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1.

Вид документа : Однотомное издание
Шифр издания : В37/K64 рукописный текст
Автор(ы) : Knyazev Yu. V.
Заглавие : The influence of cationic substitution on the magnetic properties of cobalt ludwigite : Doctoral thesis in physics
Выходные данные : Krasnoyarsk, 2017
Колич.характеристики :99 с
Коллективы : Siberian Federal University
Примечания : Bibliogr.: P. 54-57
ISBN, Цена 978-5-7638-3771-1
ГРНТИ : 29.19.37 + 31.15.25 + 29.19.33
ББК : В379.312я031
Экземпляры :ДС(1)
Свободны : ДС(1)
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2.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Olshevskaya J., Shubin A., Kovaleva A., Tomilin F. N.
Заглавие : The effect of iron substitution on the structure and electronic properties of Cr2SiC by theoretical method
Коллективы : International workshop on functional MAX-materials, Kirensky Institute of Physics, Siberian Federal Univercity
Место публикации : International workshop on the properties of functional MAX-materials (2nd FunMax): book of abstracts/ org. com. M. Farle [et al.]. - 2021. - P.42
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3.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Удод, Любовь Викторовна, Романова, Оксана Борисовна
Заглавие : Влияние катионного замещения на магнитные свойства и электрическую поляризацию в системе Bi2(Sn0.9Ме0.1)2O7, Ме =Cr3+, Fe3
Коллективы : "Новое в магнетизме и магнитных материалах", международная конференция, Научный совет по физике конденсированных сред РАН, МИРЭА - Российский технологический университет, Московский государственный университет им. М.В. Ломоносова, Магнитное общество России
Место публикации : Новое в магнетизме и магнитных материалах: сборник трудов XXIV международной конференции/ прогр. ком.: Р. С. Исхаков, С. Г. Овчинников [и др.]. - 2021. - Секция 1: Новые магнитные и родственные им материалы: синтез и физические свойства. - С. 98-101
Примечания : Библиогр.: 13. - Исследование выполнено при финансовой поддержке программы No 3.5743.2021/6.7
Аннотация: Исследовано влияние гетерогенного замещения ионами Cr3+и Fe3+ на магнитные свойства и электрическую поляризацию пиростанната висмута.Установлена зависимость магнитных свойств от степени заполнения электронных оболочек ионов хрома и железа. Найден гистерезис поляризации в Bi2(Sn0.9Cr0.1)2O7.The effect of heterogeneous substitution by Cr3+ and Fe3+ ions on the magnetic properties and electric polarization of bismuth pyrostannate is investigated. The dependence of the magnetic properties on the degree of filling of the electron shells of chromium and iron ions has been established. The hysteresis of polarization was found in Bi2(Sn0.9Cr0.1)2O7.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arauzo A., Bartolome J., Luzon J., Drokina T. V., Petrakovskii G. A., Molokeev M. S.
Заглавие : Effect of R substitution in spin glass RFeTi2O7 compounds
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 515. - Ст.167273. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2020.167273
Примечания : Cited References: 38. - This study has been financed by MECOM Project MAT2014-53921-R, MICINN Project MAT2017-83468-R and Gobierno de Aragón RASMIA E12_17R. Authors would like to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza
Аннотация: Zirconolite oxides R3+Fe3+Ti2O7 (R rare earth element) are known to exhibit spin glass behaviour at low temperatures. Here we present a detailed study of these compounds for R = Eu, Gd, Dy, Ho, and Er, together with reviewed previous measurements on Sm, Tb, Tm, Yb and Lu, with the scope of determining the role played by the rare earth on their magnetic properties. They have been investigated using X-ray powder diffraction, and further characterized by magnetization, frequency dependent ac susceptibility and heat capacity measurements. RFeTi2O7 compounds are all isostructural showing orthorhombic structure, space group Pcnb at 300 K. Disorder of the magnetic ions in the RFeTi2O7 lattice induces spin glass behaviour at low temperatures, mainly due to the Fe sublattice. We show that magnetic rare earth ions participate in the spin glass state tuning its properties. The single ion anisotropy of the R3+ ions, excluding exchange interaction with other magnetic ions, has been calculated by ab initio methods, and expressed in terms of the g tensor of the ground doublet or quasi-doublet in Kramers (Sm, Dy, Er, Yb) and non-Kramers (Tb, Ho) ions, respectively, in an effective spin S* = 1/2 model. In the case of R with a singlet ground state (Eu, Tm) or a multiplet state (Gd), the ion is isotropic. We show that the relative increase in the spin-glass temperature ΔTSGR/TSGFe with respect to the LuFeTi2O7, where Lu is non-magnetic, correlates qualitatively with the product of the ratio gz/gJ (R = Tb, Dy, Ho, and Er), or g⊥/gJ (R = Sm), times the ratio of exchange interactions JR,Fe/JFe,Fe determined from the paramagnetic room temperature susceptibility measurements. Besides, for increasing anisotropy the spin glass transition dynamics slows down to values typical of cluster glass. The coercive field below the transition is increased in the same trend. This paper explains the effect of the R-Fe exchange interaction and R single ion anisotropy on the spin-glass behaviour of these compounds.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu G., Hu T., Molokeev M. S., Xia Z.
