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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Kartashev A. V., Gorev M. V., Bogdanov E. V., Bondarev V. S.
Заглавие : Thermal, dielectric and barocaloric properties of NH4HSO4 crystallized from an aqueous solution and the melt
Место публикации : Solid State Sci.: Elsevier, 2017. - Vol. 67. - P.1-7. - ISSN 12932558 (ISSN), DOI 10.1016/j.solidstatesciences.2017.03.004
Примечания : Cited References: 27. - We are grateful to T.N. Davydova for the preparation of the sample from an aqueous solution and Dr. M.S. Molokeev for X-ray characterization of the samples. The study was partially supported by the Russian Foundation for Basic Research, research project No. 16-32-00092 mol_а.
Ключевые слова (''Своб.индексиров.''): entropy--ferroelectric--phase diagram--phase transition--thermal and dielectric properties
Аннотация: A study of heat capacity, thermal dilatation, permittivity, dielectric loops and susceptibility to hydrostatic pressure was carried out on quasi-ceramic samples of NH4HSO4 obtained from an aqueous solution as well as the melt. The main parameters of the successive P21/c (T1) ↔ Pc (T2) ↔ P1 phase transitions did not depend on the method of preparation of the samples, and were close to those determined in previous studies of single crystal and powder, except for the sign and magnitude of the baric coefficient for T2. Direct measurements of the pressure effect on the permittivity and thermal properties showed dT2/dp = −123 K·GPa−1, which is consistent in terms of magnitude and sign with the baric coefficient evaluated using dilatometric and calorimetric data in the framework of the Clausius-Clapeyron equation. Thus, the temperature region of the ferroelectric Pc phase existence is extended under pressure. A strong decrease in the entropy jump at the Pc ↔ P1 transformation with an increase in pressure, and the linear dependence of T2 on pressure, indicate that an increase in pressure shifts this phase transition towards the tricritical point on the T–p phase diagram. A significant barocaloric effect was found in the region of the Pc ↔ P1 phase transition.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pogoreltsev E. I., Bogdanov E. V., Kartashev A. V., Molokeev M. S., Flerov I. N., Laptash N. M.
Заглавие : Thermal properties of (NH4)2MeF6·NH4F (Me: Ti, Sn) crystals undergoing transformation between two cubic phases
Место публикации : Ferroelectrics: Taylor and Francis, 2016. - Vol. 501, Is. 1. - P.20-25. - ISSN 00150193 (ISSN), DOI 10.1080/00150193.2016.1198659
Примечания : Cited References: 9. - The reported study was partially supported by RFBR, research project No 15-02-02009-a
Ключевые слова (''Своб.индексиров.''): 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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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yurev I. O., Aleksandrovsky A. S., Kamaev D. N., Polkovnikov A. A., Grigorchenko V. M., Yarovenko A. A., Zelenaya A. E., Parfenova M. D., Andreev O. V.
Заглавие : The Sm2S3-X-SmS-Sm2O2S refractory system: thermal analysis, phase diagram, and properties of the phases
Колич.характеристики :17 с
Место публикации : J. Therm. Anal. Calorim. - 2024. - Vol. 149, Is. 5. - P.2057-2073. - ISSN 13886150 (ISSN), DOI 10.1007/s10973-023-12792-z. - ISSN 15882926 (eISSN)
Примечания : Cited References: 90. - The authors thank Prof. P.P. Fedorov, Chief Researcher of Prokhorov Institute of General Physics, Russian Academy of Sciences, for scientific advices. The authors thank N.I. Lozhkin, engineer of the Department of Inorganic and Physical Chemistry, Tyumen State University for the technical support of the visual thermal analysis setup. The authors thank N.A. Shulaev, research engineer of the Center for Nature-Inspired Engineering, Tyumen State University, for determining the elemental composition of samples by scanning electron microscopy. The authors thank I.V. Palamarchuk, research engineer of the Center for Collective Use "Rational Nature Management and Physical and Chemical Research" of the Tyumen State University, for measuring the diffuse reflectance spectra. The authors thank Doctor of Philology O.V. Trofimova, Professor at the Institute of Social Sciences and Humanities of the Tyumen State University, for her advices on academic writingThis study was funded by the Russian Science Foundation, Project No. 23–23-00488 “Search for EMF generation conditions in gradient ceramics of samarium monosulfide (SmS)”
Аннотация: Samarium monosulfide, a strain gauge and barometric material, exists in equilibrium with Sm3S4 and Sm2O2S in the S-Sm–O system. Therefore, studying phase equilibria in the refractory Sm2S3-X-SmS-Sm2O2S system is a scientifically interesting task. In this system, 49 samples were synthesized and studied by powder XRD, differential scanning calorimetry, visual thermal analysis, and microstructural analysis. Melting points of Sm3S4, SmS, and Sm2O2S compounds were determined. Eutectic diagrams of Sm3S4-Sm2O2S, SmS-Sm2O2S, SmS-Sm3S4 systems were constructed. Temperatures and compositions of the binary eutectic points were determined. Fusion enthalpies for Sm3S4, SmS, and Sm2O2S phases were estimated using the Schröder–Le Chatelier equation. The liquidus lines were calculated using second-degree polynomials and Redlich–Kister model. Coordinates of the ternary eutectic point in the Sm3S4-SmS-Sm2O2S system were calculated using the cutting-plane method and the Scheffé method. The calculated compositions of ternary eutectic points were averaged at one most probable point, in accordance with the data on the samples microstructure. The experimental temperature of the ternary eutectic point coincides with the calculated values within the margin of error. Positions of eutectic valleys and approximate positions of isotherms in the system were established. Thermodynamic parameters of the α-Sm2S3 → γ-Sm2S3 polymorphic transition and the dependence of the Sm2S3-X composition on heat treatment conditions were determined. According to the scanning electron microscopy data, the approximate composition of the crystallized from the melt Sm2S3 sample is Sm2S2.95. The Sm10S14O phase decomposes at 1470 ± 15 °C in the course of a solid-phase reaction. The phase diagram of the Sm2S3-X-Sm2O2S system was revisited. Optical band gaps of Sm10S14O and Sm2O2S phases were determined. The Sm10S14O compound was optically characterized for the first time; its direct and indirect optical bandgaps were found equal to 2.48 and 2.37 eV, respectively. The determined direct and indirect optical bandgaps of Sm2O2S (4.4 eV and 3.95 eV, respectively) agree with the earlier measurements, thus confirming the accuracy of the chosen synthesis procedures.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grossman, Victoria G., Bazarova J. G., Molokeev M. S., Bazarov B. G.
Заглавие : Thallium ionic conductivity of new thallium indium hafnium molybdate ceramics
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [0339-2016-0007]; [18-08-00799]; [18-03-00557]
Место публикации : Ionics. - 2020. - Vol. 26. - P.6157-6165. - ISSN 0947-7047, DOI 10.1007/s11581-020-03739-7. - ISSN 1862-0760(eISSN)
Примечания : Cited References: 60. - This study was carried out within the state assignment of FASO of Russia (Theme No 0339-2016-0007) as well was supported by RFBR Grants 18-08-00799 and 18-03-00557
Предметные рубрики: POSITIVE ELECTRODE MATERIAL
CRYSTAL-STRUCTURE
TRIPLE MOLYBDATE
Аннотация: In the process of studying the system Tl2MoO4–In2(MoO4)3–Hf(MoO4)2, a new thallium indium hafnium molybdate was found. The crystal structure of the molybdate Tl5InHf(MoO4)6 was determined in the centrosymmetric space group R3¯c (a = 10.63893 (5) Å, c = 38.1447(3) Å; V = 3739.04 (4) Å3, Z = 6). The structure is a three-dimensional framework consisting of alternating (Hf,In)O6-octahedra connected by МоО4-tetrahedra. Each octahedron has common vertices with tetrahedra. The atoms arranged in this way form channels extended along with the a and b axes, in which thallium atoms are located. The conductivity behavior of Tl5InHf(MoO4)6 ceramics was studied in the temperature range from 300 to 870 K. The conductivity of the heavy cations of thallium is activated with increasing temperature.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grigorchenko V.M., Molokeev M. S., Oreshonkov A. S., Aleksandrovsky A. S., Kertman A.V., Abulkhaev M.U., Mereshchenko A.S., Yurev I.O., Shulaev N.А., Kamaev D.N., Elyshev A.V., Andreev O.V.
