Центральная Научная Библиотека УрО РАН

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   I-98

    Ivanovskaya, V. V.
    3d metal nanowires and clusters inside carbon nanotubes: Structural, electronic, and magnetic properties [Text] / V. V. Ivanovskaya, C. Kohler, G. Seifert // Physical Review B: Condensed Matter and Materials Physics. - 2007. - Vol. 75, № 7. - P075410/1-075410/7. - Библиогр. : с. 075410/7 (42 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБОНОВЫЕ НАНОТРУБКИ -- МАГНИТНЫЕ СВОЙСТВА
Аннотация: The structure and the properties of the quasi-one-dimensional composites, i.e., carbon nanotubes filled with nanowires or clusters of 3d metals (M=Ti, Fe, and Zn), have been studied in the framework of the density functional-based tight binding method. We show that the accommodation of nanosized metal species inside carbon nanotubes (CNTs) may lead to essential changes of the structural, magnetic, and electronic properties ofthe CNTs and the metal species. Especially, we examined the effect of interactions between iron and carbonatoms on the electronic and magnetic properties of the Fen@CNT composites by comparing with freestandingFe wires and clusters. Our calculations support the increasing of the magnetic moments for both wires as well as clusters encapsulated in CNTs in comparison with bulk bcc Fe and show a strong dependence of magnetic moments on the thickness of the wires and on the size of clusters

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   D 30


    Defect interactions in La0.3Sr0.7Fe(M')O3-delta (M' = Al, Ga) perovskites: Atomistic simulations and analysis of p(O2)-T-delta diagrams [] = Defect interactions in La0.3Sr0.7Fe(M')O3-delta (M' = Al, Ga) perovskites: Atomistic simulations and analysis of p(O2)-T-delta diagrams / E. N. Naumovich, M. V. Patrakeev, V. V. Kharton, M. S. Islam, A. A. Yaremchenko, J. R. Frade, F. M. B. Marques // Solid State Ionics. - 2006. - V. 177, N 5-6. - С. 457-470. - Библиогр.: с. 469-470 (39 назв.) . - ISSN 0167-2738

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КИСЛОРОДНАЯ НЕСТЕХИОМЕТРИЯ -- НЕСТЕХИОМЕТРИЯ КИСЛОРОДНАЯ -- ДЕФЕКТЫ -- ФЕРРИТЫ -- ПЕРОВСКИТЫ -- МОДЕЛИРОВАНИЕ -- ТЕРМОДИНАМИКА -- ОКСИДЫ -- ЛЕГИРОВАНИЕ -- ДОБАВКИ
Аннотация: Atomistic modelling showed that a key factor affecting the p(O2) dependencies of point defect chemical potentials in perovskite-type La0.3Sr0.7Fe1-xM'xO3-delta (M' = Ga, Al; x = 0-0.4) under oxidizing conditions, relates to the coulombic repulsion between oxygen vacancies and/or electron holes. The configurations of A- and B-site cations with stable oxidation states have no essential influence on energetics of the mobile charge carriers, whereas the electrons formed due to iron disproportionation are expected to form defect pair clusters with oxygen vacancies. These results were used to develop thermodynamic models, adequately describing the p(O2)-T-delta diagrams of La0.3Sr0.7Fe(M')O3-delta determined by the coulometric titration technique at 923-1223 K in the oxygen partial pressure range from 1 x 10(-5) to 0.5 atm. The thermodynamic functions governing the oxygen intercalation process were found independent of the defect concentration.
Doping with aluminum and gallium leads to increasing oxygen deficiency and induces substantial changes in the behavior of iron cations, increasing the tendencies to disproportionation and hole localization. Despite similar oxygen nonstoichiometry in the Al- and Ga-substituted ferrites at a given dopant content, the latter tendency is more pronounced in the case of aluminum-containing perovskites

