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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Tikhonova L. V., Fedorov A. S.
Заглавие : Ab initio investigation of a new boron nitride allotrope
Коллективы : Russian Foundation for Basic Research [12-02-00640]
Место публикации : Phys. Status Solidi B. - 2014. - Vol. 251, Is. 6. - P.1282-1285. - ISSN 0370-1972, DOI 10.1002/pssb.201350389. - ISSN 1521-3951
Примечания : Cited References: 31. - We acknowledge support of the Russian Foundation for Basic Research through Grant No. 12-02-00640. Also, we thank the Institute of Computer Modeling (Siberian Division, Russian Academy of Sciences, Krasnoyarsk), the Joint Supercomputer Center of the Russian Academy of Sciences (Moscow), the computer cluster "Chebyshev" of the Moscow State University (Moscow), and the supercomputer of the Institute of Space and Information Technologies of the Siberian Federal University for providing an opportunity to use their computers for performing all calculations.
Предметные рубрики: AUGMENTED-WAVE METHOD
MOLECULAR-DYNAMICS
TRANSITION
METALS
Ключевые слова (''Своб.индексиров.''): boron nitride--computational materials science--density functional theory--elastic properties--superhard materials
Аннотация: A new allotropic superhard and superdense structure of sp3-bonded boron nitride (hP3-BN) is proposed. Geometric electronic, elastic, and optical properties of the structure are investigated by density functional theory generalized gradient approximation (DFT-GGA) calculations. It is shown that the structure is an insulator with a band gap of 5.06 eV; is density is 5.03% higher than that of cubic boron nitride (c-BN) and its bulk modulus is 2.25% higher than that of c BN. The calculated hP3-BN refractive index in the range 200-800 nm is significantly higher than the indexes of diamond and all known carbon allotropes, expect for the analogous carbon h-P3 structure, and it has a large optical dispersion. In the range above 800 nm the refractive index changes from 2.60 to 2.35. (C) WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pichugin K. N., Sadreev A. F.
Заглавие : Aharanov-Bohm oscillations of conductance in two-dimensional rings
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1997. - Vol. 56, Is. 15. - P9662-9673. - ISSN 0163-1829, DOI 10.1103/PhysRevB.56.9662
Примечания : Cited References: 56
Предметные рубрики: NORMAL-METAL RINGS
HALF FLUX QUANTA
MESOSCOPIC RING
MAGNETIC-FIELD
CIRCULAR BENDS
EDGE STATES
MAGNETOTRANSPORT
TRANSPORT
WIRES
TRANSITION
Аннотация: Transport properties of mesoscopic rings with applied external magnetic field are considered numerically. Rings have square and circular forms and a finite aspect ratio d/L where L is the ring size and d is the width of ring arms. The type of the Aharonov-Bohm oscillations (ABO's) of the transmission substantially depends on the number of channels participating in the electron transmission. Moreover the aspect ratio and the geometrical form of the ring are important for the ABO's. In square rings with a small aspect ratio (d/L = 1/10) the transmission displays periodic ABO's in the region of applied magnetic field defined by the inequality infinity l(B) = ((h) over bar c/eB)(1/2)greater than or equal to d, while for rings with a large aspect ratio (d/L = 1/3) only the single-channel transmission has quasiperiodical ABO's. For the circular rings with small aspect ratios the quasiperiodic ABO's are observed all over the region of the applied magnetic field while for the rings with moderate aspect ratios only the multichannel transmission displays irregular ABO's. The probability current flow patterns demonstrate fine correspondence between the transmission and the vortex structure of current distributions in the rings. For single-channel transmission, electron currents are laminar. For multichannel transport, current flow patterns display a complicated convection pattern in the form of a vortex lattice. An elementary cell of the vortex lattice consists of a few vortices and antivortices and has a size of similar to d/f, where f is the number of channels of electron transmission in the ring. Application of the flux distorts the vortex lattice enormously, partially destroying it. Correspondingly the Aharonov-Bohm oscillations of the transmission become irregular.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Serzhantova M. V., Kuzubov A. A.
