Europium-activated phosphors containing oxides of rare-earth and group-IIIB metals and method of making the same

DOEpatents

Comanzo, Holly Ann; Setlur, Anant Achyut; Srivastava, Alok Mani

2006-04-04

Europium-activated phosphors comprise oxides of at least a rare-earth metal selected from the group consisting of gadolinium, yttrium, lanthanum, and combinations thereof and at least a Group-IIIB metal selected from the group consisting of aluminum, gallium, indium, and combinations thereof. A method for making such phosphors comprises adding at least a halide of at least one of the selected Group-IIIB metals in a starting mixture. The method further comprises firing the starting mixture in an oxygen-containing atmosphere. The phosphors produced by such a method exhibit improved absorption in the UV wavelength range and improved quantum efficiency.

Europium-activated phosphors containing oxides of rare-earth and group-IIIB metals and method of making the same

DOEpatents

Comanzo, Holly Ann; Setlur, Anant Achyut; Srivastava, Alok Mani; Manivannan, Venkatesan

2004-07-13

Europium-activated phosphors comprise oxides of at least a rare-earth metal selected from the group consisting of gadolinium, yttrium, lanthanum, and combinations thereof and at least a Group-IIIB metal selected from the group consisting of aluminum, gallium, indium, and combinations thereof. A method for making such phosphors comprises adding at least a halide of at least one of the selected Group-IIIB metals in a starting mixture. The method further comprises firing the starting mixture in an oxygen-containing atmosphere. The phosphors produced by such a method exhibit improved absorption in the UV wavelength range and improved quantum efficiency.

Anomalous positive flatband voltage shifts in metal gate stacks containing rare-earth oxide capping layers

NASA Astrophysics Data System (ADS)

Caraveo-Frescas, J. A.; Hedhili, M. N.; Wang, H.; Schwingenschlögl, U.; Alshareef, H. N.

2012-03-01

It is shown that the well-known negative flatband voltage (VFB) shift, induced by rare-earth oxide capping in metal gate stacks, can be completely reversed in the absence of the silicon overlayer. Using TaN metal gates and Gd2O3-doped dielectric, we measure a ˜350 mV negative shift with the Si overlayer present and a ˜110 mV positive shift with the Si overlayer removed. This effect is correlated to a positive change in the average electrostatic potential at the TaN/dielectric interface which originates from an interfacial dipole. The dipole is created by the replacement of interfacial oxygen atoms in the HfO2 lattice with nitrogen atoms from TaN.

Role of metal oxides in chemical evolution

NASA Astrophysics Data System (ADS)

Kamaluddin

2013-06-01

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

Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates.

PubMed

Zhang, Miao; Frei, Heinz

2017-05-05

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

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

DOEpatents

Quinby, Thomas C.

1978-01-01

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

Regeneration of sulfated metal oxides and carbonates

DOEpatents

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

1978-03-28

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

Recovering heavy rare earth metals from magnet scrap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

Synergetic effect of alkaline earth metal oxides and iron oxides on the degradation of hexachlorobenzene and its degradation pathway.

PubMed

Su, Guijin; Liu, Yexuan; Huang, Linyan; Shi, Yali; Zhang, Aiqian; Zhang, Lixia; Liu, Wenbin; Gao, Lirong; Zheng, Minghui

2013-01-01

The degradation of hexachlorobenzene (HCB) was carried out over physical mixtures of a series of alkaline earth metal oxides (MO: M=Mg, Ca, Sr, Ba) and iron oxides with different crystal types (Fe(x)O(y):Fe(2)O(3) or Fe(3)O(4)) at 300°C. These physical mixtures all showed a synergetic effect toward the degradation of HCB. A range of degradation products were identified by various methods, including tri- to penta-chlorobenzenes by gas chromatography/mass spectrometry (GC-MS), tri- to penta-chlorophenols, tetrachlorocatechol (TCC) and tetrachlorohydroquinone (TCHQ) by GC-MS after derivatization, and formic and acetic acids by ion chromatography. Two degradation pathways, hydrodechlorination and oxidative degradation, appear to occur competitively. However, more sequential chlorinated benzene and phenol congeners were formed over mixed MO/Fe(3)O(4) than over mixed MO/Fe(2)O(3) under the same conditions. The oxidative reaction dominated over mixed MO/Fe(2)O(3) and was promoted as the major reaction by the synergetic effect, while both the oxidative and hydrodechlorination reactions were important over mixed MO/Fe(3)O(4), and both pathways are remarkably promoted by the synergetic effect. The enhanced hydrodechlorination may be attributed to free electrons generated by the transformation of Fe(3)O(4) into Fe(2)O(3), and hydrogen provided by water adsorbed on the MO. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

DOEpatents

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

2012-07-03

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

Rare Earth Metals: Resourcefulness and Recovery

NASA Astrophysics Data System (ADS)

Wang, Shijie

2013-10-01

When we appreciate the digital revolution carried over from the twentieth century with mobile communication and the Internet, and when we enjoy our high-tech lifestyle filled with iDevices, hybrid cars, wind turbines, and solar cells in this new century, we should also appreciate that all of these advanced products depend on rare earth metals to function. Although there are only 136,000 tons of annual worldwide demand, (Cho, Rare Earth Metals, Will We Have Enough?)1 rare earth metals are becoming such hot commodities on international markets, due to not only to their increasing uses, including in most critical military hardware, but also to Chinese growth, which accounts for 95% of global rare earth metal production. Hence, the 2013 technical calendar topic, planned by the TMS/Hydrometallurgy and Electrometallurgy Committee, is particularly relevant, with four articles (including this commentary) contributed to the JOM October Issue discussing rare earth metals' resourcefulness and recovery.

A molecular cross-linking approach for hybrid metal oxides.

PubMed

Jung, Dahee; Saleh, Liban M A; Berkson, Zachariah J; El-Kady, Maher F; Hwang, Jee Youn; Mohamed, Nahla; Wixtrom, Alex I; Titarenko, Ekaterina; Shao, Yanwu; McCarthy, Kassandra; Guo, Jian; Martini, Ignacio B; Kraemer, Stephan; Wegener, Evan C; Saint-Cricq, Philippe; Ruehle, Bastian; Langeslay, Ryan R; Delferro, Massimiliano; Brosmer, Jonathan L; Hendon, Christopher H; Gallagher-Jones, Marcus; Rodriguez, Jose; Chapman, Karena W; Miller, Jeffrey T; Duan, Xiangfeng; Kaner, Richard B; Zink, Jeffrey I; Chmelka, Bradley F; Spokoyny, Alexander M

2018-04-01

There is significant interest in the development of methods to create hybrid materials that transform capabilities, in particular for Earth-abundant metal oxides, such as TiO 2 , to give improved or new properties relevant to a broad spectrum of applications. Here we introduce an approach we refer to as 'molecular cross-linking', whereby a hybrid molecular boron oxide material is formed from polyhedral boron-cluster precursors of the type [B 12 (OH) 12 ] 2- . This new approach is enabled by the inherent robustness of the boron-cluster molecular building block, which is compatible with the harsh thermal and oxidizing conditions that are necessary for the synthesis of many metal oxides. In this work, using a battery of experimental techniques and materials simulation, we show how this material can be interfaced successfully with TiO 2 and other metal oxides to give boron-rich hybrid materials with intriguing photophysical and electrochemical properties.

A molecular cross-linking approach for hybrid metal oxides

NASA Astrophysics Data System (ADS)

Jung, Dahee; Saleh, Liban M. A.; Berkson, Zachariah J.; El-Kady, Maher F.; Hwang, Jee Youn; Mohamed, Nahla; Wixtrom, Alex I.; Titarenko, Ekaterina; Shao, Yanwu; McCarthy, Kassandra; Guo, Jian; Martini, Ignacio B.; Kraemer, Stephan; Wegener, Evan C.; Saint-Cricq, Philippe; Ruehle, Bastian; Langeslay, Ryan R.; Delferro, Massimiliano; Brosmer, Jonathan L.; Hendon, Christopher H.; Gallagher-Jones, Marcus; Rodriguez, Jose; Chapman, Karena W.; Miller, Jeffrey T.; Duan, Xiangfeng; Kaner, Richard B.; Zink, Jeffrey I.; Chmelka, Bradley F.; Spokoyny, Alexander M.

2018-03-01

There is significant interest in the development of methods to create hybrid materials that transform capabilities, in particular for Earth-abundant metal oxides, such as TiO2, to give improved or new properties relevant to a broad spectrum of applications. Here we introduce an approach we refer to as `molecular cross-linking', whereby a hybrid molecular boron oxide material is formed from polyhedral boron-cluster precursors of the type [B12(OH)12]2-. This new approach is enabled by the inherent robustness of the boron-cluster molecular building block, which is compatible with the harsh thermal and oxidizing conditions that are necessary for the synthesis of many metal oxides. In this work, using a battery of experimental techniques and materials simulation, we show how this material can be interfaced successfully with TiO2 and other metal oxides to give boron-rich hybrid materials with intriguing photophysical and electrochemical properties.

One Electron-Initiated Two-Electron Oxidation of Water by Aluminum Porphyrins with Earth's Most Abundant Metal.

PubMed

Kuttassery, Fazalurahman; Mathew, Siby; Sagawa, Shogo; Remello, Sebastian Nybin; Thomas, Arun; Yamamoto, Daisuke; Onuki, Satomi; Nabetani, Yu; Tachibana, Hiroshi; Inoue, Haruo

2017-05-09

We report herein a new molecular catalyst for efficient water splitting, aluminum porphyrins (tetra-methylpyridiniumylporphyrinatealuminum: AlTMPyP), containing earth's most abundant metal as the central ion. One-electron oxidation of the aluminum porphyrin initiates the two-electron oxidation of water to form hydrogen peroxide as the primary reaction product with the lowest known overpotential (97 mV). The aluminum-peroxo complex was detected by a cold-spray ionization mass-spectrometry in high-resolution MS (HRMS) mode and the structure of the intermediate species was further confirmed using laser Raman spectroscopy, indicating the hydroperoxy complex of AlTMPyP to be the key intermediate in the reaction. The two-electron oxidation of water to form hydrogen peroxide was essentially quantitative, with a Faradaic efficiency of 99 %. The catalytic reaction was found to be highly efficient, with a turnover frequency up to ∼2×10 4  s -1 . A reaction mechanism is proposed involving oxygen-oxygen bond formation by the attack of a hydroxide ion on the oxyl-radical-like axial ligand oxygen atom in the one-electron-oxidized form of AlTMPyP(O - ) 2 , followed by a second electron transfer to the electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trivalent Rare-Earth-Metal Bis(trimethylsilyl)amide Halide Complexes by Targeted Oxidations.

PubMed

Bienfait, André M; Wolf, Benjamin M; Törnroos, Karl W; Anwander, Reiner

2018-05-07

In contrast to previously applied salt metathesis protocols the targeted rare-earth-metal compounds Ln[N(SiMe 3 ) 2 ] 2 (halogenido) were accessed by oxidation of Ln(II) silylamide precursors. Treatment of Sm[N(SiMe 3 ) 3 ] 2 (thf) 2 with 0.5 equiv of C 2 Cl 6 or 0.25 equiv of TeBr 4 in thf and crystallization thereof gave [Sm{N(SiMe 3 ) 2 } 2 (μ-X)(thf)] 2 (X = Cl, Br). A similar reaction/crystallization procedure performed with 0.5 equiv of 1,2-diiodoethane gave monomeric Sm[N(SiMe 3 ) 2 ] 2 I(thf) 2 . Switching to Yb[N(SiMe 3 ) 2 ] 2 (thf) 2 , the aforementioned oxidants generated monomeric five-coordinate complexes Yb[N(SiMe 3 ) 2 ] 2 X(thf) 2 (X = Cl, Br, I). The reaction of Eu[N(SiMe 3 ) 2 ] 2 (thf) 2 with 0.5 equiv of C 2 Cl 6 in thf yielded the separated ion pair [Eu{N(SiMe 3 ) 2 } 3 Cl][(thf) 5 Eu(μ-Cl) 2 Eu(thf) 5 ]. Performing the chlorination in n-hexane led to oxidation followed by rapid disproportionation into EuCl 3 (thf) x and Eu[N(SiMe 3 ) 2 ] 3 . The bromination reaction did not afford crystalline material, while the iodination gave crystals of divalent EuI 2 (thf) 5 . Use of trityl chloride (Ph 3 CCl) as the oxidant in thf accomplished the Eu(III) species [Eu{N(SiMe 3 ) 2 } 2 (μ-Cl)(thf)] 2 . In situ oxidation of putative [Tm{N(SiMe 3 ) 2 } 2 (thf) x ] using 0.5 equiv of C 2 Cl 6 in thf followed by crystallization from n-hexane led to the formation of a mixture of [Tm{N(SiMe 3 ) 2 } 2 (μ-Cl)(thf)] 2 and Tm[N(SiMe 3 ) 2 ] 3 . Switching the oxidant to 0.5 equiv of 1,2-diiodoethane and crystallizing from thf repeatedly afforded the bis-halogenated complex Tm[N(SiMe 3 ) 2 ]I 2 (thf) 3 .

Chemical analysis of extracting transition metal oxides from polymetallic ore by sulphate process

NASA Astrophysics Data System (ADS)

Enkh-Uyanga, Otgon-Uul; Munkhtsetseg, Baatar; Urangoo, Urtnasan; Tserendulam, Enkhtur; Agiimaa, Davaadorj

2017-06-01

In this research work we attempt to improve the purity of polymetallic ores in Mongolia whilst developing practical applications of its refinement processes and this paper presents the results of chemical research of extracting transition metal titanium oxides, ferrous oxide and rare earth oxides from polymetallic ore. Thereby, chemical and mineral analysis of polymetallic ore is carried out basis of responses to the support process at various degrees of water whereas transition metal sulphates solubility differ. As a result of sulphate and resulphurization process we have extracted anatase with 62.5 percent titanium dioxide and brookite mineral with 89.6 percent of titanium dioxide as well as mineral with 83.8 percent of ferrous oxide hematite and rare earth oxides with 57.6 percent of cerium oxide. These oxides are identified under various conditions in the thermal processing. The morphology structure and chemical content compound of the mineral has been verified as a result of the XRF, XRD, SEM-EDX analysis.

Thermodynamic properties of some metal oxide-zirconia systems

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1989-01-01

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

Extracting metals directly from metal oxides

DOEpatents

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

1997-01-01

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

Extracting metals directly from metal oxides

DOEpatents

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

1997-02-25

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

Method of CO and/or CO.sub.2 hydrogenation using doped mixed-metal oxides

DOEpatents

Shekhawat, Dushyant; Berry, David A.; Haynes, Daniel J.; Abdelsayed, Victor; Smith, Mark W.; Spivey, James J.

2015-10-06

A method of hydrogenation utilizing a reactant gas mixture comprising a carbon oxide and a hydrogen agent, and a hydrogenation catalyst comprising a mixed-metal oxide containing metal sites supported and/or incorporated into the lattice. The mixed-metal oxide comprises a perovskite, a pyrochlore, a fluorite, a brownmillerite, or mixtures thereof doped at the A-site or the B-site. The metal site may comprise a deposited metal, where the deposited metal is a transition metal, an alkali metal, an alkaline earth metal, or mixtures thereof. Contact between the carbon oxide, hydrogen agent, and hydrogenation catalyst under appropriate conditions of temperature, pressure and gas flow rate generate a hydrogenation reaction and produce a hydrogenated product made up of carbon from the carbon oxide and some portion of the hydrogen agent. The carbon oxide may be CO, CO.sub.2, or mixtures thereof and the hydrogen agent may be H.sub.2. In a particular embodiment, the hydrogenated product comprises an alcohol, an olefin, an aldehyde, a ketone, an ester, an oxo-product, or mixtures thereof.

Metal oxide electrocatalysts for alternative energy technologies

NASA Astrophysics Data System (ADS)

Pacquette, Adele Lawren

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

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1997-01-01

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

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1994-01-01

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

High-temperature corrosion of metals in the salt and metallic melts containing rare earths

NASA Astrophysics Data System (ADS)

Karpov, V. V.; Abramov, A. V.; Zhilyakov, A. Yu.; Belikov, S. V.; Volkovich, V. A.; Polovov, I. B.; Rebrin, O. I.

2016-09-01

A complex of independent methods was employed to study the corrosion resistance of molybdenum, zirconium, tantalum and tungsten in chloride, chloride-fluoride and fluoride-oxide melts based on LiCl, CaCl2, NaCl- KCl, LiF, and containing rare earths. Tests were conducted for 30 h at 750-1050 °C. The metals showed excellent corrosion resistance in fused chlorides (the corrosion rates were below 0.0005 g/(m2 h). Despite the presence of chemically active fluoride ions in the chloride-fluoride melts, the metals studied also showed very low corrosion rates, except molybdenum, for which the rate of corrosion was 0,8 g/(m2 h). The corrosion resistance of tantalum was considerably reduced in the fluoride-oxide melts; the corrosion rate was over 1 g/(m2 h) corresponding to the 8-th grade of stability and placing tantalum to the group of "low stability" materials.

Synthesizing new types of ultrathin 2D metal oxide nanosheets via half-successive ion layer adsorption and reaction

NASA Astrophysics Data System (ADS)

Gao, Linjie; Li, Yaguang; Xiao, Mu; Wang, Shufang; Fu, Guangsheng; Wang, Lianzhou

2017-06-01

Two-dimensional (2D) metal oxide nanosheets have demonstrated their great potential in a broad range of applications. The existing synthesis strategies are mainly preparing 2D nanosheets from layered and specific transition metal oxides. How to prepare the other types of metal oxides as ultrathin 2D nanosheets remains unsolved, especially for metal oxides containing alkali, alkaline earth metal, and multiple metal elements. Herein, we developed a half-successive ion layer adsorption and reaction (SILAR) method, which could synthesize those types of metal oxides as ultrathin 2D nanosheets. The synthesized 2D metal oxides nanosheets are within 1 nm level thickness and 500 m2 · g-1 level surface area. This method allows us to develop many new types of ultrathin 2D metal oxides nanosheets that have never been prepared before.

Interaction of Metal Oxides with Biomolecules: Implication in Astrobiology

NASA Astrophysics Data System (ADS)

Kamaluddin; Iqubal, Md. Asif

2014-08-01

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

Metal oxides for optoelectronic applications.

PubMed

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

2016-04-01

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

Metal oxides for optoelectronic applications

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

A molecular cross-linking approach for hybrid metal oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Dahee; Saleh, Liban A. M.; Berkson, Zachariah J.

