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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bondarev V. S., Mikhaleva E. A., Gorev M. V., Molokeev M. S., Bogdanov E. V., Cherepakhin A. V., Flerov I. N.
Заглавие : Phase transitions, baro- and piezocaloric effects in single crystal and ceramics of ferroelectric NH4HSeO4
Колич.характеристики :10 с
Место публикации : Solid State Sci. - 2024. - Vol. 148. - Ст.107440. - ISSN 12932558 (ISSN), DOI 10.1016/j.solidstatesciences.2024.107440. - ISSN 18733085 (eISSN)
Примечания : Cited References: 45. - The study was supported by the grant of the Russian Science Foundation No. 23-22-10014, Krasnoyarsk Regional Science Foundation, https://rscf.ru/en/project/23-22-10014/
Аннотация: A study of heat capacity, thermal dilatation and sensitivity to hydrostatic and uniaxial pressure was carried out on single-crystal and ceramic samples of NH4HSeO4. The main parameters of low-temperature successive phase transitions B2 (T1) ↔ incommensurate IC (T2) ↔ ferroelectric P1 (T3) ↔ non-ferroelectric did not depend on the type of samples. The behavior of the volumetric strain and the results of direct measurements of T3(p) contributed to the resolution of the longstanding problem associated with the ambiguity of the sign of the corresponding volumetric baric coefficient. The role of thermal expansion anisotropy in the formation of the piezocaloric effect (PCE) near the ferroelectric phase transition at T3 has been studied. Due to the strong difference in the linear baric coefficients, the main contribution to the barocaloric effect (BCE) comes from the inverse intensive and extensive PCE associated with the a-axis. Compared to a single crystal, ceramics demonstrate lower BCE values, which, however, exist in a wider temperature range, which leads to close values of integral caloric parameters. The strong decrease in both BCE and PCE at low-temperature transformations in NH4HSeO4 compared to the ferroelectrics NH4HSO4 and NH4NH4SO4 is associated with a small change in entropy during three low-temperature phase transitions, ΣΔSi = 2.52 J/mol∙K, which is a consequence of a high degree of structural ordering in selenate as a result of a high-temperature transformation at T0 between the superionic and B2 phases, accompanied by a giant change in entropy, ΔS0≈Rln21.
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2.

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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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen K., Gao P., Zhang Z., Ma Y., Luo Z., Molokeev M. S., Zhou Zh., Xia M.
Заглавие : Zero-thermal-quenching broadband yellow-emitting Bi3+-activated phosphors based on metal to metal charge transfer
Колич.характеристики :9 с
Место публикации : J. Alloys Compd. - 2024. - Vol. 986. - Ст.174112. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2024.174112. - ISSN 18734669 (eISSN)
Примечания : Cited References: 52. - The authors would like to gratefully acknowledge funds from the National Natural Science Foundation of China (Grant No. 51974123), the Key R & D Projects in Hunan Province (2021SK2047 and 2022NK2044), the Wangcheng Science and Technology Plan (KJ221017) and the Science and Technology Innovation Program of Hunan Province (2022WZ1022). The work was supported by the Ministry of Science and Higher Education of the Russian Federation as part of World-class Research Center program: "Advanced Digital Technologies", contract no. 075-15-2020-935. Superior Youth Project of the Science Research Project of Hunan Provincial Department of Education (22B0211)
Аннотация: Bi3+-activated phosphors have been proven to have potential applications foreground in white light-emitting diodes (WLED), plant growth lamps and temperature sensing. Therefore, it is urgent to exploit high-efficiency Bi3+-activated phosphors. Herein, a novel broadband yellow-emitting phosphor Ba2GdGaO5:Bi3+ with high internal quantum efficiency (IQE = 77%) was obtained based on metal to metal charge transfer (MMCT) between Bi3+ ground state and Gd3+ excited states. The photoluminescence excitation (PLE) spectrum and photoluminescence (PL) spectrum range from 225 nm to 400 nm and 400 nm to 700 nm, respectively, which can avoid the reabsorption phenomenon efficiently. Besides, Ba2GdGaO5:Bi3+ has superior thermal stability and it shows zero-thermal-quenching at 150 °C. The K+ doping hardly changes the thermal stability and can improve the PL intensity to 133.1% when the K+ concentration is 2%. Finally, a phosphor-convert WLED (pc-WLED) was simply synthesized by Ba2GdGaO5:Bi3+ and BaMgAl10O17:Eu2+ (BAM:Eu2+) phosphors. The doping of Eu3+ can significantly enhance the color rendering index (CRI, from 88.1 to 91.5) and reduce the correlated color temperature (CCT, from 4911 K to 4014 K). The above experimental results demonstrated that the phosphor has great application prospect in WLED.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Su B., Molokeev M. S., Chen R., Zhang T.
Заглавие : Near-unity PLQY and high anti-thermal quenching red luminescence from one-dimensional hybrid manganese chloride for efficient and stable white light-emitting diodes
Место публикации : J. Mater. Chem. C. - 2024. - Article in press. - ISSN 20507526 (ISSN), DOI 10.1039/D4TC01477D. - ISSN 20507534 (eISSN)
Примечания : Cited References: 46
Аннотация: The discovery of novel Mn2+-based metal halides with excellent luminescence properties and thermostability is particularly of great importance for solid-state lighting (SSL). Herein, a novel one-dimensional hybrid manganese chloride (TMA)MnCl3 of a hexagonal system with a P63/m space group is synthesized via a simple saturation crystallization method. Under 443 nm excitation, (TMA)MnCl3 single crystals exhibit a strong broad-band red emission peak at 645 nm originating from the 4T1 → 6A1 transition of Mn2+ ions with a full width at half maximum of 99 nm and a photoluminescence quantum yield (PLQY) of 98.6%. Moreover, (TMA)MnCl3 shows a high anti-thermal quenching behavior, and the integrated PL intensity still retains 100% of the initial intensity measured at 300 °C, caused by the high structural rigidity. Benefiting from its strong blue light excitation, high PLQY, and excellent thermal stability, a stable white light-emitting diode device is fabricated by combining a 465 nm blue LED chip, green-emitting Lu3Al5O12:Ce3+ and the (TMA)MnCl3 red phosphor with a high color rendering index of 94.3% and a correlated color temperature of 3995 K. This work develops a novel hybrid manganese chloride red-emitter and paves a new path to explore high-performance phosphors excited by blue light for SSL.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Habibullayev N. N., Burkov A. T., Novikov S. V., Yurev I. O., Aleksandrovskiy A. S., Zakharova A. D., Shulaev N. A., Denisenko Yu. G., Andreev O. V.
Заглавие : Regularity of thermal characteristics, thermoelectric properties of EuLnCuSe3 compounds (Ln = La–Lu)
Колич.характеристики :12 с
Место публикации : Eur. Phys. J. Plus. - 2024. - Vol. 139, Is. 5. - Ст.412. - ISSN 21905444 (eISSN), DOI 10.1140/epjp/s13360-024-05155-6
Примечания : Cited References: 53. - This 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)"). A.S.A is grateful for the state assignment funding from Kirensky Institute of Physics
Аннотация: The temperatures and enthalpies of the decomposition of EuLnCuSe3 compounds (Ln = La–Lu) are determined for the first time as functions of the Ln3+ ionic radius (rLn3+). The EuLnCuSe3 compounds with Ln = La and Ce decompose in the course of a solid-phase reaction to form EuSe, Ln2Se3, and Cu2−xSe, whereas those with Ln = Tb, Dy, Ho, Tm, and Lu melt incongruently to form EuSe and a melt, for example, Tdecay = 1175 K and ΔHdecay = 2.66 kJ/mol for EuLaCuSe3, while Tmelt = 1576 K and ΔHmelt = 2.69 kJ/mol for EuTbCuSe3. When plotted as functions of rLn3+, the temperatures of thermal effects of these compounds exhibit a periodic dependence and a tetrad effect. The temperature dependence of electrical resistivity and that of the Seebeck coefficient are measured from 300 to 600 K. It is shown that the studied compounds are p-type semiconductors with bandgaps ranging from 0.4 to ~ 1 eV.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Visotin M. A., Sosedkin, Oleg A., Eremkin, Egor V.
Заглавие : MD investigations of of heat flow throw interfaces in 1D systems
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2023. - Vol. 16, Is. 3. - P.385-396. - ISSN 19971397 (ISSN); Журн. СФУ. Матем. и физ. - ISSN 23136022 (eISSN)
Примечания : Cited References: 26
Аннотация: Molecular dynamic calculations (MD) of heterogeneous 1D periodical systems are presented. It is proposed the new technique of direct calculations of thermal conductivity, where there is only one thermostat in one piece of unit cell as well as another piece where artificial friction forces act on atoms. With the help of this scheme, calculations of 1D heterogeneous systems having regions with atoms of different atomic masses are presented. It is shown that the difference in atomic masses in adjacent regions of the systems leads to a significant temperature jump at interfaces between these regions. This temperature jump exists independently of the mass ratio on both sides of the interface.The reasons for these jumps are discussed. It is also shown that, by changing the alternation of regions with different masses of atoms, it is possible to reduce the total thermal conductivity of the system by several times. On the base of these results, we can hope that for three-dimensional structures also, the thermal conductivity can be significantly reduced.Представлены молекулярно-динамические расчеты (МД) гетерогенных одномерных периодических систем. Предлагается новая методика прямых расчетов теплопроводности, при которой в одном элементе элементарной ячейки находится только один термостат, а в другом элементе действуют силы искусственного трения на атомы. С помощью этой схемы представлены расчеты одномерных гетерогенных систем, имеющих области с атомами разной атомной массы. Показано, что различие атомных масс в соседних областях систем приводит к значительному скачку температуры на границах раздела между этими областями. Этот скачок температуры существует независимо от отношения масс по обе стороны от границы раздела. Обсуждаются причины этих скачков. Также показано, что, изменяя чередование областей с разной массой атомов, можно в несколько раз уменьшить общую теплопроводность системы. На основании этих результатов можно надеяться, что и для трехмерных структур теплопроводность может быть значительно снижена.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gao, Huabo, Molokeev M. S., Chen, Qi, Min, Xin, Ma, Bin
