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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Lyubutin I. S., Gavriliuk A. G. , Struzhkin V. V.
Заглавие : Spin crossover and resulting insultor?metal transitions in Mott insulators under high pressure
Коллективы : Совещание по физике низких температур
Место публикации : XXXV Совещание по физике низких температур (НТ-35): тезисы докладов : Черноголовка, 29 сентября - 2 октября 2009 г./ Сов. по физ. низких температур. - С. 85. - ISBN 978-5-94691-384-3
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Александров, Кирилл Сергеевич, Александрова, Инга Петровна, Репета В. С.
Заглавие : Исследование фазовых переходов в триглицинселенате методом ЯКР
Коллективы : International Conference on High Pressure Physics and Technology
Место публикации : Международная конференция по высоким давлениям и технологии
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Александров, Кирилл Сергеевич, Voronov V. N., Vtyurin A. N., Krylov A. S., Molokeev M. S., Pavlovskiy M. S., Goryainov S. V., Lihacheva A. N., Ancharov A. I.
Заглавие : Pressure-indused phase transition in cubic ScF3 crystal
Коллективы : Russia/CIS/Baltic/Japan Symposium on Ferroelectricity
Место публикации : 9th Russai/CIS/Baltic/Japan symposium on ferroelectricity: abstracts book : June 15-19, 2008, Vilnius, Lithuania. - p.116
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zinenko V. I., Pavlovsky M. S.
Заглавие : Lattice dynamics of BiFeO3 under hydrostatic pressure
Коллективы : Russia/CIS/Baltic/Japan Symposium on Ferroelectricity
Место публикации : 9th Russai/CIS/Baltic/Japan symposium on ferroelectricity: abstracts book : June 15-19, 2008, Vilnius, Lithuania. - p.137
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Bogdanov E. V., Fokina V. D., Flerov I. N., Gorev M. V., Vasiliev A. D., Pogoreltsev E. I., Laptash N. M.
Заглавие : Phase transitions in (NH4)2MoO2F4: effect of hydrostatic and chemical pressure
Коллективы : Russia/CIS/Baltic/Japan Symposium on Ferroelectricity
Место публикации : 9th Russai/CIS/Baltic/Japan symposium on ferroelectricity: abstracts book : June 15-19, 2008, Vilnius, Lithuania. - p.139
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bondarev V. S., Mikhaleva E. A., Gorev M. V., Molokeev M. S., Bogdanov E. V., Cherepakhin A. V., Flerov I. N.
Заглавие : Phase transitions, baro- and piezocaloric effects in single crystal and ceramics of ferroelectric NH4HSeO4
Колич.характеристики :10 с
Место публикации : Solid State Sci. - 2024. - Vol. 148. - Ст.107440. - ISSN 12932558 (ISSN), DOI 10.1016/j.solidstatesciences.2024.107440. - ISSN 18733085 (eISSN)
Примечания : Cited References: 45. - The study was supported by the grant of the Russian Science Foundation No. 23-22-10014, Krasnoyarsk Regional Science Foundation, https://rscf.ru/en/project/23-22-10014/
Аннотация: A study of heat capacity, thermal dilatation and sensitivity to hydrostatic and uniaxial pressure was carried out on single-crystal and ceramic samples of NH4HSeO4. The main parameters of low-temperature successive phase transitions B2 (T1) ↔ incommensurate IC (T2) ↔ ferroelectric P1 (T3) ↔ non-ferroelectric did not depend on the type of samples. The behavior of the volumetric strain and the results of direct measurements of T3(p) contributed to the resolution of the longstanding problem associated with the ambiguity of the sign of the corresponding volumetric baric coefficient. The role of thermal expansion anisotropy in the formation of the piezocaloric effect (PCE) near the ferroelectric phase transition at T3 has been studied. Due to the strong difference in the linear baric coefficients, the main contribution to the barocaloric effect (BCE) comes from the inverse intensive and extensive PCE associated with the a-axis. Compared to a single crystal, ceramics demonstrate lower BCE values, which, however, exist in a wider temperature range, which leads to close values of integral caloric parameters. The strong decrease in both BCE and PCE at low-temperature transformations in NH4HSeO4 compared to the ferroelectrics NH4HSO4 and NH4NH4SO4 is associated with a small change in entropy during three low-temperature phase transitions, ΣΔSi = 2.52 J/mol∙K, which is a consequence of a high degree of structural ordering in selenate as a result of a high-temperature transformation at T0 between the superionic and B2 phases, accompanied by a giant change in entropy, ΔS0≈Rln21.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang, Xingyu, Liu, Youquan, Molokeev M. S., Xu, Bohui, Jiang, Xingxing, Lin, Zheshuai
