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1.

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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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S.
Заглавие : Phase-transitions and distortions of the structure in the family of crystals related to alpha-k2so
Место публикации : Kristallografiya. - 1993. - Vol. 38, Is. 1. - P.128-139. - ISSN 0023-4761; Crystallogr. Rep.
Примечания : Cited References: 38
Предметные рубрики: X-RAY
EXPECTED STRUCTURES
A2BX4 COMPOUNDS
TEMPERATURE
(NH4)2BEF4
CHEMISTRY
DISORDER
SYMMETRY
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Vereshchagin, Sergey N., Sterkhova I. V., Atuchin V. V.
Заглавие : The cis-trans isomer transformation, spectroscopic and thermal properties of Li, Na, K 1,3-diethyl-2-thiobarbiturate complexes
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : Polyhedron: PERGAMON-ELSEVIER SCIENCE LTD, 2015. - Vol. 85. - P.493-498. - ISSN 0277-5387, DOI 10.1016/j.poly.2014.09.011
Примечания : Cited References:42. - The study has been carried out within the public task of the Ministry ofEducation and Science of the Russian Federation for research engineeringat the Siberian Federal University in 2014. V.V.A. is partly supportedby the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CRYSTAL-STRUCTURE
2-THIOBARBITURIC ACID
STRUCTURAL-CHARACTERIZATION
HYDROGEN-BOND
DIFFRACTION
THIOBARBITURATE
CHEMISTRY
NETWORKS
SPECTRA
SERIES
Ключевые слова (''Своб.индексиров.''): 1,3-diethyl-2-thiobarbituric acid--alkali ions--x-ray diffraction--infrared spectroscopy--thermal analysis
Аннотация: Three new complexes of 1,3-diethyl-2-thiobarbituric acid (C8H11N2O2S, HDETBA) with Li+, Na+, K+ alkali ions were synthesized. The complexes have been prepared by neutralization of 1,3-diethyl-2-thiobarbituric acid with the corresponding metal hydroxide in aqueous solution. The colorless crystals have been investigated using X-ray single crystal and powder techniques and characterized by differential scanning calorimetry, thermogravimetry and infrared spectroscopy. The compounds of MDETBA with M = Li and M = Na crystallize in the monoclinic lattice with a = 10.678(1) Å, b = 7.2687(9) Å, c = 13.202(2) Å, β = 108.841(2)°, Z = 4, V = 969.8(2) Å3, S.G. P21/n and a = 10.534(2) Å, b = 7.604(1) Å, c = 14.186(1) Å, β = 108.964(4)°, Z = 4, V = 1074.6(3) Å3, S.G. P21/n, respectively. Сompound KDETBA crystallizes in the orthorhombic lattice with a = 4.2541(6) Å, b = 14.739(2) Å, c = 16.635(3) Å, Z = 4, V = 1043.1(3) Å3, S.G. P212121. In Li(I) and Na(I) complexes, the DETBA− ion is in cis-configuration and, in the K(I) complex, this ion is in trans-configuration. The reason for the transformation from cis- to trans-configuration has been rationalized.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molokeev M. S., Golovnev N. N., Vereshchagin S. N., Atuchin V. V.
Заглавие : Crystal structure, spectroscopic and thermal properties of the coordination compounds M(1,3-diethyl-2-thiobarbiturate) M = Rb+, Cs+, Tl+ and NH4+
Место публикации : Polyhedron: Elsevier, 2015. - Vol. 98. - P.113-119. - ISSN 0277-5387, DOI 10.1016/j.poly.2015.05.048
Примечания : Cited References: 43. - The study was carried out within the public task of the Ministry of Education and Science of the Russian Federation for research engineering of the Siberian Federal University in 2015. V.V.A. is grateful to the Ministry of Education and Science of the Russian Federation for financial support of the investigation.