Заглавие : Novel AMoO4:Eu3+ (A = Ca and Ba) optical thermometer: Investigation of effect of local ionic coordination environment on optical performance and temperature measurement sensitivity
Место публикации : Ceram. Int. - 2023. - Vol. 49, Is. 16. - P.26803-26810. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2023.05.217. - ISSN 18733956 (eISSN)
Примечания : Cited References: 52. - The work was supported by the program of Science and Technology International Cooperation Project of Qinghai province (No. 2022-HZ-807) and the National Natural Science Foundation of China (Grant No. 51802172), and was carried out within the framework of the Strategic Academic Leadership Program “Priority-2030′′ for the Siberian Federal University
Аннотация: A range of Eu3+-doped AMoO4 (A = Ca and Ba) phosphors were successfully synthetized, and their crystal structures, optical performance, and temperature measurement sensitivities were investigated in detail. Peak doping concentration of CaMoO4:Eu3+ phosphor was 0.18, while peak doping concentration of BaMoO4:Eu3+ phosphor may be greater than 0.18. Then, temperature-dependent photoluminescence emission spectra of representative CaMoO4:0.09Eu3+ and BaMoO4:0.03Eu3+ phosphors were recorded. CaMoO4:0.09Eu3+ phosphor exhibited abnormal thermal quenching, which was attributed to defects caused by heterovalent substitution of ions and increase in the temperature, and good thermal stability. Finally, the possibility of using both phosphors as optical thermometers was discussed, which exhibited good temperature sensitivity. However, CaMoO4:0.09Eu3+ phosphor exhibited two peak absolute (Sa, 1.28 %K−1 and 1.39 %K−1) and relative sensitivities (Sr, 1.21 %K−1 and 1.20 %K−1). In addition, variation trend of Sr value with temperature was considerably peculiar. Two optimum Sa and Sr values were attributed to abnormal thermal quenching of CaMoO4:0.09Eu3+ phosphor. Peak Sa and Sr values of BaMoO4:0.03Eu3+ phosphor was 12.39 %K−1 and 0.89 %K−1, respectively. In addition, Sa of AMoO4:Eu3+ phosphor was negatively related to Eu3+ central asymmetry, while peak Sr value was more inclined to appropriate ionic central asymmetry.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volova, Tatiana G., Uspenskaya, Mayya V., Kiselev, Evgeniy G., Sukovatyi, Aleksey G., Zhila, Natalia O., Vasiliev A. D., Shishatskaya, Ekaterina I.
Заглавие : Effect of monomers of 3-hydroxyhexanoate on properties of copolymers poly(3-hydroxybutyrate-co 3-hydroxyhexanoate)
Место публикации : Polymers. - 2023. - Vol. 15, Is. 13. - Ст.2890. - ISSN 20734360 (eISSN), DOI 10.3390/polym15132890
Примечания : Cited References: 99. - The study was funded by the Russian Science Foundation (project No 23-64-10007)
Аннотация: The properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(3HB-co-3HHx) copolymers with different ratios of monomers synthesized by the wild-type strain Cupriavidus necator B-10646 on sugars, and an industrial sample from Kaneka synthesized by the recombinant strain C. necator NSDG-ΔfadB1 on soybean oil, were studied in a comparative aspect and in relation to poly(3-hydroxybutyrate) P(3HB). The copolymer samples, regardless of the synthesis conditions or the ratio of monomers, had reduced values of crystallinity degree (50–60%) and weight average molecular weight (415–520 kDa), and increased values of polydispersity (2.8–4.3) compared to P(3HB) (70–76%, 720 kDa, and 2.2). The industrial sample had differences in its thermal behavior, including a lower glass transition temperature (−2.4 °C), two peaks in its crystallization and melting regions, a lower melting point (Tmelt) (112/141 °C), and a more pronounced gap between Tmelt and the temperature of thermal degradation (Tdegr). The process, shape, and size of the spherulites formed during the isothermal crystallization of P(3HB) and P(3HB-co-3HHx) were generally similar, but differed in the maximum growth rate of the spherulites during exothermic crystallization, which was 3.5–3.7 μm/min for P(3HB), and 0.06–1.25 for the P(3HB-co-3HHx) samples. The results from studying the thermal properties and the crystallization mechanism of P(3HB-co-3HHx) copolymers are important for improving the technologies for processing polymer products from melts.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu, Qin, Dang, Peipei, Zhang, Guodong, Molokeev M. S., Polyutov, Sergey, Lian, Hongzhou, Cheng, Ziyong, Li, Guogang, Lin, Jun
Заглавие : Achieving excellent thermostable red emission in singly Mn2+-doped near zero thermal expansion (NZTE) material Li2Zn3(P2O7)2
Колич.характеристики :10 с
Место публикации : J. Mater. Chem. C. - 2023. - Vol. 11, Is. 31. - P.10684-10693. - ISSN 20507526 (ISSN), DOI 10.1039/D3TC01683H. - ISSN 20507534 (eISSN)
Примечания : Cited References: 62. - This work wasfinancially supported by the National Science and Technology Major Project (2022YFB3503800), the Projects for Science and Technology Development Plan of Jilin Province (20210402046GH), the National Natural Science Foundation of China (NSFC No. 51932009, 51929201, 52072349, 52172166), the Natural Science Foundation of Zhejiang Province (LR22E020004), the Project funded by China Postdoctoral Science Foundation (2022TQ0365), and the Ministry of Science and High Education of Russian Federation (Project No. FSRZ2023-0006), M.S. Molokeev and S.P. Polyutov acknowledge the support by the Ministry of Science and High Education of Russian Federation (Project No. FSRZ-2023-0006)