Заглавие : Realizing persistent zero area compressibility over a wide pressure range in Cu2GeO4 by microscopic orthogonal-braiding strategy
Колич.характеристики :6 с
Место публикации : Angew. Chem. Int. Ed. - 2024. - Vol. 63, Is. 7. - Ст.e202318401. - ISSN 14337851 (ISSN), DOI 10.1002/anie.202318401. - ISSN 15213773 (eISSN)
Примечания : Cited References: 24. - The authors would like to acknowledge Zhuohong Yin for useful discussions and experimental time for the 4W2 beamline in the Beijing synchrotron radiation facility (BSRF). This work was supported by the National Scientific Foundations of China (Grants T2222017, 12274425, 22133004, 11974360 and 51890864) and the CAS Project for Young Scientists in Basic Research (YSBR-024). M.S. Molokeev would like to acknowledge support fromthe Ministry of Science and High Education of the Russian Federation (Project No. FSRZ-2023-0006)
Аннотация: Zero area compressibility (ZAC) is an extremely rare mechanical response that exhibits an invariant two-dimensional size under hydrostatic pressure. All known ZAC materials are constructed from units in two dimensions as a whole. Here, we propose another strategy to obtain the ZAC by microscopically orthogonal-braiding one-dimensional zero compressibility strips. Accordingly, ZAC is identified in a copper-based compound with a planar [CuO4] unit, Cu2GeO4, that possesses an area compressibility as low as 1.58(26) TPa-1 over a wide pressure range from ~0 GPa to 21.22 GPa. Based on our structural analysis, the subtle counterbalance between the shrinkage of [CuO4] and the expansion effect from the increase in the [CuO4]-[CuO4] dihedral angle attributes to the ZAC response. High-pressure Raman spectroscopy, in combination with first-principles calculations, shows that the electron transfer from in-plane bonding dx2-y2 to out-of-plane nonbonding dz2 orbitals within copper atoms causes the counterintuitive extension of the [CuO4]-[CuO4] dihedral angle under pressure. Our study provides an understanding on the pressure-induced structural evolution of copper-based oxides at an electronic level and facilitates a new avenue for the exploration of high-dimensional anomalous mechanical materials.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Karpov I.V., Fedorov L. Yu, Abkaryan A.K., Zharkov S. M., Molokeev M. S., Ivanenko A. A., Nemtsev I. V., Irtyugo L.A.
Заглавие : Resistive switching properties of a nanostructured layer of mixed ZrO2 phases obtained in low-pressure arc discharge plasma
Колич.характеристики :9 с
Место публикации : Vacuum. - 2024. - Vol. 227. - Ст.113375. - ISSN 0042207X (ISSN), DOI 10.1016/j.vacuum.2024.113375. - ISSN 18792715 (eISSN)
Примечания : Cited References: 34. - The work was performed with a support of the grant of the Russian Science Foundation (Project No. 24-29-00374, https://rscf.ru/project/24-29-00374/)
Аннотация: The controlled vacuum-arc synthesis of zirconium dioxide (ZrO2) nanoparticles is considered, which makes it possible to regulate the percentage ratio of the monoclinic and tetragonal phases. The samples were characterized using XRD analysis, SEM, HRTEM analysis, FT-IR analysis, TG/DTA analysis and EPR spectroscopy. It has been established that the formation of the tetragonal phase is associated with the formation of a large number of oxygen vacancies formed due to high-speed quenching of nanoparticles. Reducing the operating gas pressure in a vacuum chamber from 180 Pa to 30 Pa makes it possible to obtain nanoparticles up to 2 nm in size. The synthesized ZrO2 nanoparticles do not contain foreign impurities and when heated, the weight loss is up to 7 %. The process of local resistive switching in the contact of an atomic force microscope (AFM) probe to a nanostructured ZrO(2-x) layer on a conducting substrate has been studied. Cyclic current-voltage characteristics demonstrate the existence of stable states of high and low resistance, switched by changing the polarity of the applied voltage. The coexistence of the m- and t-ZrO2 phases (and the resulting oxygen nonstoichiometry in the interboundary regions) provides conditions for the formation/destruction of a filament from oxygen vacancies, which determine the conductivity of the dielectric in the LRS state.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Goryainov S., Krylov A. S., Borodina U., Likhacheva A., Krylova S. N., Seryotkin Yu., Bogdanov N., Vtyurin A. N., Grishina S.
