Главная
Авторизация
Фамилия
Пароль
 

Базы данных


Труды сотрудников ИФ СО РАН - результаты поиска

Вид поиска

Область поиска
в найденном
 Найдено в других БД:Каталог книг и брошюр библиотеки ИФ СО РАН (1)
Формат представления найденных документов:
полныйинформационныйкраткий
Отсортировать найденные документы по:
авторузаглавиюгоду изданиятипу документа
Поисковый запрос: (<.>S=SPECTROSCOPY<.>)
Общее количество найденных документов : 39
Показаны документы с 1 по 10
 1-10    11-20   21-30   31-39 
1.


   
    Antiferromagnetic dichroism in a complex multisublattice magnetoelectric CuB2O4 / K. N. Boldyrev [et al.] // Phys. Rev. Lett. - 2015. - Vol. 114, Is. 24. - Ст. 247210, DOI 10.1103/PhysRevLett.114.247210. - 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.). . - ISSN 0031. - ISSN 1079-7114
   Перевод заглавия: Антиферромагнитный дихроизм в сложном многоподрешеточном магнетоэлектрике CuB2O4
РУБ Physics, Multidisciplinary
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.

Смотреть статью,
Scopus,
WOS,
Смотреть статью,
Читать в сети ИФ
Держатели документа:
RAS, Inst Spect, Moscow 142190, Russia.
RAS, Ioffe Phys Tech Inst, St Petersburg 194021, Russia.
RAS, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Boldyrev, K. N.; Pisarev, R. V.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич; Popova, M. N.; 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]
}
Найти похожие
2.


   
    Antiferromagnetic Resonance and Dielectric Properties of Rare-earth Ferroborates in the Submillimeter Frequency Range / A. M. Kuz'menko [et al.] // J. Exp. Theor. Phys. - 2011. - Vol. 113, Is. 1. - P. 113-120, DOI 10.1134/S106377611105013X. - Cited References: 27. - This work was supported by the Russian Foundation for Basic Research, project no. 10-02-00846. . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
GDFE3(BO3)(4)
   SPECTROSCOPY

   CRYSTAL

Кл.слова (ненормированные):
Antiferromagnetic resonance -- Basic parameters -- Effective anisotropy constant -- Ferroborates -- Ferroics -- Ferromagnetic orderings -- Frequency ranges -- Magnetic interactions -- Magnetoresonance -- Millimeter frequency range -- Rare earth ions -- Submillimeters -- Antiferromagnetic materials -- Crystallography -- Erbium -- Europium -- Ferromagnetic resonance -- Ion exchange -- Magnetic anisotropy -- Magnetic devices -- Magnetic structure -- Permittivity -- Resonance -- Antiferromagnetism
Аннотация: The magnetoresonance and dielectric properties of a number of crystals of a new family of multiferroics, namely, rare-earth ferroborates RFe(3)(BO(3))(4) (R = Y, Eu, Pr, Tb, Tb(0.25)Er(0.75)), are studied in the submillimeter frequency range (nu = 3-20 cm(-1)). Ferroborates with R = Y, Tb, and Eu exhibit permittivity jumps at temperatures of 375, 198, and 58 K, respectively, which are caused by the R32 -> P3(1)2(1) phase transition. Antiferromagnetic resonance (AFMR) modes in the subsystem of Fe(3+) ions are detected in the range of antiferromagnetic ordering (T < T(N) = 30-40 K) in all ferroborates that have either an easy-plane (Y, Eu) or easy-axis (Pr, Tb, Tb(0.25)Er(0.75)) magnetic structure. The AFMR frequencies are found to depend strongly on the magnetic anisotropy of a rare-earth ion and its exchange interaction with the Fe subsystem, which determine the type of magnetic structure and the sign and magnitude of an effective anisotropy constant. The basic parameters of the magnetic interactions in these ferroborates are found, and the magnetoelectric contribution to AFMR is analyzed.

