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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Abramova G. M., Sokolov V., Petrakovskiy G. A., Mita Y., Kagayama T., Bovina A. F., Pichyugin A.
Заглавие : 3d-substitution design in a Mott insulator MnS
Коллективы : Russian-Japanese Workshop "State of Materials Research and New Trends in Material Science"
Место публикации : Russian-Japanese Workshop "State of Materials Research and New Trends in Material Science". - 2009. - P.45-47
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Astakhov A. M., Antishin D. V., Revenko V. A., Vasiliev A. D., Buka E. S.
Заглавие : A simple method for the preparation of 3,5-dinitrimino-1,2,4-triazole and its salts
Место публикации : Chem. Heterocycl. Compds.: Springer, 2017. - Vol. 53, Is. 6-7. - P.722-727. - ISSN 0009-3122, DOI 10.1007/s10593-017-2116-7. - ISSN 1573-8353(eISSN)
Примечания : Cited References:33
Предметные рубрики: ENERGETIC MATERIALS
DERIVATIVES
2-NITROGUANIDINE
Ключевые слова (''Своб.индексиров.''): 3,5-dinitramino-1,2,4-triazole--3,5-dinitrimino-1,2,4-triazole--1,2,4-triazoles--energetic compounds--nitramines--nitrimines--nucleophilic substitution
Аннотация: The reaction of 2-methyl-1-nitrD 3/4 isothiourea with hydrazine in the presence of alkali metal bicarbonates (carbonates) resulted in the formation of 3,5-dinitrimino-1,2,4-triazole salts. The same salts were also formed by a reaction of 2-methyl-1-nitrD 3/4 isothiourea with alkali metal salts of 4-nitrD 3/4 semicarbazide. This represents the first synthesis and characterization of the high-energy 3,5-dinitrimino-1,2,4-triazole, which can be readily isolated by treatment of its disodium salt with HCl.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Grankina V. A., Kartashev A. V.
Заглавие : A study of the effect of gradual substitution NH4 - Cs on phase transitions in NH4LiSO4 crystals
Разночтения заглавия :авие SCOPUS: A study of the effect of gradual substitution NH4 Cs on phase transitions in NH4LiSO4 crystals
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2002. - Vol. 44, Is. 2. - P379-385. - ISSN 1063-7834, DOI 10.1134/1.1451032
Примечания : Cited References: 22
Предметные рубрики: MIXED-CRYSTALS
TEMPERATURE PHASE
LINH4SO4
BIREFRINGENCE
SULFATE
RAMAN
Аннотация: Solid solutions in the Cs-x(NH4)(1 - x)LiSO4 (0 less than or equal to x less than or equal to 0.35) system are grown and investigated. The birefringence (n(a) - n(b)) and the heat capacity are measured in the temperature range 100-530 K. The (x-T) phase diagram is constructed. It is demonstrated that the substitution of cesium for ammonium in the NH4LiSO4 crystal affects the transition temperatures in such a way that the region of the ferroelectric phase increases and the ferroelastic phase disappears at x 0.22. The character of the high-temperature transition remains unchanged (2beta = 0.24 +/- 0.01 for all compositions), but the birefringence anomaly and enthalpy decrease. As the concentration x increases, the low-temperature transition becomes more similar to a first-order transition: the birefringence jump deltan and the temperature hysteresis DeltaT increase. (C) 2002 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu T., Molokeev M. S., Xia Z., Zhang Q.
Заглавие : Aliovalent substitution toward reinforced structural rigidity in Ce3+-doped garnet phosphors featuring improved performance
Место публикации : J. Mater. Chem. C. - 2019. - Vol. 7, Is. 46. - P.14594-14600. - ISSN 20507534 (ISSN), DOI 10.1039/c9tc05354a
Примечания : Cited References: 38. - This work was supported by the National Natural Science Foundation of China (No. 51722202 and 51972118), the Guangdong Provincial Science & Technology Project (2018A050506004) and the Fundamental Research Funds for the Central Universities (D2190980).
