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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Prus A. G., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Angular dependence of the magnetoresistance in Y3/4Lu1/4Ba2Cu3O7-CuO composites at 77 K
Разночтения заглавия :авие SCOPUS: Angular dependence of the magnetoresistance in Y3/4Lu 1/4Ba2Cu3O7-CuO composites at 77 K
Место публикации : Tech. Phys. Lett.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 32, Is. 8. - P677-679. - ISSN 1063-7850, DOI 10.1134/S1063785006080128
Примечания : Cited References: 16
Предметные рубрики: CERAMIC SUPERCONDUCTORS
MAGNETIC-FIELD
MICROSTRUCTURE
BOUNDARIES
TRANSPORT
MOTION
FILMS
Аннотация: The angular dependence of the magnetoresistance of polycrystalline Y3/4Lu1/4Ba2Cu3O7-CuO composites has been studied. These composites represent a system of Josephson junctions and exhibit a large magnetoresistance at 77 K. In addition to the isotropic component, there is the angle-dependent component proportional to sin(2)theta, where theta is the angle between the directions of current and magnetic field. This behavior is unambiguous evidence for the process of flux flow in the Josephson medium realized in the composites.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zherikhina L. N., Tskhovrebov A. M., Klinkova L. A., Balaev D. A., Popkov S. I., Shaikhutdinov K. A.
Заглавие : Ba0.6K0.4BiO3 single crystal as a multiple Josephson system: New coherent effect?
Коллективы : International Conference on Low Temperature Physics
Место публикации : Journal of Physics: Conference Series. - 2012. - Vol. 400, Pt. 2. - Ст.022146. - P. - ISSN 1742-6588, DOI 10.1088/1742-6596/400/2/022146
Ключевые слова (''Своб.индексиров.''): antiphase--coherent effect--electric transport--high-t--inhomogeneous superconductors--josephson--josephson junctions--josephson tunneling--non-linear i-v--polycrystalline samples--superconducting gaps--superconducting state--low temperature effects--low temperature engineering--magnetic fields--superconductivity--single crystals
Аннотация: The existence of space inhomogeneous superconductor insulator state (SISIS) found out earlier in polycrystalline samples of high-Tc system Ba0.6K0.4BiO3 (Tc?30 K) is confirmed on Ba0.6K0.4BiO3 single crystal. At T* (T*<Tc, T*?17 K) the transition from the homogeneous superconducting state into the SISIS occurs. SISIS is characterized by the appearance of two gapes on the Fermi surface: semi- and superconducting, that are modulated in space in antiphase, the electric transport between superconducting regions being carried out due to Josephson tunneling. Thus the whole sample becomes a multiple Josephson system. Nonlinear I-V curves, depended on temperature and magnetic field, that are typical to a Josephson system, are observed on Ba0.6K0.4BiO3 single crystal at temperatures below T*. Besides, a step like peculiarity at the values of voltage of the order of one and two superconducting gaps shows up. These peculiarities are suppressed by magnetic field much earlier then critical current. Perhaps the last phenomenon is the consequence of "coherent" state of several successive Josephson junctions, appeared in the exfoliation state. В© Published under licence by IOP Publishing Ltd.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Gokhfeld D. M.
