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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorobyev S. A., Saikova S. V., Erenburg S. B., Trubina S. V., Ivanov Y. N., Maksimov N. G., Mikhlin Y. L.
Заглавие : A comparative study of the structure of copper and lead xanthates
Место публикации : J. Struct. Chem. - 2017. - Vol. 58, Is. 6. - P.1144-1151. - ISSN 00224766 (ISSN), DOI 10.1134/S0022476617060117
Примечания : Cited References: 38
Ключевые слова (''Своб.индексиров.''): copper xanthate--lead xanthate--dixanthogen--structure--xps--exafs--solid state nmr
Аннотация: XPS, PbL3 and CuK EXAFS, solid state NMR, and EPR techniques are used to study insoluble products formed in the interaction of aqueous solutions of lead(II) nitrate and copper (II) sulfate with potassium nbutylxanthate (KX). The XPS spectra of lead xanthates with the composition PbX2 are similar to those of KX, and interatomic distances of 0.279 nm suggest a nearly ionic character of Pb–S bonds. In copper xanthate precipitating together with dixanthogen (approximately 15 wt.%), the Cu(I)–S bond length is smaller (0.229 nm), and copper coordination number of 2.9 in a composite with dixanthogen increases to 3.3 after its removal by washing with acetone. The XPS spectra indicate the covalent character of the bond and non-equivalence of xanthate radicals. Solid state 1H and 13C NMR spectra as well as the actual absence of metal lines under the measurement conditions demonstrate strong disordering of the structure of xanthates, which is stronger for PbX2 and weakest in CuX after the removal of dixanthogen. EPR reveals sulfur-containing radicals and Cu2+ in CuX, however, their amounts are insignificant and decrease after the washing with acetone. The results of the work are significant for the understanding of the reactivity of xanthates, in particular, under the conditions of flotation of base metal ores.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Ageev O. A.
Заглавие : Rb-87 NMR in Rb2CDCl4
Место публикации : Fiz. Tverd. Tela: Mezhdunarodnaya kniga, 1990. - Vol. 32, Is. 7. - P.2126-2129. - ISSN 0367-3294
Примечания : Cited References: 8
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Structural and thermodynamic consequencies of the interaction of conformational degrees of freedom of azomethines in the nematic phase
Место публикации : J. Struct. Chem.: Springer, 2014. - Vol. 55, Is. 4. - P.605-611. - ISSN 0022-4766, DOI 10.1134/S0022476614040039. - ISSN 1573-8779
Примечания : Cited References: 21
Предметные рубрики: CONJUGATED POLY(AZOMETHINE)S
TERMINAL SUBSTITUENTS
ELECTRONIC-STRUCTURES
FLUORINATED ANALOGS
INTERNAL-ROTATION
MOLECULES
COMPOUND
ANGLES
STATE
NMR
Ключевые слова (''Своб.индексиров.''): azomethines--benzylideneaniline--conformation--steric effects of substituents--nematic-isotropic liquid transition--conformational polymorphism
Аннотация: The interaction of the conformational degrees of freedom of azomethines in the nematic phase, which is induced by electronic donor-acceptor properties of the terminal substituents of the benzylideneaniline core is studied. These degrees of freedom related to the rotation angles phi (k) around the bonds between the substituent and the aniline ring (phi(1)) and also between the CH=N bridge and the aniline ring (omega(2)) are characterized by the parameters Q (k) = aOE (c) cos(2)phi (k) . It is found that the interaction of these degrees of freedom is manifested in the linear dependence Q (2)(Q (1)). Within the phenomenological theory the effect of this interaction on changes delta (k) in the Q (k) values during the nematic liquid crystal-isotropic liquid phase transition is revealed along with the temperature T (NI) and character of this transition. The derivation of previously established empirical dependences T (NI)(Q (k) ) is presented in the presence of direct and indirect steric effects of side substituents affecting the Q (k) values. A diverse combination of delta (k) signs in the nematic phase, which is a prerequisite for the conformational polymorphism of the nematic phases of azomethines, is shown.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yasuda Y., Nakamura H., Fujii Y., Kikuchi H., Chiba M., Yamamoto Y., Hori H., Petrakovskii G. A., Popov M. A., Bezmaternykh L. N.
