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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zharkov S. M., Kveglis L. I.
Заглавие : Electron-beam-initiated crystallization of iron-carbon films
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 5. - P969-974. - ISSN 1063-7834, DOI 10.1134/1.1744977
Примечания : Cited References: 34
Предметные рубрики: AMORPHOUS-GERMANIUM FILMS
EXPLOSIVE CRYSTALLIZATION
PATTERN-FORMATION
TEMPERATURE
MICROSCOPY
MECHANISM
Аннотация: A structure formed in nanocrystalline iron-carbon films exposed to an electron beam was studied. Explosive crystallization (EC) with the formation of dendrite and cellular-dendritic instabilities at a rate of up to 1 cm/s was observed. It was shown that the dependence between the growth rate of dendrite branches (or cells) during EC and the rounding radius of dendrite branch tips can be approximately described by equations used to calculate the crystal growth in supercooled melts. To explain the EC mechanism, a model of a liquid zone formed at the crystallization front was used. It was shown that the liquid zone arises due to energy accumulated in the film in the nanocrystalline state. It was assumed that this energy was accumulated due to the energy of elastic stresses. (C) 2004 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tambasov I. A., Tarasov A. S., Volochaev M. N., Rautskii M. V., Myagkov V. G., Bykova L. E., Zhigalov V. S., Matsynin A. A., Tambasova E. V.
Заглавие : Weak localization and size effects in thin In2O3 films prepared by autowave oxidation
Коллективы : Russian Foundation for Basic Research [16-32-00302 MOJI_a, 15-02-00948-A, 16-03-00069-A]; Council for Grants of the President of the Russian Federation [SP-317.2015.1]; Program of Foundation for Promotion of Small Enterprises in Science and Technology ("UMNIK" Program) [6662GammaY2015, 9607GammaY/2015]
Место публикации : Physica E: Elsevier Science, 2016. - Vol. 84. - P.162-167. - ISSN 1386-9477, DOI 10.1016/j.physe.2016.06.005. - ISSN 1873-1759(eISSN)
Примечания : Cited References:70. - This study was supported by the Russian Foundation for Basic Research (Grants # 16-32-00302 MOJI_a, # 15-02-00948-A, # 16-03-00069-A), by the Council for Grants of the President of the Russian Federation (SP-317.2015.1), and by the Program of Foundation for Promotion of Small Enterprises in Science and Technology (No. 6662 Gamma Y2015, 9607 Gamma Y/2015) ("UMNIK" Program). Electron microscopic studies were performed on the equipment of CCU KSC SB RAS.
Предметные рубрики: SOLID-STATE SYNTHESIS
INDIUM TIN OXIDE
DOPED ZNO FILMS
OPTICAL-PROPERTIES
MAGNETIC-FIELD
NEGATIVE MAGNETORESISTANCE
CARBON NANOTUBES
TEMPERATURE
SEMICONDUCTOR
TRANSPORT
Ключевые слова (''Своб.индексиров.''): thin indium oxide films--weak localization--electron-electron--interaction--disordered semiconductors--nanostructured films--phase-coherent length
Аннотация: The negative magnetoresistance of thin In2O3 films, obtained by an autowave oxidation reaction, was detected within a temperature range of 4.2-80 K. The magnetoresistance was -1.35% at a temperature of 4.2 K and an external magnetic field of 1 T. A weak localization theory was used to explain the negative magnetoresistance and to determine the phase-coherence length in a temperature range of 4.2-80 K. The phase-coherence length was found to oscillate as the temperatures increased to around 30 K. From the maximum and minimum values of the oscillation of the phase-coherence length, it was suggested that the In2O3 film has two structure characteristic parameters. Transmission electron microscopy showed the structure of the thin In2O3 film to have structural features of a crystal phase- amorphous phase. It was found that the crystalline phase characteristic size was consistent with the maximum phase-coherence length and the amorphous phase characteristic size was consistent with the minimum phase-coherence length. It has been suggested that the temperature measurements of the magnetoresistance and the theory of weak localization can be used to evaluate the structural features of nanocomposite or nanostructured thin films. (C) 2016 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Altin E., Gokhfeld D. M., Demirel S., Oz E., Kurt F., Altin S., Yakinci M.E.
