Библиотека института физики им. Л.В. Киренского СО РАН

Главная

Базы данных

Труды сотрудников ИФ СО РАН - результаты поиска

Вид поиска

Каталог книг и брошюр библиотеки ИФ СО РАН

Каталог журналов библиотеки ИФ СО РАН

Труды сотрудников ИФ СО РАН

Область поиска

в найденном

Найдено в других БД:

Каталог книг и брошюр библиотеки ИФ СО РАН (2)

Формат представления найденных документов:
полный	информационный	краткий

Отсортировать найденные документы по:
автору	заглавию	году издания	типу документа

Поисковый запрос: (<.>K=Fluorine<.>)

Общее количество найденных документов : 25
Показаны документы с 1 по 20

1-20 21-25

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Kartashev A. V., Pogorel'tsev E. I., Laptash N. M.
Заглавие : Heat capacity, thermal expansion and barocaloric effect in fluoride K2TaF7
Место публикации : J. Mater. Sci. - 2019. - Vol. 54, Is. 23. - P.14287–14295. - ISSN 00222461 (ISSN), DOI 10.1007/s10853-019-03924-8
Примечания : Cited References: 20. - The reported study was funded by RFBR according to the research Project No. 18-02-00269_a.
Аннотация: The heat capacity and thermal expansion of potassium heptafluorotantalate were studied. The room temperature phase P21/c is stable at least to 4 K. The strong first-order phase transition P21/c−Pnma at T0=486.2K is accompanied by giant changes in the entropy, ΔS0=22.3J(molK)−1, and volume strain, δV0/V=−3.6%. A rather high sensitivity of K2TaF7 to pressure was found, dT0/dp=−220KGPa−1. Significant extensive and intensive barocaloric effects are found at low pressure. The possibility of improving the barocaloric properties is discussed.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Kartashev A. V., Bogdanov E. V., Flerov I. N., Laptash N. M.
Заглавие : Calorimetric, dilatometric and DTA under pressure studies of the phase transitions in elpasolite (NH4)2KZrF7
Место публикации : J. Fluor. Chem. - 2020. - Vol. 235. - Ст.109523. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2020.109523
Примечания : Cited References: 45. - The reported study was funded by RFBR according to the research project No. 18-02-00269 a. X-ray and dilatometric data were obtained using the equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center "Krasnoyarsk Science Center SB RAS"
Аннотация: Heat capacity, thermal expansion, and sensitivity to the hydrostatic pressure of (NH4)2KZrF7 elpasolite are studied in a wide temperature range. The changes in deformation and entropy during successive phase transitions are determined: Δ(ΔV/V) = 3·10−4; ΔS = 8 J/mol K The temperatures and entropies of phase transitions turned out to be slightly sensitive to pressure changes. An analysis of the entropy of phase transformations was performed in the framework of the model of the cubic phase structure Fm-3 m. In the low temperature phase, an anomalous behavior of thermodynamic properties, which is not characteristic of phase transitions, was observed, accompanied by a significant change in the crystal lattice entropy.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Boca M., Molokeev M. S., Rakhmatullin A., Kubikova B., Netriova Z.
Заглавие : The structure of the metastable K18Ta5Zr5F63 phase
Место публикации : New J. Chem. - 2020. - Vol. 44, Is. 22. - P.9264-9270. - ISSN 11440546 (ISSN), DOI 10.1039/d0nj02428g
Примечания : Cited References: 30. - Financial support from TGIR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged. This work was supported by the Slovak Research and Development Agency under the contract no. APVV-15-0479. This work was financially supported by the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and the Slovak Academy of Sciences, grant no. Vega 2/0024/20
Аннотация: A metastable phase K18Ta5Zr5F63 was prepared by molten salt synthesis of K2TaF7 and K2ZrF6 in a sealed Pt crucible. This is the first example of a structure of a fluoride complex compound containing both tantalum and zirconium as central atoms. The asymmetric part of the unit cell contains two Ta/Zr sites and one pure Zr site. The Ta1/Zr1 ion is coordinated by seven F ions forming one capped trigonal prism. The Ta2/Zr2 ion is coordinated by six F ions forming a trigonal prism, and this polyhedron is fully ordered. The Zr3 ion is coordinated by six F ions, which are disordered over two positions. All (Zr/Ta)Fn (n = 6–8) polyhedra are isolated from each other, although the ZrF6 units have shared faces, forming an infinite channel along the c-axis. 19F MAS NMR experiments agree with the proposed structural model, identifying all five central non-equivalent polyhedra. The K18Ta5Zr5F63 phase decomposes within several months to its initial components; this can be monitored by NMR, DSC and XRD experiments. Moreover, accelerated decomposition can be achieved by thermal treatment, resulting in the formation of a K3ZrF7 phase.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pogoreltsev E. I., Bogdanov E. V., Melnikova S.V., Flerov I. N., Laptash N. M.
