Publications (19)15.75 Total impact
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Article: Structural, electronic properties and stability of MXenes Ti2C and Ti3C2 functionalized by methoxy groups
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ABSTRACT: The properties of MXenes, a new group of quasi-two-dimensional d-metal carbide or nitride nanomaterials derived by chemical exfoliation from the MAX phases, can be very sensitive to the presence of surface functional groups. Herein, the MXenes Ti2C and Ti3C2 functionalized by methoxy groups are considered by means of the density functional theory tight-binding method. Their structural, electronic properties, and relative stability are discussed in comparison with related and experimentally fabricated hydroxy derivatives of MXenes.04/2013; -
Article: Thorite versus huttonite: stability, electronic properties and X-ray emission spectra from first-principle calculations
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ABSTRACT: The structural, electronic properties and stability of thorium orthosilicate ThSiO4 polymorphs: thorite and huttonite are investigated by means of the full-potential linearized augmented-plane-wave method with the generalized gradient approximation for the exchange-correlation potential (FLAPW-GGA). The forbidden gaps of thorite and huttonite are estimated at about 7.8 and 7.6eV, respectively. It is found that Th5f states in ThSiO4 partially overlap with occupied O2p bands. The data obtained showed that thorite is more stable than huttonite; in turn both ThSiO4 polymorphs are unstable with respect to their constituent binary oxides (thorianite ThO2 and α-quartz SiO2) in agreement with the experiments. The theoretical shapes of X-ray emission (XES) (Si,O)Kα,β spectra for thorite, huttonite as well as for SiO2 and ThO2 are calculated and discussed. We show that the XES spectroscopy near the (Si,O)K edge may be very useful technique not only for detailed investigation of the bulk-electronic structure of Th silicates but also for the phase analysis of complex mineral samples containing these species.Physics and Chemistry of Minerals 04/2012; 33(8):545-552. · 1.73 Impact Factor -
Article: Atom-decorated nanotubes
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ABSTRACT: Quantum chemical and molecular dynamics studies of nanotubes decorated with atoms of various elements are surveyed. The effect of adsorption of hydrogen, oxygen, alkali metal, alkaline earth metal, d-metal, halogen, and inert gas atoms on external walls of carbon nanotubes on the structure and electronic or other physicochemical properties of nanotubes is considered. The results of simulation of the properties of some atom-decorated non-carbon nanotubes (BN, BCx, BxCyNz) are briefly discussed. The bibliography includes 332 references.Russian Chemical Reviews 09/2011; 80(8):727. · 2.64 Impact Factor -
Article: Structural, electronic properties and Fermi surface of ThCr2Si2-type charge-balanced KFe2AsSe phase as a parent system for a new group of "mixed" pnictide-chalcogenide superconductors
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ABSTRACT: The ThCr2Si2-type arsenide-selenide phase KFe2AsSe is proposed as a parent system for a new "intermediate" group of Fe-based superconducting materials bridging the known families of Fe-pnictides (such as BaFe2As2) and Fe-chalcogenides (such as KxFe2-ySe2) superconductors. The characterization of the proposed charge-balanced phase by means of FLAPW-GGA approach covers the crystal structure, As/Se atomic ordering, stability, electronic bands, Fermi surface, and density of electronic states.07/2011; -
Article: Elastic and electronic properties of hexagonal rhenium sub‐nitrides Re3N and Re2N in comparison with hcp‐Re and wurtzite‐like rhenium mononitride ReN
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ABSTRACT: Very recently, two hexagonal rhenium sub-nitrides Re3N and Re2N, which belong to a rather rare group of known metal-rich (M/N > 1) nitrides of heavy 4d, 5d metals, have been successfully synthesized, and their potential technological applications as ultra-incompressible materials have been proposed. In this work, we present a detailed ab initio study of recently synthesized rhenium sub-nitrides in comparison with hcp-Re and wurtzite-like rhenium mono-nitride ReN, with the purpose to evaluate the trends of the elastic, electronic properties, and chemical bonding in the series of these hexagonal systems as a function of the Re/N stoichiometry: Re → Re3N → Re2N → ReN.physica status solidi (b) 05/2011; 248(6):1369 - 1374. · 1.32 Impact Factor -
Article: Elastic properties and inter‐atomic bonding in layered Fe–Cu arsenide oxide Sr2Fe2CuAs2O2
