Vladimir L. Solozhenko

Université Paris 13 Nord, Île-de-France, France

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Publications (138)303.33 Total impact

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    Oleksandr O. Kurakevych, Vladimir L. Solozhenko
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    ABSTRACT: p-V-T equation of state of superhard boron suboxide B6O has been measured up to 6 GPa and 2700 K using multianvil technique and synchrotron X-ray diffraction. To fit the experimental data, the theoretical p-V-T equation of state has been derived in approximation of the constant value of the Anderson-Gr\"uneisen parameter {\delta}T. The model includes bulk modulus B0 =181 GPa and its first pressure derivative B0' = 6 at 300 K; two parameters describing thermal expansion at 0.1 MPa, i.e. a = 1.4x10-5 K-1 and b = 5x10-9 K-2, as well as {\delta}T = 6. The good agreement between fitted and experimental isobars has been achieved to the absolute volume changes up to 5% as compared to volume at standard conditions, V0. The fitted thermal expansion at 0.1 MPa is well consistent with the experimental data, as well as with ambient-pressure heat capacity cp, bulk modulus B0 and {\delta}T describing its evolution with volume and temperature. The fitted value of Gr\"uneisen parameter {\gamma} = 0.85 is in agreement with previous empiric estimations for B6O and experimental values for other boron-rich solids.
    07/2014;
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    ABSTRACT: The 300 K equation of state of cubic (zinc-blende) boron phosphide BP has been studied by in situ single-crystal X-ray diffraction with synchrotron radiation up to 55 GPa. The measurements have been performed under quasi-hydrostatic conditions using a Ne pressure medium in a diamond anvil cell. A fit of the experimental p-V data to the Vinet equation of state yields the bulk modulus B0 of 179(1) GPa with its pressure derivative of 3.3(1). These values are in a good agreement with previous elastic measurements, as well as with semiempirical estimations.
    07/2014;
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    ABSTRACT: Two new methods to produce nanopowders of B12P2 boron subphosphide by self-propagating high-temperature synthesis have been proposed. Bulk polycrystalline B12P2 with microhardness of HV = 35(3) GPa and stability in air up to 1300 K has been prepared by sintering these powders at 5.2 GPa and 2500 K.
    02/2014;
  • Journal of Applied Physics 01/2014; 116(3):033501-033501-5. · 2.21 Impact Factor
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    ABSTRACT: Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt ZnO was measured in the 10-300 K temperature range using synchrotron X-ray powder diffraction. No phase transition was observed down to 10 K. The lattice parameter of rock-salt ZnO was found to increase from 4.266 {\AA} in the 10-80 K range up to 4.2752(3) {\AA} at 298 K, while the volume thermal expansion coefficient increases from slight negative values below 40 K up to 4.77\times10^-5 K^-1 at 298 K.
    Solid State Communications 01/2014; 177:65-67. · 1.53 Impact Factor
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    ABSTRACT: Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt ZnO, was measured in the 10–300 K temperature range using synchrotron X-ray powder diffraction. No phase transition was observed down to 10 K. The lattice parameter of rock-salt ZnO was found to increase from 4.266 Å in the 10–80 K range up to 4.2752(3) Å at 298 K, while the volume thermal expansion coefficient increases from slight negative values below 40 K up to 4.77×10-5 K-1 at 298 K.
    Solid State Communications 01/2014; 177:65–67. · 1.53 Impact Factor
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    ABSTRACT: Very recently Leitner et al. [Thermochimica Acta 572 (2013) 1-5] have tried to extract the thermodynamic data of rock-salt ZnO from ab initio and experimental data available in the literature. In this Comment we show that neglecting (i) the strongly pronounced kinetic features of the pressure-induced phase transition in ZnO at room temperature and (ii) results of calorimetric measurements available in the literature [Russ. Chem. Bull. 59 (2010) 325-328] makes the proposed set of thermodynamic functions completely incorrect.
    11/2013;
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    ABSTRACT: Phase equilibria in the B–BN–B2O3 ternary system at pressures up to 5 GPa have been studied by in situ probing with synchrotron X-ray powder diffraction, microscopic and X-ray diffraction characterization of recovered samples, and thermodynamic analysis. The phase diagram of the system has been constructed by combining the previously reported data for binary subsystems and a conventional phenomenological model describing ternary interactions. The interaction parameter of the model of the ternary liquid phase has been determined by adjustment of experimental melting points to the calculated monovariant eutectic curve. The phase diagram is characterized by two ternary eutectics, one ternary transition-type equilibrium, and the maximum in the monovariant eutectic curve.
