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1

Nonpolar resistance switching of metal\\/binary-transition-metal oxides\\/metal sandwiches: Homogeneous\\/inhomogeneous transition of current distribution  

Microsoft Academic Search

Exotic features of a metal\\/oxide\\/metal sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3 , NiO , and CoO . The sandwich exhibits a resistance that reversibly switches between two

I. H. Inoue; S. Yasuda; H. Akinaga; H. Takagi

2008-01-01

2

Preparation and Evaluation of FeAl Binary Oxide for Arsenic Removal: Comparative Study with Single Metal Oxides  

Microsoft Academic Search

In this study, Fe-Al binary oxide was synthesized and evaluated for arsenic removal. Due to its large surface area, Fe-Al mixed oxide shows four times higher As(V) and As(III) adsorption capacity than conventional iron oxide. For a comparative study, single metal oxides such as iron oxide and aluminum oxide are also synthesized. The physical and chemical characteristics of the prepared

Hye-Jin Hong; Wasif Farooq; Jung-Seok Yang; Ji-Won Yang

2010-01-01

3

Resistive switching memory devices composed of binary transition metal oxides using sol-gel chemistry.  

PubMed

We describe a novel and versatile approach for preparing resistive switching memory devices based on binary transition metal oxides (TMOs). Titanium isopropoxide (TIPP) was spin-coated onto platinum (Pt)-coated silicon substrates using a sol-gel process. The sol-gel-derived layer was converted into a TiO2 film by thermal annealing. A top electrode (Ag electrode) was then coated onto the TiO2 films to complete device fabrication. When an external bias was applied to the devices, a switching phenomenon independent of the voltage polarity (i.e., unipolar switching) was observed at low operating voltages (about 0.6 VRESET and 1.4 VSET). In addition, it was confirmed that the electrical properties (i.e., retention time, cycling test and switching speed) of the sol-gel-derived devices were comparable to those of vacuum deposited devices. This approach can be extended to a variety of binary TMOs such as niobium oxides. The reported approach offers new opportunities for preparing the binary TMO-based resistive switching memory devices allowing a facile solution processing. PMID:19317425

Lee, Chanwoo; Kim, Inpyo; Choi, Wonsup; Shin, Hyunjung; Cho, Jinhan

2009-04-21

4

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

5

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

PubMed

To capture and recover mercury from coal-fired flue gas, a series of novel regenerable sorbents based on Zr-Mn binary metal oxides were prepared and employed at a relatively low temperature. PXRD, TEM, TPR, XPS, and N2-adsorption methods were employed to characterize the sorbents. The Hg(0) adsorption performance of the sorbents was tested, and the effects of the main operation parameters and the gas components on the adsorption were investigated. Zr significantly improved the sorbent's mercury capacity, which was nearly 5mg/g for Zr0.5Mn0.5Oy. Furthermore, the spent sorbent could be regenerated by heating to 350°C, and the highly concentrated elemental mercury released could be facilely recycled. Therefore, a much greener process for mercury capture and recovery could be anticipated based on this regenerable sorbent. PMID:23933289

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

2013-07-22

6

The generation of acid sites on the surfaces of binary metal oxide catalysts  

SciTech Connect

The generation of acid sites by the addition of dopant cations to the surfaces of metal oxides was studied through the use of pyridine adsorption, combined with gravimetric measurements, infrared spectroscopy and Mossbauer spectroscopy. Lewis acid sites were shown to be coordinately unsaturated cations on the surface. The existence of these Lewis acid sites can be estimated based on the coordination of the cations. The strength of the sites can be estimated using the electronegativity of the cations. The existence of Bronsted acid sites was shown to occur in special cases where a bridging hydroxyl group exists between two different cations on the surface. The existence of the Bronsted acid sites can be predicted with the bonding geometry and surface structure.

Connell, G.; Dumesic, J.A.

1986-01-01

7

Excellent uniformity and reproducible resistance switching characteristics of doped binary metal oxides for non-volatile resistance memory applications  

Microsoft Academic Search

We have investigated various doped metal oxides such as copper doped molybdenum oxide, copper doped Al2O3, copper doped ZrO2, aluminium doped ZnO, and CuxO for novel resistance memory applications. Compared with non-stoichiometric oxides (Nb2O5-x, ZrOx, SrTiOx), doped metal oxides show higher device yield. Moreover, Cu:MoOx have demonstrated excellent memory characteristics such as reliability under programming cycles, potential multi-bit operation, good

Dongsoo Lee; Dong-jun Seong; Hye jung Choi; Inhwa Jo; R. Dong; W. Xiang; Seokjoon Oh; Myeongbum Pyun; Sun-ok Seo; Seongho Heo; Minseok Jo; Dae-Kyu Hwang; H. K. Park; M. Chang; M. Hasan; Hyunsang Hwang

2006-01-01

8

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

9

Platinum nanoparticles–manganese oxide nanorods as novel binary catalysts for formic acid oxidation  

Microsoft Academic Search

The current study proposes a novel binary catalyst system (composed of metal\\/metal oxide nanoparticles) as a promising electrocatalyst in formic acid oxidation. The electro-catalytic oxidation of formic acid is carried out with binary catalysts of Pt nanoparticles (nano-Pt) and manganese oxide nanorods (nano-MnOx) electrodeposited onto glassy carbon (GC) electrodes. Cyclic voltammetric (CV) measurements showed that unmodified GC and nano-MnOx\\/GC electrodes

Mohamed S. El-Deab

10

TiO 2-Supported Binary Metal Oxide Catalysts for Low-temperature Selective Catalytic Reduction of NO x with NH 3  

Microsoft Academic Search

Binary metal oxide(MnOx-A\\/TiO2) catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide(TiO2), where, A indicates Fe2O3, WO3, MoO3, and Cr2O3. Their catalytic activity, N2 selectivity, and SO2 poisonous tolerance were investigated. The catalytic performance at low temperatures decreased in the following order: Mn-W\\/TiO2>Mn-Fe\\/TiO2>Mn-Cr\\/TiO2>Mn-Mo\\/TiO2, whereas the N2 selectivity decreased in the order: Mn-Fe\\/TiO2>Mn-W\\/TiO2>Mn-Mo\\/TiO2>Mn-Cr\\/TiO2. In the

Bi-jun WU; Xiao-qin LIU; Ping XIAO; Shu-gang WANG

2008-01-01

11

An Acidity Scale for Binary Oxides.  

ERIC Educational Resources Information Center

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

Smith, Derek W.

1987-01-01

12

Pd-Si binary bulk metallic glass  

NASA Astrophysics Data System (ADS)

Pd80+ x Si20- x ( x = 0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature T g, the initial crystallization temperature T x and the onset crystallization temperature T p of Pd-Si binary glassy alloys increase. Moreover, the supercooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability, which can be greatly improved by fluxing treatment.

Yao, Kefu; Chen, Na

2008-04-01

13

Improvement in heat resistance of NOx trap catalyst using Ti–Na binary metal oxide as NOx trap material  

Microsoft Academic Search

The purpose of this study was to identify suitable base materials for NOx trap catalysts from the viewpoint of heat resistance. First, suitable elements among alkali metals (M: K, Na, Li) and alkaline earth metals (M: Ba, Ca, Sr, Mg) were evaluated using M–Rh,Pt\\/Al2O3. Na was found to be the most suitable element that combines NOx trap performance with hydrocarbon

Hidehiro Iizuka; Masato Kaneeda; Norihiro Shinotsuka; Osamu Kuroda; Kazutoshi Higashiyama; Akira Miyamoto

2010-01-01

14

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

15

Effects of surface poisons on the oxidation of binary alloys  

SciTech Connect

A system of reaction-diffusion equations describing the oxidation of binary alloys in environments containing small amounts of surface poisons is analyzed. These poisons reduce the oxygen flux into the alloy, which causes the alloy to oxidize in two stages.During the initial stage, the oxidation reaction occurs in a stationary boundary layer at the alloy surface. Consequently, a thin zone containing a very high concentration of the metal oxide is created at the alloy surface. During the second stage, the oxidation reaction occurs in a moving boundary layer. This leads to a Stefan problem, which is analyzed by using asymptotic and numerical techniques. By comparing the solutions to those of alloys in unpoisoned environments, it is concluded that surface poisons can lead to the formation of protective external oxide scales in alloys which would not normally form such scales. 11 references.

Hagan, P.S.; Polizzotti, R.S.; Luckman, G.

1985-10-01

16

Synthesis and characterization of a binary noble metal nitride  

Microsoft Academic Search

There has been considerable interest in the synthesis of new nitrides because of their technological and fundamental importance. Although numerous metals react with nitrogen there are no known binary nitrides of the noble metals. We report the discovery and characterization of platinum nitride (PtN), the first binary nitride of the noble metals group. This compound can be formed above 45-50

Eugene Gregoryanz; Chrystele Sanloup; M. Somayazulu; James Badro; Guillaume Fiquet; Ho-Kwang Mao; Russell J. Hemley

2004-01-01

17

Synthesis and Electronic Applications of Oxide-Metal Eutectic Composites.  

National Technical Information Service (NTIS)

A review is given of important developments in the synthesis of oxide-metal eutectic composites and the composite application in the continuing development of field emitters. Known metal oxide-metal binary and ternary eutectic systems are listed. The synt...

J. D. Holder J. K. Cochran D. N. Hill A. T. Chapman G. W. Clark

1980-01-01

18

Transition-Metal Oxides with Metallic Conductivity.  

National Technical Information Service (NTIS)

Two possible mechanisms for metallic conductivity in transition-metal oxides are discussed: band formation on the transition-meta subbary and band formation via pi bonding orbitals. This permits a general classification of metallic oxides. Two electron-tr...

J. B. Goodenough

1964-01-01

19

Metal atom oxidation laser  

DOEpatents

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

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

1975-10-28

20

Metal atom oxidation laser  

DOEpatents

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

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

1975-10-28

21

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

22

The Difference Between Metal-Poor and Metal-Rich Binaries  

NASA Astrophysics Data System (ADS)

In the past there have been many discrepant studies about whether metal-poor (Population II) stars were deficient in binaries or had approximately the same binary frequency as metal-rich stars. We consider here the distributions of periods in five samples of binaries: (1) 138 field halo binaries with low metal abundances ([Fe/H] < -0.30) observed by Latham et al. and Goldberg et al., (2) 42 blue metal-poor binaries discovered by Preston & Sneden, (3) all 145 known FG dwarf binaries with [Fe/H] > -0.30 as listed on-line by Pourbaix, (4) 31 binaries among the well-studied FG dwarfs within 25 pc of the Sun, and (5) binaries in three open clusters with ages of 108-109 yr. The main result is that the metal-poor stars lack short-period binaries relative to the metal-rich stars; the period distributions are very different. This tells us two things. First, the determination of the frequency of discovered binaries for metal-poor and metal-rich stars will depend upon the equipment used: if one uses low-resolution spectrographs, one will detect many of the short-period binaries but not many of the long-period binaries and conclude that the metal-poor stars are deficient in binaries. If one uses higher resolution, as did Latham et al., one will detect many more binaries and conclude that there is no difference in binary frequency between metal-poor and metal-rich stars. Second, if binaries are formed in three-body interactions in clusters and, as n-body simulations show, the longer they remain in dense cluster environments, the harder (shorter periods) they become.

Abt, Helmut A.

2008-02-01

23

Metal Oxides Synthesis  

Microsoft Academic Search

\\u000a Many oxide\\/oxide composite nanocrystals were synthesized in continuous flow SCW processes in short time (e.g., 0.4 s?2 min)\\u000a from metal cations via hydrolysis and subsequent dehydration. Metal particles could be produced by further reduction of the\\u000a metal oxide in SCW. These particles included ferrite magnetic pigments [Fe3O4, MFe2O4 (M = Co, Ni, Zn), NixCo1?xFe2O4, \\u000a \\u000a\\u000a\\u000a\\u000a\\u000a\\u000aBaO\\\\scriptscriptstyle·<\\/font\\u000a>6Fe2 O3{\\\\textrm {BaO}}{\\\\scriptscriptstyle{\\\\bullet}}6{\\\\textrm{Fe}}_{2} {\\\\textrm{O}}_{3}\\u000a ] for recording

Zhen Fang

24

Binary Populations of Carbon-Enhanced Metal-Poor Stars  

NASA Astrophysics Data System (ADS)

We construct binary-star population nucleosynthesis models of carbon-enhanced metal-poor (CEMP) stars. We compare the CEMP to extremely metal-poor (EMP) ratio of our models to the observed ratio and find it is an order of magnitude too small. Through an increase in the efficiency of third dredge-up in low-mass, low-metallicity, thermally-pulsing Asymptotic Giant Branch (TP-AGB) stars our models better match the observations.

Izzard, Robert G.; Glebbeek, Evert; Stancliffe, Richard J.; Pols, Onno

2009-09-01

25

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

26

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

27

Close binary mass anomalies and metallicity  

NASA Astrophysics Data System (ADS)

Direct (radial velocity) and indirect (spectral type, luminosity class) mass determinations for luminosity class V binaries are compared. The existence of statistical biases or apparently irreconcilable individual discrepancies, or both, in the data is examined, and their explanation by astrophysical effects such as chemical composition and age differences is considered. The existence of residual discrepancies, after correction for chemical composition effects and statistical allowance for age effects, which could only be due to other astrophysical effects, to instrumental effects, or to selection effects, is investigated. A need for at least one additional astrophysical effect, suspected to be fast core rotation, is found in a few binaries. It is argued that some remaining evidence for systematic observational errors is more likely to be the result of selection effects rather than an instrumental effect.

van Hamme, W.; Wilson, R. E.

1986-08-01

28

Surface modes in binary metal-dielectric metamaterials  

NASA Astrophysics Data System (ADS)

Motivated by Nam et al. (2010) [1], we present general properties of localized surface modes, including the Shockley-like and Tamm-like surface modes, and give their existence conditions with coupling perturbation at the surface in semi-infinite binary metal-dielectric metamaterials in the frame of coupled mode theory.

Zhao, Yuanyuan

2012-11-01

29

Electrolytic recovery of binary metals and EDTA from strong complexed solutions  

Microsoft Academic Search

Electrolytic recovery of binary Cu(II) and Pb(II) from solutions containing strong complexing agent EDTA (ethylenediaminetetraacetic acid) was studied in a two-chamber cell separating with a cation exchange membrane Neosepta CM-1. An equimolar solution of EDTA and total metals was focused. The iridium oxide coated on titanium (Ti\\/IrO2) and stainless steel were used as the anode and cathode, respectively. Experiments were

Ruey-Shin Juang; Shiow-Wen Wang

2000-01-01

30

Transparent metal oxide nanowire transistors  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

31

Investigation of surface synergetic oxygen vacancy in CuO-CoO binary metal oxides supported on ?-Al2O3 for NO removal by CO.  

PubMed

The influence of CO pretreatment on the properties of CuO-CoO/?-Al(2)O(3) catalysts was investigated by SEM, TEM, XRD, LRS, XPS, TPR, and in situ FT-IR techniques. And the activities were measured by NO removal by CO. It was shown that the CuO-CoO/?-Al(2)O(3) catalysts following CO pretreatment exhibited extremely high activity and selectivity. The interaction between copper oxide and cobalt oxide upon the ?-Al(2)O(3) support before and after CO pretreatment was tentatively discussed in the view of incorporation model. According to this model, the dispersed Cu-O-Co species could be reduced to Cu-?-Co species by CO pretreatment, which was considered to be the primary active component for this reaction. FT-IR results suggested that CO was apt to adsorb on Cu(+) sites rather than Co(2+) while the NO adsorbates could convert to much more stable species with the temperature increasing. Undoubtedly, it was the surface synergetic oxygen vacancy coupled with the adjacent Cu and Co ions that guaranteed the reaction well processing over the CO pretreated samples. As a result, a possible mechanism was tentatively proposed. PMID:23089598

Lv, Yuanyuan; Liu, Lichen; Zhang, Hongliang; Yao, Xiaojiang; Gao, Fei; Yao, Kaian; Dong, Lin; Chen, Yi

2012-10-01

32

Cation effects in the oxidative coupling of methane on silica-supported binary alkali and alkaline earths  

SciTech Connect

The oxidative coupling of methane has been investigated with a series of silica-supported binary oxide catalysts containing alkali or alkaline earths or combinations of the former and latter. The conversion of methane and the stability of the silica-supported binary alkali metal oxides were found to increase with decreasing cation mobility, while the selectivities and conversions observed with the binary alkaline earths increase with cation size. The selectivities and conversions of binary alkali/alkaline earths appear to depend upon the size of the alkali and alkaline earth cations, respectively. With small quantities of TCM (CCl[sub 4]) added continuously to the feedstream, catalysts containing small alkali and large alkaline earth cations produced the largest selectivities and conversions. 23 refs., 14 figs., 2 tabs.

Voyatzis, R.; Moffat, J.B. (Univ. of Waterloo, Ontario (Canada))

1993-07-01

33

Clean Metal Oxide Semiconductor Systems  

Microsoft Academic Search

Aspects of sodium contamination of metal-oxide-silicon (MOS) systems associated with silicon surface preparation, the oxidation plenum, and post-oxidation procedures, including contact application, are discussed. The validity of neutron activation analysis to determine sodium distributions in MOS samples is established. Refractory materials for furnace construction are examined and shown to contain as much as 1 - 5 percent sodium or potasium.

H. G. Carlson; C. R. Fuller; D. E. Meyer; J. R. Osborne; V. Harrap; G. A. Brown

1966-01-01

34

Outlook for binary power plants using liquid-metal MHD  

Microsoft Academic Search

Preliminary testing and extrapolations thereof indicate that liquid-metal MHD can be used as a topping cycle to increase the efficiency of large central-station power plants. Because maximum temperatures as low as 870° C are effective, such binary plants are possible with existing material technology. The best present choices appear to be a potassium working fluid and either a (helium-or sodium-cooled)

L. L. Prem; W. E. Parkins

1970-01-01

35

Oscillatory surface intermixing in binary metallic alloys*  

NASA Astrophysics Data System (ADS)

The creation of a surface of a metallic system often leads to an oscillatory charge density distribution propagating into the bulk [1], which may further induce an oscillatory interlayer lattice relaxation [2]. Oscillatory intermixing has also been frequently observed in disordered alloys, with one of the constituents enriched or depleted from layer to layer. Here we investigate the oscillation of the concentration profiles in the first few layers of different alloys using the density functional theory, with the Mo-Re and Mo-Ta systems as specific examples. The Re (Ta) atom has charge excess (deficiency) with respect to the host Mo atom. The Re (Ta) is found to follow the maxima (minima) of the oscillatory charge density distribution of the Mo surface layers, thus elucidating the microscopic origin of the oscillation of the alloy concentration at different layers. [1] N. D. Lang and W. Kohn, Phys. Rev. B 1 4555 (1970). [2] Jun-Hyung Cho, Ismail, Z. Zhang and E. W. Plummer, Phys. Rev. B 59 1677 (1999).

Varga, Kalman; Wang, Ligen; Pennycook, Stephen J.; Pantelides, Sokrates T.; Zhang, Zhenyu

2001-03-01

36

Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements.  

National Technical Information Service (NTIS)

Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method ...

J. E. Selle

1992-01-01

37

Valence structure of alkaline and post-transition metal oxides  

Microsoft Academic Search

As a stepping point to predicting band gaps and electronic structure of more complicated materials based on alkaline and post-transition metal oxides, we examine the valence structure of these simple binary oxides using both high resolution X-ray emission spectroscopy and a variety of density functional theory calculations. We confirm that the new modified Becke-Johnson (mBJ) extension of the Perdew-Burke-Ernzerhoff (PBE96)

John A. McLeod; Robert J. Green; Nikolay A. Skorikov; L. D. Finkelstein; Mahmoud Abu-Samak; Ernst Z. Kurmaev; Alexander Moewes

2011-01-01

38

Process for fabrication of metal oxide films  

DOEpatents

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

39

METAL OXIDE NANOPARTICLES  

SciTech Connect

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

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

2007-10-01

40

Metal oxide photoanodes for water splitting.  

PubMed

Solar hydrogen production through photocatalytically assisted water splitting has attracted a great deal of attention since its first discovery almost 30 years ago. The publication of investigations into the use of TiO? photoanodes has continued apace since and a critical review of current trends is reported herein. Recent advances in the understanding of the behaviour of nanoparticulate TiO? films is summarized along with a balanced report into the utility and nature of titania films doped with non-metallic elements and ordered, nanostructured films such as those consisting of nanotubes. Both of these are areas that have generated a not insignificant degree of activity. One goal of doping TiO? has been to extend the photoresponse of the material to visible light. A similar goal has seen a resurgence in interest in Fe?O? photoanodes. Herein, the influence of dopants on the photocurrent density observed at Fe?O? photoanodes and, in this regard, the role of silicon has attracted much attention, and a little debate. Finally, we look beyond the binary oxides. Photoanodes made from new materials such as mixed metal oxides, perovskite structured semiconductors, metal (oxy)nitrides or composite electrodes offer the potential to either tailor the optical band gap or tune the conduction or valence band energetics. Recent work in this area is detailed here. PMID:21506001

Augusty?ski, J; Alexander, B D; Solarska, R

2011-01-01

41

Metal Oxide Infrared Emission.  

National Technical Information Service (NTIS)

The state of the earth's upper atmosphere under disturbed conditions is of considerable importance for a variety of military applications ranging from artificial metal releases to high-altitude nuclear explosions. In this context, the authors have been de...

R. N. Zare

1972-01-01

42

SINTERING METAL OXIDES  

DOEpatents

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

Roake, W.E.

1960-09-13

43

Engineering catalytic contacts and thermal stability: gold/iron oxide binary nanocrystal superlattices for CO oxidation.  

PubMed

Well-defined surface, such as surface of a single crystal, is being used to provide precise interpretation of catalytic processes, while the nanoparticulate model catalyst more closely represents the real catalysts that are used in industrial processes. Nanocrystal superlattice, which combines the chemical and physical properties of different materials in a single crystalline structure, is an ideal model catalyst, that bridge between conventional models and real catalysts. We identify the active sites for carbon monoxide (CO) oxidation on Au-FeO(x) catalysts by using Au-FeO(x) binary superlattices correlating the activity to the number density of catalytic contacts between Au and FeO(x). Moreover, using nanocrystal superlattices, we propose a general strategy of keeping active metals spatially confined to enhance the stability of metal catalysts. With a great range of nanocrystal superlattice structures and compositions, we establish that nanocrystal superlattices are useful model materials through which to explore, understand, and improve catalytic processes bridging the gap between traditional single crystal and supported catalyst studies. PMID:23294105

Kang, Yijin; Ye, Xingchen; Chen, Jun; Qi, Liang; Diaz, Rosa E; Doan-Nguyen, Vicky; Xing, Guozhong; Kagan, Cherie R; Li, Ju; Gorte, Raymond J; Stach, Eric A; Murray, Christopher B

2013-01-17

44

Properties of binary transition-metal arsenides (TAs)  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

45

Method for plating with metal oxides  

DOEpatents

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

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

1994-08-23

46

Metal Oxides in the Environment  

SciTech Connect

Oxides are ubiquitous in much of environmental chemistry. Silica and related glasses are potential vehicles by which radioactive elements may be sequestered and stored. The migration of toxic waste in ground water is largely influenced by interactions at the liquid-solid interface, with several metal oxides making up the bulk of soil. In addition, metal oxides with Bronsted acid or Lewis base functionality are potential replacements for many traditional liquid catalysis that are hazardous to work with and difficult to dispose. In this proposal, we targeted two such areas of oxide chemistry. The long-term behavior of silicate materials slated for use in the entombment of high-level waste (HLW), and the use of solid acid metal oxides as replacements for toxic sulfuric and hydrofluoric acid used in industry (referred to as Green Chemistry). Thus, this project encompassed technology that can be used to both remediate and prevent pollution. These oxide systems were studied using density functional theory (DFT). The comparatively large size and complexity of the systems that will bweree studied made use of high-accuracy electronic structure studies intractable on conventional computers. The 512 node parallel processor housed in the Molecular Science Computing Facility (MSCF) provided the required capability.

Jonsson, Hannes; Corrales, L. Rene; Gabriel, Peggy; Haw, James F.; Henkelman, Graeme A.; Neurock, Matthew; Nicholas, John B.; Park, Byeongwon; Song, Jakyoung; Trout, Bernhardt; Tsemekhman, Kiril L.; Uberuaga, Blas P.; Van Ginhoven, Renee M.

2002-08-30

47

Lithium metal reduction of plutonium oxide to produce plutonium metal  

SciTech Connect

This patent describes a method for production of plutonium metal from plutonium oxide by metallic lithium reduction, with regeneration of lithium reactant. It comprises: reacting the plutonium oxide with metallic lithium; oxides and unreacted lithium; subliming the product lithium oxide and unreacted lithium from unreacted plutonium oxide with high heat and low pressure; recapturing the product lithium oxides; reacting the recaptured product lithium oxides with anhydrous hydrochloric acid to produce lithium chloride salt; and decomposing product lithium chloride salt by electrolysis to regenerate lithium metal.

Coops, M.S.

1992-06-02

48

Solution synthesis of nanoparticular binary transition metal antimonides.  

PubMed

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

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

2011-07-07

49

Nonaqueous routes to crystalline metal oxide nanoparticles: Formation mechanisms and applications  

Microsoft Academic Search

We developed novel reaction approaches using non-aqueous and halide-free procedures to synthesize a wide variety of different metal oxide nanoparticles including the binary metal oxides of groups IV and V, SnO2, In2O3, FeOx, ZnO, Ga2O3, perovskites (BaTiO3, SrTiO3, (Ba,Sr)TiO3, BaZrO3) and related compounds (LiNbO3). These routes involve the solvothermal reaction of metal oxide precursors such as metal alkoxides or metal

Markus Niederberger; Georg Garnweitner; Nicola Pinna; Giovanni Neri

2005-01-01

50

Infrared reflection spectroscopy for precise tracking of corrosion behavior in 3d-transition metals doped binary lead silicate glass  

Microsoft Academic Search

Fourier transform infrared reflection (FTIRR) spectroscopy was used to monitor and confirm the proposed corrosion mechanisms and structural differences in the surface regions of some prepared undoped binary lead silicate PbO-SiO2 glass (LSG) together with samples doped with one of the first 3d-transition metal oxides (TMOs) (TiO2-->CuO) exposed to aqueous solutions of different pHs for a fixed time (1 h).

F. H. El-Batal; E. M. A. Khalil; Y. M. Hamdy; H. M. Zidan; M. S. Aziz; A. M. Abdelghany

2010-01-01

51

Infrared reflection spectroscopy for precise tracking of corrosion behavior in 3d-transition metals doped binary lead silicate glass  

Microsoft Academic Search

Fourier transform infrared reflection (FTIRR) spectroscopy was used to monitor and confirm the proposed corrosion mechanisms and structural differences in the surface regions of some prepared undoped binary lead silicate PbO–SiO2 glass (LSG) together with samples doped with one of the first 3d-transition metal oxides (TMOs) (TiO2?CuO) exposed to aqueous solutions of different pHs for a fixed time (1h). The

F. H. El-Batal; E. M. A. Khalil; Y. M. Hamdy; H. M. Zidan; M. S. Aziz; A. M. Abdelghany

2010-01-01

52

Electrochemical Oxidation of Barrier-Layer Metals.  

National Technical Information Service (NTIS)

As it is well known, The oxide films which possess rectified conductivity in electrolytes are the barrier-layer metals. They include aluminum, tantalum, niobium, zirconium and certain other metals.. Silicon and certain semi metals possess analogous proper...

I. S. Zhukova L. L. Odynets

1964-01-01

53

Sacrificial oxide etching compatible with aluminum metallization  

Microsoft Academic Search

This paper reports on sacrificial oxide etching with very high selectivity to aluminum metallization using mixtures of 73% HF and IPA. Etch rate ratios up to 680 have been achieved even for (slow etching) thermal oxide. Thermal oxide etch rates up to 1.8 ?m\\/min. are reported. Thick polysilicon accelerometers with aluminum metallization and thermal sacrificial oxide have been made as

P. T. J. Gennissen; P. J. French

1997-01-01

54

Oxidation and reduction in irradiated binary crystals of resorcinol and progesterone  

SciTech Connect

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

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

1985-12-01

55

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

56

Studies of catalytic aerobic oxidation with nanostructured amorphous metals, alloys and metal oxides  

Microsoft Academic Search

The oxidation of cyclohexane with molecular oxygen in the presence of isobutyraldehyde catalyzed by nanostructured iron and cobalt oxides and iron oxide supported on titania has been studied. It was found that highly dispersed transi- tion metal oxide is more effective for oxidation than the corresponding zero-valent metal powders. Nanostructured cobalt oxide on MCM-41 is found to be efficient for

J. Indian; V. K ESAVANa; D. DHAR; Y. KOLTYPIN; N. PERKAS; A. GEDANKEN; S. CHANDRASEKARAN

57

Reaction experiments for thermochemical water-splitting. [Classes of cycles: metal-metal oxide; metal oxide-metal hydroxide; metal oxide-metal sulfate; metal-metal halide; metal oxide-metal halide  

Microsoft Academic Search

Almost all known pure thermochemical hydrogen production cycles can be grouped into five generic classes, each involving either a metal oxide or a metal halide as an intermediate. In general, those cycles with the highest-temperature endothermic reactions and the least number of reactions are the most efficient. This is expected because thermochemical cycles are special types of heat engines. The

J. Gahimer; J. Pangborn; S. Foh; M. Mazumder; R. Stotz

1976-01-01

58

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

NASA Astrophysics Data System (ADS)

Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co3O4, ZnO, Mn2O3, MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N2, whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N2. Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N2 and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H2 and CO2 adsorption properties depending on the environment used for the thermolysis of MOFs.Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co3O4, ZnO, Mn2O3, MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N2, whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N2. Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N2 and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H2 and CO2 adsorption properties depending on the environment used for the thermolysis of MOFs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10944h

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

2012-01-01

59

Ammonia release method for depositing metal oxides  

DOEpatents

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

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

1994-12-13

60

Melt-Grown Oxide-Metal Composites.  

National Technical Information Service (NTIS)

This research is designed to develop melt-grown oxide-metal composite structures for high field electron emission testing. A number of refractory oxide-metal mixtures (i.e. UO2-W, stabilized ZrO2 and HfO2-W, UO2-Ta, and the rare earth oxides of Gd2O3, Nd2...

A. T. Chapman J. F. Benzel J. K. Cochran R. K. Feeney F. W. Long

1973-01-01

61

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

PubMed

Herein, for the first time, we report a generalized strategy for the successful synthesis of highly crystalline metal and metal oxide nanoparticles embedded in a carbon matrix by the controlled thermolysis of metal organic frameworks (MOFs). The rationalized synthesis strategy of a broad range of metal and metal oxides nanoparticles, such as Cu/CuO, Co/Co(3)O(4), ZnO, Mn(2)O(3), MgO and CdS/CdO, by thermolysis of MOFs demonstrates for the first time that metal ions with a reduction potential of -0.27 volts or higher present in MOFs always form pure metal nanoparticles during thermolysis in N(2), whereas metal ions with a reduction potential lower than -0.27 volts form metal oxide nanoparticles during thermolysis in N(2). Another point of interest is the fact that we have found a unique relationship between the nanoparticle size and the distance between the secondary building units inside the MOF precursors. Interestingly, the crystallinity of the carbon matrix was also found to be greatly influenced by the environment (N(2) and air) during thermolysis. Moreover, these nanoparticles dispersed in a carbon matrix showed promising H(2) and CO(2) adsorption properties depending on the environment used for the thermolysis of MOFs. PMID:22143166

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

2011-12-06

62

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

63

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

PubMed

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

Ahmady-Asbchin, Salman; Jafari, Naser

2013-01-01

64

Activity and diffusion of metals in binary aluminum alloys  

SciTech Connect

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

Jao, C. S.

1980-12-01

65

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

66

Photoemissive properties of binary magnesium-barium and aluminium-lithium metallic alloys  

NASA Astrophysics Data System (ADS)

The photoemissive properties of binary Mg-Ba and Al-Li metallic alloys, suitable as high-current photocathodes, were studied. The photoelectron energy-distribution curves and the quantum yield's spectral characteristics are presented for these materials. The concept of forming the advanced photoemissive properties for metallic solid solutions and heterophase alloys is suggested.

Tkachenko, V. G.; Maksimchuk, I. N.; Shklover, V. V.; Katrich, G. A.; Klimov, V. V.

