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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Misyul' S. V., Bovina A. F., Afanas'ev M. L.
Заглавие : Polarization-optical and X-ray diffraction investigations on the symmetry of distorted phases of ammonium cryolite (NH4)(3)ScF6
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 2. - P345-349. - ISSN 1063-7834, DOI 10.1134/1.1131210
Примечания : Cited References: 12
Предметные рубрики: TRANSITIONS
Аннотация: Single-crystal plates of different sections of the (NH4)(3)ScF6 crystal have been investigated by polarization-optical microscopy and X-ray diffraction over a wide temperature range, including the temperatures of two known phase transitions and the third transition found recently. It is established that the symmetry of phases changes in the following sequence: O-h(5) - Fm3m (Z = 4) ↔ C-2h(5) - P12(1)/n1 (Z = 2)↔ C-2h(3) -I12/m1 (Z = 16) ↔ C-i(1) - I (l) over bar (Z = 16). (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Gorev M. V., Grankina V. A.
Заглавие : Phase transitions in RbxK1-xLiSO4 mixed crystals
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1998. - Vol. 40, Is. 7. - P1219-1222. - ISSN 1063-7834, DOI 10.1134/1.1130524
Примечания : Cited References: 12
Предметные рубрики: LOW-TEMPERATURE PHASE
LIKSO4
Аннотация: Structural phase transitions in RbxK1-xLiSO4 mixed crystals (with x varying from 0 to 1) have been studied from the melting point to liquid-nitrogen temperature. Calorimetric (DTA and DSM) data, birefringence and optical polarization measurements were used to construct the full phase (T-x) diagram. It has been established that crystals of most compositions (x less than or equal to 0.95) grow in the hexagonal-trigonal KLiSO4 structure. Replacement of K by the larger Rb atom results in a considerable increase of the region of existence of the P31c phase and expulsion of the high-temperature hexagonal phase. (C) 1998 American Institute of Physics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Isaenko L. I., Pashkov V. M., Pevnev I. V.
Заглавие : Search for and study of phase transitions in some representatives of the APb(2)X(5) family
Разночтения заглавия :авие SCOPUS: Search for and study of phase transitions in some representatives of the APb2X5 family
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2152-2156. - ISSN 1063-7834, DOI 10.1134/S1063783406110217
Примечания : Cited References: 5
Предметные рубрики: CRYSTAL
Аннотация: Single crystals of KPb2Cl5, RbPb2Cl5, and RbPb2Br5 are grown and studied using optical polarization methods. The heat capacity of the crystals is investigated by differential scanning microcalorimetry, and the birefringence and the angle of rotation of the optical indicatrix are measured. The measurements are performed in the temperature range 270-640K. It is found that KPb2Cl5 undergoes a first-order ferroelastic phase transition at T-0 up arrow=530K, T-0 down arrow=528K, and Delta H=1000 +/- 200 J/mol. The transition is accompanied by twinning and a change in symmetry mmm reversible arrow P2(1)/c. The RbPb2Cl5 crystal remains monoclinic up to the melting temperature. The RbPb2Br5 compound belongs to the I4/mcm tetragonal modification and does not undergo structural transformations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Grankina V. A., Kartashev A. V.
Заглавие : A study of the effect of gradual substitution NH4 - Cs on phase transitions in NH4LiSO4 crystals
Разночтения заглавия :авие SCOPUS: A study of the effect of gradual substitution NH4 Cs on phase transitions in NH4LiSO4 crystals
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2002. - Vol. 44, Is. 2. - P379-385. - ISSN 1063-7834, DOI 10.1134/1.1451032
Примечания : Cited References: 22
Предметные рубрики: MIXED-CRYSTALS
TEMPERATURE PHASE
LINH4SO4
BIREFRINGENCE
SULFATE
RAMAN
Аннотация: Solid solutions in the Cs-x(NH4)(1 - x)LiSO4 (0 less than or equal to x less than or equal to 0.35) system are grown and investigated. The birefringence (n(a) - n(b)) and the heat capacity are measured in the temperature range 100-530 K. The (x-T) phase diagram is constructed. It is demonstrated that the substitution of cesium for ammonium in the NH4LiSO4 crystal affects the transition temperatures in such a way that the region of the ferroelectric phase increases and the ferroelastic phase disappears at x 0.22. The character of the high-temperature transition remains unchanged (2beta = 0.24 +/- 0.01 for all compositions), but the birefringence anomaly and enthalpy decrease. As the concentration x increases, the low-temperature transition becomes more similar to a first-order transition: the birefringence jump deltan and the temperature hysteresis DeltaT increase. (C) 2002 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Misyul' S. V., Bovina A. F., Afanas'ev M. L.
Заглавие : Optical and x-ray diffraction investigations of the symmetry of distorted phases of the (NH4)(2)KGaF6 crystal
Разночтения заглавия :авие SCOPUS: Optical and x-ray diffraction investigations of the symmetry of distorted phases of the (NH4)2KGaF6 crystal
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2002. - Vol. 44, Is. 10. - P1967-1971. - ISSN 1063-7834, DOI 10.1134/1.1514789
Примечания : Cited References: 10
Предметные рубрики: THERMODYNAMIC PROPERTIES
TRANSITION
Аннотация: Powders and single-crystal plates of different sections of an (NH4)(2)KGaF6 crystal are investigated using polarized light microscopy and x-ray diffraction over a wide temperature range, including the phase transition temperatures. It is established that the sequence of symmetry changes in the crystal under investigation is as follows: O-h(5)-Fm3m (Z = 4) ↔ C-4h(5)-I114/m (Z = 2) ↔ C-2h(5)-P112(1)/n (Z = 2). (C) 2002 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Misyul' S. V., Bovina A. F., Afanas'ev M. L.
Заглавие : Optical and x-ray studies of the structural phase transition in cryolite (NH4)(3)GaF6
Разночтения заглавия :авие SCOPUS: Optical and x-ray studies of the structural phase transition in cryolite (NH4)3GaF6
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2001. - Vol. 43, Is. 8. - P1594-1597. - ISSN 1063-7834, DOI 10.1134/1.1395110
Примечания : Cited References: 7
Аннотация: Optical polarization and x-ray diffraction studies of powders and single-crystal plates of different cuts of an (NH4)(3)GaF6 crystal are carried out in a broad temperature range, including the phase transition point. The following sequence of symmetry changes is found to occur: O-h(5) - Fm3m (Z = 4)↔ C-i(1) - I (1) over bar (Z = 16). (C) 2001 MAIK "Nauka /Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Kartashev A. V., Mel'nikova S. V.
Заглавие : Calorimetric and optical studies of orthorhombic and cubic CsLiCrO4 crystals
Разночтения заглавия :авие SCOPUS: Calorimetric and optical studies of orthorhombic and cubic CsLiCrO 4 crystals
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2171-2176. - ISSN 1063-7834, DOI 10.1134/S1063783406110242
Примечания : Cited References: 23
Предметные рубрики: PHASE-TRANSITIONS
X-RAY
NH4LISO4
ALPHA
Аннотация: Careful calorimetric and polarization optical studies of a metastable cubic modification of a CsLiCrO4 crystal (space group (F43m)) are performed. Anomalies of the heat capacity indicative of structural distortions at 92.4 and 69.1 K were revealed, and the values of the thermodynamic parameters of the phase transitions were determined. The crystal twinning in the intermediate phase was studied. A comparative analysis of the phase transitions occurring in a series of ALiMO(4) crystals (A=NH4, Cs; M=S, Cr, Mo, W) was performed. First studies of the monotropic structural transformation F43m - Pmcn and the enantiotropic phase transition Pmcn reversible arrow P112(1)/n were carried out using scanning calorimetry, and the thermodynamic parameters of these transitions were determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Isaenko L. I., Mel'nikova S. V., Merkulov A. A., Pashkov V. M., Tarasova A. Y.
Заглавие : Investigation of the influence of gradual substitution K a dagger" Rb on the structure and phase transition in K (x) Rb1-x Pb2Br5 solid solutions
Коллективы : President of the Russian Federation [NSh-1011.2008.2]
Разночтения заглавия :авие SCOPUS: Investigation of the influence of gradual substitution K - Rb on the structure and phase transition in K x Rb1 - X Pb 2Br5 solid solutions
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 3. - P589-592. - ISSN 1063-7834, DOI 10.1134/S1063783409030251
Примечания : Cited References: 5. - This study was supported by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools ( grant no. NSh-1011.2008.2).
Предметные рубрики: CRYSTAL
Аннотация: Single crystals of K (x) Rb1 - x Pb2Br5 solid solutions have been grown and investigated using X-ray diffraction and polarized light microscopy in the temperature range 270-640 K. The regions of existence of the tetragonal (I4/mcm) and monoclinic (P2(1)/c) phases have been determined. It has been demonstrated that the partial introduction of rubidium into KPb2Br5 leads to an increase in the temperature of the ferroelastic phase transition (P2(1)/ca dagger"mmm), so that it approaches the melting temperature. In the solid solutions with x a parts per thousand 0.4-0.5, the temperature region of existence of the orthorhombic phase is narrowed to a parts per thousand 1-2 K. It has been revealed that an increase in the potassium content in the material results in a considerable increase in the incorporation coefficient of Er3+ ions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Kocharova A. G.