Предметные рубрики: 2-THIOBARBITURIC ACID
THIOBARBITURIC ACID
1,3-DIETHYL-2-THIOBARBITURIC ACID
HYDROGEN-BOND
COMPLEXES
DIFFRACTION
CHEMISTRY
NETWORKS
LIGAND
SERIES
Ключевые слова (''Своб.индексиров.''): 1,3-diethyl-2-thiobarbituric acid--alkali ion thallium(i) and ammonium cations--coordination compounds--thermal analysis--x-ray diffraction
Аннотация: Four new compounds of 1,3-diethyl-2-thiobarbituric acid (C8H11N2O2S, Hdetba) with Rb+, Cs+, Tl+ and NH4+ ions were prepared by Hdetba neutralization with the metal carbonates or ammonium hydroxide in aqueous solution. The colorless crystals have been investigated using X-ray diffraction techniques, differential scanning calorimetry, thermogravimetry and infrared spectroscopy. The coordination compounds of MDetba with M = Rb, Cs and Tl crystallize in the orthorhombic space group P212121, but compound NH4Detba crystallizes in the triclinic space group P1¯. The MDetba structures were compared at the molecular and supramolecular levels. The Detba- ion in the NH4+ compound forms conformer (A) with two diethyl groups on one side of the ion ring, whereas the Detba- ion in the Rb(I), Cs(I) and Tl(I) compounds forms conformer (B) with two diethyl groups on different sides of the ring. The results of IR spectroscopy and thermal analysis are consistent with the X-ray data. © 2015 Elsevier Ltd.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tarakina N. V., Tyutyunnik A. P., Bazuev G. V., Vasiliev A. D., Gould C., Nikolaenko I. V., Berger I. F.
Заглавие : Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba7Li1.75Mn3.5O15.75 with Mn4+/Mn5+ charge distribution
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2015. - Vol. 44, Is. 42. - P.18527-18535. - ISSN 1477-9226, DOI 10.1039/c5dt01528f
Примечания : Cited References: 40. - The authors regret a spelling mistake in the surname of one of authors. The surname given as ‘Vasilev’ should be ‘Vasiliev’N.V.T. acknowledges funding by the Bavarian Ministry of Sciences, Research and the Arts. X-ray powder diffraction studies were carried out at the Center for collective use "X-ray structure analysis" at the Institute of Solid State Chemistry, Ural Branch of RAS (Ekaterinburg, Russia)
Предметные рубрики: Magnetic-properties
Chemistry
Phases
Аннотация: Ba7Li1.75Mn3.5O15.75 is a new hexagonal perovskite whose crystal structure has elements typical for the layered hexagonal perovskites and quasi-one-dimensional oxides, hence representing a new polytype. It has been synthesized via a solid-state microwave route. The crystal structure was solved using a combination of X-ray and neutron diffraction data, which show that Ba7Li1.75Mn3.5O15.75 crystallizes in a hexagonal unit cell with parameters a = 5.66274(2) A and c = 16.7467(1) A (V = 465.063(4) A3), with one formula unit, and can be described as columns of face-shared octahedra occupied by Mn4+ and Li+ cations and vacancies along the c axis separated in the ab plane by barium atoms. Every sixth layer, the coordination of Mn5+ and Li+ changes to tetrahedral. Additional local ordering of manganese and lithium atoms among cationic sites leading to the formation of a rhombohedral supercell has been observed by scanning transmission electron microscopy.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kartashev A. V., Gorev M. V., Bogdanov E. V., Flerov I. N., Laptash N. M.
Заглавие : Thermal properties and phase transition in the fluoride, (NH4)3SnF7
Место публикации : J. Solid State Chem. - 2016. - Vol. 237. - P.269-273. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2016.02.027
Примечания : Cited References: 18. - This study was partially supported by the Russian Foundation for Basic Research (RFBR), research Project no. 15-02-02009a.
Предметные рубрики: Heat-capacity
Chemistry
Ключевые слова (''Своб.индексиров.''): phase transition--fluorides--heat capacity--entropy--thermal expansion--high pressure
Аннотация: Calorimetric, dilatometric and differential thermal analysis studies were performed on (NH4)3SnF7 for a wide range of temperatures and pressures. Large entropy (δS0=22 J/mol K) and elastic deformation (δ(ΔV/V)0=0.89%) jumps have proven that the Pa-3虠Pm-3m phase transition is a strong first order structural transformation. A total entropy change of ΔS0=32.5 J/mol K is characteristic for the order-disorder phase transition, and is equal to the sum of entropy changes in the related material, (NH4)3TiF7, undergoing transformation between the two cubic phases through the intermediate phases. Hydrostatic pressure decreases the stability of the high temperature Pm-3m phase in (NH4)3SnF7, contrary to (NH4)3TiF7, characterised by a negative baric coefficient. The effect of experimental conditions on the chemical stability of (NH4)3SnF7 was observed. © 2016 Elsevier Inc.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Lesnikov M. K., Atuchin V. V.
