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Документ Absorption spectra of layered ZnI2 and K2ZnI4 compounds intercalated by СО2(Institute for Single Crystals, 2009) Yunakova, O.N.; Miloslavsky, V.K.; Kovalenko, E.N.; Makovetsky, E.D.The absorption spectra of thin films of ZnI2 and K2ZnI4 layered compounds intercalated with СО2 molecules have been investigated in temperature interval from 90 to 240 K. It is found that the intercalation results in high-frequency shift of exciton bands and their broadening. Considering the structure of ZnI2 and K2ZnI4 crystal lattices, the most probable positions of СО2 molecules in spacings between layers of compounds have been established. It is shown that, in K2ZnI4 compound, unlike ZnI2, there are two position types of intercalant molecules with molecular axes of different orientation relative to the compound crystallographic axes.Документ Comparison of refractive indices of amorphous and crystalline As2S3(Institute for Single Crystals, 2009) Miloslavsky, V.K.; Makovetsky, E.D.Method to calculate refractive index and transparency range dispersion of amorphous As2S3 is proposed. It is based on effective dielectric permittivity models for porous composite media, comparison of glass and crystal density and use of data on refractive index of the crystal. It is shown that the best agreement of calculated and experimental values of refractive index of glass is obtained within the wavelength interval 460-670 nm when using Lorenz-Lorentz formula. It is established that As2S3 glasses possess pores with filling factor q=0.057 submerged to isotropic matrix with approximately two times smaller porosity (qM=0.031).Документ Condensation mechanism of AgCl and NaCl island films on a nickel substrate(STC “Institute for Single Crystals”, 2011) Gladkikh, N.T.; Dukarov, S.V.; Sukhov, V.N.; Churilov, I.G.The paper presents the results of exploring the temperature range of formation and thermal stability of the AgCl and NaCl liquid phase in the islands condensed to Ni substrate in vacuum. It is established that the change of the mechanism of condensation from vapour-crystal to vapour-liquid at the deposition of the films of these chemical compounds is observed when the temperatures of the substrate is lower than their melting temperature. The values of supercooling at crystallization on the nickel substrate of island films of substances under study are determined, which make 95 K for AgCl and 369 K for NaCl, respectively. It is shown that the method of studying supercoolings which uses vacuum condensates is applicable to a broad range of substances. Приводятся результаты исследований температурного интервала образования и температурной устойчивости жидкой фазы в островковых вакуумных конденсатах хлоридов серебра и натрия на никелевых подложках. Установлено, что смена механизма конденсации от пар-кристалл к пар-жидкость при осаждении пленок этих химических соединений наблюдается при температурах подложки ниже температуры их плавления. Определены величины переохлаждений при кристаллизации островковых пленок исследуемых веществ на никелевой подложке, которые составили 95 и 369 К для AgCl и NaCl, соответственно. Показано, что метод изучения переохлаждений с использованием вакуумных конденсатов пригоден для широкого класса веществ. Наводяться результати досліджень температурного інтервалу утворення та температурної стійкості рідкої фази в острівцевих вакуумних конденсатах хлоридів срібла і натрію на нікелевих підкладках. Встановлено, що зміна механізму конденсації від пара-кристал до пара-рідина при осадженні плівок цих хімічних сполук спостерігається при температурах підкладки нижче температури їх плавлення. Визначено величини переохолоджень при кристалізації острівцевих плівок досліджуваних речовин на нікелевій підкладці, які склали 95 та 369 К для AgCl і NaCl, відповідно. Показано, що метод вивчення переохолоджень з використанням вакуумних конденсатів придатний для широкого класу речовин.