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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Zhigalov V. S., Matsynin A. A., Bykova L. E., Mikhlin Y. L., Bondarenko G. N., Patrin G. S., Yurkin G. Yu.
Заглавие : Formation of ferromagnetic germanides by solid-state reactions in 20Ge/80Mn films
Место публикации : Thin Solid Films: Elsevier Science, 2014. - Vol. 552. - P.86-91. - ISSN 0040-6090, DOI 10.1016/j.tsf.2013.12.029
Примечания : Cited References: 53
Предметные рубрики: PHASE-FORMATION
MAGNETIC-PROPERTIES
Mn5Ge3 FILMS
X-RAY
Ge(111)
TRANSFORMATIONS
DIFFUSION
SPECTRA
SYSTEM
LAYERS
Ключевые слова (''Своб.индексиров.''): manganite-germanium--solid state reaction--first phase--mn5ge3 alloy--carbon impurity--oxygen impurity--annealing--magnetic anisotropy
Аннотация: Solid state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy, and magnetic and electrical measurements. The films have a nominal atomic ratio Ge:Mn = 20:80 and are investigated at temperatures from 50 to 500 °C. It is established that after annealing at ~ 120°C, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 20Ge/80Mn interface. As the annealing temperature increases to 300°C, the weak magnetic Mn5Ge 2 + Mn3Ge phases simultaneously begin to grow and they become dominant at 400°C. Increasing the annealing temperature to 500°C leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 350-360 K and magnetization 14-25 kA/m at room temperature. The X-ray diffraction study of the samples shows the reflections from the Mn 5Ge3 phase, and the photoelectron spectra contain the oxygen and carbon peaks. The homogeneous distribution of oxygen and carbon over the sample thickness suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn 5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3CxOy. The initiation temperature (~ 120 C) is the same in the Mn5Ge3 phase with the solid-state reactions in the Ge/Mn films as well as in the phase separation in the GexMn1 - x diluted semiconductors. Thus, we conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn 1 - x diluted semiconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Vishnyakova E. A., Romanchenko A. S., Saikova S. V., Likhatski M. N., Larichev Y. V., Tuzikov F. V., Zaikovskii V. I., Zharkov S. M.
Заглавие : Oxidation of Ag nanoparticles in aqueous media: Effect of particle size and capping
Место публикации : Appl. Surf. Sci.: Elsevier Science, 2014. - Vol. 297. - P.75-83. - ISSN 0169-4332, DOI 10.1016/j.apsusc.2014.01.081. - ISSN 1873-5584
Примечания : Cited References: 58. - This work was partially financially supported by the Ministry of Education and Science of RF (Grant 8580) and RFBR (12-03-31178).
Предметные рубрики: EX-SITU XPS
POLYCRYSTALLINE SILVER ELECTRODES
RAY PHOTOELECTRON-SPECTROSCOPY
METAL NANOPARTICLES
ELECTROCHEMICAL OXIDATION
ABSORPTION SPECTROSCOPY
PYROLYTIC-GRAPHITE
OXYGEN-ADSORPTION
TRANSFORMATIONS
DISSOLUTION
Ключевые слова (''Своб.индексиров.''): silver nanoparticles--oxidation--resistive switching effect--x-ray photoelectron spectroscopy
Аннотация: Many applications and environmental impact of silver-bearing nanomaterials critically depend upon their specific reactivity, which is still poorly understood. Here, silver nanoparticles (Ag NPs) of about 3-5 nm and 10-12 nm in diameter, uncapped and capped with l-glucose or citrate, were prepared, characterized using UV-vis absorption spectroscopy, SAXS, TEM, and their (electro) chemical oxidation was examined in comparison with each other and bulk metal applying scanning tunneling microscopy and spectroscopy, cyclic voltammetry, and XPS. A resistive switching effect was found in the tunneling spectra measured in air at the smaller uncapped Ag NPs deposited on HOPG and was interpreted in terms of Ag transfer between the particle and the probe. The anodic oxidation of these Ag NPs in 1 M NaOH yielded 3D Ag2O, while only a layer of "primary"Ag(I) oxide emerged on larger uncapped nanoparticles during the potential sweep. The formation of AgO at higher potentials proceeded readily at the "primary"oxide but was retarded at the smaller NPs. The citrate- and glucose-capping substantially impeded the formation both of Ag2O and AgO. The findings highlighted, particularly, a non-trivial effect of particle size and transient mobilization of Ag species on the reactions of silver nanoparticles. (c) 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S. N., Solovyov L. A., Rabchevskii E. V., Dudnikov V. A., Ovchinnikov S. G., Anshits A. G.
