Центральная Научная Библиотека УрО РАН

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   T 44


    The effects of sulfur and other impurities on carbon-graphite transition [] / V. A. Tyumentsev, E. A. Belenkov, G. P. Shveikin, S. A. Podkopaev // Carbon. - 1998. - V. 36, N 7-8. - С. 845-853 . - ISSN 0008-6223

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КОКС -- ГРАФИТИЗАЦИЯ -- ДИФРАКЦИЯ РЕНТГЕНОВСКАЯ -- РЕНТГЕНОВСКАЯ ДИФРАКЦИЯ -- ПЕРЕХОДЫ ФАЗОВЫЕ -- ФАЗОВЫЕ ПЕРЕХОДЫ -- ЖЕЛЕЗО -- ХРОМ -- СЕРА -- S -- Fe -- Cr -- ПЕРЕХОД УГЛЕРОД-ГРАФИТ -- МИКРОСКОПИЯ ЭЛЕКТРОННАЯ -- ЭЛЕКТРОННАЯ МИКРОСКОПИЯ
Аннотация: The transition to graphite of carbons containing sulfur and the effects of added iron and chromium on this process have been studied using X-ray diffraction analysis and electron microscopy. It was found that after heat treatment in the temperature interval 1300-1600°C carbons containing at least 1.5 mass% of sulfur, or 0.3 mass% of sulfur and 1.5 mass% of added Cr2O3 become heterogeneous; they consist of an ultradisperse matrix and of large (> 100 nm) and sufficiently perfect (Deltad/d002 ~ 0.002) regions of coherent scattering with interlayer spacing d002 that corresponds to the graphite-crystal structure. When disperse iron is added, the amount of the graphite phase in this temperature interval decreases by a factor of 2

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   S 53

    Shein, I. R.
    Electronic and structural properties of cementite-type M3X (M=Fe, Co, Ni; X=C or B) by first principles calculations [Текст] / I. R. Shein, N. I. Medvedeva, A. L. Ivanovskii // Physica B: Condensed Matter (Amsterdam, Netherlands). - 2006. - Vol. 371, № 1. - С. 126-132. - Bibliogr. : p. 132 (44 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБИДЫ ПЕРЕХОДНЫХ МЕТАЛЛОВ -- БОРИДЫ ПЕРЕХОДНЫХ МЕТАЛЛОВ -- МАГНИТНЫЕ СВОЙСТВА
Аннотация: Density functional theory within the generalized gradient approximation (GGA) is used to investigate the electronic structure and formation energies of cementite-like carbides and borides of Groups VII–VIII transition metals (TMs) (M3X; where M ¼ Fe, Co, Ni; X ¼ C or B). All phases are metallic-like; Fe3C, Co3C, Fe3B and Co3B exhibit ferromagnetic states whereas Ni3C and Ni3B are paramagnetic. The formation energies of M3X calculated with respect to bulk TMs, graphite and a-boron (B12) are negative for borides, however, they are positive for carbides, i.e. these M3C phases are metastable or unstable at ambient conditions. The stability differences of these compounds are discussed in terms of their electronic structure and chemical bonding

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   S 53

    Shein, I. R.
    First-principles study of structural, elastic and electronic properties of thorium dicarbide (ThC2) polymorphs / I. R. Shein, A. L. Ivanovskii // Journal of Nuclear Materials. - 2009. - Vol. 393, № 1. - С.192-196 : il. - Bibliogr. : p. 196 (23 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ДИКАРБИД ТОРИЯ -- ПОЛИМОРФИЗМ -- СТЕХИОМЕТРИЯ
Аннотация: The comparative study of the structural, elastic, cohesive and electronic properties of three polymorphs (alfa-monoclinic, beta-tetragonal and gamma-cubic) of thorium dicarbide ThC2 is performed within the density-functional theory. The optimized atomic coordinates, lattice parameters, theoretical density , bulk moduli, compressibility , as well as electronic densities of states, electronic heat capacity and molar Pauli paramagnetic susceptibility for all ThC2 polymorphs are obtained and analyzed in comparison with available experimental data. The peculiarities of inter-atomic bonding for thorium dicarbide are discussed. Besides, we have evaluated the formation energies (Ef) of ThC2 polymorphs for different possible preparation routes (namely for the reactions with the participation of simple substances (metallic Th and graphite) or thorium monocarbide ThC and graphite). The results show that the synthesis of the ThC2 polymorphs from simple substances is more favorable – in comparison with the reactions with participation of Th monocarbide