1996-03-01

67

Calculation of diffusion in a binary powder mixture of metals with limited mutual solubility  

Microsoft Academic Search

The case is analyzed of diffusion in a binary mixture of metals whose mutual solubility leads to the formation of two phases, one on the base of each of the metals. A powder-mixture model in the form of two concentric spheres is employed, and it is assumed that the “lean” component is present in the mixture as spherical inclusions and

A. I. Raichenko

1968-01-01

68

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

69

Three-electrode metal oxide reduction cell  

DOEpatents

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

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

2008-08-12

70

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

Microsoft Academic Search

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

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

2002-01-01

71

Oxidation of metals and associated mass transport  

SciTech Connect

These proceedings collect papers on metal oxidation. Topics include: the effect of reactive elements on cation self-diffusion, stresses in oxide films, cracking, spalling, AES, XPS, RBS, NRA and Laser Raman studies of corrosion, and the effect of yttrium ion implantation on oxide growth kinetics.

Dayananda, M.A.; Rothman, S.J.; King, W.E.

1987-01-01

72

Morphological and microchemical phenomena in the high-temperature oxidation of binary Al-Li alloys  

Microsoft Academic Search

The high-temperature oxidation behavior of binary Al-Li alloys has been characterized by scanning electron microscopy and secondary ion mass spectrometry in order to understand the mechanism of rapid oxidation in these alloys and to correlate the oxide morphology to its microchemistry. The oxide scale developed on polished specimens during short exposures in air at 530°C shows characteristic nodules that usually

K. K. Soni; D. B. Williams; J. M. Chabala; R. Levi-Setti; D. E. Newbury

1991-01-01

73

The Chromospheric Activity, Age, Metallicity, and Space Motions of 36 Wide Binaries  

NASA Astrophysics Data System (ADS)

We present the chromospheric activity (CA) levels, metallicities, and full space motions for 41 F, G, K, and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries contain a white dwarf (WD) component. In such binaries, the total age can be estimated by adding the cooling age of the WD to an estimate of the progenitor's main-sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that, in general, CA decays with age from 50 Myr to at least 8 Gyr for stars with 1.0 <= V - I <= 2.4. However, little change occurs in the CA level for stars with V - I < 1.0 between 1 Gyr and 5 Gyr, consistent with the results of Pace et al. Our sample also exhibits a negative correlation between the stellar age and metallicity, a positive correlation between the stellar age and W space velocity component, and the W velocity dispersion increases with age. Finally, the population membership of these wide binaries is examined based upon their U, V, W kinematics, metallicity, and CA. We conclude that wide binaries are similar to field and cluster stars in these respects. More importantly, they span a much more continuous range in age and metallicity than is afforded by nearby clusters.

Zhao, J. K.; Oswalt, T. D.; Rudkin, M.; Zhao, G.; Chen, Y. Q.

2011-04-01

74

A new approach to estimate refractive index, electronic polarizability, and optical basicity of binary oxide glasses  

NASA Astrophysics Data System (ADS)

In this paper, we introduce the optical electronegativity ??glass* to predict basic properties of binary oxide glasses. Optical electronegativity ??glass* of numerous binary oxide glasses has been evaluated on the basis of two different properties: the linear refractive index n and energy gap Eg, which have demonstrated remarkable correlation. Furthermore, we also calculate the refractive index n through the energy-gap-based optical electronegativity ??E*, and obtain a perfect linear correlation between the calculated refractive index ncal and the n0 values of Dimitrov and Komatsu. The average electronic oxide polarizability ? and the optical basicity ? of binary oxide glasses have been estimated on the basis of the optical electronegativity ??glass* calculated from the refractive index n. The estimated values are in good agreement with the available experimental data. The present method needs only one original experimental parameter to estimate the optical electronegativity ??glass*, which is the refractive index n.

Zhao, Xinyu; Wang, Xiaoli; Lin, Hai; Wang, Zhiqiang

2008-07-01

75

Chiral thin films of metal oxide.  

PubMed

In this paper, we describe for the first time the synthesis of new chiral nanosized metal oxide surfaces based on chiral self-assembled monolayers (SAMs) coated with metal oxide (TiO2) nanolayers. In this new type of nanosize chiral surface, the metal oxide nanolayers enable the protection of the chiral self-assembled monolayers while preserving their enantioselective nature. The chiral nature of the SAM/TiO2 films was characterized by variety of unique techniques, such as second-harmonic generation circular dichroism (SHG-CD), quartz crystal microbalance, and chiral adsorption measurements with circular dichroism spectroscopy. The chiral resolution abilities of the SAMs coated with metal oxide (TiO2) nanolayers were investigated in the crystallization of a racemic mixture of threonine and glutamic acid. Our proposed methodology for the preparation of nanoscale chiral surfaces described in this article could open up opportunities in other fields of chemistry, such as chiral catalysis. PMID:23794366

Moshe, Hagay; Vanbel, Maarten; Valev, Ventsislav Kolev; Verbiest, Thierry; Dressler, David; Mastai, Yitzhak

2013-06-21

76

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

77

Process for etching mixed metal oxides  

DOEpatents

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

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

1994-10-18

78

Process for etching mixed metal oxides  

DOEpatents

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

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

1994-01-01

79

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

80

Building porosity in metal oxide ceramics  

Microsoft Academic Search

The authors have demonstrated that with neutral pH hydrolysis only the alkoxide ligands of carboxylate-modified silicon and nonsilicon metal alkoxide compounds undergo hydrolysis; the modifying ligand is retained in the coordination sphere of the metal. Subsequent acid-induced hydrolysis removed the carboxylate template and created pores. Selective removal of one component of a mixed metal oxide or the introduction of a

M. Hampden-Smith; C. Roger

1993-01-01

81

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 containment vessel is enclosed within an aqueous atmosphere that is above the supercritical temperature and pressure of the solvent of the metal alkoxide solution.

Coronado, Paul R. (Livermore, CA)

1999-01-01

82

Enhanced absorption metal oxides for photocatalytic applications  

Microsoft Academic Search

Environmental pollution and industrialization on a global scale has drawn attention to the vital need for developing new hygienic and environmentally friendly purification technologies. The most common indoor and outdoor purification process have their corresponding limitations of electricity and\\/or other energy sources. To address such enormous tasks, advance oxidation technology like heterogeneous photocatalytic systems via metal oxide semiconductors such as

Reenamole Georgekutty

2009-01-01

83

Metals and lipid oxidation. Contemporary issues  

Microsoft Academic Search

Lipid oxidation is now recognized to be a critically important reaction in physiological and toxicological processes as well\\u000a as in food products. This provides compelling reasons to understand what causes lipid oxidation in order to be able to prevent\\u000a or control the reactions. Redox-active metals are major factors catalyzing lipid oxidation in biological systems. Classical\\u000a mechanisms of direct electron transfer

K. M. Schaich

1992-01-01

84

Oxidation-reduction reactions of metal ions.  

PubMed Central

Several metal or metalloid ions exist in multiple oxidation states and can undergo electron transfer reactions that are important in biological and environmental systems. There are endogenous metal ions such as iron, copper, and cobalt that participate in oxidation-reduction reactions with species of oxygen like molecular dioxygen, superoxide, and hydrogen peroxide. These reactions may be modulated by endogenous reducing agents such as glutathione, ascorbate, and tocopherol. The reactions can be described in terms of thermodynamics through the use of standard electrode potentials. A favorable reaction will depend on the concentrations of the reactants and may depend on the pH and/or on the presence of organic ligands that form complexes with the metal or metalloid. Arsenate (As(V)) can react with glutathione in buffered aqueous solutions to produce arsenite (As(III)) and oxidized glutathione. This reaction may be important in the methylation reactions of arsenic. Arsenic species can decrease the red blood cell levels of reduced glutathione, but the products of oxidation and the mechanism of oxidation are more complex than those found in water alone. Chromium (VI) is thought to interact with DNA after first reacting with a reducing agent such as glutathione to form lower oxidation states of chromium. These examples illustrate the importance of oxidation-reduction reactions for toxic metals and metalloids.

Carter, D E

1995-01-01

85

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part II: Binary Systems With Sb2O3 and KNO3 as Oxidants  

Microsoft Academic Search

Abstract–Studies of binary Si\\/oxidant pyrotechnic systems have been extended by examination of the temperature profiles of Si\\/Sb2O3 and Si\\/KNO3 compositions.The burning rates of the Si\\/2O3 compositions (1.6 10 8.5 mm s) showed a maximum at ?40% Si. Maximum heat of reaction was measured at ?25% silicon. The temperature profiles showed a smooth rise to maximum temperatures of ?1000 to 1300°C,

R. Anil Rugunanan; Michael E. Brown

1993-01-01

86

Removal of tetracycline from water by Fe-Mn binary oxide.  

PubMed

Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments. A series of Fe-Mn binary oxide with different Fe:Mn molar ratios was synthesized by a simultaneous oxidation and coprecipitation process for TC removal. Results showed that Fe-Mn binary oxide had higher removal efficiency than that of hydrous iron oxide and hydrous manganese oxide, and that the oxide with a Fe:Mn molar ratio of 5:1 was the best in removal than other molar ratios. The tetracycline removal was highly pH dependent. The removal of tetracycline decreased with the increase of initial concentration, but the absolute removal quantity was more at high concentration. The presence of cations and anions such as Ca2+, Mg2+, CO3(2-) and SO4(2-) had no significant effect on the tetracycline removal in our experimental conditions, while SiO3(2-) and PO4(3-) had hindered the adsorption of tetracycline. The mechanism investigation found that tetracycline removal was mainly achieved by the replacement of surface hydroxyl groups by the tetracycline species and formation of surface complexes at the water/oxide interface. This primary study suggests that Fe-Mn binary oxide with a proper Fe:Mn molar ratio will be a very promising material for the removal of tetracycline from aqueous solutions. PMID:22655383

Liu, Huijuan; Yang, Yang; Kang, Jin; Fan, Maohong; Qu, Jiuhui

2012-01-01

87

Trends in the elastic response of binary early transition metal nitrides  

NASA Astrophysics Data System (ADS)

Motivated by an increasing demand for coherent data that can be used for selecting materials with properties tailored for specific application requirements, we studied elastic response of nine binary early transition metal nitrides (ScN, TiN, VN, YN, ZrN, NbN, LaN, HfN, and TaN) and AlN. In particular, single-crystal elastic constants, Young's modulus in different crystallographic directions, polycrystalline values of shear and Young's moduli, and the elastic anisotropy factor were calculated. Additionally, we provide estimates of the third order elastic constants for the ten binary nitrides.

Holec, David; Friák, Martin; Neugebauer, Jörg; Mayrhofer, Paul H.

2012-02-01

88

Charging Phenomena at the Metal Oxide–Liquid Metal Interfaces and Determination of Excess Electron Density of Metal Oxide–Mercury Systems by the Induced emf Method  

Microsoft Academic Search

Interfacial charge in a metal oxide–liquid metal system is mainly due to the electron transfer between two phases. Many metal oxides accompany electronic defects, such as quasi-free electrons or holes in their lattices. When those oxides are brought into contact with a liquid metal, electrons in the oxide may transfer to the liquid metal phase, giving rise to an electrical

Young Hyun Paik; Jang H. Pan; Wu J. Yoon

2001-01-01

89

Metal-Metal Oxide Nanoomposite for Solar Cell Applications  

NASA Astrophysics Data System (ADS)

Currently, there is a large need for alternative energies and one good option is solar cells. A High efficiency solar cell generally consists of a number of thin layers: active layer consisting of a material having high absorption in the solar spectrum, transparent conducting layer, p- and n-type materials used to fabricate the junction, and electrodes for good Ohmic contacts. The presence of metal nanoparticles in metal oxide films improves significantly the solar absorbance of metal oxide films. The absorption depends on the bandgap of metal oxides which can be tuned by incorporation of metal nanoparticles. Tuning of the bandgap and absorption are the very important parameters to fabricate the solar cell devices. Thin films of M-MO (M = transition metals Co and Ni) nanocomposite have been grown on quartz substrate using pulse laser deposition technique. Structural properties have been characterized using X-ray diffraction and scanning electron microscopy. Electrical properties with and without light and absorption spectra have been measured using I-V characterization and UV-VIS spectroscopy techniques. Detailed results will be discussed in the presentation.

Gemar, H.; Ghosh, K.

2012-02-01

90

Ion Beam Mixing in Binary Amorphous Metallic Alloys.  

National Technical Information Service (NTIS)

Ion beam mixing (IM) was measured in homogeneous amorphous metallic alloys of Cu-Er and Ni-Ti as a function of temperature using tracer impurities, i.e., the so-called ''marker geometry''. In Cu-Er, a strong temperature dependence in IM was observed betwe...

H. Hahn R. S. Averback T. Diaz de la Rubia P. R. Okamoto

1985-01-01

91

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing 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

92

Magnetic binary oxide particles (MBOP): A promising adsorbent for removal of As (III) in water  

Microsoft Academic Search

Magnetic binary oxide particles (MBOP) synthesized using chitosan template has been investigated for uptake capacity of arsenic (III). Batch experiments were performed to determine the rate of adsorption and equilibrium isotherm and also effect of various rate limiting factors including adsorbent dose, pH, optimum contact time, initial adsorbate concentration and influence of presence cations and anions. It was observed that

Rajesh M. Dhoble; Sneha Lunge; A. G. Bhole; Sadhana Rayalu

2011-01-01

93

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

94

Interfacial tension between immiscible liquids in alkaline earth – boron oxide binary systems  

Microsoft Academic Search

Liquid immiscibility is common in glass-forming oxide melts, and interfacial tension between the conjugate liquid phases is an important property that determines the kinetics of phase separation. Here we present, to the best of our knowledge, the first experimental measurements of interfacial tension between immiscible melts in the alkaline earth – boron oxide binary systems; MgO-B2O3, CaO-B2O3 and BaO-B2O3. We

Ilya V. Veksler; Johannes Kähn; Donald B. Dingwell

2010-01-01

95

Wide metal-poor binaries BVRI photometry (Zapatero Osorio+, 2004)  

NASA Astrophysics Data System (ADS)

Observing dates, differential photometry and astrometry (rho and position angle) of companion candidates around 473 nearby, low-metallicity G- to M-type stars are provided in the Table. The target stars were mainly taken from the Carney-Latham surveys. Also provided are exposure times, the FWHM of the CCD images, and the telescope used for collecting the observations. The last column contains a flag indicating whether the candidate is a confirmed physical companion. (2 data files).

Zapatero Osorio, M. R.; Martin, E. L.

2004-04-01

96

Regeneration of sulfated metal oxides and carbonates  

DOEpatents

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

Hubble, Bill R. (Plainfield, IL); Siegel, Stanley (Downers Grove, IL); Cunningham, Paul T. (Naperville, IL)

1978-03-28

97

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

98

Metal oxide powder synthesized with amorphous metal chelates  

Microsoft Academic Search

Chelate powder consisting of amorphous particles was synthesized through the process in which the droplet of the chelate solution is dried in the gas phase and solidified in a moment using a splay-dry technique. To investigate the advantage of the use of amorphous chelate powder in the processing of metal oxide powder, this study provides following two routes: a conventional

H. Saitoh; R. Satoh; A. Nakamura; N. Nambu; S. Ohshio

2002-01-01

99

Uranium Metal to Oxide Conversion by Air Oxidation ?Process Development  

SciTech Connect

Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

Duncan, A

2001-12-31

100

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

101

Simulating Structure, Magnetism and Electronic Properties of Monoatomic, Binary and Ternary Transition Metal Nanoclusters  

Microsoft Academic Search

Based on large-scale molecular dynamics and density functional theory calculations, we provide some insight into morphological, magnetic and electronic changes of monoatomic (Fe), binary (Fe-Pt) and ternary (Ni-Mn-Ga) transition metal clusters with the size of the clusters. For Fe, the magnetic order is shown to influence the cluster growth and to stabilize the bcc like structure already for small cluster

P. Entel; M. E. Gruner; A. Hucht; R. Meyer; G. Rollmann; S. Sahoo; S. K. Nayak

2008-01-01

102

Kinetic Parameters of Binary Iron\\/Oxidant Pyrolants  

Microsoft Academic Search

The thermal properties of pyrotechnic mixtures containing iron powder as fuel and KNO3, KClO3, and KClO4 as oxidants are reported. The thermogravimetry–differential thermal analysis results for pure components and corresponding pyrotechnic mixtures revealed that the melting point, decomposition temperature, and rate of oxygen releasing of the oxidants have dominant effects on ignition reaction of the pyrotechnic mixtures. The apparent activation

Mojtaba Shamsipur; Seied Mahdi Pourmortazavi; Manochehr Fathollahi

2012-01-01

103

Magnetic correlations in doped transition metal oxides.  

National Technical Information Service (NTIS)

The authors review recent reactor- and spallation-source-based neutron scattering experiments on the magnetic fluctuations and order in a variety of doped transition metal oxides. In particular, data are shown for the NiO chain compound, Y(sub 2(minus)x)C...

G. Aeppli W. Bao C. Broholm

1995-01-01

104

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

105

Lithium Metal Oxide Electrodes for Lithium Batteries.  

National Technical Information Service (NTIS)

An uncycled preconditioned 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 < or = x < 1 and delta is less than 0....

C. S. Johnson K. Amine M. M. Thackeray S. H. Kang

2006-01-01

106

Metal foam stabilization by oxide network particles  

Microsoft Academic Search

The fundamental stabilization mechanism for foaming metal powder compacts (PM foams) is investigated. It is shown that PM foams belong to the class of stable foams where the stability is controlled by the balance of interfacial forces which equilibrate after drainage has been completed. The origin of these interfacial forces is traced back to the oxide content of the underlying

Carolin Körner; Michael Arnold; Robert F. Singer

2005-01-01

107

Reactor process using metal oxide ceramic membranes  

DOEpatents

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

Anderson, M.A.

1994-05-03

108

Reactor process using metal oxide ceramic membranes  

DOEpatents

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

Anderson, Marc A. (Madison, WI)

1994-01-01

109

Galvanic replacement reactions in metal oxide nanocrystals.  

PubMed

Galvanic replacement reactions provide a simple and versatile route for producing hollow nanostructures with controllable pore structures and compositions. However, these reactions have previously been limited to the chemical transformation of metallic nanostructures. We demonstrated galvanic replacement reactions in metal oxide nanocrystals as well. When manganese oxide (Mn3O4) nanocrystals were reacted with iron(II) perchlorate, hollow box-shaped nanocrystals of Mn3O4/?-Fe2O3 ("nanoboxes") were produced. These nanoboxes ultimately transformed into hollow cagelike nanocrystals of ?-Fe2O3 ("nanocages"). Because of their nonequilibrium compositions and hollow structures, these nanoboxes and nanocages exhibited good performance as anode materials for lithium ion batteries. The generality of this approach was demonstrated with other metal pairs, including Co3O4/SnO2 and Mn3O4/SnO2. PMID:23704569

Oh, Myoung Hwan; Yu, Taekyung; Yu, Seung-Ho; Lim, Byungkwon; Ko, Kyung-Tae; Willinger, Marc-Georg; Seo, Dong-Hwa; Kim, Byung Hyo; Cho, Min Gee; Park, Jae-Hoon; Kang, Kisuk; Sung, Yung-Eun; Pinna, Nicola; Hyeon, Taeghwan

2013-05-24

110

Local oxidation of metal and metal nitride films  

NASA Astrophysics Data System (ADS)

Oxide growth on sputter-deposited thin films is studied on the local scale by atomic force microscope (AFM)-assisted lithography. We investigate the group IV reactive metals Zr, Hf, Ti, and their nitrides. The nitrogen content of the deposition plasma affects the film crystal structure and electrical resistivity, which in turn alter the local oxidation rates. Mass transport plays an important role, producing features with heights ranging from a few nanometers up to hundreds of nanometers. The heights of the largest features are one to two orders of magnitude greater than observed in other material systems, and the growth is well controlled. We use various techniques to investigate the solid-state reaction and transport mechanisms involved in this oxidation driven by a highly localized electric field. Our results demonstrate the potential of AFM lithographic techniques for characterizing oxidation processes across a wide range of time and length scales. .

Farkas, N.; Tokash, J. C.; Zhang, G.; Evans, E. A.; Ramsier, R. D.; Dagata, J. A.

2004-07-01

111

Removal of Anionic and Cationic Dyes From Water by FeAl Binary Oxide  

Microsoft Academic Search

Al was incorporated in iron oxide to enhance dye removal capacity (Fe-Al binary oxide). Oxides with different Fe:Al ratios(10:0, 9:1, 7:3, 5:5, 3:7, 1:9 and 0:10) were synthesized and applied for removal of organic dyes. Increase of incorporated Al expanded effective surface area that could contact with dye. The highest dye removal efficiency was achieved by 5:5 and 3:7 Fe:Al

Hye-Jin Hong; Jungmin Kim; Jung-Seok Yang; Eun Jung Kim; Ji-Won Yang

2012-01-01

112

Quantum Criticality in Transition-Metal Oxides  

NASA Astrophysics Data System (ADS)

We report on experiments of the bulk susceptibility ?( T), heat capacity C( T)/ T, resistivity ?( T) and nuclear resonances (NMR and NQR) in order to review evidence of quantum critical behaviour in some metallic transition-metal oxides. In analogy to the conventional 4 f- and 5 f-electron based heavy-fermion compounds, the prerequisites of quantum criticality, i.e. a magnetic phase transition at T=0 accompanied by non-Fermi liquid behaviour, are observed in LiV2O4 which was the first transition-metal oxide showing heavy-fermion properties. Furthermore, we investigate the large group of copper-ruthenates of the composition ACu3Ru x Ti4- x O12 which also demonstrate heavy-fermion and non-Fermi liquid properties. For LaCu3Ru x Ti4- x O12 we establish a magnetic phase diagram where the substitution of titanium by ruthenium cations suppresses long-range magnetic order in favour of a magnetic quantum critical point, which comes along with a metal-to-insulator transition. Our experiments elucidate open questions concerning the nature of the heavy-fermion properties, intermediate valence, and the origin of the metal-to-insulator transition. Specifically, the role of the ruthenium and copper d-electrons is addressed: the metal-to-insulator transition turns out to correlate with the increasing itinerancy of local moments at the Cu site in our doping experiments.

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

2010-10-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2003-07-01

114

Method for converting uranium oxides to uranium metal  

Microsoft Academic Search

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

Duerksen; Walter K

1988-01-01

115

Method for Converting Uranium Oxides to Uranium Metal.  

National Technical Information Service (NTIS)

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...

W. K. Duerksen

1987-01-01

116

40 CFR 721.5549 - Lithiated metal oxide.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

117

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

118

40 CFR 721.4610 - Mixed metal oxides (generic).  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

119

40 CFR 721.10006 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.10006 Section...Chemical Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance...substance identified generically as mixed metal oxide (PMN P-99-511) is...

2013-07-01

120

40 CFR 721.5548 - Mixed metal oxide (generic).  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

121

First principles theory of metal-oxide interfaces: the Schottky-Mott theory revisited  

NASA Astrophysics Data System (ADS)

Using calculations from first principles, we discuss the interplay between structure and functionality at metal-insulator interfaces using the paradigmatic example of the junctions between various metals (Ag, Pd,Pt,Ni,Cu,Al) and binary crystalline oxides (BaO,CaO and SrO). Our results demonstrate that it is possible to tune the Schottky barrier height in a very broad range of values just manipulating the metal at the interface and elucidate the role of the relative overlap in the density of states of the different components in determining the band alignment. We will also show how we can apply this concepts to interfaces between metals and ferroelectric oxides where the interface structure and charge transfer affect the spontaneous polarization of the ferroelectric.

Nunez, Matias; Buongiorno Nardelli, Marco

2006-03-01

122

Chemisorption and the electronic structure of transition metal oxides and transition metals bonded to oxide surfaces  

Microsoft Academic Search

Some simple transition metal oxides such as NiO have incomplete atomic subshells and yet are highly insulating. This implies a high degree of electronic localization and also indicates that the chemical bonds are saturated. In this respect these oxides are similar to alkaline earth oxides such as MgO. The analogy extends to their surface properties. MgO and NiO, for example,

A. Barry Kunz

1985-01-01

123

Arsenate uptake and arsenite simultaneous sorption and oxidation by Fe-Mn binary oxides: influence of Mn/Fe ratio, pH, Ca2+, and humic acid.  

PubMed

Arsenate retention, arsenite sorption and oxidation on the surfaces of Fe-Mn binary oxides may play an important role in the mobilization and transformation of arsenic, due to the common occurrence of these oxides in the environment. However, no sufficient information on the sorption behaviors of arsenic on Fe-Mn binary oxides is available. This study investigated the influences of Mn/Fe molar ratio, solution pH, coexisting calcium ions, and humic acids have on arsenic sorption by Fe-Mn binary oxides. To create Fe-Mn binary oxides, simultaneous oxidation and co-precipitation methods were employed. The Fe-Mn binary oxides exhibited a porous crystalline structure similar to 2-line ferrihydrite at Mn/Fe ratios 1:3 and below, whereas exhibited similar structures to ?-MnO(2) at higher ratios. The As(V) sorption maximum was observed at a Mn/Fe ratio of 1:6, but As(III) uptake maximum was at Mn/Fe ratio 1:3. However, As(III) adsorption capacity was much higher than that of As(V) at each Mn/Fe ratio. As(V) sorption was found to decrease with increasing pH, while As(III) sorption edge was different, depending on the content of MnO(2) in the binary oxides. The presence of Ca(2+) enhanced the As(V) uptake under alkaline pH, but did not significantly influence the As(III) sorption by 1:9 Fe-Mn binary oxide; whereas the presence of humic acid slightly reduced both As(V) and As(III) uptake. These results indicate that As(III) is more easily immobilized than As(V) in the environment, where Fe-Mn binary oxides are available as sorbents and they represent attractive adsorbents for both As(V) and As(III) removal from water and groundwater. PMID:22014399

Zhang, Gaosheng; Liu, Huijuan; Qu, Jiuhui; Jefferson, William

2011-10-01

124

Pillared Clay-Supported Noble Metal and Metal Oxide Catalysts for Complete Oxidation of VOCs  

NASA Astrophysics Data System (ADS)

Pillared clays (PILCs) have porous structure, high surface area, special surface acidity, and thermal stability. Due to their properties, PILCs are very suitable to be used as support for active catalytic phases in the preparation of supported catalysts, and the resulting solids can be applied in several reactions, particularly in environmental-friendly reactions. Volatile organic compounds (VOCs) have contributed significantly to air pollution. The deep catalytic oxidation of these pollutants has been identified as one of the most efficient ways to destroy VOCs. This review examines recent developments in the complete oxidation of VOCs over PILC-supported noble metal and metal oxide catalysts.

Zuo, Shufeng; Huang, Qinqin; Zhou, Renxian

125

Practical performance and its efficiency of arsenic removal from groundwater using Fe-Mn binary oxide  

Microsoft Academic Search

A treatment unit packed by granular adsorbent of Fe-Mn binary oxide incorporated into diatomite (FMBO(1:1)-diatomite) was studied to remove arsenic from anaerobic groundwater without any pre-treatment or post-treatment. The raw anaerobic groundwater containing 35–45 ?g\\/L of arsenic was collected from suburb of Beijing. Arsenic(III) constituted roughly 60%–80% of the total arsenic content. Approximately 7,000 bed volumes (ratio of effluent volume

Fangfang Chang; Jiuhui Qu; Ruiping Liu; Xu Zhao; Pengju Lei

2010-01-01

126

Stellar evolution at low metallicity under the influence of binary interaction and rotation  

NASA Astrophysics Data System (ADS)

The chapters of this thesis have been published in the following journals. Ch. 2: "Fluorine in carbon-enhanced metal-poor stars: a binary scenario", Astronomy and Astrophysics Letters, 484, 27, 2008, M. Lugaro, S.E. de Mink, R.G. Izzard, S.W. Campbell, A. I. Karakas, S. Cristallo, O.R. Pols, J.C. Lattanzio, O. Straniero, R. Gallino, and T.C. Beers Ch. 3: "Efficiency of mass transfer in massive close binaries. Tests from double-lined eclipsing binaries in the SMC", Astronomy and Astrophysics, 467, 1181, 2007, S.E. de Mink, O.R. Pols, and R.W. Hilditch Ch. 4: "Rotational mixing in massive binaries: detached short-period systems", Astronomy and Astrophysics 497, 243, 2009, S.E. de Mink, M. Cantiello, N. Langer and O.R. Pols, I. Brott and S.-Ch Yoon Ch. 5: "Massive binaries as the source of globular cluster abundance patterns", Astronomy and Astrophysics Letters, 507, 1, 2009, S.E. de Mink, O.R. Pols, N. Langer, R.G. Izzard Ch. 6: "The Effect of Stellar Rotation on Colour-Magnitude Diagrams: On the apparent presence of multiple populations in intermediate age stellar clusters", Monthly Notices of the Royal Astronomical Society Letters 398, 11, 2009, N. Bastian and S.E. de Mink Ch. 7: "The evolution of runaway stellar collision products", Astronomy and Astrophysics, 497, 255, 2009. E. Glebbeek, E. Gaburov, S.E. de Mink, O.R. Pols, and S.F. Portegies Zwart

de Mink, S. E.

2010-04-01

127

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

PubMed

We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide. PMID:19928255

Singh, Dinesh Pratap; Srivastava, Onkar Nath

2009-09-01

128

Topological Crystalline Insulators in Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

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 Pb1-xSnxTe, 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.

Kargarian, Mehdi; Fiete, Gregory A.

2013-04-01

129

Reactivity of aluminum nanopowders with metal oxides  

Microsoft Academic Search

During the past few years, significant progress has been made in research of the formation of nanopowders and their application in both civilian and military sectors. One example of such an application is the development of nanoscale energetic materials. This paper presents the recent experimental studies of ultra-fast reactions between nanosized aluminum and various metal oxides, including WO3, MoO3, CuO,

S. Valliappan; J. Swiatkiewicz; J. A. Puszynski

2005-01-01

130

Electrolysis of water on (oxidized) metal surfaces  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

131

Removal of metallic iron on oxide slags  

SciTech Connect

It is possible, in some cases, for ground coal particles to react with gasifier gas during combustion, allowing the ash material in the coal to form phases besides the expected slag phase. One of these phases is metallic iron, because some gasifiers are designed to operate under a reducing atmosphere (pO{sub 2}) of approximately 10{sup -4} atm). Metallic iron can become entrained in the gas stream and deposit on, and foul, downstream equipment. To improve the understanding of the reaction between different metallic iron particles and gas, which eventually oxidizes them, and the slag that the resulting oxide dissolves in, the kinetics of iron reaction on slag were predicted using gas-phase mass-transfer limitations for the reaction and were compared with diffusion in the slag; the reaction itself was observed under confocal scanning laser microscopy. The expected rates for iron droplet removal are provided based on the size and effective partial pressure of oxygen, and it is found that decarburization occurs before iron reaction, leading to an extra 30- to 100-second delay for carbon-saturated particles vs pure iron particles. A pure metallic iron particle of 0.5 mg should be removed in about 220 seconds at 1400{sup o}C and in 160 seconds at 1600{sup o}C.

Shannon, G.N.; Fruehan, R.J.; Sridhar, S. [Carnegie Mellon University, Pittsburgh, PA (United States). Dept. of Material Science & Engineering

2009-10-15

132

Methanol oxidation over nonprecious transition metal oxide catalysts  

SciTech Connect

This paper reports methanol oxidation over nonprecious transition metal oxide catalysts studied in a gradient less external recycle reactor. The catalysts (oxides of Cr, Mn, Fe, Co, Ni, Cu), which were prepared by using the incipient wetness technique, were supported on 1/8 in.{gamma}-Al{sub 2}O{sub 3} tablets. The catalysts were characterized by using BET surface area measurement, X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis techniques. All the catalysts exhibited similar activities for methanol conversion, but the Cu catalyst was found to be considerably more selective to CO{sub 2}. The order of the reaction was 1.2 with respect to methanol concentration and appeared to range between 0.5 and 0 with respect to oxygen concentration.

Ozkan, U.S.; Kueller, R.F.; Moctezuma, E. (Ohio State Univ., Columbus, OH (USA). Dept. of Chemical Engineering)

1990-07-01

133

Impact dynamics of oxidized liquid metal drops  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

134

Memristive switching mechanism for metal/oxide/metal nanodevices.  