Аннотация: Highly efficient phosphors with thermal stability and color-tunable emission are required for the fabrication of phosphor-converted white light-emitting diodes (pc-WLEDs). Currently developed engineering strategies are generally successful in photoluminescence tuning but, unfortunately, suffer severe deterioration in emission intensity/efficiency and/or thermal stability. Herein, an efficient aliovalent substitution strategy toward reinforced structural rigidity is proposed and demonstrated experimentally. By incorporating Be2+ ion into the garnet-type Lu2SrAl4SiO12:Ce3+ phosphor, the phosphor shows enhanced internal/external quantum efficiency, from 79.2%/26.7% to 84.5%/32.9%, photoluminescence tuning from green (peaking at ∼512 nm) to yellow (peaking at ∼552 nm), and zero thermal quenching, even up to 200 °C. The Be2+ substitution at the Al2/Si2 site enables stable and rigid local surroundings around the Ce3+ activator, which is responsible for the unprecedented performance. In addition, high-quality warm WLED devices with a luminous efficiency of 158.1 lm W-1, correlated color temperature of 3858 K and high color rendering index of 81.7, are obtained by combining Lu2SrAl4SiO12:Ce3+,Be2+ as the yellow emitter, CaAlSiN3:Eu2+ as the red emitter and a blue-emitting InGaN chip. These findings highlight a new strategy for performance optimization of LED phosphors by selecting rigid covalent compounds with further reinforced structural rigidity via aliovalent substitution.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Shestakov N. P.
Заглавие : Bi2(Sn0.95Cr0.05)2O7: Structure, IR spectra, and dielectric properties
Место публикации : Ceram. Int.: Elsevier, 2016. - Vol. 42, Is. 4. - P.5177-5183. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2015.12.040
Примечания : Cited References: 45. - This work was supported by the Russian Foundation for Basic Research Projects no. 15-42-04099 r_siberia_a, Siberian Branch of Science and NAS of Belarus “Electronic and magnetic phase transitions in materials with magnetoelectric affect” and government work no. 114090470016.
Предметные рубрики: BISMUTH PYROSTANNATE
PYROCHLORE STRUCTURE
MAGNETIC-PROPERTIES
PARTIAL OXIDATION
HIGH-TEMPERATURE
X-RAY
Bi2Sn2O7
SUBSTITUTION
CATALYSTS
DIFFRACTION
Ключевые слова (''Своб.индексиров.''): bismuth pyrostannate--infrared absorption spectra--structural transition--permittivity--debye model
Аннотация: Infrared absorption spectra of the bismuth pyrostannate Bi2(Sn0.95Cr0.05)2O7 were investigated in the frequency range 350-1100 cm-1 at temperatures of 110-525 K. Four frequency regions with split absorption lines are distinguished. Softening of frequencies at the structural transitions was observed. The maxima of permittivity measured in the frequency range 1-200 kHz at temperatures 100-400 K were determined. It was found that the magnetic susceptibility changes its sign in the low-temperature region. The correlation between anomalies in the magnetic susceptibility, permittivity, and absorption line intensity was established. Softening of frequencies is explained by the variation in the coefficient of thermal expansion of the lattice. The temperature behavior of permittivity is described using the Debye model. © 2015 Elsevier Ltd and Techna Group S.r.l.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji H. P., Huang Z. H., Xia, Zhiguo, Molokeev M. S., Atuchin V. V., Huang S. F.
