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Vladimir A. Cherepanov - One of the best experts on this subject based on the ideXlab platform.
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Influence of A- and B-site substitutions on crystal structure and oxygen content in air-prepared Ba1−xPrxFe1−yCoyO3−δ perovskites
Journal of Alloys and Compounds, 2021Co-Authors: N. E. Volkova, Vladimir A. Cherepanov, L. Ya. Gavrilova, M.v. Bazueva, D.t. Aisarinova, A.d. Alkhamova, Antoine MaignanAbstract:Abstract The study of 96 samples of various compositions (x, y) in the Ba1−xPrxFe1−yCoyO3−δ system, prepared in air by the Glycerol-Nitrate method, made it possible to establish the compositional boundaries of stability for three types of crystal structure: 1) layered 112-type PrBaCo2−yFeyO5+δ (x = 0.5; 0 ≤ y ≤ 0.6) A-site ordered perovskite, 2) cubic perovskite phase (SG Pm-3m) within 0 ≤ x ≤ 0.6 and for which y depends on the Pr (x) content, and 3) orthorhombic phase (SG Pbnm) within 0.7 ≤ x ≤ 1. The unit cell parameters for the cubic and orthorhombic perovskites were refined by the Le-Bail or Rietveld analysis. The values of oxygen content, determined by the iodometric titration and TGA, are found to increase with Pr and Fe contents. The stability ranges for all three types of complex oxides, together with the multi-phase fields, were outlined for the room temperature conditions in a form of pseudo-phase diagram.
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Thermal Expansion and Conductivity of Sm 0.9 Ca 1.1 Fe 1 - y Co y O 4 - δ Solid Solutions
Russian Journal of Physical Chemistry A, 2020Co-Authors: N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. I. Dyagileva, Vladimir A. CherepanovAbstract:Complex oxides Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are synthesized in air at 1100°С using the Glycerol-Nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the ΔL/L = f(T) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm0.9Ca1.1Fe1 − yCoyO4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm0.9Ca1.1FeO4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.
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Crystal structure, oxygen content and conductivity of Sr1-xGdxCoO3-δ
Solid State Sciences, 2020Co-Authors: A. V. Maklakova, N. E. Volkova, L. Ya. Gavrilova, A. S. Baten’kova, M.a. Vlasova, Vladimir A. CherepanovAbstract:Abstract Solid solutions Sr1–xGdxCoO3–δ (0.0≤x ≤ 0.4) were synthesized through a Glycerol-Nitrate technique. The final anneals were performed at 1100 °C in air for 120 h. All the samples were slowly cooled to room temperature at a rate of about 100 °C/h; alternatively, they were quenched to room temperature at a cooling rate of about 500°/min. The structural parameters of all the samples were refined via Rietveld analysis. All the single-phase oxides slowly cooled to room temperature in air possess a tetragonal 2ap × 2ap × 4ap superstructure (sp. gr. I4/mmm). Only Sr0.9Gd0.1CoO3–δ undergoes a complete order-disorder type phase transition: heating it up to 1100 °C in air transforms it from an ordered tetragonal 2ap × 2ap × 4ap structure to a disordered cubic structure. The super-structural lines for Sr0.9Gd0.1CoO3–δ noticeably decreased at 1100 °C, but are still present in the XRD pattern. The structure of Sr1–xGdxCoO3–δ with x = 0.3 and 0.4 at 1100 °C remains almost unchanged. The oxygen content in Sr1–xGdxCoO3–δ at room temperature ranges from δ = 2.57 in the sample with x = 0.1 to δ = 2.75 in the sample with x = 0.4. The variations in oxygen content, electrical conductivity and the Seebeck coefficient in the Sr1–xGdxCoO3–δ oxides were measured in air versus temperature. The temperature dependences of conductivity for Sr1-xGdxCoO3-δ exhibit maximum (~550 S/cm) at 300–400 °C. The conductivity values depend weakly on the Gd content in Sr1–xGdxCoO3–δ. The temperature dependences of the Seebeck coefficient (S) for all oxides are represented by smooth curves with minimum. The positive S values at room temperature (12–36 μV/K) decreased down to zero or even tiny negative values (– 3 μV/K) as the temperate rose within the range of 300–800 °C and they then rose slightly to 2–14 μV/K at 1100 °C.