PubMed

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 in 1971, and we recently showed that memristor behaviour can naturally explain such coupled electron-ion dynamics. Here we provide experimental evidence to support this general model of memristive electrical switching in oxide systems. We have built micro- and nanoscale TiO2 junction devices with platinum electrodes that exhibit fast bipolar nonvolatile switching. We demonstrate that switching involves changes to the electronic barrier at the Pt/TiO2 interface due to the drift of positively charged oxygen vacancies under an applied electric field. Vacancy drift towards the interface creates conducting channels that shunt, or short-circuit, the electronic barrier to switch ON. The drift of vacancies away from the interface annilihilates such channels, recovering the electronic barrier to switch OFF. Using this model we have built TiO2 crosspoints with engineered oxygen vacancy profiles that predictively control the switching polarity and conductance. PMID:18654568

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

2008-06-15

135

Biomarker sensing using nanostructured metal oxide sensors  

NASA Astrophysics Data System (ADS)

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

Kalyanasundaram, Krithika

136

Practical performance and its efficiency of arsenic removal from groundwater using Fe-Mn binary oxide.  

PubMed

A treatment unit packed by granular adsorbent of Fe-Mn binary oxide incorporated into diatomite (FMBO(1:1)-diatomite) was studied to remove arsenic from anaerobic groundwater without any pre-treatment or post-treatment. The raw anaerobic groundwater containing 35-45 microg/L of arsenic was collected from suburb of Beijing. Arsenic (III) constituted roughly 60%-80% of the total arsenic content. Approximately 7,000 bed volumes (ratio of effluent volume to adsorbent volume) treated water with arsenic concentration below 10 microg/L were produced in the operation period of four months. The regeneration of FMBO (1:1)-diatomite had been operated for 15 times. In the first stage, the regeneration process significantly improved the adsorption capacity of FMBO (1:1)-diatomite. With increased loading amount of Fe-Mn binary oxide, the adsorption capacity for arsenic decreased 20%-40%. Iron and manganese in anaerobic groundwater were oxidized and adsorptive filtrated by FMBO (1:1)-diatomite efficiently. The final concentrations of iron and manganese in effluents were nearly zero. The continued safe performance of the treatment units proved that adsorbent FMBO (1:1)-diatomite had high oxidation ability and exhibited strong adsorptive filtration. PMID:20397380

Chang, Fangfang; Qu, Jiuhui; Liu, Ruiping; Zhao, Xu; Lei, Pengju

2010-01-01

137

Advances in metal-induced oxidative stress and human disease  

Microsoft Academic Search

Detailed studies in the past two decades have shown that redox active metals like iron (Fe), copper (Cu), chromium (Cr), cobalt (Co) and other metals undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biological systems. Disruption of metal ion homeostasis may lead to oxidative stress, a state

Klaudia Jomova; Marian Valko

2011-01-01

138

Polymer-assisted aqueous deposition of metal oxide films  

DOEpatents

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

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

2003-07-08

139

Proposed model for calculating the standard formation enthalpy of binary transition-metal systems  

NASA Astrophysics Data System (ADS)

In this letter, we present a proposed model for calculating the standard formation enthalpy of binary transition-metal systems by adding a prefactor S(c) to the well-documented formula developed by Miedema. The main idea is to take into account the significant effect of the atomic size difference on the contact surface while two dissimilar metals approaching together. Employing this model, the standard formation enthalpies of some 260 intermetallic compounds were calculated and compared with the experimentally measured data. It was found that the precision of the calculated values by the proposed model could be improved 13%-65% and that statistically, over 95% of the calculated values were in agreement with the experimental ones within an error of plus-or-minus23 kJ/mol, while employing the Miedema's formula the agreement was about 80%.

Zhang, R. F.; Liu, B. X.

2002-08-01

140

Zeolites as transformation elements in discriminating semiconductor metal oxide sensors  

Microsoft Academic Search

The effectiveness of using zeolites as a method of introducing variance in the gas responses of semiconductor metal oxide gas sensors is demonstrated. Screen printed tungsten trioxide (WO3) and chromium titanium oxide (CTO) thick films overlaid with the hydrogen form of different zeolites were exposed to organic vapours with similar functional groups. The composite metal oxide-zeolite gas sensors responses exhibit

A. Afonja; R. Binions; S. Dungey; I. P. Parkin; D. W. Lewis; D. E. Williams

2010-01-01

141

The salting out action of alkali metal nitrates on the water-diethylamine binary system  

NASA Astrophysics Data System (ADS)

The results of a polythermal study of the salting out action of alkali metal (Na, K, and Cs) nitrates on the water-diethylamine binary system characterized by stratification with a lower critical solution point (LCSP) were comparatively analyzed. Alkali metal nitrates experiencing homoselective solvation in aqueousorganic solvents were found to decrease the LCSP of this binary system, that is, have a salting out action. A decrease in the radius of the cation in the series CsNO3-KNO3-NaNO3 decreased the temperature of critical tie line formation in the monotectic state of salt-water-diethylamine ternary systems (69.3, 48.1, and 22.9°C, respectively). In all ternary systems, first and foremost in the system with potassium nitrate, the effect of diethylamine salting out from aqueous solutions grew stronger as the temperature increased. The conclusion was drawn that, among the salts studied, sodium nitrate had the strongest salting out effect at 22.9-88.4°C, and potassium nitrate, at 88.4-150.0°C.

Il'in, K. K.; Cherkasov, D. G.; Kurskii, V. F.

2011-01-01

142

Reactive sputter deposition of metal oxide nanolaminates  

Microsoft Academic Search

We discuss the reactive sputter deposition of metal oxide nanolaminates on unheated substrates using four archetypical examples: ZrO2 Al2O3, HfO2 Al2O3, ZrO2 Y2O3, and ZrO2 TiO2. The pseudobinary bulk phase diagrams corresponding to these nanolaminates represent three types of interfaces. I. Complete immiscibility (ZrO2 Al2O3 and HfO2 Al2O3). II. Complete miscibility (ZrO2 Y2O3). III. Limited miscibility without a common end-member

Carolyn Rubin Aita

2008-01-01

143

Metal oxide membranes for gas separation  

DOEpatents

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

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

1994-01-01

144

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

145

Porous metal oxides as gas sensors.  

PubMed

Semiconducting metal oxides are frequently used as gas-sensing materials. Apart from large surface-to-volume ratios, well-defined and uniform pore structures are particularly desired for improved sensing performance. This article addresses the role of some key structural aspects in porous gas sensors, such as grain size and agglomeration, pore size or crack-free film morphology. New synthesis concepts, for example, the utilisation of rigid matrices for structure replication, allow to control these parameters independently, providing the opportunity to create self-diagnostic sensors with enhanced sensitivity and reproducible selectivity. PMID:17721888

Tiemann, Michael

2007-01-01

146

Magnetic correlations in doped transition metal oxides  

SciTech Connect

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

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

1995-02-15

147

Metal oxides as combustion catalysts for a stratified, dual bed partial oxidation catalyst  

Microsoft Academic Search

Bimetallic, dual bed catalysts made up of metal oxides were investigated in the millisecond catalytic partial oxidation of methane to synthesis gas. A metal oxide combustion catalyst containing manganese, chromium, or copper was coupled with a nickel reforming catalyst to carry out the partial oxidation of methane. These catalysts produce hydrogen yields that compare to a platinum\\/nickel dual bed catalyst

B. N. T. Nguyen; C. A. Leclerc

2007-01-01

148

Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy  

SciTech Connect

Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

Galloway, H.C.

1995-12-01

149

Pathways for Carboxylic Acid Decomposition on Transition Metal Oxides  

Microsoft Academic Search

The concept of structure sensitivity is well established for reactions catalyzed by metals as it has been generally demonstrated by the use of supported metal catalysts exhibiting different particle size [l-71. The con-cept of structure sensitivity in catalysis by metal oxides is considerably less well developed than in catalysis by metals, in spite of the growing number of examples of

Sivanandi Rajadurai

1994-01-01

150

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

SciTech Connect

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

Linden, T. [Department of Physics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Kalogera, V.; Sepinsky, J. F. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Prestwich, A.; Zezas, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gallagher, J. S. [Department of Astronomy, University of Wisconsin, Madison, WI 53706-1582 (United States)

2010-12-20

151

Thermodynamic and kinetic aspects on the selective surface oxidation of binary, ternary and quarternary model alloys  

Microsoft Academic Search

Segregation and selective oxidation phenomena of minor alloying elements during annealing of steel sheets lead to the formation of bare spots after hot dip galvanizing. In order to understand the influence of common alloying elements on the surface chemistry after annealing, model alloys of binary (Fe–2Si, Fe–2Mn and Fe–0.8Cr), ternary (Fe–2Mn–2Si, Fe–2Mn–0.8Cr and Fe–2Si–0.8Cr) and quarternary (Fe–2Mn–2Si–0.8Cr) systems were investigated.

Srinivasan Swaminathan; Michael Spiegel

2007-01-01

152

One-dimensional metal oxide nanostructures for heterogeneous catalysis  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

153

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

154

Catalytic oxidation of dichloromethane, chloroform, and their binary mixtures over a platinum alumina catalyst  

SciTech Connect

The complete catalytic oxidation of dichloromethane, chloroform, and their binary mixtures was examined over a 3% Pt/[kappa]-[delta] Al[sub 2]O[sub 3] catalyst at temperature between 300 and 400 C using a fixed bed catalytic reactor. The oxidation of chloroform and dichloromethane as pure compounds was nonlinear in the concentration of chloromethane and zeroth order in the concentration of oxygen. HCl, formed during the oxidation of each chloromethane, decreased the reaction rate. Kinetic rate expressions were developed to described the oxidation of dichloromethane and chloroform as pure compounds. These expressions were derived by assuming that the reaction occurred via adsorption and decomposition of the chloromethane into an oxygen covered platinum surface, with the reaction being inhibited by the presence of HCl. From the results of the pure compound studies, reaction rate expressions were developed to describe the oxidation of dichloromethane/chloroform mixtures. The resulting reaction rate expressions accurately predicted the catalyst's performance during the oxidation of dichloromethane/chloroform mixtures over a wide range of conditions.

Papenmeier, D.M.; Rossin, J.A. (Geo-Centers, Inc., Aberdeen Proving Ground, MD (United States). Gunpowder Branch)

1994-12-01

155

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

156

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

SciTech Connect

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

Lad, R.J.

1992-01-01

157

Surface tension of nitric oxide and its binary mixtures with krypton, methane, and ethene  

SciTech Connect

The surface tension of three binary liquid mixtures of NO with Kr, CH{sub 4}, and C{sub 2}H{sub 4} has been determined as a function of composition in the temperature range 102.0 to 119.0 K. These measurements are a contribution to the study of binary liquid mixtures in which one component is unassociated while the molecules of the other can associate between themselves. Nitric oxide is the simplest molecule capable of forming dimers, but not larger aggregates. This results in the surface tension of liquid nitric oxide having a strong temperature dependence: when the temperature increases the degree of dimerization decreases, contributing to a larger decrease of the surface tension. The surface tension of NO mixtures shows strong deviations from ideality. The mixtures containing Kr and CH{sub 4} exhibit negative deviations, while for the NO + C{sub 2}H{sub 4} system the surface tension shows a complex dependence on the composition. This strong departure from ideality had already been found for the bulk properties of these three systems. The surface tension of the CH{sub 4} + Kr system, already well characterized in the literature, was also measured to test the equipment.

Calado, J.C.G.; Santos Mendonca, A.F.S. dos; Saramago, B.J.V.; Soares, V.A.M. [Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural

1997-05-15

158

Simulating Structure, Magnetism and Electronic Properties of Monoatomic, Binary and Ternary Transition Metal Nanoclusters  

NASA Astrophysics Data System (ADS)

Based on large-scale molecular dynamics and density functional theory calculations, we provide some insight into morphological, magnetic and electronic changes of monoatomic (Fe), binary (Fe-Pt) and ternary (Ni-Mn-Ga) transition metal clusters with the size of the clusters. For Fe, the magnetic order is shown to influence the cluster growth and to stabilize the bcc like structure already for small cluster sizes. For Fe-Pt clusters up to a few nm in size, multiply-twinned structures are more favorable than the L10 phase. For not too big ternary Ni-Mn-Ga clusters, the martensitic tendency of cubic to tetragonal transformation is like in Fe-Pt hindered by surface effects, while the bigger clusters develop a bulk-like tetragonal transformation.

Entel, P.; Gruner, M. E.; Hucht, A.; Meyer, R.; Rollmann, G.; Sahoo, S.; Nayak, S. K.

2008-10-01

159

The Use of Steady Electromagnetic Fields to Control the Columnar Solidification of Binary-Metal Alloys  

NASA Astrophysics Data System (ADS)

This article considers the nondirectional solidification of a binary-metal alloy in a cylindrical cavity, which is cooled along its outer vertical wall and the bottom. To study the influence of convection within the liquid phase on the final segregation, three cases are examined: the purely buoyancy-driven convection (case 0), the impact of an external steady axial magnetic field on the melt flow during solidification (case 1), and the effect of the combination of an external magnetic field with a steady electrical current (DC) applied directly to the melt (case 2). The results show that convection in the form of multivortices caused by the thermosolutal buoyancy leads to macrosegregations in the form of V-channels. The application of an external axial magnetic field alone suppresses the multivortex structure and, thus, the macrosegregation. By contrast, the parallel use of an additional voltage of 10-3 V leads to an increase in final macrosegregation.

Nikrityuk, P. A.; Eckert, K.; Grundmann, R.

2009-06-01

160

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

161

Reactive sputter deposition of metal oxide nanolaminates  

Microsoft Academic Search

We discuss the reactive sputter deposition of metal oxide nanolaminates on unheated substrates using four archetypical examples: ZrO2–Al2O3, HfO2–Al2O3, ZrO2–Y2O3, and ZrO2–TiO2. The pseudobinary bulk phase diagrams corresponding to these nanolaminates represent three types of interfaces. I. Complete immiscibility (ZrO2–Al2O3 and HfO2–Al2O3). II. Complete miscibility (ZrO2–Y2O3). III. Limited miscibility without a common end-member lattice (ZrO2–TiO2). We found that, although reactive

Carolyn Rubin Aita

2008-01-01

162

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

SciTech Connect

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

Darsell, Jens T.; Weil, K. Scott

2010-06-09

163

Preparation of bioactive titanium metal via anodic oxidation treatment  

Microsoft Academic Search

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

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

2004-01-01

164

Chemical Reduction of Intermodulation Interference Caused by Metal-Oxide-Metal Junctions Aboard Ship.  

National Technical Information Service (NTIS)

Intermodulation interference from metal oxide metal nonlinear junctions near high frequency transmitters and receivers is suppressed effectively by application of chemical mixtures that provide an alternate, low impedance current path across the junction....

R. Hynes H. W. Carhart J. C. Cooper

1991-01-01

165

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

Microsoft Academic Search

Transition metal oxides exhibit a rich collection of electronic properties and have many practical applications in areas such as catalysis and ultra-high-density magnetic data storage. Therefore the development of switchable molecular transition metal oxides has potential for the engineering of single-molecule devices and nanoscale electronics. At present, the electronic properties of transition metal oxides can only be tailored through the

Christopher Fleming; De-Liang Long; Nicola McMillan; Jacqueline Johnston; Nicolas Bovet; Vin Dhanak; Nikolaj Gadegaard; Paul Kögerler; Leroy Cronin; Malcolm Kadodwala

2008-01-01

166

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: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

Richard T. Scalettar; Warren E. Pickett

2005-08-02

167

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

168

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

SciTech Connect

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

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

2011-03-02

169

Application of Metal Oxide Refractories for Melting and Casting Reactive Metals.  

National Technical Information Service (NTIS)

Extensive investigations have been conducted to develop metal oxide refractories for containment of molten uranium and uranium alloys. Since uranium and uranium alloys are readily susceptable to the formation of complex oxides, carbides, nitrides, interme...

A. B. Townsend C. E. Holcombe N. C. Jessen

1979-01-01

170

Negative ion photoelectron spectroscopy of metal clusters, metal-organic clusters, metal oxides, and metal-doped silicon clusters  

Microsoft Academic Search

The techniques of time-of-flight mass spectrometry and negative ion photoelectron spectroscopy were utilized to study metal clusters (Mgn -, Znn-, Can -, Mnn-, CuAln -, LiAln-, and NmSn n-), metal-organic complexes (Tin(benzene) m-, Fn(benzene)m- , Nin(benzene)m-), metal oxides(AuO-, PtO-, TaOn -, HfO2-, and MnnO -), and metal-doped semiconductor clusters (CrSin -, GdmSin- and HoSi n-). The study of magnesium and

Weijun Zheng

2005-01-01

171

Transition metal-catalyzed oxidations of bishomoallylic alcohols  

Microsoft Academic Search

In recent years, new transition metal-catalyzed reactions for chemo- and stereoselective oxidations of bishomoallylic alcohols have been developed. The role of transition metals in this catalysis is connected with (i) activation of a primary oxidant (e.g. molecular oxygen, hydrogen peroxide, or tert-butyl hydroperoxide—reactivity), (ii) direction of the alkenol oxidation into a specific reaction channel (chemoselectivity), and (iii) control of the

Jens Hartung; Marco Greb

2002-01-01

172

Microscopic model for dielectric constant in metal-insulator-metal capacitors with high-permittivity metallic oxides  

Microsoft Academic Search

A microscopic model for metal-insulator-metal (MIM) capacitors with high permittivity metallic oxides is developed to determine the electric field dependence of dielectric constant. The model indicates that the metallic cation displacement in the tetrahedral cell is at the origin of the dielectric constant variations. The temperature dependence has also been included to compare the model with experiment and to give

Ste´phane Be´cu; Se´bastien Cre´mer; Jean-Luc Autran

2006-01-01

173

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 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...

2013-07-01

174

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

175

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

176

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

177

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

NASA Astrophysics Data System (ADS)

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

Preston, George W.

1994-12-01

178

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

179

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

180

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

SciTech Connect

Studies of structural, electronic, and chemical properties of metal/oxide and oxide/oxide interfaces were performed on well-defined interfaces that created by depositing ultra-thin potassium and aluminum films and their oxides onto single crystal TiO[sub 2] and NiO surfaces. Work focused on determining the structure, growth mechanisms, and morphologies of metal and oxide films as they are deposited an single crystal oxide surfaces using RHEED and atomic force microscopy probing electronic structure, bonding and chemical interactions at the interfaces using x-ray and uv photoelectron spectroscopies (XPS, UPS) and Auger electron spectroscopy (AES), and understanding factors affecting stability and reactivity of the interface regions including the role of defects and impurities. Results indicate that kinetic effects have an important influence on interface structure and composition, and they also show that defects in the oxide substrate induce new electronic states at the interface which play a major role in cation-anion bonding and interface interactions. The results establish a link between electronic and chemical bonding properties and the interface structure and morphology, which is required to successfully manipulate the interfacial properties of advanced ceramic materials.

Lad, R.J.

1992-11-01

181

? 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

2013-03-11

182

Equilibrium composition of metal and slag in reductive smelting of binary batch based on Chineisk and Korshunovo concentrates  

Microsoft Academic Search

content in vanadium hot metal is 0.05?0.12%, while the hot-metal temperature on leaving the blast furnace is around 1400 ° C. The limiting titanium-oxide content in the blast-furnace slag is maintained at 24?25%, while the quantity of titanium oxides in the batch reaches 180?200 kg TiO 2 per ton of hot metal [6]. To reduce the titanium-dioxide content in the

Yu. A. Deryabin

2007-01-01

183

Formation of metal oxides by cathodic arc deposition  

SciTech Connect

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

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

1995-03-01

184

Method for converting uranium oxides to uranium metal  

SciTech Connect

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal.

Duerksen, W.K.

1988-01-05

185

Method for converting uranium oxides to uranium metal  

SciTech Connect

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 mixtures is then cooled to a temperature less than -100/sup 0/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, W.K.

1987-01-01

186

Method for converting uranium oxides to uranium metal  

SciTech Connect

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

187

Switching-time analysis of binary-oxide memristors via a nonlinear model  

NASA Astrophysics Data System (ADS)

A simulation-based analysis is conducted of the ionic switching times for nanometer-scale binary-oxide ``memristor'' devices. This analysis is based upon a device model that incorporates nonlinear field-driven ionic transport within the bulk of the memristor. In contrast, prior models of charge transport in such devices have relied upon linear simplifications, or else they have included nonlinear effects only at the electrode interfaces. As shown here via simulation, the nonlinear model provides much closer quantitative agreement with experimentally observed device switching times. Also, this model predicts a distinct asymmetry between the ``set'' and ``reset'' switching behaviors of memristors that is not present in linear models. Thus, the model and the quantitative results derived using it suggest an experimental route by which the underlying device physics might be elucidated further.

Hashem, Nabeem; Das, Shamik

2012-06-01

188

Magnetism in Metal Oxides Under Pressure  

NASA Astrophysics Data System (ADS)

The nature of the magnetic collapse in transition metal oxides under pressure has been a source of recent theoretical interest with multiple explanations presented in the literature[1,2]. In order to better understand this phenomenon we present the results of two sets of calculations utilizing different electronic structure methods. We perform quantum Monte Carlo (QMC) calculations of FeO under pressure. As QMC uses no approximate functional and solves the many-body, correlated Schrödinger equation, these calculations are often much more accurate than standard Density Functional Theory (DFT) approaches. Therefore we use QMC to calculate total energies of FeO in both the high spin and low spin states. In addition we use DFT calculations to gain a qualitative understanding of the mechanism for the transition. As a post processing step to the DFT calculations, a tight binding Hamiltonian is constructed aiding in the physical interpretation. Results are presented for FeO, MnO and NiO in the B1 structure. As the pressure is increased, the bandwidth increases much faster than the crystal field splitting suggesting that it plays the dominant role in the magnetic collapse. 1 J. Kunes et al. Nature Materials. 7, 198 (2008) 2 R. E. Cohen et al. Science. 275, 654 (1997)

Shulenburger, L.; Esler, K.; Savrasov, S.; Kim, J.; Cohen, R. E.

2008-12-01

189

Dielectric response of sputtered transition metal oxides  

NASA Astrophysics Data System (ADS)

We have investigated the dielectric properties of thin layers of five oxides of transition metals (Ta2O5, HfO2, ZrO2, (ZrO2)0.91(Y2O3)0.09, and Sn0.2Zr0.2Ti0.6O2) sputtered from ceramic targets at different pressures. We find that layers deposited at low pressure behave as expected from literature, whereas layers deposited at high pressure all exhibit an anomalous dielectric response similar to that reported for the so-called ``colossal'' dielectric constant materials. The characterization of the thickness, frequency, and temperature dependence of the capacitance, as well as the comparison of film properties before and after annealing show that the anomalous dielectric response is due to quenched-in vacancies that act as dopants and cause the insulating layers to behave as semiconductors. An increase in quenched-in vacancies concentration with sputtering pressure results in a transition from normal to anomalous dielectric response and gradual increase in layer conductivity. In contrast, the refractive index does not depend on sputtering pressure. This observation indicates the possible application of these materials as transparent coatings with a tunable electrical conductivity.

Iosad, N. N.; Ruis, G. J.; Morks, E. V.; Morpurgo, A. F.; van der Pers, N. M.; Alkemade, P. F. A.; Sivel, V. G. M.

2004-06-01

190

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

191

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

SciTech Connect

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

Dhital, Saurav; Stassun, Keivan G.; Bastien, Fabienne A. [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN 37235 (United States); West, Andrew A.; Massey, Angela P. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Bochanski, John J., E-mail: saurav.dhital@vanderbilt.edu [Astronomy and Astrophysics Department, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2012-03-15

192

Refined Metallicity Indices for M Dwarfs Using the SLoWPoKES Catalog of Wide, Low-mass Binaries  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

193

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

194

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

196

Method of physical vapor deposition of metal oxides on semiconductors  

DOEpatents

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

Norton, David P. (Knoxville, TN)

2001-01-01

197

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

Microsoft Academic Search

Safe drinking water is paramount to human survival. Current treatments do not adequately remove all metals from solution, are expensive, and use many resources. Metal oxide nanoparticles are ideal sorbents for metals due to their smaller size and increased surface area in comparison to bulk media. With increasing demand for fresh drinking water and recent environmental catastrophes to show how

Karen Elizabeth Engates

2010-01-01

198

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

199

Characterization of High Temperature Electrically Conducting Oxides.  

National Technical Information Service (NTIS)

The goal of the investigation reported on herein was to study the interrelationships between electrical conductivity, oxidation-reduction kinetics, defect structure, and composition of n- and p-type binary and ternary transition metal oxides. The experime...

H. U. Anderson D. M. Sparlin

1984-01-01

200

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

201

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes.  

PubMed

Supercapacitors have attracted huge attention in recent years as they have the potential to satisfy the demand of both huge energy and power density in many advanced technologies. However, poor conductivity and cycling stability remains to be the major challenge for its widespread application. Various strategies have been developed for meeting the ever-increasing energy and power demands in supercapacitors. This Research News article aims to review recent progress in the development of mesoporous carbon incorporated metal oxide nanomaterials, especially metal oxide nanoparticles confined in ordered mesoporous carbon and 1D metal oxides coated with a layer of mesoporous carbon for high-performance supercapacitor applications. In addition, a recent trend in supercapacitor development - hierarchical porous graphitic carbons (HPGC) combining macroporous cores, mesoporous walls, and micropores as an excellent support for metal oxides - is also discussed. PMID:23030034

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-08-01

202

Catalytic Oxidation by Transition Metal Ions in Zeolites.  

National Technical Information Service (NTIS)

The regular cavities of zeolites form a unique environment for carrying out both stoichiometric and catalytic oxidation reactions. Transition metal ions such as molybdenum and cobalt may be introduced into the zeolite, and, as well, the acidity may be var...

J. H. Lunsford

1988-01-01

203

Direct Observation of Metal-Oxide Interactions in Nanoscale Systems  

Microsoft Academic Search

Although hetero-interfaces between metals and oxides are common in technology, a quantitative understanding of such interfaces remains a challenge. In this study, we investigate the atomic and electronic structure of metal-oxide interfaces by correlated Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope. In particular, we use these techniques to examine the structure-property relationships at

Robert F. Klie; Kai Sun; Nigel D. Browning; Mark M. Disko; J. Liu

2002-01-01

204

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

205

The trends of oxygen vacancy levels in metal oxides  

NASA Astrophysics Data System (ADS)

Most of the d or d^10 oxides such as ZnO, SnO2, In2O3, and TiO2 are wide-bandgap n-type semiconductors even though they are not intentionally doped. For quite a long time, it was commonly believed that oxygen vacancies (VO) in metal oxides are the electron donors because the formation energy of VO in metal oxides is low and the electrical conductivity of the n-type oxides is closely linked to the formation of VO However, recent theoretical and experimental studies have put this point of view in question especially with different calculation methods involved. We present a detailed analysis of the wavefunction characters of oxygen vacancy in conventional metal oxides and unveil the chemical trend of oxygen vacancy transition energy levels with respect to the conduction-band minimum (CBM). We show that in the type-s and type-p metal oxides, where the character of an oxygen vacancy level is similar to that of the CBM, the oxygen vacancy levels are generally deep and become deeper when the cation size decreases. In type-d metal oxides, the oxygen vacancy levels are generally shallow and can sometimes even be above the CBM. Our analysis is confirmed by the calculated trends of oxygen vacancy levels in representative metal oxides using hybrid density functional analysis. It also provides guidelines to search a metal oxide that has shallow VO donor levels, such as the one found in BiVO4

Yin, Wanjian; Wei, Suhuai; Al-Jassim, Mowafak; Yan, Yanfa

2012-02-01

206

The oxidation of carbon monoxide on platinum-supported binary oxide catalysts  

Microsoft Academic Search

The kinetics of the carbon monoxide oxidation on Pt-supported MeSb2O6 (Me=Ni, Co and Cu) have been investigated in a recycle reactor at 80°C. The catalysts contain 1% Pt (weight)-supported on NiSb2O6, CoSb2O6 and CuSb2O6. The reaction rates were measured at different carbon monoxide contents in air from 0 to 1% (vol.). The results were compared with that of Pt\\/SnO2\\/Al2O3 catalyst

Gülten Gürda?; Thomas Hahn

2000-01-01

207

Evaluation of the joint-action toxicity of binary mixtures of heavy metals against the mangrove periwinkle Tympanotonus fuscatus var radula (L.)  

Microsoft Academic Search

The joint-action toxicity of binary mixtures of heavy metal compounds prepared in predefined ratios of 4:1, 3:2, 1:1, 2:3, and 1:4 (wt\\/wt) of Zn:Cu, Zn:Cd, and Cd:Cu, respectively, and tested against the mangrove periwinkle Tympanotonus fuscatus were carried out in laboratory bioassays. The interactions between binary mixtures showed significant departures from the action of the individual constituent metals when acting

Adebayo Akeem Otitoloju

2002-01-01

208

Hysteresis in gadolinium oxide metal-oxide-semiconductor capacitors  

NASA Astrophysics Data System (ADS)

This investigation explores how oxidation affects the gadolinium oxide capacitor and the corresponding Gd2O3 hysteresis phenomenon. The current-voltage varied with Gd2O3 thickness and a charged capacitance voltage (C-V) curve with a left shift is also observed in experimental results. The breakdown voltages rise with increasing oxidation time, while the corresponding C-V hysteresis gaps decrease with increasing oxidation time.

Hsieh, Li-Zen; Ko, Hong-Hsi; Kuei, Ping-Yu; Chang, Liann-Be; Jeng, Ming-Jer

2005-10-01

209

Catalysis by low oxidation state transition metal (carbonyl) clusters  

Microsoft Academic Search

This review seeks to evaluate the role of low oxidation state transition metal clusters (metal carbonyl clusters) in catalysis. The review commences with a discussion of the cluster surface analogy and then proceeds to discuss whether catalysis takes place by intact molecular clusters or mononuclear fragments; both these topic have been fiercely contested in the literature. Next, the application of

Paul J. Dyson

2004-01-01

210

Aqueous synthesis of high surface area metal oxides  

Microsoft Academic Search

By applying high throughput synthesis and characterization technologies, we have been optimizing common dry or aqueous synthetic routes for the preparation of high surface area metals and oxides, such as precipitation and modified Pechini methods. For wet combustion synthesis, we have been screening a variety of organic acids as dispersants and developed proprietary recipes for individual metals. By resorting to

Christian Bluthardt; Carola Fink; Klemens Flick; Alfred Hagemeyer; Marco Schlichter; Anthony Volpe

2008-01-01

211

Anodic oxidation and self-polarization of zinc metal  

Microsoft Academic Search

X-ray diffraction techniques have been applied to study the structural changes and processes which take place when zinc metal is subjected to oxidation and self-polarization at the metal-electrolyte interface. The effect of electrolyte concentration and anodizing voltage on the structure and composition of the ZnO layer formed was investigated.

A. H. Abou El Ela; M. El Bahay; S. M. El-Raghy

1981-01-01

212

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

213

Catalytic Decomposition of Formic Acid on Metal Oxides  

Microsoft Academic Search

Studies on the decomposition of formic acid were initiated during the first decade of the present century by Mailhe and Sabatier [1], using metals and metal oxides. These authors were concerned primarily with the selectivity of their catalysts, i.e., their ability to favor one of the reactions possible for the decomposition of formic acid (Eq. 1).

J. M. Trillo; G. Munuera; J. M. Criado

1972-01-01

214

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

SciTech Connect

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

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

2012-12-01

215

Method and System for Focused Ion Beam Directed Self-Assembly of Metal Oxide Island Structures.  

National Technical Information Service (NTIS)

A process for guiding the growth of metal oxide islands of material which involves: presenting a metal oxide surface to a charged particle beam; impinging the metal oxide surface with ions from the charged particle beam; presenting said metal oxide surfac...

J. F. Groves R. Wortman Y. Du

2005-01-01

216

Photoluminescent graphene oxide microarray for multiplex heavy metal ion analysis.  

