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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Banerjee S., Saikia S., Molokeev M. S., Nag A.
Заглавие : Unveiling temperature-induced structural phase transition and luminescence in Mn2+-doped Cs2NaBiCl6 double perovskite
Колич.характеристики :8 с
Место публикации : Chem. Mater. - 2024. - Vol. 36, Is. 9. - P.4750-4757. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.4c00514. - ISSN 15205002 (eISSN)
Примечания : Cited References: 49. - Authors acknowledge Dr. Arup Rath’s lab NCL Pune and SAIF-IIT Bombay for diffuse reflectance spectroscopy and ICP-AES measurements, respectively. A.N. acknowledges Science & Engineering Research Board, India, for Swarnajayanti Fellowship (SB/SJF/2020-21/02), and BRICS grant (e-27558) of the Department of Science and Technology, India. Authors acknowledge the Department of Science and Technology India (FIST program, SR/FST/CS-II/2019/105) for temperature-dependent powder XRD and EPR data. S.B. is grateful to IISER Pune for a research fellowship. S.S. acknowledges Prime Minister’s Research Fellowship (PMRF), Ministry of Education, India. M.M. acknowledges the Russian Science Foundation, grant 24-43-00006
Аннотация: Halide double perovskites like Cs2NaBiCl6 are good host materials for luminescent dopants like Mn2+. The nature of photoluminescence (PL) depends on the local structure around the dopant ion, and doping may sometimes influence the global structure of the host. Here, we unveil the correlation between the temperature-induced (global) structural phase transition of Mn2+-doped Cs2NaBiCl6 with the local structure and PL of the Mn2+ dopant. X-ray diffraction analysis shows Mn2+-doped Cs2NaBiCl6 is in a cubic (Fm3m) phase between 300 and 110 K, below which the phase changes to tetragonal (I4/mmm), which persists at least until 15 K. The small (∼1%) doping amount does not alter the phase transition behavior of Cs2NaBiCl6. Importantly, the phase transition does not influence the Mn2+ d-electron PL. The PL peak energy, intensity, spectral width, and lifetime do not show any signature of the phase transition between 300–6 K. The hyperfine splitting in temperature-dependent electron paramagnetic spectra of Mn2+ ions also remain unchanged across the phase transition. These results suggest that the global structural phase transition of the host does not influence the local structure and emission property of the dopant Mn2+ ion. This structure–property insight might be explored for other transition-metal- and lanthanide-doped halide double perovskites as well. The stability of dopant emission regardless of the structural phase transition bodes well for their potential applications in phosphor-converted light emitting diodes.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Guan M., Hao J., Qiu L., Molokeev M. S., Ning L., Dai Zh., Li G.
Заглавие : Two-dimensional hybrid perovskite with high-sensitivity optical thermometry sensors
Колич.характеристики :8 с
Место публикации : Inorg. Chem. - 2024. - Vol. 63, Is. 8. - P.3835-3842. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.3c04140. - ISSN 1520510X (eISSN)
Примечания : Cited References: 37. - This work was supported by the National Natural Science Foundation of China (Grant Nos. 52072349, 52172162, 12374386, and 11974022). Z.D. acknowledges support from the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (No.162301202610), the Natural Science Foundation of Guangdong Province (2022A1515012145), and Shenzhen Science and Technology Program(JCYJ20220530162403007). G.L. acknowledges support from the Natural Science Foundation of Zhejiang Province (LR22E020004). M.M. acknowledges the support from the Ministry of Science and High Education of Russian Federation (Project No. FSRZ-2023-0006)
Аннотация: Optical thermometry has gained significant attention due to its remarkable sensitivity and noninvasive, rapid response to temperature changes. However, achieving both high absolute and relative temperature sensitivity in two-dimensional perovskites presents a substantial challenge. Here, we propose a novel approach to address this issue by designing and synthesizing a new narrow-band blue light-emitting two-dimensional perovskite named (C8H12NO2)2PbBr4 using a straightforward solution-based method. Under excitation of near-ultraviolet light, (C8H12NO2)2PbBr4 shows an ultranarrow emission band with the full width at half-maximum (FWHM) of only 19 nm. Furthermore, its luminescence property can be efficiently tuned by incorporating energy transfer from host excitons to Mn2+. This energy transfer leads to dual emission, encompassing both blue and orange emissions, with an impressive energy transfer efficiency of 38.3%. Additionally, we investigated the temperature-dependent fluorescence intensity ratio between blue emission of (C8H12NO2)2PbBr4 and orange emission of Mn2+. Remarkably, (C8H12NO2)2PbBr4:Mn2+ exhibited maximum absolute sensitivity and relative sensitivity values of 0.055 K–1 and 3.207% K–1, respectively, within the temperature range of 80–360 K. This work highlights the potential of (C8H12NO2)2PbBr4:Mn2+ as a promising candidate for optical thermometry sensor application. Moreover, our findings provide valuable insights into the design of narrow-band blue light-emitting perovskites, enabling the achievement of single-component dual emission in optical thermometry sensors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин С. Н., Дудников, Вячеслав Анатольевич, Наслузов В. А., Соловьев Л. А.