Developing methods to create hybrid materials to maximize their transformative capabilities has been the subject of significant interest. In particular, several key methods have been developed to manipulate earth abundant metal oxides such as TiO 2 to produce hybrid materials with improved or new properties relevant to a broad spectrum of applications. Here, we introduce a new approach we refer to as “molecular doping”, whereby a hybrid molecular boron oxide material is formed from polyhedral boron cluster precursors of the type [B 12(OH) 12] 2-. This new approach is enabled by the inherent robustness of the boron cluster molecular buildingmore » block, which is compatible with harsh thermal and oxidizing conditions that are necessary for the synthesis of many metal oxides. In this work, we show how this material can be successfully interfaced with TiO 2, resulting in boron-rich hybrid materials with unprecedented photophysical and electrochemical properties.« less

Method of CO and/or CO.sub.2 hydrogenation to higher hydrocarbons using doped mixed-metal oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shekhawat, Dushyant; Berry, David A.; Haynes, Daniel J.

2017-03-21

A method of hydrogenation utilizing a reactant gas mixture comprising a carbon oxide and a hydrogen agent, and a hydrogenation catalyst comprising a mixed-metal oxide containing metal sites supported and/or incorporated into the lattice. The mixed-metal oxide comprises a pyrochlore, a brownmillerite, or mixtures thereof doped at the A-site or the B-site. The metal site may comprise a deposited metal, where the deposited metal is a transition metal, an alkali metal, an alkaline earth metal, or mixtures thereof. Contact between the carbon oxide, hydrogen agent, and hydrogenation catalyst under appropriate conditions of temperature, pressure and gas flow rate generate amore » hydrogenation reaction and produce a hydrogenated product made up of carbon from the carbon oxide and some portion of the hydrogen agent. The carbon oxide may be CO, CO.sub.2, or mixtures thereof and the hydrogen agent may be H.sub.2. In a particular embodiment, the hydrogenated product comprises olefins, paraffins, or mixtures thereof.« less

Band gap tuning in transition metal oxides by site-specific substitution

DOEpatents

Lee, Ho Nyung; Chisholm, Jr., Matthew F; Jellison, Jr., Gerald Earle; Singh, David J; Choi, Woo Seok

2013-12-24

A transition metal oxide insulator composition having a tuned band gap includes a transition metal oxide having a perovskite or a perovskite-like crystalline structure. The transition metal oxide includes at least one first element selected form the group of Bi, Ca, Ba, Sr, Li, Na, Mg, K, Pb, and Pr; and at least one second element selected from the group of Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Hf, Ta, W, Re, Os, Ir, and Pt. At least one correlated insulator is integrated into the crystalline structure, including REMO.sub.3, wherein RE is at least one Rare Earth element, and wherein M is at least one element selected from the group of Co, V, Cr, Ni, Mn, and Fe. The composition is characterized by a band gap of less of 4.5 eV.

Near-Earth asteroids: Metals occurrence, extraction, and fabrication

NASA Astrophysics Data System (ADS)

Westfall, Richard

Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength

Near-Earth asteroids: Metals occurrence, extraction, and fabrication

NASA Technical Reports Server (NTRS)

Westfall, Richard

1991-01-01

Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength

Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

PubMed

Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

2009-01-01

Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

Rare earth metal-containing ionic liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prodius, Denis; Mudring, Anja-Verena

As an innovative tool, ionic liquids (ILs) are widely employed as an alternative, smart, reaction media (vs. traditional solvents) offering interesting technology solutions for dissolving, processing and recycling of metal-containing materials. The costly mining and refining of rare earths (RE), combined with increasing demand for high-tech and energy-related applications around the world, urgently requires effective approaches to improve the efficiency of rare earth separation and recovery. In this context, ionic liquids appear as an attractive technology solution. Finally, this paper addresses the structural and coordination chemistry of ionic liquids comprising rare earth metals with the aim to add to understandingmore » prospects of ionic liquids in the chemistry of rare earths.« less

Rare earth metal-containing ionic liquids

DOE PAGES

Prodius, Denis; Mudring, Anja-Verena

2018-03-07

As an innovative tool, ionic liquids (ILs) are widely employed as an alternative, smart, reaction media (vs. traditional solvents) offering interesting technology solutions for dissolving, processing and recycling of metal-containing materials. The costly mining and refining of rare earths (RE), combined with increasing demand for high-tech and energy-related applications around the world, urgently requires effective approaches to improve the efficiency of rare earth separation and recovery. In this context, ionic liquids appear as an attractive technology solution. Finally, this paper addresses the structural and coordination chemistry of ionic liquids comprising rare earth metals with the aim to add to understandingmore » prospects of ionic liquids in the chemistry of rare earths.« less

Alkali metal and alkali earth metal gadolinium halide scintillators

DOEpatents

Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

2016-08-02

The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

High-pressure metallization of FeO and implications for the earth's core

NASA Technical Reports Server (NTRS)

Knittle, Elise; Jeanloz, Raymond

1986-01-01

The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock-wave and diamond-cell techniques. A metallic phase of FeO is observed at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the earth's outer core, in accord with the geochemical predictions of Ringwood (1977 and 1979). The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core-forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions.

Methods for synthesizing metal oxide nanowires

DOEpatents

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

2016-08-09

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

Thin film hydrous metal oxide catalysts

DOEpatents

Dosch, Robert G.; Stephens, Howard P.

1995-01-01

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

Separation of rare earths from transition metals by liquid-liquid extraction from a molten salt hydrate to an ionic liquid phase.

PubMed

Rout, Alok; Binnemans, Koen

2014-02-28

The solvent extraction of trivalent rare-earth ions and their separation from divalent transition metal ions using molten salt hydrates as the feed phase and an undiluted fluorine-free ionic liquid as the extracting phase were investigated in detail. The extractant was tricaprylmethylammonium nitrate, [A336][NO3], and the hydrated melt was calcium nitrate tetrahydrate, Ca(NO3)2·4H2O. The extraction behavior of rare-earth ions was studied for solutions of individual elements, as well as for mixtures of rare earths in the hydrated melt. The influence of different extraction parameters was investigated: the initial metal loading in the feed phase, percentage of water in the feed solution, equilibration time, and the type of hydrated melt. The extraction of rare earths from Ca(NO3)2·4H2O was compared with extraction from CaCl2·4H2O by [A336][Cl] (Aliquat 336). The nitrate system was found to be the better one. The extraction and separation of rare earths from the transition metals nickel, cobalt and zinc were also investigated. Remarkably high separation factors of rare-earth ions over transition metal ions were observed for extraction from Ca(NO3)2·4H2O by the [A336][NO3] extracting phase. Furthermore, rare-earth ions could be separated efficiently from transition metal ions, even in melts with very high concentrations of transition metal ions. Rare-earth oxides could be directly dissolved in the Ca(NO3)2·4H2O phase in the presence of small amounts of Al(NO3)3·9H2O or concentrated nitric acid. The efficiency of extraction after dissolving the rare-earth oxides in the hydrated nitrate melt was identical to extraction from solutions with rare-earth nitrates dissolved in the molten phase. The stripping of the rare-earth ions from the loaded ionic liquid phase and the reuse of the recycled ionic liquid were also investigated in detail.

Tailoring transition-metal hydroxides and oxides by photon-induced reactions

DOE PAGES

Niu, Kai -Yang; Fang, Liang; Ye, Rong; ...

2016-10-18

Controlled synthesis of transition-metal hydroxides and oxides with earth-abundant elements have attracted significant interest because of their wide applications, for example as battery electrode materials or electrocatalysts for fuel generation. Here, we report the tuning of the structure of transition-metal hydroxides and oxides by controlling chemical reactions using an unfocused laser to irradiate the precursor solution. A Nd:YAG laser with wavelengths of 532 nm or 1064 nm was used. The Ni 2+, Mn 2+, and Co 2+ ion-containing aqueous solution undergoes photo-induced reactions and produces hollow metal-oxide nanospheres (Ni 0.18Mn 0.45Co 0.37O x) or core–shell metal hydroxide nanoflowers ([Ni 0.15Mnmore » 0.15Co 0.7(OH) 2](NO 3) 0.2•H 2O), depending on the laser wavelengths. We propose two reaction pathways, either by photo-induced redox reaction or hydrolysis reaction, which are responsible for the formation of distinct nanostructures. As a result, the study of photon-induced materials growth shines light on the rational design of complex nanostructures with advanced functionalities.« less

Magnetic preferential orientation of metal oxide superconducting materials

DOEpatents

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

1990-07-17

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.

Magnetic preferential orientation of metal oxide superconducting materials

DOEpatents

Capone, Donald W.; Dunlap, Bobby D.; Veal, Boyd W.

1990-01-01

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.

Thermodynamic Investigation of the Reduction-Distillation Process for Rare Earth Metals Production

NASA Astrophysics Data System (ADS)

Judge, W. D.; Azimi, G.

2017-10-01

Owing to their high vapor pressure, the four rare earth metals samarium, europium, thulium, and ytterbium are produced by reduction-distillation whereby their oxides are reduced with metallic lanthanum in vacuo, and the produced metal is subsequently vaporized off. Here, we performed a thorough thermodynamic investigation to establish a fundamental understanding of the reduction-distillation process. Thermodynamic functions including vapor pressures, Gibbs free energies, and enthalpies of reaction were calculated and compared with available experimental data. Furthermore, the kinetics of the process was explored and theoretical evaporation rates were calculated from thermodynamic data. The thermodynamic model developed in this work can help optimize processing conditions to maximize the yield and improve the overall process.

Lithium metal reduction of plutonium oxide to produce plutonium metal

DOEpatents

Coops, Melvin S.

1992-01-01

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

Graphene-supported metal oxide monolith

DOEpatents

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

2017-01-10

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

Metal oxide nanostructures with hierarchical morphology

DOEpatents

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

2007-11-13

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

Mesoporous metal oxide graphene nanocomposite materials

DOEpatents

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

2016-05-24

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

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

DOEpatents

Ray, Siba P.; Liu, Xinghua; Weirauch, Douglas A.

2002-01-01

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

Method for plating with metal oxides

DOEpatents

Silver, Gary L.; Martin, Frank S.

1994-08-23

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

Catalysis using hydrous metal oxide ion exchanges

DOEpatents

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

1985-01-01

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

Catalysis using hydrous metal oxide ion exchangers

DOEpatents

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

1983-07-21

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

Method for plating with metal oxides

DOEpatents

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

1994-08-23

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

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

NASA Technical Reports Server (NTRS)

Youngdahl, C. A.

1967-01-01

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.

Metal oxide nanorod arrays on monolithic substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can includemore » a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.« less

Method for treating rare earth-transition metal scrap

DOEpatents

Schmidt, Frederick A.; Peterson, David T.; Wheelock, John T.; Jones, Lawrence L.

1992-12-29

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

Method for treating rare earth-transition metal scrap

DOEpatents

Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.

1992-12-29

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a rare earth fluoride-bearing flux of CaF[sub 2], CaCl[sub 2] or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy. 3 figs.

Rare-earth metal prices in the USA ca. 1960 to 1994

USGS Publications Warehouse

Hedrick, James B.

1997-01-01

Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass. CA, USA, in 1949, was significant because it led to the production of commercial quantities or rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

Rare-earth metal prices in the USA ca. 1960 to 1994

USGS Publications Warehouse

Hedrick, J.B.

1997-01-01

Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass, CA, USA, in 1949, was significant because it led to the production of commercial quantities of rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

Metal atom oxidation laser

DOEpatents

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

1975-10-28

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

Mesoporous metal oxides and processes for preparation thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suib, Steven L.; Poyraz, Altug Suleyman

A process for preparing a mesoporous metal oxide, i.e., transition metal oxide. Lanthanide metal oxide, a post-transition metal oxide and metalloid oxide. The process comprises providing an acidic mixture comprising a metal precursor, an interface modifier, a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to form the mesoporous metal oxide. A mesoporous metal oxide prepared by the above process. A method of controlling nano-sized wall crystallinity and mesoporosity in mesoporous metal oxides. The method comprises providing an acidic mixture comprising a metal precursor, an interface modifier,more » a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to control nano-sized wall crystallinity and mesoporosity in the mesoporous metal oxides. Mesoporous metal oxides and a method of tuning structural properties of mesoporous metal oxides.« less

Silica metal-oxide vesicles catalyze comprehensive prebiotic chemistry.

PubMed

Bizzarri, Bruno Mattia; Botta, Lorenzo; Pérez-Valverde, Maritza Iveth; Saladino, Raffaele; Di Mauro, Ernesto; Garcia Ruiz, Juan Manuel

2018-03-30

It has recently been demonstrated that mineral self-assembled structures catalyzing prebiotic chemical reactions may form in natural waters derived from serpentinization, a geological process widespread in the early stages of Earth-like planets. We have synthesized self-assembled membranes by mixing microdrops of metal solutions with alkaline silicate solutions in the presence of formamide (NH2CHO), a single carbon molecule, at 80ºC. We found that these bilayer membranes, made of amorphous silica and metal oxide-hydroxide nanocrystals, catalyze the condensation of formamide, yielding the four nucleobases of RNA, three aminoacids and several carboxylic acids in a single pot experiment. Besides manganese, iron and magnesium, two abundant elements in the earliest Earth crust that are key in serpentinization reactions, are enough to produce all these biochemical compounds. These results suggest that the transition from inorganic geochemistry to prebiotic organic chemistry is common on a universal scale and, most probably, earlier than ever thought for our planet. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Production method for making rare earth compounds

DOEpatents

McCallum, R.W.; Ellis, T.W.; Dennis, K.W.; Hofer, R.J.; Branagan, D.J.

1997-11-25

A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g., a transition metal and optional boron), and a carbide-forming element (e.g., a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g., Nd{sub 2}Fe{sub 14}B or LaNi{sub 5}) and a carbide of the carbide-forming element are formed.

Production method for making rare earth compounds

DOEpatents

McCallum, R. William; Ellis, Timothy W.; Dennis, Kevin W.; Hofer, Robert J.; Branagan, Daniel J.

1997-11-25

A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.

Metals and lipid oxidation. Contemporary issues.

PubMed

Schaich, K M

1992-03-01

Lipid oxidation is now recognized to be a critically important reaction in physiological and toxicological processes as well as in food products. This provides compelling reasons to understand what causes lipid oxidation in order to be able to prevent or control the reactions. Redox-active metals are major factors catalyzing lipid oxidation in biological systems. Classical mechanisms of direct electron transfer to double bonds by higher valence metals and of reduction of hydroperoxides by lower valence metals do not always account for patterns of metal catalysis of lipid oxidation in multiphasic or compartmentalized biological systems. To explain why oxidation kinetics, mechanisms, and products in molecular environments which are both chemically and physically complex often do not follow classical patterns predicted by model system studies, increased consideration must be given to five contemporary issues regarding metal catalysis of lipid oxidation: hypervalent non-heme iron or iron-oxygen complexes, heme catalysis mechanism(s), compartmentalization of reactions and lipid phase reactions of metals, effects of metals on product mixes, and factors affecting the mode of metal catalytic action.

Theoretical study of the diatomic alkali and alkaline-earth oxides

NASA Technical Reports Server (NTRS)

Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.

1986-01-01

Theoretical dissociation energies for the ground states of the alkali and alkaline earth oxides are presented that are believed to be accurate to 0.1 eV. The 2 Pi - 2 Sigma + separations for the alkali oxides are found to be more sensitive to basis set than to electron correlation. Predicted 2 Pi ground states for LiO and NaO and 2 Sigma + ground states for RbO and CsO are found to be in agreement with previous theoretical and experimental work. For KO, a 2 Sigma + state is found at both the numerical Hartree-Fock (NHF) level and at the singles plus doubles configuration interaction level using a Slater basis set that is within 0.02 eV of the NHF limit. It is found that an accurate balanced treatment of the two states requires correlating the electrons on both the metal and oxide ion.

Metal atom oxidation laser

DOEpatents

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

1975-10-28

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

Surface protected lithium-metal-oxide electrodes

DOEpatents

Thackeray, Michael M.; Kang, Sun-Ho

2016-04-05

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

Catalytic production of metal carbonyls from metal oxides

DOEpatents

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

1984-01-01

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

Catalytic production of metal carbonyls from metal oxides

DOEpatents

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

1984-01-06

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

Syntheses and structures of alkaline earth metal bis(diphenylamides).

PubMed

Gärtner, Martin; Fischer, Reinald; Langer, Jens; Görls, Helmar; Walther, Dirk; Westerhausen, Matthias

2007-06-11

Various preparative procedures are employed in order to synthesize alkaline earth metal bis(diphenylamides) such as (i) metalation of HNPh2 with the alkaline earth metal M, (ii) metalation of HNPh2 with MPh2, (iii) metathesis reaction of MI2 with KNPh2, (iv) metalation of HNPh2 with PhMI in THF, and (v) metathesis reaction of PhMI with KNPh2 followed by a dismutation reaction yielding MPh2 and M(NPh2)2. The magnesium compounds [(diox)MgPh2]infinity (1) and (thf)2Mg(NPh2)2 (2) show tetracoordinate metal atoms, whereas in (dme)2Ca(NPh2)2 (3), (thf)4Sr(NPh2)2 (4), and (thf)4Ba(NPh2)2 (5) the metals are 6-fold coordinated. Additional agostic interactions between an ipso-carbon of one of the phenyl groups of the amide ligand and the alkaline earth metal atom lead to unsymmetric coordination of the NPh2 anions with two strongly different M-N-C angles in 3-5.

Mesoporous Transition Metal Oxides for Supercapacitors.

PubMed

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

2015-10-14

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

Single-Phase Rare-Earth Oxide/Aluminum Oxide Glasses

NASA Technical Reports Server (NTRS)

Weber, J. K. Richard; Abadie, John G.; Hixson, April D.; Nordine, Paul C.

2006-01-01

Glasses that comprise rare-earth oxides and aluminum oxide plus, optionally, lesser amounts of other oxides, have been invented. The other oxide(s) can include SiO2, B2O3, GeO2, and/or any of a variety of glass-forming oxides that have been used heretofore in making a variety of common and specialty glasses. The glasses of the invention can be manufactured in bulk single-phase forms to ensure near uniformity in optical and mechanical characteristics, as needed for such devices as optical amplifiers, lasers, and optical waveguides (including optical fibers). These glasses can also be formulated to have high indices of refraction, as needed in some of such devices.

Rare earth element recycling from waste nickel-metal hydride batteries.

PubMed

Yang, Xiuli; Zhang, Junwei; Fang, Xihui

2014-08-30

With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Method for producing metal oxide nanoparticles

DOEpatents

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

2008-04-15

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

Effect of H2O on metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe: Implications for the oxidation state of the Earth and Mars

NASA Astrophysics Data System (ADS)

Clesi, V.; Bouhifd, M. A.; Bolfan-Casanova, N.; Manthilake, G.; Fabbrizio, A.; Andrault, D.

