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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Orlov Yu. S., Bushinsky M. V., Solovyov L. A., Vereshchagin S. N., Gavrilkin, S. Yu, Tsvetkov, A. Yu, Gorev M. V., Novikov S. V., Mantytskaya O. S., Ovchinnikov S. G.
Заглавие : Structural, magnetic, electronic, and dilatation properties of the ordered solid solutions Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-03-00017]; RFBRRussian Foundation for Basic Research (RFBR) [18-52-00017, F18R-119]; BRFFR [18-52-00017, F18R-119]; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory [18-42-243004, SB RAS V.45.3.3]
Место публикации : J. Alloy. Compd. - 2020. - Vol. 830. - Ст.154629. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2020.154629. - ISSN 1873-4669(eISSN)
Примечания : Cited References: 44. - The work was financially supported by Russian Foundation for Basic Research (grant No. 19-03-00017); RFBR and BRFFR as a part of scientific project No. 18-52-00017 and project F18R-119; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: "New thermoelectric materials based on multi-scale spatially inhomogeneous substituted rare-earth cobalt oxides and the Ruddlesden-Popper phases " project No. 18-42-243004, Project of Basic Research SB RAS V.45.3.3.
Предметные рубрики: LN(1-X)SR(X)COO(3-DELTA) LN
COBALTATE PEROVSKITES
Аннотация: Single-phase samples of the layered perovskite-like cobalt oxides Ln0.2Sr0.8CoO3-δ (Ln = Sm, Gd, Dy) with the same oxygen nonstoichiometry index δ = 0.37 ± 0.01 were synthesized. All samples are characterized by a tetragonal unit cell with the space group I4/mmm. The structural, magnetic, electric transport and dilatation properties of the obtained samples are investigated. The studied samples are characterized by two anomalies in magnetic properties, a high-temperature maximum near Тm = 350 К with magnetic field hysteresis below Tm, and a diffuse peak in the intermediate temperature range, which shifts with ionic radius decrease of the rare-earth element to higher temperatures. The high-temperature maxima of the magnetic susceptibility correlate with anomalies in thermal expansion, heat capacity and the features in the temperature dependences of the electrical resistivity, pointing to a strong relationship between the structural, magnetic and electronic degrees of freedom. The given comparative analysis of the experimental data of various substituting rare-earth elements with the same oxygen nonstoichiometry has been carried out for the first time.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Shishkina N. N., Bayukov O. A., Kirik N. P., Solovyov L. A., Zhizhaev A. M., Rabchevsky E. V., Anshits A. G.
Заглавие : Cation Distribution in the Composite Materials of the CaFe2O4-α-Fe2O3 Series
Коллективы : Russian Foundation for Basic Research; Government of the Krasnoyarsk Krai; Krasnoyarsk Regional Science Foundation [18-42-243011]; UMNIK program
Место публикации : J. Struct. Chem. - 2019. - Vol. 60, Is. 5. - P.763-771. - ISSN 0022-4766, DOI 10.1134/S0022476619050081. - ISSN 1573-8779(eISSN)
Примечания : Cited References: 25. - The study was performed with the financial support of the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Krai, the Krasnoyarsk Regional Science Foundation within the project No. 18-42-243011 "The effect of the composition and the defective structure of CaFe2O4 based "core-shell" composite materials on their electronic and catalytic properties" and the UMNIK program.
Предметные рубрики: PD/P-TYPE CAFE2O4
OXYGEN
CONDUCTIVITY
Аннотация: Structured composite materials CaFe2O4-α-Fe2O3 (α-Fe2O3 content is 2–82 wt.%) are obtained with the method of solid-phase synthesis at 1000 °C. The phase composition of the samples is studied using powder X-ray diffraction. It is shown that the content of CaFe2O4 and α-Fe2O3 phases changes linearly, depending on the composition of the starting material. The scanning electron microscopy data indicate the formation of a two-phase system α-Fe2O3-CaFe2O4. The Mössbauer spectroscopy data at room temperature testify the formation of cationic iron vacancies in the CaFe2O4 crystal structure in the absence of α-Fe2O3 structural defects. Cationic vacancies can be formed during the synthesis in the atmosphere of air.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Kazak N. V., Orlov Yu. S., Vereshchagin S. N., Gavrilkin, S. Yu., Tsvetkov, A. Yu., Gorev M. V., Veligzhanin A. A., Trigub A. L., Troyanchuk I. O., Ovchinnikov S. G.
