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 Найдено в других БД:Каталог книг и брошюр библиотеки ИФ СО РАН (1)Каталог журналов библиотеки ИФ СО РАН (2)
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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Romanova O. B.
Заглавие : Dielectric and transport properties, electric polarization at the sequential structural phase transitions in iron-substituted bismuth pyrostannate
Место публикации : Ceram. Int. - 2021. - Vol. 47, Is. 2. - P.1704-1711. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.08.287
Примечания : Cited References: 33. - The reported study was funded by Russian Foundation for Basic Research project № 20-52-00005 Bel_a
Аннотация: The electrical characteristics including the electrical resistance, impedance, I–V characteristics, capacitance, dissipation factor, and thermoelectric power of the Bi2Sn2-хFeхO7 (х = 0.1, 0.2) stannates have been investigated in the temperature range of 100–600 K at frequencies of 102–106 Hz. The paramagnetic contribution of electrons to the dynamic magnetic susceptibility has been established. The conductivity mechanism of the compounds has been found from the I–V characteristics and the change in the carrier sign has been determined from the thermoelectric power. The hysteresis of the I–V curves, charge transfer currents and polarization current have been observed in the Bi2Sn1·8Fe0·2O7 compound. A nonlinear field dependence of the polarization in the orthorhombic phase has been found. The correlation between the obtained characteristics and the phase structure transitions has been established. Two relaxation channels and activation energy have been found using the Debye model. The hysteretic I–V characteristics have been explained using a model of the electronic structure and the dipole and migration polarization.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokin N. A., Kiiko V. S., Pavlov A. V., Malkin A. I.
Заглавие : BT-30 Ceramic Electrophysical Properties
Место публикации : Refract. Ind. Ceram. - 2020. - Vol. 61, Is. 3. - P.341-348. - ISSN 1083-4877 (ISSN), DOI 10.1007/s11148-020-00484-2. - ISSN 1573-9139 (eISSN)
Примечания : Cited References: 12
Аннотация: A total complex resistance (impedance) method is used to study the electrophysical characteristics of (BeO + TiO2)-ceramics modified with TiO2 micro- and nanoparticles in an amount of 30 wt.% (BT-30). Dispersion of the actual ε′ and imaginary ε′′ components of the dielectric permittivity component and specific conductivity in the frequency range from 100 Hz to 100 MHz from room temperature to the boiling point of liquid nitrogen are determined. High values of ε′ and ε′′ in the low-frequency range are typical for structurally inhomogeneous materials due to the accumulation of electric charges at the surface and within microcrystals. Two dielectric relaxation processes associated with electrical conductivity within the body and at the surface of ceramics are detected for the first time. An increase in conductivity with an increase in the microwave field frequency above 1 MHz is explained by the appearance of a current relaxation component. The activation energy of the static resistance of ceramic specimens is determined as a function of the reciprocal temperature that depends little on the weight content of TiO2 nanoparticles and varies in the range of 0.024 – 0.10 eV This also confirms the existence of two independent conduction processes, weakly dependent on the nanoparticle content in the ceramic composition. With placement of ceramic in a high-frequency electric field, spatial charges are formed, the field of which contributes to creation of additional polarization and dielectric losses.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Coondoo I., Panwar N., Krylova S. N., Krylov A. S., Alikin D., Jakka S. K., Turygin A., Shur V. Y., Kholkin A. L.
Заглавие : Temperature-dependent Raman spectroscopy, domain morphology and photoluminescence studies in lead-free BCZT ceramic
Место публикации : Ceram. Int. - 2021. - Vol. 47, Is. 2. - P.2828-2838. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.09.137
Примечания : Cited References: 65. - I.C. would like to thank financial assistance by national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology / MCTES . The authors would also like to acknowledge the Ural Center for Shared Use “Modern nanotechnology”, Ural Federal University, Russia and the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS”. The authors would like to thank Dr. E. Venkata Ramana, Department of Physics, University of Aveiro for the dielectric measurements. The work was supported by Government of the Russian Federation (Act 211, 440 Agreement 02.A03.21.0006)
Аннотация: Present work focuses on detailed temperature-dependent X-ray diffraction, Raman scattering, domain configuration, and photoluminescence (PL) studies in the (Ba0·85Ca0.15) (Zr0·10Ti0.90)O3 (BCZT) ceramics. The comprehensive Raman spectroscopy analysis in the present work not only validates the presence of the intermediate orthorhombic phase in BCZT, but also provides evidence of another transition: rhombohedral R3c phase to R3m at low temperature. Temperature behaviour of the lowest frequency transverse optical mode (soft E (TO) phonon) and hard modes was studied. Temperature dependence of peak positions, intensities, and linewidths of Raman phonon modes signalled the presence of phase transitions near −50 ± 5 °C, 0±5 °C, 35±5 °C and 110 ± 10 °C. Evolution of domain morphology occurring at phase transitions above room temperature was studied by piezoresponse force microscopy technique. Analysis of PL spectra revealed disorder/heterogeneity in the sample and indicated the existence of self-trapped excitons. PL spectra are composed of four distinct colour components (~2.55eV:blue, ~2.32eV:green, ~2.08eV:orange and ~1.78eV:red).
