bluuebunny/crossref_metadata_2025 huggingface dataset:
Десорбция водорода из пентаграфана
Authors: Опенов Л.А. , Подливаев А.И.
Published: April 2019

AbstractThermally activated hydrogen desorption from pentagraphane is studied by atomistic computer simulation. Pentagraphane is a recently predicted quasi-two-dimensional hydrocarbon compound that represents a pentagraphene single layer, in which both sides are covered with hydrogen and the C–C bonds form a network of adjacent pentagons, whereas the hexagons characteristic of carbon nanostructures are lacking. The effect of hydrogen desorption on the electronic structure, phonon density of states, and Young’s modulus are studied. The temperature dependence of the characteristic desorption time is determined by the molecular-dynamics method.
Оптическая спектроскопия и сверхпроводимость купратов (О б з о р)
Authors: Москвин А.С.
Published: April 2019

AbstractThe optical properties of low-dimensional dielectric cuprates, including parent systems for high-temperature superconductors, such as La_2CuO_4, Sr_2CuO_2Cl_2, and YBa_2Cu_3O_6 are briefly reviewed. The main focus is on the d – d and p – d charge transfer transitions, which determine the fundamental absorption band. The analysis of optical properties shows the instability of parent cuprates against the d – d charge transfer with the formation of metastable electron–hole (EH) dimers of the Cu^1+–Cu^3+-type pairs coupled by the two-particle transfer and characterized by the giant electric polarizability. The formation of a system of stable EH dimers upon nonisovalent substitution determines the unconventional properties of the pseudogap and superconducting phases of doped cuprates.
Электронная структура и квадрупольные взаимодействия в перспективных катодных материалах Na-=SUB=-x-=/SUB=-M-=SUB=-y-=/SUB=-(MoO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-, M=Mn, Fe, Co и Ni
Authors: Медведева Н.И. , Сердцев А.В.
Published: April 2019

AbstractThe electronic structure and the magnetic properties of molybdates Na_ x M_ y (MoO_4)_3 (M = Mn, Fe, Co, and Ni) which are promising materials for sodium batteries have been studied in the framework of the density functional theory with the GGA and GGA+ U approximations for the first time. The calculations show that all the compounds are insulators. An important role of the correlation effects, provided by the on-site Coulomb interactions, was established in the formation of the band gap in these compounds. The quadrupole constants of  ^23Na nuclei are calculated in the nonmagnetic and ferromagnetic states within the GGA and GGA+ U approaches. It is shown that the quadrupole frequencies for nonequivalent crystallographic positions of sodium are in different frequency ranges, which allows to study the diffusion of sodium in these compounds by the Nuclear Magnetic Resonance method.
Влияние J-J-взаимодействия возбужденных состояний редкоземельного иона Pr-=SUP=-3+-=/SUP=- на магнитополяризованную люминесценцию празеодим-иттриевого граната-алюминия
Authors: Валиев У.В. , Burdick Gary W. , Вильданов Р.Р. , Rakhimov R.Yu. , Fu Dejun
Published: April 2019

AbstractThe spectra of luminescence and magnetic circular polarization of luminescence of praseodymium–yttrium aluminum garnet Pr^3+ : Y_3Al_5O_12 (PrYAG) are studied in the visible spectral region at temperature T = 300 K. An analysis of spectral dependences of magnetooptical and optical spectra makes it possible to identify optical 4  f –4  f -transitions between Stark sublevels of multiplets ^3 P _0, ^3 P _1, ^3 Н _5, and ^3 Н _6 in PrYAG. It was shown that an important role in the spectrum of the degree of magnetic circular polarization of luminescence of this paramagnetic garnet is played by the effect of quantum-mechanical J – J mixing of states of Stark singlets ^3 Н _5 and ^3 Н _6 of non-Kramer rare-earth ion Pr^3+ in the “green” luminescence band related to forbidden 4  f → 4  f transition ^3 P _0 → ^3 Н _5 in the visible spectral region. To interpret the spectra of magnetic circular polarization of luminescence, the energy of experimentally determined Stark sublevels of multiplets under study, their irreducible representations and wave functions determined by numerical simulation of the energy spectrum of the rare-earth ion Pr^3+ in the garnet structure are used.
Investigation of Ce-=SUP=-3+-=/SUP=- impurity centers in UV active media Ce:LiCaAlF-=SUB=-6-=/SUB=- and Ce:LiSr-=SUB=-0.8-=/SUB=-Ca-=SUB=-0.2-=/SUB=-AlF-=SUB=-6-=/SUB=- -=SUP=-*-=/SUP=-
Authors: Shavelev A.A. , Nizamutdinov A.S. , Semashko V.V. , Korableva S.L. , Marisov M.A. , Lukinova E.V. , Rakhimov N.F. , Morozov O.A. , Madirov E.I. , Shakirov A.A.
Published: April 2019

Fluoride crystals with the colquiriite structure LiCaAlF6 doped with Ce3+ ions are used as active media for lasers of ultraviolet spectral range with advantages of laser wavelength tuning range and no photoinduced degradation of laser properties. In this work we show that the multicenter character of Ce3+ segregation in this matrix agrees with the previously known peculiarities. On the basis of spectral-kinetic properties investigation, we show the increase of segregation coefficient for Ce3+ in LiSr0.8Ca0.2AlF6 mixed crystal. In laser experiments with Ce : LiCaAlF6 crystal, the differential efficiency of 47% and the wavelength tuning from 281 to 312 nm have been reached.
Спектроскопия и кинетика люминесценции ионов Pr-=SUP=-3+-=/SUP=- в K-=SUB=-3-=/SUB=-LuSi-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- : Pr-=SUP=-3+-=/SUP=-
Authors: Пустоваров В.А. , Ивановских К.В. , Хатченко Ю.Е. , Bettinelli M. , Shi Q.
Published: April 2019