    The Journal of Physical Chemistry C. 08/2013; 117(36):18642–18647.
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    Vladimir L Solozhenko, Oleksandr O Kurakevych
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    ABSTRACT: Solid-state phase transformations and melting of high-purity crystalline boron have been in situ and ex situ studied at pressures to 20 GPa in the 1500-2500 K temperature range where diffusion processes become fast and lead to formation of thermodynamically stable phases. The equilibrium phase diagram of boron has been constructed based on thermodynamic analysis of experimental and literature data. The high-temperature part of the diagram contains p-T domains of thermodynamic stability of rhombohedral β-B106, orthorhombic γ-B28, pseudo-cubic (tetragonal) t'-B52, and liquid boron (L). The positions of two triple points have been experimentally estimated, i.e. β-t'-L at ~ 8.0 GPa and ~ 2490 K; and β-γ-t' at ~ 9.6 GPa and ~ 2230 K. Finally, the proposed phase diagram explains all thermodynamic aspects of boron allotropy and significantly improves our understanding of the fifth element.
    Scientific Reports 08/2013; 3:2351. · 5.08 Impact Factor
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    Oleksandr O. Kurakevych, Vladimir L. Solozhenko
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    ABSTRACT: During past years, a number of reports have been published on synthesis of tetragonal allotrope of boron, t-B52 phase. However, no unambiguous characterization of the crystal structure has been performed to the present time, while remarkable variation of the a/c lattice-parameter ratio raises strong doubts about its uniqueness. Here the Rietveld refinement of the crystal structure of the high pressure - high temperature boron phase synthesized by a direct solid-state transformation of rhombohedral beta-B106 at 20 GPa and 2500 K has been reported for the first time. Although this boron allotrope belongs to the t-B52 type, its structure can be considered as pseudo-cubic with the a/c ratio of sqr(2).
    Journal of Superhard Materials 02/2013; 35(1). · 0.72 Impact Factor
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    ABSTRACT: Transparent, colorless and contamination-free ZnO single crystals have been grown by rapid crystallization from the melt at [similar]4 GPa and [similar]1700 K. Recovered crystals exhibit needle-like (along the [0001] direction) morphology and have sizes up to 2 mm in length and 0.2 mm dia. Wurtzite structure (P63mc) has been confirmed by single-crystal X-ray diffraction, and lattice parameters (a = 3.2474(5) A, c = 5.2017(7) A) are in good agreement with literature data. Photoluminescence measurements revealed an intensive violet line at 398 nm, whose intensity depends non-linearly on the laser excitation power due to collective effects in photoexcited charge carriers or/and an effect of the stimulated emission in the ZnO crystals under study.
    CrystEngComm 01/2013; 15(32):6318-6322. · 3.88 Impact Factor
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    ABSTRACT: A synthesis route to rock salt zinc oxide (rs-ZnO), high-pressure phase metastable at ambient conditions, has been developed. High-purity bulk nanocrystalline rs-ZnO has been synthesized from wurtzite (w) ZnO nanopowders at 7.7 GPa and 770−820 K and, for the first time, recovered at normal conditions. Structure, phase composition, and thermal phase stability of recovered rs-ZnO have been studied by synchrotron X-ray powder diffraction and X-ray absorption spectroscopy (XANES and EXAFS) at ambient pressure. Phase purity of rs-ZnO was achieved by usage of w-ZnO nanoparticles with a narrow size distribution as a pristine material synthesized by various chemical methods. At ambient pressure, rs-ZnO could be stable up to 360 K. The optical properties of rs-ZnO have been studied by conventional cathodoluminescence in high vacuum at room and liquidnitrogen temperatures. The nanocrystalline rs-ZnO at 300 and 77 K has shown bright blue luminescence at 2.42 and 2.56 eV, respectively.
    Chemistry of Materials. 01/2013; 25(9):1775-1782.
  • V. Mukhanov, P. Sokolov, Y. Godec, V. Solozhenko
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    ABSTRACT: A new method of producing boron phosphide (BP) submicron powders by a self-propagating high-temperature reaction between boron phosphate and magnesium in the presence of an inert diluent (sodium chloride) has been proposed. Bulk polycrystalline BP with microhardness of H V = 28(2) GPa has been prepared by sintering the above powders at 7.7 GPa and 2600 K.
    Journal of Superhard Materials 01/2013; 35(6). · 0.72 Impact Factor
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    ABSTRACT: The melting of silicon carbide has been studied at pressures 5-8 GPa and temperatures up to 3300 K. It has been found that SiC melts congruently, and its melting curve has negative slope of -44 +/- 4 K/GPa.
    Journal of Superhard Materials 10/2012; 34(5). · 0.72 Impact Factor
