D. V. Shchur

Effect of ultrasound treatment of C60 solutions on the crystalline structure of precipitated fullerite

The structure of fullerite precipitated from solutions of C60 in toluene, chlorobenzene, and 1,2-dichlorobenzene by adding isopropanol was studied. It was demonstrated that, irrespective of the nature of the solvent, the parameter of the fcc lattice of precipitated fullerite decreases markedly when the process occurs in the presence of a ultrasound field. No effect of ultrasound sonication on the size of the precipitated crystallites was observed.

Hydrogen-sorption properties of magnesium and its intermetallics with Ca7Ge-Type structure

The statistical theory of the hydrogenation of magnesium and its alloys Mg6M′M″(with M′ = Mg, Ti, V, Nb, Zr; M″ = Mg, Al, Zn) has been developed. The energies of crystals have been calculated, and equations for their thermodynamic equilibrium state have been found. Equations for determining the P-T-c diagram have been obtained. Curves that determine the temperature dependences of the concentration of hydrogen desorbed from crystals were studied. The maximum hydrogen-desorption temperature and its dependence on interatomic-interaction energy parameters and the activity of hydrogen atoms were estimated. Isopleths of hydrogen solubility were calculated for different concentrations of hydrogen. The level of the curves for different coefficients of activity and slope for different hydrogen contents were found. Isotherms of hydrogen solubility in crystals were studied. The possibility of achieving the sorption hysteresis effect was clarified, and the length and width of the hysteresis loop at different temperatures were estimated. The aforementioned functional dependences were plotted. The calculated data were compared with experimental results available in the literature. The theoretical and experimental data agree qualitatively.

Fullerite intercalated with argon at room temperature: Synthesis and physicochemical properties

Fullerite with the bulk formula ArxC60, where 0.60 < x < 0.75, was synthesized by precipitation from a mixture of argon-saturated solutions. The fcc unit cell parameter in the sample was 1.422 nm; the orientational phase transition (OPT) temperature was 247 K. These values noticeably differ from the relevant parameters of undoped fullerite (1.416 nm and 260 K, respectively). Heating accompanied by argon evolution restores the fullerite C60 structure.

Isotope effect in the hydrogen distribution in the solid solution TiN0.40H0.19D0.19

AbstractThe structure of a solid solution with a combined isotope composition based on TiN0.40H0.19D0.19 (space group

Phase transitions in zirconium–palladium alloys

P\overline 3 m1

Short-Range Order and Correlation Effects in Solid Solutions

) has been studied by neutron diffraction. The isotope effect in the distribution of H and D isotopes has been found: the isotopes are located in tetrahedral interstices of the same type but with different z coordinates; there is splitting of 2d tetrahedral interstices into two groups, the protium (H) and deuterium (D). Therefore, in the ordered “layered” structure of the TiN0.40H0.19D0.19 solid solution, two different isotopes of the same element cannot be located at the same plane perpendicular to the threefold axis. The crystal-chemical analysis of the surroundings of H and D has been performed, and considerable differences have been revealed between the coordination polyhedra surrounding different hydrogen isotopes. It has been found that, in some metal-hydrogen systems, protium and deuterium should be treated as independent chemical components.

Adsorption and thermal desorption of hollow and endohedral fullerenes on a free crystal surface

A statistical theory is developed for the decomposition of an amorphous zirconium-palladium alloy in a hydrogen atmosphere with the formation of metal hydrides. The free energies of the phases are calculated, and equations for the equilibrium states of the phases are derived. The phase-transformation temperatures are determined, and their dependences on the system composition are obtained. The temperature dependences of the hydrogen solubilities in the phases are found, and the appearance of the inflection points or jumps at the phase-transformation points, which are experimentally observed as inflections in the dependences, is grounded. Hydrogen solubility isotherms are calculated, and the possibility of a hysteresis effect is revealed.

Statistical Thermodynamics of Phase Transformations in Lithium Alanates with Release of Hydrogen

A statistical theory of zirconium–palladium alloys has been developed with allowance for the formation of amorphous, icosahedral, and crystalline phases. The free energies are calculated. The phase diagram near the stoichiometric composition of the Zr2Pd alloy has been constructed. The structural phase transitions are studied. The possibility of formation of various spin orders on the sites of zirconium and palladium atoms is found. The temperature dependence of the heat capacity of the alloy is constructed, and the heat capacity jumps at the Curie points are estimated. The theoretical results are compared to experimental data.