WOS,
Scopus,
Читать в сети ИФ
Держатели документа:
[Kuz'menko, A. M.
Mukhin, A. A.
Ivanov, V. Yu.
Lebedev, S. P.] Russian Acad Sci, Inst Gen Phys, Moscow 119991, Russia
[Kadomtseva, A. M.] Moscow MV Lomonosov State Univ, Moscow 119991, Russia
[Bezmaternykh, L. N.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН
Institute of General Physics, Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991, Russian Federation
Moscow State University, Moscow, 119991, Russian Federation
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Kuz'menko, A. M.; Mukhin, A. A.; Ivanov, V. Y.; Kadomtseva, A. M.; Lebedev, S. P.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич
}
Найти похожие
3.


    Arkhipkin, V. G.
    Electromagnetically induced transparency and controlling the time shape of laser pulses / V. G. Arkhipkin, I. V. Timofeev // Dokl. Phys. - 2005. - Vol. 50, Is. 4. - P. 165-168, DOI 10.1134/1.1922553. - Cited References: 14 . - ISSN 1028-3358
РУБ Mechanics + Physics, Multidisciplinary
Рубрики:
SPECTROSCOPY

WOS,
РИНЦ,
Читать в сети ИФ

Публикация на русском языке Архипкин, Василий Григорьевич. Электромагнитно индуцированная прозрачность и управление временной формой лазерных импульсов [Текст] / В. Г. Архипкин, И. В. Тимофеев // Доклады Академии наук. - 2005. - Т. 401 № 4. - С. 467-470


Доп.точки доступа:
Timofeev, I. V.; Тимофеев, Иван Владимирович; Архипкин, Василий Григорьевич
}
Найти похожие
4.


    Aver'yanov, E. M.
    Local field anisotropy in Langmuir-Blodgett films of cadmium arachidate / E. M. Aver'yanov // Phys. Solid State. - 2011. - Vol. 53, Is. 12. - P. 2492-2494, DOI 10.1134/S1063783411120031. - Cited References: 9 . - ISSN 1063-7834
РУБ Physics, Condensed Matter
Рубрики:
SPECTROSCOPY
Аннотация: Lorentz tensor and local field tensor components for uniaxial Langmuir-Blodgett films of cadmium arachidate from 3 to 100 nm thick on silver, polymethyl methacrylate, and glass substrates have been experimentally determined using the data on the film refractive index dispersion in the visible range. The constraints from below on the mean value and anisotropy of the molecular polarizability caused by the intermolecular interactions in the film have been established.

WOS,
Scopus,
Читать в сети ИФ
Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok 50, Krasnoyarsk 660036, Russian Federation

Доп.точки доступа:
Аверьянов, Евгений Михайлович
}
Найти похожие
5.


    AVERYANOV, E. M.
    POLARIZED LUMINESCENCE SPECTRUM OF IMPURITY LIQUID-CRYSTAL - THE DEGENERATION LIFTED AND RENEWED BY RELAXATION / E. M. AVERYANOV // Zhurnal Eksperimentalnoi Teor. Fiz. - 1993. - Vol. 103, Is. 6. - P. 2018-2038. - Cited References: 45 . - ISSN 0044-4510
РУБ Physics, Multidisciplinary
Рубрики:
RESOLVED FLUORESCENCE DEPOLARIZATION
   UNIAXIAL MOLECULAR SAMPLES

   NEMATIC ORDER PARAMETERS

   EXCITED-STATES

   SPECTROSCOPY

   MEMBRANES

   FLUOROPHORES

   ORIENTATION

   TRANSITION

   DYES

Аннотация: The general molecular-statistical approach is proposed for the analysis or the polarized luminescence spectrum for impurity molecule of an arbitrary symmetry in the nematic liquid crystal matrix. On the particular example of uniaxial molecules the influence of features of the molecular electron structure, orientational statistics, molecular dynamics, and features of the anisotropic intermolecular coupling upon the positions of maxima v(if)(t) of impurity fluorescence polarized bands J(ij)(t) is studied. For the first time it is shown that all these factors significantly affect the degree of spectrum v(ij)(t) degeneration. For t not-equal 0, relaxation of excited impurity molecule subsystem toward the orientational distribution lifts a partial degeneration of spectrum v(ij), occuring at t not-equal 0, and renews partial or total degeneration of spectrum v(ij) in the limit t = infinity. In the lack of the spectrum v(ij) degeneration for t = 0 the relaxation may restore partial degeneration for t not-equal 0 as a function of the features of electron structure of molecules. The results of work explain the familiar experimental data on the number of independent component v(ij) and relation between them, on dependence of v(ij) upon the order of matrix and impurity subsystem, on the mutual relation in the positions of impurity band polarized component in the absorption and fluorescence spectra.