Abstract—The luminescent characteristics of K_3LuSi_2O_7:Pr^3+ (1%), which is a promising optical material for the use as a scintillator, have been studied using a set of techniques. The luminescence spectra of K_3LuSi_2O_7:Pr^3+ (1%) contain two bands in the UV-range with peaks at 284 and 330 nm, which correspond intraconfigurational 5 d → 4 f transitions in the Pr^3+ ions. The radiation in the visible and near IR range (480–850 nm) has been represented by the intraconfigurational 4 f → 4 f transitions. The kinetics of 5 d → 4 f -luminescence contains a build-up stage (τ_rise ∼ 7–12 ns), nonexponential decay stage (τ_1/2 ∼ 60 ns), and a slow component of the μs-range when excited by high-frequency (∼8 MHz) synchrotron radiation of the X-ray range. The fast component of the decay (τ = 54 ns) dominates in the decay kinetics of luminescence along with the build-up stage while the contribution of the μs decay component is less than 0.5% at the excitation by an pulse electron beam (5Hz). The excitation spectra of d – f - and f–f -photoluminescence in the ultraviolet and vacuum ultraviolet range that are measured using synchrotron radiation reveal features that are caused by both intracenter transitions and processes related to the energy transfer from the intrinsic electronic excitations to the impurity center.
Конверсия энергии в нанокристаллах Gd-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-, легированных ионами Er-=SUP=-3+-=/SUP=-
Authors: Трофимова Е.С. , Пустоваров В.А. , Зацепин А.Ф.
Published: April 2019

AbstractThe conversion of the energy absorbed by cubic Gd_2O_3 nanocrystals doped with Er^3+ and codoped with Yb^3+ and Zn^2+ ions in a temperature range of 95–425 K is studied at various concentrations of dopants. The photoluminescence spectra confirm the ability of excitation energy transfer from the Gd^3+ ions or the matrix towards the Er^3+ ions. The population of upper excited states in the Er^3+ ions depends on the way of excitation, which cause the alterations in the probability of multiphonon relaxation from the excited states to the radiative levels. The kinetics of photoluminescence decay exhibit the possible energy transfer from anionic defects created by extra doping with Zn^2+ ions. The temperature dependences of the upconversion luminescence yield for emission lines of 560 and 660 nm are found to be different.
Кинетика импульсной катодолюминесценции кристаллов ортобората лития-гадолиния, легированного примесью церия
Authors: Киселева М.С. , Огородников И.Н. , Яковлев В.Ю.
Published: April 2019

The pulse cathodoluminescence kinetics of Li6GdB3O9 crystals in the form of both the single crystal and crystal-fiber have been studied using time-resolved absorption and luminescence spectroscopies upon excitation with a nanosecond electron beam at 293 K. Mechanism for pulse cathodoluminescence excitation has been developed on the basis of the numerical modeling of recombination processes.
Перенос электрона между разнородными лантаноидами в кристаллах BaF-=SUB=-2-=/SUB=- --- II механизмы переноса
Authors: Раджабов Е.А. , Козловский В.А.
Published: April 2019

The processes of electron transfer from a divalent lanthanide acceptor (Eu, Sm, Yb) to a trivalent lanthanide donor (Nd, Sm, Dy, Tm, Yb) and reverse thermal transfer are studied in barium fluoride crystals. Electron phototransfer at room temperatures is accompanied by a counter-movement of the charge-compensating interstitial fluorine. In the process of photobleaching at low temperatures, the divalent lanthanide donor turns out to be near the interstitial fluorine, which causes its 4f-5d absorption bands to shift to the red. The magnitude of the shift increases with decreasing size of the lanthanide in the series (Nd, Sm, Dy, Tm, Yb). Detailed mechanisms of photo and thermal electron transfer between heterogeneous lanthanides in BaF2 crystals are analyzed.
Выращивание щелочно-земельных галоидных сцинтилляционных кристаллов и их оптические свойства
Authors: Шалаев А.А. , Русаков А.И. , Шендрик Р.Ю. , Субанаков А.К. , Сокольникова Ю.В. , Мясникова А.С.
Published: April 2019

The features of the growth of alkaline-earth halide crystals BaBrI, BaClI and SrBrI by the Bridgman method are considered. The results of the study of the scintillation characteristics of grown crystals activated by europium ions are given. The actual content of europium in crystals was determined, and the light yield and luminescence decay times were estimated, and the X-ray luminescence spectra and absorption spectra of the obtained crystals were given.
Анализ причин концентрационного тушения люминесценции в кристаллофосфорах Zn-=SUB=-2-=/SUB=-SiO-=SUB=-4-=/SUB=- : Mn
Authors: Онуфриева Т.А. , Красненко Т.И. , Зайцева Н.A. , Бакланова И.В. , Ротермель М.В. , Иванова И.В. , Попов И.Д. , Самигуллина Р.Ф.
Published: April 2019

AbstractThe analysis of the unified series of single-phase Zn_2 – 2 x Mn_2 x SiO_4 samples ( x ≤ 0.2) has provided the possibility to determine the optimal dopant concentration x = 0.13 for the maximum luminescence intensity. It has been established that the dominating mechanism of concentration luminescence quenching and excitation energy dissipation is the oxidation of some Mn^2+ activating ions and the growth of defectness in the luminophore due to this process Phosphors.
Спектральные и магнитные свойства ионов Er-=SUP=-3+-=/SUP=- и Yb-=SUP=-3+-=/SUP=- в кристаллах Y-=SUB=-2-=/SUB=-Ti-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- со структурой пирохлора
Authors: Батулин Р.Г. , Черосов М.А. , Гильмутдинов И.Ф. , Халиулин Б.М. , Киямов А.Г. , Клековкина В.В. , Малкин Б.З. , Мухамедшин И.Р. , Мумджи И.Э. , Никитин С.И. , Родионов А.А. , Юсупов Р.В.
Published: April 2019

