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Thirty laterally fluorosubstituted new 4-isothiocyanato-, 4-cyano-, 4-fluoro- and 4-(1,1,1-trifluorometoxy)-4′-(4-alkylphenyl)tolanes have been synthesised and their phase transition temperatures and enthalpies and electric permittivity have been measured. These data have been analysed together with data for earlier prepared similar compounds and with recently prepared analogously substituted 4″-alkyl-terphenyls. It was shown that some di-, tri- and tetra-fluorosubstituted 4-isothiocyanato- and 4-cyano-4′-(4-alkylphenyltolanes) are very useful components for the formulation of high birefringence (Δn up to 0.5 measured at 589 nm) and large temperature range nematic mixtures for photonic applications, especially in the infra-red, GHz and THz range of electromagnetic radiation. Three ways of formulation of high birefringence mixtures were proposed. 相似文献
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International Applied Mechanics - The two-dimensional problem of electroelasticity for a piezoelectric half-space with cylindrical cavities and plane cracks under a distant electric field is... 相似文献
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G. N. Churilov I. V. Osipova Ye. V. Tomashevich G. A. Glushchenko A. S. Fedorov Z. I. Popov N. V. Bulina S. N. Vereshchagin A. M. Zhizhaev A. V. Cherepakhin 《Journal of Experimental and Theoretical Physics》2011,113(6):1057-1062
Composite nanoparticles consisting of magnesium, nickel, and carbon atoms are studied both theoretically and experimentally.
The calculations performed in terms of the density functional theory show that the jump frequency of hydrogen atoms in nickel-containing
magnesium hydride increases substantially near impurity nickel atoms; as a result, the rate of hydrogen absorption by magnesium
also increases. Nickel on the magnesium surface is shown to be absorbed via an island growth mechanism. Composite Mg-C, Ni-C,
and Mg-Ni-C powders are produced by plasmachemical synthesis in a carbon-helium plasma stream. Hydrogen is introduced into
a chamber during synthesis. It is found by X-ray photoelectron spectroscopy and thermogravimetric analysis that, among these
three composites, only Mg-Ni-C contains magnesium fixed in the MgH2 compound. The process of such “ultrarapid” hydrogenation of magnesium, which occurs in the time of formation of composite
nanoparticles, can be explained by the catalytic action of nickel, which is enhanced by a high temperature. Scanning electron
microscopy micrographs demonstrate the dynamics of the dehydrogenation of Mg-Ni-C composite nanoparticles in heating by an
electron beam. 相似文献
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R. P. Parkhomenko V. A. Glushchenko M. P. Yakubenya Yu. A. Grigor'ev A. A. Potrepalov 《Russian Physics Journal》1988,31(7):595-598
A study was made of the volt-ampere characteristics of Pd-GaAs Schottky barriers in relation to the defectiveness of the gallium arsenide. The defect content of the material was checked metallographically and by the method of x-ray topography. Single crystals of GaAs doped with Ge, Ge + Sb, and Ge + In were studied. Here, the electron concentration was (1–4) · 1015 cm–3, and mean dislocation density ranged from 4·104 to 2·102 cm–2. The defectiveness of the material was altered by the introduction of different concentrations of isovalent impurities. It was shown that for diodes produced by the same technology, the manifestation of low-temperature VAC anomalies and the current mechanism are determined by structural features of the semiconductor (by dislocations and microdefects).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 90–95, July, 1988. 相似文献
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