Заглавие : Structural, Magnetic, and Thermodynamic Properties of Ordered and Disordered Cobaltite Gd0.1Sr0.9CoO3 – δ
Коллективы : Russian Foundation for Basic Research [17-02-00826, 16-02-00507, 18-52-00017 Bel_a]; Russian Federation [SP-1844.2016.1]; Ministry of Education and Science of the Russian Federation [RFMEFI61917X0007]
Место публикации : J. Exp. Theor. Phys. - 2019. - Vol. 128, Is. 4. - P.630-640. - ISSN 1063-7761, DOI 10.1134/S1063776119020171. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research (grant nos. 17-02-00826, 16-02-00507, and 18-52-00017 Bel_a) and by the Council on Grants of the President of the Russian Federation (SP-1844.2016.1). X-ray spectra were recorded using the equipment of a unique scientific facility Kurchatov Synchrotron Radiation Source financed by the Ministry of Education and Science of the Russian Federation (project ID RFMEFI61917X0007).
Предметные рубрики: PROFILE REFINEMENT
PHASE-TRANSITION
OXYGEN SORPTION
PEROVSKITE
Аннотация: The effect of cationic and anionic orderings on the crystal structure and magnetic properties of substituted rare-earth cobaltites Gd0.1Sr0.9CoO3 – δ was studied using X-ray diffraction, measurement of XANES spectra, and magnetic and thermodynamic characteristics. The effects of ordering cause a decrease in symmetry to tetragonal and a distortion of the coordination octahedra of CoO6. Anomalous magnetic and thermodynamic quantities are observed at 260 and 360 K, respectively, for disordered and ordered samples. The XANES spectra measured at the CoK edge did not reveal a noticeable shift in the absorption edge compared with the spectrum of original GdCoO3. This suggests that the charge compensation process is associated not only with a change in the electronic state of cobalt ions, but also with the emergence of holes in the 2p states of oxygen.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisenko, Yu. G., Sal'nikova E. I., Basova S. A., Molokeev M. S., Krylov A. S., Aleksandrovsky A. S., Oreshonkov A. S., Atuchin V. V., Volkova S. S., Khritokhin N. A., Andreev O. V.
Заглавие : Synthesis of samarium oxysulfate Sm2O2SO4 in the high-temperature oxidation reaction and its structural, thermal and luminescent properties
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-02-00754, 18-32-20011]; Russian Science FoundationRussian Science Foundation (RSF) [19-42-02003]
Место публикации : Molecules. - 2020. - Vol. 25, Is. 6. - Ст.1330. - ISSN 1420-3049(eISSN), DOI 10.3390/molecules25061330
Примечания : Cited References: 56. - This research was funded by the Russian Foundation for Basic Research (Grants 18-02-00754, 18-32-20011) and Russian Science Foundation (project 19-42-02003).
Предметные рубрики: RARE-EARTH SULFATES
SPECTROSCOPIC PROPERTIES
OXYGEN-STORAGE
LN
LA
Аннотация: The oxidation process of samariumoxysulfide was studied in the temperature range of 500–1000 °C. Our DTA investigation allowed for establishing the main thermodynamic (∆Hºexp = −654.6 kJ/mol) and kinetic characteristics of the process (Ea = 244 kJ/mol, A = 2 × 1010). The enthalpy value of samarium oxysulfate (ΔHºf (Sm2O2SO4(monocl)) = −2294.0 kJ/mol) formation was calculated. The calculated process enthalpy value coincides with the value determined in the experiment. It was established that samarium oxysulfate crystallizes in the monoclinic symmetry class and its crystal structure belongs to space group C2/c with unit cell parameters a = 13.7442 (2), b = 4.20178 (4) and c = 8.16711 (8)Å, β = 107.224 (1)°, V = 450.498 (9)Å3, Z = 4. The main elements of the crystalline structure are obtained and the cation coordination environment is analyzed in detail. Vibrational spectroscopy methods confirmed the structural model adequacy. The Sm2O2SO4 luminescence spectra exhibit three main bands easily assignable to the transitions from 4G5/2 state to 6H5/2, 6H7/2, and 6H9/2 multiplets.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shubin A. A., Kovalskii V. Y., Ruzankin S. P., Zilberberg I. L., Parmon V. N., Tomilin F. N., Avramov P. V.
Заглавие : The FeIV-O• oxyl unit as a key intermediate in water oxidation on the FeIII-hydroxide: DFT predictions
Место публикации : Int. J. Quantum Chem. - 2021. - Vol. 121, Is. 10. - Ст.e26610. - ISSN 00207608 (ISSN), DOI 10.1002/qua.26610
Примечания : Cited References: 21. - Aleksandr A. Shubin, Igor L. Zilberberg, and Valentin N. Parmon acknowledge the support of Russian Foundation for Basic Research under grant No. 15-29-01275. Viktor Yu. Kovalskii acknowledges the support of Russian Foundation for Basic Research under grant No. 18-33-00932. Calculations have been performed at the Siberian Supercomputer Centre SB RAS
Аннотация: The O-O coupling process in water oxidation on the gamma FeOOH hydroxide catalyst is simulated by means of density functional theory using model iron cubane cluster Fe4O4(OH)4. A key reactive intermediate is proposed to be the HO-FeIV-O• oxyl unit with terminal oxo radical. The “initial” vertex FeIII(OH) moiety forms this intermediate at the calculated overpotential of 0.93 V by adding one water molecule and withdrawing two proton–electron pairs. The O-O coupling goes via water nucleophilic attack on the oxyl oxygen to form the O-O bond with a remarkably low barrier of 11 kcal/mol. This process is far more effective than alternative scenario based on direct interaction of two ferryl FeIV-O sites (with estimated barrier of 36 kcal/mol) and is comparable with the coupling between terminal oxo center and three-coordinated lattice oxo center (12 kcal/mol barrier). The process of hydroxylation of terminal oxygen inhibits the O-O coupling. Nevertheless, being more effective for ferryl oxygen, the hydroxylation in fact enhances selectivity of the O-O coupling initiated by the oxyl oxygen.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S., Dudnikov V. A., Orlov Yu. S., Solovyov L.
