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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Gavrilova T. A., Isaenko L. I., Kesler V. G., Molokeev M. S., Zhurkov S. A.
Заглавие : Synthesis and structural properties of cubic G0-Rb2KMoO3F3 oxyfluoride
Место публикации : Ceram. Int.: Elsevier, 2012. - Vol. 38, Is. 3. - P.2455-2459. - ISSN 0272-8842, DOI 10.1016/j.ceramint.2011.11.013
Примечания : Cited References: 23. - This study was partly supported by RFBR (Grant 09-02-00062) and SB RAS (Grant 34).
Предметные рубрики: PHASE-TRANSITIONS
FERROELECTRIC K3WO3F3
(NH4)(3)MOO3F3
TEMPERATURE
PEROVSKITE
ELPASOLITE
CRYSTALS
BEHAVIOR
High temperature
Melt solidification
Micromorphologies
Melt solidification
Microstructure-final
Oxyfluorides
Space Groups
Oxyfluorides
X ray methods
Ключевые слова (''Своб.индексиров.''): powders: solid state reaction--microstructure-final--x-ray methods--alkali oxides--halides
Аннотация: High-temperature G0 polymorph of Rb2KMoO3F3 has been prepared by melt solidification. Micromorphology and chemical properties of the final product were evaluated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The elpasolite-related crystal structure of G0-Rb2KMoO3F3 has been refined by Rietveld method at T = 298 K (space group Fm-3m, a = 8.92446(8) Å, V = 710.76(1) Å3; RB = 3.55%). Ferroelectric G1-Rb2KMoO3F3 polymorph, earlier reported at T˂328 K, is not found at T = 298 K.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisov V. M., Denisova L. T., Irtyugo L. A., Patrin G. S., Volkov N. V., Chumilina L. G.
Заглавие : High-Temperature Heat Capacity of Y2.9Ho0.1Al5O12
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 55, Is. 4. - P.692-695. - ISSN 1063-7834, DOI 10.1134/S1063783413040082
Примечания : Cited References: 21
Предметные рубрики: CRYSTALS
GARNETS
Аннотация: This paper presents data on the heat capacity of Y2.9Ho0.1Al5O12 as a function of temperature (360-1020 K). The experimental data obtained are used to derive the thermodynamic functions of the oxide compound.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Merkushova E. M., Vtyurin A. N., Isaenko L. I.
Заглавие : Raman spectroscopic study of the lattice dynamics in the Rb2KMoO3F3 oxyfluoride
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 6. - P.1275-1280. - ISSN 1063-7834, DOI 10.1134/S1063783412060170
Примечания : Cited References: 24. - This study was supported by the Russian Foundation for Basic Research (project nos. 11-02-98002-r_sibir', 09-02-00062, and NSh-4645.2010.2).
Предметные рубрики: PHASE-TRANSITIONS
SCATTERING
(NH4)3WO3F3
CRYSTALS
DISORDER
Cs
Аннотация: The lattice dynamics of the Rb2KMoO3F3 oxyfluoride has been studied by Raman spectroscopy in the temperature range 7–400 K. A phase transition has been revealed at T ≈ 185 K with decreasing temperature. Anomalies of the frequencies and Raman line half-widths have been analyzed. No condensation of soft lattice modes has been found. The character of changes in the Raman spectra of the Rb2KMoO3F3 oxyfluoride shows that the phase transition is related to variations in the [MoO3F3]3− molecular octahedron.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Crossing resonance of stochastically interacting wave fields
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 116, Is. 2. - P.206-222. - ISSN 1063-7761, DOI 10.1134/S1063776113020118
Примечания : Cited References: 42. - We are grateful to V. V. Val'kov and A. F. Sadreev for useful discussions. This work was supported by the Presidium of the Russian Academy of Sciences (Program no. 24.29), the Dynasty Foundation (Program for Support of Young Scientists), the Federal Target Program (state contract no. 14.B37.21.0730), and the Special Program for Siberian Federal University of the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CRYSTALS
SYSTEMS
ALLOYS
MEDIA
Аннотация: The dynamic susceptibilities (Green's functions) of the system of two interacting wave fields of different physical natures with a stochastically inhomogeneous coupling parameter between them with zero mean value have been examined. The well-known self-consistent approximation taking into account all diagrams with noncrossing correlation/interaction lines has been generalized to the case of stochastically interacting wave fields. The analysis has been performed for spin and elastic waves. The results obtained taking into account the processes of multiple scattering of waves from inhomogeneities are significantly different from those obtained for this situation earlier in the Bourret approximation [R.C. Bourret, Nuovo Cimento 26, 1 (1962)]. Instead of frequencies degeneracy removal in the wave spectrum and the splitting of resonance peaks of dynamic susceptibilities, a wide single-mode resonance peak should be observed at the crossing point of the unperturbed dispersion curves. The fine structure appears at vertices of these wide peaks in the form of a narrow resonance on the Green's-function curve of one field and a narrow antiresonance on the vertex of the Green's-function curve of the other field.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pashchenko M. I., Bedarev V. A., Merenkov D. N., Savina Yu. O., Pashchenko V. O., Gnatchenko S. L., Bezmaternykh L. N., Temerov V. L.
