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Найдено документов в текущей БД: 53

    Structural, spectroscopic, and electronic properties of cubic G0-Rb2KTiOF5 oxyfluoride
/ V. V. Atuchin [et al.] // J. Phys. Chem. C. - 2013. - Vol. 117, Is. 14. - P. 7269-7278, DOI 10.1021/jp401391y. - Cited References: 80. - This study was supported by SB RAS (Grant 28.13), the National Natural Science Foundation of China under Grants 11174297 and 91022036, and the National Basic Research Project of China (Nos. 2010CB630701 and 2011CB922204). . - ISSN 1932-7447
   Перевод заглавия: Структурные, спектроскопические и электронные свойства кубического оксифторида G0-Rb2KTiOF5.
РУБ Chemistry, Physical + Nanoscience & Nanotechnology + Materials Science, Multidisciplinary

Аннотация: The G0-Rb2KTiOF5 single crystals with dimensions up to nearly a centimeter in size have been prepared by slow solidification method. The elpasolite-related crystal structure of G0-Rb2KTiOF5 has been refined by Rietveld method at T = 298 K (space group Fm (3) over barm, Z = 4, a = 8.880(1) angstrom, V = 700.16(2) angstrom(3); R-B = 2.66%). The wide optical transparency range of 0.25-9 mu m and forbidden band gap of E-g = 3.87 eV have been obtained for the G0-Rb2KTiOF5 crystal. Dominating photoluminescence bands at 3.36 and 2.33 eV are related to free and self-trapped excitons, respectively. The electronic structure of G0-Rb2KTiOF5 has been evaluated by X-ray photoelectron spectroscopy and calculated with the first-principles methods. A good agreement between theoretical and experimental results has been achieved. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and a wide comparison with related oxides and fluorides. The competition between O2- and F- ions for metal valence electrons has been found.

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Держатели документа:
Russian Acad Sci, Lab Opt Mat & Struct, Inst Semicond Phys, Novosibirsk 630090, Russia
Russian Acad Sci, Inst Geol & Mineral, Lab Crystal Growth, Siberian Branch, Novosibirsk 630090, Russia
Russian Acad Sci, Inst Semicond Phys, Lab Phys Bases Integrated Microelect, Siberian Branch, Novosibirsk 630090, Russia
Chinese Acad Sci, Tech Inst Phys & Chem, Key Lab Funct Crystals & Laser Technol, BCCRD, Beijing 100190, Peoples R China
Russian Acad Sci, Siberian Branch, Inst Phys, Lab Crystal Phys, Krasnoyarsk 660036, Russia
Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China

Доп.точки доступа:
Atuchin, V. V.; Isaenko, L. I.; Kesler, V. G.; Kang, L.; Lin, Z. S.; Molokeev, M. S.; Молокеев, Максим Сергеевич; Yelisseyev, A. P.; Zhurkov, S. A.

    Thermal properties and phase transitions in (NH4) 3ZrF7
/ V. D. Fokina [et al.] // Journal of Fluorine Chemistry. - 2013. - Vol. 154. - P. 1-6, DOI 10.1016/j.jfluchem.2013.07.001 . - ISSN 0022-1139

Кл.слова (ненормированные):
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.

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Держатели документа:
RAS, Siberian Dept, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660074, Russia
Krasnoyarsk State Agr Univ, Krasnoyarsk 660049, Russia
RAS, Far Eastern Dept, Inst Chem, Vladivostok 690022, Russia

Доп.точки доступа:
Fokina, V. D.; Фокина, Валентина Дмитриевна; Gorev, M. V.; Горев, Михаил Васильевич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.

