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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Sukhinin Y. V.
Заглавие : Phase transitions in a system of CH3(CH2)(n-1) self-assembled on the Au(111) crystal surface
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1996. - Vol. 54, Is. 24. - P17966-17973. - ISSN 1098-0121, DOI 10.1103/PhysRevB.54.17966
Примечания : Cited References: 44
Предметные рубрики: ORGANIZED MOLECULAR ASSEMBLIES
ALKYL THIOL MONOLAYERS
STRUCTURAL CHARACTERIZATION
DYNAMICS SIMULATION
DEVILS STAIRCASE
GOLD SURFACES
FILMS
MODEL
CHAIN
DIFFRACTION
Аннотация: The n-alkanethiols CH3(CH2)(n-1) on the crystal surface of gold (111) are considered. Couplings between atoms (C, H) of the n-alkanethiols were modelled by the Morse potential, and couplings between the n-alkanethiols and the crystal surface were modelled by 12-3 potentials. Because of symmetry Z(2) of the n-alkanethiols in a tilted state, the system can be reduced to the Ising model on the triangular lattice, the phase diagram of which can be explicitly considered. Depending on the choice of the coupling parameters, the ordered state of the system may form an incommensurate or 2X1 superstructure. The temperatures of the phase transition, equilibrium tilting, twisting, and azimuthal angles are found to depend on the Morse coupling constants.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mushailov E. S., Kim P. D., Turpanov I. A., Bondarenko G. V., Bondarenko G. N., Mishina S. E.
Заглавие : Multilayer composite epitaxial CuCo single crystals
Место публикации : JETP Letters. - 2000. - Vol. 71, Is. 5. - P.195-197. - ISSN 0021-3640, DOI 10.1134/1.568313
Примечания : Cited References: 10
Предметные рубрики: SUPERLATTICES
DIFFRACTION
FILMS
Аннотация: The ion-plasma spraying method was used to synthesize new phases of metastable atomic-ordered layered CuCo single crystals and single crystals of CucCo1 - c solid solutions via epitaxial layer-by-layer crystallization, and some of their physical properties were studied. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Flerov I. N., Bondarev V. S., Sciau P., Lehmann A. G.
Заглавие : Heat capacity of the PbFe1/2Ta1/2O3 perovskite-like compound
Разночтения заглавия :авие SCOPUS: Heat Capacity of the PbFe1/2Ta1/2O3 Perovskite-Like Compound
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 3. - P521-525. - ISSN 1063-7834, DOI 10.1134/1.1687872
Примечания : Cited References: 26
Предметные рубрики: SINGLE-CRYSTALS
PBFE0.5TA0.5O3
FERROELECTRICS
DIFFRACTION
NIOBATE
GROWTH
Аннотация: The heat capacity C-p(T) of the complex perovskite PbFe1/2Ta1/2O3 has been studied using adiabatic calorimetry in the temperature range 150-370 K. Three diffuse anomalies in C-p(T) are found to exist at temperatures T-d approximate to 350 K, T-m approximate to 250-300 K, and T-c approximate to 205 K. The anomalous and the lattice contribution to the heat capacity are separated, and the change in the entropy is determined. The results of the study are discussed jointly with the data on the structure and physical properties of the compound. (C) 2004 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Molokeev M. S., Vasil'ev A. D., Bovina A. F., Laptash N. M.
Заглавие : Heat capacity, structural disorder, and the phase transition in cryolite (NH4)(3)Ti(O-2)F-5
Разночтения заглавия :авие SCOPUS: Heat capacity, structural disorder, and the phase transition in cryolite (NH4)3Ti(O2)F5
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 8. - P1559-1567. - ISSN 1063-7834, DOI 10.1134/S1063783406080221
Примечания : Cited References: 18
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
CRYSTAL-STRUCTURES
(NH4)(3)TIOF5
(NH4)(3)WO3F3
DIFFRACTION
Аннотация: The heat capacity, T-p phase diagrams, and unit cell parameters of cryolite (NH4)(3)Ti(O-2)F-5 were studied over a wide temperature range. A phase transition was found near 226 K, and its thermodynamic characteristics and their dependence on the crystallization conditions were determined. The coordinates and thermal parameters of atoms in the Fm3m phase were refined. An analysis of the electron density distribution and the transition entropy showed that the mechanism of the structural transition involves, above all, rotation of the Ti(O-2)F-5 octahedra. Possible models of disordering of tetrahedral ammonium groups are considered.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fischer P., Pomjakushin V., Sheptyakov D., Keller L., Janoschek M., Roessli B., Schefer J., Petrakovskii G. A., Bezmaternykh L. N., Temerov V. L., Velikanov D. A.