2016-11-01

This study investigates the metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe-C-Ni-Co-Si-S in a multi-anvil over a range of P, T, fO2 and water content (5-20 GPa, 2073-2500 K, from 1 to 5 log units below the iron-wüstite (IW) buffer and for XH2O varying from 500 ppm to 1.5 wt%). By comparing the present experiments with the available data sets on dry systems, we observes that the effect of water on the partition coefficients of moderately siderophile elements is only moderate. For example, for iron we observed a decrease in the partition coefficient of Fe (Dmet/silFe) from 9.5 to 4.3, with increasing water content of the silicate melt, from 0 to 1.44 wt%, respectively. The evolution of metal-silicate partition coefficients of Ni, Co, V, Cr, Mn and Fe are modelled based on sets of empirical parameters. These empirical models are then used to refine the process of core segregation during accretion of Mars and the Earth. It appears that the likely presence of 3.5 wt% water on Mars during the core-mantle segregation could account for ∼74% of the FeO content of the Martian mantle. In contrast, water does not play such an important role for the Earth; only 4-6% of the FeO content of its mantle could be due to the water-induced Fe-oxidation, for a likely initial water concentration of 1.8 wt%. Thus, in order to reproduce the present-day FeO content of 8 wt% in the mantle, the Earth could initially have been accreted from a large fraction (between 85% and 90%) of reducing bodies (similar to EH chondrites), with 10-15% of the Earth's mass likely made of more oxidized components that introduced the major part of water and FeO to the Earth. This high proportion of enstatite chondrites in the original constitution of the Earth is consistent with the 17O,48Ca,50Ti,62Ni

Dual Functionalization of White Phosphorus: Formation, Characterization, and Reactivity of Rare-Earth-Metal Cyclo-P3 Complexes.

PubMed

Du, Shanshan; Yin, Jianhao; Chi, Yue; Xu, Ling; Zhang, Wen-Xiong

2017-12-11

The [3+1] fragmentation reaction of rare-earth metallacyclopentadienes 1 a-c with 0.5 equivalents of P 4 affords a series of rare-earth metal cyclo-P 3 complexes 2 a-c and a phospholyl anion 3. 2 a-c demonstrate an unusual η 3 coordination mode with one P-P bond featuring partial π-bonding character. 2 a-c are the first cyclo-P 3 complexes of rare-earth metals, and also the first organo-substituted polyphosphides in the category of Group 3 and f-block elements. Rare-earth metallacyclopentadienes play a dual role in the combination of aromatization and Diels-Alder reaction. Compounds 2 a-c can coordinate to one or two [W(CO) 5 ] units, yielding 4 a-c or 5 c, respectively. Furthermore, oxidation of 2 a with p-benzoquinone produces its corresponding phospholyllithium and regenerated P 4 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation.

PubMed

Zhang, Peili; Li, Lin; Nordlund, Dennis; Chen, Hong; Fan, Lizhou; Zhang, Biaobiao; Sheng, Xia; Daniel, Quentin; Sun, Licheng

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2 . The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates.

PubMed

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

2015-04-21

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

Aerosol-spray diverse mesoporous metal oxides from metal nitrates

PubMed Central

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

2015-01-01

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

Metal sulfide and rare-earth phosphate nanostructures and methods of making same

DOEpatents

Wong, Stanislaus; Zhang, Fen

2016-06-28

The present invention provides a method of producing a crystalline rare earth phosphate nanostructure. The method comprising: providing a rare earth metal precursor solution and providing a phosphate precursor solution; placing a porous membrane between the metal precursor solution and the phosphate precursor solution, wherein metal cations of the metal precursor solution and phosphate ions of the phosphate precursor solution react, thereby producing a crystalline rare earth metal phosphate nanostructure.

Mesoporous Transition Metal Oxides for Supercapacitors

PubMed Central

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

2015-01-01

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

Reactive metal-oxide interfaces: A microscopic view

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Thermophysical properties of liquid rare earth metals

NASA Astrophysics Data System (ADS)

Thakor, P. B.; Sonvane, Y. A.; Patel, H. P.; Jani, A. R.

2013-06-01

The thermodynamical properties like long wavelength limit S(0), iso-thermal compressibility (χT), thermal expansion coefficient (αV), thermal pressure coefficient (γV), specific heat at constant volume (CV) and specific heat at constant pressure (CP) are calculated for liquid rare earth metals. Our newly constructed parameter free model potential is used to describe the electron ion interaction due to Sarkar et al (S) local field correction function. Lastly, we conclude that our newly constructed model potential is capable to explain the thermophysical properties of liquid rare earth metals.

Molecular Level Coating of Metal Oxide Particles

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Molecular Level Coating for Metal Oxide Particles

NASA Technical Reports Server (NTRS)

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

2000-01-01

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

Method of making controlled morphology metal-oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ozcan, Soydan; Lu, Yuan

2016-05-17

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

Composite catalyst for carbon monoxide and hydrocarbon oxidation

DOEpatents

Liu, W.; Flytzani-Stephanopoulos, M.

1996-03-19

A method and composition are disclosed for the complete oxidation of carbon monoxide and/or hydrocarbon compounds. The method involves reacting the carbon monoxide and/or hydrocarbons with an oxidizing agent in the presence of a metal oxide composite catalyst. The catalyst is prepared by combining fluorite-type oxygen ion conductors with active transition metals. The fluorite oxide, selected from the group consisting of cerium oxide, zirconium oxide, thorium oxide, hafnium oxide, and uranium oxide, and may be doped by alkaline earth and rare earth oxides. The transition metals, selected from the group consisting of molybdenum, copper, cobalt, manganese, nickel, and silver, are used as additives. The atomic ratio of transition metal to fluorite oxide is less than one.

Composite catalyst for carbon monoxide and hydrocarbon oxidation

DOEpatents

Liu, Wei; Flytzani-Stephanopoulos, Maria

1996-01-01

A method and composition for the complete oxidation of carbon monoxide and/or hydrocarbon compounds. The method involves reacting the carbon monoxide and/or hydrocarbons with an oxidizing agent in the presence of a metal oxide composite catalyst. The catalyst is prepared by combining fluorite-type oxygen ion conductors with active transition metals. The fluorite oxide, selected from the group consisting of cerium oxide, zirconium oxide, thorium oxide, hafnium oxide, and uranium oxide, and may be doped by alkaline earth and rare earth oxides. The transition metals, selected from the group consisting of molybdnum, copper, cobalt, maganese, nickel, and silver, are used as additives. The atomic ratio of transition metal to fluorite oxide is less than one.

Thermochemistry of rare earth doped uranium oxides LnxU1-xO2-0.5x+y (Ln = La, Y, Nd)

NASA Astrophysics Data System (ADS)

Zhang, Lei; Navrotsky, Alexandra

2015-10-01

Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10-50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

Microbial-mediated method for metal oxide nanoparticle formation

DOEpatents

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

2015-09-08

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

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Peili; Li, Lin; Nordlund, Dennis

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE PAGES

Zhang, Peili; Li, Lin; Nordlund, Dennis; ...

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrated alkaline earth metal salts of... Specific Chemical Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a... hydrated alkaline earth metal salts of metalloid oxyanions (PMN P-94-1557) is subject to reporting under...

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity

NASA Astrophysics Data System (ADS)

Li, L. H.; Deng, Z. X.; Xiao, J. X.; Yang, G. W.

2015-06-01

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

PubMed

Li, L H; Deng, Z X; Xiao, J X; Yang, G W

2015-01-26

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

Electrocatalytic N-Doped Graphitic Nanofiber - Metal/Metal Oxide Nanoparticle Composites.

PubMed

Tang, Hongjie; Chen, Wei; Wang, Jiangyan; Dugger, Thomas; Cruz, Luz; Kisailus, David

2018-03-01

Carbon-based nanocomposites have shown promising results in replacing commercial Pt/C as high-performance, low cost, nonprecious metal-based oxygen reduction reaction (ORR) catalysts. Developing unique nanostructures of active components (e.g., metal oxides) and carbon materials is essential for their application in next generation electrode materials for fuel cells and metal-air batteries. Herein, a general approach for the production of 1D porous nitrogen-doped graphitic carbon fibers embedded with active ORR components, (M/MO x , i.e., metal or metal oxide nanoparticles) using a facile two-step electrospinning and annealing process is reported. Metal nanoparticles/nanoclusters nucleate within the polymer nanofibers and subsequently catalyze graphitization of the surrounding polymer matrix and following oxidation, create an interconnected graphite-metal oxide framework with large pore channels, considerable active sites, and high specific surface area. The metal/metal oxide@N-doped graphitic carbon fibers, especially Co 3 O 4 , exhibit comparable ORR catalytic activity but superior stability and methanol tolerance versus Pt in alkaline solutions, which can be ascribed to the synergistic chemical coupling effects between Co 3 O 4 and robust 1D porous structures composed of interconnected N-doped graphitic nanocarbon rings. This finding provides a novel insight into the design of functional electrocatalysts using electrospun carbon nanomaterials for their application in energy storage and conversion fields. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Methods of producing adsorption media including a metal oxide

DOEpatents

Mann, Nicholas R; Tranter, Troy J

2014-03-04

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

Metal Based Synthetic Strategies and the Examination of Structure Determining Factors in Alkaline Earth Metal Compounds

NASA Astrophysics Data System (ADS)

Takahashi, Yuriko

Last decades have witnessed a large expansion of the organometallic heavier alkaline earth metal species. However, continued growth of this promising area of chemistry has been slowed by severe restrictions and limitations in viable synthetic methodologies leading to difficulties in preparing and characterizing the target compounds. There is clearly a need for the further development of synthetic methodologies and detailed structure function analysis that will promote the further advancement of organoalkaline earth metal chemistry in applications as diverse as materials chemistry and catalysis. This thesis work greatly extends the synthetic options currently available towards organoalkaline earth metal species by introducing redox transmetallation protolysis (RTP), a reaction based on the readily available Ph3Bi as a non-toxic transmetallation agent. Based on a straightforward one-pot procedure and work-up, Ph3Bi based RTP presents a powerful synthetic alternative for the facile preparation of a large variety of heavy alkaline earth metal compounds. The second part of the thesis explores the effect of secondary non covalent interactions on the coordination chemistry as well as thermal properties of a series of novel alkali, alkaline earth, rare earth as well as heterobimetallic alkali/alkaline earth fluoroalkoxides. These compounds showcase the significance of non-covalent M···F-C and agostic interactions on metal stabilization and structural features, providing critical input on ligand design for the design of advanced metal organic vapor deposition (MOCVD) precursor materials. This work also showcases the impact of M···F-C interactions over M---co-ligand coordination, a critical precursor design element as well.

Nanostructured transition metal oxides useful for water oxidation catalysis

DOEpatents

Frei, Heinz M; Jiao, Feng

2013-12-24

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

Systematic study of metal-insulator-metal diodes with a native oxide

NASA Astrophysics Data System (ADS)

Donchev, E.; Gammon, P. M.; Pang, J. S.; Petrov, P. K.; Alford, N. McN.

2014-10-01

In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device's rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

Giant magnetic anisotropy of rare-earth adatoms and dimers adsorbed by graphene oxide.

PubMed

Zhang, Kai-Cheng; Li, Yong-Feng; Liu, Yong; Zhu, Yan; Shi, Li-Bin

2017-05-24

Nowadays, transition-metal adatoms and dimers with giant magnetic anisotropy have attracted much attention due to their potential applications in data storage, spintronics and quantum computations. Using density-functional calculations, we investigated the magnetic anisotropy of the rare-earth adatoms and dimers adsorbed by graphene oxide. Our calculations reveal that the adatoms of Tm, Er and Sm possess giant magnetic anisotropy, typically larger than 40 meV. When the dimers of (Tm,Er,Sm)-Ir are adsorbed onto graphene oxide, the magnetic anisotropy even exceeds 200 meV. The magnetic anisotropy can be tuned by the external electric field as well as the environment.

Oxidized film structure and method of making epitaxial metal oxide structure

DOEpatents

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

2003-02-25

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

Conducting metal oxide and metal nitride nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst supportmore » in a fuel cell.« less

Oxidation of silicon nitride sintered with rare-earth oxide additions

NASA Technical Reports Server (NTRS)

Mieskowski, D. M.; Sanders, W. A.

1985-01-01

The effects of rare-earth oxide additions on the oxidation of sintered Si3N4 were examined. Insignificant oxidation occurred at 700 and 1000 C, with no evidence of phase instability. At 1370 C, the oxidation rate was lowest for Y2O3 and increased for additions of La2O3, Sm2O3, and CeO2, in that order. Data obtained from X-ray diffraction, electron microprobe analysis, and scanning electron microscopy indicate that oxidation occurs via diffusion of cationic species from Si3N4 grain boundaries.

Rare-earth gate oxides for GaAs MOSFET application

NASA Astrophysics Data System (ADS)

Kwon, Kwang-Ho; Yang, Jun-Kyu; Park, Hyung-Ho; Kim, Jongdae; Roh, Tae Moon

2006-08-01

Rare-earth oxide films for gate dielectric on n-GaAs have been investigated. The oxide films were e-beam evaporated on S-passivated GaAs, considering interfacial chemical bonding state and energy band structure. Rare-earth oxides such as Gd 2O 3, (Gd xLa 1- x) 2O 3, and Gd-silicate were employed due to high resistivity and no chemical reaction with GaAs. Structural and bonding properties were characterized by X-ray photoemission, absorption, and diffraction. The electrical characteristics of metal-oxide-semiconductor (MOS) diodes were correlated with material properties and energy band structures to guarantee the feasibility for MOS field effect transistor (FET) application. Gd 2O 3 films were grown epitaxially on S-passivated GaAs (0 0 1) at 400 °C. The passivation induced a lowering of crystallization temperature with an epitaxial relationship of Gd 2O 3 (4 4 0) and GaAs (0 0 1). A better lattice matching relation between Gd 2O 3 and GaAs substrate was accomplished by the substitution of Gd with La, which has larger ionic radius. The in-plane relationship of (Gd xLa 1- x) 2O 3 (4 4 0) with GaAs (0 0 1) was found and the epitaxial films showed an improved crystalline quality. Amorphous Gd-silicate film was synthesized by the incorporation of SiO 2 into Gd 2O 3. These amorphous Gd-silicate films excluded defect traps or current flow path due to grain boundaries and showed a relatively larger energy band gap dependent on the contents of SiO 2. Energy band parameters such as Δ EC, Δ EV, and Eg were effectively controlled by the film composition.

Process for producing metal compounds from graphite oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

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

Process for Producing Metal Compounds from Graphite Oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

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

40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from the...

40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from the...

40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from the...

40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from the...

40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare earth metals subcategory. The provisions of this subpart are applicable to discharges resulting from the...

High surface area, electrically conductive nanocarbon-supported metal oxide

DOEpatents

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

2015-07-14

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

High surface area, electrically conductive nanocarbon-supported metal oxide

DOEpatents

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

2014-03-04

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

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

DOEpatents

Poston, J.A.

1997-12-02

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.

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

DOEpatents

Poston, James A.

1997-01-01

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

Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

NASA Astrophysics Data System (ADS)

Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

2016-05-01

Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (nBulk and nSurf) and the adsorption energy of an oxygen atom (Eads) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the nBulk and nSurf with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the Eads on the surfaces was highly correlated with the nBulk with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO3 vs. LaTiO3). These results suggest that a bulk-derived descriptor such as nBulk can be used to screen metal-oxide catalysts.

Rare-Earth Metals and Their Applications in Aviation

DTIC Science & Technology

1984-08-01

metals are not as common as iron and steel which are visible everywhere, yet they are not unfamiliar to us. We often encounter them in everyday life...the flint of a lighter. It is an alloy of rare-earth metal and iron . It contains about 30% iron and the remainder is a composite rare-earth alloy...used to manufacture the detonators of bullets and shells as well as the pyrophoric alloys of firing devices. This type of alloy has a 49.5% content of

Quantum Mechanical Studies of Large Metal, Metal Oxide, and Metal Chalcogenide Nanoparticles and Clusters

DOE PAGES

Fernando, Amendra; Weerawardene, K. L. Dimuthu M.; Karimova, Natalia V.; ...

2015-04-21

Here, metal, metal oxide, and metal chalcogenide materials have a wide variety of applications. For example, many metal clusters and nanoparticles are used as catalysts for reactions varying from the oxidation of carbon monoxide to the reduction of protons to hydrogen gas. Noble metal nanoparticles have unique optical properties such as a surface plasmon resonance for large nanoparticles that yield applications in sensing and photonics. In addition, a number of transition metal clusters are magnetic. Metal oxide clusters and surfaces are commonly used as catalysts for reactions such as water splitting. Both metal oxide and metal chalcogenide materials can bemore » semiconducting, which leads to applications in sensors, electronics, and solar cells. Many researchers have been interested in studying nanoparticles and/or small clusters of these materials. Some of the system sizes under investigation have been experimentally synthesized, which enables direct theory–experiment comparison. Other clusters that have been examined theoretically are of interest as models of larger systems or surfaces. Often, the size-dependence of their properties such as their HOMO–LUMO gap, magnetic properties, optical properties, etc., is of interest.« less

Oxidation-Mediated Fingering in Liquid Metals

NASA Astrophysics Data System (ADS)

Eaker, Collin B.; Hight, David C.; O'Regan, John D.; Dickey, Michael D.; Daniels, Karen E.

2017-10-01

We identify and characterize a new class of fingering instabilities in liquid metals; these instabilities are unexpected due to the large interfacial tension of metals. Electrochemical oxidation lowers the effective interfacial tension of a gallium-based liquid metal alloy to values approaching zero, thereby inducing drastic shape changes, including the formation of fractals. The measured fractal dimension (D =1.3 ±0.05 ) places the instability in a different universality class than other fingering instabilities. By characterizing changes in morphology and dynamics as a function of droplet volume and applied electric potential, we identify the three main forces involved in this process: interfacial tension, gravity, and oxidative stress. Importantly, we find that electrochemical oxidation can generate compressive interfacial forces that oppose the tensile forces at a liquid interface. The surface oxide layer ultimately provides a physical and electrochemical barrier that halts the instabilities at larger positive potentials. Controlling the competition between interfacial tension and oxidative (compressive) stresses at the interface is important for the development of reconfigurable electronic, electromagnetic, and optical devices that take advantage of the metallic properties of liquid metals.

40 CFR 721.5549 - Lithiated metal oxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN P-96-19...

40 CFR 721.5549 - Lithiated metal oxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN P-96-19...

Promoting effect of alkaline earth metal doping on catalytic activity of HC and NOx conversion over Pd-only three-way catalyst.