Заглавие : Methane oxidation over A-site ordered and disordered Sr0.8Gd0.2CoO3−δ perovskites
Коллективы : SB RAS project [38]; RFBR [13-02-00358]
Место публикации : Chem. Commun.: Royal Society of Chemistry, 2014. - Vol. 50, Is. 46. - P.6112-6115. - ISSN 1359-7345, DOI 10.1039/c4cc00913d. - ISSN 1364-548X
Примечания : Cited References: 20. - The authors acknowledge the financial support from SB RAS project N 38 (2012) and RFBR grant 13-02-00358.
Предметные рубрики: MEMBRANE REACTORS
OXYGEN
OXIDES
PERFORMANCE
COMBUSTION
FEATURES
PHASES
Аннотация: A tetragonal phase Sr0.8Gd0.2CoO3−δ with ordered Gd3+/Sr2+ ions and oxygen vacancy sites is found to be about five times less active in the reaction of methane combustion than a quenched cubic perovskite phase with randomly distributed (disordered) Gd3+/Sr2+ ions over the A-sites of the crystal lattice.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Gavrilova T. A., Kesler V. G., Molokeev M. S., Aleksandrov K. S.
Заглавие : Low-temperature synthesis and structural properties of ferroelectric K 3WO3F3 elpasolite
Место публикации : Chem. Phys. Lett. - 2010. - Vol. 493, Is. 1-3. - P.83-86. - ISSN 0009-2614, DOI 10.1016/j.cplett.2010.05.023
Примечания : Cited References: 37
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
CORE-LEVEL SPECTROSCOPY
PHASE-TRANSITIONS
SOLID-STATE
ELECTRON-DIFFRACTION
DIFFUSE-SCATTERING
RHEED ANALYSIS
POLAR
BEHAVIOR
(NH4)(3)TIOF5
Ключевые слова (''Своб.индексиров.''): chemical synthesis--elpasolite--ferroelectric phase transition--fluorine atoms--low temperature synthesis--low temperatures--oxyfluorides--partial ordering--room temperature--sem--space groups--structure parameter--xrd--chemical properties--ferroelectric materials--ferroelectricity--fluorine--oxygen--phase transitions--rietveld method--single crystals--synthesis (chemical)--x ray photoelectron spectroscopy--x ray powder diffraction--scanning electron microscopy
Аннотация: Low-temperature ferroelectric G2 polymorph of K3WO 3F3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO3F3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3), b = 8.6808(5), c = 6.1581(3), ? = 135.124(3), V = 329.46(3) 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A2BMO3F3 oxyfluorides is discussed. В© 2010 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Aleksandrov K. S., Aplesnin S. S., Roessli B., Semadeni F., Amato A., Baines C., Bartolome J., Evangelisti M.
Заглавие : Spin-glass state in CuGa2O4
Место публикации : Phys. Rev. B. - 2001. - Vol. 63, Is. 18. - Ст.184425. - ISSN 0163-1829, DOI 10.1103/PhysRevB.63.184425
Примечания : Cited References: 28
Предметные рубрики: TRANSITION
Ключевые слова (''Своб.индексиров.''): copper--gallium--glass--oxygen--acceleration--article--magnetism--measurement--molecular dynamics--phase transition
Аннотация: Magnetic susceptibility, magnetization, specific-heat, and positive muon spin relaxation (?SR) measurements have been used to characterize the magnetic ground state of the spinel compound CuGa2O4. We observe a spin-glass transition of the S = 1/2 Cu2+ spins below Tf = 2.5 K characterized by a cusp in the susceptibility curve which is suppressed when a magnetic field is applied. We show that the magnetization of CuGa2O4 depends on the magnetic history of the sample. Well below Tf, the muon signal resembles the dynamical Kubo-Toyabe expression reflecting that the spin freezing process in CuGa2O4 results in a Gaussian distribution of the magnetic moments. By means of Monte Carlo simulations, we obtain the relevant exchange integrals between the Cu2+ spins in this compound.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bataleva, Yu. V., Palyanov, Yu. N., Sokol A. G., Borzdov, Yu. M., Bayukov O. A.
Заглавие : The role of rocks saturated with metallic iron in the formation of ferric carbonate-silicate melts: experimental modeling under PT-conditions of lithospheric mantle
Коллективы : Siberian Branch of the Russian Academy of Sciences [31], Russian Foundation for Basic Research [12-05-00740]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2015. - Vol. 56, Is. 1-2. - P.143-154. - ISSN 1068, DOI 10.1016/j.rgg.2015.01.008. - ISSN 1878030X(eISSN)
Примечания : Cited References:68. - This work was supported by Integration project 31 from the Siberian Branch of the Russian Academy of Sciences and by grant 12-05-00740 from the Russian Foundation for Basic Research.
