Search results for "TRANSMISSION ELECTRON"
showing 10 items of 426 documents
Synthesis of Fullerene- and Nanotube-Like SnS2 Nanoparticles and Sn/S/Carbon Nanocomposites
2009
SnS2 nested fullerene-type (IF) nanoparticles, nanotubes, and SnS2/C hybrid nanostructures were obtained by vapor transport starting from elemental tin and CS2. The reaction was carried out in a single-step process by heating elemental tin metal powder in a horizontal tube furnace at 800−1000 °C. TEM analysis allowed proposing a plausible mechanism for the formation of fullerene-like particles of SnS2 as well as tubes and scrolls from nanosheets of SnS2. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX…
A study on the stability of carbon nanoforms–polyimidazolium network hybrids in the conversion of co2 into cyclic carbonates
2021
Three different carbon nanoforms (CNFs), single-walled and multi-walled carbon nanotubes (SWCNTs, MWCNTs) and carbon nanohorns (CNHs), have been used as supports for the direct polymerization of variable amounts of a bis-vinylimidazolium salt. Transmission electron microscopy confirmed that all CNFs act as templates on the growth of the polymeric network, which perfectly covers the nanocarbons forming a cylindrical (SWCNTs, MWCNTs) or spherical (CNHs) coating. The stability of these hybrid materials was investigated in the conversion of CO2 into cyclic carbonate under high temperature and CO2 pressure. Compared with the homopolymerized monomer, nanotube-based materials display an improved c…
Carbon-doped titania as a precursor for titanate nanotubes
2018
Carbon-doped titania was fabricated via carbothermal treatment in nitrogen–acetylene gas flow and further used as a precursor for multiwalled titanate nanotube (TNT) synthesis via alkaline hydrothermal route. Investigation of the reaction products after hydrothermal treatment of carbon-doped titania using Transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller method shows the successful formation of TNTs. The presence of carbon was proved although the type of incorporation could not be certified. All samples show approximately the same carbon content before and after hydrothermal treatment. An increasing pretreatment temperature of titania precursor powders yields m…
Effect of Reaction Parameters on Composition and Morphology of Titanate Nanomaterials
2009
International audience; In the present article, we report the synthesis of titanate nanotubes and nanoribbons with controlled morphology, structure, and chemical composition depending on the main parameters of the synthesis. Hydrothermal processing time, grain size of the precursor, type of agitation, and acid treatment were investigated, and the principal controversies mentioned in the literature such as nanotube crystallographic structure, their chemical composition, and acid treatment impact are discussed. These controversies may be due to the heterogeneities present in all the samples and are rarely considered in the literature. These nanostructures were characterized by Raman spectrosc…
Carbon nanotube bags: catalytic formation, physical properties, two-dimensional alignment and geometric structuring of densely filled carbon tubes.
2001
The catalytic CVD synthesis, using propyne as carbon precursor and Fe(NO3)3 as catalyst precursor inside porous alumina, gives carbon nanotube (CNT) bags in a well-arranged two-dimensional order. The tubes have the morphology of bags or fibers, since they are completely filled with smaller helicoidal CNTs. This morphology has so far not been reported for CNTs. Owing to the dense filling of the outer mother CNTs with small helicoidal CNTs, the resulting CNT fibers appear to be stiff and show no sign of inflation, as sometimes observed with hollow CNTs. The fiber morphology was observed by raster electron microscopy (REM), transmission electron microscopy (TEM), and atomic force microscopy (A…
Chemical Mimicry: Hierarchical 1D TiO2@ZrO2 Core−Shell Structures Reminiscent of Sponge Spicules by the Synergistic Effect of Silicatein-α and Silint…
2011
In nature, mineralization of hard tissues occurs due to the synergistic effect of components present in the organic matrix of these tissues, with templating and catalytic effects. In Suberites domuncula, a well-studied example of the class of demosponges, silica formation is mediated and templated by an axial proteinaceous filament with silicatein-α, one of the main components. But so far, the effect of other organic constituents from the proteinaceous filament on the catalytic effect of silicatein-α has not been studied in detail. Here we describe the synthesis of core-shell TiO(2)@SiO(2) and TiO(2)@ZrO(2) nanofibers via grafting of silicatein-α onto a TiO(2) nanowire backbone followed by …
Transmission electron microscopy investigation of oxidation of (110)NiAl single crystal with wedge-shaped profile
2016
Abstract Low energy electron diffraction (LEED), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX), and electron energy loss spectroscopy (EELS) investigations of oxidation processes in (110)NiAl single crystal of wedge like shape, i.e., on the sample’s areas of different thickness, were carried out. It was found that in the result of several cycles of ion etching, annealing and oxidation the upper layer of (110)NiAl is enriched with Ni. With the increase of Ni concentration from 50 to 100 at. %, the stoichiometry of the near surface area changes and the new phases of Ni3Al and Ni with Al doping are formed one after another. Up to Ni content of 75 at. %…
Annealing reactions in lead implanted copper
2002
Abstract The terminal solubility of Pb in Cu is extremely low and does not exceed 0.09 at.% at 875 K. Ion implantation of lead ions at 100 keV into Cu single crystals produces metastable solutions. Annealing of the samples causes redistribution of the implanted atoms to equilibrium or near-equilibrium aggregate states which may be reflected in a change in the type of impurity lattice location in the host matrix. We have studied the effect of annealing on single crystalline Cu implanted at temperatures around 375 K with Pb to a concentration of a 1–2 at.%. Rutherford backscattering/channeling analysis and transmission electron microscopy of the as-implanted samples have shown that the implan…
Formation of cobalt silicide from filter metal vacuum arc deposited films
2006
The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 deg…
Investigation of precipitate in an austenitic ODS steel containing a carbon-rich process control agent
2018
This work has been carried out within the framework of the German Helmholtz Association and has received funding from the topic “Materials Research for the Future Energy Supply”. The work of M. Parish and Rainer Ziegler is gratefully acknowledged. Thanks are also due to the team of the chemical laboratory at the KIT for performing the chemical analysis. The help of the beamline staff at ELETTRA (project 20140052 ) synchrotron radiation facility is acknowledged. We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology.