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21.
A. I. Kosse Yu. E. Kuzovlev G. G. Levchenko Yu. V. Medvedev A. Yu. Prokhorov V. A. Khokhlov P. N. Mikheenko 《JETP Letters》2003,78(6):379-383
A model is proposed for vortex pinning in a superconducting film with a rough surface. The model relates the critical current to the steepness of the surface relief and, at a high vortex concentration, to the distance between neighboring steepness maxima on the paths of vortex motion. The dependence of the critical current density on the thickness of a high-Tc superconducting film is measured in a weak magnetic field. Its behavior can be explained by the pinning at the stepped surface relief. 相似文献
22.
V. A. Khokhlov V. V. Krzhizhanovskii A. Yu. Prokhorov V. F. Drobot’ko A. V. Klimov G. G. Levchenko 《Physics of the Solid State》2001,43(9):1603-1610
The diamagnetic response of a laser-deposited YBCO film was studied in weak exciting magnetic fields H ac =H 0sinωt (H 0=2–500 mOe, ω/2π=1–30 kHz). An analysis of the experimentally measured diamagnetic response showed evidence of a ring character of the electric field flowing in the sample at small H 0 values. The plots of T m (the temperature of maximum dissipative losses χ″1) versus H 0 measured at various frequencies showed the existence of a certain critical field strength H*(ω) at which the (1?T m /T c ) versus H 0 2/3 plots exhibit a break. A logarithmic dependence of T m on the frequency ω of the exciting field H ac is reliably valid only in the region of (ω/2π)>5 kHz. Verification of the scaling relationship showed that this relationship is valid (to within the experimental accuracy) for the frequencies ω above 5 kHz and the field amplitudes H 0>H*(ω). However, the exponent n in the scaling relationship under consideration is not correlated with the exponent n in the power relationship describing the current-voltage characteristic. 相似文献
23.
A study of the effect of hydrostatic pressure and temperature on the EPR spectrum of the Mn2+ ion in Zn(BF4)2 · 6H2O is reported. The break in the temperature dependence of the b 2 0 parameter at 196 K is evidence of the existence of a phase transition accompanied by a change in the thermal expansion coefficient. It is shown that pressure considerably affects the spectral parameters by reducing the axial parameter b 2 0 and increasing the cubic one, b 4 0 . At 9 kbar, the b 2 0 parameter is temperature independent. A comparison of the pressure dependences of the spectra of Zn(BF4)2 · 6H2O, ZnSiF6 · 6H2O, ZnTiF6 · 6H2O, and MgSiF2 · 6H2O crystals suggests equal hydrogen-bond lengths in these compounds. A ligand hyperfine structure has been detected, which originates from the Zeeman interaction with the proton nuclei surrounding Mn2+ and manifests itself in the formation of satellites at each EPR line, their separation being proportional to the magnetic field. The nonlinear pressure dependence of the linewidth is related to the structural features of the crystal under study. 相似文献
24.
I. A. Prokhorov Yu. A. Serebryakov E. N. Korobeinikova B. G. Zakharov V. V. Ratnikov I. L. Shul’pina 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(3):255-259
Structural features of GaSb(Si) single crystals grown under various heat and mass transfer conditions were studied by x-ray topography and by double- and triple-crystal diffractometry. It was shown that a decrease in the convective flow intensity during crystal growth by the vertical Bridgman method with axisymmetric upper heat supply in comparison with the Czochralski method eliminates growth striations (caused by microsegregation) and improves the uniformity of electrical parameters of materials. According to triple-crystal x-ray diffractometry data, the increased density of structural defects observed in some crystal regions causes significant lattice distortions, which makes an additional contribution to crystal inhomogeneity. Some specific features in x-ray topography images of growth striations, caused by a high silicon concentration and a dopant state deviation from an ideal substitutional solid solution, were revealed. 相似文献
25.