Заглавие : Синтез и устойчивость фаз Раддлесдена-Поппера (Sr0.8Ln0.2)3Со2O7-δ (Ln=Sm, Gd, Dy)
Колич.характеристики :10 с
Место публикации : Журн. СФУ. Химия. - 2024. - Т. 17, № 2. - С. 279-288. - ISSN 19982836 (ISSN); J. Sib. Fed. Univ. Chem. - ISSN 23136049 (eISSN)
Примечания : Библиогр.: 29. - Работа выполнена в рамках государственного задания Института химии и химической технологии СО РАН (проект FWES 2021-0013). Синтез образцов выполнен в рамках научной тематики Госзадания Института физики СО РАН
Аннотация: В работе приведены результаты квантово-химического расчета стабильности фазы Раддлесдена-Поппера (Sr1-хGdx)3Со2O7-δ (RP2) в зависимости от распределения катионов Gd3+/Sr2+ и наличия кислородных вакансий. Показано, что при х˂0.208 как катионы Gd3+, так и кислородные вакансии локализуются в перовскитном слое, что приводит к стабилизации структуры. На примере стронций-редкоземельного кобальтита состава (Sr0.8Ln0.2)3Со2O7-δ (Ln=Sm, Gd, Dy) экспериментально продемонстрирована возможность получения отсутствующих на фазовых диаграммах метастабильных фаз RP2.The paper presents the results of a quantum chemical calculation of the stability of the Ruddlesden-Popper phase (Sr1-xGdx)3Co2O7-δ (RP2) depending on the distribution of Gd3+/Sr2+ cations and the presence of oxygen vacancies. It has been shown that at x˂0.208 both Gd3+ cations and oxygen vacancies are localized in the perovskite layer, which leads to structure stabilization. New metastable RP2 phases of strontium-rare earth cobaltites with (Sr0.8Ln0.2)3Co2O7-δ composition (Ln=Sm, Gd, Dy) were synthesized and characterized, these phases being absent from the phase diagrams in air.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I.
Заглавие : Lattice source for charge and spin inhomogeneity in 2D perovskite cuprates
Колич.характеристики :5 с
Место публикации : Phys. B: Condens. Matter. - 2024. - Vol. 673. - Ст.415457. - ISSN 09214526, DOI 10.1016/j.physb.2023.415457. - ISSN 18732135
Примечания : Cited References: 31. - We acknowledge the support of the Russian Science Foundation through grant RSF No. 22-22-00298
Аннотация: In the work we highlight the structural features of 2D perovskite cuprates (tilted CuO6 octahedra with different orientation with respect to spacer rocksalt layers), where sources of charge and spin inhomogeneity can be hidden. We used the impurity Anderson model with the Jahn–Teller(JT) local cells to show the charge inhomogeneity arises at any low doping concentration x, but disappears when the doping level exceeds threshold concentration xc, and the smaller the magnitudes xc, the larger the area of regions with JT pseudo effect. It is expected that spontaneous chiral symmetry breaking in the dynamic JT state of the stripe CuO2 layer as a whole can lead to the appearance of the goldstone phonon mode. As consequence, the giant thermal Hall effect could be observed in the 2D perovskite cuprates with CuO6 octahedra, rather than with CuO4 squares, e.g. in the Tl-based n layer cuprates or cuprates based on infinite-layer CaCuO2 structure.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Krylova S. N., Popova E. A., Kitaev Yu. E., Lushnikov S. G.
Заглавие : Lattice dynamics of the BaMg1/3Ta2/3O3 complex perovskite
Коллективы : Уральский Федеральный университет им. Первого Президента России Б.Н. Ельцина, Ural Federal University, "Materials science and nanotechnology", International conference
Место публикации : Materials Science and Nanotechnology (MSN-2023): abstract book of International conference/ Ural Federal University; org. com. A. N. Vtyurin [et al.]. - Ekaterinburg, 2023. - Ст.O14. - P.54. - ISBN 978-5-9500624-6-9
Примечания : Cited References: 9. - Russian Foundation for Basic Research and DFG project No 21-52-12018
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин, Сергей Николаевич, Дудников, Вячеслав Анатольевич, Рабчевский, Евгений Владимирович, Соловьев, Леонид Александрович
Заглавие : Особенности формирования перовскитоподобных фаз Раддлесдена — Поппера на основе редкоземельных оксидов
Колич.характеристики :6 с
Место публикации : Труды Кольского научн. центра РАН. Сер. технич. науки. - 2023. - Vol. 14, Is. 3. - С. 76-81. - ISSN 29491215 (ISSN), DOI 10.37614/2949-1215.2023.14.3.013; Trans. Kola Sci. Centre RAS. Ser. Eng. Sci.