Заглавие : B-11-NMR study of low-temperature phase transition in CuB2O4
Разночтения заглавия :авие SCOPUS: 11B-NMR study of low-temperature phase transition in CuB 2O4
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2007. - Vol. 19: International Conference on Highly Frustrated Magnetism (AUG 15-19, 2006, Osaka, JAPAN), Is. 14. - Ст.145277. - ISSN 0953-8984, DOI 10.1088/0953-8984/19/14/145277
Примечания : Cited References: 10
Предметные рубрики: COPPER METABORATE
Ключевые слова (''Своб.индексиров.''): copper compounds--low temperature effects--magnetic field effects--nuclear magnetic resonance--b t phase diagram--dzialoshinskii moriya interaction--phase transitions
Аннотация: The material CuB2O4 presents a variety of phases in the B - T phase diagram, caused by the frustration and the Dzialoshinskii - Moriya interaction. In order to investigate the nature of the phase transitions, a B-11- NMR experiment on CuB2O4 has been performed under an applied magnetic field along the a- axis down to 0.4 K. A new incommensurate - incommensurate phase transition has been found at 0.8 K under a field of 0.5 T. Further, another phase transition has been observed at 4.7 K under a field of about 2 T, which is consistent with the transition reported by the neutron diffraction experiment.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I.P., Ivanov Yu.N., Bondarev V.S., Sukhovskiy A.A., Voronov V.N.
Заглавие : Calorimetric and 23Na MAS NMR Study of the Phase Diagram of NaNb1-xTaxO3 Solid Solutions
Место публикации : Functional mate rials. - 2010. - Vol. 17. - С. 18-24
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I. P., Ivanov Y. N., Bondarev V. S., Sukhovskii A. A., Voronov V. N.
Заглавие : Calorimetric and 23Na MAS NMR study of the phase diagram of NANB1_xTAxO3 solid solutions
Место публикации : Functional Materials. - 2010. - Vol. 17, Is. 1. - P.18-23. - ISSN 1027-5495
Аннотация: The heat capacity of NaNb1_xTaxO3 solid solutions was measured in the temperature range 100 to 770 K. The step-like change of phase transition temperature is observed in the T-x phase diagram at concentration x = 0.55. The obtained results are in a good agreement with the data of dielectric studies. The 23Na MAS NMR spectra were obtained at Larmor frequency 79.35 MHz using a Bruker AVANCE 300 spectrometer. The quadru-polar coupling constant, (CQ=e2qQ/h) and asymmetry parameter (n) were determined by computer fitting of the NMR line shape using the DMFit software. The found parameters show that solid solution structure is NaTa03-based at 0.7<X ?1 and NaNbO3-based at 0?x?0.5. The spectra in the intermediate region (0.5<x?0.7) can be described at a reasonable accuracy when assuming the coexistence of NaTaO3 and NaNbO3 structures. В© 2010 - STC "Institute for Single Crystals".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gabrienko A. A., Morozov E. V., Subramani V., Martyanov O. N., Kazarian S. G.
Заглавие : Chemical visualization of asphaltenes aggregation processes studied in situ with ATR-FTIR spectroscopic imaging and NMR imaging
Коллективы : Skolkovo Foundation; BP
Место публикации : J. Phys. Chem. C: American Chemical Society, 2015. - Vol. 119, Is. 5. - P.2646-2660. - ISSN 1932-7447, DOI 10.1021/jp511891f
Примечания : Cited References:78. - This research was performed under the UNIHEAT project. The authors wish to acknowledge the Skolkovo Foundation and BP for financial support. The authors thank BP for providing samples of crude oil
Предметные рубрики: MEXICAN CRUDE OILS
X-RAY-DIFFRACTION
INFRARED-SPECTROSCOPY
PETROLEUM ASPHALTENES
MOLECULAR-DYNAMICS
VARIABLE SELECTION
ORGANIC-SOLVENTS
LIGHT-SCATTERING
N-HEPTANE
NEAR-IR
Аннотация: Crude oil phase behavior and asphaltene precipitation have been studied by two complementary chemical imaging methods for the first time. ATR-FTIR spectroscopic imaging approach has revealed the chemical composition of agglomerated and precipitated asphaltenes upon dilution with a flocculant. Asphaltenes, containing oxygen and nitrogen heteroatomic functional groups, have been detected to be least stable. Aromatic abundant asphaltenes have been observed to have relatively high solubility in crude oil/heptane blends. NMR imaging approach, capable of imaging in the bulk of crude oil samples, has demonstrated that n-heptane causes aggregation which can lead to the stable suspension or to the sedimentation followed by the formation of deposits, depending on flocculant concentration. These processes have been monitored for small and large amounts of heptane added to crude oil. The data obtained by ATR-FTIR spectroscopic imaging and NMR imaging have been correlated to propose a possible link between the chemical structure of asphaltenes and a mechanism of the formation of deposits.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chudin O. S., Verpekin V. V., Kondrasenko A. A., Burmakina G. V., Piryazev D. A., Vasiliev A. D., Pavlenko N. I., Zimonin D. V., Rubaylo A. I.
