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1

Strain-induced ferroelectricity in simple rocksalt binary oxides.  

PubMed

Using first-principles density functional calculations, we show that ferroelectricity can be induced in simple alkaline-earth-metal binary oxides such as barium oxide (BaO) using appropriate epitaxial strains. Going beyond the fundamental discovery, we highlight that the functional properties (polarization, dielectric constant, and piezoelectric response) of such strained binary oxides are comparable in magnitude to those of typical ferroelectric perovskite oxides, making them of direct interest for applications. Finally, we show that magnetic binary oxides such as EuO, with the same rocksalt structure, behave similarly to the alkaline-earth-metal oxides, suggesting a route to new multiferroics combining ferroelectric and magnetic properties. PMID:20366683

Bousquet, Eric; Spaldin, Nicola A; Ghosez, Philippe

2010-01-22

2

Resistance Switching and Formation of a Conductive Bridge in Metal\\/Binary Oxide\\/Metal Structure for Memory Devices  

Microsoft Academic Search

The resistance switching mechanism of a metal\\/CuO\\/metal sandwich with a planar device structure has been studied. We report the direct observation of a conducting bridge within the CuO channel of the device, which is formed upon the initial voltage application (forming process). It is found that the resistance switching phenomenon only occurs when just a single bridge is formed during

Kohei Fujiwara; Takumi Nemoto; Marcelo J. Rozenberg; Yoshinobu Nakamura; Hidenori Takagi

2008-01-01

3

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

4

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

5

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

6

Catastrophic oxidation of metals  

NASA Astrophysics Data System (ADS)

The review deals with the current state of the problem of catastrophic oxidation of metals ('hot corrosion') caused by formation of a liquid corrosion product in a multi-component system. The kinetics, thermodynamics, and mechanisms of the two stages of accelerated oxidation of metals, namely, fast and super-fast stages, are considered with the copper-bismuth oxide system as an example. It is shown that the fast stage is caused by the formation of a liquid-channel grain boundary structure in the corrosion product, while the super-fast stage is caused by the high rate of dissolution of the oxide layer. The results of studies of the interaction of liquid phase with two-dimensional defects (grain boundaries) in solids are generalised. A model of catastrophic oxidation of metals is proposed. The bibliography includes 104 references.

Belousov, Valerii V.

1998-07-01

7

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

8

Reliable metal-to-metal oxide antifuses  

Microsoft Academic Search

This paper presents a new high performance, reliable metal-to-metal antifuse. The problem of switch-off in the programmed antifuses is avoided by using metals with low thermal conductivity and thin oxide

G. Zhang; C. Hu; P. Yu; S. Chiang; S. Eltoukhy; E. Hamdy

1994-01-01

9

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

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

Wellinghoff, Stephen T. (Inventor)

1997-01-01

10

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

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

Wellinghoff, Stephen T. (Inventor)

1994-01-01

11

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

12

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

Microsoft Academic Search

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

Hitoshi Ogihara; Sadakane Masahiro; Yoshinobu Nodasaka; Wataru Ueda

2009-01-01

13

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

14

Efficient electrocatalytic oxygen evolution on amorphous nickel-cobalt binary oxide nanoporous layers.  

PubMed

Nanoporous Ni-Co binary oxide layers were electrochemically fabricated by deposition followed by anodization, which produced an amorphous layered structure that could act as an efficient electrocatalyst for water oxidation. The highly porous morphologies produced higher electrochemically active surface areas, while the amorphous structure supplied abundant defect sites for oxygen evolution. These Ni-rich (10-40 atom % Co) binary oxides have an increased active surface area (roughness factor up to 17), reduced charge transfer resistance, lowered overpotential (?325 mV) that produced a 10 mA cm(-2) current density, and a decreased Tafel slope (?39 mV decade(-1)). The present technique has a wide range of applications for the preparation of other binary or multiple-metals or metal oxides nanoporous films. Fabrication of nanoporous materials using this method could provide products useful for renewable energy production and storage applications. PMID:25134007

Yang, Yang; Fei, Huilong; Ruan, Gedeng; Xiang, Changsheng; Tour, James M

2014-09-23

15

Diffusion and Interdiffusion in Binary Metallic Melts  

E-print Network

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 (MD) 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 non-entropic 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 $T_c$. 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.

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

2014-08-09

16

The oxidation resistance, hardness and constitution of metallic aluminides  

Microsoft Academic Search

The majority of the binary intermetallic compounds of aluminium with metals from the First and Third Long Periods and with Mg, Y, Pd, Ag, Th and U have been prepared, hardness tested and oxidized in air at successively higher temperatures. From the oxidation results the temperature corresponding to a weight change of 1 mg cm-2 over 4 h was determined

H. E. N. Stone

1975-01-01

17

The Difference between Metal-poor and Metal-rich Binaries  

NASA Astrophysics Data System (ADS)

I explored the reason why many authors differed as to whether the field metal-poor stars are deficient in spectroscopic binaries or have the same frequency as metal-rich stars. From published studies of five large samples of binaries, it is obvious that the distribution of orbital periods of metal-poor stars peaks at 875 days while that of metal-rich stars peaks at about 22 days. That means that if one uses high-dispersion spectra, one will find many binaries in both samples but if one uses low-dispersion spectra, one will fail to detect the long-period binaries and will find more binaries among the metal-rich stars. The reason for the difference in period distributions seems to be that most of the metal-poor stars have left the globular clusters quickly (within 10^6 yr), before most of them can form short-period binaries in three-body encounters.

Abt, H. A.

2009-08-01

18

Metal oxide nanowires gas sensors  

Microsoft Academic Search

Metal oxides are an attractive and heterogeneous class of materials covering the entire range from metals to semiconductors and insulators and almost all aspects of material science and physics in areas including superconductivity and magnetism. As far as chemical sensing is concerned it has been known, from more than five decades, that the electrical conductivity of metal oxides semiconductors varies

E. Comini

2008-01-01

19

Nano-metal oxide: potential catalyst on thermal decomposition of ammonium perchlorate  

Microsoft Academic Search

In this review, an attempt to collect the summarised data of literature on catalytic effect of nano-oxides, such as mono oxides, mixed oxide, binary and ternary ferrites and rare earth metal oxides on the thermal decomposition of ammonium perchlorate (AP) is made. Influence of size effect of oxides on thermal decomposition of AP and comparison of bulk and nanosized oxides

Shalini Chaturvedi; Pragnesh N. Dave

2011-01-01

20

Nano-metal oxide: potential catalyst on thermal decomposition of ammonium perchlorate  

Microsoft Academic Search

In this review, an attempt to collect the summarised data of literature on catalytic effect of nano-oxides, such as mono oxides, mixed oxide, binary and ternary ferrites and rare earth metal oxides on the thermal decomposition of ammonium perchlorate (AP) is made. Influence of size effect of oxides on thermal decomposition of AP and comparison of bulk and nanosized oxides

Shalini Chaturvedi; Pragnesh N. Dave

2012-01-01

21

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

22

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

23

REVIEW: Porous Anodic Metal Oxides  

NASA Astrophysics Data System (ADS)

Porous anodic aluminium oxide (AAO) and anodic titanium oxide (ATO) attracted an increased attention in the recent years due to their high potentials of application in nanotechnology. This article presents a brief review of some important developments of these smart materials including anodization methods, formation mechanisms of the pores, self-ordering processes and applications. Anodization of other metals are also highlighted.

Su, Zixue; Zhou, Wuzong

2008-01-01

24

Metal oxide nanostructures with hierarchical morphology  

DOEpatents

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

Ren, Zhifeng (Newton, MA); Lao, Jing Yu (Saline, MI); Banerjee, Debasish (Ann Arbor, MI)

2007-11-13

25

Process for fabrication of metal oxide films  

SciTech Connect

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

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

1990-07-17

26

An in situ study using anomalous wide angle X-ray scattering and X-ray absorption spectroscopy of the binary metal oxide catalytic system SnO2-ZnAI2O4 supported on alumina  

NASA Astrophysics Data System (ADS)

A fine structural description of the local order around zinc and tin atoms of a binary metal oxide catalyst, namely SnO2-ZnAl2O4/AI2O3 which can be used as a DeNOx catalyst, is achieved through XAS (X-ray absorption Spectroscopy) and AWAXS (Anomalous wide angle X-ray scattering). The analysis of the data was supported by ab initio calculations based on the multiple scattering processes for the XAS spectroscopy and ab initio calculations based on the Debye equation in the case of anomalous scattering. We found that the tetrahedral sites occupied by the zinc atoms are not completely filled and that part of the zinc atoms are engaged in a SnO2 like structure. Also, it seems that most of the tin atoms are engaged in tin dioxide clusters. For the set of in situ XAS experiments done at the K Zn edge and K Sn edge, no significant modification of the interatomic distances around each of the two metals versus the reactive gases are measured. Taking into account the previous results obtained on the monoxide metal supported catalyst ZnAl2O4/Al2O3, we can assume thus that only a dramatic lack of occupancy on the metal site favours an incursion of light atoms in the network. This structural property can explain in return the expansion of the crystallographic cell as well as a significant increased of the Debye-Waller factor associated to zinc-zinc pairs. Une description détaillée de l'ordre local autour du zinc et de l'étain est effectuée sur un catalyseur SnO2-ZnAl2O4/AI2O3 par deux techniques spécifiques au rayonnement synchrotron, la spectroscopie d'absorption X et la diffraction anomale. Une attention particulière est portée sur l'analyse des données. En ce qui concerne la spectroscopie d'absorption X, celle-ci s'effectue par le biais de logiciels prenant en compte les processus de diffusion multiple du photoélectron. La simulation numérique des différentielles obtenues par soustraction des diagrammes de diffraction s'effectue à partir de l'équation de Debye en tenant compte des fluctuations du facteur de diffusion atomique en fonction de l'énergie du photon incident. Le jeu de résultats ainsi recueilli permet une mesure précise de l'état électronique du zinc, du taux d'occupation des sites tétraédriques ainsi que de la taille du cristallite de l'oxyde étudié. Se basant sur des résultats précédents inhérents au monométallique ZnAl2O4/Al2O3, nous discutons l'importance du caractère lacunaire en zinc du catalyseur et la relation existant entre cette spécificité et la modification des paramètres structuraux enregistrés à haute température.

Revel, R.; Bazin, D.; Bouchet-Fabre, B.; Seigneurin, A.; Kihn, Y.

2002-07-01

27

Machinable dissolved metal oxide superconductors  

SciTech Connect

Powders of a metal oxide superconductor are mixed with sufficient amount (10--80 mol%) of In, Sn, and/or Al, to become nonbrittle, machinable. Preferred superconductors are YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] and Bi-Sr-Ca-Cu-O compounds.

Chen, Chung-Hsuan.

1991-01-01

28

Binary metal metallocarbohedrenes of titanium and group IIIA, VA, and VIA metals  

SciTech Connect

Binary metal metallocarbohedrenes of titanium and the metals yttrium, niobium, molybdenum, tantalum, and tungsten have been produced by the direct laser vaporization of mixtures of titanium carbide with these metals. Interestingly, as individuals metals, yttrium, tantalum, and tungsten have not displayed a tendency for forming the metallocarbohedrene (Met-Car) structure. Substitution of titanium atoms by these non-group IVA metals in the titanium Met-Car, Ti[sub 8]C[sub 12], is not as extensive as that achieved with the group IVA metal zirconium under similar conditions. Recent theoretical predictions based upon electronic structure and nuclear charge are considered in interpreting these results. 15 refs., 1 fig.

Cartier, S.F.; May, B.D.; Castleman, A.W. Jr. (Pennsylvania State Univ., University Park, PA (United States))

1994-06-15

29

Strong configurational dependence of elastic properties for a binary model metallic glass  

E-print Network

Strong configurational dependence of elastic properties for a binary model metallic glass Gang Duan in a Cu­Zr binary metallic glass assessed by molecular dynamics simulations is reported. By directly, the shear modulus dependence on the specific configurational inherent state of metallic glasses is shown

Goddard III, William A.

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

Primary alkaline battery containing bismuth metal oxide  

US Patent & Trademark Office Database

A battery includes a cathode having an oxide containing one or more metals and pentavalent bismuth, an anode, a separator between the cathode and the anode, and an alkaline electrolyte. The metal(s) can be an alkali metal, an alkaline earth metal, a transition metal, and/or a main group metal. The separator can be ion-selective or capable of substantially preventing soluble bismuth ionic species from diffusing from the cathode to the anode.

2009-05-26

32

Metal oxide-based transparent conducting oxides  

NASA Astrophysics Data System (ADS)

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

Gillispie, Meagen Anne

33

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

34

Metal oxide composite dosimeter method and material  

DOEpatents

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

Miller, Steven D. (Richland, WA)

1998-01-01

35

Resistance switching in amorphous and crystalline binary oxides grown by electron beam evaporation and atomic layer deposition  

Microsoft Academic Search

Resistance switching random access non-volatile memories (ReRAM) could represent the leading alternative to floating gate technology for post 32nm technology nodes. Among the currently investigated materials for ReRAM, transition metal binary oxides, such as NiO, CuxO, ZrOx, TiO2, MgO, and Nb2O5 are receiving increasing interest as they offer high potential scalability, low-energy switching, thermal stability, and easy integration in CMOS

S. Spiga; A. Lamperti; C. Wiemer; M. Perego; E. Cianci; G. Tallarida; H. L. Lu; M. Alia; F. G. Volpe; M. Fanciulli

2008-01-01

36

Magnetochromism in Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

We discuss the discovery and mechanism of magnetic field-induced color changes in three different low-dimensional transition metal oxides: Li purple bronze, (CPA)_2CuBr_4, and Pr-substituted La_1.2Sr_1.8Mn_2O_7. In Li purple bronze, the field manipulates the density of states near E_F, altering O p to Mo d excitations. In the copper halide, the applied field rotates the CuBr4 chromophore units, yielding a strong magnetochromic effect. And in (La_0.4Pr_0.6_1.2Sr_1.8Mn_2O_7, the magnetic field acts on the Jahn-Teller-split Mn^3+ eg orbitals, with consequences of a substantial CMR effect, unusual magnetic relaxation behavior, and a change in orbital occupation.

Musfeldt, Janice; Choi, Jongwoo; Haraldsen, Jason; Woodward, Jonathan; Wei, Xing; He, Jian; Mandrus, David; Landee, Chris; Turnbull, Mark; Suryanarayanan, Ramanathanan; Revcolevschi, Alex

2004-03-01

37

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

38

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 Grove, IL); Ackerman, John P. (Downers Grove, IL)

2005-06-28

39

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

40

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

41

Surface plasmon resonance in conducting metal oxides  

Microsoft Academic Search

We report the initial observation of surface plasmon resonance (SPR) in a conducting metal oxide thin film. The SPR phenomenon has been observed by attenuated total reflection of near-infrared radiation and is in agreement with electron energy loss spectroscopy measurements. To date, only metals are known to exhibit surface plasmon resonance and only noble metals have practical application. According to

Crissy Rhodes; Stefan Franzen; Jon-Paul Maria; Mark Losego; Donovan N. Leonard; Brian Laughlin; Gerd Duscher; Stephen Weibel

2006-01-01

42

Controlling plasmonic resonances in binary metallic nanostructures Ying Gu,1,a  

E-print Network

Controlling plasmonic resonances in binary metallic nanostructures Ying Gu,1,a Jia Li,1 Olivier J on the interplay of plasmonic resonances in binary nanostructures indicated that, at a fixed wavelength, resonance chaos, collective resonance, resonance flat, and new branch regions. This means that plasmonic

Floreano, Dario

43

A Numerical Model Describing Multiphase Binary Diffusion in Liquid Metal/Solid Metal Couples  

NASA Astrophysics Data System (ADS)

A numerical model for multiphase binary diffusion in liquid metal/solid metal infinite couples is developed by introducing a bisection method which determines a location of the Matano interface. The model makes use of phase diagram sources and kinetic data without any adjustable parameters. The model gives displacements of the interphase interfaces including the liquid/solid interface relative to the x = 0 plane, a change in the mass of a solid metal and a distance-composition profile at diffusion time given. The calculated rates of phase layer growth agreed reasonably well with the measured rates by other researchers in liquid Sn saturated with Cu/solid Cu couples and liquid Zn/solid Fe couples in the diffusion-controlled stage.

Tsuji, Shinji

2014-11-01

44

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

45

Lithium metal oxide electrodes for lithium batteries  

Microsoft Academic Search

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

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

2008-01-01

46

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

47

Searching for active binary rutile oxide catalyst for water splitting from first principles.  

PubMed

Water electrolysis is an important route to large-scale hydrogen production using renewable energy, in which the oxygen evolution reaction (OER: 2H(2)O ? O(2) + 4H(+) + 4e(-)) causes the largest energy loss in traditional electrocatalysts involving Ru-Ir mixed oxides. Following our previous mechanistic studies on the OER on RuO(2)(110) (J. Am. Chem. Soc. 2010, 132, 18214), this work aims to provide further insight into the key parameters relevant to the activity of OER catalysts by investigating a group of rutile-type binary metal oxides, including RuNiO(2), RuCoO(2), RuRhO(2), RuIrO(2) and OsIrO(2). Two key aspects are focused on, namely the surface O coverage at the relevant potential conditions and the kinetics of H(2)O activation on the O-covered surfaces. The O coverage for all the oxides investigated here is found to be 1 ML at the concerned potential (1.23 V) with all the exposed metal cations being covered by terminal O atoms. The calculated free energy barrier for the H(2)O dissociation on the O covered surfaces varies significantly on different surfaces. The highest OER activity occurs at RuCoO(2) and RuNiO(2) oxides with a predicted activity about 500 times higher than pure RuO(2). On these oxides, the surface bridging O near the terminal O atom has a high activity for accepting the H during H(2)O splitting. It is concluded that while the differential adsorption energy of the terminal O atom influences the OER activity to the largest extent, the OER activity can still be tuned by modifying the electronic structure of surface bridging O. PMID:22941355

Chen, Dong; Fang, Ya-Hui; Liu, Zhi-Pan

2012-12-28

48

Photopromoted and Thermal Decomposition of Nitric Oxide by Metal Oxides.  

National Technical Information Service (NTIS)

This technical report summarizes research on decomposition of NOx by photopromoted and thermal solid-catalyzed decomposition of NO. Typical catalysts incorporated one or more metal oxides. Photopromotion of catalytic activity was observed with several cat...

E. Berman, J. Dong, N. N. Lichtin

1992-01-01

49

Cyclic catalytic upgrading of chemical species using metal oxide materials  

DOEpatents

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

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

2013-05-07

50

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

51

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

52

Acoustic properties of metal oxides aqueous suspensions  

Microsoft Academic Search

The feasibility of using aqueous suspensions of several metal oxide nanoparticles as contrast agents for ultrasonic cardiovascular\\u000a visualization has been investigated. Nanopowders of Al, Fe, and Zr oxides were prepared by the electrical explosion of metallic\\u000a wires, and characteristics such as particle size, specific area, and particle size distribution, were obtained, as were TEM\\u000a photographs. Dynamic light-scattering data demonstrated that

T. F. Shklyar; O. A. Toropova; A. P. Safronov; D. V. Leiman; Yu. A. Kotov; F. A. Blyakhman

2010-01-01

53

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

54

Study on Metal/Metal oxide/Graphene Tunnel Junctions  

NASA Astrophysics Data System (ADS)

Metal/metal-oxide/graphene (Metal = Al, Ti, Hf, Zr) tunnel junctions were fabricated by transferring single-layer graphene grown by chemical vapor deposition on Cu onto metal strips by either a wet or dry approach. The metal strips were prepared by dc magnetron sputtering through a shadow mask and were exposed to air for about 10 minutes for native oxides to grow prior to the transfer. Good tunneling properties were observed for all the junctions fabricated by either means of graphene transfer. The zero-bias resistance of these junctions all increases with time to a final value, indicating continuing oxidation of the metals with a self-limited oxidation rate. Some junctions show the final area-normalized zero-bias resistances and self-limited oxidation time scales for Al, Ti, Hf, Zr are about 0.15, 0.2, 6000, 1000 k?cm^2 and 25, 90, 6, 9 hour, respectively. The tunneling spectra were studied at various temperature down to 4.2 K and analyzed by the Brinkman-Dynes-Rowell model to get the height and width of the tunnel barriers, taking into account the electron structure of graphene. The junctions are good candidates for chemical sensing applications.

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

2013-03-01

55

Nano-enabled metal oxide varistors  

Microsoft Academic Search

Zinc oxide based metal oxide varistors (MOV) are widely used electrical surge protection components. The design of modern high power, high-density electronic systems necessitate the need for smaller footprint, higher current density and higher nonlinearity MOVs. Such requirements can no longer be satisfied by commercially available MOVs due to their limited voltage capability, high leakage current and mechanical cracking related

Daniel Qi Tan; Karim Younsi; Yingneng Zhou; Patricia Irwin; Yang Cao

2009-01-01

56

Exploiting Covalency to Enhance MetalOxide and OxideOxide Adhesion at Heterogeneous Interfaces  

E-print Network

provide some means of oxidation/ corrosion protection for the superalloy. This goal partially moti- vatesExploiting Covalency to Enhance Metal­Oxide and Oxide­Oxide Adhesion at Heterogeneous Interfaces to those formed using more ionic oxides, such as Al2O3, in place of SiO2. The improved strength

Carter, Emily A.

57

FT-ICR studies of metal-carbon binary clusters for formation mechanism of endohedral fullerene  

E-print Network

FT-ICR studies of metal-carbon binary clusters for formation mechanism of endohedral fullerene the clustering process of endohedral metallo-fullerene (Figure 1). Cluster beams were generated by laser-vaporizations of various sample materials used for arc-discharge generation of metal- containing fullerene and SWNT (single

Maruyama, Shigeo

58

Photoredox laser chemistry of transition metal oxides  

NASA Astrophysics Data System (ADS)

We describe two-color laser excitation of tungsten oxide in ambient air to effect a fully reversible photoredox cycle. One color is infrared, apparently functioning as heat, and the other is visible or shorter wavelength, but not necessarily super bandgap, apparently supplying electronic excitation. In the case of either tungsten oxide or molybdenum oxide, the process can be monitored using a very strong set of Raman spectroscopic features. This process could find application in optical data storage and may be a generally useful strategy for manipulating transition metal oxides.

Osman, J. M.; Bussjager, R. J.; Nash, F.; Chaiken, J.; Villarica, R. M.

59

Removal of phosphate from aqueous solution by magnetic Fe–Zr binary oxide  

Microsoft Academic Search

Phosphorus removal was a crucial aspect in controlling eutrophication problem of water pollution. Zirconium oxide was a suitable adsorbent for phosphate removal due to its good adsorption efficiency, but it suffered from the separation inconvenience. In this paper, magnetic Fe–Zr binary oxide was synthesized and used as adsorbent for removing phosphate from aqueous solution. The adsorbent was characterized by energy

Fei Long; Ji-Lai Gong; Guang-Ming Zeng; Long Chen; Xi-Yang Wang; Jiu-Hua Deng; Qiu-Ya Niu; Hui-Ying Zhang; Xiu-Rong Zhang

2011-01-01

60

Exposure Characterization of Metal Oxide Nanoparticles in the Workplace  

Microsoft Academic Search

This study presents exposure data for various metal oxides in facilities that produce or use nanoscale metal oxides. Exposure assessment surveys were conducted at seven facilities encompassing small, medium, and large manufacturers and end users of nanoscale (particles <0.1 ?m diameter) metal oxides, including the oxides of titanium, magnesium, yttrium, aluminum, calcium, and iron. Half- and full-shift sampling consisting of

Brian Curwin; Steve Bertke

2011-01-01

61

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

62

Biomimetic surfaces of semiconducting metal oxides  

NASA Astrophysics Data System (ADS)

Metal oxides such as titanium dioxide and zink oxide are well-known semiconductors. They are used in various a wide variety of functional devices. The size and morphology of the material has a substantial effect on device performance. Here, we propose to manufacture a hierarchic assembly of nanomaterials on the micrometer scale to arrive at new functionalities for photonic devices. The construction of the materials follows a bottom-up assembly that mimics processes that occur in nature.

Orita, Kosuke; Karthaus, Olaf

2014-03-01

63

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

64

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

65

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

66

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

67

Metal-oxide-oxide-metal granular tunnel diodes fabricated by anodization  

NASA Astrophysics Data System (ADS)

A metal-oxide-oxide-metal (MO-OM) junction was fabricated based on anodized Al and Ta granular metal-oxide tunnel junctions. Electrical transport properties of the MO-OM junction were investigated at various temperatures. A strong asymmetric nonlinear current-voltage curve at room temperature indicated a diode-like behavior with a threshold voltage of 0.19 V under forward bias. The nonlinear current-voltage curves under forward and reverse biases were well fitted separately by the Simmons equation (J. G. Simmons, J. Appl. Phys. 34, 1793 (1963)) with barrier thickness, height, and tunneling area treated as variables.

Fan, Wenbin; Commisso Dolph, Melissa; Lu, Jiwei; Wolf, Stuart A.

2011-12-01

68

Task specific ionic liquid for direct electrochemistry of metal oxides  

Microsoft Academic Search

We present the first report on task specific ionic liquid (TSIL) for direct electrochemical detection of heavy metal oxides including cadmium oxide, copper oxide and lead oxide at room temperature. This TSIL based electrochemical sensor demonstrated a high sensitivity and selectivity towards the online monitoring of these trace metal oxide particulates, along with short detection time, low cost and high

Donglai Lu; Nasim Shomali; Amy Shen

2010-01-01

69

Spectroscopic studies of metal growth on oxides  

E-print Network

of metal clusters on well-defined oxide surfaces. In this work, the nucleation and growth modes of Ag on TiO?(110)(1x1) and (1x2) surfaces, Ag on ultra-thin Al?O? films, and Au on ultra-thin SiO? films were studied by scanning tunneling microscopy (STM...

Luo, Kai

2012-06-07

70

Metal-supported solid oxide fuel cells  

SciTech Connect

Low cost, colloidal deposition methods have been utilized to produce novel solid oxide fuel cell structures on metal alloy support electrodes. YSZ films were deposited on iron-chrome supports on top of a thin Ni/YSZ catalytic layer, and sintered at 1350 degrees C, in a reducing atmosphere. Dense, 20??m YSZ electrolyte films were obtained on highly porous stainless steel substrates.

Villarreal, I.; Jacobson, C.; Leming, A.; Matus, Y.; Visco, S.; De Jonghe, L.

2003-01-07

71

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

72

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

73

Thermochemistry of binary alloys of lanthanum with 3 d -transition metals  

Microsoft Academic Search

The enthalpy of mixing for liquid binary alloys of lanthanum with 3d-transition metals (Sc, Ti, V, Cr, and Fe) is determined\\u000a by a calorimetric method within the field of compositions rich in lanthanum. Data for the partial enthalpy of mixing in the\\u000a La-3d-metal system with infinite dilution demonstrates a complex relationship of a change in it in the series of

V. V. Berezutskii; N. I. Usenko; M. I. Ivanov

2006-01-01

74

Adsorption and release of nitric oxide in metal organic frameworks  

US Patent & Trademark Office Database

Disclosed are metal organic frameworks that adsorb nitric oxide, NO-loaded metal organic frameworks, methods of preparing the NO-loaded metal organic frameworks, methods of releasing the nitric oxide into a solution or into air, and uses of the metal organic frameworks.

2013-07-16

75

Ba and Ni speciation in a nodule of binary Mn oxide phase composition from Lake Baikal  

E-print Network

Ba and Ni speciation in a nodule of binary Mn oxide phase composition from Lake Baikal Alain in a ferromanganese nodule from Lake Baikal were charac- terized by X-ray microfluorescence, microdiffraction layer sites in the interlayer. Ã? 2007 Elsevier Ltd. All rights reserved. 1. INTRODUCTION Lake Baikal

76

The variation of thermal oxidation resistance across certain binary systems  

Microsoft Academic Search

Isochronal oxidation tests have been carried out on numerous compositions based on copper and silver with elements forward in the Periodic Table and compositions based on aluminium and zinc passing back. Variability across the various systems is such that three composition ranges may be defined; the first is the terminal solution where the oxidation parameter, Tp, rises from a value

H. E. N. Stone

1991-01-01

77

Nano-structuring of complex metal oxides for catalytic oxidation  

Microsoft Academic Search

New crystalline solid materials of Mo3VOx having high-dimensional structures were synthesized in a single crystalline form using a hydrothermal method where the essential structural unit in the structure already presents in the preparative solution and the fundamental structure of Mo3VOx is formed as a result of self-organization between negatively charged pentagonal units and VO2+ cations. We also synthesized metal oxides

Wataru Ueda; Masahiro Sadakane; Hitoshi Ogihara

2008-01-01

78

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

79

Mesoscopically structured nanocrystalline metal oxide thin films.  

PubMed

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. PMID:25224841

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

2014-11-01

80

Copper and zinc decontamination from single- and binary-metal solutions using hydroxyapatite.  

PubMed

Toxic metals contamination of waters, soils and sediments can seriously affect plants, animals and human being. The bioavailability of metal ions can be reduced trapping them in minerals with low solubilities. This study investigated the sorption of aqueous Cu and Zn onto hydroxyapatite surfaces. Batch experiments were carried out using synthetic hydroxyapatite. The metals were applied as single or binary species, in a range of metal concentrations ranging from 0 to 8 mmol/L at 25+/-2 degrees C. The removal capacity of hydroxyapatite was 0.016-0.764 mmol of Cu/g and 0.015-0.725 mmol of Zn/g. In the Cu-Zn binary system, competitive metal sorption occurred with reduction of the removal capacity by 13-76% and 10-63% for Cu and Zn, respectively, compared to the single-metal systems. The sorption of Cu and Zn was well characterized by the Langmuir model. Heavy metal immobilization was attributed to a two-step mechanism: first rapid surface complexation and secondly partial dissolution of hydroxyapatite and ion exchange with Ca followed by the precipitation of a heavy metal-containing hydroxyapatite. PMID:17204364

Corami, Alessia; Mignardi, Silvano; Ferrini, Vincenzo

2007-07-19

81

Hydrous metal oxide catalysts for oxidation of hydrocarbons  

SciTech Connect

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

Miller, J.E.; Dosch, R.G.; McLaughlin, L.I. [Sandia National Labs., Albuquerque, NM (United States). Process Research Dept.

