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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Valkova T. A.
Заглавие : Application of indefinite metric for transition to bose description of Su(3) hamiltonians - excitation spectrum of spin nematics
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 99, Is. 6. - P.1881-1897. - ISSN 0044-4510
Примечания : Cited References: 37
Предметные рубрики: BIQUADRATIC EXCHANGE
PHASE-TRANSITIONS
DIAGRAM TECHNIQUE
MAGNETISM
FIELD
STATE
Аннотация: A procedure is developed for a correct transition to the Bose representation for quantum SU(3) Hamiltonians. The analysis is carried out for a spin nematic by applying the indefinite metric formalism and pseudo-Hubbard operators. An important aspect of the theory is that the finiteness of the number of physical states is taken into account. This is attained by introducing and consistently taking into account the metric operator for which purpose a simple expression in terms of Bose operators is suggested. It is shown that in this approach the quantum Bose analog of the Hamiltonian is an Hermitian operator. This circumstance removes a number of principle contradictions which appeared previously on application of the Bose analog of the Hamiltonian derived by virtually identifying the Hubbard and pseudo-Hubbard operators and ignoring the finiteness of the number of physical states. The integral equations defining the chief characteristics of the system are obtained and solved analytically for the spin-nematic state of a magnet with S = 1 and by taking into account anharmonic effects. This permits one to write down in nonlinear theory explicit expressions for the two branches of the quantum excitation spectrum. The character of the renormalization of the spectrum parameters due to the presence of zero-point quantum oscillations is studied. The renormalization of the critical field on transition of the system from the spin nematic state is calculated analytically.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Application of synchrotron radiation to the study of magnetic materials
Место публикации : Uspekhi Fiz. Nauk: MEZHDUNARODNAYA KNIGA, 1999. - Vol. 169, Is. 8. - P.869-887. - ISSN 0042-1294
Примечания : Cited References: 93
Предметные рубрики: X-RAY-SCATTERING
RESONANCE EXCHANGE SCATTERING
RARE-EARTH-METALS
CIRCULAR-DICHROISM
VALENCE STATES
CO/PD(111) MULTILAYERS
ABSORPTION-SPECTRA
PHASE-TRANSITIONS
SPIN POLARIZATION
EDGE STRUCTURE
Аннотация: The recent results of the studies of magnetic materials using synchrotron irradiation are reviewed. The influence of magnetic effects on X-ray scattering is studied for linearly and circularly polarized photons, and effects of magnetic circular dichroism on the spectra of X-ray absorption and photoelectron emission are discussed. It is shown that X-ray magnetooptics techniques provide fine details of crystal and magnetic structures and also make it possible to separate the spin and orbital contributions to the total moment; to obtain element- and position-sensitive information on the magnetic properties of the material; to visualize domains and domain walls; and to probe magnetization reversal dynamics. A comparison of magnetic neutron and X-ray methods is given.
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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) : Fokina V. D., Bogdanov E. V., Pogorel'tsev E. I., Bondarev V. S., Flerov I. N., Laptash N. M.
Заглавие : Calorimetric and dielectric studies of the (NH4)(2)MoO2F4 oxyfluoride
Коллективы :
Разночтения заглавия :авие SCOPUS: Calorimetric and dielectric studies of the (NH4)2MoO2F4 oxyfluoride
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 1. - P158-166. - ISSN 1063-7834, DOI 10.1134/S1063783410010282
Примечания : Cited References: 22. - This study was supported by the Russian Foundation for Basic Research ( project no. 09-02-00062).
Предметные рубрики: PHASE-TRANSITIONS
(NH4)(2)WO2F4
DIFFRACTION
MECHANISM
CRYSTALS
Аннотация: The temperature dependences of the heat capacity, dielectric properties, and response to an external pressure and an electric field for the (NH4)(2)MoO2F4 oxyfluoride (space group Cmcm, Z = 4) have been studied. A comparative analysis of the data on the entropy of phase transitions, p-T phase diagrams, permittivity, and anomalous heat capacity in combination with the results of previous studies of the related compounds (NH4)(2)WO2F4 and (ND4)(2)WO2F4 has made it possible to establish that both [MO2F4](2-) anions and ammonium groups play a substantial role in the mechanism and nature of the structural transformations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Kartashev A. V., Mel'nikova S. V.