Заглавие : (NH4)3HfF7: Crystallooptical and calorimetric studies of a number of successive phase transitions
Место публикации : J. Fluor. Chem.: Elsevier, 2017. - Vol. 204. - P.45-49. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2017.10.004
Примечания : Cited References: 14
Аннотация: Single crystals of (NH4)3HfF7 were grown. Polarising optical observations as well as measurement of the heat capacity and birefringence Δn(Т) were performed in the temperature range of 200–310 K. Reversible phase transitions at temperatures T0 = 290 K, Т1 = 280.5 K, Т2 ≈ 273 K, Т3 = 266 K, Т4 = 259 K, Т5 = 231 K, Т6 = 229 K were found. Observations in polarised light make it possible to suggest a sequence of changes in the symmetry groups for these transitions: Fm3m ⟵Т0→ cub. ⟵Т1→ mmm (1) ⟵Т2→ mmm (2) ⟵Т3→ mmm (3) ⟵Т5→ 2/c. The T-p phase diagram was studied and the temperature boundaries of the stability of the distorted crystalline phases were determined. A significant change of the entropy at successive phase transitions ΣΔS = 10.6 J/mol K indicates a disordering of the initial cubic phase.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wu, Po-Chang, Chen, Hsin-Li, Rudakova, Natalya V., Timofeev I. V., Zyryanov V. Ya., Lee, Wei
Заглавие : Electro-optical and dielectric properties of polymer-stabilized blue phase liquid crystal impregnated with a fluorine-containing compound
Коллективы : Ministry of Science and Technology, Taiwan [104-2112-M-009-008-MY3, 106-2923-M-009-002-MY3]; Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund [16-42-240704, 17-42-240464]
Место публикации : J. Mol. Liq. - 2018. - Vol. 267. - P.138-143. - ISSN 0167-7322, DOI 10.1016/j.molliq.2017.12.062. - ISSN 1873-3166(eISSN)
Примечания : Cited References: 47. - The authors are indebted to Prof. Mon-Juan Lee of Chang-Jung Christian University for valuable discussions on photopolymerization. This work was financially supported by the Ministry of Science and Technology, Taiwan, through Grant Nos. 104-2112-M-009-008-MY3 and 106-2923-M-009-002-MY3, and by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research projects 16-42-240704 and 17-42-240464.
Предметные рубрики: HYSTERESIS
TEMPERATURE
MONOMERS
Ключевые слова (''Своб.индексиров.''): polymer-stabilized blue phase--liquid crystal--fluorine-containing--compound--operating voltage--ionic effect
Аннотация: The effects of a fluorine-containing compound (4,4′-difluorobenzophenone; DF) on the electro-optical and dielectric properties of polymer-stabilized blue phase (PSBP) liquid crystals were investigated. When a PSBP cell was driven by an in-plane electric field, the addition of DF up to 2.7 wt% effectively reduced the operation voltage by ~ 30%. Further inspection by dielectric spectroscopy indicated that the ionic concentration in PSBP decreased with increasing loading of DF. This finding can be ascribed to the complexation of impurity ions near the ketone group and carbon–fluorine bonds of the DF compound that restrained the ion transport after photopolymerization. As a result, the DF compound can be regarded as a superior ion-suppressor, enabling the reduction in the ionic effect and, in turn, the promotion of the electro-optical response of a PSBP.
Смотреть статью,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Bogdanov E. V., Molokeev M. S., Laptash N. M., Flerov I. N.
Заглавие : Optical and calorimetric studies of K2TaF7
Место публикации : J. Fluor. Chem. - 2019. - Vol. 222-223. - P.75-80. - ISSN 00221139 (ISSN) , DOI 10.1016/j.jfluchem.2019.04.016
Примечания : Cited References: 26. - The reported study was funded by RFBR according to the research project № 18-02-00269.
Аннотация: Optical and calorimetric experiments on K2TaF7 are performed in a wide temperature range. No features were found in the behavior of the birefringence Δnb(T), the angle of rotation of the indicatrix ϕ(T) and the heat capacity ΔCp(T) except for those associated with the Pnma↔P21/c phase transition. Structural transformation was characterized as strong first order “proper” ferroelastic accompanied by a huge angle ϕ ≈40° and strong pre-transition phenomena in Δnb(T). Two contributions to the anomalies of the optical properties were found associated with the photoelastic effect and the transition parameter related linearly to the spontaneous deformation. Thermal treatments cause correlated changes in temperature and enthalpy of the phase transition, which leads to the invariance of the large magnitude of the corresponding entropy ΔS = 22 J/mol·K which does not match the model with the absence of structural disorder in the Pnma phase.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen Y., Liu F., Zhang Z., Hong J., Molokeev M. S., Bobrikov I. A., Shi J., Zhou J., Wu M.
