[en] Two-dimensional (2D) materials such as graphene and layered transition metal disulfides (TMD) have a high specific surface and are capable of intercalation with alkali metal ions. The theoretical specific electrochemical capacity of TMD materials is much higher than that of graphite. For low-dimensional 2D structures consisting of one or more monolayers, interaction with alkali metals leads to an even greater effective capacity. In this case, the real surface structure, the presence of vacancy, topological defects, the doping by heteroatoms with electron-donor or electron-acceptor properties into the two-dimensional structure begins to play a significant role Particularly interesting are hybrid materials consisting of layers MoS₂ and graphene. The poor electrical conductivity and high agglomerate risk of pure TMD electrodes can be overcome by interspersing nanocarbon phases within the composite material. The synergetic interactions of TMD and graphene nanohybrid materials for superior electrochemical performance in lithium and sodium ion batteries have been demonstrated in scientific publications in recent years. Using the modern methods of soft X-ray spectroscopy and X-ray photoelectron spectroscopy, NMR spectroscopy and a theoretical quantum chemistry approach, we investigated the process of alkali ions intercalation into composite and hybrid nanomaterials. Based on the results obtained, we determined how the size and morphology of MoS 2 layers and flakes, their imperfection and doping with other metals, as well as the chemical bond with graphene layers will affect the interaction with lithium and sodium atoms and ions and the stability of the electrode material in the processes of electrochemical intercalation/deintercalation. The reported study was funded by RFBR and DFG, project number 21-53-12021.

[en] Full text: Al and Cu coatings on glass, copper and steel substrates were obtained by the method of a rotating wire brush. Such a treatment makes both cutting out metal particles from bulk metal specimen and transferring them to the substrate in conditions of severe dynamical shear deformation. At the micro level, the scheme of deformation is similar to that for the friction test. The procedure is performed in air and involves intensive oxidation of transferred metal particles. The results of secondary ion mass spectrometry (SIMS) show the presence of oxygen compounds of metals practically throughout the coating. The AFM and X-ray diffraction studies of coatings showed that transferred metals have a nonhomogeneous, thermally stable nano structure with a grain size from 30 to 200 nm. The microhardness of the coatings was by a factor of 8-10 higher than that for the source metals. The coatings show high adhesion and good wear resistance. Such properties are determined by nano structure of coatings, stabilized by the presence of oxide interlayers

[en] Indentation experiments on monocrystalline {111} Cd_0.96Zn_0.04Te samples showed that acoustic wave treatment (AWT) before indentation resulted in crystal hardening. The mechanism causing this effect is still not well understood. However, dislocation motion could be hindered owing to the Cottrell matrix effect due to point defects liberated by AWT. Hardening was found to override softening due to AWT-induced dislocation motion. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

[en] Polycrystalline Cd_1-xZn_xTe films were grown on glass substrates over the full range of compositions (0 < x < 1) by metal-organic chemical vapour deposition at 480 deg. C. The films (∼5 μm thick) showed uniform texture oriented along the (1 1 1) direction, perpendicular to the substrate, independent of the film composition. The dependence of the lattice parameter of cubic Cd_1-xZn_xTe on the composition followed Vegard's law. The thick Cd_1-xZn_xTe films were shown to be of a single phase and structurally stable. The average grain size in the thick films was in the range 3-5 μm. The dominant imperfections in the films were twins (mostly Σ = 3) and dislocations. The x-ray diffraction (XRD) FWHM parameter reached a maximum at x = 0.5. Transmission electron microscopy (TEM) in situ heating in the range 200-400 deg. C caused plastic deformation in the grains without causing ordering effects. Optical absorption and low-temperature photoluminescence measurements confirmed the XRD and TEM results

[en] Holes with an average size of 2–5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C–1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks. (paper)