I. A. Prokhorov B. G. Zakharov V. E. Asadchikov A. V. Butashin B. S. Roshchin A. L. Tolstikhina M. L. Zanaveskin Yu. V. Grishchenko A. E. Muslimov I. V. Yakimchuk Yu. O. Volkov V. M. Kanevskii E. O. Tikhonov 《Crystallography Reports》2011,56(3):456-462
The possibility of characterizing a number of practically important parameters of sapphire substrates by X-ray methods is substantiated. These parameters include wafer bending, traces of an incompletely removed damaged layer that formed as a result of mechanical treatment (scratches and marks), surface roughness, damaged layer thickness, and the specific features of the substrate real structure. The features of the real structure of single-crystal sapphire substrates were investigated by nondestructive methods of double-crystal X-ray diffraction and plane-wave X-ray topography. The surface relief of the substrates was investigated by atomic force microscopy and X-ray scattering. The use of supplementing analytical methods yields the most complete information about the structural inhomogeneities and state of crystal surface, which is extremely important for optimizing the technology of substrate preparation for epitaxy. 相似文献
26.
27.
Mathematical Notes - In this paper, we study the continuity properties of the solution to a boundary-value problem for the radiation transfer equation with generalized conjugation conditions at the... 相似文献
28.
J. Betzabe Gonzlez‐campos Evgen Prokhorov Gabriel Luna‐Brcenas A. Mendoza Galvn Isaac C. Sanchez Sergio M. Nuo Donlucas B. Garcia‐Gaitan Yuriy Kovalenko 《Journal of Polymer Science.Polymer Physics》2009,47(9):932-943
Relaxations in chitin have been investigated in the temperature range 298–523 K using impedance spectroscopy in the frequency range 10−1–108 Hz. The objective was to detect a glass‐transition temperature for this naturally occurring, semicrystalline polysaccharide. The impedance study was complemented with X‐ray diffraction, thermogravimetric, and differential scanning calorimetry measurements. Preliminary impedance data treatment includes the subtraction of the dc conductivity contribution, the exclusion of contact and interfacial polarization effects, and obtaining a condition of minimum moisture content for further analysis. When all these aspects are taken into account, two relaxations are clearly revealed in the impedance data. For the first time, evidence is presented for a relaxation process, which exhibits a non‐Arrhenius temperature dependence, in dry α‐chitin (∼0.1% moisture content), and likely represents the primary α‐relaxation. This evidence suggests a glass transition temperature for chitin of 335 ± 10 K estimated on the basis of the temperature dependence of the conductivity and of the relaxation time. A second relaxation in dry α‐chitin, not previously reported in the literature, is observed from 353 K to the onset of thermal degradation (∼483 K) and is identified as the σ‐relaxation often associated with proton mobility. It exhibits a normal Arrhenius‐type temperature dependence with activation energy of 113 ± 3 kJ/mol. The latter has not been previously reported in the literature. A high frequency secondary β‐relaxation is also observed with Arrhenius activation energy of 45 ± 1 kJ/mol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 932–943, 2009 相似文献
29.
V. A. Volkov V. R. Musin U. G. Pirumov M. B. Prokhorov V. Yu. Strel'tsov 《Fluid Dynamics》1993,28(6):825-832
A closed mathematical model of the flow of a two-phase mixture consisting of evaporating water droplets and a chemically reacting multicomponent gas is described. The effect of the real droplet heating and evaporationkinetics on the gas-phase chemical reactions in a mixture of combustion products is studied within the framework of this model.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.6, pp. 96–106, November–December, 1993. 相似文献
30.
In the last few decades, significant progress has been achieved in the development of generators and detectors of terahertz
radiation (at frequencies in the range from ≈300 GHz to ≈3 THz). Different terahertz spectroscopic techniques have been widely
used now in investigating semiconductors, superconductors, molecular magnets, multiferroics, metamaterials, and other promising
objects. It has been demonstrated that terahertz spectroscopy offers wide but not completely realized possibilities for studying
quantum phase transitions in electron-correlated systems. 相似文献