Заглавие : Calorimetric and optical studies of orthorhombic and cubic CsLiCrO4 crystals
Разночтения заглавия :авие SCOPUS: Calorimetric and optical studies of orthorhombic and cubic CsLiCrO 4 crystals
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2171-2176. - ISSN 1063-7834, DOI 10.1134/S1063783406110242
Примечания : Cited References: 23
Предметные рубрики: PHASE-TRANSITIONS
X-RAY
NH4LISO4
ALPHA
Аннотация: Careful calorimetric and polarization optical studies of a metastable cubic modification of a CsLiCrO4 crystal (space group (F43m)) are performed. Anomalies of the heat capacity indicative of structural distortions at 92.4 and 69.1 K were revealed, and the values of the thermodynamic parameters of the phase transitions were determined. The crystal twinning in the intermediate phase was studied. A comparative analysis of the phase transitions occurring in a series of ALiMO(4) crystals (A=NH4, Cs; M=S, Cr, Mo, W) was performed. First studies of the monotropic structural transformation F43m - Pmcn and the enantiotropic phase transition Pmcn reversible arrow P112(1)/n were carried out using scanning calorimetry, and the thermodynamic parameters of these transitions were determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Bovina A. F., Laptash N. M.
Заглавие : Calorimetric and x-ray diffraction studies of the (NH4)(3)WO3F3 and (NH4)(3)TiOF5 perovskite-like oxyfluorides
Разночтения заглавия :авие SCOPUS: Calorimetric and X-ray diffraction studies of the (NH4)3WO 3F3 and (NH4)3TiOF5 perovskite-like oxyfluorides
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 5. - P915-921. - ISSN 1063-7834, DOI 10.1134/1.1744971
Примечания : Cited References: 11
Предметные рубрики: PHASE-TRANSITIONS
ELPASOLITE
K3MOO3F3
Аннотация: The heat capacity and unit cell parameters of the (NH4)(3)WO3F3 and (NH4)(3)TiOF5 perovskite-like oxyfluorides were measured in the temperature interval from 80 to 300 K; the existence of two and one phase transitions in these compounds, respectively, was demonstrated, and their thermodynamic parameters were determined. The effect of a hydrostatic pressure of up to 0.5 GPa on the phase transition temperatures was studied. Triple points and high-pressure phases were found in the T vs. p diagrams. An analysis of entropy changes suggests that all the structural transformations revealed are associated with the ordering of structural blocks. (C) 2004 MAIK "Nauka / Interperiodica".
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanov Y. N., Totz J., Michel D., Klotzsche G., Sukhovsky A. A., Aleksandrova I. P.
Заглавие : Chemical exchange in NH4HSeO4 single crystals studied by two-dimensional H-2 nuclear magnetic resonance
Разночтения заглавия :авие SCOPUS: Chemical exchange in NH4HSeO4 single crystals studied by two-dimensional 2H nuclear magnetic resonance
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1999. - Vol. 11, Is. 18. - P.3751-3760. - ISSN 0953-8984, DOI 10.1088/0953-8984/11/18/310
Примечания : Cited References: 16
Предметные рубрики: PHASE-TRANSITIONS
CONDUCTIVITY PROCESSES
AMMONIUM
Ключевые слова (''Своб.индексиров.''): hydrogen bonds--nuclear magnetic resonance--single crystals--thermal effects--ammonium hydrogen selenate--ammonium compounds
Аннотация: Processes of chemical exchange of deuterons in partially deuterated ammonium hydrogen selenate, NH4HSeO4 (AHSe), crystals are investigated by means of H-2 nuclear magnetic resonance (NMR) experiments over a wide temperature range. The temperature dependencies of the quadrupole line splittings in the one-dimensional spectra of AHSe above 350 K revealed lineshape changes which are characteristic for chemical exchange processes. A detailed study of these exchange processes in AHSe is achieved by means of two-dimensional H-2 NMR experiments. In the temperature range investigated, a chemical exchange occurs only between those deuteron (proton) sites which are involved in hydrogen bonds (alpha- and beta-positions). It was established that the rates of exchange between all types of hydrogen-bound deuteron are approximately the same. Exchange between these positions and the deuterons in the ND4 groups could not be detected. On the basis of our findings, we finally discuss a model for the microscopic mechanism of hydrogen transport in AHSe.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia, Zhiguo, Molokeev M. S., Oreshonkov A. S., Atuchin V. V., Liu R. S., Dong C.
Заглавие : Crystal and local structure refinement in Ca2Al3O6F explored by X-ray diffraction and Raman spectroscopy
Место публикации : Phys. Chem. Chem. Phys.: Royal Society of Chemistry, 2014. - Vol. 16, Is. 13. - P.5952-5957. - ISSN 1463-9076, DOI 10.1039/c3cp53816h. - ISSN 1463-9084
Примечания : Cover illustration: Graphical abstract from this article. - Cited References: 34. - This present work was supported by the National Natural Science Foundations of China (Grant No. 51002146, 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047) and Beijing Youth Excellent Talent Program (YETP0635), and this study was also partially supported by SB RAS, Grant 28.13. Part of the work was supported by the National Science Council of Taiwan under contract No. NSC 101-2113-M-002-014-MY3.