Заглавие : Tetragonal to cubic transition of Sr0.8Dy0.2CoO3-δ and oxygen mobility: TG-DSC-XRD study
Место публикации : J. Alloys Compd. - 2021. - Vol. 860. - Ст.158257. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2020.158257
Примечания : Cited References: 35. - This work was conducted within the framework of the budget project (Project No. АААА-А17-117021310222-4) for Institute of Chemistry and Chemical Technology SB RAS using the equipment of Krasnoyarsk Regional Research Equipment Centre of SB RAS and in part was funded by Russian Foundation for Basic Research (projects 19-03-00017), RFBR and BRFBR (project 18-52-00017), Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science (project 18-42-243004)
Аннотация: Processes of ordering (d-o) and disordering (o-d) of Sr2+/Dy3+ cations in a single-phase Sr0.8Dy0.2CoO3-δ was investigated by TG-DSC and XRD as a function of heating/cooling rate (β = 2,10,20,50,99 K min−1 and ~50 K/s) in 20% O2-Ar flow. According to DSC data the interconversion of disordered cubic (c) and ordered tetragonal (t) structure appears at 1276–1328 K as a first-order phase transition; the temperature and enthalpy of o-d transformation have only slight dependence on β whereas the characteristics of reversed d-o process vary greatly with cooling rate. XRD powder patterns of all samples showed no indications of a simultaneous presence of c+t domains, pointing to a single phase composition (c or t). It was suggested that the observed behavior is a consequence of two simultaneous interconnected processes of A-sublattice melting and cation/ (anion vacancy) ordering. A rarely used novel TG-DSC method based on variable gas phase composition was utilized to study properties of mobile oxygen over Sr0.8Dy0.2CoO3-δ samples. It was shown that the appearance of tetragonal phase reduces both oxygen mobility and its bonding energy, the latter decreasing substantially only at high degree of Sr2+/Dy3+ ordering.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kovel E. S., Sachkova A. S., Vnukova N. G., Churilov G. N., Knyazeva E. M., Kudryasheva N. S.
Заглавие : Antioxidant Activity and Toxicity of Fullerenols via Bioluminescence Signaling: Role of Oxygen Substituents
Место публикации : Int. J. Mol. Sci. - 2019. - Vol. 20, Is. 9. - Ст.2324. - ISSN 14220067 (ISSN) , DOI 10.3390/ijms20092324
Примечания : Cited References: 74. - This work was supported by PRAN-32, Program: 'Nanostructures: physics, chemistry, biology, technological basis'; RFBR 18-29-19003; RFBR-Krasnoyarsk Regional Foundation 18-44-240004, Tomsk Polytechnic University CE Program.
Аннотация: Fullerenols are nanosized water-soluble polyhydroxylated derivatives of fullerenes, a specific allotropic form of carbon, bioactive compounds, and perspective basis for drug development. Our paper analyzes the antioxidant activity and toxicity of a series of fullerenols with different number of oxygen substituents. Two groups of fullerenols were under investigation: (1) C60Oy(OH)(x), C60,70Oy(OH)(x), where x+y = 24-28 and (2) C60,70Oy(OH)(x), Fe0,5C60Oy(OH)(x), Gd@C82Oy(OH)(x), where x+y = 40-42. Bioluminescent cellular and enzymatic assays (luminous marine bacteria and their enzymatic reactions, respectively) were applied to monitor toxicity in the model fullerenol solutions and bioluminescence was applied as a signaling physiological parameter. The inhibiting concentrations of the fullerenols were determined, revealing the fullerenols' toxic effects. Antioxidant fullerenol' ability was studied in solutions of model oxidizer, 1,4-benzoquinone, and detoxification coefficients of general and oxidative types (D-GT and D-OxT) were calculated. All fullerenols produced toxic effect at high concentrations (0.01 g L-1), while their antioxidant activity was demonstrated at low and ultralow concentrations (0.001 g L-1). Quantitative toxic and antioxidant characteristics of the fullerenols (effective concentrations, concentration ranges, D-GT, and D-OxT) were found to depend on the number of oxygen substituents. Lower toxicity and higher antioxidant activity were determined in solutions of fullerenols with fewer oxygen substituents (x+y ⋍ 24-28). The differences in fullerenol properties were attributed to their catalytic activity due to reversible electron acceptance, radical trapping, and balance of reactive oxygen species in aqueous solutions. The results provide pharmaceutical sciences with a basis for selection of carbon nanoparticles with appropriate toxic and antioxidant characteristics. Based on the results, we recommend, to reduce the toxicity of prospective endohedral gadolinium-fullerenol preparations Gd@C82Oy(OH)(x), decreasing the number of oxygen groups to x+y ⋍ 24-28. The potential of bioluminescence methods to compare toxic and antioxidant characteristics of carbon nanostructures were demonstrated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sachkova A. S., Kovel E. S., Churilov G. N., Stom D. I., Kudryasheva N. S.