Заглавие : Magneto-optical properties of terbium iron borate
Место публикации : Appl. Optics: Optical Society of America, 2014. - Vol. 53, Is. 10. - P.B116-B120. - ISSN 1559-128X, DOI 10.1364/AO.53.00B116. - ISSN 2155-3165
Примечания : Cited References: 19
Предметные рубрики: GENERATION
CRYSTALS
LASER
Аннотация: The Faraday effect induced by an external magnetic field in TbFe3(BO3)4 and TbAl3(BO3)4 borates at a wavelength 633 nm has been investigated. It was found that the terbium subsystem brings the dominant magnetic contribution to the Faraday rotation at low temperatures in borate TbFe3(BO3)4. For both TbFe3(BO3)4 and TbAl3(BO3)4 the magneto-optical coefficients of the terbium subsystem were determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Sofronova S. N., Kolesnikova E. M., Ivanov Y. N., Sukhovsky A. A., Goryainov S. V., Ivanenko A. A., Shestakov N. P., Kocharova A. G., Vtyurin A. N.
Заглавие : Experimental and theoretical methods to study structural phase transition mechanisms in K3WO3F3 oxyfluoride
Коллективы : Russian Foundation for Basic Research [4828.2012.2, 12-02-31205]; Federal Special Program "Scientific and scientific-pedagogical staff of innovative Russia" [8379]
Место публикации : J. Solid State Chem. - 2014. - Vol. 218. - P.32-37. - ISSN 0022-4596, DOI 10.1016/j.jssc.2014.05.028. - ISSN 1095-726X
Примечания : Cited References: 21. - The Authors are grateful to Prof. Zinenko V.I. for constructive discussion of the results. The work has been done with financial support of the Russian Foundation for Basic Research projects nos. 4828.2012.2, 12-02-31205; Federal Special Program "Scientific and scientific-pedagogical staff of innovative Russia" project no. 8379.
Предметные рубрики: LATTICE-DYNAMICS
RAMAN-SCATTERING
ELPASOLITE
(NH4)3WO3F3
SPECTROSCOPY
CRYSTALS
Ключевые слова (''Своб.индексиров.''): raman spectroscopy--ir spectroscopy--nmr spectroscopy--high hydrostatic pressure--oxyfluorides--lattice dynamics calculations
Аннотация: The results of structural phase transitions mechanisms study in K3WO3F3oxyfluoride are represented by different experimental and theoretical methods. The structural phase transition anomalies at T1=452 K and T2=414 K of Raman and IR spectra have been analyzed. Using vibrational spectroscopy methods, the NMR-experiment has been done to clarify the nature of found phase transitions: displacive types or order-disorder types. The model of “disordered” crystal was proposed, and the results of lattice dynamics calculation in frameworks of the generalized Gordon–Kim method of ordered (R3) and “disordered” crystals were compared. The high pressure phases were studied by the Raman technique too.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Raevski I. P., Titov V. V., Malitskaya M. A., Eremin E. V., Kubrin S. P., Blazhevich A. V., Chen H., Chou C.-C., Raevskaya S. I., Zakharchenko I. N., Sarychev D. A., Shevtsova S. I.