PubMed

Yang, Linyan; Lin, Siyu; Yang, Xue; Fang, Weimin; Zhou, Renxian

2014-08-30

The influence of alkaline earth metal (M=Mg, Ca, Sr and Ba) promoter on the structural/textural properties of Ce0.67Zr0.33O2 (designated as CZ) and the catalytic behavior of its supported Pd-only three-way catalyst (Pd/CZM) have been investigated. The results show that the modification with alkaline earth metal obviously improves the catalytic activity for hydrocarbon (HC) and nitrogen oxides (NOx) conversion, especially the introduction of Ba. Furthermore, the operation window of the promoted catalysts has also been widened. The doping of alkaline earth metal leads to the formation of more homogeneous Ce-Zr-M ternary solid solution with higher surface area and smaller crystallite size, and the corresponding Pd/CZM catalysts present improved reducibility of PdO species. The modification with Ca, Sr and Ba improves the thermal aging resistance, especially Ba. DRIFTS results reveal that the doping of alkaline earth metal enhances the oxygen and electron transfer ability and favors the dissociation of NO, which promotes the activation and storage capacity of the acidic atoms like NOx, and leads to enhanced catalytic activity performance. Copyright © 2014 Elsevier B.V. All rights reserved.

Timing the oxidation of Earth's crust: Evidence from big data records of manganese mineralization

NASA Astrophysics Data System (ADS)

Hummer, D. R.; Golden, J. J.; Hystad, G.; Downs, R. T.; Eleish, A.; Liu, C.; Ralph, J.; Morrison, S.; Meyer, M.; Hazen, R. M.

2017-12-01

A great deal of work has focused on unravelling the oxygenation of Earth's early atmosphere and oceans, which took place during and after the Great Oxidation Event (1). Recently, field and experimental methods have also been used to examine the timing of mantle oxidation, especially near subduction zones (2). However, very little information is available on the timing of crustal oxidation. To examine the oxidation of Earth's shallow crust, we analyzed records of manganese (Mn) mineral occurrences across geologic time from a database of 2666 mineral-locality data pairs (mindat.org as of 20 Nov. 2015) that had associated geologic ages in the literature. Manganese is a redox-sensitive transition element with oxidation states of +2, +3, and +4, whose average oxidation state in the geologic record can be used as a proxy for the oxygenation of the shallow crust, where Mn mineralization typically occurs. Analysis revealed that Mn mineralization older than 600 Ma contained mostly Mn2+ mineral species, with isolated localities containing Mn3+ and Mn4+ species. During the Phanerozoic, the average oxidation state of Mn follows the same trend as reconstructions of atmospheric oxygen (3), but on a 66+1 Myr delay (as calculated using a least squares fitting procedure). This contrasts with a delay of hundreds of millions of years for the oxidation of molybdenum, which forms much deeper in the crust (4). We interpret these time lags as the time necessary to equilibrate various crustal depths to atmospheric oxygen fugacity through infiltration of oxidizing fluids and tectonic mixing processes. Analysis of other redox-sensitive transition metals (such as Cr, V, and Fe) using big data techniques may reveal a strategy for timing the oxidation of different portions of Earth's crust. (1) T.W. Lyons, C.T. Reinhard, N.J. Planavsky, Nature 506, 307-315 (2014). (2) M. Brounce, et al. Geology 43, 775-778 (2015). (3) N.M. Bergman, T.M. Lenton, A.J. Watson, Am. J. Sci. 304, 397-437 (2004). (4

Process optimization and kinetics for leaching of rare earth metals from the spent Ni-metal hydride batteries.

PubMed

Meshram, Pratima; Pandey, B D; Mankhand, T R

2016-05-01

Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features. Copyright © 2015. Published by Elsevier Ltd.

High temperature, oxidation resistant noble metal-Al alloy thermocouple

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

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

DOE PAGES

Chen, Wei; Wang, Haotian; Li, Yuzhang; ...

2015-07-15

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

Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

NASA Technical Reports Server (NTRS)

Bill, R. C.

1974-01-01

Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development.

Unified computational model of transport in metal-insulating oxide-metal systems

NASA Astrophysics Data System (ADS)

Tierney, B. D.; Hjalmarson, H. P.; Jacobs-Gedrim, R. B.; Agarwal, Sapan; James, C. D.; Marinella, M. J.

2018-04-01

A unified physics-based model of electron transport in metal-insulator-metal (MIM) systems is presented. In this model, transport through metal-oxide interfaces occurs by electron tunneling between the metal electrodes and oxide defect states. Transport in the oxide bulk is dominated by hopping, modeled as a series of tunneling events that alter the electron occupancy of defect states. Electron transport in the oxide conduction band is treated by the drift-diffusion formalism and defect chemistry reactions link all the various transport mechanisms. It is shown that the current-limiting effect of the interface band offsets is a function of the defect vacancy concentration. These results provide insight into the underlying physical mechanisms of leakage currents in oxide-based capacitors and steady-state electron transport in resistive random access memory (ReRAM) MIM devices. Finally, an explanation of ReRAM bipolar switching behavior based on these results is proposed.

Metal oxide composite dosimeter method and material

DOEpatents

Miller, Steven D.

1998-01-01

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

Interfacial Metal-Oxide Interactions in Resistive Switching Memories.

PubMed

Cho, Deok-Yong; Luebben, Michael; Wiefels, Stefan; Lee, Kug-Seung; Valov, Ilia

2017-06-07

Metal oxides are commonly used as electrolytes for redox-based resistive switching memories. In most cases, non-noble metals are directly deposited as ohmic electrodes. We demonstrate that irrespective of bulk thermodynamics predictions an intermediate oxide film a few nanometers in thickness is always formed at the metal/insulator interface, and this layer significantly contributes to the development of reliable switching characteristics. We have tested metal electrodes and metal oxides mostly used for memristive devices, that is, Ta, Hf, and Ti and Ta 2 O 5 , HfO 2 , and SiO 2 . Intermediate oxide layers are always formed at the interfaces, whereas only the rate of the electrode oxidation depends on the oxygen affinity of the metal and the chemical stability of the oxide matrix. Device failure is associated with complete transition of short-range order to a more disordered main matrix structure.

Charge transport in metal oxide nanocrystal-based materials

NASA Astrophysics Data System (ADS)

Runnerstrom, Evan Lars

There is probably no class of materials more varied, more widely used, or more ubiquitous than metal oxides. Depending on their composition, metal oxides can exhibit almost any number of properties. Of particular interest are the ways in which charge is transported in metal oxides: devices such as displays, touch screens, and smart windows rely on the ability of certain metal oxides to conduct electricity while maintaining visible transparency. Smart windows, fuel cells, and other electrochemical devices additionally rely on efficient transport of ionic charge in and around metal oxides. Colloidal synthesis has enabled metal oxide nanocrystals to emerge as a relatively new but highly tunable class of materials. Certain metal oxide nanocrystals, particularly highly doped metal oxides, have been enjoying rapid development in the last decade. As in myriad other materials systems, structure dictates the properties of metal oxide nanocrystals, but a full understanding of how nanocrystal synthesis, the processing of nanocrystal-based materials, and the structure of nanocrystals relate to the resulting properties of nanocrystal-based materials is still nascent. Gaining a fundamental understanding of and control over these structure-property relationships is crucial to developing a holistic understanding of metal oxide nanocrystals. The unique ability to tune metal oxide nanocrystals by changing composition through the introduction of dopants or by changing size and shape affords a way to study the interplay between structure, processing, and properties. This overall goal of this work is to chemically synthesize colloidal metal oxide nanocrystals, process them into useful materials, characterize charge transport in materials based on colloidal metal oxide nanocrystals, and develop ways to manipulate charge transport. In particular, this dissertation characterizes how the charge transport properties of metal oxide nanocrystal-based materials depend on their processing and

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

PubMed

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

2013-04-05

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

Wide-band-gap, alkaline-earth-oxide semiconductor and devices utilizing same

DOEpatents

Abraham, Marvin M.; Chen, Yok; Kernohan, Robert H.

1981-01-01

This invention relates to novel and comparatively inexpensive semiconductor devices utilizing semiconducting alkaline-earth-oxide crystals doped with alkali metal. The semiconducting crystals are produced by a simple and relatively inexpensive process. As a specific example, a high-purity lithium-doped MgO crystal is grown by conventional techniques. The crystal then is heated in an oxygen-containing atmosphere to form many [Li].degree. defects therein, and the resulting defect-rich hot crystal is promptly quenched to render the defects stable at room temperature and temperatures well above the same. Quenching can be effected conveniently by contacting the hot crystal with room-temperature air.

Evolution of the Oxidation State of the Earth's Mantle

NASA Technical Reports Server (NTRS)

Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, E.; Rahman, Z.

2015-01-01

The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3(+) at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. In our previous experiments on shergottite compositions, variable fO2, T, and P less than 4 GPa, Fe3(+)/sigma Fe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3(+)/sigma Fe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3(+). Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Preliminary multi-anvil experiments with Knippa basalt as the starting composition were conducted at 5-7 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal to Fe3(+)/2(+). Experiments are underway to produce glassy samples that can be measured by EELS and XANES, and are conducted at higher pressures.

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

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

NASA Astrophysics Data System (ADS)

Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

2014-05-01

The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

Synthesis of Oxides Containing Transition Metals

DTIC Science & Technology

1990-07-09

metal oxide single crystals by the electrolysis of molten salts containing mixtures of the appropriate oxides. Andreiux and Bozon (33-34) were able to...examples of unusual transition metal oxides which can be prepared (usually as single crystals) by electrolysis of fused salts . Summary The methods of...ferrites with the composition MFe 204 involved the thermal decomposition of oxalate (3) or pyridinate salts (1). The synthesis of ferrites from mixed

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

Crystallographic phases in heavy rare earth metals under megabar pressures

NASA Astrophysics Data System (ADS)

Samudrala, G. K.; Vohra, Y. K.

2012-07-01

Experiments aimed at understanding the crystallographic phases of heavy rare earth metals were carried out in a diamond anvil cell at the Advanced Photon Source, Argonne National Laboratory. Heavy rare earth metals dysprosium (Dy), holmium (Ho), erbium (Er) and thulium (Tm) were compressed to multi-megabar pressures. The rare earth crystal sequence hcp→Sm-type→dhcp→distorted-fcc (dfcc) is observed in all four elements. Upon further compression, a structural transformation to a monoclinic C2/m phase has been observed. We summarize the results from these experiments and present Rietveld structural refinements on high pressure phases for the specific case of dysprosium.

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

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

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

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

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

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

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

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

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

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

Ammonia release method for depositing metal oxides

DOEpatents

Silver, Gary L.; Martin, Frank S.

1994-12-13

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

Dextran templating for the synthesis of metallic and metal oxide sponges

NASA Astrophysics Data System (ADS)

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

2003-06-01

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

Direct electrochemical reduction of metal-oxides

DOEpatents

Redey, Laszlo I.; Gourishankar, Karthick

2003-01-01

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

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

NASA Technical Reports Server (NTRS)

Herz, Richard K.

1990-01-01

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

Metal-insulator and charge ordering transitions in oxide nanostructures

NASA Astrophysics Data System (ADS)

Singh, Sujay Kumar

Strongly correlated oxides are a class of materials wherein interplay of various degrees of freedom results in novel electronic and magnetic phenomena. Vanadium oxides are widely studied correlated materials that exhibit metal-insulator transitions (MIT) in a wide temperature range from 70 K to 380 K. In this Thesis, results from electrical transport measurements on vanadium dioxide (VO2) and vanadium oxide bronze (MxV 2O5) (where M: alkali, alkaline earth, and transition metal cations) are presented and discussed. Although the MIT in VO2 has been studied for more than 50 years, the microscopic origin of the transition is still debated since a slew of external parameters such as light, voltage, and strain are found to significantly alter the transition. Furthermore, recent works on electrically driven switching in VO2 have shown that the role of Joule heating to be a major cause as opposed to electric field. We explore the mechanisms behind the electrically driven switching in single crystalline nanobeams of VO2 through DC and AC transport measurements. The harmonic analysis of the AC measurement data shows that non-uniform Joule heating causes electronic inhomogeneities to develop within the nanobeam and is responsible for driving the transition in VO2. Surprisingly, field assisted emission mechanisms such as Poole-Frenkel effect is found to be absent and the role of percolation is also identified in the electrically driven transition. This Thesis also provides a new insight into the mechanisms behind the electrolyte gating induced resistance modulation and the suppression of MIT in VO2. We show that the metallic phase of VO2 induced by electrolyte gating is due to an electrochemical process and can be both reversible and irreversible under different conditions. The kinetics of the redox processes increase with temperature; a complete suppression of the transition and the stabilization of the metallic phase are achievable by gating in the rutile metallic phase

Phase Transformations and Metallization of Magnesium Oxide at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

McWilliams, R. Stewart; Spaulding, Dylan K.; Eggert, Jon H.; Celliers, Peter M.; Hicks, Damien G.; Smith, Raymond F.; Collins, Gilbert W.; Jeanloz, Raymond

2012-12-01

Magnesium oxide (MgO) is representative of the rocky materials comprising the mantles of terrestrial planets, such that its properties at high temperatures and pressures reflect the nature of planetary interiors. Shock-compression experiments on MgO to pressures of 1.4 terapascals (TPa) reveal a sequence of two phase transformations: from B1 (sodium chloride) to B2 (cesium chloride) crystal structures above 0.36 TPa, and from electrically insulating solid to metallic liquid above 0.60 TPa. The transitions exhibit large latent heats that are likely to affect the structure and evolution of super-Earths. Together with data on other oxide liquids, we conclude that magmas deep inside terrestrial planets can be electrically conductive, enabling magnetic field-producing dynamo action within oxide-rich regions and blurring the distinction between planetary mantles and cores.

Synthesis and applications of nanoporous perovskite metal oxides

PubMed Central

Huang, Xiubing; Zhao, Guixia

2018-01-01

Perovskite-type metal oxides have been widely investigated and applied in various fields in the past several decades due to their extraordinary variability of compositions and structures with targeted physical and chemical properties (e.g., redox behaviour, oxygen mobility, electronic and ionic conductivity). Recently, nanoporous perovskite metal oxides have attracted extensive attention because of their special morphology and properties, as well as superior performance. This minireview aims at summarizing and reviewing the different synthesis methods of nanoporous perovskite metal oxides and their various applications comprehensively. The correlations between the nanoporous structures and the specific performance of perovskite oxides are summarized and highlighted. The future research directions of nanoporous perovskite metal oxides are also prospected. PMID:29862001

Ammonia release method for depositing metal oxides

DOEpatents

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

1994-12-13

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

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

PubMed

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

Metal/oxide interfacial effects on the selective oxidation of primary alcohols

PubMed Central

Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

2017-01-01

A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O–H and C–H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged. PMID:28098146

Charge transfer in rare earth oxide hybrid solar cells revealed through ultrafast spectroscopic measurement

NASA Astrophysics Data System (ADS)

Pandit, Bill; Fernando, Kasun; Alphenaar, Bruce; Liu, Jinjun

2014-03-01

Hybrid inorganic-organic solar cells typically combine a transition metal oxide (such as TiO2) and organic dye or polymer absorber to form the donor acceptor pair. Here, Oxidized neodymium (Nd2O3) particles are combined with [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) to form the active layer of a bulk heterojunction solar cell. The addition of the Nd2O3 results in an enhancement in the short circuit current and open circuit voltage compared to pure PCBM. We also studied the ultrafast dynamics of photoexcitation in pristine PCBM film, and their blends with the rare earth oxide neodymium particles using the pump-probe photomodulation (PM) spectroscopy with ~30 fs time resolution. Our transient PM spectrum covers spectral range of 430 nm to 730 nm. Although the spectra of Nd2O3/PCBM are very similar with pristine PCBM, the recombination kinetics of photogenerated excitons decay rate increases with the addition of Nd2O3, and ground state photobleaching is also observed. Taken together this provides evidence for the charge transfer between the organic and rare earth inorganic components. Supported by the DOE-EPSCoR fund DOE BES (DE-FG02-07ER46375) at University of Louisville.

Selective Aerobic Oxidation of Alcohols over Atomically-Dispersed Non-Precious Metal Catalysts

DOE PAGES

Xie, Jiahan; Yin, Kehua; Serov, Alexey; ...

2016-12-15

Catalytic oxidation of alcohols often requires the presence of expensive transition metals. We show that earth-abundant Fe atoms dispersed throughout a nitrogen-containing carbon matrix catalyze the oxidation of benzyl alcohol and 5-hydroxymethylfurfural by O 2 in the aqueous phase. Furthermore, the activity of the catalyst can be regenerated by a mild treatment in H 2. An observed kinetic isotope effect indicates that β-H elimination from the alcohol is the kinetically relevant step in the mechanism, which can be accelerated by substituting Fe with Cu. Dispersed Cr, Co, and Ni also convert alcohols, demonstrating the general utility of metal–nitrogen–carbon materials formore » alcohol oxidation catalysis. Oxidation of aliphatic alcohols is substantially slower than that of aromatic alcohols, but adding 2,2,6,6-tetramethyl-1-piperidinyloxy as a co-catalyst with Fe can significantly improve the reaction rate.« less

Three-electrode metal oxide reduction cell

DOEpatents

Dees, Dennis W.; Ackerman, John P.

2008-08-12

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

Three-Electrode Metal Oxide Reduction Cell

DOEpatents

Dees, Dennis W.; Ackerman, John P.

2005-06-28

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

Recent applications of liquid metals featuring nanoscale surface oxides

NASA Astrophysics Data System (ADS)

Neumann, Taylor V.; Dickey, Michael D.

2016-05-01

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

Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

1996-01-01

A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

NASA Astrophysics Data System (ADS)

Renaud, Gilles

Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

Lithium metal oxide electrodes for lithium batteries

DOEpatents

Thackeray, Michael M [Naperville, IL; Kim, Jeom-Soo [Naperville, IL; Johnson, Christopher S [Naperville, IL

2008-01-01

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

Chlorination of UO 2, PuO 2 and rare earth oxides using ZrCl 4 in LiCl-KCl eutectic melt

NASA Astrophysics Data System (ADS)

Sakamura, Yoshiharu; Inoue, Tadashi; Iwai, Takashi; Moriyama, Hirotake

2005-04-01

A new chlorination method using ZrCl 4 in a molten salt bath has been investigated for the pyrometallurgical reprocessing of nuclear fuels. ZrCl 4 has a high reactivity with oxygen but is not corrosive to refractory metals such as steel. Rare earth oxides (La 2O 3, CeO 2, Nd 2O 3 and Y 2O 3) and actinide oxides (UO 2 and PuO 2) were allowed to react with ZrCl 4 in a LiCl-KCl eutectic salt at 773 K to give a metal chloride solution and a precipitate of ZrO 2. An addition of zirconium metal as a reductant was effective in chlorinating the dioxides. When the oxides were in powder form, the reaction was observed to progress rapidly. Cyclic voltammetry provided a convenient way of establishing when the reaction was completed. It was demonstrated that the ZrCl 4 chlorination method, free from corrosive gas, was very simple and useful.

Metal-oxide-based energetic materials and synthesis thereof

DOEpatents

Tillotson, Thomas M. , Simpson; Randall, L [Livermore, CA; Hrubesh, Lawrence W [Pleasanton, CA

2006-01-17

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

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

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

1994-01-11

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

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †.