AbstractCubic Y_2Ti_2O_7 single crystals doped with Er^3+ or Yb^3+ ions have been studied by the methods of electron spin resonance (ESR) and selective laser spectroscopy. ESR spectra exhibit signals from rare-earth ions that substitute for yttrium ions in sites with local trigonal symmetry. The g tensor components are determined. The results of optical investigations indicate that impurity centers of several types are formed; the sublevel energies of the ground and excited multiplets of these centers are found. Among the great variety of detected optical centers, the centers that dominate in the formation of ESR spectra are discriminated. An analysis of the experimental data using the exchange-charge model have made it possible to determine the sets of parameters of the crystal field for Er^3+ and Yb^3+ ions substituting Y^3+ ions in regular crystallographic sites in pyrochlore Y_2Ti_2O_7.
Исследование спектральных свойств калиево-алюмоборатных стекол, легированных хромом
Authors: Агафонова Д.А. , Бабкина А.Н. , Зырянова К.С. , Игнатьев А.И. , Никоноров Н.В. , Орешкина К.В.
Published: April 2019

The work is devoted to the study of the spectral properties of potassium alumina-borate glass activated with different concentrations of trivalent chromium compounds. In this work, the glass transition temperatures of the composition (434°С) and the volume crystallization temperature of the glass matrix (600°С) were determined. Heat treatment of glass at the crystallization temperature led to the appearance of intense narrow luminescence bands in the region of 685–715 nm, which was associated with the nucleation of the crystalline LiAl7B4O17: Cr3 + phase in the glass matrix, in which chromium occupied positions in the high-symmetric octahedral environment. The concentration dependences of luminescence lifetime and quantum yield showed the presence of concentration quenching of the luminescence with an increase in the chromium content from 0.05 to 0.2 mol%. The maximum value of the quantum yield was 30%.
Люминесценция кристаллов BaBrI, активированных ионами Ce-=SUP=-3+-=/SUP=-
Authors: Шендрик Р.Ю. , Ковалев И.И. , Русаков А.И. , Сокольникова Ю.В. , Шалаев А.А.
Published: April 2019

The optical properties of BaBrI crystals doped with cerium ions were studied. The possible types of cerium-containing luminescence centers are established. Based on the experimental data obtained for trivalent lanthanides, a Dorenbos diagram was constructed. According to the results of the study of the luminescence spectra measured under X-ray excitation, possible energy transfer mechanisms are assumed. This work was supported by the Russian Science Foundation, a grant of the Russian Science Foundation 17-72-10084: spectroscopy of cerium and cerium-oxygen centers, determination of cerium concentration in crystals, analysis of the results obtained. Some of the crystals investigated in the article were grown as part of the government assignment 0350-2016-0024. The data in the work were obtained using the scientific equipment of the Collective Scientific Center "Isotope-geochemical studies" of the IHP SB RAS.
Оптический метод измерения температуры фторидных кристаллов, активированных ионами Yb-=SUP=-3+-=/SUP=- и Tm-=SUP=-3+-=/SUP=-
Authors: Казаков Б.Н. , Гориев O.Г. , Хадиев A.P. , Кораблева C.Л. , Семашко B.B.
Published: April 2019

AbstractThe fluorescence intensities ratio (FIR) method is applied for measuring the temperature inside the luminescent LiY_0.8Yb_0.2F_4:Tm^3+ crystal. The obtained results are used for monitoring of the sample temperature in the experiment when the exciting radiation waist is shifted by the focusing lens inside the sample. It is shown that a considerable change in the luminescence intensity of the LiY_0.8Yb_0.2F_4:Tm^3+ crystal (0.2%) is not accompanied by a significant change in the temperature. This verifies the hypothesis about the appearance of amplified spontaneous luminescence (ASL) of Yb^3+ ions during intense laser pumping in these crystals.
Люминесценция ионов Pr-=SUP=-3+-=/SUP=- и Nd-=SUP=-3+-=/SUP=- в двойных молибдатах
Authors: Софич Д. , Доржиева С.Г. , Чимитова О.Д. , Базаров Б.Г. , Тушинова Ю.Л. , Базарова Ж.Г. , Шендрик Р.Ю.
Published: April 2019

AbstractThe optical spectra of samples of double zirconium molybdates activated by rare-earth Pr^3+ and Nd^3+ ions are studied. The presence of bands corresponding to the 4 f –4 f transitions of Pr^3+ and Nd^3+ trivalent ions in the absorption, excitation, and luminescence spectra is shown. A strong dependence of the luminescence intensity of Pr^3+ ions on temperature is revealed.
Поляриметрия регулярных и стохастических сигналов в магнитооптике
Authors: Запасский В.С.
Published: April 2019

AbstractA brief review is presented of application of the high-sensitive laser polarimetry for detecting small changes—either regular, or stochastic—of the medium magnetization. Principles and results of application of the spectroscopy of spin fluctuations to atomic and semiconductor systems are described. New possibilities of studying the radiospectroscopic and optical properties of spin systems using the methods of noise spectroscopy are considered. Prospects for expanding the circle of objects of the spin noise spectroscopy at the expense of impurity dielectrics are discussed.
Spectral Properties and Thermal Quenching of Mn-=SUP=-4+-=/SUP=- Luminescence in Silicate Garnet Hosts CaY-=SUB=-2-=/SUB=-MgMAlSi-=SUB=-2-=/SUB=-O-=SUB=-12-=/SUB=- (M=Al, Ga, Sc) -=SUP=-*-=/SUP=-
Authors: Kirm M. , Oja M. , Kozlova J. , Mandar H. , Vielhauer S. , Jansen T. , Justel T. , Khaidukov N.M. , Makhov V.N.
Published: April 2019

