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1.
O. Volkova K. Klimov O. Savelieva N. Tristan E. Goodilin B. Buechner A. Vasiliev 《Journal of magnetism and magnetic materials》2006
Magnetic and transport properties of double distorted perovskites CaCuMn6O12 and CaCu2Mn5O12 are studied in a range 2–300 K. The leading role in magnetism of these compounds belongs to antiferromagnetic exchange interaction of Cu2+ in square coordination with Mn3+/Mn4+ in octahedral coordination. The values of saturation magnetization indicate that Mn3+ ions in square coordination are coupled ferromagnetically with Mn3+/Mn4+ in octahedral coordination. The colossal magnetoresistance in the pellet samples is due assumingly to intergranular spin-polarized tunneling of current carriers. 相似文献
2.
We use relations of rational thermodynamics of irreversible processes for a continuous medium with intrinsic state parameters and Eringen’s model of nonlocal theory of elasticity to study the approach to the construction of mathematical models of thermomechanical processes in a deformable body with regard to the effects of temporal and spatial nonlocality of the continuous medium. 相似文献
3.
Zvereva EA Evstigneeva MA Nalbandyan VB Savelieva OA Ibragimov SA Volkova OS Medvedeva LI Vasiliev AN Klingeler R Buechner B 《Dalton transactions (Cambridge, England : 2003)》2012,41(2):572-580
Two synthetic routes-ion-exchange preparation from layered Na(3)Ni(2)SbO(6) at 300 °C and direct solid-state synthesis at 1150 °C resulted in layered Li(3)Ni(2)SbO(6), a cation-ordered derivative from the rocksalt type. The Fddd form reported earlier could not be reproduced. According to the XRD Rietveld analysis, Li(3)Ni(2)SbO(6) is a pseudohexagonal monoclinic structure, C2/m, with a = 5.1828(2) ?, b = 8.9677(3) ?, c = 5.1577(2) ?, β = 109.696(2)°. No Li/Ni mixed occupancy was detected. At high temperatures, the magnetic susceptibility follows the Curie-Weiss law with a positive value of Weiss temperature, ~8 K, indicating a predominance of ferromagnetic interactions. However, Li(3)Ni(2)SbO(6) orders antiferromagnetically at T(N)~ 15 K. The effective magnetic moment is 4.3 μ(B)/f.u. which satisfactorily agrees with theoretical estimations assuming high-spin configuration of Ni(2+) (S = 1). Electron spin resonance (ESR) spectra show single Lorentzian shape line attributed to Ni(2+) ion in octahedral coordination. The absorption is characterized by isotropic temperature independent effective g-factor g = 2.150 ± 0.005. In accordance with the layered honeycomb crystal structure determined for Li(3)Ni(2)SbO(6), the superexchange interaction between Ni(2+) ions through Ni-O-Ni pathways within Ni(2)SbO(6) layers are assumed to be ferromagnetic, while the dominant interaction between layers is antiferromagnetic. 相似文献
4.
L. S. Lussier C. Sandorfy H. OA L E-Thanh D. Vocelle 《Photochemistry and photobiology》1987,45(S1):801-808
Abstract— The Fourier-transform infrared spectra of chloroform-d solutions of conjugated imines CH3 CH=CHCH=NCH(CH3 )2 and CH3 CH2 CH=CHCH=CHCH=NCH(CH3 )2 and the related protonated species with HCl, HBr, HI, trichloro, dichloro, monobromo and monochloroacetic acids or propionic acid are presented. The effects of conjugation and protonation are examined. The results show that conjugation slightly increases the basicity of the Schiff bases. HCl, HBr and HI protonate the Schiff bases completely. The carboxylic acids protonate partially depending on their p K a , values. When the Schiff base contains two (or more) C=C bonds conjugated with C=N, the main C=C stretching band undergoes a strong intensification showing that sizeable dipole moment variations occur along the conjugated chain. 相似文献
5.
