10 results on '"Kh. E. Yorov"'
Search Results
2. Is Supercritical So Critical? The Choice of Temperature to Synthesize SiO2 Aerogels
- Author
-
Gennady P. Kopitsa, Sergey A. Lermontov, Adél Len, N. A. Sipyagina, Olga S. Ivanova, A. N. Malkova, Alexander E. Baranchikov, Kh. E. Yorov, and Vladimir Ivanov
- Subjects
Pore size ,Materials science ,Materials Science (miscellaneous) ,010402 general chemistry ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Supercritical fluid ,0104 chemical sciences ,Degree (temperature) ,Inorganic Chemistry ,Hydrolysis ,Volume (thermodynamics) ,Chemical engineering ,Specific surface area ,Physical and Theoretical Chemistry ,Mesoporous material ,Porosity - Abstract
The structure of SiO2-based materials obtained by hydrolysis of tetraethoxysilane and subsequent drying of SiO2 lyogels at temperatures from 85 to 265°C has been analyzed in detail. It has been found that drying conditions have no marked effect on the specific surface area of SiO2, which constitutes ~1000 m2/g in all cases. Average pore size and specific pore volume monotonically increase with drying temperature, the contribution of large mesopores (>20 nm) into total material porosity rises at high drying temperature. Drying temperature has a considerable effect on the degree and character of individual SiO2 particles aggregation.
- Published
- 2020
3. Bromobismuthates of 1,1'-(1,N-Alkanediyl)bis(picolines): Synthesis, Thermal Stability, Crystal Structures, and Optical Properties
- Author
-
A. Yu. Rudenko, Petr A. Buikin, Nikolay P. Simonenko, Kh. E. Yorov, Andrey B. Ilyukhin, and V. Yu. Kotov
- Subjects
Crystallography ,Structure analysis ,Chemistry ,General Chemical Engineering ,Thermal stability ,General Chemistry ,Crystal structure ,010402 general chemistry ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences - Abstract
Hybrid bromobismuthates of N-alkylated derivatives of 2- and 3-methylpyridine, (C15H20N2)2Bi2Br10 (I), (C17H24N2)2Bi2Br10 (II), (C18H26N2)3(Bi2Br9)2 (III), (C14H18N2)(H3O)BiBr6 ∙ 2H2O (IV), (C14H18N2)2BiBr6IBr2 (V), (C16H22N2)3(Bi2Br9)2 (VI), and (C18H26N2)3(Bi2Br9)2 (VII), are synthesized in concentrated HBr and characterized by physicochemical methods. The structures of complexes I–VII are studied by X-ray structure analysis (CIF files CCDC nos. 1946844–1946850). Complexes I and II contain anions [Bi2Br10]4–. Anions [Bi2Br9]3– are found in the structures of compounds III, VI, and VII. Bis(3-methyl-1-pyridino)ethane bromobismuthate IV contains cations H3O+ and anions [BiBr6]3– and, unlike other bromobismuthates, decomposes at low temperatures. In presence of HI vapors, double bromobismuthate V containing the [BiBr6]3– and IBr2– anions crystallizes along with compound IV.
- Published
- 2020
4. Highly reversible photochromism in composite WO3/nanocellulose films
- Author
-
O. L. Evdokimova, Kh. E. Yorov, Alexander V. Agafonov, Alexander E. Baranchikov, A. B. Shcherbakov, T. V. Kusova, Olga S. Ivanova, and Vladimir Ivanov
- Subjects
Materials science ,Polymers and Plastics ,Scanning electron microscope ,Composite number ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanocrystalline material ,0104 chemical sciences ,Nanocellulose ,Photochromism ,Chemical engineering ,Thermal stability ,0210 nano-technology ,Thermal analysis - Abstract
Reversible photochromic hybrid organic–inorganic films containing nanocrystalline cellulose as a matrix and tungsten oxide as a photochromic component (CNC/WO3) were obtained via a simple and quick solvent casting method. The films were studied by scanning electron microscopy, together with element mapping, FT-IR spectroscopy and X-ray diffraction, confirming successful incorporation of WO3 nanoparticles into a nanocellulose matrix. Thermal analysis data indicated that the modification of a nanocellulose matrix with WO3 increases its thermal stability. The CNC/WO3 films showed a quick coloration-bleaching transition with good reversibility within 20 min, without notable degradation of photochromic properties after 10 cycles. The synthetic method proposed allows for scalable preparation of highly efficient low-cost WO3-based photochromic materials.
