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Entani, Shiro; Antipina, L. Y.*; Avramov, P.*; Otomo, Manabu*; Matsumoto, Yoshihiro*; Hirao, Norie; Shimoyama, Iwao; Naramoto, Hiroshi*; Baba, Yuji; Sorokin, P. B.*; et al.
Nano Research, 8(5), p.1535 - 1545, 2015/05
Times Cited Count：26 Percentile：71.65(Chemistry, Physical)
interface in the Fe-doped C filmSakai, Seiji; Matsumoto, Yoshihiro; Otomo, Manabu; Entani, Shiro; Avramov, P.; Sorokin, P. B.*; Naramoto, Hiroshi*
Synthetic Metals, 173, p.22 - 25, 2013/06
Times Cited Count：2 Percentile：10.3(Materials Science, Multidisciplinary)Avramov, P.; Fedorov, D. G.*; Sorokin, P. B.*; Sakai, Seiji; Entani, Shiro; Otomo, Manabu; Matsumoto, Yoshihiro; Naramoto, Hiroshi*
Journal of Physical Chemistry Letters (Internet), 3(15), p.2003 - 2008, 2012/08
Times Cited Count：36 Percentile：79.49(Chemistry, Physical)Antipina, L. Y.*; Avramov, P.; Sakai, Seiji; Naramoto, Hiroshi*; Otomo, Manabu; Entani, Shiro; Matsumoto, Yoshihiro; Sorokin, P. B.*
Physical Review B, 86(8), p.085435_1 - 085435_7, 2012/08
Times Cited Count：52 Percentile：86.87(Materials Science, Multidisciplinary)Chernozatonskii, L. A.*; Sorokin, P. B.*; Kuzubov, A. A.*; Sorokin, B. P.*; Kvashnin, A. G.*; Kvashnin, D. G.*; Avramov, P.; Yakobson, B. I.*
Journal of Physical Chemistry C, 115(1), p.132 - 136, 2011/01
Times Cited Count：80 Percentile：88.67(Chemistry, Physical)Avramov, P.; Fedorov, D. G.*; Sorokin, P. B.*; Chernozatonskii, L. A.*; Gordon, M. S.*
Journal of Physical Chemistry C, 111(51), p.18824 - 18830, 2007/12
Times Cited Count：12 Percentile：39.94(Chemistry, Physical)We have systematically constructed a set of stable silicon nanocluster families with large arbitrary fullerenetype hollows inside. In addition, conglomerate structures are designed by connecting the nanoclusters through pentagonal and hexagonal junctions. The atomic and electronic structure of the proposed objects is investigated using the semiempirical quantum-mechanical method. It is shown that within each family the band gap and the stability are inversely proportional to the particle effective size. The clusters inherit a wide variety of structural and symmetry properties from their parent silicon fullerenes. The conglomerates confine electrons like quasi-molecules with a peculiar electronic structure related to the junctions. Quantum dots and their conglomerates can host guest atoms in their hollows and therefore present a new promising type of nanomaterials with tunable electronic properties.
Avramov, P.; Chernozatonskii, L. A.*; Sorokin, P. B.*; Gordon, M. S.*
Nano Letters, 7(7), p.2063 - 2067, 2007/07
Times Cited Count：13 Percentile：51.77(Chemistry, Multidisciplinary)Using an empirical scheme, the atomic structure of a new exotic class of silicon nanoclusters was elaborated upon the central icosahedral core (Si-IC) and pentagonal petals (Si-PP) growing from Si-IC vertexes. It was shown that Si-IC/Si-PP interface formation is energetically preferable. Some experimental observations of silicon nanostructures can be explained by the presence of the proposed objects. The extended Huckel theory electronic structure calculations demonstrate an ability of the proposed objects to act as nanoscale tunnel junctions.
quantum nanodots and nanowiresAvramov, P.; Kuzubov, A. A.*; Fedorov, A. S.*; Sorokin, P. B.*; Tomilin, F. N.*; Maeda, Yoshihito
Physical Review B, 75(20), p.205427_1 - 205427_8, 2007/05
Times Cited Count：18 Percentile：60.66(Materials Science, Multidisciplinary)The atomic and electronic structures of a set of proposed pentagonal thin (1.6 nm in diameter) Si/SiO quantum nanodots (QDs) and nanowires (NWs) with narrow interface, as well as parent metastable Si structures (1.2 nm in diameter), were studied using cluster B3LYP/6-31G
and periodic boundary condition (PBC) plane-wave (PW) pseudopotential (PP) local-density approximation methods. The total density of states (TDOS) of the smallest quasispherical QD (Si
) corresponds well to the PBC PW PP LDA TDOS of the crystalline Si. The elongated SiQDs and SiNWs demonstrate the metallic nature of the electronic structure. The surface oxidized layer opens the band gap in the TDOS of the Si/SiO species. The top of the valence band and the bottom of conduction band of the particles are formed by the Si core derived states. The theoretical band gap width is determined by the length of the Si/SiO clusters and describes the size confinement effect in the experimental photoluminescence spectra of the silica embedded nanocrystalline Si with high accuracy.
