Metal–metal chalcogenide molecular precursors to binary, ternary, and quaternary metal chalcogenide thin films for electronic devices

DOE PAGES

Zhang, Ruihong; Cho, Seonghyuk; Lim, Daw Gen; ...

2016-03-15

We found that bulk metals and metal chalcogenides dissolve in primary amine–dithiol solvent mixtures at ambient conditions. Thin-films of CuS, SnS, ZnS, Cu 2Sn(Sx,Se 1-x) 3, and Cu 2ZnSn(SxSe 1-x) 4 (0 ≤ x ≤ 1) were deposited using the as-dissolved solutions. Furthermore, Cu 2ZnSn(SxSe 1-x) 4 solar cells with efficiencies of 6.84% and 7.02% under AM1.5 illumination were fabricated from two example solution precursors, respectively.

Solution synthesis of mixed-metal chalcogenide nanoparticles and spray deposition of precursor films

DOEpatents

Schulz, Douglas L.; Curtis, Calvin J.; Ginley, David S.

2000-01-01

A colloidal suspension comprising metal chalcogenide nanoparticles and a volatile capping agent. The colloidal suspension is made by reacting a metal salt with a chalcogenide salt in an organic solvent to precipitate a metal chalcogenide, recovering the metal chalcogenide, and admixing the metal chalcogenide with a volatile capping agent. The colloidal suspension is spray deposited onto a substrate to produce a semiconductor precursor film which is substantially free of impurities.

Composite catalysts supported on modified carbon substrates and methods of making the same

DOEpatents

Popov, Branko N [Columbia, SC; Subramanian, Nalini [Kennesaw, GA; Colon-Mercado, Hector R [Columbia, SC

2009-11-17

A method of producing a composite carbon catalyst is generally disclosed. The method includes oxidizing a carbon precursor (e.g., carbon black). Optionally, nitrogen functional groups can be added to the oxidized carbon precursor. Then, the oxidized carbon precursor is refluxed with a non-platinum transitional metal precursor in a solution. Finally, the solution is pyrolyzed at a temperature of at least about 500.degree. C.

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.

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.

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.

Nanofibrous electrocatalysts

DOEpatents

Liu, Di Jia; Shui, Jianglan; Chen, Chen

2016-05-24

A nanofibrous catalyst and method of manufacture. A precursor solution of a transition metal based material is formed into a plurality of interconnected nanofibers by electro-spinning the precursor solution with the nanofibers converted to a catalytically active material by a heat treatment. Selected subsequent treatments can enhance catalytic activity.

Fluorinated precursors of superconducting ceramics, and methods of making the same

DOEpatents

Wiesmann, Harold; Solovyov, Vyacheslav

2014-02-18

This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere containing fluorinated gas to provide the fluorinated precursor.

Fluorinated precursors of superconducting ceramics, and methods of making the same

DOEpatents

Wiesmann, Harold [Stony Brook, NY; Solovyov, Vyacheslav [Rocky Point, NY

2008-04-22

This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere containing fluorinated gas to provide the fluorinated precursor.

Fluorinated precursors of superconducting ceramics, and methods of making the same

DOEpatents

Wiesmann, Harold [Stony Brook, NY; Solovyov, Vyacheslav [Rocky Point, NY

2012-07-10

This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere containing fluorinated gas to provide the fluorinated precursor.

Deposition and Characterization of Thin Films on Metallic Substrates

NASA Technical Reports Server (NTRS)

Gatica, Jorge E.

2005-01-01

A CVD method was successfully developed to produce conversion coatings on aluminum alloys surfaces with reproducible results with a variety of precursors. A well defined protocol to prepare the precursor solutions formulated in a previous research was extended to other additives. It was demonstrated that solutions prepared following such a protocol could be used to systematically generate protective coatings onto aluminum surfaces. Experiments with a variety of formulations revealed that a refined deposition protocol yields reproducible conversion coatings of controlled composition. A preliminary correlation between solution formulations and successful precursors was derived. Coatings were tested for adhesion properties enhancement for commercial paints. A standard testing method was followed and clear trends were identified. Only one precursors was tested systematically. Anticipated work on other precursors should allow a better characterization of the effect of intermetallics on the production of conversion/protective coatings on metals and ceramics. The significance of this work was the practical demonstration that chemical vapor deposition (CVD) techniques can be used to systematically generate protective/conversion coating on non-ferrous surfaces. In order to become an effective approach to replace chromate-based pre- treatment processes, namely in the aerospace or automobile industry, the process parameters must be defined more precisely. Moreover, the feasibility of scale-up designs necessitates a more comprehensive characterization of the fluid flow, transport phenomena, and chemical kinetics interacting in the process. Kinetic characterization showed a significantly different effect of magnesium-based precursors when compared to iron-based precursors. Future work will concentrate on refining the process through computer simulations and further experimental studies on the effect of other transition metals to induce deposition of conversion/protective films on aluminum and other metallic substrates.

Synthesis of silicon containing materials using liquid hydrosilane compositions through direct injection

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

Srinivasan, Guruvenket; Sailer, Robert A.; Hoey, Justin

An apparatus and a non-vapor-pressure dependent method of chemical vapor deposition of Si based materials using direct injection of liquid hydrosilane(s) are presented. Liquid silane precursor solutions may also include metal, non-metal or metalloid dopants, nanomaterials and solvents. An illustrative apparatus has a precursor solution and carrier gas system, atomizer and deposit head with interior chamber and a hot plate supporting the substrate. Atomized liquid silane precursor solutions and carrier gas moves through a confined reaction zone that may be heated and the aerosol and vapor are deposited on a substrate to form a thin film. The substrate may bemore » heated prior to deposition. The deposited film may be processed further with thermal or laser processing.« less

Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

DOEpatents

Voigt, J.A.; Sipola, D.L.; Tuttle, B.A.; Anderson, M.T.

1999-06-01

A process is disclosed for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications. 4 figs.

Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

DOEpatents

Voigt, James A.; Sipola, Diana L.; Tuttle, Bruce A.; Anderson, Mark T.

1999-01-01

A process for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications.

Methods for producing thin film charge selective transport layers

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

Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

Cubic nitride templates

DOEpatents

Burrell, Anthony K; McCleskey, Thomas Mark; Jia, Quanxi; Mueller, Alexander H; Luo, Hongmei

2013-04-30

A polymer-assisted deposition process for deposition of epitaxial cubic metal nitride films and the like is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures under a suitable atmosphere to yield metal nitride films and the like. Such films can be used as templates for the development of high quality cubic GaN based electronic devices.

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.

Method to synthesize metal chalcogenide monolayer nanomaterials

DOEpatents

Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

2016-12-13

Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

Precision synthesis of colloidal inorganic nanocrystals using metal and metalloid amides

NASA Astrophysics Data System (ADS)

Yarema, Maksym; Caputo, Riccarda; Kovalenko, Maksym V.

2013-08-01

Rational selection of molecular precursors is the key consideration in the synthesis of inorganic nanocrystals and nanoparticles. This review highlights the state-of-the-art and future potential of metal amides as precursors in the solution-phase synthesis of monodisperse colloidal nanocrystals of metals and metal alloys, as well as metal oxides and chalcogenides. We exclusively focus on homoleptic metal and metalloid alkylamides M(NR2)n and silylamides M[N(SiMe3)2]n as predominant choice of element-nitrogen bonded precursors, which are often advantageous to commonly used metal-oxygen and metal-carbon bonded counterparts. In particular, these amides are highly reactive in oxidation, reduction and metathesis reactions; they are oxygen-free, easy-to-make and/or commercially available. A comprehensive literature review is complemented by our theoretical studies on the thermal stability of metal silylamides using molecular dynamics simulations.

Porous light-emitting compositions

DOEpatents

Burrell, Anthony K [Los Alamos, NM; McCleskey, Thomas Mark [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM; Bauer, Eve [Los Alamos, NM; Mueller, Alexander H [Los Alamos, NM

2012-04-17

Light-emitting devices are prepared by coating a porous substrate using a polymer-assisted deposition process. Solutions of metal precursor and soluble polymers having binding properties for metal precursor were coated onto porous substrates. The coated substrates were heated at high temperatures under a suitable atmosphere. The result was a substrate with a conformal coating that did not substantially block the pores of the substrate.

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).

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.

Method for the preparation of thallium-containing superconducting materials by precipitation

DOEpatents

Bunker, Bruce C.; Lamppa, Diana L.; Voigt, James A.

1991-01-01

This invention provides improved methods for the preparation of precursor powders that are used in the preparation of superconducting ceramic materials that contain thallium. A first solution that contains the hydrogen peroxide and metal cations, other than thallium, that will be part of the ceramic is quickly mixed with a second solution that contains precipitating anions and thallium (I) to form a precipitate which is dried to yield precursor powders. The precursor powders are calcined an sintered to produce superconducting materials that contain thallium.

Electro Spray Method for Flexible Display

DTIC Science & Technology

2016-05-12

conditions which expensive and complicated.8-9) Kim et al. reported the fabrication of IZO thin films via combustion processing and obtained mobility values...metal nitrates as metal sources in solutions. Through the high self-generated energies by the combustion of acetylacetone or urea in solution...barrier to increase the mobility of solution-process-derived TFTs. Therefore, we used H2O as the solvent in our precursor solution. The use of H2O

XPS study of thermal and electron-induced decomposition of Ni and Co acetylacetonate thin films for metal deposition

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

Weiss, Theodor; Warneke, Jonas; Zielasek, Volkmar, E-mail: zielasek@uni-bremen.de

2016-07-15

Optimizing thin metal film deposition techniques from metal-organic precursors such as atomic layer deposition, chemical vapor deposition (CVD), or electron beam-induced deposition (EBID) with the help of surface science analysis tools in ultrahigh vacuum requires a contamination-free precursor delivery technique, especially in the case of the less volatile precursors. For this purpose, the preparation of layers of undecomposed Ni(acac){sub 2} and Co(acac){sub 2} was tried via pulsed spray evaporation of a liquid solution of the precursors in ethanol into a flow of nitrogen on a CVD reactor. Solvent-free layers of intact precursor molecules were obtained when the substrate was heldmore » at a temperature of 115 °C. A qualitative comparison of thermally initiated and electron-induced precursor decomposition and metal center reduction was carried out. All deposited films were analyzed with respect to chemical composition quasi in situ by x-ray photoelectron spectroscopy. Thermally initiated decomposition yielded higher metal-to-metal oxide ratios in the deposit than the electron-induced process for which ratios of 60:40 and 20:80 were achieved for Ni and Co, resp. Compared to continuous EBID processes, all deposits showed low levels of carbon impurities of ∼10 at. %. Therefore, postdeposition irradiation of metal acetylacetonate layers by a focused electron beam and subsequent removal of intact precursor by dissolution in ethanol or by heating is proposed as electron beam lithography technique on the laboratory scale for the production of the metal nanostructures.« less

Fabrication of nanostructured metal oxide films with supercritical carbon dioxide: Processing and applications

NASA Astrophysics Data System (ADS)

You, Eunyoung

Nanostructured metal oxide films have many applications in catalysis, microelectronics, microfluidics, photovoltaics and other fields. Since the performance of a device depends greatly on the structure of the material, the development of methodologies that enable prescriptive control of morphology are of great interest. The focus of this work is to control the structure and properties of the nanostructured metal oxide films using novel synthetic schemes in supercritical fluids and to use those films as key building components in alternative energy applications. A supercritical fluid is a substance at a temperature and pressure above its critical point. It typically exhibits gas-like transport properties and liquid-like densities. Supercritical fluid deposition (SFD) utilizes these properties of supercritical CO2 (scCO2) to deposit chemically pure metal, oxides and alloys of metal films. SFD is a chemical vapor deposition (CVD)-like process in the sense that it uses similar metal organic precursors and deposits films at elevated temperatures. Instead of vaporizing or subliming the precursors, they are dissolved in supercritical fluids. SFD has typically shown to exhibit higher precursor concentrations, lower deposition temperatures, conformal deposition of films on high aspect ratio features as compared to CVD. In2 O3, ZnO and SnO2 are attractive materials because they are used in transparent conductors. SFD of these materials were studied and In2 O3 deposition kinetics using tris(2,2,6,6-tetramethyl-3,5-heptanedionato) In (III) as precursor were determined. Growth rate dependence on the deposition temperature and the precursor concentrations were studied and the physicochemical and optical properties of In2 O3 films were characterized. Metal oxide nanochannels that can potentially be used for microfluidics have been fabricated by sequentially performing nanoimprint lithography (NIL) and SFD. NIL was used to pattern photoresist grating on substrates and SFD of TiO2 was performed thereafter. Subsequent calcination of the samples at high temperature of 400 °C revealed TiO2 nanochannels. H2-assisted-codeposition of Pt and cerium oxide using SFD was performed on porous carbon substrates for their use as anodes for direct methanol fuel cells. X-ray photoelectron analysis revealed that Pt was deposited as a pure metal and Ce was deposited as an oxide. Electrochemical analysis of a full cell revealed that an anode prepared with SFD exhibited better performance than that prepared with conventional brush-painting method. The second process that was developed is a direct spray-on technique to rapidly deposit crystalline nanoscale dendritic TiO2 onto a solid surface. This technique employs atomization of precursor solutions in supercritical fluids combined with the plasma thermal spraying. A solution of metal oxide precursor in scCO2 was expanded across a nozzle into the plasma jet where it is converted to metal oxide. We have investigated TiO2 as our model system using titanium tetra isopropoxide (Ttip) as a precursor. The film structure depends on key process variables including precursor concentration, precursor solution flow rate and plasma gun to substrate distance. The high surface area of the deposited films is attractive for applications in photovoltaics and we have fabricated dye-sensitized solar cells using these films.

Acid anhydrides: a simple route to highly pure organometallic solutions for superconducting films

NASA Astrophysics Data System (ADS)

Roma, N.; Morlens, S.; Ricart, S.; Zalamova, K.; Moreto, J. M.; Pomar, A.; Puig, T.; Obradors, X.

2006-06-01

The presence of impurities in the precursor metal carboxylate solutions for the preparation of epitaxial thin films by metal organic decomposition (MOD) is substantially avoided by the use of acid anhydrides. In particular, trifluoroacetic anhydride (TFAA) was used for the synthesis of the starting Y, Ba and Cu trifluoroacetates used in YBa2Cu3O7-x (YBCO) preparation by the MOD process. In this way, highly stable organometallic precursors and a short pyrolysis process could be used leading to YBCO films with high critical currents (Jc >=2-4 MA cm-2 at 77 K). Furthermore, the reproducibility of the results has been ascertained.

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.

Solid lithium ion conducting electrolytes and methods of preparation

DOEpatents

Narula, Chaitanya K; Daniel, Claus

2013-05-28

A composition comprised of nanoparticles of lithium ion conducting solid oxide material, wherein the solid oxide material is comprised of lithium ions, and at least one type of metal ion selected from pentavalent metal ions and trivalent lanthanide metal ions. Solution methods useful for synthesizing these solid oxide materials, as well as precursor solutions and components thereof, are also described. The solid oxide materials are incorporated as electrolytes into lithium ion batteries.

Solid lithium ion conducting electrolytes and methods of preparation

DOEpatents

Narula, Chaitanya K.; Daniel, Claus

2015-11-19

A composition comprised of nanoparticles of lithium ion conducting solid oxide material, wherein the solid oxide material is comprised of lithium ions, and at least one type of metal ion selected from pentavalent metal ions and trivalent lanthanide metal ions. Solution methods useful for synthesizing these solid oxide materials, as well as precursor solutions and components thereof, are also described. The solid oxide materials are incorporated as electrolytes into lithium ion batteries.

Metal phosphonate coordination networks and frameworks as precursors of electrocatalysts for the hydrogen and oxygen evolution reactions

NASA Astrophysics Data System (ADS)

Zhang, Rui; El-Refaei, Sayed M.; Russo, Patrícia A.; Pinna, Nicola

2018-05-01

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) play key roles in the conversion of energy derived from renewable energy sources into chemical energy. Efficient, robust, and inexpensive electrocatalysts are necessary for driving these reactions at high rates at low overpotentials and minimize energetic losses. Recently, electrocatalysts derived from hybrid metal phosphonate compounds have shown high activity for the HER or OER. We review here the utilization of metal phosphonate coordination networks and metal-organic frameworks as precursors/templates for transition-metal phosphides, phosphates, or oxyhydroxides generated in situ in alkaline solutions, and their electrocatalytic performance in HER or OER.

An Efficient, Versatile, and Safe Access to Supported Metallic Nanoparticles on Porous Silicon with Ionic Liquids.

PubMed

Darwich, Walid; Haumesser, Paul-Henri; Santini, Catherine C; Gaillard, Frédéric

2016-06-03

The metallization of porous silicon (PSi) is generally realized through physical vapor deposition (PVD) or electrochemical processes using aqueous solutions. The former uses a strong vacuum and does not allow for a conformal deposition into the pores. In the latter, the water used as solvent causes oxidation of the silicon during the reduction of the salt precursors. Moreover, as PSi is hydrophobic, the metal penetration into the pores is restricted to the near-surface region. Using a solution of organometallic (OM) precursors in ionic liquid (IL), we have developed an easy and efficient way to fully metallize the pores throughout the several-µm-thick porous Si. This process affords supported metallic nanoparticles characterized by a narrow size distribution. This process is demonstrated for different metals (Pt, Pd, Cu, and Ru) and can probably be extended to other metals. Moreover, as no reducing agent is necessary (the decomposition in an argon atmosphere at 50 °C is fostered by surface silicon hydride groups borne by PSi), the safety and the cost of the process are improved.

An Efficient, Versatile, and Safe Access to Supported Metallic Nanoparticles on Porous Silicon with Ionic Liquids

PubMed Central

Darwich, Walid; Haumesser, Paul-Henri; Santini, Catherine C.; Gaillard, Frédéric

2016-01-01

The metallization of porous silicon (PSi) is generally realized through physical vapor deposition (PVD) or electrochemical processes using aqueous solutions. The former uses a strong vacuum and does not allow for a conformal deposition into the pores. In the latter, the water used as solvent causes oxidation of the silicon during the reduction of the salt precursors. Moreover, as PSi is hydrophobic, the metal penetration into the pores is restricted to the near-surface region. Using a solution of organometallic (OM) precursors in ionic liquid (IL), we have developed an easy and efficient way to fully metallize the pores throughout the several-µm-thick porous Si. This process affords supported metallic nanoparticles characterized by a narrow size distribution. This process is demonstrated for different metals (Pt, Pd, Cu, and Ru) and can probably be extended to other metals. Moreover, as no reducing agent is necessary (the decomposition in an argon atmosphere at 50 °C is fostered by surface silicon hydride groups borne by PSi), the safety and the cost of the process are improved. PMID:27271608

Fabrication of gold dot, ring, and corpuscle arrays from block copolymer templates via a simple modification of surface energy

NASA Astrophysics Data System (ADS)

Cho, Heesook; Choi, Sinho; Kim, Jin Young; Park, Soojin

2011-12-01

We demonstrate a simple method for tuning the morphologies of as-spun micellar thin films by modifying the surface energy of silicon substrates. When a polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymer dissolved in o-xylene was spin-coated onto a PS-modified surface, a dimple-type structure consisting of a thick PS shell and P2VP core was obtained. Subsequently, when the films were immersed in metal precursor solutions at certain periods of time and followed by plasma treatment, metal individual dots in a ring-shaped structure, metal nanoring, and metal corpuscle arrays were fabricated, depending on the loading amount of metal precursors. In contrast, when PS-b-P2VP films cast onto silicon substrates with a native oxide were used as templates, only metal dotted arrays were obtained. The combination of micellar thin film and surface energy modification offers an effective way to fabricate various nanostructured metal or metal oxide films.We demonstrate a simple method for tuning the morphologies of as-spun micellar thin films by modifying the surface energy of silicon substrates. When a polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymer dissolved in o-xylene was spin-coated onto a PS-modified surface, a dimple-type structure consisting of a thick PS shell and P2VP core was obtained. Subsequently, when the films were immersed in metal precursor solutions at certain periods of time and followed by plasma treatment, metal individual dots in a ring-shaped structure, metal nanoring, and metal corpuscle arrays were fabricated, depending on the loading amount of metal precursors. In contrast, when PS-b-P2VP films cast onto silicon substrates with a native oxide were used as templates, only metal dotted arrays were obtained. The combination of micellar thin film and surface energy modification offers an effective way to fabricate various nanostructured metal or metal oxide films. Electronic supplementary information (ESI) available: AFM images of Au nanorings prepared from a mixed solvent and characterization of PS-b-P2VP micellar films. See DOI: 10.1039/c1nr11075f

Facile Routes To Improve Performance of Solution-Processed Amorphous Metal Oxide Thin Film Transistors by Water Vapor Annealing.

PubMed

Park, Won-Tae; Son, Inyoung; Park, Hyun-Woo; Chung, Kwun-Bum; Xu, Yong; Lee, Taegweon; Noh, Yong-Young

2015-06-24

Here, we report on a simple and high-rate oxidization method for producing solution-based compound mixtures of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) metal-oxide semiconductors (MOS) for thin-film transistor (TFT) applications. One of the issues for solution-based MOS fabrication is how to sufficiently oxidize the precursor in order to achieve high performance. As the oxidation rate of solution processing is lower than vacuum-based deposition such as sputtering, devices using solution-processed MOS exhibit relatively poorer performance. Therefore, we propose a method to prepare the metal-oxide precursor upon exposure to saturated water vapor in a closed volume for increasing the oxidization efficiency without requiring additional oxidizing agent. We found that the hydroxide rate of the MOS film exposed to water vapor is lower than when unexposed (≤18%). Hence, we successfully fabricated oxide TFTs with high electron mobility (27.9 cm(2)/V·s) and established a rapid process (annealing at 400 °C for 5 min) that is much shorter than the conventional as-deposited long-duration annealing (at 400 °C for 1 h) whose corresponding mobility is even lower (19.2 cm(2)/V·s).

Synthesis of noble metal/carbon nanotube composites in supercritical methanol.

PubMed

Sun, Zhenyu; Fu, Lei; Liu, Zhimin; Han, Buxing; Liu, Yunqi; Du, Jimin

2006-03-01

A simple and efficient route has been employed to deposit noble metal nanoparticles (Pt, Ru, Pt-Ru, Rh, Ru-Sn) onto carbon nanotubes (CNTs) in supercritical methanol solution. In this method, the inorganic metallic salts acted as metal precursors, and methanol as solvent as well as reductant for the precursors. The as-prepared nanocomposites were structurally and morphologically characterized by X-ray diffraction spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. It was demonstrated that the CNTs were decorated by crystalline metal nanoparticles with uniform sizes and a narrow particle size distribution. The size and loading content of the nanoparticles on CNTs could be tuned by manipulating reaction parameters. Furthermore, the formation mechanism of the composites was also discussed.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1992-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1993-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Toshifumi Sugama.

1993-04-06

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR)[sub n] (wherein M is Ti, Zr, Ge or Al; R is CH[sub 3], C[sub 2]H[sub 5] or C[sub 3]H[sub 7]; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., < 1,000 C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Method of producing Pb-stabilized superconductor precursors and method of producing superconductor articles therefrom

DOEpatents

Kroeger, D.M.; Hsu, H.S.; Brynestad, J.

1995-03-07

Metal oxide superconductor powder precursors are prepared in an aerosol pyrolysis process. A solution of the metal cations is introduced into a furnace at 600--1,000 C for 0.1 to 60 seconds. The process produces micron to submicron size powders without the usual loss of the lead stabilizer. The resulting powders have a narrow particle size distribution, a small grain size, and are readily converted to a superconducting composition upon subsequent heat treatment. The precursors are placed in a metal body deformed to form a wire or tape and heated to form a superconducting article. The fine powders permit a substantial reduction in heat treatment time, thus enabling a continuous processing of the powders into superconducting wire, tape or multifilamentary articles by the powder-in-tube process. 3 figs.

Method of producing Pb-stabilized superconductor precursors and method of producing superconductor articles therefrom

DOEpatents

Kroeger, Donald M.; Hsu, Huey S.; Brynestad, Jorulf

1995-01-01

Metal oxide superconductor powder precursors are prepared in an aerosol pyrolysis process. A solution of the metal cations is introduced into a furnace at 600.degree.-1000.degree. C. for 0.1 to 60 seconds. The process produces micron to submicron size powders without the usual loss of the lead stabilizer. The resulting powders have a narrow particle size distribution, a small grain size, and are readily converted to a superconducting composition upon subsequent heat treatment. The precursors are placed in a metal body deformed to form a wire or tape and heated to form a superconducting article. The fine powders permit a substantial reduction in heat treatment time, thus enabling a continuous processing of the powders into superconducting wire, tape or multifilamentary articles by the powder-in-tube process.

Production of nanocrystalline metal powders via combustion reaction synthesis

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

Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.

Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

Effect of alkali ions (Na+, K+, Cs+) on reaction mechanism of CZTS nano-particles synthesis

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Altosaar, Mare; Grossberg, Maarja; Mikli, Valdek

2018-04-01

The control of morphology, elemental composition and phase composition of Cu2ZnSnS4 (CZTS) nano-crystals depends on the control of complex formation and surface stabilization of nano-particles in solution-based synthesis in oleylamine. At temperatures ≥280 °C, the control of nano-crystal's morphology and homogenous growth is difficult because of fast poly-nuclear growth occurring at higher temperatures. In the present work the effect of oleylamine complex formation with different alkali ions (Na+, K+ and Cs+) on nano-crystals growth at synthesis temperature of 280 °C was studied. It was found that nano-powders synthesized in the presence of Na+ and K+ ions showed the formation of crystals of different sizes - small nano-particles (18 nm-30 nm), large aggregated crystals (few nm to 1 μm) and large single crystals (1 μm - 4 μm). The presence of Cs+ ions in the nano-powder synthesis in oleylamine-metal precursor-CsOH solution promoted growth of nano-crystals of homogenous size. It is proposed that the formed oleylamine-Cs complexes a) enhance the formation and stabilization of oleylamine-metal (Cu, Zn and Sn) complexes before the injection of sulphur precursor into the oleylamine-metal precursor solution and b) after addition of sulphur stabilize the fast nucleated nano-particles and promote diffusion limited growth.

Processes for making dense, spherical active materials for lithium-ion cells

DOEpatents

Kang, Sun-Ho [Naperville, IL; Amine, Khalil [Downers Grove, IL

2011-11-22

Processes are provided for making dense, spherical mixed-metal carbonate or phosphate precursors that are particularly well suited for the production of active materials for electrochemical devices such as lithium ion secondary batteries. Exemplified methods include precipitating dense, spherical particles of metal carbonates or metal phosphates from a combined aqueous solution using a precipitating agent such as ammonium hydrogen carbonate, sodium hydrogen carbonate, or a mixture that includes sodium hydrogen carbonate. Other exemplified methods include precipitating dense, spherical particles of metal phosphates using a precipitating agent such as ammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, or a mixture of any two or more thereof. Further provided are compositions of and methods of making dense, spherical metal oxides and metal phosphates using the dense, spherical metal precursors. Still further provided are electrodes and batteries using the same.

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.

Near-infrared–driven decomposition of metal precursors yields amorphous electrocatalytic films

PubMed Central

Salvatore, Danielle A.; Dettelbach, Kevan E.; Hudkins, Jesse R.; Berlinguette, Curtis P.

2015-01-01

Amorphous metal-based films lacking long-range atomic order have found utility in applications ranging from electronics applications to heterogeneous catalysis. Notwithstanding, there is a limited set of fabrication methods available for making amorphous films, particularly in the absence of a conducting substrate. We introduce herein a scalable preparative method for accessing oxidized and reduced phases of amorphous films that involves the efficient decomposition of molecular precursors, including simple metal salts, by exposure to near-infrared (NIR) radiation. The NIR-driven decomposition process provides sufficient localized heating to trigger the liberation of the ligand from solution-deposited precursors on substrates, but insufficient thermal energy to form crystalline phases. This method provides access to state-of-the-art electrocatalyst films, as demonstrated herein for the electrolysis of water, and extends the scope of usable substrates to include nonconducting and temperature-sensitive platforms. PMID:26601148

Controlled thermal sintering of a metal-metal oxide-carbon ternary composite with a multi-scale hollow nanostructure for use as an anode material in Li-ion batteries.

PubMed

Kim, Hwan Jin; Zhang, Kan; Choi, Jae-Man; Song, Min Sang; Park, Jong Hyeok

2014-03-11

We report a synthetic scheme for preparing a SnO2-Sn-carbon triad inverse opal porous material using the controlled sintering of Sn precursor-infiltrated polystyrene (PS) nanobead films. Because the uniform PS nanobead film, which can be converted into carbon via a sintering step, uptakes the precursor solution, the carbon can be uniformly distributed throughout the Sn-based anode material. Moreover, the partial carbonization of the PS nanobeads under a controlled Ar/oxygen environment not only produces a composite material with an inverse opal-like porous nanostructure but also converts the Sn precursor/PS into a SnO2-Sn-C triad electrode.

Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

NASA Technical Reports Server (NTRS)

Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

2004-01-01

Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil similar JSC-1 in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. Characterization of the precursor molecules and efforts to further concentrate and hydrolyze the products to obtain gel materials will be presented for evaluation as ceramic precursors.

Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

NASA Technical Reports Server (NTRS)

Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

2003-01-01

Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SiO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2,7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil simular in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. The elemental composition and structure of the precursor molecules were characterized. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors.

High Tc superconducting films from metallo-organic precursors

NASA Astrophysics Data System (ADS)

Davison, W. W.; Shyu, S. G.; Buchanan, R. C.

High Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O(7-x), using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1-1.0 micron were achieved after heat treatment at 550-850 C at not longer than 4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction, and superconducting properties.

Surface-functionalized mesoporous carbon materials

DOEpatents

Dai, Sheng; Gorka, Joanna; Mayes, Richard T.

2016-02-02

A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

Strategies to indium nitride and gallium nitride nanoparticles: Low-temperature, solution-phase and precursor routes

NASA Astrophysics Data System (ADS)

Dingman, Sean Douglas

I present new strategies to low-temperature solution-phase synthesis of indium and gallium nitride (InN and GaN) ceramic materials. The strategies include: direct conversion of precursor molecules to InN by pyrolysis, solution-phase synthesis of nanostructured InN fibers via molecular precursors and co-reactants, and synthesis of powders through reactions derived from molten-salt chemistry. Indium nitride powders are prepared by pyrolysis of the precursors R 2InN3 (R = t-Bu (1), i-Amyl(2), Et(3), i-Pr( 4)). The precursors are synthesized via azide-alkoxide exchange of R2InOMe with Me3SiN3. The precursors are coordination polymers containing five-coordinate indium centers. Pyrolysis of 1 and 2 under N2 at 400°C yields powders consisting primarily of InN with average crystal sizes of 15--35 nm. 1 yields nanocrystalline InN with average particle sizes of 7 nm at 250°C. 3 and 4 yield primarily In metal from pyrolysis. Refluxing 1 in diisopropylbenzene (203°C) in the presence of primary amines yields InN nanofibers 10--100 nm in length. InN nanofibers of up to 1 mum can be synthesized by treating 1 with 1,1-dimethylhydrazine (DMHy) The DMHy appears to control the fiber length by acting as a secondary source of active nitrogen in order to sustain fiber growth. The resulting fibers are attached to droplets of indium metal implying a solution-liquid-solid growth mechanism. Precursor 4 yields crystalline InN whiskers when reacted with DMHy. Reactions of 4 with reducing agents such as HSnBu3, yield InN nanoparticles with an average crystallite size of 16 nm. Gallium precursors R2GaN3 (R = t-Bu( 5), Me3SiCH2(6) and i-Pr( 7)), synthesized by azide-alkoxide exchange, are found to be inert toward solution decomposition and do not yield GaN. These compounds are molecular dimers and trimers unlike the indium analogs. Compound 6 displays a monomer-dimer equilibrium in benzene solution, but exists as a solid-state trimer. InN powders are also synthesized by reactions of InCl3 and LiNH2 in a molten alkali-halide eutectic, KBr: Liar (60:40), at 400°C. The molten salt acts as an appropriate recrystallization medium for InN. Large InN platelets up to 500 nm could be synthesized. This is a significant step in finding mild reaction conditions that yield large InN crystals.

Mechanochemical synthesis, structure and properties of lead containing alkaline earth metal fluoride solid solutions MxPb1-xF2 (M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

2018-03-01

The paper deals with the mechanochemical synthesis of lead containing alkaline earth metal fluoride solid solutions MxPb1-xF2 (M = Ca, Sr, Ba) by high-energy ball milling. Several metal precursors and fluorinating agents were tested for synthesizing M0.5Pb0.5F2. Metal acetates and ammonium fluoride as precursors show the most promising results and were therefore used for the formation of MxPb1-xF2 with different metal cationic ratios. The characterization of the local fluorine coordination and the crystal structure was performed by 19F MAS NMR spectroscopy and X-ray diffraction. Additional calculations of 19F chemical shifts using the superposition model allow a deeper insight into the local structure of the compounds. The fluoride ion conductivity was followed by temperature dependent DC conductivity measurements. Significantly higher conductivities were found in comparison with those of the corresponding binary fluorides. The highest values were observed for samples with high lead content M0.25Pb0.75F2, bearing in mind the much higher conductivity of PbF2 compared to MF2.

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

NASA Astrophysics Data System (ADS)

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

2011-04-01

A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxidenanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO4, La2(MoO4)3 can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO4, La2(MoO4)3) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxidenanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO2 nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied.A conventional and general route has been exploited to the high yield synthesis of many kinds of highly crystalline metal oxide and mixed oxidenanocrystals with different morphologies including belt, rod, truncated-octahedron, cubic, sphere, sheet via the hydrothermal reaction of inorganic precursors in aqueous solution in the presence of bifunctional 6-aminohexanoic acid (AHA) molecules as a capping agent. This method is a simple, reproducible and general route for the preparation of a variety of high-crystalline inorganic nanocrystals in scale-up. The shape of inorganic nanocrystals such as CoWO4, La2(MoO4)3 can be controlled by simply adjusting the synthesis conditions including pH solution and reaction temperature. Further, by tuning precursor monomer concentration, the mesocrystal hierarchical aggregated microspheres (e.g., MnWO4, La2(MoO4)3) can be achieved, due to the spontaneous assembly of individual AHA-capped nanoparticles. These obtained AHA-capped nanocrystals are excellent supports for the synthesis of a variety of hybrid metal/oxidenanocrystals in which noble metal particles are uniformly deposited on the surface of each individual nanosupport. The photocatalytic activity of Ag/TiO2 nanobelts as a typical hybrid photocatalyst sample for Methylene Blue degradation was also studied. Electronic supplementary information (ESI) available: Additional TEM, XRD, XPS, FTIR, UV-vis and photoluminescence results of the nanocrystals. See DOI: 10.1039/c1nr10109a

Gamma-radiolytic preparation of multi-component oxides

NASA Astrophysics Data System (ADS)

Procházková, Lenka; Bárta, Jan; Čuba, Václav; Ekberg, Christian; Tietze, Sabrina; Jakubec, Ivo

2016-07-01

The preparation of solid precursors to Zn1-xCdxO and (Lu,Y)3Al5O12:Ce induced by 60Co gamma-ray irradiation of aqueous solutions containing soluble metal salts and ammonium formate is presented. Due to the irradiation, crystalline zinc carbonate hydroxide Zn4(CO3)(OH)6·H2O or amorphous carbonates of Lu, Y and Al were formed in the solutions. After calcination at 500 °C, the agglomerated phase-pure Zn1-xCdxO with crystallite size about 50 nm was obtained if the Cd concentration in solutions remained below 16 M% (with respect to Zn) with x being up to 0.035. The solid precursors to garnets contained the intended concentration of all elements, according to X-ray fluorescence analysis. After calcination at 1200 °C in mild vacuum, the respective phase-pure garnets with crystallite size 100 nm or their solid solution were produced when the Ce dopation was kept below 2 M% (with respect to rare-earth metals). The Ce solubility in the garnet lattice was estimated as 1-2 M% at the calcination conditions used.

Small angle neutron and X-ray studies of carbon structures with metal atoms

NASA Astrophysics Data System (ADS)

Lebedev, V. T.; Szhogina, A. A.; Bairamukov, V. Yu

2017-05-01

Encapsulation of metal atoms inside carbon single-wall cages or within multi-layer cells has been realized using molecular precursors and high temperature processes transforming them into desirable structures. Endohedral fullerenols Fe@C60(OH)X with 3d-metal (iron) have been studied by SANS in aqueous solutions where they form stable globular clusters with radii R C ∼ 10-12 nm and aggregation numbers N C ∼ 104. This self-assembly is a crucial feature of paramagnetic fullerenols as perspective contrast agents for Magneto-Resonance Imaging in medicine. Cellular carbon-metal structures have been created by the pyrolysis of diphthalocyanines of lanthanides and actinides. It was established that these ultra porous matrices consist of globular cells of molecular precursor size (∼ 1 nm) which are aggregated into superstructures. This provides retain of metal atoms inside matrices which may serve for safety storage of spent fuel of nuclear power plants.

Solid-Solution Sulfides Derived from Tunable Layered Double Hydroxide Precursors/Graphene Aerogel for Pseudocapacitors and Sodium-Ion Batteries.

PubMed

Song, Yajie; Li, Hui; Yang, Lan; Bai, Daxun; Zhang, Fazhi; Xu, Sailong

2017-12-13

Transition-metal sulfides (TMSs) are suggested as promising electrode materials for electrochemical pseudocapacitors and lithium- and sodium-ion batteries; however, they typically involve mixed composites or conventionally stoichiometric TMSs (such as NiCo 2 S 4 and Ni 2 CoS 4 ). Herein we demonstrate a preparation of solid-solution sulfide (Ni 0.7 Co 0.3 )S 2 supported on three-dimensional graphene aerogel (3DGA) via a sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor/3DGA. The electrochemical tests show that the (Ni 0.7 Co 0.3 )S 2 /3DGA electrode exhibits a capacitance of 2165 F g -1 at 1 A g -1 , 2055 F g -1 at 2 A g -1 , and 1478 F g -1 at 10 A g -1 ; preserves 78.5% capacitance retention upon 1000 cycles for pseudocapacitors; and in particular, possesses a relatively high charge capacity of 388.7 mA h g -1 after 50 cycles at 100 mA g -1 as anode nanomaterials for sodium-ion batteries. Furthermore, the electrochemical performances are readily tuned by varying the cationic type of the tunable LDH precursors to prepare different solid-solution sulfides, such as (Ni 0.7 Fe 0.3 )S 2 /3DGA and (Co 0.7 Fe 0.3 )S 2 /3DGA. Our results show that engineering LDH precursors can offer an alternative for preparing diverse transition-metal sulfides for energy storage.

Treating Fibrous Insulation to Reduce Thermal Conductivity

NASA Technical Reports Server (NTRS)

Zinn, Alfred; Tarkanian, Ryan

2009-01-01

A chemical treatment reduces the convective and radiative contributions to the effective thermal conductivity of porous fibrous thermal-insulation tile. The net effect of the treatment is to coat the surfaces of fibers with a mixture of transition-metal oxides (TMOs) without filling the pores. The TMO coats reduce the cross-sectional areas available for convection while absorbing and scattering thermal radiation in the pores, thereby rendering the tile largely opaque to thermal radiation. The treatment involves a sol-gel process: A solution containing a mixture of transition-metal-oxide-precursor salts plus a gelling agent (e.g., tetraethylorthosilicate) is partially cured, then, before it visibly gels, is used to impregnate the tile. The solution in the tile is gelled, then dried, and then the tile is fired to convert the precursor salts to the desired mixed TMO phases. The amounts of the various TMOs ultimately incorporated into the tile can be tailored via the concentrations of salts in the solution, and the impregnation depth can be tailored via the viscosity of the solution and/or the volume of the solution relative to that of the tile. The amounts of the TMOs determine the absorption and scattering spectra.

Nanoengineered membrane electrode assembly interface

DOEpatents

Song, Yujiang; Shelnutt, John A

2013-08-06

A membrane electrode structure suitable for use in a membrane electrode assembly (MEA) that comprises membrane-affixed metal nanoparticles whose formation is controlled by a photochemical process that controls deposition of the metal nanoparticles using a photocatalyst integrated with a polymer electrolyte membrane, such as an ionomer membrane. Impregnation of the polymer membrane with the photocatalyst prior to metal deposition greatly reduces the required amount of metal precursor in the deposition reaction solution by restricting metal reduction substantially to the formation of metal nanoparticles affixed on or near the surface of the polymer membrane with minimal formation of metallic particles not directly associated with the membrane.

Laser-processing of VO2 thin films synthesized by polymer-assisted-deposition

NASA Astrophysics Data System (ADS)

Breckenfeld, Eric; Kim, Heungsoo; Gorzkowski, Edward P.; Sutto, Thomas E.; Piqué, Alberto

2017-03-01

We investigate a novel route for synthesis and laser-sintering of VO2 thin films via solution-based polymer-assisted-deposition (PAD). By replacing the traditional solvent for PAD (water) with propylene glycol, we are able to control the viscosity and improve the environmental stability of the precursor. The solution stability and ability to control the viscosity makes for an ideal solution to pattern simple or complex shapes via direct-write methods. We demonstrate the potential of our precursor for printing applications by combining PAD with laser induced forward transfer (LIFT). We also demonstrate large-area film synthesis on 4 in. diameter glass wafers. By varying the annealing temperature, we identify the optimal synthesis conditions, obtaining optical transmittance changes of 60% at a 2500 nm wavelength and a two-order-of-magnitude semiconductor-to-metal transition. We go on to demonstrate two routes for improved semiconductor-to-metal characteristics. The first method uses a multi-coating process to produce denser films with large particles. The second method uses a pulsed-UV-laser sintering step in films annealed at low temperatures (<450° C) to promote particle growth and improve the semiconductor-to-metal transition. By comparing the hysteresis width and semiconductor-to-metal transition magnitude in these samples, we demonstrate that both methods yield high quality VO2 with a three-order-of-magnitude transition.

Domain growth of carbon nanotubes assisted by dewetting of thin catalyst precursor films

NASA Astrophysics Data System (ADS)

Srivastava, Alok Kumar; Sachan, Priyanka; Samanta, Chandan; Mukhopadhyay, Kingsuk; Sharma, Ashutosh

2014-01-01

We explore self-organized dewetting of ultrathin films of a novel metal complex as a one step surface patterning method to create nanoislands of iron, using which spatially separated carbon nanostructures were synthesized. Dewetting of ultrathin metal complex films was induced by two different methods: liquid solvent exposure and thermal annealing to engender surface patterning. For thermal dewetting, thin films of the iron oleate complex were dewetted at high temperature. In the case of liquid solvent assisted dewetting, the metal complex, mixed with a sacrificial polymer (polystyrene) was spin coated as thin films (<40 nm) and then dewetted under an optimal solution mixture consisting of methyl ethyl ketone, acetone and water. The carrier polymer was then selectively removed to produce the iron metal islands. These metal islands were used for selective growth of discrete patches of multiwall CNTs and CNFs by a chemical vapor deposition (CVD) process. Solvent induced dewetting showed clear advantages over thermal dewetting owing to reduced size of catalyst domains formed by dewetting, an improved control over CNT growth as well as in its ability to immobilize the seed particles. The generic solution mediated dewetting and pattern generation in thin films of various catalytic precursors can thus be a powerful method for selective domain growth of a variety of functional nanomaterials.

Chemical solution deposition method of fabricating highly aligned MgO templates

DOEpatents

Paranthaman, Mariappan Parans [Knoxville, TN; Sathyamurthy, Srivatsan [Knoxville, TN; Aytug, Tolga [Knoxville, TN; Arendt, Paul N [Los Alamos, NM; Stan, Liliana [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

2012-01-03

A superconducting article includes a substrate having an untextured metal surface; an untextured barrier layer of La.sub.2Zr.sub.2O.sub.7 or Gd.sub.2Zr.sub.2O.sub.7 supported by and in contact with the surface of the substrate; a biaxially textured buffer layer supported by the untextured barrier layer; and a biaxially textured superconducting layer supported by the biaxially textured buffer layer. Moreover, a method of forming a buffer layer on a metal substrate includes the steps of: providing a substrate having an untextured metal surface; coating the surface of the substrate with a barrier layer precursor; converting the precursor to an untextured barrier layer; and depositing a biaxially textured buffer layer above and supported by the untextured barrier layer.

Method for dispersing catalyst onto particulate material and product thereof

DOEpatents

Utz, Bruce R.; Cugini, Anthony V.

1992-01-01

A method for dispersing finely divided catalyst precursors onto the surface of coal or other particulate material includes the steps of forming a wet paste mixture of the particulate material and a liquid solution containing a dissolved transition metal salt, for instance a solution of ferric nitrate. The wet paste mixture is in a state of incipient wetness with all of this solution adsorbed onto the surfaces of the particulate material without the presence of free moisture. On adding a precipitating agent such as ammonia, a catalyst precursor such as hydrated iron oxide is deposited on the surfaces of the coal. The catalyst is activated by converting it to the sulfide form for the hydrogenation or direct liquefaction of the coal.

Method for dispersing catalyst onto particulate material

DOEpatents

Utz, Bruce R.; Cugini, Anthony V.

1992-01-01

A method for dispersing finely divided catalyst precursors onto the surface of coal or other particulate material includes the steps of forming a wet paste mixture of the particulate material and a liquid solution containing a dissolved transition metal salt, for instance a solution of ferric nitrate. The wet paste mixture is in a state of incipient wetness with all of this solution adsorbed onto the surfaces of the particulate material without the presence of free moisture. On adding a precipitating agent such as ammonia, a catalyst precursor such as hydrated iron oxide is deposited on the surfaces of the coal. The catalyst is activated by converting it to the sulfide form for the hydrogenation or direct liquefaction of the coal.

Liquid precursor inks for deposition of In--Se, Ga--Se and In--Ga--Se

DOEpatents

Curtis, Calvin J.; Hersh, Peter A.; Miedaner, Alexander; Habas, Susan; van Hest, Maikel; Ginley, David S.

2015-08-11

An ink includes a solution of selenium in ethylene diamine solvent and a solution of at least one metal salt selected from the group consisting of an indium salt or a gallium salt in at least one solvent including an organic amide. The organic amide can include dimethylformamide. The organic amide can include N-methylpyrrolidone.

Solution-processed flexible fluorine-doped indium zinc oxide thin-film transistors fabricated on plastic film at low temperature.

PubMed

Seo, Jin-Suk; Jeon, Jun-Hyuck; Hwang, Young Hwan; Park, Hyungjin; Ryu, Minki; Park, Sang-Hee Ko; Bae, Byeong-Soo

2013-01-01

Transparent flexible fluorine-doped indium zinc oxide (IZO:F) thin-film transistors (TFTs) were demonstrated using the spin-coating method of the metal fluoride precursor aqueous solution with annealing at 200°C for 2 hrs on polyethylene naphthalate films. The proposed thermal evolution mechanism of metal fluoride aqueous precursor solution examined by thermogravimetric analysis and Raman spectroscopy can easily explain oxide formation. The chemical composition analysed by XPS confirms that the fluorine was doped in the thin films annealed below 250°C. In the IZO:F thin films, a doped fluorine atom substitutes for an oxygen atom generating a free electron or occupies an oxygen vacancy site eliminating an electron trap site. These dual roles of the doped fluorine can enhance the mobility and improve the gate bias stability of the TFTs. Therefore, the transparent flexible IZO:F TFT shows a high mobility of up to 4.1 cm(2)/V·s and stable characteristics under the various gate bias and temperature stresses.

Solution-Processed Flexible Fluorine-doped Indium Zinc Oxide Thin-Film Transistors Fabricated on Plastic Film at Low Temperature

PubMed Central

Seo, Jin-Suk; Jeon, Jun-Hyuck; Hwang, Young Hwan; Park, Hyungjin; Ryu, Minki; Park, Sang-Hee Ko; Bae, Byeong-Soo

2013-01-01

Transparent flexible fluorine-doped indium zinc oxide (IZO:F) thin-film transistors (TFTs) were demonstrated using the spin-coating method of the metal fluoride precursor aqueous solution with annealing at 200°C for 2 hrs on polyethylene naphthalate films. The proposed thermal evolution mechanism of metal fluoride aqueous precursor solution examined by thermogravimetric analysis and Raman spectroscopy can easily explain oxide formation. The chemical composition analysed by XPS confirms that the fluorine was doped in the thin films annealed below 250°C. In the IZO:F thin films, a doped fluorine atom substitutes for an oxygen atom generating a free electron or occupies an oxygen vacancy site eliminating an electron trap site. These dual roles of the doped fluorine can enhance the mobility and improve the gate bias stability of the TFTs. Therefore, the transparent flexible IZO:F TFT shows a high mobility of up to 4.1 cm2/V·s and stable characteristics under the various gate bias and temperature stresses. PMID:23803977

Amorphous Metal Oxide Thin Films from Aqueous Precursors: New Routes to High-kappa Dielectrics, Impact of Annealing Atmosphere Humidity, and Elucidation of Non-Uniform Composition Profiles

NASA Astrophysics Data System (ADS)

Woods, Keenan N.

Metal oxide thin films serve as critical components in many modern technologies, including microelectronic devices. Industrial state-of-the-art production utilizes vapor-phase techniques to make high-quality (dense, smooth, uniform) thin film materials. However, vapor-phase techniques require large energy inputs and expensive equipment and precursors. Solution-phase routes to metal oxides have attracted great interest as cost-effective alternatives to vapor-phase methods and also offer the potential of large-area coverage, facile control of metal composition, and low-temperature processing. Solution deposition has previously been dominated by sol-gel routes, which utilize organic ligands, additives, and/or solvents. However, sol-gel films are often porous and contain residual carbon impurities, which can negatively impact device properties. All-inorganic aqueous routes produce dense, ultrasmooth films without carbon impurities, but the mechanisms involved in converting aqueous precursors to metal oxides are virtually unexplored. Understanding these mechanisms and the parameters that influence them is critical for widespread use of aqueous approaches to prepare microelectronic components. Additionally, understanding (and controlling) density and composition inhomogeneities is important for optimizing electronic properties. An overview of deposition approaches and the challenges facing aqueous routes are presented in Chapter I. A summary of thin film characterization techniques central to this work is given in Chapter II. This dissertation contributes to the field of solution-phase deposition by focusing on three areas. First, an all-inorganic aqueous route to high-kappa metal oxide dielectrics is developed for two ternary systems. Chapters III and IV detail the film formation chemistry and film properties of lanthanum zirconium oxide (LZO) and zirconium aluminum oxide (ZAO), respectively. The functionality of these dielectrics as device components is also demonstrated. Second, the impact of steam annealing on the evolution of aqueous-derived films is reported. Chapter V demonstrates that steam annealing lowers processing temperatures by effectively reducing residual counterion content, improving film stability with respect to water absorption, and enhancing dielectric properties of LZO films. Third, density and composition inhomogeneities in aqueous-derived films are investigated. Chapters VI and VII examine density inhomogeneities in single- and multi-metal component thin films, respectively, and show that these density inhomogeneities are related to inhomogeneous metal component distributions. This dissertation includes previously published coauthored material.

Sol-gel processing with inorganic metal salt precursors

DOEpatents

Hu, Zhong-Cheng

2004-10-19

Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

Combustion synthesized indium-tin-oxide (ITO) thin film for source/drain electrodes in all solution-processed oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Tue, Phan Trong; Inoue, Satoshi; Takamura, Yuzuru; Shimoda, Tatsuya

2016-06-01

We report combustion solution synthesized (SCS) indium-tin-oxide (ITO) thin film, which is a well-known transparent conductive oxide, for source/drain (S/D) electrodes in solution-processed amorphous zirconium-indium-zinc-oxide TFT. A redox-based combustion synthetic approach is applied to ITO thin film using acetylacetone as a fuel and metal nitrate as oxidizer. The structural and electrical properties of SCS-ITO precursor solution and thin films were systematically investigated with changes in tin concentration, indium metal precursors, and annealing conditions such as temperature, time, and ambient. It was found that at optimal conditions the SCS-ITO thin film exhibited high crystalline quality, atomically smooth surface (RMS ~ 4.1 Å), and low electrical resistivity (4.2 × 10-4 Ω cm). The TFT using SCS-ITO film as the S/D electrodes showed excellent electrical properties with negligible hysteresis. The obtained "on/off" current ratio, subthreshold swing factor, subthreshold voltage, and field-effect mobility were 5 × 107, 0.43 V/decade, 0.7 V, and 2.1 cm2/V s, respectively. The performance and stability of the SCS-ITO TFT are comparable to those of the sputtered-ITO TFT, emphasizing that the SCS-ITO film is a promising candidate for totally solution-processed oxide TFTs.

The influences of microwave irradiation and polyol precursor pH on Cu/AC catalyst and its CO oxidation performance

NASA Astrophysics Data System (ADS)

Chuang, Kui-Hao; Shih, Kaimin; Wey, Ming-Yen

2012-10-01

This study evaluated the effects of microwave irradiation parameters and the pH of the polyol precursor on the morphological features and catalytic performances of Cu/activated carbon (AC) catalysts. Experimental results of carbon monoxide (CO) oxidation indicated that the highest catalytic activity is achieved when the Cu/AC catalyst is prepared with microwave irradiation at 700 W for 60 s. Scanning electron microscopy revealed the presence of beneficial small copper aciculae on the Cu/AC catalyst under such a microwave irradiation scheme. Further investigation of operational parameters found that the performance of Cu/AC catalysts is enhanced by adopting a pH = 12 polyol precursor solution. With the observation that small cube copper ( 16 nm) aggregates form when a pH = 12 polyol precursor solution is used, this study also demonstrated the importance of controlling the morphology of metal nanoparticles on Cu/AC catalysts when using the microwave-assisted polyol method.

Preparation of ceramic materials using liquid metal carboxylate precursors

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

Walker, E.H.; Apblett, A.W.

We have recently discovered a novel class of metal carboxylates which are liquids at room temperature. These metal salts bear polyether organic residues and their physical properties make them highly conducive to the preparation of ceramic films and fibers. Furthermore, the liquid salts are excellent solvents for other metal salts such as nitrates. The resultant solutions are readily converted upon pyrolysis to multi-metallic oxide phases at fairly low temperatures due to the high homogeneity of the cation distribution in the liquid. The preparation of a variety of aluminum, titanium, and iron-containing ceramics in this manner will be reported.

Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

DOEpatents

McLean, II, William; Miller, Philip E.

1997-01-01

A method for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction.

Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

DOEpatents

McLean, W. II; Miller, P.E.

1997-12-16

A method is described for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction. 3 figs.

Mixed-ligand approach to design of heterometallic single-source precursors with discrete molecular structure.

PubMed

Lieberman, Craig M; Navulla, Anantharamulu; Zhang, Haitao; Filatov, Alexander S; Dikarev, Evgeny V

2014-05-05

Heterometallic single-source precursors for the Pb/Fe = 1:1 oxide materials, PbFe(β-dik)4 (β-dik = hexafluoroacetylacetonate (hfac, 1), acetylacetonate (acac, 2), and trifluoroacetylacetonate (tfac, 4)), have been isolated by three different solid-state synthetic methods. The crystal structures of heterometallic diketonates 1, 2, and 4 were found to contain polymeric chains built on alternating [Fe(β-dik)2] and [Pb(β-dik)2] units that are held together by bridging M-O interactions. Heterometallic precursors are highly volatile, but soluble only in coordinating solvents, in which they dissociate into solvated homometallic fragments. In order to design the heterometallic precursor with a proper metal/metal ratio and with a discrete molecular structure, we used a combination of two different diketonate ligands. Heteroleptic complex Pb2Fe2(hfac)6(acac)2 (5) has been obtained by optimized stoichiometric reaction of an addition of homo-Fe(acac)2 to heterometallic Pb2Fe(hfac)6 (3) diketonate that can be run in solution on a high scale. The combination of two ligands with electron-withdrawing and electron-donating groups allows changing the connectivity pattern within the heterometallic assembly and yields the precursor with a discrete tetranuclear structure. In accord with its molecular structure, heteroleptic complex 5 is soluble even in noncoordinating solvents and was found to retain its heterometallic structure in solution. Thermal decomposition of heterometallic precursors in air at 750 °C resulted in the target Pb2Fe2O5 oxide, a prospective multiferroic material. Prolonging the annealing time or increasing the decomposition temperature leads to another phase-pure lead-iron oxide PbFe12O19 that is a representative of the important family of magnetic hexaferrites.

Uniform nanoparticles by flame-assisted spray pyrolysis (FASP) of low cost precursors

PubMed Central

Rudin, Thomas; Wegner, Karsten

2013-01-01

A new flame-assisted spray pyrolysis (FASP) reactor design is presented, which allows the use of inexpensive precursors and solvents (e.g., ethanol) for synthesis of nanoparticles (10–20 nm) with uniform characteristics. In this reactor design, a gas-assisted atomizer generates the precursor solution spray that is mixed and combusted with externally fed inexpensive fuel gases (acetylene or methane) at a defined height above the atomizing nozzle. The gaseous fuel feed can be varied to control the combustion enthalpy content of the flame and onset of particle formation. This way, the enthalpy density of the flame is decoupled from the precursor solution composition. Low enthalpy content precursor solutions are prone to synthesis of non-uniform particles (e.g., bimodal particle size distribution) by standard flame spray pyrolysis (FSP) processes. For example, metal nitrates in ethanol typically produce nanosized particles by gas-to-particle conversion along with larger particles by droplet-to-particle conversion. The present FASP design facilitates the use of such low enthalpy precursor solutions for synthesis of homogeneous nanopowders by increasing the combustion enthalpy density of the flame with low-cost, gaseous fuels. The effect of flame enthalpy density on product properties in the FASP configuration is explored by the example of Bi2O3 nanoparticles produced from bismuth nitrate in ethanol. Product powders were characterized by nitrogen adsorption, X-ray diffraction, X-ray disk centrifuge, and transmission electron microscopy. Homogeneous Bi2O3 nanopowders were produced both by increasing the gaseous fuel content and, most notably, by cutting the air entrainment prior to ignition of the spray. PMID:23408113

Assembling a supercapacitor electrode with dual metal oxides and activated carbon using a liquid phase plasma.