Заглавие : Raman study of decomposition of Na-bearing carbonates in water fluid at high P–T parameters
Колич.характеристики :12 с
Место публикации : Spectrochim. Acta - A: Mol. Biomol. Spectrosc. - 2024. - Vol. 322. - Ст.124801. - ISSN 13861425 (ISSN), DOI 10.1016/j.saa.2024.124801. - ISSN 18733557 (eISSN)
Примечания : Cited References: 74. - Authors thank V.S. Shevchenko, A.F. Shatskiy, A.G. Sokol and A.V. Golovin for fruitful discussion. We acknowledge I.N. Kupriyanov for discussion and measurements of FTIR spectra of the samples. This work was carried out within the framework of the Russian Federation state assignment of the Sobolev Institute of Geology and Mineralogy SB RAS (state registration number: 122041400176-0) and A.K., S.K and A.V. thanks for support the Russian Federation state assignment of Kirensky Institute of Physics, Federal Research Center KSC SB RAS (state registration number: FWES-2024-0003). Work partially supported by the Russian Foundation for Basic Researches (RFBR-21-55-14001 ANF a grant). Equipment and devices of the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS” were used for Raman experiments at high P–T conditions
Аннотация: The study of Na-carbonates stability and their transformations in aqueous carbonate fluid under high P–T conditions is relevant from the point of view of the understanding geochemical processes of the Na-assisted carbon circulation in the Earth’s crust and subduction zones. In situ Raman study of Na-bearing carbonate-water-Fe-metal system in diamond anvil cell (DAC) at high P–T conditions revealed that carbonates decompose with abiogenic formation of formates and other organic compounds that differs from behavior of carbonates in dry system. XRD and FTIR methods have been used additionaly to determine the phase composition. Na-bearing carbonates (nahcolite NaHCO3, shortite Na2Ca2(CO3)3 and cancrinite Na7Ca[(CO3)1.5Al6Si6O24]·2H2O) in aqueous fluid decompose to form simple carbonates and formates (as dominant organic molecules) at moderate P–T parameters (above ∼0.2 GPa, 200°C). Our experimental results directly confirm the hypothesis of Horita and Berndt (Science, 1999) about possible yield of organic formates in the carbonate-water-metal system. Nahcolite NaHCO3 in aqueous fluid in the presence of Fe metal decomposes into anhydrous phases: natrite γ-Na2CO3, siderite, magnetite (due to dissolution of Fe steel gasket), Na-formate and likely organic molecular crystalline solvate of Na-formate and methyl formate. Shortite decays into anhydrous phases: aragonite CaCO3, Na-Ca-formates and an amorphous phase. Cancrinite decomposes to unidentified carbonate-alumonosilicate phases, Na-Ca-formates and unknown organic molecular crystal. Magnetite is also formed in this system due to dissolution of Fe steel gasket used in DAC. The present study provides a new insight in processes of abiogenic formation of organic matter from carbonates in the crust and upper mantle.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Жандун, Вячеслав Сергеевич, Казак, Наталья Валерьевна
Заглавие : Спиновые переходы в людвигите Co2FeBO5 под высоким давлением: ab initio исследование
Коллективы : "Новое в магнетизме и магнитных материалах", международная конференция, Научный совет по физике конденсированных сред РАН, МИРЭА - Российский технологический университет, Московский государственный университет им. М.В. Ломоносова, Магнитное общество России
Место публикации : Новое в магнетизме и магнитных материалах: сборник трудов XXV международной конференции/ прогр. ком.: Р. С. Исхаков, С. Г. Овчинников [и др.]. - 2024. - Секция 7 [Сборник 7]: Магнитные фазовые переходы и критические явления. - С. 14-16. - ISBN 978-5-4465-1869-2
Примечания : Библиогр.: 4. - РНФ, Красноярский краевой фонд науки, грант № 24-12-20012