Предметные рубрики: OXYGEN FUGACITY
DIAMOND FORMATION
OXIDATION-STATE
EARTHS MANTLE
Ключевые слова (''Своб.индексиров.''): carbonate-silicate melt--graphite--co2 fluid--iron carbide--garnet--redox gradient--high-pressure experiment
Аннотация: Experimental modeling of the processes of formation of ferric carbonate-silicate melts through the carbonate-oxide-metal interaction is performed in the (Mg,Ca)CO3-SiO2-Al2O3-Fe0 system at 6.3 and 7.5 GPa and within 1150-1650 °C, using a multianvil high-pressure apparatus of “split-sphere” type (BARS). Two parallel reactions run in the subsolidus region (1150-1450 °C): decarbonation, producing pyrope-almandine (Fe# = 0.40-0.75) and CO2 fluid, and redox interaction between carbonate and Fe0, resulting in the crystallization of iron carbide in assemblage with magnesiowustite (Fe# = 0.75-0.85). It is shown that the reduction of carbonate or CO2 fluid by iron carbide and parallel redox interaction of magnesiowustite with CO2 produce graphite in assemblage with Fe3 + -containing magnesiowustite. In the temperature range of 1450-1650 °C, generation of carbonate-silicate melts coexisting with pyrope-almandine, magnesiowustite, magnetite, ferrospinel, and graphite takes place. The composition of the produced melts is as follows: SiO2 - 10-15 wt.%, X(FeO + Fe2O3) = 36-43 wt.%, and Fe3+/XFe - 0.18-0.23. These Fe3 + -enriched carbonate-silicate melts/fluids are saturated with carbon and are the medium of graphite crystallization. Oxide and silicate phases (almandine, ferrospinel, and magnetite) coexisting with graphite are also characterized by high Fe3+/XFe values. It has been established that Fe3 + -enriched carbonate-silicate melts can result from the interaction of Fe0-containing rocks with carbonated rocks. In the reduced mantle (with the presence of iron carbides or oxides), melts of this composition can be the source of carbon and the medium of graphite crystallization at once. After separation and ascent, these ferric carbonate-silicate melts can favor oxidizing metasomatism in the lithospheric mantle.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Mikhaleva E. A., Gorev M. V., Kartashev A. V.
Заглавие : Caloric and multicaloric effects in oxygen ferroics and multiferroics
Коллективы : Всероссийская конференция по физике сегнетоэлектриков
Место публикации : Phys. Solid State/ Всероссийская конференция по физике сегнетоэлектриков (20 ; 2014 ; 18-22 авг. ; Красноярск): MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 57, Is. 3. - P.429-441. - ISSN 1063, DOI 10.1134/S1063783415030075. - ISSN 10906460(eISSN)
Примечания : Cited References:53. - This study was supported by the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools of the Russian Federation (grant no. NSh-924.2014.2).
Предметные рубрики: PHASE-TRANSITIONS
MAGNETOCALORIC MATERIALS
ELECTROCALORIC MATERIALS
REFRIGERATION
CERAMICS
OXYFLUORIDES
Аннотация: The main problems of the current state-of-the-art research into the caloric effects observed in oxygen ferroics, multiferroics, and composites, as well as the influence of different factors (anisotropy, dimensional parameters, direct and indirect interferroic interactions) on these effects, have been considered. Possible ways to increase the caloric efficiency of materials have been analyzed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S. N., Solov'ev L. A., Rabchevskii E. V., Dudnikov V. A., Ovchinnikov S. G., Anshits A. G.
Заглавие : New method for regulating the activity of ABO3 perovskite catalysts
Коллективы : Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools [NSh-2886.2014.2]
Место публикации : Kinet. Catal.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 56, Is. 5. - P.640-645. - ISSN 0023, DOI 10.1134/S0023158415040199. - ISSN 16083210(eISSN)
Примечания : Cited References:23. - This work was supported in part by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (grant no. NSh-2886.2014.2).
Предметные рубрики: MEMBRANE REACTORS
METHANE COMBUSTION
OXIDATION
OXIDES
OXYGEN
PERFORMANCE
FEATURES
PHASES
CO
Ключевые слова (''Своб.индексиров.''): perovskite--cobalt--methane--deep oxidation--oxidative condensation
Аннотация: A new possibility of changing the activity and selectivity of perovskite catalysts in the oxidative conversion of methane was demonstrated using the Sr x Gd1–x CoO3–δ (0.5 x 0.9) compounds as an example. It was established that, at the same chemical composition, the disordering of Sr2+/Gd3+ ions over the A positions of the crystal structure led to a significant increase in activity in the deep oxidation reaction of CH4, as compared with the samples with an ordered distribution of cations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ma L., Xia Z., Atuchin V. V., Molokeev M. S., Auluck S., Reshak A. H., Liu Q.