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grossman, Victoria G., Bazarova J. G., Molokeev M. S., Bazarov B. G.
Заглавие : Thallium ionic conductivity of new thallium indium hafnium molybdate ceramics
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [0339-2016-0007]; [18-08-00799]; [18-03-00557]
Место публикации : Ionics. - 2020. - Vol. 26. - P.6157-6165. - ISSN 0947-7047, DOI 10.1007/s11581-020-03739-7. - ISSN 1862-0760(eISSN)
Примечания : Cited References: 60. - This study was carried out within the state assignment of FASO of Russia (Theme No 0339-2016-0007) as well was supported by RFBR Grants 18-08-00799 and 18-03-00557
Предметные рубрики: POSITIVE ELECTRODE MATERIAL
CRYSTAL-STRUCTURE
TRIPLE MOLYBDATE
Аннотация: In the process of studying the system Tl2MoO4–In2(MoO4)3–Hf(MoO4)2, a new thallium indium hafnium molybdate was found. The crystal structure of the molybdate Tl5InHf(MoO4)6 was determined in the centrosymmetric space group R3¯c (a = 10.63893 (5) Å, c = 38.1447(3) Å; V = 3739.04 (4) Å3, Z = 6). The structure is a three-dimensional framework consisting of alternating (Hf,In)O6-octahedra connected by МоО4-tetrahedra. Each octahedron has common vertices with tetrahedra. The atoms arranged in this way form channels extended along with the a and b axes, in which thallium atoms are located. The conductivity behavior of Tl5InHf(MoO4)6 ceramics was studied in the temperature range from 300 to 870 K. The conductivity of the heavy cations of thallium is activated with increasing temperature.
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5.

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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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pugachev A. M., Zaytseva I. V., Surovtsev N. V., Krylov A. S.
Заглавие : Anharmonicity and local noncentrosymmetric regions in BaTiO3 pressed powder studied by the Raman line temperature dependence
Место публикации : Ceram. Int. - 2020. - Vol. 46, Is. 14. - P.22619-22623. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.06.024
Примечания : Cited References: 26. - The reported study was funded by RFBR , according to the research project No. 18-02-00399 and 19-42-543-016 , Government of Novosibirsk region No. 19-42-543-016 and State assignment No AAAA-A17-117052410033-9. The experiments were performed in the multiple-access center “High-Resolution Spectroscopy of Gases and Condensed Matter” in IA&E SB RAS (Novosibirsk, Russia) and Center for Common Use of the Krasnoyarsk Scientific Center, SB RAS (Krasnoyarsk, Russia)
Аннотация: The temperature dependencies of position, width, and integral amplitude the E(TO) line near 307 cm−1 in Raman spectra in barium titanate powders with different non-hydrostatic pressure and temperature treatment were studied. It was found that parameters of the E(TO) line near 307 cm−1 are different in the crystal, the untreated powder, the powder treated by the non-hydrostatic pressure, and the powder annealed after the pressure treatment. The line width (FWHM) increase with temperature according to Klemens model. It indicates that the origin of the line broadening is the anharmonicity of the E(TO) phonons. The pressure treatment changes the anharmonicity of the phonon potential. It was found that the temperature dependence of the integral intensity of the E(TO) line is similar to that of the second optical harmonic signal and reflects the presence of the local polar regions. Thus, the E(TO) line in the Raman spectrum allows one to characterize the average polarity of local regions and their anharmonicity depending on non-hydrostatic pressures and thermal treatment.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Bogdanov E. V., Bondarev V. S., Gorev M. V., Rysiakiewicz-Pasek E.
