Simple Oxidation Process Research Articles

Preparation and characterization of nickel-coated graphite nanosheets

Nickel-coated graphite nanosheets have been fabricated by simple oxidation and reduction process. The resulting products have a homogeneous and consecutive distribution of nickel coated on the surface of graphite nanosheets. The addition of polyvinylpyrrolidone (PVP) can control the size of nickel particles. Scanning electron microscopy (SEM) images, XRD pattern of the composites all confirm the deposition of nickel. The magnetic property of the coated GNs was characterized by Magnetic Property Measurement System (MPMS).

Synthesis and Field Emission Properties of Rutile TiO2 Nanowires Arrays Grown Directly on a Ti Metal Self-Source Substrate

Large-area and uniform quasi-aligned titanium oxide (TiO2) nanowire arrays have been produced in situ on a titanium (Ti) foil by a simple high-temperature oxidation process with acetone as the oxidant. The products are characterized by X-ray diffraction, electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The TiO2 nanowires have a rutile single-crystalline structure. The typical diameters range from 20 to 50 nm and lengths are up to a few micrometers. Since the Ti foil serves as both the source of Ti and substrate, direct synthesis and assembly of TiO2 nanowire arrays on a conductive Ti substrate is accomplished in a single step. Consequently, good intrinsic adhesion and electrical contact are achieved naturally between the nanowires and metal substrate. Such TiO2 nanowire arrays exhibit good field emission properties with a low turn-on field of 4.1 V/microm boding well for applications in vacuum microelectronics.

Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons

Graphene, or single-layered graphite, with its high crystallinity and interesting semimetal electronic properties, has emerged as an exciting two-dimensional material showing great promise for the fabrication of nanoscale devices. Thin, elongated strips of graphene that possess straight edges, termed graphene ribbons, gradually transform from semiconductors to semimetals as their width increases, and represent a particularly versatile variety of graphene. Several lithographic, chemical and synthetic procedures are known to produce microscopic samples of graphene nanoribbons, and one chemical vapour deposition process has successfully produced macroscopic quantities of nanoribbons at 950 degrees C. Here we describe a simple solution-based oxidative process for producing a nearly 100% yield of nanoribbon structures by lengthwise cutting and unravelling of multiwalled carbon nanotube (MWCNT) side walls. Although oxidative shortening of MWCNTs has previously been achieved, lengthwise cutting is hitherto unreported. Ribbon structures with high water solubility are obtained. Subsequent chemical reduction of the nanoribbons from MWCNTs results in restoration of electrical conductivity. These early results affording nanoribbons could eventually lead to applications in fields of electronics and composite materials where bulk quantities of nanoribbons are required.

Iron isotopes in acid mine waters and iron-rich solids from the Tinto–Odiel Basin (Iberian Pyrite Belt, Southwest Spain)

The isotopic composition of Fe was determined in water, Fe-oxides and sulfides from the Tinto and Odiel Basins (South West Spain). As a consequence of sulfide oxidation in mine tailings both rivers are acidic (1.45 < pH < 3.85) and display high concentrations of dissolved Fe (up to 420 mmol l − 1 ) and sulphates (up to 1190 mmol l − 1 ). The δ 56Fe of pyrite-rich samples from the Rio Tinto and from the Tharsis mine ranged from − 0.56 ± 0.08‰ to + 0.25 ± 0.1‰. δ 56Fe values for Fe-oxides precipitates that currently form in the riverbed varied from − 1.98 ± 0.10‰ to 1.57 ± 0.08‰. Comparatively narrower ranges of values (− 0.18 ± 0.08‰ and + 0.21 ± 0.14‰) were observed in their fossil analogues from the Pliocene–Pleistocene and in samples from the Gossan (the oxidized layer that formed through exposure to oxygen of the massive sulfide deposits) (− 0.36 ± 0.12‰ to 0.82 ± 0.07‰). In water, δ 56Fe values ranged from − 1.76 ± 0.10‰ to + 0.43 ± 0.05‰. At the source of the Tinto River, fractionation between aqueous Fe(III) and pyrite from the tailings was less than would be expected from a simple pyrite oxidation process. Similarly, the isotopic composition of Gossan oxides and that of pyrite was different from what would be expected from pyrite oxidation. In rivers, the precipitation of Fe-oxides (mainly jarosite and schwertmannite and lesser amounts of goethite) from water containing mainly (more than 99%) Fe(III) with concentrations up to 372 mmol l − 1 causes variable fractionation between the solid and the aqueous phase (− 0.98‰ < Δ 56Fe solid–water < 2.25‰). The significant magnitude of the positive fractionation factor observed in several Fe(III) dominated water may be related to the precipitation of Fe(III) sulphates containing phases.