Заглавие : Optical Studies of Phase Transitions in the (NH4)(3)VO2F4 Crystal
Коллективы : Russian Federation [NSh-1011.2008.2]; Russian Foundation for Basic Research [06-02-16 102]
Разночтения заглавия :авие SCOPUS: Optical studies of phase transitions in the (NH4) 3VO2F4 crystal
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 3. - P597-600. - ISSN 1063-7834, DOI 10.1134/S1063783409030275
Примечания : Cited References: 7. - This work was supported by the Council on Grants from the President of the Russian Federation (grant NSh-1011.2008.2) and the Russian Foundation for Basic Research (project no. 06-02-16 102).
Предметные рубрики: (NH4)3VO2F4
Аннотация: (NH4)(3)VO2F4 crystals were grown, and polarization-optical studies and measurements of birefringence were conducted on crystal plates of various cuts over a wide temperature range. Phase transitions were detected at temperatures T-1 up arrow = 417 K, T-3 up arrow = 211 K, and T-4 up arrow = 205 K (on heating) and at T-1 down arrow = 413 K, T-3 down arrow = 210 K, and T-4 down arrow = 200 K (on cooling). The transitions are accompanied by anomalies of the birefringence and by twinning. The sequence of changes in the phase symmetry is assumed to be as follows: cubic Fm (3) over barm↔ orthorhombic Immm (I222(1)) monoclinic 112/m)↔ triclinic P (1) over bar. Near temperatures T-2 approximate to 240-250 K, an additional anomaly of the birefringence is observed, with the crystal retaining the orthorhombic symmetry.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bogdanov E. V., Mel'nikova S. V., Pogoreltsev E. I., Molokeev M. S., Flerov I. N.
Заглавие : The structure and phase transitions in oxyfluoride (ND4)2MoO2F4
Место публикации : Solid State Sci.: Elsevier, 2016. - Vol. 61. - P.155-160. - ISSN 12932558 (ISSN), DOI 10.1016/j.solidstatesciences.2016.08.012
Примечания : Cited References: 18. - The authors are grateful to A.G. Kocharova for the synthesis and deuteration of the samples, and to A.A. Sukhovsky and Y.N. Ivanov for the execution of NMR studies to determine the degree of sample deuteration.This study was partially supported by Russian Foundation for Basic Research, project No. 16–32–00201 mol_а.
Ключевые слова (''Своб.индексиров.''): deuterium--heavy water--single crystals--x ray analysis--crystal phasis--deuterations--distorted phasis--oxyfluorides--polarization optics--scanning microcalorimetry--tricritical point--molybdenum oxide
Аннотация: Single crystals of (ND4)2MoO2F4 containing 95% deuterium were produced by repeated recrystallization of (NH4)2MoO2F4 in heavy water. The effect of deuteration on the parameters of successive phase transitions was investigated by differential scanning microcalorimetry and polarization optics. X-ray analysis of the original and distorted phases was performed. It was found that deuteration does not change the sequence of crystal phases typical for (NH4)2MoO2F4, but leads to a shift in the phase transition Cmcm Pnma towards the tricritical point. The mechanism of phase transitions in (ND4)2MoO2F4 was associated with both the ordering and the displacement of atoms. © 2016 Elsevier Masson SAS
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Voronov V. N.
Заглавие : Specific features of the ferroelastic phase transition in CsLiS1-zCrzO4 solid solutions
Разночтения заглавия :авие SCOPUS: Specific features of the ferroelastic phase transition in CsLiS 1-z CrzO4 solid solutions
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 9. - P1786-1790. - ISSN 1063-7834, DOI 10.1134/S1063783406090290
Примечания : Cited References: 11
Предметные рубрики: CSLICRO4 CRYSTAL
X-RAY
CSLISO4
Аннотация: Single crystals of the CsLiS1-zCrzO4 solid solutions (z = 0, 0. 1, 0.4, 0.5, 0.9, 1.0) are grown, optical polarization studies are performed, and the birefringence and the angle of rotation of the optical indicatrix phi(T) are measured. A (z-T) phase diagram is constructed in the temperature range from 77 to similar to 550 K. It is established that substitution of chromium for sulfur has practically no effect on the shape of the optical indicatrix in the initial phase with Pmcn symmetry but produces strong distortions in the monoclinic phase with P112(1)/n symmetry. The unusual shape of the curve phi(T) for compositions with z approximate to 1 is accounted for by the interaction of the polarization-constant tensor components a(ij). No radical differences in the patterns of the ferroelastic phase transition between CsLiSO4 and CsLiCrO4 are revealed (the critical exponent for the transition parameter is beta = 0.33 +/- 0.01). These crystals differ only in the magnitudes of the anomalies, which is associated with the large difference between the ionic radii of sulfur and chromium.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Fokina V. D., Laptash N. M.
