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41.
A. A. Samokhvalov T. I. Arbusova N. A. Viglin S. V. Naumov V. R. Galakhov D. A. Zatsepin Yu. A. Kotov O. M. Samatov D. G. Kleshchev 《Physics of the Solid State》1998,40(2):268-271
This paper describes the problem of high-temperature superconductivity related to investigations of the magnetic susceptibility,
electron paramagnetic resonance, and O Kα x-ray emission spectra of samples from the following systems based on copper monoxide: CuO-Cu, CuO-Cu2O and CuO-MgO. In all these systems, thermal processing results in a paramagnetism which is not observed in the individual
components of these systems before they are processed. O Kα spectra of the interface of a Cu-single-crystal CuO film structure indicate the presence of not only Cu2+ but also Cu1+ ions in the layer of CuO in close contact with Cu. Possible reasons for the appearance of paramagnetism in these systems
are discussed. It is proposed that a paramagnetic layer at the contact between the antiferromagnetic copper monoxide and the
other copper-oxide phases or with copper could be the cause of the impurity metastability observed previously in the high-T
c superconducting phase.
Fiz. Tverd. Tela (St. Petersburg) 40, 295–298 (February 1998) 相似文献
42.
N. I. Solin L. N. Romashev S. V. Naumov A. A. Saranin A. V. Zotov D. A. Olyanich V. G. Kotlyar O. A. Utas 《Technical Physics》2016,61(2):233-239
We consider methods for controlling magnetoresistive parameters of magnetic metal superlattices, manganites, and magnetic semiconductors. By reducing the thickness of ferromagnetic layers in superlattices (e.g., Fe layers in Fe/Cr superlattices), it is possible to form superparamagnetic clustered–layered nanostructures with a magnetoresistance weakly depending on the direction of the external magnetic field, which is very important for applications of such type of materials. Producing Mn vacancies and additionally annealing lanthanum manganites in the oxygen atmosphere, it is possible to increase their magnetoresistance by more than four orders of magnitude. By changing the thickness of p–n junction in the structure of ferromagnetic semiconductors, their magnetoresistance can be increased by 2–3 orders of magnitude. 相似文献
43.
P. B. Novikov D. Yu. Naumov E. V. Boldyreva N. V. Podberezskaya 《Journal of Structural Chemistry》1998,39(3):333-342
The structure of [Co(NH3)5NO2]C2O4 is solved and refined (space group Immm, a=7.428(2), b=9.790(3), c=6.568(1) Å, V=477.6(2) Å3, Z=2; R1=0.0177, wR2=0.0279 for F2>4σ(F2); R1=0.1177, wR2=0.0643 for all data; residual electron density from 0.125 to ?0.140 e/Å3). Specific contacts in the structure are analyzed. Crystal chemical interpretation is suggested to explain the occurrence of photodecomposition rather than photochemical bond isomerization under the action of light in cobalt(III) nitropentammoniate oxalate crystals, in contrast to all previously investigated cobalt(III) nitropentammoniates. 相似文献
44.
45.
I. M. Davletbaeva V. F. Shkodich A. M. Gumerov O. Yu. Emelina A. V. Naumov 《Polymer Science Series A》2010,52(4):392-397
The interaction of 2,4-toluylene diisocyanate with open-chain analogs of crown ethers containing potassium alcoholate groups is studied, and the mechanism of stabilization of the formed O-polyisocyanate end units via intermolecular interactions is proposed. The electron delocalization in intermolecular cyclic structures may be responsible for electron-transfer processes in the polymers under study. 相似文献
46.
47.
Mitkina TV Sokolov MN Naumov DY Kuratieva NV Gerasko OA Fedin VP 《Inorganic chemistry》2006,45(17):6950-6955
The unprecedented selective encapsulation of trans-[Co(en)2Cl2]+ from the mixture of trans and cis isomers into the cavity of macrocyclic cavitand cucurbit[8]uril (C48H48N32O16, CB[8]) leads to the inclusion compound {trans-[Co(en)2Cl2]@CB[8]}Cl.17H2O (1). Single-crystal X-ray analysis, 1H NMR, and ESI-MS spectra confirm the formation of host-guest complex 1 in both solid state and solution. The geometry of the complex cation alters significantly upon inclusion, which causes appreciable hypsochromic shifts of the absorption bands of the guest complex. According to TGA data, inclusion of trans-[Co(en)2Cl2]+ dramatically stabilizes the complex toward thermal decomposition. Encapsulation of trans-[Co(en)2Cl2]+ into the CB[8] cavity also increases the stability of the metal complex toward isomerization into the cis form. The supramolecular adduct {cis-[Co(en)2(H2O)2](CB[8])6}Cl3.ca109.5H2O (2) was isolated only after prolonged heating of an aqueous solution of 1 at 120 degrees C in an evacuated tube; it was characterized by X-ray crystallography, IR, and elemental analysis. 相似文献
48.
I. A. Litvinov O. N. Kataeva V. A. Naumov F. F. Guseva O. N. Nuretdinova 《Journal of Structural Chemistry》1994,34(5):823-826
A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 185–188, September–October, 1993. 相似文献
49.
A. Yu. Ledneva N. G. Naumov A. V. Virovets S. Cordier Y. Molard 《Journal of Structural Chemistry》2012,53(1):132-137
The structures of three novel octahedral rhenium cluster compounds [Re6S8(CN)2(py)4]·H2O (1), [Re6S8(CN)2(4-Mepy)4] (2), [Re6S8(CN)2(4-Mepy)4]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, c = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) Å3, d x = 3.318 g/cm3, R = 0.0585 (1); I41/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) Å3, d x = 3.169 g/cm3, R = 0.0489 (2); P21/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) Å3, d x = 2.957 g/cm3, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3. 相似文献
50.
Thomas S Biswas N Venkateswaran S Kapoor S Naumov S Mukherjee T 《The journal of physical chemistry. A》2005,109(44):9928-9934
The surface-enhanced Raman scattering (SERS) studies of 5-amino tetrazole (5AT), a tetrazole derivative, in aqueous silver sol at pH approximately 9 and on deposited colloidal silver films were carried out and compared with the normal Raman spectrum of the molecule. The experimentally observed Raman bands along with their corresponding infrared bands were assigned based on the results of density functional theory (DFT) calculations. The significant changes evidenced between the SERS and the normal Raman spectra combined with the theoretical data obtained for Ag-5AT system demonstrated that the molecule is adsorbed on colloidal Ag particles through the lone pair of electrons of the nitrogen atom. The contribution of the chemical mechanism for the SERS enhancement was proved by the behavior of the electronic absorption spectrum of the Ag colloid upon addition of 5AT. This is further supported by the theoretical calculations that show that the favorable interaction of the frontier orbitals localized on Ag(+) and the negatively charged nitrogen from the tetrazole ring leads to the formation of the stable (up to 130 kJ mol(-1)) charge-transfer complex. The orientation of the adsorbed species with respect to the metal surface was also predicted by applying the "surface selection rule". In addition, the feasibility of the formation of the polymeric species has also been discussed. 相似文献