Заглавие : Vortex pinning and magnetic peak effect in Eu(Eu,Ba)2.125Cu3Ox
Место публикации : J. Mater. Sci.-Mater. Electron.: Springer, 2014. - Vol. 25, Is. 3. - P.1466-1473. - ISSN 0957-4522, DOI 10.1007/s10854-014-1753-1. - ISSN 1573-482X
Примечания : Cited References: 30
Предметные рубрики: SUPERCONDUCTORS
FIELD
NANOCRYSTALLINE
TEMPERATURE
LOOP
Аннотация: Eu–Ba–Cu–O composition was synthesized by solid state reaction technique. To determine optimum growth temperature, heat treatment was examined on the material at 880–1,100 °C. Microstructural evolution, phase formation and elemental distribution depending on heat treatments were examined by using X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscope analysis. Optimum fabrication conditions were determined as 1,020 °C for 24 h under oxygen atmosphere and detailed characterization of corresponding compound was performed. The magnetization hysteresis loops are expounded to be the product of superconducting Eu-123 grains and magnetic Eu2+ ions. The peak effect on the magnetization curves was described by the extended critical state model. Scaling of the pinning force was found such that the peak position is proportional to the irreversibility field H irr and the maximum pinning force is proportional to H irr 2 .
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Korovushkin M. M.
Заглавие : Renormalization of Energy Structure and Oscillation Period in the de Haas-van Alphen Effect at the Strong Intersite Coulomb Interaction
Разночтения заглавия :авие SCOPUS: Renormalization of energy structure and oscillation period in the de Haas-van Alphen effect at the strong intersite Coulomb interaction
Место публикации : J. Phys. Soc. Jpn.: PHYSICAL SOC JAPAN, 2011. - Vol. 80, Is. 1. - Ст.14703. - С. P. - ISSN 0031-9015, DOI 10.1143/JPSJ.80.014703
Примечания : Cited References: 36. - This study was supported by the program "Quantum Physics of Condensed Matter'' of the Presidium of the Russian Academy of Sciences (RAS), the Russian Foundation for Basic Research (project No. 10-02-00251), the Federal goal-oriented program Scientific Brainpower of the Russian Innovations 2009-2013, and the Siberian Division of RAS (Interdisciplinary Integration project No. 53). One of the authors (M. K.) would like to acknowledge the support of the Lavrentiev's Competition of the Siberian Division of RAS. The authors are grateful to the Physical Society of Japan for financial support in publication.
Предметные рубрики: T-C SUPERCONDUCTOR
EXTENDED HUBBARD-MODEL
CUPRATE SUPERCONDUCTORS
ELECTRON CORRELATIONS
QUANTUM OSCILLATIONS
FERMI-SURFACE
OXIDES
TEMPERATURE
STATE
BANDS
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--cuprate superconductors--intersite coulomb interaction--t-v model--de haas-van alphen effect--cuprate superconductors--de haas-van alphen effect--intersite coulomb interaction--strongly correlated electron systems--t-v model
Аннотация: The effect of strong intersite Coulomb correlations on the formation of the electron structure of the t-V model has been studied. A qualitatively new result indicating the occurrence of a split-off band of Fermi states has been obtained. The spectral intensity of this band increases with an increase in doping level and is determined by the mean-square fluctuation of occupation numbers. This results in the transformation of the energy structure and the integrated density of states and in a further decrease in state occupation in the quasimomentum space near the Fermi level as compared with Hubbard renormalization. It has been shown that this effect leads to an increase in the area of the quasimomentum space part limited by the Fermi contour and is important for the analysis of the de Haas-van Alphen oscillations in cuprate superconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Val'kova T. A., Shklyaev A. A.
Заглавие : Quantum fluctuations in a two-dimensional antiferromagnet with four-spin interaction of cubic symmetry
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 10. - P2061-2066. - ISSN 1063-7834, DOI 10.1134/S1063783411100350
Примечания : Cited References: 13. - This study was supported by the Presidium of the Russian Academy of Sciences (Program "Quantum Physics of Condensed Matter"), the Siberian Branch of the Russian Academy of Sciences (Interdisciplinary Integration project no. 53), the Ministry of Education and Science of the Russian Federation (Russian Federal Targeted Program "Scientific and Scientific-Pedagogical Personnel of the Innovative Russia" in 2009-2013), and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: HEISENBERG-ANTIFERROMAGNET
TEMPERATURE
STATE
Аннотация: The excitation spectrum of a non-Heisenberg 2D antiferromagnet with the four-spin interaction of cubic symmetry has been calculated in the first order of 1/2S. It has been shown that, for weak anisotropy, the N,el state is destroyed by quantum fluctuations. The phase diagrams showing the stability regions of the N,el phase in the space of spin-anisotropy parameters have been plotted.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Onufrienok V. V., Chzhan A. V., Bondarenko G. V., Yurkin G. Yu.