Заглавие : Li/Na substitution and Yb3+ co-doping enabling tunable near-infrared emission in LiIn2SbO6:Cr3+ phosphors for light-emitting diodes
Место публикации : iScience. - 2021. - Vol. 24, Is. 4. - Ст.102250. - ISSN 25890042 (ISSN), DOI 10.1016/j.isci.2021.102250
Примечания : Cited References: 45. - The present work was supported by the National Natural Science Foundation of China of China (Grant Nos. 51972118 and 51961145101), the Fundamental Research Funds for the Central Universities (D2190980), the Guangzhou Science & Technology Project (202007020005), the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Pro-gram (2017BT01X137), and RFBR according to the research project No. 19-52-80003
Аннотация: Near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) has great potential in non-invasive detection, while the discovery of tunable broadband NIR phosphor still remains a challenge. Here, we report that Cr3+-activated LiIn2SbO6 exhibits a broad emission band ranging from 780 to 1400 nm with a full width at half maximum (FWHM) of 225 nm upon 492 nm excitation. The emission peaks are tuned from 970 to 1020 nm together with considerable broadening of FWHM (∼285 nm) via Li/Na substitution. Depending on Yb3+ co-doping, a stronger NIR fluorescence peak of Yb3+ appears with improved thermal resistance, which is ascribed to efficient energy transfer from Cr3+ to Yb3+. An NIR pc-LED package has been finally designed and demonstrated a remarkable ability to penetrate pork tissues (∼2 cm) so that the insertion depth of a needle can be observed, indicating that the phosphor can be applied in non-destructive monitoring.
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6.

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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7.

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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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aplesnin S., Romanova O., Eremin E., Ryabinkina L., Demidenko O., Makovetskii G., Yanushkevich K.
Заглавие : The Influence Of Anionic Substitution With Structural And Electrical Properties Of Mn - Se - Те Chalkogenides
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2011): Book of abstracts. - 2011. - Ст.24PO-I2-27. - P.693
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9.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zamkova N.G., Zhandun V.S., Zinenko V.I.
Заглавие : Effect of Sr2+ ion substitution by the triva- lent ions (Sc3+,In3+,La3+,Bi3+) on the ferroelectric instability in SrTi03
Коллективы : European Meeting on Ferroelectricity
Место публикации : 12th European Meeting on Ferroelectricity: Abstracts. - 2011. - Ст.1-4
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lim, Chang-Sung, Aleksandrovsky A. S., Molokeev M. S., Oreshonkov A. S., Atuchin V. V.