AbstractMulti-component silicate garnet ceramics CaY_2MgMAlSi_2O_12 comprising different cations M = Al, Ga or Sc in octahedral sites doped with Mn^4+ ions have been synthesized and studied as novel red-emitting phosphors aiming at warm white pc -LED applications. All synthesized phosphors exhibit Mn^4+ luminescence in rather deep red region, the shortest-wavelength spectrum of Mn^4+ luminescence (peak wavelength at 668 nm) being obtained for the host with the largest cation M^3+ = Sc^3+ in the octahedral site. The effect of increasing the energy of the emitting Mn^4+^2 E level with the size of the host cation in octahedral sites is supposed to be the result of decrease of the covalence of the “Mn^4+-ligand” bonding with increase of the interionic Mn^4+–O^2– distance. All studied phosphors demonstrate rather poor thermal stability of Mn^4+ photoluminescence with a thermal quenching temperature T _1/2 below 200 K, the lowest value being observed for the host with M = Sc. As expected, the decrease of the energy of the O^2––Mn^4+ charge-transfer state is observed with the increase of the M^3+ cation radius, i.e. with the increase of the O^2––Mn^4+ interionic distance. The thermal quenching temperature of Mn^4+ luminescence in the studied phosphors correlates with the energy of the O^2––Mn^4+ charge transfer state which is supposed to serve as a quenching state for Mn^4+ luminescence.
Кинетика нарастания ап-конверсионной люминесценции кристалла LiY-=SUB=-0.8-=/SUB=-Yb-=SUB=-0.2-=/SUB=-F-=SUB=-4-=/SUB=- : Tm-=SUP=-3+-=/SUP=- (0.2 at.%) при импульсном возбуждении
Authors: Михеев А.В. , Казаков Б.Н.
Published: April 2019

AbstractThe regression analysis of the rise kinetics of up-conversion luminescence of the LiY_0.8Yb_0.2F_4:Tm^3+ (0.2 at %) crystal is performed. The kinetics curve is obtained with rectangular pulsed excitation by radiation from a laser diode (IR LD) with a wavelength of λ_ p = 933 nm. The most important—in these experimental conditions—mechanisms of the energy transfer from Yb^3+ ions to Tm^3+ ions are established, which are responsible for the transitions between the ground ^3 H _6 and excited ^3 F _4, ^3 H _4, ^1 G _4, ^1 D _2, and ^1 I _6 terms of the Tm^3+ ions. The durations of the relevant energy transfer processes are determined. It is shown that the energy transfer between rare earth ions in the LiY_0.8Yb_0.2F_4:Tm^3+ (0.2 at %) crystal occurs through the dipole–dipole interactions.
Синтез и люминесцентные свойства титанатов висмута Bi-=SUB=-1.6-=/SUB=-Ho-=SUB=-x-=/SUB=-Ti-=SUB=-2-=/SUB=-O-=SUB=-7-delta-=/SUB=- и Bi-=SUB=-1.6-=/SUB=-Mg-=SUB=-0.1-=/SUB=-Ho-=SUB=-x-=/SUB=-Ti-=SUB=-2-=/SUB=-O-=SUB=-7-delta-=/SUB=-
Authors: Ищенко А.В. , Королева М.С. , Власов М.И. , Истомина Е.И. , Пийр И.В.
Published: April 2019

AbstractPyrochlores Bi_1.6Ho_ x Ti_2O_7 – δ and Bi_1.6Mg_0.1Ho _ x Ti_2O_7 – δ, where x = 0, 0.01, 0.05, and 0.1, and Bi_1.5Ho_ x Ti_2O_7 – δ, where x = 0.25 and 0.5, have been synthesized and their structural, optical, and luminescence properties have been studied. As a result of analyzing the data obtained experimentally and the available theoretical data, it is shown that the intrinsic luminescence of the samples is due to the O2 p ↔ Bi6 p and Bi6 s  ↔ Bi6 p electron transitions and the impurity luminescence is due to the f – f transitions in Ho^3+ and the O2 p → Ho^3+ charge transfer.
Модификация наночастиц оксида церия при облучении ускоренными электронами
Authors: Бажукова И.Н. , Мышкина А.В. , Соковнин С.Ю. , Ильвес В.Г. , Киряков А.Н. , Бажуков С.И. , Вазиров Р.А. , Касьянова В.В. , Звонарева И.А.
Published: April 2019

AbstractThe luminescence and optical properties of ceria (CeO_2) nanoparticles irradiated by accelerated electrons with an energy of 10 MeV are investigated in this work. CeO_2 nanoparticles are prepared by the pulse electron evaporation of a ceramic target with vapor condensation of the evaporated material in a low-pressure gas on a NANOBIM-2 installation. The irradiation of CeO_2 nanopowders is found to cause the degradation of their luminescence and optical characteristics. The irradiation of a final aqueous suspension leads to the shift of a photoluminescence band toward the long wave range spectral range in comparison with the irradiation of a nanopowder. The catalytic-like behavior of CeO_2 nanoparticles interacting with hydrogen peroxide is analyzed, as well. Nanoparticles modified by the electron beam exhibit the deterioration of their enzyme-like activity.
Обменные и обменно-релятивистские эффекты в возбужденных состояниях 3d-ионов в кристаллах
Authors: Москвин А.С.
Published: April 2019

AbstractThe use of the simplest Heisenberg or Dzyaloshinskii–Moriya-type spin Hamiltonians traditional for the ground orbital nondegenerate states does not allow the features of the exchange and exchange-relativistic couplings for the excited states of 3 d and 4 f ions in crystals to be correctly described. We have considered a generalized Hamiltonian of the exchange and superexchange couplings, which makes it possible to take into account the effects of orbital (quasi)degeneracy and the exchange mechanism of excitation transfer using a single approach. A new mechanism of the spin–other orbit exchange-relativistic couplings is discussed, in particular, the spin–orbital analog of the Dzyaloshinskii–Moriya interaction and its manifestation in the circular magnetooptics of weak ferromagnets.
Люминесцентные свойства активированных нанокомпозитов на основе наночастиц структуры "ядро--оболочка"
Authors: Пухов К.К.
Published: April 2019

