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991.
A. González Arias A. del Cueto J. M. Muñoz C. de Francisco L. Torres A. G. Flores M. Zazo J. Iñiguez 《Applied Physics A: Materials Science & Processing》1996,63(5):453-459
Silica may dissolve up to about 0.05 wt% in an iron excess NiZnCo spinel matrix, affecting noticeably the magnetic properties at low and high values of the applied field. The initial permeability is reduced by about 50% with the addition of only 0.1 % SiO2, while the coercivity almost triples, without noticeable changes in porosity or grain distribution. The vacancy and Fe2+ content of the sintered material also show a considerable change. The energy associated to the transformation Fe3+ Fe2+ for the samples without SiO2 was found to be 0.41–0.42 eV, while for the samples with SiO2 additions it decreased to 0.26 eV. The changes in magnetic properties are thought to be caused, more than because of the mentioned changes in ion distribution, by the stresses and defects created in the lattice due to the very small size of the Si4+ ion, which substitutes Fe3+ ions in tetrahedral sites. The transition Fe3+ Fe2+ seems to take place exclusively in the octahedral sites. 相似文献
992.
A. Kučírková K. Navrátil L. Pajasová V. Vorlíček 《Applied Physics A: Materials Science & Processing》1996,63(5):495-503
Optical properties of semi-insulating polycrystalline silicon (SIPOS) films were investigated over the wide region of wavelengths. The vibrational modes of Si-O-Si and Si-Si bonds were studied by IR and Raman spectroscopy. A pronounced effect of oxygen content on the measured spectra was observed. Optical constants of SIPOS films have been compared with those of amorphous silicon and glassy silicon dioxide and their values have been successfully interpreted in terms of the theory of effective medium. The results have shown that the amorphous character prevails in the as-deposited SIPOS films. 相似文献
993.
The anisotropic homogeneous 3 is isometrically globally embedded into a nine-dimensional Euclidean or pseudo-Euclidean space. In a special case the Euclidean space is six-dimensional. The space-sections of the anti-Mach metric appear as a submanifold of theE
9. We obtain also the isometric embedding ofSO(3) with its natural Killing metric. 相似文献
994.
In the framework of noncommutative geometry we describe spinor fields with nonvanishing winding number on a truncated (fuzzy) sphere. The corresponding field theory actions conserve all basic symmetries of the standard commutative version (space isometries and global chiral symmetry), but due to the noncommutativity of the space the fields are regularized and they contain only a finite number of modes.Part of the Project P8916-PHY of the Fonds zur Förderung der wissenschaftlichen Forschung in Österreich. 相似文献
995.
Studying the algebraic structure of the YangiansY(sl(2)), andY(sl(3)) we present their boson realizations. In the case ofY(sl(2)) we give the realization by using 1-canonical boson pair and two parameters and in theY(sl(3)) with 2-canonical boson pairs, two parameters and subalgebrasl(2). Substituting the realization ofU(sl(2)), we can obtain the pure boson realization by 3-canonical pairs and three parameters.Presented at the 4th Colloquium Quantum Groups and Integrable Systems, Prague, 22–24 June 1995. 相似文献
996.
R. S. Dunne A. J. Macfarlane J. A. de Azcárraga J. C. Pérez Bueno 《Czechoslovak Journal of Physics》1996,46(12):1235-1242
Theq-calculus for genericq is developed and related to the deformed oscillator of parameterq
1/2. By passing with care to the limit in whichq is a root of unity, one uncovers the full algebraic structure ofZ
n
-graded fractional supersymmetry and its natural representation.Presented at the 5th International Colloquium on Quantum Groups: Quantum Groups and Integrable Systems, Prague, 20–22 June 1996.This paper describes research supported in part by E.P.S.R.C and P.P.A.R.C. (UK) and by the C.I.C.Y.T (Spain). J.C.P.B. wishes to acknowledge an FPI grant from the CSIC and the Spanish Ministry of Education and Science. 相似文献
997.
We apply the pseudoextension mechanism, which in the undeformed case gives the centrally extended Galilei group {ie137-02} as a contraction of a trivial extensionP×U(1) of the Poincaré group, to the case of the-Poincaré algebra. As a result, the four-dimensional {ie137-03}-deformed extended Galilei algebra is obtained.Presented at the 4th Colloquium Quantum Groups and Integrable Systems, Prague, 22–24 June 1995. 相似文献
998.
Precise values of energies and widths of low-lying resonances in some rare-gas atom systems (Ar-Ar, Ne-Kr, Ne-Xe) are reported. 相似文献
999.
1000.