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Straumal B.B.,National University of Science and Technology "MISIS" | Kogtenkova O.A.,RAS Institute of Solid State Physics | Kolesnikova K.I.,National University of Science and Technology "MISIS" | Straumal A.B.,National University of Science and Technology "MISIS" | And 2 more authors.
JETP Letters | Year: 2014

The reversible wetting of grain boundaries by the second solid phase in the copper-indium system has been observed. With an increase in the temperature, the contact angle θ between the (Cu)/(Cu) grain boundary in a Cu-based solid solution based and particles of the δ-phase (Cu70In30) decreases gradually. Above TW = 370°C, the first (Cu)/(Cu) grain boundaries completely “wetted” by the δ phase appear in Cu-In polycrystals. In other words, the δ phase forms continuous layers along grain boundaries and θ = 0. At 440°C, the fraction of completely wetted grain boundaries reaches a maximum (93%), whereas the average contact angle reaches a minimum (θ = 2°). With a further increase in the temperature, the fraction of completely wetted grain boundaries decreases and vanishes again at TDW = 520°C. This phenomenon can be explained by an anomalous shape of the solubility limit curve of indium in a solid solution (Cu). © 2014, Pleiades Publishing, Inc.


Bozhko S.I.,Trinity College Dublin | Levchenko E.A.,Astrakhan State University | Semenov V.N.,RAS Institute of Solid State Physics | Bulatov M.F.,State Scientific Research and Design Institute of Rare Metal Industry | Shvets I.V.,Trinity College Dublin
Journal of Experimental and Theoretical Physics | Year: 2015

The rotation dynamics of C60 molecules in monolayer fullerene films grown on the WO2/W(110) surface is studied by scanning tunneling microscopy. The formation of molecule clusters, which have a high libron vibration amplitude, is detected near the rotational phase transition temperature. The energy parameters that determine a change in the molecule orientation, namely, the energy difference between the nearest minima of the C60 molecule energy (30 meV) as a function of the molecule orientation and the potential barrier between them (610 meV), are determined. The results are discussed in terms of the mean-field approximation. © 2015, Pleiades Publishing, Inc.


Polyakov A.Ya.,State Scientific Research and Design Institute of Rare Metal Industry | Smirnov N.B.,State Scientific Research and Design Institute of Rare Metal Industry | Govorkov A.V.,State Scientific Research and Design Institute of Rare Metal Industry | Belogorokhov I.A.,State Scientific Research and Design Institute of Rare Metal Industry | And 8 more authors.
Russian Microelectronics | Year: 2011

The structural characteristics and electrical properties of bulk aluminum nitride crystals grown by sublimation and used as substrates for light emitting diode (LED) structures and AlGaN/GaN field effect transistors were studied. The crystalline perfection was assessed by selec- tive chemical etching and by X-ray diffraction techniques. Electrical and optical properties were investigated using the temperature dependence of conductivity, admittance spectroscopy, high- temperature/low-frequency capacitance voltage measurements and by photoinduced transient cur- rent spectroscopy (PICTS), microcathodoluminescence (MCL) spectra and MCL imaging tech- niques. It was established that the studied samples were single crystals with a large grain substructure, with characteristic grain size of several hundred microns and a dislocation density of 10 2-10 4 cm -2 inside the grains. The electrical characteristics of the crystals were governed by the compensation of residual donors with a level near E c-0.3 eV by deep centers with activation energy of 0.7 eV, both centers manifesting themselves in the temperature dependence of conductivity and in admittance spectra. In addition, deep cen- ters responsible for the luminescence band with the peak energy of 3.3 eV and associated with low-angle grain boundaries were also observed. © Pleiades Publishing, Ltd., 2011.

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