Заглавие : Simultaneous antiferromagnetic Fe3+ and Nd3+ ordering in NdFe3((BO3)-B-11)(4)
Разночтения заглавия :авие SCOPUS: Simultaneous antiferromagnetic Fe3+ and Nd3+ ordering in NdFe3(11BO3)4
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2006. - Vol. 18, Is. 34. - P.7975-7989. - ISSN 0953-8984, DOI 10.1088/0953-8984/18/34/010
Примечания : Cited References: 20
Предметные рубрики: PHASE-TRANSITION
DIFFRACTION
CRYSTALS
GDFE3(BO3)(4)
SINQ
Ключевые слова (''Своб.индексиров.''): iron compounds--magnetic moments--magnetization--neodymium compounds--neutron diffraction--vectors--crystal-field effects--free ion moment--specific heat measurements--symmetry analysis--antiferromagnetic materials
Аннотация: By means of magnetic susceptibility and specific heat measurements, x-ray and unpolarized neutron diffraction investigations on powder and single-crystal samples, simultaneous long-range antiferromagnetic Fe and Nd ordering in NdFe3((BO3)-B-11)(4) with R32 chemical structure has been found at temperatures below T-N = 30.5(5) K down to 1.6 K. At temperatures down to 19 K the propagation vector is k(hex) = [0, 0, 3/2] and becomes slightly incommensurate at lower temperatures. Combined with symmetry analysis, best powder neutron profile fits are obtained with magnetic spiral configurations with the magnetic moments oriented parallel to the hexagonal basal plane according to the irreducible representations tau(3) in the commensurate case. This is in agreement with the easy directions of magnetization perpendicular to the c-axis as determined by magnetic susceptibility measurements. At 1.6 K the magnetic Fe moment amounts to 4.9 mu(B) B close to the free ion moment of Fe3+. The magnetic Nd3+ moment saturates presumably due to crystal-field effects at 2.7 mu(B).
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Fokina V. D., Bovina A. F., Bogdanov E. V., Molokeev M. S., Kocharova A. G., Pogorel'tsev E. I., Laptash N. M.
Заглавие : Mechanism and nature of phase transitions in the (NH4)(3)MoO3F3 oxyfluoride
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 3. - P515-524. - ISSN 1063-7834, DOI 10.1134/S1063783408030219
Примечания : Cited References: 13
Предметные рубрики: (NH4)(2)WO2F4
DIFFRACTION
CS
Аннотация: The temperature dependences of the heat capacity, the unit cell parameter, and the permittivity for the (NH4)(3)MoO3F3 cryolite (space group Fm (3) over barm) are investigated. It is revealed that the compound undergoes ferroelectric and ferroelastic structural phase transitions at temperatures of 297 and 205 K, respectively. The mechanism of structural distortions is discussed in terms of the entropy parameters, pressure-temperature phase diagrams, and electron density maps for critical atoms. An analysis is made of the influence of the cation size and shape on the phase transitions in oxyfluorides of the general formula A(2)A'MO3F3 (A,A' = NH4, K; M = Mo, W).
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fokina V. D., Gorev M. V., Kocharova A. G., Flerov I. N., Pogoreltsev E.I.