Заглавие : Cation substitution dependent bimodal photoluminescence in whitlockite structural Ca3-xSrx(PO4)2:Eu2+ (0 ≤ x ≤ 2) solid solution phosphors
Место публикации : Inorg. Chem.: American Chemical Society, 2014. - Vol. 53, Is. 20. - P.11119-11124. - ISSN 0020-1669, DOI 10.1021/ic501679f. - ISSN 1520-510X
Примечания : Cited References: 37. - This work was supported by the National Natural Science Foundations of China (Grant Nos. 51032007, 51002146, 51272242), the Research Fund for 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 Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047), and Beijing Youth Excellent Talent Program (YETP0635). V.V.A. acknowledges the Ministry of Education and Science of the Russian Federation for financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
EFFICIENT ENERGY-TRANSFER
EMISSION-TUNABLE PHOSPHOR
EXCITED WHITE LEDS
CRYSTAL-STRUCTURE
LUMINESCENCE PROPERTIES
Mn2+ PHOSPHOR
COLOR TONE
PHASE
Eu2+
Аннотация: Cation substitution dependent tunable bimodal photoluminescence behavior was observed in the Ca3-xSrx(PO4)2:Eu2+ (0 ≤ x ≤ 2) solid solution phosphors. The Rietveld refinements verified the phase purity and whitlockite type crystal structure of the solid solutions. The tunable photoluminescence evolution was studied as a function of strontium content, over the composition range 0.1 ≤ x ≤ 2. In addition to the emission band peak at 416 nm in Ca3(PO4)2:Eu2+, the substitution of Ca2+ by Sr2+ induced the emerging broad-band peak at 493-532 nm. A dramatic red shift of the emission peak located in the green-yellow region was observed on an increase of x in the samples with 0.75 ≤ x ≤ 2.00. The two emission bands could be related to the EuOn-Ca9 and EuOn-Ca9-xSrx emitting blocks, respectively. The values for the two kinds of emitting blocks in the solid solutions can be fitted well with the observed intensity evolution of the two emission peaks.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ming, Hong, Zhao, Yifei, Zhou, Yayun, Molokeev M. S., Wang, Yuanjing, Song, Enhai, Zhang, Qinyuan
Заглавие : Chemical group substitution enables highly efficient Mn4+ luminescence in heterovalent systems
Место публикации : Adv. Optical Mater. - 2023. - Vol. 11, Is. 10. - Ст.2300076. - ISSN 21951071 (eISSN), DOI 10.1002/adom.202300076
Примечания : Cited References: 36. - This work was financially supported by the National Key Research and Development Program of China (2022YFB3503800), the National Science Foundation of China (Grant Nos. 52202170 and 51972117). This work was also funded by RFBR according to the research project No. 19-52-80003
Аннотация: Defects are a double-edged sword for heterovalent metal-ion doping phosphors. Along with the luminescence tunability of phosphors bestowed by defects, their expected luminescence efficiency would also be inevitably lowered due to the presence of these quenching sites. Herein, a chemical group substitution strategy is proposed, where inorganic polyhedrons act as the smallest chemical units during the structural evolution of the doping process. Such a method can not only effectively prevent the defect generation for charge compensation in heterovalent doping systems, but also facilitate the incorporation of activators into the matrix, leading to extremely high luminescence efficiency. The concept is first confirmed energetically favorable by first-principles simulations. As a robust experimental proof, two newly reported Mn4+-incorporated hexavalent organic-inorganic hybrid oxyfluorides (TMA)2BO2F4:Mn4+ (where TMA stands for tetramethylammonium, and B = W6+ or Mo6+) present high quantum efficiency (up to 94.4%) and short lifetime (down to 2.26 ms) that are superior to the commercial red phosphor K2SiF6:Mn4+ (≈84.8%, ≈8.06 ms). Utilizing the differences in decay lifetimes and thermal quenching behaviors of (TMA)2BO2F4:Mn4+ and K2SiF6:Mn4+, a time- and temperature-resolved single-color multiplexing mode with high-safety and easy-access is developed for information security. This work offers an effective strategy to manipulate defect generation in luminescent materials.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zheng Y., Zhang H., Zhang H., Xia Z., Liu Y., Molokeev M. S., Lei B.