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Crystal structure, oxygen nonstoichiometry and properties of novel Ruddlesden-Popper phase Sm 1.8 Sr 1.2 Fe 2 O 7-δ
Materials Letters, 2018Co-Authors: L.v. Khvostova, N. E. Volkova, L. Ya. Gavrilova, Vladimir A. CherepanovAbstract:Abstract Sm1.8Sr1.2Fe2O7-δ Ruddlesden-Popper (RP) phase has been prepared using a Glycerol Nitrate technique at 1100 °C in air. The X-ray diffraction (XRD) pattern for the single phase Sm1.8Sr1.2Fe2O7-δ was refined by the Rietveld method within the tetragonal structure (space group P42/mnm) with unit cell parameters a = 5.489(1) A; c = 20.019 (1) A. The oxygen content in Sm1.8Sr1.2Fe2O7-δ at room temperature determined by TGA and iodometric titration is estimated to be 6.85 ± 0.01. Thermal expansion, electrical conductivity and Seebeck coefficient of Sm1.8Sr1.2Fe2O7-δ were measured within the temperature range of 25–1100 °C in air. Electron holes were considered as the main charge carriers.
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Crystal structure, oxygen nonstoichiometry, thermal expansion and conductivity of (Nd,Sr)(Fe,Co)O3 − δ oxides
Solid State Ionics, 2016Co-Authors: Sh.i. Elkalashy, A.s. Urusova, T.v. Aksenova, Vladimir A. CherepanovAbstract:Abstract A series of samples with overall composition Nd1 − xSrxFe1 − yCoyO3 − δ (x = 0.7, 0.0 ≤ y ≤ 1.0) and (y = 0.3, 0.0 ≤ x ≤ 1.0) were prepared by Glycerol Nitrate technique and characterized by X-ray diffraction, thermogravimetric analysis, iodometric titration and dilatometry. Nd1 − xSrxFe0.7Co0.3O3 − δ with 0.0 ≤ x ≤ 0.5 possesses orthorhombic structure (sp. gr. Pbnm) and reveals O-type → O/-type → O-type structural transition around x = 0.3. The orthorhombic distortion decreases with the increasing strontium substitution and solid solutions Nd1 − xSrxFe0.7Co0.3O3 − δ with 0.7 ≤ x ≤ 1.0 and Nd0.3Sr0.7Fe1 − yCoyO3 − δ with 0.0 ≤ y ≤ 1.0 exhibit the cubic structure (sp. gr. Pm3m). The structural parameters were refined using Rietveld full-profile analysis. The changes of oxygen content in Nd1 − xSrxFe1 − yCoyO3 − δ versus temperature were determined by the thermogravimetric analysis. The gradual substitution of neodymium by strontium or of iron by cobalt leads to the decrease of oxygen content. The thermal expansion measurements of Nd1 − xSrxFe0.7Co0.3O3 − δ (x = 0.3; 0.4; 0.5 and 0.7) were performed and chemical expansion constituents have been separated. The electrical conductivity significantly increased with strontium content in low temperature range. The influence of Sr content diminished in high temperature range.
N. E. Volkova - One of the best experts on this subject based on the ideXlab platform.
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Influence of A- and B-site substitutions on crystal structure and oxygen content in air-prepared Ba1−xPrxFe1−yCoyO3−δ perovskites
Journal of Alloys and Compounds, 2021Co-Authors: N. E. Volkova, Vladimir A. Cherepanov, L. Ya. Gavrilova, M.v. Bazueva, D.t. Aisarinova, A.d. Alkhamova, Antoine MaignanAbstract:Abstract The study of 96 samples of various compositions (x, y) in the Ba1−xPrxFe1−yCoyO3−δ system, prepared in air by the Glycerol-Nitrate method, made it possible to establish the compositional boundaries of stability for three types of crystal structure: 1) layered 112-type PrBaCo2−yFeyO5+δ (x = 0.5; 0 ≤ y ≤ 0.6) A-site ordered perovskite, 2) cubic perovskite phase (SG Pm-3m) within 0 ≤ x ≤ 0.6 and for which y depends on the Pr (x) content, and 3) orthorhombic phase (SG Pbnm) within 0.7 ≤ x ≤ 1. The unit cell parameters for the cubic and orthorhombic perovskites were refined by the Le-Bail or Rietveld analysis. The values of oxygen content, determined by the iodometric titration and TGA, are found to increase with Pr and Fe contents. The stability ranges for all three types of complex oxides, together with the multi-phase fields, were outlined for the room temperature conditions in a form of pseudo-phase diagram.
