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1.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Romanova O. B., Ryabinkina L. I.
Заглавие : Peculiarities of the transport and magnetic properties of the cation substituted manganese sulphides
Место публикации : Ninth International workshop on Non–Crystalline solids, Porto 2008, p. 60
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2.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Fokina V.D., Flerov I.N., Molokeev M.S., Pogoreltsev E.I., Bogdanov E.V., Laptash N.M.
Заглавие : Effect of central cation substitution on the properties and phase transitions in (NH4)3Me(O2)2F4 oxyfluorides
Коллективы : International Seminar on Ferroelastic Physics
Место публикации : The 6th International Seminar on Ferroelastics Physics (ISFP-6): Voronezh, September 22–25, 2009. - С. 43
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Moshkina E. M., Chernyshev A., Vasil'ev A. D., Maximov N., Aleksandrovsky A. S., Andryushchenko T., Shabanov A. V.
Заглавие : Crystal growth and cation order of Ni3-xCoxB2O6 oxyborates
Колич.характеристики :15 с
Место публикации : CrystEngComm. - 2024. - Article in press. - ISSN 14668033 (eISSN), DOI 10.1039/D4CE00091A
Примечания : Cited References: 28. - The research was funded by Russian Science Foundation and Krasnoyarsk Regional Fund of Science, project № 23-12-20012 (https://rscf.ru/en/project/23-12-20012/)
Аннотация: A series of single crystals of Ni3-xCoxB2O6 compounds with the kotoite structure and with different concentrations of transition metal ions (x = 0; 0,19; 0,6; 0,93; 2) were obtained. The lattice parameters and atomic coordinates were determined using X-ray diffraction. The theoretical calculations using the WIEN2k package predict that nickel ions tend to occupy the 4f crystallographic position, while cobalt ions tend to occupy the 2a crystallographic positions. The study of the diffuse scattering spectra and comparison of the Racah parameters for the compounds Ni3B2O6 and Co2NiB2O6 provides experimental evidence that the nickel ions occupy crystallographic position 4f.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sofronova S. N., Pavlovskii M. S., Chernyshov A., Moshkina E. M., Velikanov D. A.
Заглавие : Exprerimental and theoretical study of the cation and magnetic ordering in NixCo3-xB2O6
Коллективы : Samarkand International Symposium on Magnetism, Samarkand State University
Место публикации : Book of abstacts of Samarkand International Symposium on Magnetism (SISM-2023)/ int. adv. com. S. G. Ovchinnikov [et al.]. - 2023. - Ст.2PO-L4-21. - P.119. - ISBN 978-5-00202-320-2
Примечания : Cited References: 3. - РНФ № 23-12-20012 ; Красноярский регион. фонд науки
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sofronova S. N., Pavlovsky M. S., Chernyshov A. V., Moshkina E. M., Velikanov D. A.
Заглавие : Theoretical study of the cation and magnetic ordering in NixCo3-xB2O6
Коллективы : International Baltic Conference on Magnetism, Балтийский федеральный университет им. И. Канта
Место публикации : V International Baltic Conference on Magnetism. IBCM: Book of abstracts. - 2023. - P.191
Примечания : Cited References: 3. - РФФИ № 23-12-20012
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6.

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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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ma, Yalin, Molokeev M. S., Zhu, Chuanhui, Zhao, Shuang, Han, Yifeng, Wu, Meixia, Liu, Sizhan, Tyson, Trevor A., Croft, Mark, Li, Man-Rong
Заглавие : Magnetic transitions in exotic perovskites stabilized by chemical and physical pressure
Место публикации : J. Mater. Chem. C. - 2020. - Vol. 8, Is. 15. - P.5082-5091. - ISSN 2050-7526, DOI 10.1039/c9tc06976c. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 79. - This work was financially supported by the National Science Foundation of China (NSFC-21801253, 11804404 and 21875287) and the National Science Foundation (NSF) Grant No. DMR-1809931. Structural analysis of exotic materials in this study was partly supported by the Research Grant No. 075-15-2019-1886 from the Government of the Russian Federation. The XANES work at the Brookhaven National Laboratory, NSLS-II, was supported by the DOEBES (DE-SC0012704). The NSLS-II work was performed on beamline 7-BM and the authors gratefully acknowledge the invaluable help of the beamline scientists Steven Ehrlich and Syed Khalid.