Аннотация: Новые оксибораты Me2Me’BO5, где Me и Me’ - переходные металлы, привлекают особое внимание как перспективные ферримагнетики [1-4]. Ферримагнетный людвигит Co2FeBO5 является результатом замены диамагнитных ионов Co3+ в людвигите Co3BO5 на магнитный ион Fe3+, что играет решающую роль в зарядовом и магнитном балансе, определяя уникальные электронные и магнитные свойства данного соединения. В настоящей работе исследуется влияние давления на магнитные и электронные свойства людвигита Co2FeBO5 в рамках теории функционала плотности. Расчеты при высоком давлении показывают, что магнитные моменты Fe и Co имеют различное поведение под давлением. Давление оказывает существенное влияние на магнитное состояние атомов Co2 и Fe4, что приводит к резкому уменьшению их магнитных моментов при критическом давлении. В свою очередь магнитные моменты триады Co3-Co1-Co3 испытывают слабое монотонное уменьшение с давлением. Наряду со спиновыми переходами обнаружен коллапс энергетической щели при критическом давлении P=50 ГПа.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N., Zamkova N. G.
Заглавие : Magnetic structure and pressure-induced spin-crossover in Me3B2O6 (Me = Mn, Fe, Co, Ni) kotoites: Representation analysis and DFT calculations
Колич.характеристики :10 с
Место публикации : Comput. Mater. Sci. - 2024. - Vol. 236. - Ст.112859. - ISSN 09270256 (ISSN), DOI 10.1016/j.commatsci.2024.112859. - ISSN 18790801 (eISSN)
Примечания : Cited References: 25. - The study was funded by a grant from the Russian Science Foundation # 22-22-20024 https://rscf.ru/project/22-22-20024/, Krasnoyarsk Regional Fund of Science. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru). VZ thanks Dr. Natalia Kazak and Oksana Draganyuk for help in preparing the manuscript, useful discussions and valuable advices
Аннотация: The magnetic and electronic properties of transition metal borates Me3B2O6 (Me = Mn, Fe, Co, Ni) with kotoite structure have been investigated at ambient and high pressures via a combination of representation analysis and density functional theory (DFT + U) calculations. Several magnetic configurations corresponding to the different irreducible representations have been considered. The total-energy calculations reveal that the magnetic ground state of Me3B2O6 kotoites is composition-dependent. The lowest energy magnetic phase of manganese and nickel kotoites is characterized by the antiferromagnetic ordering of the transition metal magnetic moments along the c- axis and along the b-axis for cobalt and iron kotoites. The magnetic cell of Ni3B2O6 kotoite corresponds to k = (1/2, 0, 1/2) vector and four time larger than the unit cell. The calculated exchange constants indicate the competition between ferromagnetic and antiferromagnetic interactions. At a critical pressure, Me ions undergo a high-spin to low-spin state crossover. This magnetic moments collapse is analyzed in terms of change in electronic structure under pressure.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang, Xingyu, Liu, Youquan, Molokeev M. S., Xu, Bohui, Jiang, Xingxing, Lin, Zheshuai
Заглавие : Realizing persistent zero area compressibility over a wide pressure range in Cu2GeO4 by microscopic orthogonal-braiding strategy
Колич.характеристики :6 с
Место публикации : Angew. Chem. - 2024. - Vol. 136, Is. 7. - Ст.e202318401. - ISSN 00448249 (ISSN), DOI 10.1002/ange.202318401. - ISSN 15213757 (eISSN)
Примечания : Cited References: 24. - The authors would like to acknowledge Zhuohong Yin for useful discussions and experimental time for the 4W2 beamline in the Beijing synchrotron radiation facility (BSRF). This work was supported by the National Scientific Foundations of China (Grants T2222017, 12274425, 22133004, 11974360 and 51890864) and the CAS Project for Young Scientists in Basic Research (YSBR-024). M.S. Molokeev would like to acknowledge support fromthe Ministry of Science and High Education of the Russian Federation (Project No. FSRZ-2023-0006)
