXIDE NANOPARTICLES TO ARABIDOPSIS THALIANA  

E-print Network

Fe3O4), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). ThreeDEVELOPMENTAL PHYTOTOXICITY OF METAL OXIDE NANOPARTICLES TO ARABIDOPSIS THALIANA CHANG WOO LEE on the effects of four metal oxide nanoparticles, aluminum oxide (nAl2O3), silicon dioxide (nSiO2), magnetite (n

Alvarez, Pedro J.

112

Impact Dynamics of Oxidized Liquid Metal Drops  

E-print Network

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 the 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 $We^{\\star}$ is employed that uses an effective surface...

Xu, Qin; Jaeger, Heinrich M

2013-01-01

113

Binary-metal perovskites toward high-performance planar-heterojunction hybrid solar cells.  

PubMed

A simple, low temperature solution process for Pb/Sn binary-metal perovskite planar-heterojunction solar cells is demonstrated. Sn inclusion substantially influences the band-gap, crystallization kinetics, and thin-film formation leading to a broadened light absorption and enhanced film coverage on ITO/PEDOT:PSS. As a result, the optimized device shows a PCE exceeding 10%, which is the best result for binary-metal perovskite solar cells so far. PMID:25123496

Zuo, Fan; Williams, Spencer T; Liang, Po-Wei; Chueh, Chu-Chen; Liao, Chien-Yi; Jen, Alex K-Y

2014-10-01

114

Topological crystalline insulators in transition metal oxides.  

PubMed

Topological crystalline insulators possess electronic states protected by crystal symmetries, rather than time-reversal symmetry. We show that the transition metal oxides with heavy transition metals are able to support nontrivial band topology resulting from mirror symmetry of the lattice. As an example, we consider pyrochlore oxides of the form A2M2O7. As a function of spin-orbit coupling strength, we find two Z2 topological insulator phases can be distinguished from each other by their mirror Chern numbers, indicating a different topological crystalline insulators. We also derive an effective k·p Hamiltonian, similar to the model introduced for Pb(1-x)Sn(x)Te, and discuss the effect of an on-site Hubbard interaction on the topological crystalline insulator phase using slave-rotor mean-field theory, which predicts new classes of topological quantum spin liquids. PMID:25167290

Kargarian, Mehdi; Fiete, Gregory A

2013-04-12

115

Mesoscopically structured nanocrystalline metal oxide thin films  

NASA Astrophysics Data System (ADS)

This review describes the main successful strategies that are used to grow mesostructured nanocrystalline metal oxide and SiO2 films via deposition of sol-gel derived solutions. In addition to the typical physicochemical forces to be considered during crystallization, mesoporous thin films are also affected by the substrate-film relationship and the mesostructure. The substrate can influence the crystallization temperature and the obtained crystallographic orientation due to the interfacial energies and the lattice mismatch. The mesostructure can influence the crystallite orientation, and affects nucleation and growth behavior due to the wall thickness and pore curvature. Three main methods are presented and discussed: templated mesoporosity followed by thermally induced crystallization, mesostructuration of already crystallized metal oxide nanobuilding units and substrate-directed crystallization with an emphasis on very recent results concerning epitaxially grown piezoelectric structured ?-quartz films via crystallization of amorphous structured SiO2 thin films.

Carretero-Genevrier, Adrian; Drisko, Glenna L.; Grosso, David; Boissiere, Cédric; Sanchez, Clement

2014-11-01

116

A CCD imaging search for wide metal-poor binaries  

NASA Astrophysics Data System (ADS)

We explored the regions within a radius of 25 arcsec around 473 nearby, low-metallicity G- to M-type stars using (VR)I optical filters and small-aperture telescopes. About 10% of the sample was searched up to angular separations of 90 arcsec. We applied photometric and astrometric techniques to detect true physical companions to the targets. The great majority of the sample stars was drawn from the Carney-Latham surveys; their metallicities range from roughly solar to [Fe/H] = -3.5 dex. Our I-band photometric survey detected objects that are between 0 and 5 mag fainter (completeness) than the target stars; the maximum dynamical range of our exploration is 9 mag. We also investigated the literature, and inspected images from the Digitized Sky Surveys to complete our search. By combining photometric and proper motion measurements, we retrieved 29 previously known companions, and identified 13 new proper motion companions. Near-infrared 2MASS photometry is provided for the great majority of them. Low-resolution optical spectroscopy (386-1000 nm) was obtained for eight of the new companion stars. These spectroscopic data confirm them as cool, late-type, metal-depleted dwarfs, with spectral classes from esdK7 to sdM3. After comparison with low-metallicity evolutionary models, we estimate the masses of the proper motion companion stars to be in the range 0.5-0.1 M?. They are moving around their primary stars at projected separations between ˜32 and ˜57 000 AU. These orbital sizes are very similar to those of solar-metallicity stars of the same spectral types. Our results indicate that about 15% of the metal-poor stars have stellar companions in wide orbits, which is in agreement with the binary fraction observed among main sequence G- to M-type stars and T Tauri stars. Based on observations made with the IAC80 telescope operated on the island of Tenerife by the Instituto de Astrofísica de Canarias in the Spanish Observatorio del Teide; also based on observations made with the 2.2 m telescope of the German-Spanish Calar Alto Observatory (Almería, Spain), the William Herschel Telescope (WHT) operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos (ORM) of the Instituto de Astrofísica de Canarias; and the Telescopio Nazionale Galileo (TNG) at the ORM. The complete Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/419/167

Zapatero Osorio, M. R.; Martín, E. L.

2004-05-01

117

Metal oxide semiconductor NO 2 sensor  

Microsoft Academic Search

A newly developed sensor for NO2 has been investigated from a practical point of view. Various metal oxide semiconductors have been examined and as a result it is found that WO3 shows the highest potentiality as an NO2 sensor for air-quality monitoring. Several approaches, such as introducing SiO2 binder, microprocessing techniques, heat-cleaning techniques and adopting a filter material, have been

Tomohiro Inoue; Kazuyuki Ohtsuka; Yutaka Yoshida; Yoshinobu Matsuura; Yoshihisa Kajiyama

1995-01-01

118

Removal of nickel and zinc from single and binary metal solutions by Sargassum angustifolium.  

PubMed

The capability of Sargassum angustifolium in removing nickel (Ni) (II) and zinc (Zn) (II) from single and binary metal solution was determined. In binary solution the presence of the secondary metal inhibited the sorption of the primary metal by S. angustifolium but the inhibitory effect of Ni during sorption of Zn is stronger than the inhibitory effect of Zn in absorption of Ni. The total metal (Ni + Zn) sorbed from the binary metal solution by S. angustifolium cells always remained lower than the total sorption of individual metals from their respective single metal solutions, thereby suggesting competition between Ni(II) and Zn(II) for the common binding sites on S. angustifolium. The maximum uptake capacities of the S. angustifolium, which was collected near Bushehr, Persian Gulf, Iran in the natural form, at the optimal conditions for Ni(II) and Zn(II) ions in single metal solutions were approximately 0.71 and 0.93 mmol/g dry S. angustifolium, respectively. Under the binary system Ni(II) and Zn(II) uptake capacities were 0.41 mmol Ni/g and 0.36 mmol Zn/g, respectively. Better fitness of equilibrium metal sorption data to the Langmuir than the Freundlich model suggests multilayer adsorption of test metals onto the cell surface. PMID:24056438

Ahmady-Asbchin, Salman; Jafari, Naser

2013-01-01

119

Electrolysis of water on (oxidized) metal surfaces  

NASA Astrophysics Data System (ADS)

Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias directly from the electronic structure calculations. We consider electrodes of Pt(1 1 1) and Au(1 1 1) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear relations are assumed to be obeyed exactly, this leads to a universal relationship between the catalytic rate and the oxygen binding energy. Finally, we conclude that for systems obeying these relations, there is a limit to how good a water splitting catalyst an oxidized metal surface can become.

Rossmeisl, J.; Logadottir, A.; Nørskov, J. K.

2005-12-01

120

Method for producing metal oxide aerogels  

DOEpatents

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.

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

1995-04-25

121

Method for producing metal oxide aerogels  

DOEpatents

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.

Tillotson, Thomas M. (Tracy, CA); Poco, John F. (Livermore, CA); Hrubesh, Lawrence W. (Pleasanton, CA); Thomas, Ian M. (Livermore, CA)

1995-01-01

122

Analytical modeling of stress and strain of symmetrically oxidized metal  

NASA Astrophysics Data System (ADS)

During high temperature isothermal oxidation, a plane of oxide molecules is inserted in each oxide grain boundary. These oxide scales grow laterally and thicken in a columnar microstructure to generate a lateral growth strain. But as the oxide scales are constrained by the underlying metal, the metal constraint produces a net in plane compressive stress in the oxide scales. To balance a compressive stress in the oxide scales, a net in plane tensile stress is generated in the metal, which results creep elongation of an oxide/metal composite. Based on this mechanism, the present paper provides a simplified modeling approach to predict an evolution of the stresses and strains in the oxide/metal composite considering the lateral growth strain of the oxide and creep strain of the metal and oxide. Oxide stress variation due to the creep properties of the oxide/metal composite such as creep indexes (m and n) and creep constants (Aox and Am) is provided for the notional mechanical properties. Oxide stress variation due to the lateral growth constant Dox and oxide kinetics parabolic constant kp is also discussed. Finally, the modeling results are compared with the experimental results obtained for FeCrALY and Ni alloy to highlight the importance of the proposed modeling.

Maharjan, S.; Zhang, X. C.; Wang, Z. D.

2012-08-01

123

Biomarker sensing using nanostructured metal oxide sensors  

NASA Astrophysics Data System (ADS)

Resistive Chemical sensors are those gas sensitive materials, typically semiconducting metal oxides, that change their electrical properties in response to a change in the ambient. The key features of a chemosensor are sensitivity, selectivity, response time and sensor stability. The hypothesis of this work is that, since metal oxides are polymorphic compounds, the crystal structure of the specific polymorph determines the relative gas selectivity of the material; also that the morphology of the sensing element determines the gas sensitivity limit. This work focuses on the synthesis of nanostructured metal oxides for chemosensors used in selective 'biomarker' detection. Biomarkers are chemical compounds, products of human metabolism which act as specific disease markers. The biomarkers studied in this work include NO, isoprene, NH3, ethanol and acetone which can all be found in exhaled human breath and which allow the non-invasive detection of a range of diseases. Sensors based on three different metal oxides-MoO3, WO 3, and TiO2 were fabricated using sol-gel, electrospinning and spray pyrolysis techniques and tested both as single elements and in an array configuration (electronic nose). The effects of the processing method used, grain size and shape and crystal phase of the material produced, and temperature effects of postsynthesis processing and sensing have been evaluated. Structural characterization has been carried out using X-Ray Diffraction, Scanning and High Resolution Transmission Electron Microscopy, while spectroscopic measurements using XPS, Raman and In-situ FTIR provide valuable information about the surface-analyte interactions. This work has shown that the use of monoclinic polymorph of WO3 yields a selective response to NO, while the other phase of the same oxide give a non-selective chemical response. The orthorhombic phase of MoO 3 exhibits specificity to NH3. An explanation for the variable sensing properties is given based on the gas interactions with the given polymorph involving adsorption/reaction processes. Another major finding of this work is that there was orders of magnitude increase in gas sensitivity when high aspect ratio nanowires as opposed to nanoparticles of the same diameter were used.

Kalyanasundaram, Krithika

124

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

PubMed

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. PMID:25681933

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

2015-02-14

125

Process for Producing Metal Compounds From Graphite Oxide  

NASA Technical Reports Server (NTRS)

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 fiber 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.

Hung, Ching-Cheh (Inventor)

2000-01-01

126

Process for Producing Metal Compounds from Graphite Oxide  

NASA Technical Reports Server (NTRS)

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.

Hung, Ching-Cheh (Inventor)

2000-01-01

127

Process for producing metal compounds from graphite oxide  

NASA Technical Reports Server (NTRS)

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.

Hung, Ching-Cheh (Inventor)

2000-01-01

128

Polymer-assisted aqueous deposition of metal oxide films  

DOEpatents

An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

Li, DeQuan (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

2003-07-08

129

Direct comparison of the electrical properties in metal\\/oxide\\/nitride\\/oxide\\/silicon and metal\\/aluminum oxide\\/nitride\\/oxide\\/silicon capacitors with equivalent oxide thicknesses  

Microsoft Academic Search

We examine the electrical properties of metal\\/oxide\\/nitride\\/oxide\\/silicon (MONOS) capacitors with two different blocking oxides, SiO2 and Al2O3, under the influence of the same electric field. The thickness of the Al2O3 layer is set to 150 Å, which is electrically equivalent to a thickness of the SiO2 layer of 65 Å, in the MONOS structure for this purpose. The capacitor with the Al2O3

Ho-Myoung An; Yu Jeong Seo; Hee Dong Kim; Kyoung Chan Kim; Jong-Guk Kim; Won-Ju Cho; Jung-Hyuk Koh; Yun Mo Sung; Tae Geun Kim

2009-01-01

130

Chemical Sensors Based on Metal Oxide Nanostructures  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

131

Metallic oxide switches using thick film technology  

NASA Technical Reports Server (NTRS)

Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

Patel, D. N.; Williams, L., Jr.

1974-01-01

132

Magnetic correlations in doped transition metal oxides  

SciTech Connect

The authors review recent reactor- and spallation-source-based neutron scattering experiments on the magnetic fluctuations and order in a variety of doped transition metal oxides. In particular, data are shown for the NiO chain compound, Y{sub 2{minus}x}Ca{sub x}BaNiO{sub 5}, the two-dimensional cuprate superconductors La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3} O{sub 6+x}, and the classical three-dimensional ``Mott-Hubbard`` system V{sub 2{minus}y}O{sub 3}.

Aeppli, G. [AT and T Bell Labs., Murray Hill, NJ (United States); Bao, W.; Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States)] [and others

1995-02-15

133

Metal oxide membranes for gas separation  

DOEpatents

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.

Anderson, Marc A. (Madison, WI); Webster, Elizabeth T. (Madison, WI); Xu, Qunyin (Plainsboro, NJ)

1994-01-01

134

Metal oxide membranes for gas separation  

DOEpatents

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.

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

1994-08-30

135

The interactions between transition metal nanoparticles and their metal-oxide supports are often critical for heterogeneous metal nanoparticle  

E-print Network

are often critical for heterogeneous metal nanoparticle catalysts (1). However, the roles of the speciesReports The interactions between transition metal nanoparticles and their metal- oxide supports at the metal-support interface is widely regarded as the key step in room-temperature CO oxidation (13

Napp, Nils

136

Impacts of metal and metal oxide nanoparticles on marine organisms.  

PubMed

Increasing use of metal and metal oxide nanoparticles [Me(O)NPs] in products means many will inevitably find their way into marine systems. Their likely fate here is sedimentation following hetero-aggregation with natural organic matter and/or free anions, putting benthic, sediment-dwelling and filter feeding organisms most at risk. In marine systems, Me(O)NPs can absorb to micro-organisms with potential for trophic transfer following consumption. Filter feeders, especially bivalves, accumulate Me(O)NPs through trapping them in mucus prior to ingestion. Benthic in-fauna may directly ingest sedimented Me(O)NPs. In fish, uptake is principally via the gut following drinking, whilst Me(O)NPs caught in gill mucus may affect respiratory processes and ion transport. Currently, environmentally-realistic Me(O)NP concentrations are unlikely to cause significant adverse acute health problems, however sub-lethal effects e.g. oxidative stresses have been noted in many organisms, often deriving from dissolution of Ag, Cu or Zn ions, and this could result in chronic health impacts. PMID:24359692

Baker, Tony J; Tyler, Charles R; Galloway, Tamara S

2014-03-01

137

Near room temperature lithographically processed metal-oxide transistors  

E-print Network

A fully lithographic process at near-room-temperature was developed for the purpose of fabricating transistors based on metal-oxide channel materials. The combination of indium tin oxide (ITO) as the source/drain electrodes, ...

Tang, Hui, M. Eng. Massachusetts Institute of Technology

2008-01-01

138

Surface Oxidation and Dissolution of Metal Nanocatalysts in Acid Medium  

E-print Network

the main features of the oxidation phenomena observed experimentally, it is concluded that the dissolution mechanism of metal atoms involves: 1) Surface segregation of alloy atoms, 2) oxygen absorption into the subsurface of the catalyst, and 3) metal...

Callejas-Tovar, Juan

2012-10-19

139

REACTIVITY OF FORMULATED METAL OXIDE SORBENTS WITH HOT HYDROGEN SULFIDE  

Microsoft Academic Search

Three metal oxide sorbents, labeled TU-19, TU-24, and TU-25 were formulated with zinc oxide powder as an active sorbent ingredient, bentonite as a binding material, and titanium oxide as a supporting metal oxide. Equilibrium absorption of H2S into sorbents increases with concentrations of H2S. Reactivity of sorbents increases with increased reaction temperatures. Reaction rates of H2S with the sorbent increase

Kyung C. Kwon; Sammaiah Pallerla; Roy Sanjeev; Susan K. Joines; Charles Komar

2001-01-01

140

Effect of double oxide layer on metal–glass sealing  

Microsoft Academic Search

One of the main requirements of a metal–glass sealing is hermeticity along with mechanical strength of the metal–glass bond. For this purpose, the thermal expansion coefficient of the metal needs to be as close as possible to the glass expansion coefficient to limit stress development in the glass. Second, an oxide layer should be developed on the metal surface that

Marc Mantel

2000-01-01

141

Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials  

SciTech Connect

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.

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

2003-11-18

142

Fluidized reduction of oxides on fine metal powders without sintering  

NASA Technical Reports Server (NTRS)

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.

Hayashi, T.

1985-01-01

143

Method of producing solution-derived metal oxide thin films  

DOEpatents

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.

Boyle, Timothy J. (Albuquerque, NM); Ingersoll, David (Albuquerque, NM)

2000-01-01

144

Structure, adhesion, and stability of metal/oxide and oxide/oxide interfaces  

SciTech Connect

Studies of several model metal/oxide and oxide/oxide interfaces were carried out by depositing ultra-thin metal thins on single crystal oxide substrates. The specific systems that were characterized include K/TiO{sub 2}, K{sub 2}O/TiO{sub 2}, Al/TiO{sub 2}, Al{sub 2}O{sub 3}/TiO{sub 2}, and K/NiO. The interface electronic structure and bonding interactions were determined with x-ray and uv photoelectron spectroscopies (XPS and UPS) and the structure and morphology was analyzed with low energy and high energy electron diffraction (LEED and RHEED) and atomic force microscopy (AFM). The two metal overlayers studies, K and Al, were found to strongly interact with the single crystal oxide substrates. Given adequate thermal energy, the metals became oxidized and substoichiometric TiO{sub 2} and NiO compositions were created near the interface. Defects were found to have a major influence on interface structure. The construction of the thin film deposition/RHEED analysis chamber was completed during the past year, and a versatile sample transfer and heating system was implemented. Three graduate students participated in the project, the results were presented at three national meetings, and one manuscript was submitted for publication.

Lad, R.J.

1992-01-01

145

Alkane activation on crystalline metal oxide surfaces.  

PubMed

Advances in the fundamental understanding of alkane activation on oxide surfaces are essential for developing new catalysts that efficiently and selectively promote chemical transformations of alkanes. In this tutorial review, we discuss the current understanding of alkane activation on crystalline metal oxide surfaces, and focus mainly on summarizing our findings on alkane adsorption and C-H bond cleavage on the PdO(101) surface as determined from model ultrahigh vacuum experiments and theoretical calculations. These studies show that alkanes form strongly-bound ?-complexes on PdO(101) by datively bonding with coordinatively-unsaturated Pd atoms and that these molecularly adsorbed species serve as precursors for C-H bond activation on the oxide surface. In addition to discussing the binding and properties of alkane ?-complexes on PdO(101), we also summarize recent advances in kinetic models to predict alkane dissociation rates on solid surfaces. Lastly, we highlight computations which predict that the formation and facile C-H bond activation of alkane ?-complexes also occurs on RuO2 and IrO2 surfaces. PMID:24480977

Weaver, Jason F; Hakanoglu, Can; Antony, Abbin; Asthagiri, Aravind

2014-11-21

146

Microwave properties of thermochromic metal oxide surfaces  

NASA Astrophysics Data System (ADS)

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.

Ousbäck, Jan-Olof; Kariis, Hans

2006-09-01

147

In situ oxidation of zirconium binary alloys by environmental SEM and analysis by AFM, FIB, and TEM  

NASA Astrophysics Data System (ADS)

Binary Zr-alloys containing 1%Fe and 1% Ni (large precipitates) and 1% Cr and 0.6% Nb (small precipitates), as well as a pure Zr sample were exposed in situ at 130 Pa water vapour pressure at 415 °C in an environmental SEM. The surface topography and composition of each sample was characterised before in situ experiments, during and after oxidation. After oxidation the surface was characterised by SEM and EDS, AFM and TEM combined with EDS. Focused ion beam was used to prepare cross sections of the metal-oxide interface and for the preparation of TEM thin foils. The oxidation behaviour of precipitates for these alloying elements can be characterised into two large families, those which show a rapid oxidation and those which induce a delayed oxidation in comparison with the Zr-matrix. At 415 °C after 1 h of oxidation for Zr1%Fe and Zr1%Ni, the formation of protrusions could be detected at the surface, being related to underlying SPP in the oxide. On Zr1%Cr and Zr0.6%Nb unoxidised SPPs were observed in the oxide, close to the metal-oxide interface. These SPPs were, however, oxidised close to the outer surface of the oxide. The surface roughness was increased for all materials after in situ oxidation, however, only for Zr1%Fe and Zr1%Ni protrusions appeared on the surface during oxidation. It was subsequently demonstrated that these latter correspond to the position of SPPs. For Zr1%Fe the surface roughness increased more than in the other materials and on these protrusions small iron oxide crystals have been observed at the surface. These observations confirm that Fe has a different behaviour compared to the other SPP forming elements, and it diffuses out to the free surface of the material. These alloying elements being the constituents of the commercial alloys (Fe and Cr for Zircaloy-4; Fe, Cr and Ni for Zircaloy-2 and Nb for all Nb-containing alloys), this study allows to separate their individual influence and can allow a subsequent comparison to the behaviour of those more complex alloys.

Proff, C.; Abolhassani, S.; Dadras, M. M.; Lemaignan, C.

2010-09-01

148

Synthesis of Metallic Iridium Oxide Nanowires via Metal Organic Chemical Vapor Deposition Fengyan ZHANG  

E-print Network

Synthesis of Metallic Iridium Oxide Nanowires via Metal Organic Chemical Vapor Deposition Fengyan, U.S.A. (Received December 9, 2004; accepted February 3, 2005; published March 4, 2005) Iridium oxide) iridium (I) as the precursor on Si or SiO2 substrate with and without metal nanoparticles as catalysts

Wang, Deli

149

Synthesis of nanostructured manganese oxides from a dipolar binary liquid (water\\/benzene) system and hydrogen storage ability research  

Microsoft Academic Search

A new dipolar binary liquid strategy has been developed to manganese oxide nanostructure’s synthesis, in which different manganese oxide nanostructures have been easily obtained without using any templates or catalysts. It has been found that the reaction temperatures, alkali precipitators’ concentrations and Mn2+ concentrations play a significant role in our dipolar binary liquid technique. This novel approach can be potentially

Hai Men; Peng Gao; Yuzeng Sun; Yujin Chen; Xiaona Wang; Longqiang Wang

2010-01-01

150

Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*)  

E-print Network

707 Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*) IBM T.J. Watson of an ordered or disordered noble metal (Ag, Au) monolayer on the Si(111) surface has a great influence on the growth mode ofmetal atoms and the oxidation ofthe silicon surface atoms. These phenomena are discussed

Paris-Sud XI, Université de

151

Preparation of bioactive titanium metal via anodic oxidation treatment  

Microsoft Academic Search

Titania with specific structures of anatase and rutile was found to induce apatite formation in vitro. In this study, anodic oxidation in H2SO4 solution, which could form anatase and rutile on titanium metal surface by conditioning the process, was employed to modify the structure and bioactivity of biomedical titanium. After the titanium metal was subjected to anodic oxidation treatment, thin

Bangcheng Yang; Masaiki Uchida; Hyun-Min Kim; Xingdong Zhang; Tadashi Kokubo

2004-01-01

152

Laser-assisted formation of metallic oxide microtubes  

SciTech Connect

The fabrication of metallic oxide microtubes is possible directly, without any support structure, by continuous wave infrared laser-assisted oxidation of the metal in air. The particular case presented is the growth of tube-like vanadium pentoxide microcrystals grown in our laboratories. {copyright} {ital 1997 Materials Research Society.}

Nanai, L. [Department of Experimental Physics, Jozsef Attila University, H-6720 Szeged (Hungary); George, T.F. [Office of the Chancellor/Departments of Chemistry and Physics Astronomy, University of Wisconsin--Stevens Point, Stevens Point, Wisconsin 54481-3897 (United States)

1997-01-01

153

Detection of chemical warfare agents using nanostructured metal oxide sensors  

Microsoft Academic Search

The feasibility of thick-film chemical sensors based on various semiconductor metal oxides to reliably detect chemical warfare agents has been studied. Nanocrystalline semiconductor metal oxide (SMO) powders were used as initial materials for the sensors’ fabrication. The thick films were prepared using a simple drop-coating technique accompanied with in situ annealing of the deposited films by a heater that is

Alexey A. Tomchenko; Gregory P. Harmer; Brent T. Marquis

2005-01-01

154

Nanoionic switching in metal oxide nanostructures  

NASA Astrophysics Data System (ADS)

Ion migration in oxide nanostructures is a key process in information storage technologies, where the logic data are stored as nanoscale conductive filaments [1]. Due to the inherently nanoscale size of the ionic switching location (few cubic nanometers), the local electric field and current density induce extremely high temperatures as a result of Joule heating [2,3]. To develop and design advanced nanoionic materials and devices with improved performance and reliability, the ion migration phenomena in metal oxides must be carefully understood and modeled. This talk will address the modeling of ionic migration and the consequent switching in HfOx layers of RRAM devices [4]. The model solves drift/diffusion equations for thermally-activated hopping of positive ion, such as oxygen vacancies (VO^+) and metal cations (Hf^+), in presence of intense Joule heating and electric field. The impact of the ion distribution on the local conductivity is described physics-based models of defect-assisted electronic conduction in semiconductors [5,6]. Microscopic parameters, such as the energy barrier for ion hopping, are directly inferred from the experimental switching kinetics at variable voltages. The simulation results picture the filament growth/depletion with time and account for the observed switching characteristics, such as the progressive opening of a depleted gap and the possibility of electrode-to-electrode migration of ions. Finally, new phenomena, such as switching variability at atomic-size filaments and stress-induced symmetric switching, will be discussed.[4pt] [1] R. Waser, et al., Adv. Mater. 21, 2632 (2009).[0pt] [2] D. Ielmini, et al., Nanotechnology 22, 254022 (2011).[0pt] [3] S. Menzel, et al., Adv. Funct. Mater. 21, 4487 (2011).[0pt] [4] S. Larentis, et al., IEEE Trans. Electron Devices 59, 2468 (2012).[0pt] [5] H. D. Lee, et al., Phys. Rev. B 81, 193202 (2010).[0pt] [6] D. Ielmini, Phys. Rev. B 78, 035308 (2008).

Ielmini, Daniele

2013-03-01

155

Conductive metal oxide film and method of making  

DOEpatents

The present invention is a method for reducing a dopant in a film of a metal oxide wherein the dopant is reduced and the first metal oxide is substantially not reduced. The method of the present invention relies upon exposing the film to reducing conditions for a predetermined time and reducing a valence of the metal from a positive valence to a zero valence and maintaining atoms with a zero valence in an atomic configuration within the lattice structure of the metal oxide. According to the present invention, exposure to reducing conditions may be achieved electrochemically or achieved in an elevated temperature gas phase.

Windisch, Jr., Charles F. (Kennewick, WA); Exarhos, Gregory J. (Richland, WA)

1999-01-01

156

Metal oxide porous ceramic membranes with small pore sizes  

DOEpatents

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.