Заглавие : Co-substitution in Ca1−xYxAl12−xMgxO19 phosphors: local structure evolution, photoluminescence tuning and application for plant growth LEDs
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 15. - P.4217-4224. - ISSN 20507534 (ISSN), DOI 10.1039/c8tc00165k
Примечания : Cited References: 47. - The present work was supported by the National Natural Science Foundation of China (Grant No. 21671070), the Project for Construction of High-level University in Guangdong Province, and the Teamwork Projects funded by the Guangdong Natural Science Foundation (Grant No. S2013030012842), and the Guangzhou Science & Technology Projects (No. 201704030086, 201605030005), and the reported study was funded by the RFBR according to the research project 17-52-53031. Special Funds for the Cultivation of Guangdong College Students’ Scientific and Technological Innovation (‘‘Climbing Program’’ Special Funds) were granted for Dr Yinjian Zheng.
Ключевые слова (''Своб.индексиров.''): co substitution--crystal structure transformation--high temperature solid-state reaction--lighting systems--local structure--luminescence measurements--structural refinement--tunable luminescences
Аннотация: Herein, Mn4+-activated Ca1-xYxAl12-xMgxO19 (x = 0-0.50) solid solutions were prepared using a conventional high-temperature solid-state reaction. Crystal structure transformation via chemical co-substitution of Y3+/Mg2+ for Ca2+/Al3+ was investigated in detail. The optical properties of Ca1-xYxAl12-xMgxO19 (x = 0-0.50) have been reported for the first time using a combination of techniques including structural refinement and luminescence measurements. Co-doping of Mg and Y cations within the CaAl12O19 host in a controlled manner resulted in the as-prepared samples with red/far-red ratio-tunable luminescence properties. The emission bands well-matched with the absorption band of phytochrome. Interestingly, enhanced Mn4+ luminescence can be obtained upon the addition of Mg2+ and Y3+. Unexpectedly, the quantum yields exhibit a slight change when x is in the range from 0.05 to 0.40; this indicates that these solid solutions have significant potential as lighting systems for plant growth.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorban A., Popova T., Zinovyev A.
Заглавие : Codon usage trajectories and 7-cluster structure of 143 complete bacterial genornic sequences
Разночтения заглавия :авие SCOPUS: Codon usage trajectories and 7-cluster structure of 143 complete bacterial genomic sequences
Место публикации : Physica A: ELSEVIER SCIENCE BV, 2005. - Vol. 353. - P365-387. - ISSN 0378-4371, DOI 10.1016/j.physa.2005.01.043
Примечания : Cited References: 46
Предметные рубрики: DNA-BASE COMPOSITION
ASYMMETRIC SUBSTITUTION PATTERNS
PROTEIN-CODING REGIONS
MICROBIAL GENOMES
GENE IDENTIFICATION
MARKOV-MODELS
G+C CONTENT
BIAS
PREDICTION
SELECTION
Ключевые слова (''Своб.индексиров.''): genome--cluster--codon usage--correlations--entropy--mean field--cluster--codon usage--correlations--entropy--genome--mean field--approximation theory--correlation methods--database systems--entropy--functions--genes--mathematical models--clusters--codon usage--genomes--mean field--bacteria
Аннотация: Three results are presented. First, we prove the existence of a universal 7-cluster structure in all 143 completely sequenced bacterial genomes available in Genbank in August 2004, and explained its properties. The 7-cluster structure is responsible for the main part of sequence heterogeneity in bacterial genomes. In this sense, our 7 clusters is the basic model of bacterial genome sequence. We demonstrated that there are four basic "pure" types of this model, observed in nature: "parallel triangles", "perpendicular triangles", degenerated case and the flower-like type. Second, we answered the question: how big are the position-specific information and the contribution connected with correlations between nucleotide. The accuracy of the mean-field (context-free) approximation is estimated for bacterial genomes. We show that codon us-age of bacterial genomes is a multi-linear function of their genomic G+C-content with high accuracy (more precisely, by two similar functions, one for eubacterial genomes and the other one for archaea). Description of these two codon-usage trajectories is the third result. All 143 cluster animated 3D-scatters are collected in a database and is made available on our web-site: http://www.ihes.fr/similar to zinovyev/7clusters. (c) 2005 Elsevier B.V. All rights reserved.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Romanova O. B., Aplesnin S. S., Sitnikov M. N., Kharkov A. M., Demidenko O. F., Galyas A. I., Yanyshkevich K. I.