Документ Crossover from dirty to clean superconducting limit in dc magnetron-sputtered thin Nb films(Elsevier, 2012-05-11) Dobrovolskiy, O.V.; Huth, M.High-quality Nb (110) thin films with residual resistance ratios up to 60 and critical temperatures Tc≈9.27 K have been prepared by conventional dc-magnetron sputtering on α-Al2O3 by careful selection of the sputtering conditions. This allowed for a systematic study of the influence of the growth rate on the structural quality and the superconducting properties of the films. The optimized growth conditions were revealed at the substrate temperature Ts=850 °C, Ar pressure Ps=0.4 Pa, and the growth rate g≃0.5 nm/s. The results of the films' structural characterization by X-ray diffraction, reflection high-energy electron diffraction, and atomic force microscopy are presented. In terms of the electron mean free path l and the superconducting coherence length ξ, deduced from the magneto-resistivity data, the clean superconducting limit (l>ξ) is realized in the high-purity films. For comparison, in impure Nb films sputtered at room temperature while keeping the rest of the sputtering parameters unvaried, the opposite dirty limit (ξ≳l) ensues. The merits of these findings are discussed in the context of the demands of present-day fluxonics devices regarding the normal-state and flux-flow properties of superconducting films they are made of.Документ Current-controlled filter on superconducting films with a tilted washboard pinning potential(Elsevier, 2012) Dobrovolskiy, O.V.; Shklovskij, V.A.; Huth, M.The influence of an ac current of arbitrary amplitude and frequency on the mixed-state dc-voltage-ac-drive tiltingratchet response of a superconducting film with uniaxial cosine pinning potential at finite temperature is theoretically investigated. The results are obtained in the single-vortex approximation, within the frame of an exact solution of the Langevin equation for non-interacting vortices. Both experimentally achievable, the dc ratchet response and absorbed ac power are predicted to demonstrate a pronounced filter-like behavior at microwave frequencies. Based on our findings, we propose a cut-off filter and discuss its operating curves as functions of the driving parameters, i.e, ac amplitude, frequency, and dc bias. The predicted results can be examined, e.g, on superconducting films with a washboard pinning potential landscape.Документ Cорбция водорода нанопористыми углеродными материалами(Харківський національний університет імені В. Н. Каразіна, 2014-04-22) Хлыстюк, М.В.Документ Determination of coordinate dependence of a pinning potential from a microwave experiment with vortices(LOW TEMPERATURE PHYSICS, 2013-02) Dobrovolskiy, O.V.; V. A. Shklovskij, V.A.The measurement of the complex impedance response accompanied by power absorption P(x) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the pinning potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T¼0K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(xjj0) measured at subcritical dc currents 0Документ Dispersion of refractive index in thin films CdI2 and ZnI2(Institute for Single Crystals, 2010) Yunakova, O.N.; Miloslavsky, V.K.; Kovalenko, E.N.The refractive index dispersion in thin CdI2 and ZnI2 films has been measured in the wavelength interval 300-1000 nm and processed using the monooscillator model ageeing well with experimental data. The optical permittivity e_unlim of both compounds has been determined using the found parameters of this model, the optical permittivity data have been used in the further analysis of exciton states in CdI2 and ZnI2, in particular, for determination of 1s exciton radius. The found a_ex values are close to the unit cell parameters of the compounds, thus indicating that the excitons in two compounds belong to excitons of the intermediate electron-hole band.Документ Effect of an electric field on coalescence in gallium island films(1990) Chizhik, S.P.; Dukarov, S.V.; Gladkikh, N.T.; Grigoryeva, L.K.It was found that the external longitudinal electric field stimulates coalescence in gallium island films with different particle sizes on a poorly conducting carbon substrate, which can be considered as a manifestation of the particle mutual-charging effect. - - - - - - - - - - - - - - - Установлено, что внешнее продольное электрическое поле стимулирует процесс коалесценции в островковых пленках галлия с различным размером частиц на слабопроводящей углеродной подложке, что может рассматриваться как проявление эффекта взаимного заряжения частиц.