Showing papers on "Graphene oxide paper published in 2004"

Template Synthesis and Photocatalytic Properties of Porous Metal Oxide Spheres Formed by Nanoparticle Infiltration

Abstract: Porous polymeric beads have been used as templates for the fabrication of porous metal oxide spheres. The beads were soaked in sols of titanium dioxide, zirconium dioxide, iron oxide, aluminum oxide, indium oxide, tin oxide, and cerium oxide. Successful infiltration and templating was obtained for titania, zirconia, tin oxide, and ceria giving monodisperse, nonaggregated spheres with a porous surface and inner structure. The use of iron and aluminum oxide sols resulted in cracked spheres with excess oxide material on the sphere surfaces, and in the case of indium oxide, broken, hollow, shell-like structures were produced. Combining the iron, aluminum, or indium oxide sols with the titania sol, at a 1:1 weight ratio, and impregnating the template produced inorganic spheres containing the two metal oxides. The photocatalytic properties of the titania and mixed titania/indium oxide spheres were studied by monitoring the decomposition of 2-chlorophenol as a function of time and solution pH. Both the porous ti...

Process for producing nano-scaled graphene plates

Abstract: A process for producing nano-scaled graphene plates with each plate comprising a sheet of graphite plane or multiple sheets of graphite plane with the graphite plane comprising a two-dimensional hexagonal structure of carbon atoms. The process includes the primary steps of: (a) providing a powder of fine graphite particles comprising graphite crystallites with each crystallite comprising one sheet or normally a multiplicity of sheets of graphite plane bonded together; (b) exfoliating the graphite crystallites to form exfoliated graphite particles, which are characterized by having at least two graphite planes being either partially or fully separated from each other; and (c) subjecting the exfoliated graphite particles to a mechanical attrition treatment to further reduce at least one dimension of the particles to a nanometer scale, <100 nm, for producing the nano-scaled graphene plates.

Combustion looping using composite oxygen carriers

Abstract: A method for producing hydrogen gas is provided and comprises reducing a metal oxide in a reduction reaction between a carbon-based fuel and a metal oxide to provide a reduced metal or metal oxide having a lower oxidation state, and oxidizing the reduced metal or metal oxide to produce hydrogen and a metal oxide having a higher oxidation state. The metal or metal oxide is provided in the form of a porous composite of a ceramic material containing the metal or metal oxide. The porous composite may comprise either a monolith, pellets, or particles.

Mass production of carbon nanostructures

Abstract: Carbon nanostructures are mass produced from graphite. In particularly preferred aspects, graphene is thermo-chemically derived from graphite and used in numerous compositions. In further preferred aspects, the graphene is re-shaped to form other nanostructures, including nanofractals, optionally branched open-ended SWNT, nanoloops, and nanoonions.

Supermolecular Self-Assembly of Graphene Sheets: Formation of Tube-in-Tube Nanostructures

Abstract: Graphitic impurity nanoparticles were reorganized outside and inside of carbon nanotubes to produce novel tube-in-tube nanostructures. The graphitic nanoparticles were disintegrated into small graphene sheets by an intercalation-exfoliation process with nitric acid, during which the graphene sheets were simultaneously modified with carboxyl and hydroxyl groups at their edges. The modified graphene sheets were self-organized outside and inside of pristine carbon nanotubes in an acid-catalyzed esterification process, leading to an assembly of wellconstructed tube-in-tube nanostructures. Carbon nanotubes are basically constituted by sp 2 C-C covalent bonds as in graphite planes. Their syntheses have been highly successful following various routes, such as laser evaporation or arc-discharge of graphite, catalytic chemical vapor deposition, and decomposition of organic explosives. 1-4 These methods are based on a common key process: the assembly of small carbon species (Cn) generated at high temperatures. The studies on the structures of carbon nanotubes have shown that the practically obtained nanotubes are highly defective and have a local structure similar to that of turbostratic graphite. 5,6 The presence of discontinued defects in the tube structures means that an individual tube could be actually viewed as an assembly of small graphene sheets and that they could be directly synthesized from the graphene sheets under mild conditions if proper organization technology is available. Because of the anisotropic lamellar structure of graphite, single or thinly stacked graphene sheets can be easily obtained by an intercalation-exfoliation process against bulk graphite with inorganic acids such as nitric, suphuric, and perchloric acids. 7-10 This process has been developed industrially over 15 years to produce flexible graphite for the application of sealing gaskets. In the synthesized carbon nanotube samples, graphitic impurity nanoparticles are always present. They seriously hamper the accurate characterization of the bulk properties of nanotubes and affect their practical applications. To remove these impurities, various purification methods have been developed. 11-17 Although the graphitic nanoparticles intrinsically contain richer sub-stable nonhexagonal rings and thus are more reactive than carbon nanotubes, 11 the presence of defects in the tube structures renders the purification difficult. Furthermore, carbonaceous impurities are also frequently present in the inner voids of tubes. 5 These internal

