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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

Suppressed Thermally Induced Flatband Voltage Instabilities with Binary Noble Metal Gated Metal--Oxide--Semiconductor Capacitors  

NASA Astrophysics Data System (ADS)

We investigated thermally induced flatband voltage (VFB) instabilities with single noble metals (Pt, Ir, Pd), their binary metal (IrPt) and control TiN used for gate electrodes in metal oxide semiconductor devices with atomic layer deposited HfO2 gate dielectric. As-deposited e-beam evaporated noble metals and sputtered TiN gated devices show near band-edge p-type metal--oxide--semiconductor (pMOS) characteristics and higher VFB than midgap value, respectively. After 450 °C at 30 min forming gas anneal, VFB of devices with e-beam evaporated single metals and sputtered TiN is substantially shifted toward mid-gap position, indicating thermally induced VFB instability. However, device with binary metal alloy gate shows suppressed VFB shifts and work-function as high as 4.95 eV is attained with 450 °C at 30 min FGA. It can be explained by oxygen diffusion within gate stack structure into interfacial layer (IL) between Si and HfO2 during anneal, leading to thicker IL and vacancy generation in dielectric.

Choi, Changhwan; Ahn, Jinho; Choi, Rino

2012-02-01

3

Synthesis of Binary Magnesium--Transition Metal Oxides via Inverse Coprecipitation  

NASA Astrophysics Data System (ADS)

Synthesis of binary magnesium--transition metal oxides, MgM2O4 (M: Cr, Mn, Fe, Co) and MgNiO2, was performed by calcination at relatively low temperatures of 500 and 750 °C for 24 h through inverse coprecipitation of carbonate hydroxide precursors. The important roles of the precipitation agent, sodium carbonate, were clarified by considering equilibria in an aqueous solution. The structure parameters of the obtained binary magnesium--transition metal oxide powders, specifically the occupancy of atomic sites, were evaluated from synchrotron X-ray diffraction (XRD) profiles by Rietveld refinement in addition to the magnetic properties at room temperature. The present work provides general guidelines for low-cost and high-volume synthesis of complex oxides, which are easily decomposed at high temperatures.

Yagi, Shunsuke; Ichikawa, Yuya; Yamada, Ikuya; Doi, Takayuki; Ichitsubo, Tetsu; Matsubara, Eiichiro

2013-02-01

4

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

5

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

PubMed

A series of Sn-Mn binary metal oxides were prepared through co-precipitation method. The sorbents were characterized by powder X-ray diffraction (powder XRD), transmission electronic microscopy (TEM), H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) methods. The capability of the prepared sorbents for mercury adsorption from simulated flue gas was investigated by fixed-bed experiments. Results showed that mercury adsorption on pure SnO2 particles was negligible in the test temperature range, comparatively, mercury capacity on MnOx at low temperature was relative high, but the capacity would decrease significantly when the temperature was elevated. Interestingly, for Sn-Mn binary metal oxide, mercury capacity increased not only at low temperature but also at high temperature. Furthermore, the impact of SO2 on mercury adsorption capability of Sn-Mn binary metal oxides was also investigated and it was noted that the effect at low temperature was different comparing with that of high temperature. The mechanism was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs). Moreover, a mathematic model was built to calculate mercury desorption activation energy from Sn to Mn binary metal oxides. PMID:24910043

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

2014-08-15

6

A general nonaqueous route to binary metal oxide nanocrystals involving a C-C bond cleavage.  

PubMed

A widely applicable solvothermal route to nanocrystalline iron, indium, gallium, and zinc oxide based on the reaction between the corresponding metal acetylacetonate as metal oxide precursor and benzylamine as solvent and reactant is presented. Detailed XRD, TEM, and Raman studies prove that, with the exception of the iron oxide system, where a mixture of the two phases magnetite and maghemite is formed, only phase pure materials are obtained, gamma-Ga(2)O(3), zincite ZnO, and cubic In(2)O(3). The particle sizes lie in the range of 15-20 nm for the iron, 10-15 nm for the indium, 2.5-3.5 nm for gallium, and around 20 nm for zinc oxide. GC-MS analysis of the final reaction solution after removal of the nanoparticles showed that the composition is rather complex consisting of more than eight different organic compounds. Based on the fact that N-isopropylidenebenzylamine, 4-benzylamino-3-penten-2-one, and N-benzylacetamide were the main species found, we propose a detailed formation mechanism encompassing solvolysis of the acetylacetonate ligand, involving C-C bond cleavage, as well as ketimine and aldol-like condensation steps. PMID:15826200

Pinna, Nicola; Garnweitner, Georg; Antonietti, Markus; Niederberger, Markus

2005-04-20

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

Sulfated binary oxide solid superacids  

Microsoft Academic Search

Sulfated binary oxide solid superacids were prepared by the chemical method. The structural properties of the catalyst were examined by using BET, XRD, DTA and IR spectroscopy. Acidity properties of the catalysts were tested by Hammett indicator. Catalytic activity of the catalysts was researched by the reaction of glycerin with acetic acid in toluene. The optimum calcined temperature of the

Hua Yang; Rong Lu; Jingzhe Zhao; Xuwei Yang; Lianchun Shen; Zichen Wang

2003-01-01

10

Electrolytic Synthesis of Binary Oxide Systems Based on Manganese(II) Oxide  

Microsoft Academic Search

Joint anodic deposition of manganese, cobalt, nickel, and chromium oxides, which form binary oxide systems, from two-component sulfate solutions of the constituent metals was studied under different electrolysis conditions.

V. M. Nagirnyi; R. D. Apostolova; A. S. Baskevich; P. M. Litvin

2002-01-01

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

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

PubMed

Alkali-metal-ion extraction reactions using poly(tetrafluoroethylene) (PTFE; AEP reactions) were performed on two kinds of ?-NaFeO(2)-type layered compounds: Na(0.68)(Li(0.68/3)Ti(1-0.68/3))O(2) and K(0.70)(Li(0.70/3)Sn(1-0.70/3))O(2). At 400 °C in flowing argon, these layered compounds were reacted with PTFE. By these reactions, alkali-metal ions in the layered compounds were successfully extracted, and TiO(2) and SnO(2) with rutile-type structure were formed. The structural similarity between the alkali-metal-ion-extracted layered compounds and the binary metal oxide products in these unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomic pair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ions from layered compounds, and AEP reaction is not limited to the previously reported ?-FeOOH-type layered titania K(0.8)(Li(0.27)Ti(1.73))O(4), but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, it was clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult to synthesize by other reactions. PMID:22679905

Ozawa, Tadashi C; Sasaki, Takayoshi

2012-07-01

13

Microwave absorption investigation on the formation of YBa 2 Cu 3 O 7?? by a binary metal oxide route involving interaction of BaCuO 2 and Y 2 Cu 2 O 5  

Microsoft Academic Search

Low-field microwave absorption has been used to discriminate between the YBa2Cu3O7?? high temperature superconductor synthesized by reacting the binary metal oxides, BaCuO2 and Y2Cu2O5, versus synthesis with a single metal oxide route. This discrimination is more clearly seen by microwave absorption than\\u000a by resistance measurements. Supplementary data was obtained by electron spin resonance in the g=2 region, scanning electron\\u000a microscopy,

M. Puri; S. Marrelli; J. Bear; L. Kevan

1990-01-01

14

Metal oxide films on metal  

DOEpatents

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

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

1995-01-01

15

Electronic polarizability of the oxide ion and density of binary silicate, borate and phosphate oxide glasses  

NASA Astrophysics Data System (ADS)

A relationship between the polarizability of the oxide ion ?O 2-( no), determined from the refractive index, and the experimental density has been established for binary oxide glasses, such as the systems of silicate, borate and phosphate. Our present conclusions suggest that the ?O 2-( no) values increase with increasing density. The increasing rate of ?O 2-( no) versus density depends strongly on the charge of metals in glasses. For binary glass systems, such as Bi 2O 3-SiO 2, Bi 2O 3-B 2O 3, Sb 2O 3-B 2O 3, Sb 2O 3-P 2O 5 and Bi 2O 3-P 2O 5, the increasing rate of ?O 2-( no) versus density is much larger (an order of magnitude ranging from one to two) than those of binary oxide glasses containing monovalent alkali and divalent metals.

Qi, Ji; Xue, Dongfeng; Ratajczak, Henryk; Ning, Guiling

2004-06-01

16

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

17

Stochastic learning in oxide binary synaptic device for neuromorphic computing.  

PubMed

Hardware implementation of neuromorphic computing is attractive as a computing paradigm beyond the conventional digital computing. In this work, we show that the SET (off-to-on) transition of metal oxide resistive switching memory becomes probabilistic under a weak programming condition. The switching variability of the binary synaptic device implements a stochastic learning rule. Such stochastic SET transition was statistically measured and modeled for a simulation of a winner-take-all network for competitive learning. The simulation illustrates that with such stochastic learning, the orientation classification function of input patterns can be effectively realized. The system performance metrics were compared between the conventional approach using the analog synapse and the approach in this work that employs the binary synapse utilizing the stochastic learning. The feasibility of using binary synapse in the neurormorphic computing may relax the constraints to engineer continuous multilevel intermediate states and widens the material choice for the synaptic device design. PMID:24198752

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

2013-01-01

18

Stochastic learning in oxide binary synaptic device for neuromorphic computing  

PubMed Central

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

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

2013-01-01

19

Fundamentals of metal oxide catalysis  

NASA Astrophysics Data System (ADS)

The properties of metal oxide catalysts and hence, catalytic activity are highly dependent on the composition and structure of these oxides. This dissertation has 3 parts -- all directed towards understanding relationships between structure, composition and activity in metal oxide catalysts. The first part of this dissertation focuses on supported metal oxide catalysts of tungsten, vanadium and molybdenum. Mechanisms are proposed for ethanol oxidative dehydrogenation which is used to probe the acidity and reducibility of these oxide catalysts. These studies are then used to develop a novel method to quantify active redox sites and determine the nature of the active site on these catalysts -- our results show that the intrinsic redox turn-over frequency is independent of the nature of the metal oxide and its loading and that the actual rate obtained over an oxide is only a function of the number of removable oxygen atoms linking the metal to the support. The extension of Ultraviolet-visible Diffuse Reflectance Spectroscopy (UV-vis DRS) to the study of active oxide domains in binary oxide catalysts is demonstrated for distinguishing between interacting and non-interacting domains in binary MoO x-WOx catalysts on alumina. We show also how the rigorous analysis of pre-edge features, absorption white-line intensity and the full width at half maximum of the white-line in X-ray Absorption Spectra provide determinants for metal atom coordination and domain size in supported metal oxide catalysts. The second part of this work looks at effects of structure variations on the activity of polyoxometalate catalysts that are promising for the production of Methacrylic Acid from Isobutane. The use of these catalysts is limited by structural changes that impact their performance -- an "activation" period is required before the catalysts become active for methacrylic acid production and structural changes also lead to degradation of the catalyst, which are also seen during thermal degradation. The affect of reaction conditions on the lifetime of these catalysts is investigated. The structural changes occurring in these catalysts are studied during thermal degradation at the bulk-scale (using UV-vis DRS, XAS and X-ray Diffraction) and at the atomic-scale (using High-Resolution Transmission Electron Microscopy). These studies show that the actual mechanism of structural reorganization occurs through a twinning process which eventually leads to MoO3, which is inactive for methacrylic acid production. This gives new insight into how to make these catalysts commercially attractive. Finally, the design and fabrication of a micro-reactor to perform complete spectroscopic and reactive characterization of supported metal oxide catalysts is presented; we aim to integrate semiconductor microfabrication technology with conventional spectroscopic tools to create cost-effective, simple and flexible tools for catalytic studies.

Nair, Hari

20

Effect of palladium and nickel on the temperature programmed reduction of metal oxides and metal oxide layers  

Microsoft Academic Search

A new binary oxide support was suggested as being useful in many commercial reactions. Our study was focused on the reduction\\u000a effect of metal oxide layer on alumina during reaction. Hence temperature programmed reduction of both bulk metal oxide and\\u000a metal oxide layer on alumina was studied first and the effect of palladium and nickel on the reduction of the

Jong Pal Kim

2004-01-01

21

Superconducting state parameters of binary metallic glasses  

NASA Astrophysics Data System (ADS)

Ashcroft’s empty core (EMC) model potential is used to study the superconducting state parameters (SSPs) viz. electron-phonon coupling strength ?, Coulomb pseudopotential ?*, transition temperature T C , isotope effect exponent ?and effective interaction strength N O V of some binary metallic glasses based on the superconducting (S), conditional superconducting (S’) and non-superconducting (NS) elements of the periodic table. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used for the first time with EMC potential in the present investigation to study the screening influence on the aforesaid properties. The T C obtained from the H-local field correction function are in excellent agreement with available theoretical or experimental data. In the present computation, the use of the pseudo-alloy-atom model (PAA) was proposed and found successful. Present work results are in qualitative agreement with such earlier reported experimental values which confirm the superconducting phase in all metallic glasses. A strong dependency of the SSPs of the metallic glasses on the valence ‘Z’ is identified.

Vora, Aditya M.

2008-06-01

22

Oxidation Behavior of Binary Niobium Alloys  

NASA Technical Reports Server (NTRS)

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

Barrett, Charles A.; Corey, James L.

1960-01-01

23

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

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

Wellinghoff, Stephen T. (Inventor)

1997-01-01

24

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

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

Wellinghoff, Stephen T. (Inventor)

1994-01-01

25

Metal oxide sensors  

Microsoft Academic Search

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

H. Meixner; U. Lampe

1996-01-01

26

Extracting metals directly from metal oxides  

DOEpatents

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

Wai, Chien M. (Moscow, ID) [Moscow, ID; Smart, Neil G. (Moscow, ID) [Moscow, ID; Phelps, Cindy (Moscow, ID) [Moscow, ID

1997-01-01

27

Extracting metals directly from metal oxides  

DOEpatents

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

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

1997-02-25

28

Metal oxide nanowires gas sensors  

Microsoft Academic Search

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

E. Comini

2008-01-01

29

Raman and IR studies of surface metal oxide species on oxide supports: Supported metal oxide catalysts  

Microsoft Academic Search

Raman and infrared spectroscopy provide complementary information about the nature of the surface metal oxide species present in supported metal oxide catalysts. This paper reviews the type of fundamental information that is typically obtained in Raman and IR characterization studies of supported metal oxide catalysts. The molecular structures of the surface metal oxide species are reflected in the terminal M=O

Israel E. Wachs

1996-01-01

30

Metal oxide hollow nanostructures for lithium-ion batteries.  

PubMed

Metal oxide hollow structures have received great attention because of their many promising applications in a wide range of fields. As electrode materials for lithium-ion batteries (LIBs), metal oxide hollow structures provide high specific capacity, superior rate capability, and improved cycling performance. In this Research News, we summarize the recent research activities in the synthesis of metal oxide hollow nanostructures with controlled shape, size,composition, and structural complexity, as well as their applications in LIBs. By focusing on hollow structures of some binary metal oxides (such as SnO 2 ,TiO 2 , Fe 2 O 3 , Co 3 O 4 ) and complex metal oxides, we seek to provide some rational understanding on the effect of nanostructure engineering on the electrochemical performance of the active materials. It is thus anticipated that this article will shed some light on the development of advanced electrode materials for next-generation LIBs. PMID:22574316

Wang, Zhiyu; Zhou, Liang; Lou, Xiong Wen David

2012-04-10

31

Strenfth and Deformation Characteristics of Binary Metal Whiskers.  

National Technical Information Service (NTIS)

The tensile strength of a large number of Fe, Fe-Cu, Fe-Co, Cu and Cu-Co whiskers with diameters ranging from 20 to 300 microns has been measured at room temperature and at elevated temperatures. The results indicate that the binary metal whiskers of the ...

N. P. Chou T. S. Ke

1965-01-01

32

Critical Behavior of Metallic Immiscible Liquid Binary Systems.  

National Technical Information Service (NTIS)

Different aspects of the critical behavior of the metallic binary systems Ga-Hg and Li-Na have been investigated experimentally. In the Ga-Hg system the coexistence curve was determined by measuring the electrical resistivities of the two distinct layers ...

H. K. Schuermann

1971-01-01

33

Spectroscopic Metallicity Determinations for W UMa-type Binary Stars  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

34

SPECTROSCOPIC METALLICITY DETERMINATIONS FOR W UMa-TYPE BINARY STARS  

SciTech Connect

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

Rucinski, Slavek M. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Pribulla, Theodor; Budaj, Jan, E-mail: rucinski@astro.utoronto.ca, E-mail: pribulla@ta3.sk, E-mail: budaj@ta3.sk [Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranska Lomnica (Slovakia)

2013-09-15

35

Lithium metal reduction of plutonium oxide to produce plutonium metal  

Microsoft Academic Search

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

Coops

1992-01-01

36

Thin film hydrous metal oxide catalysts  

DOEpatents

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

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

1995-01-01

37

Lithium metal reduction of plutonium oxide to produce plutonium metal  

Microsoft Academic Search

A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used

Coops; Melvin S

1992-01-01

38

109Ag chemical shifts of different silver oxidation states in binary and ternary silver oxides  

Microsoft Academic Search

Here we present 109Ag solid state magic angle spinning (MAS) NMR spectra for different silver oxides, binary as well as ternary. It is shown that the chemical shift of silver nuclei is strongly dependent on the silver oxidation state in these compounds and can thus serve as means to identify the silver oxidation state in new materials.

Leo van Wüllen; Sascha Vensky; Wilfried Hoffbauer; Martin Jansen

2005-01-01

39

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

40

Lithium metal reduction of plutonium oxide to produce plutonium metal.  

National Technical Information Service (NTIS)

A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha 5 plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by s...

M. S. Coops

1991-01-01

41

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

42

Thermodynamics of Liquid Alkali Metals and Their Binary Alloys  

NASA Astrophysics Data System (ADS)

The theoretical investigation of thermodynamic properties like internal energy, entropy, Helmholtz free energy, heat of mixing (?E) and entropy of mixing (?S) of liquid alkali metals and their binary alloys are reported in the present paper. The effect of concentration on the thermodynamic properties of Ac1Bc2 alloy of the alkali-alkali elements is investigated and reported for the first time using our well established local pseudopotential. To investigate influence of exchange and correlation effects, we have used five different local field correction functions viz; Hartree(H), Taylor(T), Ichimaru and Utsumi(IU), Farid et al. (F) and Sarkar et al. (S). The increase of concentration C2, increases the internal energy and Helmholtz free energy of liquid alloy Ac1Bc2. The behavior of present computation is not showing any abnormality in the outcome and hence confirms the applicability of our model potential in explaining the thermodynamics of liquid binary alloys.

Thakor, P. B.; Patel, Minal H.; Gajjar, P. N.; Jani, A. R.

2009-07-01

43

Lithium metal reduction of plutonium oxide to produce plutonium metal  

DOEpatents

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

Coops, Melvin S. (Livermore, CA)

1992-01-01

44

Infrared spectroscopy of supported metal oxide catalysts  

Microsoft Academic Search

In situ infrared spectroscopy can provide much fundamental information about the nature of the surface metal oxide species present in supported metal oxide catalysts. The molecular structure of the surface metal oxide species can be obtained from M=O vibrations (number of different species and the number of terminal M=O bonds present in each species). The location of the surface metal

Israel E. Wachs

1995-01-01

45

Oxidation of Tungsten and Other Refractory Metals.  

National Technical Information Service (NTIS)

Contents: Methods for studying high temperature oxidation reactions, High pressure oxidation of refractory metals - experimental methods and interpretation, Initial stages of the oxidation of tungsten and tantalum, Four types of oxidation processes in the...

1965-01-01

46

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part I: Binary Systems with Fe203 and Sn02 as Oxidants  

Microsoft Academic Search

Abstract– The results of a detailed study of the combustion of several binary silicon\\/oxidant pyrotechnic systems are reported in this and three immediately following papers. The overall aim of the study was to investigate the role of different oxidants in binary combination with silicon as the common fuel.Temperature profiles of the burning pyrotechnic compositions have been recorded. simultaneously with measurements

R. Anil Rugunanan; Michael E. Brown

1993-01-01

47

Atomistic modeling and molecular dynamic simulation of binary metallic glasses  

NASA Astrophysics Data System (ADS)

Bulk metallic glasses (BMGs) have great potentials because of their unique outstanding mechanical and physical properties. However, the fundamental principles guiding the discovery of new BMGs have not been systematically developed. In this work, the glass forming ability (GFA) of binary metallic systems has been investigated by using molecular dynamic simulations. A series of interatomic potentials representing different atomic size ratios and chemical bonding of the constituent atoms were constructed to demonstrate the effects of the size ratio, concentration of the minority atoms and compositional short range order (CSRO) on the GFA. The phase diagrams of glass transition were built to represent the glass formation in the quenching process. We found that when the atomic size ratio should be limited in a range to form a binary metallic glasses. The addition of the solute atoms always improves the GFA of the modeling system. The size ratio factor, defined as the product of the size mismatch and the minimum concentration of the solute atoms, has been used to quantitatively describe the GFA. CSRO, introduced by applying the repulsive potential between small sized atoms, improves glass formability, and makes small atoms have slower dynamics and lower diffusivity than large atoms. Al-Ni binary system was studied with Finnis-Sinclair potential to describe atomic interactions. We investigated the transitions of Al80Ni20 systems at two cooling rates, and found that there exist octahedral local clusters in the amorphous AlNi alloys. The strong Al-Ni interaction and weak Ni-Ni interaction leads to preferred Al atoms neighborhood for Ni atoms. This type of the chemical bonding is similar to the CSRO introduced in the modeling system. The studies of the relaxation time reveal that the small sized Ni atoms actually have slower dynamics than Al atoms. It is in agreement with that of the modeling system and suggests that the size mismatch and CSRO play key roles in determining the GFA of BMG materials.