Предметные рубрики: COLOSSAL MAGNETORESISTANCE
CATION ORDER
RMN3O6 R
T-C
TEMPERATURE
Аннотация: Exotic perovskites significantly enrich materials for multiferroic and magnetoelectric applications. However, their design and synthesis is a challenge due to the mostly required recipe conditions at extremely high pressure. Herein, we presented the Ca2−xMnxMnTaO6 (0 ≤ x ≤ 1.0) solid solutions stabilized by chemical pressure assisted with intermediate physical pressure up to 7 GPa. The incorporation of Mn2+ into the A-site neither drives any cationic ordering nor modifies the orthorhombic Pbnm structure, namely written as (Ca1−x/2Mnx/2)(Mn1/2Ta1/2)O3 with disordered A and B site cationic arrangements. The increment of x is accompanied by a ferromagnetic to antiferromagnetic transition around x = 0.2, which is attributed to the double-exchange interactions between A-site Mn2+ and B-site Mn3+. Partial charge disproportionation of the B-site Mn3+ into Mn2+ and Mn4+ occurs for x above 0.8 samples as manifested by X-ray spectrum and magnetic behaviors. The coexistence of B-site Mn3+ (Jahn–Teller distortion ion) and B′-site Ta5+ (second-order Jahn–Teller distortion ion) could be energetically responsible for the absence of A-site columnar ordering as observed in other quadruple perovskites with half of the A-sites occupied by small transition-metal cations. These exceptional findings indicate that exotic perovskites can be successfully stabilized at chemical and intermediate physical pressure, and the presence of Jahn–Teller distortion cations at the same lattice should be avoided to enable cationic ordering.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Belskaya N. A., Moshkina E. M., Bezmaternykh L. N., Vasiliev A. D., Sofronova S. N., Eremina R. M., Eremin E. V., Muftakhutdinov A. R., Cherosov M. A., Ovchinnikov S. G.
Заглавие : Antiferromagnetism of the cation-ordered warwickite system Mn2-xMgxBO4 (x=0.5, 0.6 and 0.7)
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [20-02-00559]; Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science to the research project [18-42243007]
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 507. - Ст.166820. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2020.166820. - ISSN 1873-4766(eISSN)
Примечания : Cited References: 39. - The reported study was funded by the Russian Foundation for Basic Research (no. 20-02-00559), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project. 18-42243007.
