Showing papers on "Graphene oxide paper published in 2006"

Raman spectrum of graphene and graphene layers.

Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process The G peak slightly down-shifts This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area

Graphene-based composite materials

Abstract: The remarkable mechanical properties of carbon nanotubes arise from the exceptional strength and stiffness of the atomically thin carbon sheets (graphene) from which they are formed. In contrast, bulk graphite, a polycrystalline material, has low fracture strength and tends to suffer failure either by delamination of graphene sheets or at grain boundaries between the crystals. Now Stankovich et al. have produced an inexpensive polymer-matrix composite by separating graphene sheets from graphite and chemically tuning them. The material contains dispersed graphene sheets and offers access to a broad range of useful thermal, electrical and mechanical properties. Individual sheets of graphene can be readily incorporated into a polymer matrix, giving rise to composite materials having potentially useful electronic properties. Graphene sheets—one-atom-thick two-dimensional layers of sp2-bonded carbon—are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in-plane values for graphite (∼3,000 W m-1 K-1 and 1,060 GPa, respectively); their fracture strength should be comparable to that of carbon nanotubes for similar types of defects1,2,3; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties4,5,6,7,8. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene-polymer composites via complete exfoliation of graphite9 and molecular-level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene–graphene composite formed by this route exhibits a percolation threshold10 of ∼0.1 volume per cent for room-temperature electrical conductivity, the lowest reported value for any carbon-based composite except for those involving carbon nanotubes11; at only 1 volume per cent, this composite has a conductivity of ∼0.1 S m-1, sufficient for many electrical applications12. Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.

Functionalized Single Graphene Sheets Derived from Splitting Graphite Oxide

Abstract: A process is described to produce single sheets of functionalized graphene through thermal exfoliation of graphite oxide. The process yields a wrinkled sheet structure resulting from reaction sites involved in oxidation and reduction processes. The topological features of single sheets, as measured by atomic force microscopy, closely match predictions of first-principles atomistic modeling. Although graphite oxide is an insulator, functionalized graphene produced by this method is electrically conducting.

Solution Properties of Graphite and Graphene

Abstract: Covalent derivatization of the acidic functional groups in oxidized graphite with octadecylamine renders graphite soluble in common organic solvents. Atomic force microscopic characterization of the soluble species supports the idea that the solutions consist of single and few layer graphene sheets, and we report the first solution properties of graphite.

Transition metal oxides as the buffer layer for polymer photovoltaic cells

Abstract: Polymer-based photovoltaic cells have been fabricated by inserting a thin, transparent, transition metal oxide layer between the transparent anode (indium tin oxide) and the polymer layer. Two different transition metal oxides, namely vanadium oxide and molybdenum oxide, were used and the device performance was compared. The surface of the oxide films and the interface between the polymer and the oxide was studied with the help of atomic force microscopy. The effect of the thickness of the oxide layer on electrical characteristics of the device was also studied and optimized thickness was achieved to give high power conversion efficiency of 3.3% under simulated AM1.5G illumination of 100mW∕cm2.

Highly ordered graphene for two dimensional electronics

Abstract: With expanding interest in graphene-based electronics, it is crucial that high quality graphene films be grown. Sublimation of Si from the 4H-SiC(0001) (Si-terminated) surface in ultrahigh vacuum is a demonstrated method to produce epitaxial graphene sheets on a semiconductor. In this letter the authors show that graphene grown from the SiC(0001¯) (C-terminated) surface are of higher quality than those previously grown on SiC(0001). Graphene grown on the C face can have structural domain sizes more than three times larger than those grown on the Si face while at the same time reducing SiC substrate disorder from sublimation by an order of magnitude.

Thermally exfoliated graphite oxide

Abstract: A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 m2/g to 2600 m2/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Stable dispersions of polymer-coated graphitic nanoplatelets

Abstract: A method of making a dispersion of reduced graphite oxide nanoplatelets involves providing a dispersion of graphite oxide nanoplatelets and reducing the graphite oxide nanoplatelets in the dispersion in the presence of a reducing agent and a polymer. The reduced graphite oxide nanoplatelets are reduced to an extent to provide a higher C/O ratio than graphite oxide. A stable dispersion having polymer-treated reduced graphite oxide nanoplatelets dispersed in a dispersing medium, such as water or organic liquid is provided. The polymer-treated, reduced graphite oxide nanoplatelets can be distributed in a polymer matrix to provide a composite material.

Vanadium oxide nanostructures: from zero-?to three-dimensional

Abstract: Oxide structures with nanometric dimensions exhibit novel physical and chemical properties, with respect to bulk oxide materials, due to the spatial confinement and the proximity of the substrate. They derive their atomic structure and morphology, on the one hand, from the interactions at the interface between the oxide overlayer and the substrate and, on the other hand, from kinetic constraints during the growth process. Here we describe the formation of vanadium oxide nanostructures on a single-crystal metal surface and their characterization by scanning tunnelling microscopy (STM) and ab initio density functional theory (DFT) calculations. We show that vanadium oxide nanostructures can be formed on Rh(111) with morphologies ranging from quasi-zero- to three-dimensional and that the oxide growth can be tuned into a particular dimensionality by careful adjustment of experimental parameters. These 'artificial oxide phases' display new physical and chemical properties, which make them potentially interesting materials for nanotechnology applications.