Заглавие : Phase transitions in oxyfluoride (NH4)(2)WO2F4
Разночтения заглавия :авие SCOPUS: Phase transitions in oxyfluoride (NH4)2WO 2F4
Место публикации : Phys. Solid State: SPRINGER, 2006. - Vol. 48, Is. 1. - P117-121. - ISSN 1063-7834, DOI 10.1134/S1063783406010239
Примечания : Cited References: 11
Аннотация: (NH4)(2)WO2F4 single crystals are grown, and their polarization-optical, calorimetric, and birefringence properties are studied in the temperature range 90-350K. A first-order structural phase transition is found to occur at T-01 up arrow = 202K with thermal hysteresis of Delta T-01 approximate to 6-12K. The phase transition is accompanied by twinning and modification of the symmetry Cmcm↔ (1) over bar. An additional weak anomaly in the differential scanning calorimeter signal is found at T-02 approximate to 170K. The total thermal effect of both anomalies is = 3200 +/- 400 J/mol and Sigma Delta S-i = 16.5 +/- 2.0 J/mol K. The phase transition at T-01 is of the order-disorder type.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Krylov A. S., Zhogal' A. L., Laptash N. M.
Заглавие : Optical studies of phase transitions in the (NH4)(3)Ti(O-2)F-5 crystal
Коллективы : Russian Federation [NSh-1011.2008.2]; Russian Foundation for Basic Research [06-02-16102]; RFBR Enisei [07-02-096800]
Разночтения заглавия :авие SCOPUS: Optical studies of phase transitions in the (NH4) 3Ti(O2)F5 crystal
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 4. - P817-822. - ISSN 1063-7834, DOI 10.1134/S1063783409040301
Примечания : Cited References: 13. - This work was supported by the Council on Grants from the President of the Russian Federation (project no. NSh-1011.2008.2), the Russian Foundation for Basic Research (project no. 06-02-16102), and RFBR Enisei (project no. 07-02-096800).
Предметные рубрики: (NH4)(3)WO3F3 OXYFLUORIDE
RAMAN-SCATTERING
DISORDER
Аннотация: Polarization-optical study of twinning and measurements of the Raman spectra and birefringence in oxyfluoride (NH4)(3)Ti(O-2)F-5 were carried out over the temperature range 90-350 K. Phase transitions were detected at temperatures T (01) = 266 K (second-order transition) and T (02) = 225 K (first order). It is assumed that the crystal symmetry is changed as follows: Fm3m a dagger" I4/mmm a dagger" I4/m. Anomalies of the spectral parameters are established in the frequency range of internal vibrations of ammonium ions and Ti(O-2)F-5 complexes. An analysis of the results shows that the transition at T (01) is likely due to small shifts of the tetrahedral groups from their position on the triad axis and that the transition at T (02) is due to fluorine-oxygen ordering of Ti(O-2)F-5 complexes.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mel'nikova S. V., Kartashev A. V., Grankina V. A., Flerov I. N.
Заглавие : Investigation of the reconstructive phase transition between metastable (alpha) and stable (beta) modifications of the NH4LiSO4 crystal
Разночтения заглавия :авие SCOPUS: Investigation of the Reconstructive Phase Transition between Metastable (α) and Stable (β) Modifications of the NH4LiSO 4 Crystal
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 8. - P1572-1578. - ISSN 1063-7834, DOI 10.1134/1.1602898
Примечания : Cited References: 13
Предметные рубрики: AMMONIUM LITHIUM-SULFATE
LINH4SO4
TEMPERATURE
Аннотация: Crystals of ammonium lithium sulfate NH4LiSO4 in alpha and beta modifications are studied, and conditions of their nucleation and growth are determined. The alpha modification of NH4LiSO4 and alpha--beta phase transitions are investigated using polarized light microscopy, x-ray diffraction, and differential scanning calorimetry in the temperature range 80-530 K. It is found that, depending on the conditions of growth and storage, there exist two temperature ranges (T(alpha--beta)approximate to340-350 and approximate to440-450 K) in which the crystals can undergo an alpha--beta reconstructive phase transition. The enthalpy of this transformation depends on the symmetry of the final phase. In the former case (340-350 K), the reconstructive phase transition leads to rapid destruction of the sample. In the latter case (440-450 K), the crystal structure undergoes a slow transformation (recrystallization) without noticeable distortions. The results obtained indicate that no structural phase transition occurs in the alpha modification of NH4LiSO4 at 250 K. (C) 2003 MAIK "Nauka/Interperiodica".