Заглавие : Synthesis and properties of the NdSF compound, phase diagram of the NdF3–Nd2S3 system
Колич.характеристики :9 с
Место публикации : J. Solid State Chem. - 2024. - Vol. 333. - Ст.124640. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2024.124640. - ISSN 1095726X (eISSN)
Примечания : Cited References: 48. - This research was funded by the Tyumen Oblast Government as part of the West-Siberian Interregional Science and Education Center’s project No. 89-DON (3)The studies ab initio simulation of electron band structure, analysis of optical properties, XRD analysis was partially supported by "Priority-2030" program for the Siberian Federal University, and the state assignment of Kirensky Institute of Physics
Аннотация: The NdF3–Nd2S3 system attracts attention of researchers due to the possibility of using LnSF compounds (Ln = rare earth element) as possible new p- and n-type materials. The samples of this system were synthesized from NdF3 and Nd2S3. The NdSF compound belongs to the PbFCl structural type, P4/nmm space group, unit cell parameters: a = 3.9331(20) Å, c = 6.9081(38) Å. The experimentally determined direct and indirect NdSF bandgaps are equal to 2.68 eV and 2.24 eV. The electronic band structure was calculated via DFT simulation. The NdSF compound melts congruently at T = 1385 ± 10°С, ΔНm = 40.5 ± 10 kJ/mol, ΔS = 24.4 ± 10 J/mol. The NdSF microhardness is 455 ± 10 HV. Five phase transformations in the NdF3–Nd2S3 system were recorded by DSC; their balance equations were derived. The liquidus of the system calculated from the Redlich–Kister equation is fully consistent with the DSC data.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shtykova M. A., Molokeev M. S., Zakharov B. A., Selezneva N. V., Aleksandrovsky A. S., Bubnova R. S., Kamaev D. N., Gubin A. A., Habibullayev N. N., Matigorov A. V., Boldyreva E. V., Andreev O. V.
Заглавие : Structure and properties of phases in the Cu2-ХSe-Sb2Se3 system. The Cu2-XSe-Sb2Se3 phase diagram
Место публикации : J. Alloys Compd. - 2022. - Vol. 906. - Ст.164384. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2022.164384
Примечания : Cited References: 111. - The research was supported for R.S. Bubnova by the Ministry of Science and Higher Education of the Russian Federation within the scientific tasks of the Institute of Silicate chemistry (Russian Academy of Sciences) [project number 0097-2019-0013]. The equipment of Research and Education Center "Molecular design and ecologically safe technologies" (Novosibirsk State University) was used for single-crystal X-ray diffraction experiments. BAZ and EVB acknowledge support by the Ministry of Science and Higher Education, project AAAA-A21-121011390011-4
Аннотация: The phase diagram of the Cu2−XSe-Sb2Se3 system is revisited to clarify ambiguity/disagreement in previously reported data. Ternary Cu3SbSe3 and CuSbSe2 compounds were obtained. In order to confirm that the phases have been identified correctly, crystal structures were solved, and the energy band gaps measured. For the sample containing 75 mol% Sb2Se3 and 25 mol% Cu1.995Se the temperature range of the stability of the high-temperature CuSb3Se5 phase was determined for the first time. This phase is formed at 445 °С, decomposes following a peritectic reaction at 527 °С, and can be quenched. A high-temperature X-ray diffraction study of a sample containing 75 mol% Sb2Se3 and 25 mol% Cu2Se allowed us to measure the thermal expansion of the CuSbSe2 and Sb2Se3 phases present in the sample. The anisotropy of thermal expansion of CuSbSe2 is similar to that of As2S3 (orpiment); thermal expansion of Sb2Se3 is similar to that of AsS (realgar). The 6 balance equations of the invariant phase transformations involving all the ternary compounds existing in the Cu2−XSe-Sb2Se3 system were suggested for the first time. The temperature and the enthalpies of all these transformations were measured. A phase diagram of the Cu2−XSe-Sb2Se3 system was found for the first time in all the range of concentrations at temperatures from ambient to the complete melting. This diagram takes into consideration the phase equilibria that involve all the ternary compounds that are possible in this system. The liquidus of the Cu2−XSe-Sb2Se3 system was calculated according to Redlich-Kister equation; it agrees with the experimental data within 1–17 °С.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shinkorenko A. S., Zinenko V. I., Pavlovskii M. S.