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Thermal Expansion and Conductivity of Sm 0.9 Ca 1.1 Fe 1 - y Co y O 4 - δ Solid Solutions
Russian Journal of Physical Chemistry A, 2020Co-Authors: N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. I. Dyagileva, Vladimir A. CherepanovAbstract:Complex oxides Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are synthesized in air at 1100°С using the Glycerol-Nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the ΔL/L = f(T) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm0.9Ca1.1Fe1 − yCoyO4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm0.9Ca1.1FeO4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.
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Thermal Expansion and Conductivity of Sm_0.9Ca_1.1Fe_1 – _yCo_yO_4 – δ Solid Solutions
Russian Journal of Physical Chemistry A, 2020Co-Authors: N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. I. Dyagileva, V. A. CherepanovAbstract:Complex oxides Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ ( y = 0, 0.7) are synthesized in air at 1100°С using the Glycerol-Nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ ( y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the Δ L / L = f ( T ) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm_0.9Ca_1.1FeO_4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.
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Crystal structure, oxygen content and conductivity of Sr1-xGdxCoO3-δ
Solid State Sciences, 2020Co-Authors: A. V. Maklakova, N. E. Volkova, L. Ya. Gavrilova, A. S. Baten’kova, M.a. Vlasova, Vladimir A. CherepanovAbstract:Abstract Solid solutions Sr1–xGdxCoO3–δ (0.0≤x ≤ 0.4) were synthesized through a Glycerol-Nitrate technique. The final anneals were performed at 1100 °C in air for 120 h. All the samples were slowly cooled to room temperature at a rate of about 100 °C/h; alternatively, they were quenched to room temperature at a cooling rate of about 500°/min. The structural parameters of all the samples were refined via Rietveld analysis. All the single-phase oxides slowly cooled to room temperature in air possess a tetragonal 2ap × 2ap × 4ap superstructure (sp. gr. I4/mmm). Only Sr0.9Gd0.1CoO3–δ undergoes a complete order-disorder type phase transition: heating it up to 1100 °C in air transforms it from an ordered tetragonal 2ap × 2ap × 4ap structure to a disordered cubic structure. The super-structural lines for Sr0.9Gd0.1CoO3–δ noticeably decreased at 1100 °C, but are still present in the XRD pattern. The structure of Sr1–xGdxCoO3–δ with x = 0.3 and 0.4 at 1100 °C remains almost unchanged. The oxygen content in Sr1–xGdxCoO3–δ at room temperature ranges from δ = 2.57 in the sample with x = 0.1 to δ = 2.75 in the sample with x = 0.4. The variations in oxygen content, electrical conductivity and the Seebeck coefficient in the Sr1–xGdxCoO3–δ oxides were measured in air versus temperature. The temperature dependences of conductivity for Sr1-xGdxCoO3-δ exhibit maximum (~550 S/cm) at 300–400 °C. The conductivity values depend weakly on the Gd content in Sr1–xGdxCoO3–δ. The temperature dependences of the Seebeck coefficient (S) for all oxides are represented by smooth curves with minimum. The positive S values at room temperature (12–36 μV/K) decreased down to zero or even tiny negative values (– 3 μV/K) as the temperate rose within the range of 300–800 °C and they then rose slightly to 2–14 μV/K at 1100 °C.