1993-07-01

82

Surface aspects of bismuth-metal oxide catalysts  

SciTech Connect

A series of conventional and model bismuth-metal oxide catalysts (vanadates, molybdates, tungstates, and niobates) were physically and chemically characterzied (Raman spectroscopy, BET, XPS, and methanol oxidation) to obtain additional insights into the structure-reactivity relationships of such catalytic materials. The reactivity for methanol oxidation over the conventional bismuth-metal oxide catalysts was found to be primarily related to the surface area of the oxide catalysts and was essentially independent of the near surface composition and the bulk structure. The selectivity for methanol oxidation over the conventional bismuth-metal oxide catalysts was essentially found not to be a function of the surface area, the near surface composition, and the bulk structure. A series of model bismuth-metal oxide catalysts was synthesized by depositing metal oxides on the surface of a bismuth oxide support. The model studies demonstrated that two-dimensional metal oxide overlayers are not stable on the bismuth oxide support and readily react to form bulk bismuth-metal oxide compounds upon heating. Furthermore, the model studies revealed that these bulk bismuth-metal oxide compounds are related to the active sites for the partial oxidation reaction. In situ Raman spectroscopy in methanol/oxygen, methanol, and oxygen reaction environments with helium as the diluent revealed no additional information regarding the nature of the active site. It was found that only highly crystalline bismuth-metal oxide phases are selective for the partial oxidation of methanol to formaldehyde. Thus, selective bismuth-metal oxide catalysts will always possess highly crystalline metal oxide phases containing extremely low surface areas which make it difficult to obtain fundamental surface information about the outermost layers. 48 refs., 11 figs., 9 tabs.

Arora, N.; Deo, G.; Wachs, I.E. [Lehigh Univ., Bethlehem, PA (United States)] [and others] [Lehigh Univ., Bethlehem, PA (United States); and others

1996-03-01

83

CRC Handbook of Electrical Resistivitives of Binary Metallic Alloys  

SciTech Connect

Material design engineers often require a tabulation of physical properties in order to select the appropriate material for use, while developmental engineers need to be aware of basic principles and systemic trends that can be utilized as a guide for developing future materials and alloys. The trade-off in conductivity that results when metals are replaced by alloys for strength and stability purposes becomes an important consideration for both types of engineers. This handbook presents an extensive, updated and comprehensive compilation of the electrical resistivities of metallic alloys.

Schroder, K.

1983-01-01

84

Linking experiment and theory for three-dimensional networked binary metal nanoparticle-triblock terpolymer superstructures  

NASA Astrophysics Data System (ADS)

Controlling superstructure of binary nanoparticle mixtures in three dimensions from self-assembly opens enormous opportunities for the design of materials with unique properties. Here we report on how the intimate coupling of synthesis, in-depth electron tomographic characterization and theory enables exquisite control of superstructure in highly ordered porous three-dimensional continuous networks from single and binary mixtures of metal nanoparticles with a triblock terpolymer. Poly(isoprene-block-styrene-block-(N,N-dimethylamino)ethyl methacrylate) is synthesized and used as structure-directing agent for ligand-stabilized platinum and gold nanoparticles. Quantitative analysis provides insights into short- and long-range nanoparticle-nanoparticle correlations, and local and global contributions to structural chirality in the networks. Results provide synthesis criteria for next-generation mesoporous network superstructures from binary nanoparticle mixtures for potential applications in areas including catalysis.

Li, Zihui; Hur, Kahyun; Sai, Hiroaki; Higuchi, Takeshi; Takahara, Atsushi; Jinnai, Hiroshi; Gruner, Sol M.; Wiesner, Ulrich

2014-02-01

85

Frequency-selective surface coupled metal-oxide-metal diodes  

NASA Astrophysics Data System (ADS)

Metal-Oxide-Metal diodes offer the possibility of directly rectifying infrared radiation. To be effective for sensing or energy harvesting they must be coupled to an antenna which produces intense fields at the diode. While antennas significantly increase the effective capture area of the MOM diode, it is still limited and maximizing the captured energy is still a challenging goal. In this work we investigate integrating MOM diodes with a slot antenna Frequency Selective Surface (FSS). This maximizes the electromagnetic capture area while minimizing the transmission line length which helps reduce losses because metal losses are much lower at DC than at infrared frequencies. Our design takes advantage of a single self-aligned patterning step using shadow evaporation. The structure is optimized at 10.6 µm to have less than 2% reflection (polarization sensitive) and simulations predict that 70% of the incident energy is dissipated into the oxide layer. Initial experimental results fabricated with e-beam lithography are presented and the diode coupled FSS is shown to produce a polarization sensitive unbiased DC short circuit current. This work is promising for both infrared sensing and imaging as well as direct conversion of thermal energy.

Kinzel, Edward C.; Brown, Robert L.; Ginn, James C.; Lail, Brian A.; Slovick, Brian A.; Boreman, Glenn D.

2013-06-01

86

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

PubMed

The macroalga Gracilaria domingensis is an important resource for the food, pharmaceutical, cosmetic, and biotechnology industries. G. domingensis is at a part of the food web foundation, providing nutrients and microelements to upper levels. As seaweed storage metals in the vacuoles, they are considered the main vectors to magnify these toxic elements. This work describes the evaluation of the toxicity of binary mixtures of available metal cations based on the growth rates of G. domingensis over a 48-h exposure. The interactive effects of each binary mixture were determined using a toxic unit (TU) concept that was the sum of the relative contribution of each toxicant and calculated using the ratio between the toxicant concentration and its endpoint. Mixtures of Cd(II)/Cu(II) and Zn(II)/Ca(II) demonstrated to be additive; Cu(II)/Zn(II), Cu(II)/Mg(II), Cu(II)/Ca(II), Zn(II)/Mg(II), and Ca(II)/Mg(II) mixtures were synergistic, and all interactions studied with Cd(II) were antagonistic. Hypotheses that explain the toxicity of binary mixtures at the molecular level are also suggested. These results represent the first effort to characterize the combined effect of available metal cations, based on the TU concept on seaweed in a total controlled medium. The results presented here are invaluable to the understanding of seaweed metal cation toxicity in the marine environment, the mechanism of toxicity action and how the tolerance of the organism. PMID:24920431

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

2014-07-01

87

BINARY EXTRACTING AGENTS FOR RARE-EARTH METAL SEPARATION  

Microsoft Academic Search

Extraction is one of the efficient hydrometallurgical technologies used to solve the problem of in- dustrial separation of elements having similar chemical properties, including lanthanides(III). Cation- exchange extracting agents of phosphoric acid dialkyl ether group are characterized by the highest figures of the rare-earth metal separation factors, most often of which di(2-ethylhexyl)phosphoric acid (D2EGF?) is used. There exists the problem

S. N. Kalyakin; V. I. Kuzmin

2009-01-01

88

Observations of Electron Irradiation Effects at Transition Metal Oxide Surfaces.  

NASA Astrophysics Data System (ADS)

In this dissertation the effects of electron irradiation on several maximally-valent transition-metal oxides have been investigated using a combination of surface profile imaging, selected-area-electron diffraction, optical diffractograms, and electron-energy-loss spectroscopy. It was found that the surfaces of TiO_2, Nb _2O_5, V_2 O_5 and Ti_2 Nb_{10}O _{29} were reduced to the corresponding binary oxide phase inside a 400keV high-resolution electron microscope during observation at high magnification and high current density (5-50A/cm^2). These reduced surface phases, which are all based on cubic rock -salt structures, grow with a well-defined three-dimensional epitaxial relationship with the bulk oxide. Certain structural features of the epitaxy were found to be common to the oxides studied and computer-drawn models of the crystalline structures were used to gain insight into the atomic rearrangements which took place during the monoxide growth. In the case of WO_3, for which no stable monoxide phase has been reported, the striking similarity in the epitaxial growth of a surface phase led to the proposal of a novel monoxide phase. The metallic conductivity of each of these monoxide phases was considered to be significant in terms of the mechanism which is proposed to initiate the electron-stimulated-desorption of oxygen from the original oxides. Evidence for a current density threshold for the accumulation of the monoxide phase and observation of recrystallization below this threshold are reported. In contrast, in response to extremely high-current density irradiation (10 ^3-10^4A/cm ^2), the surfaces of these oxides developed sputter pits and were reduced beyond the monoxide phase. These observations were repeated for TiO_2 in a ultra-high-vacuum microscope. Secondary electron images, high-angle annular dark-field images and EELS confirmed that the improved vacuum did not affect substantially the beam-induced reactions.

McCartney, Martha Rogers

89

Graphene oxide-based flexible metal-insulator-metal capacitors  

NASA Astrophysics Data System (ADS)

This work explores the fabrication of graphene oxide (GO)-based metal-insulator-metal (MIM) capacitors on flexible polyethylene terephthalate (PET) substrates. Electrical properties are studied in detail. A high capacitance density of ˜4 fF µm-2 measured at 1 MHz and permittivity of ˜6 have been obtained. A low voltage coefficient of capacitance, VCC-?, and a low dielectric loss tangent indicate the potential of GO-based MIM capacitors for RF applications. The constant voltage stressing study has shown a high reliability against degradation up to a projected period of 10 years. Degradation in capacitance of the devices on flexible substrates has been studied by bending radius down to 1 cm even up to 6000 times of repeated bending.

Bag, A.; Hota, M. K.; Mallik, S.; Maiti, C. K.

2013-05-01

90

Transition metal oxide improves overall efficiency and maintains performance with inexpensive metals.  

E-print Network

Transition metal oxide improves overall efficiency and maintains performance with inexpensive that inserting a transition metal oxide (TMO) between the lead sulfide (PbS) quantum dot (QD) layer and the metal Oxide as a Hole Extraction Layer in PbS Quantum Dot Solar Cells."Nano Letters 11, 3263 (2011). Key

91

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

92

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

93

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

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 change us, but we start and end with family" -Anthony Brandt ii #12;Acknowledgements I would like Metal Oxides and Rare Earth Metals by Brian Ross Maddox Electron correlation can affect profound changes

Islam, M. Saif

95

Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu-Ag and Cu-Ni  

E-print Network

Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu to obtain an atomistic description of the melting, glass formation, and crystallization processes in metal glass formation. S0163-1829 99 05205-4 I. INTRODUCTION Metal glasses were prepared1 by the Duwez group

Goddard III, William A.

96

The Effect of Metal Oxide on Nanoparticles from Thermite Reactions  

ERIC Educational Resources Information Center

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

Moore, Lewis Ryan

2006-01-01

97

Structure and stability of binary metal alloys. Precipitation treated via ab-initio calculations  

Microsoft Academic Search

Theoretical studies of substitutional ordering phenomena in binary metal alloys demands the consid- eration of both huge parameter-spaces (e.g. for ground-state searches) and systems containing more than a million atoms (e.g. for precipitation). The combination of density functional theory calculations (DFT) with cluster expansion methods (CE) and Monte-Carlo (MC) simulations fulfills these requirements. They can be applied to study properties

STEFAN MÜLLER

98

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

99

Point defect concentration relaxation and creep transients in binary oxides  

Microsoft Academic Search

In non-stoichiometric oxides (NiO, CoO, Cu2O…) two thermodynamic parameters (temperature T and partial pression of oxygen Po2) are necessary in order to fix the population of point defects. When one of these two parameters (T or Po2) is suddenly changed and a physical property is continuously recorded, a “transient” can be observed due to the diffusion of the point defects

M. Jiménez-Melendo; A. Domínguez-Rodríguez; J. Castaing

1995-01-01

100

X-ray binary formation in low-metallicity blue compact dwarf galaxies  

NASA Astrophysics Data System (ADS)

X-rays from binaries in small, metal-deficient galaxies may have contributed significantly to the heating and reionization of the early Universe. We investigate this claim by studying blue compact dwarfs (BCDs) as local analogues to these early galaxies. We constrain the relation of the X-ray luminosity function (XLF) to the star formation rate (SFR) using a Bayesian approach applied to a sample of 25 BCDs. The functional form of the XLF is fixed to that found for near-solar metallicity galaxies and is used to find the probability distribution of the normalization that relates X-ray luminosity to SFR. Our results suggest that the XLF normalization for low-metallicity BCDs (12+log(O/H) < 7.7) is not consistent with the XLF normalization for galaxies with near-solar metallicities, at a confidence level 1-5 × 10- 6. The XLF normalization for the BCDs is found to be 14.5± 4.8 ({M}_{?}^{-1} yr), a factor of 9.7 ± 3.2 higher than for near-solar metallicity galaxies. Simultaneous determination of the XLF normalization and power-law index result in estimates of q = 21.2^{+12.2}_{-8.8} ({M}_{?}^{-1} yr) and ? = 1.89^{+0.41}_{-0.30}, respectively. Our results suggest a significant enhancement in the population of high-mass X-ray binaries in BCDs compared to the near-solar metallicity galaxies. This suggests that X-ray binaries could have been a significant source of heating in the early Universe.

Brorby, M.; Kaaret, P.; Prestwich, A.

2014-07-01

101

Oxidation effect on templating of metal oxide nanoparticles within block copolymers  

E-print Network

Oxidation effect on templating of metal oxide nanoparticles within block copolymers Pinar Akcora a-norbornene dicarboxylic acid) (NOR-NORCOOH) have been synthesized and processed to template metal oxide nanoparticle. Block copolymers with iron oxide nano- particles have been used, for example, in the development of nano

Kofinas, Peter

102

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

103

Non-platinum electrocatalysts: Manganese oxide nanoparticle-cobaltporphyrin binary catalysts for oxygen reduction  

Microsoft Academic Search

This study is concerned with the development of non-platinum electrocatalysts for the efficient 4-electron reduction of molecular\\u000a oxygen to water in acidic media. A binary catalyst composed of electrodeposited manganese oxide nanoparticles (nano-MnO\\u000a x\\u000a ) and cobalt porphyrin macro complex (CoP) has been proposed in. The modification of glassy carbon (GC) electrode with CoP\\u000a alone resulted in a significant positive

Mohamed S. El-Deab; Sameh H. Othman; Takeyoshi Okajima; Takeo Ohsaka

2008-01-01

104

Sensing using nanostructured metal oxide thin films  

NASA Astrophysics Data System (ADS)

Metal oxides gas sensing properties particularly for In IIO 3 and ZnO nanostructures and nanostructured thin films are reviewed. Fabrication methods for these most commonly used metal oxides are presented, followed by a study on how growth techniques lead to nanostructures and nanostructured polycrystalline films with surface features of nanometer scale for film thickness bellow 1?m. The study continues with a discussion on how, a broad range of morphological parameters, affect the thin film response to various gases. After an overview, the study focus on thin films prepared by reactive dc magnetron sputtering and pulsed laser deposition in different growth conditions. In IIO 3 and ZnO thin films prepared for ozone sensing exhibit resistivity changes of five to eight orders of magnitude at room temperature after exposure to UV light and subsequent ozone treatment. Structural properties, i.e., crystallinity and microstructure investigated by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) are studied. The nanostructure and nanostructured surfaces are highly controlled by the deposition parameters, which, control the transport properties, and thus the sensing characteristics as measured by conductometric techniques. Analyses on the sensing response of nanostructures and nanostructured In IIO 3 and ZnO films for different gases are presented. Experiments on Surface Acoustic Wave (SAW) devices based on In IIO 3 and ZnO thin films fabricated on LiNbO3 substrates indicate the capability of achieving sensing levels in the low ppb range.

Kiriakidis, G.; Dovinos, D.; Suchea, M.

2006-10-01

105

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

106

FUNCTIONALIZED METAL OXIDE NANOPARTICLES: ENVIRONMENTAL TRANSFORMATIONS AND ECOTOXICITY  

EPA Science Inventory

This study will provide fundamental information on alterations in the surface chemistry of commercially important functionalized metal oxide NPs under environmentally relevant oxidative and reductive conditions, as well as needed data on the inherent and photo-enhanced toxicit...

107

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

108

Adsorption of bovine serum albumin onto metal oxide surfaces  

Microsoft Academic Search

The adsorption of bovine serum albumin (BSA) on surfaces of silicon dioxide (silica), titanium dioxide (titania), zirconium oxide (zirconia), and aluminium oxide (alumina) was studied as a function of pH. The adsorption isotherms for these metal oxides showed well-defined saturation plateaus in the pH range of 3.5 to 9.0. On positively charged metal oxides the isotherms showed a steeper initial

Satoshi Fukuzaki; Hiromi Urano; Kazuya Nagata

1996-01-01

109

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

2014-10-20

110

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

111

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

112

Periodic models in quantum chemical simulations of F centers in crystalline metal oxides  

NASA Astrophysics Data System (ADS)

We present a survey of recent first principles simulations of the neutral oxygen vacancies (F centers) existing as native or radiation-induced point defects in various crystalline metal oxides in different forms (bulk, bare substrate surface, and on the interface with metal adsorbates). We mainly consider periodic models in calculations of point defects using the metal oxide supercell or cyclic clusters. We compare different formalisms of first principles calculations, mostly the Density Functional Theory (DFT) as implemented in the framework of either localized basis set of atomic orbitals or delocalized basis sets of plane waves. We analyze in detail the structural and electronic properties of F centers in binary oxides of light metals (MgO and Al2O3), and ternary metal oxides (SrTiO3, BaTiO3, PbTiO3, KNbO3, and PbZrO3 perovskites). When available, we compare results of ab initio periodic defect calculations with experimental data, results of the first principles cluster calculations (both embedded and molecular) as well as with semi-empirical calculations.0

Zhukovskii, Yuri F.; Kotomin, Eugene A.; Evarestov, Robert A.; Ellis, Donald E.

113

Adventures with substances containing metals in negative oxidation states.  

PubMed

A brief history of substances containing s,p- and d-block metals in negative oxidation states is described. A classification of these species and discussions of formal oxidation state assignments for low-valent transition metals in complexes are included, along with comments on the innocent and noninnocent character of ligands in metalates. Syntheses of highly reduced carbonyl complexes formally containing transition metals in their lowest known oxidation states of III- and IV- are discussed. Atmospheric-pressure syntheses of early-transition-metal carbonyls involving alkali-metal polyarene-mediated reductions of non-carbonyl precursors have been developed. In the absence of carbon monoxide, these reactions afford homoleptic polyarenemetalates, including the initial species containing three aromatic hydrocarbons bound to one metal. In several instances, these metalates function as useful synthons for "naked" spin-paired atomic anions of transition metals. PMID:16602773

Ellis, John E

2006-04-17

114

On the partial oxidation of propane and propylene on mixed metal oxide catalysts  

Microsoft Academic Search

The present review analyses the literature data reported on the partial oxidation of propane to organic compounds (acrolein, acrylic acid and acrylonitrile) over mixed metal oxides, mainly magnesium vanadates, vanadia bismuth molybdates and vanadia antimony. The data were compared to those reported on the partial oxidation of propylene over bismuth molybdate and antimony—tin multicomponent oxides and over cuprous simple oxide.

M. M. Bettahar; G. Costentin; L. Savary; J. C. Lavalley

1996-01-01

115

Microstructural Characterization of Base Metal Alloys with Conductive Native Oxides for Electrical Contact Applications  

NASA Astrophysics Data System (ADS)

Metallic contacts are a ubiquitous method of connecting electrical and electronic components/systems. These contacts are usually fabricated from base metals because they are inexpensive, have high bulk electrical conductivities and exhibit excellent formability. Unfortunately, such base metals oxidize in air under ambient conditions, and the characteristics of the native oxide scales leads to contact resistances orders of magnitude higher than those for mating bare metal surface. This is a critical technological issue since the development of unacceptably high contact resistances over time is now by far the most common cause of failure in electrical/electronic devices and systems. To overcome these problems, several distinct approaches are developed for alloying base metals to promote the formation of self-healing inherently conductive native oxide scales. The objective of this dissertation study is to demonstrate the viability of these approaches through analyzing the data from Cu-9La (at%) and Fe-V binary alloy systems. The Cu-9 La alloy structure consists of eutectic colonies tens of microns in diameter wherein a rod-like Cu phase lies within a Cu6La matrix phase. The thin oxide scale formed on the Cu phase was found to be Cu2O as expected while the thicker oxide scale formed on the Cu6La phase was found to be a polycrystalline La-rich Cu2O. The enhanced electrical conductivity in the native oxide scale of the Cu-9La alloy arises from heavy n-type doping of the Cu2O lattice by La3+. The Fe-V alloy structures consist of a mixture of large elongated and equiaxed grains. A thin polycrystalline Fe3O4 oxide scale formed on all of the Fe-V alloys. The electrical conductivities of the oxide scales formed on the Fe-V alloys are higher than that formed on pure Fe. It is inferred that this enhanced conductivity arises from doping of the magnetite with V+4 which promotes electron-polaron hopping. Thus, it has been demonstrated that even in simple binary alloy systems one can obtain a dramatic reduction in the contact resistances of alloy oxidized surfaces as compared with those of the pure base metals.

Senturk, Bilge Seda

116

Atomic layer deposition of the aluminum oxide-yttrium oxide pseudo-binary system  

NASA Astrophysics Data System (ADS)

The growth of thin films of selected phases from the pseudo-binary Al 2O3-Y2O3 material system was demonstrated using atomic layer deposition (ALD). Specifically ALD growth of Al2O 3, Y2O3, Ce2O3, Y2 Al4O12 (Yttrium Aluminum Monoclinic - YAM), and Y3Al5O12 (Yttrium Aluminum Garnet - YAG) was accomplished. All films were grown using the same precursors: AlCl 3 at 105°C and H2O, Y(thd)3 [thd = 2,2,6,6-tetramethyl-3,5-heptanedione] at 140°C and O3, and Ce(acac)3 [acac = acetylacetonate] at 140°C, and O3. The Al2O3 films were grown at substrate temperatures from 295°C to 515°C. A surface-controlled growth temperature 'window' (ALD window) was found for Al 2O3 between 365°C to 465°C using AlCl3 and H2O. The resultant films grown at all temperatures were amorphous as characterized by X-ray diffraction, and showed a rough surface morphology. The growth rate was determined to be 1 A/cycle within the ALD 'window'. The thickness of films grown in the ALD 'window' varied linearly with the number of cycles. Films up to 1 microm thick were grown (10,000 cycles). The Y2O3 films were grown at substrate temperatures ranging from 200°C to 500°C. No surface-controlled growth temperature window could be determined using Y(thd)3 and O3. The resultant films were polycrystalline with a cubic structure and a smooth surface morphology. The growth rate was determined to be 3 pm/cycle at 350°C. Films up to 30 nm thick were grown (10,000 cycles). Atomic layer deposition of Ce2O3 thin films were also studied because Ce3+ is often used as a luminescent rare earth dopant in YAG and YAM. The Ce2O3 films were grown at substrate temperatures from 200°C to 500°C. No surface-controlled growth temperature window could be found using Ce(acac)3 and O 3. The resultant films had a rough surface morphology. Using X-ray photoelectron spectroscopy (XPS), it was determined that the Ce3+ oxidation state was present in the as-deposited films rather than Ce4+. When included in the growth process for YAG and YAM, Ce2O 3 was found to create very rough surfaces. The ternary oxide phases of YAM and YAG were produced by ALD growth of alternating nano-scaled multilayer stacks of Al2O3 and Y2O3 and subsequent calcinations of these thin nano-scale stack structures. By adjusting the ratio of Al2O 3 deposition cycles to Y2O3 deposition cycles, stoichiometric amounts of material were deposited in an alternating fashion. A 300 nm YAG film was deposited using the ALD method at a substrate growth temperature of 350°C. X-ray diffraction data showed that these films were amorphous as-deposited, but they were transformed to a polycrystalline cubic garnet structure when calcined at 975°C for 12 hrs in air. The surface morphology was uniform and smooth. A 400 nm YAM thin film was also successfully deposited using the ALD method at a growth temperature of 350°C. X-ray diffraction of the YAM film showed an amorphous film as-deposited and a polycrystalline monoclinic structure after calcining at 975°C for 12 hrs in air. The surface morphology of this YAM film was rough and non-uniform.

Rowland, Jason Conrad

117

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

118

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

119

A General Approach to Noble Metal-Metal Oxide Dumbbell Nanoparticles and Their Catalytic Application for CO Oxidation  

SciTech Connect

Heterogeneous dumbbell-like nanoparticles represent an important type of composite nanomaterial that has attracted growing interest. Here we report a general approach to noble metal-metal oxide dumbbell nanoparticles based on seed-mediated growth. Metal oxides are grown over the presynthesized noble metal seeds by thermal decomposition of metal carbonyl followed by oxidation in air. The as-synthesized dumbbell nanoparticles have intrinsic epitaxial linkage between the metal and the oxide, providing enhanced heterojunction interactions. Moreover, the properties of one component are readily modified by the other in these nanoparticles, as demonstrated by the enhanced catalytic activity toward CO oxidation of such dumbbell nanoparticles in comparison with their counterparts prepared by conversional methods. The heterojunction effects provided in such nanostructures thus offer another degree of freedom for tailoring material properties. The developed synthetic strategy could also be generalized to other systems and thus represent a general approach to heterogeneous nanomaterials for various functional applications.

Dai, Sheng [ORNL; Wang, Chao [Brown University; Yin, Hongfeng [ORNL; Sun, Shouheng [ORNL

2010-01-01

120

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

121

Development of metal oxide catalysts for the removal of vocs  

Microsoft Academic Search

Metal oxide catalysts were tested for the removal of volatile organic compounds (VOCs) in an atmospheric fixed bed flow reactor. Silver containing mixed oxide was highly active when it was calcined at lower temperature (400 °C) due to the surface exposed metallic Ag?. However, when the catalyst was calcined at higher temperature (800 °C), it became less active since Ag?

Sung-Hee Kim; Young-Chul Kim; Nam-Cook Park

1999-01-01

122

Superconductivity in the metallic-oxidized magnesium interface  

NASA Astrophysics Data System (ADS)

Metastable superconductivity at 39-54 K in the interfaces formed by metallic and oxidized magnesium (MgO) has been observed by ac magnetic susceptibility measurements. The superconducting interfaces have been produced by the surface oxidation of metallic magnesium under special conditions.

Sidorov, N. S.; Palnichenko, A. V.; Khasanov, S. S.

2012-03-01

123

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

NASA Astrophysics Data System (ADS)

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

Carnes, Corrie Leigh

124

The role of metallicity in high mass X-ray binaries in galaxy formation models  

E-print Network

Context: Recent theoretical works claim that high-mass X-ray binaries (HMXBs) could have been important sources of energy feedback into the interstellar and intergalactic media, playing a major role in the reionization epoch. A metallicity dependence of the production rate or luminosity of the sources is a key ingredient generally assumed but not yet probed. Aims: Our goal is to explore the relation between the X-ray luminosity (Lx) and star formation rate of galaxies as a possible tracer of a metallicity dependence of the production rates and/or X-ray luminosities of HMXBs. Methods: We developed a model to estimate the Lx of star forming galaxies based on stellar evolution models which include metallicity dependences. We applied our X-ray binary models to galaxies selected from hydrodynamical cosmological simulations which include chemical evolution of the stellar populations in a self-consistent way. Results: Our models successfully reproduce the dispersion in the observed relations as an outcome of the com...

Artale, M C; Tissera, P B

2014-01-01

125

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

126

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

127

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

128

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

Kronberg, James W. (108 Independent Blvd., Aiken, SC 29801)

1992-01-01

129

The spectral behaviour of A-type metallic line spectroscopic binary 41 Sex A  

NASA Astrophysics Data System (ADS)

Revised orbital elements of the A3 Vm type single line spectroscopic binary 41 Sex A are presented. Along with many Am stars, 41 Sex A also shows a pseudo-luminosity effect quite clearly at a higher dispersion. Metallic lines in its spectra show pronounced variation with phase, the maximum strengths occurring at approximately 0.25, 0.5, 0.75, and 1.0 of its orbital phase. The star appears to have four abundance patches indicating a quadrupole magnetic configuration. The phase modulated spectral variation in 41 Sex A suggests that it represents a new class of Am variables.

Rao, S. S.; Abhyankar, K. D.; Nagar, Praveen

1990-09-01

130

Valence electronic structure and cohesive property of a binary noble metal nitride  

Microsoft Academic Search

The valence electronic structure of a newly synthesized binary noble metal nitride PtN is obtained by utilizing an empirical\\u000a electronic theory. The results reveal that the valence electron configuration of the nitride is: Pt 6s 0.143, 6p 1.286, 5d\\u000a 3.0; N 2s 0.5694, 2p 2.4306. Such a configuration is different from that used to generate pseudopotential for the first principle

Changzeng Fan; Liling Sun; Jun Zhang; Yuanzhi Jia; Lianyong Zhang; Zunjie Wei; Mingzhen Ma; Riping Liu; Songyan Zeng; Wenkui Wang

2005-01-01

131

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

132

An electro-thermal model for metal-oxide-metal antifuses  

Microsoft Academic Search

In this paper, a complete electro-thermal analysis is presented for the metal-oxide-metal antifuses. The application of the Wiedemann-Franz Law and the thin film effect on thermal and electrical conductivities of metal films were also discussed. Several key parameters for tungsten-oxide-tungsten antifuse were extracted. The reaction temperature between tungsten and oxide was estimated to be around 1300°C. The core resistivity was

Guobiao Zhang; Chenming Hu; Peter Y. Yu; Steve Chiang; Shafy Eltoukhy; E. Z. Hamdy

1995-01-01

133

Stabilization of electrocatalytic metal nanoparticles at metal-metal oxide-graphene triple junction points.  

