Synthesis and characterization of tungsten oxide nanorods

2004 ◽  
Vol 19 (12) ◽  
pp. 3665-3670 ◽  
Author(s):  
D.Z. Guo ◽  
K. Yu-Zhang ◽  
A. Gloter ◽  
G.M. Zhang ◽  
Z.Q. Xue
Keyword(s):  
Electron Microscopy ◽  
Tungsten Oxide ◽  
Electric Heating ◽  
Tungsten Oxides ◽  
X Ray ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Oxide Nanorods ◽  
Electron Energy Loss

Single crystalline nanorods (15–200 nm in diameter and hundreds nanometers in length) have been formed on the carbon-covered W wires by simple electric heating under a vacuum of 5 × 10−4 Pa. The chemical composition and crystalline structure of the nanorods were carefully investigated by various characterization techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. After ruling out any possible existence of carbon nanotubes (CNTs), tungsten carbide, W–Fe alloying, and formation of other types of tungsten oxides, monoclinic W18O49 phase has been well identified. The mechanism of nanorod formation of sub-tungsten oxide (∼WO2.7 compared to WO3) will be discussed in relation to the sample preparation conditions.

Electron Optical Characterization of Amorphous SIC:H CVD Films

1986 ◽  
Vol 69 ◽  
Author(s):  
R. M. Fisher ◽  
J. B. Posthill ◽  
M. Sarikaya ◽  
J. A. Reimer ◽  
M. Petrich
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Characterization ◽  
Carbon Films ◽  
Optical Methods ◽  
X Ray ◽  
Silicon Carbon ◽  
Transmission Electron ◽  
Electron Energy Loss

AbstractThe utility of various electron optical methods to characterize the microstructure and composition of thin films of amorphous silicon-carbon films formed by plasma-activated CVD of SiH4 and CH4 has been investigated. The techniques employed include conventional and high resolution transmission electron microscopy and diffraction, non-dispersive x-ray spectroscopy and electron energy loss spectroscopy.

Growth and Characterization of Tungsten Oxide for Applications in Nanoelectronics

2006 ◽  
Vol 48 ◽  
pp. 113-118
Author(s):  
Karthikk Sridharan ◽  
Kenneth P. Roberts ◽  
Saibal Mitra
Keyword(s):  
Tungsten Oxide ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Tungsten Filament ◽  
X Ray ◽  
Transmission Electron ◽  
Oxide Nanorods ◽  
Hot Filament

Tungsten oxide nanorods were prepared in a hot filament chemical vapor deposition (HFCVD) reactor. A mixture of gases containing hydrogen, oxygen or hydrogen and methane mixed with water vapor were passed into a quartz glass jar reactor and activated using a heated tungsten filament. The resulting deposits were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), and Raman Spectroscopy. The deposit consisted of tungsten oxide nanorods (5 – 10 nm diameter and 50 – 75 nm long) and tungsten nanospheres with diameters of ~50nm. The tungsten oxide is then reduced to metallic tungsten by annealing in a hydrogen environment.

Intergrowth of niobium tungsten oxides of the tetragonal tungsten bronze type

2020 ◽  
Vol 75 (11) ◽  
pp. 913-919
Author(s):  
Frank Krumeich
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tungsten Bronze ◽  
Structural Complexity ◽  
Dark Field ◽  
Tetragonal Tungsten Bronze ◽  
Tungsten Oxides ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractSince the 1970s, high-resolution transmission electron microscopy (HRTEM) is well established as the most appropriate method to explore the structural complexity of niobium tungsten oxides. Today, scanning transmission electron microscopy (STEM) represents an important alternative for performing the structural characterization of such oxides. STEM images recorded with a high-angle annular dark field (HAADF) detector provide not only information about the cation positions but also about the distribution of niobium and tungsten as the intensity is directly correlated to the local scattering potential. The applicability of this method is demonstrated here for the characterization of the real structure of Nb7W10O47.5. This sample contains well-ordered domains of Nb8W9O47 and Nb4W7O31 besides little ordered areas according to HRTEM results. Structural models for Nb4W7O31 and twinning occurring in this phase have been derived from the interpretation of HAADF-STEM images. A remarkable grain boundary between well-ordered domains of Nb4W7O31 and Nb8W9O47 has been found that contains one-dimensionally periodic features. Furthermore, short-range order observed in less ordered areas could be attributed to an intimate intergrowth of small sections of different tetragonal tungsten bronze (TTB) based structures.

scholarly journals Synthesis and characterization of Fe, Co, and Ni colloids in 2-mercaptoethanol

2020 ◽  
Vol 10 ◽  
pp. 184798042096688
Author(s):  
Galo Cárdenas-Triviño ◽  
Sergio Triviño-Matus
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Colloidal Dispersions ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Chemical Liquid Deposition ◽  
Liquid Deposition

Metal colloids in 2-mercaptoethanol using nanoparticles (NPs) of iron (Fe), cobalt (Co), and nickel (Ni) were prepared by chemical liquid deposition method. Transmission electron microscopy, electron diffraction, UV-VIS spectroscopy, and scanning electron microscopy with electron dispersive X-ray spectroscopy characterized the resulting colloidal dispersions. The NPs exhibited sizes with ranges from 9.8 nm for Fe, 3.7 nm for Co, and 7.2 nm for Ni. The electron diffraction shows the presence of the metals in its elemental state Fe (0), Co (0), and Ni (0) and also some compounds FeO (OH), CoCo2S4, and NiNi2S4.