Заглавие : Transition of metastable pyrrhotites to a stable phase state
Место публикации : Inorg. Mater. - 2020. - Vol. 56, Is. 9. - P.898-902. - ISSN 0020-1685, DOI 10.1134/S0020168520090137. - ISSN 1608-3172(eISSN)
Примечания : Cited References: 23
Предметные рубрики: MAGNETIC-PROPERTIES
TEMPERATURE
CHEMISTRY
Аннотация: Equilibrium phase relations of synthetic minerals prepared by annealing metastable iron sulfides, followed by prolonged isothermal storage in the Earth atmosphere, have been studied by X-ray diffraction. The results demonstrate that prolonged storage of synthetic pyrrhotites annealed at different temperatures makes it possible to identify metastable and stable phases of Fe and S compounds.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Eremin E. V., Shaykhutdinov K. A., Tsikalov V. S., Petrov M. I., Balaev D. A., Semenov S. V.
Заглавие : The magnetic-field-driven effect of microwave detection in a manganite granular system
Место публикации : J. Phys. D. - 2008. - Vol. 41, Is. 1. - Ст.15004. - ISSN 0022-3727, DOI 10.1088/0022-3727/41/1/015004
Примечания : Cited References: 24
Предметные рубрики: IDENTICAL METALS
TUNNEL-JUNCTIONS
MAGNETORESISTANCE
RECTIFICATION
SPINTRONICS
TEMPERATURE
PEROVSKITES
Ключевые слова (''Своб.индексиров.''): bias currents--curie temperature--electric power generation--granular materials--magnetic field effects--microwave irradiation--voltage measurement--direct current voltage--magnetic tunnel junctions--metal insulator metal junctions--nonmagnetic metals--manganites
Аннотация: We demonstrate the microwave detection effect in a granular La0.7Ca0.3MnO3 sample. Dc voltage generated by the sample in response to microwave irradiation below the Curie temperature is found to be dependent on the applied magnetic field. The magnetic field dependence of the dc voltage has a broad peak resembling an absorption line. The detection effect depends substantially on the magnetic history of the sample; however, identical measurement conditions provide reproducibility of the experimental results. The detected dc voltage increases linearly with microwave power and strongly depends on a bias current through the sample. According to the results of systematic measurements, there exist two contributions to a value of the detected output signal. The first is magneto-independent; it can be explained in the framework of a mechanism used traditionally for description of the rectification effect in metal-insulator-metal junctions with nonmagnetic metals. The other is magneto-dependent; it originates from the interplay between the spin-dependent current through magnetic tunnel junctions and spin dynamics of the grains, which form these junctions in the sample.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokina T. V., Petrakovskii G. A., Molokeev M. S., Bondarev V. S., Velikanov D. A.
Заглавие : Synthesis and study of structural, thermodynamic, and magnetic properties of NaxLi1–xFeGe2O6 (x = 0.1–0.9) compounds
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 7. - P.1361-1370. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416070143
Примечания : Cited References: 20
Предметные рубрики: CLINOPYROXENE-TYPE LiFeGe2O6
PHASE-TRANSITION
PYROXENES
TEMPERATURE
LiFeSi2O6
CRYSTAL
Аннотация: The properties of NaxLi1–xFeGe2O6 (x = 0.1–0.9) solid solutions obtained via a solid-phase synthesis have been measured by X-ray diffraction, calorimetry, and magnetic method. The order–disorder transformations in low-dimensional NaxLi1–xFeGe2O6 (x = 0.1–0.9) spin systems with predominately antiferromagnetic exchange interaction have been revealed in the low-temperature susceptibility dependences. The study of thermal and physical properties has confirmed that substituting the sodium ions with the lithium ones induces the first-order structural phase transitions of the displacement type which are characterized by a symmetry change in monoclinic crystals from high-temperature C2/c space group to low-temperature P21/c space group. © 2016, Pleiades Publishing, Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Gavrilova T. A., Isaenko L. I., Kesler V. G., Molokeev M. S., Zhurkov S. A.
Заглавие : Synthesis and structural properties of cubic G0-Rb2KMoO3F3 oxyfluoride
Место публикации : Ceram. Int.: Elsevier, 2012. - Vol. 38, Is. 3. - P.2455-2459. - ISSN 0272-8842, DOI 10.1016/j.ceramint.2011.11.013
Примечания : Cited References: 23. - This study was partly supported by RFBR (Grant 09-02-00062) and SB RAS (Grant 34).
Предметные рубрики: PHASE-TRANSITIONS
FERROELECTRIC K3WO3F3
(NH4)(3)MOO3F3
TEMPERATURE
PEROVSKITE
ELPASOLITE
CRYSTALS
BEHAVIOR
High temperature
Melt solidification
Micromorphologies
Melt solidification
Microstructure-final
Oxyfluorides
Space Groups
Oxyfluorides
X ray methods
Ключевые слова (''Своб.индексиров.''): powders: solid state reaction--microstructure-final--x-ray methods--alkali oxides--halides
Аннотация: High-temperature G0 polymorph of Rb2KMoO3F3 has been prepared by melt solidification. Micromorphology and chemical properties of the final product were evaluated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The elpasolite-related crystal structure of G0-Rb2KMoO3F3 has been refined by Rietveld method at T = 298 K (space group Fm-3m, a = 8.92446(8) Å, V = 710.76(1) Å3; RB = 3.55%). Ferroelectric G1-Rb2KMoO3F3 polymorph, earlier reported at T˂328 K, is not found at T = 298 K.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Yelisseyev A. P., Galashov E. N., Molokeev M. S.
Заглавие : Synthesis and luminescence properties of Li2O–Y2O3–TeO2:Eu3+ tellurite glass
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : Mater. Chem. Phys.: Elsevier Science, 2014. - Vol. 147, Is. 3. - P.1191-1194. - ISSN 0254-0584, DOI 10.1016/j.matchemphys.2014.07.003. - ISSN 1879-3312
Примечания : Cited References: 26. - This study is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: LIGHT-EMITTING-DIODES
SPECTROSCOPIC PROPERTIES
OPTICAL-PROPERTIES
ENERGY-TRANSFER
CERAMICS
Eu3+
PHOTOLUMINESCENCE
TEMPERATURE
EMISSION
PHOSPHOR
Ключевые слова (''Своб.индексиров.''): glasses--heat treatment--photoluminescence spectroscopy--optical properties
Аннотация: The Eu3+-doped red-orange emitting phosphor of tellurite glass 0.25Li2O–0.20Y2O3–0.5TeO2–0.05Eu2O3 has been synthesized by the melt quenching method. The amorphous nature of the glass has been verified by XRD measurements. The photoluminescence excitation and emission spectra, the luminescence decay curves have been investigated for the composition. The phosphor can be efficiently excited by the near UV light to realize the intense narrow red emission line (611 nm) corresponding to forced electric dipole transition 5D0 → 7F2 of Eu3+ ions. The Li2O–Y2O3–TeO2:Eu3+glass phosphor is a potential red-orange emitting candidate for the application in WLEDs.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pachauri, Neha, Khodadadi B., Althammer M., Singh A.V., Loukya B., Datta R., Iliev M., Bezmaternykh L. N., Gudim I. A., Mewes T., Gupta A.
Заглавие : Study of structural and ferromagnetic resonance properties of spinel lithium ferrite (LiFe5O8) single crystals
Коллективы : NSF [ECCS-1102263], NSF-CAREER [0952929], ICMS
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 117, Is. 23. - Ст.233907. - ISSN 0021, DOI 10.1063/1.4922778. - ISSN 10897550(eISSN)
Примечания : Cited References:32. - This work has been supported by NSF Grant No. ECCS-1102263. Tim Mewes and Behrouz Khodadadi would like to acknowledge support by the NSF-CAREER Award No. 0952929. R. Datta and B. Loukya sincerely acknowledge ICMS for providing advanced microscopy facility and funding. We thank Sahar Keshavarz, Archana Panikar, Stefan Kingler, and Jamileh Beik Mohammadi for help with the experimental work.
Предметные рубрики: EFFECTIVE LINEWIDTH
MAGNETIC-PROPERTIES
FIELD
TEMPERATURE
DEPENDENCE
Аннотация: The effect of B-site cation ordering on the room temperature structural and ferromagnetic resonance (FMR) properties of single crystal spinel lithium ferrite (LiFe5O8, LFO) have been investigated. A detailed microstructural analysis is done through X-ray diffraction, polarized Raman spectroscopy, and transmission electron microscopy (TEM) to examine the effect of post-annealing on the B-site cation ordering. The X-ray diffraction pattern of the as-grown crystal indicates a disordered state of the crystal. However, the annealed sample shows additional superlattice reflections corresponding to the ordered phase. This ordering is further confirmed by Raman spectra and TEM images, which reveal ordering of Li and Fe ions at the octahedral sites contrasting with the relatively high degree of octahedral site disorder in the as-grown crystal. To study the effect of B-site ordering on the magnetic properties and FMR linewidth, vibrating sample magnetometry and broadband FMR measurements have been performed for both the ordered and disordered phases of lithium ferrite. The value of saturation magnetization for both phases is ∼290 emu/cm3. A single mode FMR profile is observed for both phases with little distortion. The linewidth characteristics of the ordered and disordered phases of lithium ferrite phases are compared, and it is observed that the linewidth is independent of the cation ordering. Both the phases exhibit a low linewidth (∼26 Oe at 30 GHz) and the effective damping parameter for the as-grown and annealed samples is determined to be 0.0021 ± 0.0001.Влияние катионного упорядочения в Б-позициях при комнатной температуре на структурные свойства и ферромагнитный резонанс (ФМР) монокристалла литий железной шпинели (LiFe5O8, LFO) были исследованы. Подробный анализ микроструктуры делается с использованием рентгеновской дифракции, спектроскопии комбинационного рассеяния поляризованного света и просвечивающей электронной микроскопии (ПЭМ), чтобы изучить влияние после отжига на катионное упорядочение в B-позиции. Рентгеновская дифракционная картина, так выращенных кристаллов указывает на беспорядочное состояние кристалла. Тем не менее, пример показывает дополнительные индексы, соответствующие сверхрешетчатой упорядоченной фазы, при отжиге. Этот порядок подтверждается также спектрами комбинационного рассеяния и ТЕМ изображений, которые показывают порядок ионов Li и Fe в октаэдрических контрастными с относительно высокой степенью восьмигранной расстройства позиций в выращенных кристаллах. Для изучения влияния упорядочения В-позиций на магнитные свойства и ширины линии ФМР, вибрационные образцы магнитометрии и широкополосных ФМР измерений были выполнены как для упорядоченных и неупорядоченных фаз литиевого феррита. Значение намагниченности насыщения для обоих фаз ~290 emu / см3. Одиночный профиль в режиме ФМР наблюдается для обеих фаз с небольшим искажением. Ширина линии характеристики упорядоченной и неупорядоченной фаз литиевых ферритов сравниваются, и следует отметить, что ширина линии не зависит от катионного упорядочения. Оба фазы проявляют малую ширину линии (Э около 26 на 30 ГГц) и эффективный параметр демпфирования, как, для только выращенных, так и для отожженных образцов, определяется как 0,0021 ± 0,0001.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Liu Q.
Заглавие : Structural phase transformation and luminescent properties of Ca2-xSrxSiO4:Ce3+ orthosilicate phosphors
Место публикации : Inorg. Chem.: American Chemical Society, 2015. - Vol. 54, Is. 23. - P.11369-11376. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.5b01955
Примечания : Cited References: 38. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51572023, 51272242, and 51511130035), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in Univ. of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), Beijing Youth Excellent Talent Program (YETP0635), and the Funds of the State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences (RERU2015022)
Предметные рубрики: LIGHT-EMITTING-DIODES
DICALCIUM SILICATE
CRYSTAL-STRUCTURE
SOLID-SOLUTION
BOND-VALENCE
Ce3+
Eu2+
β-Ca2SiO4
GREEN
TEMPERATURE
Аннотация: The orthosilicate phosphors demonstrate great potential in the field of solid-state lighting, and the understanding of the structure-property relationships depending on their versatile polymorphs and chemical compositions is highly desirable. Here we report the structural phase transformation of Ca2-xSrxSiO4:Ce3+ phosphor by Sr2+ substituting for Ca2+ within 0 ≤ x 2. The crystal structures of Ca2-xSrxSiO4:Ce3+ are divided into two groups, namely, β phase (0 ≤ x 0.15) and α′ phase (0.18 ≤ x 2), and the phase transition (β → α′) mechanism originated from the controlled chemical compositions is revealed. Our findings verified that the phase transition Pnma (α′-phase) ↔ P21/n (β-phase) can be ascribed to the second-order type, and Sr2+ ions in Ca2-xSrxSiO4 preferentially occupy the seven-coordinated Ca2+ sites rather than the eight-coordinated sites with increasing Sr2+ content, which was reflected from the Rietveld refinements and further clarified through the difference of the Ca-O bond length in the two polymorphs of Ca2SiO4. The emission peaks of Ce3+ shift from 417 to 433 nm in the composition range of 0 ≤ x ≤ 0.8, and the difference in the decay curves can also verify the phase transformation process. Thermal quenching properties of selected Ca2-xSrxSiO4:Ce3+ samples were evaluated, and the results show that the integral emission intensities at 200 °C maintain 90% of that at room temperature suggesting superior properties for the application as white light-emitting diodes (w-LEDs) phosphors. © 2015 American Chemical Society.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Gavrilova T. A., Kesler V. G., Molokeev M. S., Aleksandrov K. S.
Заглавие : Structural and electronic parameters of ferroelectric K3WO3F3
Коллективы :
Место публикации : Solid State Commun. - 2010. - Vol. 150, Is. 43-44. - P.2085-2088. - ISSN 0038-1098, DOI 10.1016/j.ssc.2010.09.023
Примечания : Cited References: 34. - This study was partly supported by RFBR (Grant 09-02-00062) and SB RAS (Grant 34).
Предметные рубрики: CORE-LEVEL SPECTROSCOPY
PHASE-TRANSITIONS
RHEED ANALYSIS
SURFACE
OXYFLUORIDE
ELPASOLITE
(NH4)(2)KWO3F3
SUBSTITUTION
TEMPERATURE
DIFFRACTION
Ключевые слова (''Своб.индексиров.''): ferroelectrics--chemical synthesis--electronic structure--photoelectron spectroscopies
Аннотация: The low-temperature ferroelectric G2 polymorph of K3WO3F3 oxyfluoride is formed by chemical synthesis. The electronic parameters of G2-K3WO3F3 have been measured by X-ray photoelectron spectroscopy under excitation with Al K alpha radiation (1486.6 eV). Detailed spectra have been recorded for all element core levels and Auger lines. The chemical bonding effects in the WO3 F-3 and WO6 octahedrons are considered by using the binding energy difference Delta BE(O-W) = BE(O 1s) BE(W 4f(7/2)). (C) 2010 Elsevier Ltd. All rights reserved.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Safronov A. P., Beketov I. V., Komogortsev S. V., Kurlyandskaya G. V., Medvedev A. I., Leiman D. V., Larranaga A., Bhagat S. M.
Заглавие : Spherical magnetic nanoparticles fabricated by laser target evaporation
Место публикации : AIP Adv.: American Institute of Physics, 2013. - Vol. 3, Is. 5. - Ст.052135. - P. - ISSN 2158-3226, DOI 10.1063/1.4808368
Примечания : Cited References: 47. - This work was supported by the RFBR 10-02-96015 and 12-02-31385 projects, UrFU 215, Spanish MEC MAT2011-27573-C04 grants, Universidad del Pais Vasco UPV/EHU under UFI11/53 action and Physics Department of the University of Maryland visiting grant. Selected measurements were performed at SGIker service of UPV-EHU. We thank O.M. Samatov, Dr. A.M. Murzakayev, Dr. I. Orue, and A.A. Svalova for special support.
Предметные рубрики: IRON-OXIDE NANOPOWDERS
CO2-LASER EVAPORATION
FE3O4 NANOPARTICLES
FINITE-SIZE
TEMPERATURE
FERROMAGNETS
FERROFLUIDS
DEPENDENCE
EXPLOSION
PARTICLES
Аннотация: Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of M-s up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bayukov O. A., Pletnev O. N., Yakushkin S. S., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Size effects in the magnetic properties of ε-Fe2O3 nanoparticles
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 118, Is. 21. - Ст.213901. - ISSN 00218979 (ISSN), DOI 10.1063/1.4936838
Примечания : Cited References: 41. - We are grateful to Professor Yu. L. Raikher for useful discussions and M. A. Kazakova for the help in sample preparationThis work was supported by Russian Federal Agency of Scientific Organizations (Project No. V.44.1.15) and scientific and educational center of energy-efficient catalysis of NSU
Предметные рубрики: FERROMAGNETIC-RESONANCE
OXIDE NANOPARTICLES
WAVE ABSORBER
IRON
TRANSITION
TEMPERATURE
PARTICLES
PHASE
FNANOWIRES
FIELD
Аннотация: We report the results of comparative analysis of magnetic properties of the systems based on ε-Fe2O3, nanoparticles with different average sizes (from ∼3 to 9 nm) and dispersions. The experimental data for nanoparticles higher than 6-8 nm in size are consistent with the available data, specifically, the transition to the magnetically ordered state occurs at a temperature of ∼500 K and the anomalies of magnetic properties observed in the range of 80-150 K correspond to the magnetic transition. At the same time, Mossbauer and ferromagnetic resonance spectroscopy data as well as the results of static magnetic measurements show that at room temperature all the investigated samples contain ε-Fe2O3 particles that exhibit the superparamagnetic behavior. It was established that the magnetic properties of nanoparticles significantly change with a decrease in their size to ∼6 nm. According to high-resolution electron microscopy and Mossbauer spectroscopy data, the particle structure can be attributed to the ε-modification of trivalent iron oxide; meanwhile, the temperature of the magnetic order onset in these particles is increased, the well-known magnetic transition in the range of 80-150 K does not occur, the crystallographic magnetic anisotropy constant is significantly reduced, and the surface magnetic anisotropy plays a decisive role. This is apparently due to redistribution of cations over crystallographic positions with decreasing particle size, which was established using Mössbauer spectra. As the particle size is decreased and the fraction of surface atoms is increased, the contribution of an additional magnetic subsystem formed in a shell of particles smaller than ∼4 nm becomes significant, which manifests itself in the static magnetic measurements as paramagnetic contribution. © 2015 AIP Publishing LLC.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popkov S. I., Krasikov A. A., Dubrovskiy A. A., Volochaev M. N., Kirillov V. L., Martyanov O. N., Balaev A. D.