Заглавие : Analysis of hydrogen adsorption in the bulk and on the surface of magnesium nanoparticles
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 1. - P126-132. - ISSN 1063-7761, DOI 10.1134/S1063776108070121
Примечания : Cited References: 15. - This study was supported financially by the Russian Foundation for Basic Research ( project no. 06-02-16132). The authors are also grateful to the Institute of Computer Modeling of the Siberian Branch of the Russian Academy of Science for providing a cluster computer on which all quantum-chemistry calculations were performed.
Предметные рубрики: MOLECULAR-DYNAMICS
TRANSITION
METALS
Ключевые слова (''Своб.индексиров.''): adsorption--gas adsorption--hydrogen--light metals--magnesium--nonmetals--hydrogen adsorption--magnesium hydrides--magnesium printing plates
Аннотация: The stability of magnesium hydride (MgH (x) ) nanoparticles (x = 0.5,...,2) is investigated using ab initio calculations. It is shown that for a nanoparticle diameter of D similar to 5 nm, the internal pressure becomes lower than 3 kbar; for this reason, the structure of hydride nanoparticles coincides with the structure of this hydride in crystalline form. It is found that the phase of partly saturated MgH (x) hydrides (x 2) must decompose into the phase of pure hcp magnesium and the alpha phase of MgH(2). The frequencies of jumps of hydrogen atoms within the hcp phase of magnesium and in the alpha phase of MgH(2) are calculated; it is shown that slow diffusion of hydrogen in magnesium is due to the large height of potential barriers for motion of hydrogen within MgH(2). To attain high diffusion rates, the structures of Mg(53)Sc and Mg(53)Ti crystals and their hydrides are calculated. It is found that the frequency of jumps of H atoms in Mg(53)ScH(108) near the Sc atoms does not noticeably change as compared to the frequency of jumps in the alpha phase of MgH(2), while the frequency of jumps in Mg(53)TiH(108) near Ti atoms is higher by approximately a factor of 2.5 x 10(6). This means that diffusion in manganese hydride with small admixtures of titanium atoms must be considerably eased. Chemical dissociation of hydrogen molecules on the (0001) surface of hcp magnesium, on the given surface with adjoined individual Ti atoms, and on the surface of a one-layer titanium cluster on the given surface of magnesium is investigated. It is found that dissociation of hydrogen at solitary titanium atoms, as well as on the surface of a Ti cluster, is facilitated to a considerable extent as compared to pure magnesium. This should also sharply increase the hydrogen adsorption rate in magnesium nanoparticles.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krakhalev M. N., Sutormin V. S., Prishchepa O. O., Kuz'menok N. M., Mikhalyonok S. G., Bezborodov V. S., Zyryanov V. Ya.
Заглавие : Anionic-cationic surfactant mixture providing the electrically controlled homeotropic surface anchoring of liquid crystals
Коллективы : International conference on Hole Burning, Single Molecule, and Related Spectroscopies: Science and Applications - 2018 , Belarusian Republican Foundation for Fundamental Research [X16P-110]; Russian Foundation for Basic Research (RFBR) [16-53-00073]; RFBR, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [18-42-243006]
Место публикации : J. Mol. Liq. - 2019. - Vol. 282: Suzdal Conference (2018, Suzdal, RUSSIA). - P.57-62. - ISSN 0167-7322, DOI 10.1016/j.molliq.2019.02.132. - ISSN 1873-3166(eISSN)
Примечания : Cited References: 30. - The reported study was supported by the Belarusian Republican Foundation for Fundamental Research (project No X16P-110) and Russian Foundation for Basic Research (RFBR) (project No 16-53-00073). Mikhail N. Krakhalev and Vitaly S. Sutormin acknowledge financial support from RFBR, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (project No 18-42-243006).