PubMed

An aptamer-linked graphene oxide (GO) microarray is synthesized for multiplex heavy metal ion detection. Fluorescent nanosized GO sheets are micropatterned, and specific aptamers targeting Ag(+) and Hg(2+) are immobilized on the GO array. Upon capture of the target heavy metal ions, electron transfer occurs between the GO (donors) and the heavy metal ions (acceptors), leading to fluorescence quenching of the GO. PMID:23606642

Liu, Fei; Ha, Hyun Dong; Han, Dong Ju; Seo, Tae Seok

2013-04-19

217

Graphene oxide for metal-insulator-semiconductor tunneling diodes  

Microsoft Academic Search

In this study, we have inserted the graphene oxide (GO) in the metal\\/insulator\\/semiconductor tunneling diodes. The graphene oxide devices reveal the better stability as compared with the control devices. At a small positive bias, different control devices have different magnitude of photocurrents, while photocurrents of GO devices have close magnitude. At 2 V, the photocurrent density of the GO device

Chu-Hsuan Lin; Wei-Ting Yeh; Chun-Hui Chan; Chun-Chieh Lin

2011-01-01

218

A semiconducting metal-oxide array for monitoring fish freshness  

Microsoft Academic Search

An array of semiconducting metal-oxide (SMO) chemiresistive sensors can quantitatively measure the freshness of Atlantic salmon (Salmo salar), haddock (Melanogrammus aeglefinus), and Atlantic cod (Gadus morhua). A variety of SMO films were tested, including films containing oxides of copper and tin, and commercially available tin-based SMO films. Analytical testing of the fish samples was performed in conjunction with SMO sensor

Jeremy Hammond; Brent Marquis; Ray Michaels; Brian Oickle; Bruce Segee; John Vetelino; Al Bushway; Mary Ellen Camire; Kathy Davis-Dentici

2002-01-01

219

Infrared emission spectroscopy studies of metal oxide catalysts  

SciTech Connect

The spectral changes of a series of metal oxides, resulting from their oxidation of toluene, were studied by infrared emission spectroscopy. Compartive investigations were carried out with a grating spectrophotometer and with an interferometric fourier transform spectrophotometer. The latter was found to be superior in the present kind of experiments.

Jonson, B.; Rebenstorf, B.; Larsson, R.; Primet, M.

1986-08-01

220

Field-induced resistive switching in metal-oxide interfaces  

Microsoft Academic Search

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

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

2004-01-01

221

Interactive effects of binary combinations of manganese with other heavy metals on metal uptake and antioxidative enzymes in Brassica juncea L. seedlings  

Microsoft Academic Search

The present study investigates the interactive mechanism involved during the uptake of heavy metals and stress tolerance in Brassica juncea L. seedlings under the influence of Mn(II) in binary combinations with Cr(VI), Ni(II), Co(II) and Cu(II) in terms of changes in antioxidative enzymes-superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). The order of

Rupinder Kaur; Renu Bhardwaj; Ashwani K. Thukral; Upma Narang

2011-01-01

222

Diffusion of metal in a confined nanospace of carbon nanotubes induced by air oxidation.  

PubMed

Air oxidation can result in the motion of metal confined in carbon nanotubes (CNTs). This can also be utilized to tailor various hybrid nanostructures. By controllable air-oxidation, as-prepared metal@CNT nanorods (a) can be converted first to core-shell-void nanorods (b), then to metal/metal oxide@CNT nanotubes (c), and finally to mesoporous metal oxide nanotubes (d). The metal/metal oxide@CNT nanotubes and mesoporous metal oxide nanotubes are expected to find many applications, such as in lithium ion batteries, catalysis, magnetic drug delivery, and gas sensing. PMID:20684548

Zhou, Jisheng; Song, Huaihe; Chen, Xiaohong; Huo, Junping

2010-08-25

223

(S)TEM analysis of functional transition metal oxides  

Microsoft Academic Search

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

Miaofang Chi

2008-01-01

224

A Survey of Proper-Motion Stars. XIV. Spectroscopic Binaries among Metal-poor Field Blue Stragglers  

NASA Astrophysics Data System (ADS)

We summarize the results from a program of monitoring the radial velocities of 10 metal-poor, high-velocity field stars whose colors are 0.01 to 0.13 mag bluer than main-sequence turnoffs of comparable-metallicity globular clusters. Two of the candidate halo blue stragglers (BD +72 94 and BD +40 1166) show no signs of velocity variability, one (HD 84937) shows only weak signs of variability, one (BD +25 1981) appears to be a very long-period binary, and six (BD -12 2669, HD 97916, HD 106516, BD +51 1817, G66-30, and G202-65) are single-lined spectroscopic binaries, with periods ranging from 167 to 844 days. Velocity coverage for the four candidates without orbital solutions ranges from 15.9 to 19.0 years. The orbital eccentricities are all low, e<0.30 and =0.11. Five of the six binary orbits have very low eccentricities, with =0.07. We have reanalyzed the velocity data from Preston & Sneden and have derived orbital solutions similar to theirs for 10 of the spectroscopic binaries among their ``blue metal-poor'' stars with [Fe/H]<=-0.6. We confirm their conclusion that the binary frequency is high; we find 47+/-10% if we include only the definite binaries with [Fe/H]<=-0.6. Our orbital solutions for the seven binaries with periods longer than 20 days all have low eccentricities, with e<=0.26 and =0.11. These orbital characteristics are very similar to the Ba II, CH, subgiant CH, and dwarf carbon stars, suggesting that mass transfer has been involved in their formation. Of the five binary stars in our program with published abundances of lithium, all have been found to be deficient (and one in beryllium as well). In contrast, two of the three apparently single stars have published lithium abundances and show no deficiency. The mass functions for the six binaries in our program and seven similar systems studied by Preston & Sneden are consistent with their unseen companions all being white dwarfs with M~0.55 Msolar and random orbital inclinations. Taking all of our observations and those of others together, we argue that the results are consistent with all field blue stragglers being binary systems with long periods and low eccentricities, the primary stars being deficient in lithium and the secondary stars being normal-mass white dwarfs. All these properties are suggestive of a blue-straggler formation model that involves mass transfer. For six of the 13 stars in the two programs for which s-process elemental abundances are available, no signs of enhancement are discernible, suggesting that the donor star was a first-ascent red giant. For the star with the longest orbital period (1307 days), CS 22956-028, s-process abundance enhancements have been reported. This star may be a precursor to the subgiant CH class, as suggested by Luck & Bond. Some of the results presented here used observations made with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona.

Carney, Bruce W.; Latham, David W.; Laird, John B.; Grant, Catherine E.; Morse, Jon A.

2001-12-01

225

Zirconia-metal (Al, Y, Ti) oxide nanolaminate films  

Microsoft Academic Search

Our work on ZrO2 when this oxide is combined with other metal oxides in multilayer nanolaminate films is reviewed in this invited paper. ZrO2–Al2O3, ZrO2–Y2O3, and ZrO2–TiO2 nanolaminates were studied. The films were grown by sequential sputter deposition of individual oxide layers from metal targets using radio-frequency-excited, O2-bearing discharges. As the thickness of individual layers decreases, interfaces play an increasingly

C. R. Aita

2004-01-01

226

Infrared Photodissociation Spectroscopy of Metal Oxide Carbonyl Cations.  

NASA Astrophysics Data System (ADS)

Mass selected metal oxide-carbonyl cations of the form MO_{m}(CO)_{n}^{+} are studied via infrared laser photodissociation spectroscopy, in the 600-2300cm^{1} region. Insight into the structure and bonding of these complexes is obtained from the number of infrared active bands, their relative intensities and their frequency positions. Density functional theory calculations are carried out in support of the experimental data. Insight into the bonding of CO ligands to metal oxides is obtained and the effect of oxidation on the carbonyl stretching frequency is revealed.

Brathwaite, Antonio D.; Duncan, Michael A.

2013-06-01

227

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

228

Internal zone growth method for producing metal oxide metal eutectic composites  

DOEpatents

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

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

1980-01-01

229

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, and as having a crystalline orientation defined as predominantly C-axis oriented by x-ray diffraction is disclosed.

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

1990-04-16

230

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

231

Role of Oxidative Stress in Transformation Induced by Metal Mixture  

PubMed Central

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

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

2011-01-01

232

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

NASA Astrophysics Data System (ADS)

A critical review is presented of all studies on homogeneous nucleation kinetics in crystalline binary metallic alloys located in the literature. Emphasis was first placed upon examining the data on the number of precipitates per unit volume of matrix phase, N v , recorded as a function of isothermal reaction or aging time. With the exception of the results of a few studies on Cu-rich Cu-Co alloys, all of these data were extensively “contaminated” by significant overlapping of the diffusion fields of adjacent precipitates and especially by concurrent coarsening. The use of the “nucleation window” concept was advocated as a means of finding a range of alloy compositions and reaction temperatures in a particular alloy system within which sufficient data on N v vs time can be collected to evaluate the steady-state nucleation rate, J s * without significant intervention by either disturbing effect. Transmission electron microscopy (TEM) was identified as a particularly valuable experimental tool for measuring N v . However, smallangle neutron scattering (SANS) is also proving useful for this purpose, and the combination of SANS with FIM-AP (field ion microscope-atom probe) has uncovered information of crucial importance to understanding the transformation sequence in Cu-Co alloys. Wagner and co-workers[52,62,63,64-78-79] have demonstrated the presence of precursor Co segregations large in extent but small in amplitude, of which the most successful lead to the formation of identifiable precipitates (within which segregation is very much larger in amplitude but considerably smaller in extent). The Wagner et al. work suggests that the supersaturations at which they formed were insufficient to permit the fluctuations which did not eventually fulfill exactly the specifications for critical nuclei to evolve into precipitates. While classical, the Cahn-Hilliard continuum nonclassical [su2] and Cook-deFontaine discrete lattice point nonclassical nucleation theories[25,26,27] yield nearly identical results in the temperature-Co concentration range experimentally studied, the J* s values thus calculated are a few orders of magnitude smaller than the experimentally measured rates when the concentration of vacancies present at the reaction temperature is (reasonably) assumed operative. On the basis of theoretical and computer simulation studies by Binder et al. [84,87,89,90] and Klein et al.,[91 94] the observed precursor concentration fluctuations are indicative of relatively long-range interactions among adjacent atoms in Cu-Co alloys, whereas the solution thermodynamics so far applied to this system is based upon the use of short interaction distances. This is suggested to be the principal source of the discrepancy between measured and calculated nucleation kinetics in Cu-Co alloys. Suggestions are offered for future research intended to clarify some of the complexities which have recently become apparent in studies of homogeneous nucleation kinetics in binary metallic alloys.

Aaronson, H. I.; Legoues, F. K.

1992-07-01

233

Thermodynamics of toxic gas molecules on metal oxide nano powders  

NASA Astrophysics Data System (ADS)

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 using a computer controlled gas adsorption isotherm apparatus, which has good temperature stability within 0.01K in a wide rage and good pressure accuracy with a resolution better than 10-5 torr in 100 torr. A set of isotherms below the triple points of the nitrous gas was measured. A specific surface area of particles was also obtained from calculations of a molecular area of adsorbate gas on the surface of the adsorbents. The thermodynamic results including compressibility and isosteric heat of adsorption of nitrous gases on various metal oxide surfaces will be presented.

Kim, Jae-Yong; Kim, Chae-Ok

2005-03-01

234

Packaging of plutonium metal and oxide in the ARIES project  

SciTech Connect

The objective of the Advanced Recovery and Integrated Extraction System (ARIES) Project is to demonstrate technology to dismantle plutonium pits from excess nuclear weapons, convert the plutonium to a metal ingot or an oxide powder, package the metal or oxide, and verify the contents of the package by nondestructive assay. The packaged weapons plutonium will be converted to mixed oxide reactor fuel or immobilized in ceramic forms suitable for geologic storage. The packaging of the material must therefore be suitable for storage until the material is further processed. A set of containers for plutonium metal and oxide has been developed to meet the needs of the ARIES process and the Department of Energy requirements for long-term storage. The package has been developed and qualified with the participation of private companies.

Rofer, C.K.; Martinez, D.A.; Trujillo, V.L.

1998-12-01

235

Packaging of Plutonium Metal and Oxide in the ARIES Project  

SciTech Connect

The objective of the Advanced Recovery and Integrated Extraction System (ARIES) Project is to demonstrate technology to dismantle plutonium pits from excess nuclear weapons, convert the plutonium to a metal ingot or an oxide powder, package the metal or oxide, and verify the contents of the package by nondestructive assay. The packaged weapons plutonium will be converted to mixed-oxide reactor fuel or immobilized in ceramic forms suitable for geologic storage. The packaging of the material must therefore be suitable for storage until the material is further processes. A set of containers for plutonium metal and oxide has been developed to meet the needs of the ARIES process and the Department of Energy requirements for long-term storage. The package has been developed and qualified with the participation of private companies.

Rofer, C.K.; Martinez, D.A.; Trujillo, V.L.

1998-11-09

236

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

SciTech Connect

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 V{sub 2}O{sub 5} 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 different from the decomposition of dyes involved in previous research. This may account for the high efficiency of the GAC catalytic oxidation method in color and chemical oxygen demand (COD) reductions of dye wastewater. An adsorption/oxidation hypothesis was proposed to account for the catalytic oxidation. Test runs were performed to determine the optimal operating conditions and amounts of metal oxide catalyst, GAC, and H{sub 2}O{sub 2}.

Li, S.H.; Lai, C.L. [Yuan Ze Univ., Taoyuan (Taiwan, Province of China). Dept. of Chemical Engineering

1999-05-01

237

Metal Oxide Growth and Characterization on CVD Graphene  

NASA Astrophysics Data System (ADS)

Thin metal oxide layers deposited on graphene can be utilized as dielectric barriers between metals and graphene to help isolate a metal contact from the graphene channel. This is important for graphene based spintronic devices as dielectric layers between the ferromagnetic electrode and graphene have been shown to increase the spin relaxation time measured utilizing non-local detection and spin precession measurements. However, simply depositing metal oxide layers such as aluminum oxide on graphene results in non-uniform film lowering the quality of the interface barrier. We will present a systematic study of aluminum oxide layers grown on CVD (chemical vapor deposition) graphene under ultra-high vacuum conditions with and without titanium seed layers. The aluminum oxide layers with the titanium seed layers showed reduced surface roughness. The chemical and structural composition determined by XPS (X-ray photoelectron spectroscopy) will be also presented that shows full oxidation of the aluminum and partial oxidation of the titanium. Our previous work which demonstrated that introducing HfO2 barrier layer in the epitaxial graphene devices on SiC wafer improves the measured lifetime and spin injection efficiency will be briefly presented as well.

Matsubayashi, Akitomo; Abel, Joseph; Prasad Sinha, Dhiraj; Lee, Ji Ung; Labella, Vincent

2013-03-01

238

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

SciTech Connect

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

Wong, Stanislaus S; Hongjun, Zhou

2012-11-27

239

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

240

Oxidative desulfurization of benzene fraction on transition metal oxides  

NASA Astrophysics Data System (ADS)

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

241

Arsenic desorption from ferric and manganese binary oxide by competitive anions: significance of pH.  

PubMed

Ferric and manganese binary oxide (FMBO) has been used to remediate an arsenic (As)-polluted river in China, but insufficient data was available to (1) evaluate its effects on the environment and (2) propose a feasible strategy of addressing the arsenic-bearing FMBO. The desorption behavior of arsenic in the presence of four competitive anions (i.e., phosphate, silicate, sulfate, and bicarbonate) at different concentrations was investigated with pH ranging from 3 to 11. The presence of these anions promoted the desorption of arsenic from arsenic-bearing FMBO and followed the sequence of phosphate > silicate > sulfate approximately equal to bicarbonate across a wide pH range. Desorption of arsenate (As[V]) was more significant than that of arsenite (As[III]). Sequence dissolution of arsenic-bearing FMBO particles by NH4-oxalate/oxalic acid and hydrochloric acid were performed. The laboratory results indicated that As(III) was primarily occluded in the crystalline parts of the FMBO. The desorption behavior of arsenic could be described by kinetic models using the Elovich and power function equations under different pH conditions and was related to the adsorption of phosphate and silicate. pH played an important role in the desorption of arsenic, because of its effects on the species distribution of anions, surface charge of the arsenic-bearing FMBO, and subsequent electrostatic forces between anions and FMBO. PMID:22866393

Xu, Wei; Wang, Hongjie; Wu, Kun; Liu, Ruiping; Gong, Wenxin; Qu, Jiuhui

2012-06-01

242

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

243

Catalytic oxidations using transition-metal carbonyls  

Microsoft Academic Search

During the past year we have been working primarily on four separate projects, all of which are related to our goal of discovering new science which will allow development of new homogeneous catalysts for selective oxidations of hydrocarbons. These four projects are: the Reâ(CO)ââ photocatalyzed decomposition of hydrogen peroxide, the oxidative decarbonylation of an iridium carbonyl complex having a phosphine

Roundhill

1981-01-01

244

Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate with methanol over binary zinc-yttrium oxides  

Microsoft Academic Search

The binary zinc–yttrium oxides were prepared by co-precipitation method, characterized and tested in the synthesis of DMC via transesterification of ethylene carbonate with methanol. The catalytic results showed that the catalyst with Zn\\/Y molar ratio of 3 and calcined at 400°C exhibited superior catalytic activity, corresponding to TOF of 236mmol\\/gcath. Appropriate content of yttrium in the catalyst enhanced the catalytic

Liguo Wang; Ying Wang; Shimin Liu; Liujin Lu; Xiangyuan Ma; Youquan Deng

2011-01-01

245

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

246

Metal-decorated graphene oxide for ammonia adsorption  

NASA Astrophysics Data System (ADS)

Based on the first-principles density functional theory, we have studied the stability, electronic structure and ammonia storage capacity of metal-decorated graphene oxide (GO). Metal atoms (Mg and Li) are bonded strongly to the epoxy oxygen atoms on the surface of the GO sheet, which can act as high-surface-area adsorbent for the ammonia uptake and release. Each metal atom can bind several ammonia molecules around itself with a reasonable binding energy. We find metal-decorated GO can store up to tens of moles of ammonia per kilogram, which is far better than the recently reported excellent ammonia adsorption by GO.

Li, Yunguo; Pathak, Biswarup; Nisar, Jawad; Qian, Zhao; Ahuja, Rajeev

2013-07-01

247

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

248

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

249

Structural characterization and photocatalytic activity of hollow binary ZrO2/TiO2 oxide fibers  

NASA Astrophysics Data System (ADS)

The formation of hollow binary ZrO2/TiO2 oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO2 and tetragonal phase of ZrO2, and the introduction of ZrO2 notably inhibits the growth of TiO2 nanocrystallites. Although calcined at 575 °C, all hollow ZrO2/TiO2 fibers exhibit higher surface areas (>113 m2/g) than pure TiO2 hollow fibers. The Pyridine adsorption on ZrO2/TiO2 sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO2. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms.

Wu, Baochao; Yuan, Rusheng; Fu, Xianzhi

2009-03-01

250

Metal Oxide Thin Films Deposited from Metal Organic Precursors in Supercritical CO 2 Solutions  

Microsoft Academic Search

This work demonstrates a novel method for deposition of metal oxide thin films, including Al2O3, ZrO2, MnOx, and RuOx where the metal-organic precursors and oxidizing agents are delivered in liquid and supercritical CO2. A cyclic deposition process is presented where reactants are introduced sequentially to control surface adsorption and byproduct removal steps. Reactions are studied in a hot wall reactor

Theodosia Gougousi; Dipak Barua; Erin D. Young; Gregory N. Parsons

2005-01-01

251

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

2012-09-08

252

Nanoporous metal oxides with tunable and nanocrystalline frameworks via conversion of metal-organic frameworks.  

PubMed

Nanoporous metal oxide materials are ubiquitous in the material sciences because of their numerous potential applications in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics, and drug delivery. While synthetic strategies for the preparation of siliceous nanoporous materials are well-established, nonsiliceous metal oxide-based nanoporous materials still present challenges. Herein, we report a novel synthetic strategy that exploits a metal-organic framework (MOF)-driven, self-templated route toward nanoporous metal oxides via thermolysis under inert atmosphere. In this approach, an aliphatic ligand-based MOF is thermally converted to nanoporous metal oxides with highly nanocrystalline frameworks, in which aliphatic ligands act as the self-templates that are afterward evaporated to generate nanopores. We demonstrate this concept with hierarchically nanoporous magnesia (MgO) and ceria (CeO2), which have potential applicability for adsorption, catalysis, and energy storage. The pore size of these nanoporous metal oxides can be readily tuned by simple control of experimental parameters. Significantly, nanoporous MgO exhibits exceptional CO2 adsorption capacity (9.2 wt %) under conditions mimicking flue gas. This MOF-driven strategy can be expanded to other nanoporous monometallic and multimetallic oxides with a multitude of potential applications. PMID:23651169

Kim, Tae Kyung; Lee, Kyung Joo; Cheon, Jae Yeong; Lee, Jae Hwa; Joo, Sang Hoon; Moon, Hoi Ri

2013-06-04

253

A comparison in activity between transition-metal oxides and transition metals  

NASA Astrophysics Data System (ADS)

Transition-metal oxides are widely used materials in catalysis as substrates and promoters, but also as the active catalyst materials themselves. We compare the reactivity of transition-metal oxides with the one of transition metals. The comparison is exemplified for the ammonia synthesis reaction. First we show that there exist characteristic Brønsted-Evans Polanyi (BEP) relations (linear relations between transition state and dissociation energies) for dissociation of molecules on transition-metal oxides in the rutile and perovskite structure. It is well-known that the (211) metal surface is several orders of magnitude more reactive than the (111) metal surface due to the lower BEP line for the 211 facet. We find that both rutiles and perovskites follow BEP relations that are lower than the one of the 211 facet. Second we utilize the established BEP relations together with calculated adsorption energetics in a micro-kinetic model to obtain a volcano plot for the catalytic activity. We find that oxides have a higher turn over frequency as compared with metals. Hence, oxides intrinsically have a great advantage in terms of catalytic activity which opens up for catalyst design.

Vojvodic, Aleksandra; Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas; Nørskov, Jens

2012-02-01

254

Stability of supported metal and supported metal oxide combustion catalysts  

Microsoft Academic Search

Catalysts used for high-temperature combustion of light hydrocarbons must maintain high activity over long time intervals by avoiding excessive sintering and deactivation in the hot and corrosive combustion environment. The sintering resistance and chemical stability of catalytically active phases is a key technical problem that must be solved for the development of commercially viable combustion catalysts. All noble metals and

Jon G. McCarty; M. Gusman; D. M. Lowe; D. L. Hildenbrand; K. N. Lau

1999-01-01

255

Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals  

Microsoft Academic Search

The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or

John Abrahamson

2002-01-01

256

Metal-oxide-metal wide-band infrared detectors with a long service life  

Microsoft Academic Search

A report is given of some characteristics of two types of long-service-life metal-oxide-metal (MOM) diodes suitable for conversion of microwave and infrared radiation to the visible range. It is suggested that it should be possible to mass-manufacture such MOM detectors

S. A. Zhgun; V. A. Zarshchikov; G. D. Lobov; V. S. Solovev; A. A. Rivlin; V. V. Shtykov

1976-01-01

257

BRIEF COMMUNICATIONS: Metal-oxide-metal wide-band infrared detectors with a long service life  

Microsoft Academic Search

A report is given of some characteristics of two types of long-service-life metal-oxide-metal (MOM) diodes suitable for conversion of microwave and infrared radiation to the visible range. It is suggested that it should be possible to mass-manufacture such MOM detectors

S. A. Zhgun; V. A. Zarshchikov; G. D. Lobov; V. S. Solov'ev; A. A. Rivlin; V. V. Shtykov

1976-01-01

258

Sulfur polymer cement encapsulation of RCRA toxic metals and metal oxides.  

National Technical Information Service (NTIS)

A study was conducted to determine the suitability of Sulfur Polymer Cement (SPC) encapsulation technology for the stabilization of RCRA toxic metal and metal oxide wastes. In a series of bench-scale experiments, the effects of sodium sulfide additions to...

C. L. Calhoun L. E. Nulf A. H. Gorin

1995-01-01

259

Metal oxide nanoparticles for advanced energy applications  

Microsoft Academic Search

Hot-wire chemical vapor deposition (HWCVD) has been employed as an economically scalable method for the deposition of crystalline molybdenum oxide nanoparticles at high density. Under optimal synthesis conditions, only crystalline nanostructures with a smallest dimension of ~3–50 nm are observed with extensive transmission electron microscopy analyses. The incorporation of crystalline molybdenum oxide nanoparticles into battery electrodes has led to profound advancements

Se-Hee Lee; Rohit. Deshpande; Daniel Benhammou; Phil A. Parilla; A. Harv Mahan; Anne C. Dillon

2009-01-01

260

Geochemical effects on metals following permanganate oxidation of DNAPLs.  

PubMed

The application of in situ chemical oxidation for dense, nonaqueous phase liquid (DNAPL) remediation requires delivery of substantial levels of oxidant chemicals into the subsurface to degrade target DNAPLs and to satisfy natural oxidant demand. This practice can raise questions regarding changes in subsurface conditions, yet information regarding potential effects, especially at the field scale, has been lacking. This paper describes an evaluation of the effects on metals associated with in situ chemical oxidation using potassium permanganate at Launch Complex 34 (LC34), Cape Canaveral Air Station, Florida. At LC34, high concentrations of permanganate (1 to 2 wt%) were injected into the subsurface as part of a demonstration of DNAPL remediation technologies. In a companion experimental effort at the Colorado School of Mines, field samples were characterized and laboratory batch and mini-column studies were completed to assess effects of permanganate oxidation on metals in the subsurface one year after completion of the field demonstration. Results indicated there was potential for long-term immobilization of a portion of introduced manganese and no treatment-induced loss in subsurface permeability due to deposition of manganese oxides particles, which are a product of the oxidation reactions. Permanganate treatment did cause elevated manganese, chromium, and nickel concentrations in site ground water within the treated region. Some of these metals effects can be attenuated during downgradient flow through uncontaminated and untreated aquifer sediments. PMID:12873009

Crimi, Michelle L; Siegrist, Robert L

261

Molten Salt Oxidation of Ion-exchange Resins Doped with Toxic Metals and Radioactive Metal Surrogates  

Microsoft Academic Search

Ion-exchange resins doped with toxic metals and radioactive metal surrogates were test-burned in a bench-scale molten salt oxidation (MSO) reactor system. The purposes of this study are to confirm the destruction performance of the two-stage MSO reactor system for the organic ion-exchange resin and to obtain an understanding of the behavior of the fixed toxic metals and the sulfur in

Hee-Chul YANG; Yong-Jun CHO; Hee-Chul EUN; Jae-Hyung YOO; Joon-Hyung KIM

2005-01-01

262

Secondary organic aerosol coating of synthetic metal-oxide nanoparticles.  

PubMed

Secondary organic aerosol (SOA) from the ?-pinene + ozone reaction readily coats TiO(2) and CeO(2) metal-oxide nanoparticles in smog-chamber experiments under atmospherically relevant conditions. Otherwise identical experiments compared bare nanoparticles and nanoparticles coated with poly(acrylic acid) (PAA). The PAA-coated particles result in significantly higher new-particle formation rates, suggesting that the SOA vapors coat bare metal oxide more readily than the PAA. After particles begin to grow via SOA coating, however, all particles, independent of size or the presence of a metal-oxide core, grow with a rate proportional to their surface area, modified to account for gas-phase diffusion in the transition regime between the kinetic and bulk-flow regimes. This suggests that SOA condensational growth may be modeled based on the size distribution of the condensational sink in the atmosphere. PMID:21534558

Lee, Joohyung; Donahue, Neil M

2011-05-02

263

Quantitative Determination of the Catalytic Activity of Bulk Metal Oxides for Formic Acid Oxidation  

Microsoft Academic Search

The dissociative chemisorption of formic acid, HCOOH, to surface formate species, HCOO-M, on metal oxide catalysts was examined. The chemisorption studies reveal an average of ?5–6 ?mol\\/m2 of active surface sites for many of the metal oxide catalysts. From TPD experiments, the decomposition temperatures of the surface formate (Tp) were found to vary from 88 to 313°C. The turnover frequency

David E. Fein; Israel E. Wachs

2002-01-01

264

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

265

High-performance organic thin-film transistors with metal oxide/metal bilayer electrode  

NASA Astrophysics Data System (ADS)

We demonstrate bilayer source-drain (S-D) electrodes for organic thin film transistors (OTFT). The bilayer consists of a transition metal oxide (MoO3,WO3, or V2O5) layer and a metal layer. The metal oxide layer, directly contacting the organic semiconducting layer, serves as the charge-injection layer. The overcoated metal layer is responsible for the conduction of charge carriers. We found that the metal oxide layer coupled between pentacene and metal layers played an important role in improving the field-effect transistor characteristics of OTFTs. Devices with the bilayer S-D electrodes showed enhanced hole-injection compared to those with only metal electrode. High field-effect mobility of 0.4 cm2/V s and on/off current ratios of 104 were obtained in the pentacene based TFTs using the bilayer S-D electrodes at a gate bias of -40 V. The improvement is attributed to the reduction in the contact barrier and the prevention of metal diffusion into the organic layer and/or unfavorable chemical reaction between the organic layer and the metal electrode.

Chu, Chih-Wei; Li, Sheng-Han; Chen, Chieh-Wei; Shrotriya, Vishal; Yang, Yang

2005-11-01

266

New technology of metal oxide thin film preparation for chemical sensor application  

Microsoft Academic Search

The reduction of grain size in metal oxide films is one of the key factors to enhance the gas sensing properties of semiconductor layers. The basic idea introduced here is to create thin metal oxide films with small grain size by using a special regime of rf sputtering from either metallic or metal oxide targets. The regime includes the deposition

Viacheslav Khatko; Josep Calderer; Eduard Llobet; Xavier Correig

2005-01-01

267

Universal Medium-Range Order of Amorphous Metal Oxides  

NASA Astrophysics Data System (ADS)

We propose that the structure of amorphous metal oxides can be regarded as a dual-dense-random-packing structure, which is a superposition of the dense random packing of metal atoms and that of oxygen atoms. Our ab initio molecular dynamics simulations show that the medium-range order of amorphous HfO2, ZrO2, TiO2, In2O3, Ga2O3, Al2O3,, and Cu2O is characterized by the pentagonal-bipyramid arrangement of metal atoms and that of oxygen atoms, and prove the validity of our dual-random-sphere-packing model. In other words, we find that the pentagonal medium-range order is universal independent of type of metal oxide.

Nishio, Kengo; Miyazaki, Takehide; Nakamura, Hisao

2013-10-01

268

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

EPA Science Inventory

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

269

Anaerobic Nitrate-Dependent Metal Bio-Oxidation  

NASA Astrophysics Data System (ADS)

Direct biological oxidation of reduced metals (Fe(II) and U(IV)) coupled to nitrate reduction at circumneutral pH under anaerobic conditions has been recognized in several environments as well as pure culture. Several phylogentically diverse mesophilic bacteria have been described as capable of anaerobic, nitrate-dependent Fe(II) oxidation (NFOx). Our recent identification of a freshwater mesophilic, lithoautotroph, Ferrutens nitratireducens strain 2002, capable of growth through NFOx presents an opportunity to further study metal bio- oxidation. Continuing physiological studies revealed that in addition to Fe(II) oxidation, strain 2002 is capable of oxidizing U(IV) (4 ?M) in washed cell suspensions with nitrate serving as the electron acceptor. Pasteurized cultures exhibited abiotic oxidation of 2 ?M U(IV). Under growth conditions, strain 2002 catalyzed the oxidation of 12 ?M U(IV) within a two week period. Cultures amended with sodium azide, an electron transport inhibitor, demonstrated limited oxidation (7 ?M) similar to pasteurized cultures, supporting the direct role of electron transport in U(IV) bio-oxidation. The oxidation of U(IV) coupled denitrification at circumneutral pH would yield enough energy to support anaerobic microbial growth (?G°'= -460.36 kJ/mole). It is currently unknown whether or not strain 2002 can couple this metabolism to growth. The growth of F. nitratireducens strain 2002 utilizing Fe(II) as the sole electron donor was previously demonstrated. The amount of U(IV) (~12 ?M) that strain 2002 oxidized under similar autotrophic growth conditions yields 0.0019 kJ, enough energy for the generation of ATP (5.3 x 10-20 kJ ATP-1), but not enough energy for cell replication as calculated for nitrate-dependent Fe(II) oxidizing conditions (0.096 kJ) assuming a similar metabolism. In addition to F. nitratireducens strain 2002, a nitrate-dependent Fe(II) oxidizing bacterium isolated from U contaminated groundwater, Diaphorobacter sp. strain TPSY, was also capable of nitrate- dependent U(IV) oxidation (8 ?M over 24 hours, pseudo first order rate constant of 0.12 ± 0.02 hr-1) in washed cell suspensions. Further biochemical investigation of nitrate-dependent U(IV) oxidation in strain TPSY revealed the expression of several putative high molecular weight proteins specific to this metabolism. Together with the previously described metabolic ability of Geobacter metallireducens (Finneran et al. 2002) and Thiobacillus denitrificans (Beller 2005), these data indicate that anaerobic, metal oxidation may be a ubiquitous microbial metabolism.