Заглавие : Phase transitions and thermodynamic properties of (NH4)(3)VO2F4 cryolite
Место публикации : Solid State Sci. - 2009. - Vol. 11, Is. 4. - P.836-840. - ISSN 1293-2558, DOI 10.1016/j.solidstatesciences.2008.11.004
Примечания : Cited Reference Count: 17. - Гранты: The authors are grateful to Dr. SM. Mel'nikova for the permission to use the unpublished results.; This work was supported by the Russian Foundation for Basic Research (project 06-02-16102).Финансирующая организация: Russian Foundation for Basic Research [06-02-16102]
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
(NH4)(3)TIOF5
CS
(NH4)(3)WO3F3
DIFFRACTION
(NH4)3VO2F4
ELPASOLITE
METALS
RB
Ключевые слова (''Своб.индексиров.''): oxyfluorides--phase transition--calorimetry--phase diagram--ferroelectricity--calorimetry--ferroelectricity--oxyfluorides--phase diagram--phase transition--calorimetry--ferroelectricity--halide minerals--phase diagrams--sugar (sucrose)--thermodynamic properties--calorimetric measurements--cubic phase--first-order phase transitions--heat capacities--oxyfluorides--phase transition temperatures--pressure dependences--structural transformations--temperature ranges--phase transitions
Аннотация: Calorimetric measurements performed in a wide temperature range on (NH4)(3)VO2F4 have shown the presence of four heat capacity anomalies at T-1 = 438 K, T-2 = 244 K, T-3 = 210.2 K, T-4 = 205.1 K associated with the first order phase transitions. In accordance with the permittivity behavior, the structural transformations are of nonferroelectric nature. Pressure dependence of the phase transition temperatures has been studied by DTA under pressure. The entropy of phase transitions is analyzed mainly in the framework of the orientational disordering of NH4+ and VO2F43- ions in a cubic phase. (C) 2008 Elsevier Masson SAS. All rights reserved.
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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) : Hamann-Borrero J. E., Philipp M., Kataeva O., Zimmermann M. V., Geck J., Klingeler R., Vasiliev A., Bezmaternykh L. N., Buchner B., Hess C.
Заглавие : Nonresonant x-ray magnetic scattering on rare-earth iron borates RFe3(BO3)(4)
Коллективы :
Разночтения заглавия :авие SCOPUS: Nonresonant x-ray magnetic scattering on rare-earth iron borates R Fe 3(BO3)4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2010. - Vol. 82, Is. 9. - Ст.94411. - ISSN 1098-0121, DOI 10.1103/PhysRevB.82.094411
Примечания : Cited References: 38. - This work was supported by the Deustche Forschungsgemeinschaft, through the Forschergruppe FOR520 (Grant No. HE3439/6) and HASYLAB at the Feyerherm from HMI Berlin and specially to Jorg Strempfer from HASYLAB at DESY in Hamburg for valuable discussions.
Предметные рубрики: SINGLE-CRYSTALS
CROSS-SECTION
GDFE3(BO3)(4)
NDFE3(BO3)(4)
DIFFRACTION
MNF2
Аннотация: Hard x-ray scattering experiments with a photon energy of 100 keV were performed as a function of temperature and applied magnetic field on selected compounds of the RFe3(BO3)4 family. The results show the presence of several diffraction features, in particular, nonresonant magnetic reflections in the magnetically ordered phase and structural reflections that violate the diffraction conditions for the low-temperature phase P3(1)21 of the rare-earth iron borates. The temperature and field dependence of the magnetic superlattice reflections corroborate the magnetic structures of the borate compounds obtained by neutron diffraction. The detailed analysis of the intensity and scattering cross section of the magnetic reflection reveals details of the magnetic structure of these materials such as the spin domain structure of NdFe3(BO3)(4) and GdFe3(BO3)(4). Furthermore we find that the correlation length of the magnetic domains is around 100 angstrom for all the compounds and that the Fe moments are rotated 53 degrees +/- 3 degrees off from the hexagonal basal plane in GdFe3(BO3)(4).
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10.

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 : Structural and electronic parameters of ferroelectric K3WO3F3
Коллективы :
Место публикации : Solid State Commun. - 2010. - Vol. 150, Is. 43-44. - P.2085-2088. - ISSN 0038-1098, DOI 10.1016/j.ssc.2010.09.023
Примечания : Cited References: 34. - This study was partly supported by RFBR (Grant 09-02-00062) and SB RAS (Grant 34).