Заглавие : Structural and spectroscopic effects of Li+ substitution for Na+ in LixNa1-xCaGd0.5Ho0.05Yb0.45(MoO4)3 scheelite-type upconversion phosphors
Место публикации : Molecules. - 2021. - Vol. 26, Is. 23. - Ст.7357. - ISSN 1420-3049 (eISSN), DOI 10.3390/molecules26237357
Примечания : Cited References: 77. - This study was supported by the Research Program through the Campus Research Foundation funded by Hanseo University in 2021 (211Yunghap06)
Аннотация: A set of new triple molybdates, LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45, was successfully manufactured by the microwave-accompanied sol–gel-based process (MAS). Yellow molybdate phosphors LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45 with variation of the LixNa1-x (x = 0, 0.05, 0.1, 0.2, 0.3) ratio under constant doping amounts of Ho3+ = 0.05 and Yb3+ = 0.45 were obtained, and the effect of Li+ on their spectroscopic features was investigated. The crystal structures of LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45 (x = 0, 0.05, 0.1, 0.2, 0.3) at room temperature were determined in space group I41/a by Rietveld analysis. Pure NaCaGd0.5Ho0.05Yb0.45(MoO4)3 has a scheelite-type structure with cell parameters a = 5.2077 (2) and c = 11.3657 (5) Å, V = 308.24 (3) Å3, Z = 4. In Li-doped samples, big cation sites are occupied by a mixture of (Li,Na,Gd,Ho,Yb) ions, and this provides a linear cell volume decrease with increasing Li doping level. The evaluated upconversion (UC) behavior and Raman spectroscopic results of the phosphors are discussed in detail. Under excitation at 980 nm, the phosphors provide yellow color emission based on the 5S2/5F4 → 5I8 green emission and the 5F5 → 5I8 red emission. The incorporated Li+ ions gave rise to local symmetry distortion (LSD) around the cations in the substituted crystalline structure by the Ho3+ and Yb3+ ions, and they further affected the UC transition probabilities in triple molybdates LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45. The complex UC intensity dependence on the Li content is explained by the specificity of unit cell distortion in a disordered large ion system within the scheelite crystal structure. The Raman spectra of LixNa1-xCaGd0.5(MoO4)3 doped with Ho3+ and Yb3+ ions were totally superimposed with the luminescence signal of Ho3+ ions in the range of Mo–O stretching vibrations, and increasing the Li+ content resulted in a change in the Ho3+ multiplet intensity. The individual chromaticity points (ICP) for the LiNaCaGd(MoO4)3:Ho3+,Yb3+ phosphors correspond to the equal-energy point in the standard CIE (Commission Internationale de L’Eclairage) coordinates.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao J., Zhou Y., Molokeev M. S., Zhang Q., Xia Z.
Заглавие : Narrow bandwidth luminescence in Sr2Li(Al,Ga)O4:Eu2+ by selective site occupancy engineering for high definition displays
Место публикации : Laser Photon. Rev. - 2021. - Vol. 15, Is. 11. - Ст.2100392. - ISSN 18638880 (ISSN), DOI 10.1002/lpor.202100392
Примечания : Cited References: 39. - J.Q. and Y.Z. contributed equally to this work. This research was supported by the National Natural Science Foundation of China (grant nos. 51972118 and 51961145101), International Cooperation Project of National Key Research and Development Program of China (2021YFE0105700), Guangzhou Science & Technology Project (202007020005), the State Key Laboratory of Luminescent Materials and Devices (Skllmd-2021-09), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01×137). This work is also funded by RFBR according to the research project no. 19-52-80003
Аннотация: It remains a critical challenge to develop narrow-band emitters for wide color gamut displays. Herein, it is designed by the selective site occupancy engineering and an unprecedented narrow-band green-emitting phosphor is prepared through chemical substitution. By introducing Ga3+ ions into Sr2LiAlO4:Eu2+ phosphor, the distribution of Eu2+ ions in Sr1 and Sr2 sites is effectively controlled, and only one type of luminescent centers Eu2+(Sr1) is remained in Sr2LiAl0.6Ga0.4O4:Eu2+ due to the compression effect of Sr2O8 polyhedra. Sr2LiAl0.6Ga0.4O4:Eu2+ phosphor presents an extremely narrow-band green emission centered at 512 nm with a full-width at half-maximum of only 40 nm. The wide color gamut (107% National Television System Committee) of the as-fabricated white liquid crystal displays and the vivid figures captured from the projector demonstrate the potential application of narrow-band emitter for wide-color gamut displays. This work provides the design principles of realizing narrow-band emission by selective site occupancy engineering and can set the stage for the exploring of Eu2+-activated phosphor for high definition displays.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang S., Gai S., Zhang X., Xia M., Zhou Z., Cheng X., Yao M., Molokeev M. S., Feng Q.