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

2007-12-01

270

Characterization of the Redox Behavior and Stability of Conducting Oxides.  

National Technical Information Service (NTIS)

Goal was to study the relation between electrical conductivity, oxidation-reduction kinetics, defect structure, and composition of n- and p-type binary and ternary transition metal oxides. The experimental part included, thermogravimetry, x-ray diffractio...

H. U. Anderson S. A. Howard D. M. Sparlin

1986-01-01

271

The mechanism of electroforming of metal oxide memristive switches.  

PubMed

Metal and semiconductor oxides are ubiquitous electronic materials. Normally insulating, oxides can change behavior under high electric fields--through 'electroforming' or 'breakdown'--critically affecting CMOS (complementary metal-oxide-semiconductor) logic, DRAM (dynamic random access memory) and flash memory, and tunnel barrier oxides. An initial irreversible electroforming process has been invariably required for obtaining metal oxide resistance switches, which may open urgently needed new avenues for advanced computer memory and logic circuits including ultra-dense non-volatile random access memory (NVRAM) and adaptive neuromorphic logic circuits. This electrical switching arises from the coupled motion of electrons and ions within the oxide material, as one of the first recognized examples of a memristor (memory-resistor) device, the fourth fundamental passive circuit element originally predicted in 1971 by Chua. A lack of device repeatability has limited technological implementation of oxide switches, however. Here we explain the nature of the oxide electroforming as an electro-reduction and vacancy creation process caused by high electric fields and enhanced by electrical Joule heating with direct experimental evidence. Oxygen vacancies are created and drift towards the cathode, forming localized conducting channels in the oxide. Simultaneously, O(2-) ions drift towards the anode where they evolve O(2) gas, causing physical deformation of the junction. The problematic gas eruption and physical deformation are mitigated by shrinking to the nanoscale and controlling the electroforming voltage polarity. Better yet, electroforming problems can be largely eliminated by engineering the device structure to remove 'bulk' oxide effects in favor of interface-controlled electronic switching. PMID:19423925

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

2009-05-05

272

Anodic oxidation and self-polarization of zinc metal  

Microsoft Academic Search

X-ray diffraction techniques have been applied to study the structural changes and processes which take place when zinc metal\\u000a is subjected to oxidation and self-polarization at the metal-electrolyte interface. The effect of electrolyte concentration\\u000a and anodizing voltage on the structure and composition of the ZnO layer formed was investigated.

A. H. Abou El Ela; M. El Bahay; S. M. El-Raghy

1981-01-01

273

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

274

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

275

Criteria for safe storage of plutonium metals and oxides  

SciTech Connect

This standard establishes safety criteria for safe storage of plutonium metals and plutonium oxides at DOE facilities; materials packaged to meet these criteria should not need subsequent repackaging to ensure safe storage for at least 50 years or until final disposition. The standard applied to Pu metals, selected alloys (eg., Ga and Al alloys), and stabilized oxides containing at least 50 wt % Pu; it does not apply to Pu-bearing liquids, process residues, waste, sealed weapon components, or material containing more than 3 wt % {sup 238}Pu. Requirements for a Pu storage facility and safeguards and security considerations are not stressed as they are addressed in detail by other DOE orders.

Not Available

1994-12-01

276

Contact processes at the molten metal-oxide interface  

SciTech Connect

Using the condition of open systems, conditions are examined for the formation of an electrical charge at a molten metal-oxide interface. It is shown that the value of the charge depends upon the difference between the chemical potentials of oxygen and the difference in the degree of ionicity of the Me-O bond between the contacting phases. As an example of applications of the rules found, conditions are examined for increasing the completeness of purification of the metal from dispersed oxide inclusions.

Markhasev, B.I.

1988-05-01

277

Direct thermal decomposition of metal nitrates in octadecylamine to metal oxide nanocrystals.  

PubMed

We have developed a method for the synthesis of metal oxide nanocrystals with controllable shape and size, which is based on the direct thermal decomposition of metal nitrates in octadecylamine. Mn3O4 nanoparticles and nanorods with different lengths were synthesized by using manganese nitrate as the decomposition material. Other metal oxide nanocrystals such as NiO, ZnO, CeO2, CoO, and Co3O4 were also prepared by this method. These nanocrystals were then assembled into 3D colloidal spheres by a surfactant-assisted self-assembly process. Subsequently, calcination was carried out to remove the surfactants to obtain mesoporous metal oxides, which show large pores, good crystallization, thermally stable pore mesostructures, and potential applications in various fields, especially in catalysis and lithium-ion batteries. PMID:18189257

Wang, Ding-Sheng; Xie, Ting; Peng, Qing; Zhang, Shao-Yan; Chen, Jun; Li, Ya-Dong

2008-01-01

278

Structure and Metal Overlayer Growth on Oxide Surfaces  

Microsoft Academic Search

This thesis discusses experimental structural studies of oxide surfaces and metal\\/oxide systems. We discuss the surface and interface properties of these materials by examining several simple model systems, and try to understand these systems using some general rules. The main experimental technique is medium-energy ion-scattering, a quantitative in-situ probe of surfaces and interfaces. Chapter 1 discusses some fundamental issues in

Jin Bao Zhou

1993-01-01

279

High-temperature and electrochemical oxidation of transition metal silicides  

Microsoft Academic Search

High-temperature and electrochemical oxidation of transition metal silicides, which are widely used in microelectronics as\\u000a ohmic contacts and protective coatings for high-temperature alloys, are discussed in this review. The process of oxide film\\u000a formation during annealing or anodizing is extremely important for both applications of silicides. It is discussed for three\\u000a disilicides: MoSi2, WSi2, and TiSi2. It has been shown

A. D. Chirkin; V. O. Lavrenko; V. M. Talash

2009-01-01

280

Containerless solidification of undercooled oxide and metallic eutectic melts  

Microsoft Academic Search

A high-speed video was employed to monitor the in situ recalescence of undercooled oxide Al2O3–36.8at.% ZrO2 and metallic Ni–18.7at.% Sn eutectics that were processed on an aero-acoustic levitator and an electromagnetic levitator, respectively. For the oxide eutectic, the entire sample becomes brighter and brighter without any clear recalescence front during spontaneous crystallization. When the sample was seeded at desired undercoolings,

Mingjun Li; Kosuke Nagashio; Kazuhiko Kuribayashi

2004-01-01

281

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

282

Mixed metal oxide films as pH sensing materials  

Microsoft Academic Search

Due to the demand for accurate, reliable and highly sensitive pH sensors, research is being pursued to find novel materials\\u000a to achieve this goal. Semiconducting metal oxides, such as TiO, SnO and SnO2 and insulating oxides such as Nb2O5 and Bi2O3, and their mixtures in different proportions are being investigated for this purpose. The films of these materials mixtures\\u000a are

Edric Gill; Khalil Arshak; Arousian Arshak; Olga Korostynska

2008-01-01

283

Colloidal metal in aluminum-oxide  

Microsoft Academic Search

The nature of the origin of the color in anodized aluminum colored by ac electrolysis in electrolytes containing nickel, copper, silver, gold, and molybdenum salts is investigated. The measured specular reflectance spectra in the region 350-750 nm can be adequately explained by assuming that small metallic particles are incorporated in the anodic film as a colloid. By calculating the optical

David G. W. Goad; M. Moskovits

1978-01-01

284

Preparation of Thorium Metal from the Oxide.  

National Technical Information Service (NTIS)

Thorium dioxide is reduced to thorium metal by dispersing it in a molten flux of magnesium chloride and magnesium fluoride in an inert atmosphere at between 825 and 875 degrees C. An excess of a magnesium-zinc alloy is then added to the solution formed wh...

J. Knighton A. V. Hariharan R. K. Steunenberg W. H. Hauschildt

1965-01-01

285

Kinetics of Metal Atom Oxidation Reactions.  

National Technical Information Service (NTIS)

The tubular fast-flow reactor, previously used for reaction kinetic measurements at temperatures up to only 1000K, has been adapted to reach temperatures up to 2000K and has been applied to studies of gas phase reactions of metal atoms with O2. The most e...

A. Fontijn S. C. Kurzius J. J. Houghton

1972-01-01

286

Electrochemical oxidation of phenol in a parallel plate reactor using ruthenium mixed metal oxide electrode  

Microsoft Academic Search

In this study, electrochemical oxidation of phenol was carried out in a parallel plate reactor using ruthenium mixed metal oxide electrode. The effects of initial pH, temperature, supporting electrolyte concentration, current density, flow rate and initial phenol concentration on the removal efficiency were investigated. Model wastewater prepared with distilled water and phenol, was recirculated to the electrochemical reactor by a

Yusuf Yavuz; A. Sava? Koparal

2006-01-01

287

Sol-flame synthesis: a general strategy to decorate nanowires with metal oxide/noble metal nanoparticles.  

PubMed

The hybrid structure of nanoparticle-decorated nanowires (NP@NW) combines the merits of large specific surface areas for NPs and anisotropic properties for NWs and is a desirable structure for applications including batteries, dye-sensitized solar cells, photoelectrochemical water splitting, and catalysis. Here, we report a novel sol-flame method to synthesize the NP@NW hybrid structure with two unique characteristics: (1) large loading of NPs per NW with the morphology of NP chains fanning radially from the NW core and (2) intimate contact between NPs and NWs. Both features are advantageous for the above applications that involve both surface reactions and charge transport processes. Moreover, the sol-flame method is simple and general, with which we have successfully decorated various NWs with binary/ternary metal oxide and even noble metal NPs. The unique aspects of the sol-flame method arise from the ultrafast heating rate and the high temperature of flame, which enables rapid solvent evaporation and combustion, and the combustion gaseous products blow out NPs as they nucleate, forming the NP chains around NWs. PMID:22494023

Feng, Yunzhe; Cho, In Sun; Rao, Pratap M; Cai, Lili; Zheng, Xiaolin

2012-04-17

288

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

289

Catalytic Oxidations Using Transition-Metal Carbonyls.  

National Technical Information Service (NTIS)

During the past year we have been working primarily on four separate projects, all of which are related to our goal of discovering new science which will allow development of new homogeneous catalysts for selective oxidations of hydrocarbons. These four p...

D. M. Roundhill

1981-01-01

290

Single-crystalline mesoporous CaO supported Cr–V binary oxides: Highly active catalysts for the oxidative dehydrogenation of isobutane  

Microsoft Academic Search

The three-dimensional mesoporous calcium oxide (meso-CaO) supported chromium–vanadium binary oxide catalysts yCrOx\\/10wt.% VOx\\/meso-CaO (i.e., yCr\\/10V\\/meso-CaO, y=0–4wt.%; the VOx and CrOx weight percentages referred to the mass contents of V2O5 and Cr2O3 in the catalysts, respectively) were prepared via an incipient wetness impregnation route and characterized by means of XRD, BET, SEM, TEM\\/SAED (selected-area electron diffraction), Raman, and H2-TPR (temperature-programmed reduction)

Jiguang Deng; Lei Zhang; Caixin Liu; Yunsheng Xia; Hongxing Dai

2011-01-01

291

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

292

Preparation of zinc oxide\\/metal oxide multilayered thin films for low-voltage varistors  

Microsoft Academic Search

Zinc oxide\\/metal oxide multilayered composite thin film varistors have been fabricated by the radio-frequency (RF, 13.56MHz) sputtering method and the electrical properties of the films were investigated. After the Au electrode was formed on a quartz substrate by vacuum evaporation, zinc oxide (ZnO) layer was deposited by the RF sputtering with ZnO target at room temperature, Ar partial pressure of

N Horio; M Hiramatsu; M Nawata; K Imaeda; T Torii

1998-01-01

293

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

294

Homogeneous water oxidation catalysts containing a single metal site.  

PubMed

The recent recognition that a single metal site is capable of mediating the multiple electron and proton transfer events associated with water oxidation represents a pivotal discovery for the field. This finding has led to a remarkable expansion of known synthetic water oxidation catalysts, and has provided the means to gain unprecedented insight into the reaction steps involved with O-O bond formation. This perspective reflects on the key studies that have advanced our understanding of water oxidation catalysis while summarizing molecular features that are integral to negotiating this complicated reaction pathway with the goal of helping identify new frontiers of discovery for the field. PMID:23133828

Wasylenko, Derek J; Palmer, Ryan D; Berlinguette, Curtis P

2012-11-07

295

Electrocatalytic oxidation of thiosulfate by metal hexacyanoferrate film modified electrodes  

Microsoft Academic Search

The electrocatalytic oxidation of S2O32? by metal (iron(II), indium(III), nickel(II), and Cobalt(II)) hexacyanoferrate film from consecutive cyclic voltammetry was investigated. The ferric hexacyanoferrate film catalyzed the rapid oxidation of thiosulfate after oxidizing the film [Fe(II)-CN-Fe(II)] to [Fe(III)-CN-Fe(III)]. The indium(III) hexacyanoferrate film has a similar catalytic mechanism. While nickel(II) hexacyanoferrate and cobalt(II) hexacyanoferrate films exhibit a different reaction mechanism, at the

Shen-Ming Chen

1996-01-01

296

The electrochemical deoxidation of metal oxides by calcium using a solid oxide membrane  

NASA Astrophysics Data System (ADS)

The reduction of a metal oxide by calcium in a CaCl2 melt produces metal and calcium oxide (CaO) dissolved in the molten chloride. To minimize waste salts, the reacted salts have to be regenerated. This can be done either by converting CaO to CaCl2 by chlorination with Cl2 and adding calcium metal or by electrochemical deoxidation of CaO. In the first method, the addition of calcium metal increases the amount of reacted salts, and consequently the waste salts, while in the second method the quantity of reacted salts remains constant. The electrochemical deoxidation of CaO occurs in one step and the produced oxygen is evacuated. This article describes a study of the electrochemical deoxidation of CaO using a solid oxide membrane.

Martin, A.; Lambertin, D.; Poignet, J.-C.; Allibert, M.; Bourges, G.; Pescayre, L.; Fouletier, J.

2003-10-01

297

TiO 2-photocatalyzed oxidative degradation of binary mixtures of vaporized organic compounds  

Microsoft Academic Search

Rates of photocatalytic removal of the components for 14 binary mixtures of vaporized organic components over Degussa P-25 TiO2 at 360 nm in the presence of air were measured. In some cases, intermediate products were identified and their rates of removal measured. Seven binary mixtures were reacted in a static reactor: CH3OH strongly inhibited removal of CH2Cl2 while CH2Cl2 somewhat

N. N. Lichtin; M. Avudaithai; E. Berman; A. Grayfer

1996-01-01

298

Detached double-lined eclipsing binaries as critical tests of stellar evolution. Age and metallicity determinations from the HR diagram  

NASA Astrophysics Data System (ADS)

Detached, double-lined spectroscopic binaries that are also eclipsing provide the most accurate determinations of stellar mass, radius, temperature and distance-independent luminosity for each of their individual components, and hence constitute a stringent test of single-star stellar evolution theory. We compile a large sample of 60 non-interacting, well-detached systems mostly with typical errors smaller than 2% for mass and radius and smaller than 5% for effective temperature, and compare them with the properties predicted by stellar evolutionary tracks from a minimization method. To assess the systematic errors introduced by a given set of tracks, we compare the results obtained using three widely-used independent sets of tracks, computed with different physical ingredients (the Geneva, Padova and Granada models). We also test the hypothesis that the components of these systems are coeval and have the same metallicity, and compare the derived ages and metallicities with the ones obtained by fitting a single isochrone to the system. Overall, there is a good agreement among the different determinations, and we provide a comprehensive discussion on the sub-sample of systems which either present problems or have estimated metallicities. Although within the errors the published tracks can fit most of the systems, a large degeneracy between age and metallicity remains. The power of the test is thus limited because the metallicities of most of the systems are unknown. The full version of Table 6 is only available in the electronic form at http://www.edpsciences.org

Lastennet, E.; Valls-Gabaud, D.

2002-12-01

299

Spin transport in metal-oxide switching devices  

NASA Astrophysics Data System (ADS)

Metal-oxide-based devices in which resistive switching occurs, often referred to as memristors or resistive-RAM (random oxide memory), show promise for use in technologically exciting applications such as high-density non-volatile memories, electronically reconfigurable logic, and neural networks. We report on electron spin transport through electrochemically precipitated copper filaments formed in TaOx memristive devices consisting of Co(60 nm)/TaOx (16nm)/Cu(5 nm)/Py(60 nm) with crossbar-type electrode geometry. These metal-oxide switching devices with ferromagnetic electrodes show memristive behavior having a typical OFF/ON resistance ratio of 10^5. Magnetoresistance measurements performed by sweeping an external magnetic field display evidence of spin transport in the low-resistance ON-state at 77 K. Spin transport vanishes in the OFF-state. These data are strong evidence that the fundamental switching mechanism in these metal-oxide devices is the creation of Cu filaments in the ON-state that completely span the 16 nm thick TaOx and form a continuous metallic conduction path. In addition to helping elucidate the conduction pathway in these intriguing structures, our findings can advance electronics combining spintronic and electronic functions.

Richter, Curt A.; Jang, H.-Jae; Kirillov, Oleg; Jurchescu, Oana

2012-02-01

300

Extrusion of metal oxide superconducting wire, tube or ribbon.  

National Technical Information Service (NTIS)

A process and apparatus for extruding a superconducting metal oxide composition YBa(sub 2)Cu(sub 3)O(sub 7-x) provides a wire (tube or ribbon) having a cohesive mass and a degree of flexibility together with enhanced electrical properties. Wire diameters ...

J. T. Dusek

1990-01-01

301

Biodiesel by catalytic reactive distillation powered by metal oxides  

Microsoft Academic Search

The properties and use of biodiesel as a renewable fuel as well as the problems associated with its current production processes are outlined. A novel sustainable esterification process based on catalytic reactive distillation is proposed. The pros and cons of manufacturing biodiesel via fatty acid esterification using metal oxide solid acid catalysts are investigated. Finding catalysts that are active, selective,

Anton A. Kiss; Alexandre C. Dimian; Gadi Rothenberg

2008-01-01

302

Angle resolved autoionization spectra of adsorbates on metal oxide surfaces  

Microsoft Academic Search

The autoionization of excited core hole states of simple adsorbates has attracted considerable attention. It provides information on the local electronic density of the valence levels. However, mainly simple adsorbates on different metal surfaces have been investigated. Here it was of considerable interest to study autoionization on oxide surfaces because effects due to the substrate are expected to be different

J. Klinkmann; D. Cappus; H.-J. Freund

1995-01-01

303

Thiosulfate oxidation: Catalysis of synthetic sphalerite doped with transition metals  

Microsoft Academic Search

The rate of thiosulfate oxidation to tetrathionate by dissolved molecular oxygen was measured in aqueous suspensions of synthetic sphalerites doped with first row transition metals (Mn, Fe, Co, Ni, Cu). Pure sphalerite and Mn-doped sphalerite show no catalytic activity for this reaction. Catalytic activity increases from Fe to Ni, which has maximum activity, with a slight decrease moving to Cu.

Yong Xu; Martin A. A. Schoonen; Daniel R. Strongin

1996-01-01

304

Functional nanomaterials based on metal oxides with hierarchical structure  

NASA Astrophysics Data System (ADS)

The depending on evolution morphology of hierarchical porous nanostructured films based on metal oxide systems was investigated using atomic force microscopy. Gas sensitive properties of these structures were investigated. It was found that the characteristics of the degree of maturation of sols are gas-sensitive parameter to create functional porous layers.

Abrashova, E. V.; Gracheva, I. E.; Moshnikov, V. A.

2013-08-01

305

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

306

The Electronic Structure of Nonpolar Surfaces in Insulating Metal Oxides  

NASA Astrophysics Data System (ADS)

Understanding the electronic and geometric structures of metal oxide surfaces has a key interest in many technological areas. A randomly chosen crystal surface has a high probability of being polar, unstable and containing in-gap states due to surface dangling bonds. As a result, the surface should be stabilized by passivation or reconstruction. However, do the nonpolar surfaces of ionic crystals of insulating metal oxides need the passivation or reconstruction similar to covalent crystals? We address this question by analyzing the nonpolar surfaces and their electronic structure for the common crystal structures of metal oxides. The study using periodic DFT calculations is performed for following representatives: Cu2O, ZnO, Al2O3, TiO2, V2O5, WO3, CaTiO3, Mg2SiO4. It has been shown that the nonpolar surface can be constructed out of dipole-free, charge-neutral and stoichiometric unit cells for each crystal. We demonstrate that all constructed and relaxed nonpolar surfaces of the metal oxides show a clear band gap. It should be emphasized that the constructed surfaces are neither reconstructed nor passivated. Additionally, we show a correlation between the electronic structure of the relaxed surfaces and Ewald energies calculated for the surface ions.

Zherebetskyy, Danylo; Wang, Lin-Wang

2013-03-01

307

Positron studies of metal-oxide-semiconductor structures  

SciTech Connect

Positron annihilation spectroscopy provides a new probe to study the properties of interface traps in metal-oxide semiconductors (MOS). Using positrons, we have examined the behavior of the interface traps as a function of gate bias. We propose a simple model to explain the positron annihilation spectra from the interface region of a MOS capacitor.

Au, H.L.; Asoka-Kumar, P.; Nielsen, B.; Lynn, K.G. (Brookhaven National Laboratory, Upton, New York 11973 (United States))

1993-03-15

308

The Color of Mars: Oxidation of Exogenic Metallic Iron  

Microsoft Academic Search

The origin of the maghemite inferred to be present in the martian soil by the Pathfinder and Viking magnetic properties experiments remains uncertain. Recent experimental results show that metallic iron can be oxidized into maghemite and hematite under conditions similar to the current martian environment. These data suggest that non-aqueous weathering of meteoritic iron could be the source of the

A. S. Yen; B. C. Murray

1998-01-01

309

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

310

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

311

Hybrid materials based on metal oxides and poly(organophosphazenes)  

Microsoft Academic Search

In this paper the sol-gel preparation of hybrid materials made of metal oxide and polytorganophosphazenel components is described. The main problem focused on during this research was to avoid phase separation in order to get homogeneous materials. This problem was pursued looking at the formation of genuine chemical bonds between the exploited polyphosphazenes and the inorganic composite networks. Investigations on

Massimo Guglielmi; Giovanna Brusatin; Giacomo Facchin; Mario Gleria; Roger De Jaeger; Marco Musiani

1996-01-01

312

The formation of the magnetic moments in disordered binary alloys of metal-metalloid type  

Microsoft Academic Search

The s-d model of disordered binary alloy with the Hubbard electron interaction is considered in the paper. The dependence of the local magnetic moment on the number of nonmagnetic atoms in the nearest neighborhood is received as a result of the solution of the self-consistent equation for the local magnetic moment. It is shown that the model proposed describes qualitatively

A. K. Arzhnikov; L. V. Dobysheva

1992-01-01

313

Interface plasmonic properties of silver coated by ultrathin metal oxides  

NASA Astrophysics Data System (ADS)

Many fields of high technology take advantage of conductor-dielectric interface properties. Deeper knowledge of physical processes that determine the optical response of the structures containing metal-dielectric interfaces is important for improving the performance of thin film devices containing such materials. Here we present a study on optical properties of several ultrathin metal oxides deposited over thin silver layers. Some widely used materials (Al2O3, SiO2, Y2O3, HfO2) were selected for deposition by r.f. sputtering, and the created metal-dielectric structures with two of them, alumina and silica, were investigated in this work using attenuated total reflectance (ATR) technique and by variable-angle spectroscopic ellipsometry (VASE). VASE was performed with a help of a commercial ellipsometer at various incident angles and in a wide spectral range. A home-made sample holder manufactured for WVASE ellipsometer and operational in Otto configuration has been implemented for angle-resolved and spectral ATR measurements. Simultaneous analysis of data obtained by these two independent techniques allows elaboration of a representative model for plasmonic-related phenomena at metal-dielectric interface. The optical constants of the interface layers formed between metal and ultrathin oxide layers are investigated. A series of oxides chosen for this study allows a comparative analysis aimed for selection of the most appropriate materials for different applications.

Sytchkova, A.; Zola, D.; Grilli, M. L.; Piegari, A.; Fang, M.; He, H.; Shao, J.

2011-09-01

314

Energetics of lithium transition metal oxides applied as cathode materials in lithium ion batteries  

NASA Astrophysics Data System (ADS)

In this work, high temperature oxide melt solution calorimetry was employed to investigate the thermodynamic properties of several representative lithium transition metal oxide systems applied as cathode materials in lithium ion batteries: layered alpha-NaFeO2 structure LiNi1-x COxO2 solid solution, Li1+xMn 2-xO4 spinel, LiMO2 (M = Mn, Fe and Co), and chemically delithiated LixCoO2. The enthalpies of formation and enthalpies of mixing for LiNi1-x COxO2 solid solution series (0 ? x ? 1) were determined using high temperature oxide melt solution calorimetry. The enthalpies of formation at 298 K from binary oxides (Li2O, NiO and CoO) and O2, and the lattice parameters decrease approximately linearly with the Co content x in LiNi1-xCOxO 2. The solid solution deviates slightly positively from ideality. Lithium substituted spinel Li1+xMn2-xO 4 (0 ? x ? 1/3) samples synthesized are stoichiometric at x < 0.25, and oxygen deficient at x ? 0.25. The enthalpy of formation from binary oxides (Li2O, Mn2O3 and MnO2 ) becomes more exothermic with x in Li1+xMn2-x O4 for stoichiometric compounds, and deviates endothermically from this trend for oxygen deficient compounds. This energetic trend is related to two competing substitution mechanisms of lithium for manganese (oxidation of Mn3+ to Mn4+ versus formation of oxygen vacancies). LiMO2 samples (M = Mn, Fe, and Co) with different structures were synthesized and their enthalpies of formation from oxides (Li2O and M2O3) or oxides (Li2O and MO) plus oxygen at 298 K were determined. The relative stability of the polymorphs of LiMO 2 was established based on their enthalpies of formation. Phase transformations in LiFeO2 were investigated by differential scanning calorimetry and high temperature oxide melt solution calorimetry. The gamma phase is the stable form of LiFeO2 at room temperature and the a phase is stable at high temperature. Energetics of chemically delithiated LixCoO2 samples (0.5 ? x ? 1.0) with the alpha-NaFeO2 structure (O 3 type) was studied. The enthalpies of formation from binary oxides (Li2O and CoO) and oxygen vary linearly with x and LixCoO 2 becomes less stable with decreasing x. The enthalpies of formation from oxides and oxygen for monoclinic Li0.5CoO2 and O3-CoO2 were estimated by extrapolation from the linear trend.

Wang, Miaojun

315

Metal oxides immobilized fabrics by radiation induced graft polymerization  

NASA Astrophysics Data System (ADS)

Radiation induced graft polymerization is effective for adding a new functionality to various forms of existing polymers. Ion-exchange nonwoven fabrics by gamma radiation induced graft polymerization have been used as filters in air and liquid. However, these materials have no capability for removing non-ionic species, such as volatile organic compound and ozone. Manganese oxides immobilized fabrics were developed for removing ozone. In addition, these materials were capable of removing formaldehyde and arsenic. Fine particles of manganese oxides were observed on the fibers. New materials produced by radiation induced graft polymerization and metal immobilization were applicable for purification of contaminants in environment. Manufacturing process is applicable for immobilization of the other metal oxides.

Fujiwara, K.; Masubuchi, T.; Miyata, K.; Shiozawa, M.; Takato, T.; Harakawa, H.

2010-03-01

316

Biocidal properties of metal oxide nanoparticles and their halogen adducts  

NASA Astrophysics Data System (ADS)

Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (? Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores. The procedure consists of a membrane method. Transmission electron micrographs are used to compare nanoparticle-treated and untreated cells and spores. It is proposed that the abrasive character of the particles, the oxidative power of the halogens/interhalogens, and the electrostatic attraction between the metal oxides and the biological material are responsible for high biocidal activities. While some activity was demonstrated, bacterial endospores were more resistant to nanoparticle treatment than the vegetative bacteria.

Haggstrom, Johanna A.; Klabunde, Kenneth J.; Marchin, George L.

2010-03-01

317

Reactions of Hf +, Ta +, and W + with O 2 and CO: Metal carbide and metal oxide cation bond energies  

Microsoft Academic Search

The reactions of Hf+, Ta+, and W+ with O2 and CO are studied as a function of translational energy in a guided ion beam tandem mass spectrometer. All three reactions with O2 form diatomic metal oxide cations in exothermic reactions that occur at the collision rate. In the CO systems, formation of both diatomic metal oxide and metal carbide cations

Christopher S. Hinton; Fengxia Li; P. B. Armentrout

2009-01-01

318

Gold supported on metal oxides for carbon monoxide oxidation  

Microsoft Academic Search

Au has been loaded (1% wt.) on different commercial oxide supports (CuO, La2O3, Y2O3, NiO) by three different methods: double impregnation (DIM), liquid-phase reductive deposition (LPRD), and ultrasonication\\u000a (US). Samples were characterised by N2 adsorption at ?196 °C, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive\\u000a X-ray spectrometry, high-angle annular dark-field imaging (Z-contrast), X-ray diffraction, and temperature programmed

Sonia A. C. Carabineiro; Nina Bogdanchikova; Miguel Avalos-Borja; Alexey Pestryakov; Pedro B. Tavares; Jose L. Figueiredo

2011-01-01

319

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

320

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

SciTech Connect

The formation of hollow binary ZrO{sub 2}/TiO{sub 2} oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N{sub 2} adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO{sub 2} and tetragonal phase of ZrO{sub 2}, and the introduction of ZrO{sub 2} notably inhibits the growth of TiO{sub 2} nanocrystallites. Although calcined at 575 deg. C, all hollow ZrO{sub 2}/TiO{sub 2} fibers exhibit higher surface areas (>113 m{sup 2}/g) than pure TiO{sub 2} hollow fibers. The Pyridine adsorption on ZrO{sub 2}/TiO{sub 2} sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO{sub 2}. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms. - Graphical abstract: The final ZrO{sub 2}/TiO{sub 2} products composed of hollow fibers are in the form of felt on the centimeter scale and possess certain strength and flexibleness. Moreover, they exhibit excellent efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane, reaching about 136% and 387% of the P25 activity after 10 h, respectively.

Wu Baochao [Research Institute of Photocatalysis, Chemistry and Chemical Engineering College, Fuzhou University, Fuzhou 350002 (China); Yuan Rusheng [Research Institute of Photocatalysis, Chemistry and Chemical Engineering College, Fuzhou University, Fuzhou 350002 (China)], E-mail: yuanrs2002@yahoo.com.cn; Fu Xianzhi [Research Institute of Photocatalysis, Chemistry and Chemical Engineering College, Fuzhou University, Fuzhou 350002 (China)

2009-03-15

321

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

SciTech Connect

The solubility behavior of transition metal oxides in high temperature water is interpreted by recognizing three types of chemical reaction equilibria: metal oxide hydration/dehydration, metal oxide dissolution and metal ion hydroxocomplex formation. The equilibria are quantified using thermodynamic concepts and the thermochemical properties of the metal oxides/ions representative of the most common constituents of construction metal alloys, i.e., element shaving atomic numbers between Z = 22 (Ti) and Z = 30 (Zn), are summarized on the basis of metal oxide solubility studies conducted in the laboratory. Particular attention is devoted to the uncharged metal ion hydrocomplex, M{sup Z}(OH){sub Z}(aq), since its thermochemical properties define minimum solubilities of the metal oxide at a given temperature. Experimentally-extracted values of standard partial molal entropy (S{sup 0}) for the transition metal ion neutral hydroxocomplex are shown to be influenced by ligand field stabilization energies and complex symmetry.

S.E. Ziemniak

2000-05-18

322

Formation of porous metal oxides in the anodization process.  