PubMed

Afzal, Adeel; Dickert, Franz L

2018-04-20

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed.

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †

PubMed Central

2018-01-01

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed. PMID:29677107

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, C.; Eldik, R. van

1995-01-01

The transition metal-catalyzed oxidation of sulfur(IV) oxides has been known for more than 100 years. There is a significant lack of information on the actual role of the transition metal-catalyzed reactions, and much of the earlier work was performed without a detailed knowledge of the chemical system. For this reason attention is focused on the role of transition metal ions in the oxidation of sulfur(IV) oxides in terms of the coordination chemistry involved, as well as the stability and chemical behavior of the various participating species. The oxidation process of sulfur(IV) oxides plays an important role in atmospheric chemistry (e.g.more » acid rain formation) as well as industrial processes (e.g. desulfurization of plume gases and ore). The present report deals with the mechanism of the transition metal-catalyzed oxidation of sulfur(IV) oxides with the aim to discuss this in terms of atmospheric and chemical processes. In addition, the authors would like to emphasize the key role of oxygen in these processes. 1,076 refs.« less

Metal ion binding to iron oxides

NASA Astrophysics Data System (ADS)

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

2006-06-01

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

Method for converting uranium oxides to uranium metal

DOEpatents

Duerksen, Walter K.

1988-01-01

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

Lithium metal oxide electrodes for lithium batteries

DOEpatents

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

2010-06-08

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

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, James W.

1992-01-01

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

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, J.W.

1992-09-15

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

Nanocomposite of graphene and metal oxide materials

DOEpatents

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

2013-10-15

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

Nanocomposite of graphene and metal oxide materials

DOEpatents

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

2012-09-04

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

Nanocomposite of graphene and metal oxide materials

DOEpatents

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

2015-06-30

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

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

Ott, Kevin C.; Kodas, Toivo T.

1994-01-01

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

Metals, toxicity and oxidative stress.

PubMed

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

2005-01-01

Metal-induced toxicity and carcinogenicity, with an emphasis on the generation and role of reactive oxygen and nitrogen species, is reviewed. Metal-mediated formation of free radicals causes various modifications to DNA bases, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Lipid peroxides, formed by the attack of radicals on polyunsaturated fatty acid residues of phospholipids, can further react with redox metals finally producing mutagenic and carcinogenic malondialdehyde, 4-hydroxynonenal and other exocyclic DNA adducts (etheno and/or propano adducts). Whilst iron (Fe), copper (Cu), chromium (Cr), vanadium (V) and cobalt (Co) undergo redox-cycling reactions, for a second group of metals, mercury (Hg), cadmium (Cd) and nickel (Ni), the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. Arsenic (As) is thought to bind directly to critical thiols, however, other mechanisms, involving formation of hydrogen peroxide under physiological conditions, have been proposed. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. Common mechanisms involving the Fenton reaction, generation of the superoxide radical and the hydroxyl radical appear to be involved for iron, copper, chromium, vanadium and cobalt primarily associated with mitochondria, microsomes and peroxisomes. However, a recent discovery that the upper limit of "free pools" of copper is far less than a single atom per cell casts serious doubt on the in vivo role of copper in Fenton-like generation of free radicals. Nitric oxide (NO) seems to be involved in arsenite-induced DNA damage and pyrimidine excision inhibition. Various studies have confirmed that metals activate signalling pathways and the carcinogenic effect of metals has been related to activation of mainly redox-sensitive transcription factors, involving NF-kappaB, AP-1 and p53

Internal zone growth method for producing metal oxide metal eutectic composites

DOEpatents

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

1980-01-01

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

Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

PubMed

Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

2015-11-16

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated "metallic" oxides.

PubMed

Apgar, Brent A; Lee, Sungki; Schroeder, Lauren E; Martin, Lane W

2013-11-20

n-n Schottky, n-n ohmic, and p-n Schottky heterojunctions based on TiO2 /correlated "metallic" oxide couples exhibit strong solar-light absorption driven by the unique electronic structure of the "metallic" oxides. Photovoltaic and photocatalytic responses are driven by hot electron injection from the "metallic" oxide into the TiO2 , enabling new modalities of operation for energy systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Code of Federal Regulations, 2014 CFR

2014-07-01

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

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

Code of Federal Regulations, 2013 CFR

2013-07-01

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

Asymmetric Catalysis with bis(hydroxyphenyl)diamides/rare-earth metal complexes.

PubMed

Kumagai, Naoya; Shibasaki, Masakatsu

2013-01-02

A series of asymmetric catalysts composed of conformationally flexible amide-based chiral ligands and rare-earth metals was developed for proton-transfer catalysis. These ligands derived from amino acids provide an intriguing chiral platform for the formation of asymmetric catalysts upon complexation with rare-earth metals. The scope of this arsenal of catalysts was further broadened by the development of heterobimetallic catalytic systems. The cooperative function of hydrogen bonding and metal coordination resulted in intriguing substrate specificity and stereocontrol, and the dynamic nature of the catalysts led to a switch of their function. Herein, we summarize our recent exploration of this class of catalysts. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Process for etching mixed metal oxides

DOEpatents

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

1994-01-01

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

IRIS TOXICOLOGICAL REVIEW AND SUMMARY DOCUMENTS FOR CERIUM OXIDE (STABLE) AND COMPOUNDS

EPA Science Inventory

Cerium is a member of the lanthanoid series of rare earth metals. It is also the most abundant and most reactive of the rare earth metals. Cerium oxidizes at room temperature and forms a variety of salt compounds including oxides, hydroxides, sulfates and chlorides. Cerium is ...

Application of a mixed metal oxide catalyst to a metallic substrate

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Method for inhibiting oxidation of metal sulfide-containing material

DOEpatents

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

2006-12-26

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

Rare earth-transition metal scrap treatment method

DOEpatents

Schmidt, Frederick A.; Peterson, David T.; Wheelock, John T.; Jones, Lawrence L.; Lincoln, Lanny P.

1992-02-11

Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets.

Rare earth-transition metal scrap treatment method

DOEpatents

Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.; Lincoln, L.P.

1992-02-11

Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. 3 figs.

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

NASA Astrophysics Data System (ADS)

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

2012-07-01

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.

Effects of rare earth doping on multi-core iron oxide nanoparticles properties

NASA Astrophysics Data System (ADS)

Petran, Anca; Radu, Teodora; Borodi, Gheorghe; Nan, Alexandrina; Suciu, Maria; Turcu, Rodica

2018-01-01

New multi-core iron oxide magnetic nanoparticles doped with rare earth metals (Gd, Eu) were obtained by a one step synthesis procedure using a solvothermal method for potential biomedical applications. The obtained clusters were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS) and magnetization measurements. They possess high colloidal stability, a saturation magnetization of up to 52 emu/g, and nearly spherical shape. The presence of rare earth ions in the obtained samples was confirmed by EDX and XPS. XRD analysis proved the homogeneous distribution of the trivalent rare earth ions in the inverse-spinel structure of magnetite and the increase of crystal strain upon doping the samples. XPS study reveals the valence state and the cation distribution on the octahedral and tetrahedral sites of the analysed samples. The observed shift of the XPS valence band spectra maximum in the direction of higher binding energies after rare earth doping, as well as theoretical valence band calculations prove the presence of Gd and Eu ions in octahedral sites. The blood protein adsorption ability of the obtained samples surface, the most important factor of the interaction between biomaterials and body fluids, was assessed by interaction with bovine serum albumin (BSA). The rare earth doped clusters surface show higher afinity for binding BSA. In vitro cytotoxicity test results for the studied samples showed no cytotoxicity in low and medium doses, establishing a potential perspective for rare earth doped MNC to facilitate multiple therapies in a single formulation for cancer theranostics.

Process for etching mixed metal oxides

DOEpatents

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

1994-10-18

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

Metal Oxide Solubility and Molten Salt Corrosion.

DTIC Science & Technology

1982-03-29

METAL OXIDE SOLUBILITY AND MOLTEN SALT CORROSION .(U) MAR 82 K H STERN UNCLASSI E DL R L-4772NL EL .2. MICROCOPY RESOLUTION TEST CHART NATIONAL BURALU...21 l 7 3 ..... l DTIC NSPECT I" ’I cCPY INSECE( METAL OXIDE SOLUBILITY AND MOLTEN SALT CORROSION I. INTRODUCTION Molten ...discussed in terms of its importance to the understanding of molten salt corrosion . II. PROTECTIVE COATINGS Since most structural metals and alloys are

Polymer-assisted aqueous deposition of metal oxide films

DOEpatents

Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

2003-07-08

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

Transition Metal Oxides as Electrocatalysts for the Oxygen Evolution Reaction in Alkaline Solutions: An Application-Inspired Renaissance.

PubMed

Song, Fang; Bai, Lichen; Moysiadou, Aliki; Lee, Seunghwa; Hu, Chao; Liardet, Laurent; Hu, Xile

2018-06-27

Water splitting is the essential chemical reaction to enable the storage of intermittent energies such as solar and wind in the form of hydrogen fuel. The oxygen evolution reaction (OER) is often considered as the bottleneck in water splitting. Though metal oxides had been reported as OER electrocatalysts more than half a century ago, the recent interest in renewable energy storage has spurred a renaissance of the studies of transition metal oxides as Earth-abundant and nonprecious OER catalysts. This Perspective presents major progress in several key areas of the field such as theoretical understanding, activity trend, in situ and operando characterization, active site determination, and novel materials. A personal overview of the past achievements and future challenges is also provided.

Electrochromic device containing metal oxide nanoparticles and ultraviolet blocking material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Guillermo; Koo, Bonil; Gregoratto, Ivano

An electrochromic device includes a nanostructured transition metal oxide bronze layer that includes one or more transition metal oxide and one or more dopant. The electrochromic device also includes nanoparticles containing one or more transparent conducting oxide (TCO), a solid state electrolyte, a counter electrode, and at least one protective layer to prevent degradation of the one or more nanostructured transition metal oxide bronze. The nanostructured transition metal oxide bronze selectively modulates transmittance of near-infrared (NIR) and visible radiation as a function of an applied voltage to the device.

Method for making monolithic metal oxide aerogels

DOEpatents

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

1995-03-07

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

Method for making monolithic metal oxide aerogels

DOEpatents

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

1995-01-01

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

Conductive metal oxide film and method of making

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windisch, C.F. Jr.; Exarhos, G.J.

1999-11-23

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

Conductive metal oxide film and method of making

DOEpatents

Windisch, Jr., Charles F.; Exarhos, Gregory J.

1999-01-01

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

Synthesis of metal-metal oxide catalysts and electrocatalysts using a metal cation adsorption/reduction and adatom replacement by more noble ones

DOEpatents

Adzic, Radoslav; Vukmirovic, Miomir; Sasaki, Kotaro

2010-04-27

The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen. The invention also relates to methods of making the metal-metal oxide composites.

PROCESS OF PRODUCING ACTINIDE METALS

DOEpatents

Magel, T.T.

1959-07-14

The preparation of actinide metals in workable, coherent form is described. In general, the objects of the invention are achieved by heating a mixture of an oxide and a halide of an actinide metal such as uranium with an alkali metal on alkaline earth metal reducing agent in the presence of iodine.

From Oxygen Generation to Metals Production: In Situ Resource Utilization by Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Khetpal, Deepak; Ducret, Andrew C.; Sadoway, Donald R.

2003-01-01

For the exploration of other bodies in the solar system, electrochemical processing is arguably the most versatile technology for conversion of local resources into usable commodities: by electrolysis one can, in principle, produce (1) breathable oxygen, (2) silicon for the fabrication of solar cells, (3) various reactive metals for use as electrodes in advanced storage batteries, and (4) structural metals such as steel and aluminum. Even so, to date there has been no sustained effort to develop such processes, in part due to the inadequacy of the database. The objective here is to identify chemistries capable of sustaining molten oxide electrolysis in the cited applications and to examine the behavior of laboratory-scale cells designed to generate oxygen and to produce metal. The basic research includes the study of the underlying high-temperature physical chemistry of oxide melts representative of lunar regolith and of Martian soil. To move beyond empirical approaches to process development, the thermodynamic and transport properties of oxide melts are being studied to help set the limits of composition and temperature for the processing trials conducted in laboratory-scale electrolysis cells. The goal of this investigation is to deliver a working prototype cell that can use lunar regolith and Martian soil to produce breathable oxygen along with metal by-product. Additionally, the process can be generalized to permit adaptation to accommodate different feedstock chemistries, such as those that will be encountered on other bodies in the solar system. The expected results of this research include: (1) the identification of appropriate electrolyte chemistries; (2) the selection of candidate anode and cathode materials compatible with electrolytes named above; and (3) performance data from a laboratory-scale cell producing oxygen and metal. On the strength of these results it should be possible to assess the technical viability of molten oxide electrolysis for in

Method of producing solution-derived metal oxide thin films

DOEpatents

Boyle, Timothy J.; Ingersoll, David

2000-01-01

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

SEPARATION OF METAL SALTS BY ADSORPTION

DOEpatents

Gruen, D.M.

1959-01-20

It has been found that certain metal salts, particularly the halides of iron, cobalt, nickel, and the actinide metals, arc readily absorbed on aluminum oxide, while certain other salts, particularly rare earth metal halides, are not so absorbed. Use is made of this discovery to separate uranium from the rare earths. The metal salts are first dissolved in a molten mixture of alkali metal nitrates, e.g., the eutectic mixture of lithium nitrate and potassium nitrate, and then the molten salt solution is contacted with alumina, either by slurrying or by passing the salt solution through an absorption tower. The process is particularly valuable for the separation of actinides from lanthanum-group rare earths.

Two-billion-year-old evaporites capture Earth's great oxidation.

PubMed

Blättler, C L; Claire, M W; Prave, A R; Kirsimäe, K; Higgins, J A; Medvedev, P V; Romashkin, A E; Rychanchik, D V; Zerkle, A L; Paiste, K; Kreitsmann, T; Millar, I L; Hayles, J A; Bao, H; Turchyn, A V; Warke, M R; Lepland, A

2018-04-20

Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era (2.5 to 1.6 billion years ago). Increasing oxidation dramatically changed Earth's surface, but few quantitative constraints exist on this important transition. This study describes the sedimentology, mineralogy, and geochemistry of a 2-billion-year-old, ~800-meter-thick evaporite succession from the Onega Basin in Russian Karelia. The deposit consists of a basal unit dominated by halite (~100 meters) followed by units dominated by anhydrite-magnesite (~500 meters) and dolomite-magnesite (~200 meters). The evaporite minerals robustly constrain marine sulfate concentrations to at least 10 millimoles per kilogram of water, representing an oxidant reservoir equivalent to more than 20% of the modern ocean-atmosphere oxidizing capacity. These results show that substantial amounts of surface oxidant accumulated during this critical transition in Earth's oxygenation. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Method of producing adherent metal oxide coatings on metallic surfaces

DOEpatents

Lane, Michael H.; Varrin, Jr., Robert D.

2001-01-01

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.

Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

PubMed

Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

2016-04-05

Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal oxide porous ceramic membranes with small pore sizes

DOEpatents

Anderson, Marc A.; Xu, Qunyin

1992-01-01

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

Metal oxide porous ceramic membranes with small pore sizes

DOEpatents

Anderson, Marc A.; Xu, Qunyin

1991-01-01

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

STABILIZED RARE EARTH OXIDES FOR A CONTROL ROD AND METHOD OF PREPARATION

DOEpatents

McNees, R.A.; Potter, R.A.

1964-01-14

A method is given for preparing mixed oxides of the formula MR/sub x/O/ sub 12/ wherein M is tungsten or molybdenum and R is a rare earth in the group consisting of samarium, europium, dysprosium, and gadolinium and x is 4 to 5. Oxides of this formula, and particularly the europiumcontaining species, are useful as control rod material for water-cooled nuclear reactors owing to their stability, favorable nuclear properties, and resistance to hydration. These oxides may be utilized as a dispersion in a stainlesssteel matrix. Preparation of these oxides is effected by blending tungsten oxide or molybdenum oxide with a rare earth oxide, compressing the mixture, and firing at an elevated temperature in an oxygen-containing atmosphere. (AEC)

Method for producing nanostructured metal-oxides

DOEpatents

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

2006-01-17

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

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy.

PubMed

Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

2010-09-07

Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y(2)O(3) and Yb(2)O(3) could cause massive vacuolization. Y(2)O(3) and Yb(2)O(3) treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects.

Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy

PubMed Central

Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

2010-01-01

Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y2O3 and Yb2O3 could cause massive vacuolization. Y2O3 and Yb2O3 treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects. PMID:20856835

Synthesis of Mesoporous Metal Oxides by Structure Replication: Thermal Analysis of Metal Nitrates in Porous Carbon Matrices

PubMed Central

Weinberger, Christian; Roggenbuck, Jan; Hanss, Jan; Tiemann, Michael

2015-01-01

A variety of metal nitrates were filled into the pores of an ordered mesoporous CMK-3 carbon matrix by solution-based impregnation. Thermal conversion of the metal nitrates into the respective metal oxides, and subsequent removal of the carbon matrix by thermal combustion, provides a versatile means to prepare mesoporous metal oxides (so-called nanocasting). This study aims to monitor the thermally induced processes by thermogravimetric analysis (TGA), coupled with mass ion detection (MS). The highly dispersed metal nitrates in the pores of the carbon matrix tend to react to the respective metal oxides at lower temperature than reported in the literature for pure, i.e., carbon-free, metal nitrates. The subsequent thermal combustion of the CMK-3 carbon matrix also occurs at lower temperature, which is explained by a catalytic effect of the metal oxides present in the pores. This catalytic effect is particularly strong for oxides of redox active metals, such as transition group VII and VIII metals (Mn, Fe, Co, Ni), Cu, and Ce. PMID:28347073

Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries.

PubMed

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

2017-05-01

Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal Oxide Gas Sensors: Sensitivity and Influencing Factors

PubMed Central

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

2010-01-01

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

Density functional plus dynamical mean-field theory of the metal-insulator transition in early transition-metal oxides

NASA Astrophysics Data System (ADS)

Dang, Hung T.; Ai, Xinyuan; Millis, Andrew J.; Marianetti, Chris A.