Anderson, Marc A. (Madison, WI); Xu, Qunyin (Madison, WI)

1992-01-01

157

Metal oxide porous ceramic membranes with small pore sizes  

DOEpatents

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.

Anderson, Marc A. (Madison, WI); Xu, Qunyin (Madison, WI)

1991-01-01

158

Solder for oxide layer-building metals and alloys  

DOEpatents

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.

Kronberg, J.W.

1992-09-15

159

Laboratory studies of refractory metal oxide smokes  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

160

Oxidized film structure and method of making epitaxial metal oxide structure  

DOEpatents

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.

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

2003-02-25

161

Binary behaviour of an oxidation-responsive MRI nano contrast agent.  

PubMed

A new nano contrast agent has been prepared incorporating a molecular magnet in oxidation-responsive nanoparticles; this system has shown a remarkable sensitivity to hydrogen peroxide (detection down to at least 40 ?M), which was used as a model reactive oxygen species. Surprisingly, the response had a binary (off/on) character, due to a non-linear cascade relation between extent of oxidation and water permeability in the particles. PMID:25447319

Jeanmaire, Damien; Timco, Grigore A; Gennari, Arianna; Sproules, Stephen; Williams, Kaye J; Winpenny, Richard E P; Tirelli, Nicola

2015-01-21

162

Synthesis and characterization of nanostructure hydrous iron–titanium binary mixed oxide for arsenic sorption  

Microsoft Academic Search

Synthesis of nanostructure hydrous iron–titanium binary mixed oxide (NHITBMO) had been reported by a simple method, and characterized\\u000a by the X-ray diffraction (XRD), thermal analysis, transmission electron microscope (TEM), Föurier Transform Infrared (FTIR),\\u000a surface area, and zero surface charge pH (pHzpc). The synthetic oxide was hydrated and microcrystalline with 77.8 m2 g?1 BET surface area. The particle size (nm) calculated using XRD

Kaushik Gupta; Shyamal Saha; Uday Chand Ghosh

2008-01-01

163

Observation and prediction of first phase formation in binary Cu-metal thin films  

NASA Astrophysics Data System (ADS)

First phase formation has been determined in Cu binary thin film systems with Ti, Zr, Mg, Sb, Pd, and Pt using transmission electron microscopy and Rutherford backscattering spectrometry. CuTi, CuZr, CuMg2, Cu2Sb, Cu3Pd, and Cu3Pt are the first phases to form upon annealing the Cu/metal bilayers. The effective heat of formation model is used to predict first phase formation in 14 Cu/metal systems.

Li, Jian; Strane, J. W.; Russell, S. W.; Hong, S. Q.; Mayer, J. W.; Marais, T. K.; Theron, C. C.; Pretorius, R.

1992-10-01

164

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

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

165

40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).  

...acrylate reaction products with mixed metal oxides (generic). 721.10574 Section...acrylate reaction products with mixed metal oxides (generic). (a) Chemical substance...acrylate reaction products with mixed metal oxides (PMN P-09-48) is subject...

2014-07-01

166

40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

...alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section...alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance...alkoxysilylalkane ester and mixed metal oxides (PMN P-07-198) is subject to...

2013-07-01

167

40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).  

...alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section...alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical...alkoxysilylalkane ester and mixed metal oxides (PMN P-07-198) is...

2014-07-01

168

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).  

...2014-07-01 2014-07-01 false Metal oxide, modified with alkyl and vinyl...Chemical Substances § 721.10044 Metal oxide, modified with alkyl and vinyl...substance identified generically as metal oxide, modified with alkyl and...

2014-07-01

169

40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).  

Code of Federal Regulations, 2012 CFR

...alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section...alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical...alkoxysilylalkane ester and mixed metal oxides (PMN P-07-198) is...

2012-07-01

170

40 CFR 721.10574 - Alkylcarboxy polyester acrylate reaction products with mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

...acrylate reaction products with mixed metal oxides (generic). 721.10574 Section...acrylate reaction products with mixed metal oxides (generic). (a) Chemical...acrylate reaction products with mixed metal oxides (PMN P-09-48) is...

2013-07-01

171

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Metal oxide, modified with alkyl and vinyl...Chemical Substances § 721.10044 Metal oxide, modified with alkyl and vinyl...substance identified generically as metal oxide, modified with alkyl and...

2013-07-01

172

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).  

Code of Federal Regulations, 2013 CFR

... false Nickel, cobalt mixed metal oxide (generic). 721.5315 Section...5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical...generically as nickel, cobalt mixed metal oxide. (PMN P-02-90) is...

2013-07-01

173

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).  

... false Nickel, cobalt mixed metal oxide (generic). 721.5315 Section...5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical...generically as nickel, cobalt mixed metal oxide. (PMN P-02-90) is...

2014-07-01

174

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Metal oxide, modified with alkyl and vinyl...Chemical Substances § 721.10044 Metal oxide, modified with alkyl and vinyl...substance identified generically as metal oxide, modified with alkyl and...

2012-07-01

175

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Nickel, cobalt mixed metal oxide (generic). 721...Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). ...substance identified generically as nickel, cobalt mixed metal oxide. (PMN...

2010-07-01

176

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Nickel, cobalt mixed metal oxide (generic). 721...Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). ...substance identified generically as nickel, cobalt mixed metal oxide. (PMN...

2011-07-01

177

Oxidation energies of transition metal oxides within the GGA+U framework Lei Wang, Thomas Maxisch, and Gerbrand Ceder*  

E-print Network

Oxidation energies of transition metal oxides within the GGA+U framework Lei Wang, Thomas Maxisch; published 4 May 2006 The energy of a large number of oxidation reactions of 3d transition metal oxides be corrected by fitting the formation enthalpy of simple nontransition metal oxides. Removal of the O2 binding

Ceder, Gerbrand

178

Enhanced Half-Metallicity in Edge-Oxidized Zigzag Graphene  

E-print Network

Enhanced Half-Metallicity in Edge-Oxidized Zigzag Graphene Nanoribbons Oded Hod,* Vero´nica Barone theoretical study of the electronic properties and relative stabilities of edge-oxidized zigzag graphene nanoribbons. The oxidation schemes considered include hydroxyl, lactone, ketone, and ether groups. Using

Hod, Oded

179

Redox switching and oxygen evolution at oxidized metal and metal oxide electrodes: iron in base.  

PubMed

Outstanding issues regarding the film formation, redox switching characteristics and the oxygen evolution reaction (OER) electrocatalytic behaviour of multicycled iron oxyhydroxide films in aqueous alkaline solution have been revisited. The oxide is grown using a repetitive potential multicycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasised. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mV dec(-1) and ca. 120 mV dec(-1) are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity changes from ca. 3/2 to ca. 1 as the potential is increased. These observations are rationalised in terms of a kinetic scheme involving Temkin adsorption and the rate determining formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the potential dependence of the surface coverage of adsorbed intermediates. PMID:22068318

Lyons, Michael E G; Doyle, Richard L; Brandon, Michael P

2011-12-28

180

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

DOEpatents

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.

Poston, J.A.

1997-12-02

181

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

DOEpatents

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.

Poston, James A. (Star City, WV)

1997-01-01

182

Stabilization of Electrocatalytic Metal Nanoparticles at Metal-Metal Oxide-Graphene Triple Junction Points  

SciTech Connect

Carbon-supported metal catalysts are widely used in heterogeneous catalysis and electrocatalysis. In this paper, we report a novel method to deposit metal catalysts and metal oxide nanoparticles on two-dimensional graphene sheets to improve the catalytic performance and stability of the catalyst materials. The new synthesis method allows indium tin oxide (ITO) nanocrystals to be directly grown on functionalized graphene sheets forming the ITO-graphene hybrids. Pt nanoparticles are then deposited to form a special triple-junction structure (Pt-ITO-graphene). Both experimental study and periodic density functional theory calculations show that the supported Pt nanoparticles are stable at Pt-ITO-graphene triple junction points. The new catalyst materials were tested for oxygen reduction for potential applications in polymer electrolyte membrane fuel cells, and they exhibited greatly enhanced stability and activity. The reasons for the high stability and activity of Pt-ITO-graphene are analyzed.

Kou, Rong; Shao, Yuyan; Mei, Donghai; Nie, Zimin; Wang, Donghai; Wang, Chong M.; Viswanathan, Vilayanur V.; Park, Seh K.; Aksay, Ilhan A.; Lin, Yuehe; Wang, Yong; Liu, Jun

2011-03-02

183

Route to transition metal carbide nanoparticles through cyanamide and metal oxides  

SciTech Connect

We have designed an efficient route to the synthesis of transition metal carbide nanoparticles starting from an organic reagent cyanamide and transition metal oxides. Four technologically important metal carbide nanoparticles such as tungsten carbide, niobium carbide, tantalum carbide and vanadium carbide were synthesized successfully at moderate temperatures. It is found that cyanamide is an efficient carburization reagent and that the metal oxides are completely transmitted into the corresponding carbide nanoparticles. A possible mechanism is proposed to explain the results of the reaction between cyanamide and the metal oxides.

Li, P.G. [Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018 (China)], E-mail: peigangiphy@yahoo.com.cn; Lei, M.; Tang, W.H. [Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018 (China)

2008-12-01

184

Formation of metal oxides by cathodic arc deposition  

SciTech Connect

Metal oxide thin films are of interest for a number of applications. Cathodic arc deposition, an established, industrially applied technique for formation of nitrides (e.g. TiN), can also be used for metal oxide thin film formation. A cathodic arc plasma source with desired cathode material is operated in an oxygen atmosphere, and metal oxides of various stoichiometric composition can be formed on different substrates. We report here on a series of experiments on metal oxide formation by cathodic arc deposition for different applications. Black copper oxide has been deposited on ALS components to increase the radiative heat transfer between the parts. Various metal oxides such as tungsten oxide, niobium oxide, nickel oxide and vanadium oxide have been deposited on ITO glass to form electrochromic films for window applications. Tantalum oxide films are of interest for replacing polymer electrolytes. Optical waveguide structures can be formed by refractive index variation using oxide multilayers. We have synthesized multilayers of Al{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/AI{sub 2}O{sub 3}/Si as possible basic structures for passive optoelectronic integrated circuits, and Al{sub 2-x}Er{sub x}O{sub 3} thin films with a variable Er concentration which is a potential component layer for the production of active optoelectronic integrated devices such as amplifiers or lasers at a wavelength of 1.53 {mu}m. Aluminum and chromium oxide films have been deposited on a number of substrates to impart improved corrosion resistance at high temperature. Titanium sub-oxides which are electrically conductive and corrosion resistant and stable in a number of aggressive environments have been deposited on various substrates. These sub-oxides are of great interest for use in electrochemical cells.

Anders, S.; Anders, A.; Rubin, M.; Wang, Z.; Raoux, S.; Kong, F.; Brown, I.G.

1995-03-01

185

Development of a regenerable metal oxide CO removal system  

NASA Technical Reports Server (NTRS)

A regenerable metal oxide carbon dioxide (CO2) removal system was developed to replace the current means of a nonreusable chemical, lithium hydroxide, for removing the metabolic CO2 of an astronaut in a space suit. Testing indicates that a viable low-volume metal oxide concept can be used in the portable life support system for CO2 removal during Space Station extravehicular activity (EVA). A canister of nearly the same volume as that used for the Space Shuttle, containing 0.10 cu ft of silver-oxide-based pellets, was tested; test data analysis indicates that 0.18 cu ft of the metal oxide will result in an 8-hour EVA capability. The testing suggests that the metal oxide technology offers a low-volume approach for a reusable CO2 removal concept applicable for at least 40 EVA missions. The development and testing of the breadboard regeneration package is also described.

Cusick, Robert J.

1990-01-01

186

Process for making a noble metal on tin oxide catalyst  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

187

Method for converting uranium oxides to uranium metal  

DOEpatents

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.

Duerksen, Walter K. (Norris, TN)

1988-01-01

188

Catalysis using hydrous metal oxide ion exchanges  

DOEpatents

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.

Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM); Stohl, Frances V. (Albuquerque, NM)

1985-01-01

189

Catalysis using hydrous metal oxide ion exchangers  

DOEpatents

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.

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

1983-07-21

190

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

SciTech Connect

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.

Chen Sheng [Key Laboratory of Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Zhu Junwu, E-mail: zhujw@mail.njust.edu.cn [Key Laboratory of Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Wang Xin, E-mail: wxin@public1.ptt.js.cn [Key Laboratory of Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China)

2011-06-15

191

Method and apparatus for the production of metal oxide powder  

DOEpatents

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.

Harris, Michael T. (Knoxville, TN); Scott, Timothy C. (Knoxville, TN); Byers, Charles H. (Oak Ridge, TN)

1992-01-01

192

Method and apparatus for the production of metal oxide powder  

DOEpatents

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.

Harris, Michael T. (Knoxville, TN); Scott, Timothy C. (Knoxville, TN); Byers, Charles H. (Oak Ridge, TN)

1993-01-01

193

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

NASA Astrophysics Data System (ADS)

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.

Nánai, László; Füle, Miklós

2014-11-01

194

Metal oxide nanostructures for gas detection  

NASA Astrophysics Data System (ADS)

Currently, most of gas sensors on the market are produced in thin or thick film technologies with the use of ceramic substrates. It is expected that the miniature sensors needed in portable applications will be based on one-dimensional structures due to their low power consumption, fast and stable time response, small dimensions and possibility of embedding in integrated circuit together with signal conditioning electronics. The authors manufactured resistance type gas sensors based on ZnO and WO3 nanostructures. ZnO:Al nanorods with good cristallinity were obtained with electrodeposition method, while ZnO:Al nanofibres with varying diameters were obtained by electrospinning method. The sensors were built as a nanowire network. WO3 films with nanocrystalline surface were manufactured by deposition of a three layer WO3/W/WO3 structure by RF sputtering and successive annealing of the structure in appropriate temperature range. In effect a uniform nanostructurized metal oxide layer was formed. Investigation of sensors characteristics revealed good sensitivity to nitrogen dioxide at temperatures lower than these for conventional conductometric type sensors.

Maziarz, Wojciech; Pisarkiewicz, Tadeusz; Rydosz, Artur; Wysocka, Kinga; Czyrnek, Grzegorz

2013-07-01

195

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

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

196

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

197

Aerosol chemical vapor deposition of metal oxide films  

DOEpatents

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).

Ott, Kevin C. (4745 Trinity Dr., Los Alamos, NM 87544); Kodas, Toivo T. (5200 Noreen Dr. NE., Albuquerque, NM 87111)

1994-01-01

198

The oxidative transformation of methane over the nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide  

Microsoft Academic Search

Two completely different behaviors of the oxidative transformation of methane were performed over the nickel-based catalysts because of the different modifications by alkali metal oxide and rare earth metal oxide and the different interactions between nickel and supports, and two types of catalysts, namely the LiNiLaOx catalyst with a good Oxidative Coupling of Methane (OCM) performance and the LiNiLaOx\\/Al2O3 supported

Qing Miao; Guoxing Xiong; Shishan Sheng; Wei Cui; Xiexian Guo

1996-01-01

199

Method of physical vapor deposition of metal oxides on semiconductors  

DOEpatents

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.

Norton, David P. (Knoxville, TN)

2001-01-01

200

Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials  

SciTech Connect

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.

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

2004-04-27

201

Mitigation of Complementary Metal-Oxide-Semiconductor Variability with Metal Gate Metal-Oxide-Semiconductor Field-Effect Transistors  

NASA Astrophysics Data System (ADS)

Variability due to Fermi level pinning at polycrystalline silicon gate grain boundary is examined as an additional source of intrinsic parameter fluctuation. Threshold voltage (Vt) variation with metal gate to avoid the variation is found to be mitigated with the measurement of n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) with an identical process except gate stack. The statistical variation of intrinsic gate delay and static noise margin of the 6 transistors static random access memory (SRAM) cell is predicted for future technology nodes using Monte Carlo circuit simulation with a process/physics-based compact model. It is found that the variability can be suppressed by ˜35% with adopting metal gate for 32 nm technology node.

Yang, Ji-Woon; Park, Chang Seo; Smith, Casey E.; Adhikari, Hemant; Huang, Jeff; Heh, Dawei; Majhi, Prashant; Jammy, Raj

2009-04-01

202

Magnetic Properties of Mesoporous and Nano-particulate Metal Oxides   

E-print Network

The magnetic properties of the first row transition metal oxides are wide and varied and have been studied extensively since the 1930’s. Observations that the magnetic properties of these material types change with the ...

Hill, Adrian H

2009-01-01

203

Electrolytic separation of crystals of transition-metal oxides  

NASA Technical Reports Server (NTRS)

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.

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

1969-01-01

204

Metal-oxide interfaces: Where the action is  

NASA Astrophysics Data System (ADS)

Heterogeneous catalyst systems comprising metals supported on oxides are widespread. Evidence now suggests that it is the interfacial regions that are most catalytically active, and this has been exploited to create a tandem nanocatalyst system.

Stair, Peter C.

2011-05-01

205

Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection  

PubMed Central

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

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

2009-01-01

206

Charge, orbital and magnetic ordering in transition metal oxides   

E-print Network

Neutron and x-ray diffraction has been used to study charge, orbital and magnetic ordering in some transition metal oxides. The long standing controversy regarding the nature of the ground state (Verwey structure) of the ...

Senn, Mark Stephen

2013-06-29

207

Voltage-current characteristics of point systems of metal-oxide-metal  

Microsoft Academic Search

A detection theory is developed for point-contact metal-oxide-metal (MOM) systems. A system with heterogeneous oxide strongly bonded to the substrate is considered. It is shown that the form of the functional connection between the barrier heights and the ultimate compressive strength of the oxide has no substantial influence on the voltage-current characteristics of the system. Quantitative analysis indicates that a

L. B. Vatova; V. V. Kobzev; A. A. Rivlin; V. S. Solovev

1975-01-01

208

A CCD imaging search for wide metal-poor binaries  

Microsoft Academic Search

We explored the regions within a radius of 25 arcsec around 473 nearby, low-metallicity G- to M-type stars using (VR)I optical filters and small-aperture telescopes. About 10% of the sample was searched up to angular separations of 90 arcsec. We applied photometric and astrometric techniques to detect true physical companions to the targets. The great majority of the sample stars

M. R. Zapatero Osorio; E. L. Martín

2004-01-01

209

Chemical aspects of solution routes to perovskite-phase mixed-metal oxides from metal-organic precursors  

Microsoft Academic Search

The goal of this article is to review the reaction chemistry occurring in solution routes to multicomponent metal oxides (i.e. containing two or more metals) from metal-organic precursors. In this context, the metal-organic precursor is usually a metal alkoxide, metal [beta]-diketonate or metal carboxylate compound. In the preparation of multicomponent metal oxide compounds, a number of key issues should be

Clive D. Chandler; Christophe. Roger; Mark J. Hampden-Smith

1993-01-01

210

Transition metal-catalyzed oxidation of sulfur(IV) oxides. Atmospheric-relevant processes and mechanisms  

Microsoft Academic Search

The transition metal-catalyzed oxidation of sulfur(IV) oxides has been known for more than 100 years. There is a significant lack of information on the actual role of the transition metal-catalyzed reactions, and much of the earlier work was performed without a detailed knowledge of the chemical system. For this reason attention is focused on the role of transition metal ions

Christian. Brandt; Rudi. van Eldik

1995-01-01

211

Taurine inhibition of metal-stimulated catecholamine oxidation  

Microsoft Academic Search

Taurine is an abundant amino acid found in mammalian tissues and it has been suggested to have cyto-protective functions.\\u000a The aim of the present study was to determine if taurine had the potential to reduce oxidative stress associated with metal-stimulated\\u000a catecholamine oxidation. Taurine and structural analogs of taurine were tested for their ability to inhibit metal-stimulated\\u000a quinone formation from dopamine

RALPH DAWSON JR; Deron Baker; Baerbel Eppler; Elisa Tang; Debbie Shih; Hunter Hern; Ming Hu

2000-01-01

212

In vitro evaluation of cytotoxicity of engineered metal oxide nanoparticles  

Microsoft Academic Search

The recent advances in nanotechnology and the corresponding popular usage of nanomaterials have resulted in uncertainties regarding their environmental impacts. In this study, we used a systematic approach to study and compare the in vitro cytotoxicity of selected engineered metal oxide nanoparticles to the test organisms — E. coli. Among the seven test nano-sized metal oxides, ZnO, CuO, Al2O3, La2O3,

Xiaoke Hu; Sean Cook; Peng Wang; Huey-min Hwang

2009-01-01

213

Metal oxide nano-crystals for gas sensing  

Microsoft Academic Search

This review article is focused on the description of metal oxide single crystalline nanostructures used for gas sensing. Metal oxide nano-wires are crystalline structures with precise chemical composition, surface terminations, and dislocation-defect free. Their nanosized dimension generate properties that can be significantly different from their coarse-grained polycrystalline counterpart. Surface effects appear because of the magnification in the specific surface of

Elisabetta Comini

2006-01-01

214

Developments in hot-filament metal oxide deposition (HFMOD)  

Microsoft Academic Search

Hot-filament metal oxide deposition (HFMOD) is a variant of conventional hot-filament chemical vapor deposition (HFCVD) recently developed in our laboratory and successfully used to obtain high-quality, uniform films of MOx, WOx and VOx. The method employs the controlled oxidation of a filament of a transition metal heated to 1000 °C or more in a rarefied oxygen atmosphere (typically, of about 1 Pa).

Steven F. Durrant; Benedito C. Trasferetti; Jair Scarmínio; Celso U. Davanzo; Francisco P. M. Rouxinol; Rogério V. Gelamo; Mario A. Bica de Moraes

2008-01-01

215

Process for Making a Noble Metal on Tin Oxide Catalyst  

NASA Technical Reports Server (NTRS)

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).

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

216

Water oxidation by an electropolymerized catalyst on derivatized mesoporous metal oxide electrodes.  

PubMed

A general electropolymerization/electro-oligomerization strategy is described for preparing spatially controlled, multicomponent films and surface assemblies having both light harvesting chromophores and water oxidation catalysts on metal oxide electrodes for applications in dye-sensitized photoelectrosynthesis cells (DSPECs). The chromophore/catalyst ratio is controlled by the number of reductive electrochemical cycles. Catalytic rate constants for water oxidation by the polymer films are similar to those for the phosphonated molecular catalyst on metal oxide electrodes, indicating that the physical properties of the catalysts are not significantly altered in the polymer films. Controlled potential electrolysis shows sustained water oxidation over multiple hours with no decrease in the catalytic current. PMID:24735242

Ashford, Dennis L; Lapides, Alexander M; Vannucci, Aaron K; Hanson, Kenneth; Torelli, Daniel A; Harrison, Daniel P; Templeton, Joseph L; Meyer, Thomas J

2014-05-01

217

Electronic structure of binary and ternary Ga or As oxides  

NASA Astrophysics Data System (ADS)

A systematic analysis of the electronic structure of As2O3, As2O5, Ga2O3, and GaAsO4 is made both experimentally and theoretically. The comparison between x-ray-photoemission spectra and tight-binding calculations allows us to recognize the contribution of each atomic state to each experimental peak. A clear distinction between As2O3 and all other oxides can be made. The top of the valence band is made of O 2p lone-pair states, except in As2O3, where the main contribution comes from As 4s states which gives a sharp feature at the top of the valence band. There is no observable difference in the x-ray photoelectron spectra between tetrahedral and octahedral environments for Ga and As atoms. From the calculated electronic charges, we can define the oxidation numbers that are also identical for tetrahedral and octahedral As or Ga atoms. Total-energy calculations show that oxides like Ga2O3 with only octahedral sites have a higher formation energy than those with both octahedral and tetrahedral sites.

Albanesi, E. A.; Sferco, S. J.; Lefebvre, I.; Allan, G.; Hollinger, G.

1992-11-01

218

On the Origin of Subdwarf B Stars and Related Metal-Rich Binaries  

E-print Network

Mounting evidence from subdwarf B (sdB) stars in the galactic field and their recently discovered counterparts in old open clusters indicates that at least two thirds of local disk sdB stars are binaries. Our recent radial velocity survey showed that sdB binaries naturally divide into two groups with contrasting spectroscopic and kinematic properties. Those with detectable spectral lines from a cooler companion invariably have periods longer than a year, while very short period sdB's have essentially invisible companions. We derive typical orbital separations for the components of the composite spectrum sdB's from their velocities. The current systems must have been produced by Roche lobe overflow/mass transfer from low mass, metal-rich giants near the first red giant branch tip, without undergoing common envelope envolution. The same process should also occur at slightly lower red giant luminosities, producing a wide binary with a helium white dwarf instead of an sdB star. Most short period sdB's probably result from a common envelope following Roche lobe overflow of the initial secondary onto the white dwarf. Rare post-common envelope sdB + main sequence (MS) binaries also exist, but available data suggest that most such systems involving lower MS companions end up merging. The small and nearly identical masses of the two known MS survivors in short period sdB binaries imply that both components must have lost a large fraction of their initial mass in the common envelope process.

Elizabeth M. Green; James Liebert; Rex A. Saffer

2000-12-11

219

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms  

E-print Network

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms Gordon E of Clean Metal Oxide Surfaces 83 2.1. The Nature of Defects on Metal Oxide Surfaces 83 2.2. Overview of UHV Surface Science Methods Used To Study Clean Metal Oxide Surfaces 84 2.3. Geometric and Electronic

Goodman, Wayne

220

Creation of Exotic Features in Metal Oxides by Surface Treatment for Enhanced Gas Sensing  

E-print Network

Creation of Exotic Features in Metal Oxides by Surface Treatment for Enhanced Gas Sensing Majed of oxide ceramics, we have developed a technique based on rigorous thermodynamic consideration of the metal/metal or air, the metal oxide of interest is reduced and re-oxidized by exposing it to a well-defined pO2

Azad, Abdul-Majeed

221

Field-induced resistive switching in metal-oxide interfaces  

Microsoft Academic Search

We investigate the polarity-dependent field-induced resistive switching phenomenon driven by electric pulses in perovskite oxides. Our data show that the switching is a common occurrence restricted to an interfacial layer between a deposited metal electrode and the oxide. We determine through impedance spectroscopy that the interfacial layer is no thicker than 10 nm and that the switch is accompanied by

S. Tsui; A. Baikalov; J. Cmaidalka; B. Lorenz; Y. Q. Wang; C. W. Chu; A. J. Jacobson

2004-01-01

222

Integrated photo-responsive metal oxide semiconductor circuit  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

223

Oxidative mechanisms in the toxicity of metal ions  

Microsoft Academic Search

The role of reactive oxygen species, with the subsequent oxidative deterioration of biological macromolecules in the toxicities associated with transition metal ions, is reviewed. Recent studies have shown that metals, including iron, copper, chromium, and vanadium undergo redox cycling, while cadmium, mercury, and nickel, as well as lead, deplete glutathione and protein-bound sulfhydryl groups, resulting in the production of reactive

S. J. Stohs; D. Bagchi

1995-01-01

224

Metal-oxide-based energetic materials and synthesis thereof  

DOEpatents

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.

Tillotson, Thomas M. (Tracy, CA), Simpson; Randall L. (Livermore, CA); Hrubesh, Lawrence W. (Pleasanton, CA)

2006-01-17

225

Surface Precipitation of Hydrolyzable Metal Ions on Oxide Surfaces  

E-print Network

Surface Precipitation of Hydrolyzable Metal Ions on Oxide Surfaces S. E. Fendorf Heavy metalO2 and TiO2 near and beyond monolayer coverage. Surface precipitation of Al(III) and La(III) was observed on MnO2, but was not apparent on TiO2 nor in bulk solution. Al(III) formed a surface precipitate

Sparks, Donald L.

