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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Pochekutov M. A.
Заглавие : Anisotropy of the magnetoresistance hysteresis in the granular superconductor Y-Ba-Cu-O at different magnetic-field and transport-current orientations
Место публикации : J. Appl. Phys.: American Institute of Physics, 2017. - Vol. 122, Is. 12. - Ст.123902. - ISSN 00218979 (ISSN), DOI 10.1063/1.4986253
Примечания : Cited References: 45. - This study was supported by the Russian Foundation for Basic Research, Government of the Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project No. 16-48-243018.
Ключевые слова (''Своб.индексиров.''): anisotropy--high temperature superconductors--hysteresis--magnetic fields--magnetic flux--magnetism--magnetoresistance--different-magnetic fields--external magnetic field--granular superconductors--macroscopic transport--magnetic flux compression--magneto transport properties--model representation--transport currents--superconducting materials
Аннотация: Dissipation in granular high-temperature superconductors (HTSs) during the passage of macroscopic transport current j is mainly determined by carrier tunneling through intergrain boundaries (Josephson junctions). In the presence of external magnetic field H, it is necessary to take into account the significant magnetic flux compression, which can lead to the situation when the effective field Beff in the intergrain boundaries exceeds the external field by an order of magnitude. This is observed as a wide hysteresis of the field dependence of magnetoresistance R(H). In this study, we investigate the R(H) hysteresis evolution in granular 1-2-3 HTSs in different j-H orientations. The magnetic flux compression significantly affects the magnetoresistance and its hysteresis for both perpendicular (H ⊥ j) and parallel (H ∥ j) orientations. The obtained experimental data on the R(H) hysteresis at the arbitrary angles θ = ∠H, j are explained using the approach developed for describing the magnetoresistance hysteresis in granular HTSs with regard to the magnetic flux compression and the model representations proposed by Daghero et al. [Phys. Rev. B 66(13), 11478 (2002)]. A concept of the effective field in the intergrain medium explains the well-known anisotropy of the magnetotransport properties of granular HTSs.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Коржнева, Ксения Евгеньевна, Исаенко Л. И., Елисеев, Александр Павлович, Молокеев, Максим Сергеевич
Заглавие : Экспериментальное исследование процессов кристаллизации K2Ba(NO3)4 из раствор-расплава
Место публикации : Фундамент. пробл. совр. материаловед. - 2018. - Т. 15, № 1. - С. 11-15. - ISSN 1811-1416, DOI 10.25712/ASTU.1811-1416.2018.01.001
Примечания : Библиогр.: 7. - Работа выполнена в рамках государственного задания, проект № 0330 - 2016 - 0008 и при поддержке Российского фонда фундаментальных исследований (грант № 18-32-00359).
Ключевые слова (''Своб.индексиров.''): рост из раствор-расплава--двойные соединения--нецентросимметричные кристаллы k2ba(no3)4--рентгенофазовый и термический анализы--оптическое пропускание--growth from solution-melt--double compounds--noncentrosymmetrical crystals k2ba(no3)4--x-ray diffraction and thermal analysis--optical transmittance
Аннотация: С развитием технологий неуклонно возрастает потребность в высокоэффективных функциональных материалах. Поэтому все более важной и актуальной становится задача разработки принципов и алгоритмов поиска этих материалов. В настоящее время системы двойных нитратов привлекают внимание исследователей тем, что в этой группе существуют двойные соединения с нецентросимметричной структурой, которые рассматриваются как перспективные нелинейные материалы для коротковолнового диапазона. В результате проведенных ранее исследований из водных растворов были получены кристаллы K2Ba(NO3)4. Было выявлено, что K2Ba(NO3)4 при температуре 197,3 оС разлагается на KNO3 и Ba(NO3)2. Из-за большого количества дефектов (дендриты, зарастание основными гранями роста) оптическое качество этих кристаллов оказалось невысоким. Что обусловило необходимость поиска новых методик выращивания, обеспечивающих получение качественных оптически прозрачных кристаллов. Поэтому нами исследовались процессы кристаллизации K2Ba(NO3)4 из раствор-расплава. Подобран растворитель состава LiNO3-CsNO3-KNO3 с температурой эвтектик