Заглавие : Engineering oxygen vacancies towards self-activated BaLuAlxZn4-xO7-(1-x)/2 photoluminescent materials: An experimental and theoretical analysis
Место публикации : Phys. Chem. Chem. Phys.: Royal Society of Chemistry, 2015. - Vol. 17, Is. 46. - P.31188-31194. - ISSN 14639076 (ISSN), DOI 10.1039/c5cp05130d
Примечания : Cited References: 28. - The present work was supported by the National Natural Science Foundations of China (Grant No. 51572023, 51272242 and 51511130035), and Fundamental Research Funds for the Central Universities (FRF-TP-15-005A1). The author A. H. Reshak would like to acknowledge the CENTEM project, reg. no. CZ.1.05/2.1.00/03.0088, cofunded by the ERDF as part of the Ministry of Education, Youth and Sports OP RDI programme and, in the follow-up sustainability stage, supported through CENTEM PLUS (LO1402) by financial means from the Ministry of Education, Youth and Sports under the National Sustainability Programme I. Computational resources were provided by MetaCentrum (LM2010005) and CERIT-SC (CZ.1.05/3.2.00/08.0144) infrastructures. SA would like to thank CSIR-NPL and Physics Department IIT Delhi for financial support. This work was partly supported by the Russian Foundation for Basic Research (Grant No. 15-52-53080 GFEN_a). VVA was partly supported by the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: PHOSPHOR
LUMINESCENCE
EVOLUTION
OXIDES
IONS
Аннотация: Novel self-activated yellow-emitting BaLuAlxZn4-xO7-(1-x)/2 photoluminescent materials were investigated by a combined experimental and theoretical analysis. The effects of Al/Zn composition modulation, calcination atmosphere and temperature on the crystal structure and photoluminescence properties have been studied via engineering oxygen vacancies. Accordingly, BaLuAl0.91Zn3.09O7 prepared in an air atmosphere was found to be the stable crystalline phase with optimal oxygen content and gave a broad yellow emission band with a maximum at 528 nm. The self-activated luminescence mechanism is ascribed to the O-vacancies based on the density functional theory (DFT) calculation. A theoretical model originating from the designed oxygen vacancies has been proposed in order to determine the influence of O-vacancies on the band structure and self-activated luminescence. Therefore, the appearance of a new local energy level in the band gap will cause the wide-band optical transitions in the studied BaLuAlxZn4-xO7-(1-x)/2 materials.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bataleva Yu. V., Palyanov Y .N., Sokol A. G., Borzdov Y. M., Bayukov O. A.
Заглавие : Wüstite stability in the presence of a CO2-fluid and a carbonate-silicate melt: Implications for the graphite/diamond formation and generation of Fe-rich mantle metasomatic agents
Место публикации : Lithos: Elsevier, 2016. - Vol. 244. - P.20-29. - ISSN 00244937 (ISSN), DOI 10.1016/j.lithos.2015.12.001
Примечания : Cited References: 68. - This work was supported by the Russian Science Foundation under grant no. 14-27-00054. The authors thank A. Moskalev for his assistance in the work preparation, A. Khokhryakov for useful suggestions throughout the study, and S. Ovchinnikov for his assistance in implementation of Mössbauer spectroscopy measurements. The authors thank editor M. Scambelluri, and two anonymous reviewers for their useful comments, which helped to profoundly improve the manuscript.
Предметные рубрики: EARTHS LOWER MANTLE
FERRIC IRON CONTENT
DIAMOND FORMATION
MINERAL INCLUSIONS
NATURAL DIAMOND
OXIDATION-STATE
DEEP MANTLECRUST
LITHOSPHERIC MANTLE
OXYGEN FUGACITY
OCEANIC-CRUST
Ключевые слова (''Своб.индексиров.''): wustite--co2-fluid--carbonate-silicate melt--decarbonation--graphite formation--hpht experiment
Аннотация: Experimental simulation of the interaction of wüstite with a CO2-rich fluid and a carbonate-silicate melt was performed using a multianvil high-pressure split-sphere apparatus in the FeO-MgO-CaO-SiO2-Al2O3-CO2 system at a pressure of 6.3GPa and temperatures in the range of 1150°C-1650°C and with run time of 20h. At relatively low temperatures, decarbonation reactions occur in the system to form iron-rich garnet (Alm75Prp17Grs8), magnesiowüstite (Mg#≤0.13), and CO2-rich fluid. Under these conditions, magnesiowüstite was found to be capable of partial reducing CO2 to C0 that leads to the formation of Fe3+-bearing magnesiowüstite, crystallization of magnetite and metastable graphite, and initial growth of diamond seeds. At T≥1450°C, an iron-rich carbonate-silicate melt (FeO~56wt.%, SiO2~12wt.%) forms in the system. Interaction between (Fe,Mg)O, SiO2, fluid and melt leads to oxidation of magnesiowüstite and crystallization of fayalite-magnetite spinel solid solution (1450°C) as well as to complete dissolution of magnesiowüstite in the carbonate-silicate melt (1550°C-1650°C). In the presence of both carbonate-silicate melt and CO2-rich fluid, dissolution (oxidation) of diamond and metastable graphite was found to occur. The study results demonstrate that under pressures of the lithospheric mantle in the presence of a CO2-rich fluid, wüstite/magnesiowüstite is stable only at relatively low temperatures when it is in the absolute excess relative to CO2-rich fluid. In this case, the redox reactions, which produce metastable graphite and diamond with concomitant partial oxidation of wüstite to magnetite, occur. Wüstite is unstable under high concentrations of a CO2-rich fluid as well as in the presence of a carbonate-silicate melt: it is either completely oxidized or dissolves in the melt or fluid phase, leading to the formation of Fe2+- and Fe3+-enriched carbonate-silicate melts, which are potential metasomatic agents in the lithospheric mantle. © 2015 Elsevier B.V.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ji H., Wang L., Molokeev M. S., Hirosaki N., Huang Z., Xia Z., Ten Kate O. M., Liu L., Xie R.