2014-09-01

The combination of density functional theory and single-site dynamical mean-field theory, using both Hartree and full continuous-time quantum Monte Carlo impurity solvers, is used to study the metal-insulator phase diagram of perovskite transition-metal oxides of the form ABO3 with a rare-earth ion A =Sr, La, Y and transition metal B =Ti, V, Cr. The correlated subspace is constructed from atomiclike d orbitals defined using maximally localized Wannier functions derived from the full p-d manifold; for comparison, results obtained using a projector method are also given. Paramagnetic DFT + DMFT computations using full charge self-consistency along with the standard "fully localized limit" (FLL) double counting are shown to incorrectly predict that LaTiO3, YTiO3, LaVO3, and SrMnO3 are metals. A more general examination of the dependence of physical properties on the mean p-d energy splitting, the occupancy of the correlated d states, the double-counting correction, and the lattice structure demonstrates the importance of charge-transfer physics even in the early transition-metal oxides and elucidates the factors underlying the failure of the standard approximations. If the double counting is chosen to produce a p-d splitting consistent with experimental spectra, single-site dynamical mean-field theory provides a reasonable account of the materials properties. The relation of the results to those obtained from "d-only" models in which the correlation problem is based on the frontier orbital p-d antibonding bands is determined. It is found that if an effective interaction U is properly chosen the d-only model provides a good account of the physics of the d1 and d2 materials.

Emerging Applications of Liquid Metals Featuring Surface Oxides

PubMed Central

2014-01-01

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

Development of techniques for processing metal-metal oxide systems

NASA Technical Reports Server (NTRS)

Johnson, P. C.

1976-01-01

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

Metal/metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems

DOEpatents

Park, Paul W.

2004-03-16

A lean NOx catalyst and method of preparing the same is disclosed. The lean NOx catalyst includes a ceramic substrate, an oxide support material, preferably .gamma.-alumina, deposited on the substrate and a metal promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium, cerium, vanadium, oxides thereof, and combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between about 80 to 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.

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

PubMed

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

2015-01-16

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

Defect Chemistry and Plasmon Physics of Colloidal Metal Oxide Nanocrystals.

PubMed

Lounis, Sebastien D; Runnerstrom, Evan L; Llordés, Anna; Milliron, Delia J

2014-05-01

Plasmonic nanocrystals of highly doped metal oxides have seen rapid development in the past decade and represent a class of materials with unique optoelectronic properties. In this Perspective, we discuss doping mechanisms in metal oxides and the accompanying physics of free carrier scattering, both of which have implications in determining the properties of localized surface plasmon resonances (LSPRs) in these nanocrystals. The balance between activation and compensation of dopants limits the free carrier concentration of the most common metal oxides, placing a ceiling on the LSPR frequency. Furthermore, because of ionized impurity scattering of the oscillating plasma by dopant ions, scattering must be treated in a fundamentally different way in semiconductor metal oxide materials when compared with conventional metals. Though these effects are well-understood in bulk metal oxides, further study is needed to understand their manifestation in nanocrystals and corresponding impact on plasmonic properties, and to develop materials that surpass current limitations in free carrier concentration.

Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides

DTIC Science & Technology

1989-08-16

22217 11 TITLE dnrcluae Sec’.r/ 2 ’als.rit,catC Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides...0 d dlentity by block number) FIELD GROUP SUB GROUP Oxidizing Agents, Lithium Oxides I - Deintercalation 19 AbS*RA?, trne on-tsxes~e it necessary...anid enit’y oy 010ck .1Uf~oer. N02+ andMoF6 are shown to be powerful oxidizing agents for the deintercalation of lithium from Li~oO2 an 62Ct . The

Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas.

PubMed

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

2016-04-06

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

Multiscale model of metal alloy oxidation at grain boundaries

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

Method of adhesion between an oxide layer and a metal layer

DOEpatents

Jennison, Dwight R.; Bogicevic, Alexander; Kelber, Jeffry A.; Chambers, Scott A.

2004-09-14

A method of controlling the wetting characteristics and increasing the adhesion between a metal and an oxide layer. By introducing a negatively-charged species to the surface of an oxide layer, layer-by-layer growth of metal deposited onto the oxide surface is promoted, increasing the adhesion strength of the metal-oxide interface. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface as well as react with the negatively charged species, be oxidized, and incorporated on or into the surface of the oxide.

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

DOEpatents

Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

2010-07-13

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

Method for continuous synthesis of metal oxide powders

DOEpatents

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

2015-09-08

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

Field-assisted nanopatterning of metals, metal oxides and metal salts

NASA Astrophysics Data System (ADS)

Liu, Jun-Fu; Miller, Glen P.

2009-02-01

The tip-based nanofabrication method called field-assisted nanopatterning or FAN has now been extended to the transfer of metals, metal oxides and metal salts onto various receiving substrates including highly ordered pyrolytic graphite, passivated gold and indium-tin oxide. Standard atomic force microscope tips were first dip-coated using suspensions of inorganic compounds in solvent. The films prepared in this manner were non-uniform and contained inorganic nanoparticles. Tip-based nanopatterning on chosen substrates was conducted under high electric field conditions. The same tip was used for both nanofabrication and imaging. Arbitrary patterns were formed with dimensions that ranged from tens of microns to sub-20 nm and were controlled by tuning the tip bias during fabrication. Most tip-based nanopatterning techniques are limited in terms of the type of species that can be deposited and the type of substrates onto which the deposition occurs. With the successful deposition of inorganic species reported here, FAN is demonstrated to be a truly versatile tip-based nanofabrication technique that is useful for the deposition of a wide variety of both organic and inorganic species including small molecules, large molecules and polymers.

Semiconducting transition metal oxides.

PubMed

Lany, Stephan

2015-07-22

Open shell transition metal oxides are usually described as Mott or charge transfer insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a correlated gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g. for energy applications. In order to place the 3d orbitals and the sp bands into an integrated picture, band structure calculations should treat both contributions on the same footing and, at the same time, account fully for electron correlation in the 3d shell. Fundamentally, this is a rather daunting task for electronic structure calculations, but quasi-particle energy calculations in GW approximation offer a viable approach for band structure predictions in these materials. Compared to conventional semiconductors, the inherent multivalent nature of transition metal cations is more likely to cause undesirable localization of electron or hole carriers. Therefore, a quantitative prediction of the carrier self-trapping energy is essential for the assessing the semiconducting properties and to determine whether the transport mechanism is a band-like large-polaron conduction or a small-polaron hopping conduction. An overview is given for the binary 3d oxides on how the hybridization between the 3d crystal field symmetries with the O-p orbitals of the ligands affects the effective masses and the likelihood of electron and hole self-trapping, identifying those situations where small masses and band-like conduction are more likely to be expected. The review concludes with an illustration of the implications of the increased electronic complexity of transition metal cations on the defect physics and doping, using

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes.

PubMed

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-08-08

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

Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

PubMed

Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

2015-08-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

When VSEPR Fails: Experimental and Theoretical Investigations of the Behavior of Alkaline-Earth-Metal Acetylides

PubMed Central

Guino-o, Marites A.; Alexander, Jacob S.; McKee, Michael L.; Hope, Håkon; Englich, Ulrich B.

2014-01-01

The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry. PMID:19844925

Corrosion-resistant metal surfaces

DOEpatents

Sugama, Toshifumi [Wading River, NY

2009-03-24

The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

Spin-on metal oxide materials with high etch selectivity and wet strippability

NASA Astrophysics Data System (ADS)

Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

2016-03-01

Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

Metal oxide-encapsulated dye-sensitized photoanodes for dye-sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hupp, Joseph T.; Son, Ho-Jin

2016-01-12

Dye-sensitized semiconducting metal oxide films for photoanodes, photoanodes incorporating the films and DSCs incorporating the photoanodes are provided. Also provided are methods for making the dye sensitized semiconducting metal oxide films. The methods of making the films are based on the deposition of an encapsulating layer of a semiconducting metal oxide around the molecular anchoring groups of photosensitizing dye molecules adsorbed to a porous film of the semiconducting metal oxide. The encapsulating layer of semiconducting metal oxide is formed in such a way that it is not coated over the chromophores of the adsorbed dye molecules and, therefore, allows themore » dye molecules to remain electrochemically addressable.« less

Anaerobic Nitrate-Dependent Metal Bio-Oxidation

NASA Astrophysics Data System (ADS)

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

2007-12-01

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

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

PubMed Central

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

2015-01-01

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ < 400 nm) is blocked to achieve an improved device lifetime. In this work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1–20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated. PMID:25592174

Metal-organic framework derived hollow polyhedron metal oxide posited graphene oxide for energy storage applications.

PubMed

Ramaraju, Bendi; Li, Cheng-Hung; Prakash, Sengodu; Chen, Chia-Chun

2016-01-18

A composite made from hollow polyhedron copper oxide and graphene oxide was synthesized by sintering a Cu-based metal-organic framework (Cu-MOF) embedded with exfoliated graphene oxide. As a proof-of-concept application, the obtained Cu(ox)-rGO materials were used in a lithium-ion battery and a sodium-ion battery as anode materials. Overall, the Cu(ox)-rGO composite delivers excellent electrochemical properties with stable cycling when compared to pure CuO-rGO and Cu-MOF.

Application of Freeze-Dried Powders of Genetically Engineered Microbial Strains as Adsorbents for Rare Earth Metal Ions.

PubMed

Moriwaki, Hiroshi; Masuda, Reiko; Yamazaki, Yuki; Horiuchi, Kaoru; Miyashita, Mari; Kasahara, Jun; Tanaka, Tatsuhito; Yamamoto, Hiroki

2016-10-12

The adsorption behaviors of the rare earth metal ions onto freeze-dried powders of genetically engineered microbial strains were compared. Cell powders obtained from four kinds of strains, Bacillus subtilis 168 wild type (WT), lipoteichoic acid-defective (ΔLTA), wall teichoic acid-defective (ΔWTA), and cell wall hydrolases-defective (EFKYOJLp) strains, were used as an adsorbent of the rare earth metal ions at pH 3. The adsorption ability of the rare earth metal ions was in the order of EFKYOJLp > WT > ΔLTA > ΔWTA. The order was the same as the order of the phosphorus quantity of the strains. This result indicates that the main adsorption sites for the ions are the phosphate groups and the teichoic acids, LTA and WTA, that contribute to the adsorption of the rare earth metal ions onto the cell walls. The contribution of WTA was clearly greater than that of LTA. Each microbial powder was added to a solution containing 16 kinds of rare earth metal ions, and the removals (%) of each rare earth metal ion were obtained. The scandium ion showed the highest removal (%), while that of the lanthanum ion was the lowest for all the microbial powders. Differences in the distribution coefficients between the kinds of lanthanide ions by the EFKYOJLp and ΔWTA powders were greater than those of the other strains. Therefore, the EFKYOJLp and ΔWTA powders could be applicable for the selective extraction of the lanthanide ions. The ΔLTA powder coagulated by mixing with a rare earth metal ion, although no sedimentation of the WT or ΔWTA powder with a rare earth metal ion was observed under the same conditions. The EFKYOJLp powder was also coagulated, but its flocculating activity was lower than that of ΔLTA. The ΔLTA and EFKYOJLp powders have a long shape compared to those of the WT or ΔWTA strain. The shapes of the cells will play an important role in the sedimentation of the microbial powders with rare earth metal ions. As the results, three kinds of the genetically

CO(2) capture properties of alkaline earth metal oxides and hydroxides: A combined density functional theory and lattice phonon dynamics study.

PubMed

Duan, Yuhua; Sorescu, Dan C

2010-08-21

By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO(2) absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH)(2) (where M=Be,Mg,Ca,Sr,Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO(2) capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH)(2) systems were found to be better candidates for CO(2) sorbent applications due to their lower operating temperatures (600-700 K). In the presence of H(2)O, MgCO(3) can be regenerated into Mg(OH)(2) at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO(2) pressure but also on the H(2)O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO(2) sorbents.

Method and apparatus for the production of metal oxide powder

DOEpatents

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

1993-01-01

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

Method and apparatus for the production of metal oxide powder

DOEpatents

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

1992-01-01

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

Environmental Defects And Economic Impact On Global Market Of Rare Earth Metals

NASA Astrophysics Data System (ADS)

Charalampides, G.; Vatalis, K.; Karayannis, V.; Baklavaridis, A.

2016-11-01

Rare earth elements include the 14 lanthanides as well as lanthanium and often yttrium. Actually, most of them are not very rare and occur widely dispersed in a variety of rocks. Rare earth metals are vital to some of the world's faster growing industries: catalysts, Nd-magnets, ceramics, glass, metallurgy, battery alloys, electronics and phosphors. Worldwide, the main countries for distribution of rare earths deposits include China, USA, Russia, Brasil, India, Australia, Greenland and Malaysia. The mining and processing of rare earth metals usually result in significant environmental defects. Many deposits are associated with high concentrations of radioactive elements such as uranium and thorium, which requires separate treatment and disposal. The accumulation of rare earth elements in soils has occurred due to pollution caused by the exploitation of rare earth resources and the wide use of rare earths as fertilizers in agriculture. This accumulation has a toxic effect on the soil microfauna community. However, there are large differences in market prices due to the degree of purity determined by the specifications in the applications. The main focus of this article is to overview Rare Earth Metals’ overall impact on global economy and their environmental defects on soils during processing techniques and as they are used as fertilizers.

Cytotoxicity, permeability, and inflammation of metal oxide nanoparticles in human cardiac microvascular endothelial cells: cytotoxicity, permeability, and inflammation of metal oxide nanoparticles.

PubMed

Sun, Jing; Wang, Shaochuang; Zhao, Dong; Hun, Fei Han; Weng, Lei; Liu, Hui

2011-10-01

Wide applications and extreme potential of metal oxide nanoparticles (NPs) increase occupational and public exposure and may yield extraordinary hazards for human health. Exposure to NPs has a risk for dysfunction of the vascular endothelial cells. The objective of this study was to assess the cytotoxicity of six metal oxide NPs to human cardiac microvascular endothelial cells (HCMECs) in vitro. Metal oxide NPs used in this study included zinc oxide (ZnO), iron(III) oxide (Fe(2)O(3)), iron(II,III) oxide (Fe(3)O(4)), magnesium oxide (MgO), aluminum oxide (Al(2)O(3)), and copper(II) oxide (CuO). The cell viability, membrane leakage of lactate dehydrogenase, intracellular reactive oxygen species, permeability of plasma membrane, and expression of inflammatory markers vascular cell adhesion molecule-1, intercellular adhesion molecule-1, macrophage cationic peptide-1, and interleukin-8 in HCMECs were assessed under controlled and exposed conditions (12-24 h and 0.001-100 μg/ml of exposure). The results indicated that Fe(2)O(3), Fe(3)O(4), and Al(2)O(3) NPs did not have significant effects on cytotoxicity, permeability, and inflammation response in HCMECs at any of the concentrations tested. ZnO, CuO, and MgO NPs produced the cytotoxicity at the concentration-dependent and time-dependent manner, and elicited the permeability and inflammation response in HCMECs. These results demonstrated that cytotoxicity, permeability, and inflammation in vascular endothelial cells following exposure to metal oxide nanoparticles depended on particle composition, concentration, and exposure time. © Springer Science+Business Media B.V. 2011

Multiscale model of metal alloy oxidation at grain boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sushko, Maria L., E-mail: maria.sushko@pnnl.gov; Alexandrov, Vitaly; Schreiber, Daniel K.

2015-06-07

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

Growth and sacrificial oxidation of transition metal nanolayers

NASA Astrophysics Data System (ADS)

Tsarfati, Tim; Zoethout, Erwin; van de Kruijs, Robbert; Bijkerk, Fred

2009-04-01

Growth and oxidation of Au, Pt, Pd, Rh, Cu, Ru, Ni and Co layers of 0.3-4.3 nm thickness on Mo have been investigated with ARPES and AFM. Co and Ni layers oxidize while the Mo remains metallic. For nobler metals, the on top O and oxidation state of subsurface Mo increase, suggesting sacrificial e - donation by Mo. Au and Cu, in spite of their significantly lower surface free energy, grow in islands on Mo and actually promote Mo oxidation. Applications of the sacrificial oxidation in nanometer thin layers exist in a range of nanoscopic devices, such as nano-electronics and protection of e.g. multilayer X-ray optics for astronomy, medicine and lithography.

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

PubMed

Yin, Jun; Hu, Ying; Yoon, Juyoung

2015-07-21

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

Process for Making a Noble Metal on Tin Oxide Catalyst

NASA Technical Reports Server (NTRS)

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

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

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

Turk, Brian S.; Gupta, Raghubir P.

2001-01-01

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

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

Turk, Brian S.; Gupta, Raghubir P.

1999-01-01

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

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

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

1999-06-22

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

Multilevel metallization method for fabricating a metal oxide semiconductor device

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Process for forming a homogeneous oxide solid phase of catalytically active material

DOEpatents

Perry, Dale L.; Russo, Richard E.; Mao, Xianglei

1995-01-01

A process is disclosed for forming a homogeneous oxide solid phase reaction product of catalytically active material comprising one or more alkali metals, one or more alkaline earth metals, and one or more Group VIII transition metals. The process comprises reacting together one or more alkali metal oxides and/or salts, one or more alkaline earth metal oxides and/or salts, one or more Group VIII transition metal oxides and/or salts, capable of forming a catalytically active reaction product, in the optional presence of an additional source of oxygen, using a laser beam to ablate from a target such metal compound reactants in the form of a vapor in a deposition chamber, resulting in the deposition, on a heated substrate in the chamber, of the desired oxide phase reaction product. The resulting product may be formed in variable, but reproducible, stoichiometric ratios. The homogeneous oxide solid phase product is useful as a catalyst, and can be produced in many physical forms, including thin films, particulate forms, coatings on catalyst support structures, and coatings on structures used in reaction apparatus in which the reaction product of the invention will serve as a catalyst.

A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides

PubMed Central

Rahman, Md. Mahbubur; Saleh Ahammad, A. J.; Jin, Joon-Hyung; Ahn, Sang Jung; Lee, Jae-Joon

2010-01-01

Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. PMID:22399911

Dissolution of Fe(III) (hydr) oxides by metal-EDTA complexes

NASA Astrophysics Data System (ADS)

Ngwack, Bernd; Sigg, Laura

1997-03-01

The dissolution of Fe(III)(hydr)oxides (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by the adsorption of metal-EDTA complexes to the surface and is followed by the dissociation of the complex at the surface and the release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to the uncomplexed EDTA. The rate decreases in the order EDTA CaEDTA ≫ PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the dissolution process: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step 1 is slower than step 2 and the dissolution rates by various metals are similar. In the case of hydrous ferric oxide, step 2 is rate-limiting and the effect of the complexed metal is very pronounced.

Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

PubMed Central

Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

2012-01-01

In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution. PMID:22693485

Method and apparatus for the production of metal oxide powder

DOEpatents

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

1992-06-16

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

Process for making a noble metal on tin oxide catalyst

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Mesoporous metal oxide microsphere electrode compositions and their methods of making

DOEpatents

Paranthaman, Mariappan Parans; Liu, Hansan; Brown, Gilbert M.; Sun, Xiao-Guang; Bi, Zhonghe

2016-12-06

Compositions and methods of making are provided for mesoporous metal oxide microspheres electrodes. The mesoporous metal oxide microsphere compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g. The methods of making comprise forming composite powders. The methods may also comprise refluxing the composite powders in a basic solution to form an etched powder, washing the etched powder with an acid to form a hydrated metal oxide, and heat-treating the hydrated metal oxide to form mesoporous metal oxide microspheres.