Avramov, P.; Sorokin, P. B.*; Fedorov, A. S.*; Fedorov, D. G.*; Maeda, Yoshihito
Physical Review B, 74(24), p.245417_1 - 245417_8, 2006/12
Times Cited Count：18 Percentile：61.42(Materials Science, Multidisciplinary)The atomic and electronic structure of a set of pristine single wall SiC nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was studied by the LDA plane wave band structure calculations. Consecutive substitution of carbon atoms by Si leads to a gap opening in the energetic spectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of the band gap upon the Si concentration. The same substitution for the semiconductor (10,0) SWCNT results in a band gap minimum (0.27 eV) at 
25% of Si concentration. In the Si concentration region of 12-18%, both types of nanotubes have less than 0.5 eV direct band gaps at the 
- point. The calculation of the chiral (8,2) SWSi
C
NT system gives a similar (0.6 eV) direct band gap. The regular distribution of Si atoms in the atomic lattice is by 0.1 eV/atom energetically preferable in comparison with a random distribution. Time dependent DFT calculations showed that the silicon substitution sufficiently increases (roughly by one order of magnitude) the total probability of optical transitions in the near infrared region, which is caused by the opening of the direct band gap in metallic SWCNTs, the unification of the nature and energy of band gaps of all SWCNT species, the large values of 
Si3
Si3
radial integrals and participation of Si3
states in chemical bonding in both valence and conductance bands.
Ninokata, Hisashi*; Misawa, Takeharu*; Baglietto, E.*; Aoki, Takayuki*; Sorokin, A. P.*; Maekawa, Isamu*; Ohshima, Hiroyuki; Yamaguchi, Akira
JNC TY9400 2003-010, 170 Pages, 2003/03
JNC-TY9400-2003-010.pdf:5.42MB
A method of large scale direct numerical simulation of turbulent flows in a high burn-up fuel pin bundle is proposed to evaluate wall shear stress and temperature distributions on the pin surfaces as well as detailed coolant velocity and temperature distributions inside subchannels under various thermal hydraulic conditions. This simulation is aimed at providing a tool to confirm margins to thermal hydraulics design limits of the nuclear fuels and at the same time to be used in design-by-analysis approaches. The method will facilitate thermal hydraulic design of high performance LMFR core fuels characterized by high burn-up, ultra long life, high reliable and safe performances, easiness of operation and maintenance, minimization of radio active wastes, without much relying on such empirical approach as hot spot factor and sub-factors, and above all the high cost mock up experiments. A pseudo direct numerical simulation of turbulence (DNS) code is developed, first on the Cartesian coordinates and then on the curvilinear boundary fit coordinates that enables us to reproduce thermal hydraulics phenomena in such a complicated flow channel as subchannels in a nuclear fuel pin assembly. The coordinate transformation is evaluated and demonstrated to yield correct physical quantities by carrying out computations and comparisons with experimental data with respect to the distributions of various physical quantities and turbulence statistics for fluid flow and heat transfers in various kinds of simple flow channel geometry. Then the boundary fitted pseudo DNS for flows inside an infinite pin array configuration is carried out and compared with available detailed experimental data. In parallel similar calculations are carried out using a commercial code STAR-CD to cross-check the DNS performances. As a result, the pseudo DNS showed reasonable comparisons with experiments as well as the STAR-CD results. Importance of the secondary flow influences is emphasized on the momentum a
clusters, nanoparticles and nanowiresAvramov, P.; Kuzubov, A. A.*; Fedorov, A. A.*; Tomilin, F. N.*; Sorokin, P. B.*
no journal, ,
The small Si
O
clusters are the precursors of the Si/SiO objects and play a key role in their synthesis. The reaction paths for formation and isomerization of a set of silica SiO (m=2, 3, n=1-5) nanoclusters have been investigated using second order pertubation theory (MP2) with the 6-31G(d) basis set. Although transition states have been located for many isomerization reactions, only for Si
O and SiO
some transition states have been found for the formation of a cluster from the separated reactants. The electronic structure calculations of the Si and Si/SiO quantum dots and nanowires have been performed using the DFT B3LYP/6-31G and PBC LDA PP PW approximations. The polycrystalline nature of the Si nanowires and Si quantum dots leads to the metallic state of all species. The oxidized SiO surface leads to stabilization of the atomic structure of all Si/SiO nanowires and to the opening of the semiconductor gap (1.4eV) in the TDOS. The top of the valence band and the bottom of the conductivity band of the Si/SiO nanoobjects are formed manly by Si p-states.
Sakai, Seiji; Matsumoto, Yoshihiro; Entani, Shiro; Otomo, Manabu; Sorokin, B. P.*; Avramov, P.; Naramoto, Hiroshi*; Sakuraba, Yuya*; Takanashi, Koki
no journal, ,
no abstracts in English
Entani, Shiro; Sorokin, B. P.*; Avramov, P.; Otomo, Manabu; Matsumoto, Yoshihiro; Narita, Ayumi; Hirao, Norie; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Naramoto, Hiroshi*; et al.
no journal, ,
no abstracts in English
Entani, Shiro; Sorokin, B. P.*; Avramov, P.; Otomo, Manabu; Matsumoto, Yoshihiro; Narita, Ayumi; Hirao, Norie; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Naramoto, Hiroshi*; et al.
no journal, ,
Entani, Shiro; Sorokin, P. B.*; Avramov, P.*; Otomo, Manabu; Matsumoto, Yoshihiro; Antipina, L. Y.*; Hirao, Norie; Shimoyama, Iwao; Naramoto, Hiroshi*; Baba, Yuji; et al.
no journal, ,
Sakai, Seiji; Sorokin, B. P.*; Entani, Shiro; Naramoto, Hiroshi*; Yotsuya, Shintaro*; Ando, Kazuya*; Yamauchi, Yasushi*
no journal, ,
no abstracts in English