Заглавие : New garnet structure phosphors, Lu3-xYxMgAl3SiO12:Ce3+ (x = 0-3), developed by solid solution design
Место публикации : J. Mater. Chem. C: Royal Society of Chemistry, 2016. - Vol. 4, Is. 12. - P.2359-2366. - ISSN 20507534 (ISSN), DOI 10.1039/c6tc00089d
Примечания : Cited References: 33. - This work was partly supported by the National Natural Science Foundation of China (Grant No. 51511130035, 51272259, 61575182, 51572232 and 51561135015) and the Russian Foundation for Basic Research (Grant No. 15-52-53080). H. J. thanks the China Scholarship Council (CSC) for providing a scholarship to support his study in NIMS.
Предметные рубрики: Particle-diagnosis approach
Luminescence
Photoluminescence
Ce3+
Substitution
Discovery
Oxygen
Аннотация: New garnet phosphors, Lu3−xYxMgAl3SiO12:Ce3+ (x = 0–3), which can be efficiently excited by blue light and emit the yellow-orange light, were developed using the solid solution design strategy combining the chemical unit substitution and the cation substitution. Crystal structures of the four compounds were reported for the first time via the Rietveld refinement of their powder XRD patterns. All phosphors show the general cubic garnet structure with the space group Iad. The specific occupancy of Lu/Y, Al/Mg, Al/Si and O atoms in different positions was identified. The evolution of cell parameters and Y/Lu/Ce–O bond lengths were identified. Photoluminescence properties were evaluated on aspects of emission/excitation spectra, internal/external quantum efficiency and thermal emission stability. Under the 450 nm blue light excitation, the phosphors exhibit bright yellow color emission, peaking in the 575–597 nm spectral range. The internal and external quantum efficiency can reach 83% and 58%, respectively. The emission red-shift in response to the Y/Lu ratio variation was discussed in relation to the local structure evolution. The phosphors are relatively promising to act as wavelength converter of blue light in white light emitting diodes.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Uschakov A. V., Karpov I. V., Lepeshev A. A., Zharkov S. M.
Заглавие : The influence of oxygen concentration on the formation of CuO and Cu2O crystalline phases during the synthesis in the plasma of low pressure arc discharge
Место публикации : Vacuum: Elsevier, 2016. - Vol. 128. - P.123-127. - ISSN 0042207X (ISSN), DOI 10.1016/j.vacuum.2016.03.025
Примечания : Cited References: 19. - This study was supported by the Russian Foundation for Basic Research. (Project No 15-08-02132).
Предметные рубрики: Nanoparticles
Oxide
Ключевые слова (''Своб.индексиров.''): oxides--vapor deposition--x-ray diffraction--transmission electron microscopy (tem)--catalytic properties
Аннотация: This paper describes the synthesis of copper oxide nanoparticles with different percentages of CuO and Cu2O phases. It was achieved by the control of the percentage of oxygen in the gas mixture (N2 + O2) in a plasma-chemical process of evaporation-condensation by means of low-pressure arc discharge. In all the experiments, the pressure in the plasma-chemical reactor remained constant at 60 Pa. By means of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) it was found that the average particle size was 6 nm, and Cu2O phase content decreases with increasing oxygen content in the gas mixture. High photocatalytic properties of Cu2O powder were shown by the example of the reaction of the methyl orange dye decomposition in water solution. The problems, associated with the performance of this method and the formation of crystalline phases, are discussed.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Barabanov A. F.