PubMed

Carbon-supported precious metal catalysts are widely used in heterogeneous catalysis and electrocatalysis, and enhancement of catalyst dispersion and stability by controlling the interfacial structure is highly desired. Here we report a new method to deposit metal oxides and metal nanoparticles on graphene and form stable metal-metal oxide-graphene triple junctions for electrocatalysis applications. We first synthesize indium tin oxide (ITO) nanocrystals directly on functionalized graphene sheets, forming an ITO-graphene hybrid. Platinum nanoparticles are then deposited, forming a unique triple-junction structure (Pt-ITO-graphene). Our experimental work and periodic density functional theory (DFT) calculations show that the supported Pt nanoparticles are more stable at the Pt-ITO-graphene triple junctions. Furthermore, DFT calculations suggest that the defects and functional groups on graphene also play an important role in stabilizing the catalysts. These 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. PMID:21302925

Kou, Rong; Shao, Yuyan; Mei, Donghai; Nie, Zimin; Wang, Donghai; Wang, Chongmin; Viswanathan, Vilayanur V; Park, Sehkyu; Aksay, Ilhan A; Lin, Yuehe; Wang, Yong; Liu, Jun

2011-03-01

134

Thermodynamics of toxic gas molecules on metal oxide nano powders  

Microsoft Academic Search

Studies on physical\\/chemical reactions of gas molecules on nano sized metal oxide powder surface is interesting because the results from the research can directly be applied to the investigation of the surface mediated catalytic reactions aimed at reducing atmospheric pollutants. Thermodynamic properties of nitrous oxides (NOx) on varies nano sized metal oxides such as MgO and ZnO powders were studied

Jae-Yong Kim; Chae-Ok Kim

2005-01-01

135

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

136

Micro- and nano-structured metal oxides based chemical sensors: an overview.  

PubMed

This article examines various kinds of chemical sensors, their mechanism of operation and the ways to improve their performance. It reports the results of exploratory investigation of binary composite polycrystalline thick-films such as SnO2-WO3, SnO2-In2O3, and SnO2-ZnO for the detection of volatile organic compound (isopropanol) are reported. It also contains an overview on the status of the new types of metal oxide based nanostructured sensors, such as nano belts, nanorods, nanotubes, nanofibers, nanocomposites, etc. PMID:24749474

Batra, Ashok K; Chilvery, A K; Guggilla, Padmaja; Aggarwal, Mohan; Currie, James R

2014-02-01

137

First stars XI. Chemical composition of the extremely metal-poor dwarfs in the binary CS 22876-032  

Microsoft Academic Search

Context: Unevolved metal-poor stars constitute a fossil record of the early Galaxy, and can provide invaluable information on the properties of the first generations of stars. Binary systems also provide direct information on the stellar masses of their member stars. Aims: The purpose of this investigation is a detailed abundance study of the double-lined spectroscopic binary CS 22876-032, which comprises

J. I. González Hernández; P. Bonifacio; H.-G. Ludwig; E. Caffau; M. Spite; F. Spite; R. Cayrel; P. Molaro; V. Hill; P. François; B. Plez; T. C. Beers; T. Sivarani; J. Andersen; B. Barbuy; E. Depagne; B. Nordström; F. Primas

2008-01-01

138

XANES investigation of phosphate sorption in single and binary systems of iron and aluminum oxide minerals.  

PubMed

Phosphate sorption on Fe- and Al-oxide minerals helps regulate the solubility and mobility of P in the environment. The objective of this study was to characterize phosphate adsorption and precipitation in single and binary systems of Fe- and Al-oxide minerals. Varying concentrations of phosphate were reacted for 42 h in aqueous suspensions containing goethite, ferrihydrite, boehmite, or noncrystalline (non-xl) Al-hydroxide, and in 1:1 (by mass) mixed-mineral suspensions of goethite/boehmite and ferrihydrite/ non-xl Al-hydroxide at pH 6 and 22 degrees C. X-ray absorption near edge structure (XANES) spectroscopy was used to detect precipitated phosphate and distinguish PO4 associated with Fe(III) versus Al(III) in mixed-mineral systems. Changes in the full width at half-maximum height (fwhm) in the white-line peak in P K-XANES spectra provided evidence for precipitation in Al-oxide single-mineral systems, but not in goethite or ferrihydrite systems. Similarly, adsorption isotherms and XANES data showed evidence for precipitation in goethite/boehmite mixtures, suggesting that mineral interactive effects on PO4 sorption were minimal. However, sorption in ferrihydrite/non-xl Al-hydroxide systems and a lack of XANES evidence for precipitation indicated that mineral interactions inhibited precipitation in these binary mixtures. PMID:15871250

Khare, Nidhi; Hesterberg, Dean; Martin, James D

2005-04-01

139

Nano Fabrication of Functional Transition Metal Oxide Thin Films  

Microsoft Academic Search

Transition metal oxide films show a rich variety of peculiar properties, such as ferroelectricity, ferromagnetism, high Tc superconductivity, colossal magnetoresistance, and so on. The method to process the oxide films down to nano scale is still under development. In this paper we introduce several techniques to process oxide films on the basis of AFM lithography and nanoimprint lithography. Using AFM

Naoki Suzuki; Hidekazu Tanaka; Yoshihiko Yanagisawa; Satoru Yamanaka; Luca Pellegrino; Bong Kuk Lee; Hea Yeon Lee; Tomoji Kawai

2008-01-01

140

Synthesis of Epitaxial Metal Oxide Nanocrystals via a Phase Separation  

E-print Network

and catalytical properties.24 26 Additionally, the possibility to oxidize the high-density Mn3O4 spinel and magnetic manganese oxide islands. Subsequent cooling in vacuum eSynthesis of Epitaxial Metal Oxide Nanocrystals via a Phase Separation Approach Kashinath A. Bogle

Castell, Martin

141

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

SciTech Connect

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

Scalettar, Richard T.; Pickett, Warren E.

2004-07-01

142

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

143

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

144

Effect of surface physics of metal oxides on the ability to form metallic nanowires  

NASA Astrophysics Data System (ADS)

Through the control of surface physics of oxide films, nanowires of various metals can be readily grown on the surface of oxide films without templates and surfactants. To clarify how the characteristics of oxides affect the formation of metallic nanowires, this report investigated the influence of the surface physical characteristics, including morphological, electrical, optical and hydrophilic properties of the metal oxide substrates (TiO2, CeO2, and indium tin oxide), on the yield of Ag and Pt nanowires. In addition to the surface roughness, photo-induced defects were suggested to be the key factor dominating the number of nucleation sites and thus the population of nanowires.

Song, Jenn-Ming; Chen, Shih-Yun; Shen, Yu-Lin; Tsai, Chi-Hang; Feng, Shih-Wei; Tung, Hsien-Tse; Chen, In-Gann

2013-11-01

145

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2010-07-01

146

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2013-07-01

147

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2011-07-01

148

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...721.10148 Acryloxy alkanoic alkane derivative with mixed metal oxides (generic...generically as acryloxy alkanoic alkane derivative with mixed metal oxides (PMN...

2012-07-01

149

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

150

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

151

Biomimetic metal oxides for the extraction of nanoparticles from water  

NASA Astrophysics Data System (ADS)

Contamination of nanomaterials in the environment will pose significant health risks in the future. A viable purification method is necessary to address this problem. Here we report the synthesis and application of a series of metal oxides prepared using a biological template for the removal of nanoparticles from the aqueous environment. A simple synthesis of metal oxides such as ZnO, NiO, CuO, Co3O4 and CeO2 employing eggshell membrane (ESM) as a biotemplate is reported. The morphology of the metal oxide powders was characterized using electron microscopes and the lattice structure was established using X-ray diffraction methods. Extraction of nanoparticles from water was carried out to compare the efficiency of metal oxides. NiO showed good extraction efficiency in removing gold and silver nanoparticles from spiked water samples within an hour. Easy access and enhanced stability of metal oxides makes them interesting candidates for applications in industrial effluent treatments and water purifications.Contamination of nanomaterials in the environment will pose significant health risks in the future. A viable purification method is necessary to address this problem. Here we report the synthesis and application of a series of metal oxides prepared using a biological template for the removal of nanoparticles from the aqueous environment. A simple synthesis of metal oxides such as ZnO, NiO, CuO, Co3O4 and CeO2 employing eggshell membrane (ESM) as a biotemplate is reported. The morphology of the metal oxide powders was characterized using electron microscopes and the lattice structure was established using X-ray diffraction methods. Extraction of nanoparticles from water was carried out to compare the efficiency of metal oxides. NiO showed good extraction efficiency in removing gold and silver nanoparticles from spiked water samples within an hour. Easy access and enhanced stability of metal oxides makes them interesting candidates for applications in industrial effluent treatments and water purifications. Electronic supplementary information (ESI) available: XRD and EDS analysis of the prepared metal oxides, EDS analysis of nanoparticles adsorbed on the surface of metal oxides and SEM micrographs of metal oxides are included. See DOI: 10.1039/c3nr34221b

Mallampati, Ramakrishna; Valiyaveettil, Suresh

2013-03-01

152

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

153

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

154

Metallicity Effect on Low-mass X-Ray Binary Formation in Globular Clusters  

NASA Astrophysics Data System (ADS)

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?) in LMXBs with luminosities in the range L X = 2 × 1037 to 5 × 1038 erg s-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 1036 erg s-1) and higher luminosities (up to the ULX regime), but with less significance (~2? 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.; Ivanova, N.; Fragos, T.; Jordán, A.; Sivakoff, G. R.; Voss, R.

2013-02-01

155

Nanoscale Metal Oxide Semiconductors for Gas Sensing  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

156

Absolute dimensions of detached eclipsing binaries. I. The metallic-lined system WW Aurigae  

E-print Network

WW Aurigae is a detached eclipsing binary composed of two metallic-lined A-type stars orbiting each other every 2.5 days. We have determined the masses and radii of both components to accuracies of 0.4 and 0.6 percent, respectively. From a cross-correlation analysis of high-resolution spectra we find masses of 1.964 +/- 0.007 Msun for the primary star and 1.814 +/- 0.007 Msun for the secondary star. From an analysis of photoelectric uvby and UBV light curves we find the radii of the stars to be 1.927 +/- 0.011 Rsun and 1.841 +/- 0.011 Rsun, where the uncertainties have been calculated using a Monte Carlo algorithm. Fundamental effective temperatures of the two stars have been derived, using the Hipparcos parallax of WW Aur and published ultraviolet, optical and infrared fluxes, and are 7960 +/- 420 and 7670 +/- 410 K. The masses, radii and effective temperatures of WW Aur are only matched by theoretical evolutionary models for a fractional initial metal abundance, Z, of approximately 0.06 and an age of roughly 90 Myr. This seems to be the highest metal abundance inferred for a well-studied detached eclipsing binary, but we find no evidence that it is related to the metallic-lined nature of the stars. The circular orbit of WW Aur is in conflict with the circularization timescales of both the Tassoul and the Zahn tidal theories and we suggest that this is due to pre-main-sequence evolution or the presence of a circular orbit when the stars were formed.

John Southworth; B Smalley; P F L Maxted; A Claret; P B Etzel

2005-07-27

157

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

158

Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis  

NASA Astrophysics Data System (ADS)

Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO2, ZrO2, Al 2O3) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular reaction, I found that Pd nanoparticles supported on mesoporous TiO2 exhibit the best catalytic performance. The demonstrated low-cost and high-productivity preparation method can be extended to other catalysts, which can contain various metals and oxide substrates and will have high potential for industrial applications. Our preparation method also provides a platform for the studies of the synergetic catalytic effects between different oxide substrates and metals. I further fabricated hollow mesoporous microspheres containing differently shaped noble metal nanocrystals. Hollow structures are strongly desired in many applications because of their high pore volumes, surface areas, and possible light-trapping effect. In my study, the hollow structures were obtained by simply dispersing polystyrene (PS) nanospheres into the precursor solution for aerosol spray. The PS spheres were removed by thermal calcination to produce hollow mesoporous microspheres. In my first study, the noble metal salts were dissolved in the precursor solutions, and the noble metal nanoparticles were obtained through thermal calcination. In this way, the size and shape of the metal nanoparticles cannot be well controlled. In my second study, I first grew noble metal nanocrystals and then incorporated them into the oxide supports. This preparation route allowed me to incorporate metal nanocrystals with controlled sizes, shapes, and compositions into the oxide matrices. The metal nanocrystals I used in this experiment included Pd nanocubes, Au nanorods, and Au core--Pd shell nanorods. These nanocrystals were functionalized with thiol-terminated methoxypoly(ethylene glycol) . The surface functionalization allowed them to adsorb on the PS spheres. After thermal calcination, the noble metal nanocrystals were left inside and adsorbed on the inner surface of the hollow mesoporous metal oxide microspheres. I investigated the catalytic activities of the Pd nanocube-embedded hollow mesoporous TiO2 and ZrO2 microspheres for the reduction of 4-nitrophenol to 4-aminophenol. I also examined the recycla

Jin, Zhao

159

Interaction of nanostructured metal overlayers with oxide surfaces  

NASA Astrophysics Data System (ADS)

Interactions between metals and oxides are key factors to determine the performance of metal/oxide heterojunctions, particularly in nanotechnology, where the miniaturization of devices down to the nanoregime leads to an enormous increase in the density of interfaces. One central issue of concern in engineering metal/oxide interfaces is to understand and control the interactions which consist of two fundamental aspects: (i) interfacial charge redistribution — electronic interaction, and (ii) interfacial atom transport — chemical interaction. The present paper focuses on recent advances in both electronic and atomic level understanding of the metal-oxide interactions at temperatures below 1000 ?C, with special emphasis on model systems like ultrathin metal overlayers or metal nanoclusters supported on well-defined oxide surfaces. The important factors determining the metal-oxide interactions are provided. Guidelines are given in order to predict the interactions in such systems, and methods to desirably tune them are suggested. The review starts with a brief summary of the physics and chemistry of heterophase interface contacts. Basic concepts for quantifying the electronic interaction at metal/oxide interfaces are compared to well-developed contact theories and calculation methods. The chemical interaction between metals and oxides, i.e., the interface chemical reaction, is described in terms of its thermodynamics and kinetics. We review the different chemical driving forces and the influence of kinetics on interface reactions, proposing a strong interplay between the chemical interaction and electronic interaction, which is decisive for the final interfacial reactivity. In addition, a brief review of solid-gas interface reactions (oxidation of metal surfaces and etching of semiconductor surfaces) is given, in addition to a comparison of a similar mechanism dominating in solid-solid and solid-gas interface reactions. The main body of the paper reviews experimental and theoretical results from the literature concerning the interactions between metals and oxides (TiO 2, SrTiO 3, Al 2O 3, MgO, SiO 2, etc.). Chemical reactions, e.g., redox reactions, encapsulation reactions, and alloy formation reactions, are highlighted for metals in contact with mixed conducting oxides of TiO 2 and SrTiO 3. The dependence of the chemical interactions on the electronic structure of the contacting metal and oxide phases is demonstrated. This dependence originates from the interplay between interfacial space charge transfer and diffusion of ionic defects across interfaces. Interactions between metals and insulating oxides, such as Al 2O 3, MgO, and SiO 2, are strongly confined to the interfaces. Literature results are cited which discuss how the metal/oxide interactions vary with oxide surface properties (surface defects, surface termination, surface hydroxylation, etc.). However, on the surfaces of thin oxide films grown on conducting supports, the effect of the conducting substrates on metal-oxide interactions should be carefully considered. In the summary, we conclude how variations in the electronic structure of the metal/oxide junctions enable one to tune the interfacial reactivity and, furthermore, control the macroscopic properties of the interfaces. This includes strong metal-support interactions (SMSI), catalytic performance, electrical, and mechanical properties.

Fu, Qiang; Wagner, Thomas

2007-11-01

160

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

161

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

162

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

163

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

164

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

Microsoft Academic Search

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 [TcâClâ] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) â«, a

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

2011-01-01

165

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

Microsoft Academic Search

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 [TcCl] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) , a

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

2011-01-01

166

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

167

Oxidation of tunnel barrier metals in magnetic tunnel junctions  

SciTech Connect

The oxidation of an ultrathin metal layer (<1 nm) to form an oxide tunnel barrier is of critical importance for the fabrication of magnetic tunnel junctions (MTJs) with low product of resistance and area (RxA). Nonuniform and excessive or insufficient oxidation will occur by using conventional plasma, air, or O{sub 2} and noble gas mixtures as oxidation methods. An oxidation method was investigated to oxidize only an ultrathin layer of metal (such as Y) without oxidizing adjacent ferromagnetic thin film layers. We have now demonstrated that a gas mixture of H{sub 2}O/H{sub 2} with a fixed chemical potential of oxygen determined by the relative amounts of the two gases can oxidize Y and Ta thin layers while simultaneously keeping a Co ferromagnetic layer completely unoxidized. This universal method can be used to preferentially oxidize a host of other metals with high tendency to form oxides, such as Zr, Hf, Nb, rare earth metals, etc. and may allow us to access the feasible lower limit of barrier thickness in MTJs.

Yang, J. Joshua; Ladwig, Peter F.; Yang Ying; Ji Chengxiang; Chang, Y. Austin; Liu, Feng X.; Pant, Bharat B.; Schultz, Allan E. [Department of Materials Science and Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Recording Head Operations, Seagate Technology, Bloomington, Minnesota 55431 (United States)

2005-05-15

168

Atomic layer deposition of the aluminum oxide-yttrium oxide pseudo-binary system  

Microsoft Academic Search

The growth of thin films of selected phases from the pseudo-binary Al 2O3-Y2O3 material system was demonstrated using atomic layer deposition (ALD). Specifically ALD growth of Al2O 3, Y2O3, Ce2O3, Y2 Al4O12 (Yttrium Aluminum Monoclinic - YAM), and Y3Al5O12 (Yttrium Aluminum Garnet - YAG) was accomplished. All films were grown using the same precursors: AlCl 3 at 105°C and H2O,

Jason Conrad Rowland

2009-01-01

169

Complementary-MOS binary counter with parallel-set inputs  

NASA Technical Reports Server (NTRS)

Metal oxide semiconductor four-stage binary counter contains reset capability as well as four parallel-set inputs gated in by a logic signal. Parallel-set inputs permit setting the counter into any of sixteen possible states.

Keller, K. R.; Yung, A. K.

1970-01-01

170

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

171

Custom-designed nanomaterial libraries for testing metal oxide toxicity.  

PubMed

Advances in aerosol technology over the past 10 years have enabled the generation and design of ultrafine nanoscale materials for many applications. A key new method is flame spray pyrolysis (FSP), which produces particles by pyrolyzing a precursor solution in the gas phase. FSP is a highly versatile technique for fast, single-step, scalable synthesis of nanoscale materials. New innovations in particle synthesis using FSP technology, including variations in precursor chemistry, have enabled flexible, dry synthesis of loosely agglomerated, highly crystalline ultrafine powders (porosity ? 90%) of binary, ternary, and mixed-binary-and-ternary oxides. FSP can fulfill much of the increasing demand, especially in biological applications, for particles with specific material composition, high purity, and high crystallinity. In this Account, we describe a strategy for creating nanoparticle libraries (pure or Fedoped ZnO or TiO?) utilizing FSP and using these libraries to test hypotheses related to the particles' toxicity. Our innovation lies in the overall integration of the knowledge we have developed in the last 5 years in (1) synthesizing nanomaterials to address specific hypotheses, (2) demonstrating the electronic properties that cause the material toxicity, (3) understanding the reaction mechanisms causing the toxicity, and (4) extracting from in vitro testing and in vivo testing in terrestrial and marine organisms the essential properties of safe nanomaterials. On the basis of this acquired knowledge, we further describe how the dissolved metal ion from these materials (Zn²? in this Account) can effectively bind with different cell constituents, causing toxicity. We use Fe-S protein clusters as an example of the complex chemical reactions taking place after free metal ions migrate into the cells. As a second example, TiO? is an active material in the UV range that exhibits photocatalytic behavior. The induction of electron-hole (e?/h?) pairs followed by free radical production is a key mechanism for biological injury. We show that decreasing the bandgap energy increases the phototoxicity in the presence of near-visible light. We present in detail the mechanism of electron transfer in biotic and abiotic systems during light exposure. Through this example we show that FSP is a versatile technique for efficiently designing a homologous library, meaning a library based on a parent oxide doped with different amounts of dopant, and investigating the properties of the resulting compounds. Finally, we describe the future outlook and state-of-the-art of an innovative two-flame system. A double-flame reactor enables independent control over each flame, the nozzle distances and the flame angles for efficient mixing of the particle streams. In addition, it allows for different flame compositions, flame sizes, and multicomponent mixing (a grain-grain heterojunction) during the reaction process. PMID:23194152

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

2013-03-19

172

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

173

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

174

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

175

A rapid microwave-assisted solvothermal approach to lower-valent transition metal oxides.  

PubMed

A green, rapid microwave-assisted solvothermal process using tetraethylene glycol (TEG) as a reducing agent has been explored as a soft-chemistry route for the preparation of various lower-valent transition metal oxides. To demonstrate the feasibility of the approach, lower-valent binary oxides such as V4O9, Mn3O4 or MnO, CoO, and Cu2O have been obtained within a short reaction time of 30 min by reducing, respectively, V2O5, MnO2, Co3O4, and CuO with TEG at <300 °C. Moreover, the approach has been used to extract oxygen from ternary oxides such as LaFeO3, SrMnO3, LaCoO3, LaNiO3, and La4Ni3O10. The oxidation state of the transition metal ions and the oxygen content in these ternary oxides could be tuned by precisely controlling the reaction temperatures from 160 to 300 °C. The products have been characterized by X-ray powder diffraction and iodometric titration. The versatility of this novel technique is demonstrated by the facile synthesis of V4O9, which has only been produced recently in single-phase form. PMID:24191765

Moorhead-Rosenberg, Zachary; Harrison, Katharine L; Turner, Travis; Manthiram, Arumugam

2013-11-18

176

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

177

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

178

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

PubMed

Large-scale electrolysis of water for hydrogen generation requires better catalysts to lower the kinetic barriers associated with the oxygen evolution reaction (OER). Although most OER catalysts are based on crystalline mixed-metal oxides, high activities can also be achieved with amorphous phases. Methods for producing amorphous materials, however, are not typically amenable to mixed-metal compositions. We demonstrate that a low-temperature process, photochemical metal-organic deposition, can produce amorphous (mixed) metal oxide films for OER catalysis. The films contain a homogeneous distribution of metals with compositions that can be accurately controlled. The catalytic properties of amorphous iron oxide prepared with this technique are superior to those of hematite, whereas the catalytic properties of a-Fe(100-y-z)Co(y)Ni(z)O(x) are comparable to those of noble metal oxide catalysts currently used in commercial electrolyzers. PMID:23539180

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

2013-04-01

179

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

180

Synthesis and applications of hierarchically porous metal and metal oxide monolithic materials  

NASA Astrophysics Data System (ADS)

A nanocasting method for synthesizing a broad range of hierarchically porous, high surface area metal and metal oxide monolithic materials was developed. The importance of a well-connected hard template was established based on conductivity measurements. A hierarchically porous, silica monolith prepared with 7% ocadecyltrimethylammonium bromide was found to be the optimum silica template. Several different factors were found to regulate how well the silica template was replicated. When the connectivity of the silica template, contents of the metal salt solution, impregnation method, temperature, atmosphere, and template removal are all controlled, a good replica of the original silica monolith can be attained in different metals or metal oxides. These metal and metal oxide monoliths were used in catalysis and liquid chromatography.

Sayler, Franchessa Maddox

181

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

182

Nano and microsized metal oxide thin film gas sensors  

Microsoft Academic Search

Functional micro- and nanosized metal oxide thin film structures are very promising candidate for future gas-sensors. Their\\u000a reduced size offers an increased surface to volume ratio thus improving sensitivity and sensor performance. Whilst most experimental\\u000a nanostructures are produced using a bottom-up approach, a top-down sputtering technique for structuring nano-sized gas sensitive\\u000a metal oxide areas is presented in this letter. Oxidised

Stefan Palzer; Emmanuel Moretton; Francisco Hernandez Ramirez; Albert Romano-Rodriguez; Jürgen Wöllenstein

2008-01-01

183

Plutonium metal and oxide container weld development and qualification  

SciTech Connect

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

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

1996-01-01

184

Mesoporous sandwiches: towards mesoporous multilayer films of crystalline metal oxides.  

PubMed

Alternating multilayers of ordered mesoporous films of different metal oxides were prepared with the EISA (evaporation-induced self-assembly) method, using block copolymer templates. Selecting certain metal oxides, as exemplified with TiO2 and WO3 in this work, a high mesoscopic order could be achieved and preserved during crystallization. In addition to standard characterizations, the electrochromism of the multilayer film was studied, proving good accessibility of the single layers. PMID:19421475

Ostermann, Rainer; Sallard, Sébastien; Smarsly, Bernd M

2009-05-21

185

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

PubMed

Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs' preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance. PMID:22018872

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

2012-04-15

186

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

187

Oxidation thermodynamics of metal substrates during the deposition of buffer layer oxides  

NASA Astrophysics Data System (ADS)

The oxidation state of a metal surface during the initial stages of deposition of an epitaxial oxide buffer layer is discussed from a thermodynamic viewpoint. The basic problem is one of minimizing oxidation of the surface of the metal while ensuring that the buffer layer oxide is able to form in the desired phase. Particular attention is paid to the deposition of CeO 2, SrTiO 3 and Y 2O 3-ZrO 2 (YSZ) onto nickel. Such materials are candidates for use in the production of high- Tc coated conductors. Calculation of the Gibbs free energy changes for the oxidation reactions, under various regimes of vacuum and gas supply, suggest conditions which are reducing for the metal oxide but under which the buffer layer oxide remains stable.

Jackson, T. J.; Glowacki, B. A.; Evetts, J. E.

188

Oxidation thermodynamics of metal substrates during the deposition of buffer layer oxides  

NASA Astrophysics Data System (ADS)

The oxidation state of a metal surface during the initial stages of deposition of an epitaxial oxide buffer layer is discussed from a thermodynamic viewpoint. The basic problem is one of minimizing oxidation of the surface of the metal while ensuring that the buffer layer oxide is able to form in the desired phase. Particular attention is paid to the deposition of CeO2, SrTiO3 and Y2O3-ZrO2 (YSZ) onto nickel. Such materials are candidates for use in the production of high-Tc coated conductors. Calculation of the Gibbs free energy changes for the oxidation reactions, under various regimes of vacuum and gas supply, suggest conditions which are reducing for the metal oxide but under which the buffer layer oxide remains stable.

Evetts, J. E.; Glowacki, B. A.; Jackson, T. J.

1998-02-01

189

Chemistry of Sulfur Oxides on Transition Metals. II. Thermodynamics of Sulfur Oxides on Platinum(111)  

E-print Network

Chemistry of Sulfur Oxides on Transition Metals. II. Thermodynamics of Sulfur Oxides on Platinum at the highest coverages and sulfur oxidation states. Calculated vibrational spectra are used to assign observed the preferred SOx species on Pt(111), consistent with observation. I. Introduction The chemistry of sulfur

Lin, Xi

190

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

SciTech Connect

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

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

1993-10-01

191

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

192

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.

193

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

194

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

E-print Network

The fraction of binary systems in various stellar populations of the Galaxy and the distribution of their orbital parameters are important but not well-determined factors in studies of star formation, stellar evolution, and Galactic chemical evolution. While observational studies have been carried out for a large sample of nearby stars, including some metal-poor, Population II stars, almost no constraints on the binary nature for extremely metal-poor (EMP; [Fe/H] < -3.0) stars have yet been obtained. Here we investigate the fraction of double-lined spectroscopic binaries and carbon-enhanced metal-poor (CEMP) stars, many of which could have formed as pairs of low-mass and intermediate-mass stars, to estimate the lower limit of the fraction of binary systems having short periods. The estimate is based on a sample of very metal-poor stars selected from the Sloan Digital Sky Survey, and observed at high spectral resolution in a previous study by Aoki et al. That survey reported three double-lined spectroscopic...