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ABSTRACT: Inspired by recent discovery of the layered five-component phase – the tetragonal arsenide oxide Sr2Fe2CuAs2O2 uniting two types of [Fe2As2] and [CuO2] blocks, which are the main building blocks inherent in two basic families of high-TC superconductors: so-called cuprates and iron-pnictides, we used the first principles calculations to predict the elastic properties and to find their interplay with inter-atomic bonding for this unique system. Our data reveal that the examined phase is a relatively soft material; the predicted bulk and shear modules are about 90 and 54 GPa, respectively. Besides, this system is mechanically stable, adopts considerable elastic anisotropy, and should demonstrate brittleness. These conclusions agree with the bonding picture for Sr2Fe2CuAs2O2, according to which the inter-atomic bonding in this system is highly anisotropic and includes ionic, covalent, and metallic contributions, where inside [Fe2As2] and [CuO2] blocks covalent-ionic Fe–As, Cu–O and metallic-like Fe–Fe bonds take place, whereas inter-blocks bonding is basically of the ionic type.physica status solidi (b) 04/2011; 248(9):2165 - 2169. · 1.32 Impact Factor -
Article: Graphene allotropes
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ABSTRACT: Using the density-functional-based tight-binding method (DF-TB) we performed a systematic comparative study of stability, structural, and electronic properties for 12 various types of graphene allotropes, which are likely candidates for engineering of novel graphene-like materials.physica status solidi (b) 01/2011; 248(8):1879 - 1883. · 1.32 Impact Factor -
Article: Elastic properties of superconducting MAX phases from first‐principles calculations
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ABSTRACT: Using first-principles density functional calculations, a systematic study of the elastic properties for all known superconducting MAX phases (Nb2SC, Nb2SnC, Nb2AsC, Nb2InC, Mo2GaC, and Ti2InC) was performed. As a result, the optimized lattice parameters, independent elastic constants, indicators of elastic anisotropy, and brittle/ductile behavior as well as the so-called machinability indexes were calculated. We also derived bulk and shear moduli, Young's moduli, and Poisson's ratios for ideal polycrystalline MAX aggregates. The results obtained are discussed in comparison with available theoretical and experimental data and elastic parameters for other layered superconductors.physica status solidi (b) 12/2010; 248(1):228 - 232. · 1.32 Impact Factor -
Article: Modeling of Magnetic Properties of NiCl$_2$ Nanostripes, Nanotubes and Fullerenes
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ABSTRACT: We show that the magnetic properties of antiferromagnetic layered NiCl$_{2}$ can be altered under nano-sizing depending on dimensionality and morphology type of the corresponding nano-forms. By means of Monte-Carlo simulations within classical Heisenberg model, the spin ordering, magnetic part of heat capacity C$_{v}$ and N\'eel temperatures T$_{N}$ for multi-walled NiCl$_{2}$ nanotubes and a fullerene were calculated and analyzed in comparison with the bulk NiCl$_{2}$ and multilayered two-dimensional NiCl$_{2}$ crystals and nanostripes. We have found that the nano-structuring of NiCl$_{2}$ at the size reducing and at the formation of the closed structures can influence propitiously on the preservation of antiferromagnetic properties. Comment: 13 pages, 3 figures, 1 Table06/2010; -
Article: Nanotubes of Polytitanic Acids H2TinO2n+1 (n = 2, 3, and 4): Structural and Electronic Properties
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ABSTRACT: Atomic models of nanotubes of a family of polytitanic acids H2TinO2n+1 (n = 2, 3, and 4) are proposed, and their properties are studied by means of the density functional theory based (DFTB) method as a function of their chemical composition and radii in comparison with the related dehydrogenated lepidocrocite TiO2 nanotubes. We find that these nanotubes have very similar structural properties, which are difficult to distinguish with the commonly applied XRD technique. The variable composition can be attributed to the nanotubes of titanic acid obtained experimentally due to thermodynamic dehydration ↔ hydration equilibrium.12/2009; -
Article: Electronic and elastic properties of perovskite‐like W3NiC, W3NiN and Co3WC from first‐principles calculations
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ABSTRACT: We have performed ab initio total energy calculations using the full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange–correlation potential to investigate structural, elastic, cohesive, electronic and magnetic properties of the tungsten-containing perovskite-like phases W3NiC, W3NiN and Co3WC. The optimized lattice parameters, independent elastic constants (Cij), bulk moduli (B) and shear moduli (G), as well as densities of electronic states and cohesive and formation energies are obtained and analyzed for the first time. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)physica status solidi (b) 05/2009; 246(7):1646 - 1651. · 1.32 Impact Factor -