Заглавие : Conductivity, structural and magnetic properties of manganese chalcogenide films under anionic substitution by tellurium
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow International Symposium on Magnetism (MISM-2017): 1-7 July 2017 : book of abstracts. - 2017. - Ст.4PO-I1-30. - P.885 (Шифр 29916280)
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gokhfel'd D. M., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Terent'yev K. Yu., Freydman A. L., Krasikov A. A., Petrov M. I.
Заглавие : Control of peak effect in YBCO by Nd substitution
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.O2.7. - P.140. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 4. - The work was supported by Russian Foundation for Basic Research Grant No.16-38-00400
Ключевые слова (''Своб.индексиров.''): peak effect--paramagnetic magnetization--bulk superconductors--critical current--irreversibility field
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liang S. S., Dang P. P., Li G. G., Molokeev M. S., Wei Y., Lian H. Z., Shang M. M., Al Kheraiff A. A., Lin J.
Заглавие : Controllable two-dimensional luminescence tuning in Eu2+,Mn2+ doped (Ca,Sr)9Sc(PO4)7 based on crystal field regulation and energy transfer
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 25. - P.6714-6725. - ISSN 2050-7526, DOI 10.1039/c8tc01825a. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 63. - This work was financially supported by the National Natural Science Foundation of China (NSFC No. 51672265, 51672266, 21521092, 51750110511, 51672257, and 51672259), the Key Research Program of Frontier Sciences of CAS (Grant No. YZDY-SSW-JSC018), the National Basic Research Program of China (2014CB643803), the Scientific and Technological Department of Jilin Province (Grant No. 20150520029JH and 20170414003GH), Jiangmen Innovative Research Team Program (2017) and Major Program of Basic Research and Applied Research of Guangdong Province (2017KZDXM083), the Russian Science Foundation (Grant No. 17-12-01047), and the Distinguished Scientist Fellowship Program of King Saud University, as well as the Deanship of Scientific Research at King Saud University through research group no. (RG-1939-038).
Предметные рубрики: SOLID-SOLUTION PHOSPHORS
LIGHT-EMITTING-DIODES
CATION SUBSTITUTION
Аннотация: Currently, controllable luminescence tuning and the generation of single component white emission are viable strategies to modify and optimize the luminescence performances of phosphors, which offer appealing prospects for the w-LED lighting industry. In this paper, we designed two-dimensional (2D) tunable color coordinates on the CIE diagram in the Eu2+,Mn2+ doped (Ca,Sr)9xSc(PO4)7 system by a combination of crystal field regulation and the energy transfer method. X-ray powder diffraction (XRD) and Rietveld refinement were utilized to analyze the phase composition and structural variation of the studied phosphors. The transmission electron microscopy (TEM) and photoluminescence spectra were exploited to analyze the generation of nanosegregation. The effects of the schedule of cation substitutions and energy transfer on the photoluminescence properties were investigated in detail. The corresponding luminescence mechanisms of the red-shifted emission with Sr2+ → Ca2+ substitution and Eu2+ → Mn2+ energy transfer were deeply discussed and proposed. In addition, the temperature-dependent thermal quenching behavior and the electroluminescence (EL) performance of the fabricated w-LED devices were also investigated to characterize the prepared Ca9(1−0.03−x−y)Sr9xSc(PO4)7:0.27Eu2+,9yMn2+. Finally, a representative w-LED device composed of a 369 nm UV chip and Ca9(1−0.03−0.02−0.5)Sr4.5Sc(PO4)7:0.27Eu2+,0.18Mn2+ could present excellent EL performance with the parameters CRI = 88, CCT = 3122 K and color coordinate (0.45, 0.44), which could well meet the commercial standard of warm white light. Therefore, our results suggest that this two-step luminescence tuning method is feasible to be applied in other phosphor systems for obtaining efficient white emitting phosphors.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Platunov M. S., Knyazev Yu. V., Ivanova N. B., Zubavichus Y. V., Veligzhanin A. A., Vasiliev A. D., Bezmaternykh L. N., Bayukov O. A., Arauzo A., Bartolome J., Lamonova K. V., Ovchinnikov S. G.