The analytical expressions are derived for the rates of the spontaneous electric–dipole radiative decays of the luminescent centers located in the core-shell nanoparticles and in the matrix of nanocomposite. The effective medium models and local field problems associated with the optical properties of activated nanocomposites based on the subwavelength core-shell nanoparticles are discussed. A detailed analysis of two modern approaches to the problem of spontaneous transitions in luminescent centers located in homogeneous spherical nanoparticles has been carried out.
Оптические свойства нанокристаллического TiO-=SUB=-2-=/SUB=-, легированного ионами Co, после различных обработок
Authors: Мостовщикова Е.В. , Ермаков А.Е. , Уймин М.А. , Минин А.С.
Published: April 2019

AbstractThe absorption spectra of cobalt-doped anatase TiO_2 nanopowders in the infrared and visible ranges have been studied after various oxidative and reductive treatments. The annealing leads to the appearance of the Drude-like contribution in the infrared region and significant change in the absorption in an visible range due to the formation of defects of the oxygen-vacancy-type and Ti^3+ ions. The observed additional contribution in the absorption spectra of TiO_2:Co nanopowders as compared to the spectra of undoped powders is ascribed to the d – d transitions in ions Co^2+. The change in the absorption related to cobalt after annealing is explained by a change in the local environment of Co ions from the octahedral to the tetrahedral environment.
A PL and PLE study of high Cu content Cu-=SUB=-2-=/SUB=-ZnSnSe-=SUB=-4-=/SUB=- films on Mo/glass and solar cells -=SUP=-*-=/SUP=-
Authors: Sulimov Mikhail A. , Yakushev Mikhail V. , Forbes Ian , Prieto Jose M. , Mudryi Alexander V. , Krustok Juri , Edwards Paul R. , Martin Robert W.
Published: April 2019

AbstractCu_2ZnSnSe_4 (CZTSe) is amongst leading candidates for the absorber layer in sustainable solar cells. We examine CZTSe thin films with [Cu]/[Zn + Sn] of 0.99 and [Zn]/[Sn] of 1.07, deposited on Mo/glass substrates, and solar cells fabricated from these films. The bandgap ( E _ g ) of the as deposited films and solar cells was examined by photoluminescence excitation (PLE) whereas the temperature and excitation intensity dependence of photoluminescence (PL) spectra was used to examine the nature of radiative recombination. The 6 K PL spectra of CZTSe/Mo exhibit an intense broad and asymmetrical band P1 at 0.822 eV and a lower intensity band P2 at 0.93 eV. The shape of this band, high rates of blue shift with excitation intensity rise (  j -shift) j (P1) = 14 meV and j (P2) = 8 meV per decade, and red shifts of both bands with increasing temperature suggest that both bands are associated with valence band tails due to potential fluctuations caused by high populations of charged defects. The mean depth of such fluctuation γ of 24 meV was estimated from the low energy side of P1. Device processing increased E _ g , blue shifted P1, decreased its width, j -shift and the mean depth of potential fluctuations. These can be due to the annealing and/or can partly be related to KCN etching and the chemical effect of Cd, from CdS replacing copper at the CdS–CZTSe interface layer. Processing induced a new broad band P3 at 1.3 eV (quenching with E _ a = 200 meV). We attributed P3 to defects in the CdS layer.
Excitons in PL spectra of Cu(In, Ga)Se-=SUB=-2-=/SUB=- single crystal -=SUP=-*-=/SUP=-
Authors: Skidchenko E. , Yakushev M.V. , Spasevski L. , Edwards P.R. , Sulimov M.A. , Martin R.W.
Published: April 2019

AbstractA photoluminescence (PL) study of Cu(In,Ga)Se_2 (CIGSe) single crystals, (grown by the vertical Bridgman technique) with the [Ga]/[Ga + In] ratio of 7 and 12% and the [Cu]/[In + Ga] ratio greater than unity, as measured by energy dispersive spectroscopy, is presented. Analysis of the excitation intensity and temperature dependence of the PL spectra suggested the excitonic nature of the observed near-band-edge emissions peaks. Free and bound excitons in CIGSe single crystals with both 7 and 12% Ga content are clearly observed, analyzed and identified. An activation energy of 19 meV is determined for the free exciton in the PL spectra of the sample with 12% Ga. The presence of the excitons demonstrated a high structural quality of the material.
Новые наноразмерные люминофоры, полученные испарением силикатов и германатов РЗЭ
Authors: Зуев М.Г. , Ильвес В.Г. , Соковнин С.Ю. , Васин А.А. , Бакланова И.В.
Published: April 2019

AbstractNanophosphors in the amorphous state are first obtained via pulsed electron beam evaporation of targets made of polycrystalline phosphors with the compositions Ca_2M_8(SiO_4)_6O_2:Eu (M = Y and Gd) and Ca_2La_8(GeO_4)_6O_2:Eu with the structure of oxyapatite. Reduction of ions Eu^3+ → Eu^2+ in the electron beam is found. Modification of the Raman scattering (RS) spectra of the samples in the case of a decrease in the size of the particles from bulk to a nanosized state is found. The change in the forbidden band width E _ g of the samples in the case of transition from a bulk powder to an NP is considered. The spectral and luminescence characteristics of the samples in the polycrystalline and nanoamorphous states are studied. It is shown that, in the case of transition to nanosamples, the ligand field around Eu^2+ changes. This may be due to the violation of the translational symmetry in the NP. The bond between the 4 f and 5 d electrons weakens. Degeneracy of the ^2 e _ g level appears. Presumably, the reduction of ions Eu^3+ → Eu^2+ in the electron beam due to the breaking of the Si(Ge)–O bond in the process of evaporation of the samples and capture of the released electron by the Eu^3+ ions is found.
Зависимость самоиндукции тонкой цилиндрической проволоки из металла от механизма поверхностного рассеяния электронов
Authors: Завитаев Э.В. , Харитонов К.Е. , Юшканов А.А.
Published: April 2019