Aoki, Wako; Beers, Timothy C; Honda, Satoshi

2014-01-01

195

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 on the growth mode ofmetal atoms and the oxidation ofthe silicon surface atoms. These phenomena are discussed long range order or not has a great importance. There are at least two cases where basic properties

Paris-Sud XI, Université de

196

Interaction of Metal Oxides with Biomolecules: Implcation in Astrobiology  

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

Kamaluddin, K.; Iqubal, Asif

197

Copper Alloys From Metal Oxide Precursors for High Conductivity Applications  

Microsoft Academic Search

Extrusion of oxide powders allows fabrication of thin-walled metal articles to produce controlled-geometry, low-density copper alloy architectures. Shapes formed with copper oxide powders mixed with alloying oxides are reduced and sintered to produce high relative densities in the thin walls. This technology has produced square-cell honeycomb extrusions, which are being characterized for heat sink applications. This effort is to determine

Benjamin C. Church; T. H. Sanders Jr.; Joe K. Cochran

2004-01-01

198

Synthesis, characterization and properties of nano-sized transition metal oxides  

Microsoft Academic Search

Chapter 1. A General introduction to the emerging field of nanomaterials is presented highlighting the category of transition metal oxides. The wide variety of structures, properties, and phenomena of transition metal oxides are stressed. Nano-sized transition metal oxides are presented as systems for fundamental and application research. Examples of individual transition metal oxides are provided. Important developments in the synthesis

Ming Yin

2005-01-01

199

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

200

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

201

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

202

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

203

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

204

Emerging Applications of Liquid Metals Featuring Surface Oxides  

PubMed Central

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

2014-01-01

205

Solvent free synthesis of chalcone and flavanone over zinc oxide supported metal oxide catalysts  

Microsoft Academic Search

Liquid phase Claisen–Schmidt condensation between 2?-hydroxyacetophenone and benzaldehyde to form 2?-hydroxychalcone, followed by intramolecular cyclisation to form flavanone was carried out over zinc oxide supported metal oxide catalysts under solvent free condition. The reaction was carried out over ZnO supported MgO, BaO, K2O and Na2O catalysts with 0.2g of each catalyst at 140°C for 3h. Magnesium oxide impregnated zinc oxide

S. Saravanamurugan; M. Palanichamy; Banumathi Arabindoo; V. Murugesan

2005-01-01

206

Catalytic oxidation of dye wastewater by metal oxide catalyst and granular activated carbon  

Microsoft Academic Search

Bench experiments were conducted to investigate the catalytic oxidation of dye wastewater by metal oxides. The catalytic oxidation was carried out in an air fluidized-bed reactor and was assisted by V2O5 as catalyst, granular activated carbon (GAC), and hydrogen peroxide. The experimental results indicated that, in the present oxidation process, both chemical and physical actions took place which are distinctly

Sheng H. Lin; Cheng L. Lai

1999-01-01

207

REDUCTION OF NITRIC OXIDE WITH METAL SULFIDES  

EPA Science Inventory

The report gives results of research to determine the technical feasibility of using metal sulfide for the chemical reduction of NOx to N2. Nineteen different metal sulfides were investigated, using a test gas of pure NO. Although most sulfides resulted in some NO reduction, BaS,...

208

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

209

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

210

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

211

Metal-oxide Nanowires for Toxic Gas Detection  

SciTech Connect

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

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

2007-01-02

212

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

213

Absolute dimensions of detached eclipsing binaries. I. The metallic-lined system WW Aurigae  

E-print Network

WW Aurigae is a detached eclipsing binary composed of two metallic-lined A-type stars orbiting each other every 2.5 days. We have determined the masses and radii of both components to accuracies of 0.4 and 0.6 percent, respectively. From a cross-correlation analysis of high-resolution spectra we find masses of 1.964 +/- 0.007 Msun for the primary star and 1.814 +/- 0.007 Msun for the secondary star. From an analysis of photoelectric uvby and UBV light curves we find the radii of the stars to be 1.927 +/- 0.011 Rsun and 1.841 +/- 0.011 Rsun, where the uncertainties have been calculated using a Monte Carlo algorithm. Fundamental effective temperatures of the two stars have been derived, using the Hipparcos parallax of WW Aur and published ultraviolet, optical and infrared fluxes, and are 7960 +/- 420 and 7670 +/- 410 K. The masses, radii and effective temperatures of WW Aur are only matched by theoretical evolutionary models for a fractional initial metal abundance, Z, of approximately 0.06 and an age of roughl...

Southworth, J; Maxted, P F L; Claret, A; Etzel, P B; Southworth, John

2005-01-01

214

Reductive mobilization of oxide-bound metals  

SciTech Connect

This project is concerned with the mobilization of MnO{sub 2}- and FeOOH-bound toxic metals in subsurface environments arising from an influx of natural organic matter or organic-containing wastes. Our work to date emphasizes the importance of characterizing the reductant, complexant, and adsorptive characteristics of constituent organic chemicals. Organic chemicals may interact with pollutant metals directly, or may bring about changes in speciation and solubility indirectly by acting upon MnO{sub 2} and FeOOH host phases. The primary application of this work is the understanding of metal sorption and release processes within subsurface environments undergoing changes in redox status.

Stone, A.T.

1992-01-01

215

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

216

Oxidation of magnesium in the systems NaClO 4 -Mg-Metal oxide (peroxide)  

Microsoft Academic Search

Oxidation of magnesium in mixtures NaClO4 + Mg + metal oxide or peroxide has been investigated using differential thermal analysis (DTA). In the systems with peroxides\\u000a Na2O2, Li2O2, BaO2, CaO2 or ZnO, magnesium oxidizes simultaneously with decomposition of NaClO4 in the region 380–520C, which is 100–200C below the oxidation temperature of magnesium in air. In the ternary systems with\\u000a transition-metal

V. D. Sasnovskaya; A. P. Razumova

2006-01-01

217

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

218

Chemistry of precious metal oxides relevant to heterogeneous catalysis.  

PubMed

The platinum group metals (PGMs) are widely employed as catalysts, especially for the mitigation of automotive exhaust pollutants. The low natural abundance of PGMs and increasing demand from the expanding automotive sector necessitates strategies to improve the efficiency of PGM use. Conventional catalysts typically consist of PGM nanoparticles dispersed on high surface area oxide supports. However, high PGM loadings must be used to counter sintering, ablation, and deactivation of the catalyst such that sufficient activity is maintained over the operating lifetime. An appealing strategy for reducing metal loading is the substitution of PGM ions into oxide hosts: the use of single atoms (ions) as catalytic active sites represents a highly atom-efficient alternative to the use of nanoparticles. This review addresses the crystal chemistry and reactivity of oxide compounds of precious metals that are, or could be relevant to developing an understanding of the role of precious metal ions in heterogeneous catalysis. We review the chemical conditions that facilitate stabilization of the notoriously oxophobic precious metals in oxide environments, and survey complex oxide hosts that have proven to be amenable to reversible redox cycling of PGMs. PMID:24008693

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

2013-10-01

219

Metal dyshomeostasis and oxidative stress in Alzheimer's disease.  

PubMed

Alzheimer's disease is the leading cause of dementia in the elderly and is defined by two pathological hallmarks; the accumulation of aggregated amyloid beta and excessively phosphorylated Tau proteins. The etiology of Alzheimer's disease progression is still debated, however, increased oxidative stress is an early and sustained event that underlies much of the neurotoxicity and consequent neuronal loss. Amyloid beta is a metal binding protein and copper, zinc and iron promote amyloid beta oligomer formation. Additionally, copper and iron are redox active and can generate reactive oxygen species via Fenton (and Fenton-like chemistry) and the Haber-Weiss reaction. Copper, zinc and iron are naturally abundant in the brain but Alzheimer's disease brain contains elevated concentrations of these metals in areas of amyloid plaque pathology. Amyloid beta can become pro-oxidant and when complexed to copper or iron it can generate hydrogen peroxide. Accumulating evidence suggests that copper, zinc, and iron homeostasis may become perturbed in Alzheimer's disease and could underlie an increased oxidative stress burden. In this review we discuss oxidative/nitrosative stress in Alzheimer's disease with a focus on the role that metals play in this process. Recent studies have started to elucidate molecular links with oxidative/nitrosative stress and Alzheimer's disease. Finally, we discuss metal binding compounds that are designed to cross the blood brain barrier and restore metal homeostasis as potential Alzheimer's disease therapeutics. PMID:22982299

Greenough, Mark A; Camakaris, James; Bush, Ashley I

2013-04-01

220

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

NASA Technical Reports Server (NTRS)

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

Herz, Richard K.

1990-01-01

221

New approaches to the preparation of metal or metal oxide particles on the surface of porous materials using supercritical water  

Microsoft Academic Search

Supercritical water was used as preparation media for particle deposited materials. Manganese oxide, silver, and lead oxide were prepared on alumina supports from metal acetate solutions in supercritical region. The resulting samples were characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). It is shown that metal or metal oxide particles could be crystallized onto

Junichi Otsu; Yoshito Oshima

2005-01-01

222

? 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

223

Quantitative EELS analysis of zirconium alloy metal/oxide interfaces.  

PubMed

Zirconium alloys have been long used for fuel cladding and other structural components in water-cooled nuclear reactors, but waterside corrosion is a primary limitation on both high fuel burn-up and extended fuel cycle operation. Understanding the processes that occur at the metal/oxide interface is crucial for a full mechanistic description of the oxidation process. In this paper we show that reliable quantification of the oxygen content at the metal/oxide interface can be obtained by Electron Energy Loss Spectrometry (EELS) if enough care is taken over both the preparation of Transmission Electron Microscopy (TEM) samples and the methodology for quantification of the EELS data. We have reviewed the accuracy of theoretically calculated inelastic partial scattering cross-sections and effective inelastic mean-free-paths for oxygen and zirconium in oxidized Zr-alloy samples. After careful recalibration against a ZrO? powder standard, systematic differences in the local oxygen profile across the interface in different zirconium alloys were found. The presence of a sub-stoichiometric oxide layer (a suboxide) was detected under conditions of slow oxide growth but not where growth was more rapid. This difference could arise from the different corrosion resistances of the alloys or, more likely, as a result of the transition in oxidation behaviour, which refers to a sharp increase in the oxidation rate when the oxide is a few microns thick. PMID:21185456

Ni, Na; Lozano-Perez, Sergio; Sykes, John; Grovenor, Chris

2011-01-01

224

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

225

Nanofilamentary resistive switching in binary oxide system; a review on the present status and outlook.  

PubMed

This review article summarized the recent understanding of resistance switching (RS) behavior in several binary oxide thin film systems. Among the various RS materials and mechanisms, TiO(2) and NiO thin films in unipolar thermo-chemical switching mode are primarily dealt with. To facilitate the discussions, the RS was divided into three parts; electroforming, set and reset steps. After short discussions on the electrochemistry of 'electrolytic' oxide materials, the general and peculiar aspects of these RS systems and mechanism are elaborated. Although the RS behaviors and characteristics of these materials are primarily dependent on the repeated formation and rupture of the conducting filaments (CFs) at the nanoscale at a localized position, this mechanism appears to offer a basis for the understanding of other RS mechanisms which were originally considered to be irrelevant to the localized events. The electroforming and set switching phenomena were understood as the process of CF formation and rejuvenation, respectively, which are mainly driven by the thermally assisted electromigration and percolation (or even local phase transition) of defects, while the reset process was understood as the process of CF rupture where the thermal energy plays a more crucial role. This review also contains several remarks on the outlook of these resistance change devices as a semiconductor memory. PMID:21572206

Kim, Kyung Min; Jeong, Doo Seok; Hwang, Cheol Seong

2011-06-24

226

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

227

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

PubMed

Knowing the thermodynamic stability of transition metal oxide nanoparticles is important for understanding and controlling their role in a variety of industrial and environmental systems. Using calorimetric data on surface energies for cobalt, iron, manganese, and nickel oxide systems, we show that surface energy strongly influences their redox equilibria and phase stability. Spinels (M(3)O(4)) commonly have lower surface energies than metals (M), rocksalt oxides (MO), and trivalent oxides (M(2)O(3)) of the same metal; thus, the contraction of the stability field of the divalent oxide and expansion of the spinel field appear to be general phenomena. Using tabulated thermodynamic data for bulk phases to calculate redox phase equilibria at the nanoscale can lead to errors of several orders of magnitude in oxygen fugacity and of 100 to 200 kelvin in temperature. PMID:20929770

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

2010-10-01

228

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

229

Enhanced arsenic removal using mixed metal oxide impregnated chitosan beads.  

PubMed

Mixed metal oxide impregnated chitosan beads (MICB) containing nanocrystalline Al?O? and nanocrystalline TiO? were successfully developed. This adsorbent exploits the high capacity of Al?O? for arsenate and the photocatalytic activity of TiO? to oxidize arsenite to arsenate, resulting in a removal capacity higher than that of either metal oxide alone. The composition of the beads was optimized for maximum arsenite removal in the presence of UV light. The mechanism of removal was investigated and a mode of action was proposed wherein TiO? oxidizes arsenite to arsenate which is then removed from solution by Al?O?. Pseudo-second order kinetics were used to validate the proposed mechanism. MICB is a more efficient and effective adsorbent for arsenic than TiO?-impregnated chitosan beads (TICB), previously reported on, yet maintains a desirable life cycle, free of complex synthesis processes, toxic materials, and energy inputs. PMID:22743162

Yamani, Jamila S; Miller, Sarah M; Spaulding, Matthew L; Zimmerman, Julie B

2012-09-15

230

Pb(II) distributions at biofilm-metal oxide interfaces  

PubMed Central

The distribution of aqueous Pb(II) sorbed at the interface between Burkholderia cepacia biofilms and hematite (?-Fe2O3) or corundum (?-Al2O3) surfaces has been probed by using an application of the long-period x-ray standing wave technique. Attached bacteria and adsorbed organic matter may interfere with sorption processes on metal oxide surfaces by changing the characteristics of the electrical double layer at the solid–solution interface, blocking surface sites, or providing a variety of new sites for metal binding. In this work, Pb L? fluorescence yield profiles for samples equilibrated with 10?7 to 10?3.8 M Pb(II) were measured and modeled to determine quantitatively the partitioning of Pb(II) at the biofilm–metal oxide interface. Our data show that the reactive sites on the metal oxide surfaces were not passivated by the formation of a monolayer biofilm. Instead, high-energy surface sites on the metal oxides form the dominant sink for Pb(II) at submicromolar concentrations, following the trend ?-Fe2O3 (0001) > ?-Al2O3 (11?02) > ?-Al2O3 (0001), despite the greater site density within the overlying biofilms. At [Pb] > 10?6 M, significant Pb uptake by the biofilms was observed. PMID:11572932

Templeton, Alexis S.; Trainor, Thomas P.; Traina, Samuel J.; Spormann, Alfred M.; Brown, Gordon E.

2001-01-01

231

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

232

Transition metal oxides for hot gas desulphurisation  

Microsoft Academic Search

Thermodynamic equilibrium simulations were made to determine suitable materials for intensive desulphurisation of fuel gases from an IGCC. Zinc-based materials are the most promising for high temperature intensive desulphurisation, but cause evaporation and regenerability problems. To overcome these problems, a new material was synthesised, containing zinc oxide supported on a titanium dioxide support. The material is able to reduce H2S

W. F. Elseviers; H. Verelst

1999-01-01

233

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

234

Electronic structure of double-perovskite transition-metal oxides  

Microsoft Academic Search

Electronic structure has been investigated by reflectivity measurement for ordered-perovskite transition-metal oxides, Sr2MMoO6 (M=Cr, Mn, Fe, and Co). The ground states of the Co and Mn compounds are paramagnetic insulators, making a sharp contrast with the ferrimagnetic metallic Sr2FeMoO6. For all the compounds, we have observed intense optical transition at ~2 eV, which has been ascribed to the charge-transfer excitation

Y. Moritomo; Sh. Xu; A. Machida; T. Akimoto; E. Nishibori; M. Takata; M. Sakata

2000-01-01

235

Oxidation of CO and hydrocarbons over noble metal catalysts  

Microsoft Academic Search

The oxidation of CO, CâHâ, 1-hexene, and toluene under excess Oâ has been studied over precious metal (PM) catalysts, Pt, Pd, and Rh, in the form of unsupported wires or supported on ..gamma..-AlâOâ or CeOâ\\/AlâOâ. The kinetics were affected by the state of the metal dispersion, the pretreatment temperature, the reaction conditions, and the presence of CeOâ. The existence of

Y YAO; Y. F. Y

1984-01-01

236

Oxidation kinetics of hydride-bearing uranium metal corrosion products  

Microsoft Academic Search

The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar–4%O2, Ar–9%O2, and Ar–20%O2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to

Terry C Totemeier; Robert G Pahl; Steven M Frank

1999-01-01

237

Fabrication and applications of metal-oxide nano-tubes  

Microsoft Academic Search

Metal-oxide nanotubes can be used for a wide range of applications, such as selective chemical and biological sensors, dye-sensitized\\u000a solar cells and photo-catalysts. The fabrication methods can be categorized into a directed method using nanotemplates (sol-gel\\u000a method and atomic layer deposition) and a non-directed method (anodization). This review article describes the recent progress\\u000a made in the field of oxide nanotube

Mingun Lee; Taewook Kim; Changdeuck Bae; Hyunjung Shin; Jiyoung Kim

2010-01-01

238

Study on Nano Complementary Metal Oxide Semiconductor Gate Leakage Current  

Microsoft Academic Search

This work examines different components of the leakage current in scaled N and P-metal oxide semiconductor field-effect transistor (MOSFET) with ultra thin gate oxide. Experimental results show that the gate tunneling leakage current through the source\\/drain extension region (also named edge direct tunneling, EDT) is the largest component, which dominates the maximum off-state power consumption of a nano-scaled transistor. To

Heng-Sheng Huang; Chia-Hung Huang; Yen-Ching Wu; Yao-Kai Hsu; Jeng-Kang Chen; Gary Hong

2003-01-01

239

Oxidation of methane over supported precious metal catalysts  

Microsoft Academic Search

Studies of the kinetics of methane oxidation over palladium (Pd) and platinum (Pt) catalysts supported on a number of metal oxides were made using a pulse-flow microreactor technique. The reaction was investigated at temperatures in the range 500 to 800 K using reactant mixtures with CHâ:Oâ ratios varying from 1:10 to 10:1. The supports themselves, with the exception of tin(IV)

C. F. Cullis; B. M. Willatt

1983-01-01

240

DEVELOPMENTAL PHYTOTOXICITY OF METAL OXIDE NANOPARTICLES TO ARABIDOPSIS THALIANA  

E-print Network

during long-term illumi- nation [13,14]. Similarly, nSiO2 enhanced the growth of Chang- bai larch (Larix on the effects of four metal oxide nanoparticles, aluminum oxide (nAl2O3), silicon dioxide (nSiO2), magnetite (n://cohesion.rice.edu/centersandinst/ICON/ emplibrary/Nanomaterial%20Volumes%20and%20Applications %20%20Holman,%20Lux%20Research.pdf). Increasing num

Alvarez, Pedro J.

241

Synthesis and Characterization of Hybrid Metal-Metal and Metal-Oxide Nanostructure Decorated Single Walled Carbon Nanotube Devices  

E-print Network

nano-gas sensors in a facile and cost effective route, a process that can be extended to other metal oxidenano-gas sensors in a facile and cost effective route, a process that can be extended to other metal oxide

Hernandez, Sandra Catalina

2010-01-01

242

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

243

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

SciTech Connect

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

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 (Rutgers); (SBU); (Cambridge); (SUNY-Binghamton); (BNL)

2012-03-15

244

Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst  

SciTech Connect

Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu{sub 2}O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu{sub 2}O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/mol < Cu{sub 2}O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N{sub 2} and CO{sub 2}. At the end of each reaction, the catalyst was found to be Cu{sub 2}O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.

Jernigan, G.G. [California Univ., Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Materials and Chemical Sciences Div.

1994-10-01

245

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

246

Short-range order in theoretical models of binary metallic glass alloys  

NASA Astrophysics Data System (ADS)

Computer-generated models of metallic glass alloys are explored to exhibit the short-range order of their atomic structure. Binary alloys Pd-Si, Fe-P, and Fe-B are studied as a function of composition. Several approaches are used. The distribution of near-neighbor types is calculated in detail, from which it is argued that a specific coordination is preferred and satisfied by a local unit structure around each metalloid. The metalloids are removed from the structure and the size distribution and shapes of the Bernal holes remaining are calculated; the results corroborate the conclusion drawn above. The local geometry is explored by computer graphic methods and a surprising degree of regularity is discovered. Two local geometries dominate the surroundings of metalloid species: the octahedron and the trigonal prism. The relative occurrence of each is seen to vary with composition but the two methods used differ as to the degree of variation. Finally, the alloy density is calculated from a Voronoi polyhedral analysis for the first time. Density and its variation with composition are seen to be adequately simulated by the models under study.

Boudreaux, D. S.; Frost, H. J.

1981-02-01

247

Dextran templating for the synthesis of metallic and metal oxide sponges  

NASA Astrophysics Data System (ADS)

Silver or gold-containing porous frameworks have been used extensively in catalysis, electrochemistry, heat dissipation and biofiltration. These materials are often prepared by thermal reduction of metal-ion-impregnated porous insoluble supports (such as alumina and pumice), and have surface areas of about 1 m2 g-1, which is typically higher than that obtained for pure metal powders or foils prepared electrolytically or by infiltration and thermal decomposition of insoluble cellulose supports. Starch gels have been used in association with zeolite nanoparticles to produce porous inorganic materials with structural hierarchy, but the use of soft sacrificial templates in the synthesis of metallic sponges has not been investigated. Here we demonstrate that self-supporting macroporous frameworks of silver, gold and copper oxide, as well as composites of silver/copper oxide or silver/titania can be routinely prepared by heating metal-salt-containing pastes of the polysaccharide, dextran, to temperatures between 500 and 900 °C. Magnetic sponges were similarly prepared by replacing the metal salt precursor with preformed iron oxide (magnetite) nanoparticles. The use of dextran as a sacrificial template for the fabrication of metallic and metal oxide sponges should have significant benefits over existing technologies because the method is facile, inexpensive, environmentally benign, and amenable to scale-up and processing.

Walsh, Dominic; Arcelli, Laura; Ikoma, Toshiyuki; Tanaka, Junzo; Mann, Stephen

2003-06-01

248

Molecular dynamic simulation of binary ZrxCu100-x metallic glass thin film growth Lu Xie, Pascal Brault(*), Anne-Lise Thomann, Larbi Bedra  

E-print Network

1 Molecular dynamic simulation of binary ZrxCu100-x metallic glass thin film growth Lu Xie, Pascal to study ZrxCu100-x (3 x 95) metallic glass films deposited on a silicon (100) substrate. Input data were, metallic glass, alloy, sputtering deposition hal-00797237,version1-6Mar2013 Author manuscript, published

Paris-Sud XI, Université de

249

Temperature dependence of electric conductivity of molten binary mixtures of alkali and rare-earth metals chlorides  

Microsoft Academic Search

The temperature dependences of the specific and molar electric conductances of CeCl3-MCl and LnCl3-KCl (M=Li, Na, K, and Cs; Ln=Er and Yb) molten binary mixtures of various compositions were studied. The size of the cations\\u000a of alkali and rare-earth metals was demonstrated to affect the intensity of the interactions of the components of the systems.\\u000a Deviations of the molar conductance

A. V. Kovalevskii; V. I. Shishalov

2006-01-01

250

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

251

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

252

Oxidation kinetics of reaction products formed in uranium metal corrosion.  

SciTech Connect

The oxidation behavior of uranium metal ZPPR fuel corrosion products in environments of Ar-4%O{sub 2} and Ar-20%O{sub 2} were studied using thermo-gravimetric analysis (TGA). These tests were performed to extend earlier work in this area specifically, to assess plate-to-plate variations in corrosion product properties and the effect of oxygen concentration on oxidation behavior. The corrosion products from two relatively severely corroded plates were similar, while the products from a relatively intact plate were not reactive. Oxygen concentration strongly affected the burning rate of reactive products, but had little effect on low-temperature oxidation rates.

Totemeier, T. C.

1998-04-22

253

Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof  

DOEpatents

Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

Perkins, John (Boulder, CO); Van Hest, Marinus Franciscus Antonius Maria (Lakewood, CO); Ginley, David (Evergreen, CO); Taylor, Matthew (Golden, CO); Neuman, George A. (Holland, MI); Luten, Henry A. (Holland, MI); Forgette, Jeffrey A. (Hudsonville, MI); Anderson, John S. (Holland, MI)

2010-07-13

254

Oxidation behavior of chromium and a chromium-yttrium binary alloy  

SciTech Connect

The effect of an addition of 0.04 wt % Y on the oxidation behavior of pure Cr at 900 and 1025/sup 0/C has been investigated. The microstructures and chemical compositions of the Cr/sub 2/O/sub 3/ scales formed were studied both parallel and transverse to the oxide/metal interface by SEM, TEM, and STEM. Oxidation kinetics were measured by TGA and the direction of scale growth determined using inert markers. At 900/sup 0/C, the rate of scale growth, the direction of scale growth and the scale microstructure were unchanged by the addition of 0.04 wt % Y to Cr At 1025/sup 0/C, the direction of scale growth and scale microstructure were unchanged by the addition of 0.04 wt % Y, but the rate of oxidation was reduced by a factor of six. A model for the development of the microstructures of chromia scales formed on Cr and Cr-0.04 wt % Y is presented, and the effect of yttrium on the rate of growth of chromia at 900 and 1025/sup 0/C is discussed.

Cotell, C.M.; Przybylski, K.; Yurek, G.J.

1986-01-01

255

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

256

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

257

Activation of carbon dioxide on metal and metal oxide surfaces  

SciTech Connect

The environmental concern about the impact of CO{sub 2} has grown recently due to its rapidly increasing concentration. Deforestation strongly affects the natural reduction of CO{sub 2} by water into carbohydrates by photosynthesis. Industrial utilization of CO{sub 2} by heterogeneous catalytic reactions can be one of the effective ways to cut the CO{sub 2} level. The first step in catalytic reaction of CO{sub 2} is the adsorption. The objective of this study is to investigate the adsorption of CO{sub 2} on the Rh/Al{sub 2}O{sub 3} surfaces. Rh is selected for this study because of its unique activity to catalyze a number of CO{sub 2} related reactions. In situ infrared results show that CO{sub 2} adsorbed on the alumina oxide support as bidentate carbonate and non-coordinated carbon which are the dominant species during the CO{sub 2} adsorption.

Tan, C.D.; Chuang, S.S.C. [Univ. of Akron, OH (United States). Dept. of Chemical Engineering

1995-12-31

258

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

259

Analysis on liquid metal corrosion–oxidation interactions  

Microsoft Academic Search

The interaction between growing surface oxides and flowing liquid metals is of importance in many high temperature applications such as coolant systems using liquid lead or lead bismuth eutectic (LBE) in advanced nuclear energy systems. The impact of flow can manifest through particle erosion, mass transfer corrosion, stress scrape, etc. In the present study, we consider the continuous flow-induced corrosion

Jinsuo Zhang; Ning Li

2007-01-01

260

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

261

Nano-confined water on surfaces of metal oxide nanoparticles  

Microsoft Academic Search

Nanolayers of water interacting with metal oxide surfaces demonstrate physical properties that are significantly different from those of bulk water and ice. Our recent water adsorption experiments suggest that the entropy of surface water is lower than those of bulk water and ice implying restricted motion of the water on the surface. We have studied dynamics of water on nanoparticles

Andrey Levchenko; Juliana Boerio-Goates; Brian Woodfield; Alexander Kolesnikov; Nancy Ross; David Wesolowski; David Cole; Alexandra Navrotsky

2008-01-01

262

Strain effects in low-dimensional transition metal oxides  

Microsoft Academic Search

Transition metal oxides offer a wide spectrum of properties which provide the foundation for a broad range of potential applications. Many of these properties originate from intrinsic coupling between lattice deformation and nanoscale electronic and magnetic ordering. Lattice strain thus has a profound influence on the electrical, optical, and magnetic properties of these materials. Recent advances in materials processing have

Jinbo Cao; Junqiao Wu

2011-01-01

263

Nano-Enabled Metal Oxide Varistors for Surge Protection  

Microsoft Academic Search

Commercial metal oxide varistor (MOV) devices provide a combination of high voltage, peak current, pulse energy absorption, and fast response speed. The non-uniformity and defects, however, may lead to relatively low voltage and energy dissipation, high leakage, low reliability and mechanical cracking. GE global research has been studying NanoMOV technology, and has been developing new formulations and processes. New compositions

Daniel Tan; Karim Younsi; Yingneng Zhou; Yang Cao; Patricia Irwin

2008-01-01

264

Opportunities in nano-structured metal oxides based biosensors  

Microsoft Academic Search

Nanomaterials are presently at the critical stage of the next technological revolution in solid-state electronics and are emerging as new structural materials, to serve as systems for controlled drug delivery, biomolecular electronics and are considered to have considerable impact in practically all domains of science. Among the various types of nanomaterials that have been developed, nanostructured metal oxides (NSMOs) have

B D Malhotra; Maumita Das; Pratima R Solanki

2012-01-01

265

Properties of Silicon and Metal Oxide Electrowetting Systems  

Microsoft Academic Search

This paper is a review of our recent work on electrowetting properties of devices based on silicon (Si) and metal oxide (MO) electrodes. In particular, the electrowetting-on-dielectric (EWOD) properties of three- dimensional (3D) structured Si and MO electrodes are investigated and compared with those of planar ones. It is shown that the EWOD properties of these materials can be advantageously

Evie L. Papadopoulou; Vassilia Zorba; Emmanuel Stratakis; Costas Fotakis

2012-01-01

266

Growth of metal oxide nanoparticles using pulsed laser ablation technique  

Microsoft Academic Search

Nano particles exhibit physical and chemical properties distinctively different from that of bulk due to high number of surface atoms, surface energy and surface area to volume ratio. Laser is a unique source of radiation and has been applied in the synthesis of nano structured metal oxides. The pulsed laser ablation (PLA) technique in liquid medium has been proven an

M. A. Gondal; Q. A. Drmosh; Tawfik A. Saleh; Z. H. Yamani

2011-01-01

267

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

268

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

269

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...

270

Electrochemical characterization of nanodimensional metal oxide materials  

NASA Astrophysics Data System (ADS)

Energy storage devices have become a bottleneck in performance improvements for portable electronics. This research seeks to answer basic science questions that may lead to the necessary improvements. First, this work demonstrates that insertion of multivalent ions into vanadium oxide greatly exceeds the storage capacity of materials presently used. Second, this work demonstrates that potassium ferrate exhibits a uniquely large pseudocapacitive effect. This effect can be used to great advantage when high power density and high energy density are required. Lastly, this work proposes a model of pseudocapacitance that has a greater descriptive power than that of previous models.

Tang, Paul Enle

271

Perspectives on the metallic interconnects for solid oxide fuel cells.  

PubMed

The various stages and progress in the development of interconnect materials for solid oxide fuel cells (SOFCs) over the last two decades are reviewed. The criteria for the application of materials as interconnects are highlighted. In-terconnects based on lanthanum chromite ceramics demonstrate many inherent drawbacks and therefore are only useful for SOFCs operating around 1000 degrees C. The advance in the research of anode-supported flat SOFCs facilitates the replacement of ceramic interconnects with metallic ones due to their significantly lowered working temperature. Besides, interconnects made of metals or alloys offer many advantages as compared to their ceramic counterpart. The oxidation response and thermal expansion behaviors of various prospective metallic interconnects are examined and evaluated. The minimization of contact resistance to achieve desired and reliable stack performance during their projected lifetime still remains a highly challenging issue with metallic interconnects. Inexpensive coating materials and techniques may play a key role in pro-moting the commercialization of SOFC stack whose interconnects are constructed of some current commercially available alloys. Alternatively, development of new metallic materials that are capable of forming stable oxide scales with sluggish growth rate and sufficient electrical conductivity is called for. PMID:15547954

Zhu, Wei-Zhong; Yan, Mi

2004-12-01

272

The effect of composition of Ni-supported Pt-Ru binary anode catalysts on ethanol oxidation for fuel cells  

Microsoft Academic Search

The effect of the composition of a platinum-ruthenium (Pt-Ru) binary catalyst on a Ni-support for the anodic oxidation of ethanol in aqueous alkaline media has been studied. Co-deposition of nano-crystallites of a Pt-Ru electrocatalyst of varying composition, has been made on Ni-supports by galvanostatic deposition from precursor salt solutions of suitable composition, without using any capping agent. Conjugated scanning electron

Joyeeta Bagchi; Swapan Kumar Bhattacharya

2007-01-01

273

Nanoscale limitations in metal oxide electrocatalysts for oxygen evolution.  

PubMed

Metal oxides are attractive candidates for low cost, earth-abundant electrocatalysts. However, owing to their insulating nature, their widespread application has been limited. Nanostructuring allows the use of insulating materials by enabling tunneling as a possible charge transport mechanism. We demonstrate this using TiO2 as a model system identifying a critical thickness, based on theoretical analysis, of about ?4 nm for tunneling at a current density of ?1 mA/cm(2). This is corroborated by electrochemical measurements on conformal thin films synthesized using atomic layer deposition (ALD) identifying a similar critical thickness. We generalize the theoretical analysis deriving a relation between the critical thickness and the location of valence band maximum relative to the limiting potential of the electrochemical surface process. The critical thickness sets the optimum size of the nanoparticle oxide electrocatalyst and this provides an important nanostructuring requirement for metal oxide electrocatalyst design. PMID:25216362

Viswanathan, Venkatasubramanian; Pickrahn, Katie L; Luntz, Alan C; Bent, Stacey F; Nørskov, Jens K

2014-10-01

274

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

275

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

276

Mechanistic aspects of photooxidation of polyhydroxylated molecules on metal oxides.  

PubMed

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(2), ?-FeOOH, and ?-Fe(2)O(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(2) oxidizes all of the carbohydrates and polyols, whereas ?-FeOOH oxidizes some of the carbohydrates, and ?-Fe(2)O(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. PMID:21532934

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

2011-03-24

277

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

E-print Network

Molten oxide electrolysis (MOE) is the electrolytic decomposition of a metal oxide, most preferably into liquid metal and oxygen gas. The successful deployment of MOE hinges upon the existence of an inert anode capable of ...

Wang, Dihua

278

Electrical excitation of colloidally synthesized quantum dots in metal oxide structures  

E-print Network

This thesis develops methods for integrating colloidally synthesized quantum dots (QDs) and metal oxides in optoelectronic devices, presents three distinct light emitting devices (LEDs) with metal oxides surrounding a QD ...

Wood, Vanessa Claire

2010-01-01

279

Oxides in metal fixed points of the ITS-90  

NASA Astrophysics Data System (ADS)

In the range between 0 °C and 961 °C, the International Temperature Scale of 1990 (ITS-90) depends to a great extent on the freezing points of the pure metals gallium, indium, tin, zinc, aluminium and silver. An up-to-date realization of these fixed points is based on cells containing metals of ultra-high purity (6N or better) and should include a correction for the influence of relevant impurities. Still, chemical analyses of the fixed-point material can show large amounts of oxygen, which had to be neglected so far, because of the lack of detailed knowledge about it, presuming it could be removed from the cell by applying a vacuum (less than 1 Pa) for a few hours. In this paper we discuss an equilibrium of several forms of oxygen in a fixed-point cell, gaseous in the cell's atmosphere, dissolved in the fixed-point metal and as oxide in a separate (solid) phase. We will conclude that in many fixed points most of the oxygen is not dissolved in the metal, but bound in oxides of the fixed-point metal as well as oxides of some impurities. To demonstrate the impact that the precipitation of impurity oxides has on thermometry, two indium fixed-point cells were doped with magnesium and chromium, which leave the fixed-point temperature unchanged. Further evidence is drawn from earlier work. All these results support the presumed existence of (at least one) persistent separate oxide phase in the fixed points of indium, tin, zinc and aluminium, which renders them eutectic or peritectic points and is a more likely reason why the oxygen content of a cell does not influence the fixed-point temperature. To complement these studies, thermodynamic calculations show how to treat the equilibrium in the cell quantitatively. Using available chemical data, a list is provided that indicates for each fixed-point metal (including the other metal fixed points of the ITS-90: mercury, gold, copper) the impurities that probably build oxides. Due to the agreement of the calculated values with the presented experimental results, we suggest excluding those impurities from the correction of a fixed-point temperature (e.g. the SIE method), unless there is strong evidence of their dissolution.

Fahr, Martin; Rudtsch, Steffen

2009-10-01

280

Optical characterization of heavy metal non-conventional binary PbO-ZnO glasses  

NASA Astrophysics Data System (ADS)

Non-conventional heavy metal oxide glasses of the system (100- x) PbO- xZnO in the composition range 5-40 mol% of ZnO have been prepared by melt-quenching technique. X-ray diffraction, UV-visible, and Fourier transform infrared (FTIR) absorption spectroscopy techniques were applied for the characterization of prepared glasses. From the absorption edge studies, the values of the optical band gap E opt and Urbach energy (? E) have been evaluated. From the experimental results, values of the optical energy gap are calculated and found to be dependent on the glass composition. FTIR spectra of the glasses reveal vibrational modes characteristic to combined presence of tetrahedral PbO4 and ZnO4 units in their specific different wavenumbers.

Marzouk, M. A.; Fayad, A. M.

2014-07-01

281

Dynamics of stellar black holes in young star clusters with different metallicities - I. Implications for X-ray binaries  

E-print Network

We present N-body simulations of intermediate-mass (3000-4000 Msun) young star clusters (SCs) with three different metallicities (Z=0.01, 0.1 and 1 Zsun), including metal-dependent stellar evolution recipes and binary evolution. Following recent theoretical models of wind mass loss and core collapse supernovae, we assume that the mass of the stellar remnants depends on the metallicity of the progenitor stars. In particular, massive metal-poor stars (Z=25 Msun) through direct collapse. We find that three-body encounters, and especially dynamical exchanges, dominate the evolution of the MSBHs formed in our simulations. In SCs with Z=0.01 and 0.1 Zsun, about 75 per cent of simulated MSBHs form from single stars and become members of binaries through dynamical exchanges in the first 100 Myr of the SC life. This is a factor of >~3 more efficient than in the case of low-mass (power wind-accreting (10-20 per cent) and Roche lobe overflow ...

Mapelli, M; Ripamonti, E; Bressan, A

2012-01-01

282

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

283

Chemical Reactivity at Metal Oxide-Aqueous Solution Interfaces  

NASA Astrophysics Data System (ADS)

The chemical reactivity of metal oxide surfaces in contact with aqueous solutions, with respect to cations and anions, is controlled by the composition, structure, and charging properties of the surface, the dielectric properties of the bulk oxide, and the stability of the aqueous cation or anion complex versus its sorption complex. These points will be illustrated for selected cations, anions, and metal oxides using macroscopic uptake and EXAFS spectroscopy results, x-ray standing wave data, and crystal truncation rod diffraction data. The reactivity of metal oxide surfaces with respect to low molecular weight (LMW) carboxylic acids is also dependent on the types of ring structures formed between surface functional groups and the LMW organic molecules. These types of interactions will be illustrated using ATR-FTIR data and dissolution measurements as a function of pH for oxalate, maleate, phthalate, and pyromellitate interacting with boehmite (AlOOH). Co-Authors are Tae Hyun Yoon, Stephen B. Johnson, Dept. of Geological & Environmental Sciences, Stanford University, Stanford CA 94305-2115; Thomas P. Trainor, Dept. of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK 99775; Anne M. Chaka, National Institute of Standards and Technology, Gaithersburg, MD 20899

Brown, Gordon E., Jr.

2005-03-01

284

Thin and thick films of metal oxides and metal phthalocyanines as gamma radiation dosimeters  

Microsoft Academic Search

Numerous efforts were devoted to investigating the influence of radiation on metal oxides and polymer materials for dosimetry applications. Metal oxides, such as NiO, LaFeO3, CeO2, TeO2, In2O3, SiO and MnO, and polymers, such as CuPc, NiPc, MnPc and CoPc, were used as the active constituents in the fabrication of ?-radiation sensors. Thin and thick film devices were made in

Khalil Arshak; Arousian Arshak; Saleh Zleetni; Olga Korostynska

2004-01-01

285

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

286

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

287

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

288

Improved 4H-SiC metal oxide semiconductor interface produced by using an oxidized SiN gate oxide that had undergone post-oxidation annealing  

NASA Astrophysics Data System (ADS)

We investigated oxidized SiN gate oxides that have undergone post-oxidation annealing (POA) treatment using diluted O2 (10% O2 in N2) at 1100 °C. The oxidized SiN/SiC interfaces were characterized by using capacitance-voltage (C-V) measurements, Auger electron spectroscopy (AES), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). POA for 60 min significantly improved the interface trap density (D it ), near-interface trap density (N it ), and effective oxide charge density (Q eff ) of the oxidized SiN. However, improvement was not observed for the as-oxidized SiN sample or the oxidized SiN sample that had undergone POA for 120 min. The electrical properties of metal-oxide semiconductor devices fabricated using these oxides are discussed in terms of the oxide chemical composition.

Moon, Jeong Hyun; Bahng, Wook; Kang, In Ho; Kim, Sang Cheol; Na, Moon Geong; Kim, Nam-Kyun

2014-05-01

289

Ferrous iron sorption by hydrous metal oxides.  

PubMed

Ferrous iron is critical to a number of biogeochemical processes that occur in heterogeneous aquatic environments, including the abiotic reductive transformation of subsurface contaminants. The sorption of Fe(II) to ubiquitous soil minerals, particularly iron-free mineral phases, is not well understood. Colloidal TiO2, gamma-AlOOH, and gamma-Al2O2 were used as model hydrous oxides to investigate Fe(II) sorption to iron-free mineral surfaces. Rapid Fe(II) sorption during the first few hours is followed by a much slower uptake process that continues for extended periods (at least 30 days). For equivalent solution conditions, the extent of Fe(II) sorption decreases in the order TiO2 >gamma-Al2O3 >gamma-AlOOH. Short-term equilibrium sorption data measured over a wide range of conditions (pH, ionic strength, Fe(II)-to-sorbent ratio) are well described by the diffuse double layer model. Fe(II) sorption to TiO2 is best described by a single-site model that considers formation of two surface complexes, SOFe+ and SOFeOH0. For gamma-AlOOH and gamma-Al2O3, sorption data are best described by a two-site model that considers formation of SOFe+ complexes at weak- and strong-binding surface sites. Accurate description of sorption data for higher Fe(II) concentrations at alkaline pH conditions requires the inclusion of a Fe(II) surface precipitation reaction in the model formulation. The presence of common groundwater constituents (calcium, sulfate, bicarbonate, or fulvic acid) had no significant effect on Fe(II) sorption. These results demonstrate that iron-free soil minerals can exert a significant influence on Fe(II) sorption and speciation in heterogeneous aquatic systems. PMID:16337955

Nano, Genevieve Villaseñor; Strathmann, Timothy J

2006-05-15

290

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

291

Comparative study of polyoxometalates and semiconductor metal oxides as catalyst. Photochemical oxidative degradation of thioethers  

Microsoft Academic Search

The photochemical degradation of thioether substrates catalyzed by representative semiconductor metal oxides and sulfides (anatase TiOâ, SnOâ, cubic WOâ, and CdS) and photoredox-active early-transition-metal polyometalates (WââOââ⁴⁻, PMoââOââ³⁻, PWââOââ³⁻, SiMoââOââ⁴⁻, PVâMoââOââ⁵⁻, and PâWââOââ⁶⁻) have been examined under both anaerobic and aerobic conditions. Under anaerobic conditions, all the semiconductors are completely ineffective at photochemically oxidizing or degrading the exemplary thioether substrate tetrahydrothiophene

R. Carlisle. Chambers; Craig L. Hill

1991-01-01

292

Electrochemical characteristics of metal oxide-coated lithium manganese oxide (spinel type)  

Microsoft Academic Search

Metal oxide-coated spinel was investigated with respect to electrochemical characteristics. Metal oxide coating on commercial spinel powder (LiMn2?xMxO4, M=Zr, Nikki, Japan) was carried out using the sol–gel method. Al2O3\\/CuOx-coated spinel exhibited stable cycle performance in the range from 3.0 to 4.4V, and it had lower charge transfer resistance and higher double layer capacitance than bare spinel in later cycles. In

Seung-Won Lee; Kwang-Soo Kim; Ki-Lyoung Lee; Hee-Soo Moon; Hyun-Joong Kim; Byung-Won Cho; Won-Il Cho; Jong-Wan Park

2004-01-01

293

Electrochemical and structural characteristics of metal oxide-coated lithium manganese oxide (spinel type)  

Microsoft Academic Search

The electrochemical and structural characteristics of the metal oxide-coated spinel were investigated in the range of 2.5–4.2V. Metal oxide coating on commercial spinel powder (LiMn2?xMxO4, M=Zr, Nikki, Japan) was carried out using the sol–gel method. Al2O3\\/(PtOx or CuOx)-coated spinel exhibited improved cyclability compared to bare spinel. Impedance analysis results indicated that electrochemical resistance value was not consistent with cycle performance.

Seung-Won Lee; Kwang-Soo Kim; Hee-Soo Moon; Jae-Pil Lee; Hyun-Joong Kim; Byung-Won Cho; Won-Il Cho; Jong-Wan Park

2004-01-01

294

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

295

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, Andre E.; Madler, Lutz

2014-01-01

296

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

297

High temperature silver-palladium-copper oxide air braze filler metal  

NASA Astrophysics Data System (ADS)

The Ag-CuO system is currently being investigated as the basis for an air braze filler metal alloy to be used in SOFC components. The system is of interest because unlike most braze alloys, it is capable of wetting a variety of ceramic materials while being applied in an air. This thesis work examined modification of Ag-CuO filler metal system by alloying with palladium to increase the use temperature of the resulting air braze alloy. Thermal analysis was performed to track changes in the solidus and liquidus temperatures for these alloys and determine equilibrium phase present as a function of temperature and composition. Sessile drop experiments were performed to investigate the effect of palladium addition on braze wetability. The influence of copper-oxide and palladium contents on brazed joint strength was characterized by a combination of four-point bend testing and fractography. From combined thermal analysis and quenched data it was found that both the liquidus and solidus increase with increasing palladium content, and the silver-rich miscibility gap boundary could be shifted by the addition of palladium. This was employed as a tool to study the effects of two-liquid phase formation on wetting behavior. In addition, a mass loss likely attributable to silver volatilization is observed in the Pd-modified filler metals when heated over ˜1100°C. As volatilization should be avoided, the ternary alloys should be limited to 15mol% Pd. It was found by sessile drop wetting experiments that there is a definitive change in wetting behavior that corresponds directly to the miscibility gap boundary for the Pd-Ag-CuO system. The first order transition tracks with changes in the miscibility gap boundary that can be induced by increasing palladium content. This is the first experimental evidence of critical point wetting behavior reported for a metal-oxide system and further confirms that critical point wetting theory is universal. Four-point bend testing and fractography of YSZ-YSZ joints brazed using binary and 5mol% Pd and 15mol% Pd ternary air braze alloys found that the specimens joined using binary Ag-2CuO compositions exhibited the highest average bend strength, 148+/-24MPa. In general increasing additions of palladium appeared to reduce room temperature bend strength. Increases in liquidus and solidus temperatures with palladium additions are expected to improve high temperature strength although this still needs to be verified.

Darsell, Jens Tommy

298

The synthesis of metal oxide nanowires by directly heating metal samples in appropriate oxygen atmospheres  

NASA Astrophysics Data System (ADS)

ZnO, MgO, and GeO2 nanowires were successfully synthesized by simply heating the desired metal powder to a temperature above its melting point in a flow of mixed gases (20% O2, 80% Ar, with the total flow rate of 120 sccm). Transmission electron microscopy observations show that as-synthesized products are exclusively nanowires, structurally uniform and single crystalline. The same technique was used to fabricate arrays of ZnO nanowires on silicon substrates, which would be of particular interest for direct integration in the current silicon-technology-based optoelectronic devices. Based on our experimental results, a metal self-catalytic growth mechanism was proposed and described conceptually. Because of the absence of impurities such as transition metal or noble metal throughout the whole growth process, the intrinsic properties of the resulting metal oxide nanowires could be expressed and utilized. And with in-depth understanding of the growth mechanism, our method could be efficient and controllable in extension to many other low-melting-point metals, such as Al, In, and Sn, for the synthesis of corresponding metal oxide nanostructures.

Dang, H. Y.; Wang, J.; Fan, S. S.

2003-07-01

299

Dynamics and Control in Complex Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

Advances in the synthesis, growth, and characterization of complex transition metal oxides coupled with new experimental techniques in ultrafast optical spectroscopy have ushered in an exciting era of dynamics and control in these materials. Experiments utilizing femtosecond optical pulses can initiate and probe dynamics of the spin, lattice, orbital, and charge degrees of freedom. Major goals include (a) determining how interaction and competition between the relevant degrees of freedom determine macroscopic functionality in transition metal oxides (TMOs) and (b) searching for hidden phases in TMOs by controlling dynamic trajectories in a complex and pliable energy landscape. Advances in creating intense pulses from the far-IR spectrum through the visible spectrum enable mode-selective excitation to facilitate exploration of these possibilities. This review covers recent developments in this emerging field and presents examples that include the cuprates, manganites, and vanadates.

Zhang, J.; Averitt, R. D.

2014-07-01

300

Understanding Organic Film Behavior on Alloy and Metal Oxides  

PubMed Central

Native oxide surfaces of stainless steel 316L and Nitinol alloys and their constituent metal oxides namely, nickel, chromium, molybdenum, manganese, iron and titanium were modified with long chain organic acids to better understand organic film formation. The adhesion and stability of films of octadecylphosphonic acid, octadecylhydroxamic acid, octadecylcarboxylic acid and octadecylsulfonic acid on these substrates was examined in this study. The films formed on these surfaces were analyzed by diffuse reflectance infrared Fourier transform spectroscopy, contact angle goniometry, atomic force microscopy and matrix assisted laser desorption ionization mass spectrometry. The effect of the acidity of the organic moiety and substrate composition on the film characteristics and stability is discussed. Interestingly, on the alloy surfaces, the presence of less reactive metal sites does not inhibit film formation. PMID:20039608

Raman, Aparna; Quinones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash

2010-01-01

301

A metallic fuel cycle concept from spent oxide fuel to metallic fuel  

SciTech Connect

A Metallic fuel cycle concept for Self-Consistent Nuclear Energy System (SCNES) has been proposed in a companion papers. The ultimate goal of the SCNES is to realize sustainable energy supply without endangering the environment and humans. For future transition period from LWR era to SCNES era, a new metallic fuel recycle concept from LWR spent fuel has been proposed in this paper. Combining the technology for electro-reduction of oxide fuels and zirconium recovery by electrorefining in molten salts in the nuclear recycling schemes, the amount of radioactive waste reduced in a proposed metallic fuel cycle concept. If the recovery ratio of zirconium metal from the spent zirconium waste is 95%, the cost estimation in zirconium recycle to the metallic fuel materials has been estimated to be less than 1/25. (authors)

Fujita, Reiko; Kawashima, Masatoshi; Yamaoka, Mitsuaki [Power and Industrial Systems Research and Development Center, Toshiba Corporation, 4-1, Ukishima-cho, Kawasaki-ku, Kawasaki, 210-0862 (Japan); Arie, Kazuo [Nuclear Energy Systems and Services Dev., Toshiba Corporation, 4-1, Ukishima-cho, Kawasaki-ku, Kawasaki, 210-0862 (Japan); Koyama, Tadafumi [Central research Institute of Electric Power Industry (Japan)

2007-07-01

302

Voltage oxide removal for plating: A new method of electroplating oxide coated metals in situ  

SciTech Connect

A novel in situ method for electroplating oxide coated metals is described. Termed VORP, for voltage oxide removal for plating, the process utilizes a voltage pulse {approx}20-200 V, {approx}2 ms in duration, applied between working and counterelectrodes while both are immersed in a copper electrolyte. The pulse is almost immediately followed by galvanostatic plate-up. Adherent copper deposits up to {approx}4 {mu}m in height on stainless steel 316 coupons have been obtained. Temperature testing up to 260 deg. C in air does not affect the copper adhesion. A preliminary model for oxide removal is proposed utilizing concepts of dielectric breakdown.

Gutfeld, R. J. von; West, A. C. [Department of Chemical Engineering, Columbia University, New York, New York 10027 (United States)

2007-03-15

303

Synthesis and characterization of nanoporous, nanorods, nanowires metal oxides  

Microsoft Academic Search

Mesoporous high surface area and high crystallinity MO2 (M=Ti, Ce, Zr, and Hf) and their mixed oxides powders were synthesized by a modified sol–gel method using laurylamine hydrochloride, metal alkoxide and acetylacetone. The prepared powders had a crystalline size of about 5–15nm, a specific surface area of 44–80m2\\/g, and a narrow pore size distribution with average pore diameter of about

Sorapong Pavasupree; Yoshikazu Suzuki; Sommai Pivsa-Art; Susumu Yoshikawa

2005-01-01

304

Energetic Surface Smoothing of Complex Metal-Oxide Thin Films  

Microsoft Academic Search

A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of La1-xSrxMnO3 on SrTiO3, using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the formation

P. R. Willmott; R. Herger; C. M. Schlepütz; D. Martoccia; B. D. Patterson

2006-01-01

305

Energetic Surface Smoothing of Complex Metal-Oxide Thin Films  

Microsoft Academic Search

A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of La{sub 1-x}SrâMnOâ on SrTiOâ, using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the

P. R. Willmott; R. Herger; C. M. Schlepuetz; D. Martoccia; B. D. Patterson

2006-01-01

306

Identification of a new pseudo-binary hydroxide during calendar corrosion of (La, Mg)2Ni7-type hydrogen storage alloys for Nickel-Metal Hydride batteries  

E-print Network

1 Identification of a new pseudo-binary hydroxide during calendar corrosion of (La, Mg)2Ni7-type hydrogen storage alloys for Nickel-Metal Hydride batteries J. Monnier 1 , H. Chen 1 , S. Joiret2,3 , J Abstract To improve the performances of Nickel-Metal Hydride batteries, an important step

Boyer, Edmond

307

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

308

Fabrication of metal-oxide nano-composite films from aqueous solution by metal-oxide co-electrodeposition  

Microsoft Academic Search

Fe–Ce–O films were synthesized by a newly developed electrochemical method called the “metal-oxide co-electrodeposition method”, i.e. the simultaneous deposition of Fe and Ce–O from a reaction solution containing FeSO4, CeCl3, (NH4)2SO4, and l-ascorbic acid. l-ascorbic acid prevents the oxidation of Fe2+ to Fe3+. (NH4)2SO4 acts as the complexing agent for Fe2+ and was effective in avoiding the precipitation of Fe–OH.

N. Fujita; M. Izaki; M. Inoue

2006-01-01

309

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

310

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

311

Strengthening of metallic alloys with nanometer-size oxide dispersions  

DOEpatents

Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

Flinn, John E. (Idaho Falls, ID); Kelly, Thomas F. (Madison, WI)

1999-01-01

312

Dual-environment effects on the oxidation of metallic interconnects  

SciTech Connect

Metallic interconnects in solid oxide fuel cells are exposed to a dual environment: fuel on one side (i.e., H2 gas) and oxidizer on the other side (i.e., air). It has been observed that the oxidation behavior of thin stainless steel sheet in air is changed by the presence of H2 on the other side of the sheet. The resulting dual-environment scales are flaky and more friable than the single-environment scales. The H2 disrupts the scale on the air side. A model to explain some of the effects of a dual environment is presented where hydrogen diffusing through the stainless steel sheet reacts with oxygen diffusing through the scale to form water vapor, which has sufficient vapor pressure to mechanically disrupt the scale. Experiments on preoxidized 316L stainless steel tubing exposed to air-air, H2-air, and H2-Ar environments are reported in support of the model.

Holcomb, G.R.; Ziomek-Moroz, M.; Covino, B.S., Jr.; Bullard, S.J.

2006-08-01

313

Strengthening of metallic alloys with nanometer-size oxide dispersions  

DOEpatents

Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains. 20 figs.

Flinn, J.E.; Kelly, T.F.

1999-06-01

314

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

315

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

316

Depth Distribution of Lithium in Oxidized Binary Al-Li Alloys Determined by Secondary Ion Mass Spectrometry and Neutron Depth Profiling  

Microsoft Academic Search

Oxidation of binary Al-Li alloys during short exposures at 530 C and long exposures at 200 C was studied with regard to the Li distribution. Secondary ion mass spectrometry (SIMS) and neutron depth profiling (NDP) were used to obtain quantitative Li depth profiles across the surface oxide layer and the underlying alloy. The underlying alloy was depleted in Li as

K. K. Soni; G. K. Lamaza; D. B. Williams; D. E. Newbury; R. G. Downing; P. K. Chi

1993-01-01

317

THE RÔLE OF CERTAIN METALLIC IONS AS OXIDATION CATALYSTS  

PubMed Central

1. When iron and copper are allowed to act on hydrogen peroxide and pyrogallol, enough carbon dioxide is produced to be readily measured. 2. The curve of the production of carbon dioxide may be fitted by an empirical equation, by the use of which the initial rate and the total amount of the oxidation may be determined. 3. The effect of the concentration of the reagents is different in each case, the effect varying as a fractional power of the copper and pyrogallol concentrations and as a logarithmic function of the hydrogen peroxide concentration. 4. When gold or silver is used the rate changes suddenly during the course of the reaction due to the precipitation of colloidal metal. 5. Mercury, cadmium, zinc, tin, and some other metals have no effect. 6. A theoretical set of equations is assumed to account for the action of the metals. 7. The metals are assumed to act by means of the formation of intermediate peroxides. 8. Experiments on the action of gold indicate that the metals are active in the ionic and not in the colloidal state. PMID:19872322

Cook, S. F.

1926-01-01

318

Extended Frenkel pairs and band alignment at metal-oxide interfaces  

Microsoft Academic Search

We show how oxygen vacancies in metal oxides next to high-work-function metals are stabilized by an oxygen exchange reaction with the metal, and by a charge transfer from the vacancy energy level to the metal Fermi level. The results help explain some of the Fermi-level pinning problems in high- k dielectric gate stacks in complimentary metal oxide semiconductor technology and

O. Sharia; K. Tse; J. Robertson; Alexander A. Demkov

2009-01-01

319

Nanocasted synthesis of mesoporous metal oxides and mixed oxides from mesoporous cubic (Ia3d) vinylsilica.  

PubMed

Mesoporous metal oxides and mixed oxides, such as NiO, CeO2, Cr2O3, Fe203, Mn2O3, NiFe2O4 and Ce(x)Zr(1-x)O2 (x=0.8 and 0.6) have been synthesized by nanocasting from mesoporous cubic (la3d) vinyl-functionalized silica (vinylsilica). Their structural properties were characterized by XRD, TEM, N2-sorption and Raman spectra. Thus-prepared mesoporous materials possess a high BET surface area (110-190 m2g(-1)), high pore volume (0.25-0.40 cm3g(-1)) and relatively ordered structures. The catalytic properties of Cr2O3 were tested in the oxidation of toluene. The mesoporous Cr2O3 exhibits unusually high catalytic activity in the complete oxidation of toluene as compared with commercial Cr2O3. PMID:19198284

Wang, Yangang; Wang, Yanqin; Liu, Xiaohui; Guo, Yun; Guo, Yanglong; Lu, Guanzhong; Schüth, Ferdi

2008-11-01

320

Oxide Electronics Utilizing Ultrafast Metal-Insulator Transitions  

NASA Astrophysics Data System (ADS)

Although phase transitions have long been a centerpiece of condensed matter materials science studies, a number of recent efforts focus on potentially exploiting the resulting functional property changes in novel electronics and photonics as well as understanding emergent phenomena. This is quite timely, given a grand challenge in twenty-first-century physical sciences is related to enabling continued advances in information processing and storage beyond conventional CMOS scaling. In this brief review, we discuss synthesis of strongly correlated oxides, mechanisms of metal-insulator transitions, and exploratory electron devices that are being studied. Particular emphasis is placed on vanadium dioxide, which undergoes a sharp metal-insulator transition near room temperature at ultrafast timescales. The article begins with an introduction to metal-insulator transition in oxides, followed by a brief discussion on the mechanisms leading to the phase transition. The role of materials synthesis in influencing functional properties is discussed briefly. Recent efforts on realizing novel devices such as field effect switches, optical detectors, nonlinear circuit components, and solid-state sensors are reviewed. The article concludes with a brief discussion on future research directions that may be worth consideration.