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   D 30


    Deformation-induced transformations in nitride layers formed in bcc iron [Текст] / V. A. Shabashov, S. V. Borisov, A. E. Zamatovsky, N. F. Vil'danova, A. G. Mukoseev, A. V. Litvinov, O. R. Shepatkovskii // Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing. - 2007. - № A452-A453. - С. 575-583

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
НИТРИДЫ -- ЖЕЛЕЗО

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   D 46


    Desulfurization of recycled vanadium-bearing raw materials [Text] / A. V. Sirin, T. I. Krasnenko, V. G. Mizin, T. P. Sirina, M. V. Rotermel', O. S. Pozdnyakova // Metallurgist . - 2006. - Vol. 50, № 11-12. - P565-570. - Библиогр. : с. 570 (6 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ДЕСУЛЬФУРАЦИЯ -- ВАНАДИЕВОЕ СЫРЬЕ
Аннотация: A study of model systems that include sodium vanadate, sulfates of nickel, iron, and calcium, and a soda solution made it possible to determine the optimum parameters for desulfurizing high-sulfur wastes formed in the operation of heating and power plants. It is shown that when Ni/V = 0.15–0.33 and Fe/V = 0.5–0.75, 98% of the vanadium and 99.8% of the nickel are precipitated and sulfur content is no greater than 0.2 mass%. This has made it possible to obtain concentrates suitable for the smelting of complex alloys

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   Y 95

    Yur`eva, E. I.
    Differences of the Quadrupole Splitting and Iron ElectronicStructure for the Heme Models for alfa and beta Subunits in Deoxyhemoglobin and for Deoxymyoglobin:Quantum-Chemical Calculationsby the DFT–DVM Method / E. I. Yur`eva, M. I. Oshtrakh // Bulletin of the Russian Academy of Sciences: Physics. - 2007. - Vol. 71, № 9. - P.1229-1234 : il. - Bibliogr. : p. 1233-1234 (33 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
РАСЧЕТЫ КВАНТОВО-ХИМИЧЕСКИЕ -- КВАДРУПОЛЬНОЕ РАСЩЕПЛЕНИЕ -- ЖЕЛЕЗО -- СТРУКТУРА ЭЛЕКТРОННАЯ -- ПРОТЕИНЫ
Аннотация: The quantum-chemical calculation of the iron electronic structure and 57 Fe quadrupole splitting??have been performed by the DFT.DVM method for rough heme models for alfa and beta subunits in deoxyhemoglobin and for deoxymyoglobine, which take into account stereochemical differences of the active cites in native proteins. The calculations revealed differences in the temperature dependences of quadrupole splitting??for the three models, indicating sensitivity of the quadrupole splitting and Fe(II) electronic structure to small stereochemical variations in the nearest iron environment. The theoretical results confirmed the possibility of approximating experimental Mossbauer spectra of tetrameric hemoglobins with allowance for the nonequivalence??of the Fe(II) electronic structure in nonidentical subunits

\\\\Expert2\\nbo\\Bulletin of the Russian Academy of Sciences Physics\\2007, V. 71, N 9, P.1229-1234.pdf
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   E 27


    Effect of Chromium on the Electronic Structure and Magnetic Properties of Cementite / N. I. Medvedeva, I. R. Shein, M. A. Konyaeva, A. L. Ivanovskii // The Physics of Metals and Metallography. - 2008. - Vol. 105, № 6. - P568-573 : il. - Bibliogr. : p. 572-573 (24 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ХРОМ -- МАГНИТНЫЕ СВОЙСТВА -- ЦЕМЕНТИТ
Аннотация: Using ab initio methods, the influence of chromium on the electron structure and magnetic properties of cementite Fe3C has been investigated depending on the chromium concentration and the possibility of the formation of a chromium carbide Cr3C has been considered. It has been established that it is the general positions of iron in the lattice of cementite that are most energetically preferable for the substitution by chromium. Chromium leads to a strengthening of interatomic interactions and the change in the sign of the enthalpy of formation in the Fe3 –xCrxC system at x= 1.9. The magnetic moments at the atoms of chromium and iron are oriented antiferromagnetically and the total magnetization of the alloyed system decreases with increasing chromium concentration