226

Binary bulk metallic glass Ni 62Nb 38 with high compressive strength of 3100 MPa  

Microsoft Academic Search

Formability and mechanical properties of Ni62Nb38 binary bulk metallic glass were investigated in this study. Ni62Nb38 glassy rods were prepared by copper mold suction casting with a critical diameter larger than 2mm. The glassy rod exhibits typical amorphous characteristics in X-ray diffraction patterns, differential scanning calorimetry traces and high-resolution electron microscopic images. The formability of the alloy was investigated by

L. Xia; S. T. Shan; D. Ding; Y. D. Dong

2007-01-01

227

An assessment of studies on homogeneous diffusional nucleation kinetics in binary metallic alloys  

Microsoft Academic Search

A critical review is presented of all studies on homogeneous nucleation kinetics in crystalline binary metallic alloys located\\u000a in the literature. Emphasis was first placed upon examining the data on the number of precipitates per unit volume of matrix\\u000a phase,N\\u000a \\u000a v\\u000a , recorded as a function of isothermal reaction or aging time. With the exception of the results of a

H. I. Aaronson; F. K. LeGoues

1992-01-01

228

Bulk metallic glass formation in the binary Cu-Zr system  

Microsoft Academic Search

Using the Cu-Zr model system, we demonstrate that bulk amorphous alloys can be obtained by copper mold casting even in a binary metallic system. The narrow, off-eutectic, bulk-glass-forming range was found to require composition pinpointing to <1 at. %. A phase selection diagram is used to explain the success of our microstructure-based approach to pinpoint the best glass former in

D. Wang; Y. Li; B. B. Sun; M. L. Sui; K. Lu; E. Ma

2004-01-01

229

Complexed metals in hazardous waste: Limitations of conventional chemical oxidation  

SciTech Connect

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.

Diel, B.N. [RUST Federal Service, Inc., Anderson, SC (United States). Clemson Technical Center; Kuchynka, D.J. [Mirage Systems, Inc., Sunnyvale, CA (United States); Borchert, J. [Chemical Waste Management, Inc., Geneva, IL (United States). Environmental Monitoring Lab.

1994-12-31

230

Hydrous Iron(III)Tin(IV) Binary Mixed Oxide: Arsenic Adsorption Behaviour from Aqueous Solution  

Microsoft Academic Search

Groundwater in the Bengal delta plain is primarily in an anoxic environment and As(III)\\/As(total) ratios reported are in the range of 0.60 to 0.90. Most of the studied adsorbents showed greater adsorption affinity for less toxic As(V) than for more toxic As(III). The synthesis and physicochemical characterizations of iron(III)-tin(IV) binary mixed oxide composite with sys- tematic arsenic adsorption behaviour are

Uday Chand Ghosh; Durjoy Bandyopadhyay; Biswaranjan Manna; Manik Mandal

2006-01-01

231

(S)TEM analysis of functional transition metal oxides  

Microsoft Academic Search

Perovskite vanadates (AVO3) form an ideal family to study the structure-property relationships in transition metal oxides because their physical properties can easily be tailored by varying the A-site cations. (S)TEM is an ideal tool for this type of study due to its capacity for simultaneous imaging and chemical analysis. Determination of the oxidation state of vanadium in complex oxides have

Miaofang Chi

2008-01-01

232

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

NASA Astrophysics Data System (ADS)

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 in oxidation reactions and adsorption of heavy metal. Spontaneous formation of OMS-2 nanospheres was possible by tuning reaction parameters in the ultrasonic atomization process. In the second part, a microwave-hydrothermal route has been developed for the synthesis of 1D cobalt compounds (Chapter 5). These compounds are transformed to spinel type Co3O4 nanorods. The effects of solvents, cobalt sources, and microwave radiation time in the formation of 1D cobalt oxide nanostructures were studied in detail. These materials are catalytically active for CO oxidation and styrene oxidation reactions. Magnesia-yttria nanocomposites with controlled nanoscale grain sizes and homogenous microstructures are useful as IR transparent materials. A simple cost-effective sucrose based sol-gel route was devised for making MgO-Y 2O3 nanocomposites. Grain growth in these nanocomposites was systematically evaluated using transmission electron microscopy studies.

Iyer, Aparna

233

Interactions of Hydrogen Isotopes and Oxides with Metal Tubes  

SciTech Connect

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.

Glen R. Longhurst

2008-08-01

234

Ternary Self-Assembly of Ordered Metal Oxide Graphene Nanocomposites for  

E-print Network

Ternary Self-Assembly of Ordered Metal Oxide Graphene Nanocomposites for Electrochemical Energy graphene as fundamental building blocks to construct ordered metal oxide graphene nanoc techniques to prepare layered nanocom- posites with ceramics, clays, and graphite oxide nanoplatelets,7 9

Aksay, Ilhan A.

235

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

236

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2012-07-01

237

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2010-07-01

238

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2011-07-01

239

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

...2014-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2014-07-01

240

40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...Substances § 721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...identified generically as acryloxy alkanoic alkane derivative with mixed metal...

2013-07-01

241

Radiative emissivity of metals and oxidized metals at high temperature  

Microsoft Academic Search

Radiative emissivities of metals at high temperatures influence the energy balance and remote sensing in a wide range of manufacturing processes as well as research and development activities and thereby determine performance and even economic viability. Accurate and comprehensive measurements of metals thermal emissivity have always been a challenge due to numerous influential factors such as: spectral range, temperature, sample

George Teodorescu

2007-01-01

242

Aerosol chemical vapor deposition of metal oxide films  

DOEpatents

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.

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

1994-01-11

243

Reductive mobilization of oxide-bound metals  

SciTech Connect

We have completed a large number of experiments which examine the release of MnO{sub 2}-bound Co, Ni, and Cu. Our work has focused upon the following areas: (1) competitive adsorption among the three toxic metals and Mn(II); (2) toxic metal release upon addition of low MW organic reductants and complexants; and (3) toxic metal release upon addition of natural organic matter-rich surface waters and IHSS organic matter reference material.

Stone, A.T.

1991-01-01

244

Emerging applications of liquid metals featuring surface oxides.  

PubMed

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

Dickey, Michael D

2014-11-12

245

Metal oxide nanostructures and their gas sensing properties: a review.  

PubMed

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

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

2012-01-01

246

Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review  

PubMed Central

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

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

2012-01-01

247

Partial oxidation of methane to syngas over nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide  

Microsoft Academic Search

The NiO\\/Al2O3 catalyst was modified by alkali metal oxide (Li, Na, K) and rare-earth metal oxide (La, Ce, Y, Sm) in order to improve the thermal stability and the carbon-deposition resistance during the partial oxidation of methane to syngas (POM) reaction at high temperature. The reaction performance, thermal stability, structure, dispersity of nickel and carbon-deposition of the modified NiO\\/Al2O3 catalyst

Qing Miao; Guoxing Xiong; Shishan Sheng; Wei Cui; Ling Xu; Xiexian Guo

1997-01-01

248

Ultrathin amorphous zinc-tin-oxide buffer layer for enhancing heterojunction interface quality in metal-oxide solar cells  

E-print Network

We demonstrate a tunable electron-blocking layer to enhance the performance of an Earth-abundant metal-oxide solar-cell material. A 5 nm thick amorphous ternary metal-oxide buffer layer reduces interface recombination, ...

Heo, Jaeyeong

249

Internal zone growth method for producing metal oxide metal eutectic composites  

DOEpatents

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.

Clark, Grady W. (Oak Ridge, TN); Holder, John D. (Knoxville, TN); Pasto, Arvid E. (Oak Ridge, TN)

1980-01-01

250

Ethanol oxidation on metal oxide-supported platinum catalysts  

SciTech Connect

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 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.

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

2009-09-01

251

Processing dependence of metal/tunnel-oxide/silicon junctions  

NASA Technical Reports Server (NTRS)

The effects of process variations on the fixed-charge density, interface-state density, and tunneling properties of tunnel oxides on (100) silicon are discussed. Annealing the oxide in nitrogen reduces the fixed-charge and interface-state densities substantially, but also causes a marked increase in oxide capacitance. Anneals in forming gas before metallization alter the interface-state distribution and decrease the insulating qualities of the tunneling oxides. Postmetallization anneals in forming gas reduce the interface-state density to 1 x 10 to the 11th e/sq cm V or below, and appear not to affect the current through the oxide. No evidence for metal-induced interface states is observed.

Dressendorfer, P. V.; Lai, S. K.; Barker, R. C.; Ma, T. P.

1980-01-01

252

High-Resolution Spectroscopy of Extremely Metal-Poor Stars from SDSS/SEGUE. II. Binary Fraction  

NASA Astrophysics Data System (ADS)

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] \\lt -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.

Aoki, Wako; Suda, Takuma; Beers, Timothy C.; Honda, Satoshi

2015-02-01

253

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

DOEpatents

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.

Wong, Stanislaus S; Hongjun, Zhou

2012-11-27

254

Application of a mixed metal oxide catalyst to a metallic substrate  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

255

TiO2-Al2O3 binary mixed oxide surfaces for photocatalytic NOx abatement  

NASA Astrophysics Data System (ADS)

TiO2-Al2O3 binary oxide surfaces were utilized in order to develop an alternative photocatalytic NOx abatement approach, where TiO2 sites were used for ambient photocatalytic oxidation of NO with O2 and alumina sites were exploited for NOx storage. Chemical, crystallographic and electronic structure of the TiO2-Al2O3 binary oxide surfaces were characterized (via BET surface area measurements, XRD, Raman spectroscopy and DR-UV-Vis Spectroscopy) as a function of the TiO2 loading in the mixture as well as the calcination temperature used in the synthesis protocol. 0.5 Ti/Al-900 photocatalyst showed remarkable photocatalytic NOx oxidation and storage performance, which was found to be much superior to that of a Degussa P25 industrial benchmark photocatalyst (i.e. 160% higher NOx storage and 55% lower NO2(g) release to the atmosphere). Our results indicate that the onset of the photocatalytic NOx abatement activity is concomitant to the switch between amorphous to a crystalline phase with an electronic band gap within 3.05-3.10 eV; where the most active photocatalyst revealed predominantly rutile phase together and anatase as the minority phase.

Soylu, Asli Melike; Polat, Meryem; Erdogan, Deniz Altunoz; Say, Zafer; Y?ld?r?m, Cansu; Birer, Özgür; Ozensoy, Emrah

2014-11-01

256

Are metallothioneins equally good biomarkers of metal and oxidative stress?  

PubMed

Several researchers investigated the induction of metallothioneins (MTs) in the presence of metals, namely Cadmium (Cd). Fewer studies observed the induction of MTs due to oxidizing agents, and literature comparing the sensitivity of MTs to different stressors is even more scarce or even nonexistent. The role of MTs in metal and oxidative stress and thus their use as a stress biomarker, remains to be clearly elucidated. To better understand the role of MTs as a biomarker in Cerastoderma edule, a bivalve widely used as bioindicator, a laboratory assay was conducted aiming to assess the sensitivity of MTs to metal and oxidative stressors. For this purpose, Cd was used to induce metal stress, whereas hydrogen peroxide (H2O2), being an oxidizing compound, was used to impose oxidative stress. Results showed that induction of MTs occurred at very different levels in metal and oxidative stress. In the presence of the oxidizing agent (H2O2), MTs only increased significantly when the degree of oxidative stress was very high, and mortality rates were higher than 50 percent. On the contrary, C. edule survived to all Cd concentrations used and significant MTs increases, compared to the control, were observed in all Cd exposures. The present work also revealed that the number of ions and the metal bound to MTs varied with the exposure conditions. In the absence of disturbance, MTs bound most (60-70 percent) of the essential metals (Zn and Cu) in solution. In stressful situations, such as the exposure to Cd and H2O2, MTs did not bind to Cu and bound less to Zn. When organisms were exposed to Cd, the total number of ions bound per MT molecule did not change, compared to control. However the sort of ions bound per MT molecule differed; part of the Zn and all Cu ions where displaced by Cd ions. For organisms exposed to H2O2, each MT molecule bound less than half of the ions compared to control and Cd conditions, which indicates a partial oxidation of thiol groups in the cysteine residues through ROS scavenging. The present results suggest that MTs are excellent markers of metal stress, but not of oxidative stress. PMID:22854745

Figueira, Etelvina; Branco, Diana; Antunes, Sara C; Gonçalves, Fernando; Freitas, Rosa

2012-10-01

257

Initial stages of high temperature metal oxidation  

SciTech Connect

The application of XPS and UPS to the study of the initial stages of high temperature (> 350/sup 0/C) electrochemical oxidation of iron and nickel is discussed. In the high temperature experiments, iron and nickel electrodes were electrochemically oxidized in contact with a solid oxide electrolyte in the uhv system. The great advantages of this technique are that the oxygen activity at the interface may be precisely controlled and the ability to run the reactions in uhv allows the simultaneous observation of the reactions by XPS.

Yang, C.Y.; O'Grady, W.E.

1981-01-01

258

Topics in Catalysis 13 (2000) 519 5 Metal nanoclusters supported on metal oxide thin films  

E-print Network

the "materials gap" and "pressure gap", permitting catalytic studies of moderately complex surfaces under metal oxides. Model supported catalysts were subsequently prepared by vapor-depositing catalytically, electronic structure, and geometric structure to macroscopic properties such as catalytic activity

Goodman, Wayne

259

Direct reduction of actinide oxide and carbide to metal: Application to the preparation of plutonium metal  

NASA Astrophysics Data System (ADS)

Three different conversion and refining methods for the preparation of high purity plutonium metal are described: the calciothermic reduction of plutonium oxide followed by electrorefining; the thoriothermic reduction of plutonium oxide followed by selective evaporation; the tantalothermic reduction of plutonium carbide followed by selective evaporation. The calciothermic reduction of plutonium oxide followed by electrorefining is used for the semi-industrial or large scale production of high purity plutonium metal. The rate and yield of preparation and refining is high. With high purity reactants the reduction of the oxide with thorium is well adapted to obtain high purity plutonium metal on the laboratory scale. The tantalothermic reduction of plutonium carbide gives high purity plutonium metal even with impure plutonium starting material (recovered from waste). This results from the high selectivity at the different steps of the process.

Spirlet, J. C.; Müller, W.; Van Audenhove, J.

1985-06-01

260

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...

261

Advances in metal-induced oxidative stress and human disease.  

PubMed

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-tocopherol (vitamin E), glutathione (GSH), carotenoids, flavonoids, and other antioxidants) are capable of chelating metal ions reducing thus their catalytic activity to form ROS. A novel therapeutic approach to suppress oxidative stress is based on the development of dual function antioxidants comprising not only chelating, but also scavenging components. Parodoxically, two major antioxidant enzymes, superoxide dismutase (SOD) and catalase contain as an integral part of their active sites metal ions to battle against toxic effects of metal-induced free radicals. The aim of this review is to provide an overview of redox and non-redox metal-induced formation of free radicals and the role of oxidative stress in toxic action of metals. PMID:21414382

Jomova, Klaudia; Valko, Marian

2011-05-10

262

Microplasma-based synthesis of vertically aligned metal oxide nanostructures  

NASA Astrophysics Data System (ADS)

Vertically aligned metal oxide nanostructures (e.g., wires, needles, pillars and trees) of CuO, PdO and NiO were synthesized on several substrates (e.g., Si and ITO (indium tin oxide)) using a high-pressure (˜Torr) microplasma-based growth technique. Organometallic precursors were dissociated in the hollow cathode region of a supersonic plasma jet creating a directed flux of metal species (e.g., atoms, metastables, etc) which react with an oxygen background to form crystalline metal oxide films having a variety of nanomorphologies. Spiral-like growth fronts were seen in some cases for CuO, suggesting that nanowire growth may involve screw dislocations. Large area, nanowire films >1 cm2 with good adhesion and electrical connection to ITO substrates were deposited by raster-scanning a single jet. Details of the microplasma operation, the dynamics of the growth process and the resulting materials are discussed.

Koh, Travis L.; O'Hara, Evan C.; Gordon, Michael J.

2012-10-01

263

Microplasma-based synthesis of vertically aligned metal oxide nanostructures.  

PubMed

Vertically aligned metal oxide nanostructures (e.g., wires, needles, pillars and trees) of CuO, PdO and NiO were synthesized on several substrates (e.g., Si and ITO (indium tin oxide)) using a high-pressure (~Torr) microplasma-based growth technique. Organometallic precursors were dissociated in the hollow cathode region of a supersonic plasma jet creating a directed flux of metal species (e.g., atoms, metastables, etc) which react with an oxygen background to form crystalline metal oxide films having a variety of nanomorphologies. Spiral-like growth fronts were seen in some cases for CuO, suggesting that nanowire growth may involve screw dislocations. Large area, nanowire films >1 cm(2) with good adhesion and electrical connection to ITO substrates were deposited by raster-scanning a single jet. Details of the microplasma operation, the dynamics of the growth process and the resulting materials are discussed. PMID:23037639

Koh, Travis L; O'Hara, Evan C; Gordon, Michael J

2012-10-26

264

Engineering metal oxide structures for efficient photovoltaic devices  

NASA Astrophysics Data System (ADS)

Metal oxide-based photoanodes are critical components of dye sensitized solar cells (DSSCs), which are photoelectrochemical cells for the conversion of solar energy, promising to have several benefits as compared with their traditional counterparts. A careful engineering of the wide band gap metal oxide composing the photoanode, as well as their process design, is strategic for improving device performances and for planning a near future production scale up, especially devoted to reducing the environmental impact of the device fabrication. Herein, we present the application of ZnO hierarchical structures as efficient materials to be applied as photoanodes in DSSC, in the perspective of looking for alternative to TiO2 nanoparticles, currently the most exploited metal oxide in these devices.

Concina, Isabella; Selopal, Gurpreet S.; Milan, Riccardo; Vomiero, Alberto; Sberveglieri, Giorgio

2014-03-01

265

Accumulation of Metals by Bacteriogenic Iron Oxides in a Subterranean Environment  

E-print Network

Accumulation of Metals by Bacteriogenic Iron Oxides in a Subterranean Environment F. G. FERRIS emission spectroscopy revealed iron oxide contents that varied from 60% to 90% (dry weight basis). Metal decreasing with increasing iron oxide content was evident for each metal, implying that metal uptake

Konhauser, Kurt

266

Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films  

Microsoft Academic Search

Presently nanocrystalline materials have opened a new chapter in the field of electronic applications, since material properties could be changed by changing the crystallite size and\\/or thickness of the film. The synthesis of nanocrystalline metal chalcogenide and metal oxide thin films by chemical bath deposition (CBD) method is currently attracting considerable attention as it is relatively inexpensive, simple and convenient

S. M. Pawar; B. S. Pawar; J. H. Kim; Oh-Shim Joo; C. D. Lokhande

2011-01-01

267

Solid State Ionics 109 (1998) 151157 The electrochemical stability of lithium-metal oxides against metal  

E-print Network

Solid State Ionics 109 (1998) 151­157 The electrochemical stability of lithium-metal oxides against of secondary lithium batteries with Li MO cathodes isx 2 investigated. Loss of active material due to metal preferably reduce before the lithium ion during charging. © 1998 Elsevier Science B.V. All rights reserved

Ceder, Gerbrand

268

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

269

Utilization of Metal Oxides and Chalcogenides Stabilized in Organic Solvents  

NASA Astrophysics Data System (ADS)

Metal oxides and metal chalcogenides are important materials for a variety of applications including photocatalysis for decomposition of water, conductive and optical coatings, catalysts, photovoltaics, pryoelectrics, self-cleaning surfaces, pigments, and high efficiency Li-insertion materials in batteries among many other applications. Fundamental discoveries of surprising solubility of insoluble materials such as single and multi-walled carbon nanotubes and graphene has lead us to discover that certain metal oxides and metal chalcogenides such as TiO2 are soluble in certain solvents. Due to the industrial importance of TiO2, discovering stable pure solvent systems demonstrates a possibility to avoid surface modification of TiO2 nanoparticles by use materials such as of (3-methacryloxypropyl)-trimethoxysilane and various other methods of artificial stabilization. We have created thin films of TiO2, transparent ultraviolet (UV) --absorptive polymers, and Li-ion battery anodes with graphene-TiO2 hybrid materials.

Lampert, Lester; Flaig, Robby; Camacho, Jorge; Hamilton, James

2011-03-01

270

OXIDATION BEHAVIOR OF WELDED AND BASE METAL UNS N06025  

SciTech Connect

The oxidation behavior of specimens containing tungsten inert gas welds of UNS N06025 (NiCrFeAlY) was investigated in air for up to 5,000h at 900 -1000 C and 1,000h at 1100 -1200 C. In general, the microstructure was very homogeneous in the weld with smaller carbides and the Al2O3 penetrations were similar or smaller compared to those formed in the base metal. Above 1000 C, significant spallation was observed and Al and Cr depletion in the metal was observed to a similar extent in the weld and base metal. The maximum internal oxidation depth of the base metal at 900 and 1100 C was lower than several other commercial Ni-base alloys.

Pint, Bruce A [ORNL; Paul, Larry D. [Thyssen-Krupp VDM

2007-01-01

271

The Strength of the Metal. Aluminum Oxide Interface  

NASA Technical Reports Server (NTRS)

The strength of the interface between metals and aluminum oxide is an important factor in the successful operation of devices found throughout modern technology. One finds the interface in machine tools, jet engines, and microelectronic integrated circuits. The strength of the interface, however, should be strong or weak depending on the application. The diverse technological demands have led to some general ideas concerning the origin of the interfacial strength, and have stimulated fundamental research on the problem. Present status of our understanding of the source of the strength of the metal - aluminum oxide interface in terms of interatomic bonds are reviewed. Some future directions for research are suggested.

Pepper, S. V.

1984-01-01

272

Thermoelectric properties of delafossite-related layered metal oxides  

Microsoft Academic Search

Thermoelectric properties of layered metal oxides NaxCoO2 in a delafossite (CuFeO2)-related crystal structure are investigated, and a possible mechanism of p-type metallic conduction leading to outstanding thermoelectric performance as an oxide is discussed in terms of crystal chemistry. Sintered samples of NaxCoO2 (x≈0.5) were prepared from Na2CO3 and Co3O4 through the conventional solid state reaction by firing in air. Probably

Michitaka OHTAKI; Yusuke KUBO; Koichi EGUCHI

1998-01-01

273

[Toxicological characteristics and standardization of various poly-metallic oxides].  

PubMed

Acute toxicity, functional cumulative and local effects of the four ++poly-metallic oxides YBa2Cu3O7, Bi4Sr3O16, Tl2Ca2Cu3O10, Lao,7Sro,3CoO3, were studied in laboratory animals. Parallel experiments on assessment toxicity of the regular oxides of the studied metals in mice were carried out. The major dissolution of metals was shown to occur in acid medium. Thallium-barium-calcium cuprite turned out to be the most toxic and cumulative; it induced the most severe morphologic changes in the liver and kidneys. The least severe disorders caused by this substance were in the rat gastric mucosa and in rabbit eye after a conjunctival injection. Yttrium-barium cuprite induced the most severe changes at the site of injection, lanthanum-strontium cobaltite ranks second here. All copper-containing polymetallic oxides show resorptive toxicity when applied to the skin. Different types of combined toxicity are possible, that is why MACs for the regular oxides can not be used for setting the normal concentrations of ++poly-metallic oxides in air. Estimated toxicometric parameters helped to score the concentrations, which may serve as tentative safe levels of the studies substances. PMID:1478519

Neizvestnova, E M; Katsnel'son, B A; Davydova, V I; Malysheva, L G; Konovalova, N E

1992-01-01

274

Process for removing soluble metal cations in iron oxide pigments  

SciTech Connect

This patent describes a process for removing soluble metal cations contained in transparent iron oxide pigments comprising washing the iron oxide pigment with a composition containing a ligand compound wherein the pigment after the washing has conductivity of less than about 500 ..mu..mho, wherein the quantity of the ligand compound is from about 0.1 to 5.0 percent by weight relative to the total pigment weight.

Patil, A.S.

1988-07-19

275

Oxidative mechanisms in the toxicity of metal ions.  

PubMed

The role of reactive oxygen species, with the subsequent oxidative deterioration of biological macromolecules in the toxicities associated with transition metal ions, is reviewed. Recent studies have shown that metals, including iron, copper, chromium, and vanadium undergo redox cycling, while cadmium, mercury, and nickel, as well as lead, deplete glutathione and protein-bound sulfhydryl groups, resulting in the production of reactive oxygen species as superoxide ion, hydrogen peroxide, and hydroxyl radical. As a consequence, enhanced lipid peroxidation. DNA damage, and altered calcium and sulfhydryl homeostasis occur. Fenton-like reactions may be commonly associated with most membranous fractions including mitochondria, microsomes, and peroxisomes. Phagocytic cells may be another important source of reactive oxygen species in response to metal ions. Furthermore, various studies have suggested that the ability to generate reactive oxygen species by redox cycling quinones and related compounds may require metal ions. Recent studies have suggested that metal ions may enhance the production of tumor necrosis factor alpha (TNF alpha) and activate protein kinase C, as well as induce the production of stress proteins. Thus, some mechanisms associated with the toxicities of metal ions are very similar to the effects produced by many organic xenobiotics. Specific differences in the toxicities of metal ions may be related to differences in solubilities, absorbability, transport, chemical reactivity, and the complexes that are formed within the body. This review summarizes current studies that have been conducted with transition metal ions as well as lead, regarding the production of reactive oxygen species and oxidative tissue damage. PMID:7744317

Stohs, S J; Bagchi, D

1995-02-01

276

Large Lateral Photovoltaic Effect in Metal-(Oxide-) Semiconductor Structures  

PubMed Central

The lateral photovoltaic effect (LPE) can be used in position-sensitive detectors to detect very small displacements due to its output of lateral photovoltage changing linearly with light spot position. In this review, we will summarize some of our recent works regarding LPE in metal-semiconductor and metal-oxide-semiconductor structures, and give a theoretical model of LPE in these two structures. PMID:22163463

Yu, Chongqi; Wang, Hui

2010-01-01

277

Metal current collect protected by oxide film  

DOEpatents

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.

Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); DeJonghe, Lutgard C. (Lafayette, CA)

2004-05-25

278

Stabilisation of metal ions in unusual oxidation states and electron dynamics in oxide glasses  

NASA Astrophysics Data System (ADS)

The results of studies on the stabilisation of metal ions in unusual oxidation states in oxide glasses are surveyed. Attention is concentrated on the relation between the stabilisation of these ions and redistribution of the electron density, and on the disproportionation reactions accompanying it. The effect of reversible low-temperature disproportionation on niobium, titanium, vanadium, molybdenum, tungsten, and other ions is considered. The formation of metal clusters in oxide glasses is shown also to be associated with disproportionation. The bibliography includes 108 references.

Aleksandrov, A. I.; Prokof'ev, Alexandr I.; Bubnov, Nikolai N.

1996-06-01

279

Isopropanol oxidation by pure metal oxide catalysts: number of active surface sites and turnover frequencies  

Microsoft Academic Search

The objective of the present study was to determine the number of active surface sites and their nature, redox or acidic, for bulk metal oxide catalysts using isopropanol as a chemical probe molecule. Isopropanol oxidation activity on the following metal oxides was investigated: MgO, CaO, SrO, BaO, Y2O3, La2O3, CeO2, TiO2, ZrO2, HfO2, V2O5, Nb2O5, Ta2O5, Cr2O3, MoO3, WO3, Mn2O3,

Deepak Kulkarni; Israel E. Wachs

2002-01-01

280

Laboratory SIP signatures associated with oxidation of disseminated metal sulfides.  

PubMed

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. PMID:23531431

Placencia-Gómez, Edmundo; Slater, Lee; Ntarlagiannis, Dimitrios; Binley, Andrew

2013-05-01

281

Laboratory SIP signatures associated with oxidation of disseminated metal sulfides  

NASA Astrophysics Data System (ADS)

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., Fe2 + and Fe3 + 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 (Fe2 + and Fe3 +), particularly for the case of pyrrhotite minerals.