ниже температуры разложения двойного соединения. Выращены прозрачные кристаллы K2Ba(NO3)4 размером до 0,7 мм, определена их структура, показано отсутствие у них центра симметрии. На данных кристаллах были сняты спектры оптического пропускания. Исследование двух спектров данного соединения выращенного разными методами показало, что кристаллы, полученные из водных растворов, прозрачен от 0,25 мкм до 2,2 мкм, при этом наблюдается пик поглощения с максимум 0,3 мкм. Кристаллы, выращенные методом из раствор-расплава, прозрачны от 0,3 мкм до 2,2 мкм. Ширина запрещенной зоны составляет около 5 эВ.With the development of technology, the need for highly efficient functional materials is steadily increasing. Therefore, the developing of principles and algorithms for these materials' search becomes more and more important and actual. Currently systems of double nitrates attract researchers attention due to the double compounds with a noncentrosymmetric structure which are considered as promising nonlinear materials for the short-wave range. As a result of previous studies K2Ba(NO3)4 crystals were obtained from aqueous solutions. It was found that K2Ba(NO3)4 decomposes on KNO3 and Ba(NO3)2 at the temperature of 197.3 oC. Due to the large amount of defects (dendrites, overgrowing by the main growth facets), the optical quality of these crystals was not high. This necessitated the search for new growth techniques that provide the production of high-quality optically transparent crystals. Therefore, we investigated the processes of crystallization of K2Ba(NO3)4 from a solution-melt. A solvent of the LiNO3-CsNO3-KNO3 composition with a eutectic temperature below the decomposition temperature of the double compound was chosen. Transparent crystals of K2Ba(NO3)4 up to 0.7 mm in size were grown, their structure was determined, and the absence of center of symmetry was shown. The optical transmission spectra were investigated on these crystals. The study of two spectra of this compound grown by different methods showed that crystals obtained from aqueous solutions are transparent from 0.25 μm to 2.2 μm, with an absorption peak with a maximum of 0.3 μm. Crystals grown by the solution-melt method are transparent from 0.3 μm to 2.2 μm. The width of the band gap is about 5 eV.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou Z., Zhang N., Chen J., Zhou X., Molokeev M. S., Guo C.
Заглавие : The Vis-NIR multicolor emitting phosphor Ba4Gd3Na3(PO4)6F2: Eu2+, Pr3+ for LED towards plant growth
Место публикации : J. Ind. Eng. Chem. - 2018. - Vol. 65. - P.411-417. - ISSN 1226086X (ISSN), DOI 10.1016/j.jiec.2018.05.014
Примечания : Cited References: 36. - This work was supported by National Natural Science Foundation of China (No. 11704312, 11274251), Research Fund for the Doctoral Program of Higher Education of China (RFDP) (No.20136101110017), Foundation of Key Laboratory of Photoelectric Technology in Shaanxi Province (15JS101).
Ключевые слова (''Своб.индексиров.''): phosphor--plant growth--leds--energy transfer
Аннотация: Photosynthesis process is the basic for plant growth, which needs energy from the light. The pigments of chlorophyll a, b and bacteriochlorophyll are responsible for the absorption of light, in which blue, red and near-infrared (NIR) light directly or indirectly promote the plant growth and enhancement of nurtiments. It is important for plant to support absorbable light, and phosphhor-converted light emitting diodes (pc-LEDs) are low-cost, energy-saving and enviromental friendly devices for plant growth. To develop a phosphor with emission covering the blue, red and NIR, a series of phosphors Ba4Gd3Na3(PO4)6F2: Eu2+, Pr3+ with blue, red and NIR multi-emitting were prepared. Their emissions not only match well with the absorption spectra of pigments in the plant, but also could be excited by near ultraviolet (n-UV) LED chip. The crystal structure of host Ba4Gd3Na3(PO4)6F2 was refined from the XRD data and three different crystallographic sites occupied by Eu2+ were determined through low temperature photoluminescence spectra. The energy transfer from Eu2+ to Pr3+ ions was also discussed in detail. Results indicated that the multi-emitting Ba4Gd3Na3(PO4)6F2: Eu2+, Pr3+ can serve as a phosphor candidate for plant growth LEDs.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Velikanov D. A., Rabinovich K. S., Samoilenko L. L.