PubMed

Ki, Seo Jin; Jeon, Ki-Joon; Park, Young-Kwon; Park, Hyunwoong; Jeong, Sangmin; Lee, Heon; Jung, Sang-Chul

2017-12-01

Developing supercapacitor electrodes at an affordable cost while improving their energy and/or power density values is still a challenging task. This study introduced a recipe which assembled a novel electrode composite using a liquid phase plasma that was applied to a reactant solution containing an activated carbon (AC) powder with dual metal precursors of iron and manganese. A comparison was made between the composites doped with single and dual metal components as well as among those synthesized under different precursor concentrations and plasma durations. The results showed that increasing the precursor concentration and plasma duration raised the content of both metal oxides in the composites, whereas the deposition conditions were more favorable to iron oxide than manganese oxide, due to its higher standard potential. The composite treated with the longest plasma duration and highest manganese concentration was superior to the others in terms of cyclic stability and equivalent series resistance. In addition, the new composite selected out of them showed better electrochemical performance than the raw AC material only and even two types of single metal-based composites, owing largely to the synergistic effect of the two metal oxides. Therefore, the proposed methodology can be used to modify existing and future composite electrodes to improve their performance with relatively cheap host and guest materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thermal aging effect of vanadyl acetylacetonate precursor for deposition of VO{sub 2} thin films with thermochromic properties

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

Yu, Jung-Hoon; Nam, Sang-Hun; Kim, Donguk

Highlights: • 7 day aged VO(acac){sub 2} sol shows enhanced adhesivity on the SiO{sub 2} compared with non-aged sol. • The aging process has significantly affected the morphologies of VO{sub 2} films. • From the FT-IR spectra, thermal aging process provides the deformation of precursor. • The metal insulator transition (MIT) efficiency (ΔT{sub at2000} {sub nm}) reached a maximum value of 51% at 7 day aging. • Thermal aging process could shorten the aging time of sol solution. - Abstract: Thermochromic properties of vanadium dioxide (VO{sub 2}) have been studied extensively due to their IR reflection applications in energy smartmore » windows. In this paper, we studied the optical switching property of VO{sub 2} thin film, depending on the thermal aging time of the vanadyl acetylacetonate (VO(acac){sub 2}) precursor. We found the alteration of the IR spectra of the precursor by tuning the aging time as well as heat treatments of the precursor. An aging effect of vanadium precursor directly affects the morphologies, optical switching property and crystallinity of VO{sub 2} films. The optimum condition was achieved at the 7 day aging time with metal insulator transition (MIT) efficiency of 50%.« less

Heavy metal absorbing Thioether-functionalized ligands derived from vegetable oils

USDA-ARS?s Scientific Manuscript database

Sulfur-functionalized vegetable oils containing thioether groups have been shown to effectively remove Ag+ from aqueous solution. Interestingly, the absorption capacity differs depending upon the choice of which vegetable oil precursor is functionalized. In this study, we will provide data for oils ...

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning

USDA-ARS?s Scientific Manuscript database

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the silver nitrate precursor in pre-electrospinning solutions into metallic silver nanoparticles, foll...

Process for the enhanced capture of heavy metal emissions

DOEpatents

Biswas, Pratim; Wu, Chang-Yu

2001-01-01

This invention is directed to a process for forming a sorbent-metal complex. The process includes oxidizing a sorbent precursor and contacting the sorbent precursor with a metallic species. The process further includes chemically reacting the sorbent precursor and the metallic species, thereby forming a sorbent-metal complex. In one particular aspect of the invention, at least a portion of the sorbent precursor is transformed into sorbent particles during the oxidation step. These sorbent particles then are contacted with the metallic species and chemically reacted with the metallic species, thereby forming a sorbent-metal complex. Another aspect of the invention is directed to a process for forming a sorbent metal complex in a combustion system. The process includes introducing a sorbent precursor into a combustion system and subjecting the sorbent precursor to an elevated temperature sufficient to oxidize the sorbent precursor and transform the sorbent precursor into sorbent particles. The process further includes contacting the sorbent particles with a metallic species and exposing the sorbent particles and the metallic species to a complex-forming temperature whereby the metallic species reacts with the sorbent particles thereby forming a sorbent-metal complex under UV irradiation.

High Performance, Low Temperature Solution-Processed Barium and Strontium Doped Oxide Thin Film Transistors.

PubMed

Banger, Kulbinder K; Peterson, Rebecca L; Mori, Kiyotaka; Yamashita, Yoshihisa; Leedham, Timothy; Sirringhaus, Henning

2014-01-28

Amorphous mixed metal oxides are emerging as high performance semiconductors for thin film transistor (TFT) applications, with indium gallium zinc oxide, InGaZnO (IGZO), being one of the most widely studied and best performing systems. Here, we investigate alkaline earth (barium or strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel layers and compare their performance of the electrical stress stability with IGZO. In films fabricated by solution-processing from metal alkoxide precursors and annealed to 450 °C we achieve high field-effect electron mobility up to 26 cm 2 V -1 s -1 . We show that it is possible to solution-process these materials at low process temperature (225-200 °C yielding mobilities up to 4.4 cm 2 V -1 s -1 ) and demonstrate a facile "ink-on-demand" process for these materials which utilizes the alcoholysis reaction of alkyl metal precursors to negate the need for complex synthesis and purification protocols. Electrical bias stress measurements which can serve as a figure of merit for performance stability for a TFT device reveal Sr- and Ba-doped semiconductors to exhibit enhanced electrical stability and reduced threshold voltage shift compared to IGZO irrespective of the process temperature and preparation method. This enhancement in stability can be attributed to the higher Gibbs energy of oxidation of barium and strontium compared to gallium.

High Performance, Low Temperature Solution-Processed Barium and Strontium Doped Oxide Thin Film Transistors

PubMed Central

2013-01-01

Amorphous mixed metal oxides are emerging as high performance semiconductors for thin film transistor (TFT) applications, with indium gallium zinc oxide, InGaZnO (IGZO), being one of the most widely studied and best performing systems. Here, we investigate alkaline earth (barium or strontium) doped InBa(Sr)ZnO as alternative, semiconducting channel layers and compare their performance of the electrical stress stability with IGZO. In films fabricated by solution-processing from metal alkoxide precursors and annealed to 450 °C we achieve high field-effect electron mobility up to 26 cm2 V–1 s–1. We show that it is possible to solution-process these materials at low process temperature (225–200 °C yielding mobilities up to 4.4 cm2 V–1 s–1) and demonstrate a facile “ink-on-demand” process for these materials which utilizes the alcoholysis reaction of alkyl metal precursors to negate the need for complex synthesis and purification protocols. Electrical bias stress measurements which can serve as a figure of merit for performance stability for a TFT device reveal Sr- and Ba-doped semiconductors to exhibit enhanced electrical stability and reduced threshold voltage shift compared to IGZO irrespective of the process temperature and preparation method. This enhancement in stability can be attributed to the higher Gibbs energy of oxidation of barium and strontium compared to gallium. PMID:24511184

Fluorine compounds for doping conductive oxide thin films

DOEpatents

Gessert, Tim; Li, Xiaonan; Barnes, Teresa M; Torres, Jr., Robert; Wyse, Carrie L

2013-04-23

Methods of forming a conductive fluorine-doped metal oxide layer on a substrate by chemical vapor deposition are described. The methods may include heating the substrate in a processing chamber, and introducing a metal-containing precursor and a fluorine-containing precursor to the processing chamber. The methods may also include adding an oxygen-containing precursor to the processing chamber. The precursors are reacted to deposit the fluorine-doped metal oxide layer on the substrate. Methods may also include forming the conductive fluorine-doped metal oxide layer by plasma-assisted chemical vapor deposition. These methods may include providing the substrate in a processing chamber, and introducing a metal-containing precursor, and a fluorine-containing precursor to the processing chamber. A plasma may be formed that includes species from the metal-containing precursor and the fluorine-containing precursor. The species may react to deposit the fluorine-doped metal oxide layer on the substrate.

Controlled Synthesis and Utilization of Metal and Oxide Hybrid Nanoparticles

NASA Astrophysics Data System (ADS)

Crane, Cameron

This dissertation reports the development of synthetic methods concerning rationally-designed, hybrid, and multifunctional nanomaterials. These methods are based on a wet chemical, solution phase approach that utilizes the knowledge of synthetic organic and inorganic chemistry to generate building blocks in solution for the growth of nanocrystals and hybrid nanostructures. This work builds on the prior knowledge of shape-controlled synthesis of noble metal nanocrystals and expands into the challenging realm of the more reactive first row transition metals. Specifically, a microemulsion sol-gel method was developed to synthesize Au-SiO2 dimers as precursors for the synthesis of segmented heterostructures of noble metals that can be used for catalysis. This microemulsion sol-gel method was modified to synthesize an aqueous suspension of oxidation-resistant Cu-SiO2 core-shell nanoparticles that can be used for sensing and catalysis. A thermal decomposition approach was developed, wherein zero-valence metal precursor complexes in the presence of seed nanoparticles produced metal-metal oxide core-shell structures with well-controlled shell thickness. This method was demonstrated on AuCu 3-Fe3O4, AuCu3-NiO, and AuCu3 -MnO core-shell systems. Switching the core from AuCu3 alloy to pure Cu, this method could extend to Cu-Fe3O4 and Cu-MnO systems. Further etching the Cu core in these core-shell structures led to the formation of the hollow metal oxides which provides a versatile route to hollow nanostructures of metal oxides. This work develops the synthetic library of tools for the production of hybrid nanostructures with multiple functionalities.

Attrition resistant fluidizable reforming catalyst

DOEpatents

Parent, Yves O [Golden, CO; Magrini, Kim [Golden, CO; Landin, Steven M [Conifer, CO; Ritland, Marcus A [Palm Beach Shores, FL

2011-03-29

A method of preparing a steam reforming catalyst characterized by improved resistance to attrition loss when used for cracking, reforming, water gas shift and gasification reactions on feedstock in a fluidized bed reactor, comprising: fabricating the ceramic support particle, coating a ceramic support by adding an aqueous solution of a precursor salt of a metal selected from the group consisting of Ni, Pt, Pd, Ru, Rh, Cr, Co, Mn, Mg, K, La and Fe and mixtures thereof to the ceramic support and calcining the coated ceramic in air to convert the metal salts to metal oxides.

Activated microporous materials through polymerization of microemulsion precursors

NASA Astrophysics Data System (ADS)

Venkatesan, Arunkumar

Microemulsions have been well studied for their unique characteristics. They are isotropic, thermodynamically stable and microstructured mixtures of oil and water stabilized by one or more surfactant species. They are formed spontaneously and are thermodynamically stable. Microemulsion precursors can be polymerized to make microporous solids with controlled pore structure and sizes. These polymeric solids have been studied extensively in the past. Although the fundamental properties of the microporous solids have been studied in depth, the development of specific applications that will utilize the unique properties of these solids has not been exhaustively researched. The current work establishes the feasibility of making activated microporous solids from microemulsion precursors, by the use of a ligand that chelates metals and also attaches itself to the polymer monolith. It also uses a novel 'in-situ' incorporation by combining the formulation and incorporation steps into one. The research objectives are, to formulate a microemulsion system that can yield useful microporous solids upon polymerization and activation, to characterize these solids using existing techniques available for analysis of similar microporous solids, to identify and understand the effect of the variables in the system and to study the influence of these variables on the performance characteristics of this material. Characterization techniques like Differential Scanning Calorimetry, Thermogravimetric Analysis and Scanning Electron Microscopy were used. A hydroxyethylmethylmethacrylate/methylmethacrylate/aqueous phase containing 10% SDS' system was chosen as the precursor microemulsion and the corresponding microporous solids were made. A metal chelating ligand, Congo Red, was incorporated onto the microporous polymer using NaOH as a binding agent. The ability of the resultant 'activated' microporous solid to remove metal ions from solution, was evaluated. The metal ion chosen was chromium and the influence of variables such as NaOH loading, Congo Red loading, Cross linker content etc. were studied. It was found that the microporous solids were effective in removing chromium from solution. They outperformed similar polymeric solids with ligands (reported in literature) in chromium removal. A removal of about 1500 micro moles of chromium ions per gram of dry polymer from a solution of 5 mMol/L initial concentration of chromium was observed. This is much more than the removal of 340 micro moles/gram of dry polymer reported in literature for comparable non-microporous systems.

From Mixed-Metal MOFs to Carbon-Coated Core-Shell Metal Alloy@Metal Oxide Solid Solutions: Transformation of Co/Ni-MOF-74 to CoxNi1-x@CoyNi1-yO@C for the Oxygen Evolution Reaction.

PubMed

Sun, Dengrong; Ye, Lin; Sun, Fangxiang; García, Hermenegildo; Li, Zhaohui

2017-05-01

Calcination of the mixed-metal species Co/Ni-MOF-74 leads to the formation of carbon-coated Co x Ni 1-x @Co y Ni 1-y O with a metal core diameter of ∼3.2 nm and a metal oxide shell thickness of ∼2.4 nm embedded uniformly in the ligand-derived carbon matrix. The close proximity of Co and Ni in the mixed-metal Co/Ni-MOF-74 promotes the metal alloying and the formation of a solid solution of metal oxide during the calcination process. The presence of the tightly coated carbon shell prohibits particle agglomeration and stabilizes the Co x Ni 1-x @Co y Ni 1-y O nanoparticles in small size. The Co x Ni 1-x @Co y Ni 1-y O@C derived from Co/Ni-MOF-74 nanocomposites show superior performance for the oxygen evolution reaction (OER). The use of mixed-metal MOFs as precursors represents a powerful strategy for the fabrication of metal alloy@metal oxide solid solution nanoparticles in small size. This method also holds great promise in the development of multifunctional carbon-coated complex core-shell metal/metal oxides owing to the diversified MOF structures and their flexible chemistry.

Fabricating porous materials using interpenetrating inorganic-organic composite gels

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

Seo, Dong-Kyun; Volosin, Alex

Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite materialmore » can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.« less

Aqueous route to facile, efficient and functional silica coating of metal nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Shah, Kwok Wei; Sreethawong, Thammanoon; Liu, Shu-Hua; Zhang, Shuang-Yuan; Tan, Li Sirh; Han, Ming-Yong

2014-09-01

Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields.Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03306j

Photochemical metal organic deposition of metal oxides

NASA Astrophysics Data System (ADS)

Law, Wai Lung (Simon)

This thesis pertains to the study of the deposition of metal oxide thin films via the process of Photochemical Metal Organic Deposition (PMOD). In this process, an amorphous metal organic precursor thin film is subjected to irradiation under ambient conditions. Fragmentation of the metal precursor results from the photoreaction, leading to the formation of metal oxide thin films in the presence of oxygen. The advantage of PMOD lies in its ability to perform lithography of metal oxide thin film without the application of photoresist. The metal organic precursor can be imaged directly by photolysis through a lithography mask under ambient conditions. Thus the PMOD process provides an attractive alternative to the conventional VLSI fabrication process. Metal carboxylates and metal acetylacetonates complexes were used as the precursors for PMOD process in this thesis. Transition metal carboxylate and metal acetylacetonate complexes have shown previously that when deposited as amorphous thin films, they will undergo fragmentation upon photolysis, leading to the formation of metal oxide thin films under ambient conditions. In this thesis, the formation of main group metal oxides of aluminum, indium and tin, as well as the formation of rare-earth metal oxides of cerium and europium by PMOD from its corresponding metal organic precursor will be presented. The nature of the photoreactions as well as the properties of the thin films deposited by PMOD will be investigated. Doped metal oxide thin films can also be prepared using the PMOD process. By mixing the metal precursors prior to deposition in the desired ratio, precursor films containing more than one metal precursor can be obtained. Mixed metal oxide thin films corresponding to the original metal ratio, in the precursor mixture, can be obtained upon photolysis under ambient conditions. In this thesis, the properties of doped metal oxide thin films of europium doped aluminum oxide as well as tin doped indium oxide thin films will also be presented.

Chemical routes to nanocrystalline and thin-film III-VI and I-III-VI semiconductors

NASA Astrophysics Data System (ADS)

Hollingsworth, Jennifer Ann

1999-11-01

The work encompasses: (1) catalyzed low-temperature, solution-based routes to nano- and microcrystalline III-VI semiconductor powders and (2) spray chemical vapor deposition (spray CVD) of I-III-VI semiconductor thin films. Prior to this work, few, if any, examples existed of chemical catalysis applied to the synthesis of nonmolecular, covalent solids. New crystallization strategies employing catalysts were developed for the regioselective syntheses of orthorhombic InS (beta-InS), the thermodynamic phase, and rhombohedral InS (R-InS), a new, metastable structural isomer. Growth of beta-InS was facilitated by a solvent-suspended, molten-metal flux in a process similar to the SolutionLiquid-Solid (SLS) growth of InP and GaAs fibers and single-crystal whiskers. In contrast, metastable R-InS, having a pseudo-graphitic layered structure, was prepared selectively when the molecular catalyst, benzenethiol, was present in solution and the inorganic "catalyst" (metal flux) was not present. In the absence of any crystal-growth facilitator, metal flux or benzenethiol, amorphous product was obtained under the mild reaction conditions employed (T ≤ 203°C). The inorganic and organic catalysts permitted the regio-selective syntheses of InS and were also successfully applied to the growth of network and layered InxSey compounds, respectively, as well as nanocrystalline In2S3. Extensive microstructural characterization demonstrated that the layered compounds grew as fullerene-like nanostructures and large, colloidal single crystals. Films of the I-III-VI compounds, CuInS2, CuGaS2, and Cu(In,Ga)S 2, were deposited by spray CVD using the known single-source metalorganic precursor, (Ph3P)2CuIn(SEt)4, a new precursor, (Ph3P)2CuGa(SEt)3, and a mixture of the two precursors, respectively. The CulnS2 films exhibited a variety of microstructures from dense and faceted or platelet-like to porous and dendritic. Crystallographic orientations ranged from strongly [112] to strongly [220] oriented. Microstructure, orientation, and growth kinetics were controlled by changing processing parameters: carrier-gas flow rate, substrate temperature, and precursor-solution concentration. Low resistivities (<50 O cm) were associated with [220]-oriented films. All CuInS2 films were approximately stoichiometric and had the desired bandgap (Eg ≅ 1.4 eV) for application as the absorber layer in thin-film photovoltaic devices.

Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

DOEpatents

Dhere, Neelkanth G.; Kadam, Ankur A.

2009-12-15

A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

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.

Active and Durable Hydrogen Evolution Reaction Catalyst Derived from Pd-Doped Metal-Organic Frameworks.

PubMed

Chen, Jitang; Xia, Guoliang; Jiang, Peng; Yang, Yang; Li, Ren; Shi, Ruohong; Su, Jianwei; Chen, Qianwang

2016-06-01

The water electrolysis is of critical importance for sustainable hydrogen production. In this work, a highly efficient and stable PdCo alloy catalyst (PdCo@CN) was synthesized by direct annealing of Pd-doped metal-organic frameworks (MOFs) under N2 atmosphere. In 0.5 M H2SO4 solution, PdCo@CN displays remarkable electrocatalytic performance with overpotential of 80 mV, a Tafel slope of 31 mV dec(-1), and excellent stability of 10 000 cycles. Our studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.

Synthesis of branched metal nanostructures with controlled architecture and composition

NASA Astrophysics Data System (ADS)

Ortiz, Nancy

On account of their small size, metal nanoparticles are proven to be outstanding catalysts for numerous chemical transformations and represent promising platforms for applications in the fields of electronics, chemical sensing, medicine, and beyond. Many properties of metal nanoparticles are size-dependent and can be further manipulated through their shape and architecture (e.g., spherical vs. branched). Achieving morphology control of nanoparticles through solution-based techniques has proven challenging due to limited knowledge of morphology development in nanosyntheses. To overcome these complications, a systematic examination of the local ligand environment of metal precursors on nanostructure formation was undertaken to evaluate its contribution to nanoparticle nucleation rate and subsequent growth processes. Specifically, this thesis will provide evidence from ex situ studies---Transmission Electron Microscopy (TEM) and UV-visible spectroscopy (UV-Vis)---that support the hypothesis that strongly coordinated ligands delay burst-like nucleation to generate spherical metal nanoparticles and ligands with intermediate binding affinity regulate the gradual reduction of metal precursors to promote aggregated assembly of nanodendrites. These ex situ studies were coupled with a new in situ perspective, providing detailed understanding of metal precursor transformation, its direct relation to nanoparticle morphology development, and the ligand influence towards the formation of structurally complex metal nanostructures, using in situ synchrotron X-ray Diffraction (XRD) and Ultra Small-Angle X-ray Scattering (USAXS). The principles extracted from the study of monometallic nanostructure formation were also found to be generally applicable to the synthesis of bimetallic nanostructures, e.g., Pd-Pt architectures, with either core-shell or alloyed structures that were readily achieved by ligand selection. These outcomes provide a direct connection between fundamental principles of coordination chemistry and nanoparticle formation, with a stronger foundation for the predictive synthesis of future nanomaterials with controllable structural features.

Polymer-assisted deposition of films and preparation of carbon nanotube arrays using the films

DOEpatents

Luo, Hongmei; Li, Qingwen; Bauer, Eve; Burrell, Anthony Keiran; McCleskey, Thomas Mark; Jia, Quanxi

2013-07-16

Carbon nanotubes were prepared by coating a substrate with a coating solution including a suitable solvent, a soluble polymer, a metal precursor having a first metal selected from iron, nickel, cobalt, and molybdenum, and optionally a second metal selected from aluminum and magnesium, and also a binding agent that forms a complex with the first metal and a complex with the second metal. The coated substrate was exposed to a reducing atmosphere at elevated temperature, and then to a hydrocarbon in the reducing atmosphere. The result was decomposition of the polymer and formation of carbon nanotubes on the substrate. The carbon nanotubes were often in the form of an array on the substrate.

Synthesis of SnO2 and Ag Nanoparticles from Electronic Wastes with the Assistance of Ultrasound and Microwaves

NASA Astrophysics Data System (ADS)

Cerchier, Pietrogiovanni; Dabalà, Manuele; Brunelli, Katya

2017-09-01

In this work, SnO2 and Ag nanoparticles were produced with a raw material nitric acid solution, which came from the leaching of printed circuit boards. First, a precursor of tin oxide was precipitated from the nitric acid solution by three different techniques: (I) conventional heating, (II) microwave irradiation, and (III) ultrasound treatment. Second, this precursor was transformed into tin oxide nanoparticles by heat treatment in a furnace. Third, hydrochloric acid was added to the nitric acid solution to induce the precipitation of silver chloride. Fourth, silver chloride was reduced to metallic silver nanoparticles in an ammonia solution using glucose syrup as both the reducing agent and the capping agent. The reduction reaction was carried out through (I) conventional heating, (II) microwave irradiation, and (III) ultrasound treatment. The nanoparticles were characterized by scanning electron microscope (SEM), x-ray diffractometer (XRD), infrared (IR)-spectroscopy, transmission electron microscope (TEM), ultraviolet (UV)-spectroscopy, and laser diffraction particle size analyzer.

Method for producing microcomposite powders using a soap solution

DOEpatents

Maginnis, Michael A.; Robinson, David A.

1996-01-01

A method for producing microcomposite powders for use in superconducting and non-superconducting applications. A particular method to produce microcomposite powders for use in superconducting applications includes the steps of: (a) preparing a solution including ammonium soap; (b) dissolving a preselected amount of a soluble metallic such as silver nitrate in the solution including ammonium soap to form a first solution; (c) adding a primary phase material such as a single phase YBC superconducting material in particle form to the first solution; (d) preparing a second solution formed from a mixture of a weak acid and an alkyl-mono-ether; (e) adding the second solution to the first solution to form a resultant mixture; (f) allowing the resultant mixture to set until the resultant mixture begins to cloud and thicken into a gel precipitating around individual particles of the primary phase material; (g) thereafter drying the resultant mixture to form a YBC superconducting material/silver nitrate precursor powder; and (h) calcining the YBC superconducting material/silver nitrate precursor powder to convert the silver nitrate to silver and thereby form a YBC/silver microcomposite powder wherein the silver is substantially uniformly dispersed in the matrix of the YBC material.

Adsorptive separation and photocatalytic degradation of methylene blue dye on titanate nanotube powders prepared by hydrothermal process using metal Ti particles as a precursor.

PubMed

Hu, Keshui; Xiao, Xin; Cao, Xiufang; Hao, Rong; Zuo, Xiaoxi; Zhang, Xiaojing; Nan, Junmin

2011-08-30

Titanate nanotube powders (TNTPs) with the twofold removal ability, i.e. adsorptive separation and photocatalytic degradation, are synthesized under hydrothermal conditions using metal Ti particles as a precursor in the concentrated alkaline solution, and their morphology, structure, adsorptive and photocatalytic properties are investigated. Under hydrothermal conditions, the titanate nanotubes (TNTs) with pore diameter of 3-4nm are produced on the surface of metal Ti particles, and stacked together to form three-dimensional (3D) network with porous structure. The TNTPs synthesized in the autoclave at 130°C for 24h exhibits a maximum adsorption capability of about 197mg g(-1) in the neutral methylene blue (MB) solution (40mg L(-1)) within 90min, the adsorption process can be described by pseudo second-order kinetics model. Especially, in comparison with the adsorptive and the photocatalytic processes are performed in turn, about 50min can be saved through synchronously utilizing the double removal ability of TNTPs when the removal ratio of MB approaches 95% in MB solution (40mg L(-1)) at a solid-liquid (S/L) ratio of 1:8 under ultraviolet (UV) light irradiation. These 3D TNTPs with the twofold removal properties and easier separation ability for recycling use show promising prospect for the treatment of dye pollutants from wastewaters in future industrial application. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis of two-dimensional titanium nitride Ti4N3 (MXene)

NASA Astrophysics Data System (ADS)

Urbankowski, Patrick; Anasori, Babak; Makaryan, Taron; Er, Dequan; Kota, Sankalp; Walsh, Patrick L.; Zhao, Mengqiang; Shenoy, Vivek B.; Barsoum, Michel W.; Gogotsi, Yury

2016-06-01

We report on the synthesis of the first two-dimensional transition metal nitride, Ti4N3-based MXene. In contrast to the previously reported MXene synthesis methods - in which selective etching of a MAX phase precursor occurred in aqueous acidic solutions - here a molten fluoride salt is used to etch Al from a Ti4AlN3 powder precursor at 550 °C under an argon atmosphere. We further delaminated the resulting MXene to produce few-layered nanosheets and monolayers of Ti4N3Tx, where T is a surface termination (F, O, or OH). Density functional theory calculations of bare, non-terminated Ti4N3 and terminated Ti4N3Tx were performed to determine the most energetically stable form of this MXene. Bare and functionalized Ti4N3 are predicted to be metallic. Bare Ti4N3 is expected to show magnetism, which is significantly reduced in the presence of functional groups.We report on the synthesis of the first two-dimensional transition metal nitride, Ti4N3-based MXene. In contrast to the previously reported MXene synthesis methods - in which selective etching of a MAX phase precursor occurred in aqueous acidic solutions - here a molten fluoride salt is used to etch Al from a Ti4AlN3 powder precursor at 550 °C under an argon atmosphere. We further delaminated the resulting MXene to produce few-layered nanosheets and monolayers of Ti4N3Tx, where T is a surface termination (F, O, or OH). Density functional theory calculations of bare, non-terminated Ti4N3 and terminated Ti4N3Tx were performed to determine the most energetically stable form of this MXene. Bare and functionalized Ti4N3 are predicted to be metallic. Bare Ti4N3 is expected to show magnetism, which is significantly reduced in the presence of functional groups. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02253g

Magnetic particles

NASA Technical Reports Server (NTRS)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

1989-01-01

Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

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

Leppäniemi, J., E-mail: jaakko.leppaniemi@vtt.fi; Ojanperä, K.; Kololuoma, T.

We propose a combined far ultraviolet (FUV) and thermal annealing method of metal-nitrate-based precursor solutions that allows efficient conversion of the precursor to metal-oxide semiconductor (indium zinc oxide, IZO, and indium oxide, In{sub 2}O{sub 3}) both at low-temperature and in short processing time. The combined annealing method enables a reduction of more than 100 °C in annealing temperature when compared to thermally annealed reference thin-film transistor (TFT) devices of similar performance. Amorphous IZO films annealed at 250 °C with FUV for 5 min yield enhancement-mode TFTs with saturation mobility of ∼1 cm{sup 2}/(V·s). Amorphous In{sub 2}O{sub 3} films annealed for 15 min with FUV atmore » temperatures of 180 °C and 200 °C yield TFTs with low-hysteresis and saturation mobility of 3.2 cm{sup 2}/(V·s) and 7.5 cm{sup 2}/(V·s), respectively. The precursor condensation process is clarified with x-ray photoelectron spectroscopy measurements. Introducing the FUV irradiation at 160 nm expedites the condensation process via in situ hydroxyl radical generation that results in the rapid formation of a continuous metal-oxygen-metal structure in the film. The results of this paper are relevant in order to upscale printed electronics fabrication to production-scale roll-to-roll environments.« less

Laser-driven coating of vertically aligned carbon nanotubes with manganese oxide from metal organic precursors for energy storage.

PubMed

Pérez Del Pino, A; György, E; Alshaikh, I; Pantoja-Suárez, F; Andújar, J L; Pascual, E; Amade, R; Bertran-Serra, E

2017-09-29

Carbon nanotubes-transition metal oxide systems are intensively studied due to their excellent properties for electrochemical applications. In this work, an innovative procedure is developed for the synthesis of vertically aligned multi-walled carbon nanotubes (VACNTs) coated with transition metal oxide nanostructures. VACNTs are grown by plasma enhanced chemical vapor deposition and coated with a manganese-based metal organic precursor (MOP) film based on manganese acetate solution. Subsequent UV pulsed laser irradiation induces the effective heating-decomposition of the MOP leading to the crystallization of manganese oxide nanostructures on the VACNT surface. The study of the morphology, structure and composition of the synthesized materials shows the formation of randomly oriented MnO 2 crystals, with few nanometers in size, and to their alignment in hundreds of nm long filament-like structures, parallel to the CNT's long axis. Electrochemical measurements reveal a significant increase of the specific capacitance of the MnO 2 -VACNT system (100 F g -1 ) as compared to the initial VACNT one (21 F g -1 ).

Laser-driven coating of vertically aligned carbon nanotubes with manganese oxide from metal organic precursors for energy storage

NASA Astrophysics Data System (ADS)

Pérez del Pino, A.; György, E.; Alshaikh, I.; Pantoja-Suárez, F.; Andújar, J. L.; Pascual, E.; Amade, R.; Bertran-Serra, E.

2017-09-01

Carbon nanotubes-transition metal oxide systems are intensively studied due to their excellent properties for electrochemical applications. In this work, an innovative procedure is developed for the synthesis of vertically aligned multi-walled carbon nanotubes (VACNTs) coated with transition metal oxide nanostructures. VACNTs are grown by plasma enhanced chemical vapor deposition and coated with a manganese-based metal organic precursor (MOP) film based on manganese acetate solution. Subsequent UV pulsed laser irradiation induces the effective heating-decomposition of the MOP leading to the crystallization of manganese oxide nanostructures on the VACNT surface. The study of the morphology, structure and composition of the synthesized materials shows the formation of randomly oriented MnO2 crystals, with few nanometers in size, and to their alignment in hundreds of nm long filament-like structures, parallel to the CNT’s long axis. Electrochemical measurements reveal a significant increase of the specific capacitance of the MnO2-VACNT system (100 F g-1) as compared to the initial VACNT one (21 F g-1).

Reactive Molecular Dynamics Investigations of Alkoxysilane Sol-Gel and Surface Coating Processes

NASA Astrophysics Data System (ADS)

Deetz, Joshua David

The ability to generate nanostructured materials with tailored morphology or chemistry is of great technological interest. One proven method of generating metal-oxide materials, and chemically modifying metal-oxide surfaces is through the reactions of molecular building blocks known as alkoxysilanes. Alkoxysilanes are a class of chemicals which contain one or more organic alkoxy groups bonded to silicon atoms. Alkoxysilane (Si-O-R) chemical groups can undergo reactions to form bridges (Si-O-M) with metal oxides. Due to their ability to "attach" to metal-oxides through condensation reactions, alkoxysilanes have a number of interesting applications, such as: the generation of synthetic siloxane materials through the sol-gel process, and the formation of functionalized surface coatings on metal-oxide surfaces. Despite widespread study of sol-gel and surface coatings processes, it is difficult to predict the morphology of the final products due to the large number of process variables involved, such as precursor molecule structure, solvent effects, solution composition, temperature, and pH. To determine the influence of these variables on the products of sol-gel and coatings processes reactive molecular dynamics simulations are used. A reactive force field was used (ReaxFF) to allow the chemical bonds in simulation to dynamically form and break. The force field parameters were optimized using a parallel optimization scheme with a combination of experimental information, and density functional theory calculations. Polycondensation of alkoxysilanes in mixtures of alcohol and water were studied. Steric effects were observed to influence the rates of hydrolysis and condensation in solutions containing different precursor monomers. By restricting the access of nucleophiles to the central silicon atom, the nucleation rate of siloxanes can be controlled. The influence of solution precursor, water, and methanol composition on reaction rates was explored. It was determined that the rate of alkoxysilane hydrolysis is strongly dependent on the concentration of water. The dynamics of siloxane cluster formation are revealed, which provides insight for experimentalists. The silanization of hydroxylated silica surfaces by alkoxysilanes was modeled in pseudo-infinite liquid solution. Butyl-, octyl-, or dodecylsilanes were exposed to hydroxylated silica surfaces in order to observe the influence of silyl headgroup size on the morphology and formation kinetics of silane films on silica substrates. The radius of gyration and order parameter of the hydrocarbon silyl groups were found to increase with grafting density. This was the first simulation study of the dynamic grafting of alkoxysilanes to a substrate.

Microplasma-liquid interactions for nanomaterials synthesis

NASA Astrophysics Data System (ADS)

Patel, Jenish; Maguire, Paul; Mariotti, Davide

2012-10-01

Interactions of microplasmas with solid, liquid and/or gas precursors provide new pathways for the synthesis and surface-engineering of nanomaterials. This study is focused on the plasma-induced non-euqilibrium liquid-chemistry (PiLC) as an effective approach to synthesize colloidal metal nanoparticles without using any reducing/capping agents. Highly dispersed gold and silver nanoparticles (NPs) were synthesized in aqueous solutions without any capping agents which explore the opportunities to functionalize the surface of these surfactant-free metal NPs for a better device applications. In particular, various sizes (5 nm to 100 nm) and shapes (e.g. spherical, hexagonal, pentagonal, triangular, etc.) of the gold nanoparticles (AuNPs) were formed with different concentrations of gold precursor. Moreover, conductivity, pH and temperature of the solutions were measured before and after the plasma processing, in order to realize the basic chemistry initiated by plasma in/at liquid surface. Especially, to understand the basic reduction process of AuNPs synthesis by plasma, we measured the presence the of hydrogen peroxide (H2O2) which is believed to be a strong reductant for gold and for the first time we demonstrated experimentally that H2O2 is the key factor that reduces the gold precursor to AuNPs. These investigations create the opportunities to understand how these microplasmas can be effectively explored to other materials synthesis/processing.

Preparation of cuxinygazsen precursor films and powders by electroless deposition

DOEpatents

Bhattacharya, Raghu N.; Batchelor, Wendi Kay; Wiesner, Holm; Ramanathan, Kannan; Noufi, Rommel

1999-01-01

A method for electroless deposition of Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3) precursor films and powders onto a metallic substrate comprising: preparing an aqueous bath solution of compounds selected from the group consisting of: I) a copper compound, a selenium compound, an indium compound and gallium compound; II) a copper compound, a selenium compound and an indium compound; III) a selenium compound, and indium compound and a gallium compound; IV) a selenium compound and a indium compound; and V) a copper compound and selenium compound; each compound being present in sufficient quantity to react with each other to produce Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3); adjusting the pH of the aqueous bath solution to an acidic value by the addition of a dilute acid; and initiating an electroless reaction with an oxidizing counterelectrode for a sufficient time to cause a deposit of Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3) from the aqueous bath solution onto a metallic substrate.

Solution based zinc tin oxide TFTs: the dual role of the organic solvent

NASA Astrophysics Data System (ADS)

Salgueiro, Daniela; Kiazadeh, Asal; Branquinho, Rita; Santos, Lídia; Barquinha, Pedro; Martins, Rodrigo; Fortunato, Elvira

2017-02-01

Chemical solution deposition is a low cost, scalable and high performance technique to obtain metal oxide thin films. Recently, solution combustion synthesis has been introduced as a chemical route to reduce the processing temperature. This synthesis method takes advantage of the chemistry of the precursors as a source of energy for localized heating. According to the combustion chemistry some organic solvents can have a dual role in the reaction, acting both as solvent and fuel. In this work, we studied the role of 2-methoxyethanol in solution based synthesis of ZTO thin films and its influence on the performance of ZTO TFTs. The thermal behaviour of ZTO precursor solutions confirmed that 2-methoxyethanol acts simultaneously as a solvent and fuel, replacing the fuel function of urea. The electrical characterization of the solution based ZTO TFTs showed a slightly better performance and lower variability under positive gate bias stress when urea was not used as fuel, confirming that the excess fuel contributes negatively to the device operation and stability. Solution based ZTO TFTs demonstrated a low hysteresis (ΔV  =  -0.3 V) and a saturation mobility of 4-5 cm2 V-1 s-1.

Coordination Polymerization of Renewable 3-Methylenecyclopentene with Rare-Earth-Metal Precursors.

PubMed

Liu, Bo; Li, Shihui; Wang, Meiyan; Cui, Dongmei

2017-04-10

Coordination polymerization of renewable 3-methylenecyclopentene has been investigated for the first time using rare-earth metal-based precursors bearing various bulky ligands. All the prepared complexes catalyze controllable polymerization of 3-methylenecyclopentene into high molecular weight polymers, of which the NPN- and NSN-tridentate non-Cp ligated lutetium-based catalytic systems exhibited extremely high activities up to 11 520 kg/(mol Lu ⋅h) in a dilute toluene solution (3.2 g/100 mL) at room temperature. The resultant polymers have pure 1,4-regioregularity (>99 %) and tailorable number average molecular weights (1-20×10 4 ) with narrow molecular weight distributions (polydispersity index (PDI)=1.45-1.79). DFT simulations were employed to study the polymerization mechanism and stereoregularity control. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formation and growth mechanisms of single-walled metal oxide nanotubes

NASA Astrophysics Data System (ADS)

Yucelen, Gulfem Ipek

In this thesis, main objectives are to discover the first molecular-level mechanistic framework governing the formation and growth of single-walled metal-oxide nanotubes, apply this framework to demonstrate the engineering of nanotubular materials of controlled dimensions, and to progress towards a quantitative multiscale understanding of nanotube formation. In Chapter 2, the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature, in the formation of single-walled aluminosilicate nanotubes is reported. The structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm, are characterized by electrospray ionization (ESI) mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. DFT calculations revealed the intrinsic curvature of nanoscale intermediates with bonding environments similar to the structure of the final nanotube product. It is shown that curved nano-intermediates form in aqueous synthesis solutions immediately after initial hydrolysis of reactants at 25 °C, disappear from the solution upon heating to 95 °C due to condensation, and finally rearrange to form ordered single-walled aluminosilicate nanotubes. Integration of all results leads to the construction of the first molecular-level mechanism of single-walled metal oxide nanotube formation, incorporating the role of monomeric and polymeric aluminosilicate species as well as larger nanoparticles. Then, in Chapter 3, new molecular-level concepts for constructing nanoscopic metal oxide objects are demonstrated. The diameters of metal oxide nanotubes are shaped with Angstrom-level precision by controlling the shape of nanometer-scale precursors. The subtle relationships between precursor shape and structure and final nanotube curvature are measured (at the molecular level). Anionic ligands (both organic and inorganic) are used to exert fine control over precursor shapes, allowing assembly into nanotubes whose diameters relate directly to the curvatures of shaped precursors. Having obtained considerable insight into aluminosilicate nanotube formation, in Chapter 4 the complex aqueous chemistry of nanotube-forming aluminogermanate solutions are examined. The aluminogermanate system is particularly interesting since it forms ultra-short nanotubes of lengths as small as ˜20 nm. Insights into the underlying important mechanistic differences between aluminogermanate and aluminosilicate nanotube growth as well as structural differences in the final nanotube dimensions are provided. Furthermore, an experimental example of control over nanotube length is shown, using the understanding of the mechanistic differences, along with further suggestions for possible ways of controlling nanotube lengths. In Chapter 5, a generalized kinetic model is formulated to describe the reactions leading to formation and growth of single-walled metal oxide nanotubes. This model is capable of explaining and predicting the evolution of nanotube populations as a function of kinetic parameters. It also allows considerable insight into meso/microscale nanotube growth processes. For example, it shows that two different mechanisms operate during nanotube growth: (1) growth by precursor addition, and (2) by oriented attachment of nanotubes to each other. In Chapter 6, a study of the structure of the nanotube walls is presented. A detailed investigation of the defect structures in aluminosilicate single-walled nanotubes via multiple advanced solid-state NMR techniques is reported. A combination of 1H-29Si and 1H- 27Al FSLG-HETCOR, 1H CRAMPS, and 1H- 29Si CP/MAS NMR experiments were employed to evaluate the proton environments around Al and Si atoms during nanotube synthesis and in the final structure. The HETCOR experiments allowed to track the evolving Si and Al environments during the formation of the nanotubes from precursor species, and relate them to the Si and Al coordination environments found in the final nanotube structure. (Abstract shortened by UMI.).

Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells

PubMed Central

Zhang, Wei; Pathak, Sandeep; Sakai, Nobuya; Stergiopoulos, Thomas; Nayak, Pabitra K.; Noel, Nakita K.; Haghighirad, Amir A.; Burlakov, Victor M.; deQuilettes, Dane W.; Sadhanala, Aditya; Li, Wenzhe; Wang, Liduo; Ginger, David S.; Friend, Richard H.; Snaith, Henry J.

2015-01-01

Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce the oxidized I2 back into I−, and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead. PMID:26615763

Atomic layer deposition of metal sulfide thin films using non-halogenated precursors

DOEpatents

Martinson, Alex B. F.; Elam, Jeffrey W.; Pellin, Michael J.

2015-05-26

A method for preparing a metal sulfide thin film using ALD and structures incorporating the metal sulfide thin film. The method includes providing an ALD reactor, a substrate, a first precursor comprising a metal and a second precursor comprising a sulfur compound. The first and the second precursors are reacted in the ALD precursor to form a metal sulfide thin film on the substrate. In a particular embodiment, the metal compound comprises Bis(N,N'-di-sec-butylacetamidinato)dicopper(I) and the sulfur compound comprises hydrogen sulfide (H.sub.2S) to prepare a Cu.sub.2S film. The resulting metal sulfide thin film may be used in among other devices, photovoltaic devices, including interdigitated photovoltaic devices that may use relatively abundant materials for electrical energy production.

Lead acetate trihydrate precursor route to synthesize novel ultrafine lead oxide from spent lead acid battery pastes

NASA Astrophysics Data System (ADS)

Sun, Xiaojuan; Yang, Jiakuan; Zhang, Wei; Zhu, Xinfeng; Hu, Yuchen; Yang, Danni; Yuan, Xiqing; Yu, Wenhao; Dong, Jinxin; Wang, Haifeng; Li, Lei; Vasant Kumar, R.; Liang, Sha

2014-12-01

A novel green recycling process is investigated to prepare lead acetate trihydrate precursors and novel ultrafine lead oxide from spent lead acid battery pastes. The route contains the following four processes. (1) The spent lead pastes are desulphurized by (NH4)2CO3. (2) The desulphurized pastes are converted into lead acetate solution by leaching with acetic acid solution and H2O2; (3) The Pb(CH3COO)2·3H2O precursor is crystallized and purified from the lead acetate solution with the addition of glacial acetic acid; (4) The novel ultrafine lead oxide is prepared by the calcination of lead acetate trihydrate precursor in N2 or air at 320-400 °C. Both the lead acetate trihydrate and lead oxide products are characterized by TG-DTA, XRD, and SEM techniques. The calcination products are mainly α-PbO, β-PbO, and a small amount of metallic Pb. The particle size of the calcination products in air is significantly larger than that in N2. Cyclic voltammetry measurements of the novel ultrafine lead oxide products show good reversibility and cycle stability. The assembled batteries using the lead oxide products as cathode active materials show a good cyclic stability in 80 charge/discharge cycles with the depth of discharge (DOD) of 100%.

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

NASA Astrophysics Data System (ADS)

Seisenbaeva, Gulaim A.; Kessler, Vadim G.

2014-05-01

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

Fibrous selective emitter structures from sol-gel process

NASA Astrophysics Data System (ADS)

Chen, K. C.

1999-03-01

Selective emitters have the potential benefit of high efficiency due to the matching of emission spectra to the response of photovoltaic (PV) cells. Continuous uniform rare-earth oxide selective emitter fibers were successfully fabricated using a viscous solution made from metal organic precursors. Cylindrical- and planar configuration emitter structures were made by direct cross-winding or stacking of precursor fiber layers. The combustion and optical performance of the planar emitter structures were tested. The results indicates that both the designing of the fiber packing density and the thickness is critical for high photon and power output.

Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines

NASA Astrophysics Data System (ADS)

Varanasi, Venu Gopal

The gas turbine engine uses an yttria-stabilized zirconia (YSZ) coating to provide thermal insulation for its turbine blades. This YSZ coating must be tetragonal in crystal structure, columnar in microstructure, and be 100--250 mum thick to provide for adequate protection for the turbine blades in the severe engine environment. Currently, YSZ coatings are fabricated by electron-beam physical vapor deposition (EB-PVD), but this fabrication method is cost intensive. Chemical vapor deposition (CVD) is a more commercially viable processing method and a possible alternative to EB-PVD. The deposition of tetragonal YSZ from gaseous metal and oxidation sources were studied. A chemical equilibrium analysis modeled the feasibility of depositing tetragonal YSZ for both chloride CVD (Zr-Y-C-O-Cl-H-Inert system) and metal-organic CVD (MOCVD) (Zr-Y-C-O-H system). Pure thermochemical properties and the assessed YSZ phase diagram were used in this analysis. Using the molar input of metals ((nY + nZr) and ( nY/(nY + nZr ) = 0.08)) as bases, equilibrium calculations showed that tetragonal YSZ formation was feasible. Tetragonal YSZ formation was feasible with high oxygen content (nO/(nY + nZr) > 8) and high temperature (T > 100°C) in the case of chloride CVD (Zr-Y-C-O-Cl-H-Inert). Tetragonal YSZ formation was feasible with high oxygen content (nO/( nY + nZr) > 5) and high temperature (T > 950°C) in the case of MOCVD (Zr-Y-C-O-H). Although solid carbon formation did not appear in chloride CVD, additional oxygen (nO/( nY + nZr) > 32) and low hydrogen content relative to carbon (nH/nC < 2) were required to avoid solid carbon formation in MOCVD. Coatings were deposited using a set of base conditions derived from the chemical equilibrium analysis. In chloride CVD, YCl3 was not included because of its low vapor pressure, thus, ZrCl4 was oxidized with the H2-CO2 gas mixture. Monoclinic ZrO2 coatings were deposited at the thermochemically optimized conditions (n O/(nY + nZr) > 8, T > 1004°C) with approximately 5.5 mum h-1 growth rate. In metal-organic CVD (MOCVD), liquid precursor solutions of Y- and Zr-beta-diketonate and Y- and Zr-n-butoxide precursors were used as the metal sources and O2 gas was used as the oxidation source. Using the Y- and Zr-beta-diketonate liquid precursor solution, tetragonal YSZ was deposited with a layered microstructure apparent and a maximum growth rate of approximately 14 mum h-1 (activation energy (E a) of 50.9 +/- 4.3 kJ mol-1). The growth rate (approximately 43 mum h-1 with Ea = 53.8 +/- 7.9 kJ mol-1) was improved using Y- and Zr- n-butoxide liquid precursor solutions, and the microstructure was columnar. Yet, two-phase deposition of monoclinic ZrO2 and tetragonal YSZ occurred. Results of electron-probe micro-analysis showed that the nY/(nY + nZr ) ratio was less than 45% of the nY/( nY + nZr) ratio in the liquid precursor solution.

Solution-deposited CIGS thin films for ultra-low-cost photovoltaics

NASA Astrophysics Data System (ADS)

Eldada, Louay A.; Hersh, Peter; Stanbery, Billy J.

2010-09-01

We describe the production of photovoltaic modules with high-quality large-grain copper indium gallium selenide (CIGS) thin films obtained with the unique combination of low-cost ink-based precursors and a reactive transfer printing method. The proprietary metal-organic inks contain a variety of soluble Cu-, In- and Ga- multinary selenide materials; they are called metal-organic decomposition (MOD) precursors, as they are designed to decompose into the desired precursors. Reactive transfer is a two-stage process that produces CIGS through the chemical reaction between two separate precursor films, one deposited on the substrate and the other on a printing plate in the first stage. In the second stage, these precursors are rapidly reacted together under pressure in the presence of heat. The use of two independent thin films provides the benefits of independent composition and flexible deposition technique optimization, and eliminates pre-reaction prior to the synthesis of CIGS. In a few minutes, the process produces high quality CIGS films, with large grains on the order of several microns, and preferred crystallographic orientation, as confirmed by compositional and structural analysis by XRF, SIMS, SEM and XRD. Cell efficiencies of 14% and module efficiencies of 12% were achieved using this method. The atmospheric deposition processes include slot die extrusion coating, ultrasonic atomization spraying, pneumatic atomization spraying, inkjet printing, direct writing, and screen printing, and provide low capital equipment cost, low thermal budget, and high throughput.

Synthesis and characterization of amorphous yttrium oxide layers by metal organic chemical solution deposition

NASA Astrophysics Data System (ADS)

Martynova, I.; Tsymbarenko, D.; Kamenev, A.; Kuzmina, N.; Kaul, A.

2014-02-01

The Solution Deposition Planarization method was successfully used for smoothing Ni-alloy tapes with initial surface roughness of 26.7 nm (on 40×40 μm2 area) and 12.6 nm (on 5×5 μm2 area). New precursor solutions were prepared from yttrium acetate and diethylenetriamine or ethylenediamine in MeOH and i-PrOH-alcohols with different viscosities. Using those solutions yttria films with the residual roughness Sa=0.4 nm (on 5×5 μm2 area) and Sa=7.6 nm (on 40×40 μm2 area) were deposited on the Ni-alloy tapes.

Numerical simulation of crevice corrosion of titanium: Effect of the bold surface

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

Evitts, R.W.; Postlethwaite, J.; Watson, M.K.

1996-12-01

A rigorous crevice corrosion model has been developed that accounts for the bold metal surfaces exterior to the crevice. The model predicts the time change in concentration of all specified chemical species in the crevice and bulk solution, and has the ability to predict active corrosion. It is applied to the crevice corrosion of a small titanium crevice in both oxygenated and anaerobic sodium chloride solutions. The numerical predictions confirm that oxygen is the driving force for crevice corrosion. During the simulations where oxygen is initially present in both the crevice and bulk solution an acidic chloride solution is developed;more » this is the precursor required for crevice corrosion. The anaerobic case displays no tendency to form such a solution. It is also confirmed that those areas in the crevice that are deoxygenated become anodic and the bold metal surface becomes cathodic. As expected, active corrosion is not attained as the simulations are based on electrochemical and chemical parameters at 25 C.« less

Sol-gel preparation of lead magnesium niobate (PMN) powders and thin films

DOEpatents

Boyle, T.J.

1999-01-12

A method of preparing a lead magnesium niobium oxide (PMN), Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, precursor solution by a solvent method wherein a liquid solution of a lead-complex PMN precursor is combined with a liquid solution of a niobium-complex PMN precursor, the combined lead- and niobium-complex liquid solutions are reacted with a magnesium-alkyl solution, forming a PMN precursor solution and a lead-based precipitate, and the precipitate is separated from the reacted liquid PMN precursor solution to form a precipitate-free PMN precursor solution. This precursor solution can be processed to form both ferroelectric powders and thin films. 3 figs.

Sol-Gel Preparation Of Lead Magnesium Ni Obate (Pmn) Powdersand Thin Films

DOEpatents

Boyle, Timothy J.

1999-01-12

A method of preparing a lead magnesium niobium oxide (PMN), Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3, precursor solution by a solvent method wherein a liquid solution of a lead-complex PMN precursor is combined with a liquid solution of a niobium-complex PMN precursor, the combined lead- and niobium-complex liquid solutions are reacted with a magnesium-alkyl solution, forming a PMN precursor solution and a lead-based precipitate, and the precipitate is separated from the reacted liquid PMN precursor solution to form a precipitate-free PMN precursor solution. This precursor solution can be processed to form both ferroelectric powders and thin films.

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

Synthesis and structures of metal chalcogenide precursors

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

1990-01-01

The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

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

PubMed

Seisenbaeva, Gulaim A; Kessler, Vadim G

2014-06-21

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

Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides.

PubMed

Guo, Lijuan; Zhao, Yu; Yao, Zhiwei

2016-01-21

This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.

Large-Scale Precise Printing of Ultrathin Sol-Gel Oxide Dielectrics for Directly Patterned Solution-Processed Metal Oxide Transistor Arrays.

PubMed

Lee, Won-June; Park, Won-Tae; Park, Sungjun; Sung, Sujin; Noh, Yong-Young; Yoon, Myung-Han

2015-09-09

Ultrathin and dense metal oxide gate di-electric layers are reported by a simple printing of AlOx and HfOx sol-gel precursors. Large-area printed indium gallium zinc oxide (IGZO) thin-film transistor arrays, which exhibit mobilities >5 cm(2) V(-1) s(-1) and gate leakage current of 10(-9) A cm(-2) at a very low operation voltage of 2 V, are demonstrated by continuous simple bar-coated processes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sol-gel derived (La 0.8M 0.2)CrO 3 (M dbnd Ca, Sr) coating layer on stainless-steel substrate for use as a separator in intermediate-temperature solid oxide fuel cell

NASA Astrophysics Data System (ADS)

A Lee, E.; Lee, S.; Hwang, H. J.; Moon, J.-W.

A ceramic coating technique is applied to reduce the voltage drop caused by oxidation of the metallic separator (SUS444) in intermediate-temperature (IT) solid oxide fuel cell (SOFCs) systems. Precursor solutions for (La, Ca)CrO 3 (LCC) and (La, Sr)CrO 3 (LSC) coatings are prepared by adding nitric acid and ethylene glycol into an aqueous solution of lanthanum, strontium (or calcium) and chromium nitrates. Dried LCC and LSC gel films are heat-treated at 400-800 °C after dip-coating on the SUS444 substrate. XRD and Fourier-transform infrared (FT-IR) analysis is used to examine the crystallization behaviour and chemical structure of the precursor solution. The oxidation behaviour of the coated SUS444 substrate is compared with an uncoated SUS444 substrate. The oxidation of the SUS444 is inhibited by the LCC and LSC thin film layers.

Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells

DOE PAGES

Zhang, Wei; Pathak, Sandeep; Sakai, Nobuya; ...

2015-11-30

Solution-processed metal halide perovskite semiconductors, such as CH 3NH 3PbI 3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce themore » oxidized I2 back into I-, and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead.« less

Characterization of Ni-YSZ anodes for solid oxide fuel cells fabricated by solution precursor plasma spraying with axial feedstock injection

NASA Astrophysics Data System (ADS)

Metcalfe, Craig; Lay-Grindler, Elisa; Kesler, Olivera

2014-02-01

Nickel and yttria-stabilized zirconia (YSZ) anodes were fabricated by solution precursor plasma spraying (SPPS) and incorporated into metal-supported solid oxide fuel cells (SOFC). A power density of 0.45 W cm-2 at 0.7 V and a peak power density of 0.52 W cm-2 at 750 °C in humidified H2 was obtained, which are the first performance results reported for an SOFC having an anode fabricated by SPPS. The effects of solution composition, plasma gas composition, and stand-off distance on the composition of the deposited Ni-YSZ coatings by SPPS were evaluated. It was found that the addition of citric acid to the aqueous solution delayed re-solidification of NiO particles, improving the deposition efficiency and coating adhesion. The composition of the deposited coatings was found to vary with torch power. Increasing torch power led to coatings with decreasing Ni content, as a result of Ni vaporizing in-flight at stand-off distances less than 60 mm from the torch nozzle exit.

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

Metal sulfide thin films by chemical spray pyrolysis

NASA Astrophysics Data System (ADS)

Krunks, Malle; Mellikov, Enn

2001-04-01

CdS, ZnS and CuS thin films were prepared by spray pyrolysis method using metal chlorides and thiourea (tu) as starting materials. Metal sulfide films form as products of thermal decomposition of complexes Cd(tu)2Cl2, Zn(tu)2Cl2 and Cu(tu)Cl(DOT)1/2H2O, originally formed in aqueous solution at precursors molar ratio 1:2. The metal-ligand bonding is thermally stable up to 220 degrees Celsius, followed by multistep degradation process of complexes. The TG/DTA analysis show similar thermal behavior of complexes up to 300 degrees Celsius with the formation of metal sulfides in this decomposition step. In air intensive oxidation processes are detected close to 400, 600 and 720 degrees Celsius for Cu, Cd and Zn complexes, respectively. The results of thermoanalytical study and XRD of sprayed films show that CdS and ZnS films could be grown at 450 degrees Celsius even in air while deposition of copper sulfide films should be performed in an inert atmosphere. High total impurities content of 10 wt% in CdS films prepared at 240 degrees Celsius is originated from the precursor and reduced to 2 wt% by increasing the growth temperature up to 400 degrees Celsius.