    Fluorides and Oxyfluorides with Elpasolite-Cryolite Structure: Order-Disorder Phase Transitions and Barocaloric Efficiency
/ I. N. Flerov, M. V. Gorev // International Conference “Functional materials and nanotechnologies” FM&NT 2012. - 2012. - P. 65


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Доп.точки доступа:
Gorev, M. V.; Горев, Михаил Васильевич; Флёров, Игорь Николаевич; Functional Materials and Nanotechnologies(2012 ; Apr. ; 17-20 ; Riga, Latvia)

    Crystal and local structure refinement in Ca2Al3O6F explored by X-ray diffraction and Raman spectroscopy
/ Z. G. Xia [et al.] // Phys. Chem. Chem. Phys. - 2014. - Vol. 16, Is. 13. - P. 5952-5957, DOI 10.1039/c3cp53816h. - Cover illustration: Graphical abstract from this article. - Cited References: 34. - This present work was supported by the National Natural Science Foundations of China (Grant No. 51002146, 51272242), Natural Science Foundations of Beijing (2132050), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-12-0950), Beijing Nova Program (Z131103000413047) and Beijing Youth Excellent Talent Program (YETP0635), and this study was also partially supported by SB RAS, Grant 28.13. Part of the work was supported by the National Science Council of Taiwan under contract No. NSC 101-2113-M-002-014-MY3. . - ISSN 1463-9076. - ISSN 1463-9084
   Перевод заглавия: Уточнение кристаллической и локальной структуры в Ca2Al3O6F при помощи рентгеновской дифракции и Рамановской спектроскопии
РУБ Chemistry, Physical + Physics, Atomic, Molecular & Chemical

Аннотация: We present a combined structural analysis on the powder of the Ca2Al3O6F phase using X-ray diffraction (XRD) and Raman spectroscopy techniques. The crystal structure of Ca2Al3O6F has been refined in the rhombohedral system, R space group, a = 17.3237(7) Å, c = 7.00017(4) Å, V = 1819.38(2) Å3, Z = 6. The Ca2Al3O6F phase consists of almost ideal AlO4 tetrahedrons linked through corners, Ca2+ ions in voids, and F− ions disordered over 6 sites around the Ca2 ion. The two different Ca sites have also been verified by the photoluminescence spectrum and decay curves using Eu2+ as the probe ion substituted onto the Ca2+ sites. A lattice dynamics simulation based on the simplified version of the Born–Karman potential model has been produced. Calculated Raman phonon modes agree qualitatively well with the experimental data. The calculations show that the strong line at 538 cm−1 (Ag) corresponds to the vibrational mode of a six-membered AlO4 tetrahedrons ring, and the line at 572 cm−1 (Ag) corresponds to the full symmetric vibration of fluorine atoms in the ab crystal plane.

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Держатели документа:
China Univ Geosci, Sch Mat Sci & Technol, Beijing 100083, Peoples R China
SB RAS, LV Kirensky Phys Inst, Lab Crystal Phys, Krasnoyarsk 660036, Russia
SB RAS, LV Kirensky Phys Inst, Lab Mol Spect, Krasnoyarsk 660036, Russia
SB RAS, Inst Semicond Phys, Lab Opt Mat & Struct, Novosibirsk 630090 90, Russia
Natl Taiwan Univ, Dept Chem, Taipei 10617, Taiwan
Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China

Доп.точки доступа:
Xia, Zhiguo; Molokeev, M. S.; Молокеев, Максим Сергеевич; Oreshonkov, A. S.; Орешонков, Александр Сергеевич; Atuchin, V. V.; Liu, R. S.; Dong, C.

    Unusual sequence of phase transitions in (NH4)3TiF7 detected by optic and calorimetric studies
/ S. V. Mel'nikova [et al.] // J. Fluor. Chem. - 2014. - Vol. 165. - P. 14-19, DOI 10.1016/j.jfluchem.2014.05.016. - 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). . - ISSN 0022-1139. - ISSN 1873-3328
РУБ Chemistry, Inorganic & Nuclear + Chemistry, Organic
Рубрики:
CRYSTAL-STRUCTURE
   DIFFRACTION

   NH4F

Кл.слова (ненормированные):
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.