Предметные рубрики: CORE-LEVEL SPECTROSCOPY
PHASE-TRANSITIONS
RHEED ANALYSIS
SURFACE
OXYFLUORIDE
ELPASOLITE
(NH4)(2)KWO3F3
SUBSTITUTION
TEMPERATURE
DIFFRACTION
Ключевые слова (''Своб.индексиров.''): ferroelectrics--chemical synthesis--electronic structure--photoelectron spectroscopies
Аннотация: The low-temperature ferroelectric G2 polymorph of K3WO3F3 oxyfluoride is formed by chemical synthesis. The electronic parameters of G2-K3WO3F3 have been measured by X-ray photoelectron spectroscopy under excitation with Al K alpha radiation (1486.6 eV). Detailed spectra have been recorded for all element core levels and Auger lines. The chemical bonding effects in the WO3 F-3 and WO6 octahedrons are considered by using the binding energy difference Delta BE(O-W) = BE(O 1s) BE(W 4f(7/2)). (C) 2010 Elsevier Ltd. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Bogdanov E. V., Flerov I. N., Kocharova A. G., Laptash N. M.
Заглавие : Investigation of thermal expansion, phase diagrams, and barocaloric effect in the (NH4)(2)WO2F4 and (NH4)(2)MoO2F4 oxyfluorides
Коллективы :
Разночтения заглавия :авие SCOPUS: Investigation of thermal expansion, phase diagrams, and barocaloric effect in the (NH4)2WO2F4 and (NH4)2MoO2F4 oxyfluorides
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 1. - P167-175. - ISSN 1063-7834, DOI 10.1134/S1063783410010294
Примечания : Cited References: 27. - This study was performed within the framework of the Interdisciplinary Integration Project no. 34 of the Siberian Branch of the Russian Academy of Sciences and supported by the Krasnoyarsk Regional Science Foundation and the Russian Foundation for Basic Research within the framework of the project "Sibir'" ( grant no. 09-02-98001) and by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools ( project no. NSh-1011.2008.2).
Предметные рубрики: TRANSITIONS
CRYSTALS
DIFFRACTION
MECHANISM
PRESSURE
Аннотация: The thermal expansion along the principal crystallographic axes of the (NH4)(2)WO2F4 and (NH4)(2)MoO2F4 oxyfluorides has been studied. The anomalous behavior of alpha (i) (T) due to the phase transitions has been revealed at T (1) = 271.4 K and T (2) a parts per thousand 180 K for the molybdate and at T (1) = 201.5 K and T (2) a parts per thousand 161 K for the tungstate. The quantities dT/dp and dT/d sigma (i) , which characterize the dependence of the phase transition temperatures on the hydrostatic and uniaxial pressures, have been determined from analyzing the results of studies of the thermal expansion and heat capacity with the use of the Pippard relations. The p-T and alpha (i) -T phase diagrams reflect different characters of the influence of the pressure on the stability of the initial and distorted phases of the oxyfluorides. The magnitudes of the extensive and intensive barocaloric effects determined in the vicinity of the structural phase transitions are as follows: Delta S (BCE) varies from approximately -10 to -17 J/mol K and Delta T (AD) a parts per thousand 8-17 K for the molybdate and Delta S (BCE) varies from approximately -10 to -17 J/mol K and Delta T (AD) a parts per thousand 8-13 K for the tungstate.
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12.

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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Likhacheva A. Y., Goryainov S. V., Krylov A. S., Bul'bak T. A., Prasad PSR
Заглавие : Raman spectroscopy of natural cordierite at high water pressure up to 5?GPa
Место публикации : J. Raman Spectrosc.: Wiley-Blackwell, 2012. - Vol. 43, Is. 4. - P.559-563. - ISSN 0377-0486, DOI 10.1002/jrs.3060
Примечания : Cited References: 38. - We greatly appreciate the critical comments of Prof. R. Kaindl and an anonymous reviewer on this work, and we thank Dr G. Lepezin for providing the cordierite sample. This work was supported by RFBR grant 11-05-01121-a.