Заглавие : Biological activity of carbonic nano-structures—comparison via enzymatic bioassay
Место публикации : J. Soils Sed. - 2019. - Vol. 19, Is. 6. - P.2689–2696. - ISSN 14390108 (ISSN) , DOI 10.1007/s11368-018-2134-9
Примечания : Cited References: 38. - This work was supported by the state budget allocated to the fundamental research at the Russian Academy of Sciences, project 0356-2017-0017; PRAN-32, Program: “Nanostructures: physics, chemistry, biology, technological basis.” Study of ROS involvement to antioxidant activity of humic substances was supported by the Russian Science Foundation, grant 16-14-10115.
Аннотация: Purpose: The aim of the work is to compare the biological activity of carbonic nano-structures of natural and artificial origination, namely, humic substances (HS) and fullerenols. Materials and methods: The representative of the fullerenol group, С60Оy(OH)x where у + x = 20–22, was chosen. Enzyme-based luminescent bioassay was applied to evaluate toxicity and antioxidant properties of HS and fullerenol (F); chemiluminescent luminol method was used to study a content of reactive oxygen species (ROS) in the solutions. Toxicity of the bioactive compounds was evaluated using effective concentrations ЕС50; detoxification coefficients DOxT were applied to study and compare antioxidant activity of the compounds. Antioxidant activity and ranges of active concentrations of the bioactive compounds were determined in model solutions of organic and inorganic oxidizers—1,4-benzoquinone and potassium ferricianide. Results and discussion: Values of ЕС50 revealed higher toxicity of HS than F (0.005 and 0.108 g L−1, respectively); detoxifying concentrations of F were found to be lower. Antioxidant ability of HS was demonstrated to be time-dependent; the 50-min preliminary incubation in oxidizer solutions was suggested as optimal for the detoxification procedure. On the contrary, F’ antioxidant effect demonstrated independency on time. Antioxidant effect of HS did not depend on amphiphilic characteristics of the media (values of DOxT were 1.3 in the solutions of organic and inorganic oxidizers), while this of F was found to depend: it was maximal (DOxT = 2.0) in solutions of organic oxidizer, 1,4-benzoquinone. Conclusions: Both HS and F demonstrated toxicity and low-concentration antioxidant ability; however, quantitative characteristics of their effects were different. The differences were explained with HS polyfunctionality, higher ability to decrease ROS content, non-rigidity, and diffusion restrictions in their solutions. Antioxidant effect of the bioactive compounds was presumably attributed to catalytic redox activity of their π-fragments. The paper demonstrates a high potential of luminescent enzymatic bioassay to study biological activity of nano-structures of natural and artificial origination.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chepkasov I. V., Visotin M. A., Kovaleva E. A., Manakhov A. M., Baidyshev V. S., Popov Z. I.
Заглавие : Stability and electronic properties of PtPd nanoparticles via MD and DFT calculations
Коллективы : Russian Foundation for Basic Research (RFBR) [17-42-190308-r]; Foundation for Assistance to Small Innovative Enterprises (FASIE) [0033625, 0033639]; Ministry of Education and Science of the Russian Federation (the government contract to Siberian Federal University) [16.1455.2017/PCh]
Место публикации : J. Phys. Chem. C. - 2018. - Vol. 122, Is. 31. - P.18070-18076. - ISSN 1932-7447, DOI 10.1021/acs.jpcc.8b04177
Примечания : Cited References: 62. - The authors are grateful to Vladislav A. Kalyuzhny for the assistance with the computational resources. The research is carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University and resources of the Center for the Information and Computing of Novosibirsk State University. The work was supported by the Russian Foundation for Basic Research (RFBR no. 17-42-190308-r) and Foundation for Assistance to Small Innovative Enterprises (FASIE) (Project no. 0033625). E.A.K. would also like to thank the Ministry of Education and Science of the Russian Federation (the government contract to Siberian Federal University, grant no. 16.1455.2017/PCh) and the Foundation for Assistance to Small Innovative Enterprises (FASIE) (Project no. 0033639).
