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

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Каталог книг и брошюр библиотеки ИФ СО РАН

Каталог журналов библиотеки ИФ СО РАН

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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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.
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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.
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