Заглавие : Magnetic properties of Ba2Cu3O4Cl2
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.P2.16. - P.158. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 4
Ключевые слова (''Своб.индексиров.''): layered cuprate--magnetic moment--coercivity--remanence--weak ferromagnet
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Velikanov D. A., Rabinovich K. S., Samoilenko L. L.
Заглавие : Magnetic properties of Ba2Cu3O4Cl2
Коллективы : "Магнитные материалы. Новые технологии", Байкальская международная конференция, "Magnetic materials. New tecnologies", Baikal International Conference, Байкальская международная конференция "Магнитные материалы. Новые технологии", Иркутский государственный университет
Место публикации : Магнитные материалы. Новые технологии: тез. докл. VII Байкал. Междунар. конф./ Иркутский гос. ун-т. - Иркутск, 2016. - P.224. - ISBN 978-591-345-152-1: тез. докл. VII Байкал. Междунар. конф. BICMM-2016/ "Magnetic materials. New tecnologies", Baikal International Conference (7 ; 2016 ; Aug. ; 22–26 ; Listvyanka, Irkutsk region), Иркутский гос. ун-т; чл. прогр. ком.: Р. С. Исхаков, С. С. Аплеснин, С. Г. Овчинников. - ISBN 978-591-345-152-1
Примечания : Библиогр.: 5 назв. - The work was supported by Russian Foundation for Basic Research. Project 16-03-00256
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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Atuchin V. V., Molokeev M. S., Park, Hee Kook, Lee, Beom Hyun, Won, Dong Min, Oh, Won-Chun, Lim, Chang Sung
Заглавие : Microwave sol-gel derived MMoO4 (M=Ba,Cs,Sr) nanoparticles doped with Er/Yb, Ho/Yb, Ho/Yb/Tm and their upconversion photoluminescence properties for biomedical applications
Коллективы : International Conference on Multifunctional Materials and Application
Место публикации : The 10th International conference on multifunctional materials and application. - 2016. - Ст.43-P. - P.76
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shtarev D. S., Shtareva, A., V, Kevorkyants R., Rudakova, A., V, Molokeev M. S., Bakiev, T., V, Bulanin K. M., Ryabchuk V. K., Serpone N.
Заглавие : Materials synthesis, characterization and DFT calculations of the visible-light-active perovskite-like barium bismuthate Ba1.264(4)Bi1.971(4)O4 photocatalyst
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [19-73-10013]; Saint-Petersburg State University [39054581]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-03-00855]
Место публикации : J. Mater. Chem. C. - 2020. - Vol. 8, Is. 10. - P.3509-3519. - ISSN 2050-7526, DOI 10.1039/c9tc06457e. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 42. - The current research was kindly funded by a grant from the Russian Science Foundation (project No. 19-73-10013). R. K., A. V. R., V. K. R. and T. V. B. acknowledge financial support from Saint-Petersburg State University (Pure ID 39054581). A. V. R. thanks the Russian Foundation for Basic Research for a Grant No. 18-03-00855 that supported studies into the photoinduced hydrophilicity of the bismuthate. The authors are further grateful to the staff of the Khabarovsk Innovation and Analytical Center of the Yu. A. Kosygin Institute of Tectonics and Geophysics of the Far Eastern Branch of the Russian Academy of Sciences, and the Resource Centers of the Research Park at the Saint-Petersburg State University: (i) the Center for Diagnostics of Functional Materials for Medicine, Pharmacology and Nanoelectronics, (ii) the Center for Physical Methods of Surface Investigation, (iii) the Center for Optical and Laser Materials Research, and the laboratories of (iv) Nanotechnology and (v) Nanophotonics for their valuable assistance in carrying out the research and in providing the needed equipment. One of us (N.S.) is grateful to Prof. Angelo Albini and the staff of the PhotoGreen Laboratory at the University of Pavia, Italy, for their continued hospitality.