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   S 91

    Suetin, D. V.
    Structural, elastic and electronic properties and formation energiesfor hexagonal (W0.5Al0.5)C in comparison with binary carbidesWC and Al4C3 from first-principles calculations / D. V. Suetin, I. R. Shein, A. L. Ivanovskii // Physica B. - 2008. - Vol. 403. - P. 2654-2661 : il. - Bibliogr. : p. 2660-2661 (41 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- КАРБИДЫ -- W-Al-C -- СВОЙСТВА УПРУГИЕ -- СВОЙСТВА СТРУКТУРНЫЕ -- СВОЙСТВА ЭЛЕКТРОННЫЕ
Аннотация: First principle calculations have been performed with the purpose to understand the peculiarities of the structural, elastic parameters and electronic properties and interatomic bonding for novel hexagonal carbide (W0.5Al0.5)C in comparison with binary phases WC and Al4C3. The geometries of all phases were optimized and their structural, elastic parameters and theoretical density were established. Besides, we have evaluated the formation energies (Eform) of W0.5Al0.5C for different possible preparation routes (namely for the reactions with the participation of simple substances (metallic W, Al and graphite, binary W or Al carbides and metallic Al and W, or binary W and Al carbides). The results show that the synthesis of the ternary carbide from simple substances is more favorable in comparison with the reactions with participation of W and Al carbides. Moreover, band structures, total and partial densities of states were obtained and analyzed systematically for (W0.5Al0.5)C, WC and Al4C3 phases in comparison with available theoretical and experimental data. The bonding picture in W0.5Al0.5C was described as a mixture of metallic, ionic and covalent contributions with the high anisotropy for the covalent W–C and Al–C bonds, where p–p like Al–C bonds become weaker than p–d like W–C bonds

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   I-98

    Ivanovskaya, V. V.
    Atomic Structure, Electronic Properties, and Thermal Stability of Diamond-like Nanowires and Nanotubes / V. V. Ivanovskaya, A. L. Ivanovskii // Inorganic Materials. - 2007. - Vol. 43, № 4. - P. 349-357 : il. - Bibliogr. : p. 356-357 (41 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
АТОМНАЯ СТРУКТУРА -- СВОЙСТВА ЭЛЕКТРОННЫЕ -- СВОЙСТВА ТЕРМИЧЕСКИЕ -- НАНОВОЛОКНА АЛМАЗОПОДОБНЫЕ -- НАНОТРУБКИ
Аннотация: Density functional tight-binding calculations are used to investigate the structure, electronic properties, energy stability, and thermal behavior (0–1500 K) of extended monolithic (nanowires) and hollow (nanotubes) diamond-like carbon nanostructures. The results indicate that diamond-like nanowires and nanotubes may be both metallic and semiconducting, depending on their morphology and size. A new type of hybrid (sp3+sp2) nanostructure is identified, which has the form of a monolithic diamond-like (sp3) wire inside a graphite-like (sp2) shell. Diamond-like nanowires are shown to be more stable than nanotubes of comparable size