Аннотация: Zero area compressibility (ZAC) is an extremely rare mechanical response that exhibits an invariant two-dimensional size under hydrostatic pressure. All known ZAC materials are constructed from units in two dimensions as a whole. Here, we propose another strategy to obtain the ZAC by microscopically orthogonal-braiding one-dimensional zero compressibility strips. Accordingly, ZAC is identified in a copper-based compound with a planar [CuO4] unit, Cu2GeO4, that possesses an area compressibility as low as 1.58(26) TPa-1 over a wide pressure range from ≈0 GPa to 21.22 GPa. Based on our structural analysis, the subtle counterbalance between the shrinkage of [CuO4] and the expansion effect from the increase in the [CuO4]-[CuO4] dihedral angle attributes to the ZAC response. High-pressure Raman spectroscopy, in combination with first-principles calculations, shows that the electron transfer from in-plane bonding dx2-y2 to out-of-plane nonbonding dz2 orbitals within copper atoms causes the counterintuitive extension of the [CuO4]-[CuO4] dihedral angle under pressure. Our study provides an understanding on the pressure-induced structural evolution of copper-based oxides at an electronic level and facilitates a new avenue for the exploration of high-dimensional anomalous mechanical materials.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nikolaev N. S., Isakova V. G., Vnukova N. G., Elesina V. I., Glushenko G. A., Tomashevich Y. V., Churilov G. N.
Заглавие : Synthesis of Ni nanoclusters supported on diamond by plasma technique and their electrochemical properties
Колич.характеристики :6 с
Место публикации : Diam. Relat. Mater. - 2024. - Vol. 142. - Ст.110844. - ISSN 09259635 (ISSN), DOI 10.1016/j.diamond.2024.110844. - ISSN 18790062 (eISSN)
Примечания : Cited References: 35
Аннотация: In this study, particles of synthetic undoped diamond (DN) obtained via the high pressure – high temperature method were coated with a nickel shell using metallic nickel plasma in a two-jet plasma generator with gas vortex and magnetic flux stabilization. Through the use of scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, we observed the formation of a nickel diamond composite with a core-shell structure, where DN serves as the core and Ni nanoclusters form the shell (DN@Ni). The results of voltammetric analysis indicated that DN@Ni, when deposited on a graphite electrode, exhibited significant electrocatalytic activity in the oxidation of methanol and paracetamol in an alkaline electrolyte.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Bogdanov E. V., Laptash N. M.
Заглавие : Chemical pressure as an effective tool for tuning the structural disordering and barocaloric efficiency of complex fluorides (NH4)3MF7 (M: Sn, Ti, Ge, Si)
Колич.характеристики :18 с
Место публикации : J. Phys. D: Appl. Phys. - 2024. - Vol. 57, Is. 17. - Ст.175301. - ISSN 00223727 (ISSN), DOI 10.1088/1361-6463/ad211b. - ISSN 13616463 (eISSN)
Примечания : Cited References: 39. - The study was supported by a Grant from the Russian Science Foundation No. 23-22-00115, https://rscf.ru/project/23-22-00115/
Аннотация: Double fluoride salts (NH4)3M4+F7 (M4+: Sn, Ti, Ge, Si) demonstrate a high efficiency of using chemical pressure as a tool for control and tuning structural ordering/disordering, sensitivity to hydrostatic pressure, successions of the phase transitions, etc and, as a result, for purposeful variation within a wide range of parameters of barocaloric effect (BCE). The conventional and inverse BCEs near the triple points were found on the T − p phase diagrams, combination of which can be used to construct original cooling cycle in narrow temperature and pressure ranges. Reconstructive transformation between two cubic phases, Pm3-m ↔ Pa3-, realized in (NH4)3SnF7 at atmospheric pressure and in (NH4)3TiF7 at p ˃ 0.4 GPa are characterized by rather low thermal hysteresis, δT0 = 1 K, and a great entropy change, ΔSBCE = 110–152 J (kg · K)−1, depending on the size of the central atom. At above 300–350 K, a contribution to BCE associated with the regular thermal expansion of the crystal lattice becomes comparable to entropy and temperature changes under pressure in the region of the phase transitions. An analysis of the absolute, relative and integral barocaloric characteristics of (NH4)3M4+F7 compounds showed their high competitiveness with respect to other barocaloric materials considered as promising solid-state refrigerants.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Bogdanov E. V., Laptash N. M.