PubMed

A theory of the formation of nanoscale porous structures in oxides of metals grown by anodization is developed. It is shown that a growing oxide layer can become unstable which yields the formation of a spatially irregular array of pores. The instability is shown to result from a nonlinear dependence of electrochemical kinetics at the metal-oxide and oxide-electrolyte interfaces on the overpotential which is governed by the Butler-Volmer relation. The conditions for the instability of the oxide layer are found. The dependence of the oxide conductivity on the electric field is taken into account and is shown to have a destabilizing effect. A weakly nonlinear analysis is performed and it shows that the system evolution near the instability threshold is described by the Kuramoto-Sivashinsky equation. Farther from threshold, in the long-wave approximation, a system of strongly nonlinear equations is derived and solved numerically; this system describes the formation of deep irregular pores. In a particular case, a self-similar solution describing the propagation of a pore with a paraboloidal shape is found. PMID:17155069

Sample, C; Golovin, A A

2006-10-26

323

Formation of porous metal oxides in the anodization process  

NASA Astrophysics Data System (ADS)

A theory of the formation of nanoscale porous structures in oxides of metals grown by anodization is developed. It is shown that a growing oxide layer can become unstable which yields the formation of a spatially irregular array of pores. The instability is shown to result from a nonlinear dependence of electrochemical kinetics at the metal-oxide and oxide-electrolyte interfaces on the overpotential which is governed by the Butler-Volmer relation. The conditions for the instability of the oxide layer are found. The dependence of the oxide conductivity on the electric field is taken into account and is shown to have a destabilizing effect. A weakly nonlinear analysis is performed and it shows that the system evolution near the instability threshold is described by the Kuramoto-Sivashinsky equation. Farther from threshold, in the long-wave approximation, a system of strongly nonlinear equations is derived and solved numerically; this system describes the formation of deep irregular pores. In a particular case, a self-similar solution describing the propagation of a pore with a paraboloidal shape is found.

Sample, C.; Golovin, A. A.

2006-10-01

324

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

325

Oxidation kinetics of Ni metallic films: Formation of NiO-based resistive switching structures  

Microsoft Academic Search

Resistive switching controlled by external voltage has been reported in many Metal\\/Resistive oxide\\/Metal (MRM) structures in which the resistive oxide was simple transition metal oxide thin films such as NiO or TiO2 deposited by reactive sputtering. In this paper, we have explored the possibility to form NiO-based MRM structures from the partial oxidation of a blanket Ni metallic film using

L. Courtade; Ch. Turquat; Ch. Muller; J. G. Lisoni; L. Goux; D. J. Wouters; D. Goguenheim; P. Roussel; L. Ortega

2008-01-01

326

Two-Dimensional Polaronic Behavior in the Binary Oxides m-HfO2 and m-ZrO2  

SciTech Connect

We demonstrate that the three-dimensional (3D) binary monoclinic oxides HfO2 and ZrO2 exhibit quasi-2D polaron localization and conductivity, which results from a small difference in the coordination of two oxygen sublattices in these materials. The transition between a 2D large polaron into a zerodimensional small polaron state requires overcoming a small energetic barrier. These results demonstrate how a small asymmetry in the lattice structure can determine the qualitative character of polaron localization and significantly broaden the realm of quasi-2D polaron systems.

Mckenna, Keith P.; Wolf, Matthew J.; Shluger, Alexander L.; Lany, Stephan; Zunger, Alex

2012-03-14

327

Two-Dimensional Polaronic Behavior in the Binary Oxides m-HfO2 and m-ZrO2  

SciTech Connect

We demonstrate that the three-dimensional (3D) binary monoclinic oxides HfO{sub 2} and ZrO{sub 2} exhibit quasi-2D polaron localization and conductivity, which results from a small difference in the coordination of two oxygen sublattices in these materials. The transition between a 2D large polaron into a zero-dimensional small polaron state requires overcoming a small energetic barrier. These results demonstrate how a small asymmetry in the lattice structure can determine the qualitative character of polaron localization and significantly broaden the realm of quasi-2D polaron systems.

McKenna, K. P.; Wolf, M. J.; Shluger, A. L.; Lany, S.; Zunger, A.

2012-03-16

328

Three-dimensional Metal Nano Pattern Transfer on PET using Metal Oxide Layer  

NASA Astrophysics Data System (ADS)

There is a strong need for a fine three-dimensional metal patterning technique for fabricating next-generation devices such as patterned media and plasmon photonic and nano-scale electrodes. In addition, flexible and transparent electronic devices on plastic substrates are desired for wearable devices and flexible thin-film displays. Therefore, a technique for patterning metals onto plastic substrates is required. Nanotransfer printing (nTP) has received much attention recently because of its high throughput and high resolution compared to inkjet printing. However, it is difficult to create sub-100 nm metal patterns using nTP because the PDMS stamp is deformed by transfer pressure. Therefore, we have developed a technique for transferring three-dimensional metal patterns onto a polyethylene terephthalate (PET) substrate by nanoimprint lithography using a metal oxide release layer. The three-dimensional nanoimprint mold was fabricated by control of acceleration voltage electron beam lithography (CAV-EBL) with spin-on-glass (SOG). As a result, three-dimensional metal nano patterns were obtained using a metal oxide release layer. Moreover, the metal moth-eye structure, which has a very high aspect ratio, was transferred onto a PET substrate by applying our process to the moth-eye structure on glassy carbon.

Unno, Noriyuki; Taniguchi, Jun

329

Solvated Electrons on Metal Oxide Surfaces  

SciTech Connect

An electron added to a solvent polarizes its surrounding medium to minimize the free energy. Such an electron with its polarization cloud, which we refer to as the solvated electron, is one of the most fundamental chemical reagents of significant experimental and theoretical interest. The structure and dynamics of solvated electrons in protic solvents have been explored ever since the discovery of intense blue coloration in solutions of alkali metals in ammonia.1-3 Because solvated electrons are the most fundamental chemical reagents as well as carriers of negative charge, substantial experimental and theoretical efforts have focused on elucidating their equilibrium structure and solvation dynamics in a variety of neat liquids.4,5 One of the most important but least explored environments for solvated electrons, namely, the two-dimensional liquid/solid and liquid/vacuum interfaces, is the subject of this review.

Zhao, Jin; Li, Bin; Onda, Ken; Feng, Min; Petek, Hrvoje

2006-09-13

330

Synthesis and characterization of reduced transition metal oxides and nanophase metals with hydrazine in aqueous solution  

Microsoft Academic Search

Reduction of the first row (3d) transition metal complexes in aqueous solution using hydrazine as the reducing agent has been investigated systematically. Nanoscale reduced metal oxides such as VO2(B), Cr2O3 were obtained through hydrazine reduction followed by proper thermal treatments. Nanocrystalline ?-Mn2O3 was synthesized directly through aqueous phase reduction at room temperature. Nanoclusters of cobalt, copper and the one-dimensional single

Zhou Gui; Rong Fan; Weiqin Mo; Xianhui Chen; Ling Yang; Yuan Hu

2003-01-01

331

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

332

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

333

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

334

Oxygen partial pressure: a key to alloying and discovery in metal oxide--metal eutectic systems  

Microsoft Academic Search

Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Poâ sensitive as are melt stoichiometry, solid phase compositions, and vapor losses due to oxidation-volatilization. Simple criteria are postulated which can aid the experimentalist in selecting the proper

J. D. Holder; G. W. Clark; B. F. Oliver

1978-01-01

335

Epitaxial Growth of Metal and Superconductor Oxide Films  

SciTech Connect

In this presentation we will discuss the epitaxial growth of metal and superconductor oxide layers on bi-axial textured substrates. It is well established now that to obtain superior critical current densities for YBCO superconductors we need biaxially textured crystalline substrates. One way to accomplish biaxial texturing in a superconducting material is to grow epitaxial YBCO onto biaxial textured substrates. Superconducting oxide layers cannot be deposited directly on textured metal substrates for example Ni and Ni-W, and Cu since superconductors interact adversely with the substrate in a manner that degrades the superconductor material, especially during the high temperatures at which the superconductor materials are deposited or processed. It is also desirable to have a textured Ni layer on paramagnetic Ni-W substrate since Ni-W is more oxidative in nature. To overcome these adverse interactions, a buffer layer of material is often deposited between the substrate and the superconducting material to form a chemical barrier between the metal substrate and the superconductor. At present we are developing biaxial textured seed metal buffer layer materials inexpensively by electrodeposition method. We successfully electroplated biaxially textured Au on Ni, Ni-W and Cu and also Ni on Ni-W and Cu. In this meeting we will discuss the epitaxial growth of electrodeposited Ni and Au and also the superconducting YBCO material prepared epitaxially by PLD method.

Bhattacharya, Raghu [National Renewable Energy Laboratory (NREL); Spagnol, Priscila [National Renewable Energy Laboratory (NREL); Christen, David K [ORNL; Lee, Dominic F [ORNL

2005-01-01

336

Preparation and evaluation of novel hydrous metal oxide (HMO)-supported noble metal catalysts  

SciTech Connect

Hydrous Metal Oxides (HMOs) are chemically synthesized materials that, because of their high cation exchange capacity, possess a unique ability to allow the preparation of highly dispersed supported-metal catalyst precursors with high metal loadings. This study evaluates high weight loading Rh/HMO catalysts with a wide range of HMO support compositions, including hydrous titanium oxide (HTO), silica-doped hydrous titanium oxide (HTO:Si), hydrous zirconium oxide (HZO), and silica-doped hydrous zirconium oxide (HZO:Si), against conventional oxide-supported Rh catalysts with similar weight loadings and support chemistries. Catalyst activity measurements for a structure-sensitive model reaction (n-butane hydrogenolysis) as a function of catalyst activation conditions show superior activity and stability for the ZrO{sub 2}, HZO, and HZO:Si supports, although all of the Rh/HMO catalysts have high ethane selectivity indicative of high Rh dispersion. For the TiO{sub 2}-, HTO-, and HTO:Si supported Rh catalysts, a significant loss of both catalyst activity and Rh dispersion is observed at more aggressive activation conditions, consistent with TiO{sub x} migration associated with SMSI phenomena. Of all the Rh/HMO catalysts, the Rh/HZO:Si catalysts appear to offer the best tradeoff in terms of high Rh dispersion, high activity, and high selectivity.

Gardner, T.J.; McLaughlin, L.I.; Evans, L.R. [Sandia National Labs., Albuquerque, NM (United States). Catalysis and Chemical Technologies Dept.; Datye, A.K. [Univ. of New Mexico, Albuquerque, NM (United States)

1998-04-01

337

A Model for stress generation and relief in oxide — Metal systems during a temperature change  

Microsoft Academic Search

When an oxidized metal is cooled from a high temperature, stresses are produced at the metal-scale interface, owing to the difference in thermal expansion rates of the oxide and metal. Such stresses become time- and temperature-dependent if the scale or underlying metal creeps as cooling occurs. A model is presented which describes thermally induced stresses in the scale and accounts

John J. Barnes; John G. Goedjen; David A. Shores

1989-01-01

338

The Effect of Particle Size and Ambient Oxidizer Concentration on Metal Particle Ignition  

Microsoft Academic Search

Ignition and combustion of metal particles are strongly influenced by the interference of a persistent layer of condensed metal oxide covering the metal fuel, thereby shielding it from the gaseous oxidizer. The existence of this surface cover sets metals apart from other condensed fuels for which ignition can be described by the theory of surface inflammation, as formulated by Frank-Kamenetzkii.

Dirk Meinköhn

2009-01-01

339

The Color of Mars: Oxidation of Exogenic Metallic Iron  

NASA Astrophysics Data System (ADS)

The origin of the maghemite inferred to be present in the martian soil by the Pathfinder and Viking magnetic properties experiments remains uncertain. Recent experimental results show that metallic iron can be oxidized into maghemite and hematite under conditions similar to the current martian environment. These data suggest that non-aqueous weathering of meteoritic iron could be the source of the pigmenting oxides in the soils on Mars. The discovery of 1% to 7% of a magnetic mineral, believed to be maghemite, by the Viking Landers [1] was confirmed by Pathfinder [2]. The conventional explanation for the origin of the ferric oxides on Mars is based on the dissolution and subsequent oxidation of ferrous iron from silicate minerals in aqueous environments [e.g., 3]. We present the idea that oxides of exogenic, rather than locally derived, iron could be responsible for the Mars surface spectra. This concept is not new [4], but here we introduce a pathway for oxidation without liquid water. New experiments which monitor the conductivity of electron-beam evaporated Fe show that metallic iron can be efficiently converted to oxide in the presence of ultraviolet radiation and oxygen. Analyses of the resulting oxide phases by FTIR techniques show both maghemite and hematite. A test of the meteoritic origin of at least some of the iron at the martian surface can be conducted with a measurement of the Ni content of the soil. Assuming an average of 7% Ni in iron meteorites and assuming roughly a quarter of the Fe at the martian surface is exogenic, 0.1% to 0.5% Ni should be present in the surface soil. [1] Hargraves et al., JGR, 82, 4547-4558, 1977. [2] Hviid et al., Science, 278, 1768-1770, 1997. [3] Burns, Geochimica et Cosmochem. Acta, 57, 4555-4574, 1993. [4] Gibson, Icarus, 13, 96-99, 1970.

Yen, A. S.; Murray, B. C.

1998-09-01

340

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

Microsoft Academic Search

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

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

2002-01-01

341

Heterometallic M/Mn (M=Cu, Co, Zn) acetate complexes as precursors for binary oxides  

NASA Astrophysics Data System (ADS)

A facile one-pot procedure, or so-called “direct synthesis,” was used to prepare the novel heterometallic complexes [M2Mn(OAc)6(bpy)2], where M=Cu (1), Co (2), Zn (3), bpy=2,2?-bipyridyl, with high yields via oxidative dissolution of pure metals in a liquid phase. The complexes were characterized by an elemental analysis, single crystal X-ray diffraction method and FTIR. These complexes are proposed as precursors, whose thermal degradation may lead to the formation of solids possessing nano- to microsize levels of dispersity. The thermal behavior of the complexes obtained was studied by thermal analysis (TG/DTA/DTG) in both air and N2 and also by TPD mass-spectrometry in vacuo. The FTIR, X-ray powder diffraction (PXRD) and thermoanalytical data were used for the identification of the solid products of thermal degradation. The morphology and microstructure of the solid residues were analyzed, using scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX) at mkm and sub-micro levels.

Makhankova, Valeriya G.; Khavryuchenko, Oleksiy V.; Lisnyak, Vladyslav V.; Kokozay, Vladimir N.; Dyakonenko, Viktoriya V.; Shishkin, Oleg V.; Skelton, Brian W.; Jezierska, Julia

2010-11-01

342

Metal-induced oxidative stress and plant mitochondria.  

PubMed

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

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

2011-10-18

343

Metal-Induced Oxidative Stress and Plant Mitochondria  

PubMed Central

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

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

2011-01-01

344

Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.  

PubMed

The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact. PMID:16210171

Abrahamson, John

2002-01-15

345

Reactions of metal ions at surfaces of hydrous iron oxide  

USGS Publications Warehouse

Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

Hem, J. D.

1977-01-01

346

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

347

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

DOEpatents

A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe.sub.2 O.sub.3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

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

2002-01-01

348

Preparation of superacids by metal oxides for reactions of butanes and pentanes  

Microsoft Academic Search

Recent works on preparation of solid superacid catalysts which are active for reactions of butanes and pentanes are reviewed. Sulfated metal oxides are obtained by adsorbing sulfate ion onto amorphous oxides of Fe, Ti, Zr, Hf, Sn, and Si followed by calcination in air; a superacid of Al2O3 is prepared from the crystallized oxide. Superacids by metal oxides are synthesized

Kazushi Arata

1996-01-01

349

Morphological Control of Metal Oxide-Doped Zinc Oxide and Application to Cosmetics  

NASA Astrophysics Data System (ADS)

Zinc oxide shows excellent transparency and ultraviolet radiation shielding ability, and is used for various cosmetics.1-3 However, it possesses high catalytic activity and lower dispersibility. Therefore, spherical particles of zinc oxide have been synthesized by soft solution reaction using zinc nitrate, ethylene glycol, sodium hydroxide and triethanolamine as starting materials. After dissolving these compounds in water, the solution was heated at 90°C for 1 h to form almost mono-dispersed spherical zinc oxide particles. The particle size changed depending on zinc ion concentration, ethylene glycol concentration and so on. Furthermore, with doping some metal ions, the phtocatalytic activity could be decreased. The obtained monodispersed metal ion-doped spherical zinc oxides showed excellent UV shielding ability and low photocatalytic activity. Therefore, they are expected to be used as cosmetics ingredients.

Goto, Takehiro; Yin, Shu; Sato, Tsugio; Tanaka, Takumi

2012-06-01

350

Field-induced resistive switching in metal-oxide interfaces  

SciTech Connect

We investigate the polarity-dependent field-induced resistive switching phenomenon driven by electric pulses in perovskite oxides. Our data show that the switching is a common occurrence restricted to an interfacial layer between a deposited metal electrode and the oxide. We determine through impedance spectroscopy that the interfacial layer is no thicker than 10 nm and that the switch is accompanied by a small capacitance increase associated with charge accumulation. Based on interfacial I-V characterization and measurement of the temperature dependence of the resistance, we propose that a field-created crystalline defect mechanism, which is controllable for devices, drives the switch.

Tsui, S.; Baikalov, A.; Cmaidalka, J.; Sun, Y.Y.; Wang, Y.Q.; Xue, Y.Y.; Chu, C.W.; Chen, L.; Jacobson, A.J. [Department of Physics and Texas Center for Superconductivity and Advanced Materials, University of Houston, 202 Houston Science Center, Houston, Texas 77204-5002 (United States); Department of Physics and Texas Center for Superconductivity and Advanced Materials, University of Houston, 202 Houston Science Center, Houston, Texas 77204-5002, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Hong Kong University of Science and Technology, Hong Kong (China); Department of Chemistry, University of Houston, 136 Fleming Building, Houston, Texas 77204-5003 (United States)

2004-07-12

351

Equillbrating metal-oxide cluster ensembles for oxidation reactions using oxygen in water  

Microsoft Academic Search

. Particularly problematic is the fact that oxidation ofsubstrates by O2 involves radical chemistry, which is intrinsically non-selective and difficult to control. In addition, metallo-organic catalysts are inherently susceptible to degra- dation5 by oxygen-based radicals, while their transition-metal- ion active sites often react with water to give insoluble, and thus inactive, oxides or hydroxides7. Furthermore, pH control is often requiredto

Ira A. Weinstock; Elena M. G. Barbuzzi; Michael W. Wemple; Jennifer J. Cowan; Richard S. Reiner; Dan M. Sonnen; Robert A. Heintz; James S. Bond; Craig L. Hill

2001-01-01

352

Synthesis, characterization, and property measurement of novel metal-oxide-metal heterojunction nanowires with ferroelectric functionality  

NASA Astrophysics Data System (ADS)

A new "bottom-up" paradigm of electronics offers the possibility of assembling virtually any electronic device using nanoscale building blocks to provide functionality. Essential to this vision is the synthesis of such building blocks with customized composition, morphology, and properties in a reproducible, controlled manner. In the case of functional oxides, extensive studies have been carried out synthesizing all-oxide nanowires that are assembled across metal contact-pad electrodes to create devices. However, there are drawbacks to this approach including: high ohmic losses; the active oxide region is determined by spacing of the electrodes; the contacts made to the functional segment are on the side-wall of the nanowire; and making reproducible contacts over a range of devices is difficult. In this context, metal-oxide-metal (MOM) heterojunction nanowires, where two Au nanowires are separated by a nanoscale segment of a functional oxide, offer several advantages over all-oxide nanowires. The MOM nanowire structure precisely defines the active oxide region within the building block itself and the metal interconnects are integrated within the building block making them more suitable for device assembly. In addition, the small interfacial area of the metal interconnects to the oxide offer the possibility of measuring coupled electronic properties of nanoscale volumes of oxides without substrate effects. In this work, a novel method is developed to synthesize Au-TiO2 -Au, Au-BaTiO3-Au and Au-PbTiO3-Au MOM heterojunction nanowires. This is the first report of successful synthesis of MOM nanowires with ternary oxides. Results from the synthesis and characterization of these nanowires are presented. In order to measure properties of these nanowires, single-nanowire-based devices are fabricated using the focused ion beam (FIB) direct write method to make connections to macroscale electrode pads. The charge transport properties are measured and show a non-linear, non-rectifying response. This response is shown to be due to a transition between ohmic and space-charge-limited-conduction (SCLC) and is investigated using Au-NiO-Au nanowires as a model system. In the Au-BaTiO3-Au and Au-PbTiO3-Au nanowire system, ferroelectric polarization measurements are performed using both electrical measurements and a scanning probe microscope approach.

Herderick, Edward D.

353

Fabrication of porous materials (metal, metal oxide and semiconductor) through an aerosol-assisted route  

NASA Astrophysics Data System (ADS)

Porous materials have gained attraction owing to their vast applications in catalysts, sensors, energy storage devices, bio-devices and other areas. To date, various porous materials were synthesized through soft and hard templating approaches. However, a general synthesis method for porous non-oxide materials, metal alloys and semiconductors with tunable structure, composition and morphology has not been developed yet. To address this challenge, this thesis presents an aerosol method towards the synthesis of such materials and their applications for catalysis, hydrogen storage, Li-batteries and photo-catalysis. The first part of this thesis presents the synthesis of porous metals, metal oxides, and semiconductors with controlled pore structure, crystalline structure and morphology. In these synthesis processes, metal salts and organic ligands were employed as precursors to create porous metal-carbon frameworks. During the aerosol process, primary metal clusters and nanoparticles were formed, which were coagulated/ aggregated forming the porous particles. Various porous particles, such as those of metals (e.g., Ni, Pt, Co, Fe, and Ni xPt(1-x)), metal oxides (e.g., Fe3O4 and SnO2) and semiconductors (e.g., CdS, CuInS2, CuInS 2x-ZnS(1-x), and CuInS2x-TiO2(1-x)) were synthesized. The morphology, porous structure and crystalline structure of the particles were regulated through both templating and non-templating methods. The second part of this thesis explores the applications of these materials, including propylene hydrogenation and H2 uptake capacity of porous Ni, NiPt alloys and Ni-Pt composites, Li-storage of Fe3O4 and SnO2, photodegradation of CuInS2-based semiconductors. The effects of morphology, compositions, and porous structure on the device performance were systematically investigated. Overall, this dissertation work unveiled a simple synthesis approach for porous particles of metals, metal alloys, metal oxides, and semiconductors with controlled compositions and structures for broad spectrum of applications.

Sohn, Hiesang

354

Process for the preparation of pulverulent metallic oxides from metallic nitrates  

US Patent & Trademark Office Database

Process for the preparation of pulverulent metallic oxides with predetermined reactivity which is adjusted by the specific surface area, which are intended to be subjected to subsequent conversions, by thermal treatment of corresponding nitrates in the form of an aqueous solution or of a solids material, consisting of hydrated uranyl nitrate, on its own or in admixture with at least one of thorium nitrate, cerium nitrate and plutonium nitrate, which process is characterized in that it consists of two treatment stages: (a) the first stage essentially consisting of incompletely dehydrating the hydrated uranyl nitrate. (b) the second stage essentially consisting of decomposing the product resulting from the first stage by calcination under controlled steam pressure. The process is used for obtaining uranium oxide on its own or in admixture with thorium oxide, cerium oxide and plutonium oxide, with a view to subsequent chemical conversions and/or sintering.

1987-08-18

355

Oxygen Partial Pressure: A Key to Alloying and Discovery in Metal Oxide--Metal Eutectic Systems.  

National Technical Information Service (NTIS)

Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Po sub 2 sens...

J. D. Holder G. W. Clark B. F. Oliver

1978-01-01

356

Metal Oxide Decomposition In Hydrothermal Alkaline Sodium Phosphate Solutions  

SciTech Connect

Alkaline hydrothermal solutions of sodium orthophosphate (2.15 < Na/P < 2.75) are shown to decompose transition metal oxides into two families of sodium-metal ion-(hydroxy)phosphate compounds. Equilibria for these reactions are quantified by determining phosphate concentration-temperature thresholds for decomposition of five oxides in the series: Ti(IV), Cr(III), Fe(III, II), Ni(II) and Zn(II). By application of a computational chemistry method General Utility Lattice Program (GULP), it is demonstrated that the unique non-whole-number Na/P molar ratio of sodium ferric hydroxyphosphate is a consequence of its open-cage structure in which the H{sup +} and excess Na{sup +} ions are located.

S.E. Ziemniak

2003-09-24

357

Colossal dielectric constants in transition-metal oxides  

NASA Astrophysics Data System (ADS)

Many transition-metal oxides show very large (“colossal”) magnitudes of the dielectric constant and thus have immense potential for applications in modern microelectronics and for the development of new capacitance-based energy-storage devices. In the present work, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant, especially emphasising effects generated by external and internal interfaces, including electronic phase separation. In addition, we provide a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related systems, which is today’s most investigated material with colossal dielectric constant. Also a variety of further transition-metal oxides with large dielectric constants are treated in detail, among them the system La2-xSrxNiO4 where electronic phase separation may play a role in the generation of a colossal dielectric constant.

Lunkenheimer, P.; Krohns, S.; Riegg, S.; Ebbinghaus, S. G.; Reller, A.; Loidl, A.

2009-12-01

358

Synthesis and Characterization of Multifunctional Epitaxial Metal-oxide Films  

NASA Astrophysics Data System (ADS)

Transition metal-oxides have attracted great attention due to their versatile properties. Multilayers, and/or artificial superlattices, are especially interesting since these architectures usually exhibit unique physical properties in comparison with single phase thin films. Furthermore, the lattice strains and the coupling in the multilayered systems can strongly affect the films' growth and their physical properties. We have grown and characterized different multilayered metal-oxide thin films using laser molecular beam epitaxy (MBE). Specifically, we have prepared [(BiFeO3)n/(La0.7Sr0.3MnO3)n]m and [(BiFeO3)n/(BiMnO3)n]m superlattices and strained BiFeO3 (BFO) 0.5: BiMnO3 (BMO) 0.5 films. We have systematically investigated the strain states on the magnetic properties of these multilayer films.

Xiong, Jie; Zhai, Junyi; Zou, Guifu; Wang, Haiyan; Yan, Li; Zhuo, Mujin; Zhang, Yingying; Tao, Bowan; Li, Yanrong; MacManus-Driscoll, J. L.; Jia, Quanxi

2011-03-01

359

Understanding organic film behavior on alloy and metal oxides.  

PubMed

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 were 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; Quiñones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash; Gawalt, Ellen S

2010-02-01

360

Spin-Orbit Interaction Rediscovered in Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

The 5d-transition metal oxides are a class of novel materials that exhibit nearly every collective state known for solids. It is commonly expected that iridium oxides should be more metallic and less magnetic than their 3d and 4f counterparts due to the extended nature of the 5d orbitals. In marked contrast, many iridates are magnetic insulators that exhibit a large array of phenomena seldom or never seen in other materials. We review the anomalous physical properties of several iridates and address potential underlying mechanisms, which include strong orbital magnetism, the Jeff = .5ex1 -.1em/ -.15em.25ex2 insulating state, and spin-orbit coupling; the latter strongly competes with other interactions to create an unusual balance between relevant degrees of freedom in this class of materials.

Cao, Gang

2011-03-01

361

Ultralow-Density Nanocage-Based Metal-Oxide Polymorphs  

Microsoft Academic Search

For two important metal oxides (MO, M=Mg, Zn) we predict, via accurate electronic structure calculations, that new low-density nanoporous crystalline phases may be accessible via the coalescence of nanocluster building blocks. Specifically, we consider the assembly of cagelike (MO)12 clusters exhibiting particularly high gas phase stability, leading to new polymorphs with energetic stabilities rivaling (and sometimes higher) than those of

Javier Carrasco; Francesc Illas; Stefan T. Bromley

2007-01-01

362

Wear resistance of gasothermic metal-oxide coatings  

Microsoft Academic Search

An investigation was carried out into the effect of composition of material being deposited in the application of a metal-oxide coating on the wear resistance of a frictional pair incorporating such a coating and, for purposes of comparison, a chromium electrodeposit. It was established that the wear of a Mo-Al2O3 coating as a function of Al2O3 content has a minimum.

A. D. Sokolov; I. M. Fedorchenko; E. I. Ishchenko

1983-01-01

363

Framework Materials Composed of Transition Metal Oxide Clusters  

Microsoft Academic Search

Transition metal oxide clusters and their derivatives, which are important in such diverse fields as analytical chemistry,\\u000a biochemical and geochemical processes, chemical sensing, catalysis, materials science, and medicine offer an unmatched variety\\u000a of attractive building block units for the design and development of new materials whose properties could possibly be correlated\\u000a with their constituent units at the molecular level. For

M. Ishaque khan

364

Surface Ionization Gas Detection on Platinum and Metal Oxide Surfaces  

Microsoft Academic Search

Surface ionization (SI) gas detection experiments have been performed on platinum (Pt) and metal oxide (MOX) films. The probability of surface ion emission varies with temperature in an Arrhenius-type manner. Among all hydrocarbons studied so far those with amine functional groups exhibited the lowest activation energies allowing detection in the ppm concentration range at emitter operation temperatures of about 400degC.

A. Hackner; A. Habauzit; G. Muller; E. Comini; G. Faglia; G. Sberveglieri

2009-01-01

365

Didactic simulation of a metal oxide semiconductor structure  

Microsoft Academic Search

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

Hamid Magrez; K. Kassmi; A. Ziyyat

2009-01-01

366

Engineering aspects of the aqueous noble metal catalysed alcohol oxidation  

Microsoft Academic Search

The aqueous noble metal catalysed alcohol oxidation is a reaction which can profitably be applied in fine-chemistry and for carbohydrate conversion. In this paper engineering aspects of this reaction are treated, i.e. the reaction kinetics, oxygen mass transfer restrictions, catalyst deactivation and reactivation, and implications for reactor design and operation.First a reaction mechanism is proposed, which is very helpful for

J. H. J Kluytmans; A. P Markusse; B. F. M Kuster; GBMM Marin; J. C Schouten

2000-01-01

367

Plutonium metal and oxide container weld development and qualification  

Microsoft Academic Search

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

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

1996-01-01

368

High-frequency characteristics of metal\\/native-oxide multilayers  

Microsoft Academic Search

The high-frequency magnetization dynamics of magnetically soft CoxFe100-x metal\\/native-oxide multilayers were studied as a function of alloy composition (10 ? x ? 50) using a time-domain inductive technique. The data show intrinsic resonance frequencies ranging from 2.1 to 3.7 GHz due to the variation of anisotropy field with x. The frequencies are consistent with a simple ferromagnetic resonance (FMR) response,

G. S. D. Beach; T. J. Silva; F. T. Parker; A. E. Berkowitz

2003-01-01

369

Micromachined metal oxide gas sensors: opportunities to improve sensor performance  

Microsoft Academic Search

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

Isolde Simon; Nicolae Bârsan; Michael Bauer; Udo Weimar

2001-01-01

370

Polymer\\/Metal Oxide Nanocrystals Hybrid Solar Cells  

Microsoft Academic Search

In this paper, we present two different types of polymer\\/metal oxide nanocrystals hybrid photovoltaics. One is the poly(3-hexylthiophene) (P3HT)\\/TiO2 nanorods hybrid bulk heterojunction (BHJ) solar cell and the other is a nanostructured ZnO\\/P3HT hybrid solar cell. In a BHJ hybrid solar cell, the dispersed semiconducting nanocrystals lead to an increased interface area between polymer and nanocrystals, which can assist charge

Shao-Sian Li; Yun-Yue Lin; Wei-Fang Su; Chun-Wei Chen

2010-01-01

371

Electron beam induced current analysis of metal oxide silicon structures  

Microsoft Academic Search

This thesis presents the history and the development of the scanning electron microscopy (SEM) of Metal-Oxide-Silicon structures by the Electron-Beam-Induced-Current technique (MOS\\/EBIC) through the year 1997. General experimental results are described which reveal the behavior of MOS capacitor structures under the influence of electron beam irradiation as well as the developments which led in a very natural way to a

Harry Robert Kirk

1998-01-01

372

Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring  

PubMed Central

Metal oxide semiconductor gas sensors are utilised in a variety of different roles and industries. They are relatively inexpensive compared to other sensing technologies, robust, lightweight, long lasting and benefit from high material sensitivity and quick response times. They have been used extensively to measure and monitor trace amounts of environmentally important gases such as carbon monoxide and nitrogen dioxide. In this review the nature of the gas response and how it is fundamentally linked to surface structure is explored. Synthetic routes to metal oxide semiconductor gas sensors are also discussed and related to their affect on surface structure. An overview of important contributions and recent advances are discussed for the use of metal oxide semiconductor sensors for the detection of a variety of gases—CO, NOx, NH3 and the particularly challenging case of CO2. Finally a description of recent advances in work completed at University College London is presented including the use of selective zeolites layers, new perovskite type materials and an innovative chemical vapour deposition approach to film deposition.