Заглавие : Developing a concept of an effective field in the intergrain medium of a granular superconductor: Effect of the intragrain Meissner currents and Abrikosov vortices trapped in grains on the magnetotransport properties of a Y-Ba-Cu-O granular HTS
Колич.характеристики :18 с
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 7-9. - P.1631-1648. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06608-2. - ISSN 15571947 (eISSN)
Примечания : Cited References: 58. - The authors are grateful to M.I. Petrov, A.D. Balaev, and V.M. Sosnin for fruitful discussions and A.V. Shabanov and I.V. Nemtsev for scanning electron microscopy investigations. The scanning electron microscopy investigations and a part of magnetic measurements (performed on a LakeShore VSM 8604 facility) were carried out at the Krasnoyarsk Regional Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences. The study is performed within the state assignment of Kirensky Institute of Physics
Аннотация: Granular high-temperature superconductors (HTSs) are characterized by the hysteretic field dependences of magnetoresistance R(H) and critical current IC(H). These hysteretic effects are described within the concept of an effective field in the intergrain medium. The effective field is a superposition of external magnetic field H and the field induced by the magnetic moments of superconducting grains into intergrain spacings (grain boundaries). The magnetization of superconducting grains is determined by two contributions: Meissner (shielding) currents (MC) and trapped magnetic fluxes (Abrikosov vortices (AV)). To develop the concept of an effective field in the intergrain medium, the magnetotransport properties (R and IC) have been compared for two cases: (AV) the magnetization of superconducting grains is only determined by the trapped magnetic flux (zero external field) and (MC) HTS grains are in the Meissner state (the external field is weaker than the first critical field of grains). In a set of experiments, the main features of the hysteretic R(H) and M(H) dependences have been illustrated and the external conditions for implementing the AV and MC states have been established. It has been found that the effects of the Abrikosov vortices and intragrain Meissner currents on an effective field in the intergrain medium at the same magnetization values are noticeably different. This is a nontrivial fact that requires a thorough study of the impact of the anisotropy of the superconducting properties of grains on the configuration of the Meissner currents in them, as well as on the orientation of vortices both inside grains and near their surface. We suggest the explanation of observed stronger effect of the Meissner currents on the intergrain medium as compared with the effect of the Abrikosov vortices.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wang Z. Y., Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Liu Q. L.
Заглавие : Blue-shift of Eu2+ emission in (Ba,Sr)3Lu(PO4)3:Eu2+ eulytite solid-solution phosphors resulting from release of neighbouring-cation-induced stress
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2014. - Vol. 43, Is. 44. - P.16800-16804. - ISSN 1477-9226, DOI 10.1039/c4dt02319f. - ISSN 1477-9234
Примечания : Cited References: 16. - The present work was supported by the National Natural Science Foundations of China (grant no. 51002146, no. 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in the University of the 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 New Ceramics and Fine Processing, Tsinghua University (KF201306). V.V.A. is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: TUNABLE COLOR TONE
EXCITED WHITE LEDS
CRYSTAL-STRUCTURE
TEMPERATURE
IONS
Аннотация: A series of iso-structural eulytite-type (Ba,Sr)(3)Lu(PO4)(3):Eu2+ solid-solution phosphors with different Sr/Ba ratios were synthesized by a solid-state reaction. Crystal structures of (Ba,Sr)(3)Lu(PO4)(3):Eu2+ were resolved by the Rietveld method, which shows an eulytite-type cubic Bi-4(SiO4)(3) structure with cations disordered in a single C-3 site while the oxygen atoms were distributed over two partially occupied sites. The emission peaks of Ba(3-x)SrxLu(PO4)(3):Eu2+ (0
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Ospishchev S. V., Shaikhutdinov K. A., Khrustalev B. P., Aleksandrov K. S.
Заглавие : Characteristics of current flow in composites made from a high-temperature superconductor and the low-temperature superconducting metal oxide Ba(PbBi)O-3
Место публикации : Phys. Solid State: American Institute of Physics, 1997. - Vol. 39, Is. 3. - P.362-368. - ISSN 1063-7834, DOI 10.1134/1.1130134
Примечания : Cited References: 21
Предметные рубрики: BAPB1-XBIXO3 SYSTEM
YBA2CU3O7-DELTA
Аннотация: Composites are prepared from a high-temperature superconductor with the 1-2-3 structure and the low-temperature oxide BaPb3/4Bi1/4O3 with various volume concentrations of the high-temperature and low-temperature superconductors. The temperature dependences of the electrical resistivities and critical current densities of the composites are measured. It is shown experimentally that these composites comprise a synthetically created network of Josephson weak links (with a specified degree of coupling). (C) 1997 American Institute of Physics.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji, Haipeng, Huang, Zhaohui, Xia, Zhiguo, Molokeev M. S., Jiang, Xingxing, Lin, Zheshuai, Atuchin V. V.