Предметные рубрики: IONIC MODIFICATION
TRANSITION
DROPLETS
CONFIGURATION
LAYER
Аннотация: In search of a substance able to function as an anionic surfactant applied for the electrically-induced anchoring transitions in liquid crystals, the compound 4-heptyloxybenzoate benzyl dodecyldimethylammonium (HOBBDDA) has been synthesized. Its orienting influence on nematic liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) has been tested. HOBBDDA dissolved up to 1.4%in 50 droplets dispersed in polymer film does not change the tangential surface anchoring inherent to polyvinyl alcohol matrix used. Homeotropic surface anchoring is realized if the HOBBDDA content exceeds 1.7%. The molecules of the surfactant in 5CB dissociate into anions and cations. The anions modify the surface anchoring under the action of DC electric field both in the normal and inverse mode. The mixture of HOBBDDA and cetyltrimethylammonium bromide can function as a binary ionic cationic surfactant which significantly expands the prospects for using the ionic-surfactant method to control liquid crystal materials. (C) 2019 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Piskunova N. I.
Заглавие : Anomalies in magnetoresistance and in the bulk modulus for ferromagnetics with four-spin exchange interaction on the Kondo lattice
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2006. - Vol. 18, Is. 29. - P.6859-6868. - ISSN 0953-8984, DOI 10.1088/0953-8984/18/29/023
Примечания : Cited References: 29
Предметные рубрики: MIXED-VALENCE MANGANITES
PHASE-SEPARATION
LA1-XSRXMNO3
BEHAVIOR
PECULIARITIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): elastic moduli--electric resistance--ferromagnetism--function evaluation--paramagnetism--transceivers--adiabatic approximation--kondo lattice--paramagnetic state--ring exchange--magnetoresistance
Аннотация: The temperature dependence of resistivity and the bulk modulus are calculated on the Kondo lattice, with ring exchange between localized spins, using the spin-polaron and adiabatic approximation. Peak and zero values of the bulk modulus as functions of temperature and concentration are determined below the temperature of the transition to the paramagnetic state. The effects of the nearest order between transverse spin components and a value of the ring exchange between localized spins on magnetoresistivity are estimated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Sorokin P. B., Fedorov A. S., Fedorov D. G., Maeda Y.
Заглавие : Band-gap unification of partially Si-substituted single-wall carbon nanotubes
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2006. - Vol. 74, Is. 24. - Ст.245417. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.245417
Примечания : Cited References: 72
Предметные рубрики: SILICON-CARBIDE NANOTUBES
DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
WAVE BASIS-SET
ELECTRONIC-STRUCTURE
AB-INITIO
NANORODS
EXCITATIONS
TRANSITION
NANOWIRES
Аннотация: 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 local-density approximation (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) single wall carbon nanotubes (SWCNT) results in a band gap minimum (0.27 eV) at similar to 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 Gamma-Gamma point. The calculation of the chiral (8,2) SWSi0.15C0.85NT system gives a similar (0.6 eV) direct band gap. The regular distribution of Si atoms in the atomic lattice is by similar to 0.1 eV/atom energetically preferable in comparison with a random distribution. Time dependent density functional theory (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 the band gaps of all SWCNT species, the large values of Si3p parallel to r parallel to Si3s radial integrals and participation of Si3d states in chemical bonding in both valence and conductance bands.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Krasnov P. O., Kozhevnikov T. A., Popov M. A.
Заглавие : Calculation of the energy of binding of titanium and scandium complexes to the surface of carbon nanotubes
Коллективы : Analytical departmental program "Development of Higher Education Potential" [2.1.1/2584]; Russian Foundation for Basic Research [09-02-00324-a]
Место публикации : Russ. J. Phys. Chem. B. - 2009. - Vol. 3, Is. 4. - P.679-683. - ISSN 1990-7931, DOI 10.1134/S1990793109040289
Примечания : Cited References: 27. - This work was supported by the analytical departmental program "Development of Higher Education Potential (2009-2100)" (grant 2.1.1/2584) and by the Russian Foundation for Basic Research, project no. 09-02-00324-a.