Chen, Hao

48

Energy Band Gap Behavior as a Function of Optical Electronegativity for Semiconducting and Insulating Binary Oxides  

NASA Astrophysics Data System (ADS)

A relationship between energy band gap and electronegativity has long been understood to exist. However, defining the relationship between the two for binary oxide systems has proven difficult. Many scientists tried to model the band gap as a function of Pauling electronegativity values, but we show that by using a new concept called ``optical electronegativity'' one can obtain much better predictions regarding band gaps of new oxide. Interestingly we found that the behavior of oxides varies across depending on the chemical group the cation is from. With that knowledge, we developed two equations to describe the alkali earth metal and poor metal oxide. By using our models, we are able to predict the band gap of radium oxide at 5.36 eV. Due to the contributions of `d' and `f' orbitals we could not model lanthanide rare earth and transition metal oxides but rather we found that band gaps for both lay beween 3.56 - 5.72 eV, and 1.82 -- 3.82 eV, respectively.

Dagenais, Kristen; Chamberlin, Matthew; Constantin, Costel

2011-10-01

49

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

2013-01-30

50

Metal Clusters and Extended Metal-Metal Bonding in Metal Oxide Systems.  

National Technical Information Service (NTIS)

The results of recent investigations of the synthesis and structures of ternary and quaternary molybdenum oxide compounds having metal-metal bonded cluster units or infinite chains are presented. In all cases the average oxidation state of molybdenum is l...

R. E. McCarley

1982-01-01

51

The catalytic methanol synthesis over nanoparticle metal oxide catalysts  

Microsoft Academic Search

Several nanoparticle metal oxides were prepared and studied for the catalytic production of methanol from hydrogen and carbon dioxide. These catalysts include: ZnO, CuO, NiO, and a binary system CuO\\/ZnO. The catalysts were prepared through sol–gel synthesis and were found, via TEM and BET, to have high surface areas and small crystallite sizes. With this in mind, the catalytic production

Corrie L. Carnes; Kenneth J. Klabunde

2003-01-01

52

Molecular Level Coating of Metal Oxide Particles  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

53

Molecular Level Coating for Metal Oxide Particles  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

54

Compression Behaviour of Bulk Metallic Glasses and Binary Amorphous Alloy  

NASA Astrophysics Data System (ADS)

The compression properties of Zr41Ti14Cu12.5Ni10Be22.5, Zr44.4Nb7Cu13.5Ni10.8Be24.3 bulk metallic glasses and Ni77P23 binary amorphous alloy are investigated at room temperature up to 24 GPa, 39 GPa and 30.5 GPa, respectively, using in-situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. The pressure-volume relationship of Ni77P23 amorphous alloy is consistent well with the second order Birch-Murnaghan (B-M) equation within the experimental pressure range. However, under higher pressure, the experimental data of Zr-based specimens deviate from the B-M equation. Compare to the binary amorphous alloy, less excess free volume existing in the bulk metallic glass and multi-component atomic configuration results in a two-stage relationship between compressibility and pressure.

Li, Gong; Liu, Jing; Liu, Ri-Ping

2007-08-01

55

Oxide film on metal substrate reduced to form metal-oxide-metal layer structure  

NASA Technical Reports Server (NTRS)

Electrically conductive layer of zirconium on a zirconium-oxide film residing on a zirconium substrate is formed by reducing the oxide in a sodium-calcium solution. The reduced metal remains on the oxide surface as an adherent layer and seems to form a barrier that inhibits further reaction.

Youngdahl, C. A.

1967-01-01

56

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

57

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

58

Preparing oxidizer coated metal fuel particles  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

59

Nanostructured transition metal oxides useful for water oxidation catalysis  

DOEpatents

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

Frei, Heinz M; Jiao, Feng

2013-12-24

60

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

61

Ammonia release method for depositing metal oxides  

DOEpatents

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

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

1994-12-13

62

Method for producing metal oxide nanoparticles  

DOEpatents

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

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

2008-04-15

63

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

64

Evolution of Nitrogen Impurities in Metal-Silicon Binary Couples and Their Effect on Silicide Formation  

NASA Astrophysics Data System (ADS)

The possible ways in which nitrogen may be present in and interact with metal silicides are outlined. It is shown that, although contaminant nitrogen can be easily eliminated in deposition systems and processing ambients, understanding the role of nitrogen in metals and metal silicides may be important for various nitridation processes used for VLSI fabrication. Nitrogen isotope ('15)N is controllably introduced into either the metal or silicon in a metal-silicon binary couple. Silicide formation is induced by vacuum annealing. After various thermal treatments, ('15)N is profiled by the ('15)N(p,(alpha))('12)C nuclear reaction. A detailed description of this technique is given. The metals investigated are Pd, Ni, Co, Pt, Ta, Mo and Ti. Metal silicides are grouped into three categories according to the moving species during silicide formation: metal, silicon or both. The interpretation of nitrogen evolution during silicide formation is based on the identity of the moving species. A wide variety of nitrogen redistribution patterns (segregation, incorporation, accumulation, dilution and fast diffusion) are observed in different samples, depending on parameters such as nitrogen diffusivity and solubility in its host matrix, and nitrogen bond strength to the silicide forming species. The presence of nitrogen sometimes will slow down the silicide growth rate. The degree of slowing down generally depends on the amount of nitrogen incorporated. In case of refractory metal, a large concentration up to 25 at% of oxygen is found to be incorporated during metal film deposition. The redistribution of oxygen during annealing is investigated using the ('16)O(d,(alpha))('14)N nuclear reaction. Two additional studies on different subjects are reported. The first one investigates the dry and wet oxidation behavior of Ti and Hf nitrides. A parabolic oxidation is found in all cases except the wet oxidation of NfN. The other study extends the work on dopant enhanced epitaxial regrowth of Si to three substrate orientations. It is found that the enhancement factor is the same, independent of the substrate orientation. An improved crystalline quality is observed for epitaxial Si regrown on an <111> substrate.

Ho, Kuo Ting

65

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

66

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

National Technical Information Service (NTIS)

Niobia/Alumina (Nb2O5/Al2O3) mixed oxides and SiO2- supported Nb2O5/Al2O3 binary oxides were prepared over a wide composition range. The mixed oxides were prepared by coprecipitation and the supported oxides were synthesized by incipient wetness impregnat...

S. M. Maurer

1988-01-01

67

Reduction of Metal Oxide to Metal using Ionic Liquids  

SciTech Connect

A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode. Successful extraction of metal from metal oxide dissolved in Urea/ChCl (2:1) was accomplished. The current efficiencies were relatively high in both the metal deposition processes with current efficiency greater than 86% for lead and 95% for zinc. This technology will advance the metal oxide reduction process by increasing the process efficiency and also eliminate the production of CO2 which makes this an environmentally benign technology for metal extraction.

Dr. Ramana Reddy

2012-04-12

68

X-ray luminous binaries, metallicity, and the early Universe  

NASA Astrophysics Data System (ADS)

High-mass X-ray binaries (HMXBs) may have had a significant impact on the heating of the intergalactic medium in the early Universe. Study of HMXBs in nearby, low-metallicity galaxies that are local analogues to early galaxies can help us understand early HMXBs. The total luminosity of HMXB populations is dominated by sources at high luminosities. These sources exhibit X-ray spectra that show curvature above 2 keV and the same is likely true of HMXB populations at high redshifts. The spectral curvature changes the K-correction for X-rays from HMXBs in a manner that weakens the constraints on X-ray emission of early HMXBs obtained from the soft X-ray background. Applied to deep X-ray surveys of star-forming galaxies, the modified K-correction suggests a moderate increase in the ratio of X-ray luminosity to star formation rate at intermediate redshifts, z = 3-5, and is consistent with a large enhancement at high redshifts, z = 6-7. L106

Kaaret, Philip

2014-05-01

69

High temperature, oxidation resistant noble metal-Al alloy thermocouple  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

70

Method of producing adherent metal oxide coatings on metallic surfaces  

DOEpatents

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

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

2001-01-01

71

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

NASA Astrophysics Data System (ADS)

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

Grover, Valerie Ann

72

Biomarker sensing using nanostructured metal oxide sensors  

Microsoft Academic Search

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

Krithika Kalyanasundaram

2007-01-01

73

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

74

Transparent metal oxide electrode CID imager  

Microsoft Academic Search

The use of metal oxide transparent conductive electrodes in a charge-injection device (CID) imaging array has resulted in a quantum efficiency of approximately 70 percent, uniform throughout the visible, with useful array response out to 3500 Å. The advantages of using highly transparent metal oxide electrodes for the fabrication of frontside illuminated arrays is described. A new high density CID

DALE M. BROWN; MARIO GHEZZO; MARVIN GARFINKEL

1976-01-01

75

Correlation between the oxidation state of {alpha}-SiC and its wettability with non-reactive (Sn) or reactive (Ni) metallic components and their binary Si-alloys  

SciTech Connect

Wetting experiments were performed on {alpha}-SiC/Sn (505 K < T < 1873 K) and {alpha}-SiC/Ni (T = 1,773 K) in an argon atmosphere with 700 vpm moisture. Wettability and reactivity of {alpha}-SiC with both metallic components were affected by the oxidation state of {alpha}-SiC. Under the experimental conditions, passive to active transition of {alpha}-SiC occurs at {approximately}1,600 K. Up to 1,600 K, wettability between liquid Sn and {alpha}-SiC is governed by a passive SiO{sub 2}-film overlaying {alpha}-SiC, while at higher temperatures an increased carbon surface concentration, leads to higher contact angle values. Under the present experimental conditions the start of reactivity between Ni and {alpha}-SiC coincides with the passive to active transition of {alpha}-SiC. The presence of silicon at the ceramic-metal interface, in the form of alloying element into both Sn or Ni, was found to decrease the temperature of passive to active transition of {alpha}-SiC, to improve the wettability for both {alpha}-SiC/Sn and {alpha}-SiC/Ni, and to suppress the interfacial reaction between Ni and {alpha}-SiC.

Tsoga, A.; Ladas, S.; Nikolopoulos, P. [Univ. of Patras (Greece). Dept. of Chemical Engineering] [Univ. of Patras (Greece). Dept. of Chemical Engineering; [Inst. of Chemical Engineering and High Temperature Chemical Processes, Patras (Greece)

1997-09-01

76

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

2008-08-12

77

A metal-oxide-semiconductor varactor  

Microsoft Academic Search

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

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

1999-01-01

78

Direct electrochemical reduction of metal-oxides  

DOEpatents

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

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

2003-01-01

79

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

PubMed

Manganese oxides typically exist as mixtures with other metal oxides in soil-water environments; however, information is only available on their redox activity as single oxides. To bridge this gap, we examined three binary oxide mixtures containing MnO(2) and a secondary metal oxide (Al(2)O(3), SiO(2) or TiO(2)). The goal was to understand how these secondary oxides affect the oxidative reactivity of MnO(2). SEM images suggest significant heteroaggregation between Al(2)O(3) and MnO(2) and to a lesser extent between SiO(2)/TiO(2) and MnO(2). Using triclosan and chlorophene as probe compounds, pseudofirst-order kinetic results showed that Al(2)O(3) had the strongest inhibitory effect on MnO(2) reactivity, followed by SiO(2) and then TiO(2). Al(3+) ion or soluble SiO(2) had comparable inhibitory effects as Al(2)O(3) or SiO(2), indicating the dominant inhibitory mechanism was surface complexation/precipitation of Al/Si species on MnO(2) surfaces. TiO(2) inhibited MnO(2) reactivity only when a limited amount of triclosan was present. Due to strong adsorption and slow desorption of triclosan by TiO(2), precursor-complex formation between triclosan and MnO(2) was much slower and likely became the new rate-limiting step (as opposed to electron transfer in all other cases). These mechanisms can also explain the observed adsorption behavior of triclosan by the binary oxide mixtures and single oxides. PMID:22309023

Taujale, Saru; Zhang, Huichun

2012-03-01

80

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

PubMed

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

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

2012-12-28

81

Adsorption behavior and mechanism of arsenate at Fe–Mn binary oxide\\/water interface  

Microsoft Academic Search

Preliminary study revealed that a prepared Fe–Mn binary oxide adsorbent with a Fe:Mn molar ratio of 3:1 was more effective for As(V) removal than pure amorphous FeOOH, which was unanticipated. In this paper, the As(V) adsorption capacities of Fe–Mn binary oxide and amorphous FeOOH were compared in detail. Furthermore, the adsorption behaviors as well as adsorption mechanism of As(V) at

Gaosheng Zhang; Huijuan Liu; Ruiping Liu; Jiuhui Qu

2009-01-01

82

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

83

Accuracy of density functional theory in predicting formation energies of ternary oxides from binary oxides and its implication on phase stability  

NASA Astrophysics Data System (ADS)

The evaluation of reaction energies between solids using density functional theory (DFT) is of practical importance in many technological fields and paramount in the study of the phase stability of known and predicted compounds. In this work, we present a comparison between reaction energies provided by experiments and computed by DFT in the generalized gradient approximation (GGA), using a Hubbard U parameter for some transition metal elements (GGA+U). We use a data set of 135 reactions involving the formation of ternary oxides from binary oxides in a broad range of chemistries and crystal structures. We find that the computational errors can be modeled by a normal distribution with a mean close to zero and a standard deviation of 24 meV/atom. The significantly smaller error compared to the more commonly reported errors in the formation energies from the elements is related to the larger cancellation of errors in energies when reactions involve chemically similar compounds. This result is of importance for phase diagram computations for which the relevant reaction energies are often not from the elements but from chemically close phases (e.g., ternary oxides versus binary oxides). In addition, we discuss the distribution of computational errors among chemistries and show that the use of a Hubbard U parameter is critical to the accuracy of reaction energies involving transition metals even when no major change in formal oxidation state is occurring.

Hautier, Geoffroy; Ong, Shyue Ping; Jain, Anubhav; Moore, Charles J.; Ceder, Gerbrand

2012-04-01

84

Lithium and metal abundances in long period AM binaries  

Microsoft Academic Search

High signal-to-noise CCD spectra of three bright, long period Am binaries (HD108651, HD116657 and HD138213) have been obtained and the atmospheric abundances of identified chemical elements were studied. We found HD116657 to be a new candidate as a Li deficient, long period Am binary, in addition to 16 Ori. While HD108651 and HD116657 have pronounced Am characteristics, HD138213 is just

I. Kh. Iliev; J. Budaj; J. Zverko; I. S. Barzova; J. Ziznovsky

1998-01-01

85

Catalytic production of metal carbonyls from metal oxides  

DOEpatents

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

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

1984-01-06

86

Switching Mode and Mechanism in Binary Oxide Resistive Random Access Memory Using Ni Electrode  

NASA Astrophysics Data System (ADS)

Resistive-switching (RS) modes in different CMOS-compatible binary oxides have been shown to be governed by the interplay with the Ni top electrode. Unipolar RS and metallic low-resistance state in polycrystalline HfO2 and ZrO2 are distinct from the preferential bipolar RS and semiconductive low-resistance state in amorphous Al2O3 and SiO2. Backside secondary ion mass spectrometry (SIMS) has shown the formation of Ni filaments in HfO2, in contrast to the formation of oxygen-vacancy filaments in Al2O3. The differences have been explained by strong dependence of Ni migration on the oxide crystallinity. Additionally, the RS mode can be further tailored using bilayer structures. The oxide layer next to the Si bottom electrode and its tendency of forming Ni filaments play significant roles in unipolar RS in the bilayer structures, in support of the conical-shape Ni filament model where the connecting and rupture of filaments for unipolar RS occur at the smallest diameter near the bottom electrodes.

Lin, Kuan-Liang; Hou, Tuo-Hung; Lee, Yao-Jen; Chang, Jhe-Wei; Lin, Jun-Hung; Shieh, Jiann; Chou, Cheng-Tung; Lei, Tan-Fu; Chang, Wen-Hsiung; Jang, Wen-Yueh; Lin, Chen-Hsi

2013-03-01

87

Cyclic catalytic upgrading of chemical species using metal oxide materials  

DOEpatents

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

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

2013-05-07

88

Half-metallic transition metal oxides  

Microsoft Academic Search

We present an application of the self-interaction corrected local spin density approximation to study the electronic structure of half-metallic double perovskites Ba2FeMoO6, Ca2FeMoO6, Sr2FeMoO6, Ca2FeReO6, and charge order in Fe3O4.

Z. Szotek; W. M. Temmerman; A. Svane; L. Petit; G. M. Stocks; H. Winter

2004-01-01

89

Development of techniques for processing metal-metal oxide systems  

NASA Technical Reports Server (NTRS)

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

Johnson, P. C.

1976-01-01

90

Metallic Precipitates Production in Refractory Oxides.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A method based upon high-temperature reduction or subtractive colorations has been developed to produce precipitates or colloids of metals in high-temperature oxides...

1982-01-01

91

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) [Naperville, IL; Kim, Jeom-Soo (Naperville, IL) [Naperville, IL; Johnson, Christopher S. (Naperville, IL) [Naperville, IL

2008-01-01

92

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

93

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

94

A threshold for onset of natural convection in binary metallic alloys  

Microsoft Academic Search

Experiments were performed with a new radioscopic flow visualization technique on natural convection during melting of a\\u000a binary metallic Ga-In alloy. This technique provides visualization of the density fields within opaque low Prandtl number\\u000a fluids and their solids. Upon applying a horizontal temperature gradient to a gallium melt alloyed with 5 weight percent indium,\\u000a the binary melt developed a vertical

J. N. Koster; R. Derebail

1997-01-01

95

A Combined Astrometric and Spectroscopic Study of Metal-Poor Binaries  

NASA Astrophysics Data System (ADS)

In this work we present a study of binary systems in a metal-poor sample of solar type stars. The stars analyzed were rejected from two planet search samples because they were found to be binaries. Using available radial velocity and Hipparcos astrometric data, we apply different methods to find, for every binary system, a possible range of solutions for the mass of the companion and its orbital period. In one case we find that the solution depends on the Hipparcos data used: the old and new reductions give different results. Some candidate low-mass companions are found, including some close to the brown dwarf regime.

Benamati, L.; Sozzetti, A.; Santos, N. C.; Latham, D. W.

2013-11-01

96

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

97

Semiconductor properties of passive oxide layers on binary tin + indium alloys  

Microsoft Academic Search

The electrochemical behaviour and solid state properties of passive oxide layers formed on binary tin + indium alloys in alkaline aqueous solution were studied by using photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). Results obtained from PCS and EIS measurements showed that the anodically formed tin oxides behaved as heavily doped, n-type amorphous semiconductors. From the photocurrent spectra the

C. A. Moina; F. E. Varela; L. Feria Hernández; G. O. Ybarra; J. R. Vilche

1997-01-01

98

Oxidative stretching of metal-metal bonds to their limits.  

PubMed

Oxidation of quadruply bonded Cr2(dpa)4, Mo2(dpa)4, MoW(dpa)4, and W2(dpa)4 (dpa = 2,2'-dipyridylamido) with 2 equiv of silver(I) triflate or ferrocenium triflate results in the formation of the two-electron-oxidized products [Cr2(dpa)4](2+) (1), [Mo2(dpa)4](2+) (2), [MoW(dpa)4](2+) (3), and [W2(dpa)4](2+) (4). Additional two-electron oxidation and oxygen atom transfer by m-chloroperoxybenzoic acid results in the formation of the corresponding metal-oxo compounds [Mo2O(dpa)4](2+) (5), [WMoO(dpa)4](2+) (6), and [W2O(dpa)4](2+) (7), which feature an unusual linear M···M?O structure. Crystallographic studies of the two-electron-oxidized products 2, 3, and 4, which have the appropriate number of orbitals and electrons to form metal-metal triple bonds, show bond distances much longer (by >0.5 Å) than those in established triply bonded compounds, but these compounds are nonetheless diamagnetic. In contrast, the Cr-Cr bond is completely severed in 1, and the resulting two isolated Cr(3+) magnetic centers couple antiferromagnetically with J/kB= -108(3) K [-75(2) cm(-1)], as determined by modeling of the temperature dependence of the magnetic susceptibility. Density functional theory (DFT) and multiconfigurational methods (CASSCF/CASPT2) provide support for "stretched" and weak metal-metal triple bonds in 2, 3, and 4. The metal-metal distances in the metal-oxo compounds 5, 6, and 7 are elongated beyond the single-bond covalent radii of the metal atoms. DFT and CASSCF/CASPT2 calculations suggest that the metal atoms have minimal interaction; the electronic structure of these complexes is used to rationalize their multielectron redox reactivity. PMID:24746142

Brogden, David W; Turov, Yevgeniya; Nippe, Michael; Li Manni, Giovanni; Hillard, Elizabeth A; Clérac, Rodolphe; Gagliardi, Laura; Berry, John F

2014-05-01

99

Metals, Toxicity and Oxidative Stress  

Microsoft Academic Search

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

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

2005-01-01

100

Experimental determination of systems suitable for study as monotectic binary metallic alloy solidification models  

NASA Technical Reports Server (NTRS)

Transparent binary metallic alloy solidification models are important in attempts to understand the processes causing liquid-liquid and solid-liquid phase transformations in metallic alloy systems. These models permit visual observation of the phase transformation and the processes proceding solidification. The number of these transparent monotectic binary models needs to be expanded to distinguish between the unique and general phenomena observed. The expansion of the number of accurately determined monotectic phase diagrams of model systems, and contribution to a data base for eventual use with UNIFAC group contribution methods is examined.

Smith, J. E., Jr.

1985-01-01

101

PLUTONIUM METAL: OXIDATION CONSIDERATIONS AND APPROACH  

SciTech Connect

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

Estochen, E.

2013-03-20

102

High dielectric constant gate oxides for metal oxide Si transistors  

NASA Astrophysics Data System (ADS)

The scaling of complementary metal oxide semiconductor transistors has led to the silicon dioxide layer, used as a gate dielectric, being so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (?) or 'high K' gate oxides such as hafnium oxide and hafnium silicate. These oxides had not been extensively studied like SiO2, and they were found to have inferior properties compared with SiO2, such as a tendency to crystallize and a high density of electronic defects. Intensive research was needed to develop these oxides as high quality electronic materials. This review covers both scientific and technological issues—the choice of oxides, their deposition, their structural and metallurgical behaviour, atomic diffusion, interface structure and reactions, their electronic structure, bonding, band offsets, electronic defects, charge trapping and conduction mechanisms, mobility degradation and flat band voltage shifts. The oxygen vacancy is the dominant electron trap. It is turning out that the oxides must be implemented in conjunction with metal gate electrodes, the development of which is further behind. Issues about work function control in metal gate electrodes are discussed.