Заглавие : Comparative investigations of the crystal structure and photoluminescence property of eulytite-type Ba3Eu(PO4)3 and Sr3Eu(PO4)3
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2015. - Vol. 44, Is. 16. - P.7679-7686. - ISSN 1477, DOI 10.1039/c4dt03887h. - ISSN 14779234(eISSN)
Примечания : Cited References:65. - This work was supported by the National Natural Science Foundations of China (grant no. 51032007, no. 51002146, no. 51272242), the Research Fund for the Doctoral Program of Higher Education of China (grant no. 20130022110006), Natural Science Foundations of Beijing (2132050), and the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047) and Beijing Youth Excellent Talent Program (YETP0635). VVA is partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: LIGHT-EMITTING-DIODES
DOPED Sr3Gd(PO4(3 PHOSPHOR
EFFICIENT
Аннотация: In this study, the Ba3Eu(PO4)3 and Sr3Eu(PO4)3 compounds were synthesized and the crystal structures were determined for the first time by Rietveld refinement using powder X-ray diffraction (XRD) patterns. Ba3Eu(PO4)3 crystallizes in cubic space group I3d, with cell parameters of a = 10.47996(9) Å, V = 1151.01(3) Å3 and Z = 4; Ba2+ and Eu3+ occupy the same site with partial occupancies of 3/4 and 1/4, respectively. Besides, in this structure, there exists two distorted kinds of the PO4 polyhedra orientation. Sr3Eu(PO4)3 is isostructural to Ba3Eu(PO4)3 and has much smaller cell parameters of a = 10.1203(2) Å, V = 1036.52(5) Å3. The bandgaps of Ba3Eu(PO4)3 and Sr3Eu(PO4)3 are determined to be 4.091 eV and 3.987 eV, respectively, based on the UV–Vis diffuse reflectance spectra. The photoluminescence measurements reveal that, upon 396 nm n-UV light excitation, Ba3Eu(PO4)3 and Sr3Eu(PO4)3 exhibit orange-red emission with two main peaks at 596 nm and prevailing 613 nm, corresponding to the 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+, respectively. The dynamic disordering in the crystal structures contributes to the broadening of the luminescence spectra. The electronic structure of the phosphates was calculated by the first-principles method. The analysis elucidats that the band structures are mainly governed by the orbits of phosphorus, oxygen and europium, and the sharp peaks of the europium f-orbit occur at the top of the valence bands.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Shaihutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Controlled magnetoresistance in Y3/4Lu1/4Ba2Cu3O7-CuO composites at 77 K
Разночтения заглавия :авие SCOPUS: Controlled magnetoresistance in Y3/4Lu1/4Ba 2Cu3O7-CuO composites at 77 K
Место публикации : Tech. Phys. Lett.: AMER INST PHYSICS, 2003. - Vol. 29, Is. 7. - P578-581. - ISSN 1063-7850, DOI 10.1134/1.1598555
Примечания : Cited References: 17
Предметные рубрики: SUPERCONDUCTOR
Аннотация: We have studied the low-temperature magnetoresistance of Y3/4Lu1/4Ba2Cu3O7-CuO composites obtained by fast sintering technique and established a relation between the probing to critical current density ratio j/j(c) and the shape of the magnetoresistance curve rho(H). For j/j(c) 1, the electric resistance arises at a threshold value of the magnetic field strength H-c. For j/j(c) greater than or equal to 1, a linear variation of rho(H) at 77 K in the range from 0 to 14 Oe can be provided by selecting the CuO content (in the 15-30 vol % interval) and the j value (in the 0.003-0.2 A/cm(2) range). In the latter case, the slope drho/dH (i.e., the sensitivity of the electric resistivity with respect to the magnetic field) is 1-20 mOmega cm/Oe and the relative field-induced increase in the resistivity rho(0)
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10.

Вид документа :
Шифр издания :
Автор(ы) : Петров, Михаил Иванович, Balaev D. A., Ospishchev S. V., Шайхутдинов, Кирилл Александрович, Khrustalev B. P., Aleksandrov K. S.
Заглавие : Critical currents in bulk Y3/4Lu1/4Ba2Cu3O7 + BaPbO3 composites
Место публикации : Physics Letters, Section A: General, Atomic and Solid State Physics. - 1997. - Vol. 237, Is. 1-2. - P.85-89
Предметные рубрики: HIGH-TC-SUPERCONDUCTORS
WEAK LINKS
JUNCTIONS
Ключевые слова (''Своб.индексиров.''): bulk composites--critical current density--network of weak s-n-s links--ybacuo + bapbo3--ybacuo+bapbo3 bulk composites--network of weak s-n-s links--critical current density
Аннотация: Bulk composites Y3/4Lu1/4Ba2Cu3O7 + BaPbO3 with BaPbO3 volume content of 0-60% have been prepared. Temperature dependences of resistance and critical current density Jc(T) are presented. The best agreement of experimental Jc(T) with theory has been reached for the Gunsenheimer-Schussler-Kummel consideration of superconductor-normal metal-superconductor (S-N-S) junctions in the "clean" limit. В© 1997 Elsevier Science B.V.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Ospishchev S. V., Shaihutdinov K. A., Khrustalev B. P., Aleksandrov K. S.