Заглавие : A novel Mn4+-activated fluoride red phosphor Cs30(Nb2O2F9)9(OH)3·H2O:Mn4+ with good waterproof stability for WLEDs
Место публикации : J. Mater. Chem. C. - 2022. - Vol. 10, Is. 18. - P.7049-7057. - ISSN 20507534 (ISSN), DOI 10.1039/d2tc00132b
Примечания : Cited References: 56. - This work was financially supported by grants from the National Natural Science Foundation of China (NSFC) (No. 51802359), the Joint Funds of NSFC and Yunnan Province (No. U1702254), and Guangdong Basic and Applied Basic Research Foundation (No. 2020A1515010556)
Аннотация: Red-light-emitting materials, as pivotal components of warm white light-emitting diodes (WLEDs), have drawn increasing public focus. Among these, Mn4+-doped red light-emitting fluorides have drawn considerable attention when combined with an InGaN chip; however, they suffer from poor water stability under humid conditions. In this work, a novel fluoride red phosphor, Cs30(Nb2O2F9)9(OH)3·H2O:xMn4+ (CNOFM), with good water resistance was synthesized for the first time using a facile co-precipitation method at ambient temperature. Experiments were implemented for the precise analysis of its crystal structure, optical properties, micro-morphology, thermal behavior, and waterproof properties. 6.66% Mn4+-doped CNOFM maintained a stable crystal structure and possessed strong PL intensity located at 633 nm with high color purity of 96%. CNOFM showed better thermal and waterproof stability compared with the commercial K2SiF6:Mn4+ red phosphor. Without any surface modifications, the PL intensity remained at about 83% of the initial value after immersion in water for 60 min, and the mechanism was investigated. Finally, a warm WLED with a CRI of 92.3 and CCT of 3271 K was fabricated using the CNOFM red phosphor.
Смотреть статью,
Scopus
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Laptash N. M., Pogoreltsev E. I.
Заглавие : Phase transformation in some hexahydrated metal(II) fluorogermanates and fluorotitanates: Optical and differential scanning calorimetry studies
Место публикации : J. Fluor. Chem. - 2022. - Vol. 263. - Ст.110048. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2022.110048
Примечания : Cited References: 31
Аннотация: Large single crystals of hydrated fluorides CoGeF6∙6H2O, FeGeF6∙6H2O, CoTiF6∙6H2O, and ZnTiF6∙6H2O were obtained and their birefringence and heat capacities have been studied. The compounds undergo a phase transition (PT) of the first order, which is accompanied by a change in optical anisotropy, twinning, and a decrease in the compound symmetry from trigonal (m, ) to monoclinic (Р21/c) in accordance with the rotation of the optical indicatrix around only one direction. The value of the entropy change during the PT is small for the first two compounds (0.36R and 0.34R) and large for the last two (0.76R and 0.95R).
Смотреть статью,
Scopus
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dubrovskiy A. A., Knyazev Yu. V., Gerasimova Yu. V., Udovenko A. A., Laptash N. M.
Заглавие : Influence of the Jahn-Teller effect on magnetic anisotropy in single crystals of fluorine hexahydrates of transition metals
Место публикации : Phys. Solid State. - 2022. - Vol. 64, Is. 11. - P.1709-1712. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2022.11.54194.406. - ISSN 10906460 (eISSN)
Примечания : Cited References: 16. - The work was done with financial support from the Russian Foundation for Basic Research, Government of Krasnoyarsk Krai and the Krasnoyarsk Krai Foundation of Science within the research project No. 20-42-240014
Аннотация: The magnetic properties of fluorine hexahydrates of transition metals have been studied. It was found that the presence of spin-orbit interaction of the transition metal ion has a significant effect on anisotropy of magnetic properties. Depending on the direction of interaction of the orbital magnetic moment of a transition metal cation with a crystal field easy direction of magnetization changes from the crystallographic b-axis to the c-axis.
Смотреть статью,
Читать в сети ИФ
Найти похожие