Примечания : Библиогр.: 14. - Статья выполнена при поддержке федерального бюджета по теме государственного задания Института химии и химической технологии ФИЦ КНЦ СО РАН № 0287-2021-00-13 с использованием оборудования Красноярского регионального центра коллективного пользования ФИЦ КНЦ СО РАН
Аннотация: В работе с использованием доступных в литературе термодинамических данных исследована зависимость величины ∆G0n,f (стандартной свободной энергии Гиббса образования фаз Раддлесдена — Поппера RPn) от значения параметра n в ряду AO∙(ABO3)n, где A = Са, Sr, Ba, La; B = Co, Ni, Ti, Zr, Hf. Обнаружено, что величина ∆G01/n,f фаз RPn для всех изученных систем линейно зависит от 1/n. Проанализированы следствия существования линейной зависимости с позиций проведения синтеза фаз RPn. На примере стронцийредкоземельных кобальтитов состава (SrxLn1-x)n+1СоnO3n+1 (Ln = Sm, Gd, Dy; n = 2, ∞) продемонстрирована возможность получения фаз RPn с различным характером распределения катионов Sr/Ln по А-позициям кристаллической решетки, приведены условия стабилизации новых метастабильных фаз (SrxLn1-x)3Со2O7-δ, отсутствующих на фазовых диаграммах.The dependence of the value of ∆G0n,f (the standard Gibbs free energy of Ruddlesden-Popper RPn phase formation) on the n-value in the series AO∙(ABO3)n (where A = Ca, Sr, Ba, La; B = Co, Ni, Ti, Zr, Hf) was analyzed using the thermodynamic data available in the literature. It is found that the value of ∆G01/n,f for all analyzed systems depends linearly on 1/n. The consequences of the existence of the linear dependence are analyzed from the point of view of carrying out the synthesis of the RPn phases. On the example of strontium-rare-earth cobaltites of the composition (SrxLn1-x)n+1СоnO3n+1 (Ln = Sm, Gd, Dy; n = 2, ∞), the possibility of obtaining RPn phases with a different character of the distribution of Sr/Ln cations over the A-positions of the crystalline lattice, stabilization conditions for new metastable phases (SrxLn1-x)3Со2O7-δ, which are absent in the phase diagrams in air, are given.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I.
Заглавие : Magnetic interaction in doped 2D perovskite cuprates with nanoscale inhomogeneity: Lattice nonlocal effects vs. superexchange
Место публикации : Condens. Matter. - 2022. - Vol. 7, Is. 4. - Ст.57. - ISSN 24103896, DOI 10.3390/condmat7040057
Примечания : Cited References: 78. - This work was supported by the Russian Science Foundation, research grant RSF No.22-22-00298
Аннотация: We have studied the superexchange interaction Jij in doped 2D cuprates. The AFM interaction strongly depends on the state of the lattice of a CuO2 layer surrounded by two LaO rock salt layers. In a static U and D stripe nanostructure, the homogeneous AFM interaction is impossible due to the U/D/U… periodic stripe sequence and TN=0. In a dynamic stripe nanostructure, the ideal CuO2 layer with nonlocal effects and the homogeneous AFM interaction are restored. However, the interaction Jij decreases by the exponential factor due to partial dynamic quenching. The meaning of the transition from the dynamic to the static cases lies in the spontaneous θ-symmetry breaking with respect to the rotation of all the tilted CuO6 octahedra by an orientation angle δθ=n⋅(45°) (where n=1÷4) in the U and D stripe nanostructure of the CuO2 layer. Moreover, the structural features help to study various experimental data on the charge inhomogeneity, Fermi level pinning in the p type cuprates only and time reversal symmetry breaking from a unified point of view.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Skorobogatov S. A., Shaykhutdinov K. A., Balaev D. A., Pavlovskii M. S., Krasikov A. A., Terentjev K. Yu.