Заглавие : Stability of the superconducting dx2-y2 phase in high-Tc superconductors with respect to the intersite coulomb repulsion of holes at oxygen
Коллективы : Russian Foundation for Basic Research [16-02-00073, 16-02-00304]; Dynasty Foundation; Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools [SP-1361.2015.1]
Место публикации : JETP Letters. - 2016. - Vol. 103, Is. 6. - P.385-389. - ISSN 0021-3640, DOI 10.1134/S0021364016060114. - ISSN 1090-6487(eISSN)
Примечания : Cited References:28. - This work was supported by the Russian Foundation for Basic Research, project nos. 16-02-00073 and 16-02-00304. The work of D.D.M. and M.M.K. was supported by the Dynasty Foundation and the work of M.M.K. was also supported by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. SP-1361.2015.1).
Предметные рубрики: Hubbard-model
Spin polaron
Density
Аннотация: It has been shown that, because of the two-orbital character of the subsystem of holes located at oxygen sites and the spatial separation of this subsystem from that of spins at copper ions, the superconducting phase in high-Tc superconductors is stable with respect to the strong Coulomb repulsion of holes located at nearestneighbor oxygen sites if the order parameter has the dx2−y2 symmetry. This effect is due to the symmetry characteristics of the Coulomb potential, owing to which the equation determining the Cooper pairing in the dx2−y2 channel does not include this potential.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wang X., Li J. -G., Molokeev M. S., Zhu Q., Li X., Sun X.
Заглавие : Layered hydroxyl sulfate: Controlled crystallization, structure analysis, and green derivation of multi-color luminescent (La,RE)2O2SO4 and (La,RE)2O2S phosphors (RE = Pr, Sm, Eu, Tb, and Dy)
Место публикации : Chem. Eng. J.: Elsevier, 2016. - Vol. 302. - P.577-586. - ISSN 13858947 (ISSN), DOI 10.1016/j.cej.2016.05.089
Примечания : Cited References: 50. - This work is supported in part by the National Natural Science Foundation of China (Grants Nos. 51172038, 51302032, and U1302272), the Fundamental Research Fund for the Central Universities (Grant No. N140204002), Grants-in-Aid for Scientific Research (KAKENHI No. 26420686), and the Russian Foundation for Basic Research (15-52-53080). X.J. Wang acknowledges financial support from the China Scholarship Council for her overseas Ph.D. study (Contract No. 201406080035) and the assistance of Q. Q. Zhu (University of Science and Technology of China) for his help with calcination.
Предметные рубрики: PHOTOLUMINESCENCE PROPERTIES
OXYSULFATE/OXYSULFIDE SYSTEMS
CRYSTAL-STRUCTURE
OXYGEN-STORAGE
Ln
NANOCOMPOSITES
EMISSION
CAPACITY
FAMILY
FABRICATION
Ключевые слова (''Своб.индексиров.''): sulfate type layered rare earth hydroxide--luminescence--oxysulfate--oxysulfide
Аннотация: The two important groups of Ln2O2SO4 and Ln2O2S compounds are traditionally synthesized with the involvements of environmentally harmful sulfur-containing reagents. We developed in this work a unique green approach for their synthesis, using Ln2(OH)4SO4·2H2O layered hydroxyl sulfate as the precursor (Ln-241 phase). Phase selective crystallization of La-241 under both atmospheric pressure and hydrothermal conditions was firstly optimized, followed by transformation into La2O2S and La2O2SO4 by controlled calcination. Rietveld structure refinement was performed for La-241, La(OH)SO4, La2O2SO4, and La2O2S, and the crystal structure and cell parameters of La-241 were originally reported. The photoluminescence performances of several important activators (Pr3+, Sm3+, Eu3+, Tb3+, and Dy3+) in the two hosts, in terms of excitation, emission, quantum yield, and color coordinates of emission, were thoroughly investigated, and multi-color luminescence including bright red, green, orange red, and yellow was obtained under ultraviolet excitation. Detailed investigations of Tb3+ photoluminescence revealed that the lack of 5D3 emission in La2O2S and the gradual quenching of 5D3 blue emission at a higher Tb3+ content (hence decreasing I488/I545 ratio and changing color coordinates) in La2O2SO4 were suggested to be due to thermal activation of the 5D3 electrons into the conduction band and cross relaxation between adjacent Tb3+, respectively. The synthesis approach developed in this work for La2O2SO4 and La2O2S, with water vapor as the only exhaust gas, is environmentally benign and holds great potential in the facile synthesis of analogous compounds of other lanthanides. © 2016 Elsevier B.V.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Orlov Yu. S., Gavrilkin S. Yu., Gorev M. V., Vereshchagin S. N., Solovyov L. A., Perov N. S., Ovchinnikov S. G.