Предметные рубрики: MOLECULAR-HYDROGEN COMPLEXES
STORAGE
TEMPERATURE
TRANSITION
DYNAMICS
METALS
Аннотация: Complexes of zigzag-type carbon nanotubes (CNTs) with transition metal atoms, scandium and titanium, were studied. It was demonstrated that the energy of binding of both atoms with a carbon surface decreases whereas the rate of diffusion along the surface increases with increasing nanotube diameter. The rate constant of migration of scandium atoms over a CNT surface are several orders of magnitude higher than that for titanium atoms, because the CNT surface-Sc atom binding energy is substantially lower.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Sabitova E. I., Semenov S. V., Shaykhutdinov K. A., Shabanov A. V., Petrov M. I.
Заглавие : Compression of a magnetic flux in the intergrain medium of a YBa2Cu3O7 granular superconductor from magnetic and magnetoresistive measurements
Разночтения заглавия :авие SCOPUS: Compression of a magnetic flux in the intergrain medium of a YBa 2Cu 3O 7 granular superconductor from magnetic and magnetoresistive measurements
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 110, Is. 9. - Ст.93918. - ISSN 0021-8979, DOI 10.1063/1.3657775
Примечания : Cited References: 21. - We thank V. V. Val'kov and A. D. Balaev for useful discussions of the results and I. Nemtsev for microscopic study of the samples. The study was supported by the Program of the Russian Academy of Sciences No. 5, Project No. 7.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
CRITICAL-CURRENT-DENSITY
CRITICAL-STATE MODEL
CRITICAL CURRENTS
JOSEPHSON MEDIUM
FIELD
TRANSITION
Ключевые слова (''Своб.индексиров.''): effective field--external fields--field dependence--field induced--granular superconductors--inter-grain--josephson--magnetoresistive--space between--superconducting grains--transport currents--electric resistance--magnetic flux--magnetic moments--superconductivity--superconducting materials
Аннотация: A method to determine a value of the effective field in the intergrain medium of a granular superconductor is proposed. The space between superconducting grains is considered to be a Josephson medium where passage of the transport current causes dissipation and the effective field is superposition of external field H and the field induced by magnetic moments of superconducting grains. The method proposed is based on the comparison of hysteresis field dependences of magnetoresistance and magnetization and their relaxation at H=const. By the example of granular YBa2Cu3O7, it is shown that, in the region of weak fields, the effective field in the intergrain medium exceeds by far the external field, i.e., compression of a magnetic flux occurs. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3657775]
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Orlov Y. S., Ovchinnikov S. G.
Заглавие : Construction of a Multielectron Basis for Mott Insulators with Strong Electron Correlations, Spin-Orbit Interaction, and Covalence
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 2. - P.322-338. - ISSN 1063-7761, DOI 10.1134/S1063776109080196
Примечания : Cited References: 35
Предметные рубрики: NARROW ENERGY BANDS
MAGNETIC ANISOTROPY ENERGY
ORIGIN
TRANSITION
PHYSICS
MANGANITES
OXIDES
CHARGE
Аннотация: We propose that the apparatus of quantum mechanics of a free atom (in particular, the theory of nj symbols and Rakah-Wigner genealogic coefficients generalized to the case of point groups and widely used in crystal field theory) be used for constructing multielectron bases with allowance for covalence and spin-orbit interaction. This allows us to take into account the electron-electron interaction for 3d ions the most comprehensively. The basis constructed in this way can be used in the generalized strong coupling method for the multiband p-d model in describing the structure of the quasiparticle energy spectrum and physical properties of systems with strong electron correlations. The procedure of construction and computation is demonstrated for the (5)T(2g) term in the d(6) configuration of the transition metal atom in an octahedral field. The mechanism for the emergence of magnetic anisotropy in S ions (Fe(3+) and Mn(2+)) due to covalent mixing of d(6) (L) under bar configurations with a nonzero orbital angular momentum ((L) under bar is a hole in ligands) is demonstrated
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ohtomo M., Yamauchi Y., Kuzubov A. A., Eliseeva N. S., Avramov P. V., Entani S., Matsumoto Y., Naramoto H., Sakai S.
Заглавие : Contact-induced spin polarization of monolayer hexagonal boron nitride on Ni(111)
Место публикации : Appl. Phys. Lett.: American Institute of Physics, 2014. - Vol. 104, Is. 5. - Ст.51604. - ISSN 0003-6951, DOI 10.1063/1.4863324. - ISSN 1077-3118
Примечания : Cited References: 20. - This study was supported by the Grant-in-Aid for Scientific Research (Grant Nos. 23860067 and 24760033) from the Japan Society for the Promotion of Science.