Заглавие : Crystal and local atomic structure of MgFeBO4,Mg0.5Co0.5FeBO4, and CoFeBO4: effects of Co substitution
Место публикации : Phys. Status Solidi B. - 2015. - Vol. 252, Is. 10. - P.2245-2258. - ISSN 0370, DOI 10.1002/pssb.201552143. - ISSN 15213951 (eISSN)
Примечания : Cited References: 46. - This work has been financed by the MECOM Project MAT11/23791, and DGA IMANA project E-34, Council for Grants of the President of the Russian Federation (project nos. NSh-2886.2014.2, SP-938.2015.5), and Russian Foundation for Basic Research (project nos. 13-02-00958-a, 13-02-00358-a, 14-02-31051-mol-a). The work of one of the coauthors (M.S.P.) was supported by the program of Foundation for promoting the development of small enterprises in scientific and technical sphere ("UMNIK" program).
Предметные рубрики: SPIN-GLASS BEHAVIOR
MAGNETIC WARWICKITES
SINGLE-CRYSTALS
PHASE-RELATIONS
OXYBORATE
SYSTEM
SPECTROSCOPY
ANISOTROPY
MN2OBO3
FE2OBO3
Ключевые слова (''Своб.индексиров.''): crystal structure--xanes--exafs--magnetic semiconductor--oxyborate
Аннотация: Single-crystalline MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 have been grown by the ﬂux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction, and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption ﬁne structure (EXAFS) spectra have been measured at the Fe and Co K-edges over a wide temperature range (6.5– 300 K). The composition, the charge state, and local environ- ment of both Fe and Co atoms have been determined. The effects of Co substitution for Mg on the local structural distortions have been revealed experimentally and the M–O bond anisotropy has been found.Монокристаллические образцы CoFeBO4 были выращены раствор-расплавным методом. Образцы были охарактеризованы с помощью рентгеноспектрального анализа, рентгеновской дифракции и спектроскопии поглощения рентгеновских лучей. Спектры вблизи K-края поглощения рентгеновского излучения структуры (XANES) и далее рентгеновского поглощения тонкой структуры (EXAFS) были измерены для Fe и Co в широком диапазоне температур (6.5- 300К). Состав, состояние заряда, и локальная положение и Fe и Co атомов были определены. Эффекты замещения Co магнием Mg на местные структурные искажения были выявлены экспериментально и анизотропия связи М-О была найдена.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cheng C., Ning L., Ke X., Molokeev M. S., Wang Z., Zhou G., Chuang Y. -C., Xia Z.
Заглавие : Designing high-performance LED phosphors by controlling the phase stability via a heterovalent substitution strategy
Место публикации : Adv. Opt. Mater. - 2020. - Vol. 8, Is. 2. - Ст.1901608. - ISSN 21951071 (ISSN), DOI 10.1002/adom.201901608
Примечания : Cited References: 31
Аннотация: Phosphor-converted white light-emitting diodes (LEDs) are currently playing key roles in the lighting and display industries and trigger urgent demands for the discovery of “good” phosphors with high quantum efficiency, improved thermal stability, and controllable excitation/emission properties. Herein, a general and efficient heterovalent substitution strategy is demonstrated in K2HfSi3O9:Eu2+ achieved by Ln3+ (Ln = Gd, Tb, Dy, Tm, Yb, and Lu) doping to optimize luminescence properties, and as an example, the Lu3+ substitution leads to improvement of emission intensity and thermal stability, as well as tunable emission color from blue to cyan. The structural stability and Eu2+ occupation via Lu3+ doping have been revealed by the structural elaboration and density functional theory calculations, respectively. It is shown that heterovalent substitution allows predictive control of site preference of luminescent centers and therefore provides a new method to optimize the solid-state phosphors for LEDs.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhao M., Zhou Y., Molokeev M. S., Zhang Q., Liu Q., Xia Z.