Заглавие : Effect of Gd and Sr ordering in a sites of doped Gd0.2Sr0.8CoO3-δ perovskite on its structural, magnetic, and thermodynamic properties
Место публикации : J. Phys. Chem. C: American Chemical Society, 2016. - Vol. 120, Is. 25. - P,13443-13449. - ISSN 19327447 (ISSN), DOI 10.1021/acs.jpcc.6b04810
Примечания : Cited References: 45. - The authors are thankful to the Russian Science Foundation (Project No. 16-13-00060) for financial support. The magnetic measurements were carried out in the Shared Facility Centre of P. N. Lebedev Physical Institute of RAS.
Предметные рубрики: Ln1-xSrxCoO(3-δ) Ln
PROFILE REFINEMENT
CRYSTAL-STRUCTURE
OXYGEN-CONTENT
COBALTITES
OXIDE
La1-xSrxCoO3-δ
Dy3+
SPIN
Ho3+
Аннотация: Magnetic and thermodynamic properties of perovskite Gd0.2Sr0.8CoO3−δ, with ordered and disordered states of Gd and Sr in the A-sites of the crystal lattice have been studied revealing remarkable differences in the physical properties of the ordered and disordered states. The ordered samples have larger oxygen nonstoichiometry, heat capacity, and thermal expansion anomalies, and abnormal temperature dependence of the magnetization around 350 K.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bogdanov E. V., Vasil'ev A. D., Flerov I. N., Laptash N. M.
Заглавие : Effect of cation substitution in fluorine-oxygen molybdates (NH4)(2-x) A (x) MoO2F4
Разночтения заглавия :авие SCOPUS: Effect of cation substitution in fluorine-oxygen molybdates (NH4)2 - xAxMoO2F4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 2. - P303-308. - ISSN 1063-7834, DOI 10.1134/S1063783411020065
Примечания : Cited References: 11. - This study was supported by the Russian Foundation for Basic Research (project no. 09-02-00062) and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools of the Russian Federation (project no. NSh-1011.2008.2).
Предметные рубрики: PHASE-TRANSITIONS
CRYSTALS
(NH4)(2)WO2F4
DIFFRACTION
OXYFLUORIDE
MECHANISM
DISORDER
Аннотация: Thermophysical and structural studies of (NH4)(2 - x) A (x) MoO2F4 (A = Cs, Rb, K) solid solutions of oxyfluorides have been performed. The character of the influence of cation substitutions on the stability of the initial phase (space group Cmcm) and on the mechanism of phase transitions has been elucidated.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Maksimov E. G., Sofronova S. N.
Заглавие : Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb1/2O3 solid solutions
Разночтения заглавия :авие SCOPUS: Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb 1/2O3 solid solutions
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 105, Is. 3. - P617-625. - ISSN 1063-7761, DOI 10.1134/S1063776107090191
Примечания : Cited References: 23
Предметные рубрики: RELAXOR FERROELECTRICS
PHASE-TRANSITION
LOCAL-STRUCTURE
PB(SC1/2NB1/2)O-3
PEROVSKITE
CRYSTALS
Ключевые слова (''Своб.индексиров.''): dipole moment--lattice vibrations--negative ions--phonons--positive ions--solid solutions--dynamic born charges--ferroelectric instabilities--frequency spectra--gordon-kim models--oxygen anions--phonon spectra--ferroelectricity
Аннотация: The dynamic Born charges and the frequency spectra of lattice oscillations in the crystals of ordered and disordered PbSc1/2Ta1/2O3 (PST) and PbSc1/2Nb1/2O3 (PSN) solid solutions have been calculated within the framework of the generalized Gordon-Kim model with allowance for the dipole and quadrupole polarizabilities. The phonon spectra of both compounds contain ferroelectric soft modes. The influence of various interactions on the magnitude of dynamic charges and ferroelectric instability in PSN and PST solid solutions has been studied and it is shown that both these charges and the ferroelectric instability are determined by the competition between long-range dipole-dipole interactions and short-range dipole-charge interactions, the determining role played by the interaction of Nb (Ta) cations and oxygen anions in the Nb-O (Ta-O) bond direction.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Pchelkina Z. V., Anisimov V. I.