Предметные рубрики: SPIN-GLASS BEHAVIOR
CRYSTAL-STRUCTURES
SINGLE-CRYSTALS
INSIGHTS
MGFEBO4
Аннотация: X-ray diffraction, heat capacity and magnetic measurements are performed on single crystals of Mn2-xMgxBO4 (x = 0.5, 0.6 and 0.7) with the warwickite structure. The monoclinic symmetry is found for all samples with the space group P21/n. The M1 site is occupied by trivalent Mn ions while the M2 site is occupied by a mixture of divalent Mg and Mn ions. Regular cation and charge distributions are observed, which is unusual for heterometallic warwickites. The local octahedral distortions of M1O6 show the monotonic dependence on the Mg content and are in accordance with the Jahn-Teller distortion. All samples are found to undergo long-range antiferromagnetic ordering with rather low transition temperatures of TN = 16, 14 and 13 K for x = 0.5, 0.6, and 0.7, respectively. The ordering of local octahedral distortions, caused by the strong electron-phonon interaction of the trivalent Mn ions, is proposed to stabilise the cationic ordering and, as a result, the long-range magnetic ordering in the material.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 9. - Ст.094409. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.094409. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 65. - We acknowledge the support of the Russian Science Foundation through Grant No. 18-12-00022
Предметные рубрики: EXCHANGE INTERACTION
PHASE-TRANSITIONS
STATE
ELECTRON
IRON
Аннотация: We derived simple rules for the sign of 180° superexchange interaction based on the multielectron calculations of the superexchange interaction in the transition metal oxides that are valid both below and above spin crossover under high pressure. The superexchange interaction between two cations in dn configurations is given by a sum of partial contributions related to the electron-hole virtual excitations to the different states of the dn+1 and dn−1 configurations. Using these rules, we have analyzed the sign of the 180° superexchange interaction of a number of oxides with magnetic cations in electron configurations from d2 until d8: the iron, cobalt, chromium, nickel, copper, and manganese oxides with increasing pressure. The most interesting result concerns the magnetic state of cobalt and nickel oxides CoO, Ni2O3 and also La2CoO4, LaNiO3 isostructural to well-known high-TC and colossal magnetoresistance materials. These oxides have a spin 12 at the high pressure. Change of the interaction from antiferromagnetic below spin crossover to ferromagnetic above spin crossover is predicted for oxide materials with cations in d5(FeBO3) and d7(CoO) configurations, while for materials with the other dn configurations spin crossover under high pressure does not change the sign of the 180∘ superexchange interaction.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Guzman G. N.A.D., Rajendran V., Bao Z., Fang M. -H., Pang W. -K., Mahlik S., Lesniewski T., Grinberg M., Molokeev M. S., Leniec G., Kaczmarek S. M., Ueda J., Lu K. -M., Hu S. -F., Chang H., Liu R. -S.
Заглавие : Multi-Site Cation Control of Ultra-Broadband Near-Infrared Phosphors for Application in Light-Emitting Diodes
Место публикации : Inorg. Chem. - 2020. - Vol. 59, Is. 20. - P.15101-15110. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.0c02055
Примечания : Cited References: 26. - The authors would like to acknowledge the support of the Ministry of Science and Technology of Taiwan (Contract Nos. MOST 109-2112-M-003-011, MOST 109-2113-M-002-020-MY3, MOST 107-2113-M-002-008-MY3, MOST 107-2923-M-002-004-MY3, and MOST 106-2112-M-003-007-MY3), the National Science Center Poland Grant Opus (No. 2016/23/B/ST3/03911), and the National Center for Research and Development Poland Grant (No. PL-TW/V/1/2018). T. Lesniewski would like to acknowledge the support of the National Science Center Poland, Grant Preludium 13 (No. 2017/25/N/ST3/02412)
Аннотация: Near-infrared (NIR) phosphors are fascinating materials that have numerous applications in diverse fields. In this study, a series of La3Ga5GeO14:Cr3+ phosphors, which was incorporated with Sn4+, Ba2+, and Sc3+, was successfully synthesized using solid-state reaction to explore every cationic site comprehensively. The crystal structures were well resolved by combining synchrotron X-ray diffraction and neutron powder diffraction through joint Rietveld refinements. The trapping of free electrons induced by charge unbalances and lattice vacancies changes the magnetic properties, which was well explained by a Dyson curve in electron paramagnetic resonance. Temperature and pressure-dependent photoluminescence spectra reveal various luminescent properties between strong and weak fields in different dopant centers. The phosphor-converted NIR light-emitting diode (pc-NIR LED) package demonstrates a superior broadband emission that covers the near-infrared (NIR) region of 650-1050 nm. This study can provide researchers with new insight into the control mechanism of multiple-cation-site phosphors and reveal a potential phosphor candidate for practical NIR LED application.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gai S., Zhu H., Gao P., Zhou C., Kong Z., Molokeev M. S., Qi Z., Zhou Z., Xia M.