Предметные рубрики: EMITTING OXYFLUORIDE PHOSPHOR
PHASE-TRANSITIONS
SOLID-STATE
FLUORIDES
DIODES
Аннотация: We present a combined structural analysis on the powder of the Ca2Al3O6F phase using X-ray diffraction (XRD) and Raman spectroscopy techniques. The crystal structure of Ca2Al3O6F has been refined in the rhombohedral system, R space group, a = 17.3237(7) Å, c = 7.00017(4) Å, V = 1819.38(2) Å3, Z = 6. The Ca2Al3O6F phase consists of almost ideal AlO4 tetrahedrons linked through corners, Ca2+ ions in voids, and F− ions disordered over 6 sites around the Ca2 ion. The two different Ca sites have also been verified by the photoluminescence spectrum and decay curves using Eu2+ as the probe ion substituted onto the Ca2+ sites. A lattice dynamics simulation based on the simplified version of the Born–Karman potential model has been produced. Calculated Raman phonon modes agree qualitatively well with the experimental data. The calculations show that the strong line at 538 cm−1 (Ag) corresponds to the vibrational mode of a six-membered AlO4 tetrahedrons ring, and the line at 572 cm−1 (Ag) corresponds to the full symmetric vibration of fluorine atoms in the ab crystal plane.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Kartashev A. V., Gorev M. V., Bogdanov E. V., Bondarev V. S., Korotkov L. N., Rysiakiewicz-Pasek E.
Заглавие : Effect of a restricted geometry on thermal and dielectric properties of NH4HSO4 ferroelectric
Коллективы : Russia/CIS/Baltic/Japan Symposium on Ferroelectricity , Russian Foundation for Basic Research (RFBR) [16-32-00092 mol_a]
Место публикации : Ferroelectrics. - 2017. - Vol. 513, Is. 1. - P.44-50. - ISSN 0015-0193, DOI 10.1080/00150193.2017.1350436. - ISSN 1563-5112(eISSN)
Примечания : Cited References:17. - The reported study was partially supported by the Russian Foundation for Basic Research (RFBR), research project No. 16-32-00092 mol_a.
Предметные рубрики: PHASE-TRANSITIONS
AMMONIUM
CAPACITY
SULFATE
KH2PO4
Ключевые слова (''Своб.индексиров.''): ferroelectric--phase transition--porous glass--nanocomposite
Аннотация: Heat capacity, thermal dilatation, sensitivity to pressure and permittivity of NH4HSO4 embedded into glass matrices with a pore size of 320 nm and 46 nm were studied. Large difference in the thermal expansion of both glass and ferroelectric leads to a "clamped" state of NH4HSO4 in nanocomposites and to the phase transition temperatures change. The restricted geometry does not effect on the order of successive transformations in NH4HSO4 but is accompanied by a significant reduction in entropy of phase transitions. The behavior of DTA-signal and permittivity show the expansion of the temperature range of the ferroelectric phase under hydrostatic pressure.
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11.

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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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Fokina V. D., Gorev M. V., Bogdanov E. V., Molokeev M. S., Bovina A. F., Kocharova A. G.
Заглавие : Effect of deuteration on the thermal properties and structural parameters of the (NH4)(2)WO2F4 oxyfluoride
Разночтения заглавия :авие SCOPUS: Effect of deuteration on the thermal properties and structural parameters of the (NH4)2WO2F4 oxyfluoride
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 6. - P1149-1156. - ISSN 1063-7834, DOI 10.1134/S1063783407060212
Примечания : Cited References: 11
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
PHASE-TRANSITIONS
(NH4)(3)WO3F3
(NH4)(3)TIOF5
Аннотация: The thermal properties and structure of (ND4)(2)WO2F4 crystals are investigated. It is established that deuteration does not lead to a change in the symmetry of the initial phase Cmcm but considerably decreases the extent of its disordering, which, in turn, brings about a substantial decrease in the phase transition entropy. Apart from the anomalies associated with phase transitions characteristic of the protonic compound, the heat capacity exhibits two additional anomalies. Analysis of the phase diagram of the deuterated crystal reveals a triple point at a pressure p = 0.18 GPa, which is predicted for (NH4)(2)WO2F4 at about 0.7 GPa.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Bondarev V. S., Gorev M. V., Vasiliev A. D., Davydova T. N.