Placencia-Gómez, Edmundo; Slater, Lee; Ntarlagiannis, Dimitrios; Binley, Andrew

2013-05-01

282

Reversible electron-transfer reactions within a nanoscale metal oxide cage mediated by metallic substrates  

SciTech Connect

Transition metal oxides exhibit a rich collection of electronic properties and have many practical applications in areas such as catalysis and ultra-high-density magnetic data storage. Therefore the development of switchable molecular transition metal oxides has potential for the engineering of single-molecule devices and nanoscale electronics. At present, the electronic properties of transition metal oxides can only be tailored through the irreversible introduction of dopant ions, modifying the electronic structure by either injecting electrons or core holes. Here we show that a molybdenum(VI) oxide 'polyoxometalate' molecular nanocluster containing two embedded redox agents is activated by a metallic surface and can reversibly interconvert between two electronic states. Upon thermal activation two electrons are ejected from the active sulphite anions and delocalized over the metal oxide cluster cage, switching it from a fully oxidized state to a two-electron reduced state along with the concomitant formation of an S-S bonding interaction between the two sulphur centres inside the cluster shell.

Fleming, C.; Long, D. L.; McMillian, N.; Johnston, J.; Bovet N.; Dhanak, V.; Gadegaard, N.; Kogerler, P.; Cronin, L.; Kadodwala, M.

2008-03-30

283

Thermochemistry of rare-earth-metal-alkaline-earth-metal-copper oxide superconductors  

Microsoft Academic Search

Enthalpies of formation of the perovskite-related oxides LaâCuOâ, La\\/sub 1.85\\/Sr\\/sub 0.15\\/CuOâ, and YBaâCuâO\\/sub y\\/(y = 6.25, 6.47, 6.69, and 6.93) have been determined at 298.15 K by solution calorimetry. Room-temperature stabilities of these compounds have been assessed in terms of the parent binary oxides and of the oxygen content. High-temperature (to 900\\/degree\\/C) thermal behavior of YBaâCuâO\\/sub y\\/ has been used

Lester R. Morss; David C. Sonnenberger; R. J. Thorn

1988-01-01

284

Atomic Layer Deposition of Metal Oxide Thin Films on Metallic Substrates  

NASA Astrophysics Data System (ADS)

Atomic layer deposition (ALD) is a powerful ultra-thin film deposition technique that uses sequential self-limiting surface reactions to provide conformal atomic scale film growth. Deposition of ALD films on many substrate systems has been studied before; however, limited data is available on deposition on metallic surfaces. The investigation of the growth of Al 2O3, HfO2, and ZrO2 as three technologically important metal oxides on metallic substrates is the subject of this thesis. Al2O3, HfO2, and ZrO2 films were grown by ALD on silicon, as a well-studied substrate, in different operating conditions to investigate the effect of process parameters on film properties. To study the growth of oxides on metals, thin metallic substrates were prepared by sputter deposition on silicon wafers and then were transferred to the ALD chamber where the film growth was monitored by in-situ spectroscopic ellipsometry. The transfer was performed via a load lock system without breaking the vacuum to preserve the pristine metal surface. Formation of a thin interfacial layer of metal oxide was observed during the initial moments of plasma enhanced ALD, that was due to the exposure of metal surface to oxygen plasma. In-situ spectroscopic ellipsometry was used to accurately measure the thickness change of the growing films including the interfacial layer. The thickness of this interfacial oxide layer depended on various process parameters including deposition temperature, order of precursors and plasma pulse length. The interfacial oxide layer was absent during the conventional thermal ALD. However, thermal ALD of oxides on metals exhibited substrate-inhibited growth, especially at higher deposition temperatures. With the knowledge of ALD growth characteristics on metals, metal-insulator-metal (MIM) devices were fabricated by both thermal and plasma enhanced ALD and electrically characterized. The presence of the interfacial oxide layer altered the device performance by changing the capacitance and current characteristics. Employing this approach, it was shown that ALD can be successfully used in the fabrication process of MIM devices and similar systems where ultra-thin insulating layers need to be uniformly deposited on a metallic surface.

Foroughi Abari, Ali

285

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

PubMed Central

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

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

2015-01-01

286

A novel microstructured metal-supported solid oxide fuel cell  

NASA Astrophysics Data System (ADS)

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 ?m layer of a honeycomb-metallic framework with hexagonal cells which supports a 250 ?m layer of electrolyte. Each hexagonal cell is further functionalized with a thin 5-10 ?m 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.

Fernández-González, R.; Hernández, E.; Savvin, S.; Núñez, P.; Makradi, A.; Sabaté, N.; Esquivel, J. P.; Ruiz-Morales, J. C.

2014-12-01

287

All-alkoxide synthesis of strontium-containing metal oxides  

DOEpatents

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.

Boyle, Timothy J. (Albuquerque, NM)

2001-01-01

288

METALLICITY EFFECT ON LOW-MASS X-RAY BINARY FORMATION IN GLOBULAR CLUSTERS  

SciTech Connect

We present comprehensive observational results of the metallicity effect on the fraction of globular clusters (GCs) that contain low-mass X-ray binaries (LMXB), by utilizing all available data obtained with Chandra for LMXBs and Hubble Space Telescope Advanced Camera for Surveys (ACS) for GCs. Our primary sample consists of old elliptical galaxies selected from the ACS Virgo and Fornax surveys. To improve statistics at both the lowest and highest X-ray luminosity, we also use previously reported results from other galaxies. It is well known that the fraction of GCs hosting LMXBs is considerably higher in red, metal-rich, GCs than in blue, metal-poor GCs. In this paper, we test whether this metallicity effect is X-ray luminosity-dependent and find that the effect holds uniformly in a wide luminosity range. This result is statistically significant (at {>=}3{sigma}) in LMXBs with luminosities in the range L {sub X} = 2 Multiplication-Sign 10{sup 37} to 5 Multiplication-Sign 10{sup 38} erg s{sup -1}, where the ratio of GC-LMXB fractions in metal-rich to metal-poor GCs is R = 3.4 {+-} 0.5. A similar ratio is also found at lower (down to 10{sup 36} erg s{sup -1}) and higher luminosities (up to the ULX regime), but with less significance ({approx}2{sigma} confidence). Because different types of LMXBs dominate in different luminosities, our finding requires a new explanation for the metallicity effect in dynamically-formed LMXBs. We confirm that the metallicity effect is not affected by other factors such as stellar age, GC mass, stellar encounter rate, and galacto-centric distance.

Kim, D.-W.; Fabbiano, G.; Fragos, T. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ivanova, N.; Sivakoff, G. R. [Department of Physics, University of Alberta, Edmonton, AB (Canada)] [Department of Physics, University of Alberta, Edmonton, AB (Canada); Jordan, A. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile)] [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Voss, R. [Department of Astrophysics/IMAPP, Radboud University, Nijmegen (Netherlands)] [Department of Astrophysics/IMAPP, Radboud University, Nijmegen (Netherlands)

2013-02-10

289

Metal Permeation into Multi-layered Graphene Oxide  

PubMed Central

Understanding the chemical and physical properties of metal/graphene oxide (M/GO) interfaces is important when GO is used in electronic and electrochemical devices because the metal layer must be firmly attached to GO. Here, permeation of metal from the surface into GO paper bulk at the M/GO interface was observed at room temperature for metals such as Cu, Ag, Ni, Au, and Pt. Cu, Ag, and Ni quickly permeated GO as ions into the bulk under humid conditions. At first, these metals changed to hydrated ions as a result of redox reactions (with reduction of GO) at the surface, and then permeated the interlayers. Au and Pt were observed to permeate GO as atoms into the GO bulk at room temperature, although the permeation rates were low. These surprising results are considered to be due to the presence of many defects and/or edges with oxygenated groups in the GO paper. PMID:24413270

Ogata, Chikako; Koinuma, Michio; Hatakeyama, Kazuto; Tateishi, Hikaru; Asrori, Mohamad Zainul; Taniguchi, Takaaki; Funatsu, Asami; Matsumoto, Yasumichi

2014-01-01

290

ADSORPTION OF TRACE METALS BY HYDROUS FERRIC OXIDE IN SEAWATER  

EPA Science Inventory

The adsorption of trace metals by amorphous hydrous ferric oxide in seawater is studied with reference to simple model systems designed to isolate the factors which may have an effect on the isotherms. Results show that the complex system behaves in a remarkably simple way and th...

291

Facile self-assembly and stabilization of metal oxide nanoparticles.  

PubMed

This paper describes a facile method of self-assembling different metal oxide nanoparticles into nanostructured materials via di-carboxylate linkers (oxalic acid) using TiO2 as an example. In this method, the di-carboxylate linkers react with surface hydroxyls on metal oxide nanoparticles forming covalent, ester-like bonds, which enable the binding of two metal oxide particles, one at either end of the linker and facilitates efficient self-assembly of one group of metal oxide nanoparticles homogeneously distributed onto the surface of another group. The oxalate linkers can then be removed by thermal decomposition. This approach is shown to be effective using differently-sized TiO2 nanoparticles, namely in-house synthesized 3-5nm anatase nanocrystals and Degussa P25 titania particles (mean 21nm particle size). Our data show that the application of a high temperature heat treatment (450°C for 30min), conventionally applied to achieve a stable porous structure by thermal decomposition of the linker molecules and by inducing inter-particle necking, damages the surface area of the nanostructured material. However, here we show that sintering at 300°C for 30min or by flash near infrared radiation sintering for 12s efficiently decomposes the oxalate linkers and stabilizes the nanostructure of the material whilst maintaining its high surface area. PMID:25525978

Charbonneau, Cecile; Holliman, Peter J; Davies, Matthew L; Watson, Trystan M; Worsley, David A

2015-03-15

292

Active metal oxides and polymer hybrids as biomaterials  

Microsoft Academic Search

Bone anchored prosthetic attachments, like other percutaneous devices, suffer from poor soft tissue integration, seen as chronic inflammation, infection, epithelial downgrowth and regression. We looked at the use of metal oxides as bioactive agents that elicit different bioresponses, ranging from cell attachment, tissue integration and reduction of inflammation to modulation of cell proliferation, morphology and microbe killing. This study presents

John D. Jarrell

2008-01-01

293

Towards Carbon-free Metals Production by Molten Oxide Electrolysis  

E-print Network

Towards Carbon-free Metals Production by Molten Oxide Electrolysis Deepak Khetpal, Andrew Ducret by-products problems with electrolytic technologies: Al electrolysis makes CO2 (½ kg C / kg Al) Mg electrolysis makes Cl2 C & F react to make CF4 & C2F6 C & Cl in presence of O dioxins? furans? #12;Sadoway, MIT

Sadoway, Donald Robert

294

The Extraction of Metals from Their Oxides and Sulphides.  

ERIC Educational Resources Information Center

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)

Price, Alun H.

1980-01-01

295

CMOS array design automation techniques. [metal oxide semiconductors  

NASA Technical Reports Server (NTRS)

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.

Ramondetta, P.; Feller, A.; Noto, R.; Lombardi, T.

1975-01-01

296

Electron spectroscopic studies of perfect and defect metal oxide surfaces  

Microsoft Academic Search

A number of surface sensitive electron spectroscopic techniques have been used during the last few years to study the geometric and electronic structure of well characterized surfaces of metal oxide single crystals. For rocksalt monoxides, the (100) surface has been found to be very nearly a truncation of the bulk lattice; only qualitativelow energy electron diffraction (LEED) measurements have been

Victor E. Henrich

1987-01-01

297

Oxidation resistant filler metals for direct brazing of structural ceramics  

DOEpatents

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.

Moorhead, Arthur J. (Knoxville, TN)

1986-01-01

298

Electrolyte permeable diaphragm including a polymeric metal oxide  

SciTech Connect

A liquid permeable diaphragm is described for an electrolytic cell, the diaphragm comprises: major amount of fibrillated poly-fluorocarbon, a minor amount of a perfluorinated ion exchange material and a polymeric metal oxide selected from the group consisting of polytitanic acid, polyzirconic acid, polysilicic acid, polyaluminic acid or mixtures.

Darlington, W.B.; Du Bois, D.W.

1987-07-14

299

Epitaxial electrodeposition of chiral and spintronic metal oxides  

Microsoft Academic Search

This dissertation presents an investigation of the electrodeposition of epitaxial and polycrystalline functional metal oxide films on conducting polycrystalline and single crystal substrates. In the first part of the study, electrodeposited CuO films are shown to be enantiospecific catalysts. In the second part of the study, Fe3O4 films are electrodeposited with a magnetoresistance of ˜-6 % at 300 K in

Hiten Mahendra Kothari

2005-01-01

300

Molten-Metal Electrodes for Solid Oxide Fuel Cells  

SciTech Connect

Molten In, Pb, and Sb were examined as anodes in solid oxide fuel cells (SOFC) that operate between 973 and 1173 K. The results for these metals were compared with those reported previously for molten Sn electrodes. Cells were operated under “battery” conditions, with dry He or N2 flow in the anode compartment, to characterize the electrochemical oxidation of the metals at the yttria-stabilized zirconia (YSZ)-electrolyte interface. In most cases, the open-circuit voltages (OCVs) were close to that based on equilibrium between the metals and their oxides. With Sn and In, the cell impedances increased dramatically at all temperatures after drawing current due to formation of insulating, oxide barriers at the electrolyte interface. Similar results were observed for Pb at 973 and 1073 K, but the impedance remained low even after PbO formation at 1173 K because this is above the melting temperature of PbO. Similarly, the impedances of molten Sb electrodes at 973 K were low and unaffected by current flow because of the low melting temperature of Sb{sub 2}O{sub 3}. The potential of using molten-metal electrodes for direct-carbon fuel cells and for energy-storage systems is discussed.

Jayakumar, A.; Vohs, J. M.; Gorte, R. J.

2010-01-01

301

Metal complexes of substituted Gable porphyrins as oxidation catalysts  

DOEpatents

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.

Lyons, J.E.; Ellis, P.E. Jr.; Wagner, R.W.

1996-01-02

302

Metal complexes of substituted Gable porphyrins as oxidation catalysts  

DOEpatents

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.

Lyons, James E. (Wallingford, PA); Ellis, Jr., Paul E. (Downingtown, PA); Wagner, Richard W. (Murrysville, PA)

1996-01-01

303

The growth of one-dimensional oxide nanostructures by thermal oxidation of metals  

NASA Astrophysics Data System (ADS)

Fundamental understanding of metals and alloys oxidation and reduction is important for the next generation technology. A detailed study on the oxide nanostructures growth from the oxidation of model metal systems, Cu, Fe, Zn and brass has been investigated to bridge the information gap between the oxidation mechanisms of buck metals and alloys to metal oxide nanostructures. It is observed that CuO nanowires have a bicrystal structure and form directly on top of underlying CuO grains. The driving force for the oxide nanowire growth is attributed to the compressive stresses generated during the oxidation. To verify this growth mechanism, Cu foils are bent or sandblasted to create stresses. We show that the oxide nanowire formation can be effectively promoted by surface bending tensile stresses or surface roughening via sandblasting. The formation of alpha-Fe2O3 nanowires by oxidation of Fe also follows the same stress driven mechanism as Cu. It is also found that decreasing the oxygen pressure or modifying the surface roughness by sandblasting can be employed to tune the hematite nanostructures from nanowires to nanobelts or nanoblades. The growth of ZnO nanowires by direct oxidation of pure Zn follows different mechanisms depending on the temperatures: the oxidation below the melting point of Zn is dominated by a solid-solid transformation process, a liquid-solid process between the melting and boiling points of Zn, and a vapor-solid process above the boiling point of Zn. ZnO nanowires can also be synthesized by thermal oxidation of brass (Cu0.7Zn0.3). With increasing the oxidation temperature or exerting sandblasting onto brass, the formation of ZnO nanowires can be effectively suppressed. The thermally induced reduction of CuO nanowires are studied by in situ transmission electron microscopy. Reduction of CuO nanowires results in the formation of a unique hierarchical hybrid nanostructure, in which the lower oxide (Cu2O) nanoparticles partially embedded into the parent oxide phase (CuO). For the CuO nanowires sheathed by a carbon shell, we show that confined nanoscale geometry leads to changes in the oxide reduction mechanism from a surface dominated process to the bulk dominated process.

Yuan, Lu

304

Evolution of massive stars at very low metallicity including rotation and binary interactions  

E-print Network

We discuss recent models on the evolution of massive stars at very low metallicity including the effects of rotation, magnetic fields and binarity. Very metal poor stars lose very little mass and angular momentum during the main sequence evolution, and rotation plays a dominant role in their evolution. In rapidly rotating massive stars, the rotationally induced mixing time scale can be even shorter than the nuclear time scale throughout the main sequence. The consequent quasi-chemically homogeneous evolution greatly differs from the standard massive star evolution that leads to formation of red giants with strong chemical stratification. Interesting outcomes of such a new mode of evolution include the formation of rapidly rotating massive Wolf-Rayet stars that emit large amounts of ionizing photons, the formation of a long gamma-ray bursts and a hypernovae, and the production of large amounts of primary nitrogen. We show that binary interactions can further enhance the effects of rotation, as mass accretion in a close binary spins up the secondary.

S. -C. Yoon; M. Cantiello; N. Langer

2008-01-28

305

Strain effects in low-dimensional transition metal oxides Jinbo Cao a,b,  

E-print Network

Strain effects in low-dimensional transition metal oxides Jinbo Cao a,b, *, Junqiao Wu a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.1. Spin­lattice­charge coupling in transition metal oxides

Wu, Junqiao

306

Dissolution of metal and metal oxide nanoparticles in aqueous media.  

PubMed

The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin films), dialysis membrane (DM) and ultrafiltration (UF). Relatively small fractions of Ag nanoparticles dissolved, whereas ZnO dissolved nearly completely within few hours. Cu and CuO dissolved as a function of pH. Using DGT, less dissolved Ag was measured compared to UF and DM, likely due to differences in diffusion of organic complexes. Similar dissolved metal concentrations of ZnO, Cu and CuO nanoparticles were determined using DGT and UF, but lower using DM. The results indicate that there is a need to apply complementary techniques to precisely determine dissolution of nanoparticles in aqueous media. PMID:24832924

Odzak, Niksa; Kistler, David; Behra, Renata; Sigg, Laura

2014-08-01

307

Mechanistic aspects of photooxidation of polyhydroxylated molecules on metal oxides  

PubMed Central

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 TiO2, ?-FeOOH, and ?-Fe2O3 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 TiO2 oxidizes all of the carbohydrates and polyols, whereas ?-FeOOH oxidizes some of the carbohydrates, and ?-Fe2O3 is unreactive. These results serve as a stepping stone for understanding the photochemistry on mineral surfaces of more complex biomolecules such as nucleic acids. PMID:21532934

Shkrob, Ilya A.; Marin, Timothy M.; Chemerisov, Sergey D.; Sevilla, Michael D.

2011-01-01

308

Mechanistic aspects of photooxidation of polyhydroxylated molecules on metal oxides.  

SciTech Connect

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.

Shkrob, I. A.; Marin, T. M.; Sevilla, M. D.; Chemerisov, S. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Oakland Univ.)

2011-03-24

309

Transition metal dioxygen complexes as intermediates in homogeneous catalytic oxidations  

NASA Astrophysics Data System (ADS)

The formation and main structural properties of superoxo and peroxo complexes are briefly described. These complexes are involved in catalytic oxidations (oxygenations) by dioxygen occurring under mild conditions in the presence of iron, cobalt, manganese, rhodium and other transition metal complexes. Examples of catalytic systems are taken from cytochrome P-450 models with specific reference to the mechanisms involved. Metalloporphyrin-catalysed oxidations of hydrocarbons involve free-radical chain processes in most cases. Added reducing agents modify the mechanism of oxidation by pumping electrons into key intermediates. They help the formation of oxometal species, which may transfer oxygen atoms to substrates, thereby improving the selectivity. Olefin oxidation is a difficult task for the homogeneous catalysts described: only a few working systems are available, based mainly on rhodium phosphine complexes. Peroxometalacycles are presumably formed, whose decomposition involves co-oxidation of a phosphine molecule. The oxidation of hindered phenols catalysed by cobalt (II) Schiff-base complexes points to the involvement of superoxocobalt species abstracting a H-atom from the phenol. Complex reaction patterns emerge from the oxidation of o-disubstituted phenols. The synthetic potential of homogeneous catalytic oxidation is illustrated on examples including various types of organic compounds.

Simándi, Lászlò I.

310

Solubility Behavior and Phase Stability of Transition Metal Oxides in Alkaline Hydrothermal Environments  

SciTech Connect

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.

S.E. Ziemniak

2000-05-18

311

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

SciTech Connect

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.

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. (Materials Science Division); ( OTD-EESA); (Univ. of Nevada at Las Vegas); (LANL); (Northwestern Univ.)

2011-06-15

312

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

SciTech Connect

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.

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. (UNLV); (NWU); (LANL)

2011-10-19

313

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Metal oxide, modified with alkyl and vinyl terminated...Chemical Substances § 721.10044 Metal oxide, modified with alkyl and vinyl terminated...substance identified generically as metal oxide, modified with alkyl and vinyl...

2011-07-01

314

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Nickel, cobalt mixed metal oxide (generic). 721.5315 Section 721...721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance...generically as nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to...

2012-07-01

315

40 CFR 721.10044 - Metal oxide, modified with alkyl and vinyl terminated polysiloxanes (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Metal oxide, modified with alkyl and vinyl terminated...Chemical Substances § 721.10044 Metal oxide, modified with alkyl and vinyl terminated...substance identified generically as metal oxide, modified with alkyl and vinyl...

2010-07-01

316

Sorption and filtration of metals using iron-oxide-coated sand  

Microsoft Academic Search

Iron oxides are good adsorbents for uncomplexed metals, some metal-ligand complexes, and many metal oxyanions. However, the adsorbent properties of these oxides are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This paper describes experiments in which iron oxides were coated onto the surface of ordinary filter sand, and this

Mark M. Benjamin; Ronald S. Sletten; Robert P. Bailey; Thomas Bennett

1996-01-01

317

Metal-oxide-silicon diodes on deuterium-implanted silicon substrate and R. K. Jarwal  

E-print Network

PROOF COPY 047021APL Metal-oxide-silicon diodes on deuterium-implanted silicon substrate D. Misraa implantation was used to incorporate deuterium at the Si­SiO2 interface. Polycrystalline silicon gate metal-oxide0003-6951 00 04721-5 Role of hydrogen in metal-oxide-semiconductor MOS device stability and reliability

Misra, Durgamadhab "Durga"

318

The Effect of the Metal Oxidation on the Vacuum Chamber Impedance Andranik Tsakanian  

E-print Network

1 The Effect of the Metal Oxidation on the Vacuum Chamber Impedance Andranik Tsakanian Hamburg for various thicknesses of the metallic layer and oxidation depth. Based on the obtained results the impedance as a sum of oxide and metal surface impedances. Based on this solution the monopole impedances

319

Role of Electronic Structure in the Susceptibility of Metastable Transition-Metal Oxide Structures to Transformation  

E-print Network

Role of Electronic Structure in the Susceptibility of Metastable Transition-Metal Oxide Structures transition-metal ions in an oxide and how these factors in turn affect the resistance of metastable 3d transition-metal oxides against transformation. This is a relevant topic to the Li rechargeable battery field

Ceder, Gerbrand

320

CO oxidation over Au/TiO2 prepared from metal-organic gold complexes  

E-print Network

CO oxidation over Au/TiO2 prepared from metal-organic gold complexes Zhen Yan, Sivadinarayana a particle size larger than 30 nm, and were catalytically inactive for CO oxidation [10]. Metal with their catalytic activity for CO oxidation. 2. Experimental The Au/TiO2 catalysts were prepared from metal- organic

Goodman, Wayne

321

GaNWW-oxide metal base transistor with very large current gain and power gain  

E-print Network

GaNÃ?WÃ?W-oxide metal base transistor with very large current gain and power gain K. Mochizuki,a) K 2000 We demonstrate a GaN/W/W-oxide metal base transistor MBT whose collector is formed by oxidizing high due to the difficulty in achieving a high hole concentration and mobility. The metal base

Asbeck, Peter M.

322

Illumination induced charge separation at tetraphenyl-porphyrin/metal oxide interfaces  

E-print Network

Illumination induced charge separation at tetraphenyl-porphyrin/metal oxide interfaces Y. Zidon were studied at tetraphenyl-porphyrin H2TPP /metal oxide interfaces by surface photovoltage charging of the H2TPP layer is induced by preferential recombination of holes at the H2TPP /metal oxide

Shapira, Yoram

323

Synthesis and structural, magnetic, thermal, and transport properties of several transition metal oxides and aresnides  

SciTech Connect

Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and antiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides V{sub n}O{sub 2n-1} where 2 {le} n {le} 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions. The only exception is V{sub 7}O{sub 13} which remains metallic down to 4 K. The ternary vanadium oxide LiV{sub 2}O{sub 4} has the normal spinel structure, is metallic, does not undergo magnetic ordering and exhibits heavy fermion behavior below 10 K. CaV{sub 2}O{sub 4} has an orthorhombic structure with the vanadium spins forming zigzag chains and has been suggested to be a model system to study the gapless chiral phase. These provide great motivation for further investigation of some known vanadium compounds as well as to explore new vanadium compounds in search of new physics. This thesis consists, in part, of experimental studies involving sample preparation and magnetic, transport, thermal, and x-ray measurements on some strongly correlated eletron systems containing the transition metal vanadium. The compounds studied are LiV{sub 2}O{sub 4}, YV{sub 4}O{sub 8}, and YbV{sub 4}O{sub 8}. The recent discovery of superconductivity in RFeAsO{sub 1-x}F{sub x} (R = La, Ce, Pr, Gd, Tb, Dy, Sm, and Nd), and AFe{sub 2}As{sub 2} (A = Ba, Sr, Ca, and Eu) doped with K, Na, or Cs at the A site with relatively high T{sub c} has sparked tremendous activities in the condensed matter physics community and a renewed interest in the area of superconductivity as occurred following the discovery of the layered cuprate high T{sub c} superconductors in 1986. To discover more superconductors with hopefully higher T{sub c}'s, it is extremely important to investigate compounds having crystal structures related to the compounds showing high T{sub c} superconductivity. Along with the vanadium oxide compounds described before, this thesis describes our investigations of magnetic, structural, thermal and transport properties of EuPd{sub 2}Sb{sub 2} single crystals which have a crystal structure closely related to the AFe{sub 2}As{sub 2} compounds and also a study of the reaction kinetics of the formation of LaFeAsO{sub 1-x}F{sub x}.

Das, Supriyo

2010-05-16

324

Transition-metal-catalyzed oxidation of metallic Sn in NiO/SnO2 nanocomposite.  

PubMed

It is well accepted that metallic tin as a discharge (reduction) product of SnO(x) cannot be electrochemically oxidized below 3.00?V versus Li(+)/Li(0) due to the high stability of Li2O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni2 SnO4 and NiO/SnO2 nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to SnO2 below 3.00?V. As a result, the reversible lithium-storage capacities of the nanocomposite reach 970?mAh?g(-1) or above, much higher than the theoretical capacity (ca. 750?mAh?g(-1)) of SnO2, NiO, or their composites. These findings extend the well-known electrochemical conversion reaction to non-transition-metal compounds and may have important applications, for example, in constructing high-capacity electrode materials and efficient catalysts. PMID:24648283

Hua, Chunxiu; Fang, Xiangpeng; Wang, Zhaoxiang; Chen, Liquan

2014-04-25

325

Coupling characteristics of thin-film metal-oxide-metal diodes at 10.6 microns  

NASA Technical Reports Server (NTRS)

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.

Wang, S. Y.; Gustafson, T. K.; Izawa, T.

1975-01-01

326

Surface plasmon dispersion analysis in the metal-oxide-metal tunnel diode  

NASA Technical Reports Server (NTRS)

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.

Donohue, J. F.; Wang, E. Y.

1987-01-01

327

Oxide Reduction in Advanced Metal Stacks for Microelectronic Applications Wentao Qin, Alex A. Volinsky1  

E-print Network

Oxide Reduction in Advanced Metal Stacks for Microelectronic Applications Wentao Qin, Alex A used for microelectronic interconnect applications. Interfacial oxides can cause device performance degradation and failure by significantly increasing electrical resistance. Interfacial oxide layers found

Volinsky, Alex A.