Заглавие : Structure analysis, tuning photoluminescence and enhancing thermal stability on Mn4+-doped La2-xYxMgTiO6 red phosphor for agricultural lighting
Место публикации : Ceram. Int. - 2020. - Vol. 46, Is. 12. - P.20173-20182. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.05.095
Примечания : Cited References: 40. - The authors would like to gratefully acknowledge funds from the National Natural Science Foundation of China (Grant No. 21706060 , 51703061 , 51974123 ), the Hunan Graduate Research and Innovation Project (Grant No. CX2018B396 ), the Hunan provincial Engineering Technology Research Center for Optical Agriculture (Grant No. 2018TP2003 ), the Scientific Research Fund of Hunan Provincial Education Department (15K058, 19C0903), the Natural Sciences Foundation of Hunan agricultural university, China (Grant No. 19QN11), the Science and Technology project of Changsha (KH1801219) and the Huxiang high level talent gathering project (2019RS1077)
Аннотация: Currently, phosphor-converted LEDs (pc-LEDs) are revolutionizing the industry of plant growth lighting. To meet the requirements of this technology, phosphors with tunable photoluminescence, high thermal stability and luminous intensity are required. Herein, we found that the simple substitution of yttrium for lanthanum in La2MgTiO6:Mn4+ (LMT:Mn4+) system could satisfy above three criteria simultaneously. The photoluminescence properties can be regulated by continuously controlling the chemical composition of La2-xYxMgTiO6:Mn4+ solid solution. The La sites are occupied by Y ions, causing a significant blue shift in the emission spectra which owing to the change of local crystal field strengthen. Meanwhile, the thermal stability and decay lifetimes are also varied due to the variation of local structure and band gap energy. The thermal stability of the material reaches 83.5% at 150 °C, which is better than the reported La2MgTiO6:Mn4+ and Y2MgTiO6:Mn4+ phosphors. The electronic luminescence (EL) of pc-LED devices using La2-xYxMgTiO6:Mn4+ red phosphor is evaluated, which matching the absorption regions of plant pigments well, reflecting the superiority of the studied phosphors in plant growth lighting areas.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Guan M., Molokeev M. S., Zhou J.
Заглавие : Atomic deciphering of cation exchange mechanism in upconversion nanoparticles
Место публикации : J. Lumin. - 2020. - Vol. 224. - Ст.117289. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2020.117289
Примечания : Cited References: 36. - The authors acknowledge the Science and Technology Innovation Committee of Shenzhen (Grant No. KQTD20170810110913065), Australian Research Council (ARC) Discovery Early Career Researcher Award Scheme (J. Z., DE 180100669), and the China Scholarship Council (Ming Guan, No. 201506400025)
Аннотация: Transition metal ion doping in upconversion nanoparticles (UCNPs) provides an effective way to enhance the luminescence for their wide array of applications. However, the doping sites of transition metal ions have not been comprehensively explored, and commonly assumed that transition metal ions replace the trivalent lanthanides within the lattice. Here we report that cation exchange of transition metal (Mn2+) in β-NaYF4:Yb3+/Er3+ UCNPs occurs through alkaline metal (Na+) replacement, via 2Na+ ↔ Mn2+ + Vacancy reaction. This process distorts the LnF9 polyhedrons and tailors the surrounding environment around the trivalent lanthanides, thereby improving the upconversion intensity from active lanthanides. Further confirmed by core-shell design and spectroscopic study, we prove that the transition–alkaline metal exchange enables both the emission enhancement and transition probability variation of activators.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fang M. -H., Mahlik S., Lazarowska A., Grinberg M., Molokeev M. S., Sheu H. -S., Lee J. -F., Liu R. -S.