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Komogortsev S. V., Denisova E. A., Chekanova L. A., Bukaemskiy A. A., Iskhakov R. S., Mel'nikova S. V., Chizhik M. V.
Заглавие : Magnetic anisotropy of nanocrystalline FeNi(P) columns electroless deposited in polycarbonate membranes
Коллективы : Annual conference on мagnetism and мagnetic мaterials
Место публикации : 58th Annual conference on мagnetism and мagnetic мaterials : abstacts. - 2013. - P.580
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Мельникова, Светлана Владимировна, Лапташ Н. М.
Заглавие : Оптические исследования фазовой (T-x)-диаграммы твердых растворов оксифторидов (NH4)2MoO2F4-Rb2MoO2F4
Место публикации : Физ. тверд. тела: Физико-технический институт им. А. Ф. Иоффе РАН, 2015. - Т. 57, Вып. 6. - С. 1180-1184. - ISSN 0367-3294
Примечания : Библиогр.: 8. - Работа выполнена при финансовой поддержке гранта Президента РФ для поддержки ведущих научных школ РФ (НШ-924.2014.2).
Аннотация: Выращены монокристаллы твердых растворов (NH4)2-xRbxMoO2F4 (включая индивидуальный комплекс Rb2MoO2F4). Проведено их исследование методами поляризационной оптики. Измерено двупреломление Δn(T) в интервале температур 100-400 K. Построена полная фазовая (T-x)-диаграмма твердых растворов.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Kartashev A. V., Gorev M. V., Bogdanov E. V., Mel'nikova S. V., Molokeev M. S., Pogoreltsev E. I., Laptash N. M.
Заглавие : Thermal, structural, optical, dielectric and barocaloric properties at ferroelastic phase transition in trigonal (NH4)2SnF6: A new look at the old compound
Место публикации : J. Fluor. Chem.: Elsevier, 2016. - Vol. 183. - P.1-9. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2015.12.010
Примечания : Cited References: 25. - The reported study was partially supported by RFBR, research project No. 15-02-02009a.
Предметные рубрики: Heat-capacity
Ammonium
(NH4)3TiF7
Pressure
Ключевые слова (''Своб.индексиров.''): 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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Anistratov A. T., Mel'nikova S. V., Zinenko V. I., Shabanova L. A., Beznosikov B. V.
Заглавие : Birefringence, twinning and structural phase transitions in ABCl3 single crystals
Коллективы : International meeting on ferroelectricity
Место публикации : Ferroelectrics. - 1978. - Vol. 20, Spesial issue. - P.305-307. - DOI 10.1080/00150197808237245
Аннотация: The temperature investigations of birefringence, twinning and elasticity of CsPbCl3, CsSrCl3, TlMnCl3, RbCdCl3, CsCaCl3 and RbMnCl3, were carried out. A group-theoretical analysis is made and the description of phase transitions is given.
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19.

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.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Денисова, Елена Александровна, Исхаков, Рауф Садыкович, Чеканова, Лидия Александровна, Мельникова, Светлана Владимировна
Заглавие : Синтез и исследование магнитных композиционных материалов на основе пористых матриц с различной морфологией пор
Место публикации : Фазовые переходы, межфазные границы и наноматериалы: электронный журнал. - 2014. - Вып. 3. - С. 92-94. - ISSN 2073-0373
Примечания : Библиогр.: 5 назв. - Работа выполнена при поддержке РФФИ проект № 13-03-00476
Ключевые слова (''Своб.индексиров.''): нанокластеры
Аннотация: Методом химического осаждения синтезированы композиционные материалы на основе различных матриц (пористый кремний, трековые мембраны, активированный уголь, МСМ-41) с порами, заполненными частицами сплава Со(Р). Исследованы структурные и магнитные характеристики композитов. Установлено, что морфология пор определяет величину поля локальной анизотропии и коэрцитивной силы композитов.
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