328

Effect of metal catalyzed oxidation in recombinant viral protein assemblies  

PubMed Central

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 oxidation in protein assembly is studied, evidencing that oxidation should be minimized during the production process if VP6 nanotubes are required. PMID:24533452

2014-01-01

329

Electronic entanglement in late transition metal oxides  

E-print Network

Here we present a study of the entanglement in the electronic structure of the late transition metal monoxides - MnO, FeO, CoO, and NiO - obtained by means of density-functional theory in the local density approximation combined with dynamical mean-field theory (LDA+DMFT). The impurity problem is solved through Exact Diagonalization (ED), which grants full access to the thermally mixed many-body ground state density operator. The quality of the electronic structure is affirmed through a direct comparison between the calculated electronic excitation spectrum and photoemission experiments. Our treatment allows for a quantitative investigation of the entanglement in the electronic structure. Two main sources of entanglement are explicitly resolved through the use of a fidelity based geometrical entanglement measure, and additional information is gained from a complementary entropic entanglement measure. We show that the interplay of crystal field effects and Coulomb interaction causes the entanglement in CoO to take a particularly intricate form.

Patrik Thunström; Igor Di Marco; Olle Eriksson

2013-01-28

330

Reactions of metal ions at surfaces of hydrous iron oxide  

USGS Publications Warehouse

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.

Hem, J.D.

1977-01-01

331

Open layers based on metal-oxide chains linked by cyclohexanedicarboxylate ligands  

E-print Network

Open layers based on metal-oxide chains linked by cyclohexanedicarboxylate ligands Inn Hoe Kim a]. The coordination polymers, or metal organic frame- works (MOFs), are composed of isolated metal atoms or clusters of the inorganic units. We have been interested in MOOFs based on infinite metal-oxide chains cross

Wang, Xiqu

332

Rapid and continuous hydrothermal crystallization of metal oxide particles in supercritical water  

Microsoft Academic Search

This paper reports on hydrolysis of 10 metal salt aqueous solutions of 6 metal oxides that was conducted in supercritical water. Continuous and rapid production of metal oxide fine particles was achieved by mixing a metal salt aqueous solution with preheated water fed from another line. The reaction time required was less than 2 min. Particle size, morphology, and crystal

Tadafumi Adschiri; Katsuhito Kanazawa; Kunio Arai

1992-01-01

333

Influence of uranium hydride oxidation on uranium metal behaviour  

SciTech Connect

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)

Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

2013-07-01

334

Quantum chemical simulations of atomic layer deposition of metal oxides and metal nitrides  

NASA Astrophysics Data System (ADS)

Scaling of SiO2 gate dielectrics to extend the miniaturization of complementary metal oxide semiconductor (CMOS) devices in accordance with Moore's Law has resulted in unacceptable tunneling current leakage levels. The projection that this challenge could significantly limit CMOS performance has prompted the intense search for alternative gate dielectric materials that can achieve high capacitances with physically thicker films which minimize tunneling leakage current. Atomic layer deposition is an ideal deposition method for high-k films because it controls the film thickness with atomic layer precision and can achieve high film conformality and uniformity. We use density functional theory (DFT) to explore chemical reactions involved in ALD processes at the atomic level. We have investigated different metal precursors for ALD process. Compared to halides, metal alkylamides are more favorable on nitrided silicon surfaces and subsequent film growth. Likewise, hafnium alkylamide is more favorable than water to initiate the nucleation on hydrogen terminated silicon surfaces. For deposition on organic self-assembled monolayers, different end groups significantly affect the selectivity towards ALD reactions. The chemical mechanisms involved in ALD of hafnium nitride, aluminum nitride are developed which provide an understanding to the difficulty in producing oxygen free metal nitrides by ALD. By combining ALD of metal oxide and metal nitride, a new method for incorporating nitrogen into oxide films is proposed. In TMA and ozone reaction, it's found that by-product water can be a catalyzer for this reaction.

Xu, Ye

335

Microelectronic components and metallic oxide studies and applications  

NASA Technical Reports Server (NTRS)

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.

Williams, L., Jr.

1976-01-01

336

Metal-Induced Oxidative Stress and Plant Mitochondria  

PubMed Central

A general status of oxidative stress in plants caused by exposure to elevated metal concentrations in the environment coincides with a constraint on mitochondrial electron transport, which enhances ROS accumulation at the mitochondrial level. As mitochondria are suggested to be involved in redox signaling under environmental stress conditions, mitochondrial ROS can initiate a signaling cascade mediating the overall stress response, i.e., damage versus adaptation. This review highlights our current understanding of metal-induced responses in plants, with focus on the production and detoxification of mitochondrial ROS. In addition, the potential involvement of retrograde signaling in these processes will be discussed. PMID:22072926

Keunen, Els; Remans, Tony; Bohler, Sacha; Vangronsveld, Jaco; Cuypers, Ann

2011-01-01

337

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...

338

Hydrogen generation using sodium borohydride solution and metal catalyst coated on metal oxide  

Microsoft Academic Search

Sodium borohydride (NaBH4) reacted slowly with water to liberate 4mol of hydrogen\\/mol of the compound at room temperature. Hydrogen generation was accelerated by applying metal–metal oxide catalysts such as Pt–TiO2, Pt–CoO and Pt–LiCoO2. As the metal crystallites size decreased and the amount increased, the hydrogen generation rate increased. It was indicated that the hydrogen generation rates using Pt and LiCoO2

Yoshitsugu Kojima; Ken-ichirou Suzuki; Kazuhiro Fukumoto; Megumi Sasaki; Toshio Yamamoto; Yasuaki Kawai; Hiroaki Hayashi

2002-01-01

339

Single-Crystal-like Nanoporous Spinel Oxides: A Strategy for Synthesis of Nanoporous Metal Oxides Utilizing Metal-Cyanide Hybrid Coordination Polymers.  

PubMed

Development of a new method to synthesize nanoporous metal oxides with highly crystallized frameworks is of great interest because of their wide use in practical applications. Here we demonstrate a thermal decomposition of metal-cyanide hybrid coordination polymers (CPs) to prepare nanoporous metal oxides. During the thermal treatment, the organic units (carbon and nitrogen) are completely removed, and only metal contents are retained to prepare nanoporous metal oxides. The original nanocube shapes are well-retained even after the thermal treatment. When both Fe and Co atoms are contained in the precursors, nanoporous Fe?Co oxide with a highly oriented crystalline framework is obtained. On the other hand, when nanoporous Co oxide and Fe oxide are obtained from Co- and Fe-contacting precursors, their frameworks are amorphous and/or poorly crystallized. Single-crystal-like nanoporous Fe?Co oxide shows a stable magnetic property at room temperature compared to poly-crystalline metal oxides. We further extend this concept to prepare nanoporous metal oxides with hollow interiors. Core-shell heterostructures consisting of different metal-cyanide hybrid CPs are prepared first. Then the cores are dissolved by chemical etching using a hydrochloric acid solution (i.e., the cores are used as sacrificial templates), leading to the formation of hollow interiors in the nanocubes. These hollow nanocubes are also successfully converted to nanoporous metal oxides with hollow interiors by thermal treatment. The present approach is entirely different from the surfactant-templating approaches that traditionally have been utilized for the preparation of mesoporous metal oxides. We believe the present work proves a new way to synthesize nanoporous metal oxides with controlled crystalline frameworks and architectures. PMID:25359496

Zakaria, Mohamed B; Hu, Ming; Imura, Masataka; Salunkhe, Rahul R; Umezawa, Naoto; Hamoudi, Hicham; Belik, Alexei A; Yamauchi, Yusuke

2014-12-22

340

Multichannel multiphoton imaging of metal oxides nanoparticles in biological system  

NASA Astrophysics Data System (ADS)

Near-IR ultrafast pulse laser and confocal microscope are combined to create a multiphoton multichannel non-linear imaging technique, which allows in situ 3-D characterization of nonfluorescent nanoparticles in biological systems. We observed intense CARS signals generated from various metal oxides due to their high third-order nonlinear susceptibilities (Chi(3)), which do not depend on the vibrational resonance but on the electronic resonance. We show that fine and ultrafine particles of metal oxides in alveolar macrophage cells may be imaged in vitro using CARS and multiphoton fluorescence microscopy with highest optical resolution for extended periods without photobleaching effects. The advantage of the epi-detection over the forward detection for imaging sub-micron particles has been investigated.

Zheng, Yuangang; Holtom, Gary; Colson, Steven D.

2004-06-01

341

Facile synthesis of metal oxide\\/reduced graphene oxide hybrids with high lithium storage capacity and stable cyclability  

Microsoft Academic Search

We report an environment-friendly approach to synthesize transition metal oxide nanoparticles (NPs)\\/reduced graphene oxide (rGO) sheets hybrids by combining the reduction of graphene oxide (GO) with the growth of metal oxide NPs in one step. Either Fe2O3 or CoO NPs were grown onto rGO sheets in ethanol solution through a solvothermal process, during which GOs were reduced to rGO without

Jixin Zhu; Ting Zhu; Xiaozhu Zhou; Yanyan Zhang; Xiong Wen Lou; Xiaodong Chen; Hua Zhang; Huey Hoon Hng; Qingyu Yan

2011-01-01

342

Structural analysis of a binary metallic glass model. A study of Pd1-xSix alloys (+)  

E-print Network

, the starting configurations are constructed either by a substitutional or an interstitial method. The state243 Structural analysis of a binary metallic glass model. II. 2014 A study of Pd1-xSix alloys (+) F pour proches voisins. Abstract. 2014 We analyse several amorphous Pd1-xSix alloys obtained

Boyer, Edmond

343

CMOS Monolithic Metal–Oxide Gas Sensor Microsystems  

Microsoft Academic Search

This paper presents two mixed-signal monolithic gas sensor microsystems fabricated in standard 0.8-$muhbox m$CMOS technology combined with post-CMOS micromachining to form the microhotplates. The on-chip microhotplates provide very high temperatures (between 200$^circ$C and 400$^circ$C), which are necessary for the normal operation of metal–oxide sensing layers. The first microsystem has a single-ended architecture comprising a microhotplate (diameter of 300$muhbox m$) and

Diego Barrettino; Markus Graf; Stefano Taschini; Sadik Hafizovic; Christoph Hagleitner; Andreas Hierlemann

2006-01-01

344

Micromachined metal oxide gas sensors: opportunities to improve sensor performance  

Microsoft Academic Search

This review deals with gas sensors combining a metal oxide based sensing layer and a substrate realized by using micromachining. It starts by giving an overview of the design principles and technology involved in the fabrication of micromachined substrates examining thermal and mechanical aspects. Both kinds of micromachined substrates, closed-membrane-type and the suspended-membrane-type, are discussed. The deposition of the sensing

Isolde Simon; Nicolae Bârsan; Michael Bauer; Udo Weimar

2001-01-01

345

Hydrothermal Synthesis of Metal Oxide Nanoparticles at Supercritical Conditions  

Microsoft Academic Search

Hydrothermal synthesis of CeO2 and AlO(OH) were conducted using a flow type apparatus over the range of temperature from 523 to 673 K at 30 MPa. Nanosize crystals were formed at supercritical conditions. The mechanism of nanoparticle formation at supercritical conditions was discussed based on the metal oxide solubility and kinetics of the hydrothermal synthesis reaction. The reaction rate of

Tadafumi Adschiri; Yukiya Hakuta; Kiwamu Sue; Kunio Arai

2001-01-01

346

Didactic simulation of a metal oxide semiconductor structure  

Microsoft Academic Search

In this paper, we present an interactive simulation of a Metal-Oxide-Semiconductor structure, based on a qualitative approach. The code is written in ActionScript\\/Flash to enjoy all the benefits of this technology in the multimedia field. In addition, our simulation combines theoretical and practical concepts on the same graphical interface: it shows the impact of physical and electrical parameters on the

Hamid Magrez; K. Kassmi; A. Ziyyat

2009-01-01

347

Pressure vessel construction for a metal oxide-hydrogen battery  

SciTech Connect

This patent describes a metal oxide-hydrogen battery. It comprises: an outer vessel, a battery cell disposed within the vessel, the vessel including a flexible inner liner of a material impervious to the passage of hydrogen gas, and an outer layer of fiber reinforced resin disposed in contact with the inner liner, a fitting disposed within an opening in a wall of the vessel and having an opening therethrough, and sealing means for sealing the inner liner to the fitting.

Jones, K.R.; Sindorf, J.F.

1990-05-08

348

For cermet inert anode containing oxide and metal phases useful for the electrolytic production of metals  

DOEpatents

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.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Douglas A. (Murrysville, PA)

2002-01-01

349

Optical properties of transition metal oxide quantum wells  

NASA Astrophysics Data System (ADS)

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.

Lin, Chungwei; Posadas, Agham; Choi, Miri; Demkov, Alexander A.

2015-01-01

350

Engineering metal oxide nanostructures for the fiber optic sensor platform.  

PubMed

This paper presents an effective integration scheme of nanostructured SnO2 with the fiber optic platform for chemical sensing applications based on evanescent optical interactions. By using a triblock copolymer as a structure directing agent as the means of nano-structuring, the refractive index of SnO2 is reduced from >2.0 to 1.46, in accordance with effective medium theory for optimal on-fiber integration. High-temperature stable fiber Bragg gratings inscribed in D-shaped fibers were used to perform real-time characterization of optical absorption and refractive index modulation of metal oxides in response to NH3 from the room temperature to 500 °C. Measurement results reveals that the redox reaction of the nanostructured metal oxides exposed to a reactive gas NH3 induces much stronger changes in optical absorption as opposed to changes in the refractive index. Results presented in this paper provide important guidance for fiber optic chemical sensing designs based on metal oxide nanomaterials. PMID:24663558

Poole, Zsolt L; Ohodnicki, Paul; Chen, Rongzhang; Lin, Yuankun; Chen, Kevin P

2014-02-10

351

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

SciTech Connect

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 length while keeping the corresponding island width constant. Third, LEED indicates that, up to about 6 BL (12 ML), the Ag film adopts the (110) structure on lattice matched NiAl(110) surface, supporting the previous assignment based upon island heights measured in STM. Starting at 4.5 to 6 BL, (111) diffraction pattern is detected. This is also in agreement with previous STM study. Careful examinations of the LEED patterns reveal the slight difference in lattice constants between bulk Ag and bulk NiAl. At last, we performed STM studies of Ni deposition on NiAl(110) in the temperature range from 200 K to 400 K. Ni forms 'dense' Ni(100)-like islands on NiAl(110) with a zig-zag shaped stripe feature which is probably due to strain relief. DFT analysis provides insights into the island growth shapes, which are rationalized by the thermodynamics and kinetics of the film growth process. For thick Ni films (coverage exceeding 6 ML), a Ni(111)-like structure developed. Traditional MF theory is applied to analyze island density at 200 K. Deviation from homogeneous nucleation behavior for island size distribution and island density reveals the presence of heterogeneous nucleation mediated by the Ni antisite point defects on NiAl(110) surface.

Jing, Dapeng

2010-12-15

352

The Development of Metal Oxide Chemical Sensing Nanostructures  

NASA Technical Reports Server (NTRS)

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.

Hunter, G. W.; VanderWal,R. L.; Xu, J. C.; Evans, L. J.; Berger, G. M.; Kulis, M. J.

2008-01-01

353

Lithium Metal Oxide Electrodes For Lithium Cells And Batteries  

DOEpatents

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.

Thackeray, Michael M. (Naperville, IL); Johnson, Christopher S. (Naperville, IL); Amine, Khalil (Downers Grove, IL); Kim, Jaekook (Naperville, IL)

2004-01-20

354

Lithium metal oxide electrodes for lithium cells and batteries  

DOEpatents

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.

Thackeray, Michael M. (Naperville, IL); Johnson, Christopher S. (Naperville, IL); Amine, Khalil (Oakbrook, IL)

2008-12-23

355

Thermodynamic properties of some metal oxide-zirconia systems  

NASA Technical Reports Server (NTRS)

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.

Jacobson, Nathan S.

1989-01-01

356

Modeling and experimental studies of oxide covered metal surfaces  

SciTech Connect

The collaborative research effort of the Aqueous Group of the Corrosion Research Center has focussed on the physical, chemical, and electronic structure of native and anodically grown TiO{sub 2} films. The stability of Ti in corrosive environments is due entirely to the presence of the oxide film; thus, our goal is to correlate measurable structural parameters of the oxide film with the corrosion resistance that it imparts to the base metal. The fundamental nature of both theoretical and experimental approaches taken in studying TiO{sub 2} films will allow key factors underlying oxide film stability to be identified and translated to other materials. 44 refs., 1 tab., 7 figs.

Smyrl, W.H.; Halley, J.W.; Oriani, R.A.; White, H.S. (Minnesota Univ., Minneapolis, MN (USA). Corrosion Research Center); Toney, M.F.; Melroy, O.R. (International Business Machines Corp., Armonk, NY (USA))

1990-01-01

357

Developmental phytotoxicity of metal oxide nanoparticles to Arabidopsis thaliana.  

PubMed

Phytotoxicity is an important consideration to understand the potential environmental impacts of manufactured nanomaterials. Here, we report on the effects of four metal oxide nanoparticles, aluminum oxide (nAl(2)O(3)), silicon dioxide (nSiO(2)), magnetite (nFe(3)O(4)), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). Three toxicity indicators (seed germination, root elongation, and number of leaves) were quantified following exposure to each nanoparticle at three concentrations: 400, 2,000, and 4,000 mg/L. Among these particles, nZnO was most phytotoxic, followed by nFe(3)O(4), nSiO(2), and nAl(2)O(3), which was not toxic. Consequently, nZnO was further studied to discern the importance of particle size and zinc dissolution as toxicity determinants. Soluble zinc concentrations in nanoparticle suspensions were 33-fold lower than the minimum inhibitory concentration of dissolved zinc salt (ZnCl(2)), indicating that zinc dissolution could not solely account for the observed toxicity. Inhibition of seed germination by ZnO depended on particle size, with nanoparticles exerting higher toxicity than larger (micron-sized) particles at equivalent concentrations. Overall, this study shows that direct exposure to nanoparticles significantly contributed to phytotoxicity and underscores the need for eco-responsible disposal of wastes and sludge containing metal oxide nanoparticles. PMID:20821493

Lee, Chang Woo; Mahendra, Shaily; Zodrow, Katherine; Li, Dong; Tsai, Yu-Chang; Braam, Janet; Alvarez, Pedro J J

2010-03-01

358

Custom-designed nanomaterial libraries for testing metal oxide toxicity  

PubMed Central

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

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

2014-01-01

359

Diffusion reactions at metal-oxide interfaces and the effect of an applied electric field  

Microsoft Academic Search

Metal-oxide interfaces play a major role in a variety of applications, such as packaging for electronic devices, oxide-dispersion-strengthening of alloys, and thermal barrier coatings. For many of these applications, it would be a great advantage if it was possible to engineer the mechanical properties of metal-oxide interfaces. The present thesis describes experiments I have carried out on a model metal-oxide

Yeonseop Yu

2005-01-01

360

Hydrocracking and hydroisomerization of long-chain alkanes and polyolefins over metal-promoted anion-modified transition metal oxides  

SciTech Connect

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.

Venkatesh, Koppampatti R.; Hu, Jianli; Tierney, John W.; Wender, Irving

1996-12-01

361

Hydrocracking and hydroisomerization of long-chain alkanes and polyolefins over metal-promoted anion-modified transition metal oxides  

DOEpatents

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.

Venkatesh, Koppampatti R. (Pittsburgh, PA); Hu, Jianli (Cranbury, NJ); Tierney, John W. (Pittsburgh, PA); Wender, Irving (Pittsburgh, PA)

2001-01-01

362

Mercury Removal from Aqueous Systems Using Commercial and Laboratory Prepared Metal Oxide Nanoparticles  

E-print Network

of arsenic. The other oxides which have shown promising results for arsenic removal include the nanoparticles of copper ox- ide [23], titanium dioxide [24],[25],[26],iron-titanium binary mixed oxide [27], humic acid coated iron oxide [28] and cerium doped... iron oxide [29]. Successful attempts have been also made to remove chromium (using nanoscale surface modi ed jacobsite [30], maghemite [31], akaganeite [32]), lead (using nanoscale titanium dioxide [33], zero-valent iron [34] and nanoscale chitosan [35...

Desai, Ishan

2010-10-12

363

Aluminum oxide coating on nickel substrate by metal organic chemical vapor deposition  

Microsoft Academic Search

Aluminum oxide thin films were coated onto nickel substrates via chemical vapor deposition. The aluminum oxide was produced by pyrolysis of a metal acetylacetonate precursor. This reaction was done at relatively low temperatures, from 435 to 550 °C to deposit a thin film of aluminum oxide. The coating provided protection against isothermal oxidation at elevated temperatures. Resistance to oxidation was

Jun Nable; Malgorzata Gulbinska; Steven L Suib; Francis Galasso

2003-01-01

364

Thin Films of Metal Oxides on Metal Single Crystals: Structure and Growth by Scanning Tunneling Microscopy  

NASA Astrophysics Data System (ADS)

Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(111) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing the structures of different oxides. For the iron oxide system the first monolayer grows as FeO(111) with a lateral lattice constant of 3.09 +/- 0.02 A as compared to the bulk value of 3.04 A. The surface is oxygen terminated with a strongly contracted FeO bond distance of 1.90 A as compared to the bulk value of 2.15 A. At higher coverages Fe _3O_4(111) and alpha-Fe_2rm O_3 (0001) structures can be identified by their symmetry with respect to the FeO monolayer. The Fe_3 O_4(111) has a simple 2 x 2 unit cell and the alpha-Fe _2O_3(0001) is surd3 x surd3R30 ^circ. The FeO(111) exhibits a large three fold symmetric unit cell (26 A) due to the lattice mismatch with the Pt(111) surface and the alpha -Fe_2O_3(0001) has an even larger unit cell (43 A) due to the lattice mismatch with the FeO monolayer. The large unit cells are images as Moire patterns (modulations in the average current and atomic corrugation) in the STM images. For titanium oxide the first monolayer grows as Ti _2O_3(0001) under reducing conditions and TiO_2(111) structures are formed at higher oxygen pressures and higher coverages. Both ordered structures also exhibit Moire pattern images in the STM experiments. A second goal of these studies is to advance the understanding of the tunneling process in metal oxides and to better determine the relationship between the experimental STM results and the surface atomic positions. For this purpose Electron Scattering Quantum Chemistry (ESQC) calculations have been applied to the case of an FeO monolayer on Pt(111) to simulate the experimental images. The correspondence between surface structure and STM image features has been determined. In particular, the maxima observed in the experimental images spaced by 3.1 A are due to the positions of the oxygen atoms. The atomic corrugation has a simple relationship with the tip-surface distance and therefore with the surface buckling. Namely, the atomic corrugation increases with decreasing tip-surface distance. However, there is no simple relationship between the average tunneling current and topography. This is the first calculation of an STM image for a metal oxide surface as well as the first STM modeling of a Moire structure. Other studies include an investigation of the coadsorption of oxygen and sulfur on the Ni(110) surface. The results of the coadsorption experiments will be included in the last chapter. Further STM calculations using the ESQC method to compare the chemisorbed oxygen system to the metal oxide structures would enhance the understanding of tunneling in metal-oxygen systems.

Galloway, Heather Claire

1995-11-01

365

Characterization, sorption, and exhaustion of metal oxide nanoparticles as metal adsorbents  

NASA Astrophysics Data System (ADS)

Safe drinking water is paramount to human survival. Current treatments do not adequately remove all metals from solution, are expensive, and use many resources. Metal oxide nanoparticles are ideal sorbents for metals due to their smaller size and increased surface area in comparison to bulk media. With increasing demand for fresh drinking water and recent environmental catastrophes to show how fragile water supplies are, new approaches to water conservation incorporating new technologies like metal oxide nanoparticles should be considered as an alternative method for metal contaminant adsorbents from typical treatment methods. This research evaluated the potential of manufactured iron, anatase, and aluminum nanoparticles (Al2O3, TiO2, Fe2O3) to remove metal contaminants (Pb, Cd, Cu, Ni, Zn) in lab-controlled and natural waters in comparison to their bulk counterparts by focusing on pH, contaminant and adsorbent concentrations, particle size, and exhaustive capabilities. Microscopy techniques (SEM, BET, EDX) were used to characterize the adsorbents. Adsorption experiments were performed using 0.01, 0.1, or 0.5 g/L nanoparticles in pH 8 solution. When results were normalized by mass, nanoparticles adsorbed more than bulk particles but when surface area normalized the opposite was observed. Adsorption was pH-dependent and increased with time and solid concentration. Aluminum oxide was found to be the least acceptable adsorbent for the metals tested, while titanium dioxide anatase (TiO2) and hematite (alpha-Fe2O3) showed great ability to remove individual and multiple metals from pH 8 and natural waters. Intraparticle diffusion was likely part of the complex kinetic process for all metals using Fe2O3 but not TiO 2 nanoparticles within the first hour of adsorption. Adsorption kinetics for all metals tested were described by a modified first order rate equation used to consider the diminishing equilibrium metal concentrations with increasing metal oxides, showing faster adsorption rates for nanoparticles compared to bulk particles. Isotherms were best fit with most correlations of r=0.99 or better using the Langmuir-Freundlich equation which describes a heterogeneous surface with monolayer adsorption. Calculated rate constants and distribution coefficients (Kd) showed TiO2 nanoparticles were very good sorbents and more rapid in removing metals than other nanoparticles studied here and reported in the literature. Desorption studies concluded Pb, Cd, and Zn appear to be irreversibly sorbed to TiO2 surfaces at pH 8. TiO2 and Fe2O3 nanoparticles were capable of multiple metal loadings, with exhaustion for both adsorbents at pH 6. Exhaustion studies at pH 8 showed hematite exhausted after four consecutive cycles while anatase showed no exhaustion after 8 cycles. Their bulk counterparts exhausted in earlier cycles indicating the lack of ability to adsorb much of the multiple metals in solution. The increased surface area of TiO2 and Fe 2O3 nanoparticles, coupled with strong adsorption at the pH of most natural waters and resistance to desorption of some metals, may offer a potential remediation method for removal of metals from water in the future.

Engates, Karen Elizabeth

366

Effect of metallicity on the gravitational-wave signal from the cosmological population of compact binary coalescences  

NASA Astrophysics Data System (ADS)

Context. Recent studies on stellar evolution have shown that the properties of compact objects strongly depend on the metallicity of the environment in which they were formed. Aims: Using some very simple assumptions on the metallicity of the stellar populations, we explore how this property affects the unresolved gravitational-wave background from extragalactic compact binaries. Methods: We obtained a suit of models using population synthesis code, estimated the gravitational-wave background they produce, and discuss its detectability with second- (advanced LIGO, advanced Virgo) and third- (Einstein Telescope) generation detectors. Results: Our results show that the background is dominated by binary black holes for all considered models in the frequency range of terrestrial detectors, and that it could be detected in most cases by advanced LIGO/Virgo, and with Einstein Telescope with a very high signal-to-noise ratio. The observed peak in a gravitational-wave spectrum depends on the metallicity of the stellar population.

Kowalska-Leszczynska, I.; Regimbau, T.; Bulik, T.; Dominik, M.; Belczynski, K.

2015-02-01

367

Precise Atmospheric Parameters for the Shortest-period Binary White Dwarfs: Gravitational Waves, Metals, and Pulsations  

NASA Astrophysics Data System (ADS)

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 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. Based on observations obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

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

2014-10-01

368

Interatomic potentials of the binary transition metal systems and some applications in materials physics  

NASA Astrophysics Data System (ADS)

The present article focuses on a discussion concerning the concept, method and detailed construction procedure of seven interatomic potentials currently available for fcc, bcc and hcp transition metals and their binary alloys. The potentials include the embedded atom method potential and its modified version, in which the cross-potential takes a three-parameter linear function, the second-moment approximation of tight-binding potential and its smoothed version, in which a truncation function is incorporated to improve the performance, the Finnis-Sinclair potential and its extended version, in which the atomic interaction is strengthened, and the recently proposed long-range empirical potential. Meanwhile, an important method, i.e.ab initio assisted construction of interatomic potentials, is introduced and the method is necessary whenever the physical data are lacking in fitting potentials. Moreover, applications of some twenty constructed potentials for studying materials science related issues are presented, such as the structural phase transitions, characteristics of metastable alloys, atomic structure of metallic glasses, and solid-state interfacial reaction/amorphization.