Заглавие : Studies of ferroelectric and magnetic phase transitions in multiferroic PbFe0.5Ta0.5O3-PbTiO3 solid solution ceramics
Коллективы : Russian Foundation for Basic Research (RFBR) [12-08-00887_a]; Research Committee of the University of Macau
Место публикации : J. Mater. Sci.: Springer, 2014. - Vol. 49, Is. 18. - P.6459-6466. - ISSN 0022-2461, DOI 10.1007/s10853-014-8376-z. - ISSN 1573-4803
Примечания : Cited References: 35. - This study is partially supported by the Russian Foundation for Basic Research (RFBR) Project 12-08-00887_a and Research Committee of the University of Macau under Research and Development Grant for Chair Professor.
Предметные рубрики: MOSSBAUER
CRYSTALS
BEHAVIOR
NIOBATE
Аннотация: Dielectric, X-ray, Mossbauer and magnetization studies of (1 − x)PbFe0.5Ta0.5O3–(x)PbTiO3 ceramics with 0 ≤ x ≤ 0.3 have been carried out to determine the compositional evolution of ferroelectric and magnetic phase transition temperatures. Addition of PbTiO3 to PbFe0.5Ta0.5O3 increases the temperature T m of the dielectric permittivity maximum, decreases both the diffusion of this maximum and its frequency dependence. However, the Curie–Weiss temperature exceeds T m for all the compositions studied, indicating that the phase transition still remains diffused. Dilution of the (Fe, Ta)-sublattice by Ti lowers the Neel temperature T N but above a certain compositional threshold (x ≈ 0.1) fast lowering of T N stops and a new magnetic state stable in a rather wide compositional range appears. Large difference between the zero-field-cooled (ZFC) and FC magnetization–temperature curves as well as between the temperatures of magnetic phase transition determined from Mossbauer and magnetization studies for compositions with x 0.1 implies that this state is a spin-glass phase.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popov A. K., Shalaev M. I., Myslivets S. A., Slabko V. V.
Заглавие : Unidirectional amplification and shaping of optical pulses by three-wave mixing with negative phonons
Коллективы : US Air Force Office of Scientific Research [FA950-12-1-298]; US National Science Foundation [ECCS-1028353]; Presidium of the Russian Academy of Sciences [24-31]; Russian Federal Program on Science, Education and Innovation [14.A18.21.1942]
Место публикации : Appl. Phys. A: Springer, 2013. - Vol. 115, Is. 2. - P.523-529. - ISSN 0947-8396, DOI 10.1007/s00339-013-8078-4. - ISSN 1432-0630
Примечания : Cited References: 32. - This work was supported in parts by the US Air Force Office of Scientific Research under Grant No. FA950-12-1-298, by the US National Science Foundation under Grant No. ECCS-1028353, by the Presidium of the Russian Academy of Sciences under Grant No. 24-31 and by the Russian Federal Program on Science, Education and Innovation under Grant No. 14.A18.21.1942.
Предметные рубрики: LEFT-HANDED METAMATERIALS
2ND-HARMONIC GENERATION
INDEX METAMATERIALS
NONLINEAR OPTICS
PARAMETRIC AMPLIFICATION
COMPENSATING LOSSES
BACKWARD WAVES
OSCILLATOR
CRYSTALS
Аннотация: A possibility to greatly enhance frequency-conversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of three-wave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily available crystals which support elastic waves with contra-directed phase and group velocities. The main goal of this work was to investigate specific properties of indicated nonlinear optical process in short-pulse regime and to show that it enables elimination of fundamental detrimental effect of fast damping of optical phonons on the process concerned. Among the applications is the possibility of creation of a family of unique photonic devices such as unidirectional Raman amplifiers and femtosecond pulse shapers with greatly improved operational properties.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Aleksandrov K. S., Tressaud A., Fokina V. D.
Заглавие : Ferroelastic phase transitions in fluorides with cryolite and elpasolite structures
Место публикации : Crystallogr. Rep. - 2004. - Vol. 49, Is. 1. - P.100-107. - ISSN 1063-7745, DOI 10.1134/1.1643969
Примечания : Cited References: 43
Предметные рубрики: NUCLEAR MAGNETIC-RESONANCE
THERMODYNAMIC PROPERTIES
RB2KMIIIF6 ELPASOLITES
NEUTRON-DIFFRACTION
CRYSTALS
PEROVSKITES
DIAGRAM
SC
RB2KGAXSC1-XF6
SCATTERING
Аннотация: The ferroelastic phase transitions are investigated in several series of fluoride crystals belonging to the elpasolite and cryolite families (space group Fm (3) over barm) with the general formula A(2)BB'F-6. The influence of the size and shape of cations and anions on the entropy and the mechanism of structural distortions is discussed. (C) 2004 MAIK "Nauka/Interperiodica".