Site-specific growth of ZnO nanowires from patterned Zn via compatible semiconductor processing

An alternative method for site-selective growth of ZnO nanowires without the use of an Au catalyst or a ZnO thin-film seed layer is presented. Using conventional lithography and metallization semiconductor processing steps, regions for selective nanowire growth are defined using Zn, which acts as a self-catalyst for subsequent ZnO nanowire growth via a simple thermal oxidation process. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction reveal that the nanowires grown by this technique are single-crystalline wurtzite ZnO. Room temperature photoluminescence exhibits strong ultraviolet emission from these nanowires, indicating good optical properties. A series of experiments was conducted to elucidate the unique growth behavior of these nanowires directly from the Zn grains and a growth model is proposed.

Simple air oxidation synthesis and optical properties of S-doped ZnO microspheres

The S-doped ZnO microspheres with average diameter of 3 micrometers (μm) have been successfully synthesized by a simple air oxidation process of ZnS precursor. X-ray diffractometer (XRD) pattern indicates that the as-obtained sample is composed of ZnO and ZnS. The scanning electron microscopy (SEM) image shows that the exterior surfaces of the microspheres are composed of many nanoparticles with an average grain size of 100 nanometers (nm). The photoluminescence (PL) spectra show the broad excitation region with the main peak at 370 nm and strong green emission centered at 500 nm, which can be attributed to the oxygen vacancies caused by S replacement of O.

Lateral ZnO nanowire growth on a planar substrate using a growth barrier

In this work, we present a technique to confine zinc oxide (ZnO) nanowires to lateralgrowth while suppressing nanowire growth on the top surface of a planar substrate throughthe use of a growth barrier. Physical-vapour-deposited silicon dioxide and spin-on-glassdielectric were evaluated, and both have proven themselves as effective growth barriers.Through a simple oxidation process, ZnO nanowires, with typical diameters in the range of20–40 nm, will grow laterally from selectively exposed zinc edges on otherwise encapsulatedzinc lines. X-ray diffraction measurements show that the as-grown nanowires belong to thecrystalline hexagonal-structured ZnO. This simple and cost-effective fabricationprocess, coupled with its process compatibility with existing silicon technology andits scalable nature, is a viable processing technique to selectively grow lateralZnO nanowires on a planar substrate, with potential applications in nanowiredevices.

Aggregation-driven growth of well-oriented ZnO nanorod arrays

Here we report an aggregation-driven growth of highly oriented and densely packed ZnOnanorod arrays through a simple natural oxidation process of pure metal zinc informamide/water solution at low temperature. Very intense orange emission was observedin the resulting nanoparticle-built ZnO nanorods with numerous interfacial defects amongtheir primary nanoparticles.

Synthesis and Microstructures of α-Fe2O3 Bicrystalline Nanowires

ABSTRACTNovel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of pure iron. The microstructure of the Fe2O3 nanowires have been systematically investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM). The investigated materials are found to be stoichiometric rhombohedral α-Fe2O3 with typical diameters of 20–80 nm and lengths up to 20 μm. In addition to known single crystal Fe2O3 nanowires, a great amount of novel bicrystalline nanowires were found with ellipsoidal heads. Investigations indicate that most of the bicrystalline nanowires are twins and their orientation relationship is obtained to be (−1, 1, 10)M//(−1, 1, 10)T, [110]M//[-1-10]T. High resolution TEM with numerical reconstruction of the electron exit wave was used to investigated the atomic structure of the micro-twins. Their growth mechanism is briefly discussed on the basis of solid phase growth process.