Аннотация: The design of thermostable phosphor is still a pivotal challenge in pc-WLED applications. Herein, an efficient strategy is proposed to design excellent thermostable red emission in singly Mn2+-doped near zero thermal expansion (NZTE) material Li2Zn3(P2O7)2. Under the excitation of 412 nm wavelength, the emission could be tuned from 636 to 672 nm by increasing the Mn2+ doping level via synthetic effect among crystal field, the exchange coupling interaction in Mn-Mn dimers and energy transfer in different luminescence centers. The PL intensity of LZPO:Mn2+ maintains 97% at 150 °C and 94% at 200 °C of initial intensity at the room temperature. During the heat process, the LZPO presents near zero thermal expansion, which contributes to the nearly unaffected PL intensity. The traps assist energy transfer to luminescent center is also compensated for the emission loss. This work not only offers a perspective idea for elucidating the correlation between crystal structure and optical properties, but also opens a new way in line with that of designing excellent thermostable luminescent materials based on NZTE materials in self-reduction system.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wu, Yanzheng, Li, Weiqiang, Zheng, Yifan, Xu, Yiqin, Wen, Dawei, Molokeev M. S., Pan, Zaifa
Заглавие : Apatite oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+: A single-phased host with solar-like and efficient emission
Место публикации : J. Am. Ceram. Soc. - 2023. - Vol. 106, Is. 5. - P.2985-2996. - ISSN 00027820 (ISSN), DOI 10.1111/jace.18981. - ISSN 15512916 (eISSN)
Примечания : Cited References: 35. - This work was supported by the National Natural Science Foundation of China (Project No. 10804099, 21804119), Key projects of Zhejiang Natural Science Foundation (Project No. LZ18B050002), GDAS’ Project of Science and Technology Development (Nos. 2021GDASYL-20210103069, 2021GDASYL-20210103071)
Аннотация: During pursuing high color rendering index for full-color-emitting phosphor, low quantum efficiency (QE) is usually accompanying. We intend to elevate the luminescence efficiency when realizing a solar-like spectra distribution, by constructing apatite structure oxynitride, inheriting high covalence and rigidity from oxynitride, and suitable multiple cation sites from oxyapatite compounds. Full-color-emitting apatite structure oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ has been prepared, and the crystal sites’ occupancies of activators in this host were favorable for white emission. (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ phosphor shows whole visible light with emission wavelength ranging from 370 to 750 nm, matching the spectra of sunlight quite well. The fabricated white light-emitting diode lamp demonstrated the distinctive overall performance of QE and chromaticity properties (Ra and R9). Furthermore, correlated color temperature is tunable from cool nature to warm white. The obtained lamp possesses the feature of less blue light hazard and high saturation of red degree, compared with the commercial YAG-based lamp.
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11.

Вид документа : Статья из журнала
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Автор(ы) : Laptash N. M., Udovenko A. A., Vasiliev A. D., Merkulov E. B.
Заглавие : Strong hydrogen bond in the crystal structure design of CuNbOF5·4H2O
Место публикации : J. Solid State Chem. - 2023. - Vol. 318. - Ст.123781. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2022.123781. - ISSN 1095726X (eISSN)
Примечания : Cited References: 40. - We thank Dr. T.B. Emelina for the DFT calculations of uncoordinated [NbOF5]2– anion. The work was partially supported within the frames of the State Order of the Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences (project No. FWFN 0205–2022–0003)
Аннотация: Fluoride metal-organic frameworks (MOFs) based on pillared [NbOF5]2– anion have been recently received research attention as ultramicroporous materials for gas storage and separation. The trans-directing property of the NbOF5 octahedron plays a significant role in designing mixed metal oxyfluoride compounds composed of the alternating transition metal polyhedra, which are linked via oxide and fluoride ligands. Mixed metal CuNbOF5·4H2O is the only unique example when the trans-directing properties of [NbOF5]2– are realized in the formation of a strong O–H⋯F hydrogen bond (HB). Well-shaped single crystals of this compound were grown and their structure was refined by X-ray diffraction. Under quasi-isobaric conditions, a phase transition at 88 ​°C takes place, which is associated with the weakening of HBs and formation of ordinary chains through conventional trans-(O,F) bridges. The character of hydrogen bonding in CuNbOF5·4H2O affects its thermal behavior described by the dehydration and pyrohydrolysis processes.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abulkhaev M. U., Molokeev M. S., Oreshonkov A. S., Aleksandrovsky A. S., Kertman A. V., Kamaev D. N., Trofimova O. V., Elyshev A. V., Andreev O. V.