AbstractThe self-induction of a thin cylindrical metallic wire has been calculated. A general case when the ratio of the electron free path to the wire radius may take an arbitrary value has been considered. The dependence of the regular reflectance on surface defect density and angle of incidence of electrons on the wire’s inner surface has been taken for boundary conditions of the problem.
Анализ зависимости предела прочности от температуры сверхвысокочастотного нагрева нагруженных гетерогенных материалов (скaльных пород) на основе образования роста микротрещин
Authors: Менжулин М.Г. , Махмудов Х.Ф.
Published: April 2019

AbstractAnalysis of the dependence of the break-down point of granite on the temperature of microwave heating allows identification of the following characteristic areas: hardening is observed at low temperature heating up to 390 K; a decrease in strength appears in the temperature range from 390 to 460 K, which is due to generation, growth, and coalescence of smaller cracks and their redistribution to the boundaries of grains with the formation of intergranular microcracks; there is a significant decrease in the strength at the temperature range from 460 to 550 K, which is caused by the separation of grains into blocks with a small area of crack density as a result of their coalescence, and the destruction and splitting of granite samples occurs at temperatures above 593 K due to the development of all kinds of microcracks. The developed method of determining the rational parameters of the microwave energy impact on the softening of hard rocks in the field of standing electromagnetic waves allows justification of the effective parameters of the impact of microwave energy on quartz-containing hard rocks for their softening and destruction based on the study of the dynamics of induced microcracks.
Анизотропия магнитоэлектрических свойств объемных композитов феррит-пьезоэлектрик
Authors: Лалетин В.М. , Филиппов Д.А. , Янушкевич К.И.
Published: April 2019

AbstractThe anisotropy of magnetoelectric properties of lead zirconate–titanate and nickel ferrite based bulk composites has been experimentally studied. It has been shown that a ratio of longitudinal to transverse magnetoelectric coefficients is affected by the piezoelectric constant of a composite. The mechanism that explains the obtained dependences has been suggested; the mechanism is based on the assumption that the anisotropy of magnetic properties is caused by the deformation occurring at electric polarization of a sample.
Резонансные изменения микроволнового коэффициента преломления в пластинах иттриевого феррита-граната
Authors: Кузнецов Е.А. , Ринкевич А.Б. , Перов Д.В.
Published: April 2019

AbstractThe influence of microwave resonance phenomena on complex refractive index in YIG plates has been theoretically and experimentally studied in the frequency range 26–38 GHz. It has been shown that a change in the magnetic field causes severe resonance-type changes in transmission and reflection factors. These changes are due both to effective interaction between millimeter electromagnetic waves and YIG plates (specifically, under ferromagnetic resonance conditions) and to the fulfillment of geometrical resonance conditions (when an integer number of half-waves or an integer odd number of quarter-waves are accommodated on the thickness of the plate). An algorithm to calculate complex refractive index with regard to the tensor-type magnetic permeability of YIG is suggested. The field and frequency dependences of complex refractive index have been analyzed. Geometrical resonance fields have been compared with extrema in the field dependences of the transmission and reflection factor moduli.
Дестабилизация внедрения высокоскоростной струи в хрупких материалах
Authors: Румянцев Б.В.
Published: April 2019

AbstractThe results of penetration of a high-speed metal jet (with a velocity of 3–7 km/s) into brittle materials (ceramics and glass) have been analyzed. The data on jet destabilization as a result of the response of the brittle material to the high-speed penetration are presented. The generalized dependence of the high-speed jet absorption efficiency on the bending strength of the brittle material has been constructed in the hydrodynamic approximation.
Отрицательные электроды для литий-ионных аккумуляторов, полученные фотоанодированием кремния солнечной градации
Authors: Ли Г.В. , Астрова Е.В. , Преображенский Н.Е. , Румянцев А.М. , Павлов С.И. , Берегулин Е.В.
Published: April 2019

AbstractNegative electrodes for lithium-ion batteries prepared by electrochemical etching of single-crystalline silicon crystals demonstrate a high specific capacity per gram of the material and per unit of nominal anode area as well as a high stability during several hundreds and even thousands of cycles. However, industrial application of such structures is inexpedient in view of the high cost of the material and technology used. In this work we have investigated anodes based on disordered macropores in solar-grade n -Si obtained by photoanodization in a 4% HF solution in dimethyl formamide. The use of this organic electrolyte leads to the formation of layers with a porosity higher than in an aqueous electrolyte and ensures spontaneous separation of these layers from the substrate. The anodes have been prepared from macroporous membranes with a thickness of 48–86 μm and a porosity of 52–75%, and their electrochemical parameters have been studied. It is found that the geometrical parameters of the porous structure and experimental conditions determine the charge and discharge capacity and the cycle life of the anodes. In the regime of the charge capacity limited by 1000 mA h/g and charge/discharge rate C /5, the obtained anodes can stably operate during several hundreds of cycles, preserving a high (greater than 98%) Coulombic efficiency.
Образование композита ZnO-C с нанокристаллической структурой
Authors: Абдуев А.Х. , Ахмедов А.К. , Асваров А.Ш. , Рабаданов К.Ш. , Эмиров Р.М.
Published: April 2019

AbstractThe formation of a nanocrystalline composite of a ZnO–C system with simultaneous mechanical activation of a mixture of zinc oxide and graphite powders in a ball mill in an inert atmosphere is studied. It is shown that the presence of graphite reduces the efficiency of dispersing ZnO crystallites. The following principal dispersion mechanisms of graphite are determined: the fragmentation of particles due to the impact of grinding bodies and the exfoliation of flakes by submicron zinc oxide particles. It has been established that a composite system is formed as a result of the prolonged mechanical activation effect on the ZnO–graphite mixture, which is a nanocrystalline zinc oxide powder with uniformly distributed inclusions of micro- and nanocrystalline graphite, turbostratic carbon, exfoliated graphene structures, and amorphous carbon.
Влияние высокотемпературного отжига на сопротивление высокоскоростному деформированию и разрушению тантала при температуре 20 и 500-=SUP=-o-=/SUP=-C
Authors: Гаркушин Г.В. , Савиных А.С. , Разоренов С.В. , Канель Г.И.
Published: April 2019

