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51.
N.E. Sorokina D.V. Savchenko S.G. Ionov A.S. Tikhomirov I.V. Nikol'skaya V.V. Avdeev 《Journal of Physics and Chemistry of Solids》2010,71(4):499-502
Here we report a physicochemical investigation of low-density carbon materials modified with pyrolytic carbon (PC). Exfoliated graphite (EG) obtained by nitrate expandable graphite thermal destruction was pressed into low-density graphite materials (LDGMs) with densities of 0.045-0.50 g/cm3 and saturated with PC by impact CVI technique. LDGM infiltration with PC leads to sample weight and density growth. The amount of deposited PC strictly depends on synthesis conditions. The maximum surface and volume deposition of PC occurred for samples with density of 0.05 g/cm3. XRD, Raman spectroscopy and scanning electron microscopy revealed that the deposited PC is of smooth laminar (SL) type. Composite thermal conductivity is about 2-3.5 Wt/m K. 相似文献
52.
M. V. Avdeev T. V. Tropin V. L. Aksenov L. Rosta M. T. Kholmurodov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(6):819-825
Fullerene solutions in carbon disulfide are studied by small-angle neutron scattering (SANS). In addition to earlier experiments on the given system, the range of measured transmitted impulses is extended and the influence of solution preparation methods on C60 cluster formation in these solutions is studied. It is shown that the formation of large C60 clusters (with a size of about 10 nm) is due to nonequilibrium methods of solution preparation. For nonequilibrium dissolution, there is a 10% excess of the observed fullerene size in the solution over the calculated value. It has been established by simulation of the C60/CS2 interface by molecular dymanics methods that inclusion of how solvent molecules are organized on the C60 surface leads to a decrease in the fullerene size in the solution, observed by using SANS. In this paper, the effect of excess R g is explained by the presence of small clusters in the solution (approximately 10% of dissolved C60 molecules). It is discovered that there is a time variation in the concentration of the saturated solution. The explanation of this effect using a model of formation and sedimentation of large clusters (with a size of 100 nm or more) is proposed. 相似文献
53.
N. Boshkov N. Tsvetkova D. Koleva G. Avdeev G. Raichevsky 《Applied Surface Science》2008,254(17):5618-5625
The anodic behavior, corrosion resistance and protective ability of Zn and alloyed Zn-Co (∼3 wt.%) nanocomposite coatings were investigated in a model corrosion medium of 5% NaCl solution. The metallic matrix of the layers incorporates core-shell nano-sized stabilized polymeric micelles (SPMs) obtained from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block co-polymers. The protective properties of the composite coatings were evaluated using potentiodynamic polarization technique, polarization resistance measurements and powder X-ray diffraction. The sizes and distribution of the stabilized polymeric micelles in the starting electrolytes used as well as in the metal matrices of the layers were investigated using scanning and transmission electron microscopy. The results obtained are compared to those of electrodeposited Zn and Zn-Co (∼3 wt.%) alloy coatings at identical conditions and demonstrate the enhanced protective characteristics of the Zn nanocomposites during the investigating period. The influence of the SPMs on the corrosion resistance of the nanocomposite layers is commented and discussed. 相似文献
54.
Avdeev N. A. Dyadina P. I. Labazova S. P. 《Journal of Experimental and Theoretical Physics》2020,131(4):537-547
Journal of Experimental and Theoretical Physics - We developed the parameterized post-Keplerian formalism for hybrid metric-Palatini f(R)-gravity. We obtained analytical expressions in the general... 相似文献
55.
Solutions of fullerence C60 in carbon disulfide CS2 have been investigated by small-angle neutron scattering. Combination of solubility, contrast, and incoherent scattering make it possible to measure and analyze the relatively small scattering cross section of this system. Along with single fullerene molecules, a small amount of large fullerene clusters (more than 100 Å in size) is found in these solutions. The formation of these clusters depends on the procedure of solution preparation. The size distribution functions of clusters are compared with the results of the phenomenological cluster model of fullerene solubility. 相似文献
56.