Документ Effect of condensation conditions on phase formation in thin two-layer Ni/GaAs films(STC “Institute for Single Crystals”, 1998) Grebennik, I.P.; Gladkikh, N.T.; Dukarov, S.V.The temperature and structure state of substrate (NaCl poly- and single crystals) are shown to influence the structure of phases formed as a result of interaction between Ni and GaAs layers. In films on polycrystal substrates, polycrystal phases with structures similar to the γ-, γ'-, NiAs, Ni3Ga4 phases in Ni-Ga and Ni-As systems are formed besides the amorphous one. Single crystal substrate exerts an orienting influence resulting in the energetically favourable growth of the hexagonal phase of the triple system with parameters aγ''= aγ', cγ'' = 2cγ'. . . . . . . . . . . . . . . . . . . Показано, что температура и структурное состояние подложки (поли- и монокристаллов NaCl) оказывает влияние на структуру фаз, образующихся при взаимодействии слоев Ni и GaAs. На поликристаллических подложках в пленках, наряду с аморфной, образуются поликристаллические фазы, структура которых подобна фазам γ-, γ'-, NiAs, Ni3Ga4, в системах Ni-Ga, Ni-As. Монокристаллическая подложка оказывает ориентирующее действе и приводит к энергетически более выгодному росту гексагональной фазы тройной системы с параметрами aγ''= aγ', cγ'' = 2cγ'.Документ Effect of temperature on the pores growth in the polycrystalline films of fusible metals(ННЦ "Харьковский физико-технический институт", 2014) Dukarov, S.V.; Petrushenko, S.I.; Sukhov, V.N.; Churilov, I.G.The paper presents the results of study through porosity in polycrystalline films of lead, tin and indium deposited on amorphous carbon substrate. It is established that the heating of film exponentially increases of the average size of through pores and do not leads to an increase of their concentration, which is practically independent of the temperature until to the melting point. We have determined the activation energy of the surface self in the films of these metals. Приведены результаты исследования сквозной пористости в поликристаллических плёнках свинца, олова и индия, напыленных на аморфные углеродные подложки. Установлено, что нагрев плёнок вызывает экспоненциальное увеличение среднего размера сквозных пор и не приводит к увеличению их концентрации, которая практически не зависит от температуры вплоть до температуры плавления. Определена энергия активации поверхностной самодиффузии в плёнках этих металлов.Документ Electrical transport and pinning properties of Nb thin films patterned with focused ion beam-milled washboard nanostructures(New J. Phys., 2012-11-22) Dobrovolskiy, O.V.; Begun, E.; Huth, M.A careful analysis of the magneto-transport properties of epitaxial nanostructured Nb thin films in the normal and the mixed state is performed. The nanopatterns were prepared by focused ion beam (FIB) milling. They provide a washboard-like pinning potential landscape for vortices in the mixed state and simultaneously cause a resistivity anisotropy in the normal state. Two matching magnetic fields for the vortex lattice with the underlying nanostructures have been observed. By applying these fields, the most likely pinning sites along which the flux lines move through the samples have been selected. By this, either the background isotropic pinning of the pristine film or the enhanced isotropic pinning originating from the nanoprocessing have been probed. Via an Arrhenius analysis of the resistivity data the pinning activation energies for three vortex lattice parameters have been quantified. The changes in the electrical transport and the pinning properties have been correlated with the results of the microstructural and topographical characterization of the FIB-patterned samples. Accordingly, along with the surface processing, FIB milling has been found to alter the material composition and the degree of disorder in as-grown films. The obtained results provide further insight into the pinning mechanisms at work in FIB-nanopatterned superconductors, e.g. for fluxonic applications.