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Voronov V. N., Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S.
Заглавие : Lattice dynamics and hydrostatic-pressure-induced phase transitions in ScF3
Место публикации : J. Exp. Theor. Phys.: American Institute of Physics, 2002. - Vol. 94, Is. 5. - P.977-984. - ISSN 1063-7761, DOI 10.1134/1.1484991
Примечания : Cited References: 20
Предметные рубрики: RAMAN-SPECTROSCOPY
CRYSTALS
SCATTERING
Аннотация: New phase transitions induced by hydrostatic pressure in a cubic (under standard conditions) ScF3 crystal are discovered by the methods of polarization microscopy and Raman scattering. The space groups R (3) over barc for Z = 2 and Pnma for Z = 4 are proposed for the high-pressure phases. A nonempirical computation of the lattice dynamics of the crystal is carried out. It is shown that, under normal pressure, the cubic phase is stable down to T = 0 K, while the application of a hydrostatic pressure gives rise to a phonon branch in the vibrational spectrum (between points R and M of the Brillouin zone) with negative values of squares of frequencies. The condensation of soft mode R-5 at the boundary point of the Brillouin zone leads to rhombohedral distortion of the cubic structure with the unit cell volume doubling. The calculated frequencies at q = 0 of the ScF3 lattice in the distorted rhombohedral phase are real-valued; the number and position of frequencies active in Raman scattering are in accord with the experimental values. (C) 2002 MAIK "Nauka/Interperiodica".
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarova I. P., Verin I. A., Aleksandrov K. S.
Заглавие : X-ray diffraction study of RbLiCrO4
Коллективы : European meeting on ferroelectricity
Место публикации : Ferroelectrics. - 1991. - Vol. 124, Is. 1. - P.91-96. - ISSN 0015-0193, DOI 10.1080/00150199108209420
Примечания : Cited References: 12
Предметные рубрики: LITHIUM POTASSIUM-SULFATE
THERMAL VIBRATIONS
CRYSTALS
PROGRAM
KLISO4
LIKSO4
Аннотация: Crystal structure of RbLiCrO4 was determined in G3 phase (sp. gr. P31c) at 293, 428, 493, 523 K and in G2 phase (sp. gr. P63) at 553, 583 K applying X-ray diffraction data. The investigated crystals exhibit ‘twinning by merohedry’. The analysis of intensities and influence of anomalous scattering on them allowed us to choose twin elements and atomic configurations of twin domains for all the investigated specimens.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Misyul S. V., Molokeev M. S., Voronov V. N.
Заглавие : Structures of distorted phases and critical and noncritical atomic displacements of elpasolite Rb2KInF6 during phase transitions
Коллективы : President of the Russian Federation [NSh-1011.2008.2]
Место публикации : Phys. Solid State. - 2009. - Vol. 51, Is. 12. - P.2505-2512. - ISSN 1063-7834, DOI 10.1134/S1063783409120130
Примечания : Cited References: 21. - This work was supported by the Council on Grants from the President of the Russian Federation, grant NSh-1011.2008.2.
Предметные рубрики: CRYSTALS
Аннотация: The structures of all three phases of the Rb2KInF6 crystal have been determined from the experimental X-ray diffraction data for the powder sample. The refinement of the profile and structural parameters has been carried out by the technique implemented in the DDM program, which minimizes the differences between the derivatives of the calculated and measured X-ray intensities over the entire profile of the X-ray diffraction pattern. The results obtained have been discussed using the group-theoretical analysis of the complete order-parameter condensate, which takes into account the critical and noncritical atomic displacements and permits the interpretation of the experimental data obtained previously. It has been reliably established that the sequence of changes in the symmetry during phase transitions in Rb2KInF6 can be represented as Fm (3) over barm 11-9(Gamma(+)(4))- 0, 0, phi I114/m 11-9(Gamma(+)(4)) circle plus 10-3(Chi(+)(3))- (psi, phi, phi) P12(1)/n1.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Demidov A. A., Volkov D. V., Gudim I. A., Eremin E. V., Boldyrev K. N.