Предметные рубрики: METASTABLE DEEXCITATION SPECTROSCOPY
METAL-SURFACES
FILMS
TRANSITION
Аннотация: Hexagonal boron nitride (h-BN) is a promising barrier material for graphene spintronics. In this Letter, spin-polarized metastable de-excitation spectroscopy (SPMDS) is employed to study the spin-dependent electronic structure of monolayer h-BN/Ni(111). The extreme surface sensitivity of SPMDS enables us to elucidate a partial filling of the in-gap states of h-BN without any superposition of Ni 3d signals. The in-gap states are shown to have a considerable spin polarization parallel to the majority spin of Ni. The positive spin polarization is attributed to the pi-d hybridization and the effective spin transfer to the nitrogen atoms at the h-BN/Ni(111) interface. (C) 2014 AIP Publishing LLC.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Semenov S. V., Bykov A. A., Sabitova E. I., Dubrovskiy A. A., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Contributions from Inter-grain Boundaries to the Magneto-resistive Effect in Polycrystalline High-T (C) Superconductors. The Underlying Reason of Different Behavior for YBCO and BSCCO Systems
Разночтения заглавия :авие SCOPUS: Contributions from inter-grain boundaries to the magneto-resistive effect in polycrystalline high-TC superconductors. the underlying reason of different behavior for YBCO and BSCCO systems
Место публикации : J. Supercond. Nov. Magn: SPRINGER, 2011. - Vol. 24, Is. 7. - P2129-2136. - ISSN 1557-1939, DOI 10.1007/s10948-011-1166-9
Примечания : Cited References: 30. - This work is supported by program N5 of RAS, project N7.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
PHASE-SLIP
TRANSPORT-PROPERTIES
TRANSITION
FIELD
COMPOSITES
BULK
TAPES
YBA2CU3O7-DELTA
DISSIPATION
Ключевые слова (''Своб.индексиров.''): bscco--ybco--intergrain boundaries--magnetoresistance--bscco--intergrain boundaries--magnetoresistance--ybco--bscco--bscco system--comparative studies--high tc superconductors--high-field--inter-grain--irreversibility lines--magneto-resistive effect--polycrystalline--resistive transition--standard measurements--weak pinning--ybco--bismuth--electric resistance--grain boundaries--high temperature superconductors--lead--magnetic fields--magnetoelectronics--magnetoresistance--magnetos--superconductivity--yttrium barium copper oxides--semiconductor metal boundaries
Аннотация: In order to clarify the mechanisms in charge of broadening of resistive transition R(T) in magnetic fields of bismuth-based polycrystalline high-T (C) superconductor (HTSC), a comparative study of Bi1.8Pb0.3Sr1.9Ca2Cu3O (x) (BSCCO) and YBa2Cu3O7-delta (YBCO) have been performed. Magnetoresistive effects and irreversibility line obtained from magnetic measurements have been studied. It was established that (1) for YBCO, the smooth part of R(T) dependence unambiguously corresponds to dissipation in the intergrain boundaries for arbitrary magnetic fields; (2) for polycrystalline BSCCO, the smooth part of R(T) dependences correspond to dissipation within intergrain boundary subsystem in the field range H 10(2) Oe only, while standard measurements of R(T) dependences in magnetic field range H 10(2) Oe reflect the dissipation processes occurring both in intergrain boundary and HTSC grain subsystems; (3) for the high-field range, the contribution from intergrain boundaries of BSCCO can be distinguished from magnetoresistance R(H) dependences obtained at high enough current density on textured samples. It is proposed that various magneto-resistive properties of these classical HTSC systems are due comparatively weak pinning in BSCCO.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Orlov Yu. S.