A negative active material for lithium secondary battery and a method for preparing same

Abstract: Provided are an anode active material for a lithium secondary battery having high reversible capacity and excellent charge/discharge efficiency, comprising a complex composed of ultra-fine Si phase particles and an oxide surrounding the ultra-fine Si phase particles, and a carbon material; and a method for preparing the same. The present invention also provides a method for preparing an anode active material for a lithium secondary battery comprising producing a complex composed of ultra-fine Si particles and an oxide surrounding the ultra-fine Si particles by mixing a silicon oxide and a material having an absolute value of oxide formation enthalpy (ΔHfor) greater than that of the silicon oxide and negative oxide formation enthalpy by a mechanochemical process or subjecting them to a thermochemical reaction to reduce the silicon oxide; and mixing the Si phase-containing oxide complex and carbon material.

Method for backside surface passivation of solar cells and solar cells with such passivation

Abstract: The present invention provides a method for dielectric passivating the surface of a solar cell by accumulation of negative fixed charges of a first type at the interface between semiconductor material and a passivating material. According to the invention the passivating material comprises an oxide system, for example a binary oxide system, comprising Al2O3 and at least one metal oxide or metalloid oxide which enhances the tetrahedral structure of Al2O3, for example, an (Al2O3)x(TiO2)1-x alloy. In this way it is possible to combine the desirable properties from at least two different oxides, while eliminating the undesirable properties of each individual material. The oxide system can be deposited onto the semiconductor surface by means of a sol-gel method, comprising the steps of formation of the metal oxide and/or metalloid oxide sol and the aluminum solution and then carefully mixing these together under stirring and ultrasonic treatment. Thin films of the oxide system can then be deposited onto the semiconductor surface by means of spin coating followed by a temperature treatment.

Negative active material for lithium secondary battery and method for preparating same

Abstract: Provided are an anode active material for a lithium secondary battery having high reversible capacity and excellent charge/discharge efficiency, comprising a complex composed of ultra-fine Si phase particles and an oxide surrounding the ultra-fine Si phase particles, and a carbon material; and a method for preparing the same. The present invention also provides a method for preparing an anode active material for a lithium secondary battery comprising producing a complex composed of ultra-fine Si particles and an oxide surrounding the ultra-fine Si particles by mixing a silicon oxide and a material having an absolute value of oxide formation enthalpy (ΔHfor) greater than that of the silicon oxide and negative oxide formation enthalpy by a mechanochemical process or subjecting them to a thermochemical reaction to reduce the silicon oxide; and mixing the Si phase-containing oxide complex and carbon material.

Semiconductor constructions comprising cerium oxide and titanium oxide

Abstract: The invention includes semiconductor constructions comprising dielectric materials which contain cerium oxide and titanium oxide. The dielectric materials can contain a homogeneous distribution of cerium oxide and titanium oxide, and/or can contain a laminate of cerium oxide and titanium oxide. The dielectric materials can be incorporated into any suitable semiconductor devices, including, for example, capacitor devices, transistor devices, and flash memory devices. The invention also includes methods of utilizing atomic layer deposition to form laminates of cerium oxide and titanium oxide.