Linking Precursor Alterations to Nanoscale Structure and Optical Transparency in Polymer Assisted Fast-Rate Dip-Coating of Vanadium Oxide Thin Films

PubMed Central

Glynn, Colm; Creedon, Donal; Geaney, Hugh; Armstrong, Eileen; Collins, Timothy; Morris, Michael A.; Dwyer, Colm O’

2015-01-01

Solution processed metal oxide thin films are important for modern optoelectronic devices ranging from thin film transistors to photovoltaics and for functional optical coatings. Solution processed techniques such as dip-coating, allow thin films to be rapidly deposited over a large range of surfaces including curved, flexible or plastic substrates without extensive processing of comparative vapour or physical deposition methods. To increase the effectiveness and versatility of dip-coated thin films, alterations to commonly used precursors can be made that facilitate controlled thin film deposition. The effects of polymer assisted deposition and changes in solvent-alkoxide dilution on the morphology, structure, optoelectronic properties and crystallinity of vanadium pentoxide thin films was studied using a dip-coating method using a substrate withdrawal speed within the fast-rate draining regime. The formation of sub-100 nm thin films could be achieved rapidly from dilute alkoxide based precursor solutions with high optical transmission in the visible, linked to the phase and film structure. The effects of the polymer addition was shown to change the crystallized vanadium pentoxide thin films from a granular surface structure to a polycrystalline structure composed of a high density of smaller in-plane grains, resulting in a uniform surface morphology with lower thickness and roughness. PMID:26123117

Chemical vapor deposition of mesoporous graphene nanoballs for supercapacitor.

PubMed

Lee, Jung-Soo; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2013-07-23

A mass-producible mesoporous graphene nanoball (MGB) was fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application. Polystyrene balls and reduced iron created under high temperature and a hydrogen gas environment provide a solid carbon source and a catalyst for graphene growth during the precursor-assisted CVD process, respectively. Carboxylic acid and sulfonic acid functionalization of the polystyrene ball facilitates homogeneous dispersion of the hydrophobic polymer template in the metal precursor solution, thus, resulting in a MGB with a uniform number of graphene layers. The MGB is shown to have a specific surface area of 508 m(2)/g and is mesoporous with a mean mesopore diameter of 4.27 nm. Mesopores are generated by the removal of agglomerated iron domains, permeating down through the soft polystyrene spheres and providing the surface for subsequent graphene growth during the heating process in a hydrogen environment. This technique requires only drop-casting of the precursor/polystyrene solution, allowing for mass-production of multilayer MGBs. The supercapacitor fabricated by the use of the MGB as an electrode demonstrates a specific capacitance of 206 F/g and more than 96% retention of capacitance after 10,000 cycles. The outstanding characteristics of the MGB as an electrode for supercapacitors verify the strong potential for use in energy-related areas.

Thin HTSC films produced by a polymer metal precursor technique

NASA Astrophysics Data System (ADS)

Lampe, L. v.; Zygalsky, F.; Hinrichsen, G.

In precursors the metal ions are combined with acid groups of polymethacrylic acid (PMAA), polyacrylic acid (PAA) or novolac. Compared to thermal degradation temperature of pure polymers those of precursors are low. Precursors films were patterned by UV lithography. Diffractometric investigations showed that the c-axis oriented epitaxial films of YBa 2Cu 3O x and Bi 2Sr 2CaCu 2O x originated from amorphous metal oxide films, which were received after thermal degradation of the precursor. Transition temperatures and current densities were determined by electric resistivity measurements.

Fused filament 3D printing of ionic polymer-metal composites for soft robotics

NASA Astrophysics Data System (ADS)

Carrico, James D.; Leang, Kam K.

2017-04-01

Additive manufacturing techniques are used to create three-dimensional structures with complex shapes and features from polymer and/or metal materials. For example, fused filament three-dimensional (3D) printing utilizes non-electroactive polymers, such as acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), to build structures and components in a layer-by-layer fashion for a wide variety of applications. Presented here is a summary of recent work on a fused filament 3D-printing technique to create 3D ionic polymer-metal composite (IPMC) structures for applications in soft robotics. The 3D printing technique overcomes some of the limitations of existing manufacturing processes for creating IPMCs, such as limited shapes and sizes and time-consuming manufacturing steps. In the process described, first a precursor material (non-acid Nafion precursor resin) is extruded into a thermoplastic filament for 3D printing. Then, a custom-designed 3D printer is described that utilizes the precursor filament to manufacture custom-shaped structures. Finally, the 3D-printed samples are functionalized by hydrolyzing them in an aqueous solution of potassium hydroxide and dimethyl sulfoxide, followed by application of platinum electrodes. Presented are example 3D-printed single and multi-degree-of-freedom IPMC actuators and characterization results, as well as example soft-robotic devices to demonstrate the potential of this process.

Fused filament 3D printing of ionic polymer-metal composites (IPMCs)

NASA Astrophysics Data System (ADS)

Carrico, James D.; Traeden, Nicklaus W.; Aureli, Matteo; Leang, Kam K.

2015-12-01

This paper describes a new three-dimensional (3D) fused filament additive manufacturing (AM) technique in which electroactive polymer filament material is used to build soft active 3D structures, layer by layer. Specifically, the unique actuation and sensing properties of ionic polymer-metal composites (IPMCs) are exploited in 3D printing to create electroactive polymer structures for application in soft robotics and bio-inspired systems. The process begins with extruding a precursor material (non-acid Nafion precursor resin) into a thermoplastic filament for 3D printing. The filament is then used by a custom-designed 3D printer to manufacture the desired soft polymer structures, layer by layer. Since at this stage the 3D-printed samples are not yet electroactive, a chemical functionalization process follows, consisting in hydrolyzing the precursor samples in an aqueous solution of potassium hydroxide and dimethyl sulfoxide. Upon functionalization, metal electrodes are applied on the samples through an electroless plating process, which enables the 3D-printed IPMC structures to be controlled by voltage signals for actuation (or to act as sensors). This innovative AM process is described in detail and the performance of 3D printed IPMC actuators is compared to an IPMC actuator fabricated from commercially available Nafion sheet material. The experimental results show comparable performance between the two types of actuators, demonstrating the potential and feasibility of creating functional 3D-printed IPMCs.

A three body problem: a genuine heterotrimetallic molecule vs. a mixture of two parent heterobimetallic molecules.

PubMed

Han, Haixiang; Wei, Zheng; Barry, Matthew C; Carozza, Jesse C; Alkan, Melisa; Rogachev, Andrey Yu; Filatov, Alexander S; Abakumov, Artem M; Dikarev, Evgeny V

2018-06-07

This work raises a fundamental question about the "real" structure of molecular compounds containing three different metals: whether they consist of genuine hetero tri metallic species or of a mixture of parent hetero bi metallic species. Heterotrimetallic complex Li 2 CoNi(tbaoac) 6 ( 1 , tbaoac = tert -butyl acetoacetate) has been designed based on the model tetranuclear structure featuring two transition metal sites in order to be utilized as a molecular precursor for the low-temperature preparation of the LiCo 0.5 Ni 0.5 O 2 battery cathode material. An investigation of the structure of 1 appeared to be very challenging, since the Co and Ni atoms have very similar atomic numbers, monoisotopic masses, and radii as well as the same oxidation state and coordination number/environment. Using a statistical analysis of heavily overlaid isotope distribution patterns of the [Li 2 MM'L 5 ] + (M/M' = Co 2 , Ni 2 , and CoNi) ions in DART mass spectra, it was concluded that the reaction product 1 contains both heterotrimetallic and bimetallic species. A structural analogue approach has been applied to obtain Li 2 MMg(tbaoac) 6 (M = Co ( 2 ) and Ni ( 3 )) complexes that contain lighter, diamagnetic magnesium in the place of one of the 3d transition metals. X-ray crystallography, mass spectrometry, and NMR spectroscopy unambiguously confirmed the presence of three types of molecules in the reaction mixture that reaches an equilibrium, Li 2 M 2 L 6 + Li 2 Mg 2 L 6 ↔ 2Li 2 MMgL 6 , upon prolonged reflux in solution. The equilibrium mixture was shown to have a nearly statistical distribution of the three molecules, and this is fully supported by the results of theoretical calculations revealing that the stabilization energies of hetero tri metallic assemblies fall exactly in between those for the parent hetero bi metallic species. The LiCo 0.5 Ni 0.5 O 2 quaternary oxide has been obtained in its phase-pure form by thermal decomposition of heterometallic precursor 1 at temperatures as low as 450 °C. Its chemical composition, structure, morphology, and transition metal distribution have been studied by X-ray and electron diffraction techniques and compositional energy-dispersive X-ray mapping with nanometer resolution. The work clearly illustrates the advantages of heterometallic single-source precursors over the corresponding multi-source precursors.

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells.

PubMed

Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

2016-11-09

We report the preparation of Cu 2 S, In 2 S 3 , CuInS 2 and Cu(In,Ga)S 2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN 1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

NASA Astrophysics Data System (ADS)

Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

2016-11-01

We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

Exploring Trends in Metal-Metal Bonding, Spectroscopic Properties, and Conformational Flexibility in a Series of Heterobimetallic Ti/M and V/M Complexes (M = Fe, Co, Ni, and Cu).

PubMed

Wu, Bing; Wilding, Matthew J T; Kuppuswamy, Subramaniam; Bezpalko, Mark W; Foxman, Bruce M; Thomas, Christine M

2016-12-05

To understand the metal-metal bonding and conformational flexibility of first-row transition metal heterobimetallic complexes, a series of heterobimetallic Ti/M and V/M complexes (M = Fe, Co, Ni, and Cu) have been investigated. The titanium tris(phosphinoamide) precursors ClTi(XylNP i Pr 2 ) 3 (1) and Ti(XylNP i Pr 2 ) 3 (2) have been used to synthesize Ti/Fe (3), Ti/Ni (4, 4 THF ), and Ti/Cu (5) heterobimetallic complexes. A series of V/M (M = Fe (7), Co (8), Ni (9), and Cu (10)) complexes have been generated starting from the vanadium tris(phosphinoamide) precursor V(XylNP i Pr 2 ) 3 (6). The new heterobimetallic complexes were characterized and studied by NMR spectroscopy, X-ray crystallography, electron paramagnetic resonance, and Mössbauer spectroscopy, where applicable, and computational methods (DFT). Compounds 3, 4 THF , 7, and 8 are C 3 -symmetric with three bridging phosphinoamide ligands, while compounds 9 and 10 adopt an asymmetric geometry with two bridging phosphinoamides and one phosphinoamide ligand bound η 2 to vanadium. Compounds 4 and 5, on the other hand, are asymmetric in the solid state but show evidence for fluxional behavior in solution. A correlation is established between conformational flexibility and metal-metal bond order, which has important implications for the future reactivity of these and other heterobimetallic molecules.

Sol-gel precursors and products thereof

DOEpatents

Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

2017-02-14

The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

Important property of polymer spheres for the preparation of three-dimensionally ordered macroporous (3DOM) metal oxides by the ethylene glycol method: the glass-transition temperature.

PubMed

Sadakane, Masahiro; Sasaki, Keisuke; Nakamura, Hiroki; Yamamoto, Takashi; Ninomiya, Wataru; Ueda, Wataru

2012-12-21

We demonstrate that the glass-transition temperature (T(g)) of a polymer sphere template is a crucial factor in the production of three-dimensionally ordered macroporous (3DOM) materials. Metal nitrate dissolved in ethylene glycol-methanol was infiltrated into the void of a face-centered, close-packed colloidal crystal of poly(methyl methacrylate) (PMMA)-based spheres. The metal nitrate reacts with EG to form a metal oxalate (or metal glycoxylate) solid (nitrate oxidation) in the void of the template when the metal nitrate-EG-PMMA composite is heated. Further heating converts metal oxalate to metal oxide and removes PMMA to form 3DOM materials. We investigated the effect of T(g) of PMMA templates and obtained clear evidence that the solidification temperature of the metal precursor solution (i.e., nitration oxidation temperature) should be lower than the T(g) of the polymer spheres to obtain a well-ordered 3DOM structure.

Facile Preparation of Highly Conductive Metal Oxides by Self-Combustion for Solution-Processed Thermoelectric Generators.

PubMed

Kang, Young Hun; Jang, Kwang-Suk; Lee, Changjin; Cho, Song Yun

2016-03-02

Highly conductive indium zinc oxide (IZO) thin films were successfully fabricated via a self-combustion reaction for application in solution-processed thermoelectric devices. Self-combustion efficiently facilitates the conversion of soluble precursors into metal oxides by lowering the required annealing temperature of oxide films, which leads to considerable enhancement of the electrical conductivity of IZO thin films. Such enhanced electrical conductivity induced by exothermic heat from a combustion reaction consequently yields high performance IZO thermoelectric films. In addition, the effect of the composition ratio of In to Zn precursors on the electrical and thermoelectric properties of the IZO thin films was investigated. IZO thin films with a composition ratio of In:Zn = 6:2 at the low annealing temperature of 350 °C showed an enhanced electrical conductivity, Seebeck coefficient, and power factor of 327 S cm(-1), 50.6 μV K(-1), and 83.8 μW m(-1) K(-2), respectively. Moreover, the IZO thin film prepared at an even lower temperature of 300 °C retained a large power factor of 78.7 μW m(-1) K(-2) with an electrical conductivity of 168 S cm(-1). Using the combustive IZO precursor, a thermoelectric generator consisting of 15 legs was fabricated by a printing process. The thermoelectric array generated a thermoelectric voltage of 4.95 mV at a low temperature difference (5 °C). We suggest that the highly conductive IZO thin films by self-combustion may be utilized for fabricating n-type flexible printed thermoelectric devices.

Gold nanocages: synthesis, properties, and applications.

PubMed

Skrabalak, Sara E; Chen, Jingyi; Sun, Yugang; Lu, Xianmao; Au, Leslie; Cobley, Claire M; Xia, Younan

2008-12-01

Noble-metal nanocages comprise a novel class of nanostructures possessing hollow interiors and porous walls. They are prepared using a remarkably simple galvanic replacement reaction between solutions containing metal precursor salts and Ag nanostructures prepared through polyol reduction. The electrochemical potential difference between the two species drives the reaction, with the reduced metal depositing on the surface of the Ag nanostructure. In our most studied example, involving HAuCl(4) as the metal precursor, the resultant Au is deposited epitaxially on the surface of the Ag nanocubes, adopting their underlying cubic form. Concurrent with this deposition, the interior Ag is oxidized and removed, together with alloying and dealloying, to produce hollow and, eventually, porous structures that we commonly refer to as Au nanocages. This approach is versatile, with a wide range of morphologies (e.g., nanorings, prism-shaped nanoboxes, nanotubes, and multiple-walled nanoshells or nanotubes) available upon changing the shape of the initial Ag template. In addition to Au-based structures, switching the metal salt precursors to Na(2)PtCl(4) and Na(2)PdCl(4) allows for the preparation of Pt- and Pd-containing hollow nanostructures, respectively. We have found that changing the amount of metal precursor added to the suspension of Ag nanocubes is a simple means of tuning both the composition and the localized surface plasmon resonance (LSPR) of the metal nanocages. Using this approach, we are developing structures for biomedical and catalytic applications. Because discrete dipole approximations predicted that the Au nanocages would have large absorption cross-sections and because their LSPR can be tuned into the near-infrared (where the attenuation of light by blood and soft tissue is greatly reduced), they are attractive materials for biomedical applications in which the selective absorption of light at great depths is desirable. For example, we have explored their use as contrast enhancement agents for both optical coherence tomography and photoacoustic tomography, with improved performance observed in each case. Because the Au nanocages have large absorption cross-sections, they are also effective photothermal transducers; thus, they might provide a therapeutic effect through selective hyperthermia-induced killing of targeted cancer cells. Our studies in vitro have illustrated the feasibility of applying this technique as a less-invasive form of cancer treatment.

Gold Nanocages: Synthesis, Properties, and Applications

PubMed Central

SKRABALAK, SARA E.; CHEN, JINGYI; SUN, YUGANG; LU, XIANMAO; AU, LESLIE; COBLEY, LAIRE M.; XIA, YOUNAN

2008-01-01

Conspectus Noble-metal nanocages represent a novel class of nanostructures with hollow interiors and porous walls. They are prepared using the remarkably simple galvanic replacement reaction between solutions containing metal precursor salts and Ag nanostructures prepared by polyol reduction. The electrochemical potential difference between the two species drives the reaction, with the reduced metal depositing on the surface of the Ag nanostructure. In our most studied example involving HAuCl4 as the metal precursor, the resultant Au epitaxially deposits on the surface of the Ag nanocubes, adopting their cubic structure. Concurrent with this deposition, the interior Ag is oxidized and removed, together with alloying and dealloying, to produce hollow and eventually porous structures that we commonly refer to as Au nanocages. This approach has proven versatile, with a wide range of morphologies – including nanorings, prism-shaped nanoboxes, nanotubes, and multiple-walled nanoshells or nanotubes – being produced by changing the shape of the initial Ag template. Besides Au-based structures, Pt- and Pd-containing hollow nanostructures have been prepared by switching the metal salt precursors to Na2PtCl4 or Na2PdCl4, respectively. Additionally, we have found it easy to tune both the composition and localized surface plasmon resonance (LSPR) of the metal nanocages by simply changing the amount of metal precursor added to the suspension of Ag nanocubes. In this way, we are developing these structures for biomedical and catalytic applications. As the Au nanocages are predicted by discrete dipole approximations (DDA) to have large absorption cross-sections and their LSPR can be tuned into the near-infrared where the attenuation of light by blood and soft tissue is greatly reduced, they are attractive for biomedical applications in which the selective absorption of light at great depths is desirable. For example, we have explored their use as contrast enhancement agents for both optical coherence tomography (OCT) and photoacoustic tomography (PAT), with improvements being observed in each case. As the Au nanocages have large absorption cross-sections, they are also effective photothermal transducers, which when targeted to cancer cells could provide a therapeutic effect by selectively killing them by hyperthermia. Our in vitro work illustrates the feasibility of this technique as a less invasive form of cancer treatment. PMID:18570442

A polymer solution technique for the synthesis of nano-sized Li 2TiO 3 ceramic breeder powders

NASA Astrophysics Data System (ADS)

Jung, Choong-Hwan; Lee, Sang Jin; Kriven, Waltraud M.; Park, Ji-Yeon; Ryu, Woo-Seog

2008-02-01

Nano-sized Li 2TiO 3 powder was fabricated by an organic-inorganic solution route. A steric entrapment route employing ethylene glycol was used for the preparation of the nano-sized Li 2TiO 3 particles. Titanium isopropoxide and lithium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. With the optimum amount of the polymer, the metal cations (Li and Ti) were dispersed in the solution and a homogeneous polymeric network was formed. The organic-inorganic precursor gels were turned to crystalline powders through an oxidation reaction during a calcination process. The dried precursor gel showed the carbon-free Li 2TiO 3 crystalline form which was observed above 400 °C. The primary particle size of the carbon-free Li 2TiO 3 was about 70 nm, and the structure of the crystallized powder was porous and agglomerated. The powder compact was densified to 92% of TD at a relatively low sintering temperature of 1100 °C for 2 h.

Cd(1-x)Zn(x)O [0.05 ≤x≤ 0.26] synthesized by vapor-diffusion induced hydrolysis and co-nucleation from aqueous metal salt solutions.

PubMed

Schwenzer, Birgit; Neilson, James R; Jeffries, Stacie M; Morse, Daniel E

2011-02-14

Nanoparticulate Cd(1-x)Zn(x)O (x = 0, 0.05-0.26, 1) is synthesized in a simple two-step synthesis approach. Vapor-diffusion induced catalytic hydrolysis of two molecular precursors at low temperature induces co-nucleation and polycondensation to produce bimetallic layered hydroxide salts (M = Cd, Zn) as precursor materials which are subsequently converted to Cd(1-x)Zn(x)O at 400 °C. Unlike ternary materials prepared by standard co-precipitation procedures, all products presented here containing < 30 mol% Zn(2+) ions are homogeneous in elemental composition on the micrometre scale. This measured compositional homogeneity within the samples, as determined by energy dispersive spectroscopy and inductively coupled plasma spectroscopy, is a testimony to the kinetic control achieved by employing slow hydrolysis conditions. In agreement with this observation, the optical properties of the materials obey Vegard's Law for a homogeneous solid solution of Cd(1-x)Zn(x)O, where x corresponds to the values determined by inductively coupled plasma analysis, even though powder X-ray diffraction shows phase separation into a cubic mixed metal oxide phase and a hexagonal ZnO phase at all doping levels.

Effect of varying Ga content in ZnO:GaN solid solution synthesized by solution combustion technique for photocatalytic applications

NASA Astrophysics Data System (ADS)

Menon, Sumithra Sivadas; Janani, R.; Baskar, K.; Gupta, Bhavana; Singh, Shubra

2017-05-01

ZnO:GaN (oxy)nitride solid solution has been established as the most efficient non-oxide photocatalyst for water splitting under visible irradiation with one step photoexcitation and also boasts a band gap tunability from 2.8 eV to 2.5 eV[1]. The solid solution of GaN in ZnO is formed by the intersubstitution of few of Zn/O ions by Ga/N ions, and this results in the introduction of new defect levels above the valence band which narrows the effective band gap enabling activity under visible region of spectra. In this work, we report the synthesis of ZnO:GaN solid solution by a solution combustion technique where metal nitrates and urea are used as precursors. The Zn/Ga ratio was varied from 16 to 1 in the precursors. The as synthesized samples were characterized as phase pure by X-ray diffraction, where the wurtzite structure was retained up to Zn/Ga ratio of 5. The Diffuse reflectance spectroscopy studies revealed that as the Ga content in the solid solution increases there is a reduction in band gap, from 2.9 eV to 2.4 eV. The reduced band gap of the samples facilitates its photocatalytic activity under visible region of the spectra as evaluated by photoelectrochemical measurements.

Gold-Decorated Supraspheres of Block Copolymer Micelles

NASA Astrophysics Data System (ADS)

Kim, M. P.; Kang, D. J.; Kannon, A. G.; Jung, D.-W.; Yi, G. R.; Kim, B. J.

2012-02-01

Gold-decorated supraspheres displaying various surface morphologies were prepared by infiltration of gold precursor into polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) supraspheres under acidic condition. The supraspheres were fabricated by emulsifying PS-b-P2VP polymer solution into surfactant solution. Selective swelling of P2VP in the suprasphere by gold precursor under acidic condition resulted in the formation of gold-decorated supraspheres with various surface structures. As evidenced by TEM and SEM images, dot pattern was formed in the case of smaller supraspheres than 800 nm; whereas fingerprint-like pattern was observed in larger supraspheres than 800 nm. Gold nanoparticles were located inside P2VP domains near the surface of prepared supraspheres as confirmed by TEM. The optical property of the supraspheres was characterized using UV-vis absorption spectroscopy and the maximum absorption peak at around 580 nm was observed, which means that gold nanoparticles densely packed into P2VP domain on the suprasphere. Our approach to prepare gold-decorated supraspheres can be extended to other metallic particles such as iron oxide or platinum nanoparticles, and those precursors can be also selectively incorporated into the P2VP domain.

Poly(cyclohexylethylene)- block-poly(ethylene oxide) block polymers for metal oxide templating

DOE PAGES

Schulze, Morgan W.; Sinturel, Christophe; Hillmyer, Marc A.

2015-09-01

A series of poly(cyclohexylethylene)- block-poly(ethylene oxide) (CEO) diblock copolymers were synthesized through tandem anionic polymerizations and heterogeneous catalytic hydrogenation. Solvent-annealed CEO diblock films were used to template dense arrays of inorganic oxide nanodots via simple spin coating of an inorganic precursor solution atop the ordered film. The substantial chemical dissimilarity of the two blocks enables (i) selective inclusion of the inorganic precursor within the PEO domain and (ii) the formation of exceptionally small feature sizes due to a relatively large interaction parameter estimated from mean-field analysis of the order–disorder transition temperatures of compositionally symmetric samples. UV/ozone treatment following incorporation producesmore » an ordered arrangement of oxide nanodots and simultaneously removes the block polymer template. However, we report the smallest particles (6 ± 1 nm) templated from a selective precursor insertion method to date using a block polymer scaffold.« less

Ice Melting to Release Reactants in Solution Syntheses.

PubMed

Wei, Hehe; Huang, Kai; Zhang, Le; Ge, Binghui; Wang, Dong; Lang, Jialiang; Ma, Jingyuan; Wang, Da; Zhang, Shuai; Li, Qunyang; Zhang, Ruoyu; Hussain, Naveed; Lei, Ming; Liu, Li-Min; Wu, Hui

2018-03-19

Aqueous solution syntheses are mostly based on mixing two solutions with different reactants. It is shown that freezing one solution and melting it in another solution provides a new interesting strategy to mix chemicals and to significantly change the reaction kinetics and thermodynamics. For example, a precursor solution containing a certain concentration of AgNO 3 was frozen and dropped into a reductive NaBH 4 solution at about 0 °C. The ultra-slow release of reactants was successfully achieved. An ice-melting process can be used to synthesize atomically dispersed metals, including cobalt, nickel, copper, rhodium, ruthenium, palladium, silver, osmium, iridium, platinum, and gold, which can be easily extended to other solution syntheses (such as precipitation, hydrolysis, and displacement reactions) and provide a generalized method to redesign the interphase reaction kinetics and ion diffusion in wet chemistry. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dense protective coatings, methods for their preparation and coated articles

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

Tulyani, Sonia; Bhatia, Tania; Smeggil, John G.

A method for depositing a protective coating on a complex shaped substrate includes the steps of: (1) dipping a complex shaped substrate into a slurry to form a base coat thereon, the slurry comprising an aqueous solution, at least one refractory metal oxide, and at least one transient fluid additive present in an amount of about 0.1 percent to 10 percent by weight of the slurry; (2) curing the dipped substrate; (3) dipping the substrate into a precursor solution to form a top barrier coat thereon; and (4) heat treating the dipped, cured substrate to form a protective coating.

Effect of Sn Content in a CuSnZn Metal Precursor on Formation of MoSe2 Film during Selenization in Se+SnSe Vapor

PubMed Central

Yao, Liyong; Ao, Jianping; Jeng, Ming-Jer; Bi, Jinlian; Gao, Shoushuai; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Chang, Liann-Be

2016-01-01

The preparation of Cu2ZnSnSe4 (CZTSe) thin films by the selenization of an electrodeposited copper–tin–zinc (CuSnZn) precursor with various Sn contents in low-pressure Se+SnSex vapor was studied. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) measurements revealed that the Sn content of the precursor that is used in selenization in a low-pressure Se+SnSex vapor atmosphere only slightly affects the elemental composition of the formed CZTSe films. However, the Sn content of the precursor significantly affects the grain size and surface morphology of CZTSe films. A metal precursor with a very Sn-poor composition produces CZTSe films with large grains and a rough surface, while a metal precursor with a very Sn-rich composition procures CZTSe films with small grains and a compact surface. X-ray diffraction (XRD) and SEM revealed that the metal precursor with a Sn-rich composition can grow a thicker MoSe2 thin film at CZTSe/Mo interface than one with a Sn-poor composition, possibly because excess Sn in the precursor may catalyze the formation of MoSe2 thin film. A CZTSe solar cell with an efficiency of 7.94%was realized by using an electrodeposited metal precursor with a Sn/Cu ratio of 0.5 in selenization in a low-pressure Se+SnSex vapor. PMID:28773366

Precursors in the preparation of transition metal nitrides and transition metal carbonitrides and their reaction intermediates

DOEpatents

Maya, Leon

1991-01-01

A process for making ammonolytic precursors to nitride and carbonitride ceramics. Extreme reaction conditions are not required and the precursor is a powder-like substance that produces ceramics of improved purity and morphology upon pyrolysis.

Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

DOEpatents

Harris, M.T.; Basaran, O.A.; Sisson, W.G.; Brunson, R.R.

1997-02-18

The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity. 3 figs.

Computational investigation of intense short-wavelength laser interaction with rare gas clusters

NASA Astrophysics Data System (ADS)

Bigaouette, Nicolas

Current Very High Temperature Reactor designs incorporate TRi-structural ISOtropic (TRISO) particle fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel by dropping a cold precursor solution into a column of hot trichloroethylene (TCE). The temperature difference drives the liquid precursor solution to precipitate the metal solution into gel spheres before reaching the bottom of a production column. Over time, gelation byproducts inhibit complete gelation and the TCE must be purified or discarded. The resulting mixed-waste stream is expensive to dispose of or recycle, and changing the forming fluid to a non-hazardous alternative could greatly improve the economics of kernel production. Selection criteria for a replacement forming fluid narrowed a list of ~10,800 chemicals to yield ten potential replacements. The physical properties of the alternatives were measured as a function of temperature between 25 °C and 80 °C. Calculated terminal velocities and heat transfer rates provided an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane were selected for further testing, and surrogate yttria-stabilized zirconia (YSZ) kernels were produced using these selected fluids. The kernels were characterized for density, geometry, composition, and crystallinity and compared to a control group of kernels produced in silicone oil. Production in 1-bromotetradecane showed positive results, producing dense (93.8 %TD) and spherical (1.03 aspect ratio) kernels, but proper gelation did not occur in the other alternative forming fluids. With many of the YSZ kernels not properly gelling within the length of the column, this project further investigated the heat transfer properties of the forming fluids and precursor solution. A sensitivity study revealed that the heat transfer properties of the precursor solution have the strongest impact on gelation time. A COMSOL heat transfer model estimated an effective thermal diffusivity range for the YSZ precursor solution as 1.13x10 -8 m2/s to 3.35x10-8 m 2/s, which is an order of magnitude smaller than the value used in previous studies. 1-bromotetradecane is recommended for further investigation with the production of uranium-based kernels.

Supported mesoporous carbon ultrafiltration membrane and process for making the same

DOEpatents

Strano, Michael; Foley, Henry C.; Agarwal, Hans

2004-04-13

A novel supported mesoporous carbon ultrafiltration membrane and process for producing the same. The membranes comprise a mesoporous carbon layer that exists both within and external to the porous support. A liquid polymer precursor composition comprising both carbonizing and noncarbonizing templating polymers is deposited on the porous metal support. The coated support is then heated in an inert-gas atmosphere to pyrolyze the polymeric precursor and form a mesoporous carbon layer on and within the support. The pore-size of the membranes is dependent on the molecular weight of the noncarbonizing templating polymer precursor. The mesoporous carbon layer is stable and can withstand high temperatures and exposure to organic chemicals. Additionally, the porous metal support provides excellent strength properties. The composite structure of the membrane provides novel structural properties and allows for increased operating pressures allowing for greater membrane flow rates. The invention also relates to the use of the novel ultrafiltration membrane to separate macromolecules from solution. An example is shown separating bovine serum albumin from water. The membrane functions by separating and by selective adsorption. Because of the membrane's porous metal support, it is well suited to industrial applications. The unique properties of the supported mesoporous carbon membrane also allow the membrane to be used in transient pressure or temperature swing separations processes. Such processes were not previously possible with existing mesoporous membranes. The present invention, however, possesses the requisite physical properties to perform such novel ultrafiltration processes.

Mild solution-processed metal-doped TiO2 compact layers for hysteresis-less and performance-enhanced perovskite solar cells

NASA Astrophysics Data System (ADS)

Liang, Chao; Li, Pengwei; Zhang, Yiqiang; Gu, Hao; Cai, Qingbin; Liu, Xiaotao; Wang, Jiefei; Wen, Hua; Shao, Guosheng

2017-12-01

TiO2 is extensively used as electron-transporting material on perovskite solar cells (PSCs). However, traditional TiO2 processing method needs high annealing temperature (>450 °C) and pure TiO2 suffers from low electrical mobility and poor conductivity. In this study, a general one-pot solution-processed method is devised to grow uniform crystallized metal-doped TiO2 thin film as large as 15 × 15 cm2. The doping process can be controlled effectively via a series of doping precursors from niobium (V), tin (IV), tantalum (V) to tungsten (VI) chloride. As far as we know, this is so far the lowest processing temperature for metal-doped TiO2 compact layers, as low as 70 °C. The overall performance of PSCs employing the metal-doped TiO2 layers is significantly improved in term of hysteresis effect, short circuit current, open-circuit voltage, fill factor, power conversion efficiency, and device stability. With the insertion of metal ions into TiO2 lattice, the corresponding CH3NH3PbI3 PSC leads to a ∼25% improved PCE of over 16% under irradiance of 100 mW cm-2 AM1.5G sunlight, compared with control device. The results indicate that this mild solution-processed metal-doped TiO2 is an effective industry-scale way for fabricating hysteresis-less and high-performance PSCs.

Synthesis of nanoparticles using ethanol

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

Wang, Jia Xu

The present disclosure relates to methods for producing nanoparticles. The nanoparticles may be made using ethanol as the solvent and the reductant to fabricate noble-metal nanoparticles with a narrow particle size distributions, and to coat a thin metal shell on other metal cores. With or without carbon supports, particle size is controlled by fine-tuning the reduction power of ethanol, by adjusting the temperature, and by adding an alkaline solution during syntheses. The thickness of the added or coated metal shell can be varied easily from sub-monolayer to multiple layers in a seed-mediated growth process. The entire synthesis of designed core-shellmore » catalysts can be completed using metal salts as the precursors with more than 98% yield; and, substantially no cleaning processes are necessary apart from simple rinsing. Accordingly, this method is considered to be a "green" chemistry method.« less

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.

A general soft-enveloping strategy in the templating synthesis of mesoporous metal nanostructures.

PubMed

Fang, Jixiang; Zhang, Lingling; Li, Jiang; Lu, Lu; Ma, Chuansheng; Cheng, Shaodong; Li, Zhiyuan; Xiong, Qihua; You, Hongjun

2018-02-06

Metal species have a relatively high mobility inside mesoporous silica; thus, it is difficult to introduce the metal precursors into silica mesopores and suppress the migration of metal species during a reduction process. Therefore, until now, the controlled growth of metal nanocrystals in a confined space, i.e., mesoporous channels, has been very challenging. Here, by using a soft-enveloping reaction at the interfaces of the solid, liquid, and solution phases, we successfully control the growth of metallic nanocrystals inside a mesoporous silica template. Diverse monodispersed nanostructures with well-defined sizes and shapes, including Ag nanowires, 3D mesoporous Au, AuAg alloys, Pt networks, and Au nanoparticle superlattices are successfully obtained. The 3D mesoporous AuAg networks exhibit enhanced catalytic activities in an electrochemical methanol oxidation reaction. The current soft-enveloping synthetic strategy offers a robust approach to synthesize diverse mesoporous metal nanostructures that can be utilized in catalysis, optics, and biomedicine applications.

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

Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide.

PubMed

Jin, Cheng; Liu, Huimin; Kong, Xianggui; Yan, Hong; Lei, Xiaodong

2018-02-27

Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by an anion exchange method with the precursor NO 3 - containing MgAl-LDH. The final as-synthesized product [Mg 0.69 Al 0.31 (OH) 2 ] (phytateNa 6 ) 0.05 (NO 3 ) 0.01 ·mH 2 O (phytate-LDH) has highly selective adsorption ability for some metal ions and can be used to enrich rare earth metal ions in mixed solution, such as Pr 3+ and Ce 3+ from a mixed solution of them with Pb 2+ and Co 2+ . At first, phytate-LDH has good adsorption performance for these ions in single metal ion solutions. At low concentration (below 10 mg L -1 ), all the capture rates of the four metal ions were more than 97%, for highly toxic Pb 2+ it was even up to nearly 100%, and a high capture rate (99.87%) was maintained for Pb 2+ at a high concentration (100 mg L -1 ). When all the four metal ions are co-existing in aqueous solution, the selectivity order is Pb 2+ ≫ Pr 3+ ≈ Ce 3+ > Co 2+ . In a solution containing mixtures of the three metal ions of Pr 3+ , Ce 3+ , and Co 2+ , the selectivity order is Pr 3+ ≈ Ce 3+ ≫ Co 2+ , and in a solution containing mixtures of Pr 3+ with Co 2+ and Ce 3+ with Co 2+ , the selectivity orders are Pr 3+ ≫ Co 2+ and Ce 3+ ≫ Co 2+ , respectively. The high selectivity and adsorption capacities for Pb 2+ , Co 2+ , Pr 3+ , and Ce 3+ result in the efficient removal of Pb 2+ and enrichment of the rare earth metal ions Pr 3+ and Ce 3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of the adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With molecular simulation, we believe that the adsorption selectivity is due to the difference of the binding energy between the metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of the rare earth metal ions and removal of toxic metal ions from waste water.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, R.

1998-08-04

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, Raghunath

1998-01-01

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

Combustion Synthesis Technology Applied to In-situ Resource Utilization

DTIC Science & Technology

2006-06-15

or bond energies. When both the precursor salts and the fuel are water soluble, a good homogenization can be achieved in the solution. In the...metallic compounds, e.g. Ni-Al. Steel processing additives, e.g. ferro-nitrides. Electrodes for electrolysis of corrosive media, e.g. TiN, TiB2...reactants; 4. Spreading of a molten phase; 5. Gasification of volatile impurities and reactants; 6. Chemical reaction with initial product formation; 7

Metal inks

DOEpatents

Ginley, David S; Curtis, Calvin J; Miedaner, Alex; van Hest, Marinus Franciscus Antonius Maria; Kaydanova, Tatiana

2014-02-04

Self-reducing metal inks and systems and methods for producing and using the same are disclosed. In an exemplary embodiment, a method may comprise selecting metal-organic (MO) precursor, selecting a reducing agent, and dissolving the MO precursor and the reducing agent in an organic solvent to produce a metal ink that remains in a liquid phase at room temperature. Metal inks, including self-reducing and fire-through metal inks, are also disclosed, as are various applications of the metal inks.

Carbon quantum dots and a method of making the same

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

Zidan, Ragaiy; Teprovich, Joseph A.; Washington, Aaron L.

The present invention is directed to a method of preparing a carbon quantum dot. The carbon quantum dot can be prepared from a carbon precursor, such as a fullerene, and a complex metal hydride. The present invention also discloses a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride and a polymer containing a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride.

Low temperature photochemical vapor deposition of alloy and mixed metal oxide films

DOEpatents

Liu, David K.

1992-01-01

Method and apparatus for formation of an alloy thin film, or a mixed metal oxide thin film, on a substrate at relatively low temperatures. Precursor vapor(s) containing the desired thin film constituents is positioned adjacent to the substrate and irradiated by light having wavelengths in a selected wavelength range, to dissociate the gas(es) and provide atoms or molecules containing only the desired constituents. These gases then deposit at relatively low temperatures as a thin film on the substrate. The precursor vapor(s) is formed by vaporization of one or more precursor materials, where the vaporization temperature(s) is selected to control the ratio of concentration of metals present in the precursor vapor(s) and/or the total precursor vapor pressure.

Aerosol reduction/expansion synthesis (A-RES) for zero valent metal particles

DOEpatents

Leseman, Zayd; Luhrs, Claudia; Phillips, Jonathan; Soliman, Haytham

2016-04-12

Various embodiments provide methods of forming zero valent metal particles using an aerosol-reductive/expansion synthesis (A-RES) process. In one embodiment, an aerosol stream including metal precursor compound(s) and chemical agent(s) that produces reducing gases upon thermal decomposition can be introduced into a heated inert atmosphere of a RES reactor to form zero valent metal particles corresponding to metals used for the metal precursor compound(s).

Tailoring the synthesis of supported Pd catalysts towards desired structure and size of metal particles.

PubMed

Suresh, Gatla; Radnik, Jörg; Kalevaru, Venkata Narayana; Pohl, Marga-Martina; Schneider, Matthias; Lücke, Bernhard; Martin, Andreas; Madaan, Neetika; Brückner, Angelika

2010-05-14

In a systematic study, the influence of different preparation parameters on phase composition and size of metal crystallites and particles in Pd-Cu/TiO(2) and Pd-Sb/TiO(2) catalyst materials has been explored. Temperature and atmosphere of thermal pretreatment (pure He or 10% H(2)/He), nature of metal precursors (chlorides, nitrates or acetates) as well as of ammonium additives (ammonium sulfate, nitrate, carbonate) and urea were varied with the aim of tailoring the synthesis procedure for the preferential formation of metal particles with similar size and structure as observed recently in active catalysts after long-term equilibration under catalytic reaction conditions in acetoxylation of toluene to benzylacetate. Among the metal precursors and additives, the chloride metal precursors and (NH(4))(2)SO(4) were most suitable. Upon thermal pretreatment of Pd-Sb or Pd-Cu precursors, chloroamine complexes of Pd and Cu are formed, which decompose above 220 degrees C to metallic phases independent of the atmosphere. In He, metallic Pd particles were formed with both the co-components. In H(2)/He flow, Pd-Cu precursors were converted to core-shell particles with a Cu shell and a Pd core, while Sb(1)Pd(1) and Sb(7)Pd(20) alloy phases were formed in the presence of Sb. Metal crystallites of about 40 nm agglomerate to particles of up to 150 nm in He and to even larger size in H(2)/He.

On 1064 nm and 350 nm laser damage thresholds of high index oxide films deposited from organic solutions and sols

NASA Astrophysics Data System (ADS)

Thomas, I.; Wilder, J.; Gonzales, R.; George, D.

1987-06-01

High index oxide coatings TiO2, Ta2O5, ZrO2 and HfO2 have been prepared from organic solutions of metal organic precursors or from colloidal oxide suspensions. Room temperature processing gives porous coatings of comparatively low index (1.8 to 1.9). Heat treatments can, in some cases, increase the index. Laser damage threshold levels at 1064 nm with a single 1 ns pulse are in the range 6 to 10 J/sq cm. Lower figures are obtained at 350 nm with a 25 ns pulse under multishot (25 Hz) conditions.

Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

NASA Astrophysics Data System (ADS)

Forsthoefel, Kersten M.

Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a molecular precursor and porous alumina templating routes paired with solution-based methodologies are shown to generate non-oxide ceramic nanotubules of boron carbide, boron nitride and silicon carbide compositions. In the final phase of this work, a new metal-catalyzed route to poly(1-alkenyl- o-carborane) homopolymers and related copolymers was developed. Both homopolymers of 1-alkenyl-o-carboranes (1-vinyl-, 1-butenyl-, 1-hexenyl-) and copolymers of 1-hexenyl-o-carborane and allyltrimethylsilane or 1-hexenyl-o-carborane and 6-hexenyldecaborane were synthesized via the Cp2ZrMe2/B(C6F5) 3 catalyst system. A copolymer containing 1-hexenyl-o-carborane and the cross-linking agent, 6-hexenyldecaborane, was synthetically designed which exhibits initial cross-linking at ˜250°C and then converts in 75% yields to boron carbide at 1250°C.

Low temperature photochemical vapor deposition of alloy and mixed metal oxide films

DOEpatents

Liu, D.K.

1992-12-15

Method and apparatus are described for formation of an alloy thin film, or a mixed metal oxide thin film, on a substrate at relatively low temperatures. Precursor vapor(s) containing the desired thin film constituents is positioned adjacent to the substrate and irradiated by light having wavelengths in a selected wavelength range, to dissociate the gas(es) and provide atoms or molecules containing only the desired constituents. These gases then deposit at relatively low temperatures as a thin film on the substrate. The precursor vapor(s) is formed by vaporization of one or more precursor materials, where the vaporization temperature(s) is selected to control the ratio of concentration of metals present in the precursor vapor(s) and/or the total precursor vapor pressure. 7 figs.

Comparative study of the synthesis of layered transition metal molybdates

NASA Astrophysics Data System (ADS)

Mitchell, S.; Gómez-Avilés, A.; Gardner, C.; Jones, W.

2010-01-01

Mixed metal oxides (MMOs) prepared by the mild thermal decomposition of layered double hydroxides (LDHs) differ in their reactivity on exposure to aqueous molybdate containing solutions. In this study, we investigate the reactivity of some T-Al containing MMOs ( T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates (LTMs) possessing the general formula AT2(OH)(MoO 4) 2·H 2O, where A=NH 4+, Na + or K +. The phase selectivity of the reaction was studied with respect to the source of molybdate, the ratio of T to Mo and the reaction pH. LTMs were obtained on reaction of Cu-Al and Zn-Al containing MMOs with aqueous solutions of ammonium heptamolybdate. Rehydration of these oxides in the presence of sodium or potassium molybdate yielded a rehydrated LDH phase as the only crystalline product. The LTM products obtained by the rehydration of MMO precursors were compared with LTMs prepared by direct precipitation from the metal salts in order to study the influence of preparative route on their chemical and physical properties. Differences were noted in the composition, morphology and thermal properties of the resulting products.

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.

Accumulation of fossil fuels and metallic minerals in active and ancient rift lakes

USGS Publications Warehouse

Robbins, E.I.

1983-01-01

A study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes. The deposition of the precursors of petroleum, gas, oil shale, coal, phosphate, barite, Cu-Pb-Zn sulfides, and uranium begins with erosion of uplifted areas, and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes. Hot springs and volcanism add other nutrients and solutes. The resulting high biological productivity creates oxidized/reduced interfaces, and anoxic and H2S-rich bottom waters which preserves metal-bearing organic tissues and horizons. In the depositional phases, the fine-grained lake deposits are in contact with coarse-grained beach, delta, river, talus, and alluvial fan deposits. Earthquake-induced turbidites also are common coarse-grained deposits of rift lakes. Postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds. Postdepositional faulting brings organic- and metal-rich sourcebeds in contact with coarse-grained host and reservoir rocks. A suite of potentially economic deposits is therefore a characteristic of rift valleys. ?? 1983.

Accumulation of fossil fuels and metallic minerals in active and ancient rift lakes

NASA Astrophysics Data System (ADS)

Robbins, Eleanora Iberall

1983-05-01

A study of active and ancient rift systems around the world suggests that accumulations of fossil fuels and metallic minerals are related to the interactions of processes that form rift valleys with those that take place in and around rift lakes. The deposition of the precursors of petroleum, gas, oil shale, coal, phosphate, barite, Cu-Pb-Zn sulfides, and uranium begins with erosion of uplifted areas, and the consequent input of abundant nutrients and solute loads into swamps and tectonic lakes. Hot springs and volcanism add other nutrients and solutes. The resulting high biological productivity creates oxidized/reduced interfaces, and anoxic and H 2S-rich bottom waters which preserves metal-bearing organic tissues and horizons. In the depositional phases, the fine-grained lake deposits are in contact with coarse-grained beach, delta, river, talus, and alluvial fan deposits. Earthquake-induced turbidites also are common coarse-grained deposits of rift lakes. Postdepositional processes in rifts include high heat flow and a resulting concentration of the organic and metallic components that were dispersed throughout the lakebeds. Postdepositional faulting brings organic- and metal-rich sourcebeds in contact with coarse-grained host and reservoir rocks. A suite of potentially economic deposits is therefore a characteristic of rift valleys.

Structure for HTS composite conductors and the manufacture of same

DOEpatents

Cotton, J.D.; Riley, G.N. Jr.

1999-06-01

A superconducting oxide composite structure including a superconducting oxide member, a metal layer surrounding the superconducting oxide member, and an insulating layer of a complex oxide formed in situ adjacent to the superconducting oxide member and the metal layer is provided together with a method of forming such a superconducting oxide composite structure including encapsulating a superconducting oxide member or precursor within a metal matrix layer from the group of: (1) a reactive metal sheath adjacent to the superconducting oxide member or precursor, the reactive metal sheath surrounded by a second metal layer or (2) an alloy containing a reactive metal; to form an intermediate product, and, heating the intermediate product at temperatures and for time sufficient to form an insulating layer of a complex oxide in situ, the insulating layer to the superconducting oxide member or precursor and the metal matrix layer. 10 figs.

Structure for hts composite conductors and the manufacture of same

DOEpatents

Cotton, James D.; Riley, Jr., Gilbert Neal

1999-01-01

A superconducting oxide composite structure including a superconducting oxide member, a metal layer surrounding the superconducting oxide member, and an insulating layer of a complex oxide formed in situ adjacent to the superconducting oxide member and the metal layer is provided together with a method of forming such a superconducting oxide composite structure including encapsulating a superconducting oxide member or precursor within a metal matrix layer from the group of: (i) a reactive metal sheath adjacent to the superconducting oxide member or precursor, the reactive metal sheath surrounded by a second metal layer or (ii) an alloy containing a reactive metal; to form an intermediate product, and, heating the intermediate product at temperatures and for time sufficient to form an insulating layer of a complex oxide in situ, the insulating layer to the superconducting oxide member or precursor and the metal matrix layer.

Thermal shock resistance ceramic insulator

DOEpatents

Morgan, Chester S.; Johnson, William R.

1980-01-01

Thermal shock resistant cermet insulators containing 0.1-20 volume % metal present as a dispersed phase. The insulators are prepared by a process comprising the steps of (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, said metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide a cermet insulator having 0.1-20 volume % metal present as a dispersed phase.

Process for producing ceramic nitrides and carbonitrides and their precursors

DOEpatents

Brown, Gilbert M.; Maya, Leon

1988-01-01

A process for preparing ceramic nitrides and carbonitrides in the form of very pure, fine particulate powder. Appropriate precursor is prepared by reacting a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

Process for producing ceramic nitrides anc carbonitrides and their precursors

DOEpatents

Brown, G.M.; Maya, L.

1987-02-25

A process for preparing ceramic nitrides and carbon nitrides in the form of very pure, fine particulate powder. Appropriate precursors is prepared by reaching a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

Evolution of Iodoplumbate Complexes in Methylammonium Lead Iodide Perovskite Precursor Solutions

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

Sharenko, Alexander; Mackeen, Cameron; Jewell, Leila

Here in this study we investigate the local structure present in single-step precursor solutions of methylammonium lead iodide (MAPbI 3) perovskite as a function of organic and inorganic precursor ratio, as well as with hydriodic acid (HI), using X-ray absorption spectroscopy. An excess of organic precursor as well as the use of HI as a processing additive has been shown to lead to the formation of smooth, continuous, pinhole free MAPbI 3 films, whereas films produced from precursor solutions containing molar equivalents of methylammonium iodide (MAI) and PbI 2 lead to the formation of a discontinuous, needlelike morphology. We nowmore » show that as the amount of excess MAI in the precursor solution is increased, the iodide coordination of iodoplumbate complexes present in solution increases. The use of HI results in a similar increase in iodide coordination. We therefore offer insight into how solution chemistry can be used to control MAPbI 3 thin film morphology by revealing a strong correlation between the lead coordination chemistry in precursor solutions and the surface coverage and morphology of the resulting MAPbI 3 film.« less

Evolution of Iodoplumbate Complexes in Methylammonium Lead Iodide Perovskite Precursor Solutions

DOE PAGES

Sharenko, Alexander; Mackeen, Cameron; Jewell, Leila; ...

2017-02-02

Here in this study we investigate the local structure present in single-step precursor solutions of methylammonium lead iodide (MAPbI 3) perovskite as a function of organic and inorganic precursor ratio, as well as with hydriodic acid (HI), using X-ray absorption spectroscopy. An excess of organic precursor as well as the use of HI as a processing additive has been shown to lead to the formation of smooth, continuous, pinhole free MAPbI 3 films, whereas films produced from precursor solutions containing molar equivalents of methylammonium iodide (MAI) and PbI 2 lead to the formation of a discontinuous, needlelike morphology. We nowmore » show that as the amount of excess MAI in the precursor solution is increased, the iodide coordination of iodoplumbate complexes present in solution increases. The use of HI results in a similar increase in iodide coordination. We therefore offer insight into how solution chemistry can be used to control MAPbI 3 thin film morphology by revealing a strong correlation between the lead coordination chemistry in precursor solutions and the surface coverage and morphology of the resulting MAPbI 3 film.« less

In situ growth of metal particles on 3D urchin-like WO3 nanostructures.

PubMed

Xi, Guangcheng; Ye, Jinhua; Ma, Qiang; Su, Ning; Bai, Hua; Wang, Chao

2012-04-18

Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO(3) through an in situ redox reaction between weakly reductive WO(2.72) and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites. © 2012 American Chemical Society

Synthesis of ligand-stabilized metal oxide nanocrystals and epitaxial core/shell nanocrystals via a lower-temperature esterification process.

PubMed

Ito, Daisuke; Yokoyama, Shun; Zaikova, Tatiana; Masuko, Keiichiro; Hutchison, James E

2014-01-28

The properties of metal oxide nanocrystals can be tuned by incorporating mixtures of matrix metal elements, adding metal ion dopants, or constructing core/shell structures. However, high-temperature conditions required to synthesize these nanocrystals make it difficult to achieve the desired compositions, doping levels, and structural control. We present a lower temperature synthesis of ligand-stabilized metal oxide nanocrystals that produces crystalline, monodisperse nanocrystals at temperatures well below the thermal decomposition point of the precursors. Slow injection (0.2 mL/min) of an oleic acid solution of the metal oleate complex into an oleyl alcohol solvent at 230 °C results in a rapid esterification reaction and the production of metal oxide nanocrystals. The approach produces high yields of crystalline, monodisperse metal oxide nanoparticles containing manganese, iron, cobalt, zinc, and indium within 20 min. Synthesis of tin-doped indium oxide (ITO) can be accomplished with good control of the tin doping levels. Finally, the method makes it possible to perform epitaxial growth of shells onto nanocrystal cores to produce core/shell nanocrystals.

Sol-Gel Precursors for Ceramics from Minerals Simulating Soils from the Moon and Mars

NASA Technical Reports Server (NTRS)

Sibille, Laurent; Gavira-Gallardo, Jose-Antonio; Hourlier-Bahloul, Djamila

2003-01-01

Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report some preliminary results on the production of sol-gel precursors for ceramic products using mineral resources available in Martian or Lunar soil. The presence of SiO2, TiO2, and A12O3 in both Martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and Lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from Lunar and Martian simulant soils. Clear sol-gel precursors have been obtained by dissolution of silica from Lunar simulant soil in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy were used to characterize the elemental composition and structure of the precursor molecules. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors. In the second set of experiments, we used the same starting materials to synthesize silicate esters in acidified alcohol mixtures. Preliminary results indicate the presence of silicon alkoxides in the product of distillation.

Towards deriving Ni-rich cathode and oxide-based anode materials from hydroxides by sharing a facile co-precipitation method.

PubMed

Qiu, Haifa; Du, Tengfei; Wu, Junfeng; Wang, Yonglong; Liu, Jian; Ye, Shihai; Liu, Sheng

2018-05-22

Although intensive studies have been conducted on layered transition metal oxide(TMO)-based cathode materials and metal oxide-based anode materials for Li-ion batteries, their precursors generally follow different or even complex synthesis routes. To share one route for preparing precursors of the cathode and anode materials, herein, we demonstrate a facile co-precipitation method to fabricate Ni-rich hydroxide precursors of Ni0.8Co0.1Mn0.1(OH)2. Ni-rich layered oxide of LiNi0.8Co0.1Mn0.1O2 is obtained by lithiation of the precursor in air. An NiO-based anode material is prepared by calcining the precursor or multi-walled carbon nanotubes (MWCNTs) incorporated precursors. The pre-addition of ammonia solution can simplify the co-precipitation procedures and the use of an air atmosphere can also make the heat treatment facile. LiNi0.8Co0.1Mn0.1O2 as the cathode material delivers a reversible capacity of 194 mA h g-1 at 40 mA g-1 and a notable cycling retention of 88.8% after 100 cycles at 200 mA g-1. This noticeable performance of the cathode arises from a decent particle morphology and high crystallinity of the layered oxides. As the anode material, the MWCNTs-incorporated oxides deliver a much higher reversible capacity of 811.1 mA h g-1 after 200 cycles compared to the pristine oxides without MWCNTs. The improvement on electrochemical performance can be attributed to synergistic effects from MWCNTs incorporation, including reinforced electronic conductivity, rich meso-pores and an alleviated volume effect. This facile and sharing method may offer an integrated and economical approach for commercial production of Ni-rich electrode materials for Li-ion batteries.

Burst nucleation by hot injection for size controlled synthesis of ε-cobalt nanoparticles.

PubMed

Zacharaki, Eirini; Kalyva, Maria; Fjellvåg, Helmer; Sjåstad, Anja Olafsen

2016-01-01

Reproducible growth of narrow size distributed ε-Co nanoparticles with a specific size requires full understanding and identification of the role of essential synthesis parameters for the applied synthesis method. For the hot injection methodology, a significant discrepancy with respect to obtained sizes and applied reaction conditions is reported. Currently, a systematic investigation controlling key synthesis parameters as injection-temperature and time, metal to surfactant ratio and reaction holding time in terms of their impact on mean ([Formula: see text]mean) and median ([Formula: see text]median) particle diameter using dichlorobenzene (DCB), Co2(CO)8 and oleic acid (OA) as the reactant matrix is lacking. A series of solution-based ε-Co nanoparticles were synthesized using the hot injection method. Suspensions and obtained particles were analyzed by DLS, ICP-OES, (synchrotron)XRD and TEM. Rietveld refinements were used for structural analysis. Mean ([Formula: see text]mean) and median ([Formula: see text]median) particle diameters were calculated with basis in measurements of 250-500 particles for each synthesis. 95 % bias corrected confidence intervals using bootstrapping were calculated for syntheses with three or four replicas. ε-Co NPs in the size range ~4-10 nm with a narrow size distribution are obtained via the hot injection method, using OA as the sole surfactant. Typically the synthesis yield is ~75 %, and the particles form stable colloidal solutions when redispersed in hexane. Reproducibility of the adopted synthesis procedure on replicate syntheses was confirmed. We describe in detail the effects of essential synthesis parameters, such as injection-temperature and time, metal to surfactant ratio and reaction holding time in terms of their impact on mean ([Formula: see text]mean) and median ([Formula: see text]median) particle diameter. The described synthesis procedure towards ε-Co nanoparticles (NPs) is concluded to be robust when controlling key synthesis parameters, giving targeted particle diameters with a narrow size distribution. We have identified two major synthesis parameters which control particle size, i.e., the metal to surfactant molar ratio and the injection temperature of the hot OA-DCB solution into which the cobalt precursor is injected. By increasing the metal to surfactant molar ratio, the mean particle diameter of the ε-Co NPs has been found to increase. Furthermore, an increase in the injection temperature of the hot OA-DCB solution into which the cobalt precursor is injected, results in a decrease in the mean particle diameter of the ε-Co NPs, when the metal to surfactant molar ratio [Formula: see text] is fixed at ~12.9.

Preparation and Characterization of Nano Gold Supported over Montmorillonite Clays

NASA Astrophysics Data System (ADS)

Suraja, P. V.; Binitha, N. N.; Yaakob, Z.; Silija, P. P.