Заглавие : Properties of GdSF and phase diagram of the GdF3 - Gd2S3 system
Место публикации : J. Solid State Chem. - 2023. - Vol. 322. - Ст.123991. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2023.123991. - ISSN 1095726X (eISSN)
Примечания : Cited References: 44. - The authors of the article are grateful to P.P. Fedorov for valuable critical comments on the manuscriptThis research was funded by the Tyumen Oblast Government, as a part of the West-Siberian Interregional Science and Education Center’s project No. 89-DON (3)
Аннотация: The objectives of this study were to refine the phase diagram of the GdF3-Gd2S3 system and to calculate their liquidus, and to synthesize GdSF and to study their properties. The GdSF compound (ST PbFCl, P4/nmm, a (Å) 3.83006(17), c (Å) 6.8529(3), has an optical band gap for a direct interband transition of 2.56 ​eV and is characterized by a pronounced increase in the Kubelka-Munk function in the region of this transition. Direct optical bandgap of GdSF is measured to be equal to 2.77 ​eV. Two indirect bandgaps are detected to be 1.54 and 2.4 ​eV. Meta-GGA simulations of band structure predicting 1.481 ​eV direct bandgap of GdSF are in good agreement with these features of the experimental absorption spectrum. To explain this complicated case, we argue that formally direct optical transitions to highly dispersive subbands contribute not to direct but to indirect bandgaps measured by Tauc analysis. The GdSF compound melts incongruently with the formation of a melt and γ-Gd2S3 compound at t ​= ​1280 ​± ​2°С, ΔН ​= ​40.6 ​± ​2.8 ​kJ/mol, ΔS ​= ​26.1 ​± ​1.8 ​J/mol∗K. The eutectic has a composition of 13 ​mol.% Gd2S3 (0.74 GdF3 ​+ ​0.26 GdSF), the melting characteristics of the eutectic are 1182 ​± ​2°С, ΔН ​= ​36.2 ​± ​2.5 ​kJ/mol, ΔS ​= ​24.9 ​± ​1.7 ​J/mol∗K. In the system GdF3 - Gd2S3 the balance equations for five phase transformations recorded by the DSC method were compiled. Convergence was achieved in the liquidus of the system constructed according to DSC data and calculated with the use of the Redlich-Kister equation.
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13.

Вид документа : Статья из журнала
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Автор(ы) : Yang, Zhiyu, Zhao, Yifei, Ueda, Jumpei, Molokeev M. S., Shang, Mengmeng, Xia, Zhiguo
Заглавие : Engineering charge-transfer interactions for red-emitting SrLa(Sc,Ga)O4:Ce3+ phosphor with improved thermal stability
Место публикации : Sci. China Mater. - 2023. - Vol. 66, Is. 5. - P.1989-1996. - ISSN 20958226 (ISSN), DOI 10.1007/s40843-022-2315-9. - ISSN 21994501 (eISSN)
Примечания : Cited References: 32. - This work was supported by the National Key Research and Development Program of China (2021YFE0105700), the National Natural Science Foundations of China (51972118), the Natural Science Foundation of Shandong Province (ZR2021ZD10 and ZR2018JL016), Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work was also funded by Russian Foundation for Basic Research (19-52-80003)
Аннотация: Blue-light-excitable red-emitting phosphors with high thermal stability are essential for fabricating white light-emitting diodes (WLEDs). Herein, Ce3+-doped SrLaScO4 (SLO:Ce3+) phosphor is discovered to have an abnormal red emission band centered at 640 nm when excited at 440 nm. Spectroscopy and structural analyses confirm that Ce3+ ions occupy the [LaO8] polyhedrons competitively, generating a strong crystal field splitting and a large Stokes shift to produce a red emission. To further restrict the thermal quenching of SLO:Ce3+, charge-transfer engineering is implemented by incorporating a large electronegative Ga3+ in the Sc3+ site, which can attract more charges from nearby coordinating groups to decrease the electronic occupation at the bottom of the conduction band and thereby enlarge the band gap. Sc/Ga substitution in SrLa(Sc,Ga)O4:Ce3+ enhances the thermal stability by increasing the intensity ratio from 15% to 31% at 150°C compared with 20°C. This is attributed to the efficient suppression of the thermally stimulated ionization process. This study presents a general design principle for discovering novel Ce3+-doped red phosphors with good thermal stability for WLED applications.
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14.

Вид документа : Статья из журнала
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Автор(ы) : Bogdanov E. V., Pogoreltsev E. I., Gorev M. V., Mel'nikova S. V., Molokeev M. S., Laptash N. M., Flerov I. N.
Заглавие : Effect of the size of the central atom on the stability of crystalline phases in solid solutions (NH4)3TixSn1-xF7
Колич.характеристики :8 с
Место публикации : J. Solid State Chem. - 2023. - Vol. 328. - Ст.124373. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2023.124373. - ISSN 1095726X (eISSN)
Примечания : Cited References: 20. - The study was supported by a grant from the Russian Science Foundation № 23-22-00115, https://rscf.ru/project/23-22-00115/X-ray and dilatometric data and SEM images were obtained using the equipment of the Krasnoyarsk Regional Center for Collective Use of the Federal Research Center — Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences. We are grateful to Dr. A.V. Shabanov for examination of the SEM images
Аннотация: The effect of a change in internal pressure as a result of partial substitution of the central atom on the realization and stability of the initial and distorted crystalline phases in (NH4)3TixSn1-xF7 solid solutions has been studied. It was found that at a Ti concentration in the range of x = 0.15–0.40, the reconstructive transition Pm-3m ↔ Pa-3 is transformed into a sequence of phase transitions Pm-3m ↔ P4/mbm ↔ P4/mnc ↔ Pa-3. In the (NH4)3Ti0.15Sn0.85F7 solid solution, the first-order phase transition between two cubic phases at T0 = 352 K is characterized by a significant volume jump δ(ΔV/V0) ≈ 1 %, comparable with that in (NH4)3SnF7. An increase of the Ti concentration leads to a strong decrease in the stability of the Pm-3m cubic phase: the first tetragonal P4/mbm phase appears in (NH4)3Ti0.4Sn0.6F7 at T0 = 400 K, which proves the existence of the predicted high-temperature cubic phase in (NH4)3TiF7. In solid solutions, a decrease in birefringence and entropy of phase transitions was observed in comparison with the initial compounds with Sn and Ti as central atoms. The role of critical parameters (unit cell volume, temperature, external pressure) in the formation of cubic and distorted phases is discussed.