Article: New high-temperature superconductors based on rare-earth and transition metal oxyarsenides and related phases: synthesis, properties and simulations
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ABSTRACT: The discovery in February 2008 of superconductivity with the transition temperature about 26 K in fluorine-doped oxyarsenide LaO1–xFxFeAs stimulated numerous studies of superconducting and other physical properties of this and related materials, resulting in a new family of high-temperature (Tc ~ 26–55 K) superconductors.The experimental and theoretical state of the art is reviewed concerning the synthesis, properties and simulation of the new family and related systems.Physics-Uspekhi 03/2009; 51(12):1229. · 2.15 Impact Factor -
Article: Structural, electronic, cohesive, and elastic properties of diamondlike allotropes of crystalline C_ {40}
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ABSTRACT: The atomic models of diamondlike allotropes of crystalline C40 (hyperdiamond, hyperlonsdaleite and so-called autointercalated hyperdiamond) are offered and using the density-functional based tight-binding method their structural, cohesive, elastic, and electronic properties are predicted as well as their theoretical x-ray diffraction spectra are derived. Among these allotropes the autointercalated hyperdiamond C40 has a unique combined type of both covalent and van der Waals bonding and shows the highest density and hardness.Phys. Rev. B. 03/2008; 77(11). -
Article: Structural, elastic and electronic Properties of isotropic cubic crystals of carbon and silicon nanotubes : Density functional based tight binding calculations.
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ABSTRACT: Atomic models of cubic crystals (CC) of carbon and graphene-like Si nanotubes are offered and their structural, cohesive, elastic and electronic properties are predicted by means of the DFTB method. Our main findings are that the isotropic crystals of carbon nanotubes adopt a very high elastic modulus B and low compressibility β, namely B = 650 GPa, β = 0.0015 1/GPa. In addition, these crystals preserve the initial conductivity type of their “building blocks”, i.e. isolated carbon and Si nanotubes. This feature may be important for design of materials with the selected conductivity type.Carbon : Science and Technology. 01/2008; -
Article: Nanotubes and related nanostructures of d-metal oxides: synthesis and computer design
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ABSTRACT: State-of-the-art studies on the synthesis, properties and the computer design of nanotube forms of transition metal oxides are analysed. Main methods for the preparation of oxide nanotubes and related quasi-one-dimensional nanostructures (nanobundles, nanoribbons, etc.) are discussed. Data on the morpho-logy and physicochemical properties of these materials and prospects for their technological applications are summarised. The results of the computer design of atomic structures and results of quantum-chemical calculations of electronic structures and chemical bond parameters of Ti, V and Mo oxide nanotubes and their fullerene-like molecules are considered.Russian Chemical Reviews 10/2007; 74(7):587. · 2.64 Impact Factor -
Article: Computational Studies of Electronic Properties of ZrS<SUB>2</SUB> Nanotubes
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ABSTRACT: The discovery of carbon nanotubes (NT) with unique properties has stimulated the search for new quasi-one-dimensional (1 D ) nanoscale inorganic materials (NTs, nanowires etc.). Numerous d -metal dichalcogenide MX<SUB>2</SUB> (M = Mo, W; X = S, Se) nanotubes were prepared and investigated in the last decade. Quite recently (2002) the first ZrS<SUB>2</SUB> nanotubes were produced. As distinct from the group V and VI metal disulfide NTs, the electronic properties and chemical bonding of 1 D nanomaterials based on group IV metal (Ti, Zr and Ta) disulfides have not been studied up till now. In the present paper, the electronic band structure and bond indices of ZrS<SUB>2</SUB> NTs were calculated for the first time and analysed in comparison with other MS<SUB>2</SUB> (M = Mo, W, Nb) nanotubes. The electronic band structure, densities of states, crystal orbital overlap populations and total band energies of ZrS<SUB>2</SUB> nanotubes and strips ( E <SUB>tot</SUB>) have been obtained using the tight-binding band structure method. The atomic