Process for nano-scaled graphene plates

Abstract: A process for producing a nano-scaled graphene plate. The material comprises a sheet of graphite plane or a multiplicity of sheets of graphite plane. The graphite plane is composed of a two-dimensional hexagonal lattice of carbon atoms and the plate has a length and a width parallel to the graphite plane and a thickness orthogonal to the graphite plane with at least one of the length, width, and thickness values being 100 nanometers or smaller. The process for producing nano-scaled graphene plate material comprises the steps of: a). partially or fully carbonizing a precursor polymer or heat-treating petroleum or coal tar pitch to produce a polymeric carbon containing micron- and/or nanometer-scaled graphite crystallites with each crystallite comprising one sheet or a multiplicity of sheets of graphite plane; b). exfoliating the graphite crystallites in the polymeric carbon; and c). subjecting the polymeric carbon containing exfoliated graphite crystallites to a mechanical attrition treatment to produce the nano-scaled graphene plate material.

Graphene intergrated circuit

Abstract: PROBLEM TO BE SOLVED: To provide a technology for integrating nonlinear elements containing graphene, and to improve degree of integration of a semiconductor. SOLUTION: The graphene integrated circuit has nonlinear elements, containing graphene formed on a silicon surface of a silicon carbide substrate. Its manufacturing method comprises a step of preparing the silicon carbide substrate, having the silicon surface covered with an insulation film; a step of removing the insulating film on a plurality of desired portions, to expose the silicon surface; a step of heating the substrate to form graphene on the exposed portions; a step of forming ohmic electrodes on the graphene, or a step of heating the substrate, having the silicon surface to form graphene on the silicon surface; a step of isolating the graphene; a step of forming an insulation film on the trenches formed by the isolation; and a step of forming ohmic electrodes on the graphene. COPYRIGHT: (C)2008,JPO&INPIT

Surface-treated titanium oxide sol and method for producing the same

Abstract: PROBLEM TO BE SOLVED: To provide coated titanium oxide for forming a transparent hard coat excellent in optical properties on a surface of a substrate of an optical element or the like. SOLUTION: Titanium oxide sol which ensures high transparency and light resistance is provided by coating titanium oxide sol particles with a layer comprising (a) a hydrated oxide of silicon or (b) a composite hydrated oxide of silicon and at least one metal species selected from tin, aluminum and zirconium. COPYRIGHT: (C)2007,JPO&INPIT

Oxide composite material and its production method

Abstract: PROBLEM TO BE SOLVED: To provide an oxide composite material consisting of an inorganic porous body with pores into which a relatively large amount of oxide nanoparticles are introduced and its production method and to provide an oxide composite material having a spherical shape having a monodisperse distribution and its production method. SOLUTION: The method for producing the oxide composite material comprises a first impregnation process in which the pores of the inorganic porous body are impregnated with a first solution comprising a metallocene or its derivative dissolved in a first solvent which is polymerized by heating, a polymerization process in which the first solvent is polymerized by heating the porous body and a first heat-treatment process in which the inorganic porous body is heat-treated at 400°C or higher in an atmosphere containing oxygen so that the metallocene or its derivative is thermally decomposed so as to produce a first metal oxide. The oxide composite material is produced with the method. COPYRIGHT: (C)2007,JPO&INPIT

Methods for forming thin oxide layers on semiconductor wafers

Abstract: An oxide layer on a silicon wafer may be removed by applying a process chemical such as hydrofluoric acid to the wafer This will typically remove substantially all of the existing oxide layer, leaving a bare silicon surface A high quality self-terminating chemical oxide layer may then be grown on the wafer The chemical oxide layer is then chemically etched to achieve a thinned oxide layer A layer of material, which may be a high-K dielectric material, is than applied onto the thinned oxide layer Microelectronic devices having improved electrical characteristics can be manufactured using this process

Coating method of metal oxide superfine particles on the surface of metal oxide and coating produced therefrom

Abstract: Disclosed are a method of coating the surface of metal oxide with ultrafine metal oxide particles and a coating produced thereby. Specifically, the method of coating the surface of metal oxide with ultrafine metal oxide particles, according to this invention, includes i) bringing metal (Ml) oxide into contact with an aqueous solution of a metal (M2) salt to be applied thereon, and ii) continuously mixing and reacting the contacted metal oxide with water at a reaction temperature of 200~700°C under pressure of 180~550 bar.

Fuel electrode precursor of low shrinkage rate in an electric power generation cell for a solid oxide fuel cell

Abstract: A fuel electrode precursor of low shrinkage rate in an electric power generation cell for a solid oxide fuel cell is provided, wherein: the fuel electrode precursor is made of a sintered body prepared from a green body constituted with oxide ceramic grains composed of at least one of yttria-stabilized zirconia, scandia-stabilized zirconia, samarium-doped ceria and gadolinium-doped ceria and metal oxide grains composed of at least one of nickel oxide, copper oxide and ruthenium oxide; and the fuel electrode precursor at least has a structure in which an iron-containing oxide is present in a grain boundary surrounding the metal oxide grains.