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Держатели документа:
RAS, LV Kirensky Phys Inst, Siberian Dept, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660074, Russia
Russian Acad Sci, Inst Chem, Far Eastern Dept, Vladivostok 690022, Russia

Доп.точки доступа:
Mel'nikova, S. V.; Мельникова, Светлана Владимировна; Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.; 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]

    Reconstructive phase transition in (NH4)3TiF7 accompanied by the ordering of TiF6 octahedra
/ M. S. Molokeev [et al.] // Acta Crystallogr. B. - 2014. - Vol. 70. - P. 924-931, DOI 10.1107/S2052520614021192. - This study was supported by Russian Fund of Basic Research, project No. 12-02-00056 a . - ISSN 0108-7681. - ISSN 1600-5740
   Перевод заглавия: Реконструктивный фазовый переход в (NH4)3TiF7, сопровождающийся упорядочением октаэдров TiF6
РУБ Crystallography

Аннотация: An unusual phase transition P4/mnc →Pa3 has been detected after cooling the (NH4)3TiF7 compound. Some TiF6 octahedra, which are disordered in the room-temperature tetragonal structure, become ordered in the low-temperature cubic phase due to the disappearance of the fourfold axis. Other TiF6 octahedra undergo large rotations resulting in huge displacements of the F atoms by 1.5-1.8 Å that implies a reconstructive phase transition. It was supposed that phases P4/mbm and Pm3m could be a high-temperature phase and a parent phase, respectively, in (NH4)3TiF7. Therefore, the sequence of phase transitions can be written as Pm3m → P4/bm → P4/mnc → Pa3. The interrelation between (NH4)3TiF7, (NH4)3GeF7 and (NH4)3PbF7 is found, which allows us to suppose phase transitions in relative compounds.

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Держатели документа:
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Siberian State Univ, Inst Engn Phys & Radioelect, Krasnoyarsk 660074, Russia
Inst Chem, Vladivostok 660022, Russia

Доп.точки доступа:
Molokeev, M. S.; Молокеев, Максим Сергеевич; Misjul, S. V.; Мисюль, Сергей Валентинович; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.

    Ferroelastic phase transitions in fluorides with cryolite and elpasolite structures
/ I. N. Flerov [et al.] // Crystallogr. Rep. - 2004. - Vol. 49, Is. 1. - P. 100-107, DOI 10.1134/1.1643969. - Cited References: 43 . - ISSN 1063-7745
Аннотация: The ferroelastic phase transitions are investigated in several series of fluoride crystals belonging to the elpasolite and cryolite families (space group Fm (3) over barm) with the general formula A(2)BB'F-6. The influence of the size and shape of cations and anions on the entropy and the mechanism of structural distortions is discussed. (C) 2004 MAIK "Nauka/Interperiodica".

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Держатели документа:
Russian Acad Sci, Kirensky Inst Phys, Siberian Div, Krasnoyarsk 660036, Russia
Inst Chim Mat Condensee Bordeaux, F-33608 Pessac, France
ИФ СО РАН

Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Gorev, M. V.; Горев, Михаил Васильевич; Aleksandrov, K. S.; Александров, Кирилл Сергеевич; Tressaud, A.; Fokina, V. D.; Фокина, Валентина Дмитриевна

    Ferroelastic phase transitions in fluorides with cryolite and elpasolite structures
/ I. N. Flerov, M. V. Gorev, K. S. Aleksandrov [et al.] // Kristallogr. - 2004. - Vol. 49, Is. 1. - P. 107-115 . - ISSN 0023-4761


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Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Gorev, M. V.; Горев, Михаил Васильевич; Aleksandrov, K. S.; Александров, Кирилл Сергеевич; Tressaud, A.; Fokina, V. D.; Фокина, Валентина Дмитриевна

    Phase transitions in perovskite-like fluorides studied by Raman spectroscopy
[Текст] / S. N. Krylova [и др.] // The 5th International Conference on Perspectives in Vibrational Spectroscopy ICOPVS-2014. - 2014. - С. 12DOI 10.13140/2.1.2959.0408
   Перевод заглавия: Фазовые переходы в перовскитоподобных фторидах исследование методом

