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11.
The effects of the 57Fe isotope content and high-frequency magnetic field amplitude h
1 on the shape of the NMR spectrum of multiferroic BiFeO3 at T = 4.2 K are studied by pulsed nuclear magnetic resonance. The NMR spectrum shape and transverse relaxation time T
2 are found to depend strongly on the 57Fe isotope content and h
1 in multiferroic BiFeO3 in the presence of a spatial spin-modulated structure of a cycloid type. In a sample with a high 57Fe isotope content, the Suhl-Nakamura interaction contributes substantially to T
2. When these dynamic effects are taken into account for analysis of the NMR spectrum shape, an undisturbed (without an anharmonicity
effect) spatial spin-modulated structure of a cycloid type is shown to exist in BiFeO3. 相似文献
12.
Mössbauer method was used to study a perovskite compound Bi0.9Ca0.1FeO3 at T = 295 K and at temperature above T N . It has been established that Bi0.9Ca0.1FeO3 has a rhombohedral crystal structure similar to that of BiFeO3. The substitution of Ca2+ for Bi3+ ions leads to the formation of three states of Fe3+ ions with an octahedral surroundings and one state with a tetrahedral oxygen surroundings with substantially different hyperfine magnetic fields. All Fe ions are in a trivalent state; the compensation of the charge deficit occurs via the formation of oxygen vacancies. Above T N , two structurally nonequivalent states of Fe3+ ions exist in the Bi0.9Ca0.1FeO3 sample, which correspond to the Fe3+ ions with an octahedral and tetrahedral oxygen coordination. 相似文献
13.
V. N. Kizhnyaev F. A. Pokatilov D. V. Vil’yanen V. I. Gross O. A. Edel’shtein 《Polymer Science Series B》2018,60(1):99-106
Network paired polymers (interpolymers) capable of limited swelling in aqueous media accompanied by the formation of polyelectrolyte hydrogels exhibiting рН and thermal sensitivity are synthesized by the reactions of poly(acrylic acid) with poly(methyl methacrylate) and poly(N-vinylcaprolactam) modified by the introduction of anchor oxirane moieties. 相似文献
14.
V. N. Kizhnyaev F. A. Pokatilov T. N. Baginova R. G. Zhitov A. G. Proidakov 《Russian Journal of Applied Chemistry》2016,89(7):1137-1144
Comparative analysis of the curing performance of epoxy-containing cross-linking agents of different structure in vulcanization of a promising binder for energetic systems, poly-N-methyl-5-vinyltetrazole prepared by the modification procedure and containing residual N–H-unsubstituted tetrazole fragments, was made. Cross-linking of polymer chains of the binder is a result of alkylation of the residual N–H-unsubstituted tetrazole rings in poly-N-methyl-5-vinyltetrazole macromolecules with oxirane rings of the second reactant. Curing of poly-N-methyl-5-vinyltetrazole in the presence of macromolecular curing agents, carbon-chain polymers containing oxirane rings in pendant chains, at temperatures lower than 100°С occurs in a considerably narrower time interval compared to curing with low-molecular-mass epoxy resin. 相似文献
15.
V. S. Pokatilov T. G. Dmitrieva V. V. Pokatilov V. V. Kitaev 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(7):840-842
The local atomic and magnetic structure of Fe70Cr15B15 X-ray amorphous alloy is studied by means of 11B nuclear magnetic resonance (NMR) and 57Fe Mössbauer spectroscopy. It is determined that Fe85B15 and Fe70Cr15B15 X-ray amorphous alloys consist of microregions (nanocrystals) with short-range orders of t-Fe3B and α-Fe phases. It was found out that chromium atoms in the Fe70Cr15B15 X-ray amorphous alloy are evenly distributed in these two nanocrystals, forming t-(Fe,Cr)3B and α-Fe(Cr) phases. 相似文献
16.
V. N. Kizhnyaev T. L. Petrova F. A. Pokatilov 《Russian Journal of Applied Chemistry》2012,85(5):812-817
The swelling in aqueous media of network poly-5-vinyltetrazole synthesized by various procedures using low-molecular-weight, oligomeric, and polymeric cross-linking agents was studied. 相似文献
17.
Pokatilov F. A. Kizhnyaev V. N. Zhitov R. G. Krakhotkina E. A. 《Russian Journal of Applied Chemistry》2016,89(12):2102-2108
Specific features of synthesis of network polymers based on tetrazolylethyl cellulose ethers by alkylation of tetrazole rings in the structure of the cellulose derivative with di- and polyfunctional oligomeric and polymeric oxiranecontaining compounds were studied. The influence exerted by the structure of the cross-linking agents on the time parameters of the network structure formation, degree of the polymer cross-linking, ability of the network polymers obtained to absorb various liquids, and pH and temperature sensitivity of the hydrogels based on cross-linked tetrazolylated cellulose was considered.
相似文献18.
Pokatilov V. S. Rusakov V. S. Pokatilov V. V. Makarova A. O. 《Bulletin of the Russian Academy of Sciences: Physics》2015,79(6):774-777
Bulletin of the Russian Academy of Sciences: Physics - 57Fe hyperfine interactions are measured in cubic perovskite Bi0.75Sr0.25Fe0.95Cr0.05O3–y by means of Mössbauer spectroscopy in the... 相似文献
19.
The perovskite Bi0.5Ca0.5FeO3 has been investigated using the Mössbauer effect at temperatures of 295 and 675 K. The measured temperature of the magnetic phase transition (Néel temperature) is T N = 640 ± 10 K. Above the Néel temperature, there are two nonequivalent structural states of iron ions. In the perovskite Bi0.5Ca0.5FeO3 at room temperature, there are seven most probable nonequivalent magnetic states of iron ions with significantly different values of the hyperfine interaction parameters. Four iron states correspond to Fe3+ ions in the octahedral oxygen environment, and three iron states correspond to Fe3+ ions in the tetrahedral oxygen environment. 相似文献
20.
I. S. Lyubutin K. V. Frolov O. A. Anosova V. S. Pokatilov A. V. Okotrub A. G. Kudashov Yu. V. Shubin L. G. Bulusheva 《Journal of Experimental and Theoretical Physics》2009,109(2):254-261
The structure, phase composition, and magnetic properties of carbon nanotubes filled with iron nanoparticles and obtained by thermolysis of a mixture of ferrocene and C60 fullerene or ferrocene and orthoxylene at a temperature of 800°C are investigated. Electron microscopy, X-ray diffraction, and Mössbauer spectroscopy data lead to the conclusion that carbon nanotubes are multilayer systems partially filled with iron nanoparticles and/or nanorods. Metallic inclusions in nanotube channels form α-Fe, γ-Fe, and Fe3C phases. The concentration of each phase in the samples is determined. It is shown that 10–20-nm iron clusters in nanotubes exhibit magnetic properties typical of bulk phases of iron. High elasticity of carbon nanotube walls facilitates stabilization of the high-temperature γ-Fe phase; the relative concentration of this phase in a sample can be increased by lowering the concentration of ferrocene in the initial reaction mixture. 相似文献