Tribological behaviour of oxide/graphite composite coatings deposited using electrolytic plasma process

Abstract: The research was intended to deposit a low-friction coating on a cast Al–Si alloy substrate using an electrolytic plasma process (EPP) and then investigate tribological behaviour of the coating. The coating was designed to have a bi-layered structure consisting of an oxide underlayer and oxide/graphite lubricant composite top layer. A symmetrical AC power supply, operating at a relatively low voltage (less than 250 V), was used in the EPP treatment. Tribological properties of coatings with different thicknesses were tested using a pin-on-disc tribometer. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize microstructures and morphologies of the coatings. It was found that an AC power could be successfully used to produce oxide and oxide/graphite composite coatings on aluminium alloys. Both thick (50 μm) oxide and oxide/graphite composite coatings had high wear. However, the oxide/graphite composite coating was superior to the single-layered oxide coating because it had a low coefficient of friction (0.22) and exhibited good compatibility with the steel counterface during dry tribological testing.

High dielectric constant transition metal oxide materials

Abstract: A transition metal oxide dielectric material is doped with a non-metal in order to enhance the electrical properties of the metal oxide. In a preferred embodiment, a transition metal oxide is deposited over a bottom electrode and implanted with a dopant. In a preferred embodiment, the metal oxide is hafnium oxide or zirconium oxide and the dopant is nitrogen. The dopant can convert the crystal structure of the hafnium oxide or zirconium oxide to a tetragonal structure and increase the dielectric constant of the metal oxide.

Water Vapor Barrier Properties of Transparent SnO2−SiOx Composite Films on Polymer Substrate

Abstract: Composite thin films consisting of silicon oxide and tin oxide have been deposited on polycarbonate substrates as gas barrier films, using a thermal evaporation process in an oxygen gas environment. Water vapor permeation through the composite films is significantly affected by the chemical interaction of water vapor with the composite oxide films and the microstructure of the composite oxide films. The chemical interaction of water vapor with oxide films has been investigated by the considering the refractive index obtained from ellipsometry and the OH group peak from X-ray photoelectron spectroscopy, and the microstructure of the composite oxide films has been characterized using atomic force microscopy. As the tin oxide is added to the silicon oxide, the refractive index and OH group peak intensity of the composite films increase, and the water vapor transmission rate through the composite oxide films shows a lower value than that through the single-element oxide films, such as tin oxide and silicon ox...

Protective coating for oxide ceramic based composites

Abstract: A layered structure includes a substrate comprising a layer of an oxide/oxide ceramic based composite material, a first oxide layer disposed directly on the substrate and formed from a material that has no greater than about 10% porosity and is substantially impermeable by water vapor, and a second oxide layer disposed directly on the first oxide layer and having a greater porosity than the first oxide layer. Either or both the first and second oxide layers of the coating system may be deposited using a plasma spraying process, a slurry deposition process which is followed by a sintering step, or an EB-PVD process.

Low temperature nitridation of amorphous high-K metal-oxide in inter-gates insulator stack

Abstract: An OXO-type inter-poly insulator (where X is a high-K metal oxide and O is an insulative oxide) is defined by forming an amorphous metal oxide layer on a silicon-based insulator (e.g., a silicon oxide layer) and then nitridating at least upper and lower sub-layers of the amorphous metal oxide with a low temperature plasma treatment that maintains temperature below the recrystallization temperature of the amorphous material. Such a plasma treatment has been found to improve breakdown voltage characteristics of the insulator. In one embodiment, the metal oxide includes aluminum oxide and it is fluorinated with low temperature plasma prior to nitridation.

In2O3 thin film resistivity control by doping metal oxide insulator for MFMox device applications

Abstract: The present invention discloses a novel ferroelectric transistor design using a resistive oxide film in place of the gate dielectric. By replacing the gate dielectric with a resistive oxide film, and by optimizing the value of the film resistance, the bottom gate of the ferroelectric layer is electrically connected to the silicon substrate, eliminating the trapped charge effect and resulting in the improvement of the memory retention characteristics. The resistive oxide film is preferably a doped conductive oxide in which a conductive oxide is doped with an impurity species. The doped conductive oxide is most preferred to be In2O3 with the dopant species being hafnium oxide, zirconium oxide, lanthanum oxide, or aluminum oxide.