Предметные рубрики: OXYGEN REDUCTION REACTION
CORE-SHELL NANOPARTICLES
GAS-PHASE
Аннотация: The structural as well as electronic properties of PtPd nanoparticles (NPs) were investigated by using molecular dynamics simulations and density functional theory calculations. A wide range of NPs of different sizes (from 1.5 to 4 nm), structures (core–shell, alloy, Janus), and compositions were taken into consideration. It was shown that PtPd NPs of less than ∼2.0 nm are prone to structural transformations to icosahedral (Ih) shape, regardless of their initial structure and composition. On the other hand, for NPs of size ∼2.5 nm, the increase of temperature up to 700–900 K leads to structural changes only for compositions close to 40% Pt, which corresponds to energetic minimum for Pt@Pd NPs. The Ih form of Pd@Pt NPs with monolayer thickness of Pt on the surface appears to have the most negatively charged surface which makes this kind of NPs the best candidate for catalysis application.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Orlov Yu. S., Dudnikov V. A., Platunov M. S., Gorev M. V., Velikanov D. A., Kazak N. V., Gavrilkin S. Yu., Solov’ev L. A., Veligzhanin A. A., Vereshchagin S. N., Ovchinnikov S. G.
Заглавие : Low-temperature Schottky anomalies and the magnetic state of the p electrons of oxygen in substituted Gd0.4Sr0.6CoO3 – δ cobaltites
Место публикации : J. Exp. Theor. Phys. - 2018. - Vol. 126, Is. 2. - P.217-223. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776118020036
Примечания : Cited References: 29. - This work was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, and Krasnoyarsk Territory Foundation for the Support of Scientific and Research Activity (project nos. 16-42-240413, 16-43-240505); the Council on Grants at the President of the Russian Federation (project nos. SP-1844.2016.1, SP-938.2015.5, NSh-7559.2016.2); and the Russian Foundation for Basic Research (project nos. 17-02-00826, 16-02-00507, 16-32-60049).
Ключевые слова (''Своб.индексиров.''): rare earths--single crystals--specific heat--temperature distribution--x ray absorption
Аннотация: The XANES spectra (X-ray absorption near-edge spectra) at the K edge of Co and the L3 edge of Gd in polycrystalline Gd0.4Sr0.6CoO3 – δ rare-earth oxides with an ordered and disordered distribution of Gd3+ and Sr2+ cations over the A sites in the crystal lattice are measured. The results of XANES measurements do not reveal a noticeable shift in the absorption edge with increasing Sr concentration as compared to the GdCoO3 parent composition. The measured temperature dependences of the heat capacity of polycrystalline ordered and disordered samples and a single-crystal ordered Gd0.4Sr0.6CoO2.85 sample exhibit two Schottky anomalies. These anomalies are thought to be related to the high-spin state of the Co3+ ions in the pyramidal environment caused by oxygen deficiency and to the magnetic state of oxygen p electrons induced by the doping-assisted generation of a hole in the 2p state. The absence of a noticeable shift in the absorption edge and the presence of two Schottky anomalies support the fact that the charge state of cobalt remains unchanged in the compounds under study.
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Knyazev Yu. V., Dudnikov V. A., Kazak N. V., Platunov M. S., Solovyov L. A., Verechschagin S. N., Burkov A. T., Novikov S. V.
Заглавие : Electronic states of the iron ions in the oxygen deficient perovskite Gd0.2Sr0.8FeO3-δ
Коллективы : Мёссбауэровская спектроскопия и её применения, международная конференция, Mössbauer Spectroscopy and Applications, International Conference, Южный федеральный университет, МИРЭА-Российский технологический университет, Российская академия наук, Институт кристаллографии им. А.В. Шубникова РАН, Федеральный научно-исследовательский центр "Кристаллография и фотоника" РАН, Московский государственный университет им. М.В. Ломоносова
Место публикации : Мёссбауэровская спектроскопия и её применения: сб. материалов XV международной конференции. - Ростов-на-Дону, 2018. - С. 45. - ISBN 978-5-9275-2831-8
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Юмашев, Владимир Витальевич, Кирик, Надежда Павловна, Шишкина, Нина Николаевна, Князев, Юрий Владимирович, Жижаев, Анатолий Михайлович, Соловьев, Леонид Александрович
Заглавие : Состав, структура и реакционная способность при восстановлении водородом композиционных материалов системы α-Fe2O3–CaFe2O4
Место публикации : Журнал СФУ. Химия. - 2019. - Т. 12, Вып. 1. - С. 54-72. - ISSN 1998-2836, DOI 10.17516/1998-2836-0108; J. Sib. Fed. Univ. Chem. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 37