AbstractTwo series of shock-wave experiments have been conducted in order to measure the Hugoniot elastic limit and determine the strain rate dependence of critical fracture stress for tantalum experiencing spall fracture. Tantalum specimens have been preannealed in vacuum at 1000°C. The evolution of elastoplastic compression shock waves at room and elevated up to 500°C temperatures has been presented from complete wave profiles recorded by a VISAR laser Doppler velocimeter. The spall strength dependence on the strain rate during the expansion of the material in a rarefaction wave has been determined.
Флуоресценция N,N'-бис(салицилиден)-1,3-пропилендиамина и его галогенпроизводных в перфторсульфоновой мембране
Authors: Лапатин Н.А. , Борисов А.Н. , Пак В.Н.
Published: April 2019

AbstractFilm phosphors are obtained by adsorption of N,N'-bis(salicylidene)-1,3-propylenediamine and its halogen derivatives from their ethanol solutions by a perfluorosulfonic membrane. Fluorescence bands with maxima at 440–460 nm are determined by the polarized state of the molecules in the membrane. We propose to consider the antibonding $$\pi _{{{\text{(N=C)}}}}^{{*}}$$ states of the azomethine fragments (HC=N–) of the molecules as emitting ones.
Спиновый угловой момент нелинейной поверхностной волны на границе раздела обычного и топологического изоляторов
Authors: Маймистов А.И. , Ляшко Е.И.
Published: April 2019

AbstractThe surface waves that propagate along the interface of a dielectric with nonlinear susceptibility of the third order and topological insulator have been considered. The optical nonlinearity of the dielectric ensures the existence of a surface wave. The density of the spin angular momentum of a surface wave has been determined for dielectrics with positive or negative linear permittivity. It has been shown that the spin angular momentum vector has a projection on the normal to the interface, which is different from the usual surface polaritons or plasmon polaritons. The discrete nature of the topological number manifests itself in the discreteness of the values of the normal and tangential components of the spin angular momentum density. The increase in the intensity of the electric field of the wave at the interface of the media changes the value of the spin angular momentum and can lead to its disappearance.
Дифференциация пигментных новообразований кожи на основе цифровой обработки оптических изображений-=SUP=-*-=/SUP=-
Authors: Римская Е.Н. , Щадько А.О. , Аполлонова И.А. , Николаев А.П. , Брико А.Н. , Дешин И.А. , Бережной П.Ю. , Кудрин К.Г. , Зайцев К.И. , Тучин В.В. , Решетов И.В.
Published: April 2019

A method for differentiation of pigmented skin neoplasms based on digital processing of optical images has been proposed. The optical images are detected using a digital camera and an etalon for its color and spatial calibration. The method implies segmentation and automatic differentiation of neoplasms based on 5 parameters –the diameter, area, color, shape and smoothness of margins of the neoplasm. It reveals clinical features of the neoplasm, required for diagnosis, and allows for calculating a probability of the neoplasms malignizaion. The proposed method has been verified using 360 imaging of pigmented neoplasms of the skin in vivo; among them: ordinary, dysplastic nevi of the skin and skin melanoma. The observed sensitivity and specificity of the proposed technique are 97% and 95%, correspondingly.
Электродинамические характеристики alpha-лактозы моногидрата в терагерцовом диапазоне-=SUP=-*-=/SUP=-
Authors: Командин Г.А. , Гавдуш А.А. , Гончаров Ю.Г. , Породинков О.Е. , Ноздрин В.С. , Чучупал С.В. , Спектор И.Е.
Published: April 2019

AbstractUsing methods of infrared, terahertz, and submillimeter spectroscopy, experimental transmission and reflection spectra of α-lactose monohydrate have been obtained at room temperature in the frequency range from 5 to 5000 cm^–1. The experimental spectra of dense pressed tablets and powdered samples have been analyzed in terms of the model of a classical oscillator. Certain parameters of absorption bands of the resonant and quasi-relaxation types are markers by which components can be selected in heterogeneous pharmacological and organic preparations using the methods of coherent submillimeter and pulsed terahertz spectroscopy.
Микрокристаллические алмазные порошки как перспективные объекты для генерации многочастотного вынужденного комбинационного рассеяния-=SUP=-*-=/SUP=-
Authors: Горелик В.С. , Скрабатун А.В. , Bi Dongxue
Published: April 2019

The laws of Raman scattering in microcrystalline diamond powders are investigated depending on the size of diamond microresonators in the range of 1–600 mkm. The observed effect of the anomalously high intensity of spontaneous Raman scattering in diamond microresonators is explained by the “trapping” of electromagnetic radiation in them, the wavelength of which is smaller than the size of diamond microcrystals. Due to the "trapping" of photons in diamond microresonators, the density of electromagnetic energy for excitation and secondary radiation increases. The high quality factor of the fundamental optical mode in the vibrational spectrum of diamond and the anomalous increase in the intensity of Raman scattering in diamond microresonators open up possibilities for observing low-threshold stimulated multifrequency Raman scattering in microcrystalline diamond powders. The use of the generation lines of a pulsed solid-state YAG: Nd3+ laser (λ = 1064 nm) and its optical harmonics (λ = 1064, 532, 354, 266 nm) as exciting radiation makes it possible to create a line of laser-frequency oscillators from the ultraviolet region that are equidistant in frequency shift to the terahertz range, promising for the study of biological and medical objects.
Сапфировый нейрохирургический зонд для аспирации опухолей мозга с демаркацией границ с помощью спектроскопии-=SUP=-*-=/SUP=-
Authors: Шикунова И.А. , Долганова И.Н. , Катыба Г.М. , Зайцев К.И. , Курлов В.Н.
Published: April 2019