S. V. Larionov Z. A. Savelieva L. A. Glinskaya R. F. Klevtsova S. N. Bizyaev A. V. Tkachev 《Journal of Structural Chemistry》2005,46(3):546-550
Interaction of Co(II) chloride with optically active bis-pinane propylenediaminodioxime (H2L) gave a diamagnetic compound of Co(III) with a composition [Co(HL)Cl2]. The crystal and molecular structure of the compound was determined by X-ray diffraction (XRD) analysis (Enraf-Nonius CAD-4 diffractometer, λMoKα, 703 F hkl , R = 0.0347). The crystals are orthorhombic with unit cell parameters a = 8.989(1) Å, b = 12.351(2) Å, c = 22.425(3) Å, V = 2487.7(6) Å3, Z = 4, ρcalc = 1.420 g/cm3, space group P212121. The crystal structure of the complex is composed of discrete one-center molecules. In the complex, the Co3+ ion coordinates four N atoms of the tetradentate cycle-forming ligand (HL? anion) and two Cl atoms. The coordination polyhedron of Co is a distorted octahedron Cl2N4. 相似文献
6.
Published data on the methods and results of study of profiles of volatile biologically active compounds are summarized and discussed. The leading role of gas chromatography-mass spectrometry combined with headspace solid-phase microextraction as an optimum analytical method for determining the qualitative and quantitative composition of volatile organic compounds in in vivo experiments is substantiated. The results of investigation of volatile organic compounds produced by micromycetes of the genus Fusarium are reviewed. 相似文献
7.
The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH2NHC(O)NH2)2](NO3)2 has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) Å3, space group P21/c, Z = 2, d
msd = 2.136 g/cm3, μ(MoK
α) = 2.143 mm−1. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least
squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R
1 = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the
C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied
by the O atoms of the NO
3
−
outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO
3
−
anions are linked into a framework by N-H...O type hydrogen bonds.
Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007. 相似文献
8.
D. V. Karpinsky I. O. Troyanchuk A. P. Sazonov O. A. Savelieva A. Heinemann 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(3):273-279
We have investigated LaCo0.5Mn0.5O3+
δ compounds with different oxygen content by means of magnetization, high resolution and small-angle neutron diffraction measurements.
Oxygen content decrease down to stoichiometric composition leads to an essential increase of TC and magnetic moment while Co/Mn ionic ordering degree is kept almost constant. It is assumed that upon oxygen reduction Co3+ ions change their valence
state down to 2+ one that leads to dominating of Co2+-Mn4+ ferromagnetic interactions as well as TC increase. Magnetic properties can be explained in terms of coexistence of long-range ferromagnetic order and short-range
clusters with antiferromagnetic interactions prevailing. Size distribution of the mentioned short-range magnetic inhomogeneities
is rather mild within the samples but it is strongly temperature dependent. 相似文献
9.
G. V. Romanenko Z. A. Savelieva N. V. Podberezskaya S. V. Larionov 《Journal of Structural Chemistry》1997,38(1):171-176
The coordination compounds of copper(II) chloride and bromide with 1,2,4-triazole (L1) and 4-amino1,2,4-triazole (L2), CuL1Hal2 and CuL2Hal2, possess interesting magnetic properties [1, 2]. For example, at very low temperatures CuL1Cl2 and CuL1Br2 are ferromagnets [2](T
c
≈ 3.3 and 6.5 K, respectively). To explain the magnetic behavior of copper(II) halide complexes with the above nitrogen heterocycles
it is generally assumed that the complexes are polynuclear chain compounds in which the copper atoms are bridged by two halogen
ions and bridging bidentate heterocycle molecules (coordination of N1 and N2 atoms). This hypothesis is made on the basis
of the X-ray diffraction analysis of CuL1Cl2 [3]. It is interesting to perform an X-ray diffraction study of CuL2Cl2 and CuL2Br2; this is important for obtaining reliable magnetostructural correlations for this group of compounds. In this
study, we investigated single crystals of the complexes; this demanded choosing special conditions of synthesis, which differ
from the conditions suggested for the synthesis of polycrystals in [1]. In this communication we report on the results of
synthesis and X-ray diffraction analysis of the single crystals of the coordination compound CuL2Cl2.
Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 1, pp. 207–212, January–February, 1997. 相似文献
10.
G. A. Savelieva G. V. Speranskaya N. M. Popova 《Reaction Kinetics and Catalysis Letters》1980,13(2):121-124
Oxygen interaction with 0.5% Ru/Al2O3 has been studied by the static adsorption and TPD methods. Irreversible adsorption and the existence of a surface molecular species of oxygen (Edes=22 kcal/mol) at Tads=–110 to +25°C have been found. At Tads 85 °C, Ru/Al2O3 oxidation begins with the formation of two more (molecular and atomic) oxygen species with Edes=5 and 107 kcal/mol, respectively.
c 0,55% Rul/-Al2O3. , (=22 /) =–110-+25°C 85° Ru/Al2O3, : (=5 /) (=107 /).相似文献