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1.
V. A. Koibaev S. K. Kuklina A. O. Likhacheva Ya. N. Nuzhin 《Mathematical Notes》2017,102(5-6):792-798
It is proved that every elementary carpet of nonzero additive subgroups which is associated with a Chevalley group of a Lie rank exceeding one over a locally finite field coincides, up to conjugation by a diagonal element, with a carpetwhose additive subgroups are equal to some chosen subfield of the ground field. A similar result is obtained for a full matrix carpet (a full net). 相似文献
2.
A. Yu. Likhacheva S. V. Goryainov I. A. Madyukov A. Yu. Manakov A. I. Ancharov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1143-1146
The structural behavior of natural lawsonite CaAl2Si2O7(OH)2 · H2O in aqueous and nonaqueous media (pressure up to 9.5 GPa) has been studied by synchrotron powder diffraction and Raman spectroscopy.
The volume compressibility of lawsonite is found to be similar in both aqueous and nonaqueous media, while irreversible amorphization
is observed only under compression in the aqueous medium to a pressure of about 6 GPa. Along with the observed increase in
framework vibration frequencies, this reveals that the lawsonite structure is unstable when hydrostatic conditions of compression
differ from those provided by crystallization of ice VII in an aqueous medium. 相似文献
3.
A new simplified synthesis of monocrystalline chips of SrB4O7: Sm2+ pressure calibrant, well-suited for the diamond anvil cell (DAC) powder diffraction experiments, is proposed. It consists of ordinary solid-state synthesis of fine-grained SrB4O7: Sm2+ and subsequent annealing near melting temperature. The obtained material was characterized and tested in HP-HT DAC experiment. 相似文献
4.
V. V. Shchennikov S. V. Ovsyannikov A. Yu. Manakov A. Yu. Likhacheva A. I. Ancharov I. F. Berger M. A. Sheromov 《JETP Letters》2006,83(6):228-232
In chambers with diamond anvils, the structure of high-pressure phases of ternary lead tellurides Pb1?x SnxTe (x = 0.29) and Pb1?x MnxTe (x = 0.05) and nonstoichiometric crystals Pb0.55Te0.45, Pb0.45Te0.55 is analyzed by the synchrotron radiation diffraction method at pressures of P up to 14 GPa. The orthorhombic structure of the intermediate high-pressure phase (space group Pnma) is determined for all the samples above 6 GPa. Models of the phase transition in PbTe from the initial rock salt structure to the orthorhombic phase, which constitutes a distorted variant of NaCl, as well as the properties of this phase, are discussed. 相似文献
5.
N. A. Likhacheva A. A. Fatykhov I. B. Abdrakhmanov R. R. Gataullin 《Russian Journal of Organic Chemistry》2007,43(9):1305-1309
Hydroxymercuration-demercuration of N-p-tolysulfonyl-4,4a,9,9a-tetrahydro-3H-carbazoles and N-p-tolyl(or methyl)sulfonyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles leads to the formation of the corresponding N-p-tolylsulfonyl-2,3,4,4a,9,9a-hexahydro-1H-carbazol-2-ols and N-p-tolyl(or methyl)sulfonyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indol-2-ols. The latter are oxidized to 2-oxo derivatives with potassium dichromate. The oxidation of 2-methoxy-8-methyl-N-p-tolylsulfonyl-2,3,4,4a,9,9a-hexahydro-1H-carbazol-1-ol under analogous conditions gives 2-methoxy-8-methyl-N-p-tolysulfonyl-2,3,4,4a,9,9a-hexahydro-1H-carbazol-1-one. 相似文献
6.
N. N. Ovsyuk S. V. Goryainov A. Y. Likhacheva 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(7):778-780
Polycrystalline powder of a diamond–lonsdaleite system from the Popigai impact crater (Siberia) is studied via UV micro-Raman scattering (RS) and X-ray diffraction. A spectrum of pure lonsdaleite is obtained by subtracting two experimental Raman spectra of diamond–lonsdaleite samples with close ratios of diamond and lonsdaleite. The maximum contribution to the difference spectrum is due to the difference between the contribution from lonsdaleite, and not to the change in the bandwidth of the diamond. Deconvolution of the lonsdaleite spectrum allows isolation of all three vibrational modes (E2g, A1g, and E1g) active in the first-order RS, the positions of which agree well with the results from first-principles calculations. 相似文献
7.
S. V. Goryainov A. Yu. Likhacheva N. N. Ovsyuk 《Journal of Experimental and Theoretical Physics》2018,127(1):20-24
We present the results of our study of a polycrystalline diamond–lonsdaleite powder from the Popigai crater (Siberia) using UV micro-Raman scattering and synchrotron X-ray diffraction. By subtracting two experimental Raman spectra of diamond–lonsdaleite samples with a close ratio of the diamond and lonsdaleite fractions, when the maximum contribution to the difference spectrum is related to the difference of the lonsdaleite contributions and not to the change in the diamond band width, we have managed to obtain the spectrum of “pure” lonsdaleite. Its deconvolution has allowed us to identify all three Raman-active vibrational modes E2g, A1g, and E1g whose positions agree well with the results of ab initio calculations. 相似文献
8.
S. V. Goryainov A. S. Krylov A. Yu. Likhacheva A. N. Vtyurin 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(7):804-807
The intermediate phases preceding overhydration are observed by Raman spectroscopy both in scolecite Ca[Al2Si3O10] · 3H2O and in thomsonite NaCa2[Al5Si5O20] · 6H2O upon compression in an aqueous medium. The first intermediate phase of scolecite is attributed to a phase precursor revealed earlier using XRD at pressure of ~1 GPa. The widening of the Raman bands of O-H vibrations caused by the disordering of H2O, which appears after additional water molecules are embedded in the zeolite channels, is typical of this intermediate phase. It is assumed on the basis of the Raman spectroscopy data that scolecite contains second overhydrated and second intermediate phases. 相似文献
9.
S. V. Rashchenko A. Yu. Likhacheva A. D. Chanyshev A. I. Ancharov 《Journal of Structural Chemistry》2012,53(1):43-46
The method of in situ X-ray diffraction with the influence of temperature and pressure on the sample was successfully applied in Siberian Synchrotron and Terahertz Radiation Centre on the experimental station Diffractometry in hard X-rays. High-pressure water-containing lawsonite silicate CaAl2[Si2O7](OH)2·H2O is obtained at 400°C and 25 kbar in a diamond anvil cell during the decomposition of laumontite. In situ diffractometry of the reaction products helps to determine parameters of the unit cell of lawsonite and phase composition of CaO-Al2O3-SiO2-H2O at 400°C and 25 kbar. 相似文献
10.
Aladko EY Ancharov AI Goryainov SV Kurnosov AV Larionov EG Likhacheva AY Manakov AY Potemkin VA Sheromov MA Teplykh AE Voronin VI Zhurko FV 《The journal of physical chemistry. B》2006,110(42):21371-21376
In this work, we present a new, previously unknown type of structure transformation in the high-pressure gas hydrates, which is related to the existence of two different isostructural phases of the sulfur hexafluoride clathrate hydrates. Each of these phases has its own stability field on the phase diagram. The difference between these hydrates consists of partial filling of small D cages by SF(6) molecules in the high-pressure phase; at 900 MPa, about half of small cages are occupied. Our calculations indicate that the increase of population of small cavities is improbable, therefore, at any pressure value, a part of the cavities remains vacant and the packing density is relatively low. This fact allowed us to suppose the existence of the upper pressure limit of hydrate formation in this system; the experimental results obtained confirm this assumption. 相似文献