Библиотека института физики им. Л.В. Киренского СО РАН

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Vtyurin A. N., Oreshonkov A. S., Voronov V. N., Krylova S. N.
Заглавие : Structural transformations in a single-crystal Rb2NaYF6: Raman scattering study
Место публикации : J. Raman Spectrosc. - 2013. - Vol. 44, Is. 5. - P.763-769. - DOI 10.1002/jrs.4263
Аннотация: This paper reports Raman spectroscopy investigation of phase transitions in Rb2NaYF6 crystal. The experimental spectra were compared with the calculated one. The spectra were obtained in temperature range from 8 to 300 K. The Raman spectra shows anomalous temperature-dependent behavior at T1 = 154 and T2 = 122 K. Soft mode restoration has been found, which allows us to attribute first transition at 154 K to displacive type. Detailed analysis temperature dependencies of the line positions and widths have been performed. We found no effects of possible lattice disorder anywhere, except narrow (about 20 K) range above the T1 temperature. The Raman spectra of Rb2NaYF6 crystal have been obtained and analyzed under hydrostatic pressure up to 4.33 GPa (at T = 295 K). The high pressure experiment up to 4.33 GPa did not disclose any effects associated with phase transitions. The lattice vibration spectra were calculated up to 10 GPa. The calculation has been demonstrated that the Rb2NaYF6 does not undergo high pressure phase transition.
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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) : Ivliev M. P., Misyul S. V., Molokeev M. S., Sakhnenko V. P.
Заглавие : Pseudo-proper ferroelectric phase transitions in oxyfluoride K3WO3F3
Место публикации : Phase Transit.: Taylor & Francis, 2014. - Vol. 87, Is. 6. - P.592-602. - ISSN 0141-1594, DOI 10.1080/01411594.2013.878026. - ISSN 1029-0338
Примечания : Cited References: 14. - This study was supported by the of the President of the Russian Federation for the Support of Leading Scientific Schools [Grant NSh-924.2014.2].
Предметные рубрики: TRANSFORMATIONS
(NH4)(3)MOO3F3
(NH4)(3)WO3F3
CS
Ключевые слова (''Своб.индексиров.''): phase transition--statistical mechanics--order-disorder--ferroelectric--transformations--(nh4)(3)moo3f3--(nh4)(3)wo3f3--cs
Аннотация: Based on the structural data on the phases of cryolite (ordered perovskite) K3WO3F3, we develop a statistical model, which allows to describe the sequence of phase transitions observed in this compound using a unified approach. According to the model, the crystal possesses two structural subsystems: the K cations located in the octahedral positions and the WO3F3 octahedra in positions alternating with K cations. In the symmetric (cubic) phase, each subsystem can be found in one of the eight states. At decreasing temperature, an orientational phase transition in the subsystem of octahedra occurs first, followed by a phase transition to the low-temperature phase, caused by the loss of stability with respect to the ordering in the K cation subsystem. We find that the electric polarization occurs as pseudoproper and discuss the mechanisms of formation of the phase states.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Ovchinnikov S. G.
Заглавие : Spin crossovers in Mott-Hubbard insulators at high pressures
Коллективы : Moscow International Symposium on Magnetism
Место публикации : J. Magn. Magn. Mater.: Elsevier Science BV, 2012. - Vol. 324, Is. 21. - P.3538-3541. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2012.02.084
Примечания : Cited References: 16. - We acknowledge the help and discussions with Drs. A.G. Gavriliuk, V.V. Struzkin and J.F. Lin. Supports by RFBR (Grants # 09-02-00171, 10-02-00251, # 11-02-00636, # 11-02-00291, # 11-02-12089) and by the RAS Program "Strongly correlated electronic systems" are acknowledged.
Предметные рубрики: ELECTRONIC-TRANSITION
MAGNETIC COLLAPSE
PHASE-TRANSFORMATIONS
BIFEO3 CRYSTAL
METAL-OXIDES
METALLIZATION
Ключевые слова (''Своб.индексиров.''): electronic structure--spin crossover--high pressure--magnetic transition
Аннотация: The high-pressure induced phase transitions initiated by electronic transition in 3d ions from the high-spin (HS) to the low-spin (LS) state (HS-LS spin-crossover) are considered. Behavior of the system with d(6) electronic configuration is investigated in the ground state of zero temperature and critical pressure P-c. Magnetic properties of the Mott-Hubbard insulator (Mg1-xFex)O are studied in the vicinity of the quantum critical point (T=0, P-c). At the critical pressure of spin crossover P-c, the spin gap energy epsilon(S) between HS and LS states is zero. The quantum spins fluctuations HS double left right arrow LS do not require any energy, and the antiferromagnetism is destroyed in the quantum critical point by the first order transition. (C) 2012 Published by Elsevier B.V.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Udod L. V., Sitnicov M. N., Aplesnin S. S., Molokeev M. S.