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Crystal Structure of Solid Solutions in the Sm _ 2 O _ 3 –CaO–MO and Ln _ 2
Inorganic Materials, 2019Co-Authors: L.v. Khvostova, N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. A. Startseva, A. V. Maklakova, A. S. Baten’kova, V. A. CherepanovAbstract:Complex oxides in the Sm_2O_3–CaO–MO and Ln_2O_3–SrO–MO systems (Ln = Sm, Gd; M = Fe, Co) were prepared via the Glycerol-Nitrate technique at 1100°С in air. The homogeneity ranges for the solid solutions were determined as follows: Sr_1 – х Gd_ х CoO_3 – δ (0.1 ≤ х ≤ 0.4); Sr_2 – y Gd_ y CoO_4 – δ (0.8 ≤ y ≤ 1.2); Sr_1 – х Gd_ х FeO_3 – δ (0.05 ≤ х ≤ 0.30 and 0.80 ≤ х ≤ 1.0); Ca_1 – x Sm_ x FeO_3 – δ (0.70 ≤ x ≤ 1.0); Sr_2 – y Sm_ y FeO_4 – δ (0.7 ≤ y ≤ 0.8); Sr_2 – y Gd_ y FeO_4 – δ (0.75 ≤ y ≤ 0.8); Ca_2 – у Sm_ у FeO_4 – δ ( у = 0.90); Sr_3 – z Sm_ z Fe_2O_7 – δ (0 ≤ z ≤ 0.3 and z = 1.8); and Sr_3 – z Gd_ z Fe_2O_7 – δ (0 ≤ z ≤ 0.3 and z = 1.9). For all single phase oxides, the crystal structure was determined and the unit cell parameters, the unit cell volume, and the structural parameters were refined.
L. Ya. Gavrilova - One of the best experts on this subject based on the ideXlab platform.
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Influence of A- and B-site substitutions on crystal structure and oxygen content in air-prepared Ba1−xPrxFe1−yCoyO3−δ perovskites
Journal of Alloys and Compounds, 2021Co-Authors: N. E. Volkova, Vladimir A. Cherepanov, L. Ya. Gavrilova, M.v. Bazueva, D.t. Aisarinova, A.d. Alkhamova, Antoine MaignanAbstract:Abstract The study of 96 samples of various compositions (x, y) in the Ba1−xPrxFe1−yCoyO3−δ system, prepared in air by the Glycerol-Nitrate method, made it possible to establish the compositional boundaries of stability for three types of crystal structure: 1) layered 112-type PrBaCo2−yFeyO5+δ (x = 0.5; 0 ≤ y ≤ 0.6) A-site ordered perovskite, 2) cubic perovskite phase (SG Pm-3m) within 0 ≤ x ≤ 0.6 and for which y depends on the Pr (x) content, and 3) orthorhombic phase (SG Pbnm) within 0.7 ≤ x ≤ 1. The unit cell parameters for the cubic and orthorhombic perovskites were refined by the Le-Bail or Rietveld analysis. The values of oxygen content, determined by the iodometric titration and TGA, are found to increase with Pr and Fe contents. The stability ranges for all three types of complex oxides, together with the multi-phase fields, were outlined for the room temperature conditions in a form of pseudo-phase diagram.
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Thermal Expansion and Conductivity of Sm 0.9 Ca 1.1 Fe 1 - y Co y O 4 - δ Solid Solutions
Russian Journal of Physical Chemistry A, 2020Co-Authors: N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. I. Dyagileva, Vladimir A. CherepanovAbstract:Complex oxides Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are synthesized in air at 1100°С using the Glycerol-Nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the ΔL/L = f(T) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm0.9Ca1.1Fe1 − yCoyO4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm0.9Ca1.1FeO4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.
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Thermal Expansion and Conductivity of Sm_0.9Ca_1.1Fe_1 – _yCo_yO_4 – δ Solid Solutions
Russian Journal of Physical Chemistry A, 2020Co-Authors: N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. I. Dyagileva, V. A. CherepanovAbstract:Complex oxides Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ ( y = 0, 0.7) are synthesized in air at 1100°С using the Glycerol-Nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ ( y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the Δ L / L = f ( T ) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm_0.9Ca_1.1Fe_1 − _ y Co_ y O_4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm_0.9Ca_1.1FeO_4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.