Заглавие : Spin dynamics and exchange interaction in orthoferrite TbFeO3 with non-Kramers rare-earth ion
Место публикации : Phys. Rev. B. - 2022. - Vol. 106, Is. 18. - Ст.184404. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.106.184404
Примечания : Cited References: 41. - We acknowledge A. Podlesnyak for help with INS experiments and S. E. Nikitin for stimulating discussion. The reported study was funded by RFBR, Project No. 20-32-90142. This research used resources at Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory
Аннотация: The low-temperature spin dynamics of the orthorhombic TbFeO3 perovskite has been studied. It has been found that the inelastic neutron scattering (INS) spectrum of the investigated compound contains two modes corresponding to different sublattices. It is shown that the iron subsystem orders antiferromagnetically at TN=632 K and exhibits the high-energy magnon dispersion. The magnetic dynamics of this subsystem has been described within the linear spin wave theory and the in-plane and out-of-plane exchange anisotropy has been demonstrated. The approach proposed previously to describe the magnon dispersion in the TmFeO3 compound has been used. Three levels of the nondispersive crystal electric field corresponding to Tb3+ ions have been found in the energy region below 40 meV at about 17, 26, and 35 meV. The behavior of the magnetic correlation length of the terbium subsystem has been determined by studying the diffuse scattering at different temperatures. The evolution of this subsystem has been numerically described within the point charge model. It is shown that the numerical data agree satisfactorily with the experiment and with the general concept of the single-ion approximation applied to the rare-earth subsystem of orthorhombic perovskites.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mao Y., Zhang J., Ren Q., Molokeev M. S., Zhou G., Zhang X. -M.
Заглавие : Unveiling the uncommon blue-excitable broadband yellow emission from self-trapped excitons in a zero-dimensional hybrid tellurium-based double perovskite
Место публикации : J. Mater. Chem. C. - 2022. - Vol. 10, Is. 46. - P.17638-17645. - ISSN 20507526 (ISSN), DOI 10.1039/d2tc03150g. - ISSN 20507534 (eISSN)
Примечания : Cited References: 56. - This work was supported by the Natural Science Foundation of Shanxi Province (No. 20210302124054), the National Natural Science Foundation of China (No. 21871167), the Science and Technology Innovation Project of Colleges and Universities in Shanxi Province (No. 2021L262), the 1331 Project of Shanxi Province and the Postgraduate Innovation Project of Shanxi Normal University (No. 2021XSY040), and funded by RFBR according to the research project no. 19-52-80003
Аннотация: Low-dimensional metal halides with ns2 lone-pair electrons have been recognized as new generation luminescent emitters for various optoelectronic applications. However, 5s2 configuration tellurium halides have not received substantial attention despite their fascinating photoluminescence (PL) properties. Here, a hybrid tellurium-based double perovskite of (C20H20P)2TeCl6 is developed, in which the [TeCl6]2− octahedra are completely surrounded by [C20H20P]+ organic cations to form a unique zero-dimensional (0D) “host–guest” structure. An uncommon broadband yellow emission peaking at 570 nm with ultra-broad excitation from ultraviolet to blue light is excavated, which originates from the triplet self-trapped exciton (STE) emission of Te4+. Moreover, the 5s2 electronic transition mechanism of Te4+ is systematically revealed in depth, benefiting from the temperature-dependent fluorescence dynamic analysis and auxiliary theoretical calculations. It is concluded that the distortion degree of the [TeCl6]2− octahedron comprehensively affects the full width at half-maximum (FWHM) (positive correlation), Stokes shift (negative correlation) and PL intensity (negative correlation) with increasing temperatures. This work sheds new light on the PL behaviour of Te4+ and opens up a feasible avenue for blue-excitable broadband emissions in low-dimensional organic–inorganic hybrid double perovskites.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Vereshchagin S. N., Solov’ev L. A., Gavrilkin S. Y., Tsvetkov A. Y., Sitnikov M. V., Orlov Yu. S.
Заглавие : Structure of metastable Sr0.8Dy0.2Co3-δ phases and their electrical and magnetic properties
Место публикации : J. Exp. Theor. Phys. - 2022. - Vol. 134, Is. 3. - P.290-299. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776122030037
Примечания : Cited References: 40. - Investigation was supported by the Russian Foundation for Basic Research (grant no. 19-03-00017). Thermal and X-ray diffraction studies were conducted in the framework of State Task 0287-2021-0013 for the Institute of Chemistry and Chemical Technologies, Siberian Branch, Russian Academy of Sciences
Аннотация: Polycrystalline Sr0.8Dy0.2Co3-δ complex cobalt oxides with a different amount of oxygen (δ = 0.26, 0.44, 0.46) have been prepared by solid-state synthesis. An increase in oxygen deficiency causes the brownmillerite phase to appear in the perovskite structure, which significantly changes its properties. At δ = 0.46, the content of the brownmillerite phase reaches 38%. A comparative analysis of the magnetic and transport properties of synthesized samples has been carried out. The asymptotic Curie temperature changes sign from positive at δ = 0.26 to negative at δ = 0.46. The magnetoresistance of the sample with δ = 0.46 is negative and exceeds 40% at T = 10 K. The temperature dependence of resistivity is characteristic of semiconductors, and the absolute values for samples at low temperatures differ almost tenfold.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gao P. -X., Dong P., Zhou Z. -Y., Zhang X. -J., Li Y. -N., Yang J. -K., Li Q., Chen K., Molokeev M. S., Zhou Z., Xia M.