Заглавие : Magnetic, magnetoelastic, and spectroscopic properties of TmAl3(BO3)4
Коллективы : Russian Foundation for Basic Research [13-02-12442ofi_m2]; Russian Federation [MK-1700.2013.2]
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 119, Is. 4. - P.737-744. - ISSN 1063-7761, DOI 10.1134/S106377611410015X. - ISSN 1090-6509
Примечания : Cited References: 28. - This study was supported financially by the Russian Foundation for Basic Research (project no. 13-02-12442ofi_m2) and (K.N.B.) by the grant no. MK-1700.2013.2 from the President of the Russian Federation.
Предметные рубрики: THERMAL-EXPANSION
CRYSTALS
MAGNETOSTRICTION
HoAl3(BO3)4
GARNETS
Аннотация: The thermodynamic properties of alumoborate TmAl3(BO3)4 single crystal are studied experimentally and theoretically. A theoretical analysis based on the crystal field model makes it possible to interpret all measured parameters. The crystal field parameters are determined. The temperature (3–300 K) and field (up to 9 T) dependences of magnetization are described. The field and temperature dependences of multipole moments of the Tm3+ ion in TmAl3(BO3)4 make it possible to describe magnetostriction and low-temperature anomalies in thermal expansion.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Safonov I. N., Misyul' S. V., Molokeev M. S., Ivliev M. P.
Заглавие : Structural transformations and phenomenological description of the formation of phase states in elpasolites Cs2RbDyF6 and Rb2KB′F6 (B′ = Ho, Dy, Tb)
Коллективы : Ministry of Education and Science of the Russian Federation [3.2534.2014/K]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 57, Is. 3. - P.491-498. - ISSN 1063, DOI 10.1134/S1063783415030282. - ISSN 10906460(eISSN)
Примечания : Cited References:20. - This study was supported by the Ministry of Education and Science of the Russian Federation within the framework of the State Task for the Russian Siberian Federal University for Implementation of Scientific Research Work in 2014 (assignment no. 3.2534.2014/K).
Предметные рубрики: TRANSITIONS
CRYSTALS
Аннотация: The structures of the cubic and monoclinic phases of an Rb2KHoF6 crystal from a series of elpasolites Rb2KB′F6 (B′ = Ho, Dy, Tb), which undergoes a trigger phase transition, have been investigated using X-ray powder diffraction. The critical and noncritical displacements of atoms in the Rb2KHoF6 structure have been determined from the group-theoretical analysis of the complete condensate of order parameters. It has been reliably established that a change in the symmetry due to the phase transition in this crystal can be represented in the form Fmˉ3m11−9(Γ+4)⊕10−3(X+3)(ϕ,ϕ,ψ)P121/n1Fm\bar 3m\frac{{11 - 9(\Gamma _4. + ) \oplus 10 - 3(X_3. + )}} {{(\phi ,\phi ,\psi )}}P12_1 /n1 . A phenomenological analysis of the conditions responsible for the formation of phase states upon the phase transitions in elpasolites Cs2RbDyF6 and Rb2KB′F6 (B′ = Ho, Dy, Tb) has been carried out. Taking into account the structural data and using the phenomenological theory, it has been found that the main factor determining the formation of phase states in these and related crystals is the instability of the elpasolite structure with respect to rotational distortions of two types. It has been shown that an important role in the formation of a sequence of structural transformations in these crystals is played by the interaction of rotational order parameters and displacements of the cation from the center of a cuboctahedral hole.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova M. N., Boldyrev K. N., Klimin S. A., Stanislavchuk T. N., Sirenko A. A., Bezmaternykh L. N.
Заглавие : Spectral signatures of spin-phonon and electron-phonon interactions in multiferroic iron borates
Коллективы : Moscow International Symposium on Magnetism , Russian Science Foundation [14-12-01033], U.S. Department of Energy [DE-FG02-07ER46382, DE-AC02-98CH10886]
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2015. - Vol. 383. - P.250-254. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2014.10.095. - ISSN 1873-4766 (eISSN)
Примечания : Cited References:32. - This work was supported by the Russian Science Foundation (Grant no. 14-12-01033). Experiments at U4-IR beamline NSLS-BNL (T.N.S. and A.A.S.) were performed under Contract no. DE-FG02-07ER46382 from the U.S. Department of Energy. The National Synchrotron Light Source is operated as a User Facility for the U.S. Department of Energy under Contract no. DE-AC02-98CH10886. M.N.P. thanks B.Z. Malkin for helpful discussions.
