Home About us Contact
|
Home About us Contact | ||
|
|
||
Graphitic Layers (graphitic + layer)
Selected AbstractsVertical Epitaxial Co5Ge7 Nanowire and Nanobelt Arrays on a Thin Graphitic Layer for Flexible Field Emission DisplaysADVANCED MATERIALS, Issue 48 2009Hana Yoon Vertically aligned single-crystalline Co5Ge7 nanowire (NW) and nanobelt arrays are grown on a very thin graphite layer as well as a curved graphite layer with a good epitaxial lattice match. Co5Ge7 NW arrays, thus grown, show very efficient field emission properties comparable to those of carbon nanotubes and may be used for flexible field emission displays in the future. [source] Functionalization of carbon nanofibers (CNFs) through atom transfer radical polymerization for the preparation of poly(tert -butyl acrylate)/CNF materials: Spectroscopic, thermal, morphological, and physical characterizationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2008Marcos Ghislandi Abstract Vapor-grown carbon nanofibers (CNFs) were oxidized and functionalized for atom transfer radical polymerization (ATRP) of tert -butyl acrylate (t -BA) from the surface of the CNFs. The materials were characterized by solubility tests, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy. The FTIR and electron microscopy results suggest that ATRP process was successfully used to graft poly(tert -butyl acrylate) (poly(t -BA)) chains from the surface of the fibers. Raman results strongly indicate the partial degradation of the graphitic layer of CNFs because of the chemical treatments. TGA results suggest that the presence of poly(t -BA) leads to a decrease of the initial degradation temperature of the fibers. XRD and electron microscopy results indicate that the microstructure of fibers was not destroyed because of the oxidation and functionalization processes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3326,3335, 2008 [source] The Thermal Decomposition of Three Magnetic Acetates at Their Autogenic Pressure Yields Different Products.EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2007Abstract We report on the one-stage, reproducible, solvent-free, competent and straightforward approach for the synthesis of fullerene-like Ni@C, Co@C, and Fe3O4@C core-shell nanostructures that can be scaled up. The single precursor reactions of low cost acetates of Fe, Co and Ni are separately conducted at a relatively low temperature (700 °C) in a closed Swagelok reactor, as compared to other methods for the formation of graphitic layers. It is worth mentioning that although identical reaction parameters are employed, using the three acetate precursors, the graphitic carbon is coated on nanosized metallic Ni and Co cores, while Fe tends to form Fe3O4, maintaining the same core-shell morphology. The systematic morphological, compositional, structural characterization and the room temperature magnetic susceptibility measurements of the as-made particles are carried out on a vibrating sample magnetometer. The plausible mechanism is based on the comparison between the dissociation products of three acetate precursors, their obtained experimental data, and calculations on the enthalpy and free energy changes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Raman spectroscopic evaluation of polyacrylonitrile-based carbon nanofibers prepared by electrospinningJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2004Chan Kim Abstract Poly(acrylonitrile) (PAN) solutions in N,N -dimethylformamide were electrospun into webs consisting of 350 nm ultra-fine fibers. The webs were oxidatively stabilized and followed by heat treatment in the range of 700,1000°C. Characterization of the microstructure of PAN-based carbon nanofibers was performed by x-ray diffraction, field-emission scanning electron microscopy, electrical conductivity and Raman spectroscopy. The Lc(002) and La(10) values were calculated to be 1.85,2.15 and 2.23,3.36 nm, respectively. The Lc(002) and La(10) values increased by about 86% and 66%, respectively, when the heat treatment temperature (HTT) was increased from 700 to 1000°C. The electrical conductivity of carbonized PAN nanofiber webs increased with increasing carbonization temperature, being 6.8 × 10,3 and 1.96 S cm,1 at 700 and 1000°C, respectively. The D and G bands from Raman scattering were fitted into a Gaussian,Lorentzian hybridized function, and the crystallite sizes in the nanofibers were evaluated from the R -values determined from the ratios of the intensity of the G band to that of the D band. The domain size of the graphitic layers was in the range 1.6,3.2 nm with higher values at higher HTT. Copyright © 2004 John Wiley & Sons, Ltd. [source] Molecular Dynamics Simulations of Amorphous Si,C,N Ceramics: Composition Dependence of the Atomic StructureJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2003Nicoletta Resta We have performed classical molecular dynamics simulations of amorphous Si,C,N materials. The dependence of the local order and of the microstructure on the chemical composition was investigated. Our simulations show that for a stoichiometric nitrogen/silicon ratio equal to or higher than 4/3, the amorphous ceramic separates into different amorphous domains, namely C-rich, SiN-rich, and SiC-rich phases. Below this ratio, the material is composed of mixed structures, homogeneously spread within the material. For a very particular composition range, we found that carbon atoms crystallize into monoatomic graphitic layers surrounding the SiN-rich domains. [source] | |||||||||||||