Заглавие : Electrical and dielectrical propeties of gas-sensor resistive type Bi2Sn2O7
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: S. G. Ovchinnikov, A. Samardak: Trans Tech Publications, 2014. - Vol. 215: Trends in Magnetism: Nanomagnetism (EASTMAG-2013). - P.503-506. - ISSN 978-303835054-5, DOI 10.4028/www.scientific.net/SSP.215.503. - ISSN 1662-9779
Примечания : Cited References: 14. - This work was supported by the Russian Foundation for Basic Research projects no. 12-02-00125-а
Ключевые слова (''Своб.индексиров.''): crystallographic structure--polymorphic transformations--electrical resistivity--dielectric permeability
Аннотация: Polycrystalline samples of Bi2Sn2O7 have been synthesized by conventional solid-state reaction method. According to the X-ray powder diffraction research, our sample co-existing of two polymorphs phases: cubic and rhombic, concurrently. The real dielectric permeability Re (ε) monotonic grows versus temperature and the imaginary dielectric permeability Im (ε) nonmonotonic is increased at the heating. There are maxima at Т=450 K on both temperature dependences Im (ε) and Re (ε) reveal. Anomalies in the temperature dependence of electrical resistivity at temperatures are found and to be correlated with the α → β structural phase transition temperature.
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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., Bondarenko G. V., Bondarenko G. N., Patrin G. S., Velikanov D. A.
Заглавие : Phase transformations in the Mn-Ge system and in Ge x Mn1-x diluted semiconductors
Место публикации : JETP Letters. - 2012. - Vol. 96, Is. 1. - P.40-43. - ISSN 0021-3640, DOI 10.1134/S0021364012130097
Примечания : Cited References: 36
Предметные рубрики: HIGH-PRESSURE SYNTHESIS
MAGNETIC-PROPERTIES
THIN-FILMS
Аннотация: Results of an X-ray diffraction study as well as magnetic and electrical measurements of the solid-state reactions in Ge/Mn polycrystalline films of an 80/20 atomic composition have been presented. It has been shown that the ferromagnetic Mn5Ge3 phase is formed first on the Ge/Mn interface after annealing at similar to 120A degrees C. The further increase in the annealing temperature to 300A degrees C leads to the beginning of the synthesis of the Mn11Ge8 phase, which becomes dominating at 400A degrees C. The existence of new structural transitions in the Mn-Ge system in the region of similar to 120 and similar to 300A degrees C has been predicted on the basis of the presented results and results obtained earlier when studying solid-state reactions in different film structures. The supposition about the general chemical mechanisms of the synthesis of the Mn5Ge3 and Mn11Ge8 phases during the solid-state reactions in the Ge/Mn films of the 80/20 atomic composition and the phase separation in Ge (x) Mn1 - x (x 0.95) diluted semiconductors has been substantiated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molokeev M. S., Misyul' S. V.
Заглавие : Processes of ordering of structural elements, critical and noncritical parameters of phase transitions in the (NH4)3WO3F3 crystal
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 1. - P.155-165. - ISSN 1063-7834, DOI 10.1134/S1063783412010222. - ISSN 1090-6460
Примечания : Cited References: 18. - 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 (grant no. NSh-4645.2010.2).
Предметные рубрики: OXYFLUORIDE
TRANSFORMATIONS
(NH4)3TiOF5
DISORDER
Аннотация: The structure of the low-temperature triclinic phase of the (NH4)3WO3F3 crystal has been determined and the structure of the cubic phase of this crystal has been refined from data of an X-ray diffraction experiment performed for a powder sample. The profile and structural parameters have been refined according to the procedure implemented in the DDM program. The results obtained have been discussed with invoking the group-theoretical analysis of the complete order parameter condensate, which takes into account the critical and noncritical atomic orderings and allows one to interpret the obtained experimental data. It has been found that the symmetry transformation in the crystal can be schematically represented in the following form: Fm3¯m(Z=4)→P1¯(Z=1)→P1¯(Z=6)Fm\bar 3m(Z = 4) \to P\bar 1(Z = 1) \to P\bar 1(Z = 6) . This transformation is accompanied by the complete ordering of WO3F3 polyhedra and the displacement of NH4 ions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molokeev M. S., Misyul' S. V.