Документ Electron spin waves in nonmagnetic conductors with resonance states of electrons(Karazin Kharkiv National University, 2008) Ermolaev, A.M.; Ulyanov, N.V.Results of theoretical investigation of properties of spin waves in nonmagnetic conductors and heterostructures with 2D electron gas in presence of impurity atoms be able to localize electrons are listed in monograph.Документ Electronographic investigation of the temperature effect on the phase formation in thin double-layer Ni/GaAs films(1998) Gladkikh, N.T.; Grebennik, I.P.; Dukarov, S.V.The results of an electronographic investigation of the Ni—GaAs double-layer films phase composition depending on temperature at condensation of Ni at GaAs are presented. The structure and number of the phases being formed have been shown to depend both on ther-mal conditions at interaction of the Ni and GaAs layers and on the Ni to GaAs layer mass ratio: mNi//mGaAs = (0.5; 1.2).Документ Features of gallium spreading over surfaces of Ag - Au - Ga thin films(STC “Institute for Single Crystals”, 1997) Andronov, V.M.; Dukarov, S.V.; Grebennik, I.P.Linear spread of gallium over thin films of Ag-Au-Ga ternary alloys with continously varying concentrations along quasi-binary sections of the ternary diagram has been studied. The observed concentration dependence of the spread zone size is attributed to structural changes occurring in alloys and resulting in an unmonotonous dependence of the spread motive force on the alloy composition. . . . . . . . . . . . . . . . . . . . . . . . . Исследовано линейное растекание галлия по поверхности тонких пленок тройных сплавов серебро-золото-галлий с непрерывно изменяющейся концентрацией вдоль квазибинарных сечений тройной диаграммы. Обнаруженная немотонная зависимость размера зоны растекания от концентрации объясняется влиянием происходящих в сплавах структурных изменений, приводящих к немонотонной зависимости движущей силы растекания от состава сплава.Документ Fluxonic Properties of Vortices in a Washboard Pinning Potential Fabricated by Focused Particle Beam Techniques(Proceedings of the International Congress on Advances in Applied Physics and Materials Science, Antalya 2011, 2012) Dobrovolskiy, O.V.; Huth, M.; Shklovskij V.A.A challenging aspect of the usage of patterned nanostructures relates to the development of superconducting devices operating with the Abrikosov vortices in some pinning potential. To provide such a potential we have used thin epitaxial films of Nb with washboard-like nanostructures in the form of grooves or Co stripes. The nanostructures were prepared by focused ion beam milling or focused electron beam induced deposition, respectively. The results of transport measurements affirm the existence of two fluxonic effects, the guided vortex motion and the vortex ratchet effect, both invoked by the nanostructuring. In particular, the effects represent the basis for the development of advanced fluxonic devices using a directional or orientational control of the net vortex motion in Nb films nanostructured by focused particle beam techniques.Документ g-phase structure in Ni-Ga-As thin film system(STC “Institute for Single Crystals”, 1997) Dukarov, S.V.When GaAs and Ni layers are deposited onto NaCl single crystals, a single crystal phase of the Ni-Ga-As ternary system is observed to grow. The presence of sites with a non-zero third index permits to determine the lattice parameters giving a" = 4.11 Å, c" = 10.90 Å as well as the angle between [-101] and [-11-1] vectors amounting 109°30'. Due to the orienting effect of the NaCl substrate, the growth of the γ"-phase of the ternary system with a" = aγ, c" = 2cγ, turns out to be more energetically favourable, while in massive specimens of the Ni—Ga binary system, the γ-phase ordering under annealing is accompanied by the γ'-phase growth with a' = 2aγ, c' = cγ. . . . . . . . . . . . . . При конденсации слоев GaAs и Ni на подогретые до температуры 200-400°С монокристаллы NaCl наблюдается рост монокристальной фазы тройной системы Ni-Ga-As. Наличие узлов с ненулевым третьим индексом дает возможность определить параметры решетки a" = 4.11 Å, c" = 10.90 Å, а также угол между векторами [-101]и [-11-1], равный 109°30'. Благодаря ориентирующему влиянию NaCl-подложки энергетически более выгодным оказывается рост γ"-фазы тройной системы с параметрами a" = aγ, c" = 2cγ, в то время как в массивных образцах двойной системы Ni-Ga упорядочение γ-фазы при отжиге сопровождается ростом γ'-фазы с a' = 2aγ, c' = cγ.