Robertson, John

2006-02-01

103

Three-coordinate metal centers in extended transition metal oxides.  

PubMed

The n = 3 Ruddlesden-Popper phase Sr3LaFe1.5Co1.5O10+/-delta is capable of sustaining O contents as low as O7.5 with a mean metal oxidation state of +2 and three coordination at the central site in the trilayer of originally octahedral transition metal sites. The shortening of the axial bonds to the flanking octahedral layers stabilizes the low oxidation state and consequent unusual low coordination number of the Fe2+ and Co2+ cations within the extended structure. PMID:17002328

Bowman, Amy; Allix, Mathieu; Pelloquin, Denis; Rosseinsky, Matthew J

2006-10-01

104

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part III: Ternary Systems  

Microsoft Academic Search

Abstract–studies of tbe combustion of several binary silicon\\/oxidant pyrotechnic systems (Si\\/Fe2o3, Si\\/SnO2, Si\\/Sb2O3 and Si\\/KNO3) have been extended to examine the behaviour of ternary systems with silicon as fuel and binary combinations of the above oxidants. The effects of substituting ferrosilicon, FeSi7, or calcium silicide, CaSi2, for some or all of the Si in the above systems have also been

R. Anil Rugunanan; Michael E. Brown

1993-01-01

105

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

106

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

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

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

2001-01-01

107

Metal sulfide initiators for metal oxide sorbent regeneration  

DOEpatents

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

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

1999-01-01

108

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

109

Metal oxide composite cathode material for high energy density batteries  

SciTech Connect

An electrochemical cell is described incorporating cathode materials comprising at least one metal oxide, at least one metal, or mixture of metals or metal oxides incorporated in the matrix of a host metal oxide. The cathode materials of this invention are constructed by the chemical addition, reaction, or otherwise intimate contact of various metal oxides and/or metal elements during thermal treatment in mixed states. The materials thereby produced contain metals and oxides of the groups ib, iib, iiib, ivb, vb, vib, viib, and viii, which includes the noble metals and/or their oxide compounds. The incorporation of the metal oxides, metals or mixtures thereof substantially increases the discharge capacity and the overall performance of the cathode materials.

Bolster, M.; Liang, C.C.; Murphy, R.M.

1982-01-12

110

Organically modified metal oxides for polymer grafting  

US Patent & Trademark Office Database

A composition of matter or modifier for use in modifying unfunctionalized polymers comprising a metal oxide substrate that can be formed into a sol, a water soluable, acid moiety, having a hydrocarbyl group with olefinic unsaturation, bound to the metal oxide substrate and a water soluble, free radical initiator, the composition of matter generally being in the form of a dry powder that can be mixed with a polymer lacking functional groups whereupon when the mixture is subjected to conditions which result in the decomposition of the free radical initiator to form free radicals.

2005-03-01

111

Magnesium oxide for improved heavy metals removal  

Microsoft Academic Search

To improve technology for treating process water, US Bureau of Mines research has shown that magnesium oxide (MgO) has many advantages over lime or caustic soda for precipitating heavy metals. Sludge produced by MgO occupies only 0.2-0.3 times as much volume as the precipitate made using a soluble base. While a settled, lime-formed precipitate is easily resuspended, the MgO-metal hydroxide

J. E. Schiller; S. E. Khalafalla

1984-01-01

112

Biomimetic surfaces of semiconducting metal oxides  

NASA Astrophysics Data System (ADS)

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

Orita, Kosuke; Karthaus, Olaf

2014-03-01

113

Tailoring Surface Reactivity of Metal Oxides  

NASA Astrophysics Data System (ADS)

Titanium oxide is receiving continued attention because of its importance as catalyst support, as a material to harvest solar energy for chemical transformations, and as a model metal oxide. In this talk, I will focus on the structure and defects (extrinsic and intrinsic) of less-studied TiO2 surfaces; i.e., rutile (011)-2x1 and anatase (101), and their influence on surface reactivity.

Diebold, Ulrike

2008-03-01

114

Complex oxide-noble metal conjugated nanoparticles.  

PubMed

Hybrid nanoparticles (NPs) composed of multiple components offer new opportunities for next-generation materials. In this study, a paradigm for the noble metal/ternary complex oxide hybrid NPs is reported by adopting pulsed laser ablation in liquids. As model hybrids, gold-spinel heterodimer (Au-CoFe2O4) and gold-pervoskite heterodimer (Au-SrTiO3) NPs are investigated. This work has demonstrated the diverse playgroup of NP conjugation enlarged by complex oxides. PMID:23427105

Guo, Jun-Ling; Chiou, Yao-De; Liang, Wen-I; Liu, Heng-Jui; Chen, Ying-Jiun; Kuo, Wei-Cheng; Tsai, Chih-Ya; Tsai, Kai-An; Kuo, Ho-Hung; Hsieh, Wen-Feng; Juang, Jenh-Yih; Hsu, Yung-Jung; Lin, Hong-Ji; Chen, Chien-Te; Liao, Xue-Pin; Shi, Bi; Chu, Ying-Hao

2013-04-11

115

Half-metallic oxide point contacts  

Microsoft Academic Search

A classification of half-metals is illustrated with examples of ferromagnetic and ferrimagnetic oxides. I : V characteristics and magnetoresistance of contacts between oxides with localized electrons (Fe3O4) and delocalized electrons ((La0.7Sr0.3)MnO3) are discussed. The magnetoresistance is large when the conductance of the contact is less than the quantum of conductance G0 = 2e2\\/h. Broad distributions of point contacts are investigated

J. M. D. Coey; J. J. Versluijs; M. Venkatesan

2002-01-01

116

Reduction of metal oxides through mechanochemical processing  

DOEpatents

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

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

2000-01-01

117

Metal supported solid oxide fuel cell  

US Patent & Trademark Office Database

A reversible solid oxide fuel cell obtainable by a method comprising the steps of: providing a metallic support layer; forming a cathode precursor layer on the metallic support layer; forming an electrolyte layer on the cathode precursor layer; sintering the obtained multilayer structure; in any order conducting the steps of: forming a cathode layer by impregnating the cathode precursor layer, and forming an anode layer on the electrolyte layer; characterised in that the method further comprises prior to forming said cathode layer, impregnating a precursor solution or suspension of a barrier material into the metallic support layer and the cathode precursor layer and subsequently conducting a heat treatment.

2012-10-30

118

Rapid Synthesis of Nanocrystalline TiO 2\\/SnO 2 Binary Oxides and Their Photoinduced Decomposition of Methyl Orange  

Microsoft Academic Search

A rapid and simple method, the so-called stearic acid method (SAM) was developed to prepare nanostructured TiO2\\/SnO2 binary oxides by combustion of stearic acid precursors. The preparative process was studied by Fourier transform infrared spectroscopy (FT-IR). During the preparative process, metal precursors were dispersed in stearic acid at molecular level. Microstructure of the samples was investigated by X-ray diffraction (XRD),

Juan Yang; Dan Li; Xin Wang; Xujie Yang; Lude Lu

2002-01-01

119

CuO–CeO 2 binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation  

Microsoft Academic Search

This work reports the first synthesis of CuO–CeO2 binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO–CeO2 nanoplates calcined at 400°C were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were

Chaoquan Hu; Qingshan Zhu; Lin Chen; Rongfang Wu

2009-01-01

120

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

121

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

122

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

123

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

Microsoft Academic Search

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

Kaushik Gupta; Shyamal Saha; Uday Chand Ghosh

2008-01-01

124

Structural, electronic and magnetic properties of binary transition metal aluminum clusters: absence of electronic shell structure  

NASA Astrophysics Data System (ADS)

Single Cr, Mn, Fe, Co and Ni doped Al clusters having up to 12 Al atoms are studied using density functional methods. The global minima of structure for all the clusters are identified, and their relative stability and electronic and magnetic properties are studied. FeAl4 and CoAl3 are found to have enhanced stability and aromatic behavior. In contrast to binary transition metal alkali and transition metal alkaline earth clusters, spherical shell models cannot describe the electronic structure of transition metal aluminum clusters.

Chauhan, Vikas; Singh, Akansha; Majumder, Chiranjib; Sen, Prasenjit

2014-01-01

125

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

126

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

127

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

128

Apparatus enables accurate determination of alkali oxides in alkali metals  

NASA Technical Reports Server (NTRS)

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

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

1966-01-01

129

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

PubMed

Controlling superstructure of binary nanoparticle mixtures in three dimensions from self-assembly opens enormous opportunities for the design of materials with unique properties. Here we report on how the intimate coupling of synthesis, in-depth electron tomographic characterization and theory enables exquisite control of superstructure in highly ordered porous three-dimensional continuous networks from single and binary mixtures of metal nanoparticles with a triblock terpolymer. Poly(isoprene-block-styrene-block-(N,N-dimethylamino)ethyl methacrylate) is synthesized and used as structure-directing agent for ligand-stabilized platinum and gold nanoparticles. Quantitative analysis provides insights into short- and long-range nanoparticle-nanoparticle correlations, and local and global contributions to structural chirality in the networks. Results provide synthesis criteria for next-generation mesoporous network superstructures from binary nanoparticle mixtures for potential applications in areas including catalysis. PMID:24557327

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

2014-01-01

130

High temperature strength of YSZ joints brazed with palladium silver copper oxide filler metals  

Microsoft Academic Search

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

Jens T. Darsell; K. Scott Weil

2011-01-01

131

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

SciTech Connect

A facile one-pot procedure, or so-called 'direct synthesis,' was used to prepare the novel heterometallic complexes [M{sub 2}Mn(OAc){sub 6}(bpy){sub 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 N{sub 2} 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. -- Graphical abstract: The novel heterometallic complexes [M{sub 2}Mn(OAc){sub 6}(bpy){sub 2}] (M=Cu, Co, Zn, bpy=2,2'-bipyridyl) were isolated and used as precursors for low-temperature synthesis of binary oxides. Single crystal X-ray diffraction, FTIR, TG/DTA/DTG, TPD-MS, PXRD, SEM/EDX analysis was performed on complexes and powders. Display Omitted

Makhankova, Valeriya G., E-mail: leram@univ.kiev.u [Department of Inorganic Chemistry, Kyiv National Taras Shevchenko University, Volodymyrska street 64, Kyiv 01601 (Ukraine); Khavryuchenko, Oleksiy V.; Lisnyak, Vladyslav V.; Kokozay, Vladimir N. [Department of Inorganic Chemistry, Kyiv National Taras Shevchenko University, Volodymyrska street 64, Kyiv 01601 (Ukraine); Dyakonenko, Viktoriya V. [STC 'Institute for Single Crystals' National Academy of Sciences of Ukraine, 60 Lenina Avenue Kharkiv 61001 (Ukraine); Shishkin, Oleg V. [STC 'Institute for Single Crystals' National Academy of Sciences of Ukraine, 60 Lenina Avenue Kharkiv 61001 (Ukraine); Department of Inorganic Chemistry, V.N. Karazin Kharkiv National University, 4 Svobody sq., Kharkiv 61077 (Ukraine); Skelton, Brian W. [Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 6009 (Australia); Jezierska, Julia [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw (Poland)

2010-11-15

132

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

PubMed

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

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

2014-07-01

133

Dynamics of stellar black holes in young star clusters with different metallicities - II. Black hole-black hole binaries  

NASA Astrophysics Data System (ADS)

In this paper, we study the formation and dynamical evolution of black hole-black hole (BH-BH) binaries in young star clusters (YSCs), by means of N-body simulations. The simulations include metallicity-dependent recipes for stellar evolution and stellar winds, and have been run for three different metallicities (Z = 0.01, 0.1 and 1 Z?). Following recent theoretical models of wind mass-loss and core-collapse supernovae, we assume that the mass of the stellar remnants depends on the metallicity of the progenitor stars. We find that BH-BH binaries form efficiently because of dynamical exchanges: in our simulations, we find about 10 times more BH-BH binaries than double neutron star binaries. The simulated BH-BH binaries form earlier in metal-poor YSCs, which host more massive black holes (BHs) than in metal-rich YSCs. The simulated BH-BH binaries have very large chirp masses (up to 80 M?), because the BH mass is assumed to depend on metallicity, and because BHs can grow in mass due to the merger with stars. The simulated BH-BH binaries span a wide range of orbital periods (10-3-107 yr), and only a small fraction of them (0.3 per cent) is expected to merge within a Hubble time. We discuss the estimated merger rate from our simulations and the implications for Advanced VIRGO and LIGO.

Ziosi, Brunetto Marco; Mapelli, Michela; Branchesi, Marica; Tormen, Giuseppe

2014-07-01

134

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

135

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

136

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

137

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

138

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

139

Reactor vessel 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.

Anderson, Marc A. (Madison, WI); Zeltner, Walter A. (Oregon, WI)

1992-08-11

140

Involvement of incipient metal oxidation products in organic oxidation reactions at noble metal anodes  

SciTech Connect

The object of the present work is to demonstrate that in many organic electro-oxidation reactions at noble metal anodes in aqueous media, interfacial cyclic redox behavior involving incipient metal oxidation products (as intermediates) may be more important that the widely accepted adsorption-based view of this type of reaction. The activated chemisorption model is still accepted as being valid for many reactions involving hydrogen gas, e.g., hydrogen evolution or ionization, and catalytic hydrogenation reactions of unsaturated organic materials at platinized platinum electrodes. The alternative view is outlined here for gold followed by a brief discussion of some other noble metals.

Burke, L.D.; Cunnane, V.J.

1986-08-01

141

Formation of porous metal oxides in the anodization process  

Microsoft Academic Search

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

C. Sample; A. A. Golovin

2006-01-01

142

Cation-network interactions in binary alkali metal borate glasses. A far-infrared study  

Microsoft Academic Search

The far-infrared spectra of compositions probing the glass-forming regions of all five binary alkali metal borate systems chi MâO x (1 - chi)BâOâ (0 < chi less than or equal to 0.40, M = Na; and 0 < chi less than or equal to 0.35, M = K, Rb, Cs) have been measured and analyzed to systematically study the alkali

E. I. Kamitsos; M. A. Karakassides; G. D. Chryssikos

1987-01-01

143

Sinogram preprocessing and binary reconstruction for determination of the shape and location of metal objects in computed tomography (CT)  

PubMed Central

Purpose: To develop a binary image reconstruction method for the autolocalization of metallic object(s) in CT with sparse projections. Methods: The authors divide the system into two types of contents: Metal(s) and nonmetal(s). The boundaries of metallic objects are obtained by using a penalized weighted least-squares algorithm with the adequate intensity gradient-controlled. A novel mechanism of “amplifying” the difference between metal(s) and nonmetallic substances is introduced by preprocessing the sinogram data, which is shown to be necessary in dealing with a case with sparse projection data. A series of experimental studies are performed to evaluate the proposed approach. Results: A novel binary CT image reconstruction formalism is established for the autodetermination of the shape and location of metallic objects in the presence of limited number of projections. Experimental studies reveal that the presented algorithm works well even when the embedded metal object(s) has different shape(s). It is also shown that when the projection data are sparse, a differential manipulation of projection data can greatly facilitate the binary reconstruction process and allow the authors to obtain accurate binary CT images that would otherwise be unattainable. Conclusions: Binary CT reconstruction provides a viable method for determining the geometric distribution information of the implanted metal objects in CT imaging.

Meng, Bowen; Wang, Jing; Xing, Lei

2010-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

145

Electrically Erasable Metal–Oxide–Semiconductor Dosimeters  

Microsoft Academic Search

Metal-oxide-semiconductor (MOS) dosimetry including the reset of the sensor device for its reuse (reutilization) is described. The method consists in restoring the shifted threshold voltage after irradiation to a predefined value by the injection of a Fowler-Nordheim tunnel current. The amount of interface states per unit area is initially saturated in order to ensure repeatability. The method was tested on

José Lipovetzky; Eduardo Gabriel Redin; Adrián Faigón

2007-01-01

146

Metal oxide semiconductor NO 2 sensor  

Microsoft Academic Search

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

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

1995-01-01

147

Magnetotransport in half-metallic ferromagnetic oxides  

Microsoft Academic Search

Magnetotransport properties are described for thin films of two different ferromagnetic oxide material systems that are thought to be half-metallic , with possible applications in spintronics: the doped lanthanum manganites, La1-xA xMnO3 where A = (Ca,Sr), and CrO2. Magnetotransport properties dominated by extrinsic (microstructure-dependent) effects are described for the manganites. The degree of crystalline texture is correlated to large changes

Steven Michael Watts

2002-01-01

148

Hydrous metal oxide catalysts for oxidation of hydrocarbons  

SciTech Connect

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

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

1993-07-01

149

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

150

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

151

Removal of Metallic Iron on Oxide Slags  

NASA Astrophysics Data System (ADS)

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 ({p_{O2}} of approximately 10-4 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 °C and in 160 seconds at 1600 °C.

Shannon, George N.; Fruehan, R. J.; Sridhar, Seetharaman

2009-10-01

152

Catalytic oxidations using transition-metal carbonyls  

SciTech Connect

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 Re/sub 2/(CO)/sub 10/ photocatalyzed decomposition of hydrogen peroxide, the oxidative decarbonylation of an iridium carbonyl complex having a phosphine amine chelate ligand, the elucidation of mechanistic pathways and the detection of carbonylrhodium intermediates in the Rh/sub 6/(CO)/sub 16/ catalyzed-co-oxidation of CO and triphenylphosphine, and synthesis and chemistry of new d/sup 6/ and d/sup 8/ transition metal complexes having hydroxo or oxo ligands.

Roundhill, D.M.

1981-01-01

153

Effects of superbasic catalysts prepared by promoting MgO with bialkali metal compounds on the oxidative coupling of methane  

Microsoft Academic Search

The improvement in methane conversion, C[sub 2] selectivity, and stability with time-on-stream for the oxidative coupling of methane (OCM) has been studied by employing superbasic catalysts prepared by promoting MgO with various binary alkali metal compounds. The performance of the resulting catalysts is found to strongly depend on the nature of the alkali metal compounds forming the pair, the promoter

E. Ruckenstein; A. Z. Khan

1993-01-01

154

First Principles Studies of Metal-Oxide Surfaces  

Microsoft Academic Search

The interest in first principles investigations of metal-oxide surfaces has been growing rapidly over the past 10 years. Several phenomena of vital importance for fundamental understanding of heterogeneous catalysis have been investigated, including the metal\\/metal-oxide interface and the interaction with adsorbates. This contribution reviews different implementations of the density functional theory frequently used in studies of metal-oxide properties. Computational results

Henrik Grönbeck

2004-01-01

155

Analytical modeling of stress and strain of symmetrically oxidized metal  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

156

Combustion of Binary and Ternary Silicon\\/Oxidant Pyrotechnic Systems, Part IV: Kinetic Aspects  

Microsoft Academic Search

Abstract–Kinetic parameters for the processes occurring during controlled heating and during combustion of the binary silicon-fuelled pyrotechnic systems. Si\\/Fe2O3, Si\\/SnO2. Si\\/Sb203 and SilKN03 have been estimated,where possible, from the results of both thermal analysis and temperature profile measurements. The values obtained from the two very different techniques are compared and discussed, and the role of the oxidant, in a series

R. ANIL RUGUNANAN; MICHAEL E. BROWN

1993-01-01

157

Graphene oxide-based flexible metal-insulator-metal capacitors  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

158

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

159

Surface Chemistry of Nano-Structured Mixed Metal Oxide Films.  

National Technical Information Service (NTIS)

We have synthesizes and studied nano-structured porous mixed metal oxide thin films with high surface area and catalytic activity. By temporally controlling the deposition of two different metals in low-pressure oxygen we synthesized mixed metal oxide cat...

C. B. Mullins

2012-01-01

160

Prediction of binary transition-transition metal amorphous alloys by mechanical alloying  

NASA Astrophysics Data System (ADS)

The glass forming ability of binary TM-TM (TM = transition metal) alloys produced by mechanical alloying is studied with both two-dimensional maps of Miedema's coordinates and combinative coordinates. The former is constructed of Miedema's coordinates, the differences of electronegatives ?? and electron densities ?n ws{1}/{3}; the latte is constructed of the ratio ??/?n ws{1}/{3} and size factor ( R1 - R2)/ R2. In these maps, binary systems whic formed amorphous phase are clearly separated from the non-formed systems by a curve. The equations of the curves are y = 3.825 x, and y = 2.52 x-1/4 for the pure Miedema coordinates and combinative coordinates, respectively.

Hen, Zhang; Bangwei, Zhang

1995-02-01

161

Catalytic oxidation of volatile organic compounds on supported noble metals  

Microsoft Academic Search

Volatile organic compounds (VOCs) are toxic and mainly contribute to the formation of photochemical smog with a consequent remarkable impact to the air quality. A few techniques are available to reduce VOC emission, among them catalytic oxidation is suitable especially for highly diluted VOCs. The development of noble metals and transition metal oxides as catalysts for VOCs oxidation has been

L. F. Liotta

2010-01-01

162

Atomic layer deposition of rare-earth-based binary and ternary oxides for microelectronic applications  

NASA Astrophysics Data System (ADS)

Atomic layer deposition (ALD) has been established as a powerful method for the growth of very thin and conformal films to be used in ultra-scaled conventional and novel microelectronic devices. We report the most recent advancements in the field of ALD of rare-earth-based oxides to be implemented as active dielectrics. The review is balanced between the development of new ALD processes and the assessment and the discussion of fundamental scientific issues related to the structural, chemical and electrical properties of thin films of rare-earth-based oxides. The deposition process of binary lanthanide oxides is critically reviewed focusing on the first (La) and last (Lu) element of the series. Concomitantly, the integration of rare earth elements as dopant atoms in HfO2 and ZrO2 is also systematically reported. A final overview is dedicated to the results obtained by ALD of more innovative lanthanum-based ternary oxides.