10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Molokeev M. S., Kartashev A. V., Pogoreltsev E. I., Mel'nikova S. V., Laptash N. M., Flerov I. N.
Заглавие : Investigation of thermal properties and structure of complex fluoride K3ZrF7
Место публикации : J. Fluor. Chem. - 2021. - Vol. 241. - Ст.109677. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2020.109677
Примечания : Cited References: 44. - The reported study was funded by RFBR according to the research project No. 18-02-00269 a. X-ray and dilatometric data were obtained using the equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center "Krasnoyarsk Science Center SB RAS"
Аннотация: X-ray, calorimetric and dilatometric studies of K3ZrF7 revealed the existence of the phase transition Fm-3m ↔ R-3m at T0 = 320 K. The structural model assumes a disorder of a pentagonal bipyramid ZrF7 with the following ratio of equivalent orientation positions in the initial and distorted phases: 12 to 6. A good agreement was found between the experimental and model-calculated changes in strain and entropy during the phase transition. A comparative analysis of entropy and structural parameters of related fluorides K3ZrF7 - (NH4)2KZrF7 - (NH4)3ZrF7 was performed. The anomalous behavior of thermodynamic properties in the range 140−230 K is not typical for phase transitions and is accompanied by a significant change in the entropy of the crystal lattice.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bogdanov E. V., Molokeev M. S., Gorev M. V., Kartashev A. V., Laptash N. M., Flerov I. N.
Заглавие : Phase transition in RbCdZrF7: Structure and thermal properties
Место публикации : J. Fluor. Chem. - 2021. - Vol. 245. - Ст.109748. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2021.109748
Примечания : Cited References: 30. - The reported study was funded by RFBR according to the research project No. 18-02-00269 a. X-ray and dilatometric data were obtained using the equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center "Krasnoyarsk Science Center SB RAS"
Аннотация: X-ray, calorimetric and dilatometric studies of RbCdZrF7 revealed the existence of the second order phase transition Cmcm - P21/m at T0 = 200 K. The structure of the initial and distorted phases is ordered. The phase transition is associated with displacements of fluorine atoms, which leads to minor rotations of the CdF7 and ZrF7 pentagonal bipyramids. A small change in entropy, 0.1R, is characteristic of displacive-type transformations. An anomalously high susceptibility of the transition temperature to hydrostatic pressure was found.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Bovina A. F., Bogdanov E. V., Pogoreltsev E. I., Laptash N. M.
Заглавие : Disorder and phase transitions in oxyfluoride (NH4)(3)Ta(O-2)(2)F-4
Место публикации : J. Fluor. Chem. - 2011. - Vol. 132, Is. 10. - P.713-718. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2011.05.012
Примечания : Cited Reference Count: 19. - Гранты: This work was supported by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation (NSh-4645.2010.2).Финансирующая организация: Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation [NSh-4645.2010.2]
Предметные рубрики: HEAT-CAPACITY
COMPLEXES
RB2KTIOF5
FLUORIDES
CRYOLITE
Ключевые слова (''Своб.индексиров.''): cubic oxyfluorides--structural disorder--phase transitions--entropy--permittivity--pressure effect--cubic oxyfluorides--entropy--permittivity--phase transitions--pressure effect--structural disorder
Аннотация: Calorimetric, X-ray, dielectric and DTA under pressure measurements have been performed on oxyfluoride (NH4)(3)Ta(O-2)(2)F-4. The succession of nonferroelectric phase transitions was found associated with the order-disorder processes. The comparative analysis tantalate with related niobate has revealed the important role of the central atom in the physical properties behavior, mechanism of structural distortions and barocaloric effect in oxyfluorides with the eight-coordinated anionic polyhedra. (C) 2011 Elsevier By. All rights reserved.
WOS,
Scopus,
eLibrary
Найти похожие