2011-02-01

The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl4·3H2O by deposition-precipitation (DP) methods. However, it is difficult to prepare nanoscale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. There is no need of increasing the pH of the solution to reduce the Au3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-VIS Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method.

The Chemistry of Inorganic Precursors during the Chemical Deposition of Films on Solid Surfaces.

PubMed

Barry, Seán T; Teplyakov, Andrew V; Zaera, Francisco

2018-03-20

The deposition of thin solid films is central to many industrial applications, and chemical vapor deposition (CVD) methods are particularly useful for this task. For one, the isotropic nature of the adsorption of chemical species affords even coverages on surfaces with rough topographies, an increasingly common requirement in microelectronics. Furthermore, by splitting the overall film-depositing reactions into two or more complementary and self-limiting steps, as it is done in atomic layer depositions (ALD), film thicknesses can be controlled down to the sub-monolayer level. Thanks to the availability of a vast array of inorganic and metalorganic precursors, CVD and ALD are quite versatile and can be engineered to deposit virtually any type of solid material. On the negative side, the surface chemistry that takes place in these processes is often complex, and can include undesirable side reactions leading to the incorporation of impurities in the growing films. Appropriate precursors and deposition conditions need to be chosen to minimize these problems, and that requires a proper understanding of the underlying surface chemistry. The precursors for CVD and ALD are often designed and chosen based on their known thermal chemistry from inorganic chemistry studies, taking advantage of the vast knowledge developed in that field over the years. Although a good first approximation, however, this approach can lead to wrong choices, because the reactions of these precursors at gas-solid interfaces can be quite different from what is seen in solution. For one, solvents often aid in the displacement of ligands in metalorganic compounds, providing the right dielectric environment, temporarily coordinating to the metal, or facilitating multiple ligand-complex interactions to increase reaction probabilities; these options are not available in the gas-solid reactions associated with CVD and ALD. Moreover, solid surfaces act as unique "ligands", if these reactions are to be viewed from the point of view of the metalorganic complexes used as precursors: they are bulky and rigid, can provide multiple binding sites for a single reaction, and can promote unique bonding modes, especially on metals, which have delocalized electronic structures. The differences between the molecular and surface chemistry of CVD and ALD precursors can result in significant variations in their reactivity, ultimately leading to unpredictable properties in the newly grown films. In this Account, we discuss some of the main similarities and differences in chemistry that CVD/ALD precursors follow on surfaces when contrasted against their known behavior in solution, with emphasis on our own work but also referencing other key contributions. Our approach is unique in that it combines expertise from the inorganic, surface science, and quantum-mechanics fields to better understand the mechanistic details of the chemistry of CVD and ALD processes and to identify new criteria to consider when designing CVD/ALD precursors.

Process for making silver metal filaments

DOEpatents

Bamberger, Carlos E.

1997-01-01

A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

Water-gas shift reaction on alumina-supported Pt-CeO x catalysts prepared by supercritical fluid deposition

DOE PAGES

Deal, Jacob W.; Le, Phong; Corey, C. Blake; ...

2016-08-25

Alumina-supported platinum catalysts, both with and without ceria, were prepared by supercritical fluid deposition and evaluated for activity for water-gas shift reaction. The organometallic precursor, platinum(II) acetylacetonate, was deposited from solution in supercritical carbon dioxide. Analysis of the catalysts by high resolution scanning transmission electron microscopy indicated that platinum was present in the form of highly dispersed metal nanoparticles. Pretreatment of the alumina-supported ceria in hydrogen prior to the deposition of the platinum precursor resulted in more platinum nucleated on ceria than non-pretreated alumina-supported ceria but varied in both particle size and structure. The ceria-containing catalyst that was not pretreatedmore » exhibited a more uniform particle size, and the Pt particles were encapsulated in crystalline ceria. Reaction rate measurements showed that the catalyst was more active for water-gas shift, with reaction rates per mass of platinum that exceeded most literature values for water-gas shift reaction on Pt-CeO x catalysts. The high activity was attributed to the significant fraction of platinum/ceria interfacial contact. We found that these results show the promise of supercritical fluid deposition as a scalable means of synthesizing highly active supported metal catalysts that offer efficient utilization of precious metals.« less

Stepwise assembly of metal-organic framework based on a metal-organic polyhedron precursor for drug delivery.

PubMed

Wang, Hai-Ning; Meng, Xing; Yang, Guang-Sheng; Wang, Xin-Long; Shao, Kui-Zhan; Su, Zhong-Min; Wang, Chun-Gang

2011-07-07

A 12-connected network with fcu topology was firstly reported focusing on using predesigned metal-organic polyhedron (MOP) as the precursor, and its adsorption and delivery of the drug 5-fluorouracil (5-FU) was also determined. This journal is © The Royal Society of Chemistry 2011

Autogenic reaction synthesis of photocatalysts for solar fuel generation

DOEpatents

Ingram, Brian J.; Pol, Vilas G.; Cronauer, Donald C.; Ramanathan, Muruganathan

2016-04-19

In one preferred embodiment, a photocatalyst for conversion of carbon dioxide and water to a hydrocarbon and oxygen comprises at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 600.degree. C. to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating. The precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion, and the metal of the salt is selected from the group consisting of Mn, Ti, Sn, V, Fe, Zn, Zr, Mo, Nb, W, Eu, La, Ce, In, and Si.

Bulk nucleation and growth of inorganic nanowires and nanotubes

NASA Astrophysics Data System (ADS)

Sharma, Shashank

The nanometer scale materials such as nanowires and nanotubes will be of particular interest as building blocks for designing novel sensors, catalysts, electronic, optical, and optoelectronic devices. However, in order to realize these applications, bulk amounts of nanowires and nanotubes need to be synthesized with precise control over the nanostructure characteristics. In addition, the structure-property relationships for one-dimensional structures are expected to be different than their bulk when their diameters are less than a characteristic Bohr exciton radius. This fundamental curiosity also necessitates bulk synthesis of nanostructures. The current bulk nanowire synthesis methods utilize either nanometer scale porous molds or nanometer scale transition metal clusters to template one-dimensional growth. All these techniques have inherent limitations in terms of control over the nanowire diameter distribution, composition, the growth direction, and the ability to generate abrupt interfaces within individual nanowires. In this dissertation, a new concept for bulk nucleation and growth of one-dimensional nanostructures is proposed and demonstrated for a variety of inorganic material systems. In this technique, multiple nanowires nucleate and grow from pools of low-melting metal melts when exposed to an activated gas phase containing the necessary precursors. This concept, hereby termed Low Melting Metals and Activated Gas phase (LMAG) mediated method, is specifically demonstrated for the synthesis of, (a) silicon nanowires grown using molten gallium and silane precursors; (b) silicon compound nanowires using solution of molten gallium and appropriate gas phase precursors, and (c) metal-oxide nanostructures grown using direct reaction of the respective metal melts and oxygen precursors. Nanowires resulted from the same molten gallium pool at high densities (>1011/cm2) and with narrow diameter distribution. The silicon nanowires synthesized using the LMAG technique were single crystalline, defect free, and contained a non uniform, extremely thin oxide sheath (<1.5 nm). The nanowire diameter could be varied from 3 to 100 nm, with lengths up to hundreds of microns. Unique tubular and paintbrush-like morphologies were obtained in gallium oxide (Ga2O3) nanostructures. Small gallium droplets (<100 nm size) allowed Ga2O3 nanowire growth parallel to the substrate, followed by 2-dimensional nanoweb formation. These experiments using small gallium droplets resulted in the growth of crystalline Ga2O3 nanotubes with outer diameters as small as 5 nm and inner diameters as small as 2.5 nm.

Functional nanometer-scale structures

NASA Astrophysics Data System (ADS)

Chan, Tsz On Mario

Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some cases, which led to desired chemical phase formation. The residue of polymer thermal decomposition was also controlled and utilized for certain functionality in some nanostructures. Throughout this study, we successfully fabricated several novel functional structures and revealed a new formation mechanism of metal/metal oxide nanotubes. The magnetic and electrical properties of these nanostructures were studied and optimized for applications in soft magnetic materials and spintronics devices. In the second part, (Chapter 7) a study on memristive switching devices with magnetron-sputtered metal-semiconductor-metal thin film structures based on ZnO is presented. Resistive random access memory (RRAM) is a new, non-volatile memory based on the memristor effect theoretically predicted by Leon Chua in 1971 and first experimentally demonstrated by Hewlett Packard in 2008. The unit cell of a RRAM (a memristor) is a two-terminal device in which the switching medium is sandwiched between the top and bottom electrodes and the resistance of the switching medium can be modulated by applying an electrical signal (current or voltage) to the electrodes. On the other hand, the significance of a memristor, as the fourth element of circuit elements besides resistor, capacitor and inductor, is not limited to just being a candidate for next-generation memory. Owing to the unique i-v characteristics of non-linear memristors that cannot be duplicated with any combinations of the other three basic elements in a passive circuitry, many new electrical functions are being developed based on the memristors. In our study, various contact electrode combinations and semiconductor doping profiles were utilized to achieve different functional resistive switching behaviors and to help fundamentally understand the underlying switching mechanisms in ZnO-based thin film structures. Two distinctive switching mechanisms (ferroelectric charge-induced resistive switching and dopant-induced filament-type resistive switching) have been identified in specified structures. Among them, the ferroelectric charge induced resistive switching is new to the existing mechanisms; and the crucial role of the electrode oxide layer in the filament type resistive switching was reported for the first time. Based on these studies, a unique structure that is believed to combine the two competing switching mechanisms was demonstrated. The new memory structure acts like a complimentary resistive switching memory (CRS) that is designed to eliminate the cross-talk issue in RRAM.

One-step green route to narrowly dispersed copper nanocrystals

NASA Astrophysics Data System (ADS)

Wu, Chunwei; Mosher, Brian P.; Zeng, Taofang

2006-12-01

We report a total "green" chemical method in aqueous solution for synthesizing stable narrowly distributed copper nanoparticles with average diameter less than 5 nm in the presence of Polyvinylpyrrolidone (PVP) as a stabilizer and without any inert gas protection. In our synthesis route, ascorbic acid, natural vitamin C (VC), an excellent oxygen scavenger, acts as both reducing agent and antioxidant, to reduce the metallic ion precursor, and to effectively prevent the common oxidation process of the newborn pure copper nanoclusters.

Synthesis of Metal-Oxide/Carbon-Fiber Heterostructures and Their Properties for Organic Dye Removal and High-Temperature CO2 Adsorption

NASA Astrophysics Data System (ADS)

Shao, Liangzhi; Nie, Shibin; Shao, Xiankun; Zhang, LinLin; Li, Benxia

2018-03-01

One-dimensional metal-oxide/carbon-fiber (MO/CF) heterostructures were prepared by a facile two-step method using the natural cotton as a carbon source the low-cost commercial metal salts as precursors. The metal oxide nanostructures were first grown on the cotton fibers by a solution chemical deposition, and the metal-oxide/cotton heterostructures were then calcined and carbonized in nitrogen atmosphere. Three typical MO/CF heterostructures of TiO2/CF, ZnO/CF, and Fe2O3/CF were prepared and characterized. The loading amount of the metal oxide nanostructures on carbon fibers can be tuned by controlling the concentration of metal salt in the chemical deposition process. Finally, the performance of the as-obtained MO/CF heterostructures for organic dye removal from water was tested by the photocatalytic degradation under a simulated sunlight, and their properties of high-temperature CO2 adsorption were predicted by the temperature programmed desorption. The present study would provide a desirable strategy for the synthesis of MO/CF heterostructures for various applications.

Method for reducing the sulfur content of a sulfur-containing hydrocarbon stream

DOEpatents

Mahajan, Devinder

2004-12-28

The sulfur content of a liquid hydrocarbon stream is reduced under mild conditions by contracting a sulfur-containing liquid hydrocarbon stream with transition metal particles containing the transition metal in a zero oxidation state under conditions sufficient to provide a hydrocarbon product having a reduced sulfur content and metal sulfide particles. The transition metal particles can be produced in situ by adding a transition metal precursor, e.g., a transition metal carbonyl compound, to the sulfur-containing liquid feed stream and sonicating the feed steam/transition metal precursor combination under conditions sufficient to produce the transition metal particles.

Alkali Metal Doping for Improved CH3NH3PbI3 Perovskite Solar Cells.

PubMed

Zhao, Wangen; Yao, Zhun; Yu, Fengyang; Yang, Dong; Liu, Shengzhong Frank

2018-02-01

Organic-inorganic hybrid halide perovskites are proven to be a promising semiconductor material as the absorber layer of solar cells. However, the perovskite films always suffer from nonuniform coverage or high trap state density due to the polycrystalline characteristics, which degrade the photoelectric properties of thin films. Herein, the alkali metal ions which are stable against oxidation and reduction are used in the perovskite precursor solution to induce the process of crystallization and nucleation, then affect the properties of the perovskite film. It is found that the addition of the alkali metal ions clearly improves the quality of perovskite film: enlarges the grain sizes, reduces the defect state density, passivates the grain boundaries, increases the built-in potential ( V bi ), resulting to the enhancement in the power conversion efficiency of perovskite thin film solar cell.

Synthesis of Bimetallic Platinum Nanoparticles for Biosensors

PubMed Central

Leteba, Gerard M.; Lang, Candace I.

2013-01-01

The use of magnetic nanomaterials in biosensing applications is growing as a consequence of their remarkable properties; but controlling the composition and shape of metallic nanoalloys is problematic when more than one precursor is required for wet chemistry synthesis. We have developed a successful simultaneous reduction method for preparation of near-spherical platinum-based nanoalloys containing magnetic solutes. We avoided particular difficulties in preparing platinum nanoalloys containing Ni, Co and Fe by the identification of appropriate synthesis temperatures and chemistry. We used transmission electron microscopy (TEM) to show that our particles have a narrow size distribution, uniform size and morphology, and good crystallinity in the as-synthesized condition. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirms the coexistence of Pt with the magnetic solute in a face-centered cubic (FCC) solid solution. PMID:23941910

Zinc-aluminum oxide solid solution nanosheets obtained by pyrolysis of layered double hydroxide as the photoanodes for dye-sensitized solar cells.

PubMed

Xu, Zhiyuan; Shi, Jingjing; Haroone, Muhammad Sohail; Chen, Wenpeng; Zheng, Shufang; Lu, Jun

2018-04-01

Due to the superiority of metal-doped ZnO compared to TiO 2 , the Zn-M (M = Al 3+ , Ga 3+ , Cr 3+ , Ti 4+ , Ce 4+ ) mixed metal oxide solid solutions have been extensively studied for photocatalytic and photovoltaic applications. In this work, a systematic research has proceeded for the preparation of a zinc-aluminum oxide semiconductor as a photoanode for the dye-sensitized solar cells (DSSCs) by a simple pyrolysis route with the Zn-Al layered double hydroxide (LDH) as a precursor. The Zn-Al oxide solid solution has been applied for DSSCs as an electron acceptor, which is used to study the influence of different Al content and sintering temperature on the device efficiency. Finally, the Zn-Al oxide solid solution with calcination temperature 600 °C and Al 27 at.% content exhibits the best performance. The photoelectric efficiency improved 100 times when the Al 3+ content decreased from 44 to 27 at.%. The Zn x Al y O solid solution show a reasonable efficiency as photoanode materials in DSSCs, with the best preliminary performance reported so far, and shows its potential application for the photovoltaic devices. Copyright © 2018 Elsevier Inc. All rights reserved.

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

Ying, Minju, E-mail: mjying@bnu.edu.cn, E-mail: g.gehring@sheffield.ac.uk; Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875; Blythe, Harry J.

We investigate the magnetic properties of ZnCoO thin films grown by pulsed laser deposition (PLD) from targets made containing metallic Co or CoO precursors instead of the usual Co{sub 3}O{sub 4}. We find that the films grown from metallic Co precursors in an oxygen rich environment contain negligible amounts of Co metal and have a large magnetization at room temperature. Structural analysis by X-ray diffraction and magneto-optical measurements indicate that the enhanced magnetism is due, in part, from Zn vacancies that partially compensate the naturally occurring n-type defects. We conclude that strongly magnetic films of Zn{sub 0.95}Co{sub 0.05}O that domore » not contain metallic cobalt can be grown by PLD from Co-metal-precursor targets if the films are grown in an oxygen atmosphere.« less

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Sha Li, Chen; Li, Yu Ning; Wu, Yi Liang; Ong, Beng S.; Loutfy, Rafik O.

2008-06-01

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

Supramolecular Assembly of Single-Source Metal-Chalcogenide Nanocrystal Precursors.

PubMed

Smith, Stephanie C; Bryks, Whitney; Tao, Andrea R

2018-05-28

In this Feature Article, we discuss our recent work in the synthesis of novel supramolecular precursors for semiconductor nanocrystals. Metal chalcogenolates that adopt liquid crystalline phases are employed as single-source precursors that template the growth of shaped solid-state nanocrystals. Supramolecular assembly is programmed by both precursor chemical composition and molecular parameters such alkyl chain length, steric bulk, and the intercalation of halide ions. Here, we explore the various design principles that enable the rational synthesis of these single-source precursors, their liquid crystalline phases, and the various semiconductor nanocrystal products that can be generated by thermolysis, ranging from highly anisotropic two-dimensional nanosheets and nanodisks to spheres.

Reverse micelle synthesis of nanoscale metal containing catalysts

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

Darab, J.G.; Fulton, J.L.; Linehan, J.C.

1993-03-01

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction andmore » precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni{sub 3}Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.« less

Dielectric properties of Ba0.6Sr0.4TiO3 thin films deposited by mist plasma evaporation using aqueous solution precursor

NASA Astrophysics Data System (ADS)

Huang, Hui; Shi, Peng; Wang, Minqiang; Yao, Xi; Tan, O. K.

2006-06-01

Mist plasma evaporation (MPE) technique has been developed to deposit Ba0.6Sr0.4TiO3 (BST) thin films on SiO2/Si and Pt/Ti/SiO2/Si substrates at atmospheric pressure using metal nitrate aqueous solution as precursor. MPE is characterized by the injection of liquid reactants into thermal plasma where the source materials in the droplets are evaporated by the high temperature of the thermal plasma. Nanometer-scale clusters are formed in the tail flame of the plasma, and then deposited and rearranged on the substrate at a lower temperature. Due to the high temperature annealing process of the thermal plasma before deposition, well-crystallized BST films were deposited at substrate temperature of 630 °C. The dielectric constant and dielectric loss of the film at 100 kHz are 715 and 0.24, respectively. Due to the good crystallinity of the BST films deposited by MPE, high dielectric tunability up to 39.3% is achieved at low applied electric field of 100 kV cm-1.

Facile synthesis of PdAgTe nanowires with superior electrocatalytic activity

NASA Astrophysics Data System (ADS)

Hong, Wei; Wang, Jin; Wang, Erkang

2014-12-01

In this work, ultrathin Te nanowires (NWs) with high-aspect-ratio are prepared by a simple hydrothermal method. By using Te NWs as the sacrificial template, we demonstrate a facile and efficient method for the synthesis of PdAgTe NWs with high-quality through the partly galvanic replacement between Te NWs and the corresponding noble metal salts precursors in an aqueous solution. The compositions of PdAgTe NWs can be tuned by simply altering the concentration of the precursors. After cyclic voltammetry treatment, multi-component PdAgTe NW with a highly active and stable surface can be obtained. The structure and composition of the as-prepared nanomaterials are analyzed by transmission electron microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, inductively coupled plasma-mass spectroscopy and X-ray photoelectron spectroscopy. Electrochemical catalytic measurement results prove that the as synthesized PdAgTe NWs present superior catalytic activity toward ethanol electrooxidation in alkaline solution than the commercial Pd/C catalyst, which making them can be used as effective catalysts for the direct ethanol fuel cells.

Reverse micelle synthesis of nanoscale metal containing catalysts. [Nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide nanoscale powders

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

Darab, J.G.; Fulton, J.L.; Linehan, J.C.

1993-03-01

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction andmore » precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni[sub 3]Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.« less

Local structure in solid solutions of stabilised zirconia with actinide dioxides (UO{sub 2}, NpO{sub 2})

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

Walter, Marcus, E-mail: marcus.walter@vkta.d; Somers, Joseph; Bouexiere, Daniel

2011-04-15

The local structure of (Zr,Lu,U)O{sub 2-x} and (Zr,Y,Np)O{sub 2-x} solid solutions has been investigated by extended X-ray absorption fine structure (EXAFS). Samples were prepared by mixing reactive (Zr,Lu)O{sub 2-x} and (Zr,Y)O{sub 2-x} precursor materials with the actinide oxide powders, respectively. Sintering at 1600 {sup o}C in Ar/H{sub 2} yields a fluorite structure with U(IV) and Np(IV). As typical for stabilised zirconia the metal-oxygen and metal-metal distances are characteristic for the different metal ions. The bond lengths increase with actinide concentration, whereas highest adaptation to the bulk stabilised zirconia structure was observed for U---O and Np---O bonds. The Zr---O bond showsmore » only a slight increase from 2.14 A at 6 mol% actinide to 2.18 A at infinite dilution in UO{sub 2} and NpO{sub 2}. The short interatomic distance between Zr and the surrounding oxygen and metal atoms indicate a low relaxation of Zr with respect to the bulk structure, i.e. a strong Pauling behaviour. -- Graphical abstract: Metal-oxygen bond distances in (Zr,Lu,U)O{sub 2-x} solid solutions with different oxygen vacancy concentrations (Lu/Zr=1 and Lu/Zr=0.5). Display Omitted Research Highlights: {yields} EXAFS indicates high U and Np adaption to the bulk structure of stabilised zirconia. {yields} Zr---O bond length is 2.18 A at infinite Zr dilution in UO{sub 2} and NpO{sub 2}. {yields} Low relaxation (strong Pauling behaviour) of Zr explains its low solubility in UO{sub 2}.« less

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

NASA Astrophysics Data System (ADS)

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-03-01

A comparative study of amine and silver carboxylate adducts [R1COOAg-2(R2NH2)] (R1 = 1, 7, 11; R2 = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (1H and 13C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

Pilot Scale Production of Activated Carbon Spheres Using Fluidized Bed Reactor and Its Evaluation for the Removal of Hexavalent Chromium from Aqueous Solutions

NASA Astrophysics Data System (ADS)

Tripathi, Nagesh Kumar; Sathe, Manisha

2017-12-01

Large scale production of activated carbon is need of ongoing research due to its excellent adsorption capacity for removal of heavy metals from contaminated solutions. In the present study, polymeric precursor polystyrene beads [Brunauer Emmett Teller (BET) surface area, 46 m2/g; carbon content, 40.64%; crushing strength, 0.32 kg/sphere] were used to produce a new variant of activated carbon, Activated Carbon Spheres (ACS) in a pilot scale fluidized bed reactor. ACS were prepared by carbonization of polymeric precursor at 850 °C followed by activation of resultant material with steam. Prepared ACS were characterized using scanning electron microscope, CHNS analyzer, thermogravimetric analyzer, surface area analyzer and crushing strength tester. The produced ACS have 1009 m2/g BET surface area, 0.89 cm3/g total pore volume, 92.32% carbon content and 1.1 kg/sphere crushing strength with less than 1% of moisture and ash content. The ACS were also evaluated for its potential to remove hexavalent chromium [Cr(VI)] from contaminated solutions. The chromium removal is observed to be 99.1% at initial concentration 50 mg/l, pH 2, ACS dose 1 g/l, contact time 2 h, agitation 120 rpm and temperature 30 °C. Thus ACS can be used as an adsorbent material for the removal of Cr(VI) from contaminated solutions.

Process for preparing transition metal nitrides and transition metal carbonitrides and their reaction intermediates

DOEpatents

Maya, Leon

1988-05-24

A process for making ammonolytic precursors to nitride and carbonitride ceramics. Extreme reaction conditions are not required and the precursor is a powder-like substance that produces ceramics of improved purity and morphology upon pyrolysis.

Influences of Silver and Zinc Contents in the Stannite Ag2ZnSnS4 Photoelectrodes on Their Photoelectrochemical Performances in the Salt-Water Solution.

PubMed

Cheng, Kong-Wei; Hong, Shu-Wei

2018-06-13

The multicomponent metal sulphide (stannite Ag2ZnSnS4) samples were grown onto the conductive metal oxide coated glass substrates by using the sulfurization of co-sputtering silver-zinc-tin precursors. Several [Ag]/[Zn+Sn] and [Zn]/[Sn] ratios were set in the metal precursors to investigate their influences on the crystal phases, microstructures and physical properties of the stannite Ag2ZnSnS4 samples. The results of the crystal phases and compositions of samples showed that the stannite Ag2ZnSnS4 phase can be obtained using the two-step sulfurization process, which maintained the silver-zinc-tin precursors at 160C for 1 hour and then kept them at 450oC for 30 minutes under sulfur/nitrogen atmosphere. N-type stannite Ag2ZnSnS4 samples with the carrier concentrations of 5.54x1012 - 9.11x1012 cm-3 can be obtained. High resistivities of Ag2ZnSnS4 samples were observed due to the low values of carrier concentration. Increasing the silver content in the sample can improve its PEC performance due to the decrease in the sample resistivity. The ratio of [Ag]/[Zn+Sn] kept at 0.8 and ratio of [Zn]/[Sn] set at 0.90 in the stannite Ag2ZnSnS4 sample had the highest photoelectrochemical performance of 0.31 mA.cm-2 with the potential set at 1.23 V vs. relative hydrogen electrode applied on the sample because of it having the lowest charge transfer resistance in electrolyte.

Ferroic Materials: Design, Preparation and Characteristics. Ceramic Transactions. Volume 43. Proceedings of International Symposium Held in Honolulu, Hawaii on November 7-10, 1993.

DTIC Science & Technology

1993-11-10

realized. Metal carboxylates are often used as precursors for ceramic oxides since they tend to be air-stable, soluble in organic solvents, and decompose...metalorganic precursors [9] . These include routes based solely on metal alkoxides [9, 101 or metal carboxylates (e.g. the Pechini (or citrate) process

Characterization of High-Velocity Solution Precursor Flame-Sprayed Manganese Cobalt Oxide Spinel Coatings for Metallic SOFC Interconnectors

NASA Astrophysics Data System (ADS)

Puranen, Jouni; Laakso, Jarmo; Kylmälahti, Mikko; Vuoristo, Petri

2013-06-01

A modified high-velocity oxy-fuel spray (HVOF) thermal spray torch equipped with liquid feeding hardware was used to spray manganese-cobalt solutions on ferritic stainless steel grade Crofer 22 APU substrates. The HVOF torch was modified in such a way that the solution could be fed axially into the combustion chamber through 250- and 300-μm-diameter liquid injector nozzles. The solution used in this study was prepared by diluting nitrates of manganese and cobalt, i.e., Mn(NO3)2·4H2O and Co(NO3)2·6H2O, respectively, in deionized water. The as-sprayed coatings were characterized by X-ray diffraction and field-emission scanning electron microscopy operating in secondary electron mode. Chemical analyses were performed on an energy dispersive spectrometer. Coatings with remarkable density could be prepared by the novel high-velocity solution precursor flame spray (HVSPFS) process. Due to finely sized droplet formation in the HVSPFS process and the use of as delivered Crofer 22 APU substrate material having very low substrate roughness ( R a < 0.5 μm), thin and homogeneous coatings, with thicknesses lower than 10 μm could be prepared. The coatings were found to have a crystalline structure equivalent to MnCo2O4 spinel with addition of Co-oxide phases. Crystallographic structure was restored back to single-phase spinel structure by heat treatment.

TiO2/WO3 photoactive bilayers in the UV-Vis light region

NASA Astrophysics Data System (ADS)

Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Vamvakaki, M.; Katsarakis, N.

2017-04-01

In this work, photoactive bilayered films consisting of anatase TiO2 and monoclinic WO3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO3 precursor solution, when deposited as an overlying layer on TiO2 by two annealing steps ( 76% methylene blue decolorization in 300 min of irradiation versus 59% in the case of a bare TiO2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO2 films with WO3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination.

Understanding the Thermal Properties of Precursor-Ionomers to Optimize Fabrication Processes for Ionic Polymer-Metal Composites (IPMCs)

PubMed Central

Choi, Kisuk; Olsen, Zakai; Hwang, Taeseon; Nam, Jae-Do

2018-01-01

Ionic polymer-metal composites (IPMCs) are one of many smart materials and have ionomer bases with a noble metal plated on the surface. The ionomer is usually Nafion, but recently Aquivion has been shown to be a promising alternative. Ionomers are available in the form of precursor pellets. This is an un-activated form that is able to melt, unlike the activated form. However, there is little study on the thermal characteristics of these precursor ionomers. This lack of knowledge causes issues when trying to fabricate ionomer shapes using methods such as extrusion, hot-pressing, and more recently, injection molding and 3D printing. To understand the two precursor-ionomers, a set of tests were conducted to measure the thermal degradation temperature, viscosity, melting temperature, and glass transition. The results have shown that the precursor Aquivion has a higher melting temperature (240 °C) than precursor Nafion (200 °C) and a larger glass transition range (32–65 °C compared with 21–45 °C). The two have the same thermal degradation temperature (~400 °C). Precursor Aquivion is more viscous than precursor Nafion as temperature increases. Based on the results gathered, it seems that the precursor Aquivion is more stable as temperature increases, facilitating the manufacturing processes. This paper presents the data collected to assist researchers in thermal-based fabrication processes. PMID:29693584

Elaboration of the hydroxyapatite with different precursors and application for the retention of the lead.

PubMed

Meski, S; Ziani, S; Khireddine, H; Yataghane, F; Ferguene, N

2011-01-01

Carbonate hydroxyapatite (CHAP) was synthesized from different precursors; synthetic (CaCO3 and Ca(OH)2) and natural (egg shell before and after calcinations at 900 degrees C) under different conditions and characterized by using TG/DTG analysis, X-ray powder diffraction (XRD) method and Fourier transform infrared (FT-IR) spectroscopy techniques. The results of these analyses indicate that the four powders present the same structure of hydroxyapatite. Furthermore the four powders obtained were used for the retention of lead. The results obtained indicated that all powders present high adsorption capacity for lead, but from environmental and economic views, the hydroxyapatite synthesized from eggshell no calcined (HA2) is most advantageous. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and sorbent dosage was studied and discussed.

Lanthanum aluminum oxide thin-film dielectrics from aqueous solution.

PubMed

Plassmeyer, Paul N; Archila, Kevin; Wager, John F; Page, Catherine J

2015-01-28

Amorphous LaAlO3 dielectric thin films were fabricated via solution processing from inorganic nitrate precursors. Precursor solutions contained soluble oligomeric metal-hydroxyl and/or -oxo species as evidenced by dynamic light scattering (DLS) and Raman spectroscopy. Thin-film formation was characterized as a function of annealing temperature using Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray reflectivity (XRR), scanning electron microscopy (SEM), and an array of electrical measurements. Annealing temperatures ≥500 °C result in thin films with low leakage-current densities (∼1 × 10(-8) A·cm(-2)) and dielectric constants ranging from 11.0 to 11.5. When incorporated as the gate dielectric layer in a-IGZO thin-film transistors (TFTs), LaAlO3 thin films annealed at 600 °C in air yielded TFTs with relatively low average mobilities (∼4.5 cm(2)·V(-1)·s(-1)) and high turn-on voltages (∼26 V). Interestingly, reannealing the LaAlO3 in 5%H2/95%N2 at 300 °C before deposition of a-IGZO channel layers resulted in TFTs with increased average mobilities (11.1 cm(2)·V(-1)·s(-1)) and lower turn-on voltages (∼6 V).

Surface defects on the Gd{sub 2}Zr{sub 2}O{sub 7} oxide films grown on textured NiW technical substrates by chemical solution method

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

Zhao, Y., E-mail: yuezhao@sjtu.edu.cn

2017-02-15

Epitaxial growth of oxide thin films has attracted much interest because of their broad applications in various fields. In this study, we investigated the microstructure of textured Gd{sub 2}Zr{sub 2}O{sub 7} films grown on (001)〈100〉 orientated NiW alloy substrates by a chemical solution deposition (CSD) method. The aging effect of precursor solution on defect formation was thoroughly investigated. A slight difference was observed between the as-obtained and aged precursor solutions with respect to the phase purity and global texture of films prepared using these solutions. However, the surface morphologies are different, i.e., some regular-shaped regions (mainly hexagonal or dodecagonal) weremore » observed on the film prepared using the as-obtained precursor, whereas the film prepared using the aged precursor exhibits a homogeneous structure. Electron backscatter diffraction and scanning electron microscopy analyses showed that the Gd{sub 2}Zr{sub 2}O{sub 7} grains present within the regular-shaped regions are polycrystalline, whereas those present in the surrounding are epitaxial. Some polycrystalline regions ranging from several micrometers to several tens of micrometers grew across the NiW grain boundaries underneath. To understand this phenomenon, the properties of the precursors and corresponding xerogel were studied by Fourier transform infrared spectroscopy and coupled thermogravimetry/differential thermal analysis. The results showed that both the solutions mainly contain small Gd−Zr−O clusters obtained by the reaction of zirconium acetylacetonate with propionic acid during the precursor synthesis. The regular-shaped regions were probably formed by large Gd−Zr−O frameworks with a metastable structure in the solution with limited aging time. This study demonstrates the importance of the precise control of chemical reaction path to enhance the stability and homogeneity of the precursors of the CSD route. - Highlights: •We investigate microstructure of Gd{sub 2}Zr{sub 2}O{sub 7} films grown by a chemical solution route. •The aging effect of precursor solution on formation of surface defect was thoroughly studied. •Gd−Zr−O clusters are present in the precursor solutions.« less

Solution combustion synthesis of oxide semiconductors

NASA Astrophysics Data System (ADS)

Thomas, Abegayl Lorenda Shara-Lynn

The quest for stable and efficient photocatalytic materials beyond TiO2 and WO3 has over the years led to the development of new materials that possess varied interfacial energetics. This dissertation study focused on using for the first time a novel method, solution combustion synthesis (SCS), to prepare two distinct families of binary metal-based oxide semiconductor materials. Detailed studies on material characteristics and applications were carried out on tungsten- and niobium-based oxide semiconductors with varying principal metals. Initial emphasis was placed on the SCS of tungsten-based oxide semiconductors (ZnWO4, CuWO4, and Ag2WO4). The influence of different tungsten precursor's on the resultant product was of particular relevance to this study, with the most significant effects highlighted. Upon characterization, each sample's photocatalytic activity towards methyl orange dye degradation was studied, and benchmarked against their respective commercial oxide sample, obtained by solid-state ceramic synthesis. Detailed analysis highlighted the importance of the SCS process as a time- and energy-efficient method to produce crystalline nano-sized materials even without additional or excessive heat treatment. It was observed that using different tungstate precursors does influence the structural and morphological make-up of the resulting materials. The as-synthesized tungstate materials showed good photocatalytic performance for the degradation of methyl orange dye, while taking into account specific surface area and adsorbed dye amount on the surface of the material. Like the tungstate's, niobium-based oxide semiconductors CuNb 2O6 and ZnNb2O6 were the first to be synthesized via solution combustion synthesis. Particular attention was placed on the crystal structures formed while using an oxalate niobium precursor during the reaction process. X-ray patterns yielded a multiphase structure for the ZnNb2O6 and a single phase structure for CuNb 2O6. Photoelectrochemical (PEC) measurements were used both as a characterization tool as well as an application for CO2 reduction. The PEC data was consistent with an n-type and p-type semiconductor for ZnNb 2O6 and CuNb2O6 respectively. Good phototelectrochemical behavior was observed for CuNb2O6 with stable, high photocurrents suggesting a suitable material for CO 2 reduction while in a 0.1 M NaHCO3 + CO2 medium. All in all, this dissertation study expounds on metal ion insertion into various structural frameworks (e.g. WO3) which may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation.

Fabrication of core-shell Fe{sub 3}O{sub 4}@MIL-100(Fe) magnetic microspheres for the removal of Cr(VI) in aqueous solution

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

Yang, Qingxiang, E-mail: qxyangzz@163.com; Zhao, Qianqian; Ren, ShuangShuang

Facile regeneration of an adsorbent is very important for commercial feasibility. One typical highly porous metal-organic framework (MOF) materials based on MIL-100(Fe) and magnetic iron oxide particles (denoted as MMCs) with diameter about of 350 nm were successfully synthesized. The growth of MIL-100(Fe) shell on the surface of Fe{sub 3}O{sub 4} was utilized precursor as crystal seed via in-situ step hydrothermal reaction. It is a simple way to obtain well organized core-shell MOF composites, compared to the step-by-step method. MMCs were firstly used to uptake of Cr(VI) anions in aqueous solution. Adsorption experiments were carried out in batch sorption mode investigatingmore » with the factors of contact time (0–1000 min), pH (from 2 to 12), dose of adsorbent (4–25 mg), and initial Cr(VI) concentration (range from 10 to 100 ppm). - Graphical abstract: One typical highly porous metal-organic framework (MOF) materials based on MIL-100(Fe) and magnetic iron oxide particles (denoted as MMCs) were successfully synthesized. Utilizing Fe{sub 3}O{sub 4} precursor as crystal seed to grow MIL-100(Fe) shell by in-situ step hydrothermal reaction. It is a simple way to obtain core-shell MOF composites. MMCs could effectively uptake of Cr(VI) anions in aqueous solution. - Highlights: • Fe{sub 3}O{sub 4}@MIL-100(Fe) composites with core-shell structure were successfully prepared through a simple method. • The influence factors on Cr(VI) adsorption by Fe{sub 3}O{sub 4}@MIL-100(Fe) were investigated. • Cr(VI) can efficiently adsorbed by Fe{sub 3}O{sub 4}@MIL-100(Fe) composites from aqueous solution.« less

Fabrication of solution processed 3D nanostructured CuInGaS₂ thin film solar cells.

PubMed

Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

2014-03-28

In this study we demonstrate the fabrication of CuInGaS₂ (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ∼1.3 μm. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ∼6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions.

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors.

PubMed

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-01-01

A comparative study of amine and silver carboxylate adducts [R 1 COOAg-2(R 2 NH 2 )] (R 1  = 1, 7, 11; R 2  = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13 C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ( 1 H and 13 C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism. Graphical abstractThe synthesis of a series (bis)alkylamine silver(I) carboxylate complexes in nonpolar solvents were carried out and fully characterized both in the solid and solution. Carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination. The complexes form layered structures which thermally decompose forming nanoparticles stabilized only by aliphatic carboxylates.

Thermal conversion of biomass to valuable fuels, chemical feedstocks and chemicals

DOEpatents

Peters, William A [Lexington, MA; Howard, Jack B [Winchester, MA; Modestino, Anthony J [Hanson, MA; Vogel, Fredreric [Villigen PSI, CH; Steffin, Carsten R [Herne, DE

2009-02-24

A continuous process for the conversion of biomass to form a chemical feedstock is described. The biomass and an exogenous metal oxide, preferably calcium oxide, or metal oxide precursor are continuously fed into a reaction chamber that is operated at a temperature of at least 1400.degree. C. to form reaction products including metal carbide. The metal oxide or metal oxide precursor is capable of forming a hydrolizable metal carbide. The reaction products are quenched to a temperature of 800.degree. C. or less. The resulting metal carbide is separated from the reaction products or, alternatively, when quenched with water, hydolyzed to provide a recoverable hydrocarbon gas feedstock.

Preparation of cermets

DOEpatents

Morgan, Chester S.

1978-01-01

Cermets are produced by the process of forming a physical mixture of a ceramic powder material with an elemental metal precursor compound and by decomposing the elemental metal precursor compound within the mixture. The decomposition step may be carried out either prior to or during a forming and densification step.

Exploring the anionic reactivity of ynimines, useful precursors of metalated ketenimines.

PubMed

Laouiti, Anouar; Couty, François; Marrot, Jérome; Boubaker, Taoufik; Rammah, Mohamed M; Rammah, Mohamed B; Evano, Gwilherm

2014-04-18

Insights into the reactivity of ynimines under anionic conditions are reported. They were shown to be excellent precursors of metalated ketenimines, which can be generated in situ by the reaction of ynimines with organolithium reagents or strong bases. The metalated ketenimines can then be trapped with various electrophiles and, depending on their substitution pattern, afford original and divergent entries to various building blocks.

Kinetic Control of Aqueous Hydrolysis: Modulating Structure/Property Relationships in Inorganic Crystals

NASA Astrophysics Data System (ADS)

Neilson, James R.

2011-12-01

A grand challenge in materials science and chemistry revolves around the preparation of materials with desired properties by controlling structure on multiple length scales. Biology approaches this challenge by evolving tactics to transform soluble precursors into materials and composites with macro-scale and atomic precision. Studies of biomineralization in siliceous sponges led to the discovery of slow, catalytic hydrolysis of molecular precursors in the biogenesis of silica skeletal elements with well defined micro- and nano-scale architectures. However, the role of aqueous hydrolysis in the limit of kinetic control is not well understood; this allows us to form a central hypothesis: that the kinetics of hydrolysis modulate the structures of materials and their properties. As a model system, the diffusion of a simple hydrolytic catalyst (such as ammonia) across an air-water interface into a metal salt solution reproduces some aspects of the chemistry found in biomineralization, namely kinetic and vectorial control. Variation of the catalyst concentration modulates the hydrolysis rate, and thus alters the resulting structure of the inorganic crystals. Using aqueous solutions of cobalt(II) chloride, each product (cobalt hydroxide chloride) forms with a unique composition, despite being prepared from identical mother liquors. Synchrotron X-ray total scattering methods are needed to locate the atomic positions in the material, which are not aptly described by a traditional crystallographic unit cell due to structural disorder. Detailed definition of the structure confirms that the hydrolysis conditions systematically modulate the arrangement of atoms in the lattice. This tightly coupled control of crystal formation and knowledge of local and average structures of these materials provides insight into the unusual magnetic properties of these cobalt hydroxides. The compounds studied show significant and open magnetization loops with little variation with composition or structure, yet subtle and systematic changes in the mean-field spin interaction strength and spin entropy loss. Meanwhile, neutron powder diffraction reveals a fully compensated Ńeel state; a detailed analysis of the local structure defines the aperiodic clusters of polyhedra responsible for magnetic order. The rate of hydrolysis of metal precursors modulates the disposition of these polyhedral clusters. The strategy of kinetically controlling aqueous hydrolysis also extends to the formation of stoichiometrically ordered bimetallic crystals [MSn(OH)6], where the hydrolysis behavior for dissimilar metal cations must be controlled via counteranions or precursor selection. In the formation of these ordered double perovskite hydroxides, the rate of hydrolysis is held constant in the limit of kinetic control. Instead, the propensities of different cations to undergo controlled hydrolysis are probed by their ability to form ordered crystals. Collectively, these studies demonstrate how systematic variation in the kinetic conditions of materials preparation and the character of each solute control the structure and properties of materials, with a precision not attainable through traditional or near-equilibrium approaches.

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

2008-05-06

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

1999-01-01

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

1999-07-13

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

Near-Field Microwave Detection of Corrosion Precursor Pitting under Thin Dielectric Coatings in Metallic Substrate

NASA Astrophysics Data System (ADS)

Hughes, D.; Zoughi, R.; Austin, R.; Wood, N.; Engelbart, R.

2003-03-01

Detection of corrosion precursor pitting on metallic surfaces under various coatings and on bare metal is of keen interest in evaluation of aircraft fuselage. Near-field microwave nondestructive testing methods, utilizing open-ended rectangular waveguides and coaxial probes, have been used extensively for detection of surface flaws in metals, both on bare metal and under a dielectric coating. This paper presents the preliminary results of using microwave techniques to detect corrosion precursor pitting under paint and primer, applique and on bare metal. Machined pits of 500 μm diameter were detected using open-ended rectangular waveguides at V-Band under paint and primer and applique, and on bare metal. Using coaxial probes, machined pits with diameters down to 150 μm on bare metal were also detected. Relative pit size and density were shown on a corrosion-pitted sample using open-ended rectangular waveguides at frequencies of 35 GHz to 70 GHz. The use of Boeing's MAUS™ scanning systems provided improved results by alleviating standoff variation and scanning artifact. Typical results of this investigation are also presented.

Synthesis of poly(aminopropyl/methyl)silsesquioxane particles as effective Cu(II) and Pb(II) adsorbents.

PubMed

Lu, Xin; Yin, Qiangfeng; Xin, Zhong; Li, Yang; Han, Ting

2011-11-30

Poly(aminopropyl/methyl)silsesquioxane (PAMSQ) particles have been synthesized by a one-step hydrolytic co-condensation process using 3-aminopropyltriethoxysilane (APTES) and methyltrimethoxysilane (MTMS) as precursors in the presence of base catalyst in aqueous medium. The amino functionalities of the particles could be controlled by adjusting the organosilanes feed ratio. The compositions of the amino-functionalized polysilsesquioxanes were confirmed by FT-IR spectroscopy, solid-state (29)Si NMR spectroscopy, and elemental analysis. The strong adsorbability of Cu(II) and Pb(II) ions onto PAMSQ particles was systematically examined. The effect of adsorption time, initial metal ions concentration and pH of solutions was studied to optimize the metal ions adsorbability of PAMSQ particles. The kinetic studies indicated that the adsorption process well fits the pseudo-second-order kinetics. Adsorption phenomena appeared to follow Langmuir isotherm. The PAMSQ particles demonstrate the highest Cu(II) and Pb(II) adsorption capacity of 2.29 mmol/g and 1.31 mmol/g at an initial metal ions concentration of 20mM, respectively. The PAMSQ particles demonstrate a promising application in the removal of Cu(II) and Pb(II) ions from aqueous solutions. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation of superconductor precursor powders

DOEpatents

Bhattacharya, Raghunath; Blaugher, Richard D.

1995-01-01

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

Densified waste form and method for forming

DOEpatents

Garino, Terry J.; Nenoff, Tina M.; Sava Gallis, Dorina Florentina

2015-08-25

Materials and methods of making densified waste forms for temperature sensitive waste material, such as nuclear waste, formed with low temperature processing using metallic powder that forms the matrix that encapsulates the temperature sensitive waste material. The densified waste form includes a temperature sensitive waste material in a physically densified matrix, the matrix is a compacted metallic powder. The method for forming the densified waste form includes mixing a metallic powder and a temperature sensitive waste material to form a waste form precursor. The waste form precursor is compacted with sufficient pressure to densify the waste precursor and encapsulate the temperature sensitive waste material in a physically densified matrix.

Cobalt Nanoparticle-Embedded Porous Carbon Nanofibers with Inherent N- and F-Doping as Binder-Free Bifunctional Catalysts for Oxygen Reduction and Evolution Reactions.

PubMed

Singhal, Richa; Kalra, Vibha

2017-01-18

Efficient, low-cost, non-precious metal-based, and stable bifunctional electrocatalysts are key to various energy storage and conversion devices such as regenerative fuel cells and metal-air batteries. In this work, we report cobalt nanoparticle-embedded porous carbon nanofibers with inherent N- and F-doping as binder-free bifunctional electrocatalysts with excellent activity for both the oxygen reduction and oxygen evolution reaction (ORR/OER) in an alkaline medium. Single-step electrospinning of a solution of the polymer mixture (carbon precursor) and the cobalt precursor followed by controlled pyrolysis with an intermediate reduction step in H 2 (to reduce cobalt oxides to cobalt) was utilized to synthesize an integrated freestanding catalyst. The fabricated catalyst with effective structural and electronic interaction between the cobalt metal nanoparticles and the N- and F-doped carbon defect sites showed enhanced catalytic properties compared to the benchmark catalysts for ORR and OER (Pt, Ir, and Ru). The ORR potential at the current density of -3 mA cm -2 was 0.81 V RHE and the OER potential at a current density of 10 mA cm -2 was 1.595 V RHE , resulting in a ΔE of only 0.785 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomic layer deposition of quaternary chalcogenides

DOEpatents

Thimsen, Elijah J; Riha, Shannon C; Martinson, Alex B.F.; Elam, Jeffrey W; Pellin, Michael J

2014-06-03

Methods and systems are provided for synthesis and deposition of chalcogenides (including Cu.sub.2ZnSnS.sub.4). Binary compounds, such as metal sulfides, can be deposited by alternating exposures of the substrate to a metal cation precursor and a chalcogen anion precursor with purge steps between.

Processing of catalysts by atomic layer epitaxy: modification of supports

NASA Astrophysics Data System (ADS)

Lindblad, Marina; Haukka, Suvi; Kytökivi, Arla; Lakomaa, Eeva-Liisa; Rautiainen, Aimo; Suntola, Tuomo

1997-11-01

Different supports were modified with titania, zirconia and chromia by the atomic layer epitaxy technique (ALE). In ALE, a metal precursor is bound to the support in saturating gas-solid reactions. Surface oxides are grown by alternating reactions of the metal precursor and an oxidizing agent. Growth mechanisms differ depending on the precursor-support pair and the processing conditions. In this work, the influences of the support, precursor and reaction temperature were investigated by comparing the growth of titania from Ti(OCH(CH 3) 2) 4 on silica and alumina, titania from TiCl 4 and Ti(OCH(CH 3) 2) 4 on silica, and zirconia from ZrCl 4 on silica and alumina. The modification of porous oxides supported on metal substrates (monoliths) was demonstrated for the growth of chromia from Cr(acac) 3.

Synthesis metal nanoparticle

DOEpatents

Bunge, Scott D.; Boyle, Timothy J.

2005-08-16

A method for providing an anhydrous route for the synthesis of amine capped coinage-metal (copper, silver, and gold) nanoparticles (NPs) using the coinage-metal mesityl (mesityl=C.sub.6 H.sub.2 (CH.sub.3).sub.3 -2,4,6) derivatives. In this method, a solution of (Cu(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5, (Ag(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.4, or (Au(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5 is dissolved in a coordinating solvent, such as a primary, secondary, or tertiary amine; primary, secondary, or tertiary phosphine, or alkyl thiol, to produce a mesityl precursor solution. This solution is subsequently injected into an organic solvent that is heated to a temperature greater than approximately 100.degree. C. After washing with an organic solvent, such as an alcohol (including methanol, ethanol, propanol, and higher molecular-weight alcohols), oxide free coinage NP are prepared that could be extracted with a solvent, such as an aromatic solvent (including, for example, toluene, benzene, and pyridine) or an alkane (including, for example, pentane, hexane, and heptane). Characterization by UV-Vis spectroscopy and transmission electron microscopy showed that the NPs were approximately 9.2.+-.2.3 nm in size for Cu.degree., (no surface oxide present), approximately 8.5.+-.1.1 nm Ag.degree. spheres, and approximately 8-80 nm for Au.degree..

Facile synthesis of multi-shell structured binary metal oxide powders with a Ni/Co mole ratio of 1:2 for Li-Ion batteries

NASA Astrophysics Data System (ADS)

Choi, Seung Ho; Park, Sun Kyu; Lee, Jung-Kul; Kang, Yun Chan

2015-06-01

Multi-shell structured binary transition metal oxide powders with a Ni/Co mole ratio of 1:2 are prepared by a simple spray drying process. Precursor powder particles prepared by spray drying from a spray solution of citric acid and ethylene glycol have completely spherical shape, fine size, and a narrow size distribution. The precursor powders turn into multi-shell powders after a post heat-treatment at temperatures between 250 and 800 °C. The multi-shell structured powders are formed by repeated combustion and contraction processes. The multi-shell powders have mixed crystal structures of Ni1-xCo2O4-x and NiO phases regardless of the post-treatment temperature. The reversible capacities of the powders post-treated at 250, 400, 600, and 800 °C after 100 cycles are 584, 913, 808, and 481 mA h g-1, respectively. The low charge transfer resistance and high lithium ion diffusion rate of the multi-shell powders post-treated at 400 °C with optimum grain size result in superior electrochemical properties even at high current densities.

Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures

PubMed Central

Manshina, A. A.; Grachova, E. V.; Povolotskiy, A. V.; Povolotckaia, A. V.; Petrov, Y. V.; Koshevoy, I. O.; Makarova, A. A.; Vyalikh, D. V.; Tunik, S. P.

2015-01-01

In the present work an efficient approach of the controlled formation of hybrid Au–Ag–C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles’ dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

Molecular solution processing of metal chalcogenide thin film solar cells

NASA Astrophysics Data System (ADS)

Yang, Wenbing

The barrier to utilize solar generated electricity mainly comes from their higher cost relative to fossil fuels. However, innovations with new materials and processing techniques can potentially make cost effective photovoltaics. One such strategy is to develop solution processed photovoltaics which avoid the expensive vacuum processing required by traditional solar cells. The dissertation is mainly focused on two absorber material system for thin film solar cells: chalcopyrite CuIn(S,Se)2 (CISS) and kesterite Cu2ZnSn(S,Se) 4 organized in chronological order. Chalcopyrite CISS is a very promising material. It has been demonstrated to achieve the highest efficiency among thin film solar cells. Scaled-up industry production at present has reached the giga-watt per year level. The process however mainly relies on vacuum systems which account for a significant percentage of the manufacturing cost. In the first section of this dissertation, hydrazine based solution processed CISS has been explored. The focus of the research involves the procedures to fabricate devices from solution. The topics covered in Chapter 2 include: precursor solution synthesis with a focus on understanding the solution chemistry, CISS absorber formation from precursor, properties modification toward favorable device performance, and device structure innovation toward tandem device. For photovoltaics to have a significant impact toward meeting energy demands, the annual production capability needs to be on TW-level. On such a level, raw materials supply of rare elements (indium for CIS or tellurium for CdTe) will be the bottleneck limiting the scalability. Replacing indium with zinc and tin, earth abundant kesterite CZTS exhibits great potential to reach the goal of TW-level with no limitations on raw material availability. Chapter 3 shows pioneering work towards solution processing of CZTS film at low temperature. The solution processed devices show performances which rival vacuum-based techniques and is partially attributed to the ease in controlling composition and CZTS phase through this technique. Based on this platform, comprehensive characterization on CZTS devices is carried out including solar cells and transistors. Especially defects properties are exploited in Chapter 4 targeting to identify the limiting factors for further improvement on CZTS solar cells efficiency. Finally, molecular structures and precursor solution stability have been explored, potentially to provide a universal approach to process multinary compounds.

Optimizing the deposition of hydrogen evolution sites on suspended semiconductor particles using on-line photocatalytic reforming of aqueous methanol solutions.

PubMed

Busser, G Wilma; Mei, Bastian; Muhler, Martin

2012-11-01

The deposition of hydrogen evolution sites on photocatalysts is a crucial step in the multistep process of synthesizing a catalyst that is active for overall photocatalytic water splitting. An alternative approach to conventional photodeposition was developed, applying the photocatalytic reforming of aqueous methanol solutions to deposit metal particles on semiconductor materials such as Ga₂O₃ and (Ga₀.₆ Zn₀.₄)(N₀.₆O₀.₄). The method allows optimizing the loading of the co-catalysts based on the stepwise addition of their precursors and the continuous online monitoring of the evolved hydrogen. Moreover, a synergetic effect between different co-catalysts can be directly established. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solution-based synthesis and design of late transition metal chalcogenide materials for oxygen reduction reaction (ORR).

PubMed

Gao, Min-Rui; Jiang, Jun; Yu, Shu-Hong

2012-01-09

Late transition metal chalcogenide (LTMC) nanomaterials have been introduced as a promising Pt-free oxygen reduction reaction (ORR) electrocatalysts because of their low cost, good ORR activity, high methanol tolerance, and facile synthesis. Herein, an overview on the design and synthesis of LTMC nanomaterials by solution-based strategies is presented along with their ORR performances. Current solution-based synthetic approaches towards LTMC nanomaterials include a hydrothermal/solvothermal approach, single-source precursor approach, hot-injection approach, template-directed soft synthesis, and Kirkendall-effect-induced soft synthesis. Although the ORR activity and stability of LTMC nanomaterials are still far from what is needed for practical fuel-cell applications, much enhanced electrocatalytic performance can be expected. Recent advances have emphasized that decorating the surface of the LTMC nanostructures with other functional nanoparticles can lead to much better ORR catalytic activity. It is believed that new synthesis approaches to LTMCs, modification techniques of LTMCs, and LTMCs with desirable morphology, size, composition, and structures are expected to be developed in the future to satisfy the requirements of commercial fuel cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thin, porous metal sheets and methods for making the same

DOEpatents

Liu, Wei; Li, Xiaohong Shari; Canfield, Nathan L.

2015-07-14

Thin, porous metal sheets and methods for forming them are presented to enable a variety of applications and devices. The thin, porous metal sheets are less than or equal to approximately 200 .mu.m thick, have a porosity between 25% and 75% by volume, and have pores with an average diameter less than or equal to approximately 2 .mu.m. The thin, porous metal sheets can be fabricated by preparing a slurry having between 10 and 50 wt % solvent and between 20 and 80 wt % powder of a metal precursor. The average particle size in the metal precursor powder should be between 100 nm and 5 .mu.m.

The chemical deposition of semiconductor thin-films for photovoltaic devices

NASA Astrophysics Data System (ADS)

Breen, Marc Louis

Initially, possible precursors to metal sulfide films formed by metal-organic chemical vapor deposition (MOCVD), the standard commercial technique for manufacturing photovoltaic semiconductors, were synthesized. Triple-junction GaInP 2/GaAs/Ge solar cells, prepared by this method, were studied to understand how chemical properties and material defects can effect the performance of photovoltaic devices. Finally, novel methods for the low-temperature, solution growth of CdS, CdSe, and CuInSe2 photovoltaic materials were targeted which will reduce manufacturing costs and increase the economic feasibility of solar energy conversion. A series of dialkyldithiocarbamate copper, gallium and indium compounds were studied as possible metal sulfide MOCVD precursors. Metal powders were oxidized by dialkylthiurams in 3- or 4-methylpyridine using standard techniques for handling air and moisture-sensitive compounds. Metal chlorides reacted directly with the sodium dialkyldithiocarbamate salts. In these complexes, the metal was found in a roughly octahedral orientation, surrounded by dithiocarbamate ligands and/or solvent molecules. Triple-junction GaInP2/GaAs/Ge cells were composed of thin-films of GaInP2 and GaAs grown monolithically on top of a germanium substrate. Each layer of semiconductor material had a different bandgap and absorbed a different portion of the solar spectrum, thus improving the overall efficiency of the cell. Work focused on dark current-voltage behavior which is known to limit solar cell open-circuit voltage, fill factor, and conversion efficiency. Cells were studied using microscopic and spectroscopic techniques to correlate the effect of physical defects in the materials with poor performance of the devices as evaluated through current vs. voltage measurements. Films of US and CdSe were readily prepared in solution through an "ion-by-ion" deposition of Cd2+ and S2- (or Se 2-) generated from the slow hydrolysis of thiourea (or dimethylthiourea). The bath chemistry was carefully controlled by the adjustment of pH to slow hydrolysis and with chelating agents to sequester the cadmium ions. Triethanolamine and ethylenediamine were both effective chelators with the latter producing thicker, clearer films. Finally, US films were grown over electrodeposited CuInSe2 to form working photovoltaic devices. In summary, contributions were made which (a) advance current methods for manufacturing photovoltaic semiconductors and (b) offer an alternative route to producing new forms of thin-film solar cell devices.

DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

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

Branko N. Popov

2009-03-03

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst showsmore » the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited comparable catalytic activity and selectivity for ORR as the Pt catalyst. A theoretical analysis is made of the four-electron reduction reaction of oxygen to water over the mixed anion and cation (202) surface of pentlandite structure Co9Se8, one of several selenide phases. Reversible potentials for forming adsorbed reaction intermediates in acid are predicted using adsorption energies calculated with the Vienna ab initio simulation program (VASP) and the known bulk solution values together in a linear Gibbs energy relationship. The effect of hydrophobic and structural properties of a single/dual-layer cathode gas diffusion layer on mass transport in PEM fuel cells was studied using an analytical expression. The simulations indicated that liquid water transport at the cathode is controlled by the fraction of hydrophilic surface and the average pore diameter in the cathode gas diffusion layer. The optimized hydrophobicity and pore geometry in a dual-layer cathode GDL leads to an effective water management, and enhances the oxygen diffusion kinetics.« less

DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

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

Branko N. Popov

2009-02-20

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst showsmore » the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited comparable catalytic activity and selectivity for ORR as the Pt catalyst. A theoretical analysis is made of the four-electron reduction reaction of oxygen to water over the mixed anion and cation (202) surface of pentlandite structure Co9Se8, one of several selenide phases. Reversible potentials for forming adsorbed reaction intermediates in acid are predicted using adsorption energies calculated with the Vienna ab initio simulation program (VASP) and the known bulk solution values together in a linear Gibbs energy relationship. The effect of hydrophobic and structural properties of a single/dual-layer cathode gas diffusion layer on mass transport in PEM fuel cells was studied using an analytical expression. The simulations indicated that liquid water transport at the cathode is controlled by the fraction of hydrophilic surface and the average pore diameter in the cathode gas diffusion layer. The optimized hydrophobicity and pore geometry in a dual-layer cathode GDL leads to an effective water management, and enhances the oxygen diffusion kinetics.« less

Non-aqueous solution preparation of doped and undoped lixmnyoz

DOEpatents

Boyle, Timothy J.; Voigt, James A.

1997-01-01

A method for generation of phase-pure doped and undoped Li.sub.x Mn.sub.y O.sub.z precursors. The method of this invention uses organic solutions instead of aqueous solutions or nonsolution ball milling of dry powders to produce phase-pure precursors. These precursors can be used as cathodes for lithium-polymer electrolyte batteries. Dopants may be homogeneously incorporated to alter the characteristics of the powder.

One-pot electrodeposition of cobalt flower-decorated silver nanotrees for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Cho, Yun-Bin; Moon, Sinyoung; Lee, Chongmok; Lee, Youngmi

2017-02-01

In this paper, we demonstrate a simple fabrication of bimetallic silver (Ag) and cobalt (Co) nanostructures (AgCo) with various Ag to Co relative contents via electrochemical co-deposition. A series of AgCo catalysts was electrodeposited on glassy carbon (GC) electrodes at -0.57 V vs. SCE in the deposition solutions, containing Ag precursor, Co precursor, Triton X-100, and 0.3 M KNO3 aqueous solution, with various Ag to Co precursor concentration ratios (1:x, x was varied from 3 to 11). The films, deposited with the total deposition charge of 0.042C, were denoted as Ag1Cox. SEM and TEM analyses showed that Ag1Cox formed a structure consisted of flower-like Co grown on tree-like Ag backbones while it had more Co flowers with a greater x. The ORR activities were examined in 0.1 M NaOH solution with rotating disk electrode (RDE) voltammetry and Ag1Co7 showed the best catalytic activity. The co-deposition mechanism was further investigated by varying the deposition time of Ag1Co7. At the early stage of deposition, Ag-tree branches were formed predominantly, followed by the growth of flower-like Co nanostructures on the Ag nanotrees: More Co flowers were produced on Ag backbones with longer deposition time, being attributed to both a less negative reduction potential of Ag+ to Ag than Co2+ to Co and promoted Co2+ reduction on the initially formed Ag surface. Ag1Co7 electrodeposited for 200 s, consisted of ∼14% Co, showed the greatest ORR catalytic activity which was better or comparable to noble metal Pt.

Fabrication of contacts for silicon solar cells including printing burn through layers

DOEpatents

Ginley, David S; Kaydanova, Tatiana; Miedaner, Alexander; Curtis, Calvin J; Van Hest, Marinus Franciscus Antonius Maria

2014-06-24

A method for fabricating a contact (240) for a solar cell (200). The method includes providing a solar cell substrate (210) with a surface that is covered or includes an antireflective coating (220). For example, the substrate (210) may be positioned adjacent or proximate to an outlet of an inkjet printer (712) or other deposition device. The method continues with forming a burn through layer (230) on the coating (220) by depositing a metal oxide precursor (e.g., using an inkjet or other non-contact printing method to print or apply a volume of liquid or solution containing the precursor). The method includes forming a contact layer (240) comprising silver over or on the burn through layer (230), and then annealing is performed to electrically connect the contact layer (240) to the surface of the solar cell substrate (210) through a portion of the burn through layer (230) and the coating (220).

Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films.

PubMed

Park, Jun-Sik; Kim, Dug-Joong; Chung, Wan-Ho; Lim, Yonghyun; Kim, Hak-Sung; Kim, Young-Beom

2017-09-29

Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite crystalline phases and good ionic conductivity were developed during the second annealing step. These films showed properties comparable to those of thermally annealed films. This process is much faster than conventional annealing processes (e.g. halogen furnaces); a few seconds compared to tens of hours, respectively. The significance of this work includes the treatment of solid-state electrolyte oxides for SOFCs and the demonstration of the feasibility of other oxide components for solid-state energy devices.

Densified waste form and method for forming

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

Garino, Terry J.; Nenoff, Tina M.; Sava Gallis, Dorina Florentina

Materials and methods of making densified waste forms for temperature sensitive waste material, such as nuclear waste, formed with low temperature processing using metallic powder that forms the matrix that encapsulates the temperature sensitive waste material. The densified waste form includes a temperature sensitive waste material in a physically densified matrix, the matrix is a compacted metallic powder. The method for forming the densified waste form includes mixing a metallic powder and a temperature sensitive waste material to form a waste form precursor. The waste form precursor is compacted with sufficient pressure to densify the waste precursor and encapsulate themore » temperature sensitive waste material in a physically densified matrix.« less

All-alkoxide synthesis of strontium-containing metal oxides

DOEpatents

Boyle, Timothy J.

2001-01-01

A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

A high yield reverse micelle synthesis of catalysts and catalyst precursors

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

Linehan, J.C.; Matson, D.W.; Darab, J.G.

1995-04-01

Reverse micelles or water-in-oil microemulsions have been prepared using a mixed AOT/SDS surfactant to increase the stability of the microemulsion and thereby allow a high loading of particle-forming precursors in the aqueous cores. The Modified Reverse Micelles (MRM), as these new binary surfactant microemulsions are called, have proven useful for the laboratory-scale synthesis of nanoscale metals, metal oxides, metal sulfides, and mixed metal materials. The system allows control over the phase and size of the precipitated crystallites and is ideal for producing nanocrystalline powders and suspensions.

Bi-Sr-Ca-Cu-O and Pb-Bi-Sr-Ca-Cu-O superconductor films via an electrodeposition process

NASA Astrophysics Data System (ADS)

Maxfield, M.; Eckhardt, H.; Iqbal, Z.; Reidinger, F.; Baughman, R. H.

1989-05-01

A novel electrochemical process has been developed for the formation of superconducting films. Using this process, superconducting films of Bi2Sr2Ca1Cu2O8 and (Pb,Bi)2Sr2Ca1Cu2O8 have been formed. The process consists of simultaneously depositing the metallic constituents of the superconductor from a single electrolyte, and thermally oxidizing the resulting precursors film to form the superconducting phase. Application of -4 to -5 V vs Ag/Ag(+) to a conductive cathode substrate which is immersed in an electrolyte containing salts of all of the metals reduces the metal cations, causing then to deposit on the cathode as a metallic film precursor. Precursor films having desired stoichiometries were obtained by regulating the electrolyte bath composition.

High-Solids Polyimide Precursor Solutions

NASA Technical Reports Server (NTRS)

Chuang, Chun-Hua (Inventor)

2004-01-01

The invention is a highly concentrated stable solution of polymide precursors (monometers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethylalcohol. the concentrated polyimide precursos solution comparisons effective amounts of at least one aromatic diamine, at least one aromatic dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.

Investigating the synthesis of ligated metal clusters in solution using a flow reactor and electrospray ionization mass spectrometry.

PubMed

Olivares, Astrid; Laskin, Julia; Johnson, Grant E

2014-09-18

The scalable synthesis of ligated subnanometer metal clusters containing an exact number of atoms is of interest due to the highly size-dependent catalytic, electronic, and optical properties of these species. While significant research has been conducted on the batch preparation of clusters through reduction synthesis in solution, the processes of metal complex reduction as well as cluster nucleation, growth, and postreduction etching are still not well understood. Herein, we demonstrate a prototype temperature-controlled flow reactor for qualitatively studying cluster formation in solution at steady-state conditions. Employing this technique, methanol solutions of a chloro(triphenylphosphine)gold precursor, 1,4-bis(diphenylphosphino)butane capping ligand, and borane-tert-butylamine reducing agent were combined in a mixing tee and introduced into a heated capillary with a known length. In this manner, the temperature dependence of the relative abundance of different ionic reactants, intermediates, and products synthesized in real time was characterized qualitatively using online mass spectrometry. A wide distribution of doubly and triply charged cationic gold clusters was observed as well as smaller singly charged organometallic complexes. The results demonstrate that temperature plays a crucial role in determining the relative population of cationic gold clusters and, in general, that higher temperature promotes the formation of doubly charged clusters and singly charged organometallic complexes while reducing the abundance of triply charged species. Moreover, the distribution of clusters observed at elevated temperatures is found to be consistent with that obtained at longer reaction times at room temperature, thereby demonstrating that heating may be used to access cluster distributions characteristic of different stages of batch reduction synthesis in solution.

Bioactive and Porous Metal Coatings for Improved Tissue Regeneration

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

Campbell, A. A.

Our first objective was to develop the SIM process for the deposition of calcium phosphate films. This process is based on the observation that, in nature, living organisms use macromolecules to control the nucleation and growth of mineral phases. These macromolecules act as templates where various charged functional groups, contained within the molecule, can interact with the ions in the surrounding media, thus stimulating crystal nucleation and growth. Rather than using complex proteins or biopolymers, surface modification schemes were developed to place simple functional groups on the underlying substrate using self-assembling monolayers. Once the substrate was chemically modified, it wasmore » then placed into an aqueous solution containing soluble precursors of the desired mineral coating. Solution pH, ionic concentration and temperature is maintained in a regime where the solution is supersaturated with respect to the desired mineral phase, thereby creating the driving force for nucleation and growth.« less

Preparation and characterization of silver nanoparticles homogenous thin films

NASA Astrophysics Data System (ADS)

Hegazy, Maroof A.; Borham, E.

2018-06-01

The wet chemical method by metal salt reduction has been widely used to synthesize nanoparticles. Accordingly the silver nitrate used as silver precursor and sodium borohydrate as reduction agent. The silver nanoparticles were characterized by different characterization techniques including UV-VIS spectrometry, Transmission electron microscope (TEM), and Zeta potential technique. Thin films of the colloidal solution were fabricated using direct precipitation technique on ITO glass, silicon substrate and commercial glass substrate and characterized by imaging technique. The absorption peak of the silver nanoparticles colloidal solution was around 400 nm. The TEM images indicate that the silver nanoparticles had spherical shape and their sizes were from 10 to 17 nm. The particle size of the silver nanoparticles was confirmed by Zeta potential technique. The imaging technique indicated that the homogeneous distribution of the colloidal silver solution thin film on the silicon substrate was stronger than the ITO glass and inhomogeneous film was emerged on the commercial glass.

Thin-film composite materials as a dielectric layer for flexible metal-insulator-metal capacitors.

PubMed

Tiwari, Jitendra N; Meena, Jagan Singh; Wu, Chung-Shu; Tiwari, Rajanish N; Chu, Min-Ching; Chang, Feng-Chih; Ko, Fu-Hsiang

2010-09-24

A new organic-organic nanoscale composite thin-film (NCTF) dielectric has been synthesized by solution deposition of 1-bromoadamantane and triblock copolymer (Pluronic P123, BASF, EO20-PO70-EO20), in which the precursor solution has been achieved with organic additives. We have used a sol-gel process to make a metal-insulator-metal capacitor (MIM) comprising a nanoscale (10 nm-thick) thin-film on a flexible polyimide (PI) substrate at room temperature. Scanning electron microscope and atomic force microscope revealed that the deposited NCTFs were crack-free, uniform, highly resistant to moisture absorption, and well adhered on the Au-Cr/PI. The electrical properties of 1-bromoadamantane-P123 NCTF were characterized by dielectric constant, capacitance, and leakage current measurements. The 1-bromoadamantane-P123 NCTF on the PI substrate showed a low leakage current density of 5.5 x 10(-11) A cm(-2) and good capacitance of 2.4 fF at 1 MHz. In addition, the calculated dielectric constant of 1-bromoadamantane-P123 NCTF was 1.9, making them suitable candidates for use in future flexible electronic devices as a stable intermetal dielectric. The electrical insulating properties of 1-bromoadamantane-P123 NCTF have been improved due to the optimized dipole moments of the van der Waals interactions.

Experimental characterization and modeling for the growth rate of oxide coatings from liquid solutions of metalorganic precursors by ultrasonic pulsed injection in a cold-wall low-pressure reactor

NASA Astrophysics Data System (ADS)

Krumdieck, Susan Pran

Several years ago, a method for depositing ceramic coatings called the Pulsed-MOCVD system was developed by the Raj group at Cornell University in association with Dr. Harvey Berger and Sono-Tek Corporation. The process was used to produce epitaxial thin films of TiO2 on sapphire substrates under conditions of low pressure, relatively high temperature, and very low growth rate. The system came to CU-Boulder when Professor Raj moved here in 1997. It is quite a simple technique and has several advantages over typical CVD systems. The purpose of this dissertation is two-fold; (1) understand the chemical processes, thermodynamics, and kinetics of the Pulsed-MOCVD technique, and (2) determine the possible applications by studying the film structure and morphology over the entire range of deposition conditions. Polycrystalline coatings of ceramic materials were deposited on nickel in the low-pressure, cold-wall reactor from metalorganic precursors, titanium isopropoxide, and a mixture of zirconium isopropoxide and yttria isopropoxide. The process utilized pulsed liquid injection of a dilute precursor solution with atomization by ultrasonic nozzle. Thin films (less than 1mum) with fine-grained microstructure and thick coatings (up to 1mum) with columnar-microstructure were deposited on heated metal substrates by thermal decomposition of a single liquid precursor. The influence of each of the primary deposition parameters, substrate temperature, total flow rate, and precursor concentration on growth rate, conversion efficiency and morphology were investigated. The operating conditions were determined for kinetic, mass transfer, and evaporation process control regimes. Kinetic controlled deposition was found to produce equiaxed morphology while mass transfer controlled deposition produced columnar morphology. A kinetic model of the deposition process was developed and compared to data for deposition of TiO2 from Ti(OC3H7) 4 precursor. The results demonstrate that growth rate and morphology over the range of process operating conditions would make the Pulsed-MOCVD system suitable for application of thermal barrier coatings, electrical insulating layers, corrosion protection coatings, and the electrolyte layers in solid oxide fuel cells.

Sol-gel type synthesis of Bi.sub.2 (Sr,Ta.sub.2)O.sub.9 using an acetate based system

DOEpatents

Boyle, Timothy J.

1997-01-01

A method of forming a layered-perovskite bismuth-strontium-tantalum oxide (SBT) ferroelectric material is performed by dissolving a bismuth compound in a first solvent to form a first solution, mixing a strontium compound and a tantalum compound to form a binary mixture, dissolving the binary mixture in a second solvent to form a second solution, mixing the first solution with the second solution to form a SBT precursor solution, evaporating the first and second solvents to form a SBT precursor material and subsequently sintering said SBT precursor material in the presence of oxygen.

Sol-gel type synthesis of Bi{sub 2}(Sr,Ta{sub 2})O{sub 9} using an acetate based system

DOEpatents

Boyle, T.J.

1997-11-04

A method of forming a layered-perovskite bismuth-strontium-tantalum oxide (SBT) ferroelectric material is performed by dissolving a bismuth compound in a first solvent to form a first solution, mixing a strontium compound and a tantalum compound to form a binary mixture, dissolving the binary mixture in a second solvent to form a second solution, mixing the first solution with the second solution to form a SBT precursor solution, evaporating the first and second solvents to form a SBT precursor material and subsequently sintering said SBT precursor material in the presence of oxygen. 6 figs.

Metallization of DNA hydrogel: application of soft matter host for preparation and nesting of catalytic nanoparticles

NASA Astrophysics Data System (ADS)

Zinchenko, Anatoly; Che, Yuxin; Taniguchi, Shota; Lopatina, Larisa I.; G. Sergeyev, Vladimir; Murata, Shizuaki

2016-07-01

Nanoparticles (NPs) of Au, Ag, Pt, Pd, Cu and Ni of 2-3 nm average-size and narrow-size distributions were synthesized in DNA cross-linked hydrogels by reducing corresponding metal precursors by sodium borohydride. DNA hydrogel plays a role of a universal reactor in which the reduction of metal precursor results in the formation of 2-3 nm ultrafine metal NPs regardless of metal used. Hydrogels metallized with various metals showed catalytic activity in the reduction of nitroaromatic compounds, and the catalytic activity of metallized hydrogels changed as follows: Pd > Ag ≈ Au ≈ Cu > Ni > Pt. DNA hydrogel-based "soft catalysts" elaborated in this study are promising for green organic synthesis in aqueous media as well as for biomedical in vivo applications.

A facile synthesis of α-MnO2 used as a supercapacitor electrode material: The influence of the Mn-based precursor solutions on the electrochemical performance

NASA Astrophysics Data System (ADS)

Li, Wenyao; Xu, Jiani; Pan, Yishuang; An, Lei; Xu, Kaibing; Wang, Guangjin; Yu, Zhishui; Yu, Li; Hu, Junqing

2015-12-01

Three types of α-MnO2 nanomaterials are synthesized in different Mn-based precursor solutions by using a facile electrochemical deposition at the same depositional condition. The relationships between the precursor solutions and corresponding MnO2 nanomaterials' morphology as well as the electrochemical performance have been studied. As an electrode, electrochemical measurements show that the MnO2 deposited in MnCl2 precursor solution (MnO2-P3) exhibits an enhanced specific capacitance (318.9 F g-1 at 2 mV s-1). Moreover, this electrode demonstrates a good rate capability with 44% retention, which is higher than the MnO2-P1 deposited with Mn(CH3COOH)2 solution and the MnO2-P2 deposited with Mn(NO3)2 precursor solution. Besides, the specific capacitance of the MnO2-P3 electrode nearly has 98.2% retention after 2000 cycles, showing good long-term cycle stability. These findings show that the MnO2-P3 is a promising electrode material for supercapacitors.

Dehalogenation and coupling of a polycyclic hydrocarbon on an atomically thin insulator.

PubMed

Dienel, Thomas; Gómez-Díaz, Jaime; Seitsonen, Ari P; Widmer, Roland; Iannuzzi, Marcella; Radican, Kevin; Sachdev, Hermann; Müllen, Klaus; Hutter, Jürg; Gröning, Oliver

2014-07-22

Catalytic activity is of pivotal relevance in enabling efficient and selective synthesis processes. Recently, covalent coupling reactions catalyzed by solid metal surfaces opened the rapidly evolving field of on-surface chemical synthesis. Tailored molecular precursors in conjunction with the catalytic activity of the metal substrate allow the synthesis of novel, technologically highly relevant materials such as atomically precise graphene nanoribbons. However, the reaction path on the metal substrate remains unclear in most cases, and the intriguing question is how a specific atomic configuration between reactant and catalyst controls the reaction processes. In this study, we cover the metal substrate with a monolayer of hexagonal boron nitride (h-BN), reducing the reactivity of the metal, and gain unique access to atomistic details during the activation of a polyphenylene precursor by sequential dehalogenation and the subsequent coupling to extended oligomers. We use scanning tunneling microscopy and density functional theory to reveal a reaction site anisotropy, induced by the registry mismatch between the precursor and the nanostructured h-BN monolayer.

Dialkyldiselenophosphinato-metal complexes - a new class of single source precursors for deposition of metal selenide thin films and nanoparticles

NASA Astrophysics Data System (ADS)

Malik, Sajid N.; Akhtar, Masood; Revaprasadu, Neerish; Qadeer Malik, Abdul; Azad Malik, Mohammad

2014-08-01

We report here a new synthetic approach for convenient and high yield synthesis of dialkyldiselenophosphinato-metal complexes. A number of diphenyldiselenophosphinato-metal as well as diisopropyldiselenophosphinato-metal complexes have been synthesized and used as precursors for deposition of semiconductor thin films and nanoparticles. Cubic Cu2-xSe and tetragonal CuInSe2 thin films have been deposited by AACVD at 400, 450 and 500 °C whereas cubic PbSe and tetragonal CZTSe thin films have been deposited through doctor blade method followed by annealing. SEM investigations revealed significant differences in morphology of the films deposited at different temperatures. Preparation of Cu2-xSe and In2Se3 nanoparticles using diisopropyldiselenophosphinato-metal precursors has been carried out by colloidal method in HDA/TOP system. Cu2-xSe nanoparticles (grown at 250 °C) and In2Se3 nanoparticles (grown at 270 °C) have a mean diameter of 5.0 ± 1.2 nm and 13 ± 2.5 nm, respectively.

Controllable lasing performance in solution-processed organic-inorganic hybrid perovskites.

PubMed

Kao, Tsung Sheng; Chou, Yu-Hsun; Hong, Kuo-Bin; Huang, Jiong-Fu; Chou, Chun-Hsien; Kuo, Hao-Chung; Chen, Fang-Chung; Lu, Tien-Chang

2016-11-03

Solution-processed organic-inorganic perovskites are fascinating due to their remarkable photo-conversion efficiency and great potential in the cost-effective, versatile and large-scale manufacturing of optoelectronic devices. In this paper, we demonstrate that the perovskite nanocrystal sizes can be simply controlled by manipulating the precursor solution concentrations in a two-step sequential deposition process, thus achieving the feasible tunability of excitonic properties and lasing performance in hybrid metal-halide perovskites. The lasing threshold is at around 230 μJ cm -2 in this solution-processed organic-inorganic lead-halide material, which is comparable to the colloidal quantum dot lasers. The efficient stimulated emission originates from the multiple random scattering provided by the micro-meter scale rugged morphology and polycrystalline grain boundaries. Thus the excitonic properties in perovskites exhibit high correlation with the formed morphology of the perovskite nanocrystals. Compared to the conventional lasers normally serving as a coherent light source, the perovskite random lasers are promising in making low-cost thin-film lasing devices for flexible and speckle-free imaging applications.

New class of single-source precursors for the synthesis of main group-transition metal oxides: heterobimetallic Pb-Mn beta-diketonates.

PubMed

Zhang, Haitao; Yang, Jen-Hsien; Shpanchenko, Roman V; Abakumov, Artem M; Hadermann, Joke; Clérac, Rodolphe; Dikarev, Evgeny V

2009-09-07

Heterometallic lead-manganese beta-diketonates have been isolated in pure form by several synthetic methods that include solid-state and solution techniques. Two compounds with different Pb/Mn ratios, PbMn(2)(hfac)(6) (1) and PbMn(hfac)(4) (2) (hfac = hexafluoroacetylacetonate), can be obtained in quantitative yield by using different starting materials. Single crystal X-ray investigation revealed that the solid-state structure of 1 contains trinuclear molecules in which lead metal center is sandwiched between two [Mn(hfac)(3)] units, while 2 consists of infinite chains of alternating [Pb(hfac)(2)] and [Mn(hfac)(2)] fragments. The heterometallic structures are held together by strong Lewis acid-base interactions between metal atoms and diketonate ligands acting in chelating-bridging fashion. Spectroscopic investigation confirmed the retention of heterometallic structures in solutions of non-coordinating solvents as well as upon sublimation-deposition procedure. Thermal decomposition of heterometallic diketonates has been systematically investigated in a wide range of temperatures and annealing times. For the first time, it has been shown that thermal decomposition of heterometallic diketonates results in mixed-metal oxides, while both the structure of precursors and the thermolysis conditions have a significant influence on the nature of the resulting oxides. Five different Pb-Mn oxides have been detected by X-ray powder diffraction when studying the decomposition of 1 and 2 in the temperature range 500-800 degrees C. The phase that has been previously reported as "Pb(0.43)MnO(2.18)" was synthesized in the pure form by decomposition of 1, and crystallographically characterized. The orthorhombic unit cell parameters of this oxide, obtained by electron diffraction technique, have been subsequently refined using X-ray powder diffraction data. Besides that, a previously unknown lead-manganese oxide has been obtained at low temperature decomposition and short annealing times. The parameters of its monoclinically distorted unit cell have been determined. The EDX analysis revealed that this compound has a Pb/Mn ratio close to 1:4 and contains no appreciable amount of fluorine.

Superconductive wire

DOEpatents

Korzekwa, David A.; Bingert, John F.; Peterson, Dean E.; Sheinberg, Haskell

1995-01-01

A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity.

Superconductive wire

DOEpatents

Korzekwa, D.A.; Bingert, J.F.; Peterson, D.E.; Sheinberg, H.

1995-07-18

A superconductive article is made by inserting a rigid mandrel into an internal cavity of a first metallic tube, said tube having an interior surface and an exterior surface, said interior surface defining the interior cavity, forming a layer of a superconductive material or superconductive precursor upon the exterior surface of said first metallic tube, machining the layer of superconductive material or superconductive precursor to a predetermined diameter to form an intermediate article configured for insertion into a second metallic tube having an interior diameter corresponding to the predetermined diameter, inserting the machined intermediate article into a second metallic tube having an internal diameter corresponding to the predetermined diameter of the intermediate article to form a composite intermediate article, reducing or ironing the composite intermediate article to a predetermined cross-sectional diameter, and sintering the reduced or ironed composite intermediate article at temperatures and for time sufficient for the superconductive material or superconductive precursor to exhibit superconductivity. 2 figs.

Carbothermal shock synthesis of high-entropy-alloy nanoparticles

NASA Astrophysics Data System (ADS)

Yao, Yonggang; Huang, Zhennan; Xie, Pengfei; Lacey, Steven D.; Jacob, Rohit Jiji; Xie, Hua; Chen, Fengjuan; Nie, Anmin; Pu, Tiancheng; Rehwoldt, Miles; Yu, Daiwei; Zachariah, Michael R.; Wang, Chao; Shahbazian-Yassar, Reza; Li, Ju; Hu, Liangbing

2018-03-01

The controllable incorporation of multiple immiscible elements into a single nanoparticle merits untold scientific and technological potential, yet remains a challenge using conventional synthetic techniques. We present a general route for alloying up to eight dissimilar elements into single-phase solid-solution nanoparticles, referred to as high-entropy-alloy nanoparticles (HEA-NPs), by thermally shocking precursor metal salt mixtures loaded onto carbon supports [temperature ~2000 kelvin (K), 55-millisecond duration, rate of ~105 K per second]. We synthesized a wide range of multicomponent nanoparticles with a desired chemistry (composition), size, and phase (solid solution, phase-separated) by controlling the carbothermal shock (CTS) parameters (substrate, temperature, shock duration, and heating/cooling rate). To prove utility, we synthesized quinary HEA-NPs as ammonia oxidation catalysts with ~100% conversion and >99% nitrogen oxide selectivity over prolonged operations.

Sorption studies of nickel ions onto activated carbon

NASA Astrophysics Data System (ADS)

Joshi, Parth; Vyas, Meet; Patel, Chirag

2018-05-01

Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. The use of low-cost activated carbon derived from azadirachta indica, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing nickel ions from wastewater. The temperature variation study showed that the nickel ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the pH of the nickel ion solutions. Therefore, this study revealed that azadirachta indica can serve as a good source of activated carbon with multiple and simultaneous metal ions removing potentials and may serve as a better replacement for commercial activated carbons in applications that warrant their use.

Amorphous Mixed-Metal Oxide Thin Films from Aqueous Solution Precursors with Near-Atomic Smoothness.

PubMed

Kast, Matthew G; Cochran, Elizabeth A; Enman, Lisa J; Mitchson, Gavin; Ditto, Jeffrey; Siefe, Chris; Plassmeyer, Paul N; Greenaway, Ann L; Johnson, David C; Page, Catherine J; Boettcher, Shannon W

2016-12-28

Thin films with tunable and homogeneous composition are required for many applications. We report the synthesis and characterization of a new class of compositionally homogeneous thin films that are amorphous solid solutions of Al 2 O 3 and transition metal oxides (TMO x ) including VO x , CrO x , MnO x , Fe 2 O 3 , CoO x , NiO, CuO x , and ZnO. The synthesis is enabled by the rapid decomposition of molecular transition-metal nitrates TM(NO 3 ) x at low temperature along with precondensed oligomeric Al(OH) x (NO 3 ) 3-x cluster species, both of which can be processed from aq solution. The films are dense, ultrasmooth (R rms < 1 nm, near 0.1 nm in many cases), and atomically mixed amorphous metal-oxide alloys over a large composition range. We assess the chemical principles that favor the formation of amorphous homogeneous films over rougher phase-segregated nanocrystalline films. The synthesis is easily extended to other compositions of transition and main-group metal oxides. To demonstrate versatility, we synthesized amorphous V 0.1 Cr 0.1 Mn 0.1 Fe 0.1 Zn 0.1 Al 0.5 O x and V 0.2 Cr 0.2 Fe 0.2 Al 0.4 O x with R rms ≈ 0.1 nm and uniform composition. The combination of ideal physical properties (dense, smooth, uniform) and broad composition tunability provides a platform for film synthesis that can be used to study fundamental phenomena when the effects of transition metal cation identity, solid-state concentration of d-electrons or d-states, and/or crystallinity need to be controlled. The new platform has broad potential use in controlling interfacial phenomena such as electron transfer in solar-cell contacts or surface reactivity in heterogeneous catalysis.

Method of fabricating a homogeneous wire of inter-metallic alloy

DOEpatents

Ohriner, Evan Keith; Blue, Craig Alan

2001-01-01

A method for fabricating a homogeneous wire of inter-metallic alloy comprising the steps of providing a base-metal wire bundle comprising a metal, an alloy or a combination thereof; working the wire bundle through at least one die to obtain a desired dimension and to form a precursor wire; and, controllably heating the precursor wire such that a portion of the wire will become liquid while simultaneously maintaining its desired shape, whereby substantial homogenization of the wire occurs in the liquid state and additional homogenization occurs in the solid state resulting in a homogenous alloy product.

Hard metal composition

DOEpatents

Sheinberg, H.

1983-07-26

A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 wt % boron carbide and the remainder a metal mixture comprising from 70 to 90% tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 and 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

Hard metal composition

DOEpatents

Sheinberg, Haskell

1986-01-01

A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

Synthesis and characterization of WO3 nanowires and metal nanoparticle-WO3 nanowire composites

NASA Astrophysics Data System (ADS)

Szabó, Mária; Pusztai, Péter; Leino, Anne-Riikka; Kordás, Krisztián; Kónya, Zoltán; Kukovecz, Ákos

2013-07-01

Tungsten-trioxide nanowire bundles were prepared using a simple hydrothermal method. Sodium-tungstate was used as precursor and sodium-sulfate as structure directing agent. All the reflections of the X-ray diffractogram of the synthesized wires belong to the hexagonal phase of the tungsten trioxide. The nanowires were successfully decorated with metal nanoparticles by wet impregnation. The TEM investigation showed that using different metal precursors resulted in different particle sizes and coverage on the surface.

Non-aqueous solution preparation of doped and undoped Li{sub x}Mn{sub y}O{sub z}

DOEpatents

Boyle, T.J.; Voigt, J.A.

1997-05-20

A method is described for generation of phase-pure doped and undoped Li{sub x}Mn{sub y}O{sub z} precursors. The method of this invention uses organic solutions instead of aqueous solutions or nonsolution ball milling of dry powders to produce phase-pure precursors. These precursors can be used as cathodes for lithium-polymer electrolyte batteries. Dopants may be homogeneously incorporated to alter the characteristics of the powder. 1 fig.

Benzoyl Halides as Alternative Precursors for the Colloidal Synthesis of Lead-Based Halide Perovskite Nanocrystals

PubMed Central

2018-01-01

We propose here a new colloidal approach for the synthesis of both all-inorganic and hybrid organic–inorganic lead halide perovskite nanocrystals (NCs). The main limitation of the protocols that are currently in use, such as the hot injection and the ligand-assisted reprecipitation routes, is that they employ PbX2 (X = Cl, Br, or I) salts as both lead and halide precursors. This imposes restrictions on being able to precisely tune the amount of reaction species and, consequently, on being able to regulate the composition of the final NCs. In order to overcome this issue, we show here that benzoyl halides can be efficiently used as halide sources to be injected in a solution of metal cations (mainly in the form of metal carboxylates) for the synthesis of APbX3 NCs (in which A = Cs+, CH3NH3+, or CH(NH2)2+). In this way, it is possible to independently tune the amount of both cations and halide precursors in the synthesis. The APbX3 NCs that were prepared with our protocol show excellent optical properties, such as high photoluminescence quantum yields, low amplified spontaneous emission thresholds, and enhanced stability in air. It is noteworthy that CsPbI3 NCs, which crystallize in the cubic α phase, are stable in air for weeks without any postsynthesis treatment. The improved properties of our CsPbX3 perovskite NCs can be ascribed to the formation of lead halide terminated surfaces, in which Cs cations are replaced by alkylammonium ions. PMID:29378131

Benzoyl Halides as Alternative Precursors for the Colloidal Synthesis of Lead-Based Halide Perovskite Nanocrystals.

PubMed

Imran, Muhammad; Caligiuri, Vincenzo; Wang, Mengjiao; Goldoni, Luca; Prato, Mirko; Krahne, Roman; De Trizio, Luca; Manna, Liberato

2018-02-21

We propose here a new colloidal approach for the synthesis of both all-inorganic and hybrid organic-inorganic lead halide perovskite nanocrystals (NCs). The main limitation of the protocols that are currently in use, such as the hot injection and the ligand-assisted reprecipitation routes, is that they employ PbX 2 (X = Cl, Br, or I) salts as both lead and halide precursors. This imposes restrictions on being able to precisely tune the amount of reaction species and, consequently, on being able to regulate the composition of the final NCs. In order to overcome this issue, we show here that benzoyl halides can be efficiently used as halide sources to be injected in a solution of metal cations (mainly in the form of metal carboxylates) for the synthesis of APbX 3 NCs (in which A = Cs + , CH 3 NH 3 + , or CH(NH 2 ) 2 + ). In this way, it is possible to independently tune the amount of both cations and halide precursors in the synthesis. The APbX 3 NCs that were prepared with our protocol show excellent optical properties, such as high photoluminescence quantum yields, low amplified spontaneous emission thresholds, and enhanced stability in air. It is noteworthy that CsPbI 3 NCs, which crystallize in the cubic α phase, are stable in air for weeks without any postsynthesis treatment. The improved properties of our CsPbX 3 perovskite NCs can be ascribed to the formation of lead halide terminated surfaces, in which Cs cations are replaced by alkylammonium ions.

Microcellular carbon foam and method

DOEpatents

Simandl, R.F.; Brown, J.D.

1993-12-07

A microcellular carbon foam is characterized by a density in the range of about 30 to 1000 mg/cm[sup 3], substantially uniform distribution of cell sizes of diameters less than 100 [mu]m with a majority of the cells being of a diameter of less than about 10 [mu]m, well interconnected strut morphology providing open porosity, and an expanded d(002) X-ray turbostatic spacing greater than 3.50 angstroms. The precursor for the carbon foam is prepared by the phase inversion of polyacrylonitrile in a solution consisting essentially of at least one alkali metal halide and a phase inversion solvent for the polyacrylonitrile.

Microcellular carbon foam and method

DOEpatents

Simandl, Ronald F.; Brown, John D.

1994-01-01

A microcellular carbon foam characterized by a density in the range of about 30 to 1000 mg/cm.sup.3, substantially uniform distribution of cell sizes of diameters less than 100 .mu.m with a majority of the cells being of a diameter of less than about 10 .mu.m, well interconnected strut morphology providing open porosity, and an expanded d(002) X-ray turbostatic spacing greater than 3.50 angstroms. The precursor for the carbon foam is prepared by the phase inversion of polyacrylonitrile in a solution consisting essentially of at least one alkali metal halide and a phase inversion solvent for the polyacrylonitrile.

Microcellular carbon foam and method

DOEpatents

Simandl, Ronald F.; Brown, John D.

1993-01-01

A microcellular carbon foam characterized by a density in the range of about 30 to 1000 mg/cm.sup.3, substantially uniform distribution of cell sizes of diameters less than 100 .mu.m with a majority of the cells being of a diameter of less than about 10 .mu.m, well interconnected strut morphology providing open porosity, and an expanded d(002) X-ray turbostatic spacing greater than 3.50 angstroms. The precursor for the carbon foam is prepared by the phase inversion of polyacrylonitrile in a solution consisting essentially of at least one alkali metal halide and a phase inversion solvent for the polyacrylonitrile.

Process for forming a metal compound coating on a substrate

DOEpatents

Sharp, D.J.; Vernon, M.E.; Wright, S.A.

1988-06-29

A method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon.

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring

NASA Astrophysics Data System (ADS)

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Leandro, Luana Di; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-01

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials.Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08632a

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties.

PubMed

Thompson, David; Kranbuehl, David; Espuche, Eliane

2016-10-18

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors.

CVD method for forming B.sub.i -containing oxide superconducting films

DOEpatents

Wessels, Bruce W.; Marks, Tobin J.; Richeson, Darrin S.; Tonge, Lauren M.; Zhang, Jiming

1994-01-01

Films of high T.sub.c Bi-Sr-Ca-Cu-O superconductor have been prepared by MOCVD using volatile metal organic precursors and water vapor. The metal organic precursors are volatized along with a bismuth source, such as Bi(C.sub.6 H.sub.5).sub.3, deposited on a heated substrate to form a film, and annealed.

Improved liquid chromatography-MS/MS of heparan sulfate oligosaccharides via chip-based pulsed makeup flow.

PubMed

Huang, Yu; Shi, Xiaofeng; Yu, Xiang; Leymarie, Nancy; Staples, Gregory O; Yin, Hongfeng; Killeen, Kevin; Zaia, Joseph

2011-11-01

Microfluidic chip-based hydrophilic interaction chromatography (HILIC) is a useful separation system for liquid chromatography-mass spectrometry (LC-MS) in compositional profiling of heparan sulfate (HS) oligosaccharides; however, ions observed using HILIC LC-MS are low in charge. Tandem MS of HS oligosaccharide ions with low charge results in undesirable losses of SO(3) from precursor ions during collision induced dissociation. One solution is to add metal cations to stabilize sulfate groups. Another is to add a nonvolatile, polar compound such as sulfolane, a molecule known to supercharge proteins, to produce a similar effect for oligosaccharides. We demonstrate use of a novel pulsed makeup flow (MUF) HPLC-chip. The chip enables controlled application of additives during specified chromatographic time windows and thus minimizes the extent to which nonvolatile additives build up in the ion source. The pulsed MUF system was applied to LC-MS/MS of HS oligosaccharides. Metal cations and sulfolane were tested as additives. The most promising results were obtained for sulfolane, for which supercharging of the oligosaccharide ions increased their signal strengths relative to controls. Tandem MS of these supercharged precursor ions showed decreased abundances of product ions from sulfate losses yet more abundant product ions from backbone cleavages.

Surface-Embedded Stretchable Electrodes by Direct Printing and their Uses to Fabricate Ultrathin Vibration Sensors and Circuits for 3D Structures.

PubMed

Song, Jun Hyuk; Kim, Young-Tae; Cho, Sunghwan; Song, Woo-Jin; Moon, Sungmin; Park, Chan-Gyung; Park, Soojin; Myoung, Jae Min; Jeong, Unyong

2017-11-01

Printing is one of the easy and quick ways to make a stretchable wearable electronics. Conventional printing methods deposit conductive materials "on" or "inside" a rubber substrate. The conductors made by such printing methods cannot be used as device electrodes because of the large surface topology, poor stretchability, or weak adhesion between the substrate and the conducting material. Here, a method is presented by which conductive materials are printed in the way of being surface-embedded in the rubber substrate; hence, the conductors can be widely used as device electrodes and circuits. The printing process involves a direct printing of a metal precursor solution in a block-copolymer rubber substrate and chemical reduction of the precursor into metal nanoparticles. The electrical conductivity and sensitivity to the mechanical deformation can be controlled by adjusting the number of printing operations. The fabrication of highly sensitive vibration sensors is thus presented, which can detect weak pulses and sound waves. In addition, this work takes advantage of the viscoelasticity of the composite conductor to fabricate highly conductive stretchable circuits for complicated 3D structures. The printed electrodes are also used to fabricate a stretchable electrochemiluminescence display. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Assembled Fe-N-Doped Carbon Nanotube Aerogels with Single-Atom Catalyst Feature as High-Efficiency Oxygen Reduction Electrocatalysts

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

Zhu, Chengzhou; Fu, Shaofang; Song, Junhua

Finely controlled synthesis of high active and robust non-precious metal catalysts with excellent electrocatalytic efficiency towards oxygen reduction reaction is extremely vital for successful implementation of fuel cells and metal batteries. Unprecedented oxygen reduction reaction electrocatalytic performances and the diversified synthetic procedure in term of favorable structure/morphology characteristics make transition metals-derived M–N–C (M=Fe, Co) structures the most promising nanocatalysts. Herein, using the nitrogen-containing small molecular and inorganic salt as precursors and ultrathin tellurium nanowires as templates, we successfully synthesized a series of well-defined M-N-doped hollow carbon nanowire aerogels through one step hydrothermal route and subsequent facile annealing treatment. Taking advantagemore » of the porous nanostructures, one-dimensional building block as well as homogeneity of active sites, the resultant Fe-N-doped carbon hollow nanowire aerogels exhibited excellent ORR electrocatalytic performance even better than commercial Pt/C in alkaline solution, holding great potential in fuel cell applications.« less

Layer-by-Layer Molecular Assemblies for Dye-Sensitized Photoelectrosynthesis Cells Prepared by Atomic Layer Deposition

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

Wang, Degao; Sheridan, Matthew V.; Shan, Bing

2017-08-30

In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of catalyst and chromophore play important roles. Here we introduce a new, robust, Atomic Layer Deposition (ALD) procedure for the preparation of assemblies on wide bandgap semiconductors. In the procedure, phosphonated metal complex precursors react with metal ion bridging to an external chromophore or catalyst to give assemblies bridged by Al(III), Sn(IV), Ti(IV), or Zr(IV) metal oxide units as bridges. The procedure has been extended to chromophore-catalyst assemblies for water oxidation catalysis. A SnO2 bridged assembly on SnO2/TiO2 core/shell electrodes undergoes water splitting with an incident photon conversion efficiency (IPCE)more » of 17.1% at 440 nm. Reduction of water at a Ni(II)-based catalyst on NiO films has been shown to give H2. Compared to conventional solution-based procedures, the ALD approach offers significant advantages in scope and flexibility for the preparation of stable surface structures.« less

Real-Time Observation of Atomic Layer Deposition Inhibition: Metal Oxide Growth on Self-Assembled Alkanethiols

DOE PAGES

Avila, Jason R.; DeMarco, Erica J.; Emery, Jonathan D.; ...

2014-07-21

Through in-situ quartz crystal microbalance (QCM) monitoring we resolve the growth of a self-assembled monolayer (SAM) and subsequent metal oxide deposition with high resolution. Here, we introduce the fitting of mass deposited during each atomic layer deposition (ALD) cycle to an analytical island-growth model that enables quantification of growth inhibition, nucleation density, and the uninhibited ALD growth rate. A long-chain alkanethiol was self-assembled as a monolayer on gold-coated quartz crystals in order to investigate its effectiveness as a barrier to ALD. Compared to solution-loading, vapor-loading is observed to produce a SAM with equal or greater inhibition-ability in minutes vs. days.more » The metal oxide growth temperature and the choice of precursor also significantly affect the nucleation density, which ranges from 0.001 to 1 sites/nm 2. Finally, we observe a minimum 100 cycle inhibition of an oxide ALD process, ZnO, under moderately optimized conditions.« less

Ce, Ti modified MCM-48 mesoporous photocatalysts: Effect of the synthesis route on support and metal ion properties

NASA Astrophysics Data System (ADS)

Mureseanu, Mihaela; Filip, Mihaela; Somacescu, Simona; Baran, Adriana; Carja, Gabriela; Parvulescu, Viorica

2018-06-01

New Ti-MCM-48 and CeTi-MCM-48 photocatalysts were obtained by impregnation of the MCM-48 silica support synthesized by a hydrothermal process with aqueous solution of Ti and Ce precursors. The immobilization of metal cations presented a low effect on the porosity, morphology and structure of MCM-48 mesoporous silica support as was evidenced by N2 adsorption-desorption, X-ray diffraction, SEM and TEM electron microscopy. EDAX analysis and X-ray photoelectron microscopy (XPS) indicated that titanium cations were present on the mesoporous silica surface only as Ti4+ species and the effect of ceria on titanium speciation was different, compared to the CeTi-MCM-48 sample, previously obtained by direct synthesis. The photocatalytic properties of mono- and bimetallic catalysts were evaluated in degradation of phenol from water and correlated with the active metallic species concentration, distribution, speciation and their interaction with the support or each other. An advanced oxidation mechanism for phenol degradation by radical species was proposed.

Selective epitaxial growth of Ge1-xSnx on Si by using metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Washizu, Tomoya; Ike, Shinichi; Inuzuka, Yuki; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

2017-06-01

Selective epitaxial growth of Ge and Ge1-xSnx layers on Si substrates was performed by using metal-organic chemical vapor deposition (MOCVD) with precursors of tertiary-butyl-germane (t-BGe) and tri-butyl-vinyl-tin (TBVSn). We investigated the effects of growth temperature and total pressure during growth on the selectivity and the crystallinity of the Ge and Ge1-xSnx epitaxial layers. Under low total pressure growth conditions, the dominant mechanism of the selective growth of Ge epitaxial layers is the desorption of the Ge precursors. At a high total pressure case, it is needed to control the surface migration of precursors to realize the selectivity because the desorption of Ge precursors was suppressed. The selectivity of Ge growth was improved by diffusion of the Ge precursors on the SiO2 surfaces when patterned substrates were used at a high total pressure. The selective epitaxial growth of Ge1-xSnx layer was also realized using MOCVD. We found that the Sn precursors less likely to desorb from the SiO2 surfaces than the Ge precursors.

Y2O3:Eu phosphor particles prepared by spray pyrolysis from a solution containing citric acid and polyethylene glycol

NASA Astrophysics Data System (ADS)

Roh, H. S.; Kang, Y. C.; Park, H. D.; Park, S. B.

Y2O3:Eu phosphor particles were prepared by large-scale spray pyrolysis. The morphological control of Y2O3:Eu particles in spray pyrolysis was attempted by adding polymeric precursors to the spray solution. The effect of composition and amount of polymeric precursors on the morphology, crystallinity and photoluminescence characteristics of Y2O3:Eu particles was investigated. Particles prepared from a solution containing polyethylene glycol (PEG) with an average molecular weight of 200 had a hollow structure, while those prepared from solutions containing adequate amounts of citric acid (CA) and PEG had a spherical shape, filled morphology and clean surfaces after post-treatment at high temperature. Y2O3:Eu particles prepared from an aqueous solution with no polymeric precursors had a hollow structure and rough surfaces after post-treatment. The phosphor particles prepared from solutions with inadequate amounts of CA and/or PEG also had hollow and/or fragmented structures. The particles prepared from the solution containing 0.3 M CA and 0.3 M PEG had the highest photoluminescence emission intensity, which was 56% higher than that of the particles prepared from aqueous solution without polymeric precursors.

Monolithic Nickel (II) Oxide Aerogels Using an Organic Epoxide: The Importance of the Counter Ion

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

Gash, A E; Satcher, J H; Simpson, R L

2004-01-13

The synthesis and characterization of nickel (II) oxide aerogel materials prepared using the epoxide addition method is described. The addition of the organic epoxide propylene oxide to an ethanolic solution of NiCl{sub 2} 6H{sub 2}O resulted in the formation of an opaque light green monolithic gel and subsequent drying with supercritical CO{sub 2} gave a monolithic aerogel material of the same color. This material has been characterized using powder X-ray diffraction, electron microscopy, elemental analysis, and nitrogen adsorption/desorption analysis. The results indicate that the nickel (II) oxide aerogel has very low bulk density (98 kg/m{sup 3} ({approx}98 %porous)), high surfacemore » area (413 m{sup 2}/g), and has a particulate-type aerogel microstructure made up of very fine spherical particles with an open porous network. By comparison, a precipitate of Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} is obtained when the same preparation is attempted with the common Ni(NO{sub 3}){sub 2} 6H{sub 2}O salt as the precursor. The implications of the difference of reactivity of the two different precursors are discussed in the context of the mechanism of gel formation via the epoxide addition method. The synthesis of nickel (II) oxide aerogel, using the epoxide addition method, is especially unique in our experience. It is our first example of the successful preparation of a metal oxide aerogel using a metal divalent metal ion and may have implications for the application of this method to the preparation of aerogels or nanoparticles of other divalent metal oxides. To our knowledge this is the first report of a monolithic pure nickel (II) oxide aerogel materials.« less

Mixed Matrix PVDF Membranes With in Situ Synthesized PAMAM Dendrimer-Like Particles: A New Class of Sorbents for Cu(II) Recovery from Aqueous Solutions by Ultrafiltration.

PubMed

Kotte, Madhusudhana Rao; Kuvarega, Alex T; Cho, Manki; Mamba, Bhekie B; Diallo, Mamadou S

2015-08-18

Advances in industrial ecology, desalination, and resource recovery have established that industrial wastewater, seawater, and brines are important and largely untapped sources of critical metals and elements. A Grand Challenge in metal recovery from industrial wastewater is to design and synthesize high capacity, recyclable and robust chelating ligands with tunable metal ion selectivity that can be efficiently processed into low-energy separation materials and modules. In our efforts to develop high capacity chelating membranes for metal recovery from impaired water, we report a one-pot method for the preparation of a new family of mixed matrix polyvinylidene fluoride (PVDF) membranes with in situ synthesized poly(amidoamine) [PAMAM] particles. The key feature of our new membrane preparation method is the in situ synthesis of PAMAM dendrimer-like particles in the dope solutions prior to membrane casting using low-generation dendrimers (G0 and G1-NH2) with terminal primary amine groups as precursors and epichlorohydrin (ECH) as cross-linker. By using a combined thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS) casting process, we successfully prepared a new family of asymmetric PVDF ultrafiltration membranes with (i) neutral and hydrophilic surface layers of average pore diameters of 22-45 nm, (ii) high loadings (∼48 wt %) of dendrimer-like PAMAM particles with average diameters of ∼1.3-2.4 μm, and (iii) matrices with sponge-like microstructures characteristics of membranes with strong mechanical integrity. Preliminary experiments show that these new mixed matrix PVDF membranes can serve as high capacity sorbents for Cu(II) recovery from aqueous solutions by ultrafiltration.

Method of fabricating metal- and ceramic- matrix composites and functionalized textiles

DOEpatents

Maxwell, James L [Jemez Springs, NM; Chavez, Craig A [Los Alamos, NM; Black, Marcie R [Lincoln, MA

2012-04-17

A method of manufacturing an article comprises providing a first sheet, wetting the first sheet with a liquid precursor to provide a first wet sheet, and irradiating the first wet sheet in a pattern corresponding to a first cross section of the article such that the liquid precursor is at least partially converted to a solid in the first cross section. A second sheet is disposed adjacent to the first sheet. The method further comprises wetting the second sheet with the liquid precursor to provide a second wet sheet, and irradiating the second wet sheet in a pattern corresponding to a second cross section of the article such that the liquid precursor is at least partially converted to a solid in the second cross section. In particular the liquid precursor may be converted to a metal, ceramic, semiconductor, semimetal, or a combination of these materials.

Surface Acidity and Properties of TiO2/SiO2 Catalysts Prepared by Atomic Layer Deposition: UV-visible Diffuse Reflectance, DRIFTS, and Visible Raman Spectroscopy Studies

DTIC Science & Technology

2009-06-15

titanium isopropoxide (TTIP) as metal precursors. The deposition rate of titania films from TiCl4 was found to be stable in the 150-300 °C...tetrachloride (TiCl4) and titanium isopropoxide (TTIP) are widely used as metal precursors and water or hydrogen peroxide are used as oxygen precursors.29-36... titanium dioxide supported on high surface area silica gel have been synthesized by atomic layer deposition (ALD) using titanium tetrachloride (TiCl4) and

Synthesis and transformations of alkylphosphate and alkoxysiloxide metal complexes to multicomponent oxide materials

NASA Astrophysics Data System (ADS)

Lugmair, Claus Guenter

This thesis describes the synthesis of mixed element oxide materials utilizing oxygen rich ``single-source precursor'' molecules. The key attributes of these precursor complexes are that they possess the stoichiometry of the targeted oxide material and that they can be converted to carbon free materials by mild thermal treatment. Complexes of Al, Cu, Fe, Hf, Nb, Ta, Ti, and Zr were prepared that contain tris(tert-butoxy)siloxy ligands as precursors to silica based materials. The pyrolytic decomposition of these complexes occur under mild conditions, with onset temperatures to decomposition between 95 and 200sp°C. The resulting metal-silica or metal oxide-silica materials contain very little carbon. The solid state transformation of Zrlbrack OSi(OsptBu)sb3rbracksb4 to ZrOsb2{*}4SiOsb2 produced an open fibrous material with pores which are ca. 20 nm in diameter. The solution phase thermolysis of the various metal siloxide complexes in anhydrous organic solvents led to xerogels consisting of small spherical primary particles (≤ca. 5 nm). These xerogels typically possess very high surface areas. The ZrOsb2{*}4SiOsb2 materials are amorphous as initially formed, and subsequent crystallizations of tetragonal ZrOsb2, monoclinic ZrOsb2, and cristobalite occur at relatively high temperatures. The enhanced stabilization of the amorphous and tetragonal phases of zirconia, relative to those derived from many sol-gel systems, implies that these single-source precursors initially produce highly homogeneous materials and that subsequent crystallizations are to a large degree diffusion-controlled, Careful addition of 1 or 2 equiv of water to THF solutions of Mlbrack OSi(OsptBu)sb3rbracksb4 (M = Zr, Hf) produced the isolable aqua complexes Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O) and Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2. It is likely that the hydrolysis of Zrlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2 also occurs by an associative mechanism via the tris(aqua) intermediate Zrlbrack OSi(Osp{t}Bu)sb3rbracksb4(Hsb2O)sb3. The reaction of ZnEtsb2 with HO(O)P(OsptBu)sb2 in the presence of slight amounts of water produced good yields of the oxo-centered tetranuclear cluster Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6. When this complex was heated in ethanol at 85sp°C for 30 h, or dissolved in acid containing solutions, it converted to a polymer, \\{Znlbrack Osb2P(OsptBu)sb2rbracksb2\\}sbn, which contains zinc atoms that are linked alternately by one and then three bridging phosphate groups. Diffusion of a toluene solution of Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6 into a dichloromethane solution of 1,6-hexanediamine produced a layered coordination network with the formula \\{Znlbrack Osb2P(OsptBu)sb2rbracksb2lbrack Hsb2N(CHsb2)sb6NHsb2rbrack\\}sbn. The reaction between Znsb4(musb4-O)lbrack Osb2P(OsptBu)sb2rbracksb6 and either 4 or 8 equiv of n-alkylamines in toluene or isopropanol at elevated temperatures (180-220sp°C) led to the formation of lamellar zincophosphate materials. These mesophases consist of zinc phosphate layers that are separated by layers of n-alkylamines which adopt either an interdigitated or a double layer arrangement. Reactions of 1 equiv of HO(O)P(OsptBu)sb2 with Ti(OR)sb4 (R = Et, spiPr) gave the new molecular titanium phosphates lbrack Ti(OR)sb3Osb2P(OsptBu)sb2rbracksbn (R = Et, spiPr). Addition of 2 equiv of KOEt to an ethanol solution of lbrack Ti(OEt)sb3Osb2P(OsptBu)sb2rbracksbn led to the formation of lbrack Tisb2K(OEt)sb8Osb2P(OsptBu)sb2rbracksb2 and 1 equiv of KOsb2P(OsptBu)sb2. Addition of 2 equiv of KOspiPr to an isopropanol solution of lbrack Ti(OspiPr)sb3Osb2P(OsptBu)sb2rbracksb2 led to the formation of KOsb2P(OsptBu)sb2 and Ti(OspiPr)sb4 in high yield. (Abstract shortened by UMI.)