Wiemer, C.; Lamagna, L.; Fanciulli, M.

2012-07-01

163

Metallic oxide switches using thick film technology  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

164

Chemical Sensors Based on Metal Oxide Nanostructures  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

165

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

166

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

167

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 0

Capone, Donald W. (Bolingbrook, IL); Poeppel, Roger B. (Glen Ellyn, IL)

1991-01-01

168

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

NASA Astrophysics Data System (ADS)

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

Rowland, Jason Conrad

169

The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33  

NASA Astrophysics Data System (ADS)

Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the "extra" WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ~100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations. The spectroscopic observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. MMT telescope time was granted by NOAO, through the Telescope System Instrumentation Program (TSIP). TSIP is funded by the National Science Foundation. This paper uses data products produced by the OIR Telescope Data Center, supported by the Smithsonian Astrophysical Observatory.

Neugent, Kathryn F.; Massey, Philip

2014-07-01

170

FUNCTIONALIZED METAL OXIDE NANOPARTICLES: ENVIRONMENTAL TRANSFORMATIONS AND ECOTOXICITY  

EPA Science Inventory

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

171

Nanotoxicity: oxidative stress mediated toxicity of metal and metal oxide nanoparticles.  

PubMed

Metal and metal oxide nanoparticles are often used as industrial catalysts or to improve product's functional properties. Recent advanced nanotechnology have been expected to be used in various fields, ranging from sensors, environmental remediation to biomedicine, medical biology and imaging, etc. However, the growing use of nanoparticles has led to their release into environment and increased levels of these particles at nearby sites or the surroundings of their manufacturing factories become obvious. The toxicity of metal and metal oxide nanoparticles on humans, animals, and certainly to the environment has become a major concern to our community. However, controversies still remain with respect to the toxic effects and the mechanisms of these nanoparticles. The scientific community now feels that an understanding of the toxic effects is necessary to handle these nanoparticles and their use. A new discipline, named nanotoxicology, has therefore been developed that basically refers to the study of the interactions of nanoparticles with biological systems and also measures the toxicity level related to human health. Nanoparticles usually generate reactive oxygen species to a greater extent than micro-sized particles resulting in increased pro-inflammatory reactions and oxidative stress via intracellular signaling pathways. In this review, we mainly focus on the routes of exposure of some metal and metal oxide nanoparticles and how these nanoparticles affect us or broadly the cells of our organs. We would also like to discuss the responsible mechanism(s) of the nanoparticle-induced reactive oxygen species mediated organ pathophysiology. A brief introduction of the characterization and application of these nanoparticles has also been included in the article. PMID:24730293

Sarkar, Abhijit; Ghosh, Manoranjan; Sil, Parames Chandra

2014-01-01

172

Fluidized reduction of oxides on fine metal powders without sintering  

NASA Technical Reports Server (NTRS)

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

Hayashi, T.

1985-01-01

173

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

174

Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials  

SciTech Connect

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

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

2003-11-18

175

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

NASA Astrophysics Data System (ADS)

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

Senturk, Bilge Seda

176

Energy level alignment in metal\\/oxide\\/semiconductor and organic dye\\/oxide systems  

Microsoft Academic Search

The alignment between the energy levels of the constituent materials of metal-oxide-semiconductor field effect transistors (MOSFET's) and dye sensitized solar cell (DSSC's) is a key property that is critical to the functions of these devices. We have measured the energy level alignment (band offsets) for metal\\/oxide\\/semiconductor (MOS) systems with high-kappa gate oxides and metal gates, and for organic dye\\/oxide systems.

Eric Bersch

2008-01-01

177

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

SciTech Connect

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

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

2013-02-10

178

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

NASA Astrophysics Data System (ADS)

We present comprehensive observational results of the metallicity effect on the fraction of globular clusters (GCs) that contain low-mass X-ray binaries (LMXB), by utilizing all available data obtained with Chandra for LMXBs and Hubble Space Telescope Advanced Camera for Surveys (ACS) for GCs. Our primary sample consists of old elliptical galaxies selected from the ACS Virgo and Fornax surveys. To improve statistics at both the lowest and highest X-ray luminosity, we also use previously reported results from other galaxies. It is well known that the fraction of GCs hosting LMXBs is considerably higher in red, metal-rich, GCs than in blue, metal-poor GCs. In this paper, we test whether this metallicity effect is X-ray luminosity-dependent and find that the effect holds uniformly in a wide luminosity range. This result is statistically significant (at >=3?) in LMXBs with luminosities in the range L X = 2 × 1037 to 5 × 1038 erg s-1, where the ratio of GC-LMXB fractions in metal-rich to metal-poor GCs is R = 3.4 ± 0.5. A similar ratio is also found at lower (down to 1036 erg s-1) and higher luminosities (up to the ULX regime), but with less significance (~2? confidence). Because different types of LMXBs dominate in different luminosities, our finding requires a new explanation for the metallicity effect in dynamically-formed LMXBs. We confirm that the metallicity effect is not affected by other factors such as stellar age, GC mass, stellar encounter rate, and galacto-centric distance.

Kim, D.-W.; Fabbiano, G.; Ivanova, N.; Fragos, T.; Jordán, A.; Sivakoff, G. R.; Voss, R.

2013-02-01

179

Prediction of electron energies in metal oxides.  

PubMed

The ability to predict energy levels in metal oxides is paramount to developinguseful materials, such as in the development of water photolysis catalysts and efficient photovoltaic cells. The binding energy of electrons in materials encompasses a wealth of information concerning their physicochemistry. The energies control the optical and electrical properties, dictating for which kinds of chemistry and physics a particular material is useful. Scientists have developed theories and models for electron energies in a variety of chemical systems over the past century. However, the prediction of quantitative energy levels in new materials remains a major challenge. This issue is of particular importance in metal oxide research, where novel chemistries have opened the possibility of a wide range of tailored systems with applications in important fields including light-emitting diodes, energy efficient glasses, and solar cells. In this Account, we discuss the application of atomistic modeling techniques, covering the spectrum from classical to quantum descriptions, to explore the alignment of electron energies between materials. We present a number of paradigmatic examples, including a series of oxides (ZnO, In2O3, and Cu2O). Such calculations allow the determination of a "band alignment diagram" between different materials and can facilitate the prediction of the optimal chemical composition of an oxide for use in a given application. Throughout this Account, we consider direct computational solutions in the context of heuristic models, which are used to relate the fundamental theory to experimental observations. We review a number of techniques that have been commonly applied in the study of electron energies in solids. These models have arisen from different answers to the same basic question, coming from solid-state chemistry and physics perspectives. We highlight common factors, as well as providing a critical appraisal of the strengths and weaknesses of each, emphasizing the difficulties in translating concepts from molecular to solid-state systems. Finally, we stress the need for a universal description of the alignment of band energies for materials design from first-principles. By demonstrating the applicability and challenges of using theory to calculate the relevant quantities, as well as impressing the necessity of a clarification and unification of the descriptions, we hope to provide a stimulus for the continued development of this field. PMID:24066925

Walsh, Aron; Butler, Keith T

2014-02-18

180

Task-specific ionic liquid for solubilizing metal oxides.  

PubMed

Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide, mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution. After transfer of the metal ions to the aqueous phase, the ionic liquid can be recycled for reuse. Betainium bis(trifluoromethylsulfonyl)imide forms one phase with water at high temperatures, whereas phase separation occurs below 55.5 degrees C (temperature switch behavior). The mixtures of the ionic liquid with water also show a pH-dependent phase behavior: two phases occur at low pH, whereas one phase is present under neutral or alkaline conditions. The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations. PMID:17048916

Nockemann, Peter; Thijs, Ben; Pittois, Stijn; Thoen, Jan; Glorieux, Christ; Van Hecke, Kristof; Van Meervelt, Luc; Kirchner, Barbara; Binnemans, Koen

2006-10-26

181

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

182

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

183

Electrochemical deposition under oxidizing conditions (EDOC): a new synthesis for nanocrystalline metal oxides  

Microsoft Academic Search

EDOC (Electrochemical Deposition under Oxidizing Conditions) is a new method for the electrochemical preparation of metal oxide nanoparticles. It is based on the reduction of metal ions; Coming from a sacrificial anode; In a non-aqueous medium. The formed metal clusters are immediately coated with stabilizers; Which prevent the particles from agglomeration and realize the nanocrystalline state. Thus we have prepared

A Dierstein; H Natter; F Meyer; H.-O Stephan; Ch Kropf; R Hempelmann

2001-01-01

184

Process to Upgrade OiL Using Metal Oxides.  

National Technical Information Service (NTIS)

Described herein are compositions and methods for using metal oxides to upgrade oil. Metal oxides may be used as catalysts to reduce the TAN of the oil by converting carboxylic acids such as naphthenic acids into non-corrosive products. In some cases, the...

A. Zhang Y. Tang

2005-01-01

185

Detection of chemical warfare agents using nanostructured metal oxide sensors  

Microsoft Academic Search

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

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

2005-01-01

186

Investigation of diagnostic techniques for metal oxide surge arresters  

Microsoft Academic Search

Gapless metal oxide surge arresters (MOSA) have been available in the market for many years since they were first introduced in the 1970's. The aim of this study is to investigate some reliable diagnostic techniques to assess the condition of a metal oxide surge arrester when subjected to severe lightning strikes in the field. A number of nondestructive and destructive

K. P. Mardira; T. K. Saha; R. A. Sutton

2005-01-01

187

The Close Binary Properties of Massive Stars in the Milky Way and Low-metallicity Magellanic Clouds  

NASA Astrophysics Data System (ADS)

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

Moe, Maxwell; Di Stefano, Rosanne

2013-12-01

188

Half-metallic oxide point contacts  

NASA Astrophysics Data System (ADS)

A classification of half-metals is illustrated with examples of ferromagnetic and ferrimagnetic oxides. I : V characteristics and magnetoresistance of contacts between oxides with localized electrons (Fe3O4) and delocalized electrons ((La0.7Sr0.3)MnO3) are discussed. The magnetoresistance is large when the conductance of the contact is less than the quantum of conductance G0 = 2e2/h. Broad distributions of point contacts are investigated in pressed powder compacts, illustrated by powder magnetoresistance measurements of CrO2, (La0.7Sr0.3)MnO3 and Fe3O4. When exchange coupling exists across an atomic scale contact, a narrow domain wall of width comparable to the contact size may be pinned there. Some consequences are thermal magnetic mode fluctuations, nonlinear I : V characteristics due to electron pressure on the wall and current-induced switching in a bistable `peanut' device with two closely spaced nanoconstrictions.

Coey, J. M. D.; Versluijs, J. J.; Venkatesan, M.

2002-10-01

189

Mn-based binary oxides as catalysts for the conversion of methane to C 2 hydrocarbons with carbon dioxide as oxidant  

Microsoft Academic Search

Binary oxides, mainly Ca-Mn, Sr-Mn and Ba-Mn, have been studied as catalysts for the coupling of CH4 to C2 hydrocarbons (C2H6 and C2H4) using CO2 as oxidant. At temperatures of ?840°C, the Ca-Mn catalyst exhibits quite similar performances to those of other Ca-containing binary oxide catalysts (Ca-Ce, Ca-Cr and Ca-Zn) reported previously; C2 selectivity and yield at 850°C increase remarkably

Ye Wang; Yasuo Ohtsuka

2001-01-01

190

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

PubMed

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

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

2014-02-01

191

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

192

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

193

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

194

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

195

Luminescence of charge transfer sensitizers anchored to metal oxide nanoparticles  

Microsoft Academic Search

The photoluminescence (PL) properties of inorganic charge transfer sensitizers anchored to nanometer sized metal oxide particles are presented. The charge transfer sensitizers are inorganic coordination compounds such as ruthenium tribipyridine, Ru(bpy)2+3, which have long lived metal-to-ligand charge transfer (MLCT) excited states. The metal oxides are insulators or semiconductor materials in the form of powders, colloidal solutions, and porous nanocrystalline films.

Todd A. Heimer; Gerald J. Meyer

1996-01-01

196

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

197

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

198

Oxidized film structure and method of making epitaxial metal oxide structure  

DOEpatents

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

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

2003-02-25

199

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] [Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural

1997-05-15

200

Growth, structure and properties of metal and metal oxide films  

NASA Astrophysics Data System (ADS)

Two systems, chromium and chromium oxide films on Pt(111), as well as rutile TiOsb2(110) surfaces, have been investigated using Low Energy Ion Scattering Spectroscopy (ISS), X-ray Photoelectron Spectroscopy (XPS), Low Energy Electron Diffraction (LEED), and Scanning Tunneling Microscopy (STM). The films of metal Cr and chromium oxide were grown by Cr vapor deposition in UHV and under an oxygen pressure of 2 x 10sp{-6} mbar, respectively. Both films grow in a step-flow mode. The Cr film is pseudomorphic to the Pt(111) substrate within the first two monolayers (ML). At higher coverages, the chromium overlayer adopts a bcc (110) surface structure and forms three-dimensional elongated islands oriented along the three close-packed directions of the Pt(111) surface. A self-organized Cr/Pt surface alloy is formed upon annealing 1.5-3 ML Cr/Pt(111) to 800 K. This alloy exhibits a highly-symmetric hexagonal network of one-atom-wide dislocation lines, with a unit cell dimension of 17.3 A. STM images reveal a strong variation of the local electronic structure due to the presence of a regular array of two-dimensional Cr clusters containing 10 atoms. For the chromium oxide, a well ordered p(2 x 2) structure is observed within the first 2 ML and attributed to the epitaxial growth of metastable Crsb3Osb4. At higher coverages, a (surd3 x surd3)R30sp° structure appears, due to formation of the stable Crsb2Osb3 phase. The influence of surface preparation procedures on the structure and appearance of TiOsb2(110) has been investigated. After initial cleaning and with increasing annealing temperature, the segregation of Ca impurity to the surfaces of fresh TiOsb2(110) single crystals has been observed. As revealed by LEED and STM, a ?ftlbrack {6enspace0atop 3enspace 1}rightrbrack structure is formed as an overlayer, with row-like features along the (001) direction. In line with the Ca 2psb{3/2} peak position of 347.4 eV, we propose formation of a CaTiOsb3-like compound, oriented with its (110) face parallel to the substrate. Upon annealing a sputtered rutile TiOsb2(110) surface and cooling it down in an oxygen background pressure, STM images show a highly-ordered (4 x 2) structure. We believe a new phase, anatase (110), is formed on the rutile TiOsb2(110) surface.

Zhang, Lanping

201

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

DOEpatents

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

Poston, J.A.

1997-12-02

202

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

203

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

204

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

SciTech Connect

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

Hu, Chaoquan, E-mail: cqhu@home.ipe.ac.cn [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China) [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Zhu, Qingshan [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)] [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Lin; Wu, Rongfang [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China) [State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China)

2009-12-15

205

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

NASA Astrophysics Data System (ADS)

We present N-body simulations of intermediate-mass (3000-4000 M?) young star clusters (SCs) with three different metallicities (Z = 0.01, 0.1 and 1 Z?), including metal-dependent stellar evolution recipes and binary evolution. Following recent theoretical models of wind mass-loss and core-collapse supernovae, we assume that the mass of the stellar remnants depends on the metallicity of the progenitor stars. In particular, massive metal-poor stars (Z ? 0.3 Z?) are enabled to form massive stellar black holes (MSBHs, with mass ?25 M?) through direct collapse. We find that three-body encounters, and especially dynamical exchanges, dominate the evolution of the MSBHs formed in our simulations. In SCs with Z = 0.01 and 0.1 Z?, about 75 per cent of simulated MSBHs form from single stars and become members of binaries through dynamical exchanges in the first 100 Myr of the SC life. This is a factor of ?3 more efficient than in the case of low-mass (<25 M?) stellar black holes. A small but non-negligible fraction of MSBHs power wind-accreting (10-20 per cent) and Roche lobe overflow (RLO, 5-10 per cent) binary systems. The vast majority of MSBH binaries that undergo wind accretion and/or RLO were born from dynamical exchange. This result indicates that MSBHs can power X-ray binaries in low-metallicity young SCs, and is very promising to explain the association of many ultraluminous X-ray sources with low-metallicity and actively star-forming environments.

Mapelli, M.; Zampieri, L.; Ripamonti, E.; Bressan, A.

2013-03-01

206

Novel magnetism of ultrathin iron oxide layers in metal\\/native oxide multilayers  

Microsoft Academic Search

Recently, magnetically soft, high-resistivity thin films have been fabricated using a metal\\/native oxide multilayer (MNOM) structure [1]. We present a study of the properties of the native oxide in MNOMs with Fe as the metal. The native oxide has a net moment of ~1.2mu_B\\/Fe atom. Mössbauer spectroscopy reveals an oxide spectrum dominated by a well-defined subspectrum with Fe^3+ valence and

G. S. D. Beach; F. T. Parker; A. E. Berkowitz; B. Ramadurai; D. J. Smith

2002-01-01

207

Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis  

NASA Astrophysics Data System (ADS)

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

Jin, Zhao

208

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

209

Nanoscale Metal Oxide Semiconductors for Gas Sensing  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

210

Determination of systems suitable for study as monotectic binary metallic alloy solidification models  

NASA Technical Reports Server (NTRS)

Succinonitrile-water and diethylene glycol-ethyl salicylate are two transparent systems which have been studied as monotectic binary metallic alloy solidification models. Being transparent, these systems allow for the direct observations of phase transformations and solidification reactions. The objective was to develop a screening technique to find systems of interest and then experimentally measure those systems. The succinonitrile-water system was used to check the procedures. To simulate the phase diagram of the system, two computer programs which determine solid-liquid and liquid-liquid equilibria were obtained. These programs use the UNIFAC method to determine activity coefficients and together with several other programs were used to predict the phase diagram. An experimental apparatus was developed and the succinonitrile-water phase diagram measured. The diagram was compared to both the simulation and literature data. Substantial differences were found in the comparisons which serve to demonstrate the need for this procedure.

Smith, J. E., Jr.

1983-01-01

211

Study of Superconducting State Parameters of Transition Metals Binary Alloys by a Pseudopotential Approach  

NASA Astrophysics Data System (ADS)

In the present article, we have reported the theoretical study of the superconducting state parameters (SSP) viz. electron-phonon coupling strength ?, Coulomb pseudopotential ?*, transition temperature TC, isotope effect exponent ? and effective interaction strength N0V of a 3d-transition metal-based binary alloys using Ashcroft's empty core (EMC) model potential. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. A considerable influence of various exchange and correlation functions on ? and ?* is found from the present study. The present results of the SSP are found in qualitative agreement with the available experimental data wherever they exist.

Vora, Aditya M.

212

Method for converting uranium oxides to uranium metal  

DOEpatents

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing 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

213

Method for converting uranium oxides to uranium metal  

DOEpatents

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

Duerksen, Walter K. (Norris, TN) [Norris, TN

1988-01-01

214

Process for making a noble metal on tin oxide catalyst  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

215

Design of a doubly grooved binary metallic diffraction grating For efficient side-pumping of high-power fiber lasers  

Microsoft Academic Search

A metallic binary grating with two grooves per period is applied to side-pump high-power fiber lasers for the first time. By combining a gradient algorithm and micro-genetic algorithm, the grating is optimized and the maximum coupling efficiencies of 94.77% and 77.27% for TM and TE polarization waves respectively are demonstrated.

Fan Zhang; Chuncan Wang; Zhi Tong; Geng Rui; Ning Tigang

2007-01-01

216

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

PubMed

The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong ? stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility. PMID:23994942

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

2013-12-01

217

Magnetotransport in half-metallic ferromagnetic oxides  

NASA Astrophysics Data System (ADS)

Magnetotransport properties are described for thin films of two different ferromagnetic oxide material systems that are thought to be half-metallic , with possible applications in spintronics: the doped lanthanum manganites, La1-xA xMnO3 where A = (Ca,Sr), and CrO2. Magnetotransport properties dominated by extrinsic (microstructure-dependent) effects are described for the manganites. The degree of crystalline texture is correlated to large changes in the magnetotransport, with less textured films showing a magnetoresistance (MR) that is both large and relatively temperature-independent over a wide temperature range, and exhibits a hysteretic peak structure in low fields. Microscopic disorder induced by ion irradiation in a highly-textured Sr-doped film induces a similar hysteretic peak structure in the MR. A mesoscopic model is described in which ion damage creates small regions of reduced magnetic properties, giving an enhanced MR for diffusive transport through those regions. Intrinsic magnetotransport properties are described for CrO2. At low temperatures, highly-textured CrO2 films grown by the high-pressure thermal decomposition of CrO3, exhibit record spin polarization and good metallic properties. As the temperature is raised through a characteristic value Delta = 80 K the character of transport changes because of the onset of strong magnetic scattering and a T2 law in the resistivity. The Hall effect data at low temperatures exhibit a sign reversal in low fields which is interpreted within a simple two-band model as indicating the presence of highly mobile holes and less mobile but more numerous electrons. The growth of CrO2 films by chemical vapor deposition (CVD) is described. X-ray diffraction data show that the CVD films---especially a film on (100) TiO2---are generally more strained than the high-pressure film. Magnetotransport measurements show much the same behavior as for the high-pressure film, except that the Hall effect reverses sign at a much higher field for the CVD film on (100) TiO2. For planar junctions with superconducting counter electrodes, a polarization of 97% was found in a metallic contact between CrO2 and Pb, and Zeeman-splitting the superconducting Al density of states in a CrO2/Al junction showed no evidence of minority spins.