Заглавие : Hybrid LDA and generalized tight-binding method for electronic structure calculations of strongly correlated electron systems
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2005. - Vol. 72, Is. 16. - Ст.165104. - ISSN 1098-0121, DOI 10.1103/PhysRevB.72.165104
Примечания : Cited References: 82
Предметные рубрики: T-J MODEL
DENSITY-FUNCTIONAL CALCULATION
NARROW ENERGY BANDS
MEAN-FIELD THEORY
COULOMB INTERACTIONS
FERMION SYSTEMS
COPPER OXIDES
SUPERCONDUCTORS
LA2-XSRXCUO4
OXYGEN
Аннотация: A hybrid scheme for the electronic structure calculations of strongly correlated electron systems is proposed. The ab initio local density approximation calculation is used to construct the Wannier functions and obtain single electron and Coulomb parameters of the multiband Hubbard-type model. In strong correlation regime the electronic structure within multiband Hubbard model is calculated by the generalized tight-binding method, which combines the exact diagonalization of the model Hamiltonian for a small cluster (unit cell) with perturbation treatment of the intercluster hopping and interactions. For undoped La2CuO4 and Nd2CuO4 this scheme results in charge transfer insulators with correct values of gaps and dispersions of bands in agreement with the angle-resolved photoemission data.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Janowitz C., Seidel U., Unger RST, Krapf A., Manzke R., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta
Разночтения заглавия :авие SCOPUS: Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xY xCu2O8+δ
Место публикации : JETP Letters. - 2004. - Vol. 80, Is. 11. - P.692-696. - ISSN 0021-3640, DOI 10.1134/1.1862796
Примечания : Cited References: 18
Предметные рубрики: ELECTRONIC-STRUCTURE
APICAL OXYGEN
MODEL
SUPERCONDUCTIVITY
ONSET
Аннотация: The experimental dispersion of the first removal state in the insulating Bi2Sr2Ca1 - xYxCu2O8 + delta regime is found to differ significantly from that of other parent materials: oxyclorides and La2CuO4. For Y contents of 0.92 greater than or equal to x greater than or equal to 0.55 due to nonstoichiometric effects in the Bi-O layers, the hole concentration in the CuO2 layers is almost constant and, on the contrary, the crystal lattice parameters a, b, c change very strongly. This (a, b) parameter increase and c parameter decrease results in an unconventional three peak structure at (0, 0), (pi/2, pi/2), (pi, pi) for x = 0.92. We can describe the experimental data only beyond the framework of the three-band p-d-model involving the representations of a new triplet counterpart for the Zhang-Rice singlet state. (C) 2004 MAIK "Nauka/Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nasluzov V. A., Rivanenkov V. V., Gordienko A. B., Neyman K. M., Birkenheuer U., Rosch N.
Заглавие : Cluster embedding in an elastic polarizable environment: Density functional study of Pd atoms adsorbed at oxygen vacancies of MgO(001)
Место публикации : J. Chem. Phys.: AMER INST PHYSICS, 2001. - Vol. 115, Is. 17. - P8157-8171. - ISSN 0021-9606, DOI 10.1063/1.1407001
Примечания : Cited References: 88
Предметные рубрики: TRANSITION-METAL ATOMS
AB-INITIO
OXIDE SURFACES
ELECTRONIC-PROPERTIES
ENERGY CALCULATIONS
MOLECULAR-DYNAMICS
MOTT-LITTLETON
MADELUNG FIELD
IONIC-CRYSTAL
MGO
Ключевые слова (''Своб.индексиров.''): atoms--binding energy--computer simulation--electron energy levels--electronic structure--magnesia--oxygen--palladium--polarization--probability density function--quantum theory--relaxation processes--charged defects--cluster embedding--elastic polarizable environment--electron affinity--oxygen vacancies--adsorption
Аннотация: Adsorption complexes of palladium atoms on F-s, F-s(+), F-s(2+), and O2- centers of MgO(001) surface have been investigated with a gradient-corrected (Becke-Perdew) density functional method applied to embedded cluster models. This study presents the first application of a self-consistent hybrid quantum mechanical/molecular mechanical embedding approach where the defect-induced distortions are treated variationally and the environment is allowed to react on perturbations of a reference configuration describing the regular surface. The cluster models are embedded in an elastic polarizable environment which is described at the atomistic level using a shell model treatment of ionic polarizabilities. The frontier region that separates the quantum mechanical cluster and the classical environment is represented by pseudopotential centers without basis functions. Accounting in this way for the relaxation of the electronic structure of the adsorption complex results in energy corrections of 1.9 and 5.3 eV for electron affinities of the charged defects F-s(+) and F-s(2+), respectively, as compared to models with a bulk-terminated geometry. The relaxation increases the stability of the adsorption complex Pd/F-s by 0.4 eV and decreases the stability of the complex Pd/F-s(2+) by 1.0 eV, but it only weakly affects the binding energy of Pd/F-s(+). The calculations provide no indication that the metal species is oxidized, not even for the most electron deficient complex Pd/F-s(2+). The binding energy of the complex Pd/O2- is calculated at -1.4 eV, that of the complex Pd/F-s(2+) at -1.3 eV. The complexes Pd/F-s and Pd/F-s(+) exhibit notably higher binding energies, -2.5 and -4.0 eV, respectively; in these complexes, a covalent polar adsorption bond is formed, accompanied by donation of electronic density to the Pd 5s orbital. (C) 2001 American Institute of Physics.
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