Заглавие : Critical currents in bulk Y3/4Lu1/4Ba2Cu3O7+BaPbO3 composites
Место публикации : Phys. Lett. A. - 1997. - Vol. 237, Is. 1-2. - P.85-89. - ISSN 0375-9601, DOI 10.1016/S0375-9601(97)00694-4
Примечания : Cited References: 24
Предметные рубрики: HIGH-TC-SUPERCONDUCTORS
WEAK LINKS
JUNCTIONS
Ключевые слова (''Своб.индексиров.''): ybacuo+bapbo3 bulk composites--network of weak s-n-s links--critical current density
Аннотация: Bulk composites Y3/4Lu1/4Ba2Cu3O7 + BaPbO3 with BaPbO3 volume content of 0-60% have been prepared. Temperature dependences of resistance and critical current density J(c)(T) are presented. The best agreement of experimental J(c)(T) with theory has been reached for the Gunsenheimer-Schussler-KUmmel consideration of superconductor-normal metal-superconductor (S-N-S) junctions in the "clean" limit. (C) 1997 Elsevier Science B.V.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popkov S. I., Balaev D. A., Shaihutdinov K. A., Petrov M. I.
Заглавие : Crossover from S-I-S to S-F-S junctions in composites Y3/4Lu1/4Ba2Cu3O7+Y-3(Al1-xFex)(5)O-12
Разночтения заглавия :авие SCOPUS: Crossover from S-I-S to S-F-S junctions in composites Y3/4Lu1/4Ba2Cu3O7 + Y3(Al1-xFex)5O12
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2007. - Vol. 460: 8th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (JUL 09-14, 2006, Dresden, GERMANY). - P1311-1312. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.03.348
Примечания : Cited References: 4
Ключевые слова (''Своб.индексиров.''): s-f-s structures--high-t-c superconductors--high-tc superconductors--s-f-s structures--ferrimagnetic materials--garnets--josephson junction devices--magnetization--transport properties--yttrium alloys--critical concentration--ferrimagnet junctions--magneto-active ions--super current carriers--high temperature superconductors
Аннотация: The transport properties of the two phases composites based on Y3/4Lu1/4Ba2Cu3O7 (YBCO) and Y-3(Al1-xFex)(5)O-12 (X = 0-0... 1.0) have been studied to investigate the effect of magnetic ordering in garnet on superconducting properties of the composites. The composites represent network of Josephson junctions where the non-superconducting ingredient (garnet) acts as barriers separating YBCO grains. It is found that magneto-active ions (Fe) in garnet are responsible for an additional suppression of Josephson coupling in the composites. At some critical concentration of Fe atoms full suppression of super current is observed in a temperature range from T-C of YBCO grains down to the characteristic temperature T,,,. This behavior is attributed to the interaction of super current carriers with spins of Fe atoms located in the barriers. The crossover from S-I-S (S-superconductor, I-insulator) to S-F-S (F-ferrimagnet) junctions is observed in the compdsites Y3/4Lu1/4Ba2Cu3O7 + Y-3(Al1-xFex)(5)O-12 with x increase. (c) 2007 Elsevier B.V. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd D. M., Шайхутдинов, Кирилл Александрович, Ospishchev S. V., Aleksandrov K. S.