Заглавие : Electrocaloric and barocaloric effects in some ferroelectric hydrosulfates and triglycinesulfate
Коллективы : European Meeting on Ferroelectricity
Место публикации : European Meeting on Ferroelectricity (12 ; 2011 ; 26 June - 1 July ; Bordeaux, France). Ferroelectrics: Taylor & Francis LTD, 2012. - Vol. 430. - P.78-83. - ISSN 0015-0193, DOI 10.1080/00150193.2012.677717
Примечания : Cited References: 14. - This work was supported by the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools (project no, Nsh - 4645.2010.2).
Предметные рубрики: PHASE-TRANSITIONS
AMMONIUM
RbHSO4
Ключевые слова (''Своб.индексиров.''): ferroelectrics--phase transitions--electrocaloric and barocaloric effects
Аннотация: A comparative analysis of electrocaloric and barocaloric efficiency of order-disorder ferroelectrics Rbx(NH4)1-xHSO4 and TGS is performed. A good agreement was found between intensive electrocaloric effects measured experimentally and calculated using electric equation of state. Barocaloric effects were evaluated analyzing the experimental data on heat capacity and T-p phase diagrams. In some crystals under study the same adiabatic temperature change can be produced by low pressure and rather high electric field.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Mikhaleva E. A.
Заглавие : Electrocaloric effect and anomalous conductivity of the ferroelectric NH4HSO4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 3. - P478-484. - ISSN 1063-7834, DOI 10.1134/S1063783408030141
Примечания : Cited References: 10
Предметные рубрики: PHASE-TRANSITIONS
Аннотация: An intensive electrocaloric effect in the uniaxial ferroelectric NH4HSO4 near the second-order phase transition (T-1 approximate to 271 K) is studied. A high electrical conductivity of the NH4HSO4 crystal is revealed, and its temperature dependence is investigated. The results obtained are analyzed together with the data available for the ferroelectrics, which hold promise for the use as solid-state cooling agents.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gerasimova J. V., Vtyurin A. N.
Заглавие : Evans hole in internal modes IR spectrum of WO3F33-ions in (NH4)(3)WO3F3 crystal
Место публикации : Chem. Phys. Lett.: ELSEVIER SCIENCE BV, 2012. - Vol. 523. - P.144-147. - ISSN 0009-2614, DOI 10.1016/j.cplett.2011.12.041
Примечания : Cited References: 11. - We would like to thank Prof. E. M. Aver'yanov for discussion, and V. A. Ouskin for the technical assistance. This work has been supported by the Russian Foundation for Basic Researches, Grant No. 11-02-98002-r_sibir_a.
Предметные рубрики: INFRARED-SPECTRA
PHASE-TRANSITIONS
OXYFLUORIDE
MOLECULES
Аннотация: Infrared absorption of (NH4)(3)WO3F3 compound has been studied. Profile of asymmetric band in 600-1000 cm (1) range associated with polar W-O vibrations of WO3F33- ions is explicable on the basis of multi-oscillatory dynamics with account of damping. Complex profile with Evans holes proves that internal modes of WO3F33- anions in the fluorine-oxygen octahedron interact due to the effects of the local field. (C) 2011 Elsevier B. V. All rights reserved.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Isaenko L. I., Kesler V. G., Lin Z. S., Molokeev M. S., Yelisseyev A. P., Zhurkov S. A.
Заглавие : Exploration on anion ordering, optical properties and electronic structure in K3WO3F3 elpasolite
Место публикации : J. Solid State Chem. - 2012. - Vol. 187. - P.159-164. - ISSN 0022-4596, DOI 10.1016/j.jssc.2011.12.037
Примечания : Cited References: 50. - This study is partly supported by SB RAS Project No. 34. ZSL acknowledges the funding support of No. 91022036, 11174297, 2010CB630701, and 2011CB922204 in China. Authors also wish to thank V. D. Fokina for microcaloric measurements.