Thin film dielectrics with perovskite structure and preparation thereof

Abstract: Methods of making a ternary oxide and a perovskite-related ternary oxide structure are described. The methods include reacting a binary oxide with a metal oxide or a metal hydroxide to form a ternary oxide dielectric layer on a substrate. Powders, anodes, pressed articles, and capacitors including the ternary oxide or perovskite-related ternary oxide structure as a dielectric layer or other layers are further described.

Metal particle-dispersed composite oxides, metal particle-dispersed composite oxide-sintered bodies, method of manufacturing metal particle-dispersed composite oxides, and hydrocarbon-based fuel reformer

Abstract: There is disclosed a metal particle-dispersed composite oxide comprising a matrix material containing a composite oxide comprising a non-reducible metal oxide and an easily reducible metal oxide, the composite oxide containing 0.01 to 0.25 mol % of at least one additive metal selected from Al, Sc, Cr, B, Fe, Ga, In, Lu, Nb and Si, surface metal particles precipitated on an outer surface of the matrix material containing the composite oxide, and inner metal particles precipitated on an inner surface of the matrix material containing the composite oxide.

High rate buffer layer for IBAD MgO coated conductors

Abstract: Articles are provided including a base substrate having a layer of an oriented material thereon, and, a layer of hafnium oxide upon the layer of an oriented material. The layer of hafnium oxide can further include a secondary oxide such as cerium oxide, yttrium oxide, lanthanum oxide, scandium oxide, calcium oxide and magnesium oxide. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of hafnium oxide or layer of hafnium oxide and secondary oxide.

Magnetic tunneling junction element having thin composite oxide film

Abstract: A tunneling junction element comprises: a substrate; a lower conductive layer formed on the substrate; a first oxide layer formed on the lower conductive layer and having a non-stoichiometric composition;a second oxide layer formed on the first oxide layer and having a stoichiometric composition; and an upper conductive layer formed on the second oxide layer, wherein the first oxide layer is oxidized during a process of forming the second oxide layer and has an oxygen concentration which is lower than an oxygen concentration of the second oxide layer and lowers with a depth in the first oxide layer, and the first and second oxide layers form a tunneling barrier.

Polymer-coated metal oxide and process for producing the same

Abstract: A novel polymer-coated metal oxide, wherein the polymer has a siloxane skeleton. Also provided is a process for producing the polymer-coated metal oxide which comprises bringing a metal oxide into contact with a solution of a polymer having a siloxane skeleton. The polymer can be thus bonded to the surface of the metal oxide. The polymer preferably has a branched structure. This branched polymer preferably is a dendritic polymer. The metal oxide preferably is glass, silica gel, titanium oxide, barium titanate, indium-tin oxide (ITO), aluminum oxide, nickel oxide, iron oxide, or the like.

Semiconductor device with high dielectric constant insulator and its manufacture

Abstract: A semiconductor device has: a silicon substrate; a silicon oxide layer formed on the surface of the silicon substrate; a high dielectric constant insulating film including a first oxide layer formed above the silicon oxide layer and made of a high dielectric constant film having a dielectric constant higher than silicon oxide and a first nitride layer formed above the first oxide layer and made of nitride having an oxygen intercepting capability, or a high dielectric constant insulating film including a first oxide film formed on the silicon oxide layer, a second oxide layer formed on the first oxide layer and a third oxide layer formed on the second oxide layer, the first and third oxide layers having an oxygen diffusion coefficient smaller than the second oxide layer; and a gate electrode formed on the high dielectric constant insulating layer and made of oxidizable material.

Ultrathin gate oxide with a reduced transition layer grown by plasma-assisted oxidation

Abstract: Ultrathin SiO2 grown by plasma-assisted oxidation (plasma oxide) has been investigated by high-resolution x-ray photoemission spectroscopy and medium energy ion scattering spectroscopy. We found that the plasma oxide grown at the low temperature of 400°C has a thinner transition layer than conventional thermal oxide. This thinner transition layer in the plasma oxide not only decreased the gate leakage current effectively, but also enhanced the reliability of the gate oxide. We attribute these electrical properties of the plasma oxide to the reduction of the transition layer.