Заглавие : Chemistry of vinylidene complexes. XXV. Synthesis and reactions of binuclear µ-vinylidene RePt complexes containing phosphite ligands. Spectroscopic, structural and electrochemical study
Место публикации : Inorg. Chim. Acta. - 2020. - Vol. 505. - Ст.119463. - ISSN 00201693 (ISSN), DOI 10.1016/j.ica.2020.119463
Примечания : Cited References: 56. - This work was conducted within the framework of the budget project AAAA-A17-117021310221-7 for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Centre of SB RAS
Аннотация: Reactions of Cp(CO)2ReCCHPh with Pt[P(OR)3]4 (R = Pri, Et, Ph) gave binuclear μ-vinylidene complexes Cp(CO)2RePt(μ-CCHPh)[P(OR)3]2. Treatment of the previously synthesized Cp(CO)2Re(μ-CCHPh)Pt(PPh3)2 with triisopropylphosphite or triethylphosphite resulted in a stepwise substitution of PPh3 ligands, leading to the disubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3]2 and monosubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3](PPh3) (R = Pri or Et) species, while no triphenylphosphine ligand substitution in the reaction with P(OPh)3 occurs at all. The monosubstituted Cp(CO)2RePt(μ-CCHPh)[P(OR)3](PPh3) (R = Pri, Et, Ph) species were also obtained by reacting Cp(CO)2ReCCHPh with mixed-ligand complexes Pt(PPh3)3L (L = P(OPri)3, P(OEt)3, P(OPh)3). Reactions of Cp(CO)2RePt(μ-CCHPh)LL′ (L = L′ = P(OPri)3, P(OEt)3, P(OPh)3; L = P(OPri)3, P(OEt)3, P(OPh)3, L′ = PPh3) with Co2(CO)9 yield tricarbonyl vinylidene species Cp(CO)2RePt(μ-CCHPh)[P(OR)3](CO) (R = Pri, Et, Ph). The obtained compounds were characterized by IR and 1H, 13C, 31P NMR spectroscopy. The molecular structures of Cp(CO)2RePt(μ-CCHPh)[P(OPri)3]2, Cp(CO)2RePt(μ-CCHPh)[P(OPri)3](PPh3) and Cp(CO)2RePt(μ-CCHPh)[P(OPri)3](CO) were determined by X-ray diffraction study. The redox properties of the new complexes and their reactions of chemical oxidation were studied.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ioganson A.A., Antonova A.B., Deikhina N.A., Pogrebnyakov D.A., Pavlenko N.I., Burmakina G.V., Rubailo A.I., Petrovskii P.V., Ginzburg A.G.
Заглавие : Chemistry of vinylidene complexes: XIV. Synthesis and NMR and IR study of heterometallic PdMn, PdFe2, and PdFe3 complexes with Ph2PCH2CH2PPh2 chelating ligand
Место публикации : Russian Journal of General Chemistry. - Санкт-Петербург: Pleiades Publishing, Ltd. (Плеадес Паблишинг, Лтд), 1999. - Т. 69, № 6. - С. 847-855. - ISSN 1070-3632. - ISSN 1608-3350(eissn)
ГРНТИ : 31.17
РИНЦ
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Antonova A.B., Chudin O.S., Pavlenko N.I., Sokolenko W.A., Rubaylo A.I., Vasiliev A. D., Verpekin V.V., Semeikin O.V.