WOS
}
Найти похожие
6.


    AVERYANOV, E. M.
    STATIONARY SPECTRUM OF ADMIXED LIQUID-CRYSTAL POLARIZED FLUORESCENCE / E. M. AVERYANOV // Zhurnal Eksperimentalnoi Teor. Fiz. - 1994. - Vol. 106, Is. 3. - P. 767-779. - Cited References: 29 . - ISSN 0044-4510
РУБ Physics, Multidisciplinary
Рубрики:
LOCAL FIELD
   SPECTROSCOPY

   PARAMETERS

   DYES


WOS
}
Найти похожие
7.


   
    Core-hole localization and ultra-fast dissociation in SF6 / V. Ekholm, G. S. Chiuzbaian, C. Sathe [et al.] // J. Phys. B. - 2020. - Vol. 53, Is. 18. - Ст. 185101, DOI 10.1088/1361-6455/aba204. - Cited References: 36. - This work was supported by the Swedish Research Council (VR). The calculations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC). FG acknowledges support within the Russian Science Foundation (Project No. 16-12-10109) . - ISSN 0953-4075. - ISSN 1361-6455
РУБ Optics + Physics, Atomic, Molecular & Chemical
Рубрики:
X-RAY-EMISSION
   SYMMETRY-BREAKING

   AB-INITIO

   SPECTROSCOPY

   SPECTRA

Кл.слова (ненормированные):
SF6 -- resonant inelastic x-ray scattering -- symmetry selection rules -- ultrafast dynamics -- vibronic couplings
Аннотация: Resonant inelastic x-ray scattering spectra excited at the fluorine K resonances of SF6 have been recorded. While a small but significant propensity for electronically parity-allowed transitions is found, the observation of parity-forbidden electronic transitions is attributed to vibronic coupling that breaks the global inversion symmetry of the electronic wavefunction and localizes the core hole. The dependence of the scattering cross section on the polarization of the incident radiation and the scattering angle is interpreted in terms of local π/σ symmetry around the S–F bond. This symmetry selectivity prevails during the dissociation that occurs during the scattering process.

Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Держатели документа:
Lund Univ, MAX IV Lab, Box 118, SE-22100 Lund, Sweden.
Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden.
Sorbonne Univ, F-75005 Paris, France.
CNRS, LCPMR, F-75005 Paris, France.
Synchrotron SOLEIL, LOrme Merisiers, BP 48, F-91192 Gif Sur Yvette, France.
Ctr Nacl Pesquisa Energia & Mat CNPEM, BR-10000 Campinas, Brazil.
Royal Inst Technol, Sch Biotechnol, Theoret Chem & Biol, S-10691 Stockholm, Sweden.
Siberian Fed Univ, Krasnoyarsk 660041, Russia.
Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.
Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden.

Доп.точки доступа:
Ekholm, V.; Chiuzbaian, G. S.; Sathe, C.; Nicolaou, A.; Guarise, M.; Simon, M.; Jaouen, N.; Luning, J.; Hague, C. F.; Gel'mukhanov, F.; Гельмуханов, Фарис Хафизович; Odelius, M.; Bjorneholm, O.; Rubensson, J-E; Swedish Research Council (VR)Swedish Research Council; Russian Science FoundationRussian Science Foundation (RSF) [16-12-10109]
}
Найти похожие
8.