Предметные рубрики: OXIDE
NIO/SRBI2O4
SPECTRA
DRIVEN
CO2
LA
Аннотация: A perovskite-like barium bismuthate of the BaBi2O4 class, Ba1.264(4)Bi1.971(4)O4, has been prepared by solid-state synthesis and subsequently characterized by a number of experimental techniques (XPS, DRS, SEM, EDX and Raman spectroscopy), as well as by a DFT computational approach using the GGA Perdew–Burke–Ernzerhof (PBE) density functional to determine the energy band structure. XRD peaks were indexed to a rhombohedral cell (R[3 with combining macron]m) with parameters close to Ba0.156Bi0.844O1.422 (i.e., to Ba0.439Bi2.374O4), which upon Rietveld refinement gave Ba1.264(4)Bi1.971(4)O4. The Bi–O bond lengths determined from this refinement (1.86 and 2.31 Å) accorded with the bond lengths estimated from Raman spectra (1.97 and 2.26 Å). DFT calculations revealed the bismuthate to display two bandgaps that correspond to lower-energy indirect (2.28 eV) and to higher-energy direct (2.36 eV) electronic transitions in good agreement with the experimental bandgaps of 2.26 eV and 2.43 eV, respectively, from Tauc plots of DRS spectra. Relative to the indirect bandgap energy of 2.26 eV, the energies of the valence band and of the conduction band were, respectively, +1.14 eV and −1.12 eV. The photoactivity of Ba1.264(4)Bi1.971(4)O4 was examined toward the photoreduction of the greenhouse gas CO2 in aqueous media photoelectrochemically yielding alcohols and alkanes, while in the gas phase in an infrared cell reactor the products were carbon monoxide and alkanes.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang, Guangqing, Molokeev M. S., Ma, Qianchao, Yang, Xuening, Han, Shuiquan, Chen, Q.i., Zhong, Binnian, Ma, Bin
Заглавие : Structural analysis and optical temperature sensing performance of Eu3+-doped Ba3In(PO4)3
Место публикации : CrystEngComm. - 2020. - Vol. 22, Is. 35. - P.5809-5817. - ISSN 1466-8033, DOI 10.1039/d0ce00997k
Примечания : Cited References: 52. - This work was supported by the National Natural Science Foundation of China (Grant No. 51802172) and the Qinghai Provincial Natural Science Foundation for Young Scholars (No. 2018-ZJ-957Q)
Предметные рубрики: FLUORESCENCE INTENSITY RATIO
UP-CONVERSION EMISSIONS
RARE-EARTH IONS
Аннотация: Eu3+-Doped Ba3In(PO4)3 was synthesized through a high-temperature solid-phase method. According to the structure refinement based on X-ray diffraction and density functional theory, the crystal and energy band structures of Ba3In(1−x)(PO4)3:xEu3+ were studied and analyzed in detail. The effect of Eu3+ doping concentrations on emission was studied at an excitation wavelength of 393 nm. For the material Ba3In(1−x)(PO4)3:xEu3+(x = 0.01–0.30), the optimal doping level is confirmed to be 0.18. Due to the thermal quenching differences of Eu3+ at the 5D0 and 5D1 energy levels, and based on the temperature-variable fluorescence intensity ratio between emission peaks, the optical temperature measurement performance of this material in the temperature range from 298.15 K to 623.15 K was characterized, and the maximum absolute and relative sensor sensitivities (Sa and Sr) were determined to be 0.1002 K−1 and 4.058%, respectively. With temperature as the only variable, the color of the phosphor changes from red to yellow light with rising temperature. Besides, Sa and Sr values of this phosphor are comparable to other sensing materials. The results indicate that Eu3+-doped Ba3In(PO4)3 phosphors have great potential to be applied in optical temperature sensing.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yang, Zhiyu, Zhou, Yayun, Qiao, Jianwei, Molokeev M. S., Xia, Zhiguo
Заглавие : Rapid synthesis of red-emitting Sr2Sc0.5Ga1.5O5:Eu2+ phosphors and the tunable photoluminescence via Sr/Ba substitution
Место публикации : Adv. Opt. Mater. - 2021. - Vol. 9. Is. 16. - Ст.2100131. - ISSN 2195-1071, DOI 10.1002/adom.202100131
Примечания : Cited References: 44. - Z.Y. and Y.Z. contributed equally to this work. This research was supported by the National Natural Science Foundations of China (Grant Nos. 51972118 and 51961145101), International Cooperation Project of National Key Research and Development Program of China (No. 2021YFE0105700), Guangzhou Science & Technology Project (No. 202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01x137). This work was also funded by RFBR according to the research Project No. 19-52-80003
Предметные рубрики: LUMINESCENCE PROPERTIES
THERMAL-STABILITY
EU2+
GREEN
EU3+
SR