Заглавие : Covalence-induced stabilization of an intermediate-spin state and the magnetic susceptibility of LaCoO3
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 104, Is. 3. - P436-444. - ISSN 1063-7761, DOI 10.1134/S1063776107030090
Примечания : Cited References: 24. - This work was supported by the program of the Division of Physical Sciences of the Russian Academy of Sciences “Strong Electronic Correlations,” the integration project SORAN-URORAN (grant no. 74), and the Krasnoyarsk krai Science Foundation
Предметные рубрики: TRANSITION
Ключевые слова (''Своб.индексиров.''): band structure--electron transitions--ground state--hamiltonians--magnetic susceptibility--magnetic variables measurement--spin dynamics--covalence induced stabilization--diagnoalization--orbital degeneracy--spin states--lanthanum compounds
Аннотация: The energies of terms with spins S = 0, 1, 2 have been found using exact diagonalization of the multielectron Hamlitonian of a multiband pd model for the CoO6 cluster. Co (e(g) orbital)-O hops, which form the covalent sigma bond, are shown to decrease the energy of the state (IS) with an intermediate spin (S = 1) as compared to the energy of the state (LS) with a low spin (S = 0). An analogue of the Tanabe-Sugano diagram that takes into account the covalence of the CoO6 cluster is constructed. The state with S = 1 is shown to be a ground state at certain model parameters. An increase in temperature is established to decrease the crystal field and, thus, favors the transition of the ground state from LS to IS at T = 100 K and the transition of the IS ground state to a state (HS) with a high spin (S = 2) at T = 550 K. The magnetic susceptibility of LaCoO3 is calculated with allowance for the LS, IS, and HS states and for the fact that the HS state exhibits threefold orbital degeneracy of the t(2g) shell, which results in an effective orbital moment L = 1 and the importance of spin-orbit interaction. The behavior of this magnetic susceptibility agrees well with the experimental chi(T) dependence of LaCoO3.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Beznosikov B. V.
Заглавие : Crystal chemistry and prediction of compounds with a structure of skutterudite type
Место публикации : Crystallogr. Rep. - 2007. - Vol. 52, Is. 1. - P.28-36. - ISSN 1063-7745, DOI 10.1134/S106377450701004X
Примечания : Cited References: 47
Предметные рубрики: SUPERCONDUCTOR PROS4SB12
MAGNETIC-PROPERTIES
HIGH-PRESSURE
RARE-EARTH
TRANSITION
LAFE4P12
Аннотация: Crystallochemical analysis of skutterudite-type structures in the BX3, AB(4)X(12), and A B-3' B4O12 compositions (A and B are metals; X = P, As, Sb) has been performed. Probable regions of structure formation are determined, thereby indicating that more than 270 new compounds of the AB4X12 composition can be synthesized.(1)
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Belozerova I. L., Gokhfeld D. M., Kashkina L. V., Kuzmin Y. I., Michel C. R., Petrov M. I., Popkov S. I., Shaikhutdinov K. A.
Заглавие : Current-voltage characteristics of a foamed Bi1.8Pb0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Разночтения заглавия :авие SCOPUS: Current-voltage characteristics of a foamed Bi1.8Pb 0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Место публикации : Phys. Solid State: SPRINGER, 2006. - Vol. 48, Is. 2. - P207-212. - ISSN 1063-7834, DOI 10.1134/S1063783406020016
Примечания : Cited References: 27
Предметные рубрики: T-C SUPERCONDUCTORS
NORMAL-PHASE
VORTEX MOTION
TRANSITION
TRANSPORT
VORTICES
Аннотация: The influence of the structure of foamed polycrystalline bismuth-based superconductors on their critical currents and current-voltage characteristics is studied. It is found that superconducting foams have a fractal structure, and the fractal dimension of the boundary between the normal and superconducting phases is estimated. The magnetic and transport properties of superconducting foams are investigated, and the current-voltage characteristics are obtained in a wide range of currents. The effect of percolation phenomena on vortex pinning in a foamed superconductor is considered. The current-voltage characteristics of the superconducting foams at the beginning of the resistive transition are found to be in good agreement with a model in which a magnetic flux is assumed to be trapped in the fractal clusters of a normal phase.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Dimension of mesogenic molecules as atomic clusters
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 2. - P378-389. - ISSN 1063-7834, DOI 10.1134/1.1866424
Примечания : Cited References: 19
Предметные рубрики: LIQUID-CRYSTAL CHEMISTRY
ORIENTATIONAL ORDER
TRANSITION
Аннотация: The problem regarding the mass dimension D of mesogenic molecules as atomic clusters is formulated and solved using computer simulation and analytical calculations. For a large number of compounds belonging to different chemical classes, it is shown that the cores of discotic lacunar (rodlike, lathlike) molecules forming nematic or columnar discotic (calamitic) phases have a fractional dimension 1 D-c 2 (D-c approximate to 1). The dependences of the dimension D-c on the symmetry, the conformation, and the structural-chemical features of the molecular core are determined. It is demonstrated that, in the region of side flexible chains in molecules of both types, the dimension D-ch can be either smaller or larger than unity, depending on the chain conformation. An analytical expression accounting for the results of numerical experiments is obtained for the dimension D-ch. (C) 2005 Pleiades Publishing, Inc.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Prishchepa O. O., Shabanov A. V., Zyryanov V. Y.