Предметные рубрики: CHEMICAL LOOPING GASIFICATION
OXYGEN CARRIER
PARTIAL OXIDATION
Аннотация: В работе изучены композиционные материалы системы α-Fe2O3-CaFe2O4, полученные методом высокотемпературного твердофазного синтеза из оксидов Са и Fe(III) с вариацией мольного отношения СаО/Fe2O3 от 0.15 до 1.00. Материалы охарактеризованы методами рентгеновской дифракции (РФА), сканирующей электронной микроскопии с системой энергодисперсионного микроанализа (СЭМ-ЭДС) и синхронного термического анализа (СТА) в режиме термопрограммируемого восстановления водородом (H2-ТПВ). СЭМ-ЭДС - исследование образцов выявило формирование сложной микроструктуры материала по типу «ядро-оболочка» с фазой гематита в качестве «ядра». H2-ТПВ образцов позволило установить, что с увеличением содержания фазы CaFe2O4 (от 33.4 до 97.5 мас. %) наблюдается снижение вклада низкотемпературных форм решеточного кислорода в областях 350-510 °С (до 2.6 раза) и 510-650 °С (до 1.7 раза) и рост вклада высокотемпературной формы кислорода в интервале 650-900 °С (до 2 раз). На основе оценки подвижности решеточного кислорода высказано предположение о перспективности использования полученных композиционных материалов с содержанием фазы CaFe2O4 более 55.2 мас. % в качестве носителей кислорода в химических циклических процессах получения синтез-газа.In this paper, α-Fe2O3–CaFe2O4 composite materials obtained by high-temperature solid-phase synthesis from Ca and Fe (III) oxides with varying molar ratio CaO/Fe2O3 in the range 0.15-1.00 were investigated. The materials are characterized by Х-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDS) and simultaneous thermal analysis (STA) in the hydrogen temperature-programmed reduction mode (H2-TPR). SEM-EDS studies of the specimens were revealed a formation of the “core-shell” type complex microstructure of material with the hematite phase as the “core”. H2-TPR of the specimens allowed to establish a decrease of the contribution of low-temperature forms of lattice oxygen in areas of 350-510 °С (up to 2.6 times) and 510-650 °С (up to 1.7 times), and the growth of the contribution of the high-temperature oxygen form in the range of 650-900 °С (up to 2 times) with an increase in the content of the phase CaFe2O4 from 33.4 to 97.5 wt. %. Relying on the assessment of lattice oxygen mobility, it was suggested, that the samples with content of CaFe2O4 phase more than 55.4 wt. % are promising for use as oxygen carriers in chemical looping processes of syngas production.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Orlov Yu. S., Fedorov A. S., Solovyov L., Vereshchagin S., Burkov A. T., Novikov S., Ovchinnikov S. G.
Заглавие : Effect of oxygen nonstoichiometry on electrical conductivity and thermopower of Gd0.2Sr0.8FeO3-δ ferrite samples
Место публикации : Materials. - 2019. - Vol. 12, Is. 1. - Ст.74. - ISSN 19961944 (ISSN), DOI 10.3390/ma12010074
Примечания : Cited References: 24
Аннотация: The behavior of the resistivity and thermopower of the Gd0.2Sr0.8FeO3−δ ferrite samples with a perovskite structure and the sample stability in an inert gas atmosphere in the temperature range of 300–800 K have been examined. It has been established that, in the investigated temperature range, the thermoelectric properties in the heating‒cooling mode are stabilized at δ ≥ 0.21. It is shown that the temperature dependencies of the resistivity obtained at different δ values obey the activation law up to the temperatures corresponding to the intense oxygen removal from a sample. The semiconductor‒semiconductor electronic transitions accompanied by a decrease in the activation energy have been observed with increasing temperature. It is demonstrated that the maximum thermoelectric power factor of 0.1 µW/(cm·K2) corresponds to a temperature of T = 800 K.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Верещагин, Сергей Николаевич, Дудников, Вячеслав Анатольевич, Орлов, Юрий Сергеевич
Заглавие : Применение ТГ/ДСК-анализа c программированным составом газовой фазы для изучения фазового перехода порядок-беспорядок в нестехиометрическом Sr-Dy-кобальтате
Место публикации : J. Sib. Fed. Univ. Chem. - 2018. - Vol. 11, Is. 4. - P.507-517. - ISSN 1998-2836, DOI 10.17516/1998-2836-0095; Журн. СФУ. Химия. - ISSN 2313-6049(eISSN)
Примечания : Библиогр.: 17. - Исследование выполнено при финансовой поддержке Российского фонда фундаментальных исследований, Правительства Красноярского края, Красноярского краевого фонда науки в рамках научного проекта No 18-42-243004 и проекта фундаментальных исследований СО РАН V.45.3.3.