Заглавие : Structural Evolution and Effect of the Neighboring Cation on the Photoluminescence of Sr(LiAl3)1−x(SiMg3)xN4:Eu2+ Phosphors
Место публикации : Angew. Chem. Int. Ed. - 2019. - Vol. 58, Is. 23. - P.7767-7772. - ISSN 14337851 (ISSN), DOI 10.1002/anie.201903178
Примечания : Cited References: 23. - This work was supported by the Ministry of Science and Technology of Taiwan (Contract Nos. MOST 107‐2113‐M‐002‐008‐MY3 and MOST 107–2923‐M‐002‐004‐MY3). This work was supported by the National Science Centre Poland grant Opus no. 2016/23/B/ST3/03911 and the National Centre for Research and Development Poland Grant (No. PL‐TW/V/1/2018).
Предметные рубрики: Solid-Solution Phosphors
Аннотация: In this study, a series of Sr(LiAl3)1−x(SiMg3)xN4:Eu2+ (SLA‐SSM) phosphors were synthesized by a solid‐solution process. The emission peak maxima of SLA‐SSM range from 615 nm to 680 nm, which indicates structural differences in these materials. 7Li solid‐state NMR spectroscopy was utilized to distinguish between the Li(1)N4 and Li(2)N4 tetrahedra in SLA‐SSM. Differences in the coordination environments of the two Sr sites were found which explain the unexpected luminescent properties. Three discernible morphologies were detected by scanning electron microscopy. Temperature‐dependent photoluminescence and decay times were used to understand the diverse environments of europium ions in the two strontium sites Sr1 and Sr2, which also support the NMR analysis. Moreover, X‐ray absorption near‐edge structure studies reveal that the Eu2+ concentration in SLA‐SSM is much higher than that in in SrLiAl3N4:Eu2+ and SrSiMg3N4:Eu2+ phosphors. Finally, an overall mechanism was proposed to explain the how the change in photoluminescence is controlled by the size of the coordinated cation.
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14.

Вид документа : Статья из журнала
Шифр издания :
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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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) : Knyazev Yu. V., Shishkina N. N., Bayukov O. A., Kirik N. P., Solovyov L. A., Zhizhaev A. M., Rabchevsky E. V., Anshits A. G.
Заглавие : Cation Distribution in the Composite Materials of the CaFe2O4-α-Fe2O3 Series
Коллективы : Russian Foundation for Basic Research; Government of the Krasnoyarsk Krai; Krasnoyarsk Regional Science Foundation [18-42-243011]; UMNIK program
Место публикации : J. Struct. Chem. - 2019. - Vol. 60, Is. 5. - P.763-771. - ISSN 0022-4766, DOI 10.1134/S0022476619050081. - ISSN 1573-8779(eISSN)
Примечания : Cited References: 25. - The study was performed with the financial support of the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Krai, the Krasnoyarsk Regional Science Foundation within the project No. 18-42-243011 "The effect of the composition and the defective structure of CaFe2O4 based "core-shell" composite materials on their electronic and catalytic properties" and the UMNIK program.
Предметные рубрики: PD/P-TYPE CAFE2O4
OXYGEN
CONDUCTIVITY
Аннотация: Structured composite materials CaFe2O4-α-Fe2O3 (α-Fe2O3 content is 2–82 wt.%) are obtained with the method of solid-phase synthesis at 1000 °C. The phase composition of the samples is studied using powder X-ray diffraction. It is shown that the content of CaFe2O4 and α-Fe2O3 phases changes linearly, depending on the composition of the starting material. The scanning electron microscopy data indicate the formation of a two-phase system α-Fe2O3-CaFe2O4. The Mössbauer spectroscopy data at room temperature testify the formation of cationic iron vacancies in the CaFe2O4 crystal structure in the absence of α-Fe2O3 structural defects. Cationic vacancies can be formed during the synthesis in the atmosphere of air.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vasiliev A. D., Golovnev N. N.