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Crystal structure, oxygen content and conductivity of Sr1-xGdxCoO3-δ
Solid State Sciences, 2020Co-Authors: A. V. Maklakova, N. E. Volkova, L. Ya. Gavrilova, A. S. Baten’kova, M.a. Vlasova, Vladimir A. CherepanovAbstract:Abstract Solid solutions Sr1–xGdxCoO3–δ (0.0≤x ≤ 0.4) were synthesized through a Glycerol-Nitrate technique. The final anneals were performed at 1100 °C in air for 120 h. All the samples were slowly cooled to room temperature at a rate of about 100 °C/h; alternatively, they were quenched to room temperature at a cooling rate of about 500°/min. The structural parameters of all the samples were refined via Rietveld analysis. All the single-phase oxides slowly cooled to room temperature in air possess a tetragonal 2ap × 2ap × 4ap superstructure (sp. gr. I4/mmm). Only Sr0.9Gd0.1CoO3–δ undergoes a complete order-disorder type phase transition: heating it up to 1100 °C in air transforms it from an ordered tetragonal 2ap × 2ap × 4ap structure to a disordered cubic structure. The super-structural lines for Sr0.9Gd0.1CoO3–δ noticeably decreased at 1100 °C, but are still present in the XRD pattern. The structure of Sr1–xGdxCoO3–δ with x = 0.3 and 0.4 at 1100 °C remains almost unchanged. The oxygen content in Sr1–xGdxCoO3–δ at room temperature ranges from δ = 2.57 in the sample with x = 0.1 to δ = 2.75 in the sample with x = 0.4. The variations in oxygen content, electrical conductivity and the Seebeck coefficient in the Sr1–xGdxCoO3–δ oxides were measured in air versus temperature. The temperature dependences of conductivity for Sr1-xGdxCoO3-δ exhibit maximum (~550 S/cm) at 300–400 °C. The conductivity values depend weakly on the Gd content in Sr1–xGdxCoO3–δ. The temperature dependences of the Seebeck coefficient (S) for all oxides are represented by smooth curves with minimum. The positive S values at room temperature (12–36 μV/K) decreased down to zero or even tiny negative values (– 3 μV/K) as the temperate rose within the range of 300–800 °C and they then rose slightly to 2–14 μV/K at 1100 °C.
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Crystal Structure of Solid Solutions in the Sm _ 2 O _ 3 –CaO–MO and Ln _ 2
Inorganic Materials, 2019Co-Authors: L.v. Khvostova, N. E. Volkova, L. Ya. Gavrilova, A. P. Galayda, A. A. Startseva, A. V. Maklakova, A. S. Baten’kova, V. A. CherepanovAbstract:Complex oxides in the Sm_2O_3–CaO–MO and Ln_2O_3–SrO–MO systems (Ln = Sm, Gd; M = Fe, Co) were prepared via the Glycerol-Nitrate technique at 1100°С in air. The homogeneity ranges for the solid solutions were determined as follows: Sr_1 – х Gd_ х CoO_3 – δ (0.1 ≤ х ≤ 0.4); Sr_2 – y Gd_ y CoO_4 – δ (0.8 ≤ y ≤ 1.2); Sr_1 – х Gd_ х FeO_3 – δ (0.05 ≤ х ≤ 0.30 and 0.80 ≤ х ≤ 1.0); Ca_1 – x Sm_ x FeO_3 – δ (0.70 ≤ x ≤ 1.0); Sr_2 – y Sm_ y FeO_4 – δ (0.7 ≤ y ≤ 0.8); Sr_2 – y Gd_ y FeO_4 – δ (0.75 ≤ y ≤ 0.8); Ca_2 – у Sm_ у FeO_4 – δ ( у = 0.90); Sr_3 – z Sm_ z Fe_2O_7 – δ (0 ≤ z ≤ 0.3 and z = 1.8); and Sr_3 – z Gd_ z Fe_2O_7 – δ (0 ≤ z ≤ 0.3 and z = 1.9). For all single phase oxides, the crystal structure was determined and the unit cell parameters, the unit cell volume, and the structural parameters were refined.
Soon Dong Lee - One of the best experts on this subject based on the ideXlab platform.
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Dactylosporangium darangshiense sp. nov., isolated from rock soil.