Заглавие : Novel far-red phosphors (La, Gd, Y)2MgTiO6:Cr3+ with tunable luminescence spectra for grow light
Разночтения заглавия :
Место публикации : Faguang Xuebao/Chin. J. Lumines. - 2022. - Vol. 43, Is. 1. - P.58-68. - ISSN 10007032 (ISSN), DOI 10.37188/CJL.20210327
Примечания : Cited References: 27. - Supported by National Natural Science Foundation of China(51974123); The Distinguished Youth Foundation of Hunan Province(2020JJ2018); Key R & D Projects in Hunan Province(2020WK2016&2020SK2032&2022NK2044), Hunan High Level Talent Gathering Project(2019RS1077&2020RC5007); Natural Science Foundation of Hunan Province(2021JJ40261); The Scientific Research Fund of Hunan Provincial Education Department(19C0903); 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)
Аннотация: Cr3+-activated double perovskite structure phosphor has drawn wide attention due to its far-red and near-infrared emission. In this work, we synthesized a series of (La,Gd,Y)2MgTiO6∶Cr3+ phosphors which can be excited by ultraviolet light of about 345 nm, and the emission bands are in the range of 700-900 nm. The spectra were tuned by ions substitution strategy. The main emission peaks were blue shifted from 766 nm to 737 nm and 757 nm by substituting the La site with Gd and Y, respectively. Meanwhile, the thermal stability at 150 ℃ increased from 41.7% to 69.1% and 67%, respectively. The crystal structure, microstructure, decay time, thermal stability and band gap were investigated systematically. The substitution of Gd/Y ions causes the lattice contraction, which results in the change of the nephelauxetic effect, and eventually leads to the blue shift of the spectra. The emission spectra of these phosphors have good matching with the 730 nm absorption peak of phytochrome FR(PFR), indicating their application prospect in plant growth lighting. Cationic substitution strategy can regulate the luminescence properties of Cr3+, which provides ideas for the development of phosphors for plant growth lamps in the future.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Павлов А. В., Квеглис, Людмила Иосифовна, Джес А. В., Сапрыкин Д. Н., Насибуллин Р. Т., Великанов, Дмитрий Анатольевич, Немцев, Иван Васильевич, Шалаев П. О.
Заглавие : Магнетизм бериллиевой керамики со структурой перовскита BeTiO3
Место публикации : Фундамент. пробл. совр. материаловед. - 2022. - Т. 19, № 1. - С. 115-124. - ISSN 1811-1416, DOI 10.25712/ASTU.1811-1416.2022.01.013; Basic Probl. Mater. Sci.
Примечания : Библиогр.: 24
Аннотация: Известно, что введение в ВеО-керамику добавки TiO2 после термообработки в восстановительной атмосфере сопровождается значительным увеличением электропроводности и способностью поглощать электромагнитное излучение в широком диапазоне частот. До сих пор механизм этого влияния до конца не установлен. С использованием методов Лоренцевой электронной микроскопии в сканирующем электронном микроскопе, а также вибрационного магнитометра, установлено проявление ферромагнетизма. Такая особенность бериллиевой керамики способствует поглощению электромагнитной энергии в объемных образцах, содержащих наночастицы TiO2. Установлено, что присутствие наночастиц способствует формированию структуры перовскита в зонах спекания BeO + TiO2. В структуре перовскита возможна поляризация молекул за счет формирования поляронов, что приводят к деформации решетки и смещению атомов. В результате такого смещения происходит изменение ближнего порядка в структуре перовскита и к образованию икосаэдрической фазы из исходной фазы со структурой кубоктаэдра. Малый размер атома бериллия позволяет организоваться тетраэдрической плотной упаковке в форме икосаэдра из атомов кислорода вокруг центрального атома бериллия. В результате повышается атомная плотность и плотность электронных состояний на уровне Ферми. Предлагаются модели для объяснения причины появления ферромагнетизма и электропроводности, которые обнаружены в бериллиевой керамике. С помощью метода спин-поляризованных электронов проведены расчеты электронной структуры нанокластеров с различным ближним порядком.It is known that the introduction of TiO2 additives into BeO ceramics after heat treatment in a reducing atmosphere is accompanied by a significant increase in electrical conductivity and the ability to absorb electromagnetic radiation in a wide frequency range. Until now, the mechanism of this influence has not been fully established. Using the methods of Lorentzian electron microscopy in a scanning electron microscope, as well as a vibration magnetometer, the manifestation of ferromagnetism was established. This feature of beryllium ceramics promotes the absorption of electromagnetic energy in bulk samples containing TiO2 nanoparticles. It was found that the presence of nanoparticles promotes the formation of the perovskite structure in the BeO + TiO2 sintering zones. In the structure of perovskite, polarization of molecules is possible due to the formation of polarons, which leads to deformation of the lattice and displacement of atoms. As a result of this displacement, a change in the short-range order in the perovskite structure occurs and to the formation of an icosahedral phase from the initial phase with a cuboctahedral structure. The small size of the beryllium atom makes it possible to organize a tetrahedral close packing in the form of an icosahedron of oxygen atoms around the central beryllium atom. As a result, the atomic density and the density of electronic states at the Fermi level increase. Models are proposed to explain the reasons for the appearance of ferromagnetism and electrical conductivity found in beryllium ceramics. Using the spin-polarized electron method, the electronic structure of nanoclusters with different short-range orders has been calculated.