Watts, Steven Michael

218

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

Microsoft Academic Search

Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously

John Perkins; David Ginley; Matthew Taylor; George A. Neuman; Henry A. Luten; Jeffrey A. Forgette; John S. Anderson

2010-01-01

219

Epitaxial Electrodeposition of Chiral Metal Oxide Films  

NASA Astrophysics Data System (ADS)

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

Switzer, Jay

2006-03-01

220

Reactive sputter deposition of metal oxide nanolaminates  

NASA Astrophysics Data System (ADS)

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 sputter deposition is a far-from-equilibrium process, thermodynamic considerations strongly influence both phase formation within layers and at interfaces. We show that pseudobinary phase diagrams can be used to predict interfacial cation mixing in the nanolaminates. However, size effects must be considered to predict specific structures. In the absence of pseudoepitaxy, size effects play a significant role in determining the nanocrystalline phases that form within a layer (e.g. tetragonal ZrO2, tetragonal HfO2, and orthorhombic HfO2) and at interfaces (e.g. monoclinic (Zr,Ti)O2). These phases are not bulk standard temperature and pressure phases. Their formation is understood in terms of self-assembly into the lowest energy structure in individual critical nuclei.

Rubin Aita, Carolyn

2008-07-01

221

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

222

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

223

Metal Oxide Gas Sensors: Sensitivity and Influencing Factors  

PubMed Central

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

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

2010-01-01

224

Custom-designed nanomaterial libraries for testing metal oxide toxicity.  

PubMed

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

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

2013-03-19

225

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

226

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

227

Interaction of poly-N-vinylpyrrolidone with hydrated metal oxides  

Microsoft Academic Search

On the basis of data of IR spectroscopy and powder diffraction analysis, an aqueous solution of poly-N-vinylpyrrolidone was\\u000a shown to interact with hydrated alumina and zirconia synthesized from corresponding metal chlorides by means of sol-gel technology.\\u000a A change was shown in the nature of polymer interaction with individual components and their binary mixture at different annealing\\u000a temperatures. Different mechanisms of

T. M. Zima; I. A. Vorsina; N. Z. Lyakhov

2009-01-01

228

Bilayer metal oxide gate insulators for scaled Ge-channel metal-oxide-semiconductor devices  

Microsoft Academic Search

We investigate the electrical properties of germanium-channel metal-oxide-semiconductor capacitors with an amorphous atomic-layer-deposited (ALD)-Al2O3 interlayer (IL) and higher-k ALD-TiO2 gate dielectric. An ALD-Al2O3 IL of ~1 nm thickness reduces the gate leakage current density at the otherwise low band-offset TiO2\\/Ge interface by six orders of magnitude at flatband. Devices with the thinnest Al2O3 IL exhibited a low capacitance equivalent thickness

Shankar Swaminathan; Michael Shandalov; Yasuhiro Oshima; Paul C. McIntyre

2010-01-01

229

Topochemical reactions of layered transition-metal oxides  

NASA Astrophysics Data System (ADS)

Low-temperature topochemical reactions performed on complex transition metal oxides allow the synthesis of novel, metastable phases often with unusual transition metal oxidation states and/or coordination geometries. Layered materials offer many opportunities to control the structural and chemical selectivity of these types of reactions to allow the preparation of desired phases in a rational manner. Using complex oxides adopting Ruddlesden–Popper type structures as examples, recent progress in the low-temperature topochemical reduction by anion de-intercalation, and oxidation by anion insertion, is reviewed.

Hayward, M. A.

2014-06-01

230

Catalytic combustion of benzene over supported metal oxides catalysts  

Microsoft Academic Search

Catalytic combustion of benzene over supported metal oxides has been investigated. The catalysts have been prepared by incipient\\u000a wetness method and characterized by XRD, FT-Raman, ESR and TPR. Among supported metal oxides, CuOx, supported on TiO2 is found to have the highest activity for benzene oxidation. In addition, among the catalysts of copper oxide supported on\\u000a TiO2, A12O3 and SiO2,

Seong-Soo Hong; Gwang-Ho Lee; Gun-Dae Lee

2003-01-01

231

Inert electrode containing metal oxides, copper and noble metal  

DOEpatents

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

Ray, Siba P. (Murrysville, PA); Woods, Robert W. (New Kensington, PA); Dawless, Robert K. (Monroeville, PA); Hosler, Robert B. (Sarver, PA)

2001-01-01

232

Inert electrode containing metal oxides, copper and noble metal  

DOEpatents

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

Ray, Siba P. (Murrysville, PA); Woods, Robert W. (New Kensington, PA); Dawless, Robert K. (Monroeville, PA); Hosler, Robert B. (Sarver, PA)

2000-01-01

233

Aerosol chemical vapor deposition of metal oxide films  

DOEpatents

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

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

1994-01-01

234

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) [Knoxville, TN

2001-01-01

235

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

PubMed

To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3 mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration. PMID:23571113

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

2013-08-01

236

Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials  

SciTech Connect

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

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

2004-04-27

237

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

238

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

Microsoft Academic Search

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

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

1993-01-01

239

Metal Oxidation in a Vacuum Tank.  

National Technical Information Service (NTIS)

Experiments were performed by a technique in which the metal is vaporized from an electrically heated container made of tantalum or tungsten. This technique was demonstrated to be efficient for quantitative metal-release studies. Eleven releases of alumin...

A. Macek

1973-01-01

240

Theoretical study of superconducting state parameters of binary metallic glasses by a pseudopotential method  

NASA Astrophysics Data System (ADS)

The theoretical investigations of the superconducting state parameters (SSP) viz. electron-phonon coupling strength ?, Coulomb pseudopotential ??, transition temperature T C, isotope effect exponent ? and effective interaction strength N0V of binary metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential for the first time. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. It is observed that ? and T C are quite sensitive to the selection of the local field correction functions in comparisons with ??, ? and N0V. The T C obtained from H-local field correction function is found in qualitative agreement with available experimental data and show linear nature with the concentration ( C). A linear T C equation is proposed by fitting the present outcomes for H-local field correction function, which is in conformity with other results for the experimental data. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the metallic glasses.

Vora, Aditya M.

2009-03-01

241

Theoretical Investigation of Superconducting State Parameters of Binary Metallic Glasses Cu1-cSnc  

NASA Astrophysics Data System (ADS)

Superconducting state parameters (SSP) viz. electron-phonon coupling strength l, Coulomb pseudopotential m*, transition temperature TC, isotope effect exponent a and effective interaction strength NO V of seven Cu1-c Snc binary metallic glasses have been reported using Ashcroft's empty core (EMC) model potential for the first time. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. The TC obtained from H-local field correction function are found in qualitative agreement with available experimental data and show linear nature with the concentration c of element Sn. A linear TC equation is proposed by fitting the present outcomes for H-local field correction function, which is in conformity with other results for the experimental data. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the metallic glasses.

Vora, Aditya M.

2008-07-01

242

Superconducting state parameters of La100- C Ga C binary metallic glasses  

NASA Astrophysics Data System (ADS)

The theoretical investigations of the superconducting state parameters (SSP) viz. electron-phonon coupling strength ?, Coulomb pseudopotential ?*, transition temperature T C , isotope effect exponent ? and effective interaction strength N O V of six binary La100- C Ga C ( C = 16, 20, 22, 24, 26 and 28 at. %) metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential for the first time. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. It is observed that the electron-phonon coupling strength ? and the transition temperature T C are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential ?*, isotope effect exponent ? and effective interaction strength N O V show weak dependences on the local field correction functions. The T C obtained from H-local field correction function are found in qualitative agreement with available experimental data and show almost linear nature with the concentration ( C) of ‘Ga’ element. A linear T C equation is proposed by fitting the present outcomes for H-local field correction function, which is in conformity with other results for the experimental data. Also, the present results are found to be in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the metallic glasses.

Vora, Aditya M.

2008-06-01

243

Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection  

PubMed Central

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

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

2009-01-01

244

Aerosol chemical vapor deposition of metal oxide films.  

National Technical Information Service (NTIS)

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 temperatu...

K. C. Ott T. T. Kodas

1990-01-01

245

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

DOEpatents

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

Morrell; Jonathan S. (Knoxville, TN), Ripley; Edward B. (Knoxville, TN) [Knoxville, TN

2009-05-05

246

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

247

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

PubMed

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

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

2013-04-01

248

Mechanism for bipolar resistive switching in transition metal oxides  

Microsoft Academic Search

Resistive andom access memories (RRAM) composed of a transtition metal oxide dielectric in a capacitor-like structure is a candidate technology for next generation non-volatile memory devices. We introduce a model that accounts for the bipolar resistive switching phenomenom observed in many perovskite transition metal oxides. It qualitatively describes the electric field-enhanced migration of oxygen vacancies at the nano-scale. The numerical

Marcelo Rozenberg; Maria Jose Sanchez; Ruben Weht; Carlos Acha; Fernando Gomez-Marlasca; Pablo Levy

2010-01-01

249

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

250

Use of Group IVB Metal Oxides for Curing Polyacrylic Rubber  

Microsoft Academic Search

Group IVB metal oxides, both with and without ethylene thiourea (ETU) have been used to cure polyacrylic rubber (ACM). Curing characteristics and properties of the vulcanizates have been studied with a view to elucidate curing mechanism with special reference to the role of metal oxides (e.g. SnO, SnO2, PbO, PbO2 and Pb3 O4). Best results are obtained with Pb3O4 in

P. Chowdhury; M. C. Chakravorti; C. K. Das

1994-01-01

251

The cobalt-iron metal\\/native oxide multilayer  

Microsoft Academic Search

A CoxFe100- x metal\\/native oxide multilayer (MNOM) structure has been developed and characterized. The MNOM consists of thin (˜20 A) nanocrystalline layers of a high-moment CoxFe100- x alloy that have been exposed in situ to oxygen to form metal\\/native oxide bilayers. Over a wide range of alloy composition (0 < x < 90), the MNOM exhibits a large saturation magnetization,

Geoffrey Stephen David Beach

2003-01-01

252

Novel nanocasting method for synthesis of ordered mesoporous metal oxides  

Microsoft Academic Search

Novel one-step high vacuum nanocasting method is developed to prepare ordered mesoporous rare earth and transition metal oxides\\u000a with high-surface area using mesoporous KIT-6 as hard templates. Characterization of these mesostructured materials was performed\\u000a by the X-ray powder diffraction, high resolution transmission electron microscopy and N2 adsorption–desorption isotherms. In this synthesis method, metal oxide precursors are effectively filled into the

AiGuo Kong; HaiYan Zhu; WenJuan Wang; QiYing Zhang; Fan Yang; YongKui Shan

2011-01-01

253

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

PubMed

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

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

2012-04-15

254

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

NASA Astrophysics Data System (ADS)

We report our studies on an improved soft chemical route to directly fabricate graphene nanoplate-metal oxide (Ag 2O, Co 3O 4, Cu 2O and ZnO) composites from the in situ oxidation of graphene nanoplates. By virtue of H + from hydrolysis of the metal nitrate aqueous solution and NO 3-, 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.

Chen, Sheng; Zhu, Junwu; Wang, Xin

2011-06-01

255

Process for Making a Noble Metal on Tin Oxide Catalyst  

NASA Technical Reports Server (NTRS)

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

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

256

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

257

Enrofloxacin oxidative degradation facilitated by metal oxide nanoparticles.  

PubMed

The activity of copper oxide, titanium carbide and silicon nitride nanoparticles for the oxidative degradation of environmentally relevant concentrations (?g L(-1) range) of enrofloxacin - an important veterinary antibiotic drug - in aqueous solutions was investigated. With hydrogen peroxide as an oxidative agent, both copper oxide and titanium carbide decrease the concentration of enrofloxacin by more than 90% over 12 h. Addition of sodium halide salts strongly increases the reaction rate of copper oxide nanoparticles. The mechanism for the formation of Reactive Oxygen Species (ROS) was investigated by Electron Spin Resonance (ESR). PMID:22055313

Fink, Lea; Dror, Ishai; Berkowitz, Brian

2012-01-01

258

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

260

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

PubMed

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

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

2014-05-01

261

Metal-oxide-based energetic materials and synthesis thereof  

DOEpatents

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

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

2006-01-17

262

Integrated photo-responsive metal oxide semiconductor circuit  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

263

Total oxidation of toluene over metal oxides supported on a natural clinoptilolite-type zeolite  

Microsoft Academic Search

Some selected (Mn2+, Co2+, Fe3+, Cu2+) oxides supported on clinoptilolite were tested in the catalytic incineration of toluene. Manganese oxide on clinoptilolite was found to be the most active and durable of all tested. The effects of ion exchanger concentration, ion exchange time, ion exchange temperature and the type of ion exchanger were also studied to screen metal oxide catalysts.

Gülin S. Pozan Soylu; Zeynep Özçelik; ?smail Boz

2010-01-01

264

Chromia on metal oxide catalysts for the oxidation of methane to methanol  

SciTech Connect

A method is described for the direct conversion of light alkanes to alcohols comprising contacting said light alkanes with an oxidant in the presence of catalyst comprising a surface oxide chromate in which chromium is chemically bound to oxygen of a metal oxide support surface.

Lyons, J.E.; Durante, V.A.; Walker, D.W.

1993-06-15

265

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

SciTech Connect

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

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

1993-10-01

266

Superconductivity in the metallic–oxidized copper interface  

Microsoft Academic Search

A strong indication of superconductivity at 20–90K in the interface formed by metallic and oxidized copper has been revealed by ac magnetic susceptibility measurements. By means of X-ray diffraction measurements, it has been found that the oxidized copper consists of a mixture of Cu2O and CuO compounds.

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

2011-01-01

267

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

268

Thermodynamic Properties of Some Metal Oxide-Zirconia Systems.  

National Technical Information Service (NTIS)

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...

N. S. Jacobson

1989-01-01

269

Oxidation of rapeseed oil: Effect of metal traces  

Microsoft Academic Search

Traces of heavy metals in edible oils are known to have an effect on the rate of oil oxidation. In this investigation we studied\\u000a the effect of trace metals by excluding instead of adding them. Three supports were used to fix trace metals: grafted cellulose,\\u000a cationic resin and absorbent resin. Cationic resin and grafted cellulose allowed copper (Cu) and iron

B. Benjellourr; T. Talou; M. Delmas; A. Gaset

1991-01-01

270

All-alkoxide synthesis of strontium-containing metal oxides  

Microsoft Academic Search

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,

Boyle; Timothy J

2001-01-01

271

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

2013-10-25

272

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

Microsoft Academic Search

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

Ming Yin

2005-01-01

273

Adsorption/Oxidation of arsenic in groundwater by nanoscale Fe-Mn binary oxides loaded on zeolite.  

PubMed

Nanoscale Fe-Mn binary oxides loaded on zeolite (NIMZ) is synthesized and characterized. The as-synthesized adsorbent is amorphous with 126 m2/g surface area; it is effective for the adsorption of both As(III) and As(V) in synthetic groundwater. It has high adsorption capacities of 296.23 and 201.10 mg/g for As(III) and As(V), respectively. For the adsorption of 2 mg/L arsenic, the aqueous concentration quickly decreases to less than 10 /microg/L within 30 min. During the adsorption of As(III), the in-aqueous measurement of As(V) shows a low concentration in the initial stage and disappears afterward. The fraction of As(V) on NIMZ gradually increases with time, proving the oxidation of As(III). The adsorption of As(III) and As(V) decreases with increasing pH. The anions of SiO3(2-), H2PO4(-), and HCO3(-) significantly compete with arsenic for the adsorption sites. The innersphere surface complexes are formed by As(III) or As(V) with the hydroxyl groups on the surface of NIMZ. PMID:24645545

Kong, Shuqiong; Wang, Yanxin; Zhan, Hongbin; Yuan, Songhu; Yu, Mei; Liu, Mingliang

2014-02-01

274

Metal oxide and mercuric sulfide nanoparticles synthesis and characterization  

Microsoft Academic Search

Commercially available and laboratory-synthesized metal based nanoparticles (NPs), iron oxide (Fe2O3), copper oxide (CuO), titanium dioxide (TiO2), zinc oxide (ZnO) and mercuric sulfide (HgS) were studied by comprehensive characterizations methods. The general synthesis process was modified sol-gel method. The size and morphology of NPs could be influenced by temperature, sonication, calcination, precursor concentration, pH and types of reaction media. All

Xin Xu

2009-01-01

275

Catalyzed decomposition of N 2O on metal oxide supports  

Microsoft Academic Search

The catalytic decomposition of N2O using metal oxides supported on silica, magnesium oxide, calcium oxide and hydrotalcite-like supports was studied. CoO is much more active than CuO and Fe2O3 when supported on silica. A conversion of 95% was achieved using CoO on SiO2 at 1500 h?1 GHSV, 500°C and 50,000 ppm feed N2O. However, the use of higher flow rates

Russell S. Drago; Krzysztof Jurczyk; Nicholas Kob

1997-01-01

276

Copper Alloys From Metal Oxide Precursors for High Conductivity Applications  

Microsoft Academic Search

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

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

2004-01-01

277

Reductive mobilization of oxide-bound metals  

SciTech Connect

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

Stone, A.T.

1991-01-01

278

Transition metal oxides deposited on rhodium and platinum: Surface chemistry and catalysis  

Microsoft Academic Search

The surface chemistry and catalytic reactivity of transition metal oxides deposited on Rh and Pt substrates has been examined in order to establish the role of oxide-metal interactions in influencing catalytic activity. The oxides investigated included titanium oxide (TiOx), vanadium oxide (VOx), iron oxide (FeOx), zirconium oxide (ZrOx), niobium oxide (NbOx), tantalum oxide (TaOx), and tungsten oxide (WOx). The techniques

Boffa

1994-01-01

279

Efficient removal of trace arsenite through oxidation and adsorption by magnetic nanoparticles modified with Fe-Mn binary oxide.  

PubMed

Magnetic nanoparticles (MNPs) modified simultaneously with amorphous Fe and Mn oxides (Mag-Fe-Mn) were synthesized to remove arsenite [As(III)] from water. Mag-Fe-Mn particles were fabricated through heterogeneous nucleation technique by employing the maghemite as the magnetic core and Fe-Mn binary oxide (FMBO) as the coating materials. Powder X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy were utilized to characterize the hybrid material. With a saturation magnetization of 23.2 emu/g, Mag-Fe-Mn particles with size of 20-50 nm could be easily separated from solutions with a simple magnetic process in short time (within 5 min). At pH 7.0, 200 ?g/L of As(III) could be easily decreased to below 10 ?g/L by Mag-Fe-Mn particles (0.1 g/L) within 20 min. As(III) could be effectively removed by Mag-Fe-Mn particles at initial pH range from 4 to 8 and the residual As was completely oxidized to less toxic arsenate [As(V)]. The co-occurring redox reactions between Mn oxide and As(III) was confirmed by XPS analysis. Chloride, sulfate, bicarbonate, and nitrate at common concentration range had negligible influence on As(III) removal, whereas, silicate and phosphate reduced the As(III) removal by competing with arsenic species for adsorption sites. As(III) removal was not obviously affected by natural organic matter (up to 8 mg/L as TOC). Mag-Fe-Mn could be regenerated with ternary solution of NaOH, NaCl, and NaClO. Throughout five consecutive cycles, the adsorption and desorption efficiencies maintained above 98% and 87%, respectively. Mag-Fe-Mn had a larger adsorption capacity for As(III) (47.76 mg/g) and could remove trace As(III) more thoroughly than MNPs modified solely with either Fe or Mn oxide due to the synergistic effect of the coating Fe and Mn oxides. This research extended the potential applicability of FMBO to a great extent and provided a convenient approach to efficiently remove trace As(III) from water. PMID:23587265

Shan, Chao; Tong, Meiping

2013-06-15

280

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

281

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

NASA Astrophysics Data System (ADS)

This research focuses on studying metal oxides (MnO 2, Co3O4, MgO, Y2O3) for various applications including water oxidation and photocatalytic oxidation, developing different synthesis methodologies, and presenting detailed characterization studies of these metal oxides. This research consists of three major parts. The first part is studying novel applications and developing a synthesis method for manganese oxide nanomaterials. Manganese oxide materials were studied for renewable energy applications by using them as catalysts for water oxidation reactions. In this study, various crystallographic forms of manganese oxides (amorphous, 2D layered, 1D 2 x 2 tunnel structures) were evaluated for water oxidation catalysis. Amorphous manganese oxides (AMO) were found to be catalytically active for chemical and photochemical water oxidation compared to cryptomelane type tunnel manganese oxides (2 x 2 tunnels; OMS2) or layered birnessite (OL-1) materials. Detailed characterization was done to establish a correlation between the properties of the manganese oxide materials and their catalytic activities in water oxidation. The gas phase photocatalytic oxidation of 2-propanol under visible light was studied using manganese oxide 2 x 2 tunnel structures (OMS-2) as catalysts (Chapter 3). The reaction is 100% selective to acetone. As suggested by the photocatalytic and characterization data, important factors for the design of active OMS-2 photocatalysts are synthesis methodology, morphology, mixed valency and the release of oxygen from the OMS-2 structure. Manganese oxide octahedral molecular sieves (2 x 2 tunnels; OMS-2) with self-assembled dense or hollow sphere morphologies were fabricated via a room temperature ultrasonic atomization assisted synthesis (Chapter 4). The properties and catalytic activities of these newly developed materials were compared with that of OMS-2 synthesized by conventional reflux route. These materials exhibit exceptionally high catalytic activities in oxidation reactions and adsorption of heavy metal. Spontaneous formation of OMS-2 nanospheres was possible by tuning reaction parameters in the ultrasonic atomization process. In the second part, a microwave-hydrothermal route has been developed for the synthesis of 1D cobalt compounds (Chapter 5). These compounds are transformed to spinel type Co3O4 nanorods. The effects of solvents, cobalt sources, and microwave radiation time in the formation of 1D cobalt oxide nanostructures were studied in detail. These materials are catalytically active for CO oxidation and styrene oxidation reactions. Magnesia-yttria nanocomposites with controlled nanoscale grain sizes and homogenous microstructures are useful as IR transparent materials. A simple cost-effective sucrose based sol-gel route was devised for making MgO-Y 2O3 nanocomposites. Grain growth in these nanocomposites was systematically evaluated using transmission electron microscopy studies.