Аннотация: Since the discovery of Raman phenomenon the Raman spectroscopy has been considered as an efficient technique to study the structure and lattice dynamics of crystals. The creation of the monochromatic radiation laser sources has revolutionized this classical field of vibrational spectroscopy and provided an impetus to create new ones. It is established that inelastic light scattering contains valuable information on the crystal structure, phonon spectrum, mechanisms of electron-phonon and phonon-phonon.
Phase transitions in perovskite-like fluorides studied by Raman spectroscopy Krylova S.a, Krylov A.a, Voronov V.a and Vtyurin A.a a Akademgorodok 50/38, Krasnoyarsk, 660036, L. V. Kirensky Institute of physics SB RAS, Russia, slanky@iph.krasn.ru Since the discovery of Raman phenomenon the Raman spectroscopy has been considered as an efficient technique to study the structure and lattice dynamics of crystals. The creation of the monochromatic radiation laser sources has revolutionized this classical field of vibrational spectroscopy and provided an impetus to create new ones. It is established that inelastic light scattering contains valuable information on the crystal structure, phonon spectrum, mechanisms of electron-phonon and phonon-phonon interactions. Obtaining this information is an important task of the solid state spectroscopy. Such experiments are necessary to investigate new crystalline materials and structures. During last decades many crystals with a complex structure were synthesized. They became new objects of fundamental solid-state physics as the perspective materials for practical use. There is a perovskite-like family including perovskites, elpasolites, layered perovskites, cryolites and other crystals with octahedral molecular ions. Perovskites are model objects to study phase transitions in crystals. The family includes the majority of modern inorganic materials applied in nonlinear optics and quantum electronics. Some of the perovskite-like materials are ferroelectrics, piezoelectrics or superconductors. This work shows the possibilities of Raman spectroscopy with reference to the phase transition investigations of some perovskite-like fluorides. It is shown that Raman spectroscopy provides the opportunity for understanding the phase transition mechanisms and estimating the behavior of ion groups at phase transition. It is shown by Raman spectroscopy that the temperature transitions from cubic into low symmetry phases in Rb2KScF6, Rb2KInF6, Rb2NaYF6 crystals result from the lattice instability caused by the MeF63+ octahedral ion tilting [1, 2]. The experimental data and results of the numerical simulations reveal that the phase transitions in the Rb2KTiOF5 crystal are due to the orientational ordering of the TiOF5 groups, but new phases remain partially disordered as well [3]. The temperature phase transitions in the (NH4)2WO2F4 crystal are caused by the ordering of molecular quasi-octahedral groups [WO2F4]2– and ammonium groups [4]. Acknowledgements This work was partly supported by the Russian Foundation for the Basic Research project no. 12-02-00056, no. 13-02-00825, and integration project SB RAS

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Доп.точки доступа:
Krylova, S. N.; Крылова, Светлана Николаевна; Krylov, A. S.; Крылов, Александр Сергеевич; Voronov, V. N.; Воронов, Владимир Николаевич; Vtyurin, A. N.; Втюрин, Александр Николаевич; International Conference on Perspectives in Vibrational Spectroscopy (5 ; 2014 ; 8-12 July ; Trivandrum, India)

    Heat capacity, entropy, dielectric properties and T–p phase diagram of (NH4)3TiF7
/ E. I. Pogoreltsev [et al.] // J. Fluor. Chem. - 2014. - Vol. 168. - P. 247-250, DOI 10.1016/j.jfluchem.2014.10.016. - Cited References: 16. - This work was supported by the Russian Foundation for Basic Research (Grant no. 15-02-02009), 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). . - ISSN 0022-1139. - ISSN 1873-3328
РУБ Chemistry, Inorganic & Nuclear + Chemistry, Organic
Рубрики:
CRYSTAL-STRUCTURE
   TRANSITIONS

   FLUORIDES

   NH4F

Кл.слова (ненормированные):
Cubic fluorides -- Phase transitions -- Dielectric -- Phase diagram -- Calorimetry

Аннотация: Successive phase transitions G1 --> G2 --> G3 in the double salt (NH4)(3)TiF7 have been studied by detailed calorimetric, DTA under hydrostatic pressure and dielectric measurements. Rather large entropy jumps at phase transition points were found to be followed by large additional contributions associated with the temperature dependence of the excess heat capacity. The permittivity behaviour and the tangent of the dielectric losses proved the nonferroelectric nature of both transformations. Two triple-points were found on the temperature-pressure phase diagram, suggesting the existence of a hypothetical parent G0 = Pm-3m cubic phase. A direct transformation between high (G0) and low (G3) temperature cubic phases takes place at p > 0.41 GPa with a baric coefficient dT(G0) --> (G3)/dp = -40 K/GPa. (C) 2014 Elsevier B.V. All rights reserved.