Документ Heteronanoparticles of silicon dioxide with shell of Pt nanocrystals(STC “Institute for Single Crystals”, 2008) Matveevskaya, N.A.; Dobrotvorskaya, M.V.; Dukarov, S.V.; Kolupaeva, Z.I.The results of preparation and study of core-shell heteronanoparticles are represented based on monodisperse spherical SiO2 colloidal particles of 40, 120, 250, and 350 nm diameter and shell consisting of Pt nanocrystals. The heteronanoparticles surface structure and composition have been studied by transmission electron microscopy, photoelectron spectroscopy and X-ray diffraction. - - - - - - - - - - - Приведены результаты по получению и изучению свойств гетеронаночастиц типа "ядро-оболочка" на основе монодисперсных сферической формы коллоидных частиц SiO2 диаметром 40, 120, 250 и 350 нм и оболочкой из нанокристаллов Pt. Методами просвечивающей электронной микроскопии, фотоэлектронной спектроскопии и рентгеновской дифракции исследованы состав и структура поверхности гетеронаночастиц. - - - - - - - - - - - Подано результати з одержання та вивчення властивостей гетеронаночастинок типу "ядро-оболонка" на основі монодисперсних сферичної форми колоїдних наночастинок SiO2 діаметром 40, 120, 250 та 350 нм та оболонкою з нанокристалів Pt. Методами просвічуваючої електронної мікроскопії, фотоелектронної спектроскопії та рентгенівської дифракції досліджено склад та структуру поверхні гетеронаночастинок.Документ In situ research on temperature dependence of the lattice parameters of fusible metals in thin Cu-Pb and Cu-Bi films(STC “Institute for Single Crystals”, 2016) Dukarov, S.V.; Petrushenko, S.I.; Sukhov, V.N.; Skryl, O.I.The results of in situ electron diffraction study of the temperature dependence of the lattice parameter of the fusible component in the Cu-Pb and Cu-Bi two-layer films are presented. It was found that at room temperature, the parameters of the Pb and Bi crystal lattices are agreed with tabular data, however, with temperature increasing one can observe the deviation from the values corresponding to bulk samples. This indicates a significant increase in the solubility of the components in the films under study. In the Cu-Pb films according to the estimation made by assuming a linear dependence of the lattice parameter of the solid solution from concentration, copper solubility in the solid lead near the eutectic temperature is about 0.8 at%, which is much greater than the value known for bulk samplesДокумент Interaction in Ga - AgAu thin film system(STC “Institute for Single Crystals”, 1999) Andronov, V.M.; Grebennik, I.P.; Dukarov, S.V.Interaction of Ga layers with thin films of AgAu alloys with variable Au content (2-62 % by mass) are shown to result in formation of AgAuGa ternary phases having lattices similar to those observed in binary systems: γ-AgGa, γ-AuGa, AuGa, AuGa2. As the Au concentration in the binary AgAu alloy increases, the transitions are observed from the single-phase region to the double- and triple-phase ones and then the double-phase one again (phase types γ-AgGa → γ-AgGa + AuGa(AuGa2) → γ-AgGa + γ-AuGa + AuGa2 → γ-AuGa + AuGa2). . . . . . . . . . . . . . . Показано, что при взаимодействии слоев Ga с тонкими пленками сплавов AgAu переменной концентрации (2-62 мас.% Au) образуются фазы тройной системы AgAuGa с решетками, по типу сходными с наблюдаемыми в двойных системах: γ-AgGa, γ-AuGa, AuGa, AuGa2. При увеличении концентрации Au в двойном сплаве AgAu наблюдается переход от однофазной области к двух-, трех- и снова в двухфазную (фазы типа γ-AgGa → γ-AgGa + AuGa(AuGa2) → γ-AgGa + γ-AuGa + AuGa2 → γ-AuGa + AuGa2).