Li, J. H.; Dai, X. D.; Liang, S. H.; Tai, K. P.; Kong, Y.; Liu, B. X.

2008-01-01

369

Improved electrochemical biosensor response via metal oxide pre-oxidation of chemical interferents  

NASA Astrophysics Data System (ADS)

Typical biological samples are inherently complicated. They may contain a myriad of compounds that are electroactive at the same potential as that used in many electrochemical biosensors. Therefore, a biosensor design feature must be included that either eliminates or blocks the interferents from generating false positive signals. The ability to use an insoluble compound, that of MnO II, in order to oxidize interferents such as ascorbic acid, acetaminophen and uric acid, was investigated in a prototype sensor system at a bias potential of 0.6 V versus Ag/AgCl. Unlike previous work with these materials, a difference between the ability for the metal oxide to oxidize the interferents was observed. Most effective was the capability of MnO II to oxidize uric acid. Alternatively, the MnO II had little effect on acetaminophen. The study is both introduced and results are discussed within the context of an implantable glucose sensor.

Houseknecht, Jamie G.; Tapsak, Mark A.

2007-09-01

370

Synthesis of mesoporous metal oxide by the thermal decomposition of oxalate precursor.  

PubMed

A synthesis method was newly developed to prepare mesoporous transition metal oxides by thermal decomposition of transition metal oxalates, and the method was advantageous in its versatility, low cost, and environmental friendliness. Various mesoporous transition metal oxides were successfully synthesized by the newly developed method, such as magnetic ?-Fe2O3, CoFe2O4, and NiFe2O4, MnxOy, Co3O4, and NiO. Morphology, structure, and magnetic property of the synthesized mesoporous transition metal oxides were characterized by XRD, TG-DTA, SEM, TEM, quantum design SQUID, and N2 sorption techniques. From the dependency of the heating rate, calcination time, and calcination temperature on the metal oxide structures, it was revealed that the calcination temperature was the major factor to determine the final mesoporous structure of the metal oxides. The mesoporous structures were well constructed by their corresponding metal oxide nanoparticles resulting from oxalate thermal decomposition. PMID:23480232

Guo, Limin; Arafune, Hiroyuki; Teramae, Norio

2013-04-01

371

Preparation of Binary and Ternary Oxides by Molten Salt Method and its Electrochemical Properties  

NASA Astrophysics Data System (ADS)

We report simple binary oxides namely SnO2, TiO2, CuO, MnO2, Fe2O3, Co3O4 and ternary oxides like MnCo2O4 by molten salt method at a temperature range of 280°C to 950°C in air and discuss the effect of morphology, crystal structure and electrochemical properties of binary and ternary oxides. Materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area methods. XRD patterns showed all MSM prepared materials exhibited characteristic lattice parameter values. BET surface area varies depending on the nature of the material, molten salt and preparation temperature and the obtained values are in the range, 1 to 160 m2/g. Electrochemical properties were studied using cyclic voltammetry (CV) and electrochemical performance studies were carried in the voltage range, 0.005-1.0V for SnO2, 1.0-2.8V for TiO2 and Fe2O3, MCo2O4 (M = Co, Mn), MnO2 and CuO were cycled in the range, 0.005-3.0V. At a current rates of 30-100 mA/g and a scan rate of 0.058 mV/sec was used for galvanostatic cycling and cyclic voltammetry. SnO2 showed that an alloying-de-alloying reaction occurs at ˜0.2 and ˜0.5 V vs. Li. TiO2 main intercalation and de-interaction reactions at ˜1.7 and ˜1.8 V vs. Li. Co3O4, MnCo2O4, and MnO2 main discharge potentials at ˜1.2, 0.9V and 0.4V, resp. and charge potentials peak ˜2.0V and 1.5V vs. Li. CuO prepared at 750°C exhibited main anodic peak at ˜2.45V and cathodic peaks at ˜0.85V and ˜1.25V. We discussed the possible reaction mechanisms and Li-storage performance values in detail.

Reddy, M. V.; Theng, L. Pei; Soh, Hulbert; Beichen, Z.; Jiahuan, F.; Yu, C.; Ling, A. Yen; Andreea, L. Y.; Ng, C. H. Justin; Liang, T. J. L. Galen; Ian, M. F.; An, H. V. T.; Ramanathan, K.; Kevin, C. W. J.; Daryl, T. Y. W.; Hao, T. Yi; Loh, K. P.; Chowdari, B. V. R.

2013-07-01

372

Magnetic preferential orientation of metal oxide superconducting materials  

DOEpatents

A superconductor comprised of a polycrystalline metal oxide such as YBa[sub 2]Cu[sub 3]O[sub 7[minus]X] (where 0 < X < 0.5) exhibits superconducting properties and is capable of conducting very large current densities. By aligning the two-dimensional Cu-O layers which carry the current in the superconducting state in the a- and b-directions, i.e., within the basal plane, a high degree of crystalline axes alignment is provided between adjacent grains permitting the conduction of high current densities. The highly anisotropic diamagnetic susceptibility of the polycrystalline metal oxide material permits the use of an applied magnetic field to orient the individual crystals when in the superconducting state to substantially increase current transport between adjacent grains. In another embodiment, the anisotropic paramagnetic susceptibility of rare-earth ions substituted into the oxide material is made use of as an applied magnetic field orients the particles in a preferential direction. This latter operation can be performed with the material in the normal (non-superconducting) state. 4 figs.

Capone, D.W.; Dunlap, B.D.; Veal, B.W.

1990-07-17

373

'Shape effects' in metal oxide supported nanoscale gold catalysts.  

PubMed

We report the activity of shape-controlled metal oxide (CeO(2), ZnO and Fe(3)O(4)) supported gold catalysts for the steam reforming of methanol (SRM) and the water gas shift (WGS) reactions. Metal oxide nanoshapes, prepared by controlled hydrolysis and thermolysis methods, expose different crystal surfaces, and consequently disperse and stabilize gold differently. We observe that similar to gold supported on CeO(2) shapes exposing the {110} and {111} surfaces, gold supported on the oxygen-rich ZnO {0001} and Fe(3)O(4) {111} surfaces shows higher activity for the SRM and WGS reactions. While the reaction rates vary among the Au-CeO(2), Au-ZnO and Au-Fe(3)O(4) shapes, the apparent activation energies are similar, indicating a common active site. TPR data further indicate that the reaction lightoff coincides with the activation of Au-O-M species on the surface of all three oxide supports evaluated here. Different shapes contain a different number of binding sites for the gold, imparting different overall activity. PMID:21240451

Boucher, Matthew B; Goergen, Simone; Yi, Nan; Flytzani-Stephanopoulos, Maria

2011-02-21

374

[Synthesis and characterization of mixed metal oxide pigments].  

PubMed

In the present work, aluminum chloride and various soluble salts of doping ions were dissolved in water. In addition, urea and polyvinyl pyrrolidone (PVP) were also dissolved in the above aqueous solution under supersonic treatments. Then the solutions were heated to induce the hydrolysis of urea so that soluble aluminum and doping ions convert into insoluble hydroxide or carbonate gels. After calcinations, the obtained gels change to mixed metal oxide pigments whose color is related to type and concentrations of the doping ions. XRD characterization demonstrates that the diffraction patterns of the products are the same as that of alpha-alumina. Diffuse reflectance spectra of samples of the samples in UV-Vis regions show that the absorption bands for d-d transitions of the doping ions undergo considerable change as the coordinate environments change. In addition, L*, a* and b* values of the pigments were measured by using UV-Vis densitometer. SEM results indicate that the size of the pigment powders is in the range 200-300 nm. The pigments are quite stable since no evidence of dissolution was observed after the synthesized pigment is soaked for 24 hours. ICP test shows that very little amount of doped metal occurs in the corresponding filtrate. The above results suggest that these new kinds of mixed metal oxide pigments are stable, non-toxic, environmental friendly and they may be applicable in molten spinning process and provide a new chance for non-aqueous printing and dyeing industry. PMID:22582641

Ding, Jie; Yue, Shi-juan; Liu, Cui-ge; Wei, Yong-ju; Meng, Tao; Jiang, Han-jie; Shi, Yong-zheng; Xu, Yi-zhuang; Yu, Jiang; Wu, Jin-guang

2012-03-01

375

Effects of semiconducting oxide films on the reflectivity change in a metal on radiation heating  

Microsoft Academic Search

The reflectivity of a metal heated by radiation in air may change on account of growth of the oxide film [I] and also because of diffusion of oxygen into the metal under the oxide [2]. Here we consider another physical factor that governs the energy deposition in the specimen, viz., the increase in the conductivity of the oxide with temperature.

A. V. Burmistrov

1982-01-01

376

Production of Oxygen Gas and Liquid Metal by Electrochemical Decomposition of Molten Iron Oxide  

E-print Network

advocated molten oxide elec- trolysis (MOE) as a carbon-free alternative to existing metals extrac- tionProduction of Oxygen Gas and Liquid Metal by Electrochemical Decomposition of Molten Iron Oxide of Resource and Environmental Sciences, Wuhan University, China Molten oxide electrolysis (MOE

Sadoway, Donald Robert

377

Understanding the NMR shifts in paramagnetic transition metal oxides using density functional theory calculations  

E-print Network

Understanding the NMR shifts in paramagnetic transition metal oxides using density functional­14 however, no such studies, to our knowledge, have been performed in transition metal oxides or other of the lithium local environment and electronic configuration of the transition metal ions. We focus

Ceder, Gerbrand

378

? and ? phases in binary rhenium-transition metal systems: a systematic first-principles investigation.  

PubMed

The Frank-Kasper phases, known as topologically close-packed (tcp) phases, are interesting examples of intermetallic compounds able to accommodate large homogeneity ranges by atom mixing on different sites. Among them, the ? and ? phases present two competing complex crystallographic structures, the stability of which is driven by both geometric and electronic factors. Rhenium (Re) is the element forming the largest number of binary ? and ? phases. Its central position among the transition metals in the periodic table plays an important role in the element ordering in tcp phases. Indeed, it has been shown that Re shows an opposite site preference depending on which elements it is alloyed with. In the present work, ?- and ?-phase stability in binary Re-X systems is systematically studied by a first-principles investigation. The heats of formation of the complete set of ordered configurations (16 for ? and 32 for ?) have been calculated in 16 well-chosen systems to identify stability criteria. They include not only the systems in which ?-Re-X (X = Ti, Mn, Zr, Nb, Mo, Hf, Ta, W) or ?-Re-X (X = V, Cr, Mn, Fe, Nb, Mo, Ta, W) exist but also the systems in which both phases are not stable, including systems in which X is a 3d element from Ti to Ni, a 4d element from Zr to Ru, and a 5d element from Hf to Os. Careful analysis is done of the energetic tendencies as a function of recomposition, size effect, and electron concentration. Moreover, the site preference and other crystallographic properties are discussed. Conclusions are drawn concerning the relative stability of the two phases in comparison with the available experimental knowledge on the systems. PMID:23477863

Crivello, Jean-Claude; Breidi, Abedalhasan; Joubert, Jean-Marc

2013-04-01

379

Liquid Metal/Metal Oxide Frameworks with Incorporated Ga2O3 for Photocatalysis.  

PubMed

Solvothermally synthesized Ga2O3 nanoparticles are incorporated into liquid metal/metal oxide (LM/MO) frameworks in order to form enhanced photocatalytic systems. The LM/MO frameworks, both with and without incorporated Ga2O3 nanoparticles, show photocatalytic activity due to a plasmonic effect where performance is related to the loading of Ga2O3 nanoparticles. Optimum photocatalytic efficiency is obtained with 1 wt % incorporation of Ga2O3 nanoparticles. This can be attributed to the sub-bandgap states of LM/MO frameworks, contributing to pseudo-ohmic contacts which reduce the free carrier injection barrier to Ga2O3. PMID:25543876

Zhang, Wei; Naidu, Boddu S; Ou, Jian Zhen; O'Mullane, Anthony P; Chrimes, Adam F; Carey, Benjamin J; Wang, Yichao; Tang, Shi-Yang; Sivan, Vijay; Mitchell, Arnan; Bhargava, Suresh K; Kalantar-Zadeh, Kourosh

2015-01-28

380

Characteristics of GaAs-anodic oxide metal-oxide-semiconductor solar cells  

SciTech Connect

Metal-oxide-semiconductor solar cells with reproducible photovoltaic characteristics have been fabricated on (n/sup +/) GaAs substrates employing an oxidation technique which combines an aqueous anodization method with a post-fabrication HC1 treatment. The cell typically displays an open-circuit voltage V/sub oc/ of the order of 0.59 V and a short-circuit current density J/sub sc/ of 13.65 mA/cm/sup 2/ under simulated AM1 illumination. An efficiency of 5.7 % has been achieved without antireflection coating.

Das, P.; Chakravarti, S.N.; Bhat, K.N.

1981-03-01

381

Interfacial oxide re-growth in thin film metal oxide III-V semiconductor systems  

SciTech Connect

The Al{sub 2}O{sub 3}/GaAs and HfO{sub 2}/GaAs interfaces after atomic layer deposition are studied using in situ monochromatic x-ray photoelectron spectroscopy. Samples are deliberately exposed to atmospheric conditions and interfacial oxide re-growth is observed. The extent of this re-growth is found to depend on the dielectric material and the exposure temperature. Comparisons with previous studies show that ex situ characterization can result in misleading conclusions about the interface reactions occurring during the metal oxide deposition process.

McDonnell, S.; Dong, H.; Hawkins, J. M.; Brennan, B.; Milojevic, M.; Aguirre-Tostado, F. S.; Zhernokletov, D. M.; Hinkle, C. L.; Kim, J.; Wallace, R. M.

2012-04-02

382

Effect of gate metal on chemical bonding state in metal/Pr-oxide/Ge gate stack structure  

NASA Astrophysics Data System (ADS)

We have investigated the impacts of the gate metal on the chemical bonding state in the metal/Pr-oxide/Ge gate stack structure by the hard X-ray photoelectron spectroscopy method and have tried to explain about the obtained results focusing on the difference of oxygen chemical potential (?O) among metal-oxide, Pr-oxide and Ge-oxide. The reductive character of the metals induces the reductive reaction of the Pr-oxide films. The reductive character changes the Pr valence state not only at the surface but also in the Pr-oxide films. The reductive character increases the ratio of Pr3+ to Pr4+ in the Pr-oxide films, suggesting the formation of the crystalline phase with high permittivity of h-Pr2O3. The reductive character of the metals also affects on the Pr-oxide/Ge interfacial structure. Besides it leads to the decrease in the amount of Ge atoms bonding with oxygen. These reductive reactions can be explained by ?O of the metals with reductive character lower than those of PrO2 formation and GeO2 formation. From the comparison of the results for the Ge and Si systems, it was found that the drawing reaction of oxygen, which means the pullout of oxygen in the Pr-oxide film, is facile for the Ge system, relating to ?O of GeO2 higher than that in SiO2. These results suggest that the selection of gate metals in the metal/Pr-oxide/Ge gate stack structure taking into account ?O is quite important to achieve the thin EOT, resulting in both the formation of the h-Pr2O3 crystalline phase of the Pr-oxide and the decrease in the amount of Ge-oxides.

Kato, Kimihiko; Sakashita, Mitsuo; Takeuchi, Wakana; Taoka, Noriyuki; Nakatsuka, Osamu; Zaima, Shigeaki

2013-05-01

383

Utilizing metal-oxide and oxide-oxide interactions for improved automotive emissions control catalysts. Final report  

SciTech Connect

The goal of this research program was to elucidate the structure-activity relationships associated with metal-metal oxide and metal oxide-metal oxide interfaces of relevance in automotive emissions control catalysts. Particular emphasis was placed on explaining the mechanism by which ceria (CeO{sub 2}) acts as an oxygen storage medium, oxygen transport on the surface and in the bulk of ceria, and how the ceria-zirconia interaction affects oxygen storage capacity and reactivity. These properties were studied using x-ray surface scattering, pulsed neutron scattering, termperature programmed desorption, x-ray photoelectron spectroscopy, and high-resolution electron energy loss spectroscopy. The overall research program was composed of two primary thrust areas: (1) detailed studies of the lattice and defect structures of ceria and mixed ceria-zirconias, and (2) surface science studies of the reactivity of ceria single crystals and ceria thin films supported on zirconia. A brief overview of the significant contribution made in each of these areas is given.

Egami, Takeshi; Vohs, John M.

2003-02-24

384

Maximizing omnidirectional light harvesting in metal oxide hyperbranched array architectures  

NASA Astrophysics Data System (ADS)

The scrupulous design of nanoarchitectures and smart hybridization of specific active materials are closely related to the overall photovoltaic performance of an anode electrode. Here we present a solution-based strategy for the fabrication of well-aligned metal oxide-based nanowire-nanosheet-nanorod hyperbranched arrays on transparent conducting oxide substrates. For these hyperbranched arrays, we observe a twofold increment in dye adsorption and enhanced light trapping and scattering capability compared with the pristine titanium dioxide nanowires, and thus a power conversion efficiency of 9.09% is achieved. Our growth approach presents a strategy to broaden the photoresponse and maximize the light-harvesting efficiency of arrays architectures, and may lead to applications for energy conversion and storage, catalysis, water splitting and gas sensing.

Wu, Wu-Qiang; Feng, Hao-Lin; Rao, Hua-Shang; Xu, Yang-Fan; Kuang, Dai-Bin; Su, Cheng-Yong

2014-05-01

385

Hubbard Thomas Fermi theory of transition metal oxide heterostructures  

NASA Astrophysics Data System (ADS)

We demonstrate that the charge distributions in Hubbard-model representations of transition metal oxide heterojunctions can be described by a Thomas-Fermi theory in which the energy is approximated as the sum of the electrostatic energy and the uniform three-dimensional Hubbard model energy per site at the local density equals to a constant. When charged atomic layers in the oxides are approximated as two-dimensional sheets with uniform charge density, the electrostatic energy is simply evaluated. We find that this Thomas-Fermi theory can reproduce results obtained from full Hartree-Fock theory for various different heterostructures. We also show explicitly how Thomas-Fermi theory can be used to estimate some key properties qualitatively.

Lee, Wei-Cheng; MacDonald, A. H.

2008-04-01

386

Multiparameter admittance spectroscopy for metal-oxide-semiconductor systems  

NASA Astrophysics Data System (ADS)

Admittance spectroscopy is extended for measuring capacitance and conductance on metal-oxide-semiconductor (MOS) structures as a function of gate voltage, frequency, and temperature. An automatic setup has been designed for collecting data along these dimensions in one measurement cycle. The theory for admittance spectroscopy has been developed by starting from basic charge carrier statistics. Using numerical integration of energy dependent parameters instead of the commonly used analytical solution, conductance dispersion curves are obtained which do not need to be adjusted by assuming lateral surface potential variations at the oxide-semiconductor interface. Also, we find that interface state densities extracted by using traditional methods are four times lower than those obtained by using our theory. Experimental data presented in three-dimensional plots are compared with theoretical calculations, revealing the possibilities and limitations of the conductance method.

Piscator, J.; Raeissi, B.; Engström, O.

2009-09-01

387

Development of microstrain in aged lithium transition metal oxides.  

PubMed

Cathode materials with high energy density for lithium-ion batteries are highly desired in emerging applications in automobiles and stationary energy storage for the grid. Lithium transition metal oxide with concentration gradient of metal elements inside single particles was investigated as a promising high-energy-density cathode material. Electrochemical characterization demonstrated that a full cell with this cathode can be continuously operated for 2500 cycles with a capacity retention of 83.3%. Electron microscopy and high-resolution X-ray diffraction were employed to investigate the structural change of the cathode material after this extensive electrochemical testing. It was found that microstrain developed during the continuous charge/discharge cycling, resulting in cracking of nanoplates. This finding suggests that the performance of the cathode material can be further improved by optimizing the concentration gradient to minimize the microstrain and to reduce the lattice mismatch during cycling. PMID:24960550

Lee, Eung-Ju; Chen, Zonghai; Noh, Hyung-Ju; Nam, Sang Cheol; Kang, Sung; Kim, Do Hyeong; Amine, Khalil; Sun, Yang-Kook

2014-08-13

388

Breakdown voltage of metal-oxide resistors in liquid argon  

E-print Network

We characterized a sample of metal-oxide resistors and measured their breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3 second period to simulate the electric breakdown in a HV-divider chain. All resistors had higher breakdown voltages in liquid argon than their vendor ratings in air at room temperature. Failure modes range from full destruction to coating damage. In cases where breakdown was not catastrophic, subsequent breakdown voltages were lower in subsequent measuring runs. One resistor type withstands 131\\,kV pulses, the limit of the test setup.

Bagby, L F; James, C C; Jones, B J P; Jostlein, H; Lockwitz, S; Naples, D; Raaf, J L; Rameika, R; Schukraft, A; Strauss, T; Weber, M S; Wolbers, S A

2014-01-01

389

Lithium metal oxide electrodes for lithium cells and batteries  

DOEpatents

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 0

Thackeray, Michael M. (Naperville, IL); Johnson, Christopher S. (Naperville, IL); Amine, Khalil (Downers Grove, IL); Kim, Jaekook (Naperville, IL)

2004-01-13

390

Effect of rare earth metal oxide additions to tungsten electrodes  

Microsoft Academic Search

A comparative study has been made on the operating characteristics of gas-tungsten arc (GTA) welding for several types of\\u000a electrodes. The work was carried out with a pure tungsten electrode and tungsten electrodes activated with a small quantity\\u000a of the rare earth metal oxides, La2O3, Y2O3, CeO2, and with ZrO2, ThO2, and MgO. Their behaviors during arcing were analyzed and

Alber A. Sadek; Masao Ushio; Fukuhisa Matsuda

1990-01-01

391

Metal Ions, Not Metal-Catalyzed Oxidative Stress, Cause Clay Leachate Antibacterial Activity  

PubMed Central

Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4–5), generate reactive oxygen species (ROS) and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions. PMID:25502790

Otto, Caitlin C.; Koehl, Jennifer L.; Solanky, Dipesh; Haydel, Shelley E.

2014-01-01

392

The AMOS cell - An improved metal-semiconductor solar cell. [Antireflection coated Metal Oxide Semiconductor  

NASA Technical Reports Server (NTRS)

A new fabrication process is being developed which significantly improves the efficiency of metal-semiconductor solar cells. The resultant effect, a marked increase in the open-circuit voltage, is produced by the addition of an interfacial layer oxide on the semiconductor. Cells using gold on n-type gallium arsenide have been made in small areas (0.17 sq cm) with conversion efficiencies of 15% in terrestrial sunlight.

Stirn, R. J.; Yeh, Y.-C. M.

1975-01-01

393

Are metallic A-F giants evolved Am stars? Rotation and rate of binaries among giant F stars  

E-print Network

We test the hypothesis of Berthet (1992) which foresees that Am stars become giant metallic A and F stars (defined by an enhanced value of the blanketing parameter Delta_m_2 of the Geneva photometry) when they evolve. If this hypothesis is right, Am and metallic A-FIII stars need to have the same rate of binaries and a similar distribution of vsini. From our new spectroscopic data and from vsini and radial velocities in the literature, we show that it is not the case. The metallic giant stars are often fast rotators with vsini larger than 100 km/s, while the maximum rotational velocity for Am stars is about 100 km/s. The rate of tight binaries with periods less than 1000 days is less than 30 percent among metallic giants, which is incompatible with the value of 75 percent for Am stars (Abt & Levy 1985). Therefore, the simplest way to explain the existence of giant metallic F stars is to suggest that all normal A and early F stars might go through a short "metallic" phase when they are finishing their life on the main sequence. Besides, it is shown that only giant stars with spectral type comprised between F0 and F6 may have a really enhanced Delta_m_2 value, while all A-type giants seem to be normal.

M. Kunzli; P. North

1997-10-21

394

Electro-catalytic oxidation of phenol on several metal-oxide electrodes in aqueous solution  

Microsoft Academic Search

Elecrtochemical degradation of phenol was evaluated at five typical anodes for mineralization to carbon dioxide or for being a pre-treatment method in toxic aromatic compounds. Three kinds of RuO2-base electrodes were prepared by thermal deposition, which were coated by the oxides of Ru or by Ru, Sn and Sb or by Ru, Sn, Sb and Gd on Ti metal surface,

Y. J Feng; X. Y Li

2003-01-01

395

Growth of Thin InAlP Native Oxides for GaAs Metal-Oxide-Semiconductor Devices Mr. Ying Cao1  

E-print Network

Growth of Thin InAlP Native Oxides for GaAs Metal-Oxide-Semiconductor Devices Mr. Ying Cao1 ; Ms thermal native oxides towards thicknesses suitable for use in GaAs metal-oxide-semiconductor (MOS) devices, we observed that thin 7 nm oxide films showed Schottky-diode-like behavior with relatively large

396

Hydride/oxidation (HYDOX) process for conversion of plutonium metal to oxide  

SciTech Connect

Options for plutonium disposition require PuO2 that can be used as feed material for mixed oxide (MOX) reactor fuel pellets, or glass and ceramic immobilization forms (cf. Federal Register Doc. 97-1355, Vol. 62, No. 13, January 2 1,1997). As part of a DOE-sponsored demonstration known as the Advanced Recovery and Integrated Extraction System (ARIES), conversion of plutonium to oxide by the Hydride/Oxidation (HYDOX) process will be used, along with other supporting technologies, to recover plutonium from the cores or *#34;pits" of nuclear weapons that have been determined to be surplus to national defense needs. This demonstration will be performed jointly by the Los Alamos and the Lawrence Livermore National Laboratories at the Los Alamos Plutonium Facility. The pyrochemical methods employed by HYDOX offer a simple and reliable process to recover plutonium in oxide form from various sources. This process will: Separate plutonium from other nuclear and non-nuclear materials, Convert massive metallic shapes into fine oxide particles, Produce oxide directly acceptable for MOX fuel fabrication, and Produce no solid or liquid waste. The paper describes the reactor module and operational sequences, provides up-to-date experimental results, identifies rate-controlling factors, and discusses their impact on the reactor design.

Bronson, M C; Zundelevich, Y

1998-06-19

397

Facile coating carbon nanotubes with metal oxide nanoparticles of controlled size  

NASA Astrophysics Data System (ADS)

Here, we present a facile one-pot method based on colloid chemistry to successfully synthesise nanocomposites of carbon nanotubes decorated with nanoparticles of different metal oxides. The as-synthesised nanocomposites were characterised by transmission electron microscopy and X-ray diffraction. The results revealed that different kinds of metal oxide nanoparticles were homogenously deposited on the carbon nanotubes. The size of the metal oxide nanoparticles could be tuned by adjusting the experimental temperature and duration of the synthesis steps.

Wang, Ning; Jiang, Tao; Yang, Yanqiu; Wu, Chuxin; Guan, Lunhui

2014-06-01

398

Chemical and spectroscopic studies of metal oxide surfaces D. W. Goodman  

E-print Network

Chemical and spectroscopic studies of metal oxide surfaces D. W. Goodman Department of Chemistry Thin oxide films e.g., 5­10 nm of SiO2, Al2O3, NiO, MgO supported on a refractory metal substrate e.g., Mo, W, Ta, Re have been prepared by deposition of the oxide metal precursor in a background of oxygen

Goodman, Wayne

399

A Low Temperature Fully Lithographic Process For Metal–Oxide Field-Effect Transistors  

E-print Network

We report a low temperature ( ~ 100à °C) lithographic method for fabricating hybrid metal oxide/organic field-effect transistors (FETs) that combine a zinc-indium-oxide (ZIO) semiconductor channel and organic, parylene, ...

Sodini, Charles G.

400

Metal-based turn-on fluorescent probes for nitric oxide sensing  

E-print Network

Chapter 1. Metal-Based Turn-On Fluorescent Probes for Sensing Nitric Oxide. Nitric oxide, a reactive free radical, regulates a variety of biological processes. The absence of tools to detect NO directly, rapidly, specifically ...