Заглавие : Magnetic, electronic, and optical properties of the tetraborates NiB4O7 and CoB4O7 in three structural modifications
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-32-00919 mol_a]
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 3. - P.468-476. - ISSN 1063-7834, DOI 10.1134/S1063783421030173. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 22. - This study was supported by the Russian Foundation for Basic Research, project no. 18-32-00919 mol_a
Аннотация: The physical properties of the NiB4O7 and CoB4O7 tetraborate compounds in three structural modifications with the sp. gr. Pbca, Cmcm, and P6522 have been calculated using the density functional theory in the VASP software package. The pressure dependences of the enthalpy of the compounds in the investigated structural modifications have been calculated. The calculated electron densities of states and band structures showed that the compounds under study in all the considered modifications are dielectrics with a band gap of 3–4 eV. The calculation of the magnetic exchange constants in the Heisenberg model have shown qualitative agreement with the experiment.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Osseni S. А., Andreev P. O., Polkovnikov A. A., Zakharov B. A., Aleksandrovsky A. S., Abulkhaev M. U., Volkova S. S., Kamaev D. N., Kovenskiy I. M., Nesterova N. V., Kudomanov M. V., Andreev O. V.
Заглавие : Properties of oxysulfide phases and phase diagram of the Nd2S3–Nd2O3 system
Место публикации : J. Solid State Chem. - 2022. - Vol. 314. - Ст.123438. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2022.123438
Примечания : Cited References: 51. - This research was funded by the Tyumen Oblast Government , as part of the West-Siberian Interregional Science and Education Center's project No. 89-DON (3)
Аннотация: We have determined the thermal characteristics and optical properties of the sulfide and oxysulfide phases in the Nd2S3 - Nd2O3 system. A congruent melting peak at temperature 1801 ​± ​4.9 ​°C with ΔH ​= ​65.2 ​± ​6.7 ​kJ/mol was detected for the Nd2S3 compound by the DSC method. The characteristics of the α-Nd2S3 → γ-Nd2S3 polymorphic transition are t ​= ​1183 ​± ​1.8°С, and ΔH ​= ​7.5 ​± ​0.3 ​kJ/mol. The γ-Nd2S3 phase obtained upon cooling during annealing at 800 ​°C is retained for up to 30 ​h, and then the γ-Nd2S3 → α-Nd2S3 transition occurs within 20 ​h. The microhardness of the phases is: α-Nd2S3 H ​= ​451 ​± ​4 HV; γ-Nd2S3 H ​= ​531 ​± ​4 HV. It was found by the TG method that the Nd10S14O phase thermally dissociates at temperatures above 1400 ​°C. The mass loss is 0.5 mass % at 1580 ​°C and 1.0 mass % at 1620 ​°C, but the samples remain single-phase ones after cooling. However, two impurity phases γ-Nd2S3-X and Nd2O2S appear in the Nd10S14O samples treated at temperatures above 1620 ​± ​20 ​°C. For samples of the Nd10S14O phase annealed in an argon atmosphere at temperatures of 1050, 1400, 1580 ​°C, a regular decrease in the unit cell parameters and optical band gap was recorded: 1050 ​°C a ​= ​15.06291(28), c ​= ​19.97864(35), Eg ​= ​2, 63 ​eV, 1400 ​°C a ​= ​15.04779(36), c ​= ​19.97160(44), Eg ​= ​2.64 ​eV; 1580 ​°C a ​= ​15.03532(48), c ​= ​19.94984(60), Eg ​= ​2.51 ​eV. The microhardness of Nd10S14O is H ​= ​549 ​± ​10 HV. The Nd2O2S phase has H ​= ​593 ​± ​4 HV, Eg ​= ​4.28 ​eV. The phase diagram of the Nd2S3 - Nd2O3 system from 1000 ​°C to the melt was constructed. The Nd2O2S phase melts congruently at 2050 ​± ​30 ​°C. Eutectics with coordinates 23 ​mol. % Nd2O3 (0.3484 Nd10S14O ​+ ​0.6516 Nd2O2S), t ​= ​1553 ​± ​1.8°С; ΔH ​= ​187 ​± ​19 ​J/g; 82 ​mol. % Nd2O3; (0.54 Nd2O2S ​+ ​0.46 Nd2O3), t ​= ​1970 ​± ​30°С were obtained. The liquidus of the Nd2S3 - Nd2O3 system was built according to DSC data and calculated using the Redlich-Kister equation. The melting enthalpy of Nd2O2S ΔH ​= ​67 ​kJ/mol was calculated using the Schroeder equation.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grossman V. G., Molokeev M. S., Bazarov B. G., Bazarova J. G.