Аннотация: Discovering new Eu2+-doped red-emitting phosphors in oxide-based materials is a challenge for white light-emitting diode (WLED) applications. Herein, a highly efficient high-frequency induction heating method is employed to rapidly prepare the red-emitting Sr2Sc0.5Ga1.5O5:Eu2+ phosphors peaking at 614 nm and exhibiting a high photoluminescence quantum yield of 78.4% under the excitation of 440 nm. The structural and spectral analyses suggest that Eu2+ ions tend to enter the [Sc1/Ga1O6] and [Ga2O6] polyhedrons with small coordination numbers, leading to the broadband red emission originated from large crystal field splitting of Eu2+ 5d level. The chemical substitution of Ba in the Sr site enhances the thermal stability and helps to the photoluminescence tuning from 614 to 728 nm in SrBaSc0.5Ga1.5O5:Eu2+. The WLED device fabricated by blending the red Sr1.7Ba0.3Sc0.5Ga1.5O5:Eu2+ and yellow Y3(Al, Ga)5O12:Ce3+ phosphors shows a high color-rendering index (Ra = 91.1), and low color-correlated temperature (CCT = 4750 K). This study aims to provide a new synthesis method and design principle for guiding the development of Eu2+-doped oxide-based red phosphors with low preparation cost; moreover, the photoluminescence tuning strategy via cation substitutions is essential to achieve tunable emission, even the near-infrared luminescence.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xiang J., Zheng J., Zhou Z., Suo H., Zhao X., Zhou X., Zhang N., Molokeev M. S., Guo C.
Заглавие : Enhancement of red emission and site analysis in Eu2+ doped new-type structure Ba3CaK(PO4)3 for plant growth white LEDs
Место публикации : Chem. Eng. J. - 2019. - Vol. 356. - P.236-244. - ISSN 13858947 (ISSN) , DOI 10.1016/j.cej.2018.09.036
Примечания : Cited References: 42. - This work was supported by National Natural Science Foundation of China (No. 11704312 , 51672215 , 11274251 ), Research Fund for the Doctoral Program of Higher Education of China (RFDP) (No. 20136101110017) and by RFBR (17-52-53031).
Ключевые слова (''Своб.индексиров.''): phosphor--ba3cak(po4)3--sites-dependent photoluminescence--plant growth--white leds
Аннотация: A novel compound Ba3CaK(PO4)3 (BCKP) with new-type structure was synthesized and its structure was determined by X-ray diffraction Rietveld refinement, in which crystal structure consists of Ba1O9, Ba2O12, Ba3O9, CaO8 and KO10 polyhedra, that's five cationic sites. As a phosphor host, Eu2+ doped BCKP emits cold white light with about 90% quantum efficiency (QE) through entering different cationic sites. Based on the results of refinement, three Eu2+ luminescence centers in sites Ca, Ba2 and K were clearly assigned in Eu2+ solely doped BCKP by the time-resolved emission spectra (TRES), Van Uitert equation, but the emissions of Eu2+ at Ba1 and Ba3 sites are not easy to be determined for the same coordination number (CN). According to their different spatial distribution of the coordinated atoms, the first-principles calculation was used to compute the d orbital splitting energy of Eu2+ ions in Ba1 and Ba3 sites to accurately distinguish the ambiguous luminescence centers. In order to meet the requirement of plant growth spectra, Mn2+ was introduced into BCKP: Eu2+ to enhance the red component of spectra, which not only perfectly match with the absorption spectra of carotenoid and chlorophyll-b, but also LEDs fabricated through combining 365 nm near ultraviolet (n-UV) chip with BCKP: Eu2+, Mn2+ phosphor exhibit excellent parameters including high color rendering index (Ra) (92), excellent correlated color temperature (CCT) (4486 K) and outstanding QE up to 65%. Results confirmed that BCKP: Eu2+/Mn2+ phosphor with great potential applications in white LEDs and plant growth.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Софронова, Светлана Николаевна, Колесникова, Евгения Михайловна
Заглавие : Динамика решетки твердых растворов (Ba,Sr)TiO3
Коллективы : Российская академия наук, Научный совет по физике конденсированных сред РАН, Санкт-Петербургский государственный электротехнический университет, Физико-технический институт им. А.Ф. Иоффе РАН, Институт кристаллографии им. А.В. Шубникова РАН, Всероссийская конференция по физике сегнетоэлектриков
Место публикации : XVIII Всероссийская конференция по физике сегнетоэлектриков (ВКС-XVIII): тезисы/ сопредс. орг. ком. К. С. Александров и др. - СПб., 2008. - С. 45 (Шифр В37/X91-558643174)
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hao J., Tao M., Gao Z., Chen S., Liu Y., Wang H., Wei Y., Molokeev M. S., Li G.