Structural and Electrochromic Properties of Sol-Gel Made Tantalum Oxide and Tungsten Oxide Films

Abstract: Tantalum oxide and tungsten oxide thin films were prepared by spin coating techniques. The effect of tantalum concentration on the optical, structural and electrochromic properties of the films were studied. The optical, structural and electrochromic properties of pure, WO3, Ta2O5 and Ta2O5 doped WO3 thin films are described and compared to each other. Film characterization was made by cyclic voltammetry (CV) and scanning electron microscopy (SEM). The coatings were studied electrochemically in 1 M LiClO4 in propylene carbonate electrolytes. Electrochemical and optical characterizations show that the tantalum concentration affects the properties of sol-gel derived films significantly. Mechanical tests show that tantalum oxide films resist to abrasion well.

Processing and Properties of Graphene-Based Nanocomposites

Abstract: Fabrication of carbon nanotubes is expensive, particularly for the purifying process required to make them widely accepted for reinforcements and structural composite applications. Instead of trying to discover lower cost processes for nanotubes, we seek to develop an alternative nanoscale carbon material with comparable properties that can be produced cost-effectively and in larger quantities. These carbon nanomaterials are referred to as nanoscale graphene platelets (NGP). In this study, we fabricated and studied graphene-based nanocomposites by (1) exfoliating carbon or graphite materials using acid treatment, thermal and microwave expansion, and (2) examined the electrical and dielectric properties of the graphite reinforced polymers. Less than 1 wt% filler content was required to reach the percolation threshold (φc ) of transition in electrical conductivity and dielectric properties. Molecular dynamics simulation was employed to characterize the increase in elastic moduli for graphene platelets embedded in polymer matrices at molecular scale.Copyright © 2004 by ASME

Deposition oxide with improved oxygen bonding

Abstract: A deposition oxide interface with improved oxygen bonding and a method for bonding oxygen in an oxide layer are provided. The method includes depositing an M oxide layer where M is a first element selected from a group including elements chemically defined as a solid and having an oxidation state in a range of +2 to +5, plasma oxidizing the M oxide layer at a temperature of less than 400° C. using a high density plasma source, and in response to plasma oxidizing the M oxide layer, improving M-oxygen bonding in the M oxide layer. The plasma oxidation process diffuses excited oxygen radicals into the oxide layer. The plasma oxidation is performed at specified parameters including temperature, power density, pressure, process gas composition, and process gas flow. In some aspects of the method, M is silicon, and the oxide interface is incorporated into a thin film transistor.

Method for forming an oxide with improved oxygen bonding

Abstract: A deposition oxide interface with improved oxygen bonding and a method for bonding oxygen in an oxide layer are provided. The method includes depositing an M oxide layer where M is a first element selected from a group including elements chemically defined as a solid and having an oxidation state in a range of +2 to +5, plasma oxidizing the M oxide layer at a temperature of less than 400° C. using a high density plasma source, and in response to plasma oxidizing the M oxide layer, improving M-oxygen bonding in the M oxide layer. The plasma oxidation process diffuses excited oxygen radicals into the oxide layer. The plasma oxidation is performed at specified parameters including temperature, power density, pressure, process gas composition, and process gas flow. In some aspects of the method, M is silicon, and the oxide interface is incorporated into a thin film transistor.

MOCVD PGO thin films deposited on indium oxide for feram applications

Abstract: Methods of forming depositing a ferroelectric thin film, such as PGO, by preparing a substrate with an upper surface of silicon, silicon oxide, or a high-k material, such as hafnium oxide, zirconium oxide, aluminum oxide, and lanthanum oxide, depositing an indium oxide film over the substrate, and then depositing the ferroelectric film using MOCVD.

A Method for Fabricating a Superior Oxide'Nitride'Oxide Gate Stack

Abstract: A superior oxide/nitride/oxide (ONO) gate stack was demonstrated. High density plasma chemical vapor deposition was used to deposit the silicon nitride layer instead of the conventional low-pressure chemical vapor deposition for silicon/oxide/nitride/oxide/ silicon technology. The densified nitride layer was performed by high-temperature dry oxidation to form a thermally grown blocking oxide layer on the silicon nitride rather than a deposited oxide layer. The ONO gate stack shows large memory window, high breakdown voltage, and reliable endurance characteristics, which is a potential candidate for future nonvolatile memory technology.