Заглавие : Crossover from the "clean" limit to the "dirty" limit in a network of S-N-S weak links in Y3/4Lu1/4Ba 2Cu3O7 + BaPb1-xSnxO 3 (0 ≤ x ≤ 0.25)
Место публикации : Phys. Solid State. - 2004. - Vol. 46, Is. 10. - P.1792-1797. - ISSN 1063-7834, DOI 10.1134/1.1809407
Аннотация: Composites with a network of "superconductor-normal metal-superconductor" (S-N-S) weak links are prepared from a Y 3/4LU1/4Ba2Cu3O7 high-temperature superconductor and BaPb1-xSnxO 3 (0 ≤ x ≤ 0.25) metal oxides. It is found that an increase in the tin content x in the nonsuperconducting component of the composite leads to an increase in the electrical resistivity ρ and, hence, to a decrease in the mean free path l of charge carriers. The temperature dependences of the electrical resistivity ρ(T) and critical current jC(T) of the composites are analyzed in the framework of the de Gennes theory of S-N-S junctions. It is demonstrated that the network of weak links in the composites is characterized by a crossover from the "clean" limit (l ≥ L) to the "dirty" limit (l ≤ L) (where L is the effective thickness of N interlayers between high-temperature superconductor grains). © 2004 MAIK "Nauka/Interperiodica".
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14.

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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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji, Haipeng, Huang, Zhaohui, Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Fang, Minghao, Liu, Yangai
Заглавие : Discovery of new solid solution phosphors via cation substitution-dependent phase transition in M-3(PO4)2:Eu2+ (M =Ca/Sr/Ba) quasi-binary sets
Место публикации : J. Phys. Chem. C: American Chemical Society, 2015. - Vol. 119, Is. 4. - P.2038-2045. - ISSN 1932-7447, DOI 10.1021/jp509743r
Примечания : Cited References:48. - This work was supported by the National Natural Science Foundations ofChina (Grant Nos. 51032007, 51002146, and 51272242), the Research Fundfor the Doctoral Program of Higher Education of China (Grant No.20130022110006), the Natural Science Foundations of Beijing (2132050),the Program for New Century Excellent Talents in University of Ministryof Education of China (NCET-12-0950), the Beijing Nova Program(Z131103000413047), and Beijing Youth Excellent Talent Program(YETP0635). V.V.A. acknowledges the Ministry of Education and Science ofthe Russian Federation for financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
LUMINESCENCE PROPERTIES
ENERGY-TRANSFER
Аннотация: The cation substitution-dependent phase transition was used as a strategy to discover new solid solution phosphors and to efficiently tune the luminescence property of divalent europium (Eu2+) in the M3(PO4)2:Eu2+ (M = Ca/Sr/Ba) quasi-binary sets. Several new phosphors including the greenish-white SrCa2(PO4)2:Eu2+, the yellow Sr2Ca(PO4)2:Eu2+, and the cyan Ba2Ca(PO4)2:Eu2+ were reported, and the drastic red shift of the emission toward the phase transition point was discussed. Different behavior of luminescence evolution in response to structural variation was verified among the three M3(PO4)2:Eu2+ joins. Sr3(PO4)2 and Ba3(PO4)2 form a continuous isostructural solid solution set in which Eu2+ exhibits a similar symmetric narrow-band blue emission centered at 416 nm, whereas Sr2+ substituting Ca2+ in Ca3(PO4)2 induces a composition-dependent phase transition and the peaking emission gets red shifted to 527 nm approaching the phase transition point. In the Ca3?xBax(PO4)2:Eu2+ set, the validity of crystallochemical design of phosphor between the phase transition boundary was further verified. This cation substitution strategy may assist in developing new phosphors with controllably tuned optical properties based on the phase transition.
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16.

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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17.

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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji H., Huang Z., Xia Z., Xie Y, Molokeev M. S., Atuchin V. V.