Nanoporous titanium niobium oxide and titanium tantalum oxide compositions and their use in anodes of lithium ion batteries

DOEpatents

Dai, Sheng; Guo, Bingkun; Sun, Xiao-Guang; Qiao, Zhenan

2017-10-31

Nanoporous metal oxide framework compositions useful as anodic materials in a lithium ion battery, the composition comprising metal oxide nanocrystals interconnected in a nanoporous framework and having interconnected channels, wherein the metal in said metal oxide comprises titanium and at least one metal selected from niobium and tantalum, e.g., TiNb.sub.2-x Ta.sub.xO.sub.y (wherein x is a value from 0 to 2, and y is a value from 7 to 10) and Ti.sub.2Nb.sub.10-vTa.sub.vO.sub.w (wherein v is a value from 0 to 2, and w is a value from 27 to 29). A novel sol gel method is also described in which sol gel reactive precursors are combined with a templating agent under sol gel reaction conditions to produce a hybrid precursor, and the precursor calcined to form the anodic composition. The invention is also directed to lithium ion batteries in which the nanoporous framework material is incorporated in an anode of the battery.

New polymeric precursors to SiNCB, BN, and La(3)Ni(2)B(2)N(3) materials

NASA Astrophysics Data System (ADS)

Wideman, Thomas W.

Boron-containing non-oxide ceramics demonstrate a number of important structural, electronic and physical properties. However, the lack of general synthetic routes to generate these materials with controlled composition, under moderate conditions, and in processed forms, has hampered both scientific studies and practical applications. The goal of the work described in this dissertation was to develop efficient new polymeric precursor routes to boron-containing materials including SiNCB ceramics composites, boron nitride fibers, and quaternary metal boro-nitride superconductors. Two types of polyborosilazane precursors to SiNCB ceramics were developed. Borazine-co-silazane copolymers were prepared through the thermal copolymerization of borazine with two silazanes, tris(trimethylsilylamino)silane, and 1,1,3,3,5,5 -hexamethylcyclotrisilazane. Polyborosilazanes with pendent boron-containing species were obtained by the modification of preformed hydridopolysilazane polymers with three monofunctional boranes: pinacolborane, 2,4-diethylborazine and 1,3-dimethyl-1,3-diaza-2-boracyclopentane. Pyrolyses of both types of polyborosilazanes produced SiNCB ceramics with controllable boron contents, enhanced thermal stabilities, and reduced crystallinity. Processible polymeric precursors to BN were also achieved by the chemical modification of polyborazylene, (Bsb3Nsb3Hsb{˜ 4}rbrack sb{x}, with diethylamine, dipentylamine, and hexamethyldisilazane. The modified polymers, unlike the parent polyborazylene, do not crosslink at low temperatures, and therefore proved to be ideal melt-spinnable precursors to BN ceramic fibers. A new polymeric precursor route to the recently discovered Lasb3Nisb2Bsb2Nsb3 superconductor (Tc = 12K) was developed by reacting lanthanum and nickel powders dispersed in the polyborazylene, to produce the intermetallic in excellent yields. The use of the polymer as a "reagent" provided a controllable, solid state source of nitrogen, and allows for the large scale syntheses of Lasb3Nisb2Bsb2Nsb3 and other quaternary metal boro-nitrides. Two new preparations of borazine, Bsb3Nsb3Hsb6, a key molecular unit in many of the polymers described above, have also been developed. Chemical investigations and practical applications of borazine-based preceramic polymers have been limited by the inefficient syntheses and high cost of borazine, which may now be prepared in 55-65% yields by the convenient, inexpensive the reaction of ammonium and borohydride salts, and the decomposition of ammonia borane, in high-boiling ether solutions.

A universal approach to the synthesis of nanodendrites of noble metals.

PubMed

Feng, Yan; Ma, Xiaohong; Han, Lin; Peng, Zhijian; Yang, Jun

2014-06-07

Nanomaterials usually exhibit structure-dependent catalytic activity, selectivity, and stability. Herein, we report a universal approach for the synthesis of noble metal nanoparticles with a dendritic structure, which is based on the reduction of metal acetylacetonate precursors in oleylamine at a temperature of 160 °C. In this strategy, the metal acetylacetonate precursors are reduced into metal atoms by oleylamine and grow into metal nanoparticles, while oleylamine is simultaneously converted into oleylamide to protect the nanoparticles. The competition between particle aggregation and oleylamide passivation is essential to the formation of a large number of particle aggregates, which eventually grow into nanodendrites via Ostwald ripening process. In particular, in comparison with commercial PtRu/C catalysts, the alloy PtRuOs nanodendrites exhibited superior catalytic activity toward methanol oxidation.

Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

NASA Technical Reports Server (NTRS)

Harrison, Joycelyn S. (Inventor); Lowther, Sharon E. (Inventor); Lillehei, Peter T. (Inventor); Park, Cheol (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Nazem, Negin (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor)

2017-01-01

A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

Novel Materials, Processing and Device Technologies for Space Exploration with Potential Dual-Use Applications

NASA Technical Reports Server (NTRS)

Hepp, A. F.; Bailey, S. G.; McNatt, J. S.; Chandrashekhar, M. V. S.; Harris, J. D.; Rusch, A. W.; Nogales, K. A.; Goettsche, K.V.; Hanson, W.; Amos, D.;

Novel Materials, Processing, and Device Technologies for Space Exploration with Potential Dual-Use Applications

NASA Technical Reports Server (NTRS)

Hepp, A. F.; Bailey, S. G.; McNatt, J. S.; Chandrashekhar, M. V. S.; Harris, J. D.; Rusch, A. W.; Nogales, K. A.; Goettsche, K. V.; Hanson, W.; Amos, D.;

Benzimidazole Based Aerogel Materials

NASA Technical Reports Server (NTRS)

Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

2016-01-01

The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

Solution-Processed Solar Cells via Nanocrystal Inks and Molecular Solutions

NASA Astrophysics Data System (ADS)

Miskin, Caleb K.

On February 15, 2008 the National Academy of Engineering unveiled their fourteen grand challenges of engineering for the 21st century. At the top of the list and voted by the public as the most important challenge was the thrust to make solar energy economical. My research has been dedicated to solving this millennial challenge by developing routes to high-efficiency, solution-processed photovoltaics (PV) for low-cost and low-energy manufacturing. My research has primarily advanced two methods for solution processed PV. In one method, semiconducting nanocrystals are synthesized and then suspended in an appropriate solvent to form an ink. The ink is then applied to a substrate by a variety of high-throughput methods such as spray coating or doctor blading and then annealed to form a polycrystalline absorber layer for solar energy. I have applied this method with great success to Cu2ZnSnS 4, a promising earth-abundant, non-toxic semiconductor. A challenge with this material is its propensity to form binary and ternary undesired phases. Using advanced nano-characterization techniques, my colleagues and I have been able to determine the spatially resolved composition of these nanoparticles and have found them to be highly non-uniform. In addition, I developed synthesis techniques aimed at controlling the nucleation and growth of this material to improve nanocrystal compositional homogeneity. Though particles produced in this work still exhibit some non-uniformities, they are greatly improved. When combined with optimized fabrication techniques, I have been able to advance the efficiency of nanocrystal ink based solar cells of CZTS from 7.2 to 9.0 percent in our lab. Another promising route to solution-processed PV is by directly coating molecular precursor solutions (rather than first forming nanocrystals) and annealing the coating to form the polycrystalline solar absorber layer. Unfortunately, a major challenge is that many metals, metal salts, and chalcogens that would be useful precursors to such films have poor solubility in organic solvents compatible with roll-to-roll manufacturing techniques. Interestingly, we have found that mixtures of commonly available thiols and amines are able to dissolve at room temperature and pressure a host of metals and salts that are otherwise insoluble in either solvent by itself. In this work, I have primarily focused on CdTe--which has been by far the most successful technology in terms of production cost ($/peak watt) and energy payback time for thin-film solar cells. In this research thrust I demonstrate for the first time the fabrication of CdTe thin-films via a solution-processed molecular precursor approach by dissolving CdCl2 and Te in ethylenediamine and 1-propanethiol. The films are formed by spin-coating thin layers of the solution and then annealing each layer until a 1.5 mum thick film is achieved. I have achieved 0.5% efficient devices by this method. As thiol-amine mixtures have the potential to leave residual sulfur in these films, other novel solvent systems are presented as future work. While amine-thiol mixtures are excellent solvents for many materials, they do not dissolve lead chalcogenides with ease. I leverage this to develop room-temperature synthesis routes to PbS, PbSe, PbTe, and PbSxSe 1-x nanoparticles. This is achieved by mixing a lead salt dissolved in thiol-amine with a chalcogen dissolved in thiol-amine at room temperature. We find that when particles produced in this manner are pressed into pellets, they show comparable thermoelectric performance to more complicated and energy intensive synthesis techniques. Ultimately, we wish to enable the use of these particles in room-temperature fabricated quantum dot solar cells. This requires the synthesis of highly monodisperse, stable colloids and is the subject of future work using thiol-amine mixtures and related aqueous analogues.

Nonequilibrium Phase Precursors during a Photoexcited Insulator-to-Metal Transition in V2O3

NASA Astrophysics Data System (ADS)

Singer, Andrej; Ramirez, Juan Gabriel; Valmianski, Ilya; Cela, Devin; Hua, Nelson; Kukreja, Roopali; Wingert, James; Kovalchuk, Olesya; Glownia, James M.; Sikorski, Marcin; Chollet, Matthieu; Holt, Martin; Schuller, Ivan K.; Shpyrko, Oleg G.

2018-05-01

Here, we photoinduce and directly observe with x-ray scattering an ultrafast enhancement of the structural long-range order in the archetypal Mott system V2O3 . Despite the ultrafast increase in crystal symmetry, the change of unit cell volume occurs an order of magnitude slower and coincides with the insulator-to-metal transition. The decoupling between the two structural responses in the time domain highlights the existence of a transient photoinduced precursor phase, which is distinct from the two structural phases present in equilibrium. X-ray nanoscopy reveals that acoustic phonons trapped in nanoscale twin domains govern the dynamics of the ultrafast transition into the precursor phase, while nucleation and growth of metallic domains dictate the duration of the slower transition into the metallic phase. The enhancement of the long-range order before completion of the electronic transition demonstrates the critical role the nonequilibrium structural phases play during electronic phase transitions in correlated electrons systems.

Metastability and structural polymorphism in noble metals: the role of composition and metal atom coordination in mono- and bimetallic nanoclusters.

PubMed

Sanchez, Sergio I; Small, Matthew W; Bozin, Emil S; Wen, Jian-Guo; Zuo, Jian-Min; Nuzzo, Ralph G

2013-02-26

This study examines structural variations found in the atomic ordering of different transition metal nanoparticles synthesized via a common, kinetically controlled protocol: reduction of an aqueous solution of metal precursor salt(s) with NaBH₄ at 273 K in the presence of a capping polymer ligand. These noble metal nanoparticles were characterized at the atomic scale using spherical aberration-corrected scanning transmission electron microscopy (C(s)-STEM). It was found for monometallic samples that the third row, face-centered-cubic (fcc), transition metal [(3M)-Ir, Pt, and Au] particles exhibited more coherently ordered geometries than their second row, fcc, transition metal [(2M)-Rh, Pd, and Ag] analogues. The former exhibit growth habits favoring crystalline phases with specific facet structures while the latter samples are dominated by more disordered atomic arrangements that include complex systems of facets and twinning. Atomic pair distribution function (PDF) measurements further confirmed these observations, establishing that the 3M clusters exhibit longer ranged ordering than their 2M counterparts. The assembly of intracolumn bimetallic nanoparticles (Au-Ag, Pt-Pd, and Ir-Rh) using the same experimental conditions showed a strong tendency for the 3M atoms to template long-ranged, crystalline growth of 2M metal atoms extending up to over 8 nm beyond the 3M core.

"Nickel Nanoflowers" with Surface-Attached Fluoropolymer Networks by C,H Insertion for the Generation of Metallic Superhydrophobic Surfaces.

PubMed

Hönes, Roland; Rühe, Jürgen

2018-05-08

Metallic superhydrophobic surfaces (SHSs) combine the attractive properties of metals, such as ductility, hardness, and conductivity, with the favorable wetting properties of nanostructured surfaces. Moreover, they promise additional benefits with respect to corrosion protection. For the modification of the intrinsically polar and hydrophilic surfaces of metals, a new method has been developed to deposit a long-term stable, highly hydrophobic coating, using nanostructured Ni surfaces as an example. Such substrates were chosen because the deposition of a thin Ni layer is a common choice for enhancing corrosion resistance of other metals. As the hydrophobic coating, we propose a thin film of an extremely hydrophobic fluoropolymer network. To form this network, a thin layer of a fluoropolymer precursor is deposited on the Ni substrate which includes a comonomer that is capable of C,H insertion cross-linking (CHic). Upon UV irradiation or heating, the cross-linker units become activated and the thin glassy film of the precursor is transformed into a polymer network that coats the surface conformally and permanently, as shown by extensive extraction experiments. To achieve an even higher stability, the same precursor film can also be transformed into a chemically surface-attached network by depositing a self-assembled monolayer of an alkane phosphonic acid on the Ni before coating with the precursor. During cross-linking, by the same chemical process, the growing polymer network will simultaneously attach to the alkane phosphonic acid layer at the surface of the metal. This strategy has been used to turn fractal Ni "nanoflower" surfaces grown by anisotropic electroplating into SHSs. The wetting characteristics of the obtained nanostructured metallic surfaces are studied. Additionally, the corrosion protection effect and the significant mechanical durability are demonstrated.

Synthesis of GaN:ZnO solid solution by solution combustion method and characterization for photocatalytic application

NASA Astrophysics Data System (ADS)

Menon, Sumithra Sivadas; Anitha, R.; Gupta, Bhavana; Baskar, K.; Singh, Shubra

2016-05-01

GaN-ZnO solid solution has emerged as a successful and reproducible photocatalyst for overall water splitting by one-step photoexcitation, with a bandgap in visible region. When the solid solution is formed, some of the Zn and O ions are replaced by Ga and N ions respectively and there is a narrowing of bandgap which is hypothesized as due to Zn3d-N2p repulsion. The traditional method of synthesis of GaN-ZnO solid solution is by nitridation of the starting oxides under constant ammonia flow. Here we report a solution combustion technique for the synthesis of the solid solution at a temperature about 500 ° C in a muffle furnace with metal nitrates as precursors and urea as the fuel. The as prepared samples showed change in color with the increased concentration of ZnO in the solution. The structural, microstructural, morphological and optical properties of the samples were realized by Powder X ray diffraction, Scanning electron microscopy, Energy dispersive X ray analysis, Transmission electron microscopy and Photoluminescence. Finally the hydrogen production efficiency of the GaN-ZnO nanopowders by water splitting was found, using methanol as a scavenger. The apparent quantum yield (AQY) of 0.048% is obtained for GaN-ZnO solid solution.

Novel materials for electrochemical power sources—introduction of PUREBLACK ® Carbons

NASA Astrophysics Data System (ADS)

Barsukov, Igor V.; Gallego, Maritza A.; Doninger, Joseph E.

Graphitization heat treatment of a precursor carbon black was seen to effectively produce a wide variety of forms of partially graphitized nano-sized carbonaceous materials with a set of unique properties, some of which are reported in this paper in comparison with those properties of the precursor carbon material. These novel materials were given the name of PUREBLACK ® Carbons. Among some of the unique properties are: higher conductivity than that of acetylene type carbon blacks due to PUREBLACK ® Carbon's particles having more graphitic structure; very low to zero volatile content (external oxygen, sulfur, etc., groups, which are often believed to be the cause of initiation of self-discharge reactions in batteries); very low equilibrium moisture pickup (20 ppm level), which makes it particularly attractive in lithium metal or lithium-ion based electrochemical systems; high purity. Electrochemical testing of the newly proposed PUREBLACK ® Carbons in several battery systems offers significant promise that it presents a viable solution to the needs of industry.

Preparation of Mesoporous Ceramics from Polymer Nanotubes

NASA Astrophysics Data System (ADS)

Chen, Dian; Park, Soojin; Chen, Jiun-Tai; Redston, Emily; Russell, Thomas

2009-03-01

Poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) nanotubes were prepared by placing polymer solution into the cylindrical nanopores of an anodic aluminum oxide (AAO) membrane. The PS-b-P4VP nanotubes within the AAO membranes were exposed to tetrahydrofuran vapor to produce uniform spherical micelles along the tube. The tubes were removed from the membranes, then suspended in ethylene glycol, a preferential solvent for P4VP. At 95^ oC, near the glass transition temperature (Tg) of PS, nanotubes with uniform nanopores were obtained by a reconstruction of the nanotubes. As the temperature was increased, mesoporous polymer structures were obtained. Tetraethyl orthosilicate or titanium tetraethoxide, ceramic precursors, were introduced into the 4VP microdomains. After exposure to an oxygen plasma or high temperature, the copolymer was removed and the precursor converted to a mesoporous ceramic. This process offers a simple route for the fabrication of tunable mesoporous ceramic or metallic structures by changing molecular weight of copolymers.

Self-assembly of a triangle-shaped, hexaplatinum-incorporated, supramolecular amphiphile in solution and at interfaces.

PubMed

Maran, Umamageswaran; Britt, David; Fox, Christopher B; Harris, Joel M; Orendt, Anita M; Conley, Hiram; Davis, Robert; Hlady, Vladamir; Stang, Peter J

2009-08-24

The self-assembly and characterization of a novel supramolecular amphiphile built from a new 60 degree amphiphilic precursor that incorporates hydrophilic platinum(II) metals and hydrophobic dioctadecyloxy chains is reported. The amphiphilic macrocycle and its precursor compound have been characterized by multinuclear NMR spectroscopy, ESI-MS, and other standard techniques. The coacervate morphology of the amphiphile at the liquid-liquid interface has been studied by using confocal optical microscopy and in situ Raman spectroscopy. The self-assembly of the amphiphilic macrocycle at the air-water interface has been investigated through Langmuir-trough techniques. The study indicates the possible formation of surface micelle-like aggregates. The disparity between the experimental molecular areas and those derived from molecular models support the idea of aggregation. AFM images of the surface aggregates show the formation of a flat topology with arbitrary ridgelike patterns. Reasonable molecular-packing arrangements are proposed to explain the molecular organization within the observed structures.

Custom-designed nanomaterial libraries for testing metal oxide toxicity

PubMed Central

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

2014-01-01

Conspectus Advances in aerosol technology over the past 10 years have provided methods that enable the generation and design of ultrafine nanoscale materials for different applications. The particles are produced combusting a precursor solution and its chemical reaction in the in the gas phase. Flame spray pyrolysis (FSP) is a highly versatile technique for single step and scalable synthesis of nanoscale materials. New innovations in particle synthesis using FSP technology and its precursor chemistry have enabled flexible dry synthesis of loosely-agglomerated highly crystalline ultrafine powders (porosity ≥ 90%) of binary, ternary and mixed binary or ternary oxides. The flame spray pyrolysis lies at the intersection of combustion science, aerosols technology and materials chemistry. The interdisciplinary research is not only inevitable but is becoming increasingly crucial in the design of nanoparticles (NPs) made in the gas phase. The increasing demand especially in the bio-applications for particles with specific material composition, high purity and crystallinity can be often fulfilled with the fast, single step FSP technique. PMID:23194152

Fidelity of metal insertion into hydrogenases.

PubMed

Magalon, A; Blokesch, M; Zehelein, E; Böck, A

2001-06-15

The fidelity of metal incorporation into the active center of hydrogenase 3 from Escherichia coli was studied by analyzing the inhibition of the maturation pathway by zinc and other transition metals. Hydrogenase maturation of wild-type cells was significantly affected only by concentrations of zinc or cadmium higher than 200 microM, whereas a mutant with a lesion in the nickel uptake system displayed a total blockade of the proteolytic processing of the precursor form into the mature form of the large subunit after growth in the presence of 10 microM Zn(2+). The precursor could not be processed in vitro by the maturation endopeptidase even in the presence of an excess of nickel ions. Evidence is presented that zinc does not interfere with the incorporation of iron into the metal center. Precursor of the large subunit accumulated in nickel proficient cells formed a transient substrate complex with the cognate endoprotease HycI whereas that of zinc-supplemented cells did not. The results show that zinc can intrude the nickel-dependent maturation pathway only when nickel uptake is blocked. Under this condition zinc appears to be incorporated at the nickel site of the large subunit and delivers a precursor not amenable to proteolytic processing since the interaction with the endoprotease is blocked.

Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

NASA Astrophysics Data System (ADS)

Muoto, Chigozie Kenechukwu

This research aims to identify the key feedstock characteristics and processing conditions to produce Y2O3-MgO composite coatings with high density and hardness using solution precursor plasma spray (SPPS) and suspension plasma spray (SPS) processes, and also, to explore the phenomena involved in the production of homogenized nano-composite powders of this material system by thermal decomposition of solution precursor mixtures. The material system would find potential application in the fabrication of components for optical applications such as transparent windows. It was shown that a lack of major endothermic events during precursor decomposition and the resultant formation of highly dense particles upon pyrolysis are critical precursor characteristics for the deposition of dense and hard Y2O3-MgO coatings by SPPS. Using these principles, a new Y2O3-MgO precursor solution was developed, which yielded a coating with Vickers hardness of 560 Hv. This was a considerable improvement over the hardness of the coatings obtained using conventional solution precursors, which was as low as 110 Hv. In the thermal decomposition synthesis process, binary solution precursor mixtures of: yttrium nitrate (Y[n]) or yttrium acetate (Y[a]), with magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were used in order to study the effects of precursor chemistry on the structural characteristics of the resultant Y2O3-MgO powders. The phase domains were coarse and distributed rather inhomogeneously in the materials obtained from the Y[n]Mg[n] and Y[a]Mg[a] mixtures; finer and more homogeneously-distributed phase domains were obtained for ceramics produced from the Y[a]Mg[n] and Y[n]Mg[a] mixtures. It was established that these phenomena were related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization. Addition of ammonium acetate to the Y[n[Mg[n] mixture changed the endothermic process to exothermic and improved the dispersion of the component phases. Two suspension types, made with powders synthesized from the Y[n]Mg[n] and Y[n]Mg[a] precursor mixtures were sprayed by SPS. The densities and hardnesses of the coatings deposited using the two powder types were similar. However, the microstructure of coatings deposited using the Y[n]Mg[a]-synthesized powder exhibited some eutectic configuration which was not observed in the coatings deposited using the Y[n]Mg[n]-synthesized powder.

Investigation on V2O5 Thin Films Prepared by Spray Pyrolysis Technique

NASA Astrophysics Data System (ADS)

Anasthasiya, A. Nancy Anna; Gowtham, K.; Shruthi, R.; Pandeeswari, R.; Jeyaprakash, B. G.

The spray pyrolysis technique was employed to deposit V2O5 thin films on a glass substrate. By varying the precursor solution volume from 10mL to 50mL in steps of 10mL, films of various thicknesses were prepared. Orthorhombic polycrystalline V2O5 films were inferred from the XRD pattern irrespective of precursor solution volume. The micro-Raman studies suggested that annealed V2O5 thin film has good crystallinity. The effect of precursor solution volume on morphological and optical properties were analysed and reported.

A novel precursor system and its application to produce tin doped indium oxide.

PubMed

Veith, M; Bubel, C; Zimmer, M

2011-06-14

A new type of precursor has been developed by molecular design and synthesised to produce tin doped indium oxide (ITO). The precursor consists of a newly developed bimetallic indium tin alkoxide, Me(2)In(O(t)Bu)(3)Sn (Me = CH(3), O(t)Bu = OC(CH(3))(3)), which is in equilibrium with an excess of Me(2)In(O(t)Bu). This quasi single-source precursor is applied in a sol-gel process to produce powders and coatings of ITO using a one-step heat treatment process under an inert atmosphere. The main advantage of this system is the simple heat treatment that leads to the disproportionation of the bivalent Sn(II) precursor into Sn(IV) and metallic tin, resulting in an overall reduced state of the metal in the final tin doped indium oxide (ITO) material, hence avoiding the usually necessary reduction step. Solid state (119)Sn-NMR measurements of powder samples confirm the appearance of Sn(II) in an amorphous gel state and of metallic tin after annealing under nitrogen. The corresponding preparation of ITO coatings by spin coating on glass leads to transparent conductive layers with a high transmittance of visible light and a low electrical resistivity without the necessity of a reduction step.

Spinel formation for stabilizing simulated nickel-laden sludge with aluminum-rich ceramic precursors.

PubMed

Shih, Kaimin; White, Tim; Leckie, James O

2006-08-15

The feasibility of stabilizing nickel-laden sludge from commonly available Al-rich ceramic precursors was investigated and accomplished with high nickel incorporation efficiency. To simulate the process, nickel oxide was mixed alternatively with gamma-alumina, corundum, kaolinite, and mullite and was sintered from 800 to 1480 degrees C. The nickel aluminate spinel (NiAl2O4) was confirmed as the stabilization phase for nickel and crystallized with efficiencies greater than 90% for all precursors above 1250 degrees C and 3-h sintering. The nickel-incorporation reaction pathways with these precursors were identified, and the microstructure and spinel yield were investigated as a function of sintering temperature with fixed sintering time. This study has demonstrated a promising process for forming nickel spinel to stabilize nickel-laden sludge from a wide range of inexpensive ceramic precursors, which may provide an avenue for economically blending waste metal sludges via the building industry processes to reduce the environmental hazards of toxic metals. The correlation of product textures and nickel incorporation efficiencies through selection of different precursors also provides the option of tailoring property-specific products.

Performance and stress analysis of metal oxide films for CMOS-integrated gas sensors.

PubMed

Filipovic, Lado; Selberherr, Siegfried

2015-03-25

The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chemicals and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their electrical conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temperatures between 250°C and 550°C during operation in order to increase their sensing functionality, a considerable degradation of the film can result. The stress generation during thin film deposition and the thermo-mechanical stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor solution, the transport of the aerosol droplets towards the wafer and the decomposition of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodology are presented. The dependence of the deposition technique on the sensor performance is also discussed.

Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

PubMed Central

Filipovic, Lado; Selberherr, Siegfried

2015-01-01

The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chemicals and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their electrical conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temperatures between 250 °C and 550 °C during operation in order to increase their sensing functionality, a considerable degradation of the film can result. The stress generation during thin film deposition and the thermo-mechanical stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor solution, the transport of the aerosol droplets towards the wafer and the decomposition of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodology are presented. The dependence of the deposition technique on the sensor performance is also discussed. PMID:25815445

Stabilized metal nanoparticles from organometallic precursors for low temperature fuel cells.

PubMed

Ramirez-Meneses, E; Dominguez-Crespo, M A; Torres-Huerta, A M

2013-01-01

In this work, a review of articles and patents related to the utilization of colloidal metal nanoparticles produced by the decomposition of organometallic precursors as supported electrocatalysts in different electrochemical reactions including hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) is discussed. In the case of stabilized metal nanoparticles, the kind of functional group contained in the stabilizer as well as the metal/stabilizer ratio, to evaluate the effect of particle size on the electrochemical performance, were also debated. Potential applications and perspectives of these electrocatalysts in proton exchange membrane fuel cells (PEMFC) are contended with reference to the role played by the coordination compounds and costs.

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.

Platinum CCC-NHC benzimidazolyl pincer complexes: synthesis, characterization, photostability, and theoretical investigation of a blue-green emitter.

PubMed

Huckaba, Aron J; Cao, Bei; Hollis, T Keith; Valle, Henry U; Kelly, John T; Hammer, Nathan I; Oliver, Allen G; Webster, Charles Edwin

2013-06-28

The recently reported metallation/transmetallation route for the synthesis of CCC-bis(NHC) pincer ligand architectures was extended to 1,3-bis(3'-(trimethylsilylmethyl)-benzimidizol-1'-yl)benzene. The precursor was metallated with Zr(NMe2)4 and transmetallated to Pt using [Pt(COD)Cl2]. This Pt complex was found to resist photobleaching under UV irradiation in ambient conditions. Density functional theory (DFT) computations were used to generate the emission spectrum of the complex and reveal that this spectrum is the result of a transition from the triplet excited state (T1) to the ground state (S0). The Pt complex's molecular structure was determined by X-ray crystallography. The UV-vis absorption and emission spectra in solution and the solid-state emission spectra are reported. The solid-state photostability data and the radiative lifetime is also reported.

Processing effects on the microstructure and dielectric properties of hydrothermal barium titanate and (barium,strontium)titanate thin films

NASA Astrophysics Data System (ADS)

McCormick, Mark Alan

The goal of this work was to produce BaTiO3 and BaxSr (1-x)TiO3 (BST) thin films with high dielectric constants, using a low-temperature (<100°C) hydrothermal synthesis route. To accomplish this, titanium metal-organic precursor films were spin-cast onto metal-coated glass substrates and converted to polycrystalline BaTiO3 or BST upon reacting in aqueous solutions of Ba(OH)2 or Ba(OH)2 and Sr(OH)2. The influences of solution molarity, processing temperature, and reaction time on thin film reaction kinetics, microstructure, and dielectric properties were examined for BaTiO3 films. Post-deposition annealing at temperatures as low as 200°C substantially affected the lattice parameter, dielectric constant, and dielectric loss. This behavior is explained in terms of hydroxyl defect incorporation during film formation. Current-voltage (I-V) measurements were performed to determine the dominant conduction mechanism(s) during application of a do field, and to extract the metal/ceramic barrier height. In particular, Schottky barrier-limited conduction and Poole-Frenkel conduction were investigated as potential leakage mechanisms. For BST thin films, film stoichiometry deviated from the initial solution composition, with a preferred incorporation of Sr2+ into the perovskite lattice. The dielectric constant of the BST films was measured as a function of composition (Ba:Sr ratio) and temperature over the range 25--150°C. Finally, capacitance-voltage (C-V) measurements were made for BST films to determine the influence of film composition on dielectric tunability.

Hydrogen generation from water/methanol under visible light using aerogel prepared strontium titanate (SrTiO3) nanomaterials doped with ruthenium and rhodium metals

NASA Astrophysics Data System (ADS)

Kuo, Yenting; Klabunde, Kenneth J.

2012-07-01

Nanostructured strontium titanate visible-light-driven photocatalysts containing rhodium and ruthenium were synthesized by a modified aerogel synthesis using ruthenium chloride and rhodium nitrate as dopant precursors, and titanium isopropoxide and strontium metal as the metal sources. The well-defined crystalline SrTiO3 structure was confirmed by means of x-ray diffraction. After calcination at 500 °C, diffuse reflectance spectroscopy shows an increase in light absorption at 370 nm due to the presence of Rh3 + ; however an increase of the calcination temperature to 600 °C led to a decrease in intensity, probably due to a loss of surface area. An increase in the rhodium doping level also led to an increase in absorption at 370 nm however, the higher amounts of dopant lowered the photocatalytic activity. The modified aerogel synthesis allows greatly enhanced H2 production performance from an aqueous methanol solution under visible light irradiation compared with lower surface area conventional materials. We believe that this enhanced activity is due to the higher surface areas while high quality nanocrystalline materials are still obtained. Furthermore, the surface properties of these nanocrystalline aerogel materials are different, as exhibited by the higher activities in alkaline solutions, while conventional materials (obtained via high temperature solid-state synthesis methods) only exhibit reasonable hydrogen production in acidic solutions. Moreover, an aerogel synthesis approach gives the possibility of thin-film formation and ease of incorporation into practical solar devices.

Microcellular carbon foam and method

DOEpatents

Simandl, R.F.; Brown, J.D.

1993-05-04

A microcellular carbon foam is characterized by a density in the range of about 30 to 1,000 mg/cm[sup 3], substantially uniform distribution of cell sizes of diameters less than 100 [mu]m with a majority of the cells being of a diameter of less than about 10 [mu]m. The foam has a well interconnected strut morphology providing open porosity, and an expanded d(002) X-ray turbostatic spacing greater than 3.50 angstroms. The precursor for the carbon foam is prepared by the phase inversion of polyacrylonitrile in a solution consisting essentially of at least one alkali metal halide and a phase inversion solvent for the polyacrylonitrile.

Microcellular carbon foam and method

DOEpatents

Simandl, R.F.; Brown, J.D.

1994-04-05

A microcellular carbon foam is described which is characterized by a density in the range of about 30 to 1000 mg/cm[sup 3], substantially uniform distribution of cell sizes of diameters less than 100 [mu]m with a majority of the cells being of a diameter of less than about 10 [mu]m, well interconnected strut morphology providing open porosity, and an expanded d(002) X-ray turbostatic spacing greater than 3.50 angstroms. The precursor for the carbon foam is prepared by the phase inversion of polyacrylonitrile in a solution consisting essentially of at least one alkali metal halide and a phase inversion solvent for the polyacrylonitrile.

Environmental Degradation of Materials: Surface Chemistry Related to Stress Corrosion Cracking

NASA Technical Reports Server (NTRS)

Schwarz, J. A.

1985-01-01

Parallel experiments have been performed in order to develop a comprehensive model for stress cracking (SCC) in structural materials. The central objective is to determine the relationship between the activity and selectivity of the microstructure of structural materials to their dissolution kinetics and experimentally measured SCC kinetics. Zinc was chosen as a prototype metal system. The SCC behavior of two oriented single-crystal disks of zinc in a chromic oxide/sodium sulfate solution (Palmerton solution) were determined. It was found that: (1) the dissolution rate is strongly (hkil)-dependent and proportional to the exposure time in the aggressive environment; and (2) a specific slip system is selectively active to dissolution under applied stress and this slip line controls crack initiation and propagation. As a precursor to potential microgrvity experiments, electrophoretic mobility measurements of zinc particles were obtained in solutions of sodium sulfate (0.0033 M) with concentrations of dissolved oxygen from 2 to 8 ppm. The equilibrium distribution of exposed oriented planes as well as their correlation will determine the particle mobility.

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO2 Gate Insulator TFT with a High Concentration Precursor

PubMed Central

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Zheng, Zeke; Zhou, Shangxiong; Peng, Junbiao; Lu, Xubing

2017-01-01

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO2 films by intentionally increasing the concentration of precursor. The ZrO2 films not only exhibit a low leakage current density of 10−6 A/cm2 at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm2·V−1·s−1 and a Ion/Ioff ratio of 106 in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO2/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness. PMID:28825652

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO₂ Gate Insulator TFT with a High Concentration Precursor.

PubMed

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Zhou, Shangxiong; Yao, Rihui; Peng, Junbiao; Lu, Xubing

2017-08-21

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO₂ films by intentionally increasing the concentration of precursor. The ZrO₂ films not only exhibit a low leakage current density of 10 -6 A/cm² at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm²·V -1 ·s -1 and a I on /I off ratio of 10⁶ in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO₂/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness.

EFFECTS OF PRECURSOR SOLUTION MODIFICATION ON THE CRYSTALLINITY AND ELECTRICAL PROPERTIES OF Na0.5Bi0.5TiO3-BiFeO3 BASED THIN FILM

NASA Astrophysics Data System (ADS)

Sui, Huiting; Yang, Changhong; Wang, Gaoyun; Feng, Chao

2014-07-01

For chemical solution decomposition process, the precursor solution is a basic factor affecting the quality of the deposited-film. In this paper, we choose (l00)-oriented 0.7[(Bi0.95Ce0.05)0.5Na0.5(Ti0.99Fe0.01)O3]-0.3BiFe0.97Mn0.03O3(0.7NBTCeFe-0.3BFOMn) thin films prepared by various precursor solutions for investigation. The roles of precursor solution modification on crystallinity, ferroelectric and dielectric properties are characterized. With the addition of polyethylene glycol into the solution, phase-pure perovskite structure can be obtained. Furthermore, when the volume ratio for the solvents (ethylene glycol to acetic acid) is modified as 2:1, enhanced ferroelectricity can be achieved with a remanent polarization (Pr) of 27.5 μC/cm2, which coincides well with the capacitance-voltage curve with relatively sharp feature. Also, the 0.7NBTCeFe-0.3BFOMn film exhibits a dielectric constant (ɛr) of 576 and dielectric loss (tan δ) of 0.123 at 100 kHz.

Synergistic effects of water addition and step heating on the formation of solution-processed zinc tin oxide thin films: towards high-mobility polycrystalline transistors

NASA Astrophysics Data System (ADS)

Huang, Genmao; Duan, Lian; Zhao, Yunlong; Zhang, Yunge; Dong, Guifang; Zhang, Deqiang; Qiu, Yong

2016-11-01

Thin-film transistors (TFTs) with high mobility and good uniformity are attractive for next-generation flat panel displays. In this work, solution-processed polycrystalline zinc tin oxide (ZTO) thin film with well-ordered microstructure is prepared, thanks to the synergistic effect of water addition and step heating. The step heating treatment other than direct annealing induces crystallization, while adequate water added to precursor solution further facilitates alloying and densification process. The optimal polycrystalline ZTO film is free of hierarchical sublayers, and featured with an increased amount of ternary phases, as well as a decreased fraction of oxygen vacancies and hydroxides. TFT devices based on such an active layer exhibit a remarkable field-effect mobility of 52.5 cm2 V-1 s-1, a current on/off ratio of 2 × 105, a threshold voltage of 2.32 V, and a subthreshold swing of 0.36 V dec-1. Our work offers a facile method towards high-performance solution-processed polycrystalline metal oxide TFTs.

Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

PubMed

Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

2016-04-13

Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

Environmentally friendly preparation of metal nanoparticles

EPA Science Inventory

The book chapter summarizes the “state of the art” in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes.

Method of making sintered ductile intermetallic-bonded ceramic composites

DOEpatents

Plucknett, Kevin; Tiegs, Terry N.; Becher, Paul F.

1999-01-01

A method of making an intermetallic-bonded ceramic composite involves combining a particulate brittle intermetallic precursor with a particulate reactant metal and a particulate ceramic to form a mixture and heating the mixture in a non-oxidizing atmosphere at a sufficient temperature and for a sufficient time to react the brittle intermetallic precursor and the reactant metal to form a ductile intermetallic and sinter the mixture to form a ductile intermetallic-bonded ceramic composite.

Heteromorphic NiCo2S4/Ni3S2/Ni Foam as a Self-Standing Electrode for Hydrogen Evolution Reaction in Alkaline Solution.

PubMed

Liu, Hui; Ma, Xiao; Rao, Yuan; Liu, Yang; Liu, Jialiang; Wang, Luyang; Wu, Mingbo

2018-04-04

Considerable works have been devoted on developing high-efficiency nonplatinum electrocatalysts for hydrogen evolution reaction (HER). Herein, 3D heteromorphic NiCo 2 S 4 /Ni 3 S 2 nanosheets network has been constructed on Ni foam (denoted as NiCo 2 S 4 /Ni 3 S 2 /NF) serving as a self-standing electrocatalyst through directly thermal sulfurization of a single-source NiCo-layered double hydroxide precursor. The resultant NiCo 2 S 4 /Ni 3 S 2 /NF electrode exhibits outstanding electrocatalytic HER performance with an extremely low onset overpotential of 15 mV and long-term durability in alkaline solution. Such enhanced HER performance can be credited to (1) the massive exposed active sites provided by mixed transition metal chalcogenides (NiCo 2 S 4 and Ni 3 S 2 ), (2) the strong interfacial interaction at NiCo 2 S 4 /Ni 3 S 2 heterojunction interfaces with the strengthened H binding, and (3) the porous highly conductive Ni foam substrate with accelerated electron transfer. This work opens up a new direction to fabricate effective and non-noble-metal electrodes for water splitting and hydrogen generation.

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

PubMed

Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

2016-02-01

In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

Method for forming solar cell materials from particulars

DOEpatents

Eberspacher, Chris; Pauls, Karen Lea

2001-01-01

Materials in bulk and film forms are prepared from fine particulate precursors such as single-phase, mixed-metal oxides; multi-phase, mixed-metal particles comprising a metal oxide; multinary metal particles; mixtures of such particles with other particles; and particulate materials intercalated with other materials.

Facile solid-state synthesis of oxidation-resistant metal nanoparticles at ambient conditions

NASA Astrophysics Data System (ADS)

Lee, Kyu Hyung; Jung, Hyuk Joon; Lee, Ju Hee; Kim, Kyungtae; Lee, Byeongno; Nam, Dohyun; Kim, Chung Man; Jung, Myung-Hwa; Hur, Nam Hwi

2018-05-01

A simple and scalable method for the synthesis of metal nanoparticles in the solid-state was developed, which can produce nanoparticles in the absence of solvents. Nanoparticles of coinage metals were synthesized by grinding solid hydrazine and the metal precursors in their acetates and oxides at 25 °C. The silver and gold acetates converted completely within 6 min into Ag and Au nanoparticles, respectively, while complete conversion of the copper acetate to the Cu sub-micrometer particles took about 2 h. Metal oxide precursors were also converted into metal nanoparticles by grinding alone. The resulting particles exhibit distinctive crystalline lattice fringes, indicating the formation of highly crystalline phases. The Cu sub-micrometer particles are better resistant to oxidation and exhibit higher conductivity compared to conventional Cu nanoparticles. This solid-state method was also applied for the synthesis of platinum group metals and intermetallic Cu3Au, which can be further extended to synthesize other metal nanoparticles.

Enabling Surgical Placement of Hydrogels through Achieving Paste-Like Rheological Behavior in Hydrogel Precursor Solutions

PubMed Central

Beck, Emily C.; Lohman, Brooke L.; Tabakh, Daniel B.; Kieweg, Sarah L.; Gehrke, Stevin H.; Berkland, Cory J.; Detamore, Michael S.

2015-01-01

Hydrogels are a promising class of materials for tissue regeneration, but they lack the ability to be molded into a defect site by a surgeon because hydrogel precursors are liquid solutions that are prone to leaking during placement. Therefore, although the main focus of hydrogel technology and developments are on hydrogels in their crosslinked form, our primary focus is on improving the fluid behavior of hydrogel precursor solutions. In this work, we introduce a method to achieve paste-like hydrogel precursor solutions by combining hyaluronic acid nanoparticles with traditional crosslinked hyaluronic acid hydrogels. Prior to crosslinking, the samples underwent rheological testing to assess yield stress and recovery using linear hyaluronic acid as a control. The experimental groups containing nanoparticles were the only solutions that exhibited a yield stress, demonstrating that the nanoparticulate rather than the linear form of hyaluronic acid was necessary to achieve paste-like behavior. The gels were also photocrosslinked and further characterized as solids, where it was demonstrated that the inclusion of nanoparticles did not adversely affect the compressive modulus and that encapsulated bone marrow-derived mesenchymal stem cells remained viable. Overall, this nanoparticle-based approach provides a platform hydrogel system that exhibits a yield stress prior to crosslinking, and can then be crosslinked into a hydrogel that is capable of encapsulating cells that remain viable. This behavior may hold significant impact for hydrogel applications where a paste-like behavior is desired in the hydrogel precursor solution. PMID:25691398

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

NASA Astrophysics Data System (ADS)

Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

Al(OH)3 and Ca(OH)2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. Ca-Al precursor (C3A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO4 LDH product. Ca-Al-CrO4 LDH phase occurred preferentially to Ca-Al-MCl2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist.

Electrodeposition of NiO films from various solvent electrolytic solutions for dye sensitized solar cell application

NASA Astrophysics Data System (ADS)

Koussi-Daoud, S.; Pellegrin, Y.; Odobel, F.; Viana, B.; Pauporté, T.

2017-02-01

We have investigated the preparation of NiO layers by cathodic electrodeposition in various organic-based solvents, namely ethanol, dimethyl sulfoxide (DMSO), DMSO/2 vol.% H2O and DMSO/25 vol.% H2O mixtures. The layers were formed from the electrochemical reduction of nickel nitrate precursor. We show that, depending on the solvent used, various nickel compounds were deposited. In the case of ethanol, a transparent precursor layer was obtained that was transformed into NiO after an annealing treatment at 300°C. For DMSO and DMSO with 2 volume % of H2O, adherent, well-covering, mesoporous and rather thick NiO layers were obtained after an annealing treatment at 450°C. These layers, after growth, contained nickel oxide or hydroxide, metallic nickel and DMSO. The solvent acted as a blowing agent, being included in the deposit and giving rise to a mesoporous film after its elimination by thermal annealing. These porous layers of p-type oxide have been successfully sensitized by a push-pull dye (P1 dye) and showed photocurrent generation and an open circuit voltage (Voc) up to 167 mV in p-type dye-sensitized solar cells (p-DSSCs). For DMSO with 25 volume % of H2O, the deposited layers contained more metallic nickel and were dense even after annealing. They were unsuitable in p-DSSCs.

Metal aminoboranes

DOEpatents

Burrell, Anthony K.; Davis, Benjamin J.; Thorn, David L.; Gordon, John C.; Baker, R. Thomas; Semelsberger, Troy Allen; Tumas, William; Diyabalanage, Himashinie Vichalya Kaviraj; Shrestha, Roshan P.

2010-05-11

Metal aminoboranes of the formula M(NH.sub.2BH.sub.3).sub.n have been synthesized. Metal aminoboranes are hydrogen storage materials. Metal aminoboranes are also precursors for synthesizing other metal aminoboranes. Metal aminoboranes can be dehydrogenated to form hydrogen and a reaction product. The reaction product can react with hydrogen to form a hydrogen storage material. Metal aminoboranes can be included in a kit.

From Metal Thiobenzoates to Metal Sulfide Nanocrystals: An Experimental and Theoretical Investigation

PubMed Central

Zhang, Zhihua; Lim, Wen Pei; Wong, Chiong Teck; Xu, Hairuo; Yin, Fenfang; Chin, Wee Shong

2012-01-01

A simple preparation of metal sulfide nanoparticles via the decomposition of thiobenzoate precursors at room temperature is presented and discussed. Long chain alkylamines were found to mediate the breakdown of metal thiobenzoates, such as those containing Ag, Cu, In and Cd, to produce uniform Ag2S, Cu2−xS, In2S3 and CdS nanoparticles respectively. The long chain amines are assumed to play dual roles as the nucleophilic reagent and the capping agent. It was found that sizes of the nanoparticles can be controlled by changing the type of amine used, as well as the molar ratio between amine and the precursor. We performed DFT calculations on a proposed mechanism involving an initial nucleophilic addition of amine molecule onto the thiocarboxylates. The proposed reaction was also confirmed through the analysis of by-products via infrared spectroscopy. On the basis of this understanding, we propose to manipulate the stability of the precursors by coordination with suitable stabilizing groups, such that the reaction kinetics can be modified to generate different nanostructures of interest. PMID:28348299

Lithium Carbonate Recovery from Cathode Scrap of Spent Lithium-Ion Battery: A Closed-Loop Process.

PubMed

Gao, Wenfang; Zhang, Xihua; Zheng, Xiaohong; Lin, Xiao; Cao, Hongbin; Zhang, Yi; Sun, Zhi

2017-02-07

A closed-loop process to recover lithium carbonate from cathode scrap of lithium-ion battery (LIB) is developed. Lithium could be selectively leached into solution using formic acid while aluminum remained as the metallic form, and most of the other metals from the cathode scrap could be precipitated out. This phenomenon clearly demonstrates that formic acid can be used for lithium recovery from cathode scrap, as both leaching and separation reagent. By investigating the effects of different parameters including temperature, formic acid concentration, H 2 O 2 amount, and solid to liquid ratio, the leaching rate of Li can reach 99.93% with minor Al loss into the solution. Subsequently, the leaching kinetics was evaluated and the controlling step as well as the apparent activation energy could be determined. After further separation of the remaining Ni, Co, and Mn from the leachate, Li 2 CO 3 with the purity of 99.90% could be obtained. The final solution after lithium carbonate extraction can be further processed for sodium formate preparation, and Ni, Co, and Mn precipitates are ready for precursor preparation for cathode materials. As a result, the global recovery rates of Al, Li, Ni, Co, and Mn in this process were found to be 95.46%, 98.22%, 99.96%, 99.96%, and 99.95% respectively, achieving effective resources recycling from cathode scrap of spent LIB.

General Strategy for the Synthesis of Transition-Metal Phosphide/N-Doped Carbon Frameworks for Hydrogen and Oxygen Evolution.

PubMed

Pu, Zonghua; Zhang, Chengtian; Amiinu, Ibrahim Saana; Li, Wenqiang; Wu, Lin; Mu, Shichun

2017-05-17

Transition metal phosphides (TMPs) have been identified as promising nonprecious metal electrocatalyst for hydrogen evolution reaction (HER) and other energy conversion reactions. Herein, we reported a general strategy for synthesis of a series of TMPs (Fe 2 P, FeP, Co 2 P, CoP, Ni 2 P, and Ni 12 P 5 ) nanoparticles (NPs) with different metal phases embedded in a N-doped carbon (NC) matrix using metal salt, ammonium dihydrogen phosphate, and melamine as precursor with varying molar ratios and thermolysis temperatures. The resultant TMPs can serve as highly active and durable bifunctional electrocatalyst toward HER and oxygen evolution reaction (OER). In particular, the Ni 2 P@NC phase only requires an overpotential of ∼138 mV to derive HER in 0.5 M H 2 SO 4, and ∼320 mV for OER in 1.0 M KOH at the current density of 10 mA cm -2 . Because of the encapsulation of NC that can effectively prevent corrosion of embedded TMP NPs, Ni 2 P@NC exhibits almost unfading catalytic performance even after 10 h under both acidic and alkaline solutions. This synthesis strategy provides a new avenue to exploring TMPs as highly active and stable electrocatalyst for the HER, OER, and other electrochemical applications.

Design and synthesis of single-source molecular precursors to homogeneous multi-component oxide materials

NASA Astrophysics Data System (ADS)

Fujdala, Kyle Lee

This dissertation describes the syntheses of single-source molecular precursors to multi-component oxide materials. These molecules possess a core metal or element with various combinations of -OSi(O tBu)3, -O2P(OtBu) 2, and -OB[OSi(OtBu)3] 2 ligands. Such molecules decompose under mild thermolytic conditions (<200°C) to provide homogeneous carbon-free materials via the elimination of isobutylene and water. A gel is formed when thermolyses are performed in non-polar solvents, and subsequent drying of the gel in a conventional manner yields high surface area xerogels. This thermolytic molecular precursor (TMP) approach has been utilized to provide a variety of oxide materials with tailored properties. In addition, the oxygen rich environment of the molecular precursors coupled with the presence of M-O-E heterolinkages permits use of them as models for oxide-supported metal species and multi-component oxides. Significantly, the first complexes to contain three or more heteroelements suitable for use in the TMP method have been synthesized. Compounds for use as single-source molecular precursors have been synthesized containing Al, B, Cr, Hf, Mo, V, W, and Zr, and their thermal transformations have been examined. Heterogeneous catalytic reactions have been examined for selected materials. Also, cothermolyses of molecular precursors and additional molecules (i.e., metal alkoxides) have been utilized to provide materials with several components for potential use as catalysts or catalyst supports. Reactions of one and two equivs of HOSi(OtBu) 3 with Cr(OtBu)4 afforded the first Cr(IV) alkoxysiloxy complexes (tBuO) 3CrOSi(OtBu)3 and ( tBuO)2Cr[OSi(OtBu) 3]2, respectively. The high-yielding, convenient synthesis of (tBuO)3CrOSi(O tBu)3 make this complex a useful single-source molecular precursor, via the TMP method, to Cr/Si/O materials. The thermal transformations of (tBuO)3CrOSi(O tBu)3 and (tBuO) 2Cr[OSi(OtBu)3]2 to chromia-silica materials occurr at low temperatures (≤180°C), to give isobutene as the major carbon-containing product. The material generated from the solid-state conversion of (tBuO) 3CrOSi(OtBu)3 (CrOS ss) has an unexpectedly high surface area of 315 m2 g-1 that is slightly reduced to 275 m2 g-1 after calcination at 500°C in O2. The xerogel obtained by the thermolysis of an n-octane solution of (tBuO)3CrOSi(O tBu)3 (CrOSixg) has a surface area of 315 m2 g-1 that is reduced to 205 m2 g-1 upon calcination at 500°C. Powder X-ray diffraction (PXRD) analysis revealed that Cr2O 3 is the only crystalline species present in CrOSiss and CrOSixg after calcination at temperatures up to 1200°C in O2. (Abstract shortened by UMI.)

Method of making sintered ductile intermetallic-bonded ceramic composites

DOEpatents

Plucknett, K.; Tiegs, T.N.; Becher, P.F.

1999-05-18

A method of making an intermetallic-bonded ceramic composite involves combining a particulate brittle intermetallic precursor with a particulate reactant metal and a particulate ceramic to form a mixture and heating the mixture in a non-oxidizing atmosphere at a sufficient temperature and for a sufficient time to react the brittle intermetallic precursor and the reactant metal to form a ductile intermetallic and sinter the mixture to form a ductile intermetallic-bonded ceramic composite. 2 figs.

Teaching Activities for the Construction of a Precursor Model in 5- to 6-Year-Old Children's Thinking: The Case of Thermal Expansion and Contraction of Metals

ERIC Educational Resources Information Center

Ravanis, Konstantinos; Papandreou, Maria; Kampeza, Maria; Vellopoulou, Angeliki

2013-01-01

This article presents the results of empirical research on the construction of a precursor model of the phenomenon of thermal expansion and contraction of metals in preschool children's thinking, which is compatible with the model used in science education. The research included 87 children aged 5-6. It was conducted at four stages, during…

Time- and energy-efficient solution combustion synthesis of binary metal tungstate nanoparticles with enhanced photocatalytic activity.

PubMed

Thomas, Abegayl; Janáky, Csaba; Samu, Gergely F; Huda, Muhammad N; Sarker, Pranab; Liu, J Ping; van Nguyen, Vuong; Wang, Evelyn H; Schug, Kevin A; Rajeshwar, Krishnan

2015-05-22

In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the most significant effects are highlighted. Each sample's photocatalytic activity towards methyl orange degradation was studied and benchmarked against their respective commercial oxide sample obtained by solid-state ceramic synthesis. Based on the results herein, we conclude that SCS is a time- and energy-efficient method to synthesize crystalline binary tungstate nanomaterials even without additional excessive heat treatment. As many of these photocatalysts possess excellent photocatalytic activity, the discussed synthetic strategy may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Paramagnetic iron-doped hydroxyapatite nanoparticles with improved metal sorption properties. A bioorganic substrates-mediated synthesis.

PubMed

Mercado, D Fabio; Magnacca, Giuliana; Malandrino, Mery; Rubert, Aldo; Montoneri, Enzo; Celi, Luisella; Bianco Prevot, Alessandra; Gonzalez, Mónica C

2014-03-26

This paper describes the synthesis of paramegnetic iron-containing hydroxyapatite nanoparticles and their increased Cu(2+) sorbent capacity when using Ca(2+) complexes of soluble bioorganic substrates from urban wastes as synthesis precursors. A thorough characterization of the particles by TEM, XRD, FTIR spectroscopy, specific surface area, TGA, XPS, and DLS indicates that loss of crystallinity, a higher specific area, an increased surface oxygen content, and formation of surface iron phases strongly enhance Cu(2+) adsorption capacity of hydroxyapatite-based materials. However, the major effect of the surface and morphologycal modifications is the size diminution of the aggregates formed in aqueous solutions leading to an increased effective surface available for Cu(2+) adsorption. Maximum sorption values of 550-850 mg Cu(2+) per gram of particles suspended in an aqueous solution at pH 7 were determined, almost 10 times the maximum values observed for hydroxyapatite nanoparticles suspensions under the same conditions.

Ag(I)-bovine serum albumin hydrosol-mediated formation of Ag3PO4/reduced graphene oxide composites for visible-light degradation of Rhodamine B solution.

PubMed

Ma, Peiyan; Chen, Anliang; Wu, Yan; Fu, Zhengyi; Kong, Wei; Che, Liyuan; Ma, Ruifang

2014-03-01

A cost-effective Ag(I)-bovine serum albumin (BSA) supramolecular hydrosol strategy was utilized to assemble Ag3PO4 nanospheres onto reduced graphene oxide (rGO) sheets. The obtained composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy. Compared with the pure Ag3PO4 crystals and Ag3PO4 particles prepared with Ag(I)-BSA hydrosol as precursor, the Ag3PO4/rGO composites obtained with different content of graphene oxide indicated improved visible-light-driven photocatalysis activity for the decomposition of Rhodamine B aqueous solution. The results pointed to the possibility of synthesizing graphene-based photocatalysts by metal ion-BSA hydrosol. Copyright © 2013 Elsevier Inc. All rights reserved.

PdCuPt Nanocrystals With Multi-branches for Enzyme-free Glucose Detection

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

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua

By carefully controlling the synthesis condition, branched PtCu bimetallic templates were synthesized in aqueous solution. After the galvanic replacement reaction between PtCu templates and the Pt precursors, PdCuPt trimetallic nanocrystals with branched structures were obtained. Owing to the open structure and the optimized composition, the electrochemical experimental results reveal that the PdCuPt trimetallic nanocrystals exhibit high electrocatalytic activity, selectivity and stability for the oxidation of glucose in alkaline solution. In details, a sensitivity of 378 μA/mM/cm2 and a detection limit of 1.29 μM can be achieved. The good electrocatalytic performance should be attributed to the unique branched nanostructure as wellmore » as the synergistic effect among metals. The superior catalytic properties suggest that these nanocrystals are promising for enzyme-free detection of glucose.« less

Efficient One-Pot Synthesis of Colloidal Zirconium Oxide Nanoparticles for High-Refractive-Index Nanocomposites.

PubMed

Liu, Chao; Hajagos, Tibor Jacob; Chen, Dustin; Chen, Yi; Kishpaugh, David; Pei, Qibing

2016-02-01

Zirconium oxide nanoparticles are promising candidates for optical engineering, photocatalysis, and high-κ dielectrics. However, reported synthetic methods for the colloidal zirconium oxide nanoparticles use unstable alkoxide precursors and have various other drawbacks, limiting their wide application. Here, we report a facile one-pot method for the synthesis of colloidally stable zirconium oxide nanoparticles. Using a simple solution of zirconium trifluoroacetate in oleylamine, highly stable zirconium oxide nanoparticles have been synthesized with high yield, following a proposed amidization-assisted sol-gel mechanism. The nanoparticles can be readily dispersed in nonpolar solvents, forming a long-term stable transparent solution, which can be further used to fabricate high-refractive-index nanocomposites in both monolith and thin-film forms. In addition, the same method has also been extended to the synthesis of titanium oxide nanoparticles, demonstrating its general applicability to all group IVB metal oxide nanoparticles.