Заглавие : Director configurations in nematic droplets with inhomogeneous boundary conditions
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 72, Is. 3. - Ст.31712. - ISSN 1539-3755, DOI 10.1103/PhysRevE.72.031712
Примечания : Cited References: 22
Предметные рубрики: DISPERSED LIQUID-CRYSTALS
TRANSITION
Ключевые слова (''Своб.индексиров.''): lecithin contents--nematic droplets--polarizers--radial structures--approximation theory--boundary conditions--drop breakup--free energy--polarization--textures--nematic liquid crystals
Аннотация: The nematic droplets with director configurations intermediate between the bipolar and radial structures have been investigated experimentally and theoretically. The liquid crystal 4(')-n-pentyl-4-cyanobiphenyl (5CB) with a variable addition of the lecithin dispersed in polyvinylbutyral has been used. The characteristic textures of the droplets formed at various lecithin contents have been examined using polarizing microscope both in the crossed polarizers and without analyzer. The computer simulation has been performed for proper ordering of the director in spherical nematic droplets by minimizing the free energy in the one-constant approximation. The inhomogeneous boundary conditions with strong anchoring of the molecules at the interface have been used. The distribution of the anchoring angle at the droplet surface has been estimated based on analysis of observed patterns. The simulated textures of the droplets under crossed polarizers are shown to compare well with the experimental ones.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Aplesnin S. S., Udod L. V.
Заглавие : Effect of electron and hole doping on the transport characteristics of chalcogenide systems
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Belarusian Republican Foundation for Basic Research [20-52-00005]
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 5. - P.754-757. - ISSN 1063-7834, DOI 10.1134/S1063783421050152. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 21. - This study was supported by the Russian Foundation for Basic Research and the Belarusian Republican Foundation for Basic Research, project no. 20-52-00005
Предметные рубрики: MAGNETIC-PROPERTIES
TRANSITION
Аннотация: The electrical properties of the Ag0.01Mn0.99S and Tm0.01Mn0.99S semiconductor compounds and the Hall effect in them have been investigated in the temperature range of 80-400 K in a magnetic field of 12 kOe. Using the I-V characteristics, the conductivity mechanism depending on the doping type and concentration has been established. Upon substitution of silver for manganese, the Mott-type conductivity has been found, while substitution of thulium causes the ohmic conductivity. The mobility and type of carriers have been determined from the Hall constant data.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd Yu. S., Dubrovskii A. A., Shaikhutdinov K. A.
