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41.
Troyanchuk I. O. Bushinsky M. V. Sikolenko V. V. Ritter C. 《Journal of Experimental and Theoretical Physics》2019,128(1):98-104
Journal of Experimental and Theoretical Physics - The dependence of the properties of the La0.45Ba0.55CoO3 – δ and La0.4Ba0.6CoO3 – δ cobaltites on the oxygen content has been... 相似文献
42.
I. O. Troyanchuk D. V. Karpinskii V. M. Dobryanskii Yu. A. Fedotova H. Szymczak 《Journal of Experimental and Theoretical Physics》2005,100(6):1121-1126
The preparation conditions and magnetic properties of the La(Co1?xFex)O3?d system of solid solutions were studied. Irrespective of synthesis conditions, the samples with x ≤ 0.15 were rhombohedral (space group \(R\bar 3c\)), and those with x ≥ 0.7, orthorhombic (space group Pnma). In the intermediate region of 0.15 < x < 0.7, the samples could be mixtures of rhombohedral and orthorhombic phases. Structural heterogeneity considerably decreased as the temperature of the synthesis increased or after annealing in a reducing medium. The samples containing more than 40% iron exhibited weak spontaneous magnetization, as is characteristic of weak ferromagnets. The magnetic properties and structure depend on the content of oxygen. A decrease in the concentration of oxygen sharply increases magnetic anisotropy; the coercive force is then close to 10 kOe, which is more than that known for other oxide systems. The magnetic properties are explained in terms of the model according to which Co3+ ions are in the low-spin state. 相似文献
43.
The crystal structure of NdCoO3 is studied by neutron diffraction. It is shown that static cooperative Jahn—Teller distortions are absent up to the temperature of transition to the metallic state. The results are discussed within the model considering the transition of cobalt ions from the low-spin to the intermediate-spin state by gradual thermal excitation without a clearly pronounced critical behavior. 相似文献
44.
I.O. Troyanchuk H. Szymczak N.V. Kasper A. Nabialek 《Journal of solid state chemistry》1997,130(2):171-175
The crystal structure and magnetic properties of orthomanganitesA1−xMnO3+y(A=La, Eu;x≤0.2;y≤0.13) were investigated. It was shown that the increase of oxygen content leads to the transformation from the weak ferromagnetic to the ferromagnetic state in these compounds. The Curie temperatures of La1−xMnO3+yand freezing temperatures of magnetic clusters for Eu1−xMnO3+yin the samples with a deficit ofAcations are higher than those in parent compounds (withx=0). A mixed magnetic state involving ferro- and antiferromagnetic domains is suggested in the intermediate range ofx,yvalues. Arguments are presented to support the assumption that the magnetic properties in the lightly doped insulating regime are governed by superexchange via anions rather than by exchange via charge carriers. 相似文献
45.
I.O. Troyanchuk M.V. Bushinsky H. Szymczak M. Baran K. Bärner 《Journal of magnetism and magnetic materials》2007
Powder neutron diffraction and magnetic studies have been performed for NdMn0.5Fe0.5O3 and NdMn0.5Cr0.5O3 manganites. In NdMn0.5Cr0.5O3, magnetic structure has been revealed consisting of ferromagnetic and G-type antiferromagnetic components as result of a 3d-ions magnetic moments ordering. Magnetic moments of Nd-ions are parallel to the ferromagnetic component. In NdMn0.5Fe0.5O3 only the antiferromagnetic G-type structure has been found whereas Nd-sublattice was not ordered. In the both compounds, magnetic moments of 3d-ions are significantly less than one can expect, what is interpreted in terms of intrinsic chemical inhomogeneity. Magnetic phase diagrams have been constructed for the Nd(Mn1−xMx)O3 (M=Fe, Cr) systems, interpreted assuming superexchange interactions Mn3+–O–Cr3+ to be positive, Mn3+–O–Fe3+ negative and taking into account a disordered arrangement of Mn and Cr ions in the crystal structure sublattice as well as interplay between Jahn–Teller effect and superexchange interactions. 相似文献
46.
V. A. Khomchenko J. A. Paixo B. F. O. Costa D. V. Karpinsky A. L. Kholkin I. O. Troyanchuk V. V. Shvartsman P. Borisov W. Kleemann 《Crystal Research and Technology》2011,46(3):238-242
Room temperature crystal structure, ferroelectric and magnetic properties of polycrystalline Bi0.85Sm0.15FeO3 samples were investigated. X‐ray diffraction study shows that the compound possesses a dominant PbZrO3‐like orthorhombic structure with √2a ×2√2a ×2a superlattice (a is the parameter of the cubic perovskite subcell). In contrast to piezoresponse force microscopy data demonstrating some features characteristic of ferroelectrics, polarization vs. electric field measurements reveal the behavior expected for nonpolar materials. Investigation of magnetic properties confirms that 15% samarium substitution suppresses the spin modulation typical of BiFeO3 and induces the appearance of spontaneous magnetization. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
47.
D.D. Khalyavin A.M. Balagurov I.O. Troyanchuk E.V. Tsipis 《Journal of solid state chemistry》2004,177(6):2068-2072
The crystal and magnetic structures of layered perovskites TbBaCo2−xFexO5+γ (0.08?x?0.24) were studied by neutron powder diffraction. Increasing iron concentration up to the x values higher than 0.10 leads to the orthorhombic→tetragonal phase transition resulting from the transformation of 2×1×1-type superstructure, formed due to ordering of extra oxygen incorporated into the vacant sites in [TbOγ] layers, into 3×3×1 superlattice. The concentration ranges, where the orthorhombic and tetragonal lattices exist, are separated with a narrow two-phase domain. For the tetragonal phases with 3×3×1 superstructure (space group P4/mmm), the Co/Fe ions are antiferromagnetically coupled, forming G-type spin-ordered configuration. The Co3+ cations located in square-pyramidal sites adopt intermediate spin state, whilst a relatively small magnetic moment of Co3+ ions in the octahedral sublattice indicates that a minor fraction of cobalt is in the low-spin state. 相似文献
48.
Troyanchuk I. O. Bushinsky M. V. Dobryanskii V. M. Pushkarev N. V. 《JETP Letters》2012,94(12):849-852
JETP Letters - In layered Sr3YCo4O10.5 + δ-type cobaltites with different oxygen contents, we have observed a first order magnetic phase transition from the high-temperature... 相似文献
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50.
L. S. Lobanovskii I. O. Troyanchuk H. Szymczak 《Journal of Experimental and Theoretical Physics》2000,91(3):537-540
The purpose of this work is to establish the relation between the magnetic, electric, and magnetotransport properties and the oxygen nonstoichiometry of the compounds Ba2(FeMo)O x (5.88 ≤ x ≤ 6.01). The investigations established the behavior of the magnetization, resistance, and magnetoresistance of samples in this series. It is shown that the behavior of the magnetization can be described by assuming that the iron ions become divalent (Fe3+→ Fe2+) as a result of the reduction of the samples and the molybdenum ions become hexavalent (Mo5+ → Mo6+) as a result the oxidation of the samples. It is established that there are two contributions to the magnetoresistance which arise as result of magnetic ordering of the intragranular interlayer and intergranular transfer of spin-polarized charge carriers. It is inferred that electric transport in samples of this series is determined by percolation processes between granules with metallic conductivity separated by a dielectric interlayers. 相似文献