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   I-70


    Investigation of TiC–C Coatings by X-Ray Photoelectron Spectroscopy / M. V. Kuznetsov, S. V. Borisov, O. R. Shepatkovskii, Yu. G. Veksler, V. L. Kozhevnikov // Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques. - 2009. - Vol. 3, № 3. - P331-337 : il. - Bibliogr. : p. 337 (14 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБИД ТИТАНА -- РЕНТГЕНОВСКАЯ ФОТОЭЛЕКТРОННАЯ СПЕКТРОСКОПИЯ -- ПОКРЫТИЯ
Аннотация: Titanium carbide-based coatings deposited by arc-technology in C2H2/Ar atmosphere were studied by X-ray photoelectron spectroscopy. It was found that, in addition to the cubic phase of TiCxOy oxycarbide, the films contain carbon in the amorphous, presumably graphite-like state. In carbon C1s spectra, bands at 282.0, 284.4, and 286.0 eV correspond to the TiCx state, amorphous carbon, and C–C bonds, respectively. The maximum at 283.0 eV was interpreted as the C state in titanium carbide nanoforms, i.e., Ti14C13 clusters or Ti8C14 carbohedra. The phase ratio was varied by coating deposition conditions, i.e., TiC/a-C deposition by Ti cathode sputtering in C2H2/Ar, and composite Ti/C target sputtering in Ar and C2H2/Ar. When using the Ti cathode and C2H2/Ar gas mixture, the ratio of carbide and amorphous a-C phases was estimated as 1 : 1; the surface layer ~15 nm thick was enriched with amorphous carbon. It was assumed that TiC/ a-C composite coatings with an additional a -C film on the surface would have an increased stability in reaction media and good biocompatibility

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   B 22


    Band Structure and Properties of Polymorphic Modifications of Lower Tungsten Carbide W2C / D. V. Suetin, I. R. Shein, A. S. Kurlov, A. I. Gusev, A. L. Ivanovskii // Physics of the Solid State. - 2008. - Vol. 50, № 8. - P1420-1426 : il. - Bibliogr. : p. 1426 (20 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБИД ВОЛЬФРАМА -- ПОЛИМОРФНЫЕ МОДИФИКАЦИИ
Аннотация: The structural and electronic properties are investigated and the relative stabilities of all the known polymorphic modifications (α,β,γ,ε) of the lower tungsten carbide W2C are numerically estimated using the ab initio full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA) of the local spin density. The equilibrium parameters of the crystal lattices, the band structures, and the total and partial densities of states are determined for the first time within a unified approach. The energies of formation of the α,β,γ, and ε polymorphic modifications of the lower tungsten carbide [in the reactions W2C<-> 2W + C (graphite)] are calculated and used to discuss their relative stabilities

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   I-98

    Ivanovskaya, V. V.
    Nonempirical Calculations of the Electronic of New Boron Nitride Graphyne-like Nanotubes / V. V. Ivanovskaya, A. N. Enyashin, A. L. Ivanovskii // Russian Journal of Physical Chemistry A. - 2006. - Vol. 80, № 3. - P372-379 : il. - Bibliogr. : p. 379 (25 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
НЕЭМПИРИЧЕСКИЕ РАСЧЕТЫ -- НИТРИД БОРА -- ГРАФЕНОПОДОБНЫЕ НАНОТРУБКИ
Аннотация: The nonempirical density-functional tight-binding approach to band structure calculations was used to study the structural and electronic properties of new boron nitride graphyne-like nanotubes (α-BN-NT) constructed on the basis of the atomic motif of α-graphyne. All α-BN tubes were semiconductors with gap widths of 3.8–4.2 eV. The electron energy characteristics of zigzag and armchair α-BN-NTs are discussed in comparison with the known boron nitride graphite-like nanotubes. In addition, the special features of interatomic interactions in α-BN are analyzed using the nonempirical discrete variational method of density functional theory

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   I-98

    Ivanovskaya, V. V.
    Quantum-chemical modeling of the atomic and electronic structure of thin diamond-like nanocrystallites / V. V. Ivanovskaya, A. L. Ivanovskii // Theoretical and Experimental Chemistry. - 2006. - Vol. 42, № 4. - P207-210 : il. - Bibliogr. : p. 210 (11 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
АЛМАЗОПОДОБНЫЕ НАНОКРИСТАЛЛИТЫ -- КВАНТОВО-ХИМИЧЕСКОЕ МОДЕЛИРОВАНИЕ
Аннотация: The structural and electronic characteristics of thin diamond-like nanocrystallites (with cross-sectional areas 5 < S < 280 Å2) were investigated by the electron density functional tight binding (DFTB) method. A new type of extended “hybrid” (sp3 + sp2 ) nanostructures, in the form of monolithic diamond-like sp3 crystallites encapsulated in a graphite-like sp2 shell, was discovered

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