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Держатели документа:
RAS, Siberian Dept, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660074, Russia
Krasnoyarsk State Agr Univ, Krasnoyarsk 660049, Russia
Russian Acad Sci, Far Eastern Dept, Inst Chem, Vladivostok 690022, Russia

Доп.точки доступа:
Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Flerov, I. N.; Флёров, Игорь Николаевич; Kartashev, A. V.; Карташев, Андрей Васильевич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Laptash, N. M.; Russian Foundation for Basic Research [15-02-02009]; 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]

    Structural transformation between two cubic phases of (NH4)3SnF7
/ I. N. Flerov [et al.] // J. Fluor. Chem. - 2015. - Vol. 178. - P. 86-92, DOI 10.1016/j.jfluchem.2015.06.024. - 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. . - ISSN 0022-1139
   Перевод заглавия: Структурный переход между двумя кубическими фазами в (NH4)3SnF7
РУБ Chemistry, Inorganic & Nuclear + Chemistry, Organic
Рубрики:
CRYSTAL-STRUCTURE
   TRANSITION

   NH4F

Кл.слова (ненормированные):
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.

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Держатели документа:
L.V. Kirensky Institute of Physics, Siberian Branch of RAS, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation
Far Eastern State Transport University, Khabarovsk, Russian Federation
Institute of Chemistry, Far Eastern Branch of RAS, Vladivostok, Russian Federation

Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Molokeev, M. S.; Молокеев, Максим Сергеевич; Laptash, N. M.; Udovenko, A. A.; Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Mel'nikova, S. V.; Мельникова, Светлана Владимировна; Misyul, S. V.; Мисюль, Сергей Валентинович

    New insights on mixed-valence iron fluorides
/ A. Tressaud [et al.] // 248th ACS National Meeting : program. - 2014. - Ст. 102

Аннотация: Within a same parent composition AxMF3, with 06 octahedra are connected. In all cases, the structures are built of networks of MF6 octahedra sharing corners and are derived either from ReO3, perovskite, hexagonal tungsten bronze- (HTB), tetragonal tungsten bronze- (TTB), or pyrochlore-type structures. The strategy for obtaining such types of compounds was based on the adjustment of the experimental parameters of the chosen synthesis route, either by conventional solid state reactions or by fluorosolvothermal process. In the latter case, the microstructural properties were studied, highlighting X-ray line broadening arising from strains and size effects. In well crystallized HTB compounds prepared by solvothermal process, MS-coupled TGA measurements under He atmosphere revealed the occurrence of OH groups stabilizing the HTB-network. In FeII-FeIII based compounds, a Mössbauer study at low temperature allowed to investigate the level of electronic delocalization. In TTB-type compounds with KxFeF3 (0.502F6 (M= Rb, Cs), exhibiting an orthorhombic symmetry at room temperature [Pnma], a sequence of structural phase transitions were observed within a narrow temperature range, 500–560K: Pnma (Z=4) →Imma (Z=4) → I41/amd (Z=4) → Fd3m (Z=8). The transition mechanisms were associated with (MF6) rotational motions and small displacements of Fe atoms, in good agreement with the low experimental entropy value, which is characteristic for displacive transformations.

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Доп.точки доступа:
Tressaud, A.; Demourgues, A.; Durand, E.; Flerov, I. N.; Флёров, Игорь Николаевич; Molokeev, M. S.; Молокеев, Максим Сергеевич; ACS National Meeting(248 ; 2014 ; авг. ; 1-14 ; San Francisco, USA)

    Phase transitions in fluorides with elposolite structure
/ A. S. Krylov [и др.] // The 8th International Conference on Advanced Vibrational Spectroscopy at TU Wien : abstracts oral. - 2015. - P. 106 . - ISBN 978-3-200-04205-6


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Доп.точки доступа:
Krylov, A. S.; Крылов, Александр Сергеевич; Vtyurin, A. N.; Втюрин, Александр Николаевич; Goryainov, S. V.; Voronov, V. N.; Воронов, Владимир Николаевич; Krylova, S. N.; Крылова, Светлана Николаевна; International conference on advanced vibrational spectroscopy(8 ; 2015 ; July ; 12-17 ; Vienna, Austria); Международная конференция по достижениям в колебательной спектроскопии(8 ; 2015 ; 12-17 июля ; Вена)