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   M 46

    Medvedeva, N. I.
    Effect of Chromium on the Electronic Structure of the Cementite Fe3C / N. I. Medvedeva, L. E. Kar'kina, A. L. Ivanovskii // Physics of the Solid State. - 2006. - Vol. 48, № 1. - P15-19 : il. - Bibliogr. : p. 19 (15 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ХРОМ -- ЭЛЕКТРОННАЯ СТРУКТУРА -- ЦЕМЕНТИТЫ
Аннотация: The effect of alloying of the cementite Fe3C with chromium on the band structure, atomic interactions, electric field gradients, and asymmetry parameters for iron nuclei is investigated using the self-consistent full-potential linear muffin-tin orbital (FPLMTO) method. An increase in the cohesive energy for the Fe3C–Cr system indicates an enhancement of the atomic interactions in the lattice of the cementite alloyed with chromium. It is found that the substitution of chromium for iron in the FeII positions containing eight equivalent iron atoms is energetically most favorable

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   Y 95

    Yurieva, E. I.
    Effect of oxygen deficit on the state of iron atoms and 57Fe Mossbauer spectral parameters in YBa2(Cul-xFex)306.0 by the results of Xalfa-DV calculations / E. I. Yurieva, V. P. Zhukov, V. A. Gubanov // Journal of Structural Chemistry. - 1993. - Vol. 34, № 4. - P552-556 : il. - Bibliogr. : p. 556 (5 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЖЕЛЕЗО -- МЕТОД ДИСКРЕТНОГО ВАРЬИРОВАНИЯ -- КЛАСТЕРЫ -- КЕРАМИКА ИТТРИЕВО-БАРИЕВАЯ
Аннотация: The electronic structure of the clusters [FemOn] m-zn, which model local structure defects arising in doping the tetragonal phase of yttrium-barium ceramics with iron atoms, has been calculated using the Xa-discrete variation (DV) method. According to the results of calculations of the hyperfine magnetic field and the quadrupole splitting of 57Fe MOssbauer spectra in YBa2(Cul-xFex)306.0, the gamma resonance (GR) doublet with quadrupole splitting [A [ ~ 2 mm/s is most likely attn'butable to the Fe atoms localized in the Cu(1) position and having the valence 2 + and a dumbbell configuration of the nearest environment cluster

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   Z 18

    Zainullina, V. M.
    Electronic and magnetic structures and conductivity of strontium ferrite. An ab initio LSDA + U approach [Текст] / V. M. Zainullina, M. A. Korotin, V. L. Kozhevnikov // Russian Journal of Electrochemistry. - 2007. - Vol. 43, № 5. - С. 570-575. - Библиогр. : с. 575 (16 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ФЕРРИТ СТРОНЦИЯ -- ЭЛЕКТРОННАЯ СТРУКТУРА
Аннотация: Using the first-principle nonempirical linear muffin-tin orbital method in the tight-binding approximation (TB-LMTO) to the LSDA + U approximation, the electronic and magnetic structures and defect formation in strontium ferrite Sr3Fe2O6 are studied. It is found that Sr3Fe2O6 is a G type antiferromagnetic with the semiconductor electronic structure. The calculated band gap of 1.82 eV agrees well with experimental value (~2 eV). The ferrite spectrum corresponds to that of a semiconductor with a band gap of charge transfer. Iron ions in Sr3Fe2O6 are in a high-spin state and have configuration t2g↑3 eg↑2 eg↓1. The calculated local magnetic moment on the iron ions is 3.9μB. The presence of iron ions with a magnetic moment approaching 4μB in Sr3Fe2O6 is explained by strong hybridization of 3d orbitals of iron and 2p orbitals of oxygen. The high-spin state of iron ions is described by d5+d6L states with predominant contribution d6L, where L is a hole on oxygen. Based on ab initio LSDA + U calculations, various types and configurations of defects in the oxygen sublattice (oxygen vacancies, anti-Frenkel defects) are studied and a model for ionic transport in Sr3Fe2O6is proposed

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10.