International Journal of Systematic and Evolutionary Microbiology, 2010Co-Authors: Seong Hae Seo, Soon Dong LeeAbstract:A novel actinomycete was isolated from soil of a rock surface collected from the peak of Darangshi Oreum (Small Mountain) in Jeju, Republic of Korea. Phylogenetic analyses based on 16S rRNA gene sequences demonstrated that strain DLS-44T belonged to the genus Dactylosporangium, with the type strains of Dactylosporangium roseum (99.1 % sequence similarity) and Dactylosporangium fulvum (99.0 %) as the nearest phylogenetic relatives. Substrate mycelium was abundant, irregularly branched, twisted and vivid orange–yellow in colour. Aerial mycelium was not produced on most media tested. Finger-shaped sporangia and globose bodies were formed directly from the vegetative mycelium. The combination of morphological and chemotaxonomic characteristics supported assignment of the actinomycete to the genus Dactylosporangium. Strain DLS-44T could be distinguished clearly from all type strains of the genus based on its physiological properties (utilization of methyl α-d-mannoside and Glycerol, Nitrate reduction and growth at 20 °C and pH 9.1) and some chemotaxonomic characteristics (absence of unsaturated fatty acids). DNA–DNA relatedness values between strain DLS-44T and its closest phylogenetic relatives were 12.2–14.8 % with D. roseum DSM 43916T and 2.5–3.6 % with D. fulvum IMSNU 22055T. On the basis of phenotypic, phylogenetic and DNA–DNA hybridization data, strain DLS-44T represents a novel species of the genus Dactylosporangium, for which the name Dactylosporangium darangshiense sp. nov. is proposed. The type strain is strain DLS-44T (=KCTC 19560T =DSM 45260T).
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Dactylosporangium darangshiense sp. nov., isolated from rock soil.
International journal of systematic and evolutionary microbiology, 2009Co-Authors: Seong Hae Seo, Soon Dong LeeAbstract:A novel actinomycete was isolated from soil of a rock surface collected from the peak of Darangshi Oreum (Small Mountain) in Jeju, Republic of Korea. Phylogenetic analyses based on 16S rRNA gene sequences demonstrated that strain DLS-44(T) belonged to the genus Dactylosporangium, with the type strains of Dactylosporangium roseum (99.1 % sequence similarity) and Dactylosporangium fulvum (99.0 %) as the nearest phylogenetic relatives. Substrate mycelium was abundant, irregularly branched, twisted and vivid orange-yellow in colour. Aerial mycelium was not produced on most media tested. Finger-shaped sporangia and globose bodies were formed directly from the vegetative mycelium. The combination of morphological and chemotaxonomic characteristics supported assignment of the actinomycete to the genus Dactylosporangium. Strain DLS-44(T) could be distinguished clearly from all type strains of the genus based on its physiological properties (utilization of methyl alpha-d-mannoside and Glycerol, Nitrate reduction and growth at 20 degrees C and pH 9.1) and some chemotaxonomic characteristics (absence of unsaturated fatty acids). DNA-DNA relatedness values between strain DLS-44(T) and its closest phylogenetic relatives were 12.2-14.8 % with D. roseum DSM 43916(T) and 2.5-3.6 % with D. fulvum IMSNU 22055(T). On the basis of phenotypic, phylogenetic and DNA-DNA hybridization data, strain DLS-44(T) represents a novel species of the genus Dactylosporangium, for which the name Dactylosporangium darangshiense sp. nov. is proposed. The type strain is strain DLS-44(T) (=KCTC 19560(T) =DSM 45260(T)).
A.s. Urusova - One of the best experts on this subject based on the ideXlab platform.
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Crystal Structure of the New Ordered Phases Based on Y_2Ba_3Fe_3Co_2O_13 + δ
Inorganic Materials, 2020Co-Authors: A.s. Urusova, A. V. Bryuzgina, M. Yu. Mychinko, A. V. Dyakova, V. A. CherepanovAbstract:New phases with an ordered structure of the composition Y_2Ba_3Fe_5_ – y Co_ y O_13 + δ (1.7 ≤ y ≤ 2.1) were obtained via the Glycerol-Nitrate technique. The regions of existence of two types of structures were determined by transmission electron microscopy: for 1.7 ≤ y ≤ 1.8, the structure described as a _ p × a _ p × 3 a _ p , and for 1.9 ≤ y ≤ 2.1, it is a _ p × a _ p × 5 a _ p , where a _ p is the parameter of the ideal cubic perovskite. The unit cell parameters for all single-phase samples were refined by the Le Bail method. The phase composition of oxides outside the homogeneity ranges is determined.