    Thermal, structural, optical, dielectric and barocaloric properties at ferroelastic phase transition in trigonal (NH4)2SnF6: A new look at the old compound
/ I. N. Flerov [et al.] // J. Fluor. Chem. - 2016. - Vol. 183. - P. 1-9, DOI 10.1016/j.jfluchem.2015.12.010. - Cited References: 25. - The reported study was partially supported by RFBR, research project No. 15-02-02009a. . - ISSN 0022-1139
РУБ Chemistry, Inorganic & Nuclear + Chemistry, Organic
Рубрики:
Heat-capacity
   Ammonium

   (NH4)3TiF7

   Pressure

Кл.слова (ненормированные):
Fluorides -- Structural disorder -- Phase transitions -- Entropy -- Barocaloric effect

Аннотация: Structural phase transition P-3m1 → P-1 of the first order and nonferroelectric nature was found in (NH4)2SnF6 at about 110 K in the process of thermal, optical, dielectric and X-ray studies. Order-disorder transformation is accompanied by large changes of entropy (ΔS0 = 16.4 J/mol K) and volume (ΔV0/V ≈ 1%). The structural model associated with three orientations of NH4 tetrahedra in P-3m1 phase and their complete ordering in P-1 phase was suggested with the entropy change (ΔS0 = 18.3 J/mol K) close to the experimental value. A good agreement between baric coefficients measured in a direct way (dT0/dp = -157 K/GPa) and evaluated using entropy and volume changes at phase transition (-170 K/GPa) was found. Barocaloric effects in (NH4)2SnF6 are comparable with those of known solid state refrigerants and are characterised by a low-pressure need for realising their maximum values. © 2015 Elsevier B.V. All rights reserved.

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Держатели документа:
Kirensky Institute of Physics, Siberian Branch of RAS, Akademgorodok 50, Krasnoyarsk, Russian Federation
Institute of Engineering Physics and Radioelectronics, Siberian State University, Krasnoyarsk, Russian Federation
Astafijev Krasnoyarsk State Pedagogical University, Krasnoyarsk, Russian Federation
Krasnoyarsk State Agrarian University, Krasnoyarsk, Russian Federation
Far Eastern State Transport University, Khabarovsk, Russian Federation
Institute of Chemistry, Far Eastern Branch of RAS, Vladivostok, Russian Federation

Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Kartashev, A. V.; Карташев, Андрей Васильевич; Gorev, M. V.; Горев, Михаил Васильевич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Mel'nikova, S. V.; Мельникова, Светлана Владимировна; Molokeev, M. S.; Молокеев, Максим Сергеевич; Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Laptash, N. M.

    Thermal properties and phase transition in the fluoride, (NH4)3SnF7
/ A. V. Kartashev [et al.] // J. Solid State Chem. - 2016. - Vol. 237. - P. 269-273, DOI 10.1016/j.jssc.2016.02.027. - Cited References: 18. - This study was partially supported by the Russian Foundation for Basic Research (RFBR), research Project no. 15-02-02009a. . - ISSN 0022-4596
РУБ Chemistry, Inorganic & Nuclear + Chemistry, Physical
Рубрики:
Heat-capacity
   Chemistry

Кл.слова (ненормированные):
Phase transition -- Fluorides -- Heat capacity -- Entropy -- Thermal expansion -- High pressure

Аннотация: Calorimetric, dilatometric and differential thermal analysis studies were performed on (NH4)3SnF7 for a wide range of temperatures and pressures. Large entropy (δS0=22 J/mol K) and elastic deformation (δ(ΔV/V)0=0.89%) jumps have proven that the Pa-3虠Pm-3m phase transition is a strong first order structural transformation. A total entropy change of ΔS0=32.5 J/mol K is characteristic for the order-disorder phase transition, and is equal to the sum of entropy changes in the related material, (NH4)3TiF7, undergoing transformation between the two cubic phases through the intermediate phases. Hydrostatic pressure decreases the stability of the high temperature Pm-3m phase in (NH4)3SnF7, contrary to (NH4)3TiF7, characterised by a negative baric coefficient. The effect of experimental conditions on the chemical stability of (NH4)3SnF7 was observed. © 2016 Elsevier Inc.