Предметные рубрики: PEROVSKITE
OXYGEN
Ключевые слова (''Своб.индексиров.''): перовскит--порядок-беспорядок--фазовый переход--тг--дск--perovskite--order-disorder--phase transition--tg--dsc
Аннотация: Методом термического анализа (ТГ/ДСК) в условиях постоянного и программированного состава газовой фазы изучено влияние скорости закалки на полноту перехода кубического разупорядоченного нестехиометрического перовскита (I) Sr(0.8)Dy(0.2)CoO(3-d) в тетрагональную модификацию (II) с упорядоченным расположением катионов Sr/Dy и анионных вакансий, а также взаимосвязь степени превращения I в II с количеством мобильного кислорода и его энергетическими характеристиками. Показано, что фазовое превращение протекает как фазовый переход первого рода, процесс образования структуры II контролируется кинетическими факторами, а использование скоростей охлаждения 3-99 К/мин позволяет получить образцы, формально соответствующие 98-30 % превращению I в II; при этом как количество подвижного кислорода, так и энтальпия его удаления из образца нелинейно зависят от полноты перехода I в II.For the first time a method of TG/DSC analysis under constant and variable gas phase composition was applied to reveal interconnection between quenching ramp rates and degree of phase transformation of cubic nonstoichiometric disordered perovskite (I) Sr(0.8)Dy(0.2)CoO(3-d) to tetragonal structure (II) with ordered Sr/Dy cations and anion vacancies. It was shown that the transformation is a first order phase transition and the ordering process is kinetically controlled. Based on the experimental transition enthalpy it was found that a formal conversion degree of I to II was 98-30% under cooling ramp rates 3-99 K/min. Non-linear relationship between the completeness of I-to-II transformation and mobile oxygen characteristics (content and the enthalpy of O-removal) was demonstrated.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kicheeva A. G., Sushko E. S., Bondarenko L. S., Kydralieva K. A., Pankratov D. A., Tropskaya N. S., Dzeranov A. A., Dzhardimalieva G. I., Zarrelli M., Kudryasheva N. S.
Заглавие : Functionalized magnetite nanoparticles: Characterization, bioeffects, and role of reactive oxygen species in unicellular and enzymatic systems
Место публикации : Int. J. Mol. Sci. - 2023. - Vol. 24, Is. 2. - Ст.1133. - ISSN 16616596 (ISSN), DOI 10.3390/ijms24021133. - ISSN 14220067 (eISSN)
Примечания : Cited References: 125. - This research was funded by Russian Science Foundation, N 22-73-10222
Аннотация: The current study evaluates the role of reactive oxygen species (ROS) in bioeffects of magnetite nanoparticles (MNPs), such as bare (Fe3O4), humic acids (Fe3O4-HA), and 3-aminopropyltriethoxysilane (Fe3O4-APTES) modified MNPs. Mössbauer spectroscopy was used to identify the local surrounding for Fe atom/ions and the depth of modification for MNPs. It was found that the Fe3O4-HA MNPs contain the smallest, whereas the Fe3O4-APTES MNPs contain the largest amount of Fe2+ ions. Bioluminescent cellular and enzymatic assays were applied to monitor the toxicity and anti-(pro-)oxidant activity of MNPs. The contents of ROS were determined by a chemiluminescence luminol assay evaluating the correlations with toxicity/anti-(pro-)oxidant coefficients. Toxic effects of modified MNPs were found at higher concentrations (10−2 g/L); they were related to ROS storage in bacterial suspensions. MNPs stimulated ROS production by the bacteria in a wide concentration range (10−15–1 g/L). Under the conditions of model oxidative stress and higher concentrations of MNPs (10−4 g/L), the bacterial bioassay revealed prooxidant activity of all three MNP types, with corresponding decay of ROS content. Bioluminescence enzymatic assay did not show any sensitivity to MNPs, with negligible change in ROS content. The results clearly indicate that cell-membrane processes are responsible for the bioeffects and bacterial ROS generation, confirming the ferroptosis phenomenon based on iron-initiated cell-membrane lipid peroxidation.
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17.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Velikanov D. A., Romanova O. B.
Заглавие : Ferromagnetism induced by oxygen vacancies in mullite Bi2Fe4O9
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 1, Sect.: Low dimensional magnetism. - Ст.C.O1. - P.327-328. - ISBN 978-5-94469-051-7
Примечания : Cited References: 3
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Velikanov D. A., Molokeev M. S., Romanova O. B., Shabanov A. V.
Заглавие : Enhancement of ferromagnetism and ferroelectricity by oxygen vacancies in mullite Bi2Fe4O9 in the Bi2(Sn0.7Fe0.3)2O7-x matrix
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 559. - Ст.169530. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169530
Примечания : Cited References: 47
Аннотация: A new bismuth pyrostannate-based composite Bi2(Sn0.7Fe0.3)2O7-x/Bi2Fe4O9 (BSFO/BFO) has been obtained by the solid-state synthesis. Temperature dependences of the magnetic hysteresis and remanent magnetization and the nonlinear field dependence of the magnetization for the Bi2Fe4O9 antiferromagnet have been established. A temperature of the formation of canted sublattices in the antiferromagnet with the occurrence of a spontaneous moment in mullite has been determined. The mechanism of the electric polarization hysteresis and the temperature dependence of the remanent polarization have been established. It has been shown, that, below the Néel temperature, the dipole polarization is induced by a lone electron pair of bismuth ions. At T TN, the migration polarization is caused by the charge carrier density at the chemical potential. A significant increase in the remanent magnetization of mullite in the bismuth pyrostannate matrix with oxygen vacancies over a value typical of polycrystalline mullite has been established. Remanent magnetization is explained in terms of ferron model.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kirik N., Krylov A. S., Boronin A., Koshcheev S., Solovyov L., Rabchevskii E., Shishkina N., Anshits A.
Заглавие : The relationship between the structural characteristics of α-Fe2O3 catalysts and their lattice oxygen reactivity regarding hydrogen
Место публикации : Materials. - 2023. - Vol. 16, Is. 12: The 15th Anniversary of Materials — Recent Advances in Catalytic Materials. - Ст.4466. - ISSN 19961944 (eISSN), DOI 10.3390/ma16124466
Примечания : Cited References: 63. - This work was conducted within the framework of the budget project for the Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences, Federal Research Center KSC SB RAS, No. FWES–2021–0013
Аннотация: In this paper, the relationship between the structural features of hematite samples calcined in the interval of 800–1100 °C and their reactivity regarding hydrogen studied in the temperature-programmed reaction (TPR-H2) was studied. The oxygen reactivity of the samples decreases with the increasing calcination temperature. The study of calcined hematite samples used X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Raman spectroscopy, and their textural characteristics were studied also. According to XRD results, hematite samples calcined in the temperature range under study are monophase, represented by the α-Fe2O3 phase, in which crystal density increases with increasing calcination temperature. The Raman spectroscopy results also register only the α-Fe2O3 phase; the samples consist of large, well-crystallized particles with smaller particles on their surface, having a significantly lower degree of crystallinity, and their proportion decreases with increasing calcination temperature. XPS results show the α-Fe2O3 surface enriched with Fe2+ ions, whose proportion increases with increasing calcination temperature, which leads to an increase in the lattice oxygen binding energy and a decrease in the α-Fe2O3 reactivity regarding hydrogen.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Васильева, Наталья Дмитриевна, Софронова, Светлана Николаевна, Баринов В. В., Тайник А. В., Трушкина Т. В., Чуракова О. В.
Заглавие : Применение процессного моделирования для интерпретации вариации стабильных изотопов в годичных кольцах деревьев
Колич.характеристики :16 с
Коллективы : РусДендро-2023, Международная дендрохронологическая конференция
Место публикации : Лесотехнич. журн. - 2023. - Т. 13, № 4, Ч. 2. - С. 23-38. - ISSN 22227962 (ISSN), DOI 10.34220/issn.2222-7962/2023.4/15; Forest. Eng. J.
Примечания : Библиогр.: 33. - Исследование выполнено за счет гранта Российского научного фонда № 21-17-00006, (https://rscf.ru/en/project/21-17-00006/)
Аннотация: Ширина годичных колец деревьев и изотопный состав стабильных изотопов углерода (δ13C), кислорода (δ18O) и водорода (δ2H) в целлюлозе годичных колец широко используются для реконструкций условий окружающей среды. Применение моделей, способных описать вариацию стабильных изотопов в годичных кольцах деревьев, представляет собой набор инструментов для интерпретации изменений окружающей среды на экофизиологическом уровне. В данной работе хронологии с погодичным временным разрешением, полученные по стабильным изотопам δ13С, δ18O и δ2H в целлюлозе годичных колец хвойных для региона Дельта реки Маккензи в Канаде (68° 30′ с.ш., 133° 48′ з.д.) для периода с 1901 по 2009 гг., были сопоставлены с модельными расчетами для интерпретации экофизиологического сигнала. При помощи процессной модели (LPX) нам удалось смоделировать δ13С вариацию, значимо коррелирующую с измеренными данными (r = 0.29; p = 0.002) для периода с 1901 по 2009 гг. Модельные расчеты по кислороду и водороду требуют дальнейшего преобразования модельных блоков, в частности, требуют доработки включения источника воды, используемой деревьями, блока оттаивания и промерзания почвы с учетом вечной мерзлоты, а также экспериментальных данных по содержанию δ18O и δ2H в воде.Tree-ring width and stable isotopes (carbon, oxygen, and hydrogen) in tree-ring cellulose are widely used to reconstruct environmental conditions. The application of models capable to describe a variation of stable isotopes in annual tree rings can be a powerful tool for interpretation of environmental changes at the eco-physiological level. In this paper, we modelled carbon (δ13С), oxygen (δ18O), and hydrogen (δ2H) variations at the tree-ring level and compared results with measured data, obtained from the Mackenzie Delta River (68°30′ N, 133°48′ W) for the common period from 1901 to 2009. Using a process-based model (LPX), we were able to simulate carbon isotope values, which significantly (r = 0.29; p = 0.002) correlate with measured carbon isotope values. The model calculations for oxygen and hydrogen require further modifications and improvements, in particular the inclusion of the source of water used by the trees in the Canadian subarctic, as well as δ18O and δ2H in the water.
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