Iyer, Aparna

282

Aerosol chemical vapor deposition of metal oxide films  

SciTech Connect

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

283

The base metal of the oxide-coated cathode  

NASA Astrophysics Data System (ADS)

The oxide-coated cathode has been the most widely used electron emitter in vacuum electronic devices. From one manufacturing company to another the emissive oxide is either a double—Ba, Sr—or a triple—Ba, Sr, Ca—oxide, having always the same respective compositions. Conversely, the base metal composition is very often proprietary because of its importance in the cathode emission performances. The present paper aims at explaining the operation of the base metal through a review. After a brief introduction, the notion of activator is detailed along with their diffusivities and their associated interfacial compounds. Then, the different cathode life models are described prior to few comments on the composition choice of a base metal. Finally, the specificities of the RCA/Thomson "bimetal" base metal are presented with a discussion on the optimized composition choice illustrated by a long-term life-test of five different melts.

Poret, F.; Roquais, J. M.

2005-09-01

284

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

285

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) [Oak Ridge, TN; Holder, John D. (Knoxville, TN) [Knoxville, TN; Pasto, Arvid E. (Oak Ridge, TN) [Oak Ridge, TN

1980-01-01

286

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

Microsoft Academic Search

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

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

2005-01-01

287

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

288

Application of a mixed metal oxide catalyst to a metallic substrate  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

289

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

290

Ethanol oxidation on metal oxide-supported platinum catalysts  

SciTech Connect

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

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

2009-09-01

291

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

292

The MSFC Complementary Metal Oxide Semiconductor (Including Multilevel Interconnect Metallization) Process Handbook.  

National Technical Information Service (NTIS)

The fabrication techniques for creation of complementary metal oxide semiconductor integrated circuits at George C. Marshall Space Flight Center are described. Examples of C-MOS integrated circuits manufactured at MSFC are presented with functional descri...

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

1979-01-01

293

Electron Correlation Effects in Half-Metallic Transition Metal Oxides  

NASA Astrophysics Data System (ADS)

Spin-resolved photoemission and absorption studies of Fe3O4 and CrO2 epitaxial thin films have been reviewed to address the relationship between the electron correlation effects and the half-metallic properties of these two materials. Spin-resolved photoemission results suggest that Fe3O4 should be considered as a strongly correlated system, and that Fe3O4 is not a half-metal. Spin-resolved O 1s X-ray absorption measurements on ferromagnetic CrO2 reveal that the spin polarization of the unoccupied states closest to the Fermi level approaches 100%, confirming the half-metallic ferromagnetic nature of the material. The spin polarization of the main line of the unoccupied states, on the other hand, is found to be only 50%, indicating a very atomic-like behavior of the Cr 3d2 ions.

Huang, D. J.; Tjeng, L. H.; Chen, J.; Chang, C. F.; Wu, W. P.; Rata, A. D.; Hibma, T.; Chung, S. C.; Shyu, S.-G.; Wu, C.-C.; Chen, C. T.

294

Electron Correlation Effects in Half-Metallic Transition Metal Oxides  

Microsoft Academic Search

Spin-resolved photoemission and absorption studies of Fe3O4 and CrO2 epitaxial thin films have been reviewed to address the relationship between the electron correlation effects and the half-metallic properties of these two materials. Spin-resolved photoemission results suggest that Fe3O4 should be considered as a strongly correlated system, and that Fe3O4 is not a half-metal. Spin-resolved O 1s X-ray absorption measurements on

D. J. Huang; L. H. Tjeng; J. Chen; C. F. Chang; W. P. Wu; A. D. Rata; T. Hibma; S. C. Chung; S.-G. Shyu; C.-C. Wu; C. T. Chen

2002-01-01

295

Deposition of Metal Oxide Films from Metal-EDTA Complexes by Flame Spray Technique  

NASA Astrophysics Data System (ADS)

R2O3 (R = Y, Eu, Er) metal oxides were synthesized from metal-ethylenediaminetetraacetic acid (EDTA) complexes using a flame spray technique. As this technique enables high deposition rates, films with thickness of several tens of micrometers were obtained. Films of yttria, europia, and erbia phase were synthesized on stainless-steel substrates with reaction assistance by H2-O2 combustion gas. The oxide films consisted of the desired crystalline phase with micropores. The porosity of the films was in the range of 6-15%, varying with the metal used. These results suggest that the true density of the metal oxide obtained from metal-EDTA powder through the thermal reaction process plays an important role in achieving film with the desired porosity.

Komatsu, Keiji; Sekiya, Tetsuo; Toyama, Ayumu; Hasebe, Yasuhiro; Nakamura, Atsushi; Noguchi, Masahiro; Li, Yu; Ohshio, Shigeo; Akasaka, Hiroki; Muramatsu, Hiroyuki; Saitoh, Hidetoshi

2014-06-01

296

Deposition of Metal Oxide Films from Metal-EDTA Complexes by Flame Spray Technique  

NASA Astrophysics Data System (ADS)

R2O3 (R = Y, Eu, Er) metal oxides were synthesized from metal-ethylenediaminetetraacetic acid (EDTA) complexes using a flame spray technique. As this technique enables high deposition rates, films with thickness of several tens of micrometers were obtained. Films of yttria, europia, and erbia phase were synthesized on stainless-steel substrates with reaction assistance by H2-O2 combustion gas. The oxide films consisted of the desired crystalline phase with micropores. The porosity of the films was in the range of 6-15%, varying with the metal used. These results suggest that the true density of the metal oxide obtained from metal-EDTA powder through the thermal reaction process plays an important role in achieving film with the desired porosity.

Komatsu, Keiji; Sekiya, Tetsuo; Toyama, Ayumu; Hasebe, Yasuhiro; Nakamura, Atsushi; Noguchi, Masahiro; Li, Yu; Ohshio, Shigeo; Akasaka, Hiroki; Muramatsu, Hiroyuki; Saitoh, Hidetoshi

2014-04-01

297

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

298

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

299

Silicon metal-semiconductor–metal photodetector with zinc oxide transparent conducting electrodes  

Microsoft Academic Search

Transparent conducting oxides thin layers, due to their optical and electrical properties, can be used as transparent electrodes in various optoelectronic devices. We present a metal-semiconductor–metal photodiode (MSM-PD) on silicon as optically active layer with zinc oxide (ZnO) thin layer as interdigitated Schottky transparent electrodes. The advantage of using a ZnO thin layer as Schottky electrodes consists in the improvement

E. Budianu; M. Purica; F. Iacomi; C. Baban; P. Prepelita; E. Manea

2008-01-01

300

Metal-oxide interfaces at the nanoscale  

NASA Astrophysics Data System (ADS)

In contrast to the 6×7 spacing registry that yields a minimum coincidence misfit, we find that the nanoscale Cu2O-Cu interface formed during initial oxidation of Cu(111) surfaces adopts a 5×6 coincidence site lattice that is accommodated by an increased lattice misfit strain. A simple analysis on the equilibrium elastic strain in epitaxial oxide nanoislands reveals a previously unnoticed correlation between the interface structure and surface stresses at the nanoscale.

Zhou, Guangwen

2009-06-01

301

Morphological investigations on mesostructured metal oxides  

SciTech Connect

The synthesis and characterization of mesostructured zirconia and titanium oxides is presented. The samples were investigated by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). XRD and TEM only revealed lamellar structures for both materials, whereas AFM could detect locally restricted initial stages of cubic or hexagonal phases in a globally lamellar Ti oxide. {copyright} {ital 1997 Materials Research Society.}

Weindenhof, V. [Institute of Experimental Physics, University of Saarbruecken, P.O. Box 151150, D-66041 Saarbruecken (Germany); Gropper, F.; Mueller, U. [ZAK/Z, BASF AG, D-67059 Ludwigshafen (Germany); Marosi, L.; Cox, G. [ZAA/S, BASF AG, D-67059 Ludwigshafen (Germany); Houbertz, R.; Hartmann, U. [Institute of Experimental Physics, University of Saarbruecken, P.O. Box 151150, D-66041 Saarbruecken (Germany)

1997-06-01

302

On the Origin of the Metallicity Dependence in Dynamically formed Extragalactic Low-mass X-Ray Binaries  

NASA Astrophysics Data System (ADS)

Globular clusters (GCs) effectively produce dynamically formed low-mass X-ray binaries (LMXBs). Observers detect ~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 X between 2 × 1037 and 5 × 1038 erg s-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.; Fragos, T.; Kim, D.-W.; Fabbiano, G.; Avendano Nandez, J. L.; Lombardi, J. C.; Sivakoff, G. R.; Voss, R.; Jordán, A.

2012-12-01

303

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

304

Metal ion adsorption to complexes of humic acid and metal oxides: Deviations from the additivity rule  

SciTech Connect

The adsorption of cadmium ions to a mixture of Aldrich humic acid and hematite is investigated. The actual adsorption to the humic acid-hematite complex is compared with the sum of the cadmium ion adsorptivities to each of the isolated components. It is shown that the sum of the cadmium ion adsorptivities is not equal to the adsorption to the complex. In general, the adsorption of a specific metal ion to the complex can be understood and qualitatively predicted using the adsorptivities to each of the pure components and taking into account the effect of the pH on the interaction between humic acid and iron oxide on the metal ion adsorption. Due to the interaction between the negatively charged humic acid and the positively charged iron oxide, the adsorption of metal ions on the mineral oxide in the complex will increase as compared to that on the isolated oxide, whereas the adsorption to the humic acid will decrease as compared to that on the isolated humic acid. As a result, the overall adsorption of a specific metal ion to the complex will be smaller than predicted by the additivity rule when this metal ion has a more pronounced affinity for the humic acid than for the mineral oxide, whereas it will be larger than predicted by the additivity rule when the metal ion has a higher affinity for the oxide than for the humic acid.

Vermeer, A.W.P.; McCulloch, J.K.; Van Riemsdijk, W.H.; Koopal, L.K.

1999-11-01

305

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

2013-06-19

306

Advances in metal-induced oxidative stress and human disease.  

PubMed

Detailed studies in the past two decades have shown that redox active metals like iron (Fe), copper (Cu), chromium (Cr), cobalt (Co) and other metals undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biological systems. Disruption of metal ion homeostasis may lead to oxidative stress, a state where increased formation of reactive oxygen species (ROS) overwhelms body antioxidant protection and subsequently induces DNA damage, lipid peroxidation, protein modification and other effects, all symptomatic for numerous diseases, involving cancer, cardiovascular disease, diabetes, atherosclerosis, neurological disorders (Alzheimer's disease, Parkinson's disease), chronic inflammation and others. The underlying mechanism of action for all these metals involves formation of the superoxide radical, hydroxyl radical (mainly via Fenton reaction) and other ROS, finally producing mutagenic and carcinogenic malondialdehyde (MDA), 4-hydroxynonenal (HNE) and other exocyclic DNA adducts. On the other hand, the redox inactive metals, such as cadmium (Cd), arsenic (As) and lead (Pb) show their toxic effects via bonding to sulphydryl groups of proteins and depletion of glutathione. Interestingly, for arsenic an alternative mechanism of action based on the formation of hydrogen peroxide under physiological conditions has been proposed. A special position among metals is occupied by the redox inert metal zinc (Zn). Zn is an essential component of numerous proteins involved in the defense against oxidative stress. It has been shown, that depletion of Zn may enhance DNA damage via impairments of DNA repair mechanisms. In addition, Zn has an impact on the immune system and possesses neuroprotective properties. The mechanism of metal-induced formation of free radicals is tightly influenced by the action of cellular antioxidants. Many low-molecular weight antioxidants (ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), glutathione (GSH), carotenoids, flavonoids, and other antioxidants) are capable of chelating metal ions reducing thus their catalytic activity to form ROS. A novel therapeutic approach to suppress oxidative stress is based on the development of dual function antioxidants comprising not only chelating, but also scavenging components. Parodoxically, two major antioxidant enzymes, superoxide dismutase (SOD) and catalase contain as an integral part of their active sites metal ions to battle against toxic effects of metal-induced free radicals. The aim of this review is to provide an overview of redox and non-redox metal-induced formation of free radicals and the role of oxidative stress in toxic action of metals. PMID:21414382

Jomova, Klaudia; Valko, Marian

2011-05-10

307

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

308

Ab initio study of lithium intercalation in metal oxides and metal dichalcogenides  

Microsoft Academic Search

A study of the average voltage to intercalate lithium in various metal oxides is presented. By combining the ab initio pseudopotential method with basic thermodynamics the average intercalation voltage can be predicted without the need for experimental data. This procedure is used to systematically study the effect of metal chemistry, anion chemistry, and structure. It is found that Li is

M. K. Aydinol; A. F. Kohan; G. Ceder; K. Cho; J. Joannopoulos

1997-01-01

309

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

310

Metals, nitrides, and carbides via solar carbothermal reduction of metal oxides  

Microsoft Academic Search

We have examined the thermodynamics of the carbothermic reduction of metal oxides in either nitrogen or argon atmospheres. The reaction, which is given generally by (where the M denotes metal) MxOy + C (+ N2;) ? {Mx?Ny?, Mx?Cy?, M} + CO, is highly endothermic and proceeds at temperatures from 1300 to 2350 K for the systems considered. Exploratory experimental studies

Edward A. Fletcher

1995-01-01

311

Ion exchange properties of novel hydrous metal oxide materials  

SciTech Connect

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

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

1996-12-31

312

Metal-oxide semiconductor nanostructures for energy and sensing applications  

NASA Astrophysics Data System (ADS)

The growth and structural/optical properties of metal-oxide semiconductor nanostructures by a simple, low-cost, and large-scalable fabrication method were studied. These nanostructures were applied to energy and optoelectronic devices, such as piezoelectric nanogenerators and photodetective sensors, to improve the device performance. The morphologies and crystallinity of the fabricated nanostructures were observed from scanning electron microscope/transmission electron microscope images, respectively. The piezoelectric output current and photoresponse property were characterized by manufacturing the nanogenerators and photodetectors with prepared metal oxide nanostructures. These results can provide a fundamental understanding of the mechanisms for improving the device performance in applications of metal-oxide semiconductor nanostructures for energy and sensing devices.

Yu, Jae Su; Ko, Yeong Hwan

2014-03-01

313

Engineering metal oxide structures for efficient photovoltaic devices  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

314

Conversion of Metal Oxide Nanosheets into Nanotubes  

NASA Astrophysics Data System (ADS)

In this chapter, structural relationship and conversion between two-dimensional (2D) nanosheets and one-dimensional (1D) nanotubes are reviewed. Nanotubes are spontaneously formed upon exfoliation of certain layered materials with a non-centrosymmetric or particular structure, such as K4Nb6O17 and some perovskite-type Ruddlesden-Popper phase K2[A n-1B n O_3n+1] (A = Na, Ca, Sr, La; B = Ta, Ti). On the other hand, colloidal centrosymmetric nanosheets represented by titanium oxide, manganese oxide, and calcium niobium oxide can also be successfully converted into their corresponding nanotubes through a simple ion intercalation/deintercalation procedure at ambient temperature. The conversion validates the hypothesis, in which directly rolling a nanosheet yields a nanotube. The close relationship is of fundamental importance in revealing the formation mechanism of nanotubes and may be used to realize a customized synthesis of nanotubes from a wide range of layered materials.

Ma, Renzhi; Sasaki, Takayoshi

315

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

316

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...

317

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

318

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

319

Enhanced arsenic removal using mixed metal oxide impregnated chitosan beads.  

PubMed

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

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

2012-09-15

320

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

321

Solution synthesis of metal oxides for electrochemical energy storage applications  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

322

Metal oxide-hydrogen battery having an outer safety shell  

SciTech Connect

A metal oxide hydrogen battery assembly is described, comprising a metal oxide hydrogen battery having an outer pressure vessel and having at least one cell module contained within the pressure vessel, said pressure vessel containing pressurized hydrogen gas, said cell module having a positive and a negative terminal, an outer gas-impermeable shell disposed around the pressure vessel to provide a space there between, electrical connecting means connected to said terminals and extending through said pressure vessel and extending to the exterior of said shell, and vent conduit means communicating with said space for venting any hydrogen gas leaking from said pressure vessel from said space to the exterior.

Jones, K.R.

1993-06-01

323

Solution synthesis of metal oxides for electrochemical energy storage applications.  

PubMed

This article provides an overview of solution-based methods for the controllable synthesis of metal oxides and their applications for electrochemical energy storage. Typical solution synthesis strategies are summarized and the detailed chemical reactions are elaborated for several common nanostructured transition metal oxides and their composites. The merits and demerits of these synthesis methods and some important considerations are discussed in association with their electrochemical performance. We also propose the basic guideline for designing advanced nanostructure electrode materials, and the future research trend in the development of high power and energy density electrochemical energy storage devices. PMID:24696018

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

2014-05-21

324

Pb(II) distributions at biofilm-metal oxide interfaces.  

PubMed

The distribution of aqueous Pb(II) sorbed at the interface between Burkholderia cepacia biofilms and hematite (alpha-Fe(2)O(3)) or corundum (alpha-Al(2)O(3)) surfaces has been probed by using an application of the long-period x-ray standing wave technique. Attached bacteria and adsorbed organic matter may interfere with sorption processes on metal oxide surfaces by changing the characteristics of the electrical double layer at the solid-solution interface, blocking surface sites, or providing a variety of new sites for metal binding. In this work, Pb L(alpha) fluorescence yield profiles for samples equilibrated with 10(-7) to 10(-3.8) M Pb(II) were measured and modeled to determine quantitatively the partitioning of Pb(II) at the biofilm-metal oxide interface. Our data show that the reactive sites on the metal oxide surfaces were not passivated by the formation of a monolayer biofilm. Instead, high-energy surface sites on the metal oxides form the dominant sink for Pb(II) at submicromolar concentrations, following the trend alpha-Fe(2)O(3) (0001) > alpha-Al(2)O(3) (1102) > alpha-Al(2)O(3) (0001), despite the greater site density within the overlying biofilms. At [Pb] > 10(-6) M, significant Pb uptake by the biofilms was observed. PMID:11572932

Templeton, A S; Trainor, T P; Traina, S J; Spormann, A M; Brown, G E

2001-10-01

325

The Electrochemical Displacement Reaction of Lithium with Metal Oxides  

Microsoft Academic Search

The electrochemical reaction of lithium with a-LiFeO2, b-Li5FeO4 , and CoO is studied by in situ X-ray diffraction and in situ Mossbauer measurements. The results of the measurements show that these metal oxides are immediately decomposed during discharge to form lithia and the reduced metal. This reaction proceeds through a single intermediate or surface phase. The reaction products are nanometer-sized,

M. N. Obrovac; R. A. Dunlap; R. J. Sanderson; J. R. Dahn

2001-01-01

326

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

PubMed Central

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

Yu, Chongqi; Wang, Hui

2010-01-01

327

Alkali metal-doped cobalt oxide catalysts for NO decomposition  

Microsoft Academic Search

The effect of addition of alkali metals was investigated on the catalytic activity of cobalt oxide (Co3O4) for the direct decomposition of NO. Although Co3O4 was totally inactive, NO decomposition over Co3O4 was significantly promoted by the addition of alkali metals (Li, Na, K, Rb and Cs). Potassium was found to be the most effective additive. The addition of alkali

Masaaki Haneda; Yoshiaki Kintaichi; Nicolas Bion; Hideaki Hamada

2003-01-01

328

Carbochlorination of metal oxides using a fused salt slurry reactor  

Microsoft Academic Search

This research project was a study of the carbochlorination of metal oxides of fly ash from the combustion of pulverized coal (and alumina) with carbon and chlorine in a high-temperature slurry reactor using a NaCl-AlClâ fused salt as the liquid medium. Carbochlorination has been demonstrated as a method for the recovery of aluminum, titanium and other metals from traditional ores

Dobbins

1986-01-01

329

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

330

SWING system, a nonaqueous rechargeable carbon\\/metal oxide cell  

Microsoft Academic Search

The SWING system contains an anode consisting of a carbonaceous material and a cathode made from lithium-containing transition metal oxides, which are either manganese-, nickel-, or cobalt-based. The cell operates with a liquid organic electrolyte and is cycled between 2.7 and 4.3 V, respectively, with an average charge\\/discharge voltage of about 3.5 V. Instead of metallic lithium, the cell is

R. Bittihn; R. Herr; D. Hoge

1993-01-01

331

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

PubMed

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

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

1992-01-01

332

Exposure characterization of metal oxide nanoparticles in the workplace.  

PubMed

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 various direct-reading and mass-based area and personal aerosol sampling was employed to measure exposure for various tasks. Workers in large facilities performing handling tasks had the highest mass concentrations for all analytes. However, higher mass concentrations occurred in medium facilities and during production for all analytes in area samples. Medium-sized facilities had higher particle number concentrations in the air, followed by small facilities for all particle sizes measured. Production processes generally had the highest particle number concentrations, particularly for the smaller particles. Similar to particle number, the medium-sized facilities and production process had the highest particle surface area concentration. TEM analysis confirmed the presence of the specific metal oxides particles of interest, and the majority of the particles were agglomerated, with the predominant particle size being between 0.1 and 1 ?m. The greatest potential for exposure to workers occurred during the handling process. However, the exposure is occurring at levels that are well below established and proposed limits. PMID:21936697

Curwin, Brian; Bertke, Steve

2011-10-01

333

Mode-selective detection of optical guided waves by integrated metal-oxide-metal structures.  

PubMed

We show that a metal-oxide-metal (Al-AlO(x)-Al) tunnel junction fabricated directly upon a planar ion-exchange glass waveguide can be used to detect the guided radiation through evanescent coupling. Carriers photogenerated in the electrode next to the guide can be internally photoemitted over the oxide barrier to generate a photocurrent. Because of the greater metallic absorption of TM-polarized modes, the process is polarization sensitive. 32-dB TM selectivity is achieved in a simple device. PMID:19741790

Soole, J B; Hughes, H P; Apsley, N

1987-07-01

334

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

335

Stress-driven formation of terraced hollow oxide nanorods during metal oxidation  

NASA Astrophysics Data System (ADS)

We report the formation of terraced hollow Cu2O nanorods upon oxidation of Cu(100) thin films at ~600 °C. Transmission electron microscopy and atomic force microscopy observations reveal that the oxide islands have an initially square pyramid shape that transits to an elongated nanorod shape and then to a terraced hollow nanorod morphology as the oxide growth proceeds. A mechanism based on the relaxation of interfacial epitaxial stress followed by the release of the bulk stress induced by the large volume expansion accompanying the conversion of metal into oxide is proposed to explain the pathway of the morphological evolution of this new oxide structure.

Zhou, Guangwen

2009-05-01

336

Reactive Evaporation of Metal Wire and Microdeposition of Metal Oxide Using Atmospheric Pressure Reactive Microplasma Jet  

NASA Astrophysics Data System (ADS)

We developed a safe technique without using a toxic gas source to deposit tungsten oxide on a localized specific area using an atmospheric pressure microplasma jet. In this technique, a consumable tungsten wire, inserted into a quartz nozzle for microplasma generation, was etched with an O2/Ar microplasma, and the resultant tungsten oxide was deposited on the substrate placed downstream. The process mechanism was determined by the detailed observation of the deposit and consumed wire surface after processing, and optical emission spectroscopy. This technique is expected to be utilized for the localized deposition of a variety of metal oxides by varying the kind of consumable metal wire.

Shimizu, Yoshiki; Bose, Arumugam Chandra; Mariotti, Davide; Sasaki, Takeshi; Kirihara, Kazuhiro; Suzuki, Tsunehisa; Terashima, Kazuo; Koshizaki, Naoto

2006-10-01

337

Anaerobic Nitrate-Dependent Metal BioOxidation  

Microsoft Academic Search

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

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

2007-01-01

338

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

339

Vapor growth of electrochromic thin films of transition metal oxides  

NASA Astrophysics Data System (ADS)

Mixed oxide films of transition metals gain considerable much attention due to their interesting optoelectronic properties. The low temperature chemical vapor growth processing of thin films of mixed W and Mo oxides is presented. The investigation is related to optimization of films structure and the related optoelectronic properties in dependence on the chemical vapor deposition (CVD) process parameters. Their electrochromic behavior and photoelectrode properties were studied.

Gesheva, K. A.; Ivanova, T.; Marsen, B.; Zollo, G.; Kalitzova, M.

2008-04-01

340

Oxidation stress evolution and relaxation of oxide film/metal substrate system  

NASA Astrophysics Data System (ADS)

Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

2012-07-01

341

Purpose-Built Anisotropic Metal Oxide Nanomaterials.  

National Technical Information Service (NTIS)

Large arrays of perpendicularly oriented anisotropic nanoparticles of ferric oxyhydroxide (Akaganeite, beta-FeOOH) and oxide (Hematite, alpha-Fe2O3) of typically 3-5 nm in diameter, self assembled as bundles of about 50 nm in diameter and of up to 1 micro...

L. Vayssieres J. Guo J. Nordgren

2001-01-01

342

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

343

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

PubMed

Transition metal oxides exhibit a rich collection of electronic properties and have many practical applications in areas such as catalysis and ultra-high-density magnetic data storage. Therefore the development of switchable molecular transition metal oxides has potential for the engineering of single-molecule devices and nanoscale electronics. At present, the electronic properties of transition metal oxides can only be tailored through the irreversible introduction of dopant ions, modifying the electronic structure by either injecting electrons or core holes. Here we show that a molybdenum(VI) oxide 'polyoxometalate' molecular nanocluster containing two embedded redox agents is activated by a metallic surface and can reversibly interconvert between two electronic states. Upon thermal activation two electrons are ejected from the active sulphite anions and delocalized over the metal oxide cluster cage, switching it from a fully oxidized state to a two-electron reduced state along with the concomitant formation of an S-S bonding interaction between the two sulphur centres inside the cluster shell. PMID:18654509

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

2008-04-01

344

Dextran templating for the synthesis of metallic and metal oxide sponges.  

PubMed

Silver or gold-containing porous frameworks have been used extensively in catalysis, electrochemistry, heat dissipation and biofiltration. These materials are often prepared by thermal reduction of metal-ion-impregnated porous insoluble supports (such as alumina and pumice), and have surface areas of about 1 m(2) g(-1), which is typically higher than that obtained for pure metal powders or foils prepared electrolytically or by infiltration and thermal decomposition of insoluble cellulose supports. Starch gels have been used in association with zeolite nanoparticles to produce porous inorganic materials with structural hierarchy, but the use of soft sacrificial templates in the synthesis of metallic sponges has not been investigated. Here we demonstrate that self-supporting macroporous frameworks of silver, gold and copper oxide, as well as composites of silver/copper oxide or silver/titania can be routinely prepared by heating metal-salt-containing pastes of the polysaccharide, dextran, to temperatures between 500 and 900 degrees C. Magnetic sponges were similarly prepared by replacing the metal salt precursor with preformed iron oxide (magnetite) nanoparticles. The use of dextran as a sacrificial template for the fabrication of metallic and metal oxide sponges should have significant benefits over existing technologies because the method is facile, inexpensive, environmentally benign, and amenable to scale-up and processing. PMID:12764358

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

2003-06-01

345

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

SciTech Connect

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

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

1994-10-01

346

Chromatographic separations and recovery of lead ions from a synthetic binary mixtures of some heavy metal using cation exchange resin.  

PubMed

A simple solid phase extraction procedure on cation exchange resin Purolite C100 is presented. The procedure based on a column technique for separation and recovery of lead ions from synthetic binary mixtures. Equilibrium distribution coefficient, k(d) for the different metal ions such as Al(III), Fe(III), Ba(II) and Pb(II) in the presence of nitric acid and ammonium acetate solutions of variable concentrations was determined at 25 degrees C. The values of separation factor, alpha were evaluated. Quantitative separation of lead ions from a synthetic binary mixtures are based on the fact that ammonium acetate is a good elute for lead ions but fails to elute the other cations. PMID:19136204

Badawy, N A; El-Bayaa, A A; Abdel-Aal, A Y; Garamon, S E

2009-07-30

347

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

348

Dissolution of metal and metal oxide nanoparticles in aqueous media.  

PubMed

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

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

2014-08-01

349

A collision model for fume formation in metal oxidation  

SciTech Connect

During the oxidation of copper at high temperatures, two simultaneous mechanisms are observed in the hot stage environmental scanning electron microscope: the nucleation and growth of solid cuprous oxide crystals and the formation of a solid fume composed of very small copper and copper oxide particles. A collision model for fume formation in metal oxidation is presented. By calculating th collision frequency between evaporated copper atoms and oxygen molecules in the gas phase, the amount of fume formed can be estimated. Although the effect of Van der Waals forces between particles has not been quantified, the temperature difference between the two gases was taken into account and yielded a multiplying factor of 4 in the collision frequency for copper oxidation at 950/sup 0/C. Unoxidized copper particles were formed from unsuccessful elastic collisions between Cu(v) and O/sub 2/. These copper particles are composed of interpenetrating icosohedra and possess a high crystalline perfection.

Raynaud, G.M.; Rapp, R.A.

1984-03-01

350

Fundamental principles of metal oxide based chemical sensors  

Microsoft Academic Search

Metal oxides based chemical sensors are devices that translate the changes in the concentration of gaseous chemical species into electrical signals, generally changes of resistance\\/conductance. A sensor element normally comprises the following parts: a) Sensitive layer deposited over a b) Substrate provided with c) Electrodes for the measurement of the electrical characteristics. The device is generally heated by its own

Nicolae Barsan

2002-01-01

351

Oxidation resistant filler metals for direct brazing of structural ceramics  

DOEpatents

A method of joining ceramics and metals to themselves and to one another is described using essentially pure trinickel aluminide and trinickel aluminide containing small amounts of carbon. This method produces strong joints that can withstand high service temperatures and oxidizing environments.

Moorhead, Arthur J. (Knoxville, TN)

1986-01-01

352

CMOS array design automation techniques. [metal oxide semiconductors  

NASA Technical Reports Server (NTRS)

A low cost, quick turnaround technique for generating custom metal oxide semiconductor arrays using the standard cell approach was developed, implemented, tested and validated. Basic cell design topology and guidelines are defined based on an extensive analysis that includes circuit, layout, process, array topology and required performance considerations particularly high circuit speed.

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

1975-01-01

353

Merox and Related Metal Phthalocyanine Catalyzed Oxidation Processes  

Microsoft Academic Search

Alkyl and aromatic mercaptans are among important organic sulfur compounds distributed in petroleum products. The mercaptans cause foul odor and are corrosive toward metals. In addition, mercaptans may cause oxidative deterioration as well as inhibit the performance of various additives (TEL, antioxidants) in finished products. Therefore, it is necessary to remove them, either by extractive processes or by converting them

B. Basu; S. Satapathy; A. K. Bhatnagar

1993-01-01

354

High-temperature Complementary Metal Oxide Semiconductors (CMOS)  

NASA Technical Reports Server (NTRS)

The results of an investigation into the possibility of using complementary metal oxide semiconductor (CMOS) technology for high temperature electronics are presented. A CMOS test chip was specifically developed as the test bed. This test chip incorporates CMOS transistors that have no gate protection diodes; these diodes are the major cause of leakage in commercial devices.

Mcbrayer, J. D.

1981-01-01

355

Density-related properties of metal oxide films  

Microsoft Academic Search

The density of the material in a deposited film determines many important film properties, for example hardness and abrasions resistance, adherence to the substrate, refractive index, film stress, flatness and film permeation. Chemical compound films like metal oxides, some nitrides and oxynitrides are mainly produced by reactive PVD processes. The energy input into the growing film strongly influence the density

Hans K. Pulker; Stefan S. Schlichtherle

2004-01-01

356

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

357

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

358

Investigation of lithium intercalation metal oxides for thermal batteries  

Microsoft Academic Search

An investigation of new, high voltage cathode materials for thermal batteries included a group of lithium intercalation metal oxide compounds. The authors present the experimental results of this high voltage cathode study and discuss the applicability of these materials to thermal batteries. The intent of this research work was to discover new positive electrodes that by virtue of higher discharge

M.-E. Bolster; R. J. Staniewicz

1990-01-01

359

Detection mechanism of metal oxide gas sensor under UV radiation  

Microsoft Academic Search

The effect of ultraviolet radiation on the sensing mechanism of polycrystalline metal oxide gas sensor has been studied analytically. The model used to describe the sensing mechanism is based on the combination of the neck mechanism and grain boundary mechanism. We found that increasing the UV radiation flux density increases the conductivity of the film by decreasing the resistance. It

Sunita Mishra; C. Ghanshyam; N. Ram; R. P. Bajpai; R. K. Bedi

2004-01-01

360

Electric field measurements around a metal oxide surge arrester  

Microsoft Academic Search

Aim of the current work is the experimental study of the electric field distribution around a medium voltage metal oxide gapless polymeric housing surge arrester, since the study and the knowledge of the electric field around an arrester can be useful for diagnostic tests and design procedures. The measurements were carried out, using two appropriate calibrated field meters. The results

C. A. Spanias; C. A. Christodoulou; I. F. Gonos; I. A. Stathopulos

2010-01-01

361

Ionizing Radiation Induced Catalysis on Metal Oxide Particles  

Microsoft Academic Search

This project was conducted to determine if ionizing radiation could be used to catalytically destroy organics over semiconducting metal oxide particles. We focused primarily on the destruction of organic chelating agents, such as EDTA, which are known to hamper the separation of radionucleii (such as Sr or Am) from tank waste using current ion exchange methods. Our objective was to

Michael A

1999-01-01

362

The Extraction of Metals from Their Oxides and Sulphides.  

ERIC Educational Resources Information Center

Briefly describes the application of thermodynamics (system at equilibrium) to the study of the extraction of metals from their oxides (dynamic situation). It is more relevant to study the temperature variation of the equilibrium constants of the reaction than to study the free energy approach. (Author/SK)

Price, Alun H.

1980-01-01

363

Perspectives on the metallic interconnects for solid oxide fuel cells.  

PubMed

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

Zhu, Wei-Zhong; Yan, Mi

2004-12-01

364

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

Microsoft Academic Search

A process and apparatus for generating elemental sulfur and re-usable metal oxide from spent metal-sulfur compound. Spent metal-sulfur compound is regenerated to re-usable metal oxide by moving a bed of spent metal-sulfur compound progressively through a single regeneration vessel having a first and second regeneration stage and a third cooling and purging stage. The regeneration is carried out and elemental

Raul E. Ayala; Eli Gal

1995-01-01

365

Oxidation of noble metal alloys for porcelain veneer crowns.  

PubMed

It has been found that oxide-forming elements in the alloy are important for the blood strength between the metal and the procelain. The purpose of the present investigation was to study the formation of oxides during pretreatment and firing of porcelain. Four commerically available Ceramo-Metal alloys were studied. The specimens were heated at 980 degrees C for five hours in air, and the weight was continuously recorded. In addition porcelain was fired on to the alloys. Metallographic examinations were conducted on both oxidized and fired speciments. The weight gain data also indicated an increased oxygen uptake with a larger amount of oxidizable elements in the alloy. Most of the oxygen gain and time indicated that the oxygen uptake was diffusion controlled. The weight gain data also indicated an increased oxygen uptake with larger amount of oxidizable elements in the alloy. Most of the oxygen in the oxidize alloys was located as oxide along grain boundaries in the metal. PMID:398663

Espevik, S; Oilo, G; Lodding, A

1979-01-01

366

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

367

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

368

A gaussian-based formalism for the representation of free energy as a function of composition of binary metallic solutions  

NASA Astrophysics Data System (ADS)

A formalism is presented for representing with precision the isothermal free energy of binary metallic systems as a function of composition. It involves the addition of two terms describing excess free energy. The first term is a modified Gaussian term similar in form to the excess stability function proposed by Darken1 superimposed on normally asymmetric forms of regular solution behavior, i.e., the Krupkowski or the subregular solution equations. Most of the present work is concerned with the use of the Gaussian plus subregular model since this can more easily be tested by using the tabulated data of Hultgren et al.2.

Esdaile, J. D.

1982-06-01

369

Oxides in metal fixed points of the ITS-90  

NASA Astrophysics Data System (ADS)

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

Fahr, Martin; Rudtsch, Steffen

2009-10-01

370

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

371

Study of small metal oxide clusters using anion photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

We report photoelectron spectra of size selected clusters of Si_xOy , Al_xOy and Mg_xOy by using anion photoelectron spectroscopy. Oxide clusters are environmentally important species due to their role in ground transport of waste materials. The SixOy series of clusters can be viewed as the sequential oxidation of the Si3 (C_2V), Si3 (D_2h) and Si3 (D_3h) clusters, respectively. For the Si_3Oy series, detailed calculations have been carried out and yielded definitive structures for these clusters. Each oxygen atom is shown to break a Si-Si bond and form two Si-O bonds, and further oxidation eventually leads to the formation of SiO4 tetrahedra. This is shown to be quite similar to the initial oxidation of bulk Si surfaces. Based on this knowledge, we propose probable structures for the larger silicon oxide clusters, Si_4Oy and Si_5O_y. Preliminary data on Al_xOy and Mg_xOy clusters are also presented which show the same sequential oxidation behavior. These clusters may provide interesting models for the oxidation of the bulk metal and can be used to test different theoretical techniques intended to treat larger oxide systems.

Desai, Sunil R.; Nicholas, John B.; Colson, Steven D.; Wu, Hongbin; Wang, Lai-Sheng

1996-03-01

372

Transition metal dioxygen complexes as intermediates in homogeneous catalytic oxidations  

NASA Astrophysics Data System (ADS)

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

Simándi, Lászlò I.

373

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

374

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

375

Direct electroplated metallization on indium tin oxide plastic substrate.  

PubMed

Looking foward to the future where the device becomes flexible and rollable, indium tin oxide (ITO) fabricated on the plastic substrate becomes indispensable. Metallization on the ITO plastic substrate is an essential and required process. Electroplating is a cost-effective and high-throughput metallization process; however, the poor surface coverage and interfacial adhesion between electroplated metal and ITO plastic substrate limits its applications. This paper develops a new method to directly electroplate metals having strong adhesion and uniform deposition on an ITO plastic substrate by using a combination of 3-mercaptopropyl-trimethoxysilane (MPS) self-assembled monolayers (SAMs) and a sweeping potential technique. An impedance capacitive analysis supports the proposed bridging link model for MPS SAMs at the interface between the ITO and the electrolyte. PMID:24380434

Hau, Nga Yu; Chang, Ya-Huei; Huang, Yu-Ting; Wei, Tzu-Chien; Feng, Shien-Ping

2014-01-14

376

Effects of sputtered metal oxide films on the ceramic-to-metal bond.  

PubMed

The application of a thin oxide film is seen as a method of improving the ceramic-to-metal bond. Using sputter coating to form oxide films allows control of its thickness. The thickness of the oxide layer can also be controlled by sputter coating. Films produced by sputtering, in themselves, have superior bond strengths in that the high-energy levels that are used in the technique drive the coating material into the atomic lattice of the substrate material (dental gold). Remaining to be determined are optimum film thickness and the oxide to be used. However, the present study opens a field of study showing promise of improving porcelain-to-metal bonding in dental restoration. PMID:3908655

Bullard, J T; Dill, R E; Marker, V A; Payne, E V

1985-12-01

377

Transition-Metal-Catalyzed Oxidation of Metallic Sn in NiO/SnO2 Nanocomposite.  

PubMed

It is well accepted that metallic tin as a discharge (reduction) product of SnOx cannot be electrochemically oxidized below 3.00?V versus Li(+) /Li(0) due to the high stability of Li2 O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni2 SnO4 and NiO/SnO2 nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to SnO2 below 3.00?V. As a result, the reversible lithium-storage capacities of the nanocomposite reach 970?mAh?g(-1) or above, much higher than the theoretical capacity (ca. 750?mAh?g(-1) ) of SnO2 , NiO, or their composites. These findings extend the well-known electrochemical conversion reaction to non-transition-metal compounds and may have important applications, for example, in constructing high-capacity electrode materials and efficient catalysts. PMID:24648283

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

2014-04-25

378

Alkali metal ion-selective electrodes based on relevant alkali metal ion doped manganese oxides  

Microsoft Academic Search

Potentiometric properties of manganese oxides doped with alkali metal ions (Na+, K+, Rb+ and Cs+), which were prepared by heating mixed solutions (starting solution) of each alkali metal and Mn2+ ions, were examined. Electrodes based on mixed phases of Nao44MnO2\\/Mn2O3 and hollandite KMn8O16\\/M2O3 found by X-ray powder diffraction (XRD) exhibited Na+- and K+-selective responses with a near-Nernstian slope, respectively, when

Yukinori Tani; Yoshio Umezawa

1998-01-01

379

Slip Casting and Extruding Shapes of Rhenium with Metal Oxide Additives. 1: Feasibility Demonstration.  

National Technical Information Service (NTIS)

The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the r...

F. A. Barr R. J. Page

1986-01-01

380

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

381

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

Microsoft Academic Search

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

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

1996-01-01

382

Monolayered nanodots of transition metal oxides.  

PubMed

Monolayered nanodots of titanium, tungsten, and manganese oxides were obtained by exfoliation of the nanocrystals through aqueous solution processes at room temperature. The precursor nanocrystals of the layered compounds, such as sodium titanate (Na(0.80)Ti(1.80)?(0.2)O4·xH2O, ?: vacancy (x < 1.17)), cesium tungstate (Cs4W11O35·yH2O (y < 10.5)), and sodium manganate (Na0.44MnO2·zH2O (z < 0.85)), were synthesized in an aqueous solution. These nanocrystals of the layered compounds were delaminated into the monolayered nanodots through introduction of a bulky organic cation in the interlayer space. The resultant monolayered nanodots of the titanate and tungstate 2-5 nm in lateral size showed a remarkable blueshift of the bandgap energies. The calculation studies supported the blueshifts of the bandgap energies. The results suggest that syntheses of monolayered nanodots can expand the tuning range of the properties based on size effect. The present approaches for generation of ultrathin tiny objects can be applied to a variety of nanomaterials. PMID:23441590

Nakamura, Keisuke; Oaki, Yuya; Imai, Hiroaki

2013-03-20

383

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

NASA Astrophysics Data System (ADS)

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

Xu, Ye

384

Metal/oxide interfacial reactions: Oxidation of metals on SrTiO3 (100) and TiO2 (110).  

PubMed

We studied chemical reactions between ultrathin metal films (Al, Cr, Fe, Mo) and single-crystal oxides (SrTiO3 (100), TiO2 (110)) with X-ray photoelectron spectroscopy (XPS). The work function of the metal and the electron density in the oxide strongly influence the reaction onset temperature (T(RO)), where metal oxidation is first observed, and the rate of metal oxidation at the metal/oxide interfaces. The Fermi levels of the two contacting phases affect both the space charges formed at the interfaces and the diffusion of ionic defects across the interfaces. These processes, which determine metal oxidation kinetics at relatively low temperatures, can be understood in the framework of the Cabrera-Mott theory. The results suggest that the interfacial reactivity is tunable by modifying the Fermi level (E(F)) of both contacting phases. This effect is of great technological importance for a variety of devices with heterophase boundaries. PMID:16852436

Fu, Qiang; Wagner, Thomas

2005-06-16

385

Binary and Ternary Metal Complexes of Uridine and Thermodynamic Quantities Associated with the Interaction of Uridine with Bivalent Metal ions in Solution  

Microsoft Academic Search

Formation of binary and ternary complexes of Cu(II), Ni(II), Zn(II), Co(II), Mn(II), Mg(II), Ca(II), metal ions with uridine as a primary ligand and 2,2?-bipyridyl, 1,10-phenanthroline and 5-sulphosalicylic acid as secondary ligands was studied by a potentiometric technique at 15°, 25°, 35° and 45°C and 0.10 M (KNO3) ionic strength. The ternary complex formation was found to take place in a

Badar Taqui Khan; R. Madhusudhan Raju; S. M. Zakeeruddin

1987-01-01

386

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

387

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

388

A low-voltage alterable EEPROM with Metal-Oxide-Nitride-Oxide-Semiconductor \\/MONOS\\/ structures  

Microsoft Academic Search

Theoretical and experimental investigations to obtain lower voltage Electrically Erasable and Programmable ROM's (EEPROM's) than conventional devices have been performed. The scaled-down Metal-Oxide-Nitride-Oxide semiconductor (MONOS) structure is proposed to realize an extremely low-voltage programmable device. The proposed scaled down MONOS devices enjoy several advantages over MNOS devices, e.g., enlargement of the memory window, elimination of degradation phenomena, and drastic improvement

E. Suzuki; K. Ishii; Y. Hayashi; H. Hiraishi

1983-01-01

389

Direct tunneling hole currents through ultrathin gate oxides in metal-oxide-semiconductor devices  

Microsoft Academic Search

We present a physical model to calculate the direct tunneling hole current through ultrathin gate oxides from the inversion layer of metal-oxide-semiconductor field-effect transistors. A parametric self-consistency method utilizing the triangular well approximation is used for the electrostatics of the inversion layer. For hole quantization in the inversion layer, an improved one-band effective mass approximation, which is a good approximation

Y. T. Hou; M. F. Li; Y. Jin; W. H. Lai

2002-01-01

390

Explanation for the oxide thickness dependence of breakdown characteristics of metal-oxide-semiconductor structures  

Microsoft Academic Search

Experimental evidence is presented showing that the thickness dependence observed for charge-to-breakdown measurements of very thin oxide layers in metal-oxide-semiconductor structures is correlated with that for the reduction in total generated microscopic defects necessary to induce destruction. These results are discussed in relationship to the formation of paths connecting some of these defects from the cathode to the anode at

D. J. DiMaria

1997-01-01

391

Boron diffusion through pure silicon oxide and oxynitride used for metal-oxide-semiconductor devices  

Microsoft Academic Search

We studied boron diffusion in thin silicon oxides including pure SiO2 and oxynitride that are used for metal-oxide semiconductor transistors. We measured the boron penetration using secondary ion mass spectroscopy. By comparing simulated and experimental results, we found that the boron diffusivity in pure SiO2, D(sub PO), is 3.96 x 10(exp -2)exp (-3.65 eV\\/kT) cm(exp 2)\\/s, and that in oxynitride

Takayuki Aoyama; Kunihiro Suzuki; Hiroko Tashiro; Yaka Tada; Tatsuya Yamazaki; Yoshihiro Armoto; Takashi Ito

1993-01-01

392

Temperature dependence of metal-nitride-oxide-silicon currents at constant oxide fields  

Microsoft Academic Search

The steady-state current through the double dielectric of metal-nitride-oxide-silicon capacitors on p-silicon substrate was measured as a function of temperature for several fixed fields in the silicon oxide of a polarity-promoting hole flow from the silicon. It is shown that the availability of empty recipient trap states for holes tunneling from the silicon into the nitride controls the current. The

A. Fedotowsky; K. Lehovec; Y. K. Park

1980-01-01

393

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

394

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

395

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

396

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

397

Understanding Organic Film Behavior on Alloy and Metal Oxides  

PubMed Central

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

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

2010-01-01

398

Carbon monoxide oxidation over three different oxidation states of copper: Metallic copper, copper (I) oxide, and copper (II) oxide - a surface science and kinetic study  

Microsoft Academic Search

Reaction rates and activation energies were measured for carbon monoxide oxidation over thin films of metallic copper, copper (I) oxide, and copper (II) oxide grown on graphite. The reactions were carried out in the temperature range 200-350[degrees]C at total pressures of 100 Torr. Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the growth and oxidation

G. G. Jernigan; G. A. Somorjai

1994-01-01

399

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

400

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

401

Behavior of metal oxide nanoparticles in natural aqueous matrices  

Microsoft Academic Search

The increasing use of nanomaterials in consumer products that are exposed to environmental media has led to a need to understand their fate and transport. In particular, metal oxide (MeO) nanoparticles, such as TiO2, ZnO and CeO2, are increasingly incorporated into a wide range of products, from sunscreens to paints and other coatings, and catalysts. With regard to their transport,

A. A. Keller; D. Zhou; H. Wang

2009-01-01

402

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

403

Emission characteristics of metal-oxide-semiconductor electron tunneling cathode  

Microsoft Academic Search

We have fabricated a metal-oxide-semiconductor (MOS) electron tunneling cathode with ultrathin SiOâ and examined the emission characteristics. We found that the emission occurred from an entire gate area by electron tunneling through the potential barrier in the MOS diode and the emission current was 0.7% of the total current flowing through the diode. The emission was also found to be

Kuniyoshi Yokoo; Hiroshi Tanaka; Shinji Sato; Junichi Murota; Shoichi Ono

1993-01-01

404

Transport of metal oxide nanoparticles in saturated porous media  

Microsoft Academic Search

The behavior of four types of untreated metal oxide nanoparticles in saturated porous media was studied. The transport of Fe3O4, TiO2, CuO, and ZnO was measured in a series of column experiments. Vertical columns were packed with uniform, spherical glass beads. The particles were introduced as a pulse suspended in aqueous solutions and breakthrough curves at the outlet were measured

Tal Ben-Moshe; Ishai Dror; Brian Berkowitz

2010-01-01

405

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

406

Metal-insulator phase transition in vanadium oxides films  

Microsoft Academic Search

Vanadium oxide films (VO2) are of a typical phase transition ranging between metal phase to a semi-conducting phase. The theoretical metamorphose temperature of VO2 is around 340K (67°C). This transition temperature is mostly governed by the deposition method in which the film was made, and the film's composition. Optical and electrical properties of VO2 films are dramatically changed during this

G. Golan; A. Axelevitch; B. Sigalov; B. Gorenstein

2003-01-01

407

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

408

Nanomechanical switches based on metal-insulator-metal capacitors from a standard complementary-metal-oxide semiconductor technology  

NASA Astrophysics Data System (ADS)

We report experimental demonstrations of contact-mode nano-electromechanical switches obtained using a capacitor module based on metal-insulator-metal configuration of a standard commercial complementary metal oxide semiconductor technology. The developed 2 terminals Titanium Nitride switches operate at low voltages (˜10 V) thanks to its small gap (27 nm), showing an excellent ION/IOFF ratio (104) and abrupt behavior (5 mV/decade, one decade of current change is achieved with a 5 mV voltage variation). A switch configuration is also presented where using two electrodes three different contact mode states can be obtained, adding functionalities to mechanical switches configurations.

Muñoz-Gamarra, J. L.; Uranga, A.; Barniol, N.

2014-06-01

409

Amorphous stability of HfO 2 based ternary and binary composition spread oxide films as alternative gate dielectrics  

NASA Astrophysics Data System (ADS)

A ternary alloyed thin film library of HfO 2-Y 2O 3-Al 2O 3 was grown on a Si(1 0 0) substrate in a few hours by a new pulsed laser deposition (PLD) system installed with a masking and substrate rotating scheme. This specially designed combinatorial ternary composition spread method enabled us to fabricate continuous ternary and binary composition spread film libraries. It is noteworthy that the library made by this system is addressable; each film composition covers the full range (from 0 to 100%) and can be directly correlated with the film location in the ternary and binary phase diagram. Rapid permittivity measurement on the film libraries was carried out by a scanning microwave microscope, while the crystal structure was by a combinatorial X-ray diffractometer (XRD). The (HfO 2) 6(Y 2O 3) 1(Al 2O 3) 3 ternary composition area in an amorphous phase was found to have a dielectric constant higher than HfO 2-Y 2O 3 binary area. This ternary oxide is promising as amorphous gate dielectric material.

Hasegawa, K.; Ahmet, P.; Okazaki, N.; Hasegawa, T.; Fujimoto, K.; Watanabe, M.; Chikyow, T.; Koinuma, H.

2004-02-01

410

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

SciTech Connect

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

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

2007-03-15

411

Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles  

NASA Astrophysics Data System (ADS)

A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

2014-06-01

412

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

2009-04-01

413

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

414

Magnetism in transition-metal-substituted semiconducting oxides  

NASA Astrophysics Data System (ADS)

The nascent field of spintronics requires materials that exhibit room-temperature ferromagnetism while retaining their semiconducting properties. A clever strategy for creating these materials is by substituting magnetic transition metals onto the cation sites of commonly used binary semiconductors in order to incorporate magnetic property (e.g. Mn-substituted GaAs). A materials system of great interest is transition-metal substituted ZnO, which was predicted by Dietl and co-workers [1] to be a room temperature ferromagnet with manganese substitution and hole doping. Despite a great deal of effort in preparing thin films of transition-metal substituted ZnO, there has not been reproducible evidence of ferromagnetism in this system; Curie temperatures and magnetic moments vary significantly between studies. In our work, bulk transition metal substituted ZnO samples were prepared and characterized in order to accurately determine their properties. We find no evidence for ferromagnetic behavior in either the Zn1-xCo xO nor the Zn1-xMn xO systems; rather the dominant nearest-neighbor interactions are antiferromagnetic. A similar behavior is observed in nanoparticulate analogs of the bulk materials. Along with substituted ZnO, the 'end-member' of the Zn1-xCox O system, novel wurzite CoO was also prepared and studied. Finally, solid solutions of a dilute ferrimagnetic semiconductor system, iron-substituted ZnGa2O4, were prepared and found to possess long-range magnetic ordering ferromagnetic hysteresis at low temperatures. Optical spectroscopy indicates that the iron substitution does not greatly alter the position of the band edge, hence maintaining the semiconducting properties. Such promising results suggest that dilute ferrimagnetic semiconductors, which do not require conduction electrons to induce magnetism, are worthy of further investigation.

Risbud, Aditi S.

415

Quantitative determination of the number of active surface sites and the turnover frequencies for methanol oxidation over metal oxide catalysts  

Microsoft Academic Search

A detailed study of the methanol chemisorption and oxidation processes on oxide surfaces allowed the development of a method to quantify the number of surface active sites (Ns) of metal oxide catalysts. In situ infrared analysis during methanol adsorption showed that molecular methanol and surface methoxy species are co-adsorbed on an oxide surface at room temperature, but only surface methoxy

Laura E Briand; William E Farneth; Israel E Wachs

2000-01-01

416

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

EPA Science Inventory

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

417

[Transition metals and nitric oxide production in human endothelial cells].  

PubMed

The bioavailability of endothelial nitric oxide (NO) is regulated by transition metals but their mechanisms of action on NO synthesis and degradation are not clearly understood. Using differential pulse amperometry and NO microelectrodes, local NO concentration was measured at the surface of cultured human umbilical vein endothelial cells (HUVECs) stimulated by histamine or thrombin in the presence of transition metal chelators. The agonist-activated NO release required both extracellular Ca2+ and transition metals. In the presence of 1 mM external Ca2+, a low concentration of EGTA (5 microM) inhibited by 40% the NO release from stimulated HUVECs. In the presence of extracellular L-arginine, the inhibitory effect of EGTA was even more marked and, in its absence, it was suppressed by adding exogenous superoxide dismutase. The decrease in NO release induced by the copper chelators, cuprizone and DETC, suggests that extracellular traces of Cu2+ could regulate NO availability. PMID:11212498

David-Dufilho, M; Privat, C; Brunet, A; Richard, M J; Devynck, J; Devynck, M A

2001-01-01

418

Ellipsometric study of oxide films formed on LDEF metal samples  

NASA Technical Reports Server (NTRS)

The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the Long Duration Exposure Facility (LDEF) were studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out, with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, Ni, Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000 A. The 410 A thick film of Al2O3 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin non-porous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.

Franzen, W.; Brodkin, J. S.; Sengupta, L. C.; Sagalyn, P. L.

1992-01-01

419

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

Microsoft Academic Search

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

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

2011-01-01

420

Effects of metal oxide nanoparticles on soil properties.  

PubMed

In recent years the behavior and properties of nanoparticles released to the environment have been studied extensively to better assess the potential consequences of their broad use in commercial products. The fate, transport and mobility of nanoparticles in soil were shown to be strongly dependent on environmental conditions. However, little is known about the possible effects of nanoparticles on soil chemical, physical and biological properties. In this study, two types of metal oxide nanoparticles, CuO and Fe(3)O(4) were mixed into two types of soil and the effects of the nanoparticles on various soil properties were assessed. Metal oxide nanoparticles were shown previously to catalyze the oxidation of organic pollutants in aqueous suspensions, and they were therefore expected to induce changes in the organic material in the soil, especially upon addition of an oxidant. It was found that the nanoparticles did not change the total amount of organic materials in the soil or the total organic carbon in the soil extract; however, three-dimensional fluorescence spectroscopy demonstrated changes in humic substances. The nanoparticles also affected the soil bacterial community composition, based on denaturing gradient gel electrophoresis (DGGE) fingerprinting, but had little impact on the macroscopic properties of the soil. PMID:23040650

Ben-Moshe, Tal; Frenk, Sammy; Dror, Ishai; Minz, Dror; Berkowitz, Brian

2013-01-01

421

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

2012-01-01

422

Thermodynamic properties of some metal oxide-zirconia systems  

NASA Technical Reports Server (NTRS)

Metal oxide-zirconia systems are a potential class of materials for use as structural materials at temperatures above 1900 K. These materials must have no destructive phase changes and low vapor pressures. Both alkaline earth oxide (MgO, CaO, SrO, and BaO)-zirconia and some rare earth oxide (Y2O3, Sc2O3, La2O3, CeO2, Sm2O3, Gd2O3, Yb2O3, Dy2O3, Ho2O3, and Er2O3)-zirconia system are examined. For each system, the phase diagram is discussed and the vapor pressure for each vapor species is calculated via a free energy minimization procedure. The available thermodynamic literature on each system is also surveyed. Some of the systems look promising for high temperature structural materials.

Jacobson, Nathan S.

1989-01-01

423

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

2004-01-20

424

The Development of Metal Oxide Chemical Sensing Nanostructures  

NASA Technical Reports Server (NTRS)

This paper discusses sensor development based on metal oxide nanostructures and microsystems technology. While nanostructures such as nanowires show significant potential as enabling materials for chemical sensors, a number of significant technical challenges remain. This paper discusses development to address each of these technical barriers: 1) Improved contact and integration of the nanostructured materials with microsystems in a sensor structure; 2) Control of nanostructure crystallinity to allow control of the detection mechanism; and 3) Widening the range of gases that can be detected by fabricating multiple nanostructured materials. A sensor structure composed of three nanostructured oxides aligned on a single microsensor has been fabricated and tested. Results of this testing are discussed and future development approaches are suggested. It is concluded that while this work lays the foundation for further development, these are the beginning steps towards realization of repeatable, controlled sensor systems using oxide based nanostructures.

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

2008-01-01

425

Lithium metal oxide electrodes for lithium cells and batteries  

DOEpatents

A lithium metal oxide positive electrode for a non-aqueous lithium cell is disclosed. The cell is prepared in its initial discharged state and has a general formula xLiMO.sub.2.(1-x)Li.sub.2M'O.sub.3 in which 0oxidation state and with at least one ion being Mn or Ni, and where M' is one or more ion with an average tetravalent oxidation state. Complete cells or batteries are disclosed with anode, cathode and electrolyte as are batteries of several cells connected in parallel or series or both.

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

2008-12-23

426

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

427

Tailor-made oxide architectures attained by molecularly permeable metal-oxide organic hybrid thin films.  

PubMed

Tailor-made metal oxide (MO) thin films with controlled compositions, electronic structures, and architectures are obtained via molecular layer deposition (MLD) and solution treatment. Step-wise formation of permeable hybrid films by MLD followed by chemical modification in solution benefits from the versatility of gas phase reactivity on surfaces while maintaining flexibility which is more common at the liquid phase. PMID:24993109

Sarkar, Debabrata; Taffa, Dereje Hailu; Ishchuk, Sergey; Hazut, Ori; Cohen, Hagai; Toker, Gil; Asscher, Micha; Yerushalmi, Roie

2014-07-17

428

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

429

Unveiling the complex electronic structure of amorphous metal oxides  

PubMed Central

Amorphous materials represent a large and important emerging area of material’s science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today’s integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5–10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.

?rhammar, C.; Pietzsch, Annette; Bock, Nicolas; Holmstrom, Erik; Araujo, C. Moyses; Grasjo, Johan; Zhao, Shuxi; Green, Sara; Peery, T.; Hennies, Franz; Amerioun, Shahrad; Fohlisch, Alexander; Schlappa, Justine; Schmitt, Thorsten; Strocov, Vladimir N.; Niklasson, Gunnar A.; Wallace, Duane C.; Rubensson, Jan-Erik; Johansson, Borje; Ahuja, Rajeev

2011-01-01

430

Development of structure-activity relationship for metal oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions.Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01533e

Liu, Rong; Zhang, Hai Yuan; Ji, Zhao Xia; Rallo, Robert; Xia, Tian; Chang, Chong Hyun; Nel, Andre; Cohen, Yoram

2013-05-01

431

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

PubMed

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

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

2010-11-15

432

Mixed-metal oxide nanopowders for structural and photonic applications  

NASA Astrophysics Data System (ADS)

This dissertation uses liquid feed flame spray pyrolysis (LF-FSP) to synthesize and process mixed-metal nano oxides with well-defined structural and photonic properties. LF-FSP combusts a metal oxide precursor solution and oxygen aerosol to produce nanoparticles with the same metal ratio as the precursor solution. The ability to tailor compositions and morphologies of the resultant nanopowders through the use of multiple liquid based metal-oxide precursors lends itself to combinatorial studies of composition and morphology, which is highly useful in property optimization. We first chose to investigate the effects of different aluminum oxide precursors on the morphology of the resulting alumina nanoparticles. This study showed that the metal ligand strongly influences the particle morphology based on the mechanisms of ligand decomposition. We successfully applied flame spray pyrolysis for the first time to synthesize combinatorially MgO:Al 2O3 with MgO concentrations in the range 0.005--50 mol%. The investigation provide a complete picture of the physical phase structure and associated native defect content over the full concentration range allowed by thermodynamics, but controlled by kinetics resulting in novel metastable phase formation and optimization the novel UV emission behavior. To demonstrate how the choice of ligand depends on the desired property, two different ceria ligands were used to alter the ceria doping mechanism of the alumina nanoparticles. The use of combustible, cerium propionate increased in the theta-alumina phase stability through increased dopant homogeneity and nano-domain development compared to the nitrite derived nanopowder. While the inorganic, cerium nitrate appears to favor Ce3+ in the Ce3+/4+ redox couple providing novel incoherent lasing. Previous combinatorial upconversion emission studies on co-doped yttria (Y0.86Yb0.11Er0.03)2O3 provided nanopowders that could be densified to give the first example of a submicron transparent upconversion ceramic sintered at 1400°C with unprecedented dopant concentrations of > 10 mol% allowing new photonic application to be realized. In addition, these sintering studies demonstrated the exceptional sinterability of LF-FSP powders. In toto, this dissertation demonstrates many experimental firsts that have only been predicted previously; including, the furthest extension of the magnesium spinel phase field, incoherent lasing, submicron transparent upconversion ceramics and reduced sintering parameters due to unaggregated nanocrystalline powders.

Hinklin, Thomas Ray

433

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

NASA Astrophysics Data System (ADS)

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

Sharma, Ramesh

434

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

PubMed

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

Guo, Limin; Arafune, Hiroyuki; Teramae, Norio

2013-04-01

435

Magnetic preferential orientation of metal oxide superconducting materials  

DOEpatents

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

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

1990-07-17

436

Magnetic preferential orientation of metal oxide superconducting materials  

DOEpatents

A superconductor comprised of a polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0metal oxide material permits the use of an applied magnetic field to orient the individual crystals when in the superconducting state to substantially increase current transport between adjacent grains. In another embodiment, the anisotropic paramagnetic susceptibility of rare-earth ions substituted into the oxide material is made use of as an applied magnetic field orients the particles in a preferential direction. This latter operation can be performed with the material in the normal (non-superconducting) state.

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

1990-01-01

437

Nanocontact resistance and structural disorder induced resistivity variation in metallic metal-oxide nanowires  

Microsoft Academic Search

Several systems of metallic metal-oxide nanowires (NWs), including pure RuO2 and as-implanted and annealed Ru0.98Cu0.02O2 and Ru0.93Cu0.07O2 NWs, have been employed in two-probe electrical characterizations by using a transmission electron microscope–scanning tunneling microscope technique with a gold tip. Thermal, mechanical, and electron beam exposing treatments are consecutively applied to reduce the electrical contact resistance, generated from the interface between the

Y F Lin; Z Y Wu; K C Lin; C C Chen; W B Jian; F R Chen; J J Kai

2009-01-01

438

Nanocontact resistance and structural disorder induced resistivity variation in metallic metal-oxide nanowires  

Microsoft Academic Search

Several systems of metallic metal-oxide nanowires (NWs), including pure RuO2 and as-implanted and annealed Ru0.98Cu0.02O2 and Ru0.93Cu0.07O2 NWs, have been employed in two-probe electrical characterizations by using a transmission electron microscope-scanning tunneling microscope technique with a gold tip. Thermal, mechanical, and electron beam exposing treatments are consecutively applied to reduce the electrical contact resistance, generated from the interface between the

Y. F. Lin; Z. Y. Wu; K. C. Lin; C. C. Chen; W. B. Jian; F. R. Chen; J. J. Kai

2009-01-01

439

Solid state metathesis synthesis of metal silicides; reactions of calcium and magnesium silicide with metal oxides  

Microsoft Academic Search

Reactions of transition metal oxides (V2O3, V2O5, Nb2O5, LiNbO3, Ta2O5, LiTaO3, MoO3 and Li2MoO4) with lithium silicide (Li2Si) and calcium silicide–magnesium silicide mix (CaSi2, Mg2Si) could be initiated by grinding, flame, filament or bulk thermal methods to produce a range of single phase transition metal silicides (VSi2, NbSi2 and TaSi2) in good yields (approximately 90%). The silicides were characterised by

Artur M. Nartowski; Ivan P. Parkin

2002-01-01

440

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