Предметные рубрики: SINGLE-CRYSTAL STRUCTURE
X-RAY
CHANNEL H2O
BEHAVIOR
SPECTRA
CO2
POLYMORPHISM
DIFFRACTION
CHEMISTRY
CAVITIES
Ключевые слова (''Своб.индексиров.''): cordierite--raman spectroscopy--high pressure--phase transition
Аннотация: The high-pressure behaviour of cordierite, a widespread ring aluminosilicate with channels incorporating fluid compounds (H2O, CO2), is characterized by the absence of phase transitions up to 2.5 GPa. However, the distortion of the ring tetrahedra observed previously at 2.3 GPa is supposed to introduce a phase transition at higher pressure, which has not been checked so far. This work presents a high-pressure Raman spectroscopic study of natural cordierite compressed in water medium up to 4.7 GPa in a diamond anvil cell. At P 4 GPa, a disordering of both the framework and intrachannel H2O subsystem is apparent from significant broadening of Raman peaks and the evolution of short-range order parameters. This is followed by abrupt shifts of the framework and O–H stretching modes at about 4.5 GPa, indicating a first-order phase transition. Its reversibility is seen from the recovery of the initial spectrum at P 3 GPa. The shift amplitudes of different framework modes indicate the predominance of distortion over contraction of the framework polyhedra upon this transition. The disordering of the H2O subsystem in the high-pressure phase is likely a consequence of distortion of the channel-forming framework elements, which is supposed to be a driving force of this transition. Copyright © 2011 John Wiley & Sons, Ltd.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Krylova S. N., Laptash N. M., Vtyurin A. N.
Заглавие : Raman scattering study of temperature induced phase transitions in crystalline ammonium heptafluorozirconate, (NH4)3ZrF7
Место публикации : Vib. Spectrosc.: Elsevier Science BV, 2012. - Vol. 62. - P.258-263. - ISSN 0924-2031, DOI 10.1016/j.vibspec.2012.07.003
Примечания : Cited References: 31. - This work was partly supported by integration project SB RAS No 28, Russian Foundation for Basic Research project No 11-02-98002-r_siberia, No 12-02-00056, SS-4828.2012.2. The authors are grateful to Dr. I.N. Flerov for helpful discussions. The assistance of Dr. S. Skokov is sincerely appreciated.
Предметные рубрики: VIBRATIONAL-SPECTRA
X-RAY
DISORDER
DIFFRACTION
ELPASOLITE
SYMMETRY
RB2KSCF6
IF7
Ключевые слова (''Своб.индексиров.''): raman spectroscopy--phase transition--ammonium heptafluorozirconate--low temperature
Аннотация: This paper reports on a Raman spectroscopy investigation of phase transitions in (NH4)3ZrF7 crystal. Raman spectra were obtained and analyzed in a wavenumber range from 3800 to 15 cm−1 and in the temperature range from 7 to 360 K. The anomalies caused by a series of subsequent structural phase transitions have been analyzed. A soft phonon mode restoring in the distorted phase was found. The spectral changes observed in the current study are similar to those typically found in phase transitions near a tricritical point. The spectral changes in the middle wavenumber range, 700–150 cm−1, indicate that the phase transitions are due to structural ordering of pentagonal ZrF73− bipyramids. Spectral data also show that a phase transition near 225 K is accompanied by an increase of the unit cell volume. In addition, spectral changes in the range of internal vibrations of ammonium ions indicate that the ion's motion slows down with decrease of temperature.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Kuzubov A. A., Sakai, Seiji, Ohtomo, Manabu, Entani, Shiro, Matsumoto, Yoshihiro, Naramoto, Hiroshi, Eleseeva N. S.
Заглавие : Contact-induced spin polarization in graphene/h-BN/Ni nanocomposites
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 112, Is. 11. - Ст.114303. - P. - ISSN 0021-8979, DOI 10.1063/1.4767134
Примечания : Cited References: 47. - This work was supported by JAEA Research fellowship (P.V.A.). P.V.A. also acknowledges JAEA ASRC and Molecular Spintronics Group for hospitality and fruitful collaboration. The authors are grateful to the ICS SB RAS and SFU CC (Krasnoyarsk), ISC RAS and MSU CRC, (SKIF MSU "Chebyshev", Moscow) for computer resources. This work was partially supported by the RFBR grant 12-02-31417.