Заглавие : Size effects in the formation of an uncompensated ferromagnetic moment in NiO nanoparticles
Коллективы : Ministry of Science and Higher Education of the Russian Federation; Russian Foundation for Basic Research, Government of the Krasnoyarsk Territory [18-42-240012]; Krasnoyarsk Territorial Foundation [18-42-240012]
Место публикации : J. Appl. Phys. - 2019. - Vol. 126, Is. 10. - Ст.103904. - ISSN 0021-8979, DOI 10.1063/1.5109054. - ISSN 1089-7550(eISSN)
Примечания : Cited References: 54. - This study was supported by the Ministry of Science and Higher Education of the Russian Federation and by the Russian Foundation for Basic Research, Government of the Krasnoyarsk Territory, and Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project: "Magnetic Reversal of Magnetic Nanoparticles in Strong Pulsed Magnetic Fields-A New Approach to the Study of Dynamic Effects Associated with the Magnetization of Magnetic Nanoparticles," Project No. 18-42-240012.
Предметные рубрики: MAGNETIC-PROPERTIES
TEMPERATURE
SUSCEPTIBILITY
NANOFERRIHYDRITE
Аннотация: The magnetic properties of samples of NiO nanoparticles with average sizes of 23, 8.5, and 4.5 nm were investigated. Using the magnetization curves measured in strong (up to 250 kOe) pulsed magnetic fields, the contributions of the free spin and ferromagnetic subsystems were extracted. It has been found that the ferromagnetic contribution increases with a decrease in the nanoparticle size and is proportional to the fraction of uncompensated exchange-coupled spins. It is demonstrated that the uncompensated spins form in the antiferromagnetic NiO oxide due to an increase in the fraction of surface atoms in the nanoparticles with decreasing particle size and defects in the bulk of particles.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Ovchinnikov S. G.
Заглавие : Isotope effect in the model of strongly correlated electrons with the magnetic and phonon superconducting pairing mechanisms
Коллективы : Presidium of the Russian Academy of Sciences [40]; Russian Academy of Sciences; Russian Foundation for Basic Research [09-02-00127]
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.1017-1021. - ISSN 1063-7761, DOI 10.1134/S1063776109120139
Примечания : Cited References: 42. - This study was financed under programs 5.7 and "Quantum Physics of Condensed Matter" of the Presidium of the Russian Academy of Sciences, integration project no. 40 of the Siberian Branch and Ural Division of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: CUPRATE SUPERCONDUCTORS
PHASE-TRANSITIONS
3-CENTER INTERACTIONS
HUBBARD-MODEL
TEMPERATURE
LA2-XSRXCUO4
SYMMETRY
EXCHANGE
COPPER
BI2SR2CACU2O8+DELTA
Ключевые слова (''Своб.индексиров.''): ab initio calculations--calculated values--cooper pairing--isotope effect--magnetic mechanisms--order of magnitude--pairing mechanism--phonon mechanism--strongly correlated electrons--superconducting pairing mechanism--superconducting state--type theory--carrier mobility--electron-phonon interactions--isotopes--superconductivity--superconducting magnets
Аннотация: Peculiarities of the temperature isotope effect in a BCS-type theory describing the exchange and phonon mechanisms of Cooper pairing in a system of strongly correlated electrons are considered. The electron-phonon interaction constant is determined from the fitting of the calculated value of the isotope-effect index to the observed value with the parameters of La(2 - x) Sr (x) CuO(4) obtained from ab initio calculations. The value of this constant indicates that the contribution from the traditional pairing mechanism to the superconducting state is of the same order of magnitude as the contribution from the magnetic mechanism.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhigalov V. S., Myagkov V. G., Bykova L. E., Bondarenko G. N., Velikanov D. A., Volochaev M. N.