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Guojun, Ding, Jialiang, Jiang, Xingxing, Zhang, Jian, Molokeev M. S., Ren, Qiqiong, Zhou, Jun, Li, Shili, Zhang, Xian-Ming
Заглавие : Coordination units of Mn2+ modulation toward tunable emission in zero-dimensional bromides for white light-emitting diodes
Место публикации : J. Mater. Chem. C. - 2022. - Vol. 10, Is. 6. - P.2095-2102. - ISSN 2050-7526, DOI 10.1039/d1tc05680h. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 57. - The present work was supported by the Natural Science Foundation of China (21871167), the 1331 Project of Shanxi Province and the Postgraduate Innovation Project of Shanxi Normal University (2019XBY018), the Beijing Natural Science Foundation (No. 2214068) and funded by RFBR according to the research project no. 19-52-80003
Предметные рубрики: HALIDE PEROVSKITE NANOCRYSTALS
RECENT PROGRESS
DOPING MN2+
Аннотация: Organic–inorganic metal halides have become a multifunctional platform for manipulating photoluminescence due to highly efficient and tunable emissions, especially for lead-free Mn2+-based halides. Herein, the zero-dimensional (0D) bromides of (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 with different coordination environments were designed and synthesized by a solvent evaporation method. They exhibit green and red broadband emission peaks at 528 nm and 627 nm with high photoluminescence quantum yields of 86.83% and 61.91%, respectively, which are attributed to the d–d transition (4T1(G) → 6A1(S)) of [MnBr4]2− tetrahedral and [Mn3Br12]6− octahedral units. The cases emphasize the effect of organic ligands on the intrinsic emissions of Mn2+ ions, thereby revealing the luminescence mechanism of Mn2+ ions in 0D isolated structures through the Tanabe–Sugano (TS) energy diagram. Thanks to their bright and stable emissions, the fabricated white light-emitting diode (LED) based on (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 provides an outstanding color rendering index (Ra) of 90.8 at a correlated color temperature (CCT) of 3709 K, along with the CIE chromaticity coordinates of (0.3985, 0.3979) and a luminous efficacy of 51.2 lm W−1. This work aims at clarifying the relationship between the coordination units of Mn2+ and tunable emissions, and in particular, proposes a new strategy to explore phosphors excited by blue light for white LEDs.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Jun, Rong, Ximing, Molokeev M. S., Wang, Yulong, Yun, Xiangyan, Xu, Denghui, Li, Xiong
Заглавие : Alloying Cs+ into Rb2ZrCl6:Te4+ toward highly efficient and stable perovskite variants
Коллективы : Beijing Natural Science FoundationBeijing Natural Science Foundation [2214068]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [61705003]; Beijing Technology and Business University Research Team Construction Project [PXM2019_014213_000007, PXM2020_014213_000017]
Место публикации : Mat. Chem. Front. - 2021. - Vol. 5, Is. 13. - P.4997-5003. - ISSN 2052-1537(eISSN), DOI 10.1039/d1qm00302j
Примечания : Cited References: 37. - This work is supported by Beijing Natural Science Foundation (No. 2214068), the National Natural Science Foundation of China (No. 61705003), and the Beijing Technology and Business University Research Team Construction Project (No. PXM2019_014213_000007 and PXM2020_014213_000017)
Предметные рубрики: TELLER
PHOTOLUMINESCENCE
TELLURIUM(IV)
COMPLEXES
PHOSPHORS
Аннотация: Doping or alloying in perovskites and perovskite variants provides a promising way for modulating the electronic and photoluminescence properties and the structural stability. In this work, a series of yellow-emitting Rb2−xCsxZrCl6:Te4+ solid solution phosphors were prepared by a hydrothermal method, and their broad emission is assigned to the triplet 3P1–1S0 self-trapped excitons (STEs). Upon increasing the alloying ion Cs+, the yellow emission can be greatly enhanced by a stronger Jahn–Teller distortion. Moreover, Cs2ZrCl6:Te4+ shows a high photoluminescence quantum yield (PLQY), and impressive thermal and anti-water stability. This doping–alloying strategy presents a new direction towards designing lead-free, high-performance and stable perovskite derivatives.
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gavrichkov V. A.