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15.

Вид документа : Статья из журнала
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Автор(ы) : Volova, Tatiana G., Zhila, Natalia O., Kiselev, Evgeniy G., Sukovatyi, Aleksey G., Lukyanenko A. V., Shishatskaya, Ekaterina I.
Заглавие : Biodegradable polyhydroxyalkanoates with a different set of valerate monomers: Chemical structure and physicochemical properties
Колич.характеристики :21 с
Место публикации : Int. J. Mol. Sci. - 2023. - Vol. 24, Is. 18. - Ст.14082. - ISSN 16616596 (ISSN), DOI 10.3390/ijms241814082. - ISSN 14220067 (eISSN)
Примечания : Cited References: 99. - The study was funded by the Russian Science Foundation (project no. 23-64-10007)
Аннотация: The properties, features of thermal behavior and crystallization of copolymers containing various types of valerate monomers were studied depending on the set and ratio of monomers. We synthesized and studied the properties of three-component copolymers containing unusual monomers 4-hydroxyvalerate (4HV) and 3-hydroxy-4-methylvalerate (3H4MV), in addition to the usual 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) monomers. The results showed that P(3HB-co-3HV-co-4HV) and P(3HB-co-3HV-co-3H4MV) terpolymers tended to increase thermal stability, especially for methylated samples, including an increase in the gap between melting point (Tmelt) and thermal degradation temperature (Tdegr), an increase in the melting point and glass transition temperature, as well as a lower degree of crystallinity (40–46%) compared with P(3HB-co-3HV) (58–66%). The copolymer crystallization kinetics depended on the set and ratio of monomers. For terpolymers during exothermic crystallization, higher rates of spherulite formation (Gmax) were registered, reaching, depending on the ratio of monomers, 1.6–2.0 µm/min, which was several times higher than the Gmax index (0.52 µm/min) for the P(3HB-co-3HV) copolymer. The revealed differences in the thermal properties and crystallization kinetics of terpolymers indicate that they are promising polymers for processing into high quality products from melts.
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16.

Вид документа : Статья из журнала
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Автор(ы) : Дудунов А. А., Лукьяненко, Анна Витальевна, Кочура С. Г., Максимов И. А., Надирадзе А. Б., Смирнов В. А., Тихомиров Р. Е.
Заглавие : Исследование условий образования тонких пленок золота на терморегулирующих покрытиях космических аппаратов
Колич.характеристики :9 с
Место публикации : Наукоемкие технол. - 2023. - Т. 24, № 7. - С. 15-23. - ISSN 19998465 (ISSN), DOI 10.18127/j19998465-202307-02; Sc. Intens. Technol.
Примечания : Библиогр.: 14
Аннотация: Постановка задачи. При оценивании загрязнения терморегулирующих покрытий космических аппаратов продуктами распыления сетеполотна, формирующего радиоотражающие поверхности рефлекторов антенн, актуальной является проблема достоверности оценок. Необходимо, чтобы модель осаждения описывала закономерности образования пленок загрязнения с учетом величин потоков частиц осаждения и температур поверхностей. Цель. Повысить достоверность модели осаждения золота на терморегулирующее покрытие типа ОСО-С на основании экспериментально полученных данных об образовании пленок загрязнения в условиях, приближенных к условиям летной эксплуатации космических аппаратов. Результаты. Получены пленки загрязнения толщиной от 0,16 до 3,5 нм при различных параметрах их образования (плотность потока частиц осаждения в диапазоне от 1014 до 1017 м-2с-1, температура образцов в диапазоне от +20 до +110°С). Исследованы спектральные характеристики облученных образцов. На атомном сканирующем микроскопе исследована шероховатость поверхности образцов с пленкой загрязнения. Методом рентгенофлуоресцентного анализа исследован химический состав пленок загрязнения. Выполнен обзор работ, описывающих процессы образования тонких пленок загрязнения и их особенности. Получена зависимость изменения коэффициента поглощения солнечного излучения As терморегулирующего покрытия типа ОСО-С от толщины пленок загрязнения из золота, полученных при сверхмалых потоках частиц осаждения. Практическая значимость. Установлено, что в условиях летной эксплуатации космических аппаратов конденсация продуктов распыления сетеполотна на поверхности терморегулирующего покрытия типа ОСО-С будет происходить практически во всем диапазоне возможных значений плотности потока частиц и температуры поверхностей. Также экспериментально подтверждено, что пленки загрязнения, образующиеся при сверхмалых скоростях осаждения, имеют увеличенную зернистость и, как следствие, меньшую проводимость, что приводит к меньшему изменению (деградации) коэффициента поглощения солнечного излучения.Problem definition – the problem on estimation reliability is topical when we estimate thermal control coating of spacecraft contamination by the sputtered products of retiform cloth forming radio-reflecting surfaces of antenna reflector. The deposition model should describe the regularities of contamination film formation by considering deposited particles flows and surfaces temperatures. Goal – to increase the reliability of the model for aurum deposition onto thermal control coating of ОСО-С type according to the experimental information under conditions close to the flight ones for the spacecraft. Results – obtained the contamination film with thickness ranging from 0,16 up to 3,5 nm under different parameters of its formation (flow density of deposited particles in the range from 1014 up to 1017 m-2s-1, samples ‘temperature in the range from +20 до 110°С). Spectral performances of the radiated samples were examined. The roughness of the samples with contamination film was studied with the help of scanning microscope. The chemical composition of contamination films was