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   S 53

    Shein, I. R.
    Electronic structure and magnetic properties of Fe3C with 3d and 4d impurities [Text] / I. R. Shein, N. I. Medvedeva, A. L. Ivanovskii // Physica Status Solidi B: Basic Solid State Physics. - 2007. - Vol. 244, № 6. - P1971-1981. - Библиогр. : с. 1981 (41 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЭЛЕКТРОННАЯ СТРУКТУРА -- МАГНИТНЫЕ СВОЙСТВА -- КАРБИД ЖЕЛЕЗА -- ПЕРЕХОДНЫЕ МЕТТАЛЛЫ
Аннотация: We study the electronic structure, formation energies, and magnetic properties of cementite Fe3C doped by 3d and 4d transition metals (TM) by means of first-principles calculations. All TM elements demonstrate a preference for the substitution of the general iron position in Fe3C. We predict that early elements (Sc, Ti, V, Cr, Zr, and Nb) stabilize the cementite, while the end elements (Ni, Cu, Pd, and Ag) in the TM series sharply destabilize it. The magnetic properties of impurity atoms are found to depend strongly on their atomic numbers and the trends to ferromagnetic or antiferromagnetic coupling of impurities with Fe atoms in Fe3C coincide with the magnetic behavior of these impurities in Fe. The physical reason is a similar location of the Fermi level in the pseudogap of spin-down and almost filled spin-up Fed states in both Fe3C and Fe

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11.

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   M 46

    Medvedeva, N. I.
    Electronic Structure and Magnetic Properties of the alfa and gamma Phases of Iron, Their Solutions with Carbon, and Cementite / N. I. Medvedeva, L. E. Kar'kina, A. L. Ivanovskii // The Physics of Metals and Metallography. - 2006. - Vol. 101, № 5. - P440-445 : il. - Bibliogr. : p. 444-445 (31 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЖЕЛЕЗО -- ТВЕРДЫЕ РАСТВОРЫ -- УГЛЕРОД
Аннотация: The full-potential LMTO method was used to comparatively analyze the band structure, magnetic and cohesive characteristics, energies of formation of α and γ iron, their carbon solid solutions, and cementite. It has been found that the solid solution γ-Fe + C, similarly to γ-Fe, is characterized by an antiinvar transition and that cementite demonstrates invar behavior. The similarity of curves of the density of states, cohesive energies, and magnetic moments for the supersaturated solid solution of carbon in the fcc iron and cementite suggests the preferable formation of cementite in regions of concentration inhomogeneity of carbon distribution in the solid solution of γ iron the solid solution of γ iron

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12.

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   M 46

    Medvedeva, N. I.
    Electronic structure and magnetic properties of б- and г- phases of iron, their solid solutions with carbon, and of cementite [Текст] / N. I. Medvedeva, L. E. Kar'kina, A. L. Ivanovskii // Physics of the Solid State. - 2006. - Vol. 48, № 1. - С. 15-19. - Библиогр. : с. 19 (15 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ

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13.

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   E 43


    Electronic Structure and Magnetic States of Crystalline and Fullerene-Like Forms of Nickel Dichloride NiCl2 / A. N. Enyashin, N. I. Medvedeva, Yu. E. Medvedeva, A. L. Ivanovskii // Physics of the Solid State. - 2005. - Vol. 47, № 3. - P527-530 : il. - Bibliogr. : p. 530 (12 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ДИХЛОРИД НИКЕЛЯ -- ФУЛЛЕРЕНЫ -- ФЕРРОМАГНЕТИКИ -- СТЕХИОМЕТРИЯ
Аннотация: The electronic structure and magnetic properties of the crystalline and fullerene-like forms of nickel dichloride NiC² are investigated in the framework of the local spin density functional theory. It is demonstrated that the band gap can be reproduced in the energy band spectrum of the NiCl² compound with inclusion of the magnetic ordering in the calculation of the band structure. The metamagnetic nature of the NiCl² dichloride (i.e., the transition from an antiferromagnetic phase to a ferromagnetic phase in a weak magnetic field) is explained in terms of a small difference (0.025 eV/cell) between the total energies of the ferromagnetic and antiferromagnetic phases. Polyhedral three-shell nanoparticles of the NiCl² compound exhibit magnetic properties (the magnetic moment of nickel lies in the range 2.0–2.3 µβ). For isostructural nanoparticles of the FeCl² dichloride, the magnetic moment of iron is larger and falls in the range 4.2–4.5 µβ, whereas nanoparticles of the CdCl² dichloride are found to be nonmagnetic. The results of analyzing the interatomic interactions indicate that the composition of fullerene-like nanoparticles of the dichlorides under investigation can deviate from the 1 : 2 stoichiometric composition

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14.

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   Z 18

    Zainullina, V. M.
    Electronic structure and properties of strontium ferrite Sr3Fe2O6 [Text] / V. M. Zainullina, M. A. Korotin, V. L. Kozhevnikov // European Physical Journal B: Condensed Matter Physics. - 2006. - Vol. 49, № 4. - P425-431. - Библиогр. : с. 431 (18 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЭЛЕКТРОННАЯ СТРУКТУРА -- ФЕРРИТ СТРОНЦИЯ
Аннотация: The electronic structure of strontium ferrite Sr3Fe2O6 was calculated using the tight-binding linear muffin-tin orbital method (TB LMTO) in the local spin density approximation of density functional theory with Coulomb correlations correction (LSDA+U). The semiconducting character of the spectrum with charge transfer energy gap of 1.82 eV was obtained in reasonably good agreement with experimental data. The iron ions are found to be in the high spin state. The calculated value of the local spin magnetic moment of Fe3+ ion is 3.94 μB which is not typical for trivalent iron ion in the high spin state. It is shown that the strong hybridization between Fe3d and O2p orbitals favors the d6L configuration of Fe3+ ion, where L is a hole in the oxygen p shell. The mechanism of oxygen transport in ferrite is discussed basing on the total energy calculations of the different spatial configurations of oxygen vacancies

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15.

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   S 53

    Shein, I. R.
    Electronic structure of new oxygen-free 38 K superconductor Ba1-xKxFe2As2 in comparison with BaFe2As2 from first principles / I. R. Shein, A. L. Ivanovskii // Письма в Журнал экспериментальной и теоретической физики. - 2008. - Т. 88, Вып. 1-2. - С. 115-118 : граф., ил. - Библиогр.: с. 118 (28 назв.) . - ISSN 0370-274X

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
СВЕРХПРОВОДНИКИ -- ЭЛЕКТРОННАЯ СТРУКТУРА -- АРСЕНИДЫ
Аннотация: Based on first principles FLAPW-GGA calculations, we have investigated the electronic structure of the newly discovered oxygen-free 38 K superconductor Ba1-xKxFe2As2 in comparison with a parent phase- the tetragonal ternary iron arsenide BaFe2As2. The density of states, magnetic properties? near-Fermi bands compositions, together with Sommerfeld coefficient y and molar Pauli paramagnetic susceptibility x have been evaluated. The results obtained allow us to classify these systems as quasi-two-dimensional ionic metals, where conduction is strongly anisotropic, happening only in the (Fe-As) layres. According to our calculations, in the case of hole doping of BaFe2As2, the density of states at the Fermi level grows, which, possibly, may be a factor promoting the occurence of superconductivity for Ba1-xKxFe2As2. On the other hand, Ba1-xKxFe2As2 lies at the border of magnetic instability and pairing interactions might involve magnetic or orbital fluctuations

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16.

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   K 72

    Konyaeva, M. A.
    Electronic Structure, Magnetic Properties, and Stability of the Binary and Ternary Carbides (Fe,Cr)3C and (Fe,Cr)7C3 / M. A. Konyaeva, N. I. Medvedeva // Physics of the Solid State. - 2009. - Vol. 51, № 10. - P2084-2089 : il. - Bibliogr. : p. 2088-2089 (29 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБИД ЖЕЛЕЗА -- КАРБИД ХРОМА -- КАРБИДЫ БИНАРНЫЕ -- КАРБИДЫ ТРОЙНЫЕ
Аннотация: The structural, electronic, and magnetic properties of the binary and ternary carbides (Fe,Cr)3C and (Fe,Cr)7C3 have been investigated within the ab initio density functional theory. The crystal structure of the binary carbides has been optimized and the preferred positions for replacement of chromium or iron impurities in the corresponding carbides have been determined. The changes in the electronic structure and magnetic properties have been investigated, the formation energies of the ternary carbides as functions of the impurity concentrations have been calculated, and conclusions have been drawn regarding the influence of the impurity on the stability of the carbides under investigation

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17.

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   Z 18

    Zainullina, V. M.
    Electronic Structures, Chemical Bonding, and Defect Formation in Mixed Cyanoferrates M2Cu[Fe(CN)6] (M=Na, K, Rb, and Cs) / V. M. Zainullina, E. V. Polyakov, L. G. Maksimova // Russian Journal of Coordination Chemistry. - 2007. - Vol. 33, № 7. - P493-500 : il. - Bibliogr. : p. 500 (18 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЦИАНОФЕРРАТЫ -- ЩЕЛОЧНЫЕ МЕТАЛЛЫ
Аннотация: The effect of the alkali metal nature on the electronic structures and chemical bonding in mixed cyanoferrates M2Cu[Fe(CN)6](M = Na, K, Rb, and Cs) was studied by ab initio tight-binding linear muffin-tin orbital (TB-LMTO) method (in the spin-polarized implementation) and the extended Hückel molecular orbital (EHMO) method. It was found that the X-ray photoelectron spectra of the ferrimagnetic compounds Na2Cu[Fe(CN)6] (I),K2Cu[Fe(CN)6] (II),Rb2Cu[Fe(CN)6](III), and Cs2Cu [Fe(CN)6](IV) are similar. The magnetic moments on Cu2+ and iron ions remain virtually constant in compounds I–IV(μ(Cu)≈0.9μB,μ(Fe)<−0.06μB). Analyses of the electron density maps and the bond overlap populations showed that the cubic frameworks of cyanoferrates are built from stable fragments …–Fe–C≡N–Cu–…. The bond strength in these fragments decreases substantially in the order C–N→Fe-C→Cu–N and only slightly in the order IV→III→II→I. The calculated total energies of the cyanoferrates Cs2–xCu[Fe(CN)6], CsHCu[Fe(CN)6], and NaHCu[Fe(CN)6] for different concentrations and configurations of defects (cesium vacancies and hydrogen substitution defects) suggest mutual repulsion of defects. This repulsion is responsible for the experimentally observed lowering of the ionic conductivity with an increase in the defect concentration in the mixed cyanoferrates

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18.