13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Izosimova M. G., Livshits A. I., Buznik V. M., Fedorov P. P., Kkrivandina E. A., Sobolev B. P.
Заглавие : Mechanism of fluorine ion diffusion in tysonite-type solid electrolytes
Место публикации : Fiz. Tverd. Tela. - 1986. - Vol. 28, Is. 9. - P.2644-2647. - ISSN 0367-3294
Примечания : Cited References: 20
WOS
Найти похожие

14.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Flerov I. N., Pogoreltsev E. I., Mel'nikova S. V., Gorev M. V., Kartashev A. V., Bogdanov E. V., Molokeev M. S., Laptash N. M.
Заглавие : Structure, physical properties and phase transitions in (NH4)2TiF6×NH4F
Коллективы : European Symposium on Fluorine Chemistry (17; 2013 ; June ; 21-25; Paris, France)
Место публикации : 17th European Symposium on Fluorine Chemistry: Abstracts book. - 2013. - P.37
Найти похожие

15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Molokeev M. S., Bogdanov E. V., Misyul S. V., Tressaud A., Flerov I. N.
Заглавие : Phase transitions in defect pyrochlore structure of CsFe2F6
Коллективы : European Symposium on Fluorine Chemistry (17; 2013 ; June ; 21-25; Paris, France)
Место публикации : 17th European Symposium on Fluorine Chemistry: Abstracts book. - 2013. - P.276
Найти похожие

16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Pogoreltsev E. I., Flerov I. N., Laptash N. M.
Заглавие : Unusual sequence of phase transitions in (NH4)3TiF7 detected by optic and calorimetric studies
Коллективы : Russian Foundation for Basic Research [12-02-00056]; Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation [NSh-924.2014.2]
Место публикации : J. Fluor. Chem.: Elsevier Science, 2014. - Vol. 165. - P.14-19. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2014.05.016. - ISSN 1873-3328
Примечания : Cited References: 13. - This work was supported by Russian Foundation for Basic Research (Grant no. 12-02-00056), and the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation (Grant no. NSh-924.2014.2).
Предметные рубрики: CRYSTAL-STRUCTURE
DIFFRACTION
NH4F
Ключевые слова (''Своб.индексиров.''): cubic fluorides--phase transitions--crystal-optic--calorimetry
Аннотация: For the first time structural transformations were observed for one of the compounds belonging to the family of double salt fluorides A3MeF7 = A2MeF6·AF. Single crystals of (NH4)3TiF7 = (NH4)2TiF6·NH4F were grown by evaporation of the aqueous solution. Polarizing optical observations, heat capacity and birefringence Δn = (no − ne) measurements were performed in a wide temperature range 100–400 K. Two reversible, first order structural phase transitions were found to be followed by an unusual sequence of symmetry changes: cubic (G3) (T2↓ = 287.5 K; T2↑ = 291–310 K) ↔ P4/mnc (G2) (T1↓ = 358.5 K; T1↑ = 360 K) ↔ 4/m (G1). The twin structures observed were described assuming the existence of cubic parent phase G0 with P m 3 ¯ m symmetry.
Смотреть статью,
Scopus,
WoS,
Читать в сети ИФ
Найти похожие