Предметные рубрики: HEXAGONAL BORON-NITRIDE
TRILAYER GRAPHENE
NI(111) SURFACE
GRAPHITE
APPROXIMATION
SPINTRONICS
DIFFRACTION
SIMULATION
SUBSTRATE
CARBON
Аннотация: Atomic and electronic structure of graphene/Ni(111), h-BN/Ni(111) and graphene/h-BN/Ni(111) nanocomposites with different numbers of graphene and h-BN layers and in different mutual arrangements of graphene/Ni and h-BN/Ni at the interfaces was studied using LDA/PBC/PW technique. Using the same technique corresponding graphene, h-BN and graphene/h-BN structures without the Ni plate were calculated for the sake of comparison. It was suggested that C-top:C-fcc and N-top:B-fcc configurations are energetically favorable for the graphene/Ni and h-BN/Ni interfaces, respectively. The Ni plate was found to induce a significant degree of spin polarization in graphene and h-BN through exchange interactions of the electronic states located on different fragments. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767134]
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Pogoreltsev E. I., Flerov I. N., Laptash N. M.
Заглавие : Unusual sequence of phase transitions in (NH4)3TiF7 detected by optic and calorimetric studies
Коллективы : Russian Foundation for Basic Research [12-02-00056]; Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation [NSh-924.2014.2]
Место публикации : J. Fluor. Chem.: Elsevier Science, 2014. - Vol. 165. - P.14-19. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2014.05.016. - ISSN 1873-3328
Примечания : Cited References: 13. - This work was supported by Russian Foundation for Basic Research (Grant no. 12-02-00056), and the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation (Grant no. NSh-924.2014.2).
Предметные рубрики: CRYSTAL-STRUCTURE
DIFFRACTION
NH4F
Ключевые слова (''Своб.индексиров.''): cubic fluorides--phase transitions--crystal-optic--calorimetry
Аннотация: For the first time structural transformations were observed for one of the compounds belonging to the family of double salt fluorides A3MeF7 = A2MeF6·AF. Single crystals of (NH4)3TiF7 = (NH4)2TiF6·NH4F were grown by evaporation of the aqueous solution. Polarizing optical observations, heat capacity and birefringence Δn = (no − ne) measurements were performed in a wide temperature range 100–400 K. Two reversible, first order structural phase transitions were found to be followed by an unusual sequence of symmetry changes: cubic (G3) (T2↓ = 287.5 K; T2↑ = 291–310 K) ↔ P4/mnc (G2) (T1↓ = 358.5 K; T1↑ = 360 K) ↔ 4/m (G1). The twin structures observed were described assuming the existence of cubic parent phase G0 with P m 3 ¯ m symmetry.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Bondarev V. S., Raevskaya S. I., Ivliev M. P., Raevskii I. P., Flerov I. N.
Заглавие : Studies of the heat capacity and thermal expansion of the Na0.95K0.05NbO3 solid solution
Коллективы : Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools of the Russian Federation [NSh-4828.2012.2]; Russian Foundation for Basic Research [12-02-31799 mol_a]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 56, Is. 2. - P.367-372. - ISSN 1063-7834, DOI 10.1134/S1063783414020115. - ISSN 1090-6460
Примечания : Cited References: 27. - 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-4828.2012.2) and the Russian Foundation for Basic Research (project no. 12-02-31799 mol_a).
Предметные рубрики: SODIUM NIOBATE
PHASE-TRANSITIONS
TEMPERATURE-RANGE
SINGLE-CRYSTALS
KNBO3
FERROELECTRICS
DIFFRACTION
OCTAHEDRA
Аннотация: The heat capacity and thermal expansion of ceramic samples of the Na0.95K0.05NbO3 solid solution have been investigated over a wide temperature range of 100-750 K. The observed anomalies in the heat capacity and thermal expansion at T (4) = 297 K, T (3) = 535 K, T (2) = 665 K, and T (1) a parts per thousand 710 K correspond to the sequences of phase transitions N - Q - G - S - T1. It has been shown that, as a result of the phase transitions, the unit cell volume at T (4) and T (2) decreases, and at T (3) and T (1), increases with increasing temperature. The directions of the shift of the phase transition temperatures induced by hydrostatic pressure have been determined. It has been established that all structural transformations are accompanied by relatively small variations in the entropy. Different mechanisms of the structural distortions have been discussed.
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18.

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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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivantsov R. D., Edelman I. S., Zharkov S. M., Velikanov D. A., Petrov D. A., Ovchinnikov S. G., Lin C.-R., Li O., Tseng Y.-T.