models of zigzag- and armchair-like open-end ZrS<SUB>2</SUB> nanotubes have been constructed. The electronic structure and bond indices of ZrS<SUB>2</SUB> nanotubes have been calculated and analysed as a function of the tubes diameters (D) in the armchair- and zigzag-like forms. Our calculations for the zigzag ( n ,0)- and armchair ( n , n )-like ZrS<SUB>2</SUB> nanotubes ( n = 8 ÷ 29) showed that all NTs with D > 2 nm are uniformly semiconducting and their energy spectra are similar to the DOS of the bulk ZrS<SUB>2</SUB>. The band gap tends to vanish as the tube diameters decrease. Zr-S covalent bonds were found to be the strongest interactions in ZrS<SUB>2</SUB> tubes, whereas Zr-Zr bonds prove to be much weaker, and the covalent S-S interactions are absent (COOPs < 0). According to our results, the zigzag-like configurations of the single-walled ZrS<SUB>2</SUB> NTs are more stable. Possible atomic structures of ZrS<SUB>2</SUB> nanotube caps and ZrS<SUB>2</SUB> fullerene-like molecules were also proposed and discussed. Computer simulation of the band structure and bonding indices of non-chiral ZrS<SUB>2</SUB> nanotubes has been performed as the first step to understand the electronic properties of 1 D nanomaterials of group IV d -metal disulfides which may be of interest, in particular, as hydrogen-storage materials and insertion materials of lithium batteries.Internet Electronic Journal of Molecular Design. 01/2003; -
Article: Bending of MgO tubes: Mechanically induced hexagonal phase of magnesium oxide
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ABSTRACT: The present work constitutes a study of the response of magnesium oxide nanotubes on the bend deformation. Our molecular-dynamics simulations show that the structure of the MgO tubes being face centered cubic at ambient conditions is transformed under mechanically induced buckling stress to hexagonal near the tube bend. This transformation occurs through a break of the Mg-O bonds between two adjacent Mg2O2 tetragons and the formation of Mg3O3 hexagons. Ab initio density-functional band-structure calculations were performed to predict the structural and electronic properties of hexagonal MgO phase and to compare with those for the cubic B1 and B2 MgO phases.Phys. Rev. B. 75(19). -
Article: Magnetization of carbon-doped MgO nanotubes
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ABSTRACT: Using local spin-density-functional formalism, we study the occurrence of spin polarization in magnesium oxide nanotubes doped with carbon impurities. We find that carbon impurity acquires a magnetization caused by the 2p states partly filled and placed in forbidden gap of a MgO tube. According to our estimations, for carbon impurity replacing oxygen inside the MgO tube wall, the spin magnetization (at about 2μB per cell) is found. The results are used in discussion of the new approach to the engineering of magnetic nanotubes, namely, the magnetization of nonmagnetic tubes induced by nonmagnetic impurities.Phys. Rev. B. 75(24). -
Article: Structural, electronic properties and stability of tungsten mono- and semi-carbides: A first principles investigation
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ABSTRACT: First principles calculations have been performed with the purpose to understand the comparative peculiarities of the structural, electronic properties and stability for all phases formed in the tungsten–carbon system: hexagonal and cubic mono-carbides WC and four polymorphs (α, β, γ and ε) of semi-carbide W2C. All calculations were performed by means of the full-potential linearized augmented plane wave method (FLAPW). The generalized gradient approximation (GGA) in the Perdew–Burke–Ernzerhof (PBE) formalism was used for the exchange and correlation energy functional. The geometries of all WC and W2C phases were optimized and their structural parameters and theoretical density were established. Besides, we have evaluated the formation energies (Eform) of all the tungsten carbides. Based on our estimations we can arrange all investigated W–C phases depending on their stability in the following sequence: h-WC>ε-W2C>β-W2C>γ-W2C>α-W2C>c-WC. Here three carbides (h-WC, ε-W2C and β-W2C) are stable (Eform<0), γ-W2C belongs to metastable systems (Eform∼0), whereas α-W2C and c-WC appear to be unstable (Eform>0). Moreover, band structures, total and partial densities of states were obtained and analyzed systematically for all W–C phases in comparison with other available theoretical and experimental data.Journal of Physics and Chemistry of Solids.
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2012
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Russian Academy of Sciences
Moscow, Moscow, Russia
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