Заглавие : Chemistry of vinylidene complexes
Место публикации : Russ. Chem. Bull. - NEW YORK: SPRINGER, 2009. - Vol. 58, Is. 5. - С. 955-963. - MAY. - ISSN 1066-5285, DOI 10.1007/s11172-009-0122-3
Примечания : Cited Reference Count: 35. - Гранты: This work was financially supported by the Krasnoyarsk Regional Science Foundation (Grants Nos. 10TS145 and 17G002), the Council on Grants at the President of the Russian Federation (Program for State Support of Leading Scientific Schools, Grant NSh-4137.2006.2), and the Presidium of the Russian Academy of Sciences (Program for Basic Research, Project No. 18.18).Финансирующая организация: Krasnoyarsk Regional Science Foundation [10TS145, 17G002]; Council on Grants at the President of the Russian Federation [NSh-4137.2006.2]; Presidium of the Russian Academy of Sciences [18.18]
Предметные рубрики: RAY CRYSTAL-STRUCTURE
MOLECULAR-STRUCTURE
PHENYLVINYLIDENE LIGANDS
BRIDGED COMPLEXES
TRANSITION-METALS
CARBONYL LIGAND
BINUCLEAR
DERIVATIVES
DINUCLEAR
RHENIUM
Ключевые слова (''Своб.индексиров.''): vinylidene complexes--heterometallic complexes--manganese--rhenium--palladium--platinum--ir and nmr spectroscopy--x-ray diffraction study--heterometallic complexes--ir and nmr spectroscopy--manganese--palladium--platinum--rhenium--vinylidene complexes--x-ray diffraction study
Аннотация: The reactions of Cp(CO)(2)Re=C=CHPh (2) with M(PPh(3))(4) (M = Pd, Pt) gave the mu-vinylidene complexes Cp(CO)(2)RePd(mu-C=CHPh)(PPh(3))(2) (3) and Cp(CO)(2)RePt(mu-C=CHPh)(PPh(3))(2) (1), respectively. The substitution of Ph(2)PCH(2)PPh(2) (dppm) for the PPh(3) ligands in 1 resulted in the formation of Cp(CO)RePt(mu-C(1)=C(2)HPh)(mu-CO)(dppm) (4). The structure of complex 4 has been determined by single-crystal X-ray diffraction analysis. The structural and spectroscopic characteristics of complexes 1, 3, and 4 were compared with the corresponding parameters of the manganese-containing analogs Cp(CO)(2)MnPd(mu-C=CHPh)(PPh(3))(2) (5), Cp(CO)(2)MnPt(mu-C=CHPh)(PPh(3))(2) (6) and Cp(CO)(2)MnPt(mu-C=CHPh)(dppm) (7).
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Drokin N. A., Kumakhov M. A., Shabanov V. F.
Заглавие : Dielectric properties of liquid crystals in polycapillary matrices
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 6. - P1315-1322. - ISSN 1063-7834, DOI 10.1134/S1063783410060314
Примечания : Cited References: 24. - This study was supported by the Council on Grants from the President of the Russian Federation (grant no. 3818.2008.3) and the Siberian Branch of the Russian Academy of Sciences (Integration Project no. 5) and performed within the framework of the State Contract (no. 02.740.11.0220).
Предметные рубрики: MOLECULAR-SIEVES
SILICA AEROGEL
POROUS-GLASS
MEMBRANES
NMR
8CB
Аннотация: This paper reports on the results of investigations into the dielectric properties of liquid crystals embedded in polycapillary matrices and describes a technique for their measurement. It has been revealed that the chemical structure of the rigid core and the length of mobile alkyl groups of liquid-crystal molecules of the alkylcyanobiphenyl group substantially affect the equilibrium configuration of the liquid-crystal director in capillaries. The reorientation of liquid-crystal molecules embedded in capillaries in the nematic phase under the influence of an external magnetic field has been investigated.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Trukhan, Sergey N., Kozhevnikov, Ivan V., Peterson, Ivan V., Martyanov, Oleg N.