Заглавие : First outer-sphere 1,3-diethyl-2-thiobarbituric compounds [M(H2O)6](1,3-diethyl-2-thiobarbiturate)2·2H2O (M = Co2+, Ni2+): Crystal structure, spectroscopic and thermal properties
Место публикации : Chem. Phys. Lett.: Elsevier, 2016. - Vol. 653. - P.54-59. - ISSN 00092614 (ISSN), DOI 10.1016/j.cplett.2016.04.059
Примечания : Cited References: 50. - The study was carried out within the public task of the Ministry of Education and Science of the Russian Federation for research engineering of the Siberian Federal University in 2015-2016. V.V. A. is grateful to the Ministry of Education and Science of the Russian Federation for the financial support of the investigation. X-ray data were obtained with use the analytical equipment of Krasnoyarsk Center of collective use of SB RAS.
Предметные рубрики: Thiobarbituric acid complexes
Transition-metal-complexes; 2-thiobarbituric acid; hydrogen-bond
2-thiobarbituric acid
Hydrogen-bond
Chemistry
Transformation
Diffraction
Ligand
Series
Copper
Ключевые слова (''Своб.индексиров.''): 1,3-diethyl-2-thiobarbituric acid--nickel(ii)--cobalt(ii)--coordination compound--x-ray diffraction--infrared spectroscopy--thermal analysis
Аннотация: Two new d-element compounds, [Co(H2O)6](Detba)2·2H2O (1) and [Ni(H2O)6](Detba)2·2H2O (2) (HDetba - 1,3-diethyl-2-thiobarbituric acid) were synthesized and characterized by single-crystal and powder X-ray diffraction analysis, TG-DSC and FT-IR. Structural analysis revealed that (1) and (2) are discrete structures, in which M2+ ion (M = Co, Ni) is six-coordinated by water molecules and it forms an octahedron. The outer-sphere Detba- ions and H2O molecules participate in O-H?(O/S) intermolecular hydrogen bonds which form the 2D layer. Thermal decomposition includes the stage of dehydration and the following stage of oxidation of Detba- with a release of CO2, SO2, H2O, NH3 and isocyanate gases. © 2016 Elsevier B.V. All rights reserved.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Bondarev V. S., Flerov I. N., Maglione M., Simon A., Sciau P., Boulos M., Guillemet-Fritsch S.
Заглавие : Thermal expansion, polarization and phase diagrams of Ba1-yBi2y/3Ti1-xZrxO3 and Ba1-yLayTi1-y/4O3 compounds
Коллективы : Russian Foundation for Basic Research [07-02-00069]; Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools [NSh-1011.2008.2]
Разночтения заглавия :авие SCOPUS: Thermal expansion, polarization and phase diagrams of Ba 1-yBi2y/3Ti1-xZrxO3 and Ba1-yLayTi1-y/4O3 compounds
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2009. - Vol. 21, Is. 7. - Ст.75902. - С. P. - ISSN 0953-8984, DOI 10.1088/0953-8984/21/7/075902
Примечания : Cited References: 28. - This work was supported by the Russian Foundation for Basic Research ( project no. 07-02-00069) and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools ( project no. NSh-1011.2008.2).
Предметные рубрики: HEAT-CAPACITY
CERAMICS
BA(TI1-XZRX)O-3
FERROELECTRICS
BEHAVIOR
BATIO3
BATI0.65ZR0.35O3
CONDUCTIVITY
PEROVSKITES
CHEMISTRY
Ключевые слова (''Своб.индексиров.''): barium--dielectric properties--lanthanum--phase diagrams--polarization--thermal stress--zirconium--ceramic compositions--root mean squares--temperature ranges--temperature-dependent measurements--thermal expansion co-efficient--thermal-expansion properties--thermal expansion
Аннотация: The thermal expansion properties of the ceramic compositions Ba1-yLayTi1-y/4O3 (y = 0.0, 0.026, 0.036, 0.054) and Ba1-yBi2y/3Ti1-xZrxO3 (y = 0.10; x = 0.0, 0.04, 0.05, 0.10, 0.15) were determined in the temperature range 120-700 K. We report the temperature- dependent measurements of the strain, thermal expansion coefficient and the magnitude of root mean square polarization. The results obtained are discussed together with the data on the structure and dielectric properties.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vasilchenko D., Vorob'eva S., Tkachev S., Baidina I. A., Belyaev A., Korenev S., Solovyov L., Vasiliev A. D.