Заглавие : Potassium and thallium conductors with a trigonal structure in the M2MoO4–Cr2(MoO4)3–Hf(MoO4)2 (M = K, Tl) systems: Synthesis, structure, and ionic conductivity
Место публикации : J. Alloys Compd. - 2021. - Vol. 873. - Ст.159828. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2021.159828
Примечания : Cited References: 62. - The work was supported by Basic Project of BINM SB RAS № 0273-2021-0008 . Research was conducted using equipment of the CCU BINM SB RAS (Ulan-Ude, Russia). Structural analysis of materials in this study was partly supported by the Research Grant No. 075-15-2019-1886 from the Government of the Russian Federation
Аннотация: The triple molybdates M5CrHf(MoO4)6 (M = K, Tl) and TlCrHf0.5(MoO4)3 were found upon studying the corresponding ternary molybdate systems M2MoO4–Cr2(MoO4)3–Hf(MoO4)2 (M = K, Tl) in the subsolidus region using X-ray powder diffraction. The crystal structures of M5CrHf(MoO4)6 (M = K, Tl) and TlCrHf0.5(MoO4)3 are refined by Rietveld method. M5CrHf(MoO4)6 (M = K, Tl) crystallizes in space group Rc with unit cell parameters: a = b = 10.45548 (5), c = 37.24614 (3) Å, V = 3526.14 (4) Å3, Z = 6 for K5CrHf(MoO4)6 and a = b = 10.53406 (12), c = 37.6837 (5) Å, V = 3621.39 (9) Å3, Z = 6 for Tl5CrHf(MoO4)6. TlCrHf0.5(MoO4)3 crystallizes in space group R with unit cell parameters: a = b = 12.9710 (2), c = 11.7825 (2) Å, V = 1716.78 (6) Å3, Z = 6. The thermal stability and electrical conductivity of the new compounds were investigated. Electrical conductivity measurements gave high values for the triple molybdates M5CrHf(MoO4)6 (M = K, Tl) (σ = 5.22 × 10−4 S / cm for K5CrHf(MoO4)6, σ = 1.1 × 10−2 S / cm for Tl5CrHf(MoO4)6 at 773 K) and relatively low values for the triple molybdate TlCrHf0.5(MoO4)3 (σ = 4.42 × 10−6 S / cm at 773 K).
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fokina V. D., Gorev M. V., Kocharova A. G., Flerov I. N., Pogoreltsev E.I.
Заглавие : Phase transitions and thermodynamic properties of (NH4)(3)VO2F4 cryolite
Место публикации : Solid State Sci. - 2009. - Vol. 11, Is. 4. - P.836-840. - ISSN 1293-2558, DOI 10.1016/j.solidstatesciences.2008.11.004
Примечания : Cited Reference Count: 17. - Гранты: The authors are grateful to Dr. SM. Mel'nikova for the permission to use the unpublished results.; This work was supported by the Russian Foundation for Basic Research (project 06-02-16102).Финансирующая организация: Russian Foundation for Basic Research [06-02-16102]
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
(NH4)(3)TIOF5
CS
(NH4)(3)WO3F3
DIFFRACTION
(NH4)3VO2F4
ELPASOLITE
METALS
RB
Ключевые слова (''Своб.индексиров.''): oxyfluorides--phase transition--calorimetry--phase diagram--ferroelectricity--calorimetry--ferroelectricity--oxyfluorides--phase diagram--phase transition--calorimetry--ferroelectricity--halide minerals--phase diagrams--sugar (sucrose)--thermodynamic properties--calorimetric measurements--cubic phase--first-order phase transitions--heat capacities--oxyfluorides--phase transition temperatures--pressure dependences--structural transformations--temperature ranges--phase transitions
Аннотация: Calorimetric measurements performed in a wide temperature range on (NH4)(3)VO2F4 have shown the presence of four heat capacity anomalies at T-1 = 438 K, T-2 = 244 K, T-3 = 210.2 K, T-4 = 205.1 K associated with the first order phase transitions. In accordance with the permittivity behavior, the structural transformations are of nonferroelectric nature. Pressure dependence of the phase transition temperatures has been studied by DTA under pressure. The entropy of phase transitions is analyzed mainly in the framework of the orientational disordering of NH4+ and VO2F43- ions in a cubic phase. (C) 2008 Elsevier Masson SAS. All rights reserved.
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