Заглавие : Superexchange in 2D perovskite HTSC with stripe nanostructure
Коллективы : "Functional materials", International conference, Крымский федеральный университет имени В.И. Вернадского
Место публикации : Ovchinnikov S. G. International conference "Functional materials": book of abstracts/ ed. V. N. Berzhansky ; org. com. S. G. Ovchinnikov [et al.]. - Simferopol, 2021. - P.223-2224
Примечания : Библиогр.: 3 назв. - The reported study was supported by the grant RFFI 19-02-00034 and the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, and Krasnoyarsk Regional Fund of Science according to the research project ”Studies of superexchange and electron-phonon interactions in correlated systems as a basis for searching for promising functional materials No. 20-42-240016.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pavlov A. V., Kveglis L. I., Saprykin D. N., Nasibullin R. T., Kalitova A. A., Velikanov D. A., Nemtsev I. V., Kantai N.
Заглавие : Emergence of ferromagnetism in nanoparticles of BeTiO3 ceramic with the perovskite structure
Место публикации : Inorg. Mater.: Appl. Res. - 2021. - Vol. 12, Is. 1. - P.88-93. - ISSN 20751133 (ISSN), DOI 10.1134/S2075113321010330
Примечания : Cited References: 21. - The part of the work involving calculations was supported by the Russian Science Foundation (grant no. 18-19-00268)
Аннотация: Emergence of ferromagnetism and an increase in the electrical conductance of BeTiO3 beryllium ceramic with the perovskite structure were discovered experimentally. To explain the reason for appearance of the metallic properties, models are proposed, and calculations of the electronic structure of nanoclusters with different short-range order are performed.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xiao, Hui, Dang, Peipei, Yun, Xiaohan, Li, Guogang, Wei, Y.i., Xiao, Xiao, Zhao, Yajie, Molokeev M. S., Cheng, Ziyong, Lin, Jun
Заглавие : Solvatochromic Photoluminescent Effects in All-Inorganic Manganese(II)-Based Perovskites by Highly Selective Solvent-Induced Crystal-to-Crystal Phase Transformations
Место публикации : Angew. Chem. Int. Edit. - 2021. - Vol. 60, Is. 7. - P.3699-3707. - ISSN 1433-7851, DOI 10.1002/anie.202012383. - ISSN 1521-3773(eISSN)
Примечания : Cited References: 85. - This work was supported by National Natural Science Foundation of China (NSFC 51932009, 51772288, 52072349, 51672259) and the Joint Fund Project to Promote Science and Technology Cooperation Across the Taiwan Straits (U2005212), the Science and Technology Cooperation Fund between Chinese and Australian Governments (2017YFE0132300), CAS-Croucher Funding Scheme for Joint Laboratories (CAS18204), Chinese Academy of Sciences (YZDY-SSWJSC018)
Предметные рубрики: LEAD-FREE
HALIDE PEROVSKITE
NANOCRYSTALS
MN2+
LUMINESCENCE
Аннотация: The development of lead‐free perovskite photoelectric materials has been an extensive focus in the recent years. Herein, a novel one‐dimensional (1D) lead‐free CsMnCl3(H2O)2 single crystal is reported with solvatochromic photoluminescence properties. Interestingly, after contact with N,N‐dimethylacetamide (DMAC) or N,N‐dimethylformamide (DMF), the crystal structure can transform from 1D CsMnCl3(H2O)2 to 0D Cs3MnCl5 and finally transform into 0D Cs2MnCl4(H2O)2. The solvent‐induced crystal‐to‐crystal phase transformations are accompanied by loss and regaining of water of crystallization, leading to the change of the coordination number of Mn2+. Correspondingly, the luminescence changes from red to bright green and finally back to red emission. By fabricating a test‐paper containing CsMnCl3(H2O)2, DMAC and DMF can be detected quickly with a response time of less than one minute. These results can expand potential applications for low‐dimensional lead‐free perovskites.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S., Dudnikov V. A., Orlov Yu. S., Solovyov L.