   
    Crystal and local atomic structure of MgFeBO4,Mg0.5Co0.5FeBO4, and CoFeBO4: effects of Co substitution / N. V. Kazak [et al.] // Phys. Status Solidi B. - 2015. - Vol. 252, Is. 10. - P. 2245-2258, DOI 10.1002/pssb.201552143. - Cited References: 46. - This work has been financed by the MECOM Project MAT11/23791, and DGA IMANA project E-34, Council for Grants of the President of the Russian Federation (project nos. NSh-2886.2014.2, SP-938.2015.5), and Russian Foundation for Basic Research (project nos. 13-02-00958-a, 13-02-00358-a, 14-02-31051-mol-a). The work of one of the coauthors (M.S.P.) was supported by the program of Foundation for promoting the development of small enterprises in scientific and technical sphere ("UMNIK" program). . - ISSN 0370. - ISSN 1521-3951
   Перевод заглавия: Кристаллическая и локальная атомная структура MgFeBO4, Mg0.5Co0.5FeBO4 and CoFeBO4: эффект замещения Со
РУБ Physics, Condensed Matter
Рубрики:
SPIN-GLASS BEHAVIOR
   MAGNETIC WARWICKITES

   SINGLE-CRYSTALS

   PHASE-RELATIONS

   OXYBORATE

   SYSTEM

   SPECTROSCOPY

   ANISOTROPY

   MN2OBO3

   FE2OBO3

Кл.слова (ненормированные):
crystal structure -- XANES -- EXAFS -- magnetic semiconductor -- oxyborate
Аннотация: Single-crystalline MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 have been grown by the flux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction, and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra have been measured at the Fe and Co K-edges over a wide temperature range (6.5– 300 K). The composition, the charge state, and local environ- ment of both Fe and Co atoms have been determined. The effects of Co substitution for Mg on the local structural distortions have been revealed experimentally and the M–O bond anisotropy has been found.
Монокристаллические образцы CoFeBO4 были выращены раствор-расплавным методом. Образцы были охарактеризованы с помощью рентгеноспектрального анализа, рентгеновской дифракции и спектроскопии поглощения рентгеновских лучей. Спектры вблизи K-края поглощения рентгеновского излучения структуры (XANES) и далее рентгеновского поглощения тонкой структуры (EXAFS) были измерены для Fe и Co в широком диапазоне температур (6.5- 300К). Состав, состояние заряда, и локальная положение и Fe и Co атомов были определены. Эффекты замещения Co магнием Mg на местные структурные искажения были выявлены экспериментально и анизотропия связи М-О была найдена.

Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Держатели документа:
Kirensky Institute of Physics, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation
National Research Center Kurchatov Institute, Moscow, Russian Federation
Servicio de Medidas Fi, sicas, Universidad de Zaragoza, Zaragoza, Spain
Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Aragon, CSIC, Universidad de Zaragoza, Zaragoza, Spain
O. O. Galkin Institute for Physics and Engineering, National Academy of Sciences of Ukraine, Donetsk, Ukraine

Доп.точки доступа:
Kazak, N. V.; Казак, Наталья Валерьевна; Platunov, M. S.; Платунов, Михаил Сергеевич; Knyazev, Yu. V.; Князев, Юрий Владимирович; Ivanova, N. B.; Иванова, Наталья Борисовна; Zubavichus, Y. V.; Veligzhanin, A. A.; Vasiliev, A. D.; Васильев, Александр Дмитриевич; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич; Bayukov, O. A.; Баюков, Олег Артемьевич; Arauzo, A.; Bartolome, J.; Lamonova, K. V.; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич
}
Найти похожие
9.


   
    Crystal structure, phase transition and structural deformations in iron borate (Y0.95Bi0.05)Fe3(BO3)4 in the temperature range 90–500 K / E. S. Smirnova [et al.] // Acta Crystallogr. B. - 2018. - Vol. 74. - P. 226-238, DOI 10.1107/S2052520618002962. - Cited References:27. - The following funding is acknowledged: Russian Foundation for Basic Research (award No. 17-02-00766) and Federal Agency of Scientific Organizations (Agreement No 007-GZ/Ch3363/26). . - ISSN 2052-5206
РУБ Chemistry, Multidisciplinary + Crystallography
Рубрики:
HIGH-PRESSURES
   GDFE3(BO3)4