Lim, Mi Hee

2006-01-01

401

ORIGINAL PAPER Influence of the Metal Oxide Substrate Structure on Vanadium  

E-print Network

of sulfuric acid [1]. The structure of the VOx species supported on a metal oxide has been exten- sively, including oxidative dehydrogenation of alkanes, desulfurization of fossil fuels and the production

Marks, Laurence D.

402

Radiation hardening of metal-oxide semi-conductor (MOS) devices by boron  

NASA Technical Reports Server (NTRS)

Technique using boron effectively protects metal-oxide semiconductor devices from ionizing radiation without using shielding materials. Boron is introduced into insulating gate oxide layer at semiconductor-insulator interface.

Danchenko, V.

1974-01-01

403

Conversion reaction mechanisms in lithium ion batteries: study of the binary metal fluoride electrodes.  

PubMed

Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF(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(2)) while others are not (e.g., CuF(2)). In this study, we investigated the conversion reaction of binary metal fluorides, FeF(2) and CuF(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(2) and CuF(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(+) with FeF(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(2). In contrast to FeF(2), no continuous Cu network was observed in the lithiated CuF(2); rather, the converted Cu segregates to large particles (5-12 nm in diameter) during the first discharge, which may be partially responsible for the lack of reversibility in the CuF(2) electrode. PMID:21894971

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

2011-11-23

404

Biological monitoring of workers exposed to cobalt metal, salt, oxides, and hard metal dust.  

PubMed Central

OBJECTIVE--The aim was to examine the relation between environmental and biological (blood and urine) indices of exposure to different chemical forms of cobalt. METHODS--A cross sectional study was undertaken in workers exposed to cobalt metal, oxides, and salts in a refinery and to a mixture of cobalt and tungsten carbide in a hard metal producing plant. RESULTS AND CONCLUSION--Although biological monitoring of workers exposed to cobalt oxides showed higher blood and urine concentrations than in non-exposed subjects, these indices poorly reflected the recent exposure level. By contrast, when exposure was to soluble cobalt compounds (metal, salts, and hard metals), the measurement of urine or blood cobalt at the end of the workweek could be recommended for the assessment of recent exposure. An eight hour exposure to 20 or 50 micrograms/m3 of a soluble form of cobalt would lead to an average concentration in a postshift urine sample collected at the end of the workweek of 18.2 or 32.4 micrograms of cobalt/g creatinine, respectively. PMID:8044242

Lison, D; Buchet, J P; Swennen, B; Molders, J; Lauwerys, R

1994-01-01

405

Physicochemical Factors that Affect Metal and Metal Oxide Nanoparticle Passage Across Epithelial Barriers  

PubMed Central

The diversity of nanomaterials in terms of size, shape, and surface chemistry poses a challenge to those who are trying to characterize the human health and environmental risks associated with incidental and unintentional exposures. There are numerous products that are already commercially available that contain solid metal and metal oxide nanoparticles, either embedded in a matrix or in solution. Exposure assessments for these products are often incomplete or difficult due to technological challenges associated with detection and quantitation of nanoparticles in gaseous or liquid carriers. The main focus of recent research has been on hazard identification. However, risk is a product of hazard and exposure, and one significant knowledge gap is that of the target organ dose following in vivo exposures. In order to reach target organs, nanoparticles must first breech the protective barriers of the respiratory tract, gastrointestinal tract, or skin. The fate of those nanoparticles that reach physiological barriers is in large part determined by the properties of the particles and the barriers themselves. This article reviews the physiological properties of the lung, gut, and skin epithelia, the physicochemical properties of metal and metal oxide nanoparticles that are likely to affect their ability to breech epithelial barriers, and what is known about their fate following in vivo exposures. PMID:20049809

Elder, Alison; Vidyasagar, Sadasivan; DeLouise, Lisa

2014-01-01

406

Electrochemical lithiation and delithiation for control of magnetic properties of nanoscale transition metal oxides  

E-print Network

Transition metal oxides comprise a fascinating class of materials displaying a variety of magnetic and electronic properties, ranging from half-metallic ferromagnets like CrO2, ferrimagnetic semiconductors like Fey's, and ...

Sivakumar, Vikram

2008-01-01

407

Bipolar plating of metal contacts onto oxide interconnection for solid oxide electrochemical cell  

DOEpatents

Disclosed is a method of forming an adherent metal deposit on a conducting layer of a tube sealed at one end. The tube is immersed with the sealed end down into an aqueous solution containing ions of the metal to be deposited. An ionically conducting aqueous fluid is placed inside the tube and a direct current is passed from a cathode inside the tube to an anode outside the tube. Also disclosed is a multi-layered solid oxide fuel cell tube which consists of an inner porous ceramic support tube, a porous air electrode covering the support tube, a non-porous electrolyte covering a portion of the air electrode, a non-porous conducting interconnection covering the remaining portion of the electrode, and a metal deposit on the interconnection.

Isenberg, Arnold O. (Forest Hills Boro, PA)

1987-01-01

408

Bipolar plating of metal contacts onto oxide interconnection for solid oxide electrochemical cell  

DOEpatents

Disclosed is a method of forming an adherent metal deposit on a conducting layer of a tube sealed at one end. The tube is immersed with the sealed end down into an aqueous solution containing ions of the metal to be deposited. An ionically conducting aqueous fluid is placed inside the tube and a direct current is passed from a cathode inside the tube to an anode outside the tube. Also disclosed is a multi-layered solid oxide fuel cell tube which consists of an inner porous ceramic support tube, a porous air electrode covering the support tube, a non-porous electrolyte covering a portion of the air electrode, a non-porous conducting interconnection covering the remaining portion of the electrode, and a metal deposit on the interconnection. 1 fig.

Isenberg, A.O.

1987-03-10

409

Supporting Information for: Graphene as a Long-term Metal Oxidation Barrier: Worse  

E-print Network

Supporting Information for: Graphene as a Long-term Metal Oxidation Barrier: Worse Than Nothing Figures Figure S1. Short-term oxidation resistance of graphene-covered Cu Figure S2. Short-term oxidation information on the surface phase of the corroded, graphene-covered Cu. For bare Cu with a native oxide, we

Zettl, Alex

410

Experimental Study of Electron Transport through Nanometer-Scale Metal-Oxide Junctions  

E-print Network

properties of Nb/Al/Nb junctions fabricated using thermal oxidation or rf-plasma oxidation at various........................................................................................................ 1 Chapter 2 Aluminum oxide tunnel barriers with high field enduranceExperimental Study of Electron Transport through Nanometer-Scale Metal-Oxide Junctions

411

Interactions of graphene oxide nanomaterials with natural organic matter and metal oxide surfaces.  

PubMed

Interactions of graphene oxide (GO) nanomaterials with natural organic matter (NOM) and metal oxide surfaces were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Three different types of NOM were studied: Suwannee River humic and fulvic acids (SRHA and SRFA) and alginate. Aluminum oxide surface was used as a model metal oxide surface. Deposition trends show that GO has the highest attachment on alginate, followed by SRFA, SRHA, and aluminum oxide surfaces, and that GO displayed higher interactions with all investigated surfaces than with silica. Deposition and release behavior of GO on aluminum oxide surface is very similar to positively charged poly-L-lysine-coated surface. Higher interactions of GO with NOM-coated surfaces are attributed to the hydroxyl, epoxy, and carboxyl functional groups of GO; higher deposition on alginate-coated surfaces is attributed to the rougher surface created by the extended conformation of the larger alginate macromolecules. Both ionic strength (IS) and ion valence (Na(+) vs Ca(2+)) had notable impact on interactions of GO with different environmental surfaces. Due to charge screening, increased IS resulted in greater deposition for NOM-coated surfaces. Release behavior of deposited GO varied significantly between different environmental surfaces. All surfaces showed significant release of deposited GO upon introduction of low IS water, indicating that deposition of GO on these surfaces is reversible. Release of GO from NOM-coated surfaces decreased with IS due to charge screening. Release rates of deposited GO from alginate-coated surface were significantly lower than from SRHA and SRFA-coated surfaces due to trapping of GO within the rough surface of the alginate layer. PMID:25026416

Chowdhury, Indranil; Duch, Matthew C; Mansukhani, Nikhita D; Hersam, Mark C; Bouchard, Dermont

2014-08-19

412

Adsorption of enterobactin to metal oxides and the role of siderophores in bacterial adhesion to metals.  

PubMed

The potential contribution of chemical bonds formed between bacterial cells and metal surfaces during biofilm initiation has received little attention. Previous work has suggested that bacterial siderophores may play a role in bacterial adhesion to metals. It has now been shown using in situ ATR-IR spectroscopy that enterobactin, a catecholate siderophore secreted by Escherichia coli, forms covalent bonds with particle films of titanium dioxide, boehmite (AlOOH), and chromium oxide-hydroxide which model the surfaces of metals of significance in medical and industrial settings. Adsorption of enterobactin to the metal oxides occurred through the 2,3-dihydroxybenzoyl moieties, with the trilactone macrocycle having little involvement. Vibrational modes of the 2,3-dihydroxybenzoyl moiety of enterobactin, adsorbed to TiO(2), were assigned by comparing the observed IR spectra with those calculated by the density functional method. Comparison of the observed adsorbate IR spectrum with the calculated spectra of catecholate-type [H(2)NCOC(6)H(3)O(2)Ti(OH)(4)](2-) and salicylate-type [H(2)NCOC(6)H(3)O(2)HTi(OH)(4)](2-) surface complexes indicated that the catecholate type is dominant. Analysis of the spectra for enterobactin in solution and that adsorbed to TiO(2) revealed that the amide of the 2,3-dihydroxybenzoylserine group reorientates during coordination to surface Ti(IV) ions. Investigation into the pH dependence of enterobactin adsorption to TiO(2) surfaces showed that all 2,3-dihydroxybenzoyl groups are involved. Infrared absorption bands attributed to adsorbed enterobactin were also strongly evident for E. coli cells attached to TiO(2) particle films. These studies give evidence of enterobactin-metal bond formation and further suggest the generality of siderophore involvement in bacterial biofilm initiation on metal surfaces. PMID:21744856

Upritchard, Hamish G; Yang, Jing; Bremer, Philip J; Lamont, Iain L; McQuillan, A James

2011-09-01

413

Adsorption and separation of binary mixtures in a metal-organic framework Cu-BTC: A computational study  

Microsoft Academic Search

Grand canonical Monte Carlo simulations were conducted to systematically evaluate the adsorption separation of three binary mixtures, CO2\\/CO, C2H4\\/CO2, and C2H4\\/C2H6, in a metal-organic framework Cu-BTC at room temperature. The simulated results showed that Cu-BTC could be potentially used for the purification of carbon monoxide, capture of carbon dioxide and separation of olefin\\/paraffin. The topology structure of the side pockets

Sanyue Wang; Qingyuan Yang; Chongli Zhong

2008-01-01

414

Preferential orientation of metal oxide superconducting materials by mechanical means  

DOEpatents

A superconductor comprised of a polycrystalline metal oxide such as YBa[sub 2]Cu[sub 3]O[sub 7[minus]X] (where 0 < X < 0.5) is capable of accommodating very large current densities. By aligning the two-dimensional Cu-O layers which carry the current in the superconducting state in the a- and b-directions, i.e., within the basal plane, a high degree of crystalline axes alignment is provided between adjacent grains permitting the metal oxide material to accommodate high current densities. The orthorhombic crystalline particles have a tendency to lie down on one of the longer sides, i.e., on the a- or b-direction. Aligning the crystals in this orientation is accomplished by mechanical working of the material such as by extrusion, tape casting or slip casting, provided a single crystal powder is used as a starting material, to provide a highly oriented, e.g., approximately 90% of the crystal particles have a common orientation, superconducting matrix capable of supporting large current densities. 3 figs.

Capone, D.W.

1990-11-27

415

Monolithic oxide-metal composite thermoelectric generators for energy harvesting  

NASA Astrophysics Data System (ADS)

Monolithic oxide-metal composite thermoelectric generators (TEGs) were fabricated using multilayer co-fired ceramic technology. These devices consisted of Ni0.9Mo0.1 and La0.035Sr0.965TiO3 as p- and n-type thermoelectric materials, and Y0.03Zr0.97O2 was used as an insulator, sandwiched between p- and n-type layers. To co-fire dissimilar materials, p-type layers contained 20 wt. % La0.035Sr0.965TiO3; thus, these were oxide-metal composite layers. The fabricated device had 50 pairs of p-i-n junctions of 5.9 mm × 7.0 mm × 2.6 mm. The calculated maximum value of the electric power output from the device was 450 mW/cm2 at ?T = 360 K. Furthermore, this device generated 100 ?W at ?T = 10 K and operated a radio frequency (RF) transmitter circuit module assumed to be a sensor network system.

Funahashi, Shuichi; Nakamura, Takanori; Kageyama, Keisuke; Ieki, Hideharu

2011-06-01

416

Surface diffusion upon oxygen isotopic exchange on oxide-supported metal nanoclusters  

Microsoft Academic Search

A newly developed real-time kinetic model is presented. The model was used for the characterization of supported metal catalysts' properties in the oxygen isotopic exchange reaction. This model is based on rate equations and includes several elementary processes: adsorption on the metal nanoclusters, reactions on the metal nanoclusters, desorption from the metal nanoclusters, surface and bulk diffusion on\\/in the oxide

A Galdikas; C Descorme; D Duprez

2004-01-01

417

Thermodynamic Study of Transformation of Methane to Synthesis Gas Over Metal Oxides  

NASA Astrophysics Data System (ADS)

A metal oxide reduction-water splitting cycle is a new developing method to produce synthesis gas without using a catalyst. In the reduction stage, metal oxide reduction and methane activation are combined in an efficient and energy-saving process using methane as a reducing agent. In this study, the effect of temperature and reductant (oxidant) amount on the equilibrium composition of products, graphitic carbon formation, yield of synthesis gas (water splitting stage), and produced ratio are thermodynamically investigated. This investigation includes metal oxides of zinc, tin, cobalt, and nickel. The results show that the synthesis gas is produced simultaneously with gaseous zinc, molten tin, solid cobalt, and solid nickel for those metal oxides in the reduction process. In the case of tin oxide, the feasibility of the graphitic carbon formation is less than the other oxides. The maximum yield of synthesis gas occurs in the stoichiometric molar ratio of methanothermal reduction reactions. From the methane consumption point of view, zinc oxide has a much higher synthesis gas yield. Finally, it is proposed that cobalt and nickel oxides can be used only in the reduction stage to produce synthesis gas and reduced metals due to low equilibrium conversion in the water splitting stage. The metal oxide reduction-water splitting cycle can be developed as an environmentally friendly technology for synthesis gas production over metal oxides.

Roohi, P.; Alizadeh, R.; Fatehifar, E.

2015-01-01

418

Can the packing efficiency of binary hard spheres explain the glass-forming ability of bulk metallic glasses?  

E-print Network

We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate $R$, size ratio $\\alpha$, and number fraction $x_S$ of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate $R_c$, below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with $\\alpha \\gtrsim 0.8$ that do not de-mix, $R_c$ decreases strongly with $\\Delta \\phi_J$, as $R_c \\sim \\exp(-1/\\Delta \\phi_J^2)$, where $\\Delta \\phi_J$ is the difference between the average packing fraction of the amorphous packings and random crystal structures at $R_c$. Systems with $\\alpha \\lesssim 0.8$ partially de-mix, which promotes crystallization, but we still find a strong correlation between $R_c$ and $\\Delta \\phi_J$. We show that known metal-metal BMGs occur in the regions of the $\\alpha$ and $x_S$ parameter space with the lowest values of $R_c$ for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing $\\alpha$ to increase packing efficiency, while maximizing $\\alpha$ to prevent de-mixing.

Kai Zhang; W. Wendell Smith; Minglei Wang; Yanhui Liu; Jan Schroers; Mark D. Shattuck; Corey S. O'Hern

2014-04-02

419

Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses  

NASA Astrophysics Data System (ADS)

We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio ?, and number fraction xS of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate Rc, below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with ? ?0.8 that do not demix, Rc decreases strongly with ??J, as Rc˜exp(-1/??J2), where ??J is the difference between the average packing fraction of the amorphous packings and random crystal structures at Rc. Systems with ? ?0.8 partially demix, which promotes crystallization, but we still find a strong correlation between Rc and ??J. We show that known metal-metal BMGs occur in the regions of the ? and xS parameter space with the lowest values of Rc for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing ? to increase packing efficiency, while maximizing ? to prevent demixing.

Zhang, Kai; Smith, W. Wendell; Wang, Minglei; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D.; O'Hern, Corey S.

2014-09-01

420

Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses.  

PubMed

We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio ?, and number fraction x(S) of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate R(c), below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with ??0.8 that do not demix, R(c) decreases strongly with ??(J), as R(c)?exp(-1/??(J)(2)), where ??(J) is the difference between the average packing fraction of the amorphous packings and random crystal structures at R(c). Systems with ??0.8 partially demix, which promotes crystallization, but we still find a strong correlation between R(c) and ??(J). We show that known metal-metal BMGs occur in the regions of the ? and x(S) parameter space with the lowest values of R(c) for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing ? to increase packing efficiency, while maximizing ? to prevent demixing. PMID:25314450

Zhang, Kai; Smith, W Wendell; Wang, Minglei; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

2014-09-01

421

Structural characterization and photocatalytic activity of hollow binary ZrO 2/TiO 2 oxide fibers  

NASA Astrophysics Data System (ADS)

The formation of hollow binary ZrO 2/TiO 2 oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO 2 and tetragonal phase of ZrO 2, and the introduction of ZrO 2 notably inhibits the growth of TiO 2 nanocrystallites. Although calcined at 575 °C, all hollow ZrO 2/TiO 2 fibers exhibit higher surface areas (>113 m 2/g) than pure TiO 2 hollow fibers. The Pyridine adsorption on ZrO 2/TiO 2 sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO 2. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms.

Wu, Baochao; Yuan, Rusheng; Fu, Xianzhi

2009-03-01

422

New algorithm in the basin hopping Monte Carlo to find the global minimum structure of unary and binary metallic nanoclusters  

NASA Astrophysics Data System (ADS)

The basin-hopping Monte Carlo algorithm was modified to more effectively determine a global minimum structure in pure and binary metallic nanoclusters. For a pure metallic Ag55 nanocluster, the newly developed quadratic basin-hopping Monte Carlo algorithm is 3.8 times more efficient than the standard basin-hopping Monte Carlo algorithm. For a bimetallic Ag42Pd13 nanocluster, the new algorithm succeeds in finding the global minimum structure by 18.3% even though the standard basin-hopping Monte Carlo algorithm fails to achieve it.

Kim, Hyoung Gyu; Choi, Si Kyung; Lee, Hyuck Mo

2008-04-01

423

Simple metal and binary alloy phases based on the hcp structure: Electronic origin of distortions and superlattices  

NASA Astrophysics Data System (ADS)

Crystal structures of simple metals and binary alloy phases based on the close-packed hexagonal (hcp) structure are analyzed within the model of Fermi sphere - Brillouin zone interactions to understand distortions and superlattices. Examination of the Brillouin-Jones configuration in relation to the nearly-free electron Fermi sphere for several representative phases reveals significance of the electron energy contribution to the phase stability. This approach may be useful for understanding high pressure structures recently found in compressed simple alkali and alkali-earth metals.

Degtyareva, Valentina F.; Afonikova, Nataliya S.

2014-11-01

424

Alloy Films Deposited by Electroplating as Precursors for Protective Oxide Coatings on Solid Oxide Fuel Cells Metallic Interconnect Materials  

SciTech Connect

The successful development of stainless steel interconnects for intermediate temperature solid oxide fuel cells (SOFC) may be the materials breakthrough that makes SOFC technology truly commercial. Many of the ferritic stainless steels, however, suffer from a relatively high area specific resistance (ASR) after long exposure times at temperature and the Cr in the native oxide can evaporate and contaminate other cell components. Conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. In the present study electrochemical deposition of binary alloys followed by oxidation of the alloy to form protective and conductive oxide layers is examined. Results are presented for the deposition of Mn/Co and Fe/Ni alloys via electroplating to form a precursor for spinel oxide coating formation. Analysis of the alloy coatings is done by SEM, EDS and XRD.

Johnson, Christopher; Gemmen, R.S.; Cross, Caleb

2006-10-01

425

Active metal oxides and polymer hybrids as biomaterials  

NASA Astrophysics Data System (ADS)

Bone anchored prosthetic attachments, like other percutaneous devices, suffer from poor soft tissue integration, seen as chronic inflammation, infection, epithelial downgrowth and regression. We looked at the use of metal oxides as bioactive agents that elicit different bioresponses, ranging from cell attachment, tissue integration and reduction of inflammation to modulation of cell proliferation, morphology and microbe killing. This study presents a novel method for creating titanium oxide and polydimethylsiloxane (PDMS) hybrid coated microplates for high throughput biological, bacterial and photocatalytic screening that overcomes several limitations of using bulk metal samples. Titanium oxide coatings were doped with silver, zinc, vanadium, aluminum, calcium and phosphorous, while PDMS was doped with titanium, vanadium and silver and subjected to hydrothermal heat treatment to determine the influence of chemistry and crystallinity on the viability, proliferation and adhesion of human fibroblasts, keratinocytes and Hela cells. Also explored was the influence of Ag and Zn doping on E. coli proliferation. We determined how titanium concentration in hybrids and silver doping influenced the photocatalytic degradation of methylene blue by coatings. A combined sub/percutaneous, polyurethane device was developed and implanted into the backs of CD hairless rats to investigate how optimized coatings influenced soft tissue integration in vivo. We demonstrate that the bioresponse of cells to coatings is controlled by elemental doping (V & Ag) and that planktonic bacterial growth was greatly reduced or stopped by Ag, but not Zn doping. Hydrothermal heat treatments (65 °C and 121 °C) did not greatly influence cellular bioresponse to coatings. We discovered a range of temperature resistant (up to 400 °C), solid state dispersions with enhanced ability to block full spectrum photon transmission and degrade methylene using medical x-rays, UV, visible and infrared photons. We show that silver doping improved the photoactivity of oxide coatings, but hindered activity of a specific hybrid. Doped titanium oxide and polymer hybrid coatings have potential for improving soft tissue integration of medical implants and wound healing by modulating cell proliferation, attachment, inflammation and providing controlled delivery of bioactive and antimicrobial compounds and photon induced electro-chemical activity.

Jarrell, John D.

426

Fabrication of hollow metal oxide nanocrystals by etching cuprous oxide with metal(ii) ions: approach to the essential driving force  

NASA Astrophysics Data System (ADS)

Hollow metal oxide nanocrystals were prepared by etching cuprous oxide with metal ions and were applied as photoelectrodes. As a hard template, polyvinylpyrrolidone stabilized cuprous oxide (PVP-Cu2O) and non-stabilized cuprous oxide (nPVP-Cu2O) were synthesized by a precipitation method. Hollow iron oxide and cobalt oxide nanocrystals with a truncated octahedral morphology were fabricated by an etching reaction with transition metal(ii) ions (Fe2+ or Co2+). In the etching reaction process, a cationic exchange reaction occurs between the divalent metal ion and Cu+ due to the higher Lewis acidity. Facet selective etching of cuprous oxide has been observed during the ionic exchange reaction of Cu+ and O2- ions in PVP-Cu2O complexes with transition metal(ii) ions (Fe2+ or Co2+) at the surface of a (110) facet. Amorphous states of hollow metal oxide products were annealed to form ?-Fe2O3 (hematite) and Co3O4 and their crystal structure was examined with X-ray diffraction and HR-TEM. The optical absorption behavior of semiconductor nanocrystals was measured with UV-vis spectroscopy to define band gap energy. The hollow hematite structure has a 2.08 eV band gap and Co3O4 (Co(ii,iii) oxide) has a 1.80 eV indirect band gap. Using these hollow nanocrystals, a metal oxide monolayer film was fabricated with a secondary growth approach and was studied for its photocatalytic properties.Hollow metal oxide nanocrystals were prepared by etching cuprous oxide with metal ions and were applied as photoelectrodes. As a hard template, polyvinylpyrrolidone stabilized cuprous oxide (PVP-Cu2O) and non-stabilized cuprous oxide (nPVP-Cu2O) were synthesized by a precipitation method. Hollow iron oxide and cobalt oxide nanocrystals with a truncated octahedral morphology were fabricated by an etching reaction with transition metal(ii) ions (Fe2+ or Co2+). In the etching reaction process, a cationic exchange reaction occurs between the divalent metal ion and Cu+ due to the higher Lewis acidity. Facet selective etching of cuprous oxide has been observed during the ionic exchange reaction of Cu+ and O2- ions in PVP-Cu2O complexes with transition metal(ii) ions (Fe2+ or Co2+) at the surface of a (110) facet. Amorphous states of hollow metal oxide products were annealed to form ?-Fe2O3 (hematite) and Co3O4 and their crystal structure was examined with X-ray diffraction and HR-TEM. The optical absorption behavior of semiconductor nanocrystals was measured with UV-vis spectroscopy to define band gap energy. The hollow hematite structure has a 2.08 eV band gap and Co3O4 (Co(ii,iii) oxide) has a 1.80 eV indirect band gap. Using these hollow nanocrystals, a metal oxide monolayer film was fabricated with a secondary growth approach and was studied for its photocatalytic properties. Electronic supplementary information (ESI) available: TEM and SEM images of PVP-Cu2O and nPVP-Cu2O, FTIR result of PVP and PVP-Cu2O etc. See DOI: 10.1039/c3nr03626j

Sohn, Jong Hwa; Cha, Hyun Gil; Kim, Chang Woo; Kim, Do Kyoung; Kang, Young Soo

2013-10-01

427

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

SciTech Connect

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.

Ivanova, N.; Avendano Nandez, J. L.; Sivakoff, G. R. [Department of Physics, University of Alberta, Edmonton, AB T6G 2E1 (Canada); Fragos, T.; Kim, D.-W.; Fabbiano, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Lombardi, J. C. [Department of Physics, Allegheny College, Meadville, PA 16335 (United States); Voss, R. [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500-GL Nijmegen (Netherlands); Jordan, A., E-mail: nata.ivanova@ualberta.ca [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, 7820436 Macul, Santiago (Chile)

2012-12-01

428

Dilute doping, defects, and ferromagnetism in metal oxide systems.  

PubMed

Over the past decade intensive research efforts have been carried out by researchers around the globe on exploring the effects of dilute doping of magnetic impurities on the physical properties of functional non-magnetic metal oxides such as TiO(2) and ZnO. This effort is aimed at inducing spin functionality (magnetism, spin polarization) and thereby novel magneto-transport and magneto-optic effects in such oxides. After an early excitement and in spite of some very promising results reported in the literature, this field of diluted magnetic semiconducting oxides (DMSO) has continued to be dogged by concerns regarding uniformity of dopant incorporation, the possibilities of secondary ferromagnetic phases, and contamination issues. The rather sensitive dependence of magnetism of the DMSO systems on growth methods and conditions has led to interesting questions regarding the specific role played by defects in the attendant phenomena. Indeed, it has also led to the rapid re-emergence of the field of defect ferromagnetism. Many theoretical studies have contributed to the analysis of diverse experimental observations in this field and in some cases to the predictions of new systems and scenarios. In this review an attempt is made to capture the scope and spirit of this effort highlighting the successes, concerns, and questions. PMID:20535732

Ogale, Satishchandra B

2010-08-01

429

Comparative responses to metal oxide nanoparticles in marine phytoplankton.  