Заглавие : Effect of heterovalent substitution of rare-earth elements on the magnetic and transport properties of YBa2Cu3O7
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 11. - P2047-2051. - ISSN 1063-7834, DOI 10.1134/S1063783407110054
Примечания : Cited References: 18
Предметные рубрики: PR
SUPERCONDUCTIVITY
CE
ND
TRANSITION
SYSTEM
LA
Аннотация: The Y(1-x) Ce (x) Ba2Cu3O7 system with low cerium concentrations has been synthesized. The cerium solubility limit measured using x-ray powder diffraction analysis is about 2.4 at. %. The temperature dependences of the magnetization M(T) are measured for samples cooled in a magnetic field (FC) and in a zero field (ZFC). The difference between the magnetizations M-ZFC-M-FC at 77.4 K, which is proportional to the pinning potential, passes through a maximum at x = 0.0156. This concentration corresponds to the average distance (equal to eight lattice constants) between the impurity ions in the plane of the rare-earth elements, which is comparable to the diameter of Abrikosov vortices in YBa2Cu3O7.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Pankrats A. I., Petrakovskii G. A., Rasch JCE, Boehm M., Vorotynov A. M., Tugarinov V. I., Szumszak R., Bovina A. F., Vasil'ev V.
Заглавие : Electron spin resonance in CuCrS(2) chrome-copper disulphides synthesized by different methods
Разночтения заглавия :авие SCOPUS: Electron spin resonance in CuCrS 2 chrome-copper disulphides synthesized by different methods
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2010. - Vol. 107, Is. 9. - Ст.93914. - ISSN 0021-8979, DOI 10.1063/1.3374679
Примечания : Cited References: 13
Предметные рубрики: COLOSSAL MAGNETORESISTANCE
PHYSICAL-PROPERTIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): chemical vapor transport--electron spin resonance--ferromagnets--g-values--magnetic transitions--polycrystalline--synthesis method--temperature range--astatine--paramagnetism--resonance--single crystals--spin dynamics--crystal impurities
Аннотация: The electron spin resonance (ESR) in CuCrS(2) disulphides is found to be strongly dependent on a synthesis method used. At a temperature of 300 K, a polycrystalline CuCrS(2) sample is paramagnetic with a g-value of 1.95 at 40 K, it undergoes the magnetic transition. In the temperature range 4.2-290 K, a single-crystal sample prepared by a chemical vapor transport method exhibits the ESR features typical of a ferromagnet. It is shown that these features are related to the presence of a small amount of the single-crystal CuCr(2)S(4) impurity in the CuCrS(2) single crystal. (C) 2010 American Institute of Physics. [doi:10.1063/1.3374679]
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyan I. A., Gavrilyuk A. G., Ovchinnikov S. G., Lyubutin I. S., Kazak N. V.
Заглавие : Electron transport in FeBO3 ferroborate at ultrahigh pressures
Место публикации : JETP Letters. - 2012. - Vol. 94, Is. 10. - P.748-752. - ISSN 0021-3640, DOI 10.1134/S0021364011220115
Примечания : Cited References: 22. - This work was supported by the Russian Foundation for Basic Research (project nos. 09-02-01527-a, 09-02-00127-a, 09-02-00171-a, 11-02-00291-a, and 11-02-00636-a), by the Ministry of Education and Science of the Russian Federation (state contract nos. 16.518.11.7021 and MK-5632.2010.2), and by the Division of Physical Sciences, Russian Academy of Sciences (program "Strong Electron Correlations").
Предметные рубрики: MAGNETIC COLLAPSE
TRANSITION
STATE
Аннотация: The electrical resistance of FeBO3 crystals at high and ultrahigh pressures (up to 198 GPa) and low temperatures has been measured using diamond anvil cells. It has found that in the high-pressure phase, 46 GPa ‹ P‹ 100 GPa, the activation energy E-ac decreases gradually from 0.55 to 0.3 eV according to a linear law. Its extrapolation to zero gives an estimated value of about 210 GPa for the pressure at which complete metallization is expected. However, above 100 GPa, the linear E-ac(P) dependence smoothly transforms to a nonlinear one. At the same time, the temperature dependence of the electrical resistance at fixed pressure significantly deviates from the Arrhenius activation law and does not obey the Mott law for the hopping conductivity. Experimental data demonstrate the dependence of the activation energy E-ac both on pressure and temperature. At T = 0, the gap tends to zero. Theoretical analysis shows that the decrease in E-ac upon cooling can be interpreted in terms of the transition of the low-spin FeBO3 phase to the magnetically ordered (anti-ferromagnetic) state.
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