Заглавие : Effects of processing parameters on the morphology, structure, and magnetic properties of Cu1-xFexCr2Se4 nanoparticles synthesized with chemical methods
Место публикации : J. Alloys Compd.: Elsevier, 2015. - Vol. 650. - P.887-895. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2015.08.017
Примечания : Cited References: 36. - The paper was partially supported by the Russian Foundation for Basic Research (grant #14-02-01211), by the President of Russia (grant #NSh-2886.2014.2), and by the Ministry of Education and Science of the Russian Federation (grant #2014/71/1763 in the framework of the state assignment for the Siberian Federal University for 2014-2016). We also thank the Ministry of Science and Technology of Taiwan and the Siberian Branch of RAS (MOST 102-2112-M-153 -002 -MY3) for financial support.
Предметные рубрики: CuCr2Se4 SINGLE-CRYSTALS
TRANSPORT-PROPERTIES
CHROMIUM SPINELS
NANOSTRUCTURES
DIFFRACTION
Li
Ключевые слова (''Своб.индексиров.''): copper selenide--magnetic nanoparticles--visible magnetic circular dichroism
Аннотация: Cu1-xFexCr2Se4 nanoparticles with x = 0, 0.2, and 0.4 were synthesized via thermal decomposition of metal nitrate or chloride salts and selenium powder using different precursor compositions and processing details. Single crystalline nano-belts or nano-rods coexist in the synthesized powder samples with hexagon-shaped plates in dependence on the precursor composition. The belts gathered into conglomerates forming "hierarchical" particles. Visible magnetic circular dichroism (MCD) of Cu1-xFexCr2Se4 nanoparticles embedded into a transparent matrix was investigated for the first time. The similarity of the MCD spectra of all samples showed the similarity of the nanoparticles electronic structure independent of their morphology. Basing on the MCD spectral maxima characteristics, electron transitions from the ground to the excited states were identified with the help of the conventional band theory and the multi-electron approach. © 2015 Elsevier B.V.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang H., Yu T., Chen Z., Nelson C. S., Bezmaternykh L. N., Abeykoon A. M. M., Tyson T. A.
Заглавие : Probing magnetostructural correlations in multiferroic HoAl3(BO3)4
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 10. - Ст.104108. - ISSN 1098, DOI 10.1103/PhysRevB.92.104108. - ISSN 1550235X(eISSN)
Примечания : Cited References:97. - This work is supported by the U.S.Department of Energy Grant No. DE-FG02-07ER46402. Synchrotron powder x-ray diffraction and x-ray absorption data acquisition were performed at Brookhaven National Laboratory's National Synchrotron Light Source (NSLS). Use of the NSLS was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. The Physical Properties Measurement System used in the heat capacity measurements was acquired under National Science Foundation Major Research Instrumentation Grant No. DMR-0923032 (American Recovery and Reinvestment Act award). This research used resources of the National Energy Research Scientific Computing Center, a U.S. Department of Energy Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Предметные рубрики: PAIR DISTRIBUTION FUNCTION
TOTAL-ENERGY CALCULATIONS
WAVE BASIS-SET
FERROELECTRIC POLARIZATION
DEBYE TEMPERATURES
SINGLE-CRYSTALS
HOFE3(BO3)4
GDFE3(BO3)4
DIFFRACTION
FEATURES
Аннотация: The system HoAl3(BO3)(4) has recently been found to exhibit a large magnetoelectric effect. To understand the mechanism, macroscopic and atomic level properties of HoAl3(BO3)(4) were explored by temperature and magnetic field dependent heat capacity measurements, pressure and temperature dependent x-ray diffraction measurements, as well as temperature and magnetic field dependent x-ray absorption fine structure measurements. The experimental work was complemented by density functional theory calculations. An anomalous change in the structure is found in the temperature range where large magnetoelectric effects occur. No significant structural change or distortion of the HoO6 polyhedra is seen to occur with magnetic field. However, the magnetic field dependent structural measurements reveal enhanced correlation between neighboring HoO6 polyhedra. This observed response is seen to saturate near 3 T. A qualitative atomic level description of the mechanism behind the large electric polarization induced by magnetic fields in the general class of RAl3(BO3)(4) systems (R = rare earth) is developed.
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