Заглавие : Dynamics of asphaltene aggregates under high-pressure CO2 revealed by pulsed-field gradient NMR
Колич.характеристики :12 с
Место публикации : Energy & Fuels. - 2023. - Vol. 37, Is. 22. - P.17215-17226. - ISSN 08870624 (ISSN), DOI 10.1021/acs.energyfuels.3c02862. - ISSN 15205029 (eISSN)
Примечания : Cited References: 90. - The present research was performed with the financial support of the Russian Science Foundation (project no. 21-13-00171, http://rscf.ru/project/21-13-00171/) using the equipment of the Krasnoyarsk Regional Center of Research Equipment of the Federal Research Center “Krasnoyarsk Science Center SB RAS”
Аннотация: The work demonstrates the results of the first experimental PFG NMR study in situ of the complex phase behavior of asphaltenes in the presence of high-pressure CO2. To perform the experiments, a series of sealed, thick-walled quartz capillaries were prepared with a mixture of CO2 and asphaltenes dissolved either in chloroform or benzene at different initial concentrations. Then, the temperature dependence of the diffusion coefficients of the asphaltene aggregates was measured for each sample after the mixture reached its equilibrium state, at which, in accordance with the solubility limit, only part of the initial asphaltenes remained dissolved. Despite quite low residual asphaltene concentrations in solution, experimental data clearly demonstrated the presence of aggregated structures (up to 70–80 wt %) attributed solely to nanoaggregates, with no signs of the presence of macroaggregates in the samples. Temperature dependencies of aggregate diffusivity clearly showed that the scenario, according to which the evolution of the asphaltene aggregates will develop, strongly depends on the initial asphaltene concentration, mass fraction of CO2 loaded into the system, and chemical nature of the solvent used. In particular, the most diluted asphaltene solution, expected to be the most resistive to the aggregation processes in a high-pressure CO2 environment, revealed the most pronounced aggregation-dependent translational dynamics as compared to those with a moderate initial asphaltene concentration. Contrarily, the concentrated asphaltene solution may not show drastic aggregation processes if the mass fraction of the CO2 loaded will not appear to be so high. Finally, the experimental results provide evidence that the temperature-triggered structural transformation of asphaltene aggregates due to the noncovalent bond breakup is not hindered under high-pressure CO2, but instead becomes more emphasized. The results obtained shed new light on asphaltene aggregate dynamics and brought new knowledge about the fundamental behavior of asphaltene in high-pressure CO2 conditions.
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13.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zobov V.E., Lundin A.A.
Заглавие : Effect of intramolecular interaction on Time Growth of Second Moment of Multiple-Quantum NMR in Solids
Коллективы : "Resonances in Condensed Matter", International Conference
Место публикации : Int. Conf. "Resonances in Condensed Matter": Book of abstracts. - 2011. - С. Th06
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova E. A., Iskhakov R. S., Stolyar S. V., Komogortsev S. V., Chekanova L. A., Maltsev V. K., Kalinin Y. E., Sitnikov A. V.
Заглавие : Exchange interaction in the Co-SiO2 nanocomposite films
Место публикации : TRENDS IN MAGNETISM. - 2011. - Vol. 168-169. - С. 265-268. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.265
Ключевые слова (''Своб.индексиров.''): exchange coupling parameter--ferromagnetic resonance--granular composite films--cobalt--exchange coupling--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--magnetic resonance measurement--nanocomposite films--nanocomposites--nuclear magnetic resonance--resonance--silicon compounds--spin waves--cobalt--exchange coupling--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--magnetic resonance measurement--magnetism--nanocomposite films--nuclear magnetic resonance--spin fluctuations--spin waves--co content--coupling parameters--dispersion relations--granular composite films--magnetic measurements--nanogranulars--nmr studies--structural state--granular composites--nano-granular--standing spin waves--composite films--composite films
Аннотация: The properties of Co-SiO2 nanogranular composite films, containing a Co volume fraction ranging from 0.3 to 0.8, have been characterized by means of magnetic measurements, NMR study, and ferromagnetic resonance. Thermal decrease of CoX(SiO2)100-X magnetization follows the T3/2 law and allows to estimate the exchange interaction constant A. With growing nominal Co content the transitions from granular to continuous structural state at 36% Co are registered by FMR measurements. The spectrum of standing spin-wave has been detected in the perpendicular experiment configuration for films with the Co content above 52 vol. %. It is found that the type of the dispersion relation of spin waves in Co-SiO2 composite films is affected by the exchange coupling fluctuations.