Предметные рубрики: SMFE3(BO3)4
SPECTROSCOPY
CRYSTALS
SM
Ключевые слова (''Своб.индексиров.''): rare-earth iron borates--spin phonon interactions--electron phonon coupling--optical spectroscopy
Аннотация: High-resolution far-infrared reflection and polarized ellipsometry, as well as Raman scattering temperature-dependent measurements are used to study spin-phonon and electron-phonon interactions in rare-earth (RE) iron borates with the R32 structure of a natural mineral huntite, namely, in RFe3(BO3)4 with R=Pr, Nd, and Sm. Pronounced peculiarities in the ω(T) dependences at the Néel temperature TN≈32 K are observed for all the compounds studied and the origin of these peculiarities is discussed. A coupling between lattice phonons and crystal-field excitations of a RE ion manifests itself by a renormalization of frequencies and intensities of coupled modes. Modeling of the spectra has revealed the value of about 15 cm−1 for the electron–phonon coupling constant in PrFe3(BO3)4.Высокоразрешающая эллипсометрия дальнего инфракрасного отражения и поляризованный света, а также температурнозависимые измерения комбинационного рассеяния используются для изучения спин-фононных и электрон-фононных взаимодействий в редкоземельных (RE) боратах железа со структурой R32 природного минерала хантита , а именно, в RFe3 (BO3) 4 с R = Pr, Nd, и Sm. Выраженные особенности ω (T) зависимостей при температуре Нееля TN ≈32 K наблюдаются для всех исследованных соединений и происхождение этих особенностей обсуждается.Связь между фононами решетки и возбуждениями кристаллического поля РЗ иона проявляется себя перенормализации частоты и интенсивности связанных мод. Моделирование спектров показал значение около 15cm-1 для константы электрон-фононной связи в PrFe3 (BO3) 4.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Boldyrev K. N., Pisarev R. V., Bezmaternykh L. N., Popova M. N.
Заглавие : Antiferromagnetic dichroism in a complex multisublattice magnetoelectric CuB2O4
Коллективы : Russian Academy of Sciences under the Programs for Basic Research; Russian Federation [MK-3521.2015.2], Russian Foundation for Basic Research [15-32-20613, 15-02-04222], Ministry of Education and Science of the Russian Federation [14.B25.0031.25]
Место публикации : Phys. Rev. Lett.: American Physical Society, 2015. - Vol. 114, Is. 24. - Ст.247210. - ISSN 0031, DOI 10.1103/PhysRevLett.114.247210. - ISSN 10797114(eISSN)
Примечания : Cited References:40. - This study was supported by the Russian Academy of Sciences under the Programs for Basic Research, by the President of the Russian Federation (Grant No. MK-3521.2015.2, K. N. B.), by the Russian Foundation for Basic Research (Grants No. 15-32-20613, K. N. B., and No. 15-02-04222, R. V. P.), and by the Ministry of Education and Science of the Russian Federation (Grant No. 14.B25.0031.25, R. V. P.).
Предметные рубрики: MAGNETIC SOLITON LATTICE
COPPER METABORATE
GYROTROPIC BIREFRINGENCE
SPECTROSCOPY
EXCITATIONS
TRANSITIONS
CRYSTALS
Cr2O3
FIELD
Аннотация: Magnetic control of the crystal chirality was announced by Saito et al. [Phys. Rev. Lett. 101, (2008)] on the ground of experiments in CuB2O4. This claim has raised a sharp dispute in the literature because it seemed to contradict the fundamental symmetry principles. We settle this dispute on the basis of a high-resolution optical spectroscopy study of excitonic transitions in CuB2O4. We find that a large sublattice-sensitive antiferromagnetic linear dichroism (LD) emerges at the Néel temperature TN=21 K and show how it could simulate a “magnetic-field control of the crystal chirality.” We prove that the discovered LD is related microscopically to the magnetic Davydov splitting. This LD is highly sensitive to subtle changes in the spin subsystems, which allowed us to observe a splitting of the phase transition into an incommensurate magnetic phase into two transitions (T∗1=8.5 and T∗2=7.9 K) and to suggest elliptical spiral structures below T∗1, instead of a simple circular helix proposed earlier.О магнитном контроле кристаллической хиральности сообщил Сайто и др. [Phys. Rev. Lett. 101, 117402 (2008)] на основании экспериментов в CuB2O4. Это требование вызвало резкий спор в литературе, потому что это казалось, противоречат основным принципам симметрии. Мы урегулировать этот спор на основе исследования с помощью оптической спектроскопии высокого разрешения экситонных переходов в CuB2O4. Мы считаем, что большой подрешетко-чувствительный антиферромагнитный линейный дихроизм (LD) возникает при температуре Нееля TN= 21 Kи показываем, как это может имитировать "контроль магнитным полем кристаллической хиральности." Мы докажем, что обнаруженный LD связанс микроскопическим магнитным Давыдовским расщеплением. Этот Л.Д. весьма чувствителен к тонким изменениям в спиновых подсистем, которые позволили нам наблюдать расщепление фазового перехода в несоизмеримы магнитная фаза в двух переходов (T*1= 8,5 и Т*2 = 7,9 К) и предположить эллиптическую спиральную структуру ниже T*1, вместо простой круговой спирали предложенный ранее.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Laptash N. M.
