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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...
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...
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...
Tin-doped C 60 thin films have been prepared by co-evaporation. Through controlling the temperature of the boat containing Sn, C 60 thin films with different Sn content have been obtained. The electrical and defect properties of these Sn-doped C 60 films have been studied using resistivity, Hall effect and electron spin resonance (ESR) measurements. Besides...
Structural changes of the C 60 and C 70 mixture during heat-treatment up to 2400°C were studied by observing the carbonized disk of the fullerene with Raman spectroscopy, X-ray diffraction, FE-SEM, TEM, and AFM/STM. The fullerene lost its five-membered ring and its fcc crystal structure by heat-treatment at 800°C, as revealed by the Raman spectra and X-ray diffraction, forming...
We report the luminescence of C 60 crystals and films due to the passage of an electrical current. The current-voltage behavior is highly non-linear with light-emission beyond a threshold voltage. The emission spectrum is featureless and resembles black-body radiation with an effective temperature on the order of 1700 K. We report experiments aimed at distinguishing between electro-...
Data from recent experimental studies of C 60 under high pressures are collected and analyzed, concentrating on the polymerized states where covalent intermolecular bonds have been formed through treatment of molecular C 60 at high pressures and temperatures at or above room temperature. We give an overview of the observed phase transformations and the structures of metastable...
Superhard and ultrahard phases of C 60 were synthesized by quenching at high pressures up to 13 GPa and high temperatures in the 300–2100 K range. The structures of the samples are discussed on the basis of X-ray and Raman spectra and electron microscopy data. The following physical properties of hard samples were studied: specific gravity; specific heat in the range 400–600 K; sound velocities;...
We present 13 C MAS NMR measurements on the (C 59 N) 2 dimer. The room temperature NMR spectrum obtained by spinning the sample at 10 kHz shows a weak line at 90 ppm and a group of lines around 140 ppm. The simulation of the obtained spectra allows us to attribute the line at 90 ppm to the sp 3 carbons forming the expected interball single bond and the other lines to...
Quantum field chemistry (QFC) conception within the framework of the kinematic electrondensity waves formalism has been applied to the description of corpuscular electron swarming. Interspersed between atoms, electron corpuscular solitary waves organize some g-dimensional lattices. An energy of the corpuscular electron swarm per single electron was obtained. Estimates of proper equilibrium parameters...
Fairly pure hexaadducts of molecular weights ranging from 2 × 10 4 to 2 × 10 6 could be prepared by reacting polystyryllithium with C 60 in toluene. These star-shaped polymers, with a fullerene core, associate a low polymolecularity of the arms (I < 1.1) and a fairly good control of the functionality (6). Their behavior in toluene has been established using static and dynamic...
The irradiation-induced self-compression of carbon onions and their transformation to diamond crystals are studied in situ by electron energy loss spectroscopy at high specimen temperature in a high-voltage electron microscope. Plasmon peaks in the low-loss region and the carbon K edge with the near-edge fine structure exhibit characteristic changes during irradiation. The spectra show the increasing...
A number of different C 60 and C 70 fullerene monoderivatives were synthesized and doped with tetrakis(dimethylamino)ethylene (TDAE) and cobaltocene (Cp 2 Co) to create charge transfer complexes with the aim of finding novel magnetic materials based on fullerenes. In this work X-band electron spin resonance (ESR) measurements are presented together with characterization of...
Carbon is the most versatile element in the periodic table. Due to its ability to form both sp 3 , sp 2 , and sp hybrids and stable multiple p π &z.sbnd;p π bonds, carbon can build up 3-, 2-, 1-, and 0-dimensionally structured substances with a broad variety of physical and chemical properties. In the last decade diamond films, active carbons, carbon fibres, and...
Using the same experimental set-up as for the solar production of fullerenes, we can also produce carbon nanotubes by direct vaporization of a mixture of powdered carbon and catalyst (Co, Ni, Y). The structure of the nanotubes is strongly dependent on the experimental conditions (pressure and flow rate of Ar gas) and we can obtain either multi-walled nanotubes or ropes of single-walled nanotubes.
The effect of air exposure and visible light illumination on the microhardness, plasticity and dislocation mobility in the C 60 single crystals was investigated. Microhardness values for defined structural states of the fullerene (pristine, oxygen-intercalated, photo-oxidized) are reported. It has been shown that oxygen intercalation in the fullerene lattice during air-aging in the dark results...
It is relatively easy to predict the structural properties of a solid made of spherical molecules. However this is not the case for a solid composed of cubic molecules such as solid cubane. The cubic structure of the cubane molecule gives rise to many unusual solid state properties. Here we present a brief review of our X-ray and neutron scattering studies along with our model calculations of the...
We report on the structural analysis of the two different phototransformed C 60 materials. The analysis was carried out by comparison of calculated Raman spectra to experimental data and by mass spectroscopy of the different species. It is demonstrated that the mass spectra of C 60 depend strongly on the desorption energy and that most of the polymeric subunits of the transformed material...
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