Yang, Zheng; Ko, Changhyun; Ramanathan, Shriram

2011-08-01

321

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-X (where 0metal 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.

Capone, Donald W. (Bolingbrook, IL); Dunlap, Bobby D. (Bolingbrook, IL); Veal, Boyd W. (Downers Grove, IL)

1990-01-01

322

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

323

EPR monitoring of redox processes in transition metal oxide catalysts.  

PubMed

Transition metal oxides (TMO) are widely used as catalysts of a number of catalytic reactions, mainly of redox nature. This is due to the unique ability of transition metal ions to change easily their oxidation state, coordination, and/or arrangement of the coordination polyhedra. At present, the only abundant, direct information available about paramagnetic centers formed during interaction of the reagents with the TMO surface stems from EPR studies. This technique is very sensitive and allows detection of very small concentration of paramagnetic sites. Moreover, analysis of the EPR spectrum offers a direct approach to the determination of symmetry and electronic structure of the centers concerned. Such information is of particular value for understanding the operating reduction/reoxidation mechanisms, with immediate implications for solid-state structural studies, catalysis and so forth. The present work shows two aspects of the use of EPR for monitoring of redox processes with the participation of TMO: a) investigation of the reaction kinetics and b) description of the individual active sites involved in the catalytically important redox processes. The presented examples include: a) kinetic descriptions (including mathematical models) of reduction and oxidation processes in the vanadia-molybdena catalysts occurring upon interaction with propene and oxygen, b) identification of paramagnetic centers formed in the reduced molybdena, c) analysis of the butene interaction with a nickel catalyst, and d) description of the radical oxygen species on the surface of manganese-containing catalysts. PMID:23686922

Labanowska, M

2001-12-17

324

Synthesis and NMR characterization of ligand-capped metal and metal-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Ligand-capped metal and metal-oxide nanoparticles (NPs) have some interesting and useful physical properties that are not present in their respective bulk materials. These properties are of research interest in many applications such as catalysis, drug delivery, biological imaging, and plasmonics. In such applications, it is critical to understand the surface structure of NPs and the roles played by the surface bound ligands. To characterize surface environment, ligand dynamics, and exchange kinetics, ligand-capped metal and metal-oxide NPs are synthesized and studied by multinuclear NMR. Phosphines and phosphonic acids are used to passivate metal (gold and silver) and metal-oxide (tin dioxide) NPs in different sizes (1-5 nm) by following published procedures or original synthesis methods. In both solution and solid state NMR, the 31P chemical shift of surface-bound ligands are distinctly different from those observed for free ligands. Additionally, NMR line widths in surface-bound ligands are highly broadened compared to those of free ligands. The lines are broadened due to both homogeneous and inhomogeneous broadening mechanisms, determined through hole burning NMR and spin-spin relaxation measurements. In small particles (< 2 nm), the main source of line broadening is inhomogeneous and originates due to structural heterogeneity and underlying chemical shift distributions. In large particles (> 2 nm), both inhomogeneous and homogeneous line broadening mechanisms are present. When the particles' sizes increase from small to large, the homogeneous broadening mechanism becomes dominant due to strong nuclear-electron interaction and reintroduction of residual dipolar coupling as shown by a combination of 1H, 13C and 31P NMR. Results from a series of ligand exchange experiments in silver and gold NPs further indicate the presence of Au(I) and Ag(I) on the particle surfaces.

Sharma, Ramesh

325

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

326

Identifying the isolated transition metal ions\\/oxides in molecular sieves and on oxide supports by UV resonance Raman spectroscopy  

Microsoft Academic Search

Isolated transition metal ions\\/oxides in molecular sieves and on surfaces are a class of active sites for selective oxidation of hydrocarbons. Identifying the active sites and their coordination structure is vital to understanding their essential role played in catalysis and designing and synthesizing more active and selective catalysts. The isolated transition metal ions in the framework of molecular sieves (e.g.,

2003-01-01

327

Carbon nanotube–metal–oxide nanocomposites: microstructure, electrical conductivity and mechanical properties  

Microsoft Academic Search

Carbon nanotube–metal–oxide composites (metal=Fe, Co or Fe\\/Co alloy; oxide=Al2O3, MgO or MgAl2O4) have been prepared by hot-pressing the corresponding composite powders, in which the carbon nanotubes, mostly single or double-walled, are very homogeneously dispersed between the metal–oxide grains. For the sake of comparison, ceramic and metal–oxide nanocomposites have also been prepared. The microstructure of the specimens has been studied and

E. FLAHAUT; A. PEIGNEY; Ch. LAURENT; Ch. MARLIERE; F. CHASTEL; A. ROUSSET

2000-01-01

328

Molecular precursor approach to nano-scaled ceramics and metal\\/metal oxide composites  

Microsoft Academic Search

Heterometal alkoxides are used as single-source precursors to obtain nanoscaled thin layers and powders of a variety of oxide ceramics and composites. The hydride alkoxide [MgH2Al(OBu')22] has been used for low-temperature deposits of crystalline MgAl2O4 spinel. The mixed-metal alkoxide [BaZr(OPri)5(OH)(PriOH)3]2, based on 1:1 stoichiometry of the metals, has been used for clean and selective synthesis (sol-gel) of nanocrystalline BaZrO3 ceramic.

M. Veith; A. Altherr; N. Lecerf; S. Mathur; K. Valtchev; E. Fritscher

1999-01-01

329

Effects of reduction of metal oxide sorbents on reactivity and physical properties during hot gas desulphurization in IGCC  

Microsoft Academic Search

In this study, the changes of physical properties and reactivity of the metal oxide sorbents were investigated under the reducing conditions of coal gas. Metal oxide sorbents are converted into metal sulphides as a result of reaction with H2S in synthesis gas. This could cause the reduced reactivity of sorbents if the metal oxides were converted into metallic elements due

No-Kuk Park; Dong-Hwal Lee; Jong-Dae Lee; Si-Ok Ryu; Tae-Jin Lee

2005-01-01

330

Kinetic and mechanistic aspects of metal ion catalysis in cerium(IV) oxidation  

Microsoft Academic Search

This review discusses the kinetic aspects of different metal ion catalysis in Ce(IV) oxidation of different types of organic and inorganic substrates in aqueous acid media. The reactions have been categorised with the metal ions acting as the catalysts. The nature of mechanism of catalysis in Ce(IV) oxidation depends on the nature of substrate for a particular metal ion catalyst

Asim K. Das

2001-01-01

331

A stable hydrogen-sensitive Pd gate metal-oxide semiconductor capacitor  

Microsoft Academic Search

A palladium gate metal-oxide semiconductor device has serious hydrogen-induced drift problems. We have shown that this drift can be eliminated through the introduction of a thin alumina layer between the metal and the silicon dioxide. This makes it possible to use Pd metal-oxide semiconductor devices as stable and accurate sensors for hydrogen.

M. Armgarth; C. Nylander

1981-01-01

332

Catalytic oxidation of CO by platinum group metals: from ultrahigh vacuum to elevated pressures  

E-print Network

Catalytic oxidation of CO by platinum group metals: from ultrahigh vacuum to elevated pressures A oxidation over platinum group metals has been investigated for some eight decades by many researchers in CO oxidation recently because of its technological importance in pollution control and fuel cells

Goodman, Wayne

333

A MultiParameter Platform For Gas Sensing Using Semiconducting Metal Oxide Films  

Microsoft Academic Search

A multi-parameter sensor platform for engineering gas responsive semiconducting metal oxide (SMO) materials and gas sensors is demonstrated. The platform combines a chemiresistor with a Metal Oxide Semiconductor (MOS) capacitor for the detection of oxidation-reduction reactions occurring in SMO films. With this platform, changes in resistance, work function, and capacitance of the SMO film can be simultaneously measured upon exposure

Guixiong Zhong; G. Bernhardt; R. Lad; S. Collins; R. Smith

2007-01-01

334

Combinatorial search for improved metal oxide oxygen evolution electrocatalysts in acidic electrolytes.  

PubMed

A library of electrocatalysts for water electrolysis under acidic conditions was created by ink jet printing metal oxide precursors followed by pyrolysis in air to produce mixed metal oxides. The compositions were then screened in acidic electrolytes using a pH sensitive fluorescence indicator that became fluorescent due to the pH change at the electrode surface because of the release of protons from water oxidation. The most promising materials were further characterized by measuring polarization curves and Tafel slopes as anodes for water oxidation. Mixed metal oxides that perform better than the iridium oxide standard were identified. PMID:23298465

Seley, David; Ayers, Katherine; Parkinson, B A

2013-02-11

335

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

336

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

337

Ionically-mediated electromechanical hysteresis in transition metal oxides  

SciTech Connect

Electromechanical activity, remanent polarization states, and hysteresis loops in paraelectric TiO2 and SrTiO3 are observed. The coupling between the ionic dynamics and incipient ferroelectricity in these materials is analyzed using extended Ginsburg Landau Devonshire (GLD) theory. The possible origins of electromechanical coupling including ionic dynamics, surface-charge induced electrostriction, and ionically-induced ferroelectricity are identified. For the latter, the ionic contribution can change the sign of first order GLD expansion coefficient, rendering material effectively ferroelectric. These studies provide possible explanation for ferroelectric-like behavior in centrosymmetric transition metal oxides.

Kim, Yunseok [ORNL] [ORNL; Kumar, Amit [ORNL] [ORNL; Jesse, Stephen [ORNL] [ORNL; Kalinin, Sergei V [ORNL] [ORNL

2012-01-01

338

Giant magnetoresistance in oxide-based metallic multilayers  

SciTech Connect

The authors report on the first measurement of low-field giant magnetoresistance in metallic multilayers of perovskite oxides. The authors performed in-plane measurements of the magnetoelectric transport properties in La{sub 0.75}Sr{sub 0.25}MnO{sub 3}/LaNiO{sub 3} trilayers and succeeded in distinguishing the giant magnetoresistance effect from other contributions to the total magnetoresistance. The samples were grown on single-crystalline SrTiO{sub 3} substrates by dc sputtering.

Granada, Mara; Rojas Sanchez, J. Carlos; Steren, Laura B. [Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica (R8402AGP) San Carlos de Bariloche, Rio Negro (Argentina)

2007-08-13

339

Pollution performance of 110 kV metal oxide arresters  

SciTech Connect

Pollution test results of single unit 110 kV metal oxide surge arresters with porcelain housing according to the solid layer and salt fog methods are presented. During 6 hours of testing, the internal and external charge and maximum temperature along the varistor column were measured. The formation of single stable dry bands on the housing was often observed, especially during salt fog tests. In such cases, the varistor temperature can reach about 70 C. The simple electrical model of the arrester enabling calculations of voltages and currents as a function of arrester and pollution parameters is shown.

Chrzan, K.; Pohl, Z. [Technical Univ. of Wroclaw (Poland). Dept. of Electrical Engineering] [Technical Univ. of Wroclaw (Poland). Dept. of Electrical Engineering; Grzybowski, S. [Mississippi State Univ., MS (United States). Dept. of Electrical and Computer Engineering] [Mississippi State Univ., MS (United States). Dept. of Electrical and Computer Engineering; Koehler, W. [Univ. of Stuttgart (Germany). Dept. of Electrical Engineering] [Univ. of Stuttgart (Germany). Dept. of Electrical Engineering

1997-04-01

340

Preparation and bifunctional gas sensing properties of porous In2O3-CeO2 binary oxide nanotubes.  

PubMed

The porous binary In(2)O(3)-CeO(2) oxides nanotubes (NTs) in cubic phase were first fabricated by electrospinning (ESP) method and characterized by SEM, TEM, XRD, XPS and UV-vis absorption techniques. By adjusting the In(2)O(3) and CeO(2) molar ratio, the out diameters and wall thicknesses of the final composites were tuned ranging of 90-180 nm and 15-9 nm, respectively. The band gap of the binary oxides gradually decreases, and the ratio of Ce(3+) to Ce(4+) increases with the increase of CeO(2), implying that surface oxygen vacancies gradually increase. The gas sensing test reveals that when the content of CeO(2) is appropriate, the as fabricated In(2)O(3)-CeO(2) NTs could be bifunctional gas sensors to detect H(2)S at low temperature(25-110 °C) while acetone at relative high temperature (300 °C). The In(75)Ce(25) NTs sensor is an optimum one, which exhibits the highest response of 498 to H(2)S at 80 °C and the highest response of 30 to acetone at 300 °C. In contrast to the pure In(2)O(3) sensor, the response and recovery times, as well as the sensing reaction barrier height, for In(75)Ce(25) both degrade considerably. The above temperature-dependent sensing properties were attributed to two different gas sensing mechanisms, sulfuration at low temperature and adsorption at high temperature. PMID:20949903

Xu, Lin; Song, Hongwei; Dong, Biao; Wang, Yu; Chen, Jiansheng; Bai, Xue

2010-11-15

341

First stars XI. Chemical composition of the extremely metal-poor dwarfs in the binary CS 22876-032  

NASA Astrophysics Data System (ADS)

Context: Unevolved metal-poor stars constitute a fossil record of the early Galaxy, and can provide invaluable information on the properties of the first generations of stars. Binary systems also provide direct information on the stellar masses of their member stars. Aims: The purpose of this investigation is a detailed abundance study of the double-lined spectroscopic binary CS 22876-032, which comprises the two most metal-poor dwarfs known. Methods: We used high-resolution, high-S/N ratio spectra from the UVES spectrograph at the ESO VLT telescope. Long-term radial-velocity measurements and broad-band photometry allowed us to determine improved orbital elements and stellar parameters for both components. We used OSMARCS 1D models and the turbospectrum spectral synthesis code to determine the abundances of Li, O, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Co and Ni. We also used the CO^5BOLD model atmosphere code to compute the 3D abundance corrections, notably for Li and O. Results: We find a metallicity of [Fe/H] ~ -3.6 for both stars, using 1D models with 3D corrections of ~-0.1 dex from averaged 3D models. We determine the oxygen abundance from the near-UV OH bands; the 3D corrections are large, -1 and -1.5 dex for the secondary and primary respectively, and yield [O/Fe] ~ 0.8, close to the high-quality results obtained from the [OI] 630 nm line in metal-poor giants. Other [ ?/Fe] ratios are consistent with those measured in other dwarfs and giants with similar [Fe/H], although Ca and Si are somewhat low ([X/Fe] ? 0). Other element ratios follow those of other halo stars. The Li abundance of the primary star is consistent with the Spite plateau, but the secondary shows a lower abundance; 3D corrections are small. Conclusions: The Li abundance in the primary star supports the extension of the Spite Plateau value at the lowest metallicities, without any decrease. The low abundance in the secondary star could be explained by endogenic Li depletion, due to its cooler temperature. If this is not the case, another, yet unknown mechanism may be causing increased scatter in A(Li) at the lowest metallicities.

González Hernández, J. I.; Bonifacio, P.; Ludwig, H.-G.; Caffau, E.; Spite, M.; Spite, F.; Cayrel, R.; Molaro, P.; Hill, V.; François, P.; Plez, B.; Beers, T. C.; Sivarani, T.; Andersen, J.; Barbuy, B.; Depagne, E.; Nordström, B.; Primas, F.

2008-03-01

342

A simple and generic approach for synthesizing colloidal metal and metal oxide nanocrystals  

NASA Astrophysics Data System (ADS)

A simple and generic approach--alternating voltage induced electrochemical synthesis (AVIES)--has been reported for synthesizing highly dispersed colloidal metal (Au, Pt, Sn, and Pt-Pd) and metal oxide (ZnO and TiO2) nanocrystals. The respective nanocrystals are produced when a zero-offset alternating voltage at 60 Hz is applied to a pair of identical metal wires, which are inserted in an electrolyte solution containing capping ligands. In the case of Au, the obtained nanocrystals are highly crystalline nano-icosahedra of 14 +/- 2 nm in diameter, the smallest Au icosahedra synthesized in aqueous solutions via green chemistry. Their catalytic activity has been demonstrated through facilitating the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride. This AVIES approach is an environmentally benign process and can be adopted by any research lab.

Cloud, Jacqueline E.; Yoder, Tara S.; Harvey, Nathan K.; Snow, Kyle; Yang, Yongan

2013-07-01

343

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

344

Surface tension of binary metal—surface active solute systems under conditions relevant to welding metallurgy  

Microsoft Academic Search

Since the fluid flow, heat transfer, and the resulting weld properties are significantly affected by interfacial tension driven\\u000a flow, the variation of interfacial tension in dilute binary solutions is studied as a function of both composition and temperature.\\u000a Entropy and enthalpy of adsorption of surface active components such as oxygen, sulfur, selenium, and tellurium in Fe-O, Fe-S,\\u000a Fe-Se, Cu-O, Cu-S,

P. Sahoo; T. Debroy; M. J. McNallan

1988-01-01

345

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

346

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

347

Ternary Self-Assembly of Ordered Metal Oxide Graphene Nanocomposites for  

E-print Network

properties.23,28 35 We focus on the nano- composites made of metal oxides (i.e., SnO2, NiO, MnO2, and SiO2Ternary Self-Assembly of Ordered Metal Oxide Graphene Nanocomposites for Electrochemical Energy-assembly of nanostructured metal oxides, semiconductors, and polymer materials.11 15 There has been a growing in- terest

Aksay, Ilhan A.

348

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

349

Nanostructured transition metal oxides for energy storage and conversion  

NASA Astrophysics Data System (ADS)

Lithium-ion batteries, supercapacitors and photovoltaic devices have been widely considered as the three major promising alternatives of fossil fuels facing upcoming depletion to power the 21th century. The conventional film configuration of electrochemical electrodes hardly fulfills the high energy and efficiency requirements because heavy electroactive material deposition restricts ion diffusion path, and lowers power density and fault tolerance. In this thesis, I demonstrate that novel nanoarchitectured transition metal oxides (TMOs), e.g. MnO2, V2O 5, and ZnO, and their relevant nanocomposites were designed, fabricated and assembled into devices to deliver superior electrochemical performances such as high energy and power densities, and rate capacity. These improvements could be attributed to the significant enhancement of surface area, shortened ion diffusion distances and facile penetration of electrolyte solution into open structures of networks as well as to the pseudocapacitance domination. The utilization of ForcespinningRTM, a newly developed nanofiber processing technology, for large-scale energy storage and conversion applications is emphasized. This process simplifies the tedious multi-step hybridization synthesis and facilitates the contradiction between the micro-batch production and the ease of large-scale manufacturing. Key Words: Transition metal oxides, energy storage and conversion, ForcespinningRTM, pseudocapacitance domination, high rate capacity

Li, Qiang

350

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

351

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-X (where 0<.times.<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.

Capone, Donald W. (Bolingbrook, IL)

1990-01-01

352

O2 adsorption dependent photoluminescence emission from metal oxide nanoparticles.  

PubMed

Optical properties of metal oxide nanoparticles are subject to synthesis related defects and impurities. Using photoluminescence spectroscopy and UV diffuse reflectance in conjunction with Auger electron spectroscopic surface analysis we investigated the effect of surface composition and oxygen adsorption on the photoluminescence properties of vapor phase grown ZnO and MgO nanoparticles. On hydroxylated MgO nanoparticles as a reference system, intense photoluminescence features exclusively originate from surface excitons, the radiative deactivation of which results in collisional quenching in an O2 atmosphere. Conversely, on as-prepared ZnO nanoparticles a broad yellow emission feature centered at h?Em = 2.1 eV exhibits an O2 induced intensity increase. Attributed to oxygen interstitials as recombination centers this enhancement effect originates from adsorbate-induced band bending, which is pertinent to the photoluminescence active region of the nanoparticles. Annealing induced trends in the optical properties of the two prototypical metal oxide nanoparticle systems, ZnO and MgO, are explained by changes in the surface composition and underline that particle surface and interface changes that result from handling and processing of nanoparticles critically affect luminescence. PMID:25277485

Gheisi, Amir R; Neygandhi, Chris; Sternig, Andreas K; Carrasco, Esther; Marbach, Hubertus; Thomele, Daniel; Diwald, Oliver

2014-11-21

353

Stability of metal oxide nanoparticles in aqueous solutions.  

PubMed

The application of nanoparticles in the processes of making commercial products has increased in recent years due to their unique physical and chemical properties. With increasing amount of commercial nanoparticles released into nature, their fate and effects on the ecosystem and human health are of growing concern. This study investigated the stability and morphology of three metal oxide nanoparticles in aqueous solutions. The commercially available nanoparticles, TiO(2), ZnO, SiO(2), aggregated quickly into micrometer-size particles in aqueous solutions, which may not threaten human health. Their changes in morphology and characteristics were further examined by dynamic light scattering (DLS) method and transmission electron microscopy (TEM). Among the several dispersion approaches, ultrasonication was found to be the most effective for disaggregating nanoparticles in water. For these three selected nanoparticles, ZnO could not remain stable in suspensions, presumably due to the dissolution of particles to form high concentration of ions, resulting in enhanced aggregation of particles. In addition, the existence of dissolved organic matters stabilized nanoparticles in lake water and wastewater for several hours in spite of the high concentration of cations in these real-water samples. The fate of metal oxide nanoparticles in natural water bodies would be determined by the type and concentration of cations and organic matters. Results obtained in this study revealed that the stability of nanoparticles changed under different aqueous conditions and so did their fate in the environment. PMID:20057098

Tso, Chih-ping; Zhung, Cheng-min; Shih, Yang-hsin; Tseng, Young-Ming; Wu, Shian-chee; Doong, Ruey-an

2010-01-01

354

Restructuring transition metal oxide nanorods for 100% selectivity in reduction of nitric oxide with carbon monoxide.  

PubMed

Transition metal oxide is one of the main categories of heterogeneous catalysts. They exhibit multiple phases and oxidation states. Typically, they are prepared and/or synthesized in solution or by vapor deposition. Here we report that a controlled reaction, in a gaseous environment, after synthesis can restructure the as-synthesized transition metal oxide nanorods into a new catalytic phase. Co3O4 nanorods with a preferentially exposed (110) surface can be restructured into nonstoichiometric CoO1-x nanorods. Structure and surface chemistry during the process were tracked with ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and environmental transmission electron microscopy (E-TEM). The restructured nanorods are highly active in reducing NO with CO, with 100% selectivity for the formation of N2 in temperatures of 250-520 °C. AP-XPS and E-TEM studies revealed the nonstoichiometric CoO1-x nanorods with a rock-salt structure as the active phase responsible for the 100% selectivity. This study suggests a route to generate new oxide catalysts. PMID:23731229

Zhang, Shiran; Shan, Junjun; Zhu, Yuan; Nguyen, Luan; Huang, Weixin; Yoshida, Hideto; Takeda, Seiji; Tao, Franklin Feng

2013-07-10

355

Pulsed laser deposited metal oxide thin films mediated controlled adsorption of proteins  

NASA Astrophysics Data System (ADS)

Several metal oxide thin films were grown on Si substrate by pulsed laser deposition for controlling adsorption of proteins. No intentional heating of substrate and introduction of oxygen gas during growth were employed. Additionally, fibrinogen, bovine serum albumin (BSA), and lysozyme were used as model protein in this study. The film properties such as cyratllinity, surface roughness, surface electrical charge and chemistry were investigated by many techniques in order to obtain the relationship with protein adsorption. Firstly, as grown Ta2O5 and ZnO thin film were used to study the effects of surface charge on the behaviors of BSA and lysozyme adsorption. The protein thickness results by ellipsometry showed that negatively charged Ta2O5 had a stronger affinity to positively charged lysozyme, while positively charged ZnO had a stronger affinity to negatively charged BSA. The results confirmed electrostatic interaction due to surface charge is one of main factors for determining adsorption of proteins. Furthermore, annealing studies were performed by heat treatment of as grown Ta2O5 and ZnO at 800°C in air ambience. Annealed Ta2O5 thin film had almost wetting property (from 10.02° to less than 1˜2°) and the change of cystallinity (from amorphous to cyrsalline) while annealed ZnO thin film had a reduced contact angle (from 75.65° to 39.41°) and remained to crystalline structure. The fibrinogen thickness on annealed Ta2O5 film was increased compared with as grown sample, while heat treated ZnO film showed much reduction of fibrinogen adsorption. Binary Ta-Zn oxide thin films (TZ) were grown by preparing PLD target composed of 50 wt% Ta2O5 and 50 wt% ZnO. This binary film had IEP pH 7.1 indicating nearly neutral charge in pH 7.4 PBS solution, and hydrophilic property. Ellipsometrical results showed that TZ film had the lowest fibrinogen, BSA and lysozyme thickness after 120 min adsorption compared with Ta2O5 and ZnO. Other samples, bilayer oxide films in which Ta2O5 and ZnO coexist were also employed to study adsorption behaviors. Especially, Ta2O 5-based bilayer films revealed zero adsorption of lysozyme.

Kim, Se Jin

356

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

357

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.

358

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

359

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

360

Fabrication of Porous Metal Oxide Semiconductor Films by a Self-Template Method Using Layered Hydroxide Metal Acetates  

Microsoft Academic Search

Porous metal oxide (Co3O4, NiO, or ZnO) films were fabricated by a self-template method using layered hydroxide metal acetates (LHMA; metal = Co, Ni, or Zn) as templates. LHMAs were initially grown on glass substrates through a chemical bath deposition in methanolic-aqueous solutions of metal acetates at 60°C. The template films had a unique, nest-like morphology consisting of interlaced flake-like

Shinobu Fujihara; Eiji Hosono; Toshio Kimura

2004-01-01

361

The neutronic and fuel cycle performance of interchangeable 3500 MWth metal and oxide fueled LMRs  

SciTech Connect

This study summarizes the neutronic and fuel cycle analysis performed at Argonne National Laboratory for an oxide and a metal fueled 3500 MWth LMR. The oxide and metal core designs were developed to meet reactor performance specifications that are constrained by requirements for core loading interchangeability and for small burnup reactivity swing. Differences in the computed performance parameters of the oxide and metal cores, arising from basic differences in their neutronic characteristics, were identified and discussed. It is shown that metal and oxide cores designed to the same ground rules exhibit many similar performance characteristics; however, they differ substantially in reactivity coefficients, control strategies, and fuel cycle options. 12 refs., 25 figs.

Fujita, E.K.; Wade, D.C.

1989-03-01

362

Photoelectron spectroscopic studies on the electronic structures of transition metal clusters and transition metal oxide clusters  

NASA Astrophysics Data System (ADS)

Photoelectron spectroscopic (PES) studies have been conducted on the bare transition metal clusters: Tin/ (n = 1~65),/ Vn/ (n = 1~70),/ Crn/ (n = 1~70),/ Fen/ (n = 1~33), Con/ (n = 1~51) and Nin/ (n = 1~50). The PES spectra of these clusters are taken at several detachment photon energies ranging from the second harmonic (532 nm) to fourth harmonic (266 nm) of the YAG laser and the 193 nm from an ArF excimer laser. Transition metals are very important catalysis elements; the photoelectron spectroscopic studies on the clusters provide a powerful tool for us to understand the metal- metal bonding and their electronic structures atom by atom. The electronic structure of titanium clusters is found to become bulk-like at relative small cluster sizes. It is observed that the 3d band emerges at the eight-atom cluster beyond which the d-band broadens and evolves toward that of the bulk. The vanadium clusters show three regions of spectral evolution: molecular behavior for n = 3-12; transition from molecular to bulk- like for n = 13-17; gradual convergence to bulk for n > 17, for which a surface-like feature is observed to slowly merge into the bulk feature near n = 60. Even-odd alternations are observed in the photoelectron spectra of small Crn clusters. Density functional calculations reveal a unique dimer growth route for chromium clusters up to Cr11, at which a structural transition occurs from the dimer growth to a bulklike body-centered-cubic structure. The PES spectra of the ferromagnetic metal clusters (Fen,/ Con, and Nin) reveal interesting relationships among the electronic structures and reactivity, geometric and magnetic properties, respectively. Photoelectron spectroscopic studies on the transition metal oxide clusters are also conducted. The study on the novel molecules Mx,/ Oy, (M = Ti, V, Cr, Fe, Cu, and Ni) shows the sequential oxidation behavior of the transition metals. Information about the structures and chemical bonding of these oxide molecules is also obtained.

Wu, Hongbin

363

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

364

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

365

Dual Environment Effects on the Oxidation of Metallic Interconnects  

SciTech Connect

Metallic interconnects in solid oxide fuel cells are exposed to a dual environment: fuel on one side (i.e. H2 gas) and oxidizer on the other side (i.e. air). It has been observed that the oxidation behavior of thin stainless steel sheet in air is changed by the presence of H2 on the other side of the sheet. The resulting dual environment scales are flaky and more friable than the single environment scales. The H2 disrupts the scale on the air-side. A model to explain some of the effects of a dual environment is presented where hydrogen diffusing through the stainless steel sheet reacts with oxygen diffusing through the scale to form water vapor, which has sufficient vapor pressure to mechanically disrupt the scale. Experiments on preoxidized 316L stainless steel tubing exposed to air/air, H2/air, and H2/Ar environments are reported in support of the model.

Holcomb, Gordon R.; Ziomek-Moroz, Malgorzata; Cramer, Stephen D.; Covino, Jr., Bernard S.; and Bullard, Sophie J.

2004-10-20

366

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 (Y2O3). 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 Y2O3 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 Y2O3 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, Africa; Guisande, Cástor; Barreiro, Aldo

2014-11-01

367

Uniform doping of metal oxide nanowires using solid state diffusion.  

