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991.
992.
Classification of three-dimensional periodic fluid flows 总被引:1,自引:0,他引:1
993.
G. M. Ter-Akopian A. V. Daniel A. S. Fomichev G. S. Popeko A. M. Rodin Yu. Ts. Oganessian J. H. Hamilton A. V. Ramayya J. Kormicki J. K. Hwang D. Fong P. Gore J. D. Cole M. Jandel J. Kliman L. Krupa J. O. Rasmussen I. Y. Lee A. O. Macchiavelli P. Fallon M. A. Stoyer R. Donangelo S. -C. Wu W. Greiner 《Physics of Atomic Nuclei》2004,67(10):1860-1865
Ternary fission of 252Cf was studied at Gammasphere using eight ΔE×E particle telescopes. Helium, beryllium, boron, and carbon light charged particles (LCPs) emitted with kinetic energy more than 9, 21, 26, and 32 MeV, respectively, were identified. The 3368-keV γ transition from the first 2+ excited state in 10Be was found and the population probability ratio N(2+)/N(0+) = 0.160 ± 0.025 was estimated. No evidence was found for 3368-keV γ rays emitted from a triple molecular state. For the first time, charge distributions are obtained for ternary fission fragments emitted with helium, beryllium, and carbon LCPs. 相似文献
994.
G. E. Abrosimova A. S. Aronin Yu. P. Kabanov D. V. Matveev V. V. Molokanov 《Physics of the Solid State》2004,46(5):885-890
The structure forming under controlled crystallization of a bulk Fe72Al5P10Ga2C6B4Si1 amorphous alloy has been studied using differential scanning calorimetry, transmission electron microscopy, and x-ray diffraction.
Crystallization of the alloy was established to result in the formation of a nanocrystalline structure consisting of three
phases. The domain structure and magnetic properties of amorphous and nanocrystalline samples were investigated using the
magnetooptic indicating film technique (MOIF) and a vibrating-sample magnetometer. The coercive force and the saturation magnetization
of the amorphous samples were found to be 1 Oe and 130 emu/g, respectively. It was shown that the formation of the nanocrystalline
structure entails a dramatic decrease in domain size (down to 1–4 μm) as compared to an amorphous sample (∼1 mm). Simultaneously,
a decrease in the saturation magnetization and a strong increase in the coercive force of the samples were observed.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 5, 2004, pp. 858–863.
Original Russian Text Copyright ? 2004 by Abrosimova, Aronin, Kabanov, Matveev, Molokanov. 相似文献
995.
Crystal and magnetic structure of the Sm0.55Sr0.45MnO3 and (Nd0.545Tb0.455)0.55Sr0.45MnO3 manganites
A. I. Kurbakov V. A. Trounov A. M. Balagurov V. Yu. Pomyakushin D. V. Sheptyakov O. Yu. Gorbenko A. R. Kaul 《Physics of the Solid State》2004,46(9):1704-1710
Neutron diffraction data are presented for the 152Sm0.55Sr0.45MnO3 (SSM) and (Nd0.545Tb0.455)0.55Sr0.45MnO3 (NTSM) manganites. The Nd and Tb contents in the latter composition are such that the average radius of the A cation 〈r
A
〉 in these two compounds is the same. The difference in local tolerance factor fluctuations was about 10%. It was found that
replacement of a rare-earth cation with leaving 〈r
A
〉 unchanged has practically no effect on the structural and transport properties; indeed, both compounds are metals at low
temperatures, have the same crystal structure from liquid-helium to room temperature, and exhibit the same pattern of structural
distortions at the onset of magnetic ordering. Magnetic moments of Mn ions in both compositions are ferromagnetically ordered
at low temperatures, with T
C
=122 and 90 K for the SSM and NTSM, respectively. Below 80 K, the rare-earth cation moments in NTSM undergo additional ordering.
In contrast to compositions that are close in Sr concentration (x
Sr=0.4, 0.5), which feature a phase-separated state with a mixture of the ferromagnetic metallic and antiferromagnetic insulator
phases, the ground state of both studied compositions with x
Sr=0.45 is uniformly ferromagnetic and metallic.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 9, 2004, pp. 1650–1656.
Original Russian Text Copyright ? 2004 by Kurbakov, Trounov, Balagurov, Pomyakushin, Sheptyakov, Gorbenko, Kaul. 相似文献
996.
B. K. Kardashev Yu. A. Burenkov B. I. Smirnov A. R. de Arellano-Lopez J. Martinez-Fernandez F. M. Varela-Feria 《Physics of the Solid State》2004,46(10):1873-1877
The effect of the vibration strain amplitude on the Young modulus and ultrasonic absorption (internal friction) in biomorphic SiC ceramics is investigated in the temperature range 116–296 K. The biomorphic SiC ceramics is prepared through pyrolysis of eucalyptus with subsequent infiltration of silicon. It is demonstrated that the vibration loading of samples in air and under vacuum is accompanied by a number of unexpected effects. The behavior of the studied ceramics is governed by at least two mechanisms, which, to a large extent, are responsible for the elastic and inelastic properties of the material. One mechanism is associated with the adsorption-desorption of environmental molecules (hypothetically, owing to the presence of pores and residual carbon), and the other mechanism involves microplastic deformation due to the motion of dislocations or other (similar) structural units. 相似文献
997.
The crystallization of nickel nanoclusters is investigated using a molecular dynamics simulation with tight-binding potentials. The formation of a cluster structure depends on the cooling conditions. Slow cooling results in the formation of a face-centered cubic structure, whereas fast cooling, according to the data obtained in 40% of the simulation experiments, leads to the formation of an icosahedral structure. The molecular dynamics simulation experiments demonstrate the possibility of controlling the formation of a structure of nickel nanoclusters during crystallization. 相似文献
998.
In terms of the standard thermodynamic approach (the Debye-Grüneisen model of solid and the Landau theory of second-order phase transitions), approximate conditions providing the constancy of the volumetric thermal expansion coefficient (the Invar effect) and of the bulk modulus (the Ellinvar effect) of a ferromagnet are established. Conditions under which a ferromagnet may exhibit Invar and Ellinvar properties simultaneously are found. Interaction between the magnetic, phonon, and electron subsystems of a ferromagnet is shown to be a crucial factor in the occurrence of the Invar and Ellinvar effects. 相似文献
999.
Yu. A. Morozov 《Technical Physics》2004,49(5):603-608
The effect of random frequency fluctuations due to spontaneous emission and generation-recombination noise on the shape of
the emission line of a semiconductor laser with pseudorandom modulation of the pump current is studied numerically. The roles
of spontaneous emission and chirp modulation in forming the lasing spectrum are separated out. The dependence of the output
spectral characteristics of the laser on the parameters and type of modulation is analyzed. 相似文献
1000.