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

PubMed Central

Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

2016-01-01

Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manna, Kuntal; Ji, Pengfei; Lin, Zekai

2016-08-30

Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturatedmore » metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.« less

The composition of Earth's core from equations of state, metal-silicate partitioning, and core formation modeling

NASA Astrophysics Data System (ADS)

Fischer, Rebecca; Campbell, Andrew; Ciesla, Fred

2016-04-01

The Earth accreted in a series of increasingly large and violent collisions. Simultaneously, the metallic core segregated from the silicate mantle, acquiring its modern composition through high pressure (P), high temperature (T) partitioning reactions. Here we present a model that couples these aspects of early planetary evolution, building on recent accretion simulations and metal-silicate partitioning experiments, constrained by density measurements of Fe-rich alloys. Previously, the equations of state of FeO, Fe-9Si, Fe-16Si, and FeSi were measured to megabar pressures and several thousand K using a laser-heated diamond anvil cell. With these equations of state, we determined that the core's density can be reproduced through the addition of 11.3 +/- 0.6 wt% silicon or 8.1 +/- 1.1 wt% oxygen to an Fe-Ni alloy (Fischer et al., 2011, 2014). Metal-silicate partitioning experiments of Ni, Co, V, Cr, Si, and O have been performed in a diamond anvil cell to 100 GPa and 5700 K, allowing the effects of P, T, and composition on the partitioning behaviors of these elements to be parameterized (Fischer et al., 2015; Siebert et al., 2012). Here we apply those experimental results to model Earth's core formation, using N-body simulations to describe the delivery, masses, and original locations of planetary building blocks (Fischer and Ciesla, 2014). As planets accrete, their core and mantle compositions are modified by high P-T reactions with each collision (Rubie et al., 2011). For partial equilibration of the mantle at 55% of the evolving core-mantle boundary pressure and the liquidus temperature, we find that the core contains 5.4 wt% Si and 1.9 wt% O. This composition is consistent with the seismologically-inferred density of Earth's core, based on comparisons to our equations of state, and indicate that the core cannot contain more than ~2 wt% S or C. Earth analogues experience 1.2 +/- 0.2 log units of oxidation during accretion, due to both the effects of high P

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review

NASA Astrophysics Data System (ADS)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2012-12-01

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review.

PubMed

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2013-01-07

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Separation of the rare-earth fission product poisons from spent nuclear fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christian, Jerry D.; Sterbentz, James W.

A method for the separation of the rare-earth fission product poisons comprising providing a spent nuclear fuel. The spent nuclear fuel comprises UO.sub.2 and rare-earth oxides, preferably Sm, Gd, Nd, Eu oxides, with other elements depending on the fuel composition. Preferably, the provided nuclear fuel is a powder, preferably formed by crushing the nuclear fuel or using one or more oxidation-reduction cycles. A compound comprising Th or Zr, preferably metal, is provided. The provided nuclear fuel is mixed with the Th or Zr, thereby creating a mixture. The mixture is then heated to a temperature sufficient to reduce the UO.sub.2more » in the nuclear fuel, preferably to at least to 850.degree. C. for Th and up to 600.degree. C. for Zr. Rare-earth metals are then extracted to form the heated mixture thereby producing a treated nuclear fuel. The treated nuclear fuel comprises the provided nuclear fuel having a significant reduction in rare-earths.« less

Preliminary study of heavy metal pollution from Fe-Al oxides in Peihuang Creek, North Taiwan

NASA Astrophysics Data System (ADS)

Lai, B.

2012-12-01

were extracted due to extraordinary high content of Fe oxide in the powder. These metals would be expected to be released under reducing conditions. And, more extraction methods simulating different natural and anthropogenic environment will be performed in the future research. Rare earth elements (REE) are an excellent indicator of adsorption/desorption geochemistry and were also determined in this study. The results demonstrate a light REE enriched pattern, which reveals that the Fe-Al oxides prefer to bind metals with low ionic potential. In addition, a positive cerium anomaly indicates an oxidation condition during the precipitation of Fe-Al oxides.

Method of physical vapor deposition of metal oxides on semiconductors

DOEpatents

Norton, David P.

2001-01-01

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

Reactivity of Metal Oxide Sorbents for Removal of H{sub 2}S

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, K.C.; Crowe, E.R.

1996-12-31

Removal of hydrogen sulfide contained in hot coal gases produced from integrated gasification combined cycle power generation systems is required to protect downstream combustion turbines from being corroded with sulfur compounds. Removal of sulfur compounds from hot coal gas products is investigated by using various metal oxide sorbents and membrane separation methods. The main requirements of these metal oxide sorbents are durability and high sulfur loading capacity during absorption-regeneration cycles. In this research, durable metal oxide sorbents were formulated. Reactivity of the formulated metal oxide sorbents with simulated coal gas mixtures was examined to search for an ideal sorbent formulationmore » with a high-sulfur loading capacity suitable for removal of hydrogen sulfide from coal gases. The main objectives of this research are to formulate durable metal oxide sorbents with high-sulfur loading capacity by a physical mixing method, to investigate reaction kinetics on the removal of sulfur compounds from coal gases at high temperature and pressure, to study reaction kinetics on the regeneration of sulfided sorbents, to identify effects of hydrogen partial pressures and moisture on equilibrium/dynamic absorption of hydrogen sulfide into formulated metal oxide sorbents as well as initial reaction rates of H{sub 2}S with formulated metal oxide sorbents, and to evaluate intraparticular diffusivity of H{sub 2}S into formulated sorbents at various reaction conditions. The metal oxide sorbents such as TU-1, TU-19, TU-24, TU-25 and TU-28 were formulated with zinc oxide powder as an active sorbent ingredient, bentonite as a binding material and titanium oxide as a supporting metal oxide.« less

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

NASA Astrophysics Data System (ADS)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

2016-12-01

In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn2O3, Co3O4 and Cr2O3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

Metal/silicon Interfaces and Their Oxidation Behavior - Photoemission Spectroscopy Analysis.

NASA Astrophysics Data System (ADS)

Yeh, Jyh-Jye

Synchrotron radiation photoemission spectroscopy was used to study Ni/Si and Au/Si interface properties on the atomic scale at room temperature, after high temperature annealing and after oxygen exposures. Room temperature studies of metal/Si interfaces provide background for an understanding of the interface structure after elevated temperature annealing. Oxidation studies of Si surfaces covered with metal overlayers yield insight about the effect of metal atoms in the Si oxidation mechanisms and are useful in the identification of subtle differences in bonding relations between atoms at the metal/Si interfaces. Core level and valence band spectra with variable surface sensitivities were used to study the interactions between metal, Si, and oxygen for metal coverages and oxide thickness in the monolayer region. Interface morphology at the initial stage of metal/Si interface formation and after oxidation was modeled on the basis of the evolutions of metal and Si signals at different probing depths in the photoemission experiment. Both Ni/Si and Au/Si interfaces formed at room temperature have a diffusive region at the interface. This is composed of a layer of metal-Si alloy, formed by Si outdiffusion into the metal overlayer, above a layer of interstitial metal atoms in the Si substrate. Different atomic structures of these two regions at Ni/Si interface can account for the two different growth orientations of epitaxial Ni disilicides on the Si(111) surface after thermal annealing. Annealing the Au/Si interface at high temperature depletes all the Au atoms except for one monolayer of Au on the Si(111) surface. These phenomena are attributed to differences in the metal-Si chemical bonding relations associated with specific atomic structures. After oxygen exposures, both the Ni disilicide surface and Au covered Si surfaces (with different coverages and surface orderings) show silicon in higher oxidation states, in comparison to oxidized silicon on a clean surface

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

DOEpatents

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

2009-05-05

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

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

NASA Astrophysics Data System (ADS)

Engates, Karen Elizabeth

Safe drinking water is paramount to human survival. Current treatments do not adequately remove all metals from solution, are expensive, and use many resources. Metal oxide nanoparticles are ideal sorbents for metals due to their smaller size and increased surface area in comparison to bulk media. With increasing demand for fresh drinking water and recent environmental catastrophes to show how fragile water supplies are, new approaches to water conservation incorporating new technologies like metal oxide nanoparticles should be considered as an alternative method for metal contaminant adsorbents from typical treatment methods. This research evaluated the potential of manufactured iron, anatase, and aluminum nanoparticles (Al2O3, TiO2, Fe2O3) to remove metal contaminants (Pb, Cd, Cu, Ni, Zn) in lab-controlled and natural waters in comparison to their bulk counterparts by focusing on pH, contaminant and adsorbent concentrations, particle size, and exhaustive capabilities. Microscopy techniques (SEM, BET, EDX) were used to characterize the adsorbents. Adsorption experiments were performed using 0.01, 0.1, or 0.5 g/L nanoparticles in pH 8 solution. When results were normalized by mass, nanoparticles adsorbed more than bulk particles but when surface area normalized the opposite was observed. Adsorption was pH-dependent and increased with time and solid concentration. Aluminum oxide was found to be the least acceptable adsorbent for the metals tested, while titanium dioxide anatase (TiO2) and hematite (alpha-Fe2O3) showed great ability to remove individual and multiple metals from pH 8 and natural waters. Intraparticle diffusion was likely part of the complex kinetic process for all metals using Fe2O3 but not TiO 2 nanoparticles within the first hour of adsorption. Adsorption kinetics for all metals tested were described by a modified first order rate equation used to consider the diminishing equilibrium metal concentrations with increasing metal oxides, showing faster

Adsorption of Salicylhydroxamic Acid on Selected Rare Earth Oxides and Carbonates

NASA Astrophysics Data System (ADS)

Galt, Greer Elaine

Adsorption behavior of the anionic collector salicylhydroxamic acid (SHA) on a selected group of rare earth oxides (REOs) and carbonates (RECs) was studied via experimental methods and modelling software. Synthetic oxide and carbonate powders of the rare earth elements cerium (Ce), praseodymium (Pr), europium (Eu), and terbium (Tb) were tested for this research. Studies were conducted at different pH levels to analyze the kinetics of collector adsorption onto the oxide and carbonate surfaces in attempts to optimize recovery parameters for commercial flotation processes using SHA. In addition, thermodynamic software StabCal was implemented to compare theoretical adsorption behavior of collectors SHA and octylhydroxamic acid (OHA) on these four rare earth oxides and carbonates. Theoretical points of zero charge were also estimated via StabCal and compared to experimental values to establish validity. Results for oxides indicate that both the amount and rate of SHA adsorption are highest for lighter REOs, decreasing as ionic diameter increases, a chelation phenomenon common with hydroxamates. However, results for the carbonates exhibit the opposite trend: strongest SHA adsorption was seen in the heavy RECs. This pattern correlates to the increasing stability of the carbonate such that ionic diameter of the REs becomes more amenable to chelation due to differences in bonding chemistry. Overall, adsorption kinetics appear dependent on pH, coordination chemistry, and cation size.

Pulsed photonic fabrication of nanostructured metal oxide thin films

NASA Astrophysics Data System (ADS)

Bourgeois, Briley B.; Luo, Sijun; Riggs, Brian C.; Adireddy, Shiva; Chrisey, Douglas B.

2017-09-01

Nanostructured metal oxide thin films with a large specific surface area are preferable for practical device applications in energy conversion and storage. Herein, we report instantaneous (milliseconds) photonic synthesis of three-dimensional (3-D) nanostructured metal oxide thin films through the pulsed photoinitiated pyrolysis of organometallic precursor films made by chemical solution deposition. High wall-plug efficiency-pulsed photonic irradiation (xenon flash lamp, pulse width of 1.93 ms, fluence of 7.7 J/cm2 and frequency of 1.2 Hz) is used for scalable photonic processing. The photothermal effect of subsequent pulses rapidly improves the crystalline quality of nanocrystalline metal oxide thin films in minutes. The following paper highlights pulsed photonic fabrication of 3-D nanostructured TiO2, Co3O4, and Fe2O3 thin films, exemplifying a promising new method for the low-cost and high-throughput manufacturing of nanostructured metal oxide thin films for energy applications.

Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

PubMed

Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

2013-06-15

The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

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

DOEpatents

Tinkle, M.C.

1973-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2012-06-01

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.

First-principles study on interlayer state in alkali and alkaline earth metal atoms intercalated bilayer graphene

NASA Astrophysics Data System (ADS)

Kaneko, Tomoaki; Saito, Riichiro

2017-11-01

Energetics and electronic structures of alkali metal (Li, Na, K, Rb, and Cs) and alkaline earth metal (Be, Mg, Ca, Sr, and Ba) atoms intercalated bilayer graphene are systematically investigated using first-principles calculations based on density functional theory. Formation of alkali and alkaline earth metal atoms intercalated bilayer graphene is exothermic except for Be and Mg. The interlayer state between two graphene layers is occupied for K, Rb, Cs, Ca, Sr, and Ba. We find that the energetic position of the interlayer states between bilayer graphene monotonically shifts downward with increasing of interlayer distance. The interlayer distances of more than 4.5 Å and 4.0 Å, respectively, are necessary for the occupation of the interlayer state in bilayer graphene for alkali and alkaline earth metal atoms, which is almost independent of the intercalant metal species. We discuss the relevance to occurrence of superconductivity for the metal intercalated bilayer graphene in terms of the occupation of the interlayer state and the phonon frequency of metal ions.

Molten metal containment vessel with rare earth oxysulfide protective coating thereon and method of making same

DOEpatents

Krikorian, Oscar H.; Curtis, Paul G.

1992-01-01

An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.

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

PubMed

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

2012-01-01

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

Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

PubMed Central

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

2012-01-01

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

Fluidized reduction of oxides on fine metal powders without sintering

NASA Technical Reports Server (NTRS)

Hayashi, T.

1985-01-01

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

Solid-State Diffusional Behaviors of Functional Metal Oxides at Atomic Scale.

PubMed

Chen, Jui-Yuan; Huang, Chun-Wei; Wu, Wen-Wei

2018-02-01

Metal/metal oxides have attracted extensive research interest because of their combination of functional properties and compatibility with industry. Diffusion and thermal reliability have become essential issues that require detailed study to develop atomic-scaled functional devices. In this work, the diffusional reaction behavior that transforms piezoelectric ZnO into magnetic Fe 3 O 4 is investigated at the atomic scale. The growth kinetics of metal oxides are systematically studied through macro- and microanalyses. The growth rates are evaluated by morphology changes, which determine whether the growth behavior was a diffusion- or reaction-controlled process. Furthermore, atom attachment on the kink step is observed at the atomic scale, which has important implications for the thermodynamics of functional metal oxides. Faster growth planes simultaneously decrease, which result in the predominance of low surface energy planes. These results directly reveal the atomic formation process of metal oxide via solid-state diffusion. In addition, the nanofabricated method provides a novel approach to investigate metal oxide evolution and sheds light on diffusional reaction behavior. More importantly, the results and phenomena of this study provide considerable inspiration to enhance the material stability and reliability of metal/oxide-based devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DOEpatents

Wickham, David [Boulder, CO; Cook, Ronald [Lakewood, CO

2008-10-28

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

Kinetic and catalytic analysis of mesoporous metal oxides on the oxidation of Rhodamine B

NASA Astrophysics Data System (ADS)

Xaba, Morena S.; Noh, Ji-Hyang; Mokgadi, Keabetswe; Meijboom, Reinout

2018-05-01

In this study, we demonstrate the synthesis and catalytic activity of different mesoporous transition metal oxides, silica (SiO2), copper oxide (CuO), chromium oxide (Cr2O3), iron oxide (Fe2O3) cobalt oxide (Co3O4), cerium oxide (CeO2) and nickel oxide (NiO), on the oxidation of a pollutant dye, Rhodamine B (RhB). These metal oxides were synthesized by inverse micelle formation method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), adsorption-desorption isotherms (BET) and H2-temperature programmed reduction (TPR). UV-vis spectrophotometry was used to monitor the time-resolved absorbance of RhB at λmax = 554 nm. Mesoporous copper oxide was calcined at different final heating temperatures of 250, 350, 450 and 550 °C, and each mesoporous copper oxide catalyst showed unique physical properties and catalytic behavior. Mesoporous CuO-550 with the smallest characteristic path length δ, proved to be the catalyst of choice for the oxidation of RhB in aqueous media. We observed that the oxidation of RhB in aqueous media is dependent on the crystallite size and characteristic path length of the mesoporous metal oxide. The Langmuir-Hinshelwood model was used to fit the experimental data and to prove that the reaction occurs on the surface of the mesoporous CuO. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability were demonstrated.

Electroluminescence color tuning between green and red from metal-oxide-semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

NASA Astrophysics Data System (ADS)

Matsuda, Toshihiro; Hattori, Fumihiro; Iwata, Hideyuki; Ohzone, Takashi

2018-04-01

Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +I G current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiO x ], (Tb/Eu/Ba)SiO x , and SiO x -rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiO x -rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.

Electron microscopy study of gold nanoparticles deposited on transition metal oxides.

PubMed

Akita, Tomoki; Kohyama, Masanori; Haruta, Masatake

2013-08-20

Many researchers have investigated the catalytic performance of gold nanoparticles (GNPs) supported on metal oxides for various catalytic reactions of industrial importance. These studies have consistently shown that the catalytic activity and selectivity depend on the size of GNPs, the kind of metal oxide supports, and the gold/metal oxide interface structure. Although researchers have proposed several structural models for the catalytically active sites and have identified the specific electronic structures of GNPs induced by the quantum effect, recent experimental and theoretical studies indicate that the perimeter around GNPs in contact with the metal oxide supports acts as an active site in many reactions. Thus, it is of immense importance to investigate the detailed structures of the perimeters and the contact interfaces of gold/metal oxide systems by using electron microscopy at an atomic scale. This Account describes our investigation, at the atomic scale using electron microscopy, of GNPs deposited on metal oxides. In particular, high-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) are valuable tools to observe local atomic structures, as has been successfully demonstrated for various nanoparticles, surfaces, and material interfaces. TEM can be applied to real powder catalysts as received without making special specimens, in contrast to what is typically necessary to observe bulk materials. For precise structure analyses at an atomic scale, model catalysts prepared by using well-defined single-crystalline substrates are also adopted for TEM observations. Moreover, aberration-corrected TEM, which has high spatial resolution under 0.1 nm, is a promising tool to observe the interface structure between GNPs and metal oxide supports including oxygen atoms at the interfaces. The oxygen atoms in particular play an important role in the behavior of gold/metal oxide

Clustered atom-replaced structure in single-crystal-like metal oxide

NASA Astrophysics Data System (ADS)

Araki, Takeshi; Hayashi, Mariko; Ishii, Hirotaka; Yokoe, Daisaku; Yoshida, Ryuji; Kato, Takeharu; Nishijima, Gen; Matsumoto, Akiyoshi

2018-06-01

By means of metal organic deposition using trifluoroacetates (TFA-MOD), we replaced and localized two or more atoms in a single-crystalline structure having almost perfect orientation. Thus, we created a new functional structure, namely, clustered atom-replaced structure (CARS), having single-crystal-like metal oxide. We replaced metals in the oxide with Sm and Lu and localized them. Energy dispersive x-ray spectroscopy results, where the Sm signal increases with the Lu signal in the single-crystalline structure, confirm evidence of CARS. We also form other CARS with three additional metals, including Pr. The valence number of Pr might change from 3+ to approximately 4+, thereby reducing the Pr–Ba distance. We directly observed the structure by a high-angle annular dark-field image, which provided further evidence of CARS. The key to establishing CARS is an equilibrium chemical reaction and a combination of additional larger and smaller unit cells to matrix cells. We made a new functional metal oxide with CARS and expect to realize CARS in other metal oxide structures in the future by using the above-mentioned process.