Заглавие : Rhodium(III) speciation in concentrated nitric acid solutions
Коллективы : Russian Foundation for Basic Research [16-03-00549 A]; Ministry for Education and Science of the Russian Federation
Место публикации : Eur. J. Inorg. Chem.: Wiley-VCH Verlag, 2016. - Vol. 2016, Is. 23. - P.3822-3828. - ISSN 1434-1948, DOI 10.1002/ejic.201600523. - ISSN 1099-0682(eISSN)
Примечания : Cited References:31. - This work was supported by the Russian Foundation for Basic Research (grant number 16-03-00549 A). D. V. thanks the Ministry for Education and Science of the Russian Federation for the award of a President of the Russian Federation for Young Scientists Fellowship.
Предметные рубрики: MAGNETIC-RESONANCE
FISSION PLATINOIDS
AQUEOUS-SOLUTIONS
PT-195 NMR
RH(III)
SPECTROSCOPY
CHEMISTRY
DISSOCIATION
PLATINUM(IV)
COMPLEXES
Ключевые слова (''Своб.индексиров.''): rhodium--nmr spectroscopy--nitrates
Аннотация: The interaction of rhodium(III) aqua ions with nitrate ions in 3–16 m nitric acid solutions has been studied by 103Rh and 15N NMR and Raman spectroscopy. The mononuclear complexes [Rh(H2O)6–n(NO3)n]3–n (n = 1–4) were found to be the only form of rhodium(III) existing in the solutions with the metal concentration in the range 0.2–1.3 m. The dynamics of the H2O → NO3– substitution process was studied at 80 °C. An increase in the average number of nitrate groups bonded to rhodium with increasing concentration of nitric acid was also determined. The fine crystalline salt Rb4trans-[Rh(H2O)2(NO3)4][Rh(NO3)6] was obtained by solvothermal concentration of the rhodium nitric acid solution on addition of rubidium nitrate. The structure of the salt was solved by the powder X-ray diffraction method, with monodentate coordination of nitrato ligands found for both the [Rh(NO3)6]3– and trans-[Rh(H2O)2(NO3)4]– anions.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kremneva A. M., Fedorov A. V., Bulavchenko O. A., Knyazev Yu. V., Saraev A. A., Yakovlev V. A., Kaichev V. V.
Заглавие : Effect of calcination temperature on activity of Fe2O3-Al2O3 nanocomposite catalysts in CO oxidation
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [17-73-20157]; National center of investigation of catalysts" at Boreskov Institute of Catalysis
Место публикации : Catal. Lett. - 2020. - Vol. 150. - P.3377-3385. - ISSN 1011-372X, DOI 10.1007/s10562-020-03250-8. - ISSN 1572-879X(eISSN)
Примечания : Cited References: 31. - This work was supported by the Russian Science Foundation (Grant No. 17-73-20157). The experiments were performed using facilities of the shared research center "National center of investigation of catalysts" at Boreskov Institute of Catalysis. The authors thank A.Yu. Gladky for the TPR measurements and Z.S. Vinokurov for the XRD measurements.
Предметные рубрики: MOSSBAUER
SPECTROSCOPY
CHEMISTRY
IRON
XPS
ADSORPTION
OXYGEN
FE
Аннотация: Nanocomposite Fe–Al oxide catalysts were prepared by the melting of iron and aluminum nitrates with the subsequent calcination in air at different temperatures. It was found that the catalysts calcined at 450 °C are more active in the oxidation of CO than the catalysts calcined at 700 °C. X-ray diffraction and X-ray photoelectron spectroscopy showed that all the catalysts consist of hematite, α-Fe2O3 nanoparticles, and Al2O3 in an amorphous state. Iron oxide is the active component, which provides the oxidation of CO, while alumina is a texture promoter. The increase in the calcination temperature leads to a minor increase in the average size of hematite nanoparticles and an insignificant decrease in the specific surface area. Kinetic measurements showed that the oxidation of CO over the Fe–Al catalysts calcined at 450 and 700 °C proceeds with the activation energy of 61–69 and 91 kJ/mol, respectively. This means that the low-temperature and high-temperature catalysts contain different active species. Temperature-programmed reduction with CO indicated that the decrease in the calcination temperature improves the reducibility of the Fe-Al nanocomposites. According to 57Fe Mössbauer spectroscopy, the low-temperature catalysts contain hydrated iron oxides (acagenite and ferrihydrite) and a significant amount of highly defective hematite, which is absent in the high-temperature catalyst. These species can provide the enhanced activity of the low-temperature catalysts in the oxidation of CO.
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