Заглавие : Facile solution-precipitation assisted synthesis and luminescence property of greenish-yellow emitting Ca6Ba(PO4)4O:Eu2+ phosphor
Место публикации : Mater. Res. Bull.: Elsevier, 2016. - Vol. 75. - P.233-238. - ISSN 00255408 (ISSN), DOI 10.1016/j.materresbull.2015.11.055
Примечания : Cited References: 22. - This work was partly supported by the National Natural Science Foundations of China (grant nos. 51272242, 51472222, 51511130035), the Research Fund for the Doctoral Program of Higher Education of China (grant no. 20130022110006), and the Russian Foundation for Basic Research (grant no. 15-52-53080 GFEN_a). VVA was partly supported by the Ministry of Education and Science of the Russian Federation
Предметные рубрики: SOLID-SOLUTION PHOSPHORS
PHOTOLUMINESCENCE PROPERTIES
VIBRATIONAL PROPERTIES
ENERGY-TRANSFER
DIODES
Ключевые слова (''Своб.индексиров.''): optical materials--luminescence--optical properties--crystal structure--phosphors
Аннотация: Greenish-yellow emitting microcrystalline Ca6Ba(PO4)4O:Eu2+ phosphor was successfully prepared by a solution-precipitation assisted high temperature reaction method. Phase structure, morphology and/or luminescence properties of the precursor and the as-prepared phosphors were characterized. The phase-pure Ca6Ba(PO4)4O:Eu2+ phosphors were obtained with smooth grain surface and particle size of 2–8 μm. Ca6Ba(PO4)4O:Eu2+ exhibits bright greenish-yellow color emission with its maximum at 540 nm upon UV-blue light excitation. The maximum position of the broad emission band is independent on the calcination temperature. The emission intensity increases with increasing calcination temperature due to improved crystallinity. Besides, the presence of two Eu2+ emission centers in the Ca6Ba(PO4)4O crystal lattice was confirmed and the coordination effects are considered concerning the roles of isolated O atoms and those from the PO4 tetrahedra.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Roessli B., Schefer J., Petrakovskii G. A., Ouladdiaf B., Boehm M., Staub U., Vorotinov A. M., Bezmaternikh L. N.
Заглавие : Formation of a magnetic soliton lattice in copper metaborate
Место публикации : Phys. Rev. Lett.: AMERICAN PHYSICAL SOC, 2001. - Vol. 86, Is. 9. - P1885-1888. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.86.1885
Примечания : Cited References: 26
Предметные рубрики: SPIN-WAVES
BA2CUGE2O7
TRANSITION
ANTIFERROMAGNET
CUGEO3
PHASE
Ключевые слова (''Своб.индексиров.''): anisotropy--antiferromagnetism--ground state--magnetic moments--magnetic properties--magnetization--neutron diffraction--neutron scattering--phase transitions--solitons--thermal effects--antiferromagnetic state--copper metaborate--higher order magnetic satellites--magnetic soliton lattice--magnetic structure--copper compounds
Аннотация: The magnetic ground state of CuB2O4 is incommensurate at T = 1.8 K and undergoes a continuous phase transition to a noncollinear commensurate antiferromagnetic state at T* similar to 10 K. Close to T* higher-order magnetic satellites are observed. Coexistence of long- and short-range magnetic order is observed in both magnetic phases. This suggests that the association of the Dzyaloshinskii-Moriya interaction and anisotropy leads to the formation of a magnetic soliton lattice.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yang, Zhiyu, Zhao, Yifei, Zhou, Yayun, Qiao, Jianwei, Chuang, Yu-Chun, Molokeev M. S., Xia, Zhiguo
Заглавие : Giant red-shifted emission in (Sr,Ba)Y2O4:Eu2+ phosphor toward broadband near-infrared luminescence
Коллективы : International Cooperation Project of National Key Research and Development Program of China [2021YFE0105700]; National Natural Science Foundations of ChinaNational Natural Science Foundation of China (NSFC) [51972118, 51961145101]; Guangzhou Science & Technology Project [202007020005]; Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program [2017BT01X137]; RFBRRussian Foundation for Basic Research (RFBR) [19-52-80003]
Место публикации : Adv. Funct. Mater. - 2022. - Vol. 32, Is. 1. - Ст.2103927. - ISSN 1616-301X, DOI 10.1002/adfm.202103927. - ISSN 1616-3028(eISSN)
Примечания : Cited References: 60. - This research was supported by the International Cooperation Project of National Key Research and Development Program of China (2021YFE0105700), National Natural Science Foundations of China (Grant No. 51972118 and 51961145101), Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work is also funded by RFBR according to the research project No. 19-52-80003
Предметные рубрики: LIGHT-SOURCES
PHOTOLUMINESCENCE
TRANSITION
CE3+
BLUE
SUBSTITUTION
Аннотация: Near-infrared (NIR) light-emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR-emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu2+-activated SrY2O4 red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY2O4:Eu2+ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant red-shifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY2O4:Eu2+. The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O6] and [Y2/Eu2O6]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As-fabricated NIR phosphor-converted LEDs demonstration shows its potential in night-vision technologies. This study reveals the NIR luminescence mechanism of Eu2+ in oxide-based hosts and provides a design principle for exploiting Eu2+-doped NIR phosphors with good thermal stability.
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