- Published
- 2019
5. Photoluminescent porous aerogel monoliths containing ZnEu-complex: the first example of aerogel modified with a heteronuclear metal complex
- Author
-
Kh. E. Yorov, Gennady P. Kopitsa, O. V. Boytsova, Adél Len, Vitaliy Pipich, Alexander V. Agafonov, Mikhail A. Kiskin, S. А. Lermontov, А. Е. Baranchikov, Vladimir Ivanov, S. Yu. Kottsov, Evgenia A. Varaksina, and Alexey A. Sidorov
- Subjects
Photoluminescence ,Materials science ,Supercritical drying ,Aerogel ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Matrix (chemical analysis) ,symbols.namesake ,X-ray photoelectron spectroscopy ,Chemical engineering ,Materials Chemistry ,Ceramics and Composites ,symbols ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Luminescence ,Raman spectroscopy - Abstract
A procedure for the chemical immobilization of a new ZnII–EuIII heterobimetallic complex in the SiO2 aerogel matrix has been developed. In this Zn–Eu complex, a peripheral non-luminescent Zn ion acts as a binder to a silica matrix and prevents direct interaction of rare-earth ions with OH− and NH− groups in the silica matrix, which would have a detrimental effect on the luminescence of lanthanides. The procedure includes the synthesis of complexes, co-gelation of the obtained complex with SiO2 sol, the washing of lyogels, and their subsequent supercritical drying in CO2. The composition and properties of the obtained aerogels were investigated using a low-temperature nitrogen adsorption technique, helium pycnometry, FTIR, Raman, UV–visible, and luminescence spectroscopy, XPS, PXRD, SEM, TEM, TGA combined with mass spectrometry, and small-angle neutron scattering. The aerogels modified with the ZnII–EuIII complex demonstrated strong red luminescence upon excitation with UV light.
- Published
- 2019
6. Luminescent alumina-based aerogels modified with tris(8-hydroxyquinolinato)aluminum
- Author
-
Alexey D. Yapryntsev, Kh. E. Yorov, Sergei A. Lermontov, E. A. Straumal, Alexander E. Baranchikov, Vladimir Ivanov, and T. V. Khamova
- Subjects
Materials science ,Supercritical drying ,Infrared spectroscopy ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Thermogravimetry ,Chemical engineering ,Transmission electron microscopy ,Gas pycnometer ,Specific surface area ,Materials Chemistry ,Ceramics and Composites ,0210 nano-technology ,Luminescence ,Spectroscopy - Abstract
A facile procedure was developed for the production of Al2O3 aerogels modified with tris(8-hydroxyquinolinato)aluminum complex (AlQ3). The addition of 8-hydroxyquinoline during the stage of alumina lyogel formation was found to increase gelation duration. The translucent monolithic aerogels were obtained by supercritical drying of lyogels in CO2. The composition and properties of aerogels were analyzed using low-temperature nitrogen adsorption, helium pycnometry, IR spectroscopy, UV–visible spectroscopy, luminescence spectroscopy, powder X-ray diffraction, scanning and transmission electron microscopy, and thermogravimetry combined with mass spectrometry. The obtained aerogels had low density (0.15–0.18 g cm−3), high specific surface area (480–550 m2/g), high porosity (90–95%), and showed bright luminescence upon excitation in the UV range.
- Published
- 2018
7. Comparative analysis of the physicochemical characteristics of SiO2 aerogels prepared by drying under subcritical and supercritical conditions
- Author
-
Kh. E. Yorov, Gennady P. Kopitsa, Vladimir Ivanov, Vitaliy Pipich, N. A. Sipyagina, Sergei A. Lermontov, A. N. Malkova, Noemi Szekely, and Alexander E. Baranchikov
- Subjects
Materials science ,Scanning electron microscope ,General Chemical Engineering ,Metals and Alloys ,02 engineering and technology ,Neutron scattering ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Microanalysis ,Supercritical fluid ,0104 chemical sciences ,Inorganic Chemistry ,Solvent ,Chemical engineering ,Specific surface area ,Materials Chemistry ,0210 nano-technology ,Thermal analysis ,Porosity - Abstract
SiO2-based aerogels have been produced be removing a solvent (ethanol or hexafluoroisopropanol) from lyogels both above and below the critical temperature of the alcohols (in the range 210–260 and 160–220°C, respectively). The resultant materials have been characterized by low-temperature nitrogen adsorption measurements, X-ray diffraction, thermal analysis, scanning electron microscopy, X-ray microanalysis, and small-angle and ultrasmall-angle neutron scattering. The results demonstrate that removing the solvent 20–30°C below the critical temperature of the solvent yields silica that is characterized by higher specific porosity and has the same or a larger specific surface area in comparison with the aerogels produced by drying under supercritical conditions. The nature of the solvent used and the solvent removal temperature influence the size and aggregation behavior of primary clusters and the cluster aggregate size in the aerogels.