examined by X-ray fluorescence analysis. The review of works describing the processes of formation of thin films of contamination and there features is carried out. The dependence of change in the absorption coefficient of solar radiation As of thermal control coating of ОСО-С type on the thickness of aurum contamination film is obtained under super small flows of deposited particles. Practical value – it is revealed that under flight conditions the process of sputtered products of retiform cloth deposition to the surfaces of thermally controlling coating of ОСО-С type will occur under implementing particle flow densities and surface temperature. It is also experimentally confirmed that the contamination films formed under super small deposition rates are characterized by increased granularity and as a result by lower conductivity and lower variation (degradation) of absorption coefficient of solar radiation.
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17.

Вид документа : Статья из журнала
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Автор(ы) : Zharkov S. M., Yumashev V. V., Moiseenko E. T., Altunin R. R., Solovyov L. A., Volochaev M. N., Zeer G. M., Nikolaeva N. S., Belousov O. V.
Заглавие : Thermokinetic study of aluminum-induced crystallization of a-Si: The effect of Al layer thickness
Колич.характеристики :24 с
Место публикации : Nanomaterials. - 2023. - Vol. 13, Is. 22. - Ст.2925. - ISSN 20794991 (eISSN), DOI 10.3390/nano13222925
Примечания : Cited References: 70. - This work was supported by the Russian Science Foundation under grant #22-13-00313
Аннотация: The effect of the aluminum layer on the kinetics and mechanism of aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in (Al/a-Si)n multilayered films was studied using a complex of in situ methods (simultaneous thermal analysis, transmission electron microscopy, electron diffraction, and four-point probe resistance measurement) and ex situ methods (X-ray diffraction and optical microscopy). An increase in the thickness of the aluminum layer from 10 to 80 nm was found to result in a decrease in the value of the apparent activation energy Ea of silicon crystallization from 137 to 117 kJ/mol (as estimated by the Kissinger method) as well as an increase in the crystallization heat from 12.3 to 16.0 kJ/(mol Si). The detailed kinetic analysis showed that the change in the thickness of an individual Al layer could lead to a qualitative change in the mechanism of aluminum-induced silicon crystallization: with the thickness of Al ≤ 20 nm. The process followed two parallel routes described by the n-th order reaction equation with autocatalysis (Cn-X) and the Avrami–Erofeev equation (An): with an increase in the thickness of Al ≥ 40 nm, the process occurred in two consecutive steps. The first one can be described by the n-th order reaction equation with autocatalysis (Cn-X), and the second one can be described by the n-th order reaction equation (Fn). The change in the mechanism of amorphous silicon crystallization was assumed to be due to the influence of the degree of Al defects at the initial state on the kinetics of the crystallization process.
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18.

Вид документа : Статья из журнала
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Автор(ы) : Denisenko Yu. G., Molokeev M. S., Jiang X., Sedykh A. E., Aleksandrovsky A. S., Oreshonkov A. S., Roginskii E. M., Zhernakov M. A., Heuler D., Seuffert M., Lin Zh., Andreev O. V., Muller-Buschbaum K.
Заглавие : Negative thermal expansion in the polymorphic modification of double sulfate β-AEu(SO4)2 (A–Rb+, Cs+)
Колич.характеристики :11 с
Место публикации : Inorg. Chem. - 2023. - Vol. 62, Is. 31. - P.12423-12433. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.3c01624. - ISSN 1520510X (eISSN)
Примечания : Cited References: 71. - The work was partly carried out within the framework of the Strategic Academic Leadership Program ″Priority-2030″ for the Siberian Federal University, Tyumen State University, Kazan Federal University and the state assignment of Kirensky Institute of Physics. The calculations were performed in part using facilities of JSCC supercomputer center of RAS
Аннотация: New polymorphic modifications of double sulfates β-AEu(SO4)2 (A–Rb+, Cs+) were obtained by the hydrothermal method, the structure of which differs significantly from the monoclinic modifications obtained earlier by solid-state methods. According to single-crystal diffraction data, it was found that the compounds crystallize in the orthorhombic system, space group Pnna, with parameters β-RbEu(SO4)2: a = 9.4667(4) Å, b = 13.0786(5) Å, c = 5.3760(2) Å, V = 665.61(5) Å3; β-CsEu(SO4)2: a = 9.5278(5) Å, b = 13.8385(7) Å, c = 5.3783(3) Å, V = 709.13(7) Å3. The asymmetric part of the unit cell contains one-half Rb+/Cs+ ion, one-half Eu3+ ion, both in special sites, and one SO42– ion. Both compounds exhibit nonlinear negative thermal expansion. According to the X-ray structural analysis and theoretical calculations, the polarizing effect of the alkali metal ion has a decisive influence on the demonstration of this phenomenon. Experimental indirect band gaps of β-Rb and β-Cs are 4.05 and 4.11 eV, respectively, while the direct band gaps are 4.48 and 4.54 eV, respectively. The best agreement with theoretical calculations is obtained using the ABINIT package employing PAW pseudopotentials with hybrid PBE0 functional, while norm-conserving pseudopotentials used in the frame of CASTEP code and LCAO approach in the Crystal package gave worse agreement. The properties of alkali ions also significantly affect the luminescent properties of the compounds, which leads to a strong temperature dependence of the intensity of the 5D0 → 7F4 transition in β-CsEu(SO4)2 in contrast to much weaker dependence of this kind in β-RbEu(SO4)2.