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Crystal structure, oxygen nonstoichiometry, thermal expansion and conductivity of (Nd,Sr)(Fe,Co)O3 − δ oxides
Solid State Ionics, 2016Co-Authors: Sh.i. Elkalashy, A.s. Urusova, T.v. Aksenova, Vladimir A. CherepanovAbstract:Abstract A series of samples with overall composition Nd1 − xSrxFe1 − yCoyO3 − δ (x = 0.7, 0.0 ≤ y ≤ 1.0) and (y = 0.3, 0.0 ≤ x ≤ 1.0) were prepared by Glycerol Nitrate technique and characterized by X-ray diffraction, thermogravimetric analysis, iodometric titration and dilatometry. Nd1 − xSrxFe0.7Co0.3O3 − δ with 0.0 ≤ x ≤ 0.5 possesses orthorhombic structure (sp. gr. Pbnm) and reveals O-type → O/-type → O-type structural transition around x = 0.3. The orthorhombic distortion decreases with the increasing strontium substitution and solid solutions Nd1 − xSrxFe0.7Co0.3O3 − δ with 0.7 ≤ x ≤ 1.0 and Nd0.3Sr0.7Fe1 − yCoyO3 − δ with 0.0 ≤ y ≤ 1.0 exhibit the cubic structure (sp. gr. Pm3m). The structural parameters were refined using Rietveld full-profile analysis. The changes of oxygen content in Nd1 − xSrxFe1 − yCoyO3 − δ versus temperature were determined by the thermogravimetric analysis. The gradual substitution of neodymium by strontium or of iron by cobalt leads to the decrease of oxygen content. The thermal expansion measurements of Nd1 − xSrxFe0.7Co0.3O3 − δ (x = 0.3; 0.4; 0.5 and 0.7) were performed and chemical expansion constituents have been separated. The electrical conductivity significantly increased with strontium content in low temperature range. The influence of Sr content diminished in high temperature range.
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Crystal structure and oxygen nonstoichiometry of oxides in the Ba-Me-Me’-Y-O (Me, Me’=Co, Fe) system
Chimica Techno Acta, 2015Co-Authors: A.s. Urusova, A. V. Bryuzgina, T.v. Aksenova, Vladimir A. CherepanovAbstract:Polycrystalline BaМe 1-x Y x O 3-δ (Me=Co, Fe) samples were synthesized by a conventional route and Glycerol–Nitrate technique. According XRD patterns of single phase solid solutions BaCo1-xYxO3-δ (0.1≤x≤0.4) and BaFe 0.9-y Y 0.1 Co y O 3-δ (0.05≤y≤0.15) were indexed using Pm3m space group. The unit cell parameters were refined using Rietveld full-profile analysis. Oxygen nonstoichiometry of these solid solutions was measured by means of thermogravimetric technique within the temperature range 298–1273 K in air.
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Tuning oxygen content and distribution by substitution at Co site in 112 YBaCo2O5+δ: impact on transport and thermal expansion properties
J. Mater. Chem. A, 2014Co-Authors: A.s. Urusova, T.v. Aksenova, Vladimir A. Cherepanov, L. Ya. Gavrilova, Oleg I. Lebedev, Vincent Caignaert, B. RaveauAbstract:Polycrystalline “112” ordered oxygen deficient double perovskites YBaCo2−xMexO5+δ (Me = Fe, Cu, Ni) were synthesized by a Glycerol-Nitrate route with 0.0 ≤ x ≤ 0.7 for Me = Fe, 0.0 ≤ x ≤ 0.6 for Me = Cu and x = 0.1 for Me = Ni. The combined X-ray diffraction, electron microscopy and thermo-gravimetric studies show that all these oxides exhibit the ap × ap × 2ap tetragonal structure (S.G. P4/mmm); moreover, the oxygen content increases continuously with x in the iron-substituted oxide YBaCo2−xFexO5+δ, whereas the opposite is observed for the copper phase YBaCo2−xCuxO5+δ. This difference, which is due to the more electropositive character of Fe3+ compared to Cu2+, is hindered in the Ni2+ case due to its inability to accommodate the pyramidal coordination. The changes of the conductivity of these compounds versus temperature are closely related to their oxygen loss, in agreement with a defect structure model suggested earlier. Thermal expansion measurements prove the absence of phase transition in all oxides within the temperature range studied. The chemical compatibility of YBaCo1.4Fe0.6O5+δ with the electrolyte Ce0.8Sm0.2O2−δ is also demonstrated.