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Держатели документа:
Kirensky Institute of Physics, Siberian Department of the Russian Academy of Sciences, Krasnoyarsk, Russian Federation
Astafijev Krasnoyarsk State Pedagogical University, Krasnoyarsk, Russian Federation
Institute of Engineering Physics and Radio Electronics, Siberian State University, Krasnoyarsk, Russian Federation
Krasnoyarsk State Agrarian University, Krasnoyarsk, Russian Federation
Institute of Chemistry, Far Eastern Department of the Russian Academy of Sciences, Vladivostok, Russian Federation

Доп.точки доступа:
Kartashev, A. V.; Карташев, Андрей Васильевич; Gorev, M. V.; Горев, Михаил Васильевич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.

    Temperature dependence of the fine structure of the C and E absorption bands in RbMnF3 below the Neel temperature
/ A. V. Malakhovskii, T. P. Morozova // Phys. Solid State. - 2006. - Vol. 48, Is. 2. - P. 283-290, DOI 10.1134/S1063783406020156. - Cited References: 24 . - ISSN 1063-7834
РУБ Physics, Condensed Matter

Аннотация: The variation in the parameters (width, position, intensity) of the fine structure lines in the C[(6)A(1g) - (4)A(1g), E-4(g)((4)G)] and E[(6)A(1g) - E-4(g)(D-4)] bands in RbMnF3 with temperature is studied in the temperature range 10-70 K. In the C band, two narrow ( 6 cm(-1)) lines are are distinguished at distances of 77 and 80 cm(-1) from the exciton line at T

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Держатели документа:
Russian Acad Sci, Siberian Div, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Morozova, T. P.; Малаховский, Александр Валентинович

    Caloric Effects in Some Ferroelectric and Ferroelastic Fluorides, Oxyfluorides and Oxides
/ I. N. Flerov [et al.] // Joint 13th Russia/CIS/Baltic/Japan Symp. on Ferroelectricity and Int. Workshop on Relaxor Ferroelectrics (RCBJSF-IWRF 2016) : book of abstracts. - 2016. - Ст. Invite-6. - References: 4. - The reported study was partially supported by RFBR, research project No. 15-02-02009 a
   Перевод заглавия: Калорические эффекты в некоторых сегнетоэлектрических и сегнетоэластических фторидах, оксифторидах и оксидах


Материалы конференции


Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Gorev, M. V.; Горев, Михаил Васильевич; Mikhaleva, E. A.; Михалева, Екатерина Андреевна; Kartashev, A. V.; Карташев, Андрей Васильевич; Bondarev, V. S.; Бондарев, Виталий Сергеевич; Russia/CIS/Baltic/Japan Symposium on Ferroelectricity(13 ; 2016 ; Jun. ; 19-23 ; Matsue, Japan); International Workshop on Relaxor Ferroelectrics(2016 ; Jun. ; 19-23 ; Matsue, Japan)

    Raman scattering and phase transitions in fluorides with elpasolite structure
/ A. N. Vtyurin [et al.] // Joint 13th Russia/CIS/Baltic/Japan Symp. on Ferroelectricity and Int. Workshop on Relaxor Ferroelectrics (RCBJSF-IWRF 2016) : book of abstracts. - 2016. - Ст. Oral-29. - References: 8
   Перевод заглавия: Комбинационное рассеяние света и фазовые переходы в фторидах со структурой эльпасолита


Материалы конференции


Доп.точки доступа:
Vtyurin, A. N.; Втюрин, Александр Николаевич; Krylov, A. S.; Крылов, Александр Сергеевич; Voronov, V. N.; Воронов, Владимир Николаевич; Goryainov, S. V.; Горяйнов, Сергей Владимирович; Bondarev, V. S.; Бондарев, Виталий Сергеевич; Oreshonkov, A. S.; Орешонков, Александр Сергеевич; Krylova, S. N.; Крылова, Светлана Николаевна; Russia/CIS/Baltic/Japan Symposium on Ferroelectricity(13 ; 2016 ; Jun. ; 19-23 ; Matsue, Japan); International Workshop on Relaxor Ferroelectrics(2016 ; Jun. ; 19-23 ; Matsue, Japan)