PubMed

The synthesis of one-dimensional nanostructures with specific properties is often hindered by difficulty in tuning the material composition without sacrificing morphology and material quality. Here, we present a simple solid state diffusion method utilizing atomic layer deposition to controllably alter the composition of metal oxide nanowires. This compositional control allows for modification of the optical, electronic, and electrochemical properties of the semiconductor nanowires. Using this method and a novel process for manganese oxide atomic layer deposition, we produced manganese-doped rutile TiO2 nanowires and investigated their structural and photoelectrochemical properties. A homogeneous incorporation of the Mn dopant into the rutile lattice was observed, and the local chemical environment of the Mn was determined using X-ray absorption spectroscopy. The doping process resulted in a tunable enhancement in the electrocatalytic activity for water oxidation, demonstrating that this simple and general method can be used to control the properties of one-dimensional nanostructures for use in a variety of applications including solar-to-fuel generation. PMID:25026188

Resasco, Joaquin; Dasgupta, Neil P; Rosell, Josep Roque; Guo, Jinghua; Yang, Peidong

2014-07-23

368

Synthesis of transition-metal phosphides from oxidic precursors by reduction in hydrogen plasma  

SciTech Connect

A series of transition metal phosphides, including MoP, WP, CoP, Co{sub 2}P, and Ni{sub 2}P, were synthesized from their oxidic precursors by means of hydrogen plasma reduction under mild conditions. The effects of reduction conditions, such as metal to phosphorus molar ratio, power input, and reduction time, on the synthesis of metal phosphides were investigated. The products were identified by means of XRD characterization. It is indicated that metal phosphides were readily synthesized stoichiometrically from their oxides in hydrogen plasma under mild conditions. - Graphical abstract: Metal phosphides were obtained stoichiometrically from their oxidic precursors by hydrogen plasma reaction under mild conditions.

Guan Jie [Department of Catalytic Chemistry and Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Wang Yao [Liaoning Key Laboratory of Petrochemical Technology and Equipments, Dalian University of Technology, Dalian 116012 (China); Qin Minglei; Yang Ying [Department of Catalytic Chemistry and Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Li Xiang [Department of Catalytic Chemistry and Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Liaoning Key Laboratory of Petrochemical Technology and Equipments, Dalian University of Technology, Dalian 116012 (China); Wang Anjie, E-mail: ajwang@dlut.edu.c [Department of Catalytic Chemistry and Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Liaoning Key Laboratory of Petrochemical Technology and Equipments, Dalian University of Technology, Dalian 116012 (China)

2009-06-15

369

THE SIZE AND ORIGIN OF METAL-ENRICHED REGIONS IN THE INTERGALACTIC MEDIUM FROM SPECTRA OF BINARY QUASARS  

SciTech Connect

We present tomography of the circum-galactic metal distribution at redshift 1.7-4.5 derived from echellete spectroscopy of binary quasars. We find C IV systems at similar redshifts in paired sightlines more often than expected for sightline-independent redshifts. As the separation of the sightlines increases from 36 kpc to 907 kpc, the amplitude of this clustering decreases. At the largest separations, the C IV systems cluster similar to the Lyman-break galaxies studied by Adelberger et al. in 2005. The C IV systems are significantly less correlated than these galaxies, however, at separations less than R{sub 1} {approx_equal} 0.42 {+-} 0.15 h {sup -1} comoving Mpc. Measured in real space, i.e., transverse to the sightlines, this length scale is significantly smaller than the break scale estimated previously from the line-of-sight correlation function in redshift space by Scannapieco et al. in 2006. Using a simple model, we interpret the new real-space measurement as an indication of the typical physical size of enriched regions. We adopt this size for enriched regions and fit the redshift-space distortion in the line-of-sight correlation function. The fitted velocity kick is consistent with the peculiar velocity of galaxies as determined by the underlying mass distribution and places an upper limit on the average outflow (or inflow) speed of metals. The implied timescale for dispersing metals is larger than the typical stellar ages of Lyman-break galaxies, and we argue that enrichment by galaxies at z {>=} 4.3 played a greater role in dispersing metals. To further constrain the growth of enriched regions, we discuss empirical constraints on the evolution of the C IV correlation function with cosmic time. This study demonstrates the potential of tomography for measuring the metal enrichment history of the circum-galactic medium.

Martin, Crystal L.; Fournier, Amanda P. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, V8P 1A1 (Canada); Hennawi, Joseph F. [Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720-3411 (United States); Djorgovski, S. G., E-mail: cmartin@physics.ucsb.ed [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

2010-09-20

370

Synthesis and characterization of hierarchically porous metal, metal oxide, and carbon monoliths with highly ordered nanostructure  

NASA Astrophysics Data System (ADS)

Hierarchically porous materials are of great interest in such applications as catalysis, separations, fuel cells, and advanced batteries. One such way of producing these materials is through the process of nanocasting, in which a sacrificial template is replicated and then removed to form a monolithic replica. This replica consists of mesopores, which can be ordered or disordered, and bicontinuous macropores, which allow flow throughout the length of the monolith. Hierarchically porous metal oxide and carbon monoliths with an ordered mesopores system are synthesized for the first time via nanocasting. These replicas were used as supports for the deposition of silver particles and the catalytic efficiency was evaluated. The ordered silica template used in producing these monoliths was also used for an in-situ TEM study involving metal nanocasting, and an observation of the destruction of the silica template during nanocasting made. Two new methods of removing the silica template were developed and applied to the synthesis of copper, nickel oxide, and zinc oxide monoliths. Finally, hollow fiber membrane monoliths were examined via x-ray tomography in an attempt to establish the presence of this structure throughout the monolith.

Grano, Amy Janine

371

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

372

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

373

Resonant Ultrasound Studies of Complex Transition Metal Oxides  

SciTech Connect

Department of Energy EPSCoR The University of Mississippi Award: DE-FG02-04ER46121 Resonant Ultrasound Spectroscopy Studies of Complex Transition Metal Oxides The central thrust of this DOE funded research program has been to apply resonant ultrasound spectroscopy (RUS), an elegant and efficient method for determining the elastic stiffness constants of a crystal, to the complex and poorly understood class of materials known as transition metal oxides (TMOs). Perhaps the most interesting and challenging feature of TMOs is their strongly correlated behavior in which spin, lattice, and charge degrees of freedom are strongly coupled. Elastic constants are a measure of the interatomic potentials in a crystal and are thus sensitive probes into the atomic environment. This sensitivity makes RUS an ideal tool to study the coupling of phase transition order parameters to lattice strains. The most significant result of the project has been the construction of a high temperature RUS apparatus capable of making elastic constant measurements at temperatures as high as 1000 degrees Celsius. We have designed and built novel acoustic transducers which can operate as high as 600 degrees Celsius based on lithium niobate piezoelectric elements. For measurement between 600 to 1000 C, a buffer rod system is used in which the samples under test and transducers are separated by a rod with low acoustic attenuation. The high temperature RUS system has been used to study the charge order (CO) transition in transition metal oxides for which we have discovered a new transition occurring about 35 C below the CO transition. While the CO transition exhibits a linear coupling between the strain and order parameter, this new precursor transition shows a different coupling indicating a fundamentally different mechanism. We have also begun a study, in collaboration with the Jet Propulsion Laboratory, to study novel thermoelectric materials at elevated temperatures. These materials include silicon germanium with various doping and Zintl phase materials. Such materials show promise for increased figures of merit, vital to making thermolectrics competitive with traditional power generation mechanisms.

Dr. Henry Bass; Dr. J. R. Gladden

2008-08-18

374

Infinitely high selective inductively coupled plasma etching of an indium tin oxide binary mask structure for extreme ultraviolet lithography  

SciTech Connect

Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics with a completely different configuration than those of conventional photolithography. This study investigated the etching properties of indium tin oxide (ITO) binary mask materials for EUVL, such as ITO (absorber layer), Ru (capping/etch-stop layer), and a Mo-Si multilayer (reflective layer), by varying the Cl{sub 2}/Ar gas flow ratio, dc self-bias voltage (V{sub dc}), and etch time in inductively coupled plasmas. The ITO absorber layer needs to be etched with no loss in the Ru layer on the Mo-Si multilayer for fabrication of the EUVL ITO binary mask structure proposed here. The ITO layer could be etched with an infinitely high etch selectivity over the Ru etch-stop layer in Cl{sub 2}/Ar plasma even with a very high overetch time.

Park, Y. R.; Ahn, J. H.; Kim, J. S.; Kwon, B. S.; Lee, N.-E.; Kang, H. Y.; Hwangbo, C. K.; Ahn, Jinho; Seo, Hwan Seok [School of Advanced Materials Science and Engineering, Center for Human Interface Nanotechnology, and Center for Advanced Plasma Surface Technology, Sungkyunkwan University, 300 Chunchun-dong, Suwon, Kyunggi-do 440-746 (Korea, Republic of); Department of Physics, Inha University, Yonghyen-dong, Nam-gu, Incheon 402-751 (Korea, Republic of); Department of Materials Science and Engineering, Hanyang University, Seoul 133-792 (Korea, Republic of); Photomask Team, Memory Division, Semiconductor Business, Samsung Electronics Co., Ltd., Banwol-dong, Hwaseong, Kyunggi-do 445-701 (Korea, Republic of)

2010-07-15

375

Role of metal oxides in the thermal degradation of poly(vinyl chloride)  

SciTech Connect

Thermal degradation of poly(vinyl chloride) has been studied in the presence of metal oxides by a thermogravimetric method. It follows a two-step mechanism. In the first step chlorine free radical is formed as in the case of pure PVC, and in the second step chlorine free radical replaces oxygen from metal oxide to form metal chloride and oxygen free radical. Subsequently, the oxygen free radical abstracts hydrogen from PVC. Formation of metal chloride is the rate-controlling step. The metal chlorides formed during the thermal degradation either volatilize or decompose simultaneously to lower metallic chlorides depending on the boiling point or the volatilization temperature.

Gupta, M.C.; Viswanath, S.G. [Nagpur Univ. (India)] [Nagpur Univ. (India)

1998-07-01

376

A general procedure to synthesize highly crystalline metal oxide and mixed oxide nanocrystals in aqueous medium and photocatalytic activity of metal/oxide nanohybrids.  

PubMed

A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxide nanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO(4), La(2)(MoO(4))(3) can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO(4), La(2)(MoO(4))(3)) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxide nanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO(2) nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied. PMID:21409273

Nguyen, Thanh-Dinh; Dinh, Cao-Thang; Do, Trong-On

2011-04-01

377

Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles  

Microsoft Academic Search

The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol–gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol–gel routes, followed

Igor Djerdj; Denis Arcon; Zvonko Jaglicic; Markus Niederberger

2008-01-01

378

Integration of Metal Oxide Nanowires in Flexible Gas Sensing Devices  

PubMed Central

Metal oxide nanowires are very promising active materials for different applications, especially in the field of gas sensors. Advances in fabrication technologies now allow the preparation of nanowires on flexible substrates, expanding the potential market of the resulting sensors. The critical steps for the large-scale preparation of reliable sensing devices are the elimination of high temperatures processes and the stretchability of the entire final device, including the active material. Direct growth on flexible substrates and post-growth procedures have been successfully used for the preparation of gas sensors. The paper will summarize the procedures used for the preparation of flexible and wearable gas sensors prototypes with an overlook of the challenges and the future perspectives concerning this field. PMID:23955436

Comini, Elisabetta

2013-01-01

379

In situ study of noncatalytic metal oxide nanowire growth.  

PubMed

The majority of the nanowire synthesis methods utilize catalyst particles to guide the nanowire geometry. In contrast, catalyst-free methods are attractive for facile fabrication of pure nanowires without the need for catalyst preparation. Nonetheless, how nanowire growth is guided without a catalyst is still widely disputed and unclear. Here, we show that the nanowire growth during metal oxidation is limited by a nucleation of a new layer. On the basis of in situ transmission electron microscope investigations we found that the growth occurs layer by layer at the lowest specific surface energy planes. Atomic layers nucleate at the edge of twin boundary ridges and form a long-range ordering along the twin boundary. We anticipate our study to be a starting point to employ defects for nanowire growth control and consequently shaping the geometry of nanowires in a similar manner as in the catalyst-assisted growth method. PMID:25233273

Rackauskas, Simas; Jiang, Hua; Wagner, Jakob B; Shandakov, Sergey D; Hansen, Thomas W; Kauppinen, Esko I; Nasibulin, Albert G

2014-10-01

380

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

381

Energetic Surface Smoothing of Complex Metal-Oxide Thin Films  

SciTech Connect

A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of La{sub 1-x}Sr{sub x}MnO{sub 3} on SrTiO{sub 3}, using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the formation of large-diameter 2D islands and the seeding of 3D growth. Above 50% coverage, islands begin to coalesce and their breakup is thereby suppressed. The energy of the incident flux is instead rechanneled into enhanced surface diffusion, which leads to an increase in the effective surface temperature of {delta}T{approx_equal}500 K. These results have important implications on optimal conditions for nanoscale device fabrication using these materials.

Willmott, P.R.; Herger, R.; Schlepuetz, C.M.; Martoccia, D.; Patterson, B.D. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

2006-05-05

382

Energetic surface smoothing of complex metal-oxide thin films.  

PubMed

A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of on , using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the formation of large-diameter 2D islands and the seeding of 3D growth. Above 50% coverage, islands begin to coalesce and their breakup is thereby suppressed. The energy of the incident flux is instead rechanneled into enhanced surface diffusion, which leads to an increase in the effective surface temperature of DeltaT approximately 500 K. These results have important implications on optimal conditions for nanoscale device fabrication using these materials. PMID:16712314

Willmott, P R; Herger, R; Schlepütz, C M; Martoccia, D; Patterson, B D

2006-05-01

383

Metal oxide morphology in argon-assisted glancing angle deposition  

SciTech Connect

Glancing angle deposition (GLAD) is a thin film deposition technique capable of fabricating columnar architectures such as posts, helices, and chevrons with control over nanoscale film features. Argon bombardment during deposition modifies the GLAD process, producing films with new morphologies which have shown promise for sensing and photonic devices. The authors report modification of column tilt angle, film density, and specific surface area for 12 different metal oxide and fluoride film materials deposited using Ar-assisted GLAD. For the vapor flux/ion beam geometry and materials studied here, with increasing argon flux, the column tilt increases, film density increases, and specific surface area decreases. With a better understanding of the nature of property modification and the mechanisms responsible, the Ar-assisted deposition process can be more effectively targeted towards specific applications, including birefringent thin films or photonic crystal square spirals.

Sorge, J. B.; Taschuk, M. T.; Wakefield, N. G.; Sit, J. C.; Brett, M. J. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4 (Canada); Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4 (Canada) and NRC National Institute for Nanotechnology, Edmonton, AB T6G 2M9 (Canada)

2012-03-15

384

Synthesis, characterization and catalytic application of nanoscale metal and metal oxide heterogeneous catalysts  

NASA Astrophysics Data System (ADS)

Nanoscale metals or metal oxides with high surface area to volume ratios have been widely used as catalysts for various chemical reactions. A major challenge to utilize metal nanocatalysts commercially is their tendency to sinter under working reaction conditions. To overcome this, much research is being done to anchor metal nanocatalysts on various supports to prevent their agglomeration. Mesoporous silica, SBA-15 is an attractive support material candidate because of its high surface area, stable structure and chemical inertness. Scientists have anchored metal nanocatalysts onto the pore of SBA-15 and observed some improvement in the stability. However, the interactions between the nanocatalysts and SBA-15 are relatively weak and sintering still occurs resulting in a loss of activity. In order to impart enhanced robustness, a new type of stable metal/SBA-15 nanocomposite has been prepared by intercalating metal nanoparticles into the walls of mesoporous silica SBA-15 by a unique synthetic strategy using metal coordinating agents such as bis[3-(triethoxysilyl) propyl]-tetrasulfide (TESPTS). In this dissertation, systemic research on the preparation parameters and extension to other metals will be presented. The structure changes caused by addition of TESPTS to the preparation of mesoporous silica were investigated. The relationship between increasing amounts of TESPTS and the structural change was obtained. Afterwards, a new type of PdMS catalyst with Pd intercalated in the walls of SBA-15 was synthesized for the first time using a modified preparation pathway. These materials were characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy and inductively coupled plasma. The PdMS system was utilized as an active and robust catalyst for Heck reactions. Notably, after the catalytic reaction, the PdMS catalysts maintained its reactivity and size without undergoing any agglomeration due to the stable nanocomposite structure. Carbon disulfide (CS2) was used to poison the catalyst to determine the relative number of active sites for the reduction of 4-nitrophenol. Moreover, the novel PdMS catalyst is recyclable and shows excellent stability after exposure to elevated temperatures. Additional, tentative PtMS and AgMS are synthesized based on the PdMS protocol. Besides, shape-controlled Pd nanocrystals are prepared aiming at to be intercalated into the wall of mesoporous silica and used as catalysts with certain selectivity.

Wang, Xue

385

Precursor directed synthesis - ``molecular'' mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures  

NASA Astrophysics Data System (ADS)

This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials. To Professor David Avnir on his 65th birthday.

Seisenbaeva, Gulaim A.; Kessler, Vadim G.

2014-05-01

386

Controllably Interfacing with Metal: A Strategy for Enhancing CO Oxidation on Oxide Catalysts by Surface Polarization.  

PubMed

Heterogeneous catalysis often involves charge transfer from catalyst surface to adsorbed molecules, whose activity thus depends on the surface charge density of catalysts. Here, we demonstrate a unique solution-phase approach to achieve controllable interfacial lengths in oxide-metal hybrid structures. Resulting from their different work functions, surface polarization is induced by the Ag-CuO interface and acts to tailor the surface charge state of CuO. As a result, the designed hybrid catalysts exhibit enhanced intrinsic activities in catalyzing CO oxidation in terms of apparent activation energy, as compared with their counterparts. Moreover, the CO conversion rate can be enhanced by maximizing the Ag-CuO interfacial length and thus the number of active sites on the CuO. This work provides a new strategy for tuning catalytic performance by controlling interface in hybrid catalysts. PMID:25296380

Bai, Yu; Zhang, Wenhua; Zhang, Zhenhua; Zhou, Jie; Wang, Xijun; Wang, Chengming; Huang, Weixin; Jiang, Jun; Xiong, Yujie

2014-10-22

387

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

388

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...

389

Nano and micro stripe based metal oxide thin film gas sensor  

Microsoft Academic Search

Functional metal oxide micro and nanostructures for the detection of gas are a very promising candidate for future gas-sensors. Due to reduced size and thus an increased surface to volume ratio nanosized sensitive structures offer a high potential for increasing sensitivity. A top down sputtering approach for gas sensors with nano-sized gas sensitive metal oxide areas is presented. Oxidised silicon

Stefan Palzer; Emmanuel Moretton; Francisco Hernandez Ramirez; Albert Romano-Rodriguez; Juan Ramon Morante; Jürgen Wöllenstein

2007-01-01

390

Gas discrimination by ZnO nanowire arrays with different metal oxide coatings  

Microsoft Academic Search

Three-dimensional (3D) metal oxide nanowire arrays have large surface area and numerous gas transport channels, which can significantly improve the gas sensing performance, such as sensitivity, response and recovery speed, etc. compared to their thin films counterparts. Furthermore, different metal oxide coatings can be used to diversify the chemical reactivity of the nanowires for gas discrimination. A general route to

Jiajun Chen; Haiqiao Su; Weilie Zhou

2011-01-01

391

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

SciTech Connect

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 with a consideration of the structure (both geometric and electronic) and properties of clean metal oxide surfaces (section 2). Section 3 considers the interaction of water vapor with metal oxide surfaces. The largest section of the paper, section 4, addresses the interactions that occur when metal oxides are immersed in liquid water. The dissolution and growth of metal oxides in aqueous solutions are addressed in section 5. Section 6 considers biotic processes involving bacterial utilization and production of metal oxides. The various theoretical approaches that are being used to interpret and predict the structure and properties of metal oxide-aqueous interfaces are described in section 7. Section 8 then considers the challenges that face this emerging field and the future directions in which research must go if answers to the important unanswered questions are to be obtained. 600 refs.

Brown, G.E. Jr. [Stanford Univ., CA (United States)] [Stanford Univ., CA (United States); Henrich, V.E. [Yale Univ., New Haven, CT (United States)] [Yale Univ., New Haven, CT (United States); Casey, W.H. [Univ. of California, Davis, CA (United States). Dept. of Land, Air, and Water Resources] [and others] [Univ. of California, Davis, CA (United States). Dept. of Land, Air, and Water Resources; and others

1999-01-01

392

Mechanisms of Zinc Oxide Nanocrystalline Thin Film Formation by Thermal Degradation of Metal-Loaded Hydrogels  

E-print Network

,7 Deposition of thin films of ZnO and of other metal oxides represents a key step in most-organic vapor phase epitaxy have proved to be effective in the deposition of high quality thin films of ZnOMechanisms of Zinc Oxide Nanocrystalline Thin Film Formation by Thermal Degradation of Metal

393

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; Aksay, Ilhan A; Choi, Daiwon; Kou, Rong; Nie, Zimin; Wang, Donghai; Yang, Zhenguo

2013-10-22

394

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

395

Highly Sensitive and Selective Gas Sensors Based on Vertically Aligned Metal Oxide Nanowire Arrays  

Microsoft Academic Search

Mimicking the biological olfactory systems that consist of olfactory receptor arrays with large surface area and massively-diversified chemical reactivity, three dimensional (3D) metal oxide nanowire arrays were used as the active materials for gas detection. Metal oxide nanowire arrays share similar 3D structures as the array of mammal's olfactory receptors and the chemical reactivity of nanowire array can be modified

Jiajun Chen

2010-01-01

396

Atomistic study of metal clusters supported on oxide surface  

NASA Astrophysics Data System (ADS)

Metal clusters on oxide surface are a widely studied topic in surface science and technology. In this work, we use the ab initio based pair potentials to study the shape evolution of these clusters with their width from 3 Å to 90 Å. The clusters have a basic polyhedron shape covered by (0 0 1) and (1 1 1) faces, with four undetermined parameters. The main purpose of this work is to determine the structure parameters numerically. Here, we use a combination of energy minimization calculation, least square method and Lagrange multiplier method, and go through a series of metals including Ag, Al, Au, Pd and Rh. As a result, we find that these clusters have a truncated octahedron structure on MgO(0 0 1) surface, with a square contact face for Ag, Al and Au, and an octagon one for Pd and Rh. Also, we see that misfit dislocation appears when the cluster becomes large, first at the edge, then inside the contact area.

Long, Y.; Chen, N. X.

397

Materials discovery by crystal growth: Lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt) from molten alkali metal hydroxides  

SciTech Connect

This review addresses the process of materials discovery via crystal growth, specifically of lanthanide metal containing oxides of the platinum group metals (Ru, Os, Ir, Rh, Pd, Pt). It provides a detailed overview of the use of hydroxide fluxes for crystal growth. The melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals are described. Furthermore, a general methodology for the successful crystal growth of oxides is provided, including a discussion of experimental considerations, suitable reaction vessels, reaction profiles and temperature ranges. Finally, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts, focusing on their crystal growth and crystal structures, is included. - Graphical abstract: A review that addresses the process of materials discovery via crystal growth using hydroxide fluxes. It provides a detailed overview of the use of hydroxide fluxes for crystal growth and describes the melt chemistry of hydroxide fluxes, specifically, the extensive acid base chemistry, the metal cation solubility, and the ability of hydroxide melts to oxidize metals. In addition, a compilation of complex platinum group metal oxides recently synthesized using hydroxide melts is included.

Mugavero, Samuel J.; Gemmill, William R.; Roof, Irina P. [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States); Loye, Hans-Conrad zur, E-mail: zurloye@mail.chem.sc.ed [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States)

2009-07-15

398

Heterostructure P-channel metal-oxide-semiconductor transistor utilizing a Si1-x-yGexCy channel  

NASA Astrophysics Data System (ADS)

The dc characteristics of Si1-x-yGexCy P-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) were evaluated between room temperature and 77 K and were compared to those of Si and Si1-xGex PMOSFETs. The low-field effective mobility in Si1-x-yGexCy devices is found to be higher than that of Si1-xGex (grown in the metastable regime) and Si devices at low gate bias and room temperature. However, with increasing transverse fields and with decreasing temperatures, Si1-x-yGexCy devices show degraded performance. The enhancement at low gate bias is attributed to the strain stabilization effect of C. This application of Si1-x-yGexCy in PMOSFETs demonstrates potential benefits in the use of C for strain stabilization of the binary alloy.

John, S.; Ray, S. K.; Quinones, E.; Oswal, S. K.; Banerjee, S. K.

1999-02-01

399

The friction and wear of metals and binary alloys in contact with an abrasive grit of single-crystal silicon carbide  

NASA Technical Reports Server (NTRS)

Sliding friction experiments were conducted with various metals and iron-base binary alloys (alloying elements Ti, Cr, Mn, Ni, Rh and W) in contact with single crystal silicon carbide riders. Results indicate that the friction force in the plowing of metal and the groove height (corresponding to the wear volume of the groove) decrease linearly as the shear strength of the bulk metal increases. The coefficient of friction and groove height generally decrease, and the contact pressure increases with an increase in solute content of binary alloys. There appears to be very good correlation of the solute to iron atomic ratio with the decreasing rate of change of coefficient of friction, the decreasing rate of change of groove height and the increasing rate of change of contact pressure with increasing solute content. These rates of change increase as the solute to iron atomic radius ratio increases or decreases from unity.

Miyoshi, K.; Buckley, D. H.

1979-01-01

400

Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes  

SciTech Connect

Photoelectrochemical (PEC) water splitting to hydrogen is an attractive method for capturing and storing the solar energy in the form of chemical energy. Metal oxides are promising photoanode materials due to their low-cost synthetic routes and higher stability than other semiconductors. In this paper, we provide an overview of recent efforts to improve PEC efficiencies via applying a variety of fabrication strategies to metal oxide photoanodes including (i) size and morphology-control, (ii) metal oxide heterostructuring, (iii) dopant incorporation, (iv) attachments of quantum dots as sensitizer, (v) attachments of plasmonic metal nanoparticles, and (vi) co-catalyst coupling. Each strategy highlights the underlying principles and mechanisms for the performance enhancements.

Cho, Seungho [Department of Chemistry and Pohang University of Science and Technology (POSTECH), San 31, Hyoja-Dong, Nam-Gu, Pohang, Gyungbuk 790–784 (Korea, Republic of); Jang, Ji-Wook; Lee, Kun-Hong, E-mail: jlee1234@unist.ac.kr, E-mail: ce20047@postech.ac.kr [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-Dong, Nam-Gu, Pohang, Gyungbuk 790–784 (Korea, Republic of); Lee, Jae Sung, E-mail: jlee1234@unist.ac.kr, E-mail: ce20047@postech.ac.kr [School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 689–798 (Korea, Republic of)

2014-01-01

401

Method of making metal oxide ceramic membranes with small pore sizes  

DOEpatents

A method for the production of metal oxide ceramic membranes is composed 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

402

Binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and these pharmaceuticals in isolated form induce oxidative stress on Hyalella azteca.  

PubMed

Toxicity in natural ecosystems is usually not due to exposure to a single substance, but is rather the result of exposure to mixtures of toxic substances. Knowing the effects of contaminants as a mixture compared to their effects in isolated form is therefore important. This study aimed to evaluate the oxidative stress induced by binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and by these nonsteroidal anti-inflammatory drugs (NSAIDs) in isolated form, using Hyalella azteca as a bioindicator. The median lethal concentration (LC50) and the lowest observed adverse effect level (LOAEL) of each NSAID were obtained. Amphipods were exposed for 72 h to the latter value in isolated form and as binary mixtures. The following biomarkers were evaluated: lipid peroxidation (LPX), protein carbonyl content (PCC), and activity of the antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Significant increases in LPX and PCC with respect to the control group (p???0.05) were induced by NSAIDs both in isolated form and as binary mixtures. Changes in SOD, CAT, and GPx activity likewise occurred with NSAIDs in isolated form and as binary mixtures. In conclusion, NSAIDs used in this study induce oxidative stress on H. azteca both in isolated form and as binary mixtures, and the interactions occurring between these pharmaceuticals are probably antagonistic in type. PMID:25004860

Gómez-Oliván, Leobardo Manuel; Neri-Cruz, Nadia; Galar-Martínez, Marcela; Islas-Flores, Hariz; García-Medina, Sandra

2014-11-01

403

Noble metal nanoparticle@metal oxide core/yolk-shell nanostructures as catalysts: recent progress and perspective.  

PubMed

Controllable integration of noble metals (e.g., Au, Ag, Pt, and Pd) and metal oxides (e.g., TiO?, CeO?, and ZrO?) into single nanostructures has attracted immense research interest in heterogeneous catalysis, because they not only combine the properties of both noble metals and metal oxides, but also bring unique collective and synergetic functions in comparison with single-component materials. Among many strategies recently developed, one of the most efficient ways is to encapsulate and protect individual noble metal nanoparticles by a metal oxide shell of a certain thickness to generate the core-shell or yolk-shell structure, which exhibits enhanced catalytic performance compared with conventional supported catalysts. In this review article, we summarize the state-of-the art progress in synthesis and catalytic application of noble metal nanoparticle@metal oxide core/yolk-shell nanostructures. We hope that this review will help the readers to obtain better insight into the design and application of well-defined nanocomposites in both the energy and environmental fields. PMID:24622876

Li, Guodong; Tang, Zhiyong

2014-04-21

404

Noble metal nanoparticle@metal oxide core/yolk-shell nanostructures as catalysts: recent progress and perspective  

NASA Astrophysics Data System (ADS)

Controllable integration of noble metals (e.g., Au, Ag, Pt, and Pd) and metal oxides (e.g., TiO2, CeO2, and ZrO2) into single nanostructures has attracted immense research interest in heterogeneous catalysis, because they not only combine the properties of both noble metals and metal oxides, but also bring unique collective and synergetic functions in comparison with single-component materials. Among many strategies recently developed, one of the most efficient ways is to encapsulate and protect individual noble metal nanoparticles by a metal oxide shell of a certain thickness to generate the core-shell or yolk-shell structure, which exhibits enhanced catalytic performance compared with conventional supported catalysts. In this review article, we summarize the state-of-the art progress in synthesis and catalytic application of noble metal nanoparticle@metal oxide core/yolk-shell nanostructures. We hope that this review will help the readers to obtain better insight into the design and application of well-defined nanocomposites in both the energy and environmental fields.

Li, Guodong; Tang, Zhiyong

2014-03-01

405

New Perspectives on Oxidized Genome Damage and Repair Inhibition by Pro-Oxidant Metals in Neurological Diseases  

PubMed Central

The primary cause(s) of neuronal death in most cases of neurodegenerative diseases, including Alzheimer’s and Parkinson’s disease, are still unknown. However, the association of certain etiological factors, e.g., oxidative stress, protein misfolding/aggregation, redox metal accumulation and various types of damage to the genome, to pathological changes in the affected brain region(s) have been consistently observed. While redox metal toxicity received major attention in the last decade, its potential as a therapeutic target is still at a cross-roads, mostly because of the lack of mechanistic understanding of metal dyshomeostasis in affected neurons. Furthermore, previous studies have established the role of metals in causing genome damage, both directly and via the generation of reactive oxygen species (ROS), but little was known about their impact on genome repair. Our recent studies demonstrated that excess levels of iron and copper observed in neurodegenerative disease-affected brain neurons could not only induce genome damage in neurons, but also affect their repair by oxidatively inhibiting NEIL DNA glycosylases, which initiate the repair of oxidized DNA bases. The inhibitory effect was reversed by a combination of metal chelators and reducing agents, which underscore the need for elucidating the molecular basis for the neuronal toxicity of metals in order to develop effective therapeutic approaches. In this review, we have focused on the oxidative genome damage repair pathway as a potential target for reducing pro-oxidant metal toxicity in neurological diseases. PMID:25036887

Mitra, Joy; Guerrero, Erika N.; Hegde, Pavana M.; Wang, Haibo; Boldogh, Istvan; Rao, Kosagi Sharaf; Mitra, Sankar; Hegde, Muralidhar L.

2014-01-01

406

Using FISH-SIMS to Study Marine Methane Oxidation Coupled to the Reduction of Metal Oxides, a Plausible Microbial Metabolism for Subsurface Mars  

NASA Astrophysics Data System (ADS)

In the shallow martian subsurface, microbial life could be supported by methane oxidation coupled to the reduction of sulfate or metal oxides. Here, we report results of efforts to characterize the organisms involved in manganese-dependent marine methane oxidation.

House, C. H.; Beal, E. J.; Orphan, V. J.

2010-04-01

407

Novel hybrid materials for gas sensing applications made of metal-decorated MWCNTs dispersed on nano-particle metal oxides  

Microsoft Academic Search

Novel hybrid gas-sensitive materials were fabricated by means of metal-decorated multiwall carbon nanotubes (MWCNT) dispersed on nano-particle metal oxides. The MWCNT were initially functionalized in an oxygen plasma for improving their dispersion and surface reactivity, and then they were decorated with metal nano-clusters by thermally evaporating gold or silver on the MWCNT. Active layers for gas sensing applications were obtained

R. Ionescu; E. H. Espinosa; R. Leghrib; A. Felten; J. J. Pireaux; R. Erni; G. Van Tendeloo; C. Bittencourt; N. Cañellas; E. Llobet

2008-01-01

408

PREPARATION AND METALLIC REDUCTION OF RARE-EARTH HALIDES AND OXIDES  

Microsoft Academic Search

The development of techniques for the preparation of high-purity rare-; earth metals is described. Rare-earth metals, excepting samarium, europium, and ; ytterbium, were prepared by converting their oxides to anhydrous chlorides or ; fluorides and reducing the rare-earth halides with active metals such as lithium ; or calcium. High-purity, anhydrous rare-earth chlorides were prepared by ; dissolving the rare-earth oxides

T. T. Campbell; F. E. Block; R. E. Mussler; G. B. Robidart

1960-01-01

409

Electrical properties of metal-oxide semiconductor nano-particle device  

Microsoft Academic Search

We have studied the electrical transport properties of two types of devices utilizing metal-oxide semiconductor nano-particles, Cu2O and Fe2O3. The metal-oxide nano-particles are embedded in a polyimide matrix through chemical reaction between the metal thin film and polyamic acid as a precursor of polyimide. To test the electron tunneling via nano-particles, Au nano-electrodes are fabricated on a SiO2\\/Si substrate with

J. H. Kim; E. K. Kim; C. H. Lee; M. S. Song; Y.-H. Kim

2005-01-01

410

An exploratory program for using hydrous metal oxide ion exchangers as Fischer-Tropsch catalysts  

Microsoft Academic Search

The purpose of this program is to investigate the potential of hydrous metal oxide (HMO) ion exchangers, invented at Sandia National Laboratories, as Fischer-Tropsch (F-T) catalysts. Metals known to be active in F-T synthesis (e.g. Fe, Co) were ion exchanged on hydrous metal oxide supports. Although HMO catalysts based on Zr, Nb, and Ta have been investigated in direct coal

A. W. Lynch; R. G. Dosch; A. G. Sault

1990-01-01

411

Microfabricated gas sensor systems with sensitive nanocrystalline metal-oxide films  

Microsoft Academic Search

This article gives an overview on recent developments in metal-oxide-based gas sensor systems, in particular on nanocrystalline\\u000a oxide materials deposited on modern, state-of-the-art sensor platforms fabricated in microtechnology. First, metal-oxide-based\\u000a gas sensors are introduced, and the underlying principles and fundamentals of the gas sensing process are laid out. In the\\u000a second part, the different deposition methods, such as evaporation, sputtering,

M. Graf; A. Gurlo; N. Bârsan; U. Weimar; A. Hierlemann

2006-01-01

412

Activation of Supported Pd Metal Catalysts for Selective Oxidation of Hydrogen to Hydrogen Peroxide  

Microsoft Academic Search

Catalytic activity of supported Pd metal catalysts (Pd metal deposited on carbon, alumina, gallia, ceria or thoria) showing almost no activity in the liquid-phase direct oxidation of H2 to H2O2 (at 295 K) in acidic medium (0.02 M H2SO4) can be increased drastically by oxidizing them using different oxidizing agents, such as perchloric acid, H2O2, N2O and air. In the

Vasant R. Choudhary; Abaji G. Gaikwad; Subhash D. Sansare

2002-01-01

413

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/TiO2 catalysts has been prepared from precursors of various metal-organic gold complexes (Aun, n = 2 prepared from Aun (n = 2­4, number of gold atoms in the complex) metal-organic complexes together

Goodman, Wayne

414

Organofunctional Metal Oxide Clusters as Building Blocks for Inorganic-Organic Hybrid Materials  

Microsoft Academic Search

The controlled hydrolysis of metal alkoxides in the presence of methacrylic acid results in metal oxide clusters capped by polymerizable methacrylate ligands. Radical polymerization of small portions of such clusters with organic co-monomers allows the preparation of an interesting new type of inorganic-organic hybrid polymers in which the metal oxo clusters efficiently crosslink the organic polymers chains. SAXS investigations revealed

Ulrich Schubert

2004-01-01

415

ORIGINAL PAPER Influence of the Metal Oxide Substrate Structure on Vanadium  

E-print Network

ORIGINAL PAPER Influence of the Metal Oxide Substrate Structure on Vanadium Oxide Monomer Formation 2013 � Springer Science+Business Media New York 2013 Abstract Vanadium oxide (VOx) molecular species. This study demonstrates that the atomic structure of the support can strongly influence the molec- ular

Marks, Laurence D.

416

Process and apparatus for generating elemental sulfur and re-usable metal oxide from spent metal sulfide sorbents  

DOEpatents

A process and apparatus for generating elemental sulfur and re-usable metal oxide from spent metal-sulfur compound. Spent metal-sulfur compound is regenerated to re-usable metal oxide by moving a bed of spent metal-sulfur compound progressively through a single regeneration vessel having a first and second regeneration stage and a third cooling and purging stage. The regeneration is carried out and elemental sulfur is generated in the first stage by introducing a first gas of sulfur dioxide which contains oxygen at a concentration less than the stoichiometric amount required for complete oxidation of the spent metal-sulfur compound. A second gas containing sulfur dioxide and excess oxygen at a concentration sufficient for complete oxidation of the partially spent metal-sulfur compound, is introduced into the second regeneration stage. Gaseous sulfur formed in the first regeneration stage is removed prior to introducing the second gas into the second regeneration stage. An oxygen-containing gas is introduced into the third cooling and purging stage. Except for the gaseous sulfur removed from the first stage, the combined gases derived from the regeneration stages which are generally rich in sulfur dioxide and lean in oxygen, are removed from the regenerator as an off-gas and recycled as the first and second gas into the regenerator. Oxygen concentration is controlled by adding air, oxygen-enriched air or pure oxygen to the recycled off-gas.

Ayala, Raul E. (Clifton Park, NY); Gal, Eli (Lititz, PA)

1995-01-01

417

Oxidation Behavior of Chromium and a Chromium-Yttrium Binary Alloy.  

National Technical Information Service (NTIS)

The effect of an addition of 0.04 wt % Y on the oxidation behavior of pure Cr at 900 and 1025 deg C has been investigated. The microstructures and chemical compositions of the Cr sub 2 O sub 3 scales formed were studied both parallel and transverse to the...

C. M. Cotell, K. Przybylski, G. J. Yurek

1986-01-01

418

THE BINARY FREQUENCY OF r-PROCESS-ELEMENT-ENHANCED METAL-POOR STARS AND ITS IMPLICATIONS: CHEMICAL TAGGING IN THE PRIMITIVE HALO OF THE MILKY WAY  

SciTech Connect

A few rare halo giants in the range [Fe/H] {approx_equal} -2.9 {+-} 0.3 exhibit r-process element abundances that vary as a group by factors up to [r/Fe] {approx}80, relative to those of the iron peak and below. Yet, the astrophysical production site of these r-process elements remains unclear. We report initial results from four years of monitoring the radial velocities of 17 r-process-enhanced metal-poor giants to detect and characterize binaries in this sample. We find three (possibly four) spectroscopic binaries with orbital periods and eccentricities that are indistinguishable from those of Population I binaries with giant primaries, and which exhibit no signs that the secondary components have passed through the asymptotic giant branch stage of evolution or exploded as supernovae. The other 14 stars in our sample appear to be single-including the prototypical r-process-element-enhanced star CS 22892-052, which is also enhanced in carbon, but not in s-process elements. We conclude that the r-process (and potentially carbon) enhancement of these stars was not a local event due to mass transfer or winds from a binary companion, but was imprinted on the natal molecular clouds of these (single and binary) stars by an external source. These stars are thus spectacular chemical tracers of the inhomogeneous nature of the early Galactic halo system.

Hansen, Terese; Andersen, Johannes; Nordstroem, Birgitta; Buchhave, Lars A. [Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Beers, Timothy C., E-mail: terese@fys.ku.dk, E-mail: ja@astro.ku.dk, E-mail: birgitta@astro.ku.dk, E-mail: beers@pa.msu.edu, E-mail: buchhave@astro.ku.dk [Department of Physics and Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)

2011-12-10

419

Oxidation behavior of weld metal, HAZ and base metal regions in weldments of Cr-Mo steels  

SciTech Connect

In the weldments of 2.25Cr-1Mo and 9Cr-1Mo ferritic steels, the regions with different microstructures were identified as weld metal, heat-affected zone (HAZ) and base metal. When exposed to high temperatures, the HAZ of 2.25Cr-1Mo steel and the weld crown region of 9Cr-1 Mo steel were found to oxidize at higher rates, and develop much thicker scale than other regions in the weldments of the respective steels. SEM/EDS point analyses and SIMS depth profiles indicate that the scale over the regions showing inferior oxidation resistance are considerably less in free chromium content. The difference in the oxidation behavior of the different regions was found to arise from the difference in the Cr content of the inner layer of the protective oxide. Possible remedial measures to minimize the high oxidation rates in certain regions of the weldments of the two steels are also discussed.

Singh Raman, R.K.; Gnanamoorthy, J.B. [Indira Gandhi Center for Atomic Research, Kalpakkam (India). Metallurgy Division

1995-04-01

420

High field conduction and switching phenomena and magnetic spin resonance in metal oxide thin films and surfaces  

Microsoft Academic Search

Investigation was performed on transport, dielectric, switching and optical properties of thin amorphous and polycrystalline films of a series of transition metal and other oxides films. The conduction and dielectric dispersion mechanisms were unambiguously identified for each oxide studied in the parent metal-oxide-parent metal configuration. The switching phenomena and the observed RF oscillations in the negative resistance region were fully

B. Lalevic

1977-01-01

421

Structural characterization and phase transformations in metal oxide fi lms synthesized by Successive Ionic Layer Deposition (SILD) method  

Microsoft Academic Search

In this paper the peculiarities of phase composition and morphology of metal oxides synthesized by succes- sive ionic layer deposition (SILD) method are discussed. The main attention is focused on SnO2-based metal oxides, which are promising materials for gas sensor applications. FTIR spectroscopy has shown that the pre- cipitates of metal oxides, deposited by SILD method, are hydroxide, peroxide or

Ghenadii Korotcenkov; Sang Do Han; Beongki Cho; Valeri Tolstoy

422

Multistep soft chemistry method for valence reduction in transition metal oxides with triangular (CdI2-type) layers.  

PubMed

Transition metal (M) oxides with MO2 triangular layers demonstrate a variety of physical properties depending on the metal oxidation states. In the known compounds, metal oxidation states are limited to either 3+ or mixed-valent 3+/4+. A multistep soft chemistry synthetic route for novel phases with M(2+/3+)O2 triangular layers is reported. PMID:24487411

Blakely, Colin K; Bruno, Shaun R; Poltavets, Viktor V

2014-03-14

423

Significant thermal conductivity enhancement in graphene oxide papers modified with alkaline earth metal ions  

NASA Astrophysics Data System (ADS)

The thermal conductivities of graphene oxide paper (GOP) and the alkaline earth metal ions (Mg2+, Ca2+) modified analogues, prepared by a facile vacuum filtration method, were measured by a laser flash method. The thermal conductivities of GOP, Mg-modified GOP, and Ca-modified GOP are 3.91 W/(m × K), 32.05 W/(m × K), and 61.38 W/(m × K), respectively, which indicate the modification of GOP with metal ions has resulted in significant enhancement in thermal conduction properties compared with unmodified GOP. The crosslink between graphene oxide sheet and metal ions, the neat stacking of graphene oxide sheets in modified GOP, together with the intercalation of metal ions into the gallery spaces between the graphene oxide sheet basal planes, result in a decrease of thermal resistance of the boundary and an increase of contact surface, thus increases the thermal conductivity of modified graphene oxide paper.

Yu, Wei; Xie, Huaqing; Li, Fengxian; Zhao, Junchang; Zhang, Zhenhai

2013-09-01

424

Metal accumulation and oxidative stress responses in, cultured and wild, white seabream from Northwest Atlantic.  

PubMed

Metals are environmentally ubiquitous and can be found at high concentrations in seawater and subsequently in marine organisms. Metals with high redox potential can trigger oxidative stress mechanisms with damaging effects in biological tissues. In aquatic species, oxidative stress has been evaluated by assessing antioxidant enzymes activities and oxidative damages in tissues. The purpose of this study was to evaluate oxidative stress biomarkers and metal residues in white seabream (Diplodus sargus), a species entering aquaculture production in Portugal. Metal residues (Cu, Cd, As and Pb), in liver and muscle, as well as oxidative stress biomarkers were assessed at different stages in the life cycle of white seabream under culture conditions and in wild specimens, of a marketable size. Metal concentrations in tissues were low, and below the established limits. However, wild white seabream showed higher accumulation than cultured ones. Antioxidant enzymes, namely catalase (CAT) and superoxide dismutase (SOD), were correlated with metal accumulation. Oxidative damages to tissues were low, with wild white seabream showing lower levels than cultured fish. This study showed that white seabream has a good antioxidant defense system, capable of reducing oxidative damages in tissues resulting from the presence of metals. PMID:18783819

Ferreira, Marta; Caetano, Miguel; Costa, Joana; Pousão-Ferreira, Pedro; Vale, Carlos; Reis-Henriques, Maria Armanda

2008-12-15

425

Investigation on durability and reactivity of promising metal oxide sorbents during sulfidation and regeneration. Quarterly report, April--June 1995  

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. Removal reaction of H{sub 2}S from coal gas mixtures with ZT-4 or other promising sorbents of fine solid particles, and regeneration reaction of sulfur-loaded sorbents will be carried on in a batch reactor or a continuous differential reactor. The objectives of this research project are to find intrinsic initial reaction kinetics for the metal oxide-hydrogen sulfide heterogeneous reaction system, to obtain effects of concentrations of coal gas components such as hydrogen, carbon monoxide, carbon dioxide, oxygen, nitrogen and moisture on equilibrium reaction rate constants of the reaction system at various reaction temperatures and pressures, to identify regeneration kinetics of sulfur-loaded metal oxide sorbents, and to formulate promising metal oxide sorbents for the removal of sulfur from coal gas mixtures. Promising durable metal oxide sorbents of high-sulfur-absorbing capacity will be formulated by mixing active metal oxide powders with inert metal oxide powders and calcining these powder mixtures, or impregnating active metal oxide sorbents on supporting metal oxide matrixes. The Research Triangle Institute, 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 sorbents as well as regeneration of sulfur-loaded metal oxide sorbents, and review experimental results.

Kwon, K.C.

1995-07-01

426

Unusual hydrogen bonding behavior in binary complexes of coinage metal anions with water  

SciTech Connect

We have studied the interaction of atomic coinage metal anions with water molecules by infrared photodissociation spectroscopy of M{sup -}{center_dot}H{sub 2}O{center_dot}Ar{sub n} clusters (M=Cu, Ag, Au; n=1, 2). We compare our observations with calculations on density-functional and coupled cluster levels of theory. The gold anion is bound to the water molecule by a single ionic hydrogen bond, similar to the halide-water complexes. In contrast, zero-point motion in the silver and copper complexes leads to a deviation from this motif.

Schneider, Holger; Boese, A. Daniel; Weber, J. Mathias [Institut fuer Physikalische Chemie, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Institute of Nanotechnology, Forschungszentrum Karlsruhe, P.O. Box 3640, D-76021 Karlsruhe (Germany); Institut fuer Physikalische Chemie, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

2005-08-22

427

Electrical characteristics of plasma oxidized Si1-x-yGexCy metal-oxide-semiconductor capacitors  

NASA Astrophysics Data System (ADS)

Microwave plasma oxidation (below 200 °C) of partially strain-compensated Si1-x-yGexCy (Ge:C=20:1 and 40:1) with and without a Si cap layer is reported. The electrical properties of grown oxides have been characterized using a metal-oxide-semiconductor structure. Fixed oxide charge density and mid-gap interface trap density are found to be 2.9×1011/cm2 and 8.8×1011/cm2/eV, respectively, for directly oxidized Si0.79Ge0.2C0.01 film. The oxide on samples with low C (0.5%) concentration, exhibits hole trapping, whereas electron trapping is observed for oxides on alloys containing 1% C.

Ray, S. K.; Bera, L. K.; Maiti, C. K.; John, S.; Banerjee, S. K.

1998-03-01

428

Metal nanocrystal memory with sol-gel derived HfO2 high-? tunneling oxide  

Microsoft Academic Search

A metal-oxide-semiconductor (MOS) capacitor structure containing gold (Au) nanoparticles (NPs) within sol-gel derived HfO2 high-? oxide is fabricated. Firstly, the Au NPs with particle size of about 3.3 nm were synthesized by chemical reduction method. Then the 10 nm-thick HfO2 tunneling oxide, the Au NPs and the 15 nm-thick HfO2 control oxide were prepared by spin coating method to construct

Shih-Tang Chen; Kun-Cheng Huang; Hua-Chiang Chen; Fu-Ken Liu; Ching-Chich Leu

2010-01-01

429

Low-temperature solution-processed metal oxide buffer layers fulfilling large area production requirements  

NASA Astrophysics Data System (ADS)

This paper is a review of our previous work on the field of low temperature, solution processed metal oxide buffer layers published in various journals. Our work focuses on zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) as n-type and molybdenum oxide (MoO3) as p-type solution processed buffer layer. In addition to that, we investigate the surface modification of AZO using phosphonic acid-anchored aliphatic and fullerene self assembled monolayers (SAMs).

Stubhan, T.; Litzov, I.; Li, Ning; Wang, H. Q.; Krantz, J.; Machui, F.; Steidl, M.; Oh, H.; Matt, G. J.; Brabec, C. J.

2012-09-01

430

Structural, electrical and magnetic properties of transition metal nickel oxides  

NASA Astrophysics Data System (ADS)

Neutron powder diffraction, high pressure, magnetic susceptibility, and heat capacity measurements, as well as x-ray powder diffraction and iodometric titration, have been conducted on transition metal nickel oxides (TMOs), representative Ruddlesden-Popper (RP) phases Lan+1NinO3n+1 (n = 1, 2, ..., infinity) and hole-doped La2-xSr xNiO4 (0 ? x ? 1.2). The first complete study of La 2-xSrxNiO4 (0 ? x ? 1.2) and La n+1NinO3n+1 (n = 2 and 3) phases under high pressure is produced. Strong direct experimental evidence for polaron dominated electrical conduction in these charge transfer (CT) gap La2-xSr xNiO4 compounds is provided. Temperature evolution of the crystal structure of La2-xSrxNiO4 (x = 1/4 and 1/3) is revealed through neutron powder diffraction, structural relationships among n = 1, 2, and 3 phases are exhibited, and charge density wave (CDW) in multilayer Lan+1NinO3n+1 phases is strongly suggested. No superconductivity is observed at pressures up to 1.6 GPa and temperatures down to 4.2 K.

Wu, Guoqing

431

Improved atomistic simulation of diffusion and sorption in metal oxides  

NASA Astrophysics Data System (ADS)

Gas diffusion and sorption on the surface of metal oxides are investigated using atomistic simulations, that make use of two different force fields for the description of the intramolecular and intermolecular interactions. MD and MC computations are presented and estimates of the mean residence time, Henry's constant, and the heat of adsorption are provided for various common gases (CO, CO2, O2, CH4, Xe), and semiconducting substrates that hold promise for gas sensor applications (SnO2, BaTiO3). Comparison is made between the performance of a simple, first generation force field (Universal) and a more detailed, second generation field (COMPASS) under the same conditions and the same assumptions regarding the generation of the working configurations. It is found that the two force fields yield qualitatively similar results in all cases examined here. However, direct comparison with experimental data reveals that the accuracy of the COMPASS-based computations is not only higher than that of the first generation force field but exceeds even that of published specialized methods, based on ab initio computations.

Skouras, E. D.; Burganos, V. N.; Payatakes, A. C.

2001-01-01

432

Growth of metal oxide nanowires from supercooled liquid nanodroplets.  

PubMed

Nanometer-sized liquid droplets formed at temperatures below the bulk melting point become supercooled as they grow through Ostwald ripening or coalescence and can be exploited to grow nanowires without any catalyst. We used this simple approach to synthesize a number of highly crystalline metal oxide nanowires in a chemical or physical vapor deposition apparatus. Examples of nanowires made in this way include VO(2), V(2)O(5), RuO(2), MoO(2), MoO(3), and Fe(3)O(4), some of which have not been previously reported. Direct evidence of this new mechanism of nanowire growth is found from in situ 2-dimensional GISAXS (grazing incidence small angle X-ray scattering) measurements of VO(2) nanowire growth, which provides quantitative information on the shapes and sizes of growing nanowires as well as direct evidence of the presence of supercooled liquid droplets. We observe dramatic changes in nanowire growth by varying the choice of substrate, reflecting the influence of wetting forces on the supercooled nanodroplet shape and mobility as well as substrate-nanowire lattice matching on the definition of nanowire orientation. Surfaces with defects can also be used to pattern the growth of the nanowires. The simplicity of this synthesis concept suggests it may be rather general in its application. PMID:19780585

Kim, Myung Hwa; Lee, Byeongdu; Lee, Sungsik; Larson, Christopher; Baik, Jeong Min; Yavuz, Cafer T; Seifert, Sönke; Vajda, Stefan; Winans, Randall E; Moskovits, Martin; Stucky, Galen D; Wodtke, Alec M

2009-12-01

433

Single-photon imaging in complementary metal oxide semiconductor processes  

PubMed Central

This paper describes the basics of single-photon counting in complementary metal oxide semiconductors, through single-photon avalanche diodes (SPADs), and the making of miniaturized pixels with photon-counting capability based on SPADs. Some applications, which may take advantage of SPAD image sensors, are outlined, such as fluorescence-based microscopy, three-dimensional time-of-flight imaging and biomedical imaging, to name just a few. The paper focuses on architectures that are best suited to those applications and the trade-offs they generate. In this context, architectures are described that efficiently collect the output of single pixels when designed in large arrays. Off-chip readout circuit requirements are described for a variety of applications in physics, medicine and the life sciences. Owing to the dynamic nature of SPADs, designs featuring a large number of SPADs require careful analysis of the target application for an optimal use of silicon real estate and of limited readout bandwidth. The paper also describes the main trade-offs involved in architecting such chips and the solutions adopted with focus on scalability and miniaturization. PMID:24567470

Charbon, E.

2014-01-01

434

Atomic-Imaging of Oxide Supported Metallic Nanocrystals  

SciTech Connect

The nucleation of noble metal nanoparticles on oxide surfaces can lead to dramatic enhancements in catalytic activity that are related to the atomic-scale formation of the nanoparticles and interfaces. For the case of submonolayer Pt deposited on the 2 x 1 SrTiO{sub 3}(001) surface atomic-force microscopy shows the formation of nanoparticles. We use X-ray standing wave (XSW) atomic imaging to show that these nanoparticles are composed of Pt face-centered-cubic nanocrystals with cube-on-cube epitaxy laterally correlated to the substrate unit cell. The phase sensitivity of the XSW allows for a direct measurement of the interface offset between the two unit cells along the c-axis. Different Pt coverages lead to differences in the observed XSW image of the interfacial structure, which is explained by a proposed model based on the Pt-Pt interaction becoming stronger than the Pt-substrate interaction as the global coverage is increased from 0.2 to 0.6 ML.

Feng, Zhenxing; Kazimirov, Alexander; Bedzyk, Michael J. (Cornell); (NWU)

2012-01-27

435

Atomic imaging of oxide-supported metallic nanocrystals.  

SciTech Connect

The nucleation of noble metal nanoparticles on oxide surfaces can lead to dramatic enhancements in catalytic activity that are related to the atomic-scale formation of the nanoparticles and interfaces. For the case of submonolayer Pt deposited on the 2 x 1 SrTiO{sub 3}(001) surface atomic-force microscopy shows the formation of nanoparticles. We use X-ray standing wave (XSW) atomic imaging to show that these nanoparticles are composed of Pt face-centered-cubic nanocrystals with cube-on-cube epitaxy laterally correlated to the substrate unit cell. The phase sensitivity of the XSW allows for a direct measurement of the interface offset between the two unit cells along the c-axis. Different Pt coverages lead to differences in the observed XSW image of the interfacial structure, which is explained by a proposed model based on the Pt-Pt interaction becoming stronger than the Pt-substrate interaction as the global coverage is increased from 0.2 to 0.6 ML.

Feng, Z.; Kazimirov, A.; Bedzyk, M. J. (Materials Science Division); (Northwestern Univ.); (Cornell Univ.)

2011-10-01

436

Atomic imaging of oxide-supported metallic nanocrystals.  

PubMed

The nucleation of noble metal nanoparticles on oxide surfaces can lead to dramatic enhancements in catalytic activity that are related to the atomic-scale formation of the nanoparticles and interfaces. For the case of submonolayer Pt deposited on the 2×1 SrTiO(3)(001) surface atomic-force microscopy shows the formation of nanoparticles. We use X-ray standing wave (XSW) atomic imaging to show that these nanoparticles are composed of Pt face-centered-cubic nanocrystals with cube-on-cube epitaxy laterally correlated to the substrate unit cell. The phase sensitivity of the XSW allows for a direct measurement of the interface offset between the two unit cells along the c-axis. Different Pt coverages lead to differences in the observed XSW image of the interfacial structure, which is explained by a proposed model based on the Pt-Pt interaction becoming stronger than the Pt-substrate interaction as the global coverage is increased from 0.2 to 0.6 ML. PMID:22032686

Feng, Zhenxing; Kazimirov, Alexander; Bedzyk, Michael J

2011-12-27

437

Zeolite-supported metal oxide sorbents for hot-gas desulfurization  

SciTech Connect

This paper describes the results of the development of supported mixed-metal oxide sorbents for hot-gas desulfurization capable of withstanding multiple sulfidation/regeneration cycles at 871 C (1600 F). The sorbents consisted of various combinations of copper, molybdenum, and/or manganese oxides supported on a high silica-containing zeolite. These sorbents were tested in a fixed-bed reactor with simulated coal gas at 205 kPa (15 psig). The combination of all three metal oxides displayed synergism in enhancing efficiency for H{sub 2}S removal and improved the crush strength on the pellets. Copper oxide was the most active component for reaction with H{sub 2}S, while molybdenum and manganese oxides ap