Заглавие : Discovery of new narrow-band phosphors with the UCr4C4-related type structure by alkali cation effect
Место публикации : Adv. Opt. Mater. - 2019. - Vol. 7, Is. 6. - Ст.1801631. - ISSN 21951071 (ISSN) , DOI 10.1002/adom.201801631
Примечания : Cited References: 29. - This work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 91622125, and 51572023) and Natural Science Foundations of Beijing (2172036). M.S.M. acknowledges the support of the Russian Foundation for Basic Research (No. 17-52-53031).
Ключевые слова (''Своб.индексиров.''): narrow-band emission--phosphors--photoluminescence--substitution strategy--white light-emitting diodes
Аннотация: Narrow-band luminescence materials used in white light-emitting diodes (WLEDs) have demonstrated a great potential to increase the maximum accessible color gamut, improve the color rendition, or enhance the visual luminous efficacy for illumination and display devices. So far, the discovery of narrow-band rare earth doped phosphors for emerging applications remains challenging owing to the limited systems in use and the broadening effect of 4f–5d transition. Here, two narrow-band cyan-emitting phosphors with the UCr4C4-related type structure, RbNa2K(Li3SiO4)4:Eu2+ (RNKLSO:Eu2+) and CsNa2K(Li3SiO4)4:Eu2+ (CNKLSO:Eu2+), are reported. The narrow-band emission results from the highly condensed network and a cube-like site for the activator (Eu2+). The emission peak assignments are investigated, and the variations of luminescence behavior with compositional changes of alkali cations are elaborated in detail. RNKLSO:8% Eu2+ (95%@250 °C of the integrated emission intensity at 25 °C) shows better thermal stability than that of CNKLSO:8% Eu2+ (79%@250 °C), which can be explained by the thermally activated crossover process represented in the configurational coordinate diagram. The optical properties of the as-fabricated WLEDs are studied and demonstrate potential with tunable properties for the full spectrum phosphor-converted LEDs. These findings in UCr4C4-type phases help shedding light on new avenues for fabricating new and totally unexpected narrow-emitting phosphors with versatile applications.
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16.

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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Miao, Shihai, Xia, Zhiguo, Molokeev M. S., Chen, Mingyue, Zhang, Jie, Liu, Quanlin
Заглавие : Effect of Al/Si substitution on the structure and luminescence properties of CaSrSiO4:Ce3+ phosphors: analysis based on the polyhedra distortion
Место публикации : J. Mater. Chem. C: Royal Society of Chemistry, 2015. - Vol. 3, Is. 18. - P.4616-4622. - ISSN 2050, DOI 10.1039/c5tc00339c. - ISSN 20507534(eISSN)
Примечания : Cited References:30. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51002146, 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), the Funds of the State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University (KF201306) and the excellent tutor section of the Fundamental Research Funds for the Central Universities of China University of Geosciences, Beijing (2652015027).Cover image: Artwork representing main idea of this article
Предметные рубрики: LIGHT-EMITTING-DIODES
COLOR-TUNABLE PHOSPHOR
ENERGY-TRANSFER
Аннотация: Blue-emitting CaSrSiO4:Ce3+,Li+ phosphors were prepared by a high temperature solid-state method, and the effect of substituting Al3+ for Si4+ in CaSrSiO4:Ce3+,Li+ has been studied. Crystal structures of the as-prepared Ca1−ySr1−ySi1−xAlxO4:yCe3+,yLi+ phosphors were resolved by the Rietveld method, which suggested that all the samples belonged to the orthorhombic symmetry (Pnma) group of α-CaSrSiO4. The photoluminescence (PL) emission and excitation spectra, the lifetime, and the effect of Al3+ concentration on the PL properties were investigated in detail. The emission peaks of the CaSrSi1−xAlxO4:Ce3+,Li+ (x = 0–0.10) phosphors were red-shifted from 452 to 472 nm with increasing Al/Si ratio. The red-shift of the Ce3+ emission is ascribed to the polyhedra distortion of the cations, originating from the variation in the neighboring [(Si,Al)O4] polyhedra, and the detailed mechanism has been discussed.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zinenko V. I., Shinkorenko A. S.
