E. A. Filonova

Phase equilibria in the La-Ba-Co-O system

Phase equilibria in the La-Ba-Co-O system were studied at 1,100 C in air. The existence of oxide phases LaCoO{sub 3}, BaCoO{sub 3{minus}y}, Ba{sub 2}CoO{sub 4}, and La{sub 2}BaO{sub 4} in quasibinary systems in air at 1,100 C was found, in agreement with previous data. Two types of solid solutions were found in the quasiternary system: La{sub 1{minus}x}Ba{sub x}CoO{sub 3{minus}{delta}} and (La{sub 1{minus}z}Ba{sub z}){sub x}CoO{sub 4}. The homogeneity range of La{sub 1{minus}x}Ba{sub x}CoO{sub 3{minus}{delta}} was found to be 0 {le} x {le} 0.8. As the content of alkali-earth metal (x) increased, a rhombohedral distortion of La{sub 1{minus}x}Ba{sub x}CoO{sub 3{minus}{delta}} decreased; La{sub 0.55}Ba{sub 0.45}CoO{sub 3{minus}{delta}} had an ideal cubic structure. The composition of single phase samples of (La{sub 1{minus}z}Ba{sub z}){sub 2}CoO{sub 4} composition was obtained for z = 0.300, 0.325, 0.350, and 0.375. These samples had the tetragonal K{sub 2}NiF{sub 4}-type structure.

Phase equilibria in the system LaMnO3+δ-SrMnO3-LaFeO3-SrFeO3-d

We have revealed the formation of a continuous series of orthorhombic LaMn1 − yFeyO3 solid solutions (0<y<1); La1 − xSrxFeO3 solid solutions in the composition range 0 < x ≤ 0.8, with an orthorhombic structure at 0 < x ≤ 0.6 and a cubic structure at 0.6 < x ≤ 0.8; and a tetragonal SrMn1 − yFeyO3 phase in the range 0.6 ≤ y ≤ 1. The composition stability limits of the perovskite phase La1 − xSrxMn1 − yFeyO3 have been determined, and the 1100°C isotherm of the La2O3-SrO-Mn3O4-Fe2O3 system in air has been constructed.

Phase equilibria in the LaCoO3–LaMnO3–SrCoO2.5–SrMnO3 system

The phase equilibria in the LaCoO{sub 3}-LaMnO{sub 3}-SrCoO{sub 2.5}-SrMnO{sub 3} system were studied at 1,100 C in air. The existence of SrCo{sub 1{minus}y}Mn{sub y}O{sub 3{minus}{delta}} with the homogeneity range 0.45 {le} y {le} 0.55 was confirmed. The homogeneity range of solid solutions of general formula La{sub 1{minus}x}Sr{sub x}Co{sup 1{minus}y}O{sub 3{+-}{delta}} with orthorhombic, rhombohedral, and cubic structure has been determined. Based on the experimental results and earlier data, the pseudoquaternary phase diagram was constructed.

The conditions of formation and physicochemical properties of Nd1 − xBaxMn1 − yFeyO3 phases

The homogeneity regions of Nd1 − xBaxMnO3 (0.0 ≤ x ≤ 0.25) and NdMn1 − yFeyO3 (0.0 ≤ y ≤ 1.0) orthorhombic solid solutions in air at 1373 K were determined. The region of the existence of Nd1 − xBaxMn1 − yFeyO3 orthorhombic solid solutions in air at 1373 K was studied. A fragment of the phase diagram of the NdMnO3-BaMnO3-BaFeO2.5-NdFeO3 quasi-quaternary complex oxide system in air at 1373 K was suggested. The mechanothermal properties of Nd0.75Ba0.25MnO3, Nd0.8Ba0.2Mn0.9Fe0.1O3, Nd0.8Ba0.2Mn0.7Fe0.3O3, and Nd0.8Ba0.2Mn0.5Fe0.5O3 doped neodymium manganates were studied.

Phase equilibria in the system LaMnO3-SrMnO3-SrCrO4-LaCrO3

A continuous solid solution LaMn1−yCryO3 with an orthorhombic structure is found to exist in the range of 0.0 ≤ y ≤ 1.0. An orthorhombic solid solution La1−xSrxCrO3 exists in the range of 0.0 ≤ x ≤ 0.1. The stability boundaries are determined for the perovskite phase La1−xSrxMn1−yCryO3. An isobaric-isothermal section LaMnO3-SrMnO3-SrCrO4-LaCrO3 of the system La2O3-SrO-Mn3O4-Cr2O3 in air at 1100°C is designed.

Thermal expansion and electrical conductivity of La0.7Sr0.3Mn1 − yCryO3

The thermal expansion and electrical conductivity of La0.7Sr0.3Mn1 − yCryO3 (y = 0, 0.1, 0.3, 0.4) solid solutions have been studied at temperatures from 300 to 1270 K and oxygen partial pressures from 10−9 to 2.1 × 104 Pa. The solid solutions crystallize in rhombohedral symmetry (sp. gr. R3c). The lattice parameters of La0.7Sr0.3Mn1 − yCryO3 decrease with increasing chromium content. Doping with chromium reduces the conductivity of lanthanum manganite, without changing the conductivity type. The charge transport in the solid solutions is due to small-polaron hopping. Disproportionation of the 3d transition metals is shown to play a key role in determining the electrical properties of the solid solutions. Partial chromium substitution for manganese reduces the thermal expansion coefficient of the manganite, improving its compatibility with yttria-stabilized zirconia, which is of practical importance.

Structural, thermal, and electrical properties of La0.7Sr0.3Mn1−yFeyO3±δ

AbstractThe crystal structure, thermal expansion, and electrical conductivity of the doped manganites La0.7Sr0.3Mn1−yFeyO3±δ (y = 0, 0.1, 0.2, 0.3) are studied. The manganites are shown to crystallize in rhombohedral symmetry (sp. gr.

Synthesis, structure, and thermal expansion of Nd1 − x BaxMn1 − y CryO3 solid solutions

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