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19.

Вид документа : Статья из журнала
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Автор(ы) : Smirnova E. S., Alekseeva O. A., Artemov V. V., Sorokin T. A., Khmelenin D. N., Sidorova E. V., Frolov K. V., Gudim I. A.
Заглавие : Crystal structure of bismuth-containing samarium iron–aluminium borates Sm1−xBixFe3−yAly(BO3)4 (x = 0.05–0.07, y = 0–0.28) in the temperature range of 25–500 K
Колич.характеристики :20 с
Место публикации : Crystals. - 2023. - Vol. 13, Is. 7. - Ст.1128. - ISSN 20734352 (eISSN), DOI 10.3390/cryst13071128
Примечания : Cited References: 59. - This work was supported by the Russian Science Foundation (project No 23-22-00286)
Аннотация: Structural features of new mixed bismuth-containing samarium iron–aluminium borate single crystals Sm1−xBixFe3−yAly(BO3)4 (x = 0.05–0.07, y = 0–0.28) were studied using X-ray diffraction analysis based on aluminium content and temperature in the range 25–500 K. The crystals were grown using the solution-in-melt technique with Bi2Mo3O12 in a flux. The composition of the single crystals was analyzed using energy-dispersive X-ray fluorescence and energy-dispersive X-ray elemental analysis. Temperature dependencies of Sm1−xBixFe3−yAly(BO3)4 unit-cell parameters were studied. Negative thermal expansion was identified below 100 K and represented by characteristic surfaces of the thermal expansion tensor. (Sm,Bi)–O, (Sm,Bi)–(Fe,Al), (Fe,Al)–(Fe,Al), and (Fe,Al)–O interatomic distances decreased with the addition of aluminium atoms. An increase in the (Fe,Al)–(Fe,Al) intrachain bond length at low temperatures in the magnetically ordered state weakened this bond, whereas a decrease in the (Fe,Al)–(Fe,Al) interchain distance strengthened super-exchange paths between different chains. It was found that the addition of aluminium atoms influenced interatomic distances in Sm1−xBixFe3−yAly(BO3)4 much more than lowering the temperature from 293 K to 25 K. The effect of aluminium doping on magnetoelectric properties and structural symmetry of rare-earth iron borates is also discussed.
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20.

Вид документа : Статья из журнала
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Автор(ы) : Ryabin A. A., Krylov A. S., Krylova S. N., Kiselev E. A., Pelegov D. V.
Заглавие : Thermal evolution of LiCoO2 structure and Raman spectra below 400 °C
Колич.характеристики :9 с
Место публикации : J. Chem. Phys. - 2023. - Vol. 159, Is. 8. - Ст.084706. - ISSN 00219606 (ISSN), DOI 10.1063/5.0164135. - ISSN 10897690 (eISSN)
Примечания : Cited References: 60. - The research was funded by the Russian Science Foundation (Project No. 22-22-00350, https://rscf.ru/project/22-22-00350). The Raman spectra measurements were made using equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University (Reg. No. 2968), supported by the Ministry of Science and Higher Education of the Russian Federation (Project No. 075-15-2021-677). Authors warmly thank Professor Jongwoo Lim (Seoul National University) for samples, reading the manuscript, and providing his valuable comments
Аннотация: Lithium cobalt oxide is a convenient model material for the vast family of cathode materials with a layered structure and still retains some commercial perspectives for microbatteries and some other applications. In this work, we have used ab initio calculations, x-ray diffraction, Raman spectroscopy, and a theoretical physical model, based on quasi-harmonic approximation with anharmonic contributions of the three-phonon and four-phonon processes, to study a temperature-induced change of Raman spectra for LiCoO2. The obtained values of shift and broadening for Eg and A1g bands can be used for quantitative characterization of temperature change, for example, due to laser-induced heating during Raman spectra measurements. The theoretical analysis of the experimental results lets us conclude that Raman spectra changes for LiCoO2 can be explained by the combination of thermal expansion of the crystal lattice and phonon damping by anharmonic coupling with comparable contributions of the three-phonon and four-phonon processes. The obtained results can be further used to develop Raman-based quality control tools.
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