Заглавие : Enhanced luminescence properties of Li2MgTiO4: Mn4+, Ge4+ phosphor via single cation substitution for indoor plant cultivation
Место публикации : Ceram. Int. - 2022. - Vol. 48. Is. 3. - P.3070-3080. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2021.10.082
Примечания : Cited References: 41. - The authors would like to gratefully acknowledge funds from National Natural Science Foundation of China (Grant No. 51974123), the Distinguished Youth Foundation of Hunan Province (Grant No. 2020JJ2018), Key R & D projects in Hunan Province (2020WK2016 & 2020SK2032), Hunan High Level Talent Gathering Project (2019RS1077 & 2020RC5007), the Natural Sciences Foundation of Hunan Agricultural University (19QN11), Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Resource Utilization Science Foundation (19KFXM12), Changsha Science and technology plan (KH2005114), and the Scientific Research Fund of Hunan Provincial Education Department (19C0903)
Аннотация: Red and far-red emitting phosphors have been widely used in phosphor-converted light emitting diode (pc-LED) devices to provide lighting for indoor plant growth, thus achieving desired product qualities. Among the many ways to optimize phosphors’ optical performance, cationic substitution is one of the most effective methods. In this study, red phosphors (Li2MgTi1-x-yO4: xMn4+, yGe4+) were synthesized by high temperature solid state method and the optical performance of phosphors were improved with increasing Ge4+ constituents. In particular, luminescence intensity of Li2MgTiO4: 0.002Mn4+, 0.1Ge4+ increased by 152% under 468 nm excitation, and the thermostability of emission intensity increases from 22% (y = 0) to 43% (y = 0.1), which is about twice as much. Finally, pc-LED device was fabricated via the red phosphor Li2MgTiO4: 0.002Mn4+,0.1Ge4+ coated on a 470 nm ultraviolet chip. By changing the proportion of the phosphor, the electroluminescence spectra of pc-LED device could match well with the absorption regions of plant pigments. Therefore, Li2MgTiO4: 0.002Mn4+, 0.1Ge4+ phosphor has potential application in plant lighting. Furthermore, this work can offer some helpful references for improving luminescent efficiency by simply modulating the chemical composition.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Jing Y., Liu Y., Jiang X., Molokeev M. S., Lin Z., Xia Z.
Заглавие : Sb3+dopant and halogen substitution triggered highly efficient and tunable emission in lead-free metal halide single crystals
Место публикации : Chem. Mater. - 2020. - Vol. 32, Is. 12. - P.5327-5334. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.0c01708
Примечания : Cited References: 46. - This work is supported by the National Natural Science Foundation of China (51961145101, 51972118, and 51722202), Fundamental Research Funds for the Central Universities (FRFTP-18-002C1), Guangzhou Science & Technology Project (202007020005), Guangdong Provincial Science &Technology Project (2018A050506004), 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
Аннотация: Rational doping and compositional control remain significant challenges in designing luminescent metal halides to achieve highly efficient and tunable emission. Here, the air-stable lead-free Cs2InCl5·H2O crystal with a zero-dimensional structure was investigated as a pristine compound to design new luminescence materials. Sb3+-doping in Cs2InCl5·H2O:Sb3+ enabled broadband yellow emission with a photoluminescence quantum yield up to 95.5%. The emission colors can be expanded into the orange-red region by halogen compositional substitution for Cs2InX5·H2O:Sb3+ (X = Cl/Br/I). The optical characterizations along with the theoretical calculations demonstrate that the characteristic singlet and triplet self-trapped exciton emissions of ns2-metal-halide centers account for the tunable luminescence. Moreover, the admirable stability against air and heat pave way for its further applications in white light-emitting diodes and high-resolution fluorescent signs in anticounterfeiting technology. Our achievement in the case of Sb3+-doped Cs2InCl5·H2O represents a successful strategy for developing stable lead-free metal halides with highly efficient emission for versatile optical applications.
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14.

Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Loginov Y. Y., Kretinin V. V., Masyugin A. N.
Заглавие : Influence of cation substitution on dielectric and electric properties of bismuth stannates Bi2Sn1.9Meo.1O7 (Me=Cr, Mn)
Коллективы : International Scientific Conference Reshetnev Readings 2017
Место публикации : IOP Conf. Ser.: Mater. Sci. Eng.: IOP, 2019. - Vol. 467: 21st International Scientific Conference Reshetnev Readings 2017 (8 November 2018 through 8 November 2018) Conference code: 144163, Is. 1. - , DOI 10.1088/1757-899X/467/1/012014
Примечания : Cited References: 9. - This study was supported by the Russian Foundation for Basic Research project N 17-32-50080, the state order № 3.5743.2017/6.7.
