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Recently we developed a reactor chamber for the secure handling of radioactive materials. Using the arc discharge method for fullerene synthesis we could test the carbon encapsulation capability of uranium. The samples obtained, characterized by bulk and direct observation methods, show that uranium encapsulates as a dicarbide with two types of carbon covers: graphene sheets parallel to the external...
Kinetic equations were established and solved for the growing process of carbon clusters. The size distribution of the carbon clusters in the observed mass spectrum was simulated with different growing models. The best fitted one was the arbitrary combination model, indicating that the clustering process was a random association between any pair of the species. In the mass spectrum the depletion...
Carbon nanotubes were prepared by thermal decomposition of acetylene over silica-supported cobalt catalysts. Subsequent chemical treatments with concentrated hydrofluoric acid and dilute nitric acid, respectively, eliminated the silica substrate and the remaining catalyst. The complete removal of cobalt was very difficult due to encapsulation of part of it in the shells, but a graphitization at...
Raman spectroscopy, X-ray and electron diffractions have been applied to study samples of fullerene C 60 after they have undergone pressure and temperature treatments up to 8 GPa and 1073 K. It is confirmed that mixtures of rhombohedral and tetragonal structures are formed in the 2-4 GPa and 673-1073 K pressure-temperature domain. Traces of a hexagonal phase are also observed in the...
Samples of fullerene C 60 submitted previously to temperatures and pressures up to 973 K and 9.5 GPa have been heated in a differential scanning calorimeter in the interval 220-725 K. In nearly all of them, the first heating showed an irreversible endothermic peak extending between 450 and 550 K which was interpreted as a depolymerization reaction. Subsequent heating of the resulting...
Microporous and activated carbons have numerous applications ranging from gas absorbers to liquid decolorizers and are often called carbon molecular sieves. Their properties depend critically on the size of their pores and pore openings. Their structures are very complex and have defied a description which can explain the structural changes which occur during the thermal or chemical treatments necessary...
Reversible electrochemical intercalation of unsolvated lithium into graphite previously treated either in LiClO 4 -ethylene carbonate (EC) or in LiClO 4 -dimethyl carbonate (DMC) solutions was carried out in a LiClO 4 -propylene carbonate (PC) electrolyte. Under these conditions, graphite exfoliation did not occur, allowing the graphite anode to cycle reversibly. The modifications...
We are pursuing statistical-mechanical investigations of thermodynamic properties of the high-temperature modification of the C 60 fullerite taking into account the intramolecular degrees of freedom and the strong anharmonicity of lattice vibrations. In our theoretical calculations we employed the correlative method of an unsymmetrized self-consistent field for strongly anharmonic crystals...
Fine and long multiwalled carbon nanotubes attached with less carbon nanoparticles were prepared by d.c. arc discharge plasma of graphite electrodes in hydrogen gas. These high-grade carbon nanotubes grew on the central part of the cathode as a carbon deposit like black soot. They were mainly observed by a scanning electron microscope and subsequently by a high resolution transmission electron microscope...
PAN-based carbon fibers were stabilized under various tensions in the presence of air at 230°C and sequentially activated at 950°C following carbonization. The prepared carbon fibers were tested for their SO 2 adsorption capacity using a thermogravimeter. The magnitude of tension during stabilization and gas environment were varied to study their effects on SO 2 adsorption capacity...
The electrode deposit obtained at a.c. and d.c. arc discharge on the anode or cathode is mechanically stiff and contains a large diversity of carbon structures of a fullerene nature with different forms and sizes. Gaps of various sizes separate the structures. The large surface area of the carbon structures, their locations with respect to each other and the large porosity of some of the structures,...
We report on photoluminescence (PL) spectra from 10 to 300 K of C 60 thin films deposited on Si, GaSe, GaAs and Au substrates. X-ray diffraction patterns evidence a polycrystalline structure of the films. The effect of the different substrates on the C 60 PL spectra and the influence of the deposition parameters, such as the deposition rate and substrate temperature on...
Organic aerogels were synthesized via the sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution and followed by supercritical drying with carbon dioxide. As a result of characterization by nitrogen adsorption, the resorcinol-formaldehyde (RF) aerogels were mesoporous materials with high surface areas and had few micropores. The surface area of the RF aerogel...
Carbon nanoparticles of fullerites and single layer nanotubes were detected in Fe-Ni-C, Ni-Fe-C and Fe-Ni-Co-C alloys, manufactured from powders of corresponding metals and graphite. Their identification was fulfilled by methods of X-ray emission spectroscopy in conjunction with scanning electron microscopy, and by high resolution transmission electron microscopy.
The molecular field treatment developed for analysis of phase equilibria of meson-nonmesogen liquid crystal mixtures was applied to a quantitative description of the phase transition behavior of mesophase pitches, which were prepared by mixing a benzene-soluble fraction with a benzene-insoluble fraction of coal-tar pitch. The result showed that such a simplified theoretical treatment can be used...
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