Effect of Silica Nanoparticles on the Photoluminescence Properties of BCNO Phosphor

NASA Astrophysics Data System (ADS)

Nuryadin, Bebeh W.; Faryuni, Irfana Diah; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal

2011-12-01

Effect of additional silica nanoparticles on the photoluminescence (PL) performance of boron carbon oxy-nitride (BCNO) phosphor was investigated. As a precursor, boric acid and urea were used as boron and nitrogen sources, respectively. The carbon sources was polyethylene glycol (PEG) with average molecule weight 20000 g/mol.. Precursor solutions were prepared by mixing these raw materials in pure water, followed by stirring to achieve homogeneous solutions. In this precursor, silica nanoparticles were added at various mass ratio from 0 to 7 %wt in the solution. The precursors were then heated at 750 °C for 60 min in a ceramic crucible under atmospheric pressure. The photoluminescence (PL) spectrum that characterized by spectrophotometer showed a single, distinct, and broad emission band varied from blue to near red color, depend on the PEG, boric acid and urea ratio in the precursor. The addition of silica nanoparticles caused the increasing of PL intensity as well as the shifting of peak wavelength of PL spectrum. The peak shifting of PL was affected by the concentration of silica nanoparticles that added into the precursor. We believe that the BCNO-silica composite phosphor becomes a promising material for the phosphor conversion-based white light-emitting diodes.

Formation of CuAlO2 Film by Ultrasonic Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Iping, S.; Lockman, Zainovia; Hutagalung, S. D.; Kamsul, A.; Matsuda, Atsunori

2011-10-01

Smooth, crack free and homogenous CuAlO2 film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO3)2.3H2O and 90 mmol Al(NO3)3.9H2O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO2 can be detected for samples prepared by spraying the precursor mist at temperature of > 550 °C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO2.

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring.

PubMed

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Di Leandro, Luana; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-28

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the "double-faced" Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml(-1). Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and "green" routes to 3D reduced GO-metal composite materials.

Porphyrins as Templates for Site-Selective Atomic Layer Deposition: Vapor Metalation and in Situ Monitoring of Island Growth

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

Avila, Jason R.; Emery, Jonathan D.; Pellin, Michael J.

Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analyticalmore » fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials.« less

Metal Ir coatings on endocardial electrode tips, obtained by MOCVD

NASA Astrophysics Data System (ADS)

Vikulova, Evgeniia S.; Kal'nyi, Danila B.; Shubin, Yury V.; Kokovkin, Vasily V.; Morozova, Natalya B.; Hassan, Aseel; Basova, Tamara V.

2017-12-01

The present work demonstrates the application of the Metal-Organic Chemical Vapor Deposition technique to fabricate metal iridium coatings onto the pole tips of endocardial electrodes. Using iridium (III) acetylacetonate as a volatile precursor, the target coatings were successfully applied to the working surface of cathodes and anodes of pacemaker electrodes in the flow type reactor in hydrogen atmosphere at deposition temperature of 550 °C. The coating samples were characterized by means of XRD, SEM, Raman- and XPS-spectroscopies. The formation of non-textured coatings with fractal-like morphology and 7-24 nm crystallite size has been realized. The electrochemical properties of the coatings were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The charge storage capacity values of the electrochemically activated samples were 17.0-115 mC cm-2 and 14.4-76.5 mC cm-2 for measurements carried out in 0.1 M sulfuric acid and in phosphate buffer saline solutions, respectively. A comparison of some characteristics of the samples obtained with commercially available cathode of pacemaker electrodes is also presented.

High-Density Three-Dimension Graphene Macroscopic Objects for High-Capacity Removal of Heavy Metal Ions

PubMed Central

Li, Weiwei; Gao, Song; Wu, Liqiong; Qiu, Shengqiang; Guo, Yufen; Geng, Xiumei; Chen, Mingliang; Liao, Shutian; Zhu, Chao; Gong, Youpin; Long, Mingsheng; Xu, Jianbao; Wei, Xiangfei; Sun, Mengtao; Liu, Liwei

2013-01-01

The chemical vapor deposition (CVD) fabrication of high-density three-dimension graphene macroscopic objects (3D-GMOs) with a relatively low porosity has not yet been realized, although they are desirable for applications in which high mechanical and electrical properties are required. Here, we explore a method to rapidly prepare the high-density 3D-GMOs using nickel chloride hexahydrate (NiCl2·6H2O) as a catalyst precursor by CVD process at atmospheric pressure. Further, the free-standing 3D-GMOs are employed as electrolytic electrodes to remove various heavy metal ions. The robust 3D structure, high conductivity (~12 S/cm) and large specific surface area (~560 m2/g) enable ultra-high electrical adsorption capacities (Cd2+ ~ 434 mg/g, Pb2+ ~ 882 mg/g, Ni2+ ~ 1,683 mg/g, Cu2+ ~ 3,820 mg/g) from aqueous solutions and fast desorption. The current work has significance in the studies of both the fabrication of high-density 3D-GMOs and the removal of heavy metal ions. PMID:23821107

Morphology and stability in a half-metallic ferromagnetic CrO 2 compound of nanoparticles synthesized via a polymer precursor

NASA Astrophysics Data System (ADS)

Biswas, S.; Ram, S.

2004-11-01

Nanoparticles of stable CrO2 of a half-metallic ferromagnet are synthesized with a novel chemical method involving a Cr4+-polymer composite precursor. A single phase CrO2 of D4h 14 : P42 / mnm tetragonal crystal structure (lattice parameters a = 0.4250 and c = 0.3190 nm) lies after firing the precursor at 350 °C for 1 h in air. Microstructure reveals single domain CrO2 particles of thin platelets (aspect ratio ∼1) of average 50 nm diameter and 35 nm thickness. In air, unless heating at temperatures above 500 °C, no due CrO2 → Cr2O3 phase transformation encounters. The results are presented in terms of X-ray diffraction and thermal or thermogravimetric analysis of precursor and derived CrO2 powder.

Transition Metal Dichalcogenide Growth via Close Proximity Precursor Supply

NASA Astrophysics Data System (ADS)

O'Brien, Maria; McEvoy, Niall; Hallam, Toby; Kim, Hye-Young; Berner, Nina C.; Hanlon, Damien; Lee, Kangho; Coleman, Jonathan N.; Duesberg, Georg S.

2014-12-01

Reliable chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) is currently a highly pressing research field, as numerous potential applications rely on the production of high quality films on a macroscopic scale. Here, we show the use of liquid phase exfoliated nanosheets and patterned sputter deposited layers as solid precursors for chemical vapour deposition. TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup. A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented. Raman spectroscopy, photoluminescence, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, scanning electron microscopy and electrical transport measurements reveal the high quality of the TMD samples produced. Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components.

Thermal Studies of New Precursors to Indium-tin Oxides for Use as Sensor Materials in the Detection of NO(x)

NASA Technical Reports Server (NTRS)

Goldsby, J. C.; Kacik, T.; Hockensmith, C. M.

1999-01-01

Control of combustion product emissions in both sub and super-sonic jet engines can be facilitated by measurement of NO(x) levels with metal oxide sensors, In2O3, metal-doped SnO2, and SnO, (as well as other materials) show resistivity changes in the presence of NO(x), but often their sensitivity, stability, and selectivity are low. This study was designed to develop new synthetic pathways to precursors that produce high purity, two phase In2O3-SnO2. The precursors were formed by complexation of tin with any oxide ligands to give the ammonium salt (NH4). Thermal studies of these precursors were carried out by thermal gravimetry (TG) and differential scanning calorimetry (DSC). Further studies by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) were also conducted.

Ultrasound-assisted synthesis and processing of carbon materials

NASA Astrophysics Data System (ADS)

Fortunato, Maria E.

2011-12-01

Part I: Porous carbons are of interest in many applications because of their high surface areas and other physicochemical properties, and much effort has been directed towards developing new methods for controlling the porosity of carbons. Ultrasonic spray pyrolysis (USP) is an aerosol method suitable for large-scale, continuous synthesis of materials. Ultrasound is used to create aerosol droplets of a precursor solution which serve as micron-sized spherical reactors for materials synthesis. This work presents a precursor system for the template-free USP synthesis of porous carbons using low-cost precursors that do not evolve or require hazardous chemicals: sucrose was used as the carbon source, and sodium carbonate, sodium bicarbonate, or sodium nitrate was added as a decomposition catalyst and porogen. The USP carbons had macroporous interiors and microporous shells with surface areas as high as 800 m2/g and a narrow pore size distribution. It was determined that the interior porosity was a result of the gas evolution from salt decomposition and not from the presence of a salt template. Porous carbon is frequently used as a catalyst support because it provides high surface area and it is chemically and physically stable under many anoxic reaction conditions. Typically, the preparation of supported catalysts requires multiple steps for carbonization and metal impregnation. In this work, iron-impregnated porous carbon microspheres (Fe-C) were prepared by a one-step USP process by incorporating both the carbon and metal sources into the precursor solution. Carbonization, pore formation, metal impregnation, and metal activation occurred simultaneously to produce Fe-C materials with surface areas as high as 800 m2/g and up to 10 wt% Fe incorporated as nanoparticles < 20 nm in diameter. Fe-C was used as a catalyst to reduce aqueous hexavalent chromium, which demonstrated the accessibility of the iron nanoparticles despite the fact that they are likely encapsulated in the porous carbon support. Part II: The effects of high intensity ultrasound arise from acoustic cavitation: the formation, growth, and collapse of bubbles in a liquid. Bubble collapse produces intense localized heating (˜5000 K), high pressures (˜300 atm), and enormous heating and cooling rates (>109 K/sec). In solid-liquid slurries, surface erosion and particle fracture occur due to the shockwaves and microjets formed from asymmetric bubble collapse at extended surfaces. The chemical and physical effects of ultrasound have been studied as an adjunct to the traditional chemical pretreatment of lignocellulosic biomass for ethanol production. Lignocellulosic biomass consists of cellulose, hemicellulose, and lignin. The surface effects of ultrasound were used in this work to increase the accessibility of the cellulose, which can be converted to glucose and then fermented into ethanol. The lignocellulosic biomass used in this work was Miscanthus x giganteus (Mxg) which was grown at the University of Illinois at Urbana-Champaign. The chemical effects of NaOH pretreatment on Mxg were enhanced by ultrasound: greater delignification and a significant increase in the amount of pores >5 nm were observed. ˜ 70% of the theoretical glucose yield was obtained by enzymatic saccharification of the ultrasound-assisted NaOH-pretreated Mxg; this is comparable to the yields that can be obtained by traditional alkaline pretreatments, but it was achieved in a shorter time and at a lower temperature. Because the apparatus used for laboratory studies is not a likely device for scale-up, the economics of ultrasound with regards to energy balance are not yet resolved.

Synthesis, characterization and biological assay of Salicylaldehyde Schiff base Cu(II) complexes and their precursors

NASA Astrophysics Data System (ADS)

Iftikhar, Bushra; Javed, Kanwal; Khan, Muhammad Saif Ullah; Akhter, Zareen; Mirza, Bushra; Mckee, Vickie

2018-03-01

Three new Schiff base ligands were synthesized by the reaction of Salicylaldehyde with semi-aromatic diamines, prepared by the reduction of corresponding dinitro-compounds, and were further used for the formation of complexes with Cu(II) metal ion. The structural features of the synthesized compounds were confirmed by their physical properties and infrared, electronic and NMR spectroscopic techniques. The studies revealed that the synthesized Schiff bases existed as tetradentate ligands and bonded to the metal ion through the phenolic oxygen and azomethine nitrogen. One of the dinitro precursors was also analyzed by single crystal X-ray crystallography, which showed that it crystallizes in monoclinic system with space group P2/n. The thermal behavior of the Cu(II) complexes was determined by thermogravimetric analysis (TGA) and kinetic parameters were evaluated from the data. Schiff base ligands, their precursors and metal complexes were also screened for antibacterial, antifungal, antitumor, Brine shrimp lethality, DPPH free radical scavenging and DNA damage assays. The results of these analyses indicated the substantial potential of the synthesized Schiff bases, their precursors and Cu(II) complexes in biological field as future drugs.

Fabricating Large-Area Sheets of Single-Layer Graphene by CVD

NASA Technical Reports Server (NTRS)

Bronikowski, Michael; Manohara, Harish

2008-01-01

This innovation consists of a set of methodologies for preparing large area (greater than 1 cm(exp 2)) domains of single-atomic-layer graphite, also called graphene, in single (two-dimensional) crystal form. To fabricate a single graphene layer using chemical vapor deposition (CVD), the process begins with an atomically flat surface of an appropriate substrate and an appropriate precursor molecule containing carbon atoms attached to substituent atoms or groups. These molecules will be brought into contact with the substrate surface by being flowed over, or sprayed onto, the substrate, under CVD conditions of low pressure and elevated temperature. Upon contact with the surface, the precursor molecules will decompose. The substituent groups detach from the carbon atoms and form gas-phase species, leaving the unfunctionalized carbon atoms attached to the substrate surface. These carbon atoms will diffuse upon this surface and encounter and bond to other carbon atoms. If conditions are chosen carefully, the surface carbon atoms will arrange to form the lowest energy single-layer structure available, which is the graphene lattice that is sought. Another method for creating the graphene lattice includes metal-catalyzed CVD, in which the decomposition of the precursor molecules is initiated by the catalytic action of a catalytic metal upon the substrate surface. Another type of metal-catalyzed CVD has the entire substrate composed of catalytic metal, or other material, either as a bulk crystal or as a think layer of catalyst deposited upon another surface. In this case, the precursor molecules decompose directly upon contact with the substrate, releasing their atoms and forming the graphene sheet. Atomic layer deposition (ALD) can also be used. In this method, a substrate surface at low temperature is covered with exactly one monolayer of precursor molecules (which may be of more than one type). This is heated up so that the precursor molecules decompose and form one monolayer of the target material.

Multi-layer articles and methods of making same

DOEpatents

Fritzemeier, Leslie G.; Zhang, Wei; Palm, Walter C.; Rupich, Martin W.

2005-05-17

The invention relates to superconductor articles, and compositions and methods for making superconductor articles. The methods can include using a precursor solution having a relatively small concentration of total free acid. The articles can include more than one layer of superconductor material in which at least one layer of superconductor material can be formed by a solution process, such as a solution process involving the use of metalorganic precursors.

Preparation of Sic/AIN Solid Solutions Using Organometallic Precursors

DTIC Science & Technology

1989-02-15

pyrolysis of organoaluminum and organosilicon compounds was investigated as a potential source of SiC /AUI solid solutions. Using two different co... pyrolysis methods, homogeneous mixtures of organoaluminum amides and both a vinylic polysilane and a poly- carbosilane were convertec to a preceramic ...solid that transformed to crystalline SiC /AiN solid solutions at 򒸀 C. Moreover, the liquid, polymeric , form of these precursor mixtures provides a

Template-Free Synthesis of Nanoporous Nickel and Alloys as Binder-Free Current Collectors of Li Ion Batteries.

PubMed

Lu, Liqiang; Andela, Paul; De Hosson, Jeff Th M; Pei, Yutao

2018-05-25

This paper reports a versatile template-free method based on the hydrogen reduction of metallic salts for the synthesis of nanoporous Ni and alloys. The approach involves thermal decomposition and reduction of metallic precursors followed with metal cluster nucleation and ligament growth. Topological disordered porous architectures of metals with a controllable distribution of pore size and ligament size ranging from tens of nanometers to micrometers are synthesized. The reduction processes are scrutinized through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The formation mechanism of the nanoporous metal is qualitatively explained. The as-prepared nanoporous Ni was tested as binder-free current collectors for nickel oxalate anodes of lithium ion batteries. The nanoporous Ni electrodes deliver enhanced reversible capacities and cyclic performances compared with commercial Ni foam. It is confirmed that this synthesis method has versatility not only because it is suitable for different types of metallic salts precursors but also for various other metals and alloys.

Template-Free Synthesis of Nanoporous Nickel and Alloys as Binder-Free Current Collectors of Li Ion Batteries

PubMed Central

2018-01-01

This paper reports a versatile template-free method based on the hydrogen reduction of metallic salts for the synthesis of nanoporous Ni and alloys. The approach involves thermal decomposition and reduction of metallic precursors followed with metal cluster nucleation and ligament growth. Topological disordered porous architectures of metals with a controllable distribution of pore size and ligament size ranging from tens of nanometers to micrometers are synthesized. The reduction processes are scrutinized through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The formation mechanism of the nanoporous metal is qualitatively explained. The as-prepared nanoporous Ni was tested as binder-free current collectors for nickel oxalate anodes of lithium ion batteries. The nanoporous Ni electrodes deliver enhanced reversible capacities and cyclic performances compared with commercial Ni foam. It is confirmed that this synthesis method has versatility not only because it is suitable for different types of metallic salts precursors but also for various other metals and alloys. PMID:29911687

Quantitation and localization of intracellular redox active metals by X-ray fluorescence microscopy in cortical neurons derived from APP and APLP2 knockout tissue

DOE PAGES

Ciccotosto, Giuseppe D.; James, Simon A.; Altissimo, Matteo; ...

2014-10-01

The amyloid precursor protein (APP) gene family includes APP and the amyloid precursor-like proteins, APLP1 and APLP2. These proteins contain metal binding sites for copper, zinc and iron and are known to have physiological roles in modulating the metal homeostasis in brain cells. Here we report the application of X-ray fluorescence microscopy (XFM) to investigate the subcellular distribution patterns of the metal ions Cu, Zn, Fe, and Ca in individual neurons derived from APP and APLP2 knockout mice brains to further define their role in metal homeostasis. These studies add to the growing body of data that the APP familymore » of proteins are metalloproteins that have shared as well as distinct effects on metals. As we continue to delineate the cellular effects of the APP family of proteins it is important to consider how metals are involved in their actions.« less

Seed-induced growth of flower-like Au-Ni-ZnO metal-semiconductor hybrid nanocrystals for photocatalytic applications.

PubMed

Chen, Yuanzhi; Zeng, Deqian; Cortie, Michael B; Dowd, Annette; Guo, Huizhang; Wang, Junbao; Peng, Dong-Liang

2015-03-25

The combination of metal and semiconductor components in nanoscale to form a hybrid nanocrystal provides an important approach for achieving advanced functional materials with special optical, magnetic and photocatalytic functionalities. Here, a facile solution method is reported for the synthesis of Au-Ni-ZnO metal-semiconductor hybrid nanocrystals with a flower-like morphology and multifunctional properties. This synthetic strategy uses noble and magnetic metal Au@Ni nanocrystal seeds formed in situ to induce the heteroepitaxial growth of semiconducting ZnO nanopyramids onto the surface of metal cores. Evidence of epitaxial growth of ZnO{0001} facets on Ni {111} facets is observed on the heterojunction, even though there is a large lattice mismatch between the semiconducting and magnetic components. Adjustment of the amount of Au and Ni precursors can control the size and composition of the metal core, and consequently modify the surface plasmon resonance (SPR) and magnetic properties. Room-temperature superparamagnetic properties can be achieved by tuning the size of Ni core. The as-prepared Au-Ni-ZnO nanocrystals are strongly photocatalytic and can be separated and re-cycled by virtue of their magnetic properties. The simultaneous combination of plasmonic, semiconducting and magnetic components within a single hybrid nanocrystal furnishes it multifunctionalities that may find wide potential applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation of well-adhered ZrO2 layers produced on structured reactors using the sonochemical sol-gel method

NASA Astrophysics Data System (ADS)

Jodłowski, Przemysław J.; Chlebda, Damian K.; Jędrzejczyk, Roman J.; Dziedzicka, Anna; Kuterasiński, Łukasz; Sitarz, Maciej

2018-01-01

The aim of this study was to obtain thin zirconium dioxide coatings on structured reactors using the sonochemical sol-gel method. The preparation method of metal oxide layers on metallic structures was based on the synergistic combination of three approaches: the application of ultrasonic irradiation during the synthesis of Zr sol-gel based on a precursor solution containing zirconium(IV) n-propoxide, the addition of stabilszing agents, and the deposition of ZrO2 on the metallic structures using the dip-coating method. As a result, dense, uniform zirconium dioxide films were obtained on the FeCrAlloy supports. The structured reactors were characterised by various physicochemical methods, such as BET, AFM, EDX, XRF, XRD, XPS and in situ Raman spectroscopy. The results of the structural analysis by Raman and XPS spectroscopy confirmed that the metallic surface was covered by a ZrO2 layer without any impurities. SEM/EDX mapping revealed that the deposited ZrO2 covered the metallic support uniformly. The mechanical and high temperature tests showed that the developed ultrasound assisted sol-gel method is an efficient way to obtain thin, well-adhered zirconium dioxide layers on the structured reactors. The prepared metallic supports covered with thin ZrO2 layers may be a good alternative to layered structured reactors in several dynamics flow processes, for example for gas exhaust abatement.

Synthesis of GaN:ZnO solid solution by solution combustion method and characterization for photocatalytic application

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

Menon, Sumithra Sivadas; Anitha, R.; Baskar, K.

2016-05-23

GaN-ZnO solid solution has emerged as a successful and reproducible photocatalyst for overall water splitting by one-step photoexcitation, with a bandgap in visible region. When the solid solution is formed, some of the Zn and O ions are replaced by Ga and N ions respectively and there is a narrowing of bandgap which is hypothesized as due to Zn3d-N2p repulsion. The traditional method of synthesis of GaN-ZnO solid solution is by nitridation of the starting oxides under constant ammonia flow. Here we report a solution combustion technique for the synthesis of the solid solution at a temperature about 500 °more » C in a muffle furnace with metal nitrates as precursors and urea as the fuel. The as prepared samples showed change in color with the increased concentration of ZnO in the solution. The structural, microstructural, morphological and optical properties of the samples were realized by Powder X ray diffraction, Scanning electron microscopy, Energy dispersive X ray analysis, Transmission electron microscopy and Photoluminescence. Finally the hydrogen production efficiency of the GaN-ZnO nanopowders by water splitting was found, using methanol as a scavenger. The apparent quantum yield (AQY) of 0.048% is obtained for GaN-ZnO solid solution.« less

Non-noble electrocatalysts for alkaline fuel cells

NASA Technical Reports Server (NTRS)

Sarangapani, S.; Lessner, P.; Manoukian, M.; Giner, J.

1989-01-01

Carbons activated with macrocyclics have attracted increasing attention as alternative electrocatalysts for oxygen reduction. Initial activity of these catalysts is good, but performance declines rapidly. Pyrolyzing the macrocyclic on the carbon support leads to enhanced stability and the catalysts retain good activity. The approach described is designed to develop bulk doped catalysts with similar structures to pyrolyzed macrocyclic catalysts. The transition metal and coordinated ligands are dispersed throughout the bulk of the conductive carbon skeleton. Two approaches to realizing this concept are being pursued, both involving the doping of carbon precursors. In one approach, the precursor is a solid phase carbon-containing ion-exchange resin. The precursor is doped with a transition metal and/or nitrogen, and the resulting mixture is pyrolyzed. In the other approach, the precursor is a gas-phase hydrocarbon. This is introduced with a transition metal species and nitrogen species into a reactor and pyrolyzed. Several studies have been conducted to determine if there is a synergistic effect between the transition metal and nitrogen and the effect of different methods of introducing the metal-nitrogen (M-N) coordination on performance. One approach was to introduce the metal and nitrogen separately, for example, by sequentially doping FeCl3 and NH4OH into the resin. Catalysts were prepared from an undoped ion-exchange resin, a resin doped only with N, a resin doped only with Fe, and a resin doped with both Fe and N. Introduction of nitrogen alone has no beneficial effect on the performance of the catalysts. The introduction of the Fe alone significantly improves the performance in both the high and low current density regions. When both Fe and N are introduced, the performance at lower current densities (catalytic activity) is increased beyond that of the Fe-doped carbon, but the performance at higher current densities is similar to the carbon containing only Fe. Catalysts prepared from resins-Fe(bipy)3SO4 precursors have performance that is only slightly less then CoTMPP adsorbed and pyroloyzed on Vulcan XC-72. Their performance is much better than carbons which have had the N and Fe introduced separately.

Nanoceramic -Metal Matrix Composites by In-Situ Pyrolysis of Organic Precursors in a Liquid Melt

NASA Astrophysics Data System (ADS)

Sudarshan; Surappa, M. K.; Ahn, Dongjoon; Raj, Rishi

2008-12-01

We show the feasibility of introducing a dispersion of a refractory ceramic phase into metals by stirring a powder of an organic polymer into a magnesium melt and having it convert into a ceramic within the melt by in-situ pyrolysis of the polymer. The pyrolysis is a highly reactive process, accompanied by the evolution of hydrogen, which disperses the ceramic phase into nanoscale constituents. In the present experiments, a polysilazane-based precursor, which is known to yield an amorphous ceramic constituted from silicon, carbon, and nitrogen, was used. Five weight percent of the precursor (which has a nominal ceramic yield of 75 to 85 wt pct) produced a twofold increase in the room-temperature yield strength and reduced the steady-state strain rate at 450 °C by one to two orders of magnitude, relative to pure magnesium. This polymer-based in-situ process (PIP) for processing metal-matrix composites (MMCs) is likely to have great generality, because many different kinds of organic precursors, for producing oxide, carbides, nitrides, and borides, are commercially available. Also, the process would permit the addition of large volume fractions of the ceramic, enabling the nanostructural design, and production of MMCs with a wide range of mechanical properties, meant especially for high-temperature applications. An important and noteworthy feature of the present process, which distinguishes it from other methods, is that all the constituents of the ceramic phase are built into the organic molecules of the precursor ( e.g., polysilazanes contain silicon, carbon, and nitrogen); therefore, a reaction between the polymer and the host metal is not required to produce the dispersion of the refractory phase.

La-Sr-Ni-Co-O based perovskite-type solid solutions as catalyst precursors in the CO 2 reforming of methane

NASA Astrophysics Data System (ADS)

Valderrama, Gustavo; Kiennemann, Alain; Goldwasser, Mireya R.

La 1- xSr xNi 0.4Co 0.6O 3 and La 0.8Sr 0.2Ni 1- yCo yO 3 solid solutions with perovskite-type structure were synthesized by the sol-gel resin method and used as catalytic precursors in the dry reforming of methane with CO 2 to syngas, between 873 and 1073 K at atmospheric pressure under continuous flow of reactant gases with CH 4/CO 2 = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La 0.9Sr 0.1CoO 3 and/or La 0.9Sr 0.1NiO 3 as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni 0, Co 0 with particle sizes in the range of nanometers over the SrO and La 2O 3 phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water-gas shift in a very small extension during the dry reforming reaction.

Low-temperature liquid precursors of crystalline metal oxides assisted by heterogeneous photocatalysis.

PubMed

Bretos, Iñigo; Jiménez, Ricardo; Pérez-Mezcua, Dulce; Salazar, Norberto; Ricote, Jesús; Calzada, M Lourdes

2015-04-24

The photocatalytically assisted decomposition of liquid precursors of metal oxides incorporating TiO2 particles enables the preparation of functional layers from the ferroelectric Pb(Zr,Ti)O3 and multiferroic BiFeO3 perovskite systems at temperatures not exceeding 350 ºC. This enables direct deposition on flexible plastic, where the multifunctionality provided by these complex-oxide materials guarantees their potential use in next-generation flexible electronics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Photoluminescence Characteristics of Eu(3+)-Doped Molybdates Nanocrystals.

PubMed

Li, Fuhai; Yu, Lixin; Wei, Shuilin; Sun, Jiaju; Chen, Weiqing; Sun, Wei

2015-12-01

In this paper, the Eu(3+)-doped molybdate (CaMoO4, ZnMoO4 and BaMoO4) phosphors have been prepared by a hydrothermal method through modulating the pH value of the precursor solution (pH = 8, 10, and 12, respectively). The crystalline phase, morphology, photoluminescent properties of the prepared samples were systematically characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectra. The results indicate that the photoluminescence and morphology can be affected by the precursor solution. And the growth of the ZnMoO4 crystals also can be affected by the pH value of the precursor solution.

High rate capability of a BaTiO3-decorated LiCoO2 cathode prepared via metal organic decomposition

NASA Astrophysics Data System (ADS)

Teranishi, Takashi; Katsuji, Naoto; Yoshikawa, Yumi; Yoneda, Mika; Hayashi, Hidetaka; Kishimoto, Akira; Yoda, Koji; Motobayashi, Hidefumi; Tasaki, Yuzo

2016-10-01

Metal organic decomposition (MOD) using octylic acid salts was applied to synthesize a BaTiO3-LiCoO2 (BT-LC) composite powder. The Ba and Ti octylates were utilized as metal precursors, in an attempt to synthesize homogeneous BT nanoparticles on the LC matrix. The BT-LC composite, having a phase-separated composite structure without any impurity phase, was successfully obtained by optimizing the MOD procedure. The composite prepared using octylate precursors exhibited a sharper distribution and better dispersibility of decorated BT particles. Additionally, the average particle size of the decorated BTs using metal octylate was reduced to 23.3 nm, compared to 44.4 nm from conventional processes using Ba acetate as well as Ti alkoxide as precursors. The composite cathode displayed better cell performance than its conventional counterpart; the discharge capacity of the metal octylate-derived specimen was 55.6 mAh/g at a 50C rate, corresponding to 173% of the capacity of the conventional specimen (32.2 mAh/g). The notable improvement in high rate capability obtained in this study, compared with the conventional route, was attributed to the higher density of the triple junction formed by the BT-LC-electrolyte interface.

One-step synthesis of dithiocarbamates from metal powders

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Hehemann, David G.; Duraj, Stan A.; Clark, Eric B.; Eckles, William E.; Fanwick, Phillip E.

1994-01-01

Neutral metal dithiocarbamate complexes (M(NR2CS2)X) are well-known precursors to metal sulfides, a class of materials with numerous technological applications. We are involved in a research effort to prepare new precursors to metal sulfides using simple, reproducible synthetic procedures. We describe the results of our synthetic and characterization studies for M = Fe, Co, Ni, Cu. and In. For example, treatment of metallic indium with tetramethylthiuram disulfide (tmtd) in 4-methylpyridine (4-Mepy) at 25 deg C produces a new homoleptic indium (III) dithiocarbamate, In(N(CH3)2CS2)3(I), in yields of over 60 percent. The indium (III) dithiocarbamate was characterized by X-ray crystallography; (I) exists in the solid state as discrete distorted-octahedral molecules. Compound (I) crystallizes in the P1bar (No. 2) space group with lattice parameters: a = 9.282(1) A, b = 10.081(1) A, c = 12.502 A, alpha = 73.91(1) deg, beta = 70.21(1) deg, gamma = 85.8(1)deg, and Z = 2. X-ray diffraction and mass spectral data were used to characterize the products of the analogous reactions with Fe, Co, Ni, and Cu. We discuss both use of dithiocarbamates as precursors and our approach to their preparation.

Micro-structural evolution and biomineralization behavior of carbon nanofiber/bioactive glass composites induced by precursor aging time.

PubMed

Jia, Xiaolong; Tang, Tianhong; Cheng, Dan; Zhang, Cuihua; Zhang, Ran; Cai, Qing; Yang, Xiaoping

2015-12-01

Bioactive glass (BG)-containing carbon nanofibers (CNFs) are promising orthopaedic biomaterials. Herein, CNF composites were produced from electrospinning of polyacrylonitrile (PAN)/BG sol-gel precursor solution, followed by carbonization. Choosing 58S-type BG (mol%: 58.0% SiO2-26.3% CaO-15.7% P2O5) as the model, micro-structural evolution of CNF/BG composites was systematically evaluated in relating to aging times of BG precursor solution. With aging time prolonging, BG precursors underwent morphological changes from small sol clusters with loosely and randomly branched structure to highly crosslinked Si-network structure, showing continuous increase in solution viscosity. BG precursor solution with low viscosity could mix well with PAN solution, resulting in CNF composite with homogeneously distributed BG component. Whereas, BG precursor gel with densely crosslinked Si-network structure led to uneven distribution of BG component along final CNFs due to its significant phase separation from PAN component. Meanwhile, BG nanoparticles in CNFs demonstrated micro-structural evolution that they transited from weak to strong crystal state along with longer aging time. Biomineralization in simulated body fluid and in vitro osteoblasts proliferation were then applied to determine the bioactivity of CNF/BG composites. CNF/BG composites prepared from shorter aging time could induce both faster apatite deposition and cell proliferation rate. It was suggested weakly crystallized BG nanoparticles along CNFs dissolved fast and was able to provide numerous nucleation sites for apatite deposition, which also favored the proliferation of osteoblasts cells. Aging time could thus be a useful tool to regulate the biological features of CNF/BG composites. Copyright © 2015 Elsevier B.V. All rights reserved.

Stabilizing cadmium into aluminate and ferrite structures: Effectiveness and leaching behavior.

PubMed

Su, Minhua; Shih, Kaimin; Kong, Lingjun

2017-02-01

The inappropriate disposal of sludge, particularly for those enriched in heavy metals, is highly hazardous to the environment. Thermally converting sludge into useful products is a highly promising technique as heavy metals are immobilized and organic substances are mineralized. This work investigated the feasibility of stabilizing simulated cadmium-laden sludge by sintering with Al-and Fe-rich precursors. To simulate the process, cadmium oxide was alternatively mixed and sintered with γ-Al 2 O 3 and α-Fe 2 O 3 . Cadmium was crystallographically incorporated into aluminate (CdAl 4 O 7 ) monoclinic structure and ferrite (CdFe 2 O 4 ) spinel, dependent on the type of precursor used. The CdFe 2 O 4 formation was initialed at about 150-300 °C lower than that of CdAl 4 O 7 . With Rietveld refinement analysis of the collated XRD data, the weight percentages of crystalline phases in the fired samples were quantified. To evaluate the cadmium incorporation efficiency, a transformation ratio (TR) index was devised. The TR values revealed that, to effectively incorporate cadmium, 950 °C was favored by γ-Al 2 O 3 and 850 °C was for α-Fe 2 O 3 within a 3-h sintering treatment. Constant pH leaching test (CPLT) was used to assess the metal stabilization effects, revealing a remarkable reduction of cadmium by transformation into CdAl 4 O 7 and CdFe 2 O 4 . Both CdAl 4 O 7 and CdFe 2 O 4 were incongruently dissolved in an acid solution. The overall finding indicated a potentially feasible technology in cadmium-laden sludge stabilization. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Taha, Mohd F., E-mail: faisalt@petronas.com.my; Shaharun, Maizatul S.; Shuib, Anis Suhaila, E-mail: anisuha@petronas.com.my

An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHNmore » elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m{sup 2}/g and 0.17 cm{sup 2}/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models.« less

Method for synthesizing carbon nanotubes

DOEpatents

Fan, Hongyou

2012-09-04

A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

Radiochemical synthesis of a carbon-supported Pt-SnO2 bicomponent nanostructure exhibiting enhanced catalysis of ethanol oxidation

NASA Astrophysics Data System (ADS)

Okazaki, Tomohisa; Seino, Satoshi; Nakagawa, Takashi; Kugai, Junichiro; Ohkubo, Yuji; Akita, Tomoki; Nitani, Hiroaki; Yamamoto, Takao A.

2015-03-01

Carbon-supported Pt-SnO2 electrocatalysts with various Sn/Pt molar ratios were prepared by an electron beam irradiation method. These catalysts were composed of metallic Pt particles approximately 5 nm in diameter together with low crystalline SnO2. The contact between the Pt and SnO2 in these materials varied with the amount of dissolved oxygen in the precursor solutions and it was determined that intimate contact between the Pt and SnO2 significantly enhanced the catalytic activity of these materials during the ethanol oxidation reaction. The mechanism by which the contact varies is discussed based on the radiochemical reduction process.

Biosynthesis of silver and platinum nanoparticles using orange peel extract: characterisation and applications.

PubMed

Castro, Laura; Blázquez, María Luisa; González, Felisa; Muñoz, Jesús Ángel; Ballester, Antonio

2015-10-01

This study focuses on the green synthesis of noble metal nanoparticles (silver (Ag) and platinum (Pt)) and how the size and shape of the nanoparticles produced can be controlled through changes in the initial pH value of the precursor solution. The nanoparticles were characterised by ultra-violet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. This simple and environmentally friendly method allows the synthesis of diverse nanostructures in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally adding seed crystallites. The antibacterial effects of Ag nanoparticles and catalytic properties of Pt nanoparticles were explored for future promising biotechnological approaches in different fields.

One-step synthesis of 2D-layered carbon wrapped transition metal nitrides from transition metal carbides (MXenes) for supercapacitors with ultrahigh cycling stability.

PubMed

Yuan, Wenyu; Cheng, Laifei; Wu, Heng; Zhang, Yani; Lv, Shilin; Guo, Xiaohui

2018-03-13

A novel one-step method to synthesize 2D carbon wrapped TiN (C@TiN) was proposed via using 2D metal carbides (MXenes) as precursors. This study provides a novel approach to synthesize carbon wrapped metal nitrides.

Sol-Gel Processing of MgF₂ Antireflective Coatings.

PubMed

Löbmann, Peer

2018-05-02

There are different approaches for the preparation of porous antireflective λ/4 MgF₂ films from liquid precursors. Among these, the non-aqueous fluorolytic synthesis of precursor solutions offers many advantages in terms of processing simplicity and scalability. In this paper, the structural features and optical performance of the resulting films are highlighted, and their specific interactions with different inorganic substrates are discussed. Due to their excellent abrasion resistance, coatings have a high potential for applications on glass. Using solvothermal treatment of precursor solutions, also the processing of thermally sensitive polymer substrates becomes feasible.

Toughened and corrosion- and wear-resistant composite structures and fabrication methods thereof

DOEpatents

Seals, Roland D; Ripley, Edward B; Hallman, Russell L

2014-04-08

Composite structures having a reinforced material interjoined with a substrate and methods of creating a composite material interjoined with a substrate. In some embodiments the composite structure may be a line or a spot or formed by reinforced material interjoined with the substrate. The methods typically include disposing a precursor material comprising titanium diboride and/or titanium monoboride on at least a portion of the substrate and heating the precursor material and the at least a portion of the substrate in the presence of an oxidation preventative until at least a portion of the precursor material forms reinforced material interjoined with the substrate. The precursor material may be disposed on the substrate as a sheet or a tape or a slurry or a paste. Localized surface heating may be used to heat the precursor material. The reinforced material typically comprises a titanium boron compound, such as titanium monoboride, and preferably comprises .beta.-titanium. The substrate is typically titanium-bearing, iron-bearing, or aluminum-bearing. A welding rod is provided as an embodiment. The welding rod includes a metal electrode and a precursor material is disposed adjacent at least a portion of the metal electrode. A material for use in forming a composite structure is provided. The material typically includes a precursor material that includes one or more materials selected from the following group: titanium diboride and titanium monoboride. The material also typically includes a flux.

Cobalt- and iron-based nanoparticles hosted in SBA-15 mesoporous silica and activated carbon from biomass: Effect of modification procedure

NASA Astrophysics Data System (ADS)

Tsoncheva, Tanya; Genova, Izabela; Paneva, Daniela; Dimitrov, Momtchil; Tsyntsarski, Boyko; Velinov, Nicolay; Ivanova, Radostina; Issa, Gloria; Kovacheva, Daniela; Budinova, Temenujka; Mitov, Ivan; Petrov, Narzislav

2015-10-01

Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV-Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

Effect of pH on film structure and electrical property of PMMA-Au composite particles prepared by redox transmetalation

NASA Astrophysics Data System (ADS)

Wu, Hong-Mao; Lin, Kuan-Ju; Yu, Yi-Hsiuan; Ho, Chan-Yuan; Wei, Ming-Hsiung; Lu, Fu-Hsing; Tseng, Wenjea J.

2014-01-01

Surface-selective deposition of gold (Au) on electroless plated poly(methyl methacrylate)-nickel (PMMA-Ni) beads was prepared chemically by a facile redox-transmetalation route in which the Ni atoms on the PMMA surface were reacted with Au precursors, i.e., chloroauric acid (HAuCl4), in water to form predominately core-shell PMMA-Au composite particles without the need of reducing agent. The Ni layer acted as a sacrificial template to facilitate the selective transmetalation deposition of a metallic Au film. When pH of the precursor solution was adjusted from 6 to 9, morphology of the Au film changed from a uniform particulate film consisting of assemblies of Au nanoparticles, to densely packed, continuous film with platelet Au crystals, and finally to isolated Au islands on the PMMA surface with a raspberry-like core-shell morphology. Uniformly dense Au coating with a thickness of about 200 nm was formed on the PMMA beads at pH of 7 to 8, which gave rise to an electrical resistivity as low as 3 × 10-2 Ω cm.

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

Xu, Wu; Canfield, Nathan L.; Zhang, Ji-Guang

Methods for making composite anodes, such as macroporous composite anodes, are disclosed. Embodiments of the methods may include forming a tape from a slurry including a substrate metal precursor, an anode active material, a pore-forming agent, a binder, and a solvent. A laminated structure may be prepared from the tape and sintered to produce a porous structure, such as a macroporous structure. The macroporous structure may be heated to reduce a substrate metal precursor and/or anode active material. Macroporous composite anodes formed by some embodiments of the disclosed methods comprise a porous metal and an anode active material, wherein themore » anode active material is both externally and internally incorporated throughout and on the surface of the macroporous structure.« less

Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

PubMed Central

Connal, Luke A.; Lynd, Nathaniel A.; Robb, Maxwell J.; See, Kimberly A.; Jang, Se Gyu; Spruell, Jason M.

2012-01-01

We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, while the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained. PMID:23335837

Infiltration processing of boron carbide-, boron-, and boride-reactive metal cermets

DOEpatents

Halverson, Danny C.; Landingham, Richard L.

1988-01-01

A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

Method for preparing metallated filament-wound structures

DOEpatents

Peterson, George R.

1979-01-01

Metallated graphite filament-wound structures are prepared by coating a continuous multi-filament carbon yarn with a metal carbide, impregnating the carbide coated yarn with a polymerizable carbon precursor, winding the resulting filament about a mandrel, partially curing the impregnation in air, subjecting the wound composite to heat and pressure to cure the carbon precursor, and thereafter heating the composite in a sizing die at a pressure loading of at least 1000 psi for graphitizing the carbonaceous material in the composite. The carbide in the composite coalesces into rod-like shapes which are disposed in an end-to-end relationship parallel with the filaments to provide resistance to erosion in abrasive laden atmospheres.

Volatile organometallic complexes suitable for use in chemical vapor depositions on metal oxide films

DOEpatents

Giolando, Dean M.

2003-09-30

Novel ligated compounds of tin, titanium, and zinc are useful as metal oxide CVD precursor compounds without the detriments of extreme reactivity yet maintaining the ability to produce high quality metal oxide coating by contact with heated substrates.

Metal complexes of alkyl-aryl dithiocarbamates: Structural studies, anticancer potentials and applications as precursors for semiconductor nanocrystals

NASA Astrophysics Data System (ADS)

Andrew, Fartisincha P.; Ajibade, Peter A.

2018-03-01

Dithiocarbamates are versatile ligands able to stabilize wide range of metal ions in their various oxidation states with the partial double bond character of Csbnd N and Csbnd S of thioureide moiety. Variation of the substituents attached to the nitrogen atom of dithiocarbamate moiety generates various intermolecular interactions, which lead to different structural arrangement in the solid state. The presence of bulky substituents on the N atom obviates the supramolecular aggregation via secondary Msbnd S interactions whereas smaller substituents encourage such aggregation that results in their wide properties and applications. Over the past decades, the synthesis and structural studies of metal complexes of dithiocarbamates have received considerable attention as potential anticancer agents with various degree of DNA binding affinity and cytotoxicity and as single molecule precursors for the preparation of semiconductor nanocrystals. In this paper, we review the synthesis, structural studies, anticancer potency and the use of alkyl-phenyl dithiocarbamate complexes as precursors for the preparation of semiconductor nanocrystals. The properties of these compounds and activities are ascribed to be due to either the dithiocarbamate moieties, the nature or type of the substituents around the dithiocarbamate backbone and the central metal ions or combination of these factors.

Encapsulation of ultrafine metal-oxide nanoparticles within mesopores for biomass-derived catalytic applications† †Electronic supplementary information (ESI) available: Experimental section, additional characterization and reaction results. See DOI: 10.1039/c7sc04724j

PubMed Central

Fang, Ruiqi; Tian, Panliang; Yang, Xianfeng

2018-01-01

The development of efficient encapsulation strategies has attracted intense interest for preparing highly active and stable heterogeneous metal catalysts. However, issues related to low loadings, costly precursors and complex synthesis processes restrict their potential applications. Herein, we report a novel and general strategy to encapsulate various ultrafine metal-oxides nanoparticles (NPs) into the mesoporous KIT-6. The synthesis is facile, which only involves self-assembly of a metal–organic framework (MOF) precursor in the silica mesopores and a subsequent calcination process to transform the MOF into metal-oxide NPs. After the controlled calcination, the metal-oxide NPs produced from MOF decomposition are exclusively confined and uniformly distributed in the mesopores of KIT-6 with high metal loadings. Benefitting from the encapsulation effects, as-synthesized Co@KIT-6 materials exhibit superior catalytic activity and recycling stability in biomass-derived HMF oxidation under mild reaction conditions. PMID:29675231

Stress-tuned conductor-polymer composite for use in sensors

DOEpatents

Martin, James E; Read, Douglas H

2013-10-22

A method for making a composite polymeric material with electrical conductivity determined by stress-tuning of the conductor-polymer composite, and sensors made with the stress-tuned conductor-polymer composite made by this method. Stress tuning is achieved by mixing a miscible liquid into the polymer precursor solution or by absorbing into the precursor solution a soluble compound from vapor in contact with the polymer precursor solution. The conductor may or may not be ordered by application of a magnetic field. The composite is formed by polymerization with the stress-tuning agent in the polymer matrix. The stress-tuning agent is removed following polymerization to produce a conductor-polymer composite with a stress field that depends on the amount of stress-tuning agent employed.

Advanced transition metal phosphide materials from single-source molecular precursors

NASA Astrophysics Data System (ADS)

Colson, Adam Caleb

In this thesis, the feasibility of employing organometallic single-source precursors in the preparation of advanced transition metal pnictide materials such as colloidal nanoparticles and films has been investigated. In particular, the ternary FeMnP phase was targeted as a model for preparing advanced heterobimetallic phosphide materials, and the iron-rich Fe3P phase was targeted due to its favorable ferromagnetic properties as well as the fact that the preparation of advanced Fe3P materials has been elusive by commonly used methods. Progress towards the synthesis of advanced Fe2--xMn xP nanomaterials and films was facilitated by the synthesis of the novel heterobimetallic complexes FeMn(CO)8(mu-PR1R 2) (R1 = H, R2 = H or R1 = H, R2 = Ph), which contain the relatively rare mu-PH2 and mu-PPhH functionalities. Iron rich Fe2--xMnxP nanoparticles were obtained by thermal decomposition of FeMn(CO)8(mu-PH 2) using solution-based synthetic methods, and empirical evidence suggested that oleic acid was responsible for manganese depletion. Films containing Fe, Mn, and P with the desired stoichiometric ratio of 1:1:1 were prepared using FeMn(CO)8(mu-PH2) in a simple low-pressure metal-organic chemical vapor deposition (MOCVD) apparatus. Although the elemental composition of the precursor was conserved in the deposited film material, spectroscopic evidence indicated that the films were not composed of pure-phase FeMnP, but were actually mixtures of crystalline FeMnP and amorphous FeP and Mn xOy. A new method for the preparation of phase-pure ferromagnetic Fe 3P films on quartz substrates has also been developed. This approach involved the thermal decomposition of the single-source precursors H 2Fe3(CO)9PR (R = tBu or Ph) at 400 °C. The films were deposited using a simple home-built MOCVD apparatus and were characterized using a variety of analytical methods. The films exhibited excellent phase purity, as evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and field-dependent magnetization measurements, the results of which were all in good agreement with measurements obtained from bulk Fe3P. As-deposited Fe3P films were found to be amorphous, and little or no magnetic hysteresis was observed in plots of magnetization versus applied field. Annealing the Fe3P films at 550 °C resulted in improved crystallinity as well as the observation of magnetic hysteresis.

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

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

Lieberman, Craig M.; Barry, Matthew C.; Wei, Zheng

A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of M xM' 3–xO 4 spinel oxide materials is reported. Three iron–cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal–oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [Fe III(acac) 3][Co II(hfac) 2] (1), [Co II(hfac) 2][Fe III(acac) 3][Co II(hfac) 2] (2), and [Fe II(hfac) 2][Fe III(acac) 3][Co II(hfac) 2]more » (3). In the above heteroleptic complexes, the Lewis acidic, coordinatively unsaturated CoII/FeII centers chelated by two hexafluoroacetylacetonate (hfac) ligands maintain bridging interactions with oxygen atoms of acetylacetonate (acac) groups that chelate the neighboring Fe III metal ion. Preliminary assignment of Fe and Co positions/oxidation states in 1–3 drawn from X-ray structural investigation was corroborated by a number of complementary techniques. Single-crystal resonant synchrotron diffraction and neutron diffraction experiments unambiguously confirmed the location of Fe and Co sites in the molecules of dinuclear (1) and trinuclear (2) complexes, respectively. Direct analysis in real time mass spectrometry revealed the presence of Fe III- and Co II-based fragments in the gas phase upon evaporation of precursors 1 and 2 as well as of Fe III, Fe II, and Co II species for complex 3. Theoretical investigation of two possible “valent isomers”, [Fe III(acac) 3][Co II(hfac) 2] (1) and [Co III(acac) 3][Fe II(hfac) 2] (1'), provided an additional support for the metal site/oxidation state assignment giving a preference of 6.48 kcal/mol for the experimentally observed molecule 1. Magnetic susceptibility measurements data are in agreement with the presence of high-spin FeIII and CoII magnetic centers with weak anti-ferromagnetic coupling between those in molecules of 1 and 2. Highly volatile heterometallic complexes 1–3 were found to act as effective single-source precursors for the low-temperature preparation of iron–cobalt spinel oxides Fe xCo 3–xO 4 known as important materials for diverse energy-related applications.« less

Development of a continuous spinning process for producing silicon carbide - silicon nitride precursor fibers

NASA Technical Reports Server (NTRS)

1985-01-01

An apparatus was designed for the continuous production of silicon carbide - silicon nitride precursor fibers. The precursor polymer can be fiberized, crosslined and pyrolyzed. The product is a metallic black fiber with the composition of the type C sub x Si sub y n sub z. Little, other than the tensile strength and modulus of elasticity, is known of the physical properties.

Enhanced Performance of PbS-quantum-dot-sensitized Solar Cells via Optimizing Precursor Solution and Electrolytes

NASA Astrophysics Data System (ADS)

Tian, Jianjun; Shen, Ting; Liu, Xiaoguang; Fei, Chengbin; Lv, Lili; Cao, Guozhong

2016-03-01

This work reports a PbS-quantum-dot-sensitized solar cell (QDSC) with power conversion efficiency (PCE) of 4%. PbS quantum dots (QDs) were grown on mesoporous TiO2 film using a successive ion layer absorption and reaction (SILAR) method. The growth of QDs was found to be profoundly affected by the concentration of the precursor solution. At low concentrations, the rate-limiting factor of the crystal growth was the adsorption of the precursor ions, and the surface growth of the crystal became the limiting factor in the high concentration solution. The optimal concentration of precursor solution with respect to the quantity and size of synthesized QDs was 0.06 M. To further increase the performance of QDSCs, the 30% deionized water of polysulfide electrolyte was replaced with methanol to improve the wettability and permeability of electrolytes in the TiO2 film, which accelerated the redox couple diffusion in the electrolyte solution and improved charge transfer at the interfaces between photoanodes and electrolytes. The stability of PbS QDs in the electrolyte was also improved by methanol to reduce the charge recombination and prolong the electron lifetime. As a result, the PCE of QDSC was increased to 4.01%.

An efficient copper phthalocyanine additive of perovskite precursor for improving the photovoltaic performance of planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Wu, Shufang; Liu, Qingwei; Zheng, Ya; Li, Renjie; Peng, Tianyou

2017-08-01

Solution processable planar heterojunction perovskite solar cell has drawn much attention as a promising low-cost photovoltaic device, and much effort has been made to improve its power conversion efficiency by choosing appropriate additives for the perovskite precursor solution. Different to those additives reported, a soluble and thermal stable tert-butyl substituted copper phthalocyanine (CuPc(tBu)4) as additive is first introduced into the perovskite precursor solution of a planar perovskite solar cell that is fabricated via the one-step solution process. It is found that the pristine device without CuPc(tBu)4 additive exhibits a power conversion efficiency of 15.3%, while an extremely low concentration (4.4 × 10-3 mM) of CuPc(tBu)4 in the precursor solution leads to the corresponding device achieving an enhanced power conversion efficiency of 17.3%. CuPc(tBu)4 as an additive can improve the quality of perovskite layer with higher crystallinity and surface coverage, then resulting in enhanced light absorption and reduced charge recombination, and thus the better power conversion efficiency. The finding presented here provides a new choice for improving the quality of perovskite layer and the photovoltaic performance of the planar heterojunction perovskite solar cells.

Enhanced Performance of PbS-quantum-dot-sensitized Solar Cells via Optimizing Precursor Solution and Electrolytes.

PubMed

Tian, Jianjun; Shen, Ting; Liu, Xiaoguang; Fei, Chengbin; Lv, Lili; Cao, Guozhong

2016-03-15

This work reports a PbS-quantum-dot-sensitized solar cell (QDSC) with power conversion efficiency (PCE) of 4%. PbS quantum dots (QDs) were grown on mesoporous TiO2 film using a successive ion layer absorption and reaction (SILAR) method. The growth of QDs was found to be profoundly affected by the concentration of the precursor solution. At low concentrations, the rate-limiting factor of the crystal growth was the adsorption of the precursor ions, and the surface growth of the crystal became the limiting factor in the high concentration solution. The optimal concentration of precursor solution with respect to the quantity and size of synthesized QDs was 0.06 M. To further increase the performance of QDSCs, the 30% deionized water of polysulfide electrolyte was replaced with methanol to improve the wettability and permeability of electrolytes in the TiO2 film, which accelerated the redox couple diffusion in the electrolyte solution and improved charge transfer at the interfaces between photoanodes and electrolytes. The stability of PbS QDs in the electrolyte was also improved by methanol to reduce the charge recombination and prolong the electron lifetime. As a result, the PCE of QDSC was increased to 4.01%.

Alternate Spray-coating for the Direct Fabrication of Hydroxyapatite Films without Crystal Growth Step in Solution.

PubMed

Watanabe, Satoshi; Kashiwagi, Rei; Matsumoto, Mutsuyoshi

2017-03-01

We discuss an alternate spray-coating technique for the direct fabrication of hydroxyapatite films using metal masks, suction-type spray nozzles and two calcification solutions of calcium hydroxide and phosphoric acid aqueous solutions. Hydroxyapatite films were formed only on the hydrophobic surface of the substrates. Scanning electron microscopy and energy dispersive X-ray spectroscopy showed that the spray-coated films consisted of hydroxyapatite nanoparticles. The Ca/P ratio was estimated to be about 1.26. X-ray diffraction patterns of the spray-coated films almost coincided with those of the hydroxyapatite powders, showing that the spray-coated films consisted of hydroxyapatite nanoparticles. Dot arrays of hydroxyapatite films at a diameter of 100 μm were formed by tuning the concentrations of calcium hydroxide and phosphoric acid aqueous solutions. This technique allows for the direct fabrication of the hydroxyapatite films without crystal growth process in hydroxyapatite precursors, the scaffolds of crystal growth such as biocompatibility SiO 2 -CaO glasses, or electrophoresis processes. By using this technique, large-area ceramic films with biocompatibility will be micropatterned with minimized material consumption, short fabrication time, and reduced equipment investments.

Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

PubMed

Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

2016-03-28

We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.

Influence of calcium precursors on the morphology and crystallinity of sol gel-derived hydroxyapatite nanoparticles

NASA Astrophysics Data System (ADS)

Vijayalakshmi Natarajan, U.; Rajeswari, S.

2008-10-01

Nanosized hydroxyapatite (HAP) particles were prepared by sol-gel method from the water-based solution of calcium and phosphorus precursor. In this study, two calcium precursors such as calcium nitrate tetrahydrate and calcium acetate were chosen as calcium precursors. The influence of aging period, pH, viscosity and sintering temperature on crystallinity and morphology of the HAP particles were investigated for the two calcium precursors with triethyl phosphate precursor. The morphology of nano-HAP towards phosphorous precursor was dependent on the type of calcium precursor used. The HAP prepared from calcium nitrate and triethyl phosphate was spherically shaped whereas the one from calcium acetate was found to be fibrous in structure. Both HAPs were stable up to 1200 °C and their crystallinity increased with respect to the sintering temperature. The obtained sample was characterized through X-ray diffraction (XRD), P 31 nuclear magnetic resonance (NMR), scanning electronic microscopy (SEM) and TEM analysis. The sol derived from the optimized aging period for the two different calcium precursors was coated on 316L stainless-steel (SS) implant and its corrosion resistivity during long-term implantation was studied by cyclic polarization in Ringer's solution. Both HAPs have their own desirable qualities and were found to be corrosion resistive.

Evaporation-Driven Deposition of ITO Thin Films from Aqueous Solutions with Low-Speed Dip-Coating Technique.

PubMed

Ito, Takashi; Uchiyama, Hiroaki; Kozuka, Hiromitsu

2017-05-30

We suggest a novel wet coating process for preparing indium tin oxide (ITO) films from simple solutions containing only metal salts and water via evaporation-driven film deposition during low-speed dip coating. Homogeneous ITO precursor films were deposited on silica glass substrates from the aqueous solutions containing In(NO 3 ) 3 ·3H 2 O and SnCl 4 ·5H 2 O by dip coating at substrate withdrawal speeds of 0.20-0.50 cm min -1 and then crystallized by the heat treatment at 500-800 °C for 10-60 min under N 2 gas flow of 0.5 L min -1 . The ITO films heated at 600 °C for 30 min had a high optical transparency in the visible range and a good electrical conductivity. Multiple-coating ITO films obtained with five-times dip coating exhibited the lowest sheet (ρ S ) and volume (ρ V ) resistivities of 188 Ω sq -1 and 4.23 × 10 -3 Ω cm, respectively.