17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Fedorov D. G., Sorokin P. B., Sakai S., Entani S., Ohtomo M., Matsumoto Y., Naramoto H.
Заглавие : Intrinsic edge asymmetry in narrow zigzag hexagonal heteroatomic nanoribbons causes their subtle uniform curvature
Место публикации : J. Phys. Chem. Lett. - 2012. - Vol. 3, Is. 15. - P.2003-2008. - ISSN 1948-7185, DOI 10.1021/jz300625t
Примечания : Cited References: 42. - This work was supported by JAEA Research fellowship (P.V.A.). P.V.A. also acknowledges JAEA ASRC and the Molecular Spintronics Group for hospitality and fruitful collaboration. D.G.F. thanks Prof. Kazuo Kitaura for many fruitful discussions and the Next Generation SuperComputing Project, Nanoscience Program and Strategic Programs for Innovative Research (MEXT, Japan) for financial support. This work was partially supported by Russian Ministry of Education and Science (Contract No. 16.552.11.7014) (P.B.S.).
Предметные рубрики: MOLECULAR-ORBITAL METHOD
WALLED CARBON NANOTUBES
GRAPHENE NANORIBBONS
ELECTRONIC-STRUCTURE
OPTICAL-TRANSITIONS
SOLIDS
BOND
Aromatic rings
Conical surfaces
Finite length
Fragment molecular orbital methods
Graphene nanoribbons
Intrinsic curvature
Nanoribbons
Out-of-plane
Structural stress
Ключевые слова (''Своб.индексиров.''): zigzag nanoribbons--hexagonal atomic lattices--fluorine-terminated graphene
Аннотация: The atomic and electronic structure of narrow zigzag nanoribbons with finite length, consisting of graphene terminated by fluorine on one side, hexagonal (h) h-BN, and h-SiC were studied with density functional theory. It is found that the asymmetry of nanoribbon edges causes a uniform curvature of the ribbons due to structural stress in the aromatic ring plane. Narrow graphene nanoribbons terminated with fluorine on one side demonstrate a considerable out-of-plane bend, suggesting that the nanoribbon is a fraction of a conical surface. It is shown that the intrinsic curvature of the narrow nanoribbons destroys the periodicity and results in a systematic cancellation of the dipole moment. The in- and out- of-plane curvature of thin arcs allows their closure in nanorings or cone fragments of giant diameter. Using the fragment molecular orbital method, we optimized the structure of a planar giant arc and a closed ring of h-BN with a diameter of 105 nm.
Смотреть статью,
Scopus,
WoS,
Читать в сети ИФ
Найти похожие