Заглавие : Enhanced green emission and thermal stability of Ba3Si6O12N2:Eu2+ by Ce3+/P5+-doping: Unity energy transfer, charge compensation and lattice strain release
Место публикации : J. Lumines. - 2020. - Vol. 220. - Ст.116995. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2019.116995
Примечания : Cited References: 66. - This work is financially supported by the National Natural Science Foundation of China (NSFC No. 51672259 , 51601131 ) and the Fundamental Research Fund for National Universities , China University of Geosciences (Wuhan)
Аннотация: To optimize luminescence properties of oxonitridosilicate phosphors are extremely necessary for improving lighting quality of white light-emitting diodes (WLEDs). Herein, we designed Ce3+, Eu2+ codoping and P5+-Si4+ substitution in the presentative Ba3Si6O12N2:Eu2+ green phosphor to realize an enhancement of luminescence efficiency and thermal stability. Rietveld refinement results of Ce3+, Eu2+, P5+-doped Ba3Si6O12N2 (BSON) confirmed the formation of pure trigonal phase (P-3) of Ba3Si6O12N2 and the successful doping of Ce3+, Eu2+, P5+ ions. Ce3+ and Eu2+ ions randomly occupy two Ba crystallographic sites. Interestingly, a near unity energy transfer (ET, ~100%) from Ce3+ ions to Eu2+ ions is observed. Meanwhile, the doping of P5+ ions into BSON also helps improving the luminescence efficiency and thermal stability, which should be attributed to the charge compensation and the relax of lattice strain. In addition, the white light emitting diodes (WLEDs) fabricated by employing P5+-doped BSON: Eu2+ present a better electroluminescence performance than BSON: Eu2+. This study could serve as a guide in developing optimized oxonitridosilicates phosphors with improved luminescence performances based on complete energy transfer and lattice variations in local coordination environments through cation substitutions, and the as-prepared Ce3+/P5+-codoped Ba3Si6O12N2:Eu2+ could be an excellent green-emitting phosphor for UV-to-Visible LED chips pumped WLEDs.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Martynov S. N.
Заглавие : The incommensurate magnetic structure of a tetragonal antiferromagnet with antisymmetric exchange
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.979-988. - ISSN 1063-7761, DOI 10.1134/S1063776109120097
Примечания : Cited References: 34
Предметные рубрики: FLUCTUATION-INDUCED PHASE
FIELD-INDUCED GAP
COPPER METABORATE
WEAK FERROMAGNETISM
SOLITON LATTICE
SPIN-WAVES
CUB2O4
BA2CUGE2O7
CSCUCL3
CHAINS
Ключевые слова (''Своб.индексиров.''): anti-symmetric--antiferromagnetic sublattices--antiferromagnets--antisymmetric exchange--exchange bonds--ferromagnetic component--ferromagnetic moments--ginzburg-landau functional--incommensurate magnetic structures--mean field approximation--modulation vectors--polarization planes--polarization vectors--symmetry groups--antiferromagnetic materials--antiferromagnetism--crystal orientation--crystal symmetry--ferromagnetic materials--ferromagnetism--magnetic devices--magnetic structure--modulation--polarization--vector spaces--vectors--crystallography
Аннотация: Analysis of the incommensurate magnetic structure that emerges for two coexisting types of the antisymmetric Dzyaloshinski-Moriya exchange interaction (the weakly ferromagnetic component of vector D along the tetragonal axis and the helicoidal component distributed in the tetragonal plane) is carried out for the first time for a tetragonal antiferromagnet. The helicoidal component for each pair of interacting spins has a 2D distribution; its direction in the tetragonal plane depends on the direction of the exchange bond in each pair. The Lifshits invariant of the Ginzburg-Landau functional is obtained, which is responsible for the formation of an incommensurate magnetic structure for such a distribution. It is shown in the mean field approximation that the incommensurate magnetic structure that forms in this case is a nonlinear double helicoid with a modulation vector lying in the tetragonal plane and with a varying angle between the polarization planes of quasi-antiferromagnetic sublattices. The ground state of the magnet is degenerate in the orientation of the modulation vector in the tetragonal plane. The rate of variation in the orientations of moments in the polarization planes passing through the tetragonal axis is controlled by the angle between the directions of the moments and the tetragonal axis. The local weakly ferromagnetic moment remaining in the polarization plane varies in magnitude and sign. The relation between the orientations of the modulation and polarization vectors is derived for the cases of simple and inversion tetragonal axes in the space symmetry group of the crystal.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Martynov S. N.
Заглавие : Antisymmetric Exchange in the CuB2O4 A Subsystem
Место публикации : JETP Letters. - 2009. - Vol. 90, Is. 1. - P.55-58. - ISSN 0021-3640, DOI 10.1134/S0021364009130116
Примечания : Cited References: 31
Предметные рубрики: TRANSVERSE MAGNETIC-FIELD
FLUCTUATION-INDUCED PHASE
COPPER METABORATE
ANTIFERROMAGNETIC CHAINS
SOLITON LATTICE
INDUCED GAP
SPIN-WAVES
BA2CUGE2O7
CSCUCL3
MNSI
Аннотация: The space distribution of the components of the microscopic Hamiltonian of the antisymmetric Dzyaloshinskii-Moriya exchange with respect to the exchange bond pairs of the A subsystem of Cu2+ ions in the crystallographic 4b positions of CuB2O4 has been obtained using symmetry analysis. The possibility of the coexistence of two different types of the exchange spatial distribution is demonstrated. The component of the anti-symmetric exchange vector D parallel to the tetragonal axis has a weakly ferromagnetic distribution for all of the directions of the bonds between the nearest magnetic neighbors. Each exchange bond has an additional component of the antisymmetric exchange parallel to the bond projection on the tetragonal plane. The spatial distribution of these components is helicoidal with the modulation vector in the tetragonal crystal plane.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chubukov A. V., Eremin I., Korshunov M. M.
Заглавие : Theory of Raman response of a superconductor with extended s-wave symmetry: Application to the iron pnictides
Коллективы : NSF [DMR 0604406]; Asian-Pacific Center for Theoretical Physics; Volkswagen Foundation [I/82203]; RMHE Program "Development of scientific potential" [N1 2.1.1/298.5]; RFBR [09-02-00127]
Разночтения заглавия :авие SCOPUS: Theory of Raman response of a superconductor with extended s -wave symmetry: Application to the iron pnictides
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2009. - Vol. 79, Is. 22. - Ст.220501. - ISSN 1098-0121, DOI 10.1103/PhysRevB.79.220501
Примечания : Cited References: 48. - We acknowledge useful conversations with G. Blumberg, W. Brenig, H.-Y. Choi, D. V. Efremov, A. Sacuto, M. Vavilov, and A. Vorontsov. A. V. C. acknowledges support from NSF (Contract No. NSF-DMR 0604406). I. E. acknowledges partial support from the Asian-Pacific Center for Theoretical Physics, the Volkswagen Foundation (Contract No. I/82203), and the RMHE Program "Development of scientific potential" (Contract No. N1 2.1.1/298.5). M. M. K. acknowledges support from RFBR (Grant No. 09-02-00127) and RAS program on "Low temperature quantum phenomena."
Предметные рубрики: LAYERED SUPERCONDUCTOR
SCATTERING
BA0.6K0.4FE2AS2
Аннотация: We argue that Raman study of Fe-pnictides is a way to unambiguously distinguish between various superconducting gaps proposed for these materials. We show that A(1g) Raman intensity develops a true resonance peak below 2 Delta if the pairing gap has A(1g) symmetry in the folded Brillouin zone (Delta(k=0)=Delta, Delta(pi, pi)=-Delta). No such peak develops for a pure s-wave gap, a d-wave gap, and an extended s-wave gap with Delta(k) =Delta cosk(x)/2cosk(y)/2. We show that the peak remains quite strong for the values of interpocket impurity scattering used to fit NMR data.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M., Bondarev V., Sciau P., Savariault J. M.