Заглавие : Tetragonal to cubic transition of Sr0.8Dy0.2CoO3-δ and oxygen mobility: TG-DSC-XRD study
Место публикации : J. Alloys Compd. - 2021. - Vol. 860. - Ст.158257. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2020.158257
Примечания : Cited References: 35. - This work was conducted within the framework of the budget project (Project No. АААА-А17-117021310222-4) for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Centre of SB RAS and in part was funded by Russian Foundation for Basic Research (projects 19-03-00017), RFBR and BRFBR (project 18-52-00017), Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (project 18-42-243004)
Аннотация: Processes of ordering (d-o) and disordering (o-d) of Sr2+/Dy3+ cations in a single-phase Sr0.8Dy0.2CoO3-δ was investigated by TG-DSC and XRD as a function of heating/cooling rate (β = 2,10,20,50,99 K min−1 and ~50 K/s) in 20% O2-Ar flow. According to DSC data the interconversion of disordered cubic (c) and ordered tetragonal (t) structure appears at 1276–1328 K as a first-order phase transition; the temperature and enthalpy of o-d transformation have only slight dependence on β whereas the characteristics of reversed d-o process vary greatly with cooling rate. XRD powder patterns of all samples showed no indications of a simultaneous presence of c+t domains, pointing to a single phase composition (c or t). It was suggested that the observed behavior is a consequence of two simultaneous interconnected processes of A-sublattice melting and cation/ (anion vacancy) ordering. A rarely used novel TG-DSC method based on variable gas phase composition was utilized to study properties of mobile oxygen over Sr0.8Dy0.2CoO3-δ samples. It was shown that the appearance of tetragonal phase reduces both oxygen mobility and its bonding energy, the latter decreasing substantially only at high degree of Sr2+/Dy3+ ordering.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Su, Binbin, Molokeev M. S., Xia, Zhiguo
Заглавие : Unveiling Mn2+ dopant states in two-dimensional halide perovskite toward highly efficient photoluminescence
Место публикации : J. Phys. Chem. Lett. - 2020. - Vol. 11, Is. 7. - P.2510-2517. - ISSN 1948-7185, DOI 10.1021/acs.jpclett.0c00593
Примечания : Cited References: 49. - This work is supported by the National Natural Science Foundation of China (51961145101, 51972118, and 51722202), Fundamental Research Funds for the Central Universities (D2190980), the 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.
Предметные рубрики: LEAD BROMIDE PEROVSKITES
ENERGY-TRANSFER
EXCITON DYNAMICS
DOPING MN2+
Аннотация: Doping is able to create novel optoelectronic properties of halide perovskites, and the involved mechanism of efficient emission is still a challenge. Herein Mn2+ substitution into 2D layered perovskites (C8H20N2)PbBr4 was investigated, demonstrating broad-band orange-red emission originating from the 4T1 → 6A1 transition of Mn2+ dopant. The photoluminescence quantum yield (PLQY) of Mn2+ emission is up to 60.8% related to the energy transfer in coupled states. We verify that an actual Mn2+ dopant as low as 0.476% reaches a high PLQY, whereas the nominal adding amount is 0.8 as the Mn2+/Pb2+ ratio. The small activation energy (∼6.72 meV) between the Mn2+ d state and the trap state accounts for this highly efficient energy transfer and photoluminescence. The proposed luminescence mechanism in Mn2+-doped 2D halide perovskites would provide unique insights into the doping design toward high-performance luminescence materials.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Orlov Yu. S., Bushinsky M. V., Solovyov L. A., Vereshchagin S. N., Gavrilkin, S. Yu, Tsvetkov, A. Yu, Gorev M. V., Novikov S. V., Mantytskaya O. S., Ovchinnikov S. G.
Заглавие : Structural, magnetic, electronic, and dilatation properties of the ordered solid solutions Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-03-00017]; RFBRRussian Foundation for Basic Research (RFBR) [18-52-00017, F18R-119]; BRFFR [18-52-00017, F18R-119]; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory [18-42-243004, SB RAS V.45.3.3]
Место публикации : J. Alloy. Compd. - 2020. - Vol. 830. - Ст.154629. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2020.154629. - ISSN 1873-4669(eISSN)
Примечания : Cited References: 44. - The work was financially supported by Russian Foundation for Basic Research (grant No. 19-03-00017); RFBR and BRFFR as a part of scientific project No. 18-52-00017 and project F18R-119; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: "New thermoelectric materials based on multi-scale spatially inhomogeneous substituted rare-earth cobalt oxides and the Ruddlesden-Popper phases " project No. 18-42-243004, Project of Basic Research SB RAS V.45.3.3.
Предметные рубрики: LN(1-X)SR(X)COO(3-DELTA) LN
COBALTATE PEROVSKITES
Аннотация: Single-phase samples of the layered perovskite-like cobalt oxides Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ = 0.37 ± 0.01 were synthesized. All samples are characterized by a tetragonal unit cell with the space group I4/mmm. The structural, magnetic, electric transport and dilatation properties of the obtained samples are investigated. The studied samples are characterized by two anomalies in magnetic properties, a high-temperature maximum near Тm = 350 К with magnetic field hysteresis below Tm, and a diffuse peak in the intermediate temperature range, which shifts with ionic radius decrease of the rare-earth element to higher temperatures. The high-temperature maxima of the magnetic susceptibility correlate with anomalies in thermal expansion, heat capacity and the features in the temperature dependences of the electrical resistivity, pointing to a strong relationship between the structural, magnetic and electronic degrees of freedom. The given comparative analysis of the experimental data of various substituting rare-earth elements with the same oxygen nonstoichiometry has been carried out for the first time.
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