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81.
We have investigated the superconducting properties of the Bi1.7 Pb0.3Sr2Ca2−xCe
x
Cu3O10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found
to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate
decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T
c (2 : 2 : 2 : 3) phase decreases and low T
c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition
temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent
state in this system; that is, Ca2+ → Ce4+ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T
c of the system. 相似文献
82.
I. A. Sedov M. A. Stolov B. N. Solomonov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(4):621-626
A method for analyzing the thermodynamical manifestations of solvophobic effects is proposed on the basis of considering the
relationship between the Gibbs energy and solvation enthalpy of nonelectrolytes. It is demonstrated that, for solutions in
nonassociated solvents, there is a linear isoequilibrium dependence between them, and the coefficients of linear dependence
are almost equivalent for various dissolved substances and solvents. It is determined that the deviations from this dependence
observed in the case of associated solvents are always positive, and the consequences of the manifestations of solvophobic
effects are considered. The contributions from the solvophobic effect to the Gibbs energy of solvation of various nonpolar
compounds in methanol are determined on the basis of a thermodynamic model of solvation suggested earlier. It is shown that
in both methanol and aqueous solutions, the values of these contributions correlate linearly with the characteristic molecular
volume of the dissolved substance. 相似文献
83.
B. N. Solomonov K. V. Zaitseva M. A. Varfolomeev I. A. Sedov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(5):811-815
We propose a method for calculating the Gibbs energies of hydrogen bonding of solutes with associated solvents via the thermodynamic
analysis of experimental values of solvation Gibbs energies. The method is applied to solutions of different proton acceptors
in methanol. It is shown that the contribution of hydrogen bonding processes to the solvation Gibbs energy in methanol is
in most cases very different in magnitude from the formation Gibbs energy of equimolar complexes of the solute and methanol.
We demonstrate the need to include the contributions from solvophobic effects in investigating intermolecular interactions
in associated solvents by means of thermodynamic data. 相似文献
84.
Igor A. Sedov Michail A. Stolov Boris N. Solomonov 《Journal of Physical Organic Chemistry》2011,24(11):1088-1094
An approach is suggested to describe the solvophobic effects in various solvents, qualitatively and quantitatively. We analyzed the relationships between the Gibbs energies and enthalpies of solvation of alkanes in various solvents on the basis of existing experimental data. It is shown that for a large group of solvents, there is a linear correlation between the two quantities. Other solvents, primarily self‐associated, show deviations from this line. These deviations are always positive, leading to a decrease in solubility, and can be used as a measure of the strength of the solvophobic effects. It is also shown that the solvophobic effects is not the only factor determining the solubility, even for alkane solutes. The magnitudes of contributions of the solvophobic effect into the Gibbs energies of solvation of various compounds in monohydric alcohols are determined. These magnitudes are found to be linearly correlated with a characteristic molecular volume of a solute. The slope of correlation grows up with the concentration of hydrogen bonds in the liquid solvent. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
85.
Osipov V. V. Solomonov V. I. Podkin A. V. Shitov V. A. Tikhonov E. V. Korsakov A. S. 《Technical Physics》2021,66(1):149-154
Technical Physics - Nanopowders of two crystalline phases, magnesium–aluminum spinel (98 wt %), and cuprite (2 wt %) have been obtained by laser evaporation of a solid target, which... 相似文献
86.
The pulsed cathodoluminescence spectra of yttrium aluminum garnet and perovskite activated by neodymium are investigated at room temperature in the wavelength range 250–750 nm. The luminescence bands are identified, and all of them are assigned to Nd3+ transitions, including those from the doublet levels. 相似文献
87.
E. P. Kropotkina Yu. Yu. Kulikov V. G. Ryskin S. V. Solomonov 《Radiophysics and Quantum Electronics》2005,48(10-11):801-806
A number of features of the vertical distribution of stratospheric ozone over Moscow and Apatity were revealed by joint millimeter-wave observations of ozone emission lines at 142.2 and 101.7 GHz carried out at the P.N. Lebedev Physical Institute and the Institute of Applied Physics of the Russian Academy of Sciences in the winter of 2002/2003. The results of these observations illustrate the high efficiency of the radiophysical techniques for ozone layer monitoring from distant ground-based stations. The joint ozone observations at two points separated to a considerable distance are an important step toward the creation of the Russian network of observatories using ground-based millimeter-wave spectrometers. 相似文献
88.
V. V. Osipov V. I. Solomonov V. V. Platonov O. A. Snigireva V. V. Lisenkov M. G. Ivanov 《Laser Physics》2006,16(1):134-145
The dynamics and the spectral kinetic characteristics of the plume emerging in the vicinity of graphite targets, pressed pellets
consisting of zirconium oxide powder stabilized with yttrium (YSZ) and yttrium-aluminum oxides with neodymium (YAO:Nd), and
single-crystal YAG:Cr are studied. The targets are irradiated in air at room temperature using a repetitively pulsed CO2 laser with a wavelength of 10.6 μm, a peak power of up to 9 kW, a pulse energy of 1.69 J, and a pulse duration of 330 μs
at a level of 0.1. The plume propagates normally to the target surface at an angle of 45° relative to the laser radiation.
The spectral kinetic characteristics of the plume luminescence are discretely measured along the entire length. It is demonstrated
that the plumes of all targets (except for the single-crystal YAG:Cr) represent the flows of a weakly nonequilibrium gas plasma
with a temperature of 10 kK (graphite) and 3.1–4.7 kK (YSZ and YAO:Nd pressed pellets). The plume size is determined by the
peak power of the laser pulse. The luminescence of the two-atom radicals (C2 in graphite; ZrO and YO in YSZ; and YO, AlO, and NdO in YAO:Nd) dominates in all of the plumes. A single radical (YO) and
the spectral lines of atoms and atomic ions are observed in the YAG:Cr plume. A relatively high temperature of the graphite
plume is maintained owing to the energy of the exothermic reaction involving the association of carbon atoms and the energy
of the vibrationally excited molecules resulting from this reaction.
Original Text ? Astro, Ltd., 2006. 相似文献
89.
We have deposited relatively thick (∼60 nm) Ge layers on Br-passivated Si(111) substrates by thermal evaporation under high
vacuum conditions at room temperature. Ge has grown in a layer-plus-island mode although it is different from the Stranski-Krastanov
growth mode observed in epitaxial growth. Both the islands and the layer are nanocrystalline. This appears to be a consequence
of reduction of surface free energy of the Si(111) substrate by Br-passivation. The size distribution of the Ge nanoislands
has been determined. The Br-Si(111) substrates were prepared by a liquid treatment, which may not produce exactly reproducible
surfaces. Nevertheless, some basic features of the nanostructural island growth are reasonably reproducible, while there are
variations in the details of the island size distribution. 相似文献
90.