Multiscale model of metal alloy oxidation at grain boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sushko, Maria L.; Alexandrov, Vitali Y.; Schreiber, Daniel K.

2015-06-07

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

Effect of simulated Earth reentry exposure on mechanical properties of several oxide dispersion strengthened and superalloy sheet materials

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1977-01-01

The effects of simulated multiple reentry into the earth's atmosphere on the mechanical properties of several high temperature metallic sheet materials were evaluated. The materials included five tin-gage (nominally 0.025- or 0.037-cm) oxide dispersion strengthened (ODS) alloys and two thin-gage (nominally 0.037-cm) superalloys. Multiple reentry conditions were simulated through cyclic Plasma Arc Tunnel (PAT) exposure. PAT exposure generally consisted of 100 cycles of 600 second duration at 1255, 1366, or 1477 K in a Mach 4.6 airstream with an impact pressure of nominally 800 N/m2. PAT exposure generally produced a uniform oxide scale, oxide pits or intergranular oxidation, Kirkendall porosity, and alloy depletion zones except for the aluminum-containing ODS alloys. Only a uniform oxide scale was formed on the aluminum-containing ODS alloys. PAT exposure did not significantly affect the mechanical properties of the thin-gage (nominally 0.025- or 0.037-cm) alloys evaluated. Thus it appears that the microstructural changes produced by Plasma Arc Tunnel exposure has little influence on mechanical properties.

Low frequency vibrational spectra and the nature of metal-oxygen bond of alkaline earth metal acetylacetonates

NASA Astrophysics Data System (ADS)

Fakheri, Hamideh; Tayyari, Sayyed Faramarz; Heravi, Mohammad Momen; Morsali, Ali

2017-12-01

Theoretical quantum chemistry calculations were used to assign the observed vibrational band frequencies of Be, Mg, Ca, Sr, and Ba acetylacetonates complexes. Density functional theory (DFT) calculations have been carried out at the B3LYP level, using LanL2DZ, def2SVP, and mixed, GenECP, (def2SVP for metal ions and 6-311++G** for all other atoms) basis sets. The B3LYP level, with mixed basis sets, was utilized for calculations of vibrational frequencies, IR intensity, and Raman activity. Analysis of the vibrational spectra indicates that there are several bands which could almost be assigned mainly to the metal-oxygen vibrations. The strongest Raman band in this region could be used as a measure of the stability of the complex. The effects of central metal on the bond orders and charge distributions in alkaline earth metal acetylacetonates were studied by the Natural Bond Orbital (NBO) method for fully optimized compounds. Optimization were performed at the B3LYP/6-311++G** level for the lighter alkaline earth metal complexes (Be, Mg, and Ca acetylacetonates) while the B3LYP level, using LanL2DZ (extrabasis, d and f on oxygen and metal atoms), def2SVP and mixed (def2SVP on metal ions and 6-311++G** for all other atoms) basis sets for all understudy complexes. Calculations indicate that the covalence nature of metal-oxygen bonds considerably decreases from Be to Ba complexes. The nature of metal-oxygen bond was further studied by using Atoms In Molecules (AIM) analysis. The topological parameters, Wiberg bond orders, natural charges of O and metal ions, and also some vibrational band frequencies were correlated with the stability constants of understudy complexes.

High Pressure Phase Transformations in Heavy Rare Earth Metals and Connections to Actinide Crystal Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vohra, Yogesh K.; Sangala, Bagvanth Reddy; Stemshorn, Andrew K.

2008-07-01

High-pressure studies have been performed on heavy rare earth metals Terbium (Tb) to 155 GPa and Holmium (Ho) to 134 GPa in a diamond anvil cell at room temperature. The following crystal structure sequence was observed in both metals hcp {yields} Sm-type {yields} dhcp {yields} distorted fcc (hR-24) {yields} monoclinic (C2/m) with increasing pressure. The last transformation to a low symmetry monoclinic phase is accompanied by a volume collapse of 5 % for Tb at 51 GPa and a volume collapse of 3 % for Ho at 103 GPa. This volume collapse under high pressure is reminiscent of f-shell delocalizationmore » in light rare earth metal Cerium (Ce), Praseodymium (Pr), and heavy actinide metals Americium (Am) and Curium (Cm). The orthorhombic Pnma phase that has been reported in Am and Cm after f-shell delocalization is not observed in heavy rare earth metals under high pressures. (authors)« less

Development of metal oxide impregnated stilbite thick film ethanol sensor

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

The Obtaining of Nano Oxide Systems SiO2-REE with Alkoxide Technology

NASA Astrophysics Data System (ADS)

Amelina, Anna; Grinberg, Evgenii

A lot of oxides systems with REE as dopants are used in catalytic processes in organic synthesis. They are very perspectives as thermostable coating in aerospace technics. These systems are usually based on silicon or aluminium oxides and doped with rare-earth elements. This systems can be produced by different methods. One of the most perspective of them is “sol-gel”-method with silicium, aluminium and rare-earth alkoxides as a precursor of doped silica and alumina, or their derivatives. Thus the obtaining of composite SiO _{2} - REE oxide materials by the hydrolysis doped with rare-earth elements was suggested. Some of alcoholate derivatives such as El(OR)n were used in this processes. The SiO _{2}- REE oxides were precipitated during the sol-gel process, where tetraethoxysilane (TEOS) as used as SiO _{2} sources. Also it is known that alkoxides of alkali metals, including lithium alkoxides, are widely used in industry and synthetic chemistry, as well as a source of lithium in various mixed oxide compositions, such as lithium niobate, lithium tantalate or lithium silicate. Therefore, we attempted to obtain the lithium silicate, which is also doped with rare-earth elements. Lithium silicate was obtained by alkaline hydrolysis of tetraethoxysilane with lithium alkoxide. Lithium alkoxide were synthesized by dissolving at metal in the corresponding alcohol are examined. The dependence of the rate of dissolving of the metal on the method of mixing of the reaction mixture and the degree of metal dispersion was investigated. The mathematical model of the process was composed and also optimization of process was carried out. Some oxide SiO _{2}, Al _{2}O _{3} and rare-earth nanostructured systems were obtained by sol-gel-method. The size of particle was determined by electron and X-ray spectroscopy and was in the range of 5 - 15 nm. Purity of this oxide examples for contaminating of heavy metals consists n.(1E-4...1E-5) wt%. Sols obtained by this method may be used

Metal Oxide Nanomaterial QNAR Models: Available Structural Descriptors and Understanding of Toxicity Mechanisms

PubMed Central

Ying, Jiali; Zhang, Ting; Tang, Meng

2015-01-01

Metal oxide nanomaterials are widely used in various areas; however, the divergent published toxicology data makes it difficult to determine whether there is a risk associated with exposure to metal oxide nanomaterials. The application of quantitative structure activity relationship (QSAR) modeling in metal oxide nanomaterials toxicity studies can reduce the need for time-consuming and resource-intensive nanotoxicity tests. The nanostructure and inorganic composition of metal oxide nanomaterials makes this approach different from classical QSAR study; this review lists and classifies some structural descriptors, such as size, cation charge, and band gap energy, in recent metal oxide nanomaterials quantitative nanostructure activity relationship (QNAR) studies and discusses the mechanism of metal oxide nanomaterials toxicity based on these descriptors and traditional nanotoxicity tests. PMID:28347085

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Chen (Inventor)

1999-01-01

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

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

1999-01-01

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

The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

ERIC Educational Resources Information Center

Moore, Lewis Ryan

2006-01-01

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

3D Architectured Graphene/Metal Oxide Hybrids for Gas Sensors: A Review

PubMed Central

Xia, Yi; Li, Ran; Chen, Ruosong; Wang, Jing; Xiang, Lan

2018-01-01

Graphene/metal oxide-based materials have been demonstrated as promising candidates for gas sensing applications due to the enhanced sensing performance and synergetic effects of the two components. Plenty of metal oxides such as SnO2, ZnO, WO3, etc. have been hybridized with graphene to improve the gas sensing properties. However, graphene/metal oxide nanohybrid- based gas sensors still have several limitations in practical application such as the insufficient sensitivity and response rate, and long recovery time in some cases. To achieve higher sensing performances of graphene/metal oxides nanocomposites, many recent efforts have been devoted to the controllable synthesis of 3D graphene/metal oxides architectures owing to their large surface area and well-organized structure for the enhanced gas adsorption/diffusion on sensing films. This review summarizes recent advances in the synthesis, assembly, and applications of 3D architectured graphene/metal oxide hybrids for gas sensing. PMID:29735951

A liquid metal reaction environment for the room-temperature synthesis of atomically thin metal oxides

NASA Astrophysics Data System (ADS)

Zavabeti, Ali; Ou, Jian Zhen; Carey, Benjamin J.; Syed, Nitu; Orrell-Trigg, Rebecca; Mayes, Edwin L. H.; Xu, Chenglong; Kavehei, Omid; O'Mullane, Anthony P.; Kaner, Richard B.; Kalantar-zadeh, Kourosh; Daeneke, Torben

2017-10-01

Two-dimensional (2D) oxides have a wide variety of applications in electronics and other technologies. However, many oxides are not easy to synthesize as 2D materials through conventional methods. We used nontoxic eutectic gallium-based alloys as a reaction solvent and co-alloyed desired metals into the melt. On the basis of thermodynamic considerations, we predicted the composition of the self-limiting interfacial oxide. We isolated the surface oxide as a 2D layer, either on substrates or in suspension. This enabled us to produce extremely thin subnanometer layers of HfO2, Al2O3, and Gd2O3. The liquid metal-based reaction route can be used to create 2D materials that were previously inaccessible with preexisting methods. The work introduces room-temperature liquid metals as a reaction environment for the synthesis of oxide nanomaterials with low dimensionality.

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

NASA Technical Reports Server (NTRS)

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

1977-01-01

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

Reactor process using metal oxide ceramic membranes

DOEpatents

Anderson, Marc A.

1994-01-01

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

Reactor process using metal oxide ceramic membranes

DOEpatents

Anderson, M.A.

1994-05-03

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

Design of template-stabilized active and earth-abundant oxygen evolution catalysts in acid† †Electronic supplementary information (ESI) available: CVs for unary metal oxides deposition, electrochemical stability at higher current densities for unary metal oxides at pH 2.5, EDS maps for CoMnOx and CoPbOx, STEM images and PXRD of CoMnOx and CoFePbOx, high-resolution XPS of Fe 2p for CoFePbOx, Pourbaix diagrams (of Mn, Co, Pb, and Fe), and elemental analysis. See DOI: 10.1039/c7sc01239j Click here for additional data file.

PubMed Central

Huynh, Michael; Ozel, Tuncay; Liu, Chong; Lau, Eric C.

2017-01-01

Oxygen evolution reaction (OER) catalysts that are earth-abundant and are active and stable in acid are unknown. Active catalysts derived from Co and Ni oxides dissolve at low pH, whereas acid stable systems such as Mn oxides (MnOx) display poor OER activity. We now demonstrate a rational approach for the design of earth-abundant catalysts that are stable and active in acid by treating activity and stability as decoupled elements of mixed metal oxides. Manganese serves as a stabilizing structural element for catalytically active Co centers in CoMnOx films. In acidic solutions (pH 2.5), CoMnOx exhibits the OER activity of electrodeposited Co oxide (CoOx) with a Tafel slope of 70–80 mV per decade while also retaining the long-term acid stability of MnOx films for OER at 0.1 mA cm–2. Driving OER at greater current densities in this system is not viable because at high anodic potentials, Mn oxides convert to and dissolve as permanganate. However, by exploiting the decoupled design of the catalyst, the stabilizing structural element may be optimized independently of the Co active sites. By screening potential–pH diagrams, we replaced Mn with Pb to prepare CoFePbOx films that maintained the high OER activity of CoOx at pH 2.5 while exhibiting long-term acid stability at higher current densities (at 1 mA cm–2 for over 50 h at pH 2.0). Under these acidic conditions, CoFePbOx exhibits OER activity that approaches noble metal oxides, thus establishing the viability of decoupling functionality in mixed metal catalysts for designing active, acid-stable, and earth-abundant OER catalysts. PMID:29163926

Mineral resource of the month: rare earths

USGS Publications Warehouse

Hedrick, James B.

2004-01-01

As if classified as a top-secret project, the rare earths have been shrouded in secrecy. The principal ore mineral of the group, bastnäsite, rarely appears in the leading mineralogy texts. The long names of the rare-earth elements and some unusual arrangements of letters, many Scandinavian in origin, may have intimidated even those skilled in phonics. Somewhat obscurely labeled, the rare earths are neither rare nor earths (the historical term for oxides). They are a relatively abundant group of metallic elements that occur in nature as nonmetallic compounds and have hundreds of commercial applications.

Compositional dependence of elastic moduli for transition-metal oxide spinels

NASA Astrophysics Data System (ADS)

Reichmann, H. J.; Jacobsen, S. D.; Boffa Ballaran, T.

2012-12-01

Spinel phases (AB2O4) are common non-silicate oxides in the Earth's crust and upper mantle. A characteristic of this mineral group is the ability to host a wide range of transition metals. Here we summarize the influence of transition metals (Fe, Zn, and Mn) on the pressure dependence of elastic moduli of related spinels (magnetite, gahnite, and franklinite) using GHz-ultrasonic interferometry. Measurements were carried out up to 10 GPa in diamond-anvil cells using hydrostatic pressure media. Transition metals with unfilled 3d orbitals strongly influence the elastic properties of spinels. Franklinite (Zn,Mn)Fe2O4 and magnetite Fe3O4 with transition metals on both A and B cation sites exhibit pressure-induced mode softening of C44, whereas C44 of gahnite(ZnAl2O4) and spinel (MgAl2O4) exhibit positive pressure derivatives of the shear moduli. Spinels with two transition elements tend to undergo phase changes at a lower pressure than those with none or only one transition metal. Along the Mn-Zn solid solution, the variation of moduli with composition is non-linear, and a mid-range franklinite composition studied here shows a minimum in C44 compared with either end-member: MnFe2O 4 or ZnFe2O4. In general, the linear variation of sound velocity with density (Birch's Law) is followed by spinels, however spinels containing only one or no transition metals follow a distinct slope from those containing transition metals on both A and B sites. The Cauchy relation, 0.5(C12 - C44) = P is fulfilled by spinels with only one or no transition metals, suggesting that that Coulomb interactions dominate. Spinels with two transition metals fail to meet the Cauchy relation, indicating strong directional dependence and covalent character of bonding. The bonding character of transition metals is crucial to understanding the elastic behavior of natural and synthetic spinel solid solutions containing transition metals.

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

NASA Technical Reports Server (NTRS)

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

1973-01-01

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

Structure of metal-oxide Ti-Ta-(Ti,Ta)xOy coatings during spark alloying and induction-thermal oxidation

NASA Astrophysics Data System (ADS)

Koshuro, V.; Fomin, A.; Fomina, M.; Rodionov, I.; Brzhozovskii, B.; Martynov, V.; Zakharevich, A.; Aman, A.; Oseev, A.; Majcherek, S.; Hirsch, S.

2016-08-01

The study focuses on combined spark alloying of titanium and titanium alloy surface and porous matrix structure oxidation. The metal-oxide coatings morphology is the result of melt drop transfer, heat treatment, and oxidation. The study establishes the influence of technological regimes of alloying and oxidation on morphological heterogeneity of metal- oxide system Ti-Ta-(Ti,Ta)xOy.

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...

Are metallothioneins equally good biomarkers of metal and oxidative stress?

PubMed

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

2012-10-01

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

Area-Selective Atomic Layer Deposition of Metal Oxides on Noble Metals through Catalytic Oxygen Activation

PubMed Central

2017-01-01

Area-selective atomic layer deposition (ALD) is envisioned to play a key role in next-generation semiconductor processing and can also provide new opportunities in the field of catalysis. In this work, we developed an approach for the area-selective deposition of metal oxides on noble metals. Using O2 gas as co-reactant, area-selective ALD has been achieved by relying on the catalytic dissociation of the oxygen molecules on the noble metal surface, while no deposition takes place on inert surfaces that do not dissociate oxygen (i.e., SiO2, Al2O3, Au). The process is demonstrated for selective deposition of iron oxide and nickel oxide on platinum and iridium substrates. Characterization by in situ spectroscopic ellipsometry, transmission electron microscopy, scanning Auger electron spectroscopy, and X-ray photoelectron spectroscopy confirms a very high degree of selectivity, with a constant ALD growth rate on the catalytic metal substrates and no deposition on inert substrates, even after 300 ALD cycles. We demonstrate the area-selective ALD approach on planar and patterned substrates and use it to prepare Pt/Fe2O3 core/shell nanoparticles. Finally, the approach is proposed to be extendable beyond the materials presented here, specifically to other metal oxide ALD processes for which the precursor requires a strong oxidizing agent for growth. PMID:29503508

Apparatus enables accurate determination of alkali oxides in alkali metals

NASA Technical Reports Server (NTRS)

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

1966-01-01

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

Ultralow-power complementary metal-oxide-semiconductor inverters constructed on Schottky barrier modified nanowire metal-oxide-semiconductor field-effect-transistors.

PubMed

Ma, R M; Peng, R M; Wen, X N; Dai, L; Liu, C; Sun, T; Xu, W J; Qin, G G

2010-10-01

We show that the threshold voltages of both n- and p-channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) can be lowered to close to zero by adding extra Schottky contacts on top of nanowires (NWs). Novel complementary metal-oxide-semiconductor (CMOS) inverters are constructed on these Schottky barrier modified n- and p-channel NW MOSFETs. Based on the high performances of the modified n- and p-channel MOSFETs, especially the low threshold voltages, the as-fabricated CMOS inverters have low operating voltage, high voltage gain, and ultra-low static power dissipation.

Method of making metal oxide ceramic membranes with small pore sizes

DOEpatents

Anderson, Marc A.; Xu, Qunyin

1992-01-01

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