Organic Superconductor, Made without Metals.

ERIC Educational Resources Information Center

Science News, 1980

1980-01-01

The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

A facile precursor route to highly loaded metal/ceramic nanofibers as a robust surface-enhanced Raman template

NASA Astrophysics Data System (ADS)

Park, Jay Hoon; Joo, Yong Lak

2017-09-01

We report silver (Ag)/ceramic nanofibers with highly robust and sensitive optical sensory capabilities that can withstand harsh conditions. These nanofibers are fabricated by first electrospinning solutions of poly vinyl alcohol (PVA) and metal precursor polymers, followed by subsequent series of heat treatment. The reported fabrication method demonstrate the effects of (i) the location of Ag crystals, (ii) crystal size and shape, and (iii) constituents of the ceramic matrix as surface-enhanced Raman spectroscopy (SERS) templates with 10-6 M 4-mercaptobenzoic acid (4-MBA). Notably, these silver/ceramic nanofibers preserved most of their highly sensitive localized surface plasmon resonance (LSPR) even under high temperature of 400 °C, in contrast to preformed Ag nanoparticles (NPs) in PVA nanofibers which lost most of its optical property presumably due to (i) Ag oxidation and (ii) loss of the matrix material. Among the ceramic substrates of ZrO2, Al2O3, and ZnO with silver crystals, we discovered that the ZnO substrate showed the most consistent and the strongest signal strength owing to the synergistic chemical and optical properties of the ZnO substrate. Moreover, the pure Ag nanofiber proved to be the best heat-resistant SERS template, owing to its (i) anisotropic morphology and (ii) thicker diameter when compared with other conventional Ag nanomaterials. These results demonstrated simple yet highly controllable fabrication of robust SERS templates, with potential applications in a catalytic sensory which is often exposed to harsh conditions.

Successful synthesis and thermal stability of immiscible metal Au-Rh, Au-Ir andAu-Ir-Rh nanoalloys

NASA Astrophysics Data System (ADS)

Shubin, Yury; Plyusnin, Pavel; Sharafutdinov, Marat; Makotchenko, Evgenia; Korenev, Sergey

2017-05-01

We successfully prepared face-centred cubic nanoalloys in systems of Au-Ir, Au-Rh and Au-Ir-Rh, with large bulk miscibility gaps, in one-run reactions under thermal decomposition of specially synthesised single-source precursors, namely, [AuEn2][Ir(NO2)6], [AuEn2][Ir(NO2)6] х [Rh(NO2)6]1-х and [AuEn2][Rh(NO2)6]. The precursors employed contain all desired metals ‘mixed’ at the atomic level, thus providing significant advantages for obtaining alloys. The observations using high-resolution transmission electron microscopy show that the nanoalloy structures are composed of well-dispersed aggregates of crystalline domains with a mean size of 5 ± 3 nm. Еnergy dispersive x-ray spectroscopy and x-ray powder diffraction (XRD) measurements confirm the formation of AuIr, AuRh, AuIr0.75Rh0.25, AuIr0.50Rh0.50 and AuIr0.25Rh0.75 metastable solid solutions. In situ high-temperature synchrotron XRD (HTXRD) was used to study the formation mechanism of nanoalloys. The observed transformations are described by the ‘conversion chemistry’ mechanism characterised by the primary development of particles comprising atoms of only one type, followed by a chemical reaction resulting in the final formation of a nanoalloy. The obtained metastable nanoalloys exhibit essential thermal stability. Exposure to 180 °C for 30 h does not cause any dealloying process.

Successful synthesis and thermal stability of immiscible metal Au-Rh, Au-Ir andAu-Ir-Rh nanoalloys.

PubMed

Shubin, Yury; Plyusnin, Pavel; Sharafutdinov, Marat; Makotchenko, Evgenia; Korenev, Sergey

2017-05-19

We successfully prepared face-centred cubic nanoalloys in systems of Au-Ir, Au-Rh and Au-Ir-Rh, with large bulk miscibility gaps, in one-run reactions under thermal decomposition of specially synthesised single-source precursors, namely, [AuEn 2 ][Ir(NO 2 ) 6 ], [AuEn 2 ][Ir(NO 2 ) 6 ] х [Rh(NO 2 ) 6 ] 1-х and [AuEn 2 ][Rh(NO 2 ) 6 ]. The precursors employed contain all desired metals 'mixed' at the atomic level, thus providing significant advantages for obtaining alloys. The observations using high-resolution transmission electron microscopy show that the nanoalloy structures are composed of well-dispersed aggregates of crystalline domains with a mean size of 5 ± 3 nm. Еnergy dispersive x-ray spectroscopy and x-ray powder diffraction (XRD) measurements confirm the formation of AuIr, AuRh, AuIr 0.75 Rh 0.25 , AuIr 0.50 Rh 0.50 and AuIr 0.25 Rh 0.75 metastable solid solutions. In situ high-temperature synchrotron XRD (HTXRD) was used to study the formation mechanism of nanoalloys. The observed transformations are described by the 'conversion chemistry' mechanism characterised by the primary development of particles comprising atoms of only one type, followed by a chemical reaction resulting in the final formation of a nanoalloy. The obtained metastable nanoalloys exhibit essential thermal stability. Exposure to 180 °C for 30 h does not cause any dealloying process.

Fabrication and Performance of High Energy Li-Ion Battery Based on the Spherical Li[Li(0.2)Ni(0.16)Co(0.1)Mn(0.54)]O2 Cathode and Si Anode.

PubMed

Ye, Jing; Li, Yi-xuan; Zhang, Li; Zhang, Xue-ping; Han, Min; He, Ping; Zhou, Hao-shen

2016-01-13

The cathode materials of Li-ion batteries for electric vehicles require not only a large gravimetric capacity but also a high volumetric capacity. A new Li-rich layered oxide cathode with superior capacity, Li[Li0.20Ni0.16Co0.10Mn0.54]O2 (denoted as LNCM), is synthesized from precursor, a coprecipitated spherical metal hydroxide. The preparation technology of precursor such as stirring speed, concentration of metal solution, and reaction time are regulated elaborately. The final product LNCM shows a well-ordered, hexagonal-layer structure, as confirmed by Rietveld refinement of X-ray diffraction pattern. The particle size of the final product has an average diameter of about 10 μm, and the corresponding tap density is about 2.25 g cm(-3). Electrochemical measurements indicate that as-prepared LNCM has great initial columbic efficiency, reversible capacity, and cycling stability, with specific discharge capacities of 278 and 201 mAh g(-1) at 0.03 and 0.5 C rates, respectively. Cycling at 0.1 C, LNCM delivers a discharge capacity of 226 mAh g(-1) with 95% retention capacity after 50 cycles. Si/LNCM cell is fabricated using Si submicroparticle as anode against LNCM. The cell can exhibit a specific energy of 590 Wh kg(-1) based on the total weight of cathode and anode materials.

Metal-organic frameworks for lithium ion batteries and supercapacitors

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

Ke, Fu-Sheng; Wu, Yu-Shan; Deng, Hexiang, E-mail: hdeng@whu.edu.cn

2015-03-15

Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000 m{sup 2} g{sup −1}) and porosity that can favor the electrochemical reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000 m{sup 2} g{sup −1}), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefitmore » from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs. - Graphical abstract: MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. - Highlights: • MOFs have potential in electrochemical area due to their high porosity and diversity. • We summarized and compared works on MOFs for lithium ion battery and supercapacitor. • We pointed out critical challenges and provided possible solutions for future study.« less

Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

PubMed

Yamauchi, Yusuke; Tonegawa, Akihisa; Komatsu, Masaki; Wang, Hongjing; Wang, Liang; Nemoto, Yoshihiro; Suzuki, Norihiro; Kuroda, Kazuyuki

2012-03-21

Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

Green synthesis of silver nanoparticles mediated by Pulicaria glutinosa extract

PubMed Central

Khan, Mujeeb; Khan, Merajuddin; Adil, Syed Farooq; Tahir, Muhammad Nawaz; Tremel, Wolfgang; Alkhathlan, Hamad Z; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H

2013-01-01

The green synthesis of metallic nanoparticles (NPs) has attracted tremendous attention in recent years because these protocols are low cost and more environmentally friendly than standard methods of synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver NPs using an aqueous solution of Pulicaria glutinosa plant extract as a bioreductant. The as-prepared silver NPs were characterized using ultraviolet–visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Moreover, the effects of the concentration of the reductant (plant extract) and precursor solution (silver nitrate), the temperature on the morphology, and the kinetics of reaction were investigated. The results indicate that the size of the silver NPs varied as the plant extract concentration increased. The as-synthesized silver NPs were phase pure and well crystalline with a face-centered cubic structure. Further, Fourier-transform infrared spectroscopy analysis confirmed that the plant extract not only acted as a bioreductant but also functionalized the NPs’ surfaces to act as a capping ligand to stabilize them in the solvent. The developed eco-friendly method for the synthesis of NPs could prove a better substitute for the physical and chemical methods currently used to prepare metallic NPs commonly used in cosmetics, foods, and medicines. PMID:23620666

New precursors and chemistry for the growth of transition metal films by atomic layer deposition

NASA Astrophysics Data System (ADS)

Knisley, Thomas Joseph

The advancing complexity of advanced microelectronic devices is placing rigorous demands on currently used PVD and CVD deposition techniques. The ALD deposition method is proposed to meet the film thickness and conformality constraints needed by the semiconductor industry in future manufacturing processes. Unfortunately, there is a limited number of chemical precursors available that have high thermal stability, reactivity, and vapor pressure suitable for ALD film growth to occur. These properties collectively contribute to the lack of suitable transition metal precursors available for use in ALD. In this thesis, we report the discovery of a series of novel transition metal diazadienate precursors that promising properties deemed suitable for ALD. The volatility and thermal stability of the new transition metal diazadienyl compounds were studied by preparative sublimation and capillary tube melting point/decomposition experiments. Thermogravimetric analyses (TGA) demonstrate precursor residues of less than 4% at 500 °C. In addition, sublimation data, melting points, and decomposition temperatures for all complexes are presented. The manganese diazadienyl complex has the highest decomposition temperature of the series of complexes produced (325 °C). During preparative sublimations, the product recoveries of all transition metal diazadienyl complexes were greater than 92.0% with nonvolatile residues of less than 7.0%. This is an excellent indication that these complexes may be suitable candidates as metal precursors for ALD. Nickel nitride (NixN) films have been studied as an intermediate material for the formation of both nickel metal and nickel silicide using chemical vapor deposition. Herein, we describe the ALD growth of nickel nitride thin films from bis(1,4-di-tert-butyl-1,3-diazabutadiene) nickel(II) (Ni(tBu2DAD)2) and 1,1-dimethylhydrazine. An ALD window for the deposition of nickel nitride films on 500 nm thermal SiO2 substrates was observed between 225 and 240 °C with a constant growth rate of 0.70 Å/cycle. X-Ray photoelectron spectroscopy (XPS) showed all expected ionizations with carbon concentrations below the detection limit after argon ion sputtering. Due to preferential nitrogen sputtering in XPS, Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) were performed and subsequently revealed Ni:N ratios between 2-4 for films deposited within the ALD window. AFM measurements revealed a RMS roughness value of 10.8 nm on an as-deposited film at 225°C. All as-deposited films were amorphous as determined by X-ray diffraction. Copper is the primary interconnect material in microelectronics devices, due to its high conductivity and low affinity towards electromigration. With transistor gate lengths scheduled to reach 14 nm by 2014, there are severe demands upon the current film growth techniques used in device fabrication. The ALD film growth method is ideally suited for future microelectronics manufacturing, since it inherently provides highly conformal thin films, even in high aspect ratio nanoscale features, and allows sub-nanometer control over film thicknesses. In Chapter 4, we describe the atomic layer deposition of high purity, low resistivity copper metal thin films using a three precursor sequence entailing Cu(dmap)2, formic acid, and hydrazine. In this process, Cu(dmap) 2 is unreactive towards hydrazine but is transformed to copper(II) formate, which is then readily reduced to copper metal by subsequent hydrazine exposure. The present work therefore addresses a central problem with the ALD growth of metal thin films: low reactivity of metal precursors toward common reducing agents. A constant growth rate of 0.47-0.50 Å/cycle upon prime grade Si(100) was observed at substrate temperatures between 100 and 170 °C. Compositional analyses (XPS and TOF-ERDA) revealed copper films with low levels of carbon, oxygen, nitrogen, and hydrogen. Powder X-ray diffraction spectra of all films showed polycrystalline copper. The resistivities of films grown between 100 and 140 °C ranged between 9.6 and 16.4 μΩ·cm, demonstrating the growth of high purity, low resistivity copper films. An AFM measurement revealed a RMS roughness value of 3.5 nm on an as-deposited 50 nm Cu film at 120 °C.

Modelling solid solutions with cluster expansion, special quasirandom structures, and thermodynamic approaches

NASA Astrophysics Data System (ADS)

Saltas, V.; Horlait, D.; Sgourou, E. N.; Vallianatos, F.; Chroneos, A.

2017-12-01

Modelling solid solutions is fundamental in understanding the properties of numerous materials which are important for a range of applications in various fields including nanoelectronics and energy materials such as fuel cells, nuclear materials, and batteries, as the systematic understanding throughout the composition range of solid solutions for a range of conditions can be challenging from an experimental viewpoint. The main motivation of this review is to contribute to the discussion in the community of the applicability of methods that constitute the investigation of solid solutions computationally tractable. This is important as computational modelling is required to calculate numerous defect properties and to act synergistically with experiment to understand these materials. This review will examine in detail two examples: silicon germanium alloys and MAX phase solid solutions. Silicon germanium alloys are technologically important in nanoelectronic devices and are also relevant considering the recent advances in ternary and quaternary groups IV and III-V semiconductor alloys. MAX phase solid solutions display a palette of ceramic and metallic properties and it is anticipated that via their tuning they can have applications ranging from nuclear to aerospace industries as well as being precursors for particular MXenes. In the final part, a brief summary assesses the limitations and possibilities of the methodologies discussed, whereas there is discussion on the future directions and examples of solid solution systems that should prove fruitful to consider.

The Au(111)/IL interfacial nanostructure in the presence of precursors and its influence on the electrodeposition process.

PubMed

Borisenko, Natalia; Lahiri, Abhishek; Pulletikurthi, Giridhar; Cui, Tong; Carstens, Timo; Zahlbach, Janine; Atkin, Rob; Endres, Frank

2018-01-01

Ionic liquids have attracted significant interest as electrolytes for the electrodeposition of metals and semiconductors, but the details of the deposition processes are not yet well understood. In this paper, we give an overview of how the addition of various precursors (TaF 5 , SiCl 4 , and GaCl 3 ) affects the solid/IL interfacial structure. In situ Atomic Force Microscopy (AFM) and vibrational spectroscopy have been employed to study the changes of the Au(111)/IL interface and in the electrolytes, respectively. Ionic liquids with the 1-butyl-1-methylpyrrolidinium ([Py 1,4 ] + ) cation and bis(trifluoromethylsulfonyl)amide ([TFSA] - ), trifluoromethylsulfonate ([TfO] - ) and tris(pentafluoroethyl)trifluorophosphate ([FAP] - ) as anions were chosen for this purpose. In situ AFM force-distance measurements reveal that both the anion of the IL and the solutes (TaF 5 or GaCl 3 ) influence the Electrical Double Layer (EDL) structure of the Au(111)/IL interface, which can affect the deposition process of Ta and the morphology of the Ga electrodeposits, respectively. Furthermore, the concentration of the precursor can significantly alter the Au(111)/[Py 1,4 ][FAP]-SiCl 4 interfacial structure wherein the presence of 0.25 M SiCl 4 a double layer structure forms that facilitates Si deposition. This study may provide some critical insights into the structure of the electrode/IL interface for specific applications.

The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol-Gel Process.

PubMed

Purcar, Violeta; Şomoghi, Raluca; Niţu, Sabina Georgiana; Nicolae, Cristian-Andi; Alexandrescu, Elvira; Gîfu, Ioana Cătălina; Gabor, Augusta Raluca; Stroescu, Hermine; Ianchiş, Raluca; Căprărescu, Simona; Cinteză, Ludmila Otilia

2017-12-12

Hybrid nanomaterials based on zinc oxide were synthesized via the sol-gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300-500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Higher-resolution selective metallization on alumina substrate by laser direct writing and electroless plating

NASA Astrophysics Data System (ADS)

Lv, Ming; Liu, Jianguo; Wang, Suhuan; Ai, Jun; Zeng, Xiaoyan

2016-03-01

How to fabricate conductive patterns on ceramic boards with higher resolution is a challenge in the past years. The fabrication of copper patterns on alumina substrate by laser direct writing and electroless copper plating is a low cost and high efficiency method. Nevertheless, the lower resolution limits its further industrial applications in many fields. In this report, the mechanisms of laser direct writing and electroless copper plating were studied. The results indicated that as the decomposed products of precursor PdCl2 have different chemical states respectively in laser-irradiated zone (LIZ) and laser-affected zone (LAZ). This phenomenon was utilized and a special chemical cleaning method with aqua regia solution was taken to selectively remove the metallic Pd in LAZ, while kept the PdO in LIZ as the only active seeds. As a result, the resolution of subsequent copper patterns was improved significantly. This technique has a great significance to develop the microelectronics devices.

Biosynthesis of cobalt oxide nanoparticles using endophytic fungus Aspergillus nidulans.

PubMed

Vijayanandan, Ajuy Sundar; Balakrishnan, Raj Mohan

2018-07-15

Metallic oxide nanoparticles have profound applications in electrochemical devices, supercapacitors, biosensors and batteries. Though four fungi were isolated from Nothapodytes foetida, Aspergillus nidulans was found to be suitable for synthesis of cobalt oxide nanoparticles, as it has proficient tolerance towards metal under study. The broth containing precursor solution and organism Aspergillus nidulans had changed from pink to orange indicating the formation of nanoparticles. Characterization by x-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive x-ray analysis (EDX) confirmed the formation of spinel cobalt oxide nanoparticles at an average size of 20.29 nm in spherical shape with sulfur-bearing proteins acting as a capping agent for the synthesized nanoparticles. The nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence. The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Controlled chemical stabilization of polyvinyl precursor fiber, and high strength carbon fiber produced therefrom

DOEpatents

Naskar, Amit K.

2016-12-27

Method for the preparation of carbon fiber, which comprises: (i) immersing functionalized polyvinyl precursor fiber into a liquid solution having a boiling point of at least 60.degree. C.; (ii) heating the liquid solution to a first temperature of at least 25.degree. C. at which the functionalized precursor fiber engages in an elimination-addition equilibrium while a tension of at least 0.1 MPa is applied to the fiber; (iii) gradually raising the first temperature to a final temperature that is at least 20.degree. C. above the first temperature and up to the boiling point of the liquid solution for sufficient time to convert the functionalized precursor fiber to a pre-carbonized fiber; and (iv) subjecting the pre-carbonized fiber produced according to step (iii) to high temperature carbonization conditions to produce the final carbon fiber. Articles and devices containing the fibers, including woven and non-woven mats or paper forms of the fibers, are also described.

Controlled in situ boron doping of diamond thin films using solution phase

NASA Astrophysics Data System (ADS)

Roy, M.; Dua, A. K.; Nuwad, J.; Girija, K. G.; Tyagi, A. K.; Kulshreshtha, S. K.

2006-12-01

Controlled boron doping of diamond film using nontoxic reagents is a challenge in itself. During the present study, attempts have been made to dope diamond films in situ with boron from a solution of boric acid (H3BO3) in methanol (CH3OH) using a specially designed bubbler that ensured continuous and controlled flow of vapors of boron precursors during deposition. The samples are thoroughly characterized using a host of techniques comprising of x-ray photoelectron spectroscopy, Raman, x-ray diffraction, and current-voltage measurements (I-V). Cross-sectional micro-Raman spectroscopy has been used to obtain depth profile of boron in diamond films. Boron concentration ([B]) in the films is found to vary linearly on a semilog scale with molarity (M) of H3BO3 in CH3OH. Lattice constant of our samples is smaller than the reported American society for testing and materials (ASTM) values due to oxygen incorporation and it increases with [B] in the diamond samples. Heavily boron doped samples exhibit Fano deformation of the Raman line shape and negative and/zero activation barrier in temperature dependent I-V measurements that indicate the formation of metallic phase in the samples. The present study illustrates the feasibility of safe and controlled boron doping of diamond films using a solution of H3BO3 in CH3OH over a significant range of [B] from semiconductor to metallic regime but with a little adverse effect due to unintentional but unavoidable incorporation of oxygen.

Nonrelativistic grey S n -transport radiative-shock solutions

DOE PAGES

Ferguson, J. M.; Morel, J. E.; Lowrie, R. B.

2017-06-01

We present semi-analytic radiative-shock solutions in which grey Sn-transport is used to model the radiation, and we include both constant cross sections and cross sections that depend on temperature and density. These new solutions solve for a variable Eddington factor (VEF) across the shock domain, which allows for interesting physics not seen before in radiative-shock solutions. Comparisons are made with the grey nonequilibrium-diffusion radiative-shock solutions of Lowrie and Edwards [1], which assumed that the Eddington factor is constant across the shock domain. It is our experience that the local Mach number is monotonic when producing nonequilibrium-diffusion solutions, but that thismore » monotonicity may disappear while integrating the precursor region to produce Sn-transport solutions. For temperature- and density-dependent cross sections we show evidence of a spike in the VEF in the far upstream portion of the radiative-shock precursor. We show evidence of an adaptation zone in the precursor region, adjacent to the embedded hydrodynamic shock, as conjectured by Drake [2, 3], and also confirm his expectation that the precursor temperatures adjacent to the Zel’dovich spike take values that are greater than the downstream post-shock equilibrium temperature. We also show evidence that the radiation energy density can be nonmonotonic under the Zel’dovich spike, which is indicative of anti-diffusive radiation flow as predicted by McClarren and Drake [4]. We compare the angle dependence of the radiation flow for the Sn-transport and nonequilibriumdiffusion radiation solutions, and show that there are considerable differences in the radiation flow between these models across the shock structure. Lastly, we analyze the radiation flow to understand the cause of the adaptation zone, as well as the structure of the Sn-transport radiation-intensity solutions across the shock structure.« less

Nonrelativistic grey S n -transport radiative-shock solutions

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

Ferguson, J. M.; Morel, J. E.; Lowrie, R. B.

We present semi-analytic radiative-shock solutions in which grey Sn-transport is used to model the radiation, and we include both constant cross sections and cross sections that depend on temperature and density. These new solutions solve for a variable Eddington factor (VEF) across the shock domain, which allows for interesting physics not seen before in radiative-shock solutions. Comparisons are made with the grey nonequilibrium-diffusion radiative-shock solutions of Lowrie and Edwards [1], which assumed that the Eddington factor is constant across the shock domain. It is our experience that the local Mach number is monotonic when producing nonequilibrium-diffusion solutions, but that thismore » monotonicity may disappear while integrating the precursor region to produce Sn-transport solutions. For temperature- and density-dependent cross sections we show evidence of a spike in the VEF in the far upstream portion of the radiative-shock precursor. We show evidence of an adaptation zone in the precursor region, adjacent to the embedded hydrodynamic shock, as conjectured by Drake [2, 3], and also confirm his expectation that the precursor temperatures adjacent to the Zel’dovich spike take values that are greater than the downstream post-shock equilibrium temperature. We also show evidence that the radiation energy density can be nonmonotonic under the Zel’dovich spike, which is indicative of anti-diffusive radiation flow as predicted by McClarren and Drake [4]. We compare the angle dependence of the radiation flow for the Sn-transport and nonequilibriumdiffusion radiation solutions, and show that there are considerable differences in the radiation flow between these models across the shock structure. Lastly, we analyze the radiation flow to understand the cause of the adaptation zone, as well as the structure of the Sn-transport radiation-intensity solutions across the shock structure.« less

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE PAGES

Du, Lei; Luo, Langli; Feng, Zhenxing; ...

2017-07-05

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarcity. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides are their low electronic conductivity and durability. The carbon encapsulating transition metal nanoparticles are expected to address these challenges. However, the relationship between precursor compositions and catalyst properties, and the intrinsic functions of each component has been rarely studied. In this paper,more » we report a highly durable (no degradation after 20,000 cycles) and highly active (360 mV overpotential at 10 mA cm –2 GEO) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron–donation/deviation from Fe and tuned lattice and electronic structures of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. Finally, we further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

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

Du, Lei; Luo, Langli; Feng, Zhenxing

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarcity. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides are their low electronic conductivity and durability. The carbon encapsulating transition metal nanoparticles are expected to address these challenges. However, the relationship between precursor compositions and catalyst properties, and the intrinsic functions of each component has been rarely studied. In this paper,more » we report a highly durable (no degradation after 20,000 cycles) and highly active (360 mV overpotential at 10 mA cm –2 GEO) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron–donation/deviation from Fe and tuned lattice and electronic structures of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. Finally, we further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

Method of manufacturing tin-doped indium oxide nanofibers

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

Ozcan, Soydan; Naskar, Amit K

2017-06-06

A method of making indium tin oxide nanofibers includes the step of mixing indium and tin precursor compounds with a binder polymer to form a nanofiber precursor composition. The nanofiber precursor composition is co-formed with a supporting polymer to form a composite nanofiber having a precursor composition nanofiber completely surrounded by the supporting polymer composition. The supporting polymer composition is removed from the composite nanofiber to expose the precursor composition nanofiber. The precursor composition nanofiber is then heated in the presence of oxygen such as O.sub.2 to form indium tin oxide and to remove the binder polymer to form anmore » indium tin oxide nanofiber. A method of making metal oxide nanofibers is also disclosed.« less

One-step synthesis of mesoporous pentasil zeolite with single-unit-cell lamellar structural features

DOEpatents

Tsapstsis, Michael; Zhang, Xueyi

2015-11-17

A method for making a pentasil zeolite material includes forming an aqueous solution that includes a structure directing agent and a silica precursor; and heating the solution at a sufficient temperature and for sufficient time to form a pentasil zeolite material from the silica precursor, wherein the structure directing agent includes a quaternary phosphonium ion.

Intelligent Processing of Ferroelectric Thin Films

DTIC Science & Technology

1993-09-03

the acetate precursors. The results from these experiments involving coprecipitation, hydrothermal , spray pyrolysis and freeze drying have shown that...Spray Pyrolysis (SP) D. Hydrothermal Processing (HP) The powder produced by each process was characterized by X-ray diffraction (XRD) and scanning...precursors were used as described above. Instead of ammonia solution, an oxalic acid solution was used as the3 precipitating agent. The precipitants

Role of Precursor-Conversion Chemistry in the Crystal-Phase Control of Catalytically Grown Colloidal Semiconductor Quantum Wires.

PubMed

Wang, Fudong; Buhro, William E

2017-12-26

Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the Bi x Cd y Te z catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution-solid-solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution-liquid-solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-reaction chemistry in the crystal-phase control of catalytically grown colloidal QWs, opening the possibility of growing phase-pure QWs of other compositions.

Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch; Dupuis, Russell D.; Fischer, Alec M.; Ponce, Fernando A.; Ryou, Jae-Hyun

2015-09-01

Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.

Sol-Gel Processing of MgF2 Antireflective Coatings

PubMed Central

Löbmann, Peer

2018-01-01

There are different approaches for the preparation of porous antireflective λ/4 MgF2 films from liquid precursors. Among these, the non-aqueous fluorolytic synthesis of precursor solutions offers many advantages in terms of processing simplicity and scalability. In this paper, the structural features and optical performance of the resulting films are highlighted, and their specific interactions with different inorganic substrates are discussed. Due to their excellent abrasion resistance, coatings have a high potential for applications on glass. Using solvothermal treatment of precursor solutions, also the processing of thermally sensitive polymer substrates becomes feasible. PMID:29724064

Bimetallic NiFe2O4 synthesized via confined carburization in NiFe-MOFs for efficient oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Fang, Zhiqiang; Hao, Zhaomin; Dong, Qingsong; Cui, Yong

2018-04-01

Transition metal oxides that derived from metal-organic framework (MOF) precursor have intensively received attention because of their numerous electrochemical applications. Bimetallic Ni-Fe oxides have been rarely reported on the basis of MOF-related strategy. Herein, a bimetallic NiFe2O4 was successfully synthesized via confined carburization in NiFe-MOF precursors and characterized by XRD, XPS, SEM, and TEM. After conducting an investigation of oxygen evolution reaction (OER), the as-synthesized NiFe2O4 material exhibited good catalytic efficiency and high stability and durability in alkaline media. The as-synthesized NiFe2O4 material would promote the development of MOFs in non-noble-metal OER catalyst.

Method for synthesizing thin film electrodes

DOEpatents

Boyle, Timothy J [Albuquerque, NM

2007-03-13

A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

High-mobility ultrathin semiconducting films prepared by spin coating.

PubMed

Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

2004-03-18

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

High-mobility ultrathin semiconducting films prepared by spin coating

NASA Astrophysics Data System (ADS)

Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

2004-03-01

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

Supramolecular metal-organic frameworks that display high homogeneous and heterogeneous photocatalytic activity for H2 production

NASA Astrophysics Data System (ADS)

Tian, Jia; Xu, Zi-Yue; Zhang, Dan-Wei; Wang, Hui; Xie, Song-Hai; Xu, Da-Wen; Ren, Yuan-Hang; Wang, Hao; Liu, Yi; Li, Zhan-Ting

2016-05-01

Self-assembly has a unique presence when it comes to creating complicated, ordered supramolecular architectures from simple components under mild conditions. Here, we describe a self-assembly strategy for the generation of the first homogeneous supramolecular metal-organic framework (SMOF-1) in water at room temperature from a hexaarmed [Ru(bpy)3]2+-based precursor and cucurbit[8]uril (CB[8]). The solution-phase periodicity of this cubic transition metal-cored supramolecular organic framework (MSOF) is confirmed by small-angle X-ray scattering and diffraction experiments, which, as supported by TEM imaging, is commensurate with the periodicity in the solid state. We further demonstrate that SMOF-1 adsorbs anionic Wells-Dawson-type polyoxometalates (WD-POMs) in a one-cage-one-guest manner to give WD-POM@SMOF-1 hybrid assemblies. Upon visible-light (500 nm) irradiation, such hybrids enable fast multi-electron injection from photosensitive [Ru(bpy)3]2+ units to redox-active WD-POM units, leading to efficient hydrogen production in aqueous media and in organic media. The demonstrated strategy opens the door for the development of new classes of liquid-phase and solid-phase ordered porous materials.

Supramolecular metal-organic frameworks that display high homogeneous and heterogeneous photocatalytic activity for H 2 production

DOE PAGES

Tian, Jia; Xu, Zi-Yue; Zhang, Dan-Wei; ...

2016-05-10

Self-assembly has a unique presence when it comes to creating complicated, ordered supramolecular architectures from simple components under mild conditions. Here, we describe a self-assembly strategy for the generation of the first homogeneous supramolecular metal-organic framework (SMOF-1) in water at room temperature from a hexaarmed [Ru(bpy) 3 ] 2+ -based precursor and cucurbit[8] uril (CB[8]). The solution-phase periodicity of this cubic transition metal-cored supramolecular organic framework (MSOF) is confirmed by small-angle X-ray scattering and diffraction experiments, which, as supported by TEM imaging, is commensurate with the periodicity in the solid state. We further demonstrate that SMOF-1 adsorbs anionic Wells-'Dawson-type polyoxometalatesmore » (WD-POMs) in a one-cage-one-guest manner to give WD-POM@SMOF-1 hybrid assemblies. Upon visible-light (500 nm) irradiation, such hybrids enable fast multi-electron injection from photosensitive [Ru(bpy) 3 ] 2+ units to redox-active WD-POM units, leading to efficient hydrogen production in aqueous media and in organic media. The demonstrated strategy opens the door for the development of new classes of liquid-phase and solid-phase ordered porous materials.« less

Fabrication and Characterization of CZTS Thin Films Prepared by the Sulfurization of RF-Sputtered Stacked Metal Precursors

NASA Astrophysics Data System (ADS)

Abusnina, Mohamed; Moutinho, Helio; Al-Jassim, Mowafak; DeHart, Clay; Matin, Mohammed

2014-09-01

In this work, Cu2ZnSnS4 (CZTS) thin films were prepared by the sulfurization of metal precursors deposited sequentially via radio frequency magnetron sputtering on Mo-coated soda-lime glass. The stack order of the precursors was Mo/Zn/Sn/Cu. Sputtered precursors were annealed in sulfur atmosphere with nine different conditions to study the impact of sulfurization time and substrate temperature on the structural, morphological, and optical properties of the final CZTS films. X-ray fluorescence was used to determine the elemental composition ratio of the metal precursors. Final CZTS films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). XRD and EDS were combined to investigate the films' structure and to identify the presence of secondary phases. XRD analysis indicated an improvement in film crystallinity with an increase of the substrate temperature and annealing times. Also indicated was the minimization and/or elimination of secondary phases when the films experienced longer annealing time. EDS revealed slight Sn loss in films sulfurized at 550°C; however, an increase of the sulfurization temperature to 600°C did not confirm these results. SEM study showed that films treated with higher temperatures exhibited dense morphology, indicating the completion of the sulfurization process. The estimated absorption coefficient was on the order of 104 cm-1 for all CZTS films, and the values obtained for the optical bandgap energy of the films were between 1.33 eV and 1.52 eV.

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

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

Zhong, Lihua; He, Xiaoman; Qu, Jun

Al(OH){sub 3} and Ca(OH){sub 2} powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kineticsmore » with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C{sub 3}A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C{sub 3}A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO{sub 4} LDH product. Ca-Al-CrO{sub 4} LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.« less

Effects of Residual Lithium in the precursors of Li[Ni1/3Co1/3Mn1/3]O2 on their lithium-ion battery performance

NASA Astrophysics Data System (ADS)

Jo, Minsang; Ku, Heesuk; Park, Sanghyuk; Song, Junho; Kwon, Kyungjung

2018-07-01

Li[Ni1/3Co1/3Mn1/3]O2 cathode active materials are synthesized from co-precipitated hydroxide precursors Lix[Ni1/3Co1/3Mn1/3]1-x(OH)2, and the effect of residual Li in the precursors on the lithium-ion battery (LIB) performance of their corresponding cathode active materials is investigated. Three kinds of precursors that contain different amounts of Li are selected depending on different conditions of the solution composition for the co-precipitation and washing process. It is confirmed that the introduction of Li to the precursors reduces the degree of structural perfection by X-ray diffraction analysis. Undesirable cation mixing occurs with the increasing Li content of the precursors, which is inferred from a decline in lattice parameters and the calculated intensity ratio of (003) and (104) peaks. In the voltage range of 3.0-4.3 V, the initial charge/discharge capacities and the rate capability of the cathode active materials are aggravated when Li exists in the precursors. Therefore, it could be concluded that the strict control of Li in a solution for co-precipitation of precursors is necessary in the resynthesis of cathode active materials from spent LIBs.

Reductive surface synthesis of gold nanoparticles on silicate glass and their biochemical sensor applicationsa

PubMed Central

Li, M.; Kim, D.-P.; Jeong, G.-Y.; Seo, D.-K.; Park, C.-P.

2012-01-01

Gold nanoparticles (Au NPs) were directly synthesized on the surface of polyvinylsilazane (PVSZ, -[(vinyl)SiH-NH2]-) without use of extra reductive additives. The reductive Si-H functional groups on the surface of cured PVSZ acted as surface bound reducing agents to form gold metal when contacted with an aqueous Au precursor (HAuCl4) solution, leading to formation of Au NPs adhered to silicate glass surface. The Au NPs-silicate platforms were preliminarily tested to detect Rhodamine B (1 μM) by surface enhanced Raman scattering. Furthermore, gold microelectrode obtained by post-chemical plating was used as an integrated amperometric detection element in the polydimethylsilane-glass hybrid microfluidic chip. PMID:24324531

Nitrogen-doped mesoporous carbon-armored cobalt nanoparticles as efficient hydrogen evolving electrocatalysts.

PubMed

Tang, Duihai; Li, Kuo; Zhang, Wenting; Qiao, Zhen-An; Zhu, Junjiang; Zhao, Zhen

2018-03-15

A series of Co nanoparticles embedded, N-doped mesoporous carbons have been synthesized through chelate-assisted co-assembly strategy followed by thermal treatment. The preparation is based on an assembly process, with evaporation of an ethanol-water solution containing melamine formaldehyde resin (MF resin) as carbon source, nitrogen source, and chelating agent. Moreover, F127 and Co(NO 3 ) 2 are used as template and metallic precursor, respectively. The Co nanoparticles embedded, N-doped mesoporous carbon annealed at 800 °C (denoted as MFCo800) shows high electrocatalytic activity for hydrogen evolution reaction (HER) with high current density and low overpotential, which has the ability to operate in both acidic and alkaline electrolytes. Copyright © 2017. Published by Elsevier Inc.

Stibathiolanes: Synthesis, solid state structure, and solution behavior

NASA Astrophysics Data System (ADS)

Fisher, Richard A.; Nielsen, Ralph B.; Davis, William M.; Buchwald, Stephen L.

1990-06-01

Interest in organometallic compounds of the main group metals has recently grown tremendously, due in part to the wide variety of applications of these compounds in the materials sciences. Despite this new activity, the synthetic strategies for main group organometallics have remained relatively undeveloped. The majority of syntheses of these compounds involve classical metathesis reactions between a main group halide and an organometallic compound such as an organolithium or Grignard reagent and are limited by a lack of selectivity and by the availability of suitable organometallic precursors. The latter limitation is severe for main group metallacycles because of the paucity of suitable 1, n(n=3,4,5)-dianionic reagents or their equivalents, which are most often used for the synthesis of this class of molecules.

Synthesis of sub-micro-flakes CrSe2 on glass and (110) Si substrates by solvothermal method

NASA Astrophysics Data System (ADS)

Tang, Qingkai; Liu, Changyou; Zhang, Binbin; Jie, Wanqi

2018-06-01

Layered structure MX2 (M = transition metal, X = S, Se and Te) chalcogenides have rich physic properties and potential applications. While it is still a challenge to prepare the chalcogenides by solvothermal method. In this work, we reported a new solution method to prepare CrSe2 sub-micro-flakes on different substrates. The surface morphologies, structures and compositions of the precursor CrSe2(en)1/2 and CrSe2 were investigated by SEM, XRD, thermogravimetric, IR and Raman spectra. The CrSe2 flakes with the sizes of 5-15 μm were obtained on both glass and (110) Si crystalline substrates. The formation mechanism of CrSe2 sub-micro-flakes is suggested.

Aqueous citrato-oxovanadate(IV) precursor solutions for VO2: synthesis, spectroscopic investigation and thermal analysis.

PubMed

Peys, Nick; Adriaensens, Peter; Van Doorslaer, Sabine; Gielis, Sven; Peeters, Ellen; De Dobbelaere, Christopher; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

2014-09-07

An aqueous precursor solution, containing citrato-VO(2+) complexes, is synthesized for the formation of monoclinic VO2. With regard to the decomposition of the VO(2+) complexes towards vanadium oxide formation, it is important to gain insights into the chemical structure and transformations of the precursor during synthesis and thermal treatment. Hence, the conversion of the cyclic [V4O12](4-) ion to the VO(2+) ion in aqueous solution, using oxalic acid as an acidifier and a reducing agent, is studied by (51)Vanadium nuclear magnetic resonance spectroscopy. The citrate complexation of this VO(2+) ion and the differentiation between a solution containing citrato-oxalato-VO(2+) and citrato-VO(2+) complexes are studied by electron paramagnetic resonance and Fourier transform infra-red spectroscopy. In both solutions, the VO(2+) containing complex is mononuclear and has a distorted octahedral geometry with a fourfold R-CO2(-) ligation at the equatorial positions and likely a fifth R-CO2(-) ligation at the axial position. Small differences in the thermal decomposition pathway between the gel containing citrato-oxalato-VO(2+) complexes and the oxalate-free gel containing citrato-VO(2+) complexes are observed between 150 and 200 °C in air and are assigned to the presence of (NH4)2C2O4 in the citrato-oxalato-VO(2+) solution. Both precursor solutions are successfully used for the formation of crystalline vanadium oxide nanostructures on SiO2, after thermal annealing at 500 °C in a 0.1% O2 atmosphere. However, the citrato-oxalato-VO(2+) and the oxalate-free citrato-VO(2+) solution result in the formation of monoclinic V6O13 and monoclinic VO2, respectively.

Low-temperature MOCVD deposition of Bi2Te3 thin films using Et2BiTeEt as single source precursor

NASA Astrophysics Data System (ADS)

Bendt, Georg; Gassa, Sanae; Rieger, Felix; Jooss, Christian; Schulz, Stephan

2018-05-01

Et2BiTeEt was used as single source precursor for the deposition of Bi2Te3 thin films on Si(1 0 0) substrates by metal organic chemical vapor deposition (MOCVD) at very low substrate temperatures. Stoichiometric and crystalline Bi2Te3 films were grown at 230 °C, which is approximately 100 °C lower compared to conventional MOCVD processes using one metal organic precursors for each element. The Bi2Te3 films were characterized using scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. The elemental composition of the films, which was determined by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, was found to be strongly dependent of the substrate temperature.

Process for producing clad superconductive materials

DOEpatents

Cass, Richard B.; Ott, Kevin C.; Peterson, Dean E.

1992-01-01

A process for fabricating superconducting composite wire by the steps of placing a superconductive precursor admixture capable of undergoing a self propagating combustion in stoichiometric amounts sufficient to form a superconductive product within a metal tube, sealing one end of said tube, igniting said superconductive precursor admixture whereby said superconductive precursor admixture endburns along the length of the admixture, and cross-section reducing said tube at a rate substantially equal to the rate of burning of said superconductive precursor admixture and at a point substantially planar with the burnfront of the superconductive precursor mixture, whereby a clad superconductive product is formed in situ, the product characterized as superconductive without a subsequent sintering stage, is disclosed.

Development of an activated carbon filter to remove NO2 and HONO in indoor air.

PubMed

Yoo, Jun Young; Park, Chan Jung; Kim, Ki Yeong; Son, Youn-Suk; Kang, Choong-Min; Wolfson, Jack M; Jung, In-Ha; Lee, Sung-Joo; Koutrakis, Petros

2015-05-30

To obtain the optimum removal efficiency of NO2 and HONO by coated activated carbon (ACs), the influencing factors, including the loading rate, metal and non-metal precursors, and mixture ratios, were investigated. The NOx removal efficiency (RE) for K, with the same loading (1.0 wt.%), was generally higher than for those loaded with Cu or Mn. The RE of NO2 was also higher when KOH was used as the K precursor, compared to other K precursors (KI, KNO3, and KMnO4). In addition, the REs by the ACs loaded with K were approximately 38-55% higher than those by uncoated ACs. Overall, the REs (above 95%) of HONO and NOx with 3% KOH were the highest of the coated AC filters that were tested. Additionally, the REs of NOx and HONO using a mixing ratio of 6 (2.5% PABA (p-aminobenzoic acid)+6% H3PO4):4 (3% KOH) were the highest of all the coatings tested (both metal and non-metal). The results of this study show that AC loaded with various coatings has the potential to effectively reduce NO2 and HONO levels in indoor air. Copyright © 2015 Elsevier B.V. All rights reserved.

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

DOEpatents

Wong, Stanislaus S; Hongjun, Zhou

2012-11-27

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

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.

Modification of Different Zirconium Propoxide Precursors by Diethanolamine. Is There a Shelf Stability Issue for Sol-Gel Applications?

PubMed Central

Spijksma, Gerald I.; Blank, Dave H. A.; Bouwmeester, Henny J. M.; Kessler, Vadim G.

2009-01-01

Modification of different zirconium propoxide precursors with H2dea was investigated by characterization of the isolated modified species. Upon modification of zirconium n-propoxide and [Zr(OnPr)(OiPr)3(iPrOH)]2 with ½ a mol equivalent of H2dea the complexes [Zr2(OnPr)6(OCH2CH2)2NH]2 (1) and [Zr2(OnPr)2(OiPr)4(OCH2CH2)2NH]2 (2) were obtained. However, 1H-NMR studies of these tetranuclear compounds showed that these are not time-stable either in solution or solid form. The effect of this time instability on material properties is demonstrated by light scattering and TEM experiments. Modification of zirconium isopropoxide with either ½ or 1 equivalent mol of H2dea results in formation of the trinuclear complex, Zr{η3μ2-NH(C2H4O)2}3[Zr(OiPr)3]2(iPrOH)2 (3) countering a unique nona-coordinated central zirconium atom. This complex 3 is one of the first modified zirconium propoxide precursors shown to be stable in solution for long periods of time. The particle size and morphology of the products of sol-gel synthesis are strongly dependent on the time factor and eventual heat treatment of the precursor solution. Reproducible sol-gel synthesis requires the use of solution stable precursors. PMID:20087472

Production of battery grade materials via an oxalate method

DOEpatents

Belharouak, Ilias; Amine, Khalil

2016-05-17

An active electrode material for electrochemical devices such as lithium ion batteries includes a lithium transition metal oxide which is free of sodium and sulfur contaminants. The lithium transition metal oxide is prepared by calcining a mixture of a lithium precursor and a transition metal oxalate. Electrochemical devices use such active electrodes.

Production of battery grade materials via an oxalate method

DOEpatents

Belharouak, Ilias; Amine, Khalil

2014-04-29

An active electrode material for electrochemical devices such as lithium ion batteries includes a lithium transition metal oxide which is free of sodium and sulfur contaminants. The lithium transition metal oxide is prepared by calcining a mixture of a lithium precursor and a transition metal oxalate. Electrochemical devices use such active electrodes.

Solution combustion synthesis of the nanocrystalline NCM oxide for lithium-ion battery uses

NASA Astrophysics Data System (ADS)

Habibi, Amirhosein; Jalaly, Maisam; Rahmanifard, Roohollah; Ghorbanzadeh, Milad

2018-02-01

In this study, the NCM cathode with a chemical composition of {{{LiNi}}}1/3}{{{Co}}}1/3}{{{Mn}}}1/3}{{{O}}}2 were synthesized through a solution combustion method. In this method, metal nitrates and urea were used as precursors and fuel, respectively. The powder obtained from combustion were transferred into a alumina crucible and insert to the muffle furnace and calcined at 750 °C for 15 h. The crystallite size of the sample was calculated with sherer equation to be about 41 nm. The prepared cathode were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC) and battery charge-discharge test. The initial charge and discharge capacities of {{{LiNi}}}1/3}{{{Co}}}1/3}{{{Mn}}}1/3}{{{O}}}2 electrode containing 94% active material at a rate of 0.05 C in voltage window of 2.5-4.3 V at room temperature was obtained 168.03 and 150.01 mAh g-1, respectively.

Carbohydrate-Assisted Combustion Synthesis To Realize High-Performance Oxide Transistors.

PubMed

Wang, Binghao; Zeng, Li; Huang, Wei; Melkonyan, Ferdinand S; Sheets, William C; Chi, Lifeng; Bedzyk, Michael J; Marks, Tobin J; Facchetti, Antonio

2016-06-08

Owing to high carrier mobilities, good environmental/thermal stability, excellent optical transparency, and compatibility with solution processing, thin-film transistors (TFTs) based on amorphous metal oxide semiconductors (AOSs) are promising alternatives to those based on amorphous silicon (a-Si:H) and low-temperature (<600 °C) poly-silicon (LTPS). However, solution-processed display-relevant indium-gallium-tin-oxide (IGZO) TFTs suffer from low carrier mobilities and/or inferior bias-stress stability versus their sputtered counterparts. Here we report that three types of environmentally benign carbohydrates (sorbitol, sucrose, and glucose) serve as especially efficient fuels for IGZO film combustion synthesis to yield high-performance TFTs. The results indicate that these carbohydrates assist the combustion process by lowering the ignition threshold temperature and, for optimal stoichiometries, enhancing the reaction enthalpy. IGZO TFT mobilities are increased to >8 cm(2) V(-1) s(-1) on SiO2/Si gate dielectrics with significantly improved bias-stress stability. The first correlations between precursor combustion enthalpy and a-MO densification/charge transport are established.

Forming MOFs into spheres by use of molecular gastronomy methods.

PubMed

Spjelkavik, Aud I; Aarti; Divekar, Swapnil; Didriksen, Terje; Blom, Richard

2014-07-14

A novel method utilizing hydrocolloids to prepare nicely shaped spheres of metal-organic frameworks (MOFs) has been developed. Microcrystalline CPO-27-Ni particles are dispersed in either alginate or chitosan solutions, which are added dropwise to solutions containing, respectively, either divalent group 2 cations or base that act as gelling agents. Well-shaped spheres are immediately formed, which can be dried into spheres containing mainly MOF (>95 wt %). The spheronizing procedures have been optimized with respect to maximum specific surface area, shape, and particle density of the final sphere. At optimal conditions, well-shaped 2.5-3.5 mm diameter CPO-27-Ni spheres with weight-specific surface areas <10 % lower than the nonformulated CPO-27-Ni precursor, and having sphere densities in the range 0.8 to 0.9 g cm(-3) and particle crushing strengths above 20 N, can be obtained. The spheres are well suited for use in fixed-bed catalytic or adsorption processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aluminum Coating Influence on Nitride Layer Performance Deposited by MO-CVD in Fluidized Bed on Austenitic Stainless Steel Substrate

NASA Astrophysics Data System (ADS)

Găluşcă, D. G.; Perju, M. C.; Nejneru, C.; Burduhos Nergiş, D. D.; Lăzărescu, I. E.

2018-06-01

The modification of surface properties by duplex treatments, involving the overlapping of two surface treatment techniques, has been established as an intelligent solution to create new applications for the substrate metallic material. There are driveline components operating under very tough wear and corrosion conditions, with high temperature and humidity variations. Such components are usually made of high Cr and Ni stainless steel and for the hardening of surfaces it is recommended a thermo chemical treatment. Since stainless steels, especially austenitic stainless steels, are difficult to nitride, experimental studies focus on increasing the depth of the nitride layer and surface hardness. Achieving the goal involves changing active layer chemical composition by introducing aluminum in the surface layer. In order to find a solution, a new surface treatment technique is produced by combining aluminum thin films by MO-CVD in a fluidized bed using a triisobutylaluminum precursor with a thermo chemical nitriding treatment.

General control of transition-metal-doped GaN nanowire growth: toward understanding the mechanism of dopant incorporation.

PubMed

Stamplecoskie, Kevin G; Ju, Ling; Farvid, Shokouh S; Radovanovic, Pavle V

2008-09-01

We report the first synthesis and characterization of cobalt- and chromium-doped GaN nanowires (NWs), and compare them to manganese-doped GaN NWs. Samples were synthesized by chemical vapor deposition method, using cobalt(II) chloride and chromium(III) chloride as dopant precursors. For all three impurity dopants hexagonal, triangular, and rectangular NWs were observed. The fraction of NWs having a particular morphology depends on the initial concentration of the dopant precursors. While all three dopant ions have the identical effect on GaN NW growth and faceting, Co and Cr are incorporated at much lower concentrations than Mn. These findings suggest that the doping mechanism involves binding of the transition-metal intermediates to specific NW facets, inhibiting their growth and causing a change in the NW morphology. We discuss the doping concentrations of Mn, Co, and Cr in terms of differences in their crystal-field stabilization energies (DeltaCFSE) in their gas-phase intermediates and in substitutionally doped GaN NWs. Using iron(III) chloride and cobalt(II) acetate as dopant precursors we show that the doping concentration dependence on DeltaCFSE allows for the prediction of achievable doping concentrations for different dopant ions in GaN NWs, and for a rational choice of a suitable dopant-ion precursor. This work further demonstrates a general and rational control of GaN NW growth using transition-metal impurities.

Oxidation Induced Doping of Nanoparticles Revealed by in Situ X-ray Absorption Studies.

PubMed

Kwon, Soon Gu; Chattopadhyay, Soma; Koo, Bonil; Dos Santos Claro, Paula Cecilia; Shibata, Tomohiro; Requejo, Félix G; Giovanetti, Lisandro J; Liu, Yuzi; Johnson, Christopher; Prakapenka, Vitali; Lee, Byeongdu; Shevchenko, Elena V

2016-06-08

Doping is a well-known approach to modulate the electronic and optical properties of nanoparticles (NPs). However, doping at nanoscale is still very challenging, and the reasons for that are not well understood. We studied the formation and doping process of iron and iron oxide NPs in real time by in situ synchrotron X-ray absorption spectroscopy. Our study revealed that the mass flow of the iron triggered by oxidation is responsible for the internalization of the dopant (molybdenum) adsorbed at the surface of the host iron NPs. The oxidation induced doping allows controlling the doping levels by varying the amount of dopant precursor. Our in situ studies also revealed that the dopant precursor substantially changes the reaction kinetics of formation of iron and iron oxide NPs. Thus, in the presence of dopant precursor we observed significantly faster decomposition rate of iron precursors and substantially higher stability of iron NPs against oxidation. The same doping mechanism and higher stability of host metal NPs against oxidation was observed for cobalt-based systems. Since the internalization of the adsorbed dopant at the surface of the host NPs is driven by the mass transport of the host, this mechanism can be potentially applied to introduce dopants into different oxidized forms of metal and metal alloy NPs providing the extra degree of compositional control in material design.

The influence of the precursor compositional ratio on Cu2ZnSnS4 films prepared by using sulfurization of the metallic precursor

NASA Astrophysics Data System (ADS)

Amal, Muhamad I.; Kim, Kyoo Ho

2013-12-01

Cu2ZnSnS4 (CZTS) films were prepared by using the sulfurization of sputtered metallic precursors. The compositional ratio of the CZTS films was slightly different compared to their initial metallic precursors due to elemental loss during annealing. The Cu/(Zn+Sn) ratio for the CZTS-1, CZTS-2 and CZTS-3 films were 0.91, 1.06 and 1.21, respectively. In addition, all films had a compositional ratio of Zn/Sn >1. The grain sizes of the CZTS films increased with increasing Cu ratio. X-ray diffraction and Raman spectroscopy showed that the CZTS films with an excess of copper and zinc had secondary phases of Cu2SnS3 and ZnS. The optical band gap and absorption coefficient for all CZTS films in the range of the experimental compositions were calculated to be 1.5 eV and >104 cm-1, respectively. The presence of secondary phases related to compositional ratio in the CZTS films influenced the electrical properties. The CZTS-1 film with a Cu-poor and Zn-rich composition whose a carrier concentration, an electrical mobility, and a resistivity values were 2.29 × 1018 cm-3, 10.29 cm2 V-1 s-1, 3.16 Ω cm, is the most suitable for solar-cell applications.

Poultry litter-based activated carbon for removing heavy metal ions in water.

PubMed

Guo, Mingxin; Qiu, Guannan; Song, Weiping

2010-02-01

Utilization of poultry litter as a precursor material to manufacture activated carbon for treating heavy metal-contaminated water is a value-added strategy for recycling the organic waste. Batch adsorption experiments were conducted to investigate kinetics, isotherms, and capacity of poultry litter-based activated carbon for removing heavy metal ions in water. It was revealed that poultry litter-based activated carbon possessed significantly higher adsorption affinity and capacity for heavy metals than commercial activated carbons derived from bituminous coal and coconut shell. Adsorption of metal ions onto poultry litter-based carbon was rapid and followed Sigmoidal Chapman patterns as a function of contact time. Adsorption isotherms could be described by different models such as Langmuir and Freundlich equations, depending on the metal species and the coexistence of other metal ions. Potentially 404 mmol of Cu2+, 945 mmol of Pb2+, 236 mmol of Zn2+, and 250-300 mmol of Cd2+ would be adsorbed per kg of poultry litter-derived activated carbon. Releases of nutrients and metal ions from litter-derived carbon did not pose secondary water contamination risks. The study suggests that poultry litter can be utilized as a precursor material for economically manufacturing granular activated carbon that is to be used in wastewater treatment for removing heavy metals.

Regulation of the Deposition Morphology of Inkjet-Printed Crystalline Materials via Polydopamine Functional Coatings for Highly Uniform and Electrically Conductive Patterns.

PubMed

Liu, Liang; Ma, Siyuan; Pei, Yunheng; Xiong, Xiao; Sivakumar, Preeth; Singler, Timothy J

2016-08-24

We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive delivery of functional materials.

Method for forming polymerized microfluidic devices

DOEpatents

Sommer, Gregory J [Livermore, CA; Hatch, Anson V [Tracy, CA; Wang, Ying-Chih [Pleasanton, CA; Singh, Anup K [Danville, CA; Renzi, Ronald F [Tracy, CA; Claudnic, Mark R [Livermore, CA

2011-11-01

Methods for making a micofluidic device according to embodiments of the present invention include defining a cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

Method for forming polymerized microfluidic devices

DOEpatents

Sommer, Gregory J.; Hatch, Anson V.; Wang, Ying-Chih; Singh, Anup K.; Renzi, Ronald F.; Claudnic, Mark R.

2013-03-12

Methods for making a microfluidic device according to embodiments of the present invention include defining.about.cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

Effect of Phosphine-Free Selenium Precursor Reactivity on The Optical and Vibrational properties of Colloidal CdSe Nanocrystals

NASA Astrophysics Data System (ADS)

Thi, L. A.; Lieu, N. T. T.; Hoa, N. M.; Tran, N.; Binh, N. T.; Quang, V. X.; Nghia, N. X.

2018-03-01

Phosphine-free selenium precursor solutions have been prepared by heating at temperatures ranging from 160 °C to 240 °C and studied by means of infrared absorption spectroscopy. The colloidal CdSe nanocrystals (NCs) synthesized from all those solutions by the wet chemical method. The influence of heating temperature on the chemical reactivity of selenium precursor and its role on the optical and vibrational properties of CdSe NCs are discussed in details. Their morphology, particle size, structural, optical and vibrational properties were investigated using transmission electron microscopy, X-ray diffraction, UV-Vis, fluorescence and Raman spectroscopy, respectively.