Аннотация: The article studies effect of nonstoichiometric substitution of the tin ions by chromium and manganese ions on the dielectric and electrical properties of bismuth pyrostannate. The research performs measurements of the current-voltage characteristics, capacitance and tangent of the dielectric loss angle in the temperature range from 300 to 800 K; it finds a qualitative difference in the temperature behavior of the permittivity of bismuth pyrostannate with chromium and manganese ions. A change in the type of conductivity from hopping to tunneling emission is established. The change in the activation energy as a function of the ion radius is found.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pankrats A. I., Kolkov M. I., Balaev A. D., Shabanov A. V., Vasiliev A. D.
Заглавие : Forming a ferrimagnetic-like structure in the PbMn1−xFexBO4 (x ≈ 0.1) single crystal upon partial substitution
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 497. - Ст.165997. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2019.165997
Примечания : Cited References: 25. - The authors are grateful to S. Nikitin for help in the specific heat measurements in a magnetic field and S. Martynov for fruitful discussions. This study was funded by RFBR and the Government of Krasnoyarsk Territory , Krasnoyarsk Regional Fund of Science , to the research project no. 18-42-240008 “Effect of Magnetic Structure on the Magnetodielectric Properties of Oxide Crystals Containing Stereoactive Ions Pb 2+ and Bi 3+”.
Аннотация: The PbMn1−xFexBO4 (x ≈ 0.1) orthoborate single crystals have been grown for the first time by spontaneous crystallization and their magnetic and resonance properties and specific heat have been examined. It has been established that partial substitution of iron ions for manganese ones leads to an increase in the Curie temperature to 34.2 K from its value of 30.3 K in the unsubstituted crystal, enhances the magnetic anisotropy, and reduces the saturation magnetization. The magnetization drop is explained in the framework of the model of a ferrimagnetic-like structure, in which the magnetic moments of iron and manganese ions form ferromagnetic subsystems coupled by the antiferromagnetic exchange. It has been found that under magnetization along the rhombic b axis the magnetic moments switch stepwise to the magnetic field direction in a certain critical field. The spin-reorientation transition is the first-order one. This feature of the crystal magnetization does not allow the experimental ferromagnetic resonance frequency-field dependence for the rhombic b axis to be described using the calculation for a simple rhombic ferromagnet. It has been established that the increase in the magnetic anisotropy of the crystal upon substitution leads to an increase in the energy gap in the ferromagnetic resonance spectrum to 121.5 GHz at T = 4.2 K.
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16.

Вид документа : Статья из журнала
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Автор(ы) : Udod L. V., Aplesnin S. S., Sitnikov M. N., Romanova O. B., Molokeev M. S.
Заглавие : Phase transitions in bismuth pyrostannate upon substitution of tin by iron ions
Место публикации : J. Alloys Compd. - 2019. - Vol. 804. - P.281-287. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2019.07.020
Примечания : Cited References: 44. - The reported study was funded by RFBR according to the research project № 18-52-00009 Bel_a; The reported study was funded by Russian Foundation for Basic Research , Government of Krasnoyarsk Territory , Krasnoyarsk Regional Fund of Science № 18-42-240001 r_a, to the research project: «Inversion of the sign of the components of the magnetoelectric tensor on the temperature in films of bismuth garnet ferrite replaced by neodymium». This work is part of the research program the state order № 3.5743.2017/6.7.
Аннотация: The Bi2(Sn1-хFeх)2O7 (х = 0, 0.1, 0.2) compounds have been synthesized by the solid-state reaction technique. The structure of the synthesized compounds has been investigated in the temperature range of 80–500 K using the thermal expansion and ultrasound damping coefficients and IR spectroscopy. The shift -type structural transitions for the composition with х = 0.2 in the low-temperature region has been established. The effect of iron ions on the phase boundaries of the polymorphic transitions in the Bi2Sn2O7 compound has been observed. Softening of the phonon modes near the phase transitions at different iron concentrations has been found.
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17.

Вид документа : Статья из журнала
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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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18.

Вид документа : Статья из журнала
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Автор(ы) : Kartashev A. V., Flerov I. N., Gorev M. V., Mikhashenok N. V.
