N. I. Alekseev

Caprolons modified with fullerenes and fulleroid materials

Conditions for the preparation of modified Caprolons were determined and optimized. A number of laboratory and industrial samples was prepared. Their main mechanical, physicochemical, and electrical properties were determined.

The solubility of fullerenes in butyric and enanthic acids at 20–80 °C

The polythermal solubility of C60 and fullerene mixture (60% C60, 39% C70, and 1% C76–90) in butyric and enanthic acids was studied over the temperature range 20–80 °C. The corresponding solubility polytherms are given and characterized.

Epitaxial assembly of graphene on face (0001) of silicon carbide: Modeling by semiempirical methods

The epitaxial growth of graphene on silicon face (0001) of silicon carbide is simulated using the semiempirical methods of quantum chemistry. The experimental conditions for the epitaxial growth of graphene on SiC, at which the probability of seams and similar defects appearing is reduced to a minimum, are formulated. Possible ways of the emergence of reconstructions of the singular carbon and silicon SiC faces during the synthesis of graphenes are investigated as a test of the approach’s efficiency. It is noted that simulation reproduces the reconstruction periods experimentally determined for both faces, and yields the most likely atomic arrangements in cases where the experimental formula of the superstructure allows different versions of such arrangements.

Activation of the carbon component of shungite-III and the sorption capacity of the material for hydrogen

The carbon material MNS, produced from shungite-III by successive alkaline and acid treatment, was studied. Cavitational treatment of an aqueous dispersion of the MNS material in the field of a standing acoustic wave converts a part of the substance into a material with a developed surface and a sorption capacity for hydrogen of up to 1.5%.

Evaporation of carbon atoms from the open surface of silicon carbide and through graphene cells: Semiempirical quantum-chemical modeling

The evaporation of silicon atoms during the epitaxial growth of graphene on the singular carbon and silicon faces of silicon carbide SiC was modeled by the semiempirical AM1 and PM3 methods. The analysis was performed for evaporation of atoms both from the open surface of SiC and through the surface of the formed graphene monolayers. The total activation barrier of the evaporation of the silicon atoms, their passage from the graphene cell, and further evaporation from graphene was shown to be lower than the barrier to evaporation of the silicon atom on a free surface of SiC. Passage through graphene is thus not the limiting stage of the process, but contributes significantly to the effective evaporation time.

Initial stage of the epitaxial assembly of graphene from silicon carbide and its simulation by semiemprical quantum chemical methods: Carbon face

The epitaxial growth of graphene on a singular carbon face of silicon carbide is simulated by semiempirical quantum chemical methods. It is shown that the main regularities of the growth of graphene on such a face, i.e., the sequence of surface reconstructions with a short spatial period (2 × 2) → (3 × 3) → graphene, are exhibited naturally during the analysis of various paths of graphene assembly and seeking the most probable path.

Simulating the conditions for the formation of graphene and graphene nanowalls by semiempirical quantum chemical methods

A “substrate-surface graphene island” is simulated by semiempirical quantum chemical methods for different substrates. It is established that such systems with various island sizes correspond to graphene growth on corresponding substrates when CVD is used. Carbon atoms can be incorporated into the island from either the side of the substrate or the side of the CVD reactor exposed to it. It is shown for a wide range of island sizes that the best configuration with respect to the substrate is the structure of a carbon nanowall oriented perpendicular to the substrate. It is emphasized that a transition to this configuration is possible in reality only if CVD is plasma-stimulated when there is a strong near-electrode field near the surface, and the preliminary scission of the carbon carrier material occurs simultaneously in the CVD reactor volume.

Quantum-chemical models of the annealing of open shell carbon clusters during the synthesis of fullerenes

It is shown that a model for assembling fullerenes from polycyclic carbon clusters, supplemented by consideration of the Stone-Wales transformation on open shell hot clusters, predicts the formation of fullerenes with an almost even distribution of pentagonal cells on their surface. The possibility of this transformation on an open shell cluster itself establishes the maximally proper assembling rate and determines its limiting condition.

Nonlinear optical properties of solutions of heavy fullerenes in the near-ultraviolet region

Nonlinear optical properties (particularly optical limiting) are determined for solutions of heavy fullerenes C76 + C78 + C84 + C90 + …, in the near-ultraviolet region (λ ≈ 280 ± 7 nm). It is shown that no optical limiting is observed in solutions of light fullerenes (C60 and C70), but found in solutions of water-soluble fullerenol-d (a mixture of oxypolyalcohols of fullerene C60-C60(OH)n1On2, with their sodium salts) based on light fullerenes.

The mechanism of unification of carbon nanotubes with small numbers of walls into bundles. Calculation of the domains of existence of different types of nanotubes at different temperatures and catalytic particle sizes

A model of nucleation of carbon nanotubes (CNTs) from catalytic particles oversaturated with carbon has been constructed. The temperature dependences of the number and size of nanotubes on the parameters of the model were derived. The nanotubes begin to grow as individual nanotubes. Then the axis of the nanotube starts to vibrate relative to the normal to the particle surface. In a certain range of conditions, the nanotubes are united into bundles. The diagram of the domains of existence of individual nanotubes and bundles was plotted as the particle size versus temperature.