Предметные рубрики: PHASE-TRANSITIONS
CRYSTAL-GROWTH
FERROELECTRIC K3WO3F3
SOLID-STATE
OXYFLUORIDE
FLUORIDE
POLAR
CS
(NH4)(3)MOO3F3
APPROXIMATION
Anion ordering
Chemical routes
Elpasolite
First-priciples calculation
Forbidden band
Low temperatures
Non-linear optical coefficients
Nonlinear optical crystal
Optical transparency
Oxyfluorotungstate
Room temperature
Ключевые слова (''Своб.индексиров.''): oxyfluorotungstate--structure--nonlinear optical crystals--electronic and optical properties--first-principles calculations
Аннотация: Room-temperature modification of potassium oxyfluorotungstate, G(2)-K3WO3F3, has been prepared by low-temperature chemical route and single crystal growth. Wide optical transparency range of 0.3-9.4 mu m and forbidden band gap E-g=4.32 eV have been obtained for G(2)-K3WO3F3 crystal. Meanwhile, its electronic structure has been calculated with the first-principles calculations. The good agreement between the theorectical and experimental results have been achieved. Furthermore, G(2)-K3WO3F3 is predicted to possess the relatively large nonlinear optical coefficients. (C) 2012 Elsevier Inc. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gekht R. S., Epikhin A. M., Ponomarev V. I.
Заглавие : Helicoidal magnetic structure in frustrated antiferromagnetics
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 37, Is. 6. - P.1891-1893. - ISSN 0367-3294
Примечания : Cited References: 6
Предметные рубрики: QUANTUM FLUCTUATIONS
PHASE-TRANSITIONS
WOS
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Ovchinnikov S. G.
Заглавие : Isotope effect in the model of strongly correlated electrons with the magnetic and phonon superconducting pairing mechanisms
Коллективы : Presidium of the Russian Academy of Sciences [40]; Russian Academy of Sciences; Russian Foundation for Basic Research [09-02-00127]
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.1017-1021. - ISSN 1063-7761, DOI 10.1134/S1063776109120139
Примечания : Cited References: 42. - This study was financed under programs 5.7 and "Quantum Physics of Condensed Matter" of the Presidium of the Russian Academy of Sciences, integration project no. 40 of the Siberian Branch and Ural Division of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: CUPRATE SUPERCONDUCTORS
PHASE-TRANSITIONS
3-CENTER INTERACTIONS
HUBBARD-MODEL
TEMPERATURE
LA2-XSRXCUO4
SYMMETRY
EXCHANGE
COPPER
BI2SR2CACU2O8+DELTA
Ключевые слова (''Своб.индексиров.''): ab initio calculations--calculated values--cooper pairing--isotope effect--magnetic mechanisms--order of magnitude--pairing mechanism--phonon mechanism--strongly correlated electrons--superconducting pairing mechanism--superconducting state--type theory--carrier mobility--electron-phonon interactions--isotopes--superconductivity--superconducting magnets
Аннотация: Peculiarities of the temperature isotope effect in a BCS-type theory describing the exchange and phonon mechanisms of Cooper pairing in a system of strongly correlated electrons are considered. The electron-phonon interaction constant is determined from the fitting of the calculated value of the isotope-effect index to the observed value with the parameters of La(2 - x) Sr (x) CuO(4) obtained from ab initio calculations. The value of this constant indicates that the contribution from the traditional pairing mechanism to the superconducting state is of the same order of magnitude as the contribution from the magnetic mechanism.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Sofronova S. N., Kolesnikova E. M., Vtyurin A. N., Isaenko L. I.
Заглавие : Lattice dynamics of oxyfluoride Rb2KMoO3F3
Коллективы : International Symposium on Ferroic Domains and Micro- to Nanoscopic Structures, Russia/CIS/Baltic/Japan Symposium on Ferroelectricity
Место публикации : Ferroelectrics: Taylor & Francis LTD, 2012. - Vol. 441. - P.52-60. - ISSN 0015-0193, DOI 10.1080/00150193.2012.743791
Примечания : Cited References: 23
Предметные рубрики: PHASE-TRANSITIONS
RAMAN-SCATTERING
ELPASOLITE
CRYSTALS
DISORDER
SPECTRA
CS
Ключевые слова (''Своб.индексиров.''): oxyfluorides--lattice dynamics--ramam measurements
Аннотация: The complete Raman spectra of oxyfluoride Rb2KMoO 3F3 were obtained. At T ≈ 185 K phase transitions were found. Lattice dynamics of disordered structures of the investigated compound was simulated, and "soft" vibrational modes were found in the calculated spectrum. Copyright © Taylor & Francis Group, LLC.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : GEKHT R. S., PONOMAREV V. I.
Заглавие : LOW-TEMPERATURE PROPERTIES OF QUASI-2-DIMENSIONAL FRUSTRATED ANTI-FERROMAGNETICS
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 11. - P3394-3397. - ISSN 0367-3294
Примечания : Cited References: 8
Предметные рубрики: PHASE-TRANSITIONS
MAGNETIC STATES
ANTIFERROMAGNETS
WOS
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