Two-dimensional micrometer-sized single-crystalline ZnO thin nanosheets

Two-dimensional micrometer-sized single-crystalline ZnO thin nanosheets were achieved on a large scale, in which Zn thin nanosheets (precursor) were first grown via a thermal decomposition and reduction of the starting ZnS powder, and then converted to the ZnO nanosheets via a simple oxidation process. The ZnO nanosheets, growing along [100] or [010] direction and enclosed by ± (001) facets, have lateral dimensions up to several hundreds of microns, and thicknesses of 30–70 nm. Both room-temperature cathodoluminescence and photoluminescence measurements reveal that the present ZnO nanosheets have visible emission bands ranging from the green to red.

Fabrication of stable nanopatterns on metals

Nanopatterns on metal surfaces can be easily created by ion sputtering. However, due to the fast diffusion processes characterizing these materials, the nanostructures are often unstable at room temperature and above. This effect prevents the use of such patterned substrates in nanotechnology applications. In this letter, we present a simple oxidation process able to stabilize these features durably. The method has been tested on Cu, but its generality suggests that it can be applied to many other metals.

Characteristics of planar tunneling junctions on BSCCO crystal oxygen ion beam irradiation effect

Tunneling-spectrum characteristics were investigated for several planar type junctions fabricated on a BSCCO (2212) crystal surface. First, the simplest type, M/BSCCO [MAl, In, Pb, Ag or Au] junction was examined. It turns out that serious interface reactions causing a poor superconducting characteristic at the crystal surface occur immediately after the junction fabrication in the MAl, In and Pb case. In order to avoid the interface problem, a simple oxidation process using a homemade ion-beam gun was adopted just after the barrier (I) deposition in Ag/I/BSCCO [IAl 2O 3, In 2O 3 or MgO] junction.fabrication. This simple procedure fairly improved the interface character and provided us with distinct superconducting gap structures on the tunneling spectra up to near the bulk T c.

The solubility of nickel and cobalt in iron silicate slags

The solubility of nickel and cobalt in silica saturated iron silicate slags in equilibrium with nickel-gold and cobalt-gold alloys has been investigated under controlled oxygen pressures in the temperature range of 1250 to 1350°C. It was found that the metal solubility increased with 1) decreasing temperature, 2) increasing oxygen pressure, and 3) increasing metal content of the alloy. The solubility of cobalt in the slag was found to be much higher than that of nickel. The solubility of the metal in the slag from its alloy can be explained by a simple oxidation process.

魚油の油焼に關する研究第3報

In the preceding papers (This Journal, 15, (1949), 267, 270) the author assumed that the first necessary condition for discolorating fish oil is oxidation of oil. Mere oxidation of oil occurs no discoloration, but when certain volatile basic nitrogen compounds react to this oxidized oil, the color of the oil will become dark-red. In this paper the author has confirmed his assumption by the following experiment. Fresh shark liver oil was oxidized by blowing the air into it under the dispersed light and in the room temperature. Three of 20cc. oxidized oil were taken out each time and some chemical properties and the color of the control oil was measured on one of these three samples (A). The remaing two were treated with 5cc. of Aq. Dest. (B) or 5cc. of strong (28%) Ammonia (C) respectively just 5 minuts in the boiling water bath and the properties of these treated oil was compared with A. (see Table 1 and 2), In the tables it is clearly pointed out that the color of the fish oil will not become darkly red by simple oxidation process, but when a certain volatile basic nitrogen compounds react to this oxidized oil the color becomes deep, and the degree of the color, depth become much larger, keeping pace with the proceeding, of oxidation. The author has found a fact that the odor of the above mentioned darkly red oil is like that of fishmeal.