- Published
- 2017
8. SiO2–TiO2 binary aerogels: Synthesis in new supercritical fluids and study of thermal stability
- Author
-
L. P. Borilo, Sergei A. Lermontov, Vladimir Ivanov, Kh. E. Yorov, N. A. Sipyagina, and Alexander E. Baranchikov
- Subjects
Anatase ,Materials science ,Materials Science (miscellaneous) ,Supercritical drying ,Supercritical fluid extraction ,02 engineering and technology ,Thermal treatment ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanocrystalline material ,Supercritical fluid ,0104 chemical sciences ,Inorganic Chemistry ,Chemical engineering ,Organic chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,0210 nano-technology ,Porosity - Abstract
A comparative analysis of properties of SiO2–TiO2 binary aerogels prepared by supercritical drying using different supercritical fluids (isopropanol, hexafluoroisopropanol, methyl tert-butyl ether, and CO2) has been performed. The use of different supercritical fluids allows preparation of both homogeneous amorphous SiO2–TiO2 binary aerogels (by supercritical drying in hexafluoroisopropanol and CO2) and composite aerogels containing nanocrystalline anatase (by supercritical drying in isopropanol and methyl tert-butyl ether). The thermal treatment of the aerogels at temperatures up to 600°C does not lead to considerable change in the porous structure and phase composition of the aerogels.
- Published
- 2016
9. Engineering SiO2–TiO2 binary aerogels for sun protection and cosmetic applications
- Author
-
Kh. E. Yorov, I. V. Kolesnik, Alexander E. Baranchikov, Gennady P. Kopitsa, Sergey A. Lermontov, Vladimir Ivanov, N. A. Sipyagina, I.P. Romanova, and Yu. B. Mamaeva
- Subjects
Materials science ,Sun protection ,General Chemical Engineering ,Supercritical drying ,Infrared spectroscopy ,Ether ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Sun Protection Factors ,Carbon dioxide ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
SiO2‒TiO2 binary aerogels obtained by the methods of low-temperature (carbon dioxide) and high-temperature (isopropanol, hexafluoroisopropanol and methyl tert-butyl ether) supercritical drying are considered as multifunctional cosmetic pigments with high anti-shine power and photoprotective properties. The composition and structure of SiO2–TiO2 aerogels obtained by supercritical drying in various fluids were studied by IR spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, scanning and transmission electron microscopy, and low-temperature nitrogen adsorption. The values of the sun protection factors SPF and UVAPF for the obtained materials are comparable to those of the commercial sunscreens Kronos 1171 and Kronos 2971, and the anti-shine power is approximately 1.5 times higher than that of kaolin-based materials.
- Published
- 2021
10. Methyl tert-butyl ether as a new solvent for the preparation of SiO2–TiO2 binary aerogels
- Author
-
L. P. Borilo, Sergei A. Lermontov, Alexander E. Baranchikov, Kh. E. Yorov, A. N. Malkova, N. A. Sipyagina, and Vladimir Ivanov
- Subjects
Anatase ,Materials science ,General Chemical Engineering ,Supercritical drying ,Metals and Alloys ,Ether ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Supercritical fluid ,Nanocrystalline material ,0104 chemical sciences ,Inorganic Chemistry ,Solvent ,chemistry.chemical_compound ,chemistry ,Specific surface area ,Materials Chemistry ,Organic chemistry ,0210 nano-technology ,Methyl tert-butyl ether - Abstract
SiO2–TiO2 binary aerogels have been synthesized for the first time using methyl tert-butyl ether as supercritical fluid. It has been shown that the aerogels prepared in methyl tert-butyl ether and isopropanol contain nanocrystalline anatase and that amorphous SiO2–TiO2 aerogels with a homogeneous distribution of their components can be obtained in CO2. A considerable contribution to the large specific surface area of the aerogels is made by micropores, especially when supercritical drying is carried out in CO2 and isopropanol.
- Published
- 2016
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.