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721.
Yu. F. Markov Yu. E. Kitaev E. M. Roginskii 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(9):1059-1063
N-benzylanyline single crystals are grown, and X-ray diffraction probing of their structure allows their symmetry to be attributed to the C2h.5 phase. Polarized Raman studies of these crystals allow the frequencies of lattice phonons to be estimated and their symmetry to be established. The abnormal behavior of the two lowest-frequency Ag symmetry soft modes, the condensation of which is not detected below the melting point (36–38°C), is noted. The possibility of a high-temperature virtual phase transition and praphase is discussed. Theory group consideration of the praphase allows determination of its symmetry and the symmetry of phonons related to the virtual phase transition. 相似文献
722.
A.?S.?KatyshevaEmail author V.?F.?Markov L.?N.?Maskaeva 《Theoretical and Experimental Chemistry》2012,47(6):390-393
We propose a technique for wet-chemical codeposition of lead sulfide and selenide using thiourea and selenourea to form films
of PbSe
y
S1–y
substitutional solid solutions. The synthesized nanocrystalline layers with NaCl (B1) structure simultaneously contain both
PbS-based and PbSe-based PbSe
y
S1–y
solid solutions (0 < y < 0.9). 相似文献
723.
V. V. Kharton A. V. Kovalevsky A. A. Yaremchenko F. M. M. Snijkers J. F. C. Cooymans J. J. Luyten A. A. Markov J. R. Frade F. M. B. Marques 《Journal of Solid State Electrochemistry》2006,10(8):663-673
Measurements of oxygen permeation through dense composite membranes showed a considerable influence of processing conditions on the surface exchange kinetics, while the
bulk ambipolar conductivity is almost unaffected by microstructural factors. Compared to the materials prepared via the glycine–nitrate
process (GNP), the surface limitations to oxygen transport are significantly higher for dual-phase made of a commercial powder synthesized by spray pyrolysis. This difference in behavior may be related to compositional inhomogeneities
in the grains of A-site deficient perovskite phase and an enhanced surface concentration of grain boundaries in the case of
GNP-synthesized composite, which has also smaller grain size, slightly higher thermal expansion and lower total conductivity.
No essential effects on Vickers hardness, varying in the range 6.3–6.5 GPa, were found. The deposition of porous catalyst
layers onto the composite surface exposed to reducing environment leads to membrane decomposition. For the fabrication of
tubular membranes, the cold isostatic pressing technique was, hence, combined with mechanical treatment to increase the specific
surface area without incorporation of catalytically active components. 相似文献
724.
Pseudogeometries with clusters and an example of a recursive [4, 2, 3]<Subscript>42</Subscript>-code
V. T. Markov A. A. Nechaev S. S. Skazhenik E. O. Tveritinov 《Journal of Mathematical Sciences》2009,163(5):563-571
In 1998, E. Couselo, S. Gonzalez, V. Markov, and A. Nechaev defined the recursive codes and obtained some results that allowed
one to conjecture the existence of recursive MDS-codes of dimension 2 and length 4 over any finite alphabet of cardinality
q ∉ {2, 6}. This conjecture remained open only for q ∈ {14, 18, 26, 42}. It is shown in this paper that there exist such codes for q = 42. We used a new construction, that of pseudogeometry with clusters. 相似文献
725.
Polyna V. Anikina Alexey A. Markov Mikhail V. Patrakeev Ilia A. Leonidov Victor L. Kozhevnikov 《Solid State Sciences》2009,11(6):1156-1162
The conductivity is measured in the series of solid solutions SrFe1 ? xNbxO3 ? δ, where x = 0.05, 0.1, 0.2, 0.3, 0.4, within the oxygen partial pressure limits 10?18–0.5 atm and temperature range 650–950 °C. The contributions to the total conductivity from oxygen ions, electrons and electron holes are obtained based on their different pressure dependences. The doped derivative with x = 0.1 is found to be a singular composition where ion conductivity attains a maximal value while activation energy for ion transport is minimal. This peculiar behavior is attributed to formation of favorable microstructure in the oxide. The deeper doping results in deterioration of ion transport, which is explained by oxygen vacancy filling. It is shown that replacement of iron for niobium favors enhanced thermodynamic stability towards reduction. The oxygen permeability is evaluated from the conductivity data, and it achieves rather high values in the doped derivatives. These oxides can, therefore, be recommended for further evaluation as oxygen separating membrane materials for partial oxidation of natural gas. 相似文献
726.
Yu. F. Markov E. M. Roginskii A. S. Yurkov 《Journal of Experimental and Theoretical Physics》2012,114(2):288-295
Information is obtained about the temperature behavior of the order parameter of a phase transition by theoretical and experimental
investigation of odd (acoustic and IR-active) phonons that appear in the Raman scattering spectra from the X points of the Brillouin zone (BZ) boundary in the paraphase of Hg2Cl2 crystals and are induced by the phase transition, unit-cell doubling, and the X → Γ folding in the BZ. The relevant critical exponents are determined, whose values are in agreement with the results of
X-ray diffraction measurements and, within the Landau phenomenological theory of phase transitions, indicate that the phase
transition in these crystals is close to the tricritical point. 相似文献
727.
The excitation functions of the (γ, n) and (γ, γ′) reactions leading to the formation of the 239Pu, 241Pu, 240Am, 242Am and 243Am spontaneously fissioning isomers have been measured. The experiments have been carried out using a 17-orbit microtron. A spark counter with pulsed feeding served as a fission fragment detector. From the excitation functions measured, the parameters of a two-humped fission barrier have been obtained and compared with other experimental results and theoretical calculations. 相似文献