Fine, George F.; Cavanagh, Leon M.; Afonja, Ayo; Binions, Russell

2010-01-01

373

In vitro evaluation of cytotoxicity of engineered metal oxide nanoparticles.  

PubMed

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, Fe2O3, SnO2 and TiO2, ZnO showed the lowest LD(50) of 21.1 mg/L and TiO2 had the highest LD(50) of 1104.8 mg/L. Data of 14C-glucose mineralization test paralleled the results of bacteria viability test. After regression calculation, the cytotoxicity was found to be correlated with cation charges (R(2) = 0.9785). The higher the cation charge is, the lower the cytotoxicity of the nano-sized metal oxide becomes. To the best of our knowledge, this finding is the first report in nanotoxicology. PMID:19215968

Hu, Xiaoke; Cook, Sean; Wang, Peng; Hwang, Huey-Min

2009-02-12

374

Differential genotoxicity of chemical properties and particle size of rare metal and metal oxide nanoparticles.  

PubMed

Nanoparticles of rare metal compounds are used in various products. However, their carcinogenicity and genotoxicity have not been sufficiently evaluated. The tumor-initiating and -promoting potentials of four rare metals, indium oxide (In2O3), dysprosium oxide (Dy2O3), tungsten oxide (WO3) and molybdenum (Mo), with a well-defined particle diameter were evaluated. The mutagenicity of these rare metals was investigated by Ames test using five bacteria strains, and transformability of these rare metals was investigated by cell-transformation assay using v-Ha-ras-transfected BALB/c 3T3 cells (Bhas 42 cells). Nano-sized Dy2O3 showed strong mutagenesis in all five bacteria strains tested with and without metabolic activation, while micro-sized particles showed weak mutagenesis in two bacterial strains. Dy2O3 induced transformation colonies of Bhas 42 cell dose-dependently, although there was no difference in the number of transformed foci between nano-sized and micro-sized particles. Nano-sized In2O3 and WO3 showed positive mutagenic response in TA1537 and TA98, respectively, whereas the micro-sized metal oxide particles showed no mutagenesis in the test bacterial strains. Both nano-sized and micro-sized In2O3 showed similar levels of transformability. However, nano-sized and micro-sized WO3 did not show any transformability. Both nano-sized and micro-sized Mo particles showed neither mutagenesis nor transformability. These results suggest that mutagenicity of rare metals depends on their particle size, although transformability depends on their chemical components but not on their particle size. PMID:22162085

Hasegawa, Go; Shimonaka, Motoyuki; Ishihara, Yoko

2011-08-23

375

Redox-active metals, oxidative stress, and Alzheimer's disease pathology.  

PubMed

Considerable evidence is mounting that dyshomeostasis of the redox-active biometals, Cu and Fe, and oxidative stress contribute to the neuropathology of Alzheimer's disease (AD). Present data suggest that metals can interact directly with Abeta peptide, the principal component of beta-amyloid that is one of the primary lesions in AD. The binding of metals to Abeta modulates several physiochemical properties of Abeta that are thought to be central to the pathogenicity of the peptide. First, we and others have shown that metals can promote the in vitro aggregation into tinctorial Abeta amyloid. Studies have confirmed that insoluble amyloid plaques in postmortem AD brain are abnormally enriched in Cu, Fe, and Zn. Conversely, metal chelators dissolve these proteinaceous deposits from postmortem AD brain tissue and attenuate cerebral Abeta amyloid burden in APP transgenic mouse models of AD. Second, we have demonstrated that redox-active Cu(II) and, to a lesser extent, Fe(III) are reduced in the presence of Abeta with concomitant production of reactive oxygen species (ROS), hydrogen peroxide (H(2)O(2)) and hydroxyl radical (OH*). These Abeta/metal redox reactions, which are silenced by redox-inert Zn(II), but exacerbated by biological reducing agents, may lead directly to the widespread oxidation damages observed in AD brains. Moreover, studies have also shown that H(2)O(2) mediates Abeta cellular toxicity and increases the production of both Abeta and amyloid precursor protein (APP). Third, the 5' untranslated region (5'UTR) of APP mRNA has a functional iron-response element (IRE), which is consistent with biochemical evidence that APP is a redox-active metalloprotein. Hence, the redox interactions between Abeta, APP, and metals may be at the heart of a pathological positive feedback system wherein Abeta amyloidosis and oxidative stress promote each other. The emergence of redox-active metals as key players in AD pathogenesis strongly argues that amyloid-specific metal-complexing agents and antioxidants be investigated as possible disease-modifying agents for treating this horrible disease. PMID:15105262

Huang, Xudong; Moir, Robert D; Tanzi, Rudolph E; Bush, Ashley I; Rogers, Jack T

2004-03-01

376

Electrical properties of InAlP native oxides for metal-oxide-semiconductor device applications  

Microsoft Academic Search

Data are presented on the insulating properties and capacitance-voltage characteristics of metal-oxide-semiconductor (MOS) device-thickness (below ~100 nm) native oxides formed by wet thermal oxidation of thin InAlP epilayers lattice matched to GaAs. Low leakage current densities of J=1.4×10-9 A\\/cm2 and J=8.7×10-11 A\\/cm2 are observed at an applied field of 1 MV\\/cm for MOS capacitors fabricated with 17 and 48 nm

Y. Cao; J. Zhang; X. Li; T. H. Kosel; P. Fay; D. C. Hall; X. B. Zhang; R. D. Dupuis; J. B. Jasinski; Z. Liliental-Weber

2005-01-01

377

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

DOEpatents

A method of cracking a feedstock by contacting the feedstock with a metal-promoted anion-modified metal oxide catalyst in the presence of hydrogen gas. The metal oxide of the catalyst is one or more of ZrO.sub.2, HfO.sub.2, TiO.sub.2 and SnO.sub.2, and the feedstock is principally chains of at least 20 carbon atoms. The metal-promoted anion-modified metal oxide catalyst contains one or more of Pt, Ni, Pd, Rh, Ir, Ru, (Mn & Fe) or mixtures of them present between about 0.2% to about 15% by weight of the catalyst. The metal-promoted anion-modified metal oxide catalyst contains one or more of SO.sub.4, WO.sub.3, or mixtures of them present between about 0.5% to about 20% by weight of the catalyst.

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

2001-01-01

378

Catalytic oxidation of dimethyl sulfide with ozone: Effects of promoter and physico-chemical properties of metal oxide catalysts  

Microsoft Academic Search

This study reports improved catalytic activities and stabilities for the oxidation of dimethyl sulfide (DMS), a major pollutant of pulp and paper mills. Ozone was used as an oxidant and activities of Cu, Mo, Cr and Mn oxides, and mixed metal oxides supported on ?-alumina, were tested over the temperature ranging from 100 to 200°C. The best catalytic activity was

Venu Gopal Devulapelli; Endalkachew Sahle-Demessie

2008-01-01

379

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

NASA Astrophysics Data System (ADS)

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

Engates, Karen Elizabeth

380

Thermodynamic properties of some metal oxide-zirconia systems  

SciTech Connect

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, N.S.

1989-12-01

381

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

382

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

383

Mossbauer spectra of tin in binary Si-Sn oxide glasses  

Microsoft Academic Search

The Mossbauer spectra of 119Sn in binary glasses of SnO and SiO2, in varying proportions of between 16.8 and 71.5 mol% SnO, have been obtained at 77 K. From these spectra the tin was found to be predominantly in the 2+ state. The isomer shift and the quadrupole splitting were both significantly greater than those in crystalline SnO and were

K. F. E. Williams; C. E. Johnson; J. A. Johnson; D. Holland; M. M. Karim

1995-01-01

384

Polycrystalline oxides formation during transient oxidation of (001) Cu-Ni binary alloys studied by in situ TEM and XRD.  

SciTech Connect

The nucleation and growth of Cu{sub 2}O and NiO islands due to oxidation of Cu{sub x}Ni{sub 1-x} (001) films were monitored, at various temperatures, by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) and in situ synchrotron X-ray diffraction (XRD). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands formed with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. In situ XRD experiments revealed that NiO formed first epitaxially, then other orientations appeared, and finally polycrystalline Cu{sub 2}O developed as the oxidation pressure was increased. The segregation of Ni and Cu towards or away, respectively, from the alloy surface during oxidation could disrupt the surface and cause polycrystalline oxide formation.

Yang, J. C.; Li, Z. Q.; Sun, L.; Zhou, G. W.; Eastman, J. A.; Fong, D. D.; Fuoss, P. H.; Baldo, P. M.; Rehn, L. E.; Thompson, L. J.; Materials Science Division; Univ.of Pittsburgh; State Univ. of New York at Binghamton

2009-01-01

385

Extended Hubbard Models for Transition Metal Oxides and Halides: Importance of Spin and Charge Fluctuations in Charge Transfer Metals  

Microsoft Academic Search

The atomic parameters used in the extended Hubbard (EHB) models for transition metal oxides were determined so as to reproduce ab initio results and experimental results. The EHB model was investigated in relation to classification of transition metal oxides into the Mott-Hubbard and charge transfer (CT) semiconductors. The model calculations indicate that both spin and charge fluctuations are of importance

Kizashi Yamaguchi; Masayoshi Nakano; Hideo Namimoto; Takayuki Fueno

1988-01-01

386

Molecular dynamics study of the binary Cu{sub 46}Zr{sub 54} metallic glass motivated by experiments: Glass formation and atomic-level structure  

SciTech Connect

We have identified a binary bulk metallic glass forming alloy Cu{sub 46}Zr{sub 54} by analyzing the structure and thermal behaviors of copper mold cast samples using x-ray diffraction, transmission electron microscopy, and differential scanning calorimeter. Motivated by these experimental results, we fitted the effective Rosato-Guillope-Legrand-type force field parameters for the binary Cu-Zr alloy system and the atomistic description of glass formation and structure analysis of the Cu{sub 46}Zr{sub 54} alloy based on molecular dynamics simulation will be also presented.

Duan Gang; Xu Donghua; Johnson, William L. [W.M. Keck Laboratory of Engineering Materials, 138-78, California Institute of Technology, 1200 E California Boulevard, Pasadena, California 91125 (United States); Zhang Qing; Zhang Guoyun; Goddard, William A. III [Materials and Process Simulation Center, 139-74, California Institute of Technology, 1200 E California Boulevard, Pasadena, California 91125 (United States); Cagin, Tahir [Department of Chemical Engineering, Texas A and M University, College Station, Texas 77845 (United States)

2005-06-01

387

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

388

Predicted trends of core-shell preferences for 132 late transition-metal binary-alloy nanoparticles.  

PubMed

Transition-metal alloyed nanoparticles with core-shell features (shell enrichment by one of the metals) are becoming ubiquitous, from (electro-)catalysis to biomedical applications, due to their size control, performance, biocompatibility, and cost. We investigate 132 binary-alloyed nanoparticle systems (groups 8 to 11 in the Periodic Table) using density functional theory (DFT) and systematically explore their segregation energies to determine core-shell preferences. We find that core-shell preferences are generally described by two independent factors: (1) cohesive energy (related to vapor pressure) and (2) atomic size (quantified by the Wigner-Seitz radius), and the interplay between them. These independent factors are shown to provide general trends for the surface segregation preference for atoms in nanoparticles, as well as semi-infinite surfaces, and give a simple correlation (a "design map") for the alloying and catalytic behavior. Finally, we provide a universal description of core-shell preference via tight-binding theory (band-energy differences) that (i) quantitatively reproduces the DFT segregation energies and (ii) confirms the electronic origins and correlations for core-shell behavior. PMID:19754042

Wang, Lin-Lin; Johnson, Duane D

2009-10-01

389

Negative ion photoelectron spectroscopy of metal clusters, metal-organic clusters, metal oxides, and metal-doped silicon clusters  

NASA Astrophysics Data System (ADS)

The techniques of time-of-flight mass spectrometry and negative ion photoelectron spectroscopy were utilized to study metal clusters (Mgn -, Znn-, Can -, Mnn-, CuAln -, LiAln-, and NmSn n-), metal-organic complexes (Tin(benzene) m-, Fn(benzene)m- , Nin(benzene)m-), metal oxides(AuO-, PtO-, TaOn -, HfO2-, and MnnO -), and metal-doped semiconductor clusters (CrSin -, GdmSin- and HoSi n-). The study of magnesium and zinc cluster anions shows that they have magic numbers at size 9, 19 and 34, and the closures and reopenings of the s-p band gap are related to the mass spectra magic numbers. The evolution of electronic structure in Can clusters resembles that of Mgn - and Znn- with band gap closure and reopening. However, the electronic structures Can- clusters are more complicated and the magic numbers are different from those of Mgn- and Znn -. That might due to the involvement of calcium's empty d orbitals. In Mn clusters, a dramatic change of electronic structure was observed at Mn5-. The transition of metallic and magnetic properties is strongly related to the s-d hybridization. The photoelectron study of LiAln- is consistent with theoretical predictions, which described LiAl13 as alkali-halide-like ionic entity, Li+(Al13)-. The results of CuAln- show that copper atom might occupy interior position in these clusters. The results of Nam Snn- implied that Na4Sn 4 and NaSn5- could be described as (Na +)4Sn44- and (Na +)Sn52-, respectively. The formation of these species indicates the existence of Zintl phase structure in the gas phase. Tin(Bz)n+1- clusters have multiple-decker sandwich structures with each titanium atom located between two parallel benzene rings. The structures of Fen(Bz)m - and Nin(Bz)m- are characterized with a metal cluster core caged by benzene molecules. The information for the electronic states of PtO, AuO, and TaOn (n = 1--3) were obtained from the photoelectron spectra of their corresponding negative ions. The coincidence between electron affinity and thermodynamic stability was observed in the investigation of ZrO2 - and HfO2-. The studies of MnnO- revealed that addition of oxygen atom could change the magnetic momentum and magnetic coupling in the Mn clusters. The photoelectron spectra of CrSin- (n = 8--12) support the earlier theoretical calculations which found CrSi 12 to be an enhanced stability cluster with its chromium atom encapsulated inside a silicon cage and with its magnetic moment completely quenched by the effects of the surrounding cage. The preliminary results of GdSi n- show that GdSi4, GdSi6 and GdSi9 might be different from their counterparts.

Zheng, Weijun

390

Energy expression of the chemical bond between atoms in metal oxides  

Microsoft Academic Search

The chemical bond between atoms in metal oxides is expressed in an energy scale. Total energy is partitioned into the atomic energy densities of constituent elements in the metal oxide, using energy density analysis. The atomization energies, ?EM for metal atom and ?EO for O atom, are then evaluated by subtracting the atomic energy densities from the energy of the

Yoshifumi Shinzato; Yuki Saito; Masahito Yoshino; Hiroshi Yukawa; Masahiko Morinaga; Takeshi Baba; Hiromi Nakai

2011-01-01

391

Medium-range icosahedral order in quasicrystal-forming Zr2Pd binary metallic glass  

NASA Astrophysics Data System (ADS)

Medium-range order in Zr2Pd metallic glass was studied using a combination of x-ray diffraction experiment and atomistic simulations. We show that, in contrast to earlier experimental interpretations, the icosahedral-like polyhedron is centered around Pd, rather than Zr. Furthermore, we find that the ordered icosahedral packing around Pd extends to the third shell in the way similar to that in the Bergman-type clusters. The existence of Bergman-type clusters sheds interesting light into the formation of nanoquasicrystal phase during crystallization process of Zr2Pd metallic glass.

Huang, Li; Fang, X. W.; Wang, C. Z.; Kramer, M. J.; Ding, Z. J.; Ho, K. M.

2011-06-01

392

(S)TEM analysis of functional transition metal oxides  

NASA Astrophysics Data System (ADS)

Perovskite vanadates (AVO3) form an ideal family to study the structure-property relationships in transition metal oxides because their physical properties can easily be tailored by varying the A-site cations. (S)TEM is an ideal tool for this type of study due to its capacity for simultaneous imaging and chemical analysis. Determination of the oxidation state of vanadium in complex oxides have been carried out by electron energy loss spectroscopy. SrVO3/LaAlO3 is then studied both experimentally and theoretically as a prototype system. Extra electrons have been detected on the interface layer, and further proven to originate mainly from a change in the local bonding configuration of V at the La-O terminated substrate surface. Cr-containing stainless steel deposited with a LaCrO3 thin-film layer is a promising interconnect material of Solid Oxide Fuel Cells (SOFC). Our investigation on its microstructural evolution reveals that the LaCrO 3 thin film plays a role in inhibiting the growth of an oxide layer on the metal surface and thus protects the surface of the stainless steel. Ca-doped LaCoO3 is a promising SOFC cathode material. The domain structures and the oxidation state of Co in Ca-doped LaCoO3, which are directly related to its mechanical properties and electronic conductivity, are investigated by in-situ TEM and EELS. The formation of microcracks is observed during thermal cycles. Ca-doping in LaCoO3 is shown to not only improve the electronic conductivity of the material, but is also likely to strengthen the grain boundaries. The realization of its application in SOFCs depends on depressing the ferroelastisity to reduce strain formation during thermal cycles. The application of the (S)TEM techniques used for studying the perovskite systems are further extended to other compounds containing transition metal elements. The refractory minerals from Comet 81 P/Wild-2 are studied to investigate the formation of the early solar system. A relatively high Ti3+/Ti 4+ ratio in fassaite and the presence of osbornite indicate that the Comet refractory minerals formed in the inner solar nebula and were later transported to the outer solar system where the comet formed. This implies a much more dynamic and perhaps more violent solar nebula than was previously suspected.

Chi, Miaofang

393

Design and modeling of metal oxide gas sensors  

NASA Astrophysics Data System (ADS)

Detailed theoretical models are presented, and used to facilitate the design of industrial metal oxide gas sensors. By modeling both the sensing mechanisms and the conduction process, these methods optimize the sensitivity and selectivity. A phenomenological approach to the operation of metal oxide gas sensors, the Integrated Reaction Conduction (IRC) model, is introduced. The IRC model consolidates the surface reaction kinetics and electrical conduction through the granular sensor microstructure. A simple relation is established between the sensing mechanism reaction energies and the sensing behavior of n-type oxide sensors. The adsorption and oxidation reaction energies for anatase-phase based TiO2 sensors are extracted from comparisons with experimental data. By predicting the effects of dopants, temperature, and sintering on the sensor response, the IRC model foretells improvement of the sensitivity and other gas sensor properties. The depletion width prior to reducing gas exposure in an n-type metal oxide sensor is calculated by combining the known defect chemistry and the various phenomena determining electron depletion near the oxide surface. These include the charged surface of adsorbed oxygen ions, dopant segregation, and ionic defect accumulation. The sensor response is found to enhance if the depletion width is comparable to the grain size. Affecting the initial depletion width via dopants or ionic defect equilibration provides an alternate route towards sensor response optimization. The Polychromatic Percolation Model (PPM) is introduced, and facilitates the design of a selective n/p composite sensor by predicting the sensor response as a function of the n-type/p-type composition. Conduction through an n-type/p-type composite containing randomly distributed and oriented grains is characterized as a percolation phenomenon, where the overall resistance of the material combines contributions from n-type and p-type pathways. The composite microstructure governs the relative fraction of each pathway type and its respective percolation threshold, while the effective resistance through each pathway is calculated using experimentally measured resistances of single-phase n-type and p-type materials. PPM model calculations match the experimentally measured response of an anatase/rutile TiO2 composite gas sensor, and the conductivity of a ZnO/CuO n/p composite. Using the predictions of the PPM model, a selective n/p composite sensor may be designed.

Chwieroth, Brian Stewart

394

n-Type reduced graphene oxide field-effect transistors (FETs) from photoactive metal oxides.  

PubMed

Graphene is of considerable interest as a next-generation semiconductor material to serve as a possible substitute for silicon. For real device applications with complete circuits, effective n-type graphene field effect transistors (FETs) capable of operating even under atmospheric conditions are necessary. In this study, we investigated n-type reduced graphene oxide (rGO) FETs of photoactive metal oxides, such as TiO(2) and ZnO. These metal oxide doped FETs showed slight n-type electric properties without irradiation. Under UV light these photoactive materials readily generated electrons and holes, and the generated electrons easily transferred to graphene channels. As a result, the graphene FET showed strong n-type electric behavior and its drain current was increased. These n-doping effects showed saturation curves and slowly returned back to their original state in darkness. Finally, the n-type rGO FET was also highly stable in air due to the use of highly resistant metal oxides and robust graphene as a channel. PMID:22422712

Yoo, Heejoun; Kim, Youngmin; Lee, Junghyun; Lee, Hyemi; Yoon, Yeoheung; Kim, Giyoun; Lee, Hyoyoung

2012-03-15

395

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

NASA Astrophysics Data System (ADS)

Typical biological samples are inherently complicated. They may contain a myriad of compounds that are electroactive at the same potential as that used in many electrochemical biosensors. Therefore, a biosensor design feature must be included that either eliminates or blocks the interferents from generating false positive signals. The ability to use an insoluble compound, that of MnO2, in order to oxidize interferents such as ascorbic acid, acetaminophen and uric acid, was investigated in a prototype sensor system at a bias potential of 0.6 V versus Ag/AgCl. Unlike previous work with these materials, a difference between the ability for the metal oxide to oxidize the interferents was observed. Most effective was the capability of MnO2 to oxidize uric acid. Alternatively, the MnO2 had little effect on acetaminophen. The study is both introduced and results are discussed within the context of an implantable glucose sensor.

Houseknecht, Jamie G.; Tapsak, Mark A.

2007-09-01

396

Electronic structures of noble metal- Pd binary alloys studied by photoemission using synchrotron radiation  

Microsoft Academic Search

We have studied eletronic structures of noble metal - Pd alloys by valence band photoemission spectroscopy using synchrotron radiation. By taking advantage of the Cooper minimum phenomena of Pd 4d states, we obtained the partial spectral weights of consitutent atoms including the photoionization matrix element effect. We found that Cu-Pd alloys form a common-band because of the strong hybridization between

S.-J. Oh; Tschang-Uh Nahm

1996-01-01

397

New Binary Compounds of the Alkali Metals with Boron, Silicon, and Germanium.  

National Technical Information Service (NTIS)

Sodium and potassium hexaborides are prepared at high temperature by action of an excess of alkali metals on boron in a sealed iron reactor; the preparation of KB sub 6 requires the use of alpha rhombohedral boron. Some properties of the new compounds are...

P. Hagenmuller R. Naslain M. Pouchard C. Cros

1976-01-01

398

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

2013-01-22

399

Electron magnetic resonance study of transition-metal magnetic nanoclusters embedded in metal oxides  

Microsoft Academic Search

Here, we report on the results of an electron magnetic resonance (EMR) study of a series of Ni\\/ZnO and Ni\\/gamma-Fe2O3 nanocomposites (NCs) to probe the resonance features of ferromagnetic (FM) Ni nanoclusters embedded in metal oxides. Interest in these NCs stems from the fact that they are promising for implementing the nonreciprocal functionality employed in many microwave devices, e.g., circulators.

Vincent Castel; Christian Brosseau

2008-01-01

400

Fabrication of arrays of metal and metal oxide nanotubes by shadow evaporation.  

PubMed

This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The evaporating material enters the porous openings of the AAO membrane and deposits onto the walls of the pores. The membrane is tilted with respect to the column of evaporating material, so the shadows cast by the openings of the pores onto the inside walls of the pores define the geometry of the tubes. Rotation of the membrane during evaporation ensures uniform deposition inside the pores. After evaporation, dissolution of the AAO in base easily removes the template to yield an array of nanotubes connected by a thin backing of the same metal or metal oxide. The diameter of the pores dictates the diameter of the tubes, and the incident angle of evaporation determines the height of the tubes. Tubes up to approximately 1.5 mum in height and 20-200 nm in diameter were fabricated. This method is adaptable to any material that can be vapor-deposited, including indium-tin oxide (ITO), a conductive, transparent material that is useful for many opto-electronic applications. An array of gold nanotubes produced by this technique served as a substrate for surface-enhanced Raman spectroscopy: the Raman signal (per molecule) from a monolayer of benzenethiolate was a factor of approximately 5 x 10(5) greater than that obtained using bulk liquid benzenethiol. PMID:19206613

Dickey, Michael D; Weiss, Emily A; Smythe, Elizabeth J; Chiechi, Ryan C; Capasso, Federico; Whitesides, George M

2008-04-01

401

Removal of Thin (20 Å) Layers of Metals, Metal Oxides, and Ceramics by Mechanical Polishing  

Microsoft Academic Search

The method of vibratory polishing has been applied to the reproducible removal of thin layers from metals, oxides, and ceramics. The rate of removal depends on the hardness of the material being polished, and for the materials tested, i.e., W, Ta, Si, Zr, Au, UO2, Ta2O5, and ZrO2, is in the range of a few atom layers (20 to 50

J. L. Whitton

1965-01-01

402

Metal oxide-modified metal nanoparticles: Synthesis, characterization, and catalytic behavior  

Microsoft Academic Search

This thesis investigates the synthesis, characterization, and catalytic behavior of metal oxide-modified platinum nanoparticles. Synthesis of the Pt nanoparticles used a traditional method for reduction of a Pt salt precursor. This H2(g) driven reduction was performed in the presence of precursors to, or fully synthesized, polyoxometalates. Molybdate, molybdate at high concentration and low pH, or phosphododecamolybdate served as stabilizers in

Nolan Thomas Flynn

2001-01-01

403

Metal Oxide Nanowires As Promising Materials For Miniaturised Electronic Noses  

NASA Astrophysics Data System (ADS)

Nanotechnology is in continuous evolution leading to production of quasi-one dimensional (Q1D) structures in a variety of morphologies: nanowires, nanotubes, nanobelts, nanorods, nanorings, hierarchical structures. In particular, metal oxides represent an appealing category of materials with properties from metals to semiconductors and covering practically all aspects of material science and physics in areas including superconductivity and magnetism. MOX nanowires are crystalline structures with well-defined surface terminations, chemical composition and almost dislocation and defect free. Due to their nanosized dimensions, they can exhibit properties significantly different from their coarse-grained polycrystalline counterpart. The increase in the specific surface causes an enhancement of the surface related properties, such as catalytic activity or surface adsorption, key properties for solid-state gas sensors development. The use of MOX nanowires as gas-sensing materials should reduce instabilities, suffered from their polycrystalline counterpart. The gas experiments confirm good sensing properties and the real integration in low power consumption transducers.

Comini, E.; Faglia, G.; Ferroni, M.; Ponzoni, A.; Sberveglieri, G.

2009-05-01

404

Magnetic behavior of reduced graphene oxide/metal nanocomposites  

NASA Astrophysics Data System (ADS)

The dispersion of metal nanoparticles on reduced graphene oxide (RGO) sheets potentially provides a new way to develop novel catalytic, magnetic, adsorbing, and electrode materials. In this work, we report the structural and magnetic properties of RGO/metal (Bi, Pt, Ni, and Pt-Ni) nanocomposites. Such nanocomposites are successfully synthesized by a facile in situ co-reduction route. The structure, composition, and morphology of the synthesized materials are systematically investigated by X-ray diffraction, inductively coupled plasma-atomic emission spectrometer , and high resolution transmission electronic microscopy. The M-H curve and zero-field-cooled and field-cooled data for RGO, RGO/Ni, and RGO/Pt-Ni nanocomposites exhibit ferromagnetic behaviour. RGO/Pt nanocomposite shows diamagnetic, while RGO/Bi nanocomposite shows lower magnetization compared to that of RGO. Detailed magnetic studies on these nanocomposites and its correlation with microstructural features are presented here.

Sahoo, P. K.; Panigrahy, Bharati; Li, Dan; Bahadur, D.

2013-05-01

405

Biofouling of various metal oxides in marine environment  

NASA Astrophysics Data System (ADS)

Biofouling has induced serious problems in various industrial fields such as marine structures, bio materials, microbially induced corrosion (MIC) etc. The effects of various metals on biofouling have been investigated so far and the mechanism has been clarified to some extent(1,2), and we proposed that Fe ion attracted lots of bacteria and formed biofilm very easily(3). In this study, we investigated the possibility for biofouling of Pseudomonas aeruginosa on various metal oxides such as Fe2O3, TiO2, WO3, AgO, Cr2O3 etc. And in addition of such a model experiment on laboratory scale, they were immersed into actual sea water as well as artificial sea water. As for the preparation of metal oxides, commercial oxide powders were used as starting material and those whose particle sizes were under 100 micrometers were formed into pellets by a press. Some of them were heated to 700 °C and sintered for 10 hours at the temperatures. After the calcinations, they were immersed into the culture of P. aeruginosa at 35 °C in about one week. After the immersion, they were taken out of the culture and the biofouling behaviors were observed by optical microscopy, low pressure scanning electron microscopy (low pressure SEM) etc. Biofouling is generally classified into several steps. Firstly, conditioning films composed of organic matters were formed on specimens. Then bacterial were attached to the specimen's surfaces, seeking for conditioning films as nutrition. Then bacteria formed biofilm on the specimens. In marine environment, more larger living matters such as shells etc would be attached to biofilms. However, in the culture media, only biofilms were formed.

Kougo, T.; Kuroda, D.; Wada, N.; Ikegai, H.; Kanematsu, H.

2012-03-01

406

High Temperature Oxidation and Surface Modification of Binary Aluminide Intermetallic Compounds Using Ion Implantation of Oxygen  

Microsoft Academic Search

This work presents a novel approach to the modification of intermetallic compounds to achieve improved oxidation resistance. In order to bypass problems associated with the transient oxidation stage of alloys and intermetallic compounds, high-dose implants of oxygen are used to form a continuous oxygen saturated layer at room temperature. In order to study the implanted layer using secondary ion mass

Robert Joseph Hanrahan Jr.

1994-01-01

407

Electrowetting at a liquid metal-oxide-semiconductor junction  

NASA Astrophysics Data System (ADS)

A voltage polarity dependent, voltage-induced wetting transition is demonstrated using a liquid metal-oxide-semiconductor (MOS) junction. A droplet of mercury can be made to spread out on an oxidized silicon wafer upon the application of a voltage. The wetting is seen to depend on the doping type and doping density of the silicon--a voltage polarity related asymmetrical electrowetting is observed. Impedance measurements on Al-SiO2-Si MOS capacitors link the space-charge effects with the electrowetting on the Hg-SiO2-Si MOS junction. A modified Young-Lippmann equation for electrowetting at a MOS junction is derived--the model agrees with the experiments.

Arscott, Steve

2013-09-01

408

Application of Metal Alkoxides in the Synthesis of Oxides.  

National Technical Information Service (NTIS)

Powders and thin films of the following simple and complex oxides have been obtained from metal alkoxides: M(11)TiO3 (M=Mg, Ca-Ba), MM1/3B2/3O3 (M=Sr,Ba,M'=Mg-Zn; B=Nb,Ta); MNbO3(M=Li,Na); ZrTiO4; PbTiO3; PST, PLZT-materials; M2BO4 (M=Li,Na; B=Mo,W), Bi2B...

M. I. Yanovskaya E. P. Turevskaya V. G. Kessler

1991-01-01

409

Thiosulfate oxidation: Catalysis of synthetic sphalerite doped with transition metals  

NASA Astrophysics Data System (ADS)

The rate of thiosulfate oxidation to tetrathionate by dissolved molecular oxygen was measured in aqueous suspensions of synthetic sphalerites doped with first row transition metals (Mn, Fe, Co, Ni, Cu). Pure sphalerite and Mn-doped sphalerite show no catalytic activity for this reaction. Catalytic activity increases from Fe to Ni, which has maximum activity, with a slight decrease moving to Cu. The catalytic activity of the doped sphalerites is proportional to the concentration of dopant. This trend in catalytic activity from pure sphalerite to Cu-doped sphalerite can be explained using the band structures of these solids.

Xu, Yong; Schoonen, Martin A. A.; Strongin, Daniel R.

1996-12-01

410

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

411

Electrostatic Cooperativity of Hydroxyl Groups at Metal Oxide Surfaces  

SciTech Connect

The O-H bond distribution of hydroxyl groups at the {110} goethite (R-FeOOH) surface was investigated by molecular dynamics. This distribution was strongly affected by electrostatic interactions with neighboring oxo and hydroxo groups. The effects of proton surface loading, simulated by emplacing two protons at different distances of separation, were diverse and generated several sets of O-H bond distributions. DFT calculations of a representative molecular cluster were also carried out to demonstrate the impact of these effects on the orientation of oxygen lone pairs in neighboring oxo groups. These effects should have strong repercussions on O-H stretching vibrations of metal oxide surfaces.h

Boily, Jean F.; Lins, Roberto D.