Заглавие : The role of chemical pressure in the formation of the structure and barocaloric properties of complex fluorides and oxyfluorides
Колич.характеристики :14 с
Место публикации : Crystallogr. Rep. - 2023. - Vol. 68, Is. 5. - P.765-778. - ISSN 10637745 (ISSN), DOI 10.1134/S1063774523600485. - ISSN 1562689X (eISSN)
Примечания : Cited References: 67
Аннотация: The role of chemical pressure as an effective tool in the processes of formation of initial and distorted (as a result of structural transformations) phases, thermodynamic properties, and direct and inverse barocaloric effects in some complex oxyfluorides and fluorides with octahedral, tetrahedral, and spherical anion and cation groups in the structure has been studied. It is found that, due to the small temperature hysteresis and high baric sensitivity of materials, the maximum values of absolute and integral barocaloric characteristics can be implemented at low pressures. Correspondingly, the temperature range of reversibility of thermodynamic cycles based on fluorides/oxyfluorides as solid-state coolants can be expanded.
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16.

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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Skorobogatov S. A., Wu L. S., Xie T., Shaykhutdinov K. A., Pomjakushina E. V., Podlesnyak A., Nikitin S. E.
Заглавие : Pressure control of the spin reorientation transition in the rare-earth orthoferrite YbFeO3
Колич.характеристики :6 с
Место публикации : Phys. Rev. B. - 2023. - Vol. 108, Is. 5. - Ст.054432. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.108.054432. - ISSN 24699969 (eISSN)
Примечания : Cited References: 31. - This research used resources at the Spallation Neutron Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated by Oak Ridge National Laboratory. Laue x-ray diffraction measurements were conducted at the Center for Nanophase Materials Sciences (Grant No. CNMS2019-R18) at Oak Ridge National Laboratory, which is a DOE Office of Science User Facility. S.E.N. acknowledges financial support from the European Union Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant No. 884104
Аннотация: YbFeO3 is exceptional among the rare-earth orthoferrites for having the lowest spin-reorientation transition (SRT) temperature, TSRT≏8K, which makes it particularly appealing to examine the interplay between noncollinear magnetism of the Fe sublattice and quasi-one-dimensional XXZ effective S=1/2 chains of Yb3+ moments. Our paper focuses on the magnetic dynamics of YbFeO3 using inelastic neutron scattering (INS), at temperatures below and above the SRT, under an applied hydrostatic pressure of 2 GPa, and in magnetic fields up to 4 T. The low-energy zero-field excitation spectrum at ambient pressure and temperatures below the SRT is dominated by a gapped magnon mode of the Yb subsystem at 0.84 meV with a dispersion only in the [00L] direction. Above TSRT, a continuum appears on top of the magnon mode because of temperature population of the magnon band, and the gap decreases to around 0.4 meV. The INS spectra in the magnetic field, both above and below TSRT, are characterized by two well-separated gapped modes. The SRT is clearly visible at low fields B˂1T, but it gradually disappears at higher magnetic fields. The hydrostatic pressure of p=2GPa effectively reduces the transition width, ΔTSRT, and keeps the SRT at higher fields up to B≏3T. We discuss the effect of the applied pressure in the frame of the modified mean-field theory and show that in the vicinity of the TSRT the pressure tunes the fourth-order anisotropy constant that effectively reduces the ΔTSRT.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bogdanov E. V., Pogoreltsev E. I., Gorev M. V., Mel'nikova S. V., Molokeev M. S., Laptash N. M., Flerov I. N.
