We report an exceptionally stable honeycomb carbon allotrope obtained by deposition of vacuum-sublimated graphite. The allotrope structures are derived from our low temperature electron diffraction and electron microscopy data. These structures can be both periodic and random and are built exclusively from sp^{2}-bonded carbon atoms, and may be considered as three-dimensional graphene. They demonstrate high levels of physical absorption of various gases unattainable in other carbon forms such as fullerites or nanotubes. These honeycomb structures can be used not only for storage of various gases and liquids but also as a matrix for new composites.
Sc-Si multilayers are suggested as high-reflectivity coatings for a VUV interval of 35-50 nm. Fabricated mirrors show normal-incidence reflectivity of 30-54%, which is high enough for effective manipulation of the beams of compact-discharge, laser-driven x-ray lasers. The values obtained are not, however, limits for Sc-Si coatings. Theoretical estimations as well as electron microscopy studies of Sc-Si interfaces indicate a large potential for a further increase in their reflectivity.
Wear is an important phenomenon that affects the efficiency and life of all moving machines. In this regard, extensive efforts have been devoted to achieve the lowest possible wear in sliding systems. With the advent of novel materials in recent years, technology is moving toward realization of zero wear. Here, we report on the development of new functional coatings comprising periodically stacked nanolayers of amorphous carbon and cobalt that are extremely wear resistant at the micro and macro scale. Because of their unique structure, these coatings simultaneously provide high elasticity and ultrahigh shear strength. As a result, almost zero wear was observed even after one million sliding cycles without any lubrication. The wear rate was reduced by 8-10-fold compared with the best previously reported data on extremely low wear materials.
The formation of interlayer transition zones (ITZs) in sputtered Mo/Si multilayer structures was studied by means of cross-section electron microscopy and grazing incidence reflectivity measurements. For the evaluation and calculation of interface effects the multiperiodic design of Mo/Si structure was used. It was found that the thickness asymmetry of ITZs (Mo-on-Si and Si-on-Mo) in Mo/Si multilayer structures depends on the degree of perfection of the crystalline structure of the molybdenum layer. A transition from asymmetrical to symmetrical ITZs with a disordering of the molybdenum crystalline structure was shown. A model for the formation mechanism of asymmetrical ITZs at the different interfaces in Mo/Si multilayer structures is suggested. According to this model, ITZ formation at the Mo-on-Si interface is controlled by the surface diffusion of Si atoms on the growing molybdenum surface. In contrast, ITZ formation at the Si-on-Mo interface is determined by the bulk diffusion of Si atoms in textured molybdenum grain
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