2009-09-24

412

Effect of rare earth metal oxide additions to tungsten electrodes  

Microsoft Academic Search

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

Alber A. Sadek; Masao Ushio; Fukuhisa Matsuda

1990-01-01

413

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

414

Bacterial adhesion to glass and metal-oxide surfaces.  

PubMed

Metal oxides can increase the adhesion of negatively-charged bacteria to surfaces primarily due to their positive charge. However, the hydrophobicity of a metal-oxide surface can also increase adhesion of bacteria. In order to understand the relative contribution of charge and hydrophobicity to bacterial adhesion, we measured the adhesion of 8 strains of bacteria, under conditions of low and high-ionic strength (1 and 100 mM, respectively) to 11 different surfaces and examined adhesion as a function of charge, hydrophobicity (water contact angle) and surface energy. Inorganic surfaces included three uncoated glass surfaces and eight metal-oxide thin films prepared on the upper (non-tin-exposed) side of float glass by chemical vapor deposition. The Gram-negative bacteria differed in lengths of lipopolysaccharides on their outer surface (three Escherichia coli strains), the amounts of exopolysaccharides (two Pseudomonas aeruginosa strains), and their known relative adhesion to sand grains (two Burkholderia cepacia strains). One Gram positive bacterium was also used that had a lower adhesion to glass than these other bacteria (Bacillus subtilis). For all eight bacteria, there was a consistent increase in adhesion between with the type of inorganic surface in the order: float glass exposed to tin (coded here as Si-Sn), glass microscope slide (Si-m), uncoated air-side float glass surface (Si-a), followed by thin films of (Co(1-y-z)Fe(y)Cr(z))3O4, Ti/Fe/O, TiO2, SnO2, SnO2:F, SnO2:Sb, A1(2)O3, and Fe2O3 (the colon indicates metal doping, a slash indicates that the metal is a major component, while the dash is used to distinguish surfaces). Increasing the ionic strength from 1 to 100 mM increased adhesion by a factor of 2.0 +/- 0.6 (73% of the sample results were within the 95% CI) showing electrostatic charge was important in adhesion. However, adhesion was not significantly correlated with bacterial charge and contact angle. Adhesion (A) of the eight strains was significantly (P < 10(-25)) correlated with total adhesion free energy (U) between the bacteria and surface (A = 2162e(-1.8U)). Although the correlation was significant, agreement between the model and data was poor for the low energy surfaces (R2 = 0.68), indicating that better models or additional methods to characterize bacteria and surfaces are still needed to more accurately describe initial bacterial adhesion to inorganic surfaces. PMID:15261011

Li, Baikun; Logan, Bruce E

2004-07-15

415

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

416

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

PubMed

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. PMID:23828213

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

2013-07-04

417

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

418

Neutron radiation effects on metal oxide semiconductor (MOS) devices  

NASA Astrophysics Data System (ADS)

The main purpose of this study is to provide the knowledge and data on Deuterium-Tritium (D-T) fusion neutron induced damage in MOS devices. Silicon metal oxide semiconductor (MOS) devices are currently the cornerstone of the modern microelectronics industry. However, when a MOS device is exposed to a flux of energetic radiation or particles, the resulting effects from this radiation can cause several degradation of the device performance and of its operating life. The part of MOS structure (metal oxide semiconductor) most sensitive to neutron radiation is the oxide insulating layer (SiO2). When ionizing radiation passes through the oxide, the energy deposited creates electron-hole pairs. These electron-hole pairs have been seriously hazardous to the performance of these electronic components. The degradation of the current gain of the dual n-channel depletion mode MOS caused by neutron displacement defects, was measured using in situ method during neutron irradiation. The average degradation of the gain of the current is about 35 mA, and the change in channel current gain increased proportionally with neutron fluence. The total fusion neutron displacement damage was found to be 4.8 × 10-21 dpa per n/cm2, while the average fraction of damage in the crystal of silicon was found to be 1.24 × 10-12. All the MOS devices tested were found to be controllable after neutron irradiation and no permanent damage was caused by neutron fluence irradiation below 1010n/cm2. The calculation results shows that (n,?) reaction induced soft-error cross-section about 8.7 × 10-14 cm2, and for recoil atoms about 2.9 × 10-15 cm2, respectively.

Abdul Amir, Haider F.; Chik, Abdulah

2009-09-01

419

Toxicity of metallic ions and oxides to rabbit alveolar macrophages  

SciTech Connect

The effects of soluble compounds and oxides of As, Cd, Cu, Hg, Ni, Pb, Sb, Sn, V, and Zn on oxidative metabolism and membrane integrity of rabbit alveolar macrophages were studied by 24-hr in vitro exposure. Oxidative metabolism induced by phagocytosis of opsonized zymosan was measured by H{sub 2}O{sub 2} and O{sub 2}{sup {minus}} release and by chemiluminescence in the presence of luminol. Membrane integrity was estimated by extracellular LDH activity. Metallic ions and oxides inhibited the release of active oxygen species. Cd(II), As(III), and V(V) were the most toxic elements as measured by all investigated parameters. Cu(II) decreased O{sub 2}{sup {minus}} release and chemiluminescence effectively but H{sub 2}O{sub 2} release and membrane integrity less. Chemiluminescence was decreased strongly by Hg(II) while O{sub 2}{sup {minus}} and H{sub 2}O{sub 2} release were depressed moderately. Zn(II) and Sb(III) compounds caused medium toxicity and the tested Sn, Ni, and Pb compounds showed only faint toxic effects.

Labedzka, M.; Gulyas, H.; Schmidt, N.; Gercken, G. (Univ. of Hamburg (Germany, F.R.))

1989-04-01

420

Physical origin of ion mixing induced amorphization and associated asymmetric growth in the binary metal systems  

NASA Astrophysics Data System (ADS)

It has been clarified that the physical origin for a crystalline metal to transform into amorphous is the collapsing of the crystalline lattice while the solute atoms exceeding its critical solid solubility. In ion beam mixing, there are two major factors influencing the amorphization behavior, i.e. the critical solid solubilities and defect (or damage) creation rates of the two constituent metals and it is accordingly predicted that if there exists any difference between the two metals in achieving their respective critical solid solubilities, asymmetric growth would take place. For the Ni-Sc system, the solid solubilities are almost identical, yet the damage creation rate in Ni is about 3 times of that in Sc. Whereas for the Ni-W system, the damage creation rates are basically the same, yet the solid solubility of Ni in W lattice was much smaller than W in Ni. Carefully performed ion beam mixing experiments indeed revealed an asymmetric amorphization in the two systems with predicted preferential directions. Moreover, similar asymmetric amorphization observed in some other systems could also be well explained by the above principle.

Hu, L.; Li, Z. F.; Lai, W. S.; Liu, B. X.

2003-05-01

421

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

SciTech Connect

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

Egami, Takeshi; Vohs, John M.

2003-02-24

422

THE PARABOLIC GROWTH OP OXIDE SOLID SOLUTIONS ON BINARY ALLOYS: A SEMI-EMPIRICAL APPROACH.  

SciTech Connect

The growth of solid solution oxide scales on alloys has been described by considering either the transport of the cations themselves, or that of the defect species in the oxide lattice. The two approaches have been shown to be similar. However, it has become apparent that the simplified defect model implicitly assumed in previous analyses using the ionic transport approach is not adequate to fully describe the variation of ionic diffusivities with oxygen potential or oxide composition. Further analyses, using a combination of the two approaches, are suggested.

Whittle, D. P.; Gesmundo, F.; Viani, F.

1980-10-01

423

An atomic resolution view at oxidation states in transition metal oxide heterostructures  

NASA Astrophysics Data System (ADS)

In LaMnO3/SrTiO3 (LMO/STO) superlattices the LMO/STO relative layer thickness ratio changes the degree of epitaxial strain within the layers and dramatically affects the physical properties of the system, which can be tuned from insulating, mild ferromagnetic, to metallic ferromagnets. Such behaviors are ultimately related to the oxygen - 3d metal bonds and hence to the occupancies of the partially filled 3d bands, which define their oxidation state. In this talk we will review procedures to measure oxidation states in manganites from electron energy loss spectra obtained in the aberration corrected scanning transmission electron microscope, and apply these techniques to imaging subtle O displacements and measure their effects on the electronic properties of LMO/STO interfaces. These results will be discussed and combined with density functional theory, in connection with the magnetotransport properties.

Varela, M.; Pennycook, S. J.; Pennycook, T. J.; Luo, W.; Pantelides, S. T.; Garcia-Barriocanal, J.; Bruno, F. Y.; Leon, C.; Santamaria, J.

2010-03-01

424

Dispersion characteristics of various metal oxide secondary nanoparticles in culture medium for in vitro toxicology assessment.  

PubMed

The aim of this study is to characterize the dispersion characteristics of various metal oxide nanoparticles and secondary nanoparticle formation in culture medium. Many studies have already investigated the in vitro toxicities of various metal oxide nanoparticles; however, there have been few discussions about the particle transport mode to cells during a period of toxicity assessment. The particle transport mode would strongly affect the amount of uptake by cells; therefore, estimation of the transport mode for various metal oxide particles is important. Fourteen different metal oxide nanoparticle dispersions in a culture medium were examined. The sizes of the secondary nanoparticles were observed to be larger than 100 nm by dynamic light scattering (DLS). According to Stokes law and the Stokes-Einstein assumption, pure metal oxide particles with such sizes should gravitationally settle faster than diffusion processes; however, the secondary metal oxide particles examined in this study exhibited unexpectedly slower gravitational settling rates. The slow gravitational settling kinetics of particles was estimated to be caused by the inclusion of protein into the secondary nanoparticles, which resulted in lower densities than the pure metal oxide particles. The ratios of metal oxide to protein in secondary particles could be affected by the protein adsorption ability of the corresponding metal oxide primary particles. To the best of our knowledge, it was clarified for the first time that stably dispersed secondary metal oxide nanoparticles with slow gravitational settling kinetics are induced by secondary nanoparticles consisting of small amounts of metal oxide particles and large amounts of protein, which results in lower particle densities than the pure metal oxide particles. The estimation of particle dynamics in culture medium using this method would be significant to recognize the inherent toxicity of nanoparticles. PMID:20006982

Kato, Haruhisa; Fujita, Katsuhide; Horie, Masanori; Suzuki, Mie; Nakamura, Ayako; Endoh, Shigehisa; Yoshida, Yasukazu; Iwahashi, Hitoshi; Takahashi, Kayori; Kinugasa, Shinichi

2009-12-13

425

Decontaimination of U-Metal Surface by an Oxidation Etching System.  

National Technical Information Service (NTIS)

A surface oxidation treatment is described to remove surface contamination from uranium (U) metal and/or hydrides of uranium and heavy metals (HM) from U-metal parts. In the case of heavy metal atomic contamination on a surface, and potentially several at...

E. J. Kansa H. C. Weed R. B. Stout R. J. Shaffer

2000-01-01

426

Heavy metal removal from wastewater and leachate co-treatment sludge by sulfur oxidizing bacteria  

Microsoft Academic Search

Heavy metal concentration in sludge is one of the major obstacles for the application of sludge on land. There are various methods for the removal of heavy metals in sludge. Using sulfur oxidizing bacteria for microbiological removal of heavy metals from sludges is an outstanding option because of high metal solubilization rates and the low cost. In this study, bioleaching

L. C. Aralp; A. Erdincler; T. T. Onay

2001-01-01

427

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

Microsoft Academic Search

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

Y. J Feng; X. Y Li

2003-01-01

428

Oxidative stability index of vegetable oils in binary mixtures with meadowfoam oil  

Microsoft Academic Search

The oxidative stability indices (OSI) of several vegetable oils were determined at 110°C. Meadowfoam oil, Limnanthes alba, was found to be the most stable oil with an OSI time of 67.3 h for refined oil and 246.9 h for crude oil. Other oils with good oxidative stabilities were refined high oleic sunflower and crude jojoba oil (Simmondsia chinensis) with OSI

T. A. Isbell; T. P. Abbott; K. D. Carlson

1999-01-01

429

Molten metal electrodes in solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

Molten metal electrodes in solid oxide fuel cells are electrochemically characterized for their possible use in direct carbon oxidation and energy storage. The cells were operated in the battery mode at 973 K, without added fuel, in order to understand the oxidation characteristics of Sb alloys as anodes at electrolyte interfaces. The cells using 50-mol% In-Sb and Sn-Sb mixtures exhibited open-circuit voltages (OCV) of 1.0 and 0.93 V, values similar to those of cells with pure In and Sn anodes respectively, and insulating In2O3 and SnO2 layers formed at the electrolyte interface. The 50-mol% Sb-Bi cell had an OCV of 0.73 V initially, close to that with pure Sb anode. The OCV remained constant until all of the Sb had been oxidized, after which it dropped to 0.43 V, similar to the value for pure Bi. SEM analysis of the spent cell showed two distinct phases, with metallic Bi at the bottom and Sb2O3 at the top. The cell with 50-mol% Sb-Pb anode exhibited an OCV that changed continuously with conversion, from 0.73 V initially to 0.67 V following the addition of charge equivalent to oxidation of 120% the Sb. The total cell impedance remained low for this entire period. EDS measurements on the sectioned Sb-Pb cell suggested formation of a mixed oxide of Pb and Sb. An energy-storage concept using molten Sb as the fuel in a reversible solid-oxide electrochemical cell was tested using a button cell with a Sc-stabilized zirconia electrolyte at 973 K, by measuring the impedances under fuel-cell and electrolyzer conditions for a range of stirred Sb-Sb2O 3 compositions. The Sb-Sb2O3 electrode impedances were found to be on the order of 0.15 ohm.cm2 for both fuel-cell and electrolyzer conditions, for compositions up to 30% Sb and 70% Sb2O3. The OCVs were 0.75 V, independent of conversion. The use of molten neat Ag and alloyed Ag-Sb for direct-carbon anodes in SOFCs has been examined at 1273 K. For Ag, an OCV typical of that expected for carbon oxidation, 1.12 V, was observed when charcoal was mixed with the molten metal. However, the anode impedance was very high, ˜100 ?cm 2. The nature of the electrode losses was investigated by measuring the voltage-current characteristics of a cell in battery mode of Ag anode under fuel cell and electrolysis conditions. The results indicate that the cell potential is governed by the dissolved oxygen concentration in the Ag at the electrolyte interface. The impedance of the electrode is limited by diffusion of oxygen in the Ag phase, due to the low solubility of oxygen in molten Ag. In the case of Ag-Sb alloy as anode with added charcoal, the OCV at 973 K was 0.75 V, the potential associated with equilibrium between Sb and Sb2O3, due to the low solubility of oxygen in the Sb phase. The implications of these results for using molten-Ag electrodes for direct-carbon fuel cells are discussed.

Javadekar, Ashay Dileep

430

Transition-metal-oxide coated titanium electrodes for redox batteries  

NASA Astrophysics Data System (ADS)

The production of porous electrodes with reproducible surface activity for experiments to corroborate predictions of porous electrode theory to ascertain if simple one step outer sphere electron transfer mechanism applies to the ferric-ferrous redox reaction at high reactant/product concentrations in a strong acid chloride medium was investigated. Kinetic rate expressions of this couple under these conditions at the metal oxide surfaces were sought. Coatings of the conductive and active rutile structure form of selected transition metal oxides were desired. Both IrO2 and RuO2 coatings having the rutile structure were prepared by thermal decomposition of their respective hydrated chloride salts. Low over potential exchange current densities of the ferric-ferrous couple were measured in concentrated solution at Pt, RuO2 and IrO2 RDF's. Significant corrections were necessary for ohmic effects, mass transfer effects, and nonuniform current distribution. It is shown that the electrocatalytic activity of RuO2 is comparable to that of Pt while the activity of IrO2 is approximately an order of magnitude less than Pt. The measured free energy of activation was similar for all three substrates and a nonbinding interaction between the couple and the surfaces is suggested. The variation in exchange currents among the different substrates can be attributed to some extent on double layer effects but primarily to crystal structure differences.

Savinell, R. F.

1982-12-01

431

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

432

Metal cations inserted in vanadium-oxide nanotubes  

NASA Astrophysics Data System (ADS)

Vanadium-oxide nanotubes (VOx-NTs) consist of nanosize cylinders of thin, easily bent vanadyl (VOx) wall chains, which are open at both ends. Surfactant molecules (e.g. C12H27N) can be easily trapped in the interior of the nanotube walls. The structure of as-synthesized VOx-NTs are observed to collapse to an amorphous vanadium oxide at temperatures greater than 250 °C. This happens, even under a protective atmosphere. This property makes the VOx-NTs unusable as a catalyst at temperatures between 400 500 °C, which is the temperature range where many applications would exist. In order to increase the thermal stability of VOx-NTs several exchange reactions have been used to modify the original nanotubes. In these reactions metallic cations (Cd2+, Co2+, Mn2+ or Zn2+) were introduced. It was observed that that the morphology of the nanotubes remained unchanged after the exchange reactions were performed. In order to characterize the exchanged VOx-NTs the following analytic techniques were used: scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared, particle-induced X-ray emission and Rutherford backscattering spectrometry. The results showed that the VOx-NTs exchanged with metallic cations have preserved their tubular morphology. However, it has not been possible to fully perform a 100% efficient exchange reaction.

Vera-Robles, L. I.; Naab, F. U.; Campero, A.; Duggan, J. L.; McDaniel, F. D.

2007-08-01

433

Acoustic plane wave preferential orientation of metal oxide superconducting materials  

DOEpatents

A polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0metal oxide in the form of a ceramic slip which has not yet set, orientation of the crystal basal planes parallel with the direction of desired current flow is accomplished by an applied acoustic plane wave in the acoustic or ultrasonic frequency range (either progressive or standing) in applying a torque to each crystal particle. The ceramic slip is then set and fired by conventional methods to produce a conductor with preferentially oriented grains and substantially enhanced current carrying capacity.

Tolt, Thomas L. (North Olmsted, OH); Poeppel, Roger B. (Glen Ellyn, IL)

1991-01-01

434

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

435

Structure and Electrical Resistivities of Liquid Al and Ga Metals and Their Binary Alloys  

NASA Astrophysics Data System (ADS)

The ionic and electronic properties of liquid Al and Ga metals and Al1- x Ga x alloys have been investigated self-consistently. Partial structure factors have been calculated from the solution of the Ornstein-Zernike equation with the hybridized mean spherical approximation closure, and the transferable electron-ion potential of Fiolhais et al. has been used as the input pseudopotential. Two different formulas are used in the electrical resistivity calculation, namely, the Faber-Ziman formula and the modified Ziman's formula suggested by Ferraz-March. The results are compared with each other and experimental values.

Korkmaz, ?.; Korkmaz, S. D.

2012-05-01

436

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

NASA Astrophysics Data System (ADS)

We have studied the interaction of atomic coinage metal anions with water molecules by infrared photodissociation spectroscopy of M-.H2O.Arn 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

2005-08-01

437

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

438

Phase composition of anodic oxide films on transition metals: a thermodynamic approach  

Microsoft Academic Search

The phase composition of anodic oxide films on transition metals is analysed using thermodynamic calculations. The model of an oxide film represents a two-layer system MkOl\\/MmOn, where the outer layer MkOl is the highest oxide, and the inner layer MmOn is the lower oxide of the metal. The changes of the Gibbs energy ?Gr are considered for the reactions of

A. L Pergament; G. B Stefanovich

1998-01-01

439

Enhancement of leaching copper by electro-oxidation from metal powders of waste printed circuit board  

Microsoft Academic Search

Oxidation leaching copper from metal powders of waste printed circuit boards (PCBs) was conducted at room temperature in sulfuric acid solution. The result showed that the copper in metal powders was oxidized by Cu2+ to form CuCl2? in the presence of chloride ion without electrochemical oxidation. Then, CuCl2? was oxidized into CuSO4 by oxygen derived from the air insufflated into

Zhu Ping; Fan ZeYun; Lin Jie; Liu Qiang; Qian GuangRen; Zhou Ming

2009-01-01

440

Electroluminescence at Si band gap energy based on metal-oxide-silicon structures  

Microsoft Academic Search

Room-temperature electroluminescence corresponding to Si band gap energy from metal-oxide-semiconductor structures on both p-type and n-type Si is observed. With very thin oxide grown by rapid thermal oxidation, the metal-oxide-semiconductor structures behave like light emitting diodes. Luminescence is observed under forward bias even with a current density as low as 0.67 A\\/cm2. The physical reason for the electroluminescence is discussed

Ching-Fuh Lin; C. W. Liu; Miin-Jang Chen; M. H. Lee; I. C. Lin

2000-01-01

441

THE BREAKDOWN OF THE PROTECTIVE OXIDE FILM ON TRANSITION METAL ALLOYS  

Microsoft Academic Search

Initial breaks in oxidation curves of iron-chromium alloys were found to ; be associated with the ferriteaustenitic phase transformation. This ; transformation was caused by preferential oxidation of chromium at a rate much ; larger than its replenishment by diffusion the metal-oxide interface. The stress ; resulting from this transformation caused breakdown of the protective oxide film. ; Results indicated

W SMELTZER

1960-01-01

442

Surface Hydroxyl Site Densities on Metal Oxides as a Measure for the Ion-Exchange Capacity  

Microsoft Academic Search

Hydroxyl groups on metal oxide in water are the sites for ion exchange, and the surface hydroxyl site density on oxides is a measure of the ion-exchange capacity. Here, the Grignard reagent method was applied to determine the surface hydroxyl site density of oxide samples. The results were similar to those reported for different oxides with other methods (dehydration by

Hiroki Tamura; Akio Tanaka; Ken-ya Mita; Ryusaburo Furuichi

1999-01-01

443

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 spectros-copy (AP-XPS) and environmental transition electron mi-croscopy (E-TEM). The restructured nanorods are highly active in reducing NO with CO, with 100% selectivity for the formation of N2 in temperatures of 250oC-520oC. AP-XPS and E-TEM studies revealed the nonstoichiometric CoO1-x nanorods with a rock-salt structure as the active phase re-sponsible for the 100% selectivity. This study suggests a route to generate new oxide catalysts. PMID:23731229

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

2013-06-01

444

Solute-atom segregation at symmetric twist and tilt boundaries in binary metallic alloys on an atomic-scale  

SciTech Connect

Monte Carlo and overlapping distributions Monte Carlo (ODMC) techniques are employed to simulate grain boundary (GB) segregation in a number of single-phase binary metallic alloys - the Au-Pt, Cu-Ni, Ni-Pd, and Ni-Pt systems. For a series of symmetric [001] twist and [001] tilt boundaries, with coincident site lattice (CSL) structures, we demonstrate that the Gibbsian interfacial excess of solute is a systematic function of the misorientation angle. We also explore in detail whether the GB solid solution behavior is ideal or nonideal by comparing the results of Monte Carlo and ODMC simulations. The range of binding free energies of specific atomic sites at GBs for solute atoms is also studied. The simulational results obtained demonstrate that the thermodynamic and statistical thermodynamic models commonly used to explain GB segregation are too simple to account for the microscopic segregation patterns observed, and that it is extremely difficult, if not impossible, to extract the observed microscopic information employing macroscopic models. 45 refs., 14 figs., 1 tab.

Rittner, J.D.; Udler, D.; Seidman, D.N. [Northwestern Univ., Evanston, IL (United States)

1996-12-31

445

Preferential Sputtering and Redistribution in Ion-Implanted Binary Metallic Alloys: Comparisons Between Linear and Non-Linear Cascade Effects.  

NASA Astrophysics Data System (ADS)

Three metallic binary alloy systems (Ag-Au, Cu -Zn, Ni-Cr) subjected to ion implantation by a third atomic species have been studied for determination of partial sputtering yields and steady-state surface configurations of the resulting ternary surface alloys. A predictive model has been developed for the description of such systems, based on a quasi-chemical approach for determination of the binding energies of individual atomic species in the matrix of atoms which surround them, and measurements which enable determination of the relative partitioning of energy to the alloy constituents. The results demonstrated good qualitative agreement with the observed preferential sputtering behavior for all systems, and good quantitative agreement for implanted Ag-Au alloy. The model supports the formalism on preferential sputtering proposed by Andersen (3) in which the preferential ejection behavior is a system-dependent fluence-independent constant. High-density collision cascades were produced in Ag, Au and Ag-Au alloy by bombardment with molecular ions; the resulting sputtering behavior was compared with the findings of Thompson and Johar (42). The results suggested that non-linearity in sputtering is not as strong an effect as previously thought, and there appeared to be no significant difference in the surface configurations of alloys produced by atomic and molecular ion implantation.

Vozzo, Frank Robert

446

Phase transformations of alloys on a reactive substrate: Interaction of binary alloys of transition and rare-earth metals with silicon  

Microsoft Academic Search

Transition and rare-earth metals have been found to interact with single-crystal Si in a way that allows a division into three distinct classes: near noble, refractory, and rare earth. Recently, attention has turned to the reaction of their binary alloys with Si. In this paper we will try to demonstrate that by regarding the alloy-Si reaction as a phase transformation

R. D. Thompson; K. N. Tu; G. Ottaviani

1985-01-01

447

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES: Screening-Dependent Study of Superconductivity in 3d-Transition Metals Binary Alloys Superconductors  

Microsoft Academic Search

In the present article, we report the screening-dependent study of the superconducting state parameters (SSPs), viz. electron-phonon coupling strength lambda, Coulomb pseudopotential mu*, transition temperature TC, isotope effect exponent alpha, and effective interaction strength N0V of 3d-band transition metals binary alloys superconductors have been made extensively in the present work using a model potential formalism and employing the pseudo-alloy-atom (PAA)

Aditya M. Vora

2009-01-01

448

Differential plasma protein binding to metal oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticles rapidly interact with the proteins present in biological fluids, such as blood. The proteins that are adsorbed onto the surface potentially dictate the biokinetics of the nanomaterials and their fate in vivo. Using nanoparticles with different sizes and surface characteristics, studies have reported the effects of physicochemical properties on the composition of adsorbed plasma proteins. However, to date, few studies have been conducted focusing on the nanoparticles that are commonly exposed to the general public, such as the metal oxides. Using previously established ultracentrifugation approaches, two-dimensional gel electrophoresis and mass spectrometry, the current study investigated the binding of human plasma proteins to commercially available titanium dioxide, silicon dioxide and zinc oxide nanoparticles. We found that, despite these particles having similar surface charges in buffer, they bound different plasma proteins. For TiO2, the shape of the nanoparticles was also an important determinant of protein binding. Agglomeration in water was observed for all of the nanoparticles and both TiO2 and ZnO further agglomerated in biological media. This led to an increase in the amount and number of different proteins bound to these nanoparticles. Proteins with important biological functions were identified, including immunoglobulins, lipoproteins, acute-phase proteins and proteins involved in complement pathways and coagulation. These results provide important insights into which human plasma proteins bind to particular metal oxide nanoparticles. Because protein absorption to nanoparticles may determine their interaction with cells and tissues in vivo, understanding how and why plasma proteins are adsorbed to these particles may be important for understanding their biological responses.

Deng, Zhou J.; Mortimer, Gysell; Schiller, Tara; Musumeci, Anthony; Martin, Darren; Minchin, Rodney F.

2009-11-01

449

Active metal oxides and polymer hybrids as biomaterials  

NASA Astrophysics Data System (ADS)

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

Jarrell, John D.

450

Experimental Study of Resistive Bistability in Metal Oxide Junctions  

SciTech Connect

We have studied resistive bistability (memory) effects in junctions based on metal oxides, with a focus on sample-to-sample reproducibility, which is necessary for the use of such junctions as crosspoint devices of hybrid CMOS/nanoelectronic circuits. Few-nm-thick layers of NbO{sub x}, CuO{sub x} and TiO{sub x} have been formed by thermal and plasma oxidation, at various deposition and oxidation conditions, both with and without rapid thermal post-annealing. The resistive bistability effect has been observed for all these materials, with particularly high endurance (over 10{sup 3} switching cycles) obtained for single-layer TiO{sub 2} junctions, and the best reproducibility reached for multi-layer junctions of the same material. Fabrication optimization has allowed us to improve the OFF/ON resistance ratio to about 10{sup 3}, but the sample-to-sample reproducibility is so far lower than that required for large-scale integration.

Su, D.; Tan, Z.; Patel, V.; Likharev, K.K.; Zhu, Y.

2011-05-01

451

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

452

Redefining the metal/charge-transfer insulator paradigm in transition metal oxides  

NASA Astrophysics Data System (ADS)

The universality of the phase diagram in the variables of interaction strength and d-occupancy, shown for late transition metal oxides in Ref.[1], is examined for two series of early transition metal oxides: (SrVO3, SrCrO3, SrMnO3) and (LaTiO3, LaVO3, LaCrO3) using density functional theory (DFT), DFT+U and DFT+dynamical mean field theory methods. The interaction required to drive the metal-insulator transition is found to depend sensitively on the d-occupancy Nd, and beyond a threshold value of the d-occupancy an insulating state cannot be achieved for any practical value of the interaction. The critical Nd values are determined and compared to ab initio and experimental estimates where available. Additionally, the minimal model for the transition is determined and the crucial role played by the Hunds coupling is demonstrated. [4pt] [1] Xin Wang, M. J. Han, Luca de' Medici, C. A. Marianetti, and Andrew J. Millis (2011). arXiv:1110.2782

Dang, Hung; Ai, Xinyuan; Marianetti, Chris; Millis, Andrew

2012-02-01

453

Role of lipid oxidation, chelating agents, and antioxidants in metallic flavor development in the oral cavity.  

PubMed

This study investigated the production of metallic flavor, which is a combination of taste and retronasal odor. Chemical reactions in the oral cavity and saliva of healthy subjects were investigated after ingesting iron and copper solutions above and near threshold levels. Significant increase in lipid oxidation (p < 0.001) occurred after metal ingestion, detected as TBARS values. Ferrous ion caused the greatest flavor sensation and lipid oxidation, followed by cupric and cuprous ions. Ferric ion did not cause metallic sensation. Occurrence of oxidation was supported by damage to salivary proteins, detected as protein-carbonyls, and by a significant increase of odorous lipid oxidation related aldehydes. Sensory evaluation demonstrated that antioxidants (vitamins E and C) minimally reduced metallic flavor but that chelating agents (EDTA and lactoferrin) removed the metallic flavor. The role of lipid oxidation is essential for the production of a metallic flavor from ingestion of ferrous, cupric, and cuprous ions. PMID:22304665

Omür-Özbek, Pinar; Dietrich, Andrea M; Duncan, Susan E; Lee, YongWoo

2012-02-21

454

Tunable magnetic properties of metal/metal oxide nanoscale coaxial cables  

NASA Astrophysics Data System (ADS)

We report the synthesis and magnetic characterization of metal/metal oxide one-dimensional heterostructures with a radial geometry—coaxial nanocables. High-density arrays of cobalt and magnetite- (Fe3O4) based nanocables with the diameter of ˜100nm and length of ˜60?m have been synthesized within the pores of anodized aluminum oxide membranes using a supercritical fluid inclusion-phase technique. All investigated heterostructures demonstrate ferrimagnetic/ferromagnetic properties at room temperature. We show that the magnetic properties of cobalt-magnetite nanocables can be tuned by varying the thickness of the sheath and core layers. The exchange bias effect, due to formation of CoO thin layers at the nanocable interfaces, was observed at low temperatures. The strength and manifestation of this effect depends on the structural characteristics and oxidation state of the Co layer. We show that the vast increase of the coercive field (up to 450 times) at low temperatures in samples containing the large fraction of magnetite is caused by a governing influence of the temperature-dependent magnetoelastic term of the anisotropy.

Kazakova, Olga; Daly, Brian; Holmes, Justin D.

2006-11-01

455

Comparison of the charges generated by Fowler-Nordheim tunneling injection in different oxides of metal-oxide-semiconductor capacitors  

Microsoft Academic Search

Fowler-Nordheim tunneling injection was performed, from the gate, in P-type metal-oxide-semiconductor capacitors with HCl, wet or dry oxides and polysilicon gate. Trapped holes, as well as negative and anomalous positive charges were created. In this paper, we establish a classification of quality, based on the magnitude of the stress generated oxide charge density, for the three oxides. The HCl and

G. Yard; A. Meinertzhagen; C. Petit; M. Jourdain; F. Mondon

1997-01-01