Заглавие : Structural changes during phase transitions and the critical and noncritical order parameters in the (NH4)3Nb(O2)2F4 crystal
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 1. - P.143-154. - ISSN 1063-7834, DOI 10.1134/S1063783412010234. - ISSN 1090-6460
Примечания : Cited References: 17. - 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 (grant no. NSh-4645.2010.2).
Предметные рубрики: TRANSFORMATIONS
OXYFLUORIDE
CELL
Аннотация: The structures of two phases of the (NH4)3Nb(O2)2F4 crystal, namely, the parent cubic phase and the most distorted low-temperature phase, have been determined from data of an X-ray diffraction experiment performed for a powder sample. The profile and structural parameters have been refined according to the procedure implemented in the DDM program. The results obtained have been discussed with invoking the group-theoretical analysis of the complete order parameter condensate, which takes into account the critical and noncritical atomic displacements and allows the interpretation of the obtained experimental data. It has been found that the most probable sequence of structural transformations occurring in the crystal can be schematically represented in the following form: Fm3¯m−→−−−−(η1,η1,η)Γ+5(11−7)C2/m−→−−−−−−−−−−−−−−−−(η1,η1,η)(0,0,0,0,0,ξ,0−ξ,0,0,0,0)Γ+5(11−7)⊗Σ2(4−2)P21/m−→−−−−−−−−−−−−−−−−−−−−−−−−−−−−(η1,η1,η)(0,0,0,0,0,ξ,0−ξ,0,0,0,0)(0,0,0,0,0,ε,0,ε,0,0,0,0)Γ+5(11−7)⊗Σ2(4−2)⊗Σ3(4−3)P21/n.\begin{gathered} Fm\bar 3m\xrightarrow[{(\eta 1,\eta 1,\eta )}]{{\Gamma _5. + (11 - 7)}}C2/m\xrightarrow[{(\eta 1,\eta 1,\eta )(0,0,0,0,0,\xi ,0 - \xi ,0,0,0,0)}]{{\Gamma _5. + (11 - 7) \otimes \Sigma _2 (4 - 2)}}P2_1 /m \hfill \\ \xrightarrow[{(\eta 1,\eta 1,\eta )(0,0,0,0,0,\xi ,0 - \xi ,0,0,0,0)(0,0,0,0,0,\varepsilon ,0,\varepsilon ,0,0,0,0)}]{{\Gamma _5. + (11 - 7) \otimes \Sigma _2 (4 - 2) \otimes \Sigma _3 (4 - 3)}}P2_1 /n. \hfill \\ \end{gathered}
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Litasov K. D., Shatskiy A. F., Ovchinnikov S. G., Popov Z. I., Ponomarev D. S., Ohtani E.
Заглавие : Phase transformations of Fe3N-Fe4N iron nitrides at pressures up to 30 GPa studied by in situ X-ray diffractometry
Коллективы : Ministry of Education and Science of the Russian Federation [14.B37.21.1261, 14.B25.31.0032]; Siberian Branch, Russian Academy of Sciences [97]
Место публикации : JETP Letters. - 2014. - Vol. 98, Is. 12. - P.805-808. - ISSN 0021-3640, DOI 10.1134/S0021364013250140. - ISSN 1090-6487
Примечания : Cited References: 23. - This work was supported by the Ministry of Education and Science of the Russian Federation (project nos. 14.B37.21.1261 and 14.B25.31.0032) and, in part, by the Siberian Branch, Russian Academy of Sciences (integration project no. 97 for 2012-2014). The experiments were performed in cooperation between the Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, and Tohoku University (Global Center of Excellence program "Advanced Science and Technology Center for the Dynamic Earth").
Предметные рубрики: EQUATION-OF-STATE
MAGNETIC-PROPERTIES
EPSILON-Fe3N1+X
1ST-PRINCIPLES
DIFFRACTION
GAMMA-Fe4N
TRANSITION
Fe4N
Аннотация: The parameters of the equation of state of the stable epsilon-Fe3Nx (where x = 0.8) nitride in the Fe-N system have been determined at pressures up to 30 GPa and temperatures up to 1273 K. The parameters V-0 = 81.48(2) angstrom(3), K-T = 162(3) GPa, K-T = 4.0 = 1.66(2), gamma(0) = 555 K, and q = 1 have been determined for epsilon-Fe3N0.8 by the approximation of the P V T data with the Vinet equation of state and the thermal parameters within the formalism. No anomalous change in the volume of the cell owing to possible magnetic transitions has been revealed. The instability of Fe4N at high pressures and Fe3N in the presence of a deficit of nitrogen in the system has been established. The stable phase in the temperature range of 300-673 K and the pressure range of 20-30 GPa is epsilon-Fe3N rather than epsilon-Fe3N0.8.
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10.

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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