Заглавие : Size effect on sensitivity to external pressure and caloric effects in TGS: Ceramics and nanocomposites
Место публикации : Mater. Today Commun. - 2020. - Vol. 25. - Ст.101463. - ISSN 23524928 (ISSN), DOI 10.1016/j.mtcomm.2020.101463
Примечания : Cited References: 39
Аннотация: Experimental study of temperature-pressure phase diagrams revealed a slight difference in the sensitivity to hydrostatic pressure of triglycine sulfate (TGS) as a bulk (single crystal, ceramics), and nanoparticles embedded in porous glass (TGS + PG). An analysis of the pressure sensitivity, dT0/p and dT0/dσ, and entropies of the P21 ↔ P21/m phase transition showed the closeness of the barocaloric parameters in various materials under study. Due to the strong anisotropy of thermal expansion, the piezocaloric effect under pressure along the axis c exceeds the barocaloric effect in single-crystal TGS. The reasons for the strong reduction in the electrocaloric effect in the ferroelectric component of nanocomposites compared with a single-crystal are discussed.
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8.

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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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Coondoo I., Krylov A. S., Sharma D. K., Krylova S. N., Alikin D., Kumar J. S., Mirzorakhimov A., Melnikova N., Soares M. J., Kholkin A. L.
Заглавие : Temperature dependent structural, dielectric, Raman, piezoresponse and photoluminescence investigations in sol-gel derived BCZT ceramics
Место публикации : Mater. Chem. Phys. - 2022. - Vol. 277. - Ст.125526. - ISSN 02540584 (ISSN), DOI 10.1016/j.matchemphys.2021.125526
Примечания : Cited References: 82. - I.C. and J.S.K would like to acknowledge financial assistance by national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MCTES. This work was partially developed within the scope of the project i3N, UIDB/50025/2020 & UIDP/50025/2020, financed by national funds through the FCT/MEC. Part of this work (A.K.) was supported by the Ministry of Science and Higher Education of the Russian Federation (grant no. 075-15-2021-588). This research used resources of the Ural Center for Shared Use “Modern nanotechnology”, Ural federal University, Russia and the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS”. The authors thank Dr. Gonzalo Irurueta, Center for Mechanical Engineering and Automation, University of Aveiro, Portugal and Dr. E. Venkata Ramana, Department of Physics, University of Aveiro, Portugal
Аннотация: 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 [50BZT-50BCT or BCZT] based compounds have been the focus of a lot of research, particularly motivated by their high piezoelectric effect. However, the literature lacks an elaborate investigation of the phase transition behavior in BCZT ceramics obtained by wet chemistry processing. Here, we present an in-depth study on the temperature dependence of x-ray diffraction (XRD), Raman scattering, dielectric properties, local piezoresponse and photoluminescence (PL) to investigate the sequence of phase transitions in the BCZT ceramic synthesized via a chemical route. Phase formation was determined by Rietveld analysis of XRD data, while compositional homogeneity and elemental quantification of the compound was validated using energy dispersive x-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS) studies. Detailed fitting of XPS data indicated the existence of Ti3+ species (∼6%) in the prepared BCZT. Phase transitions were examined by analyzing the modifications in the XRD profile of Bragg reflection {200} and anomalies observed in the temperature variation of dielectric and Raman spectra studied over a wide temperature range starting from 10K to beyond Curie temperature. Crystallographic transformation temperatures obtained from dielectric measurement agreed well with those assessed from the temperature evolution of Raman spectra. In addition to other transitions, Raman scattering results revealed the existence of a transition from to phase near −175 °C, a transition that has not been interpreted in BCZT (and generally not observed in parent BaTiO3 compound). The luminescence response was studied by photoluminescence (PL) spectroscopy in the temperature range 15–300 K. The position of the PL peak was observed to shift with temperature and discontinuities in the wavelength shift were noted near phase transitions. Evolution of domain morphology with temperature was examined by piezoresponse force microscopy technique. Consolidated results assign the phase sequence in sol-gel derived BCZT as: R(R3c)→-175±10°CR(R3m)→-50±10°CO→40±10°CT→120±10°CC.
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10.

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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