Detonation Synthesis of Nano-Size Materials

1995 ◽  
Vol 418 ◽  
Author(s):  
J. Forbes ◽  
J. Davis ◽  
C. Wong
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nucleation And Growth ◽  
Detonation Synthesis ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Transmission Electron ◽  
Nano Size

AbstractThe detonation of explosives typically creates 100's of kbar pressures and 1000's K temperatures. These pressures and temperatures last for only a fraction of a microsecond as the products expand. Nucleation and growth of crystalline materials can occur under these conditions. Recovery of these materials is difficult but can occur in some circumstances. This paper describes the detonation synthesis facility, recovery of nano-size diamond, and plans to synthesize other nano-size materials by modifying the chemical composition of explosive compounds. The characterization of nano-size diamonds by transmission electron microscopy and electron diffraction, X-ray diffraction and Raman spectroscopy will also be reported.

Characterization of columns grown during KrF laser micromachining of Al2O3–TiC ceramics

2003 ◽  
Vol 18 (5) ◽  
pp. 1123-1130 ◽  
Author(s):  
V. Oliveira ◽  
R. Vilar
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Laser Pulses ◽  
Formation Mechanisms ◽  
X Ray ◽  
Reducing Conditions ◽  
Transmission Electron ◽  
Column Formation ◽  
Krf Laser

This paper aims to contribute to the understanding of column formation mechanisms in Al2O3–TiC ceramics micromachined using excimer lasers. Chemical and structural characterization of columns grown in Al2O3–TiC composite processed with 200 KrF laser pulses at 10 J/cm2 was carried out by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction analysis. Fully developed columns consist of a core of unprocessed material surrounded by an outer layer of Al2TiO5, formed in oxidizing conditions, and an inner layer, formed in reducing conditions, composed of TiC and Al3Ti or an AlTi solid solution. Possible mechanisms of column formation are discussed.

Hydrothermal Synthesis and Characterization of BiFeO3 Polyhedral Crystallites

2012 ◽  
Vol 174-177 ◽  
pp. 508-511
Author(s):  
Lin Lin Yang ◽  
Yong Gang Wang ◽  
Yu Jiang Wang ◽  
Xiao Feng Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

BiFeO3 polyhedrons had been successfully synthesized via a hydrothermal method. The as-prepared products were characterized by power X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The possible mechanisms for the formation of BiFeO3 polyhedrons were discussed. Though comparison experiments, it was found that the kind of precursor played a key role on the morphology control of BiFeO3 crystals.

Characterization of Al65.0Cu32.9Co2.1 Alloy Containing Nanofibres

2012 ◽  
Vol 186 ◽  
pp. 212-215
Author(s):  
Jacek Krawczyk ◽  
Włodzimierz Bogdanowicz ◽  
Grzegorz Dercz ◽  
Wojciech Gurdziel
Keyword(s):  
Electron Microscopy ◽  
Average Diameter ◽  
Chemical Compositions ◽  
X Ray ◽  
Transmission Electron ◽  
Orthogonal Set ◽  
T Phase ◽  
Terminal Area ◽  
Scanning Electron

Microstructure of terminal area of Al65Cu32.9Co2.1ingots (numbers indicate at.%), obtained via directional solidification was studied. Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray powder diffraction were applied. Point microanalysis by Scanning Electron Microscope was used for examination of chemical compositions of alloy phases. It was found that tetragonal θ phase of Al2Cu stoichiometric formula was the dominate phase (matrix). Additionally the alloy contained orthogonal set of nanofibres of Al7Cu2Co T phase with the average diameter of 50-500 nm and oval areas of hexagonal Al3(Cu,Co)2H-phase, surrounded by monoclinic AlCu η1phase rim. Inside some areas of H-phase cores of decagonal quasicrystalline D phase were observed.

Solution-Based Synthesis of Magnesium Oxide Nanorods

1999 ◽  
Vol 581 ◽  
Author(s):  
Q. Wei ◽  
C.M. Lieber
Keyword(s):  
Electron Microscopy ◽  
Magnesium Oxide ◽  
Magnesium Chloride ◽  
Low Cost ◽  
Industrial Applications ◽  
Transformation Process ◽  
Matrix Composites ◽  
X Ray ◽  
Transmission Electron ◽  
Oxide Nanorods

ABSTRACTA solution-based synthesis route was developed to produce large quantities of MgO nanorods. Hydrated basic magnesium chloride, which has needle-like crystal structure, was used as a precursor. A subsequent two-step transformation process with magnesium hydroxide as an intermediate product was used to preserve the morphology of the precursor to yield magnesium oxide nanorods. Scanning electron microscopy, powder X-ray diffraction and energy dispersive X-ray spectroscopy show that the products are very pure (>95%) crystalline MgO nanorods with diameters from 40 nm to 200 nm and lengths 10 microns or longer. High-resolution transmission electron microscopy and electron diffraction further reveal that these MgO nanorods are single crystals and that the rod axis is along the <110> crystal direction. A model for the structural transformation from hydrated basic magnesium chloride to magnesium oxide has been developed and compared to our experimental results. This solution-based process can be easily scaled-up, and is a low-cost source of pure magnesium oxide nanorods needed in many industrial applications, for example, as reinforcing agents in matrix composites and as flux-pinning centers in high-TC superconductors.

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