   SPECTROSCOPY

   IFEFFIT

Кл.слова (ненормированные):
rare-earth iron borates -- crystal structure -- structural phase transition -- structural deformations
Аннотация: An accurate X-ray diffraction study of (Y0.95Bi0.05)Fe3(BO3)4 single crystals in the temperature range 90–500 K was performed on a laboratory diffractometer and used synchrotron radiation. It was established that the crystal undergoes a diffuse structural phase transition in the temperature range 350–380 K. The complexity of localization of such a transition over temperature was overcome by means of special analysis of systematic extinction reflections by symmetry. The transition temperature can be considered to be Tstr ≃ 370 K. The crystal has a trigonal structure in the space group P3121 at temperatures of 90–370 K, and it has a trigonal structure in the space group R32 at 375–500 K. There is one type of chain formed by the FeO6 octahedra along the c axis in the R32 phase. When going into the P3121 phase, two types of nonequivalent chains arise, in which Fe atoms are separated from the Y atoms by a different distance. Upon lowering the temperature from 500 to 90 K, a distortion of the Y(Bi)O6, FeO6, B(2,3)O3 coordination polyhedra is observed. The distances between atoms in helical Fe chains and Fe—O—Fe angles change non-uniformly. A sharp jump in the equivalent isotropic displacement parameters of O1 and O2 atoms within the Fe—Fe chains and fluctuations of the equivalent isotropic displacement parameters of B2 and B3 atoms were observed in the region of structural transition as well as noticeable elongation of O1, O2, B2, B3, Fe1, Fe2 atomic displacement ellipsoids. It was established that the helices of electron density formed by Fe, O1 and O2 atoms may be structural elements determining chirality, optical activity and multiferroicity of rare-earth iron borates. Compression and stretching of these helices account for the symmetry change and for the manifestation of a number of properties, whose geometry is controlled by an indirect exchange interaction between iron cations that compete with the thermal motion of atoms in the structure. Structural analysis detected these changes as variations of a number of structural characteristics in the c unit-cell direction, that is, the direction of the helices. Structural results for the local surrounding of the atoms in (Y0.95Bi0.05)Fe3(BO3)4 were confirmed by EXAFS and Mössbauer spectroscopies.

Смотреть статью,
Scopus,
WOS
Держатели документа:
Russian Acad Sci, Fed Sci Res Ctr Crystallog & Photon, Shubnikov Inst Crystallog, Moscow 119333, Russia.
Natl Res Ctr, Kurchatov Inst, Moscow 123182, Russia.
Russian Acad Sci, Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Smirnova, Ekaterina S.; Alekseeva, Olga A.; Dudka, Alexander P.; Artemov, V. V.; Zubavichus, Yan V.; Gudim, I. A.; Гудим, Ирина Анатольевна; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич; Frolov, Kirill V.; Lyubutin, Igor S.; Russian Foundation for Basic Research [17-02-00766]; Federal Agency of Scientific Organizations [007-GZ/Ch3363/26]
}
Найти похожие
10.


   
    Effect of calcination temperature on activity of Fe2O3-Al2O3 nanocomposite catalysts in CO oxidation / A. M. Kremneva, A. V. Fedorov, O. A. Bulavchenko [et al.] // Catal. Lett. - 2020. - Vol. 150. - P. 3377-3385, DOI 10.1007/s10562-020-03250-8. - 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. . - ISSN 1011-372X. - ISSN 1572-879X
РУБ Chemistry, Physical
Рубрики:
MOSSBAUER
   SPECTROSCOPY

   CHEMISTRY

   IRON

   XPS

   ADSORPTION

   OXYGEN

   FE

Кл.слова (ненормированные):
Environmental catalysis -- Nanostructure -- Gasification -- Oxidation -- Mossbauer spectroscopy
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.

Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Держатели документа:
Boreskov Inst Catalysis, Novosibirsk 630090, Russia.
Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Kremneva, A. M.; Fedorov, A. V.; Bulavchenko, O. A.; Knyazev, Yu. V.; Князев, Юрий Владимирович; Saraev, A. A.; Yakovlev, V. A.; Kaichev, V. V.; Russian Science FoundationRussian Science Foundation (RSF) [17-73-20157]; National center of investigation of catalysts" at Boreskov Institute of Catalysis
}
Найти похожие
 1-10    11-20   21-30   31-39 
 

Другие библиотеки

© Международная Ассоциация пользователей и разработчиков электронных библиотек и новых информационных технологий
(Ассоциация ЭБНИТ)