Заглавие : Effect of the size of the central atom on the stability of crystalline phases in solid solutions (NH4)3TixSn1-xF7
Колич.характеристики :8 с
Место публикации : J. Solid State Chem. - 2023. - Vol. 328. - Ст.124373. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2023.124373. - ISSN 1095726X (eISSN)
Примечания : Cited References: 20. - The study was supported by a grant from the Russian Science Foundation № 23-22-00115, https://rscf.ru/project/23-22-00115/X-ray and dilatometric data and SEM images were obtained using the equipment of the Krasnoyarsk Regional Center for Collective Use of the Federal Research Center — Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences. We are grateful to Dr. A.V. Shabanov for examination of the SEM images
Аннотация: The effect of a change in internal pressure as a result of partial substitution of the central atom on the realization and stability of the initial and distorted crystalline phases in (NH4)3TixSn1-xF7 solid solutions has been studied. It was found that at a Ti concentration in the range of x = 0.15–0.40, the reconstructive transition Pm-3m ↔ Pa-3 is transformed into a sequence of phase transitions Pm-3m ↔ P4/mbm ↔ P4/mnc ↔ Pa-3. In the (NH4)3Ti0.15Sn0.85F7 solid solution, the first-order phase transition between two cubic phases at T0 = 352 K is characterized by a significant volume jump δ(ΔV/V0) ≈ 1 %, comparable with that in (NH4)3SnF7. An increase of the Ti concentration leads to a strong decrease in the stability of the Pm-3m cubic phase: the first tetragonal P4/mbm phase appears in (NH4)3Ti0.4Sn0.6F7 at T0 = 400 K, which proves the existence of the predicted high-temperature cubic phase in (NH4)3TiF7. In solid solutions, a decrease in birefringence and entropy of phase transitions was observed in comparison with the initial compounds with Sn and Ti as central atoms. The role of critical parameters (unit cell volume, temperature, external pressure) in the formation of cubic and distorted phases is discussed.
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19.

Вид документа : Статья из журнала
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Автор(ы) : Zhandun V. S., Draganyuk O. N.
Заглавие : The spin-state transition in ACo2O4 spinels (A = Be, Mg, Ca, Cd, Zn)
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 552. - Ст.169206. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169206
Примечания : Cited References: 51. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects № 19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic Mn+1AXn (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: The magnetic and electronic properties of the Co-based spinel oxides ACo2O4 (A = Be, Mg, Ca, Zn, Cd) were studied within GGA + U approach. It was found that the Co3+ ion is in a low-spin state due to the effect of the crystal field of octahedral symmetry. It is shown that Co3+ ion undergoes a spin-state transition into the high-spin state under the critical pressure of P = −10 GPa – −20 GPa. This pressure-induced spin-state transition is caused by the redistribution of electrons between the t2g- and eg-orbitals arising with increasing interatomic distances. The role of interatomic distances between Co3+ ion and its ligands is discussed. Thin-film form also favors the appearance of a high-spin state of Co3+ ion. At the same critical pressure, there is a sharp increase in the majority spin bandgap and a sharp decrease in the minority spin bandgap. These findings allow manipulating the spin state of Co3+ ions and bandgap width through the pressure or strain arising in thin films.
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20.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Abramova G. M., Boehm M., Schefer J., Piovano A., Knyazev Yu. V., Bayukov O. A., Kubrin S. P.
Заглавие : Magnetic state of FeхMn1-хS, under hydrostatic and chemical pressure
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. 2, Sect. H: Magnetism of strongly correlated electron systems. - Ст.H.P1. - P.79-80. - ISBN 978-5-94469-051-7
Примечания : Cited References: 5. - We acknowledge the beam time used at D1A and IN8 of the Institut Laue–Langevin Grenoble (ILL) and the single instrument ZEBRA at the Swiss Spallation Neutron Source SINQ/PaulScherrer Institut, Villigen PSI. This study was in part supported by the INTAS project no. 06-1000013-9002 and the CRDF-SB RAS project no. RUP1-7054-KR-1, N 16854
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