Заглавие : Optical studies of the (T-x) phase diagram of oxyfluoride (NH4)2MoO2F4-Rb2MoO2F4 solid solutions
Коллективы : Russian Federation [NSh-924.2014.2]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 57, Is. 6. - P.1201-1205. - ISSN 1063, DOI 10.1134/S1063783415060256. - ISSN 10906460(eISSN)
Примечания : Cited References:8. - This study was supported by the Council on Grants from the President of the Russian Federation for Supporting of Leading Scientific Schools of the Russian Federation (grant NSh-924.2014.2).
Предметные рубрики: TRANSITIONS
(NH4)2WO2F4
CRYSTALS
DISORDER
Аннотация: Single crystals of solid solutions (NH4)2 − x Rb x MoO2F4 (including individual complex Rb2MoO2F4) have been grown and studied using polarization-optical methods. The birefringence Δn(T) has been measured in the temperature range of 100–400 K. The complete (T-x) phase diagram has been constructed.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrovsky A. S., Vyunishev A. M., Shakhura I. E., Zaitsev A. I., Zamkov A. V.
Заглавие : Nonlinear optical processes in domain structures of strontium tetraborate
Коллективы : International Conference on Laser Optics
Место публикации : Opt. Spectrosc. - 2009. - Vol. 107, Is. 3. - P.359-362. - ISSN 0030-400X, DOI 10.1134/S0030400X09090070
Примечания : Cited References: 11
Предметные рубрики: HARMONIC-GENERATION
CRYSTALS
Аннотация: The random quasi-phase-matching in irregular domain structures of strontium tetraborate has been investigated for nonlinear optical generation at 266 nm. The factor of increasing second-harmonic generation efficiency due to random quasi-phase-matching is determined. The spectral dependences of the second-harmonic generation are calculated. It is shown that its efficiency can be optimized at a fixed pump wavelength by rotating the domain structure.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ushakov A. V., Karpov I. V., Lepeshev A. A., Petrov M. I.
Заглавие : Enhancing of magnetic flux pinning in YBa2Cu3O7-x/CuO granular composites
Коллективы : Ministry of Education and Science of the Russian Federation [11.370.2014/K]
Место публикации : J. Appl. Phys.: American Institute of Physics, 2015. - Vol. 118, Is. 2. - Ст.023907. - ISSN 0021-8979, DOI 10.1063/1.4926549
Примечания : Cited References: 27. - This work was supported in part by the Ministry of Education and Science of the Russian Federation (Project No. 11.370.2014/K).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
T-C SUPERCONDUCTORS
CRITICAL CURRENTS
GRAIN-BOUNDARIES
CRYSTALS
DEFECTS
Аннотация: This paper shows that the combination of self-assembled structures in the form of "whiskers" and nanoparticles, which appear as a result of the joint sintering powders YBa2Cu3O7-x and arc nanopowders CuO, leads to a significant increase in the current density and the appearance of the peak effect in strong magnetic fields range. Very high critical current density appears from a complex vortex pinning, where the defects in the form of "whiskers" provides more energy of pinning, and nanoparticles inhibit the flux creep. Regulation of the morphology of such structures can be achieved by simple change of the concentration of nanodispersed additives. It is shown that the optimal additive is CuO equal to 20 wt. %. © 2015 AIP Publishing LLC.
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