Заглавие : Effect of Isovalent Cation Substitution on the Thermal, Caloric, and Magnetocaloric Properties of the (La1 – yEuy)0.7Pb0.3MnO3 Manganites
Место публикации : Phys. Solid State. - 2019. - Vol. 61, Is. 1. - P.62-68. - ISSN 10637834 (ISSN) , DOI 10.1134/S1063783419010116
Примечания : Cited References: 27. - This study was supported by the Russian Foundation for Basic Research, the Government of the Kras-noyarsk Territory, and the Krasnoyarsk Territorial Foundation for Support of the Scientific and R&D Activity, project no. 17-42-240076 “Complex Approach to Searching and Development of Promising Solid-State Ferroic Cooling Agents Based on the Single-and Multicaloric Effects.” The authors thank M.S. Molokeev for structural characterization of the composites.
Аннотация: Crystalline samples of the (La1 – yEuy)0.7Pb0.3MnO3 (y = 0, 0.2, 0.4, 0.5, 0.6, and 0.8) manganite solid solutions have been grown. Temperature dependences of the specific heat, thermal expansion, and high-intensity magnetocaloric effect have been investigated. A comparative analysis of the effect of isovalent cationic substitution on the thermal and caloric parameters of the ferromagnetic phase transition has been made. It has been shown that the growth of the Eu atom concentration leads to a decrease in the phase transition entropy and an increase in the baric coefficient dT/dp. Field and temperature dependences of the magnetocaloric effect have been established. It is demonstrated that, varying the ratio of cations, one can obtain the solid solutions with the maximum magnetocaloric effect value in fields of up to 6 kOe in a temperature range of 90–340 K. Owing to the similar reduced relative cooling powers, the investigated solid solutions can be used as reference solid-state cooling media in designing the cascade cooling systems.
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19.

Вид документа : Статья из журнала
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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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20.

Вид документа : Статья из журнала
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Автор(ы) : Li, Mingze, Li, Yawen, Molokeev M. S., Zhao, Jing, Na, Guangren, Zhang, Lijun, Xia, Zhiguo
Заглавие : Halogen substitution in zero-dimensional mixed metal halides toward photoluminescence modulation and enhanced quantum yield
Место публикации : Adv. Opt. Mater. - 2020. - Vol. 8, Is. 16. - Ст.2000418. - ISSN 2195-1071, DOI 10.1002/adom.202000418
Примечания : Cited References: 34. - M.L., Y.L. contributed equaly to this work. This work was supported by the National Natural Science Foundation of China (51961145101, 51972118, and 51722202), Fundamental Research Funds for the Central Universities (FRFTP-18-002C1), the Guangdong Provincial Science &Technology Project (2018A050506004), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01 x 137). This work was also funded by RFBR according to the research project No. 19-52-80003. The work at Jilin University is supported by the National Natural Science Foundation of China (Grant No. 61722403 and 11674121) and Jilin Province Science and Technology Development Program (Grant No. 20190201016JC). Calculations were performed in part at the high performance computing center of Jilin University.
Предметные рубрики: WHITE-LIGHT EMISSION
PEROVSKITES
EXCITONS
Аннотация: Zero‐dimensional (0D) organic−inorganic hybrid metal halides haveunprecedented degrees of freedom for structural tunability and photoluminescence modulation. Here, the 0D isomorphic hybrid metal mixed halides (C9NH20)9Pb3Zn2Br19(1−x )Cl19x (x = 0–1) with continuous halogen contents control, exhibiting tunable emission and enhancement of photoluminescence quantum yield (PLQY) are reported. The competitive bromine to chlorine substitution process in (C9NH20)9Pb3Zn2Br19(1−x )Cl19x occurs first in [ZnBr4−x Clx ]2− tetrahedron before the [Pb3Br11−x Clx ]5− trimer. The increasing Cl content in samples from x = 0 to 1 results in an expected blue shift of emission peak from 565 to 516 nm, and meanwhile a strikingly room temperature PL quantum yield increase from 8% to 91%. Combined experimental characterizations and theoretical calculations indicate that the blue shift of interband transition energy is responsible for the emission peak shift. Moreover, with the increasing Cl content, the enhanced electron−phonon interaction and the weakened thermal‐assisted nonradiative recombination result in more efficient radiative transition channels and ultimately enhanced PLQY. The impact of halogen substitution on electronic structures and optical properties in 0D hybrid metal halides is emphasized in this work as a new strategy to promote the future development of new luminescent materials.
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