Заглавие : Effect of Ca 2+ ion substitution by the trivalent ions (Sc 3+, In 3+, La 3+, Bi 3+) on the ferroelectric instability in orthorhombic CaTiO3
Место публикации : Ferroelectrics: Special Issue: Professor Wolfgang Kleemann in honor of his 70th birthday: Taylor & Francis, 2012. - Vol. 426. - P.132-138. - ISSN 0015-0193, DOI 10.1080/00150193.2012.671657. - ISSN 1563-5112
Примечания : Cited References: 9. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00067)
Ключевые слова (''Своб.индексиров.''): ferroelectric--polarization--lattice dynamics
Аннотация: Vibration frequencies of instable ferroelectric modes, as well as dependencies of crystal energy on ion's displacement amplitudes of these modes in doped compounds Ca1–x A x Ti1–x/4□ x /4O3 (space group Pbmn) with А–Sc3+, In3+, La3+, Bi3+ (□–vacancy) have been calculated in the framework of generalized nonparametric Gordon–Kim model. To compensate excessive positive charge the vacancies were considered to be at Ti4+ sites. Calculations were carried out in the «average» crystal approximation for the impurity concentration x = 0.25. For this purpose 40 atoms’ supercell sets with the different ordering of the heterovalent ions Ca2+ and impurity А3+ have been considered. Every type of impurity has been found to induce ferroelectric instability in doped compounds.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bogdanov E. V., Vasil'ev A. D., Flerov I. N., Laptash N. M.
Заглавие : Effect of cation substitution in fluorine-oxygen molybdates (NH4)(2-x) A (x) MoO2F4
Разночтения заглавия :авие SCOPUS: Effect of cation substitution in fluorine-oxygen molybdates (NH4)2 - xAxMoO2F4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 2. - P303-308. - ISSN 1063-7834, DOI 10.1134/S1063783411020065
Примечания : Cited References: 11. - This study was supported by the Russian Foundation for Basic Research (project no. 09-02-00062) and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools of the Russian Federation (project no. NSh-1011.2008.2).
Предметные рубрики: PHASE-TRANSITIONS
CRYSTALS
(NH4)(2)WO2F4
DIFFRACTION
OXYFLUORIDE
MECHANISM
DISORDER
Аннотация: Thermophysical and structural studies of (NH4)(2 - x) A (x) MoO2F4 (A = Cs, Rb, K) solid solutions of oxyfluorides have been performed. The character of the influence of cation substitutions on the stability of the initial phase (space group Cmcm) and on the mechanism of phase transitions has been elucidated.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zinenko V. I.
Заглавие : Effect of cation substitution on the lattice dynamics and ferroelectric instability of cubic BaTiO3 and BaZrO3 doped with Bi and La ions
Коллективы : Russian Foundation for Basic Research [07-02-00069]
Разночтения заглавия :авие SCOPUS: Effect of cation substitution on the lattice dynamics and ferroelectric instability of cubic BaTiO3 and BaZrO3 doped with Bi and la ions
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 5. - P973-981. - ISSN 1063-7834, DOI 10.1134/S1063783409050151
Примечания : Cited References: 11. - This work was supported by the Russian Foundation for Basic Research, project no. 07-02-00069.
Предметные рубрики: CERAMICS
Аннотация: The spectra of lattice vibration frequencies of solid solutions Ba1 - x Bi(2x/3)a-- Ti-x/3(Zr)O-3 and Ba1 - x La (x) Ti(Zr)(1 - x/4)a-- O-x/4(3) are calculated in terms of a generalized Gordon-Kim model with inclusion of the dipole and quadrupole polarizabilities. Over the entire concentration range, the calculated phonon spectra contain a ferroelectric soft mode. The effect of various interactions on the ferroelectric instability of these solid solutions is studied. It is shown that the character of ferroelectric instability is largely determined by the mechanism of charge compensation.
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