Method for manufacturing perovskite type oxide layer, method for manufacturing ferroelectric memory and method for manufacturing surface acoustic wave element

Abstract: A method for manufacturing a perovskite type oxide layer includes the steps of: forming, above a substrate, a first oxide layer composed of perovskite type oxide; forming, above the first oxide layer, a second oxide layer composed of at least one of a perovskite type oxide layer crystallized at a temperature lower than a crystallization temperature of the first oxide layer and a pyrochlore layer having elements identical with elements of the perovskite type oxide; forming an electrode layer above the second oxide layer; and conducting a heat treatment.

Methods of fabricating oxide layers on silicon carbide layers utilizing atomic oxygen

Abstract: Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500 °C to about 1300 °C, introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.

Graphene Based Spin Valve Devices

Abstract: Graphene is a name given to an atomic layer of carbon atoms densely packed into a benzene-ring structure with a nearest-neighbour distance of ~1.4Aring. This theoretical material is widely used in the description of the crystal structure and properties of graphite, large fullerenes and carbon nanotubes. As a first approximation, graphite is made of graphene layers relatively loosely stacked on top of each other with a fairly large interlayer distance of ~3.4Aring . Carbon nanotubes are usually thought of as graphene layers rolled into hollow cylinders. Graphene films are made by repeated peeling of small (mm-sized) mesas of highly-oriented pyrolytic graphite (HOPG). The exfoliation continues until flakes that are nearly invisible in an optical microscope are obtained. A simple spin valve structure has been fabricated from such films using electron beam lithography. This is based on a symmetrical electrode structure and relies on imperfections in the two ferromagnetic electrodes to give different switching fields for each electrode. Despite this highly non-optimised structure we observed a 10% change in resistance at 300 K as the applied field is swept between +450 G and -450 G. The 10% change in resistance is much larger than can be attributed to MR effects in the individual permalloy electrodes (2.5% maximum), giving confidence that it is due to the spin valve effect with the graphene acting as the non-magnetic conductor. Although spin valve effects have been observed in carbon nanotubes this is the first observation of this effect in planar graphene.

Field effect transistor using amorphous oxide film as channel layer

Abstract: A field effect transistor which has a channel layer of an amorphous oxide film comprising at least one material selected from a Ga-In-Zn oxide, a Sn-In-Zn oxide, an In-Zn-Ga-Mg oxide, an In-Sn oxide, an In-Ga oxide, and an In-Zn oxide, wherein the amorphous oxide film shows an electron carrier concentration in the range of 1014 to 1018/cm3, and wherein the amorphous oxide film contains hydrogen atoms at a concentration in the range of 1016 to 1020/cm3 is disclosed.

Synthesis of Aluminum Oxide Nanoparticles in an Aqueous Ammonium-Formaldehyde Solution

Abstract: A method of synthesis of the organic-inorganic nanocomposite consisting of a paraformaldehyde matrix and aluminum oxide nanoparticles is developed Spontaneous dispersion of the composite in water at various component ratios makes it possible to prepare a sol or gel of hydrated aluminum oxide No changes in the oxide particle dimensions are observed during storage of the composite

Thermally exfoliated graphite oxide

Abstract: A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 m2/g to 2600 m2/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Thermally exfoliated graphite oxide

Abstract: Modified graphite oxide material comprises a surface area thermally exfoliated graphite oxide is about

Method for forming substrates for MOS transistor components and its products

Abstract: The present invention provides a method for forming substrates for MOS (metal oxide semiconductor) transistor, comprising the following steps: (A) In a reduced-pressure environment having a pressure lower than 1×10−6 Torr, a base for accomplishing the surface reconstruction and a solid-state metal oxide source is provided, wherein the solid-state metal oxide source is chosen from the group consisting of the following: hafnium oxide, aluminum oxide, scandium oxide, yttrium oxide, titanium oxide, gallium gadolinium oxide and metal oxides of rare earth elements; and (B) vaporize the solid-state metal oxide source in order to make the solid-state metal oxide source become a metal oxide molecular beam and, in a working substrate temperature that is required to achieve an amorphous state of a first metal oxide film, deposit on the base having an amorphous state so as to further fabricate a substrate for MOS transistors.

Thermally highly loaded low-E layer system for glass panes comprises a metal oxide or mixed oxide separating layer arranged between a partial layer of zinc oxide and a partial layer of silicon nitride

Abstract: Thermally highly loaded low-E layer system comprises an antireflection upper layer having a partial layer of zinc oxide or mixed oxide (ZnMeO x) containing zinc oxide or a mixed oxide layer sequence of the type: ZnO: Al/ZnOMeO x, a partial layer of silicon nitride (Si 3N 4 or Si xO yN z) and a 0.5-5 nm thick separating layer made from a metal oxide or mixed oxide with a cubic crystal lattice arranged between the partial layers.