    Thermal properties of (NH4)2MeF6·NH4F (Me: Ti, Sn) crystals undergoing transformation between two cubic phases
/ E. I. Pogoreltsev [et al.] // Ferroelectrics. - 2016. - Vol. 501, Is. 1. - P. 20-25, DOI 10.1080/00150193.2016.1198659. - Cited References: 9. - The reported study was partially supported by RFBR, research project No 15-02-02009-a . - ISSN 0015-0193
   Перевод заглавия: Тепловые свойства кристаллов (NH4)2MeF6ћNH4F (Me: Ti, Sn) претерпевающих трансформацию между двумя кубическими фазами

Кл.слова (ненормированные):
Phase transitions -- fluorides -- heat capacity -- entropy -- phase diagram

Аннотация: The heat capacity, thermal expansion, and T-p phase diagrams of (NH4)3TiF7 and (NH4)3SnF7 were studied in wide temperature and pressure ranges. The total excess entropies at successive Pa-3 ↔ P4/mnc ↔ 4/m (Ti) and single Pa-3 ↔ Pm-3m (Sn) phase transitions are close to each other and characteristic for the order–disorder processes. The Pm-3m cubic phase and direct Pa-3 ↔ Pm-3m transformation were found at high pressure in (NH4)3TiF7. The different sign of baric coefficients for phase transition between two cubic phases in (NH4)3TiF7 and (NH4)3SnF7 was supposed due to nonlinear phase boundary with pressure in the latter fluoride.

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Держатели документа:
Kirensky Institute of Physics, Siberian Department of RAS, Krasnoyarsk, Russian Federation
Institute of Engineering Physics and Radioelectronic, Siberian State University, Krasnoyarsk, Russian Federation
Krasnoyarsk State Agrarian University, Krasnoyarsk, Russian Federation
Far Eastern State Transport University, Khabarovsk, Russian Federation
Institute of Chemistry, Far Eastern Department of RAS, Vladivostok, Russian Federation

Доп.точки доступа:
Pogoreltsev, E. I.; Погорельцев, Евгений Ильич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Kartashev, A. V.; Карташев, Андрей Васильевич; Molokeev, M. S.; Молокеев, Максим Сергеевич; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.

    Barocaloric effect in ferroelastic fluorides and oxyfluorides
/ I. N. Flerov [et al.] // Ferroelectrics. - 2016. - Vol. 500, Is. 1. - P. 153-163, DOI 10.1080/00150193.2016.1214525. - Библиогр.: 33. - The reported study was partially supported by the Russian Foundation for Basic Research (RFBR), research project No. 15-02-02009 a. . - ISSN 0015-0193

Кл.слова (ненормированные):
Phase transition -- fluorides -- oxyfluorides -- thermal properties -- barocaloric effect

Аннотация: Using the data about the temperature - pressure phase diagram and the phase transition entropy at ambient and high pressure, intensive and extensive barocaloric effects were analyzed in the region of single and successive order-disorder phase transitions in fluorides and oxyfluorides with the elpasolites-cryolite structure. It was found that hydrostatic as well as chemical pressure are the effective tools to change the entropy of compounds with disordered ionic groups or atoms in structure and to realize the significant intensive and extensive barocaloric effects comparable with the values of baro- and magnetocaloric effects, characteristic for materials, considered as promising solid refrigerants. © 2016 Taylor & Francis Group, LLC.

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Держатели документа:
Kirensky Institute of Physics, Siberian Department of RAS, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation
Krasnoyarsk State Agrarian University, Krasnoyarsk, Russian Federation
Institute of Chemistry, Far Eastern Department of RAS, Vladivostok, Russian Federation

Доп.точки доступа:
Flerov, I. N.; Флёров, Игорь Николаевич; Gorev, M. V.; Горев, Михаил Васильевич; Bogdanov, E. V.; Богданов, Евгений Витальевич; Laptash, N. M.