18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Molokeev M. S., Yurkin G. Yu., Gavrilova T. A., Kesler V. G., Laptash N. M., Flerov I. N., Patrin G. S.
Заглавие : Synthesis, structural, magnetic, and electronic properties of cubic CsMnMoO3F3 oxyfluoride
Место публикации : J. Phys. Chem. C: American Chemical Society, 2012. - Vol. 116, Is. 18. - P.10162-10170. - ISSN 1932-7447, DOI 10.1021/jp302020f
Примечания : Cited References: 64. - We thank Dr. A.M. Ziatdinov for the electron paramagnetic resonance measurements. This study was partly supported by SB RAS (Grant 28).
Предметные рубрики: RAY PHOTOELECTRON-SPECTROSCOPY
PHASE-TRANSITIONS
CORE LEVELS
SURFACE CHARACTERIZATION
CRYSTAL-STRUCTURE
CLEAVED SURFACE
MIXED-VALENCE
OXIDES
MN
MOLYBDENUM
Chemical bondings
Cubic phase
Energy differences
Heat capacity measurements
Oxyfluorides
Powder samples
Solid-state synthesis
Space Groups
Temperature range
Valence electron
Binding energy
Chemical bonds
Electronic structure
Fluorine compounds
Magnetic properties
Metal ions
Photoelectrons
Rietveld method
X ray photoelectron spectroscopy
Electronic properties
Аннотация: A powder sample of CsMnMoO3F3 oxyfluoride has been prepared by solid state synthesis. The pyrochlore-related crystal structure of CsMnMoO3F3 has been refined by the Rietveld method at T = 298 K (space group Fd-3m, a = 10.59141(4) angstrom, V = 1188.123(8) angstrom(3); R-B = 3.44%). The stability of the cubic phase has been obtained over the temperature range T = 110-293 K by heat capacity measurements. Magnetic properties have been measured over the range of T = 2-300 K. The electronic structure of CsMnMoO3F3 has been evaluated by X-ray photoelectron spectroscopy. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and wide comparison with related oxides and fluorides. The competition between O-2(-) and F- ions for metal valence electrons has been found.
Смотреть статью,
Scopus,
WoS,
Читать в сети ИФ
Найти похожие

19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fokina V. D., Gorev M. V., Bogdanov E. V., Pogoreltsev E. I., Flerov I. N., Laptash N. M.
Заглавие : Thermal properties and phase transitions in (NH4) 3ZrF7
Место публикации : Journal of Fluorine Chemistry. - 2013. - Vol. 154. - P.1-6. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2013.07.001
Ключевые слова (''Своб.индексиров.''): cubic fluorides--entropy--permittivity--phase transitions--pressure effect--thermal dilatation
Аннотация: The heat capacity, thermal dilatation, permittivity, and T-p phase diagram of (NH4)3ZrF7 have been studied in wide temperature and pressure ranges. Two phase transitions were found in addition to previously known structural transformations. The stability of crystal phases to temperature and pressure has been examined and a possibility of transition between two cubic phases has been discussed. The total excess entropy change SDSi = Rln6 is characteristic for the order-disorder processes, but its stepwise increase is not consistent with the structural model associated with the strong disorder assumed in the initial cubic phase. В© 2013 Elsevier B.V. All rights reserved.
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Molokeev M. S., Laptash N. M., Udovenko A. A., Pogoreltsev E. I., Mel'nikova S. V., Misyul S. V.
Заглавие : Structural transformation between two cubic phases of (NH4)3SnF7
Место публикации : J. Fluor. Chem.: Elsevier, 2015. - Vol. 178. - P.86-92. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2015.06.024
Примечания : Cited References: 19. - We thank T.A. Kaidalova for the idea of doubling the unit cell parameter of (NH4)3SnF7 at room temperature. The reported study was partially supported by RFBR, research project No. 15-02-02009 a.
Предметные рубрики: CRYSTAL-STRUCTURE
TRANSITION
NH4F
Ключевые слова (''Своб.индексиров.''): cubic fluorides--phase transitions--x-ray--calorimetry--crystal optics
Аннотация: Reinvestigations of the room temperature structure of ammonium heptafluorostannate (NH4)3SnF7 = (NH4)2SnF6·NH4F = (NH4)3[SnF6]F by both powder and single crystal X-ray diffractions have revealed that its real symmetry is Pa−3 (Z = 8) instead of Pm−3m (Z = 1) suggested earlier. Polarizing optical observations, heat capacity, X-ray powder, and single crystal measurements were performed in a wide temperature range (100–420 K). A reversible structural phase transition of the first order between two cubic modifications Pa−3 ↔ Pm−3m was found at about T0 = 360 K. The structural models associated with partially disordered and totally ordered high and low temperature phases, respectively, comply with a large value of phase transition entropy.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие