T. V. Aksenova

Crystal structure and physicochemical properties of layered perovskite-like phases LnBaCo2O5 + δ

Complex oxides LnBaCo2O5 + δ (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y) were obtained by solid-state synthesis at 1373 K in air. The crystal structure of layered perovskites LnBaCo2O5 + δ was studied by X-ray and neutron diffraction analyses. It was shown that cobaltites LnBaCo2O5 + δ crystallized in tetragonal (space group P4/mmm, 0.6 > δ > 0.45) or orthorhombic (space group Pmmm, 0.6 > δ > 0.45) structures depending on the radius of the lanthanide ion and the oxygen content. The dependences of the unit cell parameters of LnBaCo2O5 + δ on the radius of the lanthanide ion were obtained. The average thermal expansion coefficients at temperatures from 298 to 1373 K in air were determined. The dependence of the chemical component of thermal expansion on the oxygen content was evaluated for LnBaCo2O5 + δ (Ln = Nd, Sm, Gd, Y).

Phase equilibria and crystal structures of solid solutions in the system LaCoO3−δ-SrCoO2.5±δ-SrFeO3−δ-LaFeO3−δ

AbstractThe composition region and structure of La1−xSrxCo1−yFeyO3−δ solid solutions are determined by x-ray powder diffraction using the Rietveld profile analysis method. The solid solutions based on lanthanum cobaltite, LaCoO3−δ, have a rhombohedrally distorted perovskite-like structure (sp. gr. R

The thermodynamic parameters of oxygen nonstoichiometry defects in lanthanum cobaltite doped with acceptor impurities (Sr and Ni)

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Phase Equilibria and Crystal Structure of Complex Oxides in the La–Sr–Co–Ni– System

c), and those based on lanthanum ferrite, LaFeO3−δ, have an orthorhombically distorted structure (sp. gr. Pbnm). The rhombohedral distortion decreases with increasing strontium content, and the solid solutions with x ≥ 0.5 have an ideal cubic structure (sp. gr. Pm3m). The composition dependences of lattice parameters for the La1−xSrxCo1−yFeyO3−δ solid solutions are presented, and the 1100°C isotherm of the LaCoO3−δ-SrCoO2.5±δ-SrFeO3−δ-LaFeO3−δ system in air is constructed.

Фазовые равновесия и термодинамические свойства оксидов в системах на основе редкоземельных, щелочноземельных и 3d-переходных (Mn, Fe, Co) металлов. Краткий обзор. В. А. Черепанов, Л. Я. Гаврилова, Н. Е. Волкова, А. С. Урусова, Т. В. Аксенова, Е. А. Киселев

Phase equilibria in systems La-M-Fe-O (M = Ca or Sr) at 1100° in air were studied. The homogeneity ranges and structures of solid solutions La1 − xMxFeO3 − δ (0 ≤ x ≤ 0.3 for M = Ca and 0 ≤ x ≤ 0.8 for M = Sr), Sr2 − yLayFeO4 − δ (0.8 ≤ y ≤ 1.0), and Sr3 − zLazFe2O7 − δ (0 ≤ z ≤ 0.2) were determined using X-ray powder diffraction. The structural parameters of complex oxides were refined using the full-profile Rietveld technique. Correlations between the unit cell parameters and the compositions of solid solutions were derived. Isobaric/isothermal phase diagrams were constructed for systems La-M-Fe-O (M = Ca or Sr) at 1100°C in air.

Oxygen nonstoichiometry, thermal expansion and high-temperature electrical properties of layered NdBaCo2O5+δ and SmBaCo2O5+δ

AbstractThe oxygen nonstoichiometry δ of lanthanum cobaltite doped with acceptor impurities (Sr and Ni), La1 − xSrxCo0.9Ni0.1O3 − δ (x = 0.1, 0.3), was studied by high-temperature thermogravimetry over the temperature and pressure ranges 723 K ≤ T ≤ 1373 K and 10−3 atm ≤

Oxygen nonstoichiometry and defect structure of perovskite-type oxides in the La–Sr–Co–(Fe, Ni)–O systems

p_{O_2 }