We estimate the possible levels of reducing backward reflection of radio waves from an aerodynamic object covered by an absorbing
plasma created on the object at tropospheric flight altitudes. This effect is analyzed in terms of a model one-dimensional
problem of radio wave propagation in inhomogeneous layers of absorbing plasma.
5th Central Testing Institute of the Department of Defense of the Russian Federation, Voronezh, Russia. Translated from Izvestiya
Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 9, pp. 893–899, September, 1999. 相似文献
57.
Irina YU. Gorbunova Michail L. Kerber Svetlana I. Vladimirova Reem R. Musleh Nickolay N. Avdeev 《Macromolecular Symposia》1998,127(1):187-192
Miscibility of polypropylene with some oligoesters was evaluated by optical wedge interference microscopy. Mechanical, thermal, rheological and relaxation properties were studied. Compatibility between the polymers and modifying agents was shown to have a marked effect on stress-strain properties as well as on the structure and melting characteristics of the modified polymers. 相似文献
58.
The ternary copper antimony oxide Cu3‐xSb1+xO5.5+3x/2 (x=0.23) has been synthesized under 0.8–1.3 MPa pO2 at 1022–1082 °C. Rietveld refinements of X‐ray and neutron powder diffraction patterns concluded that the oxide adopts a bixbyite type structure, crystallising in the cubic space group Ia‐3 with the unit cell parameter a=9.61164(4) Å at room temperature from powder neutron diffraction data. The cationic 8b and 24d sites were found to be occupationally disordered where both Cu and Sb could be found on both sites. This is supported by X‐ray absorption spectroscopy experiments showing more than one possible Cu environment. There was a significant net deficiency of oxygen in the compound which was first inferred from observations of a thermochromic‐like phenomena and also seen from in situ high temperature neutron diffraction experiments. Magnetic susceptibility and magnetization measurements show paramagnetic behaviour with spin‐glass like transition below 6 K. 相似文献
59.
O. N. Shornikova E. V. Kogan N. E. Sorokina V. V. Avdeev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(6):1022-1025
Transformations of the specific surface area and porous structure of carbon materials based on graphite were studied by low-temperature
adsorption of nitrogen. Exfoliated graphite and graphite foil were found to have a developed (compared with the initial graphite)
surface (up to 90 m2/g) and a porous structure formed by slit-like mesopores with a characteristic radius of ∼20 ?. The determining influence
of the method of synthesis on the adsorption properties of materials was demonstrated for the first time.
Original Russian Text ? O.N. Shornikova, E.V. Kogan, N.E. Sorokina, V.V. Avdeev, 2009, published in Zhurnal Fizicheskoi Khimii,
2009, Vol. 83, No. 6, pp. 1161–1164. 相似文献
60.
M. V. Avdeev N. M. Blagoveshchenskii V. M. Garamus A. G. Novikov A. V. Puchkov 《Crystallography Reports》2011,56(7):1090-1095
The characteristics of the tripoli porous structure have been investigated by small-angle neutron scattering (SANS). Tripoli is a finely porous sedimentary rock formed by small spherical opal particles. Its main component is aqueous silica SiO2 · nH2O (80–90%). Tripoli is widely used in practice as a working medium for sorption filters and in some other commercial and construction technologies. The shape of the experimental SANS curves indicates the presence of small and large pores in tripoli. The small-pore size was estimated to be ~100 Å. The size of large pores turned out to be beyond the range of neutron wave vector transfers Q that are available for the instrument used; however, their size was indirectly estimated to be ~(2000–2500) Å. The pores of both groups behave as surfacetype fractal scatterers with the fractal dimension D ~ 2.2‐2.6. The densities of pores of these two groups differ by approximately three orders of magnitude (~1016 and ~1013 cm?3 for small and large pores, respectively); the fraction of large pores amounts to 70–80% of the total pore volume. The found pore characteristics (their densities, sizes, and relative volumes) are in satisfactory agreement (when a comparison is possible) with the absorption data. 相似文献