AbstractA contact sapphire neurosurgical probe for the removal of brain tumors with the possibility of intraoperative exogenous fluorescence diagnostics and laser coagulation of adjacent blood vessels has been developed. The geometry of the sapphire neuroprobe has been optimized to increase the sensitivity of fluorescence diagnostics. For this purpose, a series of computational experiments have been performed using the Monte Carlo method. The technique for growing a sapphire shaped crystal with a variable cross section has been developed. Using this technique, a pilot prototype of the sapphire neuroprobe has been manufactured. The sample has been approbated experimentally.
Плазмонные фотопроводящие антенны для систем терагерцовой импульсной спектроскопии и визуализации-=SUP=-*-=/SUP=-
Authors: Лаврухин Д.В. , Галиев Р.Р. , Павлов А.Ю. , Ячменев А.Э. , Майтама М.В. , Глинский И.А. , Хабибуллин Р.А. , Гончаров Ю.Г. , Зайцев К.И. , Пономарев Д.С.
Published: April 2019

AbstractWe propose a terahertz (THz) plasmonic photoconductive antenna (PCA) with a record height of its metal electrodes of h = 100 nm and a high aspect ratio of h / p = 0.5 ( p is the period of the plasmonic grating) that can be used as a source is THz pulsed spectroscopic and imaging systems. We experimentally demonstrate that the power of the THz radiation generated by the proposed plasmonic PCA is two orders of magnitude higher than that of an equivalent ordinary PCA without a plasmonic grating. Current–voltage measurements of the thus developed plasmonic PCA under femtosecond laser excitation show that the photocurrent of the PCA increases 15-fold, up to i _p ≈ 1.2 mA. To reduce the leakage currents of the PCA, we propose a fabrication technology that is based on the etching of windows in a thin Si_3N_4 passivation dielectric layer deposited on the photoconductor surface, which makes it possible to reduce the dark current to i _d ≈ 5 μA.
Оптическая цифровая регистрация седиментации эритроцитов и ее моделирование в форме коллективного процесса
Authors: Дубровский В.А. , Дворецкий К.Н. , Марков С.В. , Карпочева Е.П. , Тучин В.В.
Published: April 2019

AbstractThe dependence of the sedimentation rate of donor blood on its percentage in the sample (the degree of its dilution with physiologic saline) ranging from 0.25 to 100% (whole undiluted blood) is investigated with digital video equipment. The ratio of the value of displacement of the sediment–supernatant boundary per time unit was taken as the blood sedimentation rate. In case of registration of different speeds of movement of this boundary in a given volume of the cuvette, their spatial averaging was performed. A substantial increase in the blood sedimentation rate was found experimentally at high levels of its dilution, and, conversely, at blood concentrations in physiologic saline solutions that are close to whole blood. At the same time, the rate of blood sedimentation decreased several times with blood content in the range of 30–50%. It was experimentally shown that variation of blood content in the physiologic saline solution over a wide range did not affect the evenness of sedimentation occurring for almost any blood concentration in the mixture. In other words, in the process of sedimentation of a single blood sample of a given dilution in the physiologic saline solution, the sedimentation rate does not change with time. The experimentally obtained results allowed to build a theoretical model of blood sedimentation for two cases: 1) sedimentation of free erythrocytes (highly diluted blood) and 2) sedimentation of erythrocyte aggregates (almost undiluted blood, up to whole blood). The originality of the model comes from the proposition to consider the sedimentation of cells and/or their aggregates as a collective effect, and not in the traditional form of sedimentation of individual particles or particles interacting with each other. This model gives a satisfactory agreement with experimental laws with the use of certain empirical constants. The study is useful for understanding the process of erythrocyte sedimentation.
Мессбауэровские исследования структуры наночастиц Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-/gamma-Fe-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- типа ядро/оболочка
Authors: Камзин А.С. , Obaidat I.M. , Валлиулин А.А. , Семенов В.Г. , Al-Omari I.A. , Nayek C.
Published: April 2019

AbstractThe phase composition, the structure of cores and shells, and the dependences of the shell thickness on the fabrication technique were determined by Mössbauer spectroscopy for core/shell Fe_3O_4/γ-Fe_2O_3 magnetic nanoparticles (MNPs) with Fe_3O_4 cores of a fixed size (8 nm) and γ-Fe_2O_3 shells of a varying thickness (1, 3, or 5 nm). A layer on the MNP surface with a magnetic state differing from that in the bulk was found. It was also found that a spin-glass state probably exists between the core and the shell. The studied core/shell Fe_3O_4/γ-Fe_2O_3 MNPs have promising applications in various fields (e.g., biomedicine).
Особенности магнитоэлектрического эффекта в структурах пермендюр-кварц-пермендюр в области электромеханического резонанса
Authors: Лалетин В.М. , Филиппов Д.А. , Поддубная Н.Н. , Маничева И.Н. , Srinivasan G.
Published: April 2019

AbstractThe experimental frequency and field dependences of the magnetoelectric effect in three-layer permendur–quartz–permendur structures in the region of electromechanical resonance were studied. It was found that the magnetoelectric voltage coefficient and the Q-factor of these structures in the resonance region are much higher than those of similar structures based on lead zirconate titanate. Anomalous behavior of the field dependences of the magnetoelectric voltage coefficient and the Q-factor was observed in the region of electromechanical resonance. This feature is attributable to the negative Δ E effect.
Максимум энтропии в масштабно-инвариантных процессах с 1/f-=SUP=-alpha-=/SUP=--спектром мощности: влияние анизотропии белого шума
Authors: Коверда В.П. , Скоков В.Н.
Published: April 2019

Large value fluctuations are modeled by a system of nonlinear stochastic equations describing the interacting phase transitions. Under the action of anisotropic white noise, random processes are formed with the 1/f^alpha dependence of the power spectra on frequency at values of the exponent from 0.7 to 1.7. It is shown that fluctuations with 1/f^alpha power spectra in the studied range of changes correspond to the entropy maximum, which indicates the stability of processes with 1/f^alpha power spectra at different values of the exponent alpha.