Заглавие : Heat capacity study of relaxors BaTi0.65Zr0.35O3 and BaTi0.60Zr0.40O3
Разночтения заглавия :авие SCOPUS: Heat capacity study of relaxors BaTi0.65Zr0.35O 3 and BaTi0.60Zr0.40O3
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2006. - Vol. 18, Is. 17. - P.4407-4416. - ISSN 0953-8984, DOI 10.1088/0953-8984/18/17/026
Примечания : Cited References: 21
Предметные рубрики: CERAMICS
BA(TI1-XZRX)O-3
BATIO3
Ключевые слова (''Своб.индексиров.''): calorimetry--composition--data reduction--lead compounds--mathematical models--permittivity--specific heat--adiabatic calorimetry--burns temperature--diffuse anomalies--barium compounds
Аннотация: The heat capacity of two relaxors BaTi(1-x)ZrxO(3) (x = 0.35, 0.40) was measured using adiabatic calorimetry in the temperature range 100-360 K. The Cp(T) dependence of both compositions is characterized by the presence of two diffuse anomalies near the Burns temperature T-d and the temperature of the maximum in permittivity T-m in the temperature ranges 250-350 K and 120 200 K. The anomalous heat capacity near T-d was analysed taking into account the distribution of Zr concentration in nanoregions leading to the distribution of their transition temperatures into the polar phase. Excess heat capacity near Tm was discussed in the framework of the spherical random bond-random field model. The results are compared with the data obtained by the same procedures for PbMg1/3Nb2/3O3 studied experimentally earlier.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Patrin G. S., PETRAKOVSKII G. A., KHARITONOV I. E.
Заглавие : Detection of magneto-dependent higher harmonics in htsc ceramics via the change of the low field microwave response under the passing of an alternating-current
Место публикации : Phys. Lett. A. - 1991. - Vol. 158, Is. 3-4. - P.167-170. - ISSN 0375-9601, DOI 10.1016/0375-9601(91)90921-T
Примечания : Cited References: 15
Предметные рубрики: BA-CU-O
GENERATION
STATE
Аннотация: The results of an investigation on the generation of higher harmonics under the passing of a low frequency current in HTSC ceramics by microwave spectroscopy methods are presented. It is found that the generation of only even harmonics occurs. The dependence of the signal upon the harmonic number and. as an example for the second harmonic, the temperature dependences of the microwave response parameters are discussed.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : PETRAKOVSKII G. A., PATRIN G. S., USTYUZHANIN Y. N., SABLINA K. A., STEPANOV G. N.
Заглавие : DC-EFFECT ON THE MICROWAVE RESPONSE IN THE SUPERCONDUCTING CERAMICS HO-BA-CU-O
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 1989. - Vol. 72, Is. 8. - P759-762. - ISSN 0038-1098, DOI 10.1016/0038-1098(89)90903-4
Примечания : Cited References: 18
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Bezmaternykh L. N., Gudim I. A., Sheptyakov D., Bayukov O. A., Vorotynov A. M., Velikanov D. A., Bovina A. F.
Заглавие : Synthesis and properties of barium ferrigermanate Ba2Fe2GeO7
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 11. - P2114-2118. - ISSN 1063-7834
Примечания : Cited References: 14
Предметные рубрики: COPPER METABORATE
Аннотация: The magnetic susceptibility and specific heat of single crystals of the Ba2Fe2GeO7 barium ferrigermanate are investigated. It is revealed that the temperature dependence of the magnetic susceptibility exhibits a kink at a temperature T = 8.5 K. The number of nonequivalent positions of Fe3+ ions and their occupancies are determined using Mossbauer spectroscopy. It is shown that the Fe3+ ions located in tetrahedral positions T2 are ordered incompletely, which is inconsistent with the results obtained previously. An assumption is made regarding the possible ground magnetic state of the Ba2Fe2GeO7 compound. (c) 2005 Pleiades Publishing, Inc.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Volkov V. Y., Patrin G. S., Bidman T. A., Kiselev N. I., Vasilyev V. N.
Заглавие : Synthesis and physical-properties of high-temperature superconductors of system Tl-Ca-Ba-Cu-O
Место публикации : Izvestiya vysshikh uchebnykh zavedenii Fizika. - 1990. - Vol. 33, Is. 9. - P.+18-22. - ISSN 0021-3411; \b Russian Physics Journal; \b Известия высших учебных заведений. Физика
Примечания : Cited References: 6
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