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    ABSTRACT: Compressibility of high-purity nanostructured cBN has been studied under quasi-hydrostatic conditions at 300 K up to 35 GPa using diamond anvil cell and angle-dispersive synchrotron X-ray powder diffraction. A data fit to the Vinet equation of state yields the values of the bulk modulus B0 of 375(4) GPa with its first pressure derivative B0' of 2.3(3). The nanometer grain size (\sim20 nm) results in decrease of the bulk modulus by ~9%.
    Journal of Superhard Materials 08/2012; 34(5). · 0.72 Impact Factor
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    Vladimir A. Mukhanov, Petr S. Sokolov, Vladimir L. Solozhenko
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    ABSTRACT: The pressure dependence of melting temperatures for boron carbide and B4C-carbon eutectic has been studied up to 8 GPa, and it was found that in both cases the melting curves exhibit negative slope (-13\pm6 K/GPa), that is indicative of higher density of the melt as compared to the solid phase.
    Journal of Superhard Materials 06/2012; 34(3). · 0.72 Impact Factor
  • Vladimir L Solozhenko, Oleksandr O Kurakevych, Yann Le Godec
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    ABSTRACT: The synthesis of high-purity bulk nanostructured cubic boron nitride (cBN) at 20 GPa and 1770 K by direct phase transformation of graphite-like BN with an "ideal random layer" structure is reported. The two-times increase of hardness of nano-cBN (H(V) = 85 GPa) with respect to conventional polycrystalline cBN (H(V) ∼ 45 GPa) is evidently a result of nanosize effects.
    Advanced Materials 02/2012; 24(12):1540-4. · 14.83 Impact Factor
  • Oleksandr O. Kurakevych, Vladimir L. Solozhenko
    ChemInform 09/2011; 42(39).
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    ABSTRACT: Zarechnaya et al. claimed an isostructural transformation in gamma-B28 at about 40 GPa; below which the phase is more compressible (B0=227 GPa) and above which less compressible (B0=281 GPa) than in previous experiments or theory. Here we wish to point out some interesting questions related to these claims. Summarizing briefly our points, the suggestion of an isostructural transformation is inconsistent with ab initio calculations and experiment, we see no physical mechanism that could be responsible for such a transformation, and the evidence for it is self-contradictory.
    09/2011;
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    ABSTRACT: {\gamma}-B28 is a recently established high-pressure phase of boron. Its structure consists of icosahedral B12 clusters and B2 dumbbells in a NaCl-type arrangement (B2){\delta}+(B12){\delta}- and displays a significant charge transfer {\delta}~0.5- 0.6. The discovery of this phase proved essential for the understanding and construction of the phase diagram of boron. {\gamma}-B28 was first experimentally obtained as a pure boron allotrope in early 2004 and its structure was discovered in 2006. This paper reviews recent results and in particular deals with the contentious issues related to the equation of state, hardness, putative isostructural phase transformation at ~40 GPa, and debates on the nature of chemical bonding in this phase. Our analysis confirms that (a) calculations based on density functional theory give an accurate description of its equation of state, (b) the reported isostructural phase transformation in {\gamma}-B28 is an artifact rather than a fact, (c) the best estimate of hardness of this phase is 50 GPa, (d) chemical bonding in this phase has a significant degree of ionicity. Apart from presenting an overview of previous results within a consistent view grounded in experiment, thermodynamics and quantum mechanics, we present new results on Bader charges in {\gamma}-B28 using different levels of quantum-mechanical theory (GGA, exact exchange, and HSE06 hybrid functional), and show that the earlier conclusion about significant degree of partial ionicity in this phase is very robust.
    Journal of Superhard Materials 09/2011; · 0.72 Impact Factor

Publication Stats

1k Citations
303.33 Total Impact Points

Institutions

  • 2004–2014
    • Université Paris 13 Nord
      • Galilee Institute
      Île-de-France, France
  • 2003–2011
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 2010
    • Lomonosov Moscow State University
      Moskva, Moscow, Russia
    • Pierre and Marie Curie University - Paris 6
      • Institut de Minéralogie et de Physique des Milieux Condensés (IMPMC)
      Lutetia Parisorum, Île-de-France, France
    • Moscow State Textile University
      Moskva, Moscow, Russia
  • 2008
    • University of Lille Nord de France
      Lille, Nord-Pas-de-Calais, France
    • Universität Heidelberg
      • Institute of Earth Sciences
      Heidelberg, Baden-Wuerttemberg, Germany
  • 1992–2005
    • National Academy of Sciences of Ukraine
      Kievo, Kyiv City, Ukraine
  • 1994–1996
    • University of Bonn
      • Meteorological Institute
      Bonn, North Rhine-Westphalia, Germany