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   S 53

    Shein, I. R.
    Energy-band structure of the A(Sn1-xMx)O3 (A = Ca, Sr, Ba; M = Mn, Fe, Co) perovskite-type phases: A search for new magnetic semimetals [Text] / I. R. Shein, V. L. Kozhevnikov, A. L. Ivanovskii // Semiconductors. - 2006. - Vol. 40, № 11. - P1261-1265. - Bibliogr. : p. 1265 (19 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ПЕРОВСКИТОПОДОБНЫЕ ОКСИДЫ -- ЭЛЕКТРОМАГНИТНЫЕ СВОЙСТВА
Аннотация: The full-potential LAPW method in the local spin-density approximation (LSDA) is applied to the theoretical search for new magnetic semimetals on the basis of a nonmagnetic SrSnO3 semiconductor doped with magnetic ions M = Mn, Fe, Co. It is found that, in contrast to Sr2SnMnO6 (a ferromagnetic semiconductor) and Sr2SnCoO6(a ferromagnetic metal), Sr2SnFeO6 perovskite is a ferromagnetic semimetal: its electronic spectrum has a band gap (~0.7 eV) for the low-spin subsystem and is metal-type for the high-spin subsystem. For isoelectronic analogs SrSnO3 –CaSnO3 and BaSnO 3, it is shown that their doping by iron (Ca2SnFeO6 and Ba2SnFeO6 compositions) also makes it possible to realize the semimetal state of these systems. It is assumed that A(Sn1 –xFex)O3(A = Ca, Sr, Ba) solid solutions can become the first representatives of a new group of materials for spin electronics

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19.

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   K 81

    Krasil'nikov, V. N.
    Ethylene Glycol-Modified Cobalt and Iron Oxalates As Precursors for the Synthesis of Oxides As Extended Microsized and Nanosized Objects / V. N. Krasil'nikov, O. I. Gyrdasova, G. V. Bazuev // Russian Journal of Inorganic Chemistry. - 2008. - Vol. 53, № 12. - P1854-1861 : il. - Bibliogr. : p. 1860-1861 (18 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ЭТИЛЕНГЛИКОЛЬ -- КОБАЛЬТ -- ОКСИДЫ -- ОКСАЛАТ ЖЕЛЕЗА
Аннотация: The reactions of ethylene glycol with iron and cobalt oxalates upon heating in air are reported. Heat treatment of mixtures of oxalate powders with ethylene glycol yields new compounds (solvates) via the replacement of the water molecules in the oxalate structure by ethylene glycol molecules: MC2O4·2H2O+HOCH2CH2OH=MC2O4(HOCH2CH2OH)+2H2O↑. The crystals resulting from this reaction are elongated, and their shape is inherited by their thermolysis products. Thermolysis in air yields microwhiskers and nanowhiskers of Fe2O3and Co3O4, and thermolysis in an inert atmosphere affords Fe3O4and Co whiskers. The thermolysis of FeC2O4(HOCH2CH2OH) in helium yields a new structural modification of FeC2O4 as an intermediate product. The resulting compounds and their thermolysis products were characterized by X-ray powder diffraction, microscopy, IR spectroscopy, and thermogravimetric and chemical analyses. The particle shape and size were determined by scanning electron microscopy

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20.

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   H 65


    High-temperature phase equilibria in the oxide systems SrFe1-xGaxO2.5-SrFe1-xGaxO3 (x = 0, 0.1, 0.2) [Text] / I. A. Leonidov, M. V. Patrakeev, J. A. Bahteeva, E. B. Mitberg, V. L. Kozhevnikov, Ph. Colomban, K. R. Poeppelmeier // Journal of Solid State Chemistry. - 2006. - Vol. 179, № 4. - P.1093-1099. - Bibliogr. : p. 1099 (17 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ФАЗОВЫЕ РАВНОВЕСИЯ -- СИСТЕМЫ ОКСИДНЫЕ -- ВЫСОКОТЕМПЕРАТУРНЫЕ ФАЗОВЫЕ ДИАГРАММЫ -- ГАЛЛИЙ -- ДОБАВКИ
Аннотация: X-ray powder diffraction, Raman scattering, equilibrium oxygen content and conductivity data are combined to construct high-temperature phase diagrams (T vs. delta) for the oxide systems SrFe1-xGaxO2.5–SrFe1-xGaxO3, where , 0.1, and 0.2. Depending on oxygen content and gallium doping, three different structural types are shown to exist at high temperatures including cubic perovskite-, cubic brownmillerite-, and orthorhombic brownmillerite-type structures. Substitution of gallium for iron is shown to extend the oxygen content and temperature limits where the cubic brownmillerite-type phase is stable

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