Заглавие : Crystal Structure of Three Ionic Compounds of Levofloxacin
Место публикации : J. Struct. Chem. - 2019. - Vol. 60, Is. 12. - P.1959-1964. - ISSN 00224766 (ISSN), DOI 10.1134/S0022476619120114
Примечания : Cited References: 13. - The work was performed within the State Task of the Ministry of Education and Science of the Russian Federation to the Siberian Federal University for 2017-2019 (4.7666.2017/BCh)
Аннотация: The structures of three ionic compounds of levofloxacin (LevoH or Ci18H20FN3O4) − LevoH3[CoCl4]-H2O (I), LevoH3[ZnBr4]·H2O (II), LevoH3[CuBr4]-H2O·(III) are determined. The crystals of I-III are monoclinic; in compound III, the particles are packed so that the direction of the screw axis does not coincide with the largest unit cell parameter. The asymmetric unit of the unit cell contains two LevoH32+ and CoCl42− ions and two crystallization water molecules in I; two LevoH32+ and MBr42− (M = Cu, Zn) ions and two crystallization water molecules in II and III. The absolute structure of the crystals and the configuration of the chiral center of the levofloxacinium cation S are determined. The structures are stabilized by multiple hydrogen bonds, X−Y π and π-π interactions.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1911.06482
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 63. - We acknowledge the support of the Russian Science Foundation through Grant 18-12-00022.
Предметные рубрики: Materials Science
Strongly Correlated Electrons
Аннотация: We derived simple rules for the sign of superexchange interaction based on the multielectron calculations of the superexchange interaction in the transition metal oxides that are valid both below and above spin crossover under high pressure. The superexchange interaction between two cations in dn configurations is given by a sum of individual contributions related to the electron-hole virtual excitations to the different states of the dn+1 and dn−1 configurations. Using these rules, we have analyzed the sign of the superexchange interaction of a number of oxides with magnetic cations in electron configurations from d2 till d8: the iron, cobalt, chromium, nickel, copper and manganese oxides with increasing pressure. The most interesting result concerns the magnetic state of cobalt and nickel oxides CoO, Ni2O3 and also La2CoO4, LaNiO3 isostructural to well-known high-TC and colossal magnetoresistance materials. These oxides have a spin 12 at the high pressure. Change of the interaction from antiferromagnetic below spin crossover to ferromagnetic above spin crossover is predicted for oxide materials with cations in d5(FeBO3) and d7(CoO) configurations, while for materials with the other dn configurations spin crossover under high pressure does not change the sign of the superexchange interaction.
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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Sitnikov M. N., Zhivul'ko A. M.
Заглавие : Change in the magnetocapacity in the paramagnetic region in a cation-substituted manganese selenide
Коллективы : Russian Foundation for Basic Research [17-32-50080, 16-52-00045 Bel_a, 3.5743.2017/6.7]
Место публикации : Phys. Solid State. - 2018. - Vol. 60, Is. 4. - P.673-680. - ISSN 1063-7834, DOI 10.1134/S1063783418040029. - ISSN 1090-6460(eISSN)
Примечания : Cited References:19. - This work is supported by the Russian Foundation for Basic Research (project no. 17-32-50080), grant no. 16-52-00045 Bel_a, and state task no. 3.5743.2017/6.7.
Предметные рубрики: MULTIFERROICS
Аннотация: The capacity and the dielectric loss tangent of a Gd x Mn1–xSe (x ≤ 0.2) solid solution have been measured in the frequency range 1–300 kHz without a magnetic field and in a magnetic field of 8 kOe in the temperature range 100–450 K, and the magnetic moment of the solid solution has been measured in a field of 8.6 kOe. The magnetocapacity effect and the change in the magnetocapacity sign have been observed in room temperature in the paramagnetic region. A correlation of the changes in the dielectric permittivity and the magnetic susceptibility with temperature has been revealed. The magnetocapacity is described using the model with orbital electron ordering and the Maxwell–Wagner model.
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