Заглавие : Rotational magnetic anisotropy in polycrystalline FePt films fabricated by solid-state synthesis
Коллективы : Russian Foundation for Basic Research [16-03-00069, 15-02-00948]; Government of the Russian Federation; Krasnoyarsk Territorial Foundation for Support of Scientific and RD Activity [16-42-243006]
Место публикации : Phys. Solid State. - 2018. - Vol. 60, Is. 1. - P.178-182. - ISSN 1063-7834, DOI 10.1134/S1063783418010298. - ISSN 1090-6460(eISSN)
Примечания : Cited References:24. - This study was supported by the Russian Foundation for Basic Research, projects nos. 16-03-00069 and 15-02-00948 and supported in part by the Government of the Russian Federation and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activity, project no. 16-42-243006.
Предметные рубрики: THIN-FILMS
ROTATABLE ANISOTROPY
NANOPARTICLES
COPT
TEMPERATURE
Аннотация: It is shown that annealing 550°C of the Fe/Pt bilayer films fabricated by layer-by-layer deposition onto polycrystalline Al2O3 substrates in an atomic ratio of Fe: Pt = 71: 29 leads to the formation of the inplane rotational magnetic anisotropy with the easy axis that can be aligned by magnetic field in any direction in the film plane. The increase in the Pt content in the investigated film system to 50 at % leads to an increase in the anisotropy constant to 6.5 × 106 erg/cm3, which exceeds the value in the Fe71Pt29 sample by a factor of 6. In addition to the rotational anisotropy, the Fe50Pt50 films are characterized by the perpendicular rotational magnetic anisotropy, which is higher than the film shape anisotropy. Therefore, the easy axis in these samples can be aligned by magnetic field in any spatial direction. According to the X-ray and magnetic measurement data, the synthesized samples have a polycrystalline structure consisting of two ordered phases: magnetically hard L10–FePt and magnetically soft L12–Fe3Pt. This gives us grounds to suggest that the rotational magnetic anisotropy originates from the epitaxial intergrowth and exchange coupling of these two phases.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Velikanov D. A., Patrin G. S., Petrakovskii G. A., Volkov V. Y.
Заглавие : Quantum interference in HTSC-ceramics of system Tl-Ca-Ba-Cu-O
Место публикации : Izvestiya vysshikh uchebnykh zavedenii Fizika. - 1990. - Vol. 33, Is. 9. - P.26-29. - ISSN 0021-3411; \b Russian Physics Journal; \b Известия высших учебных заведений. Физика
Примечания : Cited References: 13
Предметные рубрики: RF SQUID
DC-SQUID
TEMPERATURE
SUPERCONDUCTOR
OPERATION
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yin, Mengyan, Liu, Yangai, Mei, Lefu, Molokeev M. S., Huang, Zhaohui, Fang, Minghao
Заглавие : Preparation, crystal structure and up-conversion luminescence of Er3+, Yb3+ co-doped Gd2(WO4)3
Место публикации : RSC Adv.: Royal Society of Chemistry, 2015. - Vol. 5, Is. 89. - P.73077-73082. - ISSN 2046-2069, DOI 10.1039/c5ra12959a
Примечания : Cited References: 43. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51472223), the Fundamental Research Funds for the Central Universities (Grant No. 2652015008), and New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-0951).
Предметные рубрики: HYDROTHERMAL SYNTHESIS
ENERGY-TRANSFER
RED PHOSPHORS
NANOCRYSTALS
EMISSION
GREEN
HO
TEMPERATURE
TUNGSTATES
TM
Аннотация: Up-conversion (UC) phosphors Gd2(WO4)3:Er3+/Yb3+ were synthesized by a high temperature solid-state reaction method. The crystal structure of Gd2(WO4)3:3% Er3+/10% Yb3+ was refined by Rietveld method and it was showed that Er3+/Yb3+ were successfully doped into the host lattice replacing Gd3+. Under 980 nm laser excitation, intense green and weak red emissions centered at around 532 nm, 553 nm, and 669 nm were observed, which were assigned to the Er3+ ion transitions of 4H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The optimum Er3+ doping concentration was determined as 3 mol% when the Yb3+ concentration was fixed at 10 mol%. The pump power study indicated that the energy transfer from Yb3+ to Er3+ in Er3+, Yb3+ co-doped Gd2(WO4)3 was a two-photon process, and the related UC mechanism of energy transfer was discussed in detail. This journal is © The Royal Society of Chemistry.
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