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15.

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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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : CHERKASOV B. I., MOSKVICH Y. N., SUKHOVSKII A. A., DAVIDOVICH R. L.
Заглавие : F-19 NMR-STUDY OF INTERNAL MOTIONS IN A NEW SUPERIONIC FAMILY, M2ZRF6 AND M2HFF6
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1988. - Vol. 30, Is. 6. - P1652-1661. - ISSN 0367-3294
Примечания : Cited References: 14
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Matsulev A. N., Buznik V. M., Livshits A. I., Fedorov P. P., Sobolev B. P.
Заглавие : F-19-NMR study of the structure of SR0.75ND0.25F2.25 solid electrolyte
Место публикации : Fiz. Tverd. Tela. - 1987. - Vol. 29, Is. 11. - P.3247-3252. - ISSN 0367-3294
Примечания : Cited References: 14
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Falaleev O. V., Falaleeva L. G.
Заглавие : Cross-singular dips in the NMR absorption line of polycrystals with isolated spin pairs
Место публикации : JETP Letters. - 1998. - Vol. 68, Is. 1. - P.101-106. - ISSN 0021-3640, DOI 10.1134/1.567828
Примечания : Cited References: 21
Предметные рубрики: F-19 NMR
Аннотация: Cross-singular dips at the center of the spectra of polycrystals of Fake systems, i.e., systems containing well-isolated pair groupings, are obtained by numerical calculations of the NMR absorption line for a 10-spin (I=1/2) model. The physical reason for such dips is the behavior of the flip-flop component of the interpair dipole-dipole interactions ("6/5 factor"). Cases of experimental manifestation of cross-singular dips are noted. (C) 1998 American Institute of Physics.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : SUKHOVSKII A. A., KRIGER A. I., MOSKVICH Y. N., Lundin A. G.
Заглавие : Ferroelectric phase-transition study in potassium trihydroselenite by Se-77 high-precision NMR method
Место публикации : Fiz. Tverd. Tela. - 1980. - Vol. 22, Is. 3. - P.914-917. - ISSN 0367-3294
Примечания : Cited References: 11
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyanchuk I. O., Bushinsky M. V., Sikolenko V., Efimov V., Volkov N. V., Tobbens D. M., Ritter C., Raveau B.
Заглавие : Ferromagnetism in single-valent manganites
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 619. - P.719-725. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.08.236. - ISSN 1873-4669
Примечания : Cited References: 46. - The authors would like to thank J.B. Goodenough for the fruitful discussion. This work has been supported by Belarusian Republican Foundation for Fundamental Research (Grant F14R-040).
Предметные рубрики: PHASE-SEPARATION
DOPED MANGANITES
DOUBLE EXCHANGE
DIFFRACTION
OXIDES
NMR
Ключевые слова (''Своб.индексиров.''): magnetically ordered materials--solid state reactions--exchange and superexchange--magnetic measurements--neutron diffraction
Аннотация: Structural and magnetization measurements have been performed on the La0.7Sr0.3Mn0.85 Nb 0.15 - x 5 + Mg x 2 + O3 stoichiometric compounds. With rise of the Mg2+ content the formal oxidation state manganese increases from +3 ( x = 0 ) up to +3.55 ( x = 0.15 ) . The compositions with 0 ⩽ x ≤ 0.08 undergo a structural transition from rhombohedral to orthorhombic symmetry below room temperature whereas x = 0.1 and x = 0.15 compounds are rhombohedral down to 2 K. The structural parameters evidence that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The Mg-free compound is ferromagnetic with the Curie point of around 150 K and a magnetic moment of 3.1 μ B /Mn. The substitution of Nb5+ with Mg2+ leads to a gradual weakening of the ferromagnetic component while in the x = 0.15 compound A-type antiferromagnetic short-range order is stabilized in spite of macroscopic R 3 ¯ c symmetry. All the compositions show insulating behavior. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder induced by Nb5+ and Mg2+ ions leads to suppression of ferromagnetism.
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