Перегляд за Автор "Soloshenko, Viktor I."

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  • Ескіз
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    Correlation between polarization and space charge phenomena in corona poled ferroelectric polymers
    (Одеський національний університет імені І. І. Мечникова, 2001) Fedosov, S. N.; Sergeeva, A. E.; Soloshenko, Viktor I.; Pissis, P.
    Polarization and space charge phenomena in ferroelectric polymers are interrelated due to existence of the depolarizing field. This field must be compensated anyhow in order to obtain stable residual polarization. It is shown that in corona poled PVDF this compensation is performed by injected and deeply trapped charges. Experimental evidence for the charge trapping has been obtained from the dynamics of apparent conductivity during poling. Irreversible decrease in the conductivity has been observed during the buildup of ferroelectric polarization independently on poling conditions. Appropriate calculations have shown that compensating charges are trapped not at the boundaries of crystallites, as usually believed, but in transition zones separating polarized parts of the volume from non-polarized ones.
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    Документ
    Dielectric relaxation of polystyrene doped with polar DR1 molecules
    (Одеський національний університет імені І. І. Мечникова, 2004) Fedosov, S. N.; Sergeeva, A. E.; Soloshenko, Viktor I.; Butenko, A. F.
    Four relaxation processes identified in polystyrene containing 2 wt % of DR1 chromophore were studied by the dielectric spectroscopy in the frequency range from 1 Hz to 1 MHz at constant temperatures from 30 to 130 °С and by thermally stimulated depolarization current measurements at sub-zero temperatures down to —160 °С. Hamon’s transformation of isothermal depolarization currents were also performed to give information on dielectric relaxation at infra-low frequencies. It has been found that distribution of relaxation times related to a relaxation becomes wider due to presence of dye molecules, while both the dielectric constant and the dielectric strength increase. Considerable narrowing of the loss peak was observed with increase of temperature indicating that the PS/DRI system is not the thermoreologically simple one and temperature-time superposition principle is not applicable above glass transition where the temperature dependence of the relaxation time obeys Williams—Landel—Ferry law. It has been found that Arrenius law is valid below glass transition.
  • Ескіз
    Документ
    PROCESSES of ELECTRICAL RELAXATION in PVDF-BaTiO3 COMPOSITES
    (Астропринт, 2006) Butenko, A. F.; Sergeeva, A. E.; Soloshenko, Viktor I.; Fedosov, S. N.; Бутенко, А. Ф.; Сергєєва, О. Є.; Солошенко, Віктор Іванович; Федосов, С. Н.; Бутенко, А. Ф.; Сергеева, А. Е.; Солошенко, Виктор Иванович; Федосов, С. Н.
    Thermally stimulated polarization and depolarization currents in composite materials made of polyvinylidenefluoride (PVDF) and BaTiO3 ceramics are studied experimentally. It has been found that the decrease in conductivity is related to the formation of the ferroelectric polarization. The information on parameters of the relaxation processes is obtained by the Relaxation Map Analysis (RMA) method. The experimental results are consistent with the model of the polari- zation development in ferroelectric polymers. Експериментально вивчені струми термостимульованої поляризації (ТСП) і деполяризації (ТСД) композиційних матеріалів на основі полівініліденфториду (ПВДФ) і порошку ВаТiО3. Встановлено, що зменшення провідності композитів пов'язано з формуванням в них сегнетоелектричної поляризації. Методом термічних вікон (МТВ) отримані дані про параметри релаксаційних процесів. Експериментальні результати знаходяться у відповідності з моделлю формування поляризації в сегнетоелектричних полімерах. Экспериментально изучены токи термостимулированной поляризации (ТСП) и деполяризации (ТСД) композиционных материалов на основе поливинилиденфторида (ПВДФ) и порошка ВаТiО3. Установлено, что уменьшение проводимости композитов связано с формированием в них сегнетоэлектрической поляризации. Методом термических окон (МТО) получены данные о параметрах релаксационных процессов. Экспериментальные результаты находятся в соответствии с моделью формирования поляризации в сегнетоэлектрических полимерах.
  • Ескіз
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    Substrate Crystallographic Orientation Effect on Photoluminescent Properties of Porous Silicon
    (Одеський національний університет імені І. І. Мечникова, 2005) Gevelyuk, Serhii A.; Doicho, Ihor K.; Mak, Vasyl T.; Soloshenko, Viktor I.; Lelechenko, V. P.; Zherditska, Y. R.
    Etching duration and anodic current density dependences of intensity and maximum position of the photoluminescence spectra of porous silicon layers obtained by anodization of silicon wafer are investigated. The sizes of silicon nanoclusters formed during the anodization procedure are estimated. It is shown that the dependence of formed clusters sizes on etching conditions for porous layers is different for various crystallographic orientations of the substrate. The model explaining this feature at various speeds of porous layer frontal advance deep into silicon substrate is offered. Presented results may be used for optimization of etching conditions in order to obtain the porous silicon layers having the preset parameters.