PubMed

A series of experiments was undertaken on three different marine microalgae to compare the effect of two metal oxide nanoparticles (NPs) on different physiological responses to stress: zinc oxide (ZnO), a known toxic compound for microalgae, and the never before tested yttrium oxide (Y?O3). The effect of these potential pollutants was estimated for different physiological variables and temporal scales: Growth, carbon content, carbon-to-nitrogen (C:N) ratio, and chlorophyll fluorescence were evaluated in long-term assays, and reactive oxygen species (ROS) production was evaluated in a short-term assay. Population growth was the most susceptible variable to the acute toxic effects of both NPs as measured in terms of number of cells and of biomass. Although Phaeodactylum tricornutum and Alexandrium minutum were negatively affected by ZnO NPs, this effect was not detected in Tetraselmis suecica, in which cell growth was significantly decreased by Y?O? NPs. Biomass per cell was negatively affected in the most toxic treatments in T. suecica but was positively affected in A. minutum. ZnO treatments induced a sharper decrease in chlorophyll fluorescence and higher ROS than did Y?O? treatments. The pronounced differences observed in the responses between the species and the physiological variables tested highlight the importance of analyzing diverse groups of microalgae and various physiological levels to determine the potential effects of environmental pollutants. PMID:24908584

Castro-Bugallo, Alexandra; González-Fernández, África; Guisande, Cástor; Barreiro, Aldo

2014-11-01

430

NANOSTRUCTURED METAL OXIDE CATALYSTS VIA BUILDING BLOCK SYNTHESES  

SciTech Connect

A broadly applicable methodology has been developed to prepare new single site catalysts on silica supports. This methodology requires of three critical components: a rigid building block that will be the main structural and compositional component of the support matrix; a family of linking reagents that will be used to insert active metals into the matrix as well as cross link building blocks into a three dimensional matrix; and a clean coupling reaction that will connect building blocks and linking agents together in a controlled fashion. The final piece of conceptual strategy at the center of this methodology involves dosing the building block with known amounts of linking agents so that the targeted connectivity of a linking center to surrounding building blocks is obtained. Achieving targeted connectivities around catalytically active metals in these building block matrices is a critical element of the strategy by which single site catalysts are obtained. This methodology has been demonstrated with a model system involving only silicon and then with two metal-containing systems (titanium and vanadium). The effect that connectivity has on the reactivity of atomically dispersed titanium sites in silica building block matrices has been investigated in the selective oxidation of phenols to benezoquinones. 2-connected titanium sites are found to be five times as active (i.e. initial turnover frequencies) than 4-connected titanium sites (i.e. framework titanium sites).

Craig E. Barnes

2013-03-05

431

X-raying metal-poor starburst galaxies: Evidence of an overabundance of luminous X-ray binaries  

NASA Astrophysics Data System (ADS)

We have studied the high mass X-ray binary (HMXB) populations within two low-metallicity, starburst galaxies, Haro 11 and VV 114. These galaxies are particularly interesting because they are good analogs of high-redshift (z > 2) Lyman break galaxies, and are part of a larger sample of Lyman break analogs (LBAs). Previous studies of the X-ray emission in LBAs have found that the X-ray luminosity per star formation rate (SFR) in these galaxies is elevated, potentially because of their low metallicities. Theoretically, XRBs formed in lower metallicity environments lose less mass from stellar winds over their lifetimes, resulting in more numerous and luminous HMXBs per SFR. In this talk, I will present how metallicity influences the X-ray luminosity distribution of HMXBs in these galaxies. This study has greater implications on understanding the evolution of X-ray emission from galaxies over the history of the Universe.

Basu-Zych, Antara; Lehmer, Bret; Hornschemeier, Ann E.; Ptak, Andrew; Yukita, Mihoko; Zezas, Andreas

2015-01-01

432

Wetting and interfacial bonding in ionocovalent oxide-liquid metal D. Chatain, L. Coudurier and N. Eustathopoulos  

E-print Network

1055 Wetting and interfacial bonding in ionocovalent oxide-liquid metal systems D. Chatain, L compared to experimental results as regards the wettability of monocrystalline oxides by pure metals lead and of metallic additions to the metal on the wettability of the oxide is then discussed. Oxygen has two effects

Paris-Sud XI, Université de

433

Effect of edge roughness on electronic transport in graphene nanoribbon channel metal-oxide-semiconductor field-effect transistors  

E-print Network

Effect of edge roughness on electronic transport in graphene nanoribbon channel metal-oxide on transport in graphene nanoribbon metal-oxide-semiconductor field-effect transistors MOSFETs are reported are metallic, nanoscale graphene ribbons have band gaps. The potential for performance gains in metal-oxide

Gilbert, Matthew

434

Total oxidation of carbon monoxide and methane over transition metal-fluorite oxide composite catalysts. I. Catalyst composition and activity  

SciTech Connect

A novel metal oxide composite catalyst for the total oxidation of carbon monoxide and methane was prepared by combining fluorite oxides with active transition metals. The fluorite oxides, such as ceria and zirconia, are oxygen-ion-conducting materials having catalytic properties usually at high temperatures. Active base metal catalysts, such as copper, were used as additives to promote the catalytic properties of these oxides. The contact of the two types of materials gave rise to a high active oxidation catalyst. At a space velocity of about 42,000 h{sup {minus}1}, complete carbon monoxide oxidation in air occurred at room temperature on the Au{sub 0.05}[Ce(La)]{sub 0.95}L{sub x} catalyst and at ca. 100{degrees}C on Cu-Ce-O composite catalysts. At the same space velocity, total oxidation of methane on the Cu-Ce-O catalyst doped with La{sub 2}O{sub 3} or SrO took place at ca. 550{degrees}C. The specific carbon monoxide oxidation activity of the Cu-Ce-O catalyst was several orders of magnitude higher than that of conventional copper-based catalysts and comparable or superior to platinum catalysts. This type of composite catalyst also showed excellent resistance to water vapor poisoning. The enhanced catalyst activity and stability resulted from strong interaction of the transition metal and fluorite oxide materials. 44 refs., 14 figs., 5 tabs.

Liu, W.; Flytzani-Stephanopoulos, F. [Tufts Univ., Medford, MA (United States)] [Tufts Univ., Medford, MA (United States)

1995-05-01

435

Molecular orbital studies in oxidation: Sulfate formation and metal-metal oxide adhesion  

NASA Technical Reports Server (NTRS)

The chemical mechanisms for sulfate formation from sodium chloride and sulfur trioxide, which is a product of jet fuel combustion was determined. Molten sodium sulfate leads to hot corrosion of the protective oxide layers on turbine blades. How yttrium dopants in nidkel-aluminum alloys used in turbine blades reduce the spalling rate of protective alumina films and enhance their adhesion was also determined. Two other fulfate mechanisms were deduced and structure of carbon monoxide on a clean chronium and clean platinum-titanium alloys surfaces was determined. All studies were by use of the atom superposition and electron delocalization molecular orbital (ASED-MO) theory. Seven studies were completed. Their titles and abstracts are given.

Anderson, A. B.

1985-01-01

436

Silica-lanthanum oxide: pioneer composite of rare-Earth metal oxide in selective phosphopeptides enrichment.  

PubMed

Relying on the successful journey of metal oxides in phosphoproteomics, lanthanum oxide is employed for the engineering of an affinity material for phosphopeptide enrichment. The lanthanum oxide is chemically modified on the surface of silica and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The obtained silica-lanthanum oxide composite is applied for the selective enrichment of phosphopeptides from tryptic digest of standard protein (?-casein, ?-casein, and commercially available casein mixtures from bovine milk). The enriched entities are analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The mass spectroscopy (MS) results show that the silica-lanthanum oxide composite exhibits enhanced capability for phosphopeptide enrichment with sensitivity assessed to be 50 fmol. Sequence coverage of casein is interpreted showing successful recovery. As a real sample, a protein digest of nonfat milk is applied. Also, the ability of lanthanum in different formats is checked in the selective phosphopeptides enrichment. The composite holds promising future in economic ground as it also possesses the regenerative ability for repetitive use. PMID:23134445

Jabeen, Fahmida; Hussain, Dilshad; Fatima, Batool; Musharraf, S Ghulam; Huck, Christian W; Bonn, G?nther K; Najam-ul-Haq, Muhammad

2012-12-01

437

Comparison Between Crystalline and Amorphous Surfaces of Transition Metal Oxide Water Oxidation Catalysts: a Theoretical Perspective  

NASA Astrophysics Data System (ADS)

Amorphous films of transition-metal oxide water oxidation catalysts (WOCs) often show an enhanced catalytic activity compared to their crystalline counterparts [1-4]. In particular, in the case of cobalt-oxide based WOCs the observed similarity in their electrochemical properties and catalytic activity, under oxidative conditions, has been correlated with the formation of similar amorphous surface morphologies, suggesting the presence of a common, catalytically active amorphous structural motif [3,4]. We present ab initio calculations of cobalt oxide based material surfaces and we compare the electronic properties of crystalline and amorphous surfaces, with the aim of identifying differences related to their different catalytic activity.[4pt] [1] Blakemore, J. D., Schley, N. D., Kushner-Lenhoff, M. N., Winter, A. M., D'Souza, F., Crabtree, R. H., and Brudvig, G. W. Inorg. Chem. 51, 7749 (2012); [2] Tsuji, E., Imanishi, A., Fukui, K.-I. and Nakato, Y. Electrochimica Acta 56, 2009 (2011); [3] Jia, H., Stark, J., Zhou, L. Q., Ling, C., Takeshi, S., and Markin, Z. RSC Advances 2, 10874 (2012); [4] Lee, S. W., Carlton, C., Risch, M., Surendranath, Y., Chen, S., Furutsuki, S., Yamada, A., Nocera, D. G., and Shao-Horn, Y. J. Am. Chem. Soc. 134, 16959 (2012).

Skone, Jonathan H.; Galli, Giulia

2013-03-01

438

Effect of Element Diffusion Through Metallic Networks During Oxidation of Type 321 Stainless Steel  

NASA Astrophysics Data System (ADS)

A detailed study was conducted on localized oxidation on Type 321 stainless steel (321ss) using synchrotron x-ray nanobeam analysis along with Raman microscopy. The results showed the presence of metallic nanonetworks in the oxide scales, which plays an important role in the continued oxidation of the alloy at 750 °C. A mechanism is proposed to explain the rapid oxidation of 321ss in complex gaseous environments at elevated temperature. Neutral metal atoms could diffuse outward, and carbon atoms could diffuse inward through the metallic nanonetworks in oxide layers. Alternately, diffusion tunnels can dramatically affect the phase composition of the oxide scales. Since the diffusion rate of neutral metal and carbon atoms through the metallic nanonetworks can be much faster than the diffusion of cations through Cr2O3, the metallic nanonetwork provides a path through the protective Cr2O3 layer for the rapid outward diffusion of metallic chromium and iron atoms to the nonprotective spinel layer. This diffusion process affects the solid-state reaction near the alloy-oxide boundary, and a dense Cr2O3 protective layer does not form. The classic stable structure of the oxide scales, with a dense Cr2O3 layer at the bottom, is damaged by the rapid diffusion through the tunnel at the reaction front, resulting in locally accelerated oxidation. This process can subsequently lead to "breakaway" oxidation and catastrophic failure of the alloy.

Zeng, Z.; Natesan, K.; Cai, Z.; Gosztola, D.; Cook, R.; Hiller, J.

2014-04-01

439

Formation of binary oxide aerosols in premixed flames: Factors influencing the segregation of species  

NASA Astrophysics Data System (ADS)

Binary aerosols consisting of ZnO/MgO and CuO/MgO were produced by passing micron-sized particles, uniform in composition through a premixed methane flat flame. The mass distribution of the precursor particles entering the flame, measured by sampling with an impactor, was unimodal. The mass distributions of the particles leaving the flame were bimodal for both Zn and Mg in the ZnO/MgO system and for Mg in the CuO/MgO system. Transmission electron microscope (TEM) images of the particles showed coarse unagglomerated particles in the large mode, and agglomerates of very fine (dsb{p} = 5 nm) particles in the small mode, indicating that solid phase reaction and gas-to-particle conversion occur simultaneously. To focus on the gas-to-particle conversion route and the effect of precursor oxidation chemistry, nanometer-sized (dsb{p} = 15 nm) SiOsb2/TiOsb2 particles were generated in a premixed methane flat flame aerosol reactor from three sets of gas phase precursors: SiBrsb4/TiClsb4,\\ SiClsb4/TiClsb4, and hexamethyldisiloxane (HMDS)/TiClsb4. The chemical composition from particle to particle, determined using energy dispersive x-ray spectrometry (EDS) coupled with TEM, varied little. The choice of silica precursor had no observable effect on the distribution of species in the mixed aerosol, indicating that chemical process do not affect the arrangement of species for mixed systems. Within the particles, small (dsb{p} = 5 to 8 nm) crystalline regions enriched in Ti were observed. This arrangement corresponds qualitatively to the equilibrium phase distribution of the SiOsb2/TiOsb2 system for the temperatures of the flame. A particle formation mechanism in which segregation occurs by diffusion within the particles was proposed. To investigate the relationship between observed segregation and the equilibrium phase distribution, binary SiOsb2/TiOsb2 and SiOsb2/Fesb2Osb3 aerosols (dsb{p} < 100\\ nm) of varying mole ratios of Ti or Fe to Si were generated in a premixed Bunsen-type methane flame reactor. Qualitative agreement was observed between the arrangement of species in the particles and the arrangement expected from equilibrium thermodynamics, evidenced by segregated regions visible within the primary particles in the TEM images and crystalline peaks in the x-ray diffraction patterns.

Ehrman, Sheryl Heather

1997-12-01

440

Sustainable synthesis, characterization, and applications of metal oxide nanostructures  

NASA Astrophysics Data System (ADS)

Nanomaterials have attracted significant research focus due to their advantageous and unique properties (i.e. electronic, magnetic, optical, and mechanical) as compared with the bulk. Metal oxide nanostructures are of particular interest, as they are very robust and display high chemical and thermal stability, while offering a diverse array of fascinating properties. By reliably controlling the size, morphology, composition, and crystallinity of these nanostructures, their properties can be tuned for a specific purpose. These advantageous tailorable properties render them as ideal candidates for many applications such as catalysis, sensing, electronics, optoelectronics, energy storage, and even medicine. Driven by their increased popularity and potential applications, efforts to synthesize nanomaterials have moved toward environmentally-friendly methodologies, such as wet-chemical, molten-salt, hydrothermal, and sol-gel methods. We will discuss the green synthesis of strontium ruthenate (SrRuO 3), the yttrium manganese oxides (YMnO3 and YMn2O 5), and the magnetic spinel ferrites (MFe2O4 where 'M' is Mg, Fe, Co, Ni, Cu, and Zn) and our ability to reliably tune their properties for various applications. The effects of the molten salt parameters on the resulting particle size and morphology were explored for SrRuO 3 and the yttrium manganese oxides. For example, rapid cooling rates and the use of surfactants allowed us to produced faceted octahedra of SrRuO 3, which resulted in a 4-fold enhancement of their activity towards methanol oxidation with respect to smooth rounded particles. Similarly, using the hydrothermal method, we generated ferrite nanoparticles of different compositions and sizes. We investigated their potential as contrast agents for magnetic resonance imaging (MRI) and as photocatalysts, and observed significant differences as a function of both size and composition. Similarly, we will also examine surface and structural effects upon the electronic properties of V2O 3 nanowires.

Tiano, Amanda Lyn

441

INVESTIGATION ON DURABILITY AND REACTIVITY OF PROMISING METAL OXIDE SORBENTS DURING SULFIDATION AND REGENERATION. QUARTERLY AND FINAL REPORT  

SciTech Connect

Hot-gas desulfurization for the integrated gasification combined cycle (IGCC) process has been investigated by many researchers to remove effectively hydrogen sulfide with various metal oxide sorbents at high pressures and high temperatures. Metal oxides such as zinc titanate oxides, zinc ferrite oxide, copper oxide, manganese oxide and calcium oxide, were found to be promising sorbents in comparison with other removal methods such as membrane separations and reactive membrane separations. Some metal oxide sorbents exhibited the quite favorable performance in terms of attrition resistance and sulfur capacity. Experiments on removal reaction of H{sub 2}S from coal gas mixtures with formulated metal oxide sorbents were conducted in a batch reactor or a differential reactor. The objectives of this research project are to formulate promising metal oxide sorbents for removal of sulfur from coal gas mixtures, to find initial reaction kinetics for the metal oxide-hydrogen sulfide heterogeneous reaction system, to obtain effects of hydrogen, nitrogen and moisture on dynamic absorption and equilibrium absorption at various absorption temperatures. Promising durable metal oxide sorbents with high-sulfur-absorbing capacity were formulated by mixing active metal oxide powders with inert metal oxide powders, and calcining these powder mixtures. The Research Triangle Institute (RTI), a sub-contractor of this research project, will also prepare promising metal oxide sorbents for this research project, plan experiments on removal of sulfur compounds from coal gases with metal oxide, and review experimental results.

K.C. KWON

1998-08-01

442

S9 -Kinetics & Mechanism of Metal Sorption/Release on Natural Materials KINETICS OF OXYANION SORPTION ON METAL OXIDES: A TIME-  

E-print Network

SORPTION ON METAL OXIDES: A TIME- RESOLVED ATR-FTIR SPECTROSCOPIC STUDY PEAK J. D. AND SPARKS been observed with o-phthalate on metal oxides (2). While it is well accepted that borate forms inner-sphere complexes on metal oxides, the mechanism of boron adsorption is not completely understood. It is possible

Sparks, Donald L.

443

Recent progress in high performance and reliable n-type transition metal oxide-based thin film transistors  

NASA Astrophysics Data System (ADS)

This review gives an overview of the recent progress in vacuum-based n-type transition metal oxide (TMO) thin film transistors (TFTs). Several excellent review papers regarding metal oxide TFTs in terms of fundamental electron structure, device process and reliability have been published. In particular, the required field-effect mobility of TMO TFTs has been increasing rapidly to meet the demands of the ultra-high-resolution, large panel size and three dimensional visual effects as a megatrend of flat panel displays, such as liquid crystal displays, organic light emitting diodes and flexible displays. In this regard, the effects of the TMO composition on the performance of the resulting oxide TFTs has been reviewed, and classified into binary, ternary and quaternary composition systems. In addition, the new strategic approaches including zinc oxynitride materials, double channel structures, and composite structures have been proposed recently, and were not covered in detail in previous review papers. Special attention is given to the advanced device architecture of TMO TFTs, such as back-channel-etch and self-aligned coplanar structure, which is a key technology because of their advantages including low cost fabrication, high driving speed and unwanted visual artifact-free high quality imaging. The integration process and related issues, such as etching, post treatment, low ohmic contact and Cu interconnection, required for realizing these advanced architectures are also discussed.

Kwon, Jang Yeon; Kyeong Jeong, Jae

2015-02-01

444

Oxidation catalysts comprising metal exchanged hexaaluminate wherein the metal is Sr, Pd, La, and/or Mn  

DOEpatents

The present invention provides metal-exchanged hexaaluminate catalysts that exhibit good catalytic activity and/or stability at high temperatures for extended periods with retention of activity as combustion catalysts, and more generally as oxidation catalysts, that make them eminently suitable for use in methane combustion, particularly for use in natural gas fired gas turbines. The hexaaluminate catalysts of this invention are of particular interest for methane combustion processes for minimization of the generation of undesired levels (less than about 10 ppm) of NOx species. Metal exchanged hexaaluminate oxidation catalysts are also useful for oxidation of volatile organic compounds (VOC), particularly hydrocarbons. Metal exchanged hexaaluminate oxidation catalysts are further useful for partial oxidation, particularly at high temperatures, of reduced species, particularly hydrocarbons (alkanes and alkenes).

Wickham, David (Boulder, CO); Cook, Ronald (Lakewood, CO)

2008-10-28

445

Effects of Binary Mixtures of Inducers (Toluene Analogs) and of Metals on Bioluminescence Induction of a Recombinant Bioreporter Strain  

PubMed Central

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. PMID:25313497

Kong, In Chul

2014-01-01

446

Formaldehyde-methanol, metallic-oxide agents head scavengers list  

SciTech Connect

Use of batch-operated chemical H/sub 2/S scavengers as an inexpensive gas-sweetening process may be an attractive alternative for moderately sour gas wells with small production remote from a gas-processing plant. This article begins a four-part series describing the most common H/sub 2/S scavengers available to the natural gas-producing industry. Advantages, disadvantages, health and safety aspects, case histories, design guidelines, and economics of these scavengers will be addressed. Currently available, nonregenerative scavengers for small-plant H/sub 2/S removal may be categorized into four groups: Formaldehyde-methanol-based, metallic oxide-based, caustic-based, and other processes.

Schaack, J.P.; Chan, F.

1989-01-23

447

Synthesis of high purity metal oxide nanoparticles for optical applications  

NASA Astrophysics Data System (ADS)

In this paper we present our recent research results in synthesizing various metal oxide nanoparticles for use as laser gain media (solid state as well as fiber lasers) and transparent ceramic windows via two separate techniques, co-precipitation and flame spray pyrolysis. The nanoparticles were pressed into ceramic discs that exhibited optical transmission approaching the theoretical limit and showed very high optical-to-optical lasing slope efficiency. We have also synthesized sesquioxide nanoparticles using a Flame Spray Pyrolysis (FSP) technique that leads to the synthesis of a metastable phase of sesquioxide which allows fabricating excellent optical quality transparent windows with very fine grain sizes. Finally, we present our research in the synthesis of rare earth doped boehmite nanoparticles where the rareearth ion is encased in a cage of aluminum and oxygen to prevent ion-ion proximity and energy transfer. The preforms have been drawn into fibers exhibiting long lifetimes and high laser efficiencies.

Baker, C.; Kim, W.; Friebele, E. J.; Villalobos, G.; Frantz, J.; Shaw, L. B.; Sadowski, B.; Fontana, J.; Dubinskii, M.; Zhang, J.; Sanghera, J.

2014-09-01

448

Breakdown voltage of metal-oxide resistors in liquid argon  

E-print Network

We characterized a sample of metal-oxide resistors and measured their breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3 second period. This test mimics the situation in a HV-divider chain when a breakdown occurs and the voltage across resistors rapidly rise from the static value to much higher values. All resistors had higher breakdown voltages in liquid argon than their vendor ratings in air at room temperature. Failure modes range from full destruction to coating damage. In cases where breakdown was not catastrophic, subsequent breakdown voltages were lower in subsequent measuring runs. One resistor type withstands 131\\,kV pulses, the limit of the test setup.

L. F. Bagby; S. Gollapinni; C. C. James; B. J. P. Jones; H. Jostlein; S. Lockwitz; D. Naples; J. L. Raaf; R. Rameika; A. Schukraft; T. Strauss; M. S. Weber; S. A. Wolbers

2014-10-04

449

A Theory of Wood Waterproofing by Complexes of Metal Oxides with Lignin Structural Units  

Microsoft Academic Search

The effect of various metallic oxides and hydroxides on wood waterproofing was investigated. The waterproofing effect was attributed to the type of complexes formed by the metallic oxide with the guaiacol units of the lignin network of wood. The type of structure of the complex formed, as well as its insolubility, contribute to the wood waterproofing, although to a different

H. Kubel; A. Pizzi

1982-01-01

450

Self-Assembly of Metal Oxides into Three-Dimensional Nanostructures: Synthesis and Application in Catalysis  

EPA Science Inventory

Nanostructured metal (Fe, Co, Mn, Cr, Mo) oxides were fabricated under microwave irradiation conditions in pure water without using any reducing or capping reagent. The metal oxides self-assembled into octahedron, spheres, triangular rods, pine, and hexagonal snowflake-like thre...

451

Computational screening of perovskite metal oxides for optimal solar light Ivano E. Castelli,a  

E-print Network

Computational screening of perovskite metal oxides for optimal solar light capture Ivano E, Cubic Perovskite Oxides and Cubic Perovskite Oxinitrides sections; Table 1, 2, 3; Fig. 1, 2. See DOI: 10/oxynitride compounds in the cubic perovskite structure covering 52 metals. The screening is based on criteria

Thygesen, Kristian

452

Self assembled multi-layer nanocomposite of graphene and metal oxide materials  

DOEpatents

Nanocomposite materials having at least two layers, each layer consisting of one metal oxide bonded to at least one graphene layer were developed. The nanocomposite materials will typically have many alternating layers of metal oxides and graphene layers, bonded in a sandwich type construction and will be incorporated into an electrochemical or energy storage device.

Liu, Jun; Choi, Daiwon; Kou, Rong; Nie, Zimin; Wang, Donghai; Yang, Zhenguo

2014-09-16

453

C-H Oxidation by Platinum Group Metal Oxo or Peroxo Species  

SciTech Connect

While C–H oxidation by ruthenium oxo compounds has been broadly applied in organic synthesis, examples of C–H oxidation by metal oxo complexes from the rest of the platinum group are still rare. We survey the preparation and reactivity of these late-transition metal oxo and peroxo complexes in this tutorial review.

Zhou, Meng; Crabtree, Robert H

2011-01-01

454

Toxicity of metallic oxides nanoparticle suspensions to a freshwater sludge worm Tubifex tubifex Müller.  

PubMed

Toxic effects of selected metallic oxides nanoparticles were studied using the short-term static bioassays. Nanoparticles were more toxic than comparable bulk metallic oxides. Freshwater sludge worm Tubifex tubifex can be used as suitable test model for nanoecotoxicological studies in future studies. PMID:21485877

Verma, Surabhi; Das, Sangita; Khangarot, B S

2011-02-01

455

Method of dissolving metal oxides with di- or polyphosphonic acid and a redundant  

DOEpatents

A method of dissolving metal oxides using a mixture of a di- or polyphosphonic acid and a reductant wherein each is present in a sufficient amount to provide a synergistic effect with respect to the dissolution of metal oxides and optionally containing corrosion inhibitors and pH adjusting agents.

Horwitz, Earl P. (Argonne, IL); Chiarizia, Renato (Argonne, IL)

1996-01-01

456

Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors  

E-print Network

Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors Dennis M (ALD) of smooth and highly conformal films of hafnium and zirconium oxides was studied using six metal alkylamide precursors for hafnium and zirconium. Water was used as an oxygen source during these experiments

457

ERDC/ELTR-11-9 Evaluation of Metals Release from Oxidation  

E-print Network

ERDC/ELTR-11-9 Evaluation of Metals Release from Oxidation of Fly Ash during Dredging of the Emory release; distribution is unlimited. #12;ERDC/EL TR-11-9 August 2011 Evaluation of Metals Release from Oxidation of Fly Ash during Dredging of the Emory River, TN Jeffery A. Steevens, Anthony J. Bednar, Mark A

US Army Corps of Engineers

458

Metal oxide surfaces and their interactions with aqueous solutions and microbial organisms  

Microsoft Academic Search

During the past decade, interest in chemical reactions occurring at metal oxide-aqueous solution interfaces has increased significantly because of their importance in a variety of fields, including atmospheric chemistry, heterogeneous catalysis and photocatalysis, chemical sensing, corrosion science, environmental chemistry and geochemistry, metallurgy and ore beneficiation, metal oxide crystal growth, soil science, semiconductor manufacturing and cleaning, and tribology. This review begins

Gordon E. Brown; Victor E. Henrich; William H. Casey; David L. Clark; Carrick Eggleston; Andrew Felmy; D. Wayne Goodman; Michael Grätzel; Gary Maciel; Maureen I. McCarthy; Kenneth H. Nealson; Dimitri A. Sverjensky; Michael F. Toney; John M. Zachara

1999-01-01

459

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells  

NASA Astrophysics Data System (ADS)

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (? < 400 nm) is blocked to achieve an improved device lifetime. In this work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with h? < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

Trost, S.; Becker, T.; Zilberberg, K.; Behrendt, A.; Polywka, A.; Heiderhoff, R.; Görrn, P.; Riedl, T.

2015-01-01

460

Nitric Oxide in Biological Denitrification: Fe/Cu Metalloenzyme and Metal Complex NOx Redox Chemistry  

E-print Network

Nitric Oxide in Biological Denitrification: Fe/Cu Metalloenzyme and Metal Complex NOx Redox Nitrite Reductase: 1204 2. Copper Nitrite Reductases 1206 B. Nitric Oxide Reductase 1208 1. Structure 1208. Copper-Mediated NO(g) Chemistry 1221 D. Iron Complex-Mediated NO(g) Reactivity 1224 E. Transition Metal

Schroeder, Imke

461

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells  

PubMed Central

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve de