Phase equilibria, crystal structure and properties of complex oxides in the Nd 2 O 3 –SrO–CoO system

Аксенова, Т. В.; Ефимова, Т. Г.; Lebedev, Oleg I.; Elkalashy, Sh.I.; Urusova, A.S.; Черепанов, В.А.

doi:10.1016/j.jssc.2017.02.002

Cited by 13 publications

(5 citation statements)

References 37 publications

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“…Samples with the overall composition corresponding to the Sm 2– z Sr z O 3– z /2 formula, with z = 0.05, 0.1, and 0.15, were annealed at 1100 °C in air for 120 h and quenched to room temperature. XRD examination showed that, in contrast to the Nd‐containing system, where the Nd 2– z Sr z O 3– z /2 solid solution formed within the range 0 ≤ z ≤ 0.15, no signs of solid‐solution formation was detected in the Sm 2 O 3 –SrO system. This fact also emphasizes the distinct difference in the phase formation of the Nd and Sm oxides, as it was similarly shown for the perovskite solid solutions, in spite of the relatively small difference in their ionic radii.…”

Section: Resultsmentioning

confidence: 87%

“…Although the difference between the ionic radii of Nd 3+ ( r = 1.27 Å) and Sm 3+ ( r = 1.24 Å) is not so big, the increasing difference of the Ln radii, compared with that for Sr 2+ , is critical for the formation of the Sr 1– x Ln x CoO 3– δ solid solutions. It becomes obvious, if one compares the formation of the orthorhombic Nd‐rich Sr 1– x Nd x CoO 3– δ solid solution (0.5 ≤ x ≤ 1), in contrast with the double‐phase region for the Sm‐containing system and the formation of different superstructure types inside the Ln‐poor region: a p × a p × 2 a p for Nd, or 2 a p × 2 a p × 4 a p for Sm . Such a significant difference in the phase relationship that appears between the Nd‐ and Sm‐containing systems in the row of Ln 2 O 3 –SrO–CoO systems, is similar to that appearing in the row of Ln 2 O 3 –BaO–CoO systems.…”

Section: Resultsmentioning

confidence: 99%

“…Earlier, it was found that SrO can be partially dissolved in the rare‐earth oxides; for example, in La 2 O 3 , or in Nd 2 O 3 . Since no systematic study of the phase equilibria in the Sm 2 O 3 –SrO system at 1100 °C, in air, had been previously performed, special attention to the possibility of SrO solubility in Sm 2 O 3 was undertaken in this work.…”

Section: Resultsmentioning

confidence: 99%

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Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

et al. 2017

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The phase equilibria in the 1 / 2 Sm 2 O 3 -SrO-CoO system were systematically studied at 1100°C in air. Single-phase Sr 1-x Sm x CoO 3-δ and Sr 2-y Sm y CoO 4+δ solid solutions were obtained within the ranges of 0.05 ≤ x ≤ 0.50 and 0.9 ≤ y ≤ 1.3, respectively. XRD patterns of the single-phase samples were refined by the Rietveld method within the tetragonal structure (space group I4/mmm). Gradual substitution of strontium by samarium leads to a decrease of the unit-cell parameters and the unit-cell volume that can be explained by the size factor.

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Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

et al. 2017

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“…In order to check the possible formation of a superstructure due to the ordering of oxygen vacancies and/or ordering of metal ions in A‐sublattice, which use to appear in the related Sr‐rich perovskite oxides, electron diffraction measurements were performed for the Sr 0.8 Y 0.2 FeO 3−δ sample. Figure demonstrates the ideal perovskite cubic cell without any additional reflections.…”

Section: Resultsmentioning

confidence: 99%

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

et al. 2018

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Phase equilibria in the 1/2Y 2 O 3 -SrO-1/2Fe 2 O 3 system were systematically studied at 1373 K in air. The homogeneity ranges and crystal structure of the solid solutions Sr 1−x Y x FeO 3−δ with 0.875 ≤ x ≤ 1 (sp. gr. Pnma) and 0.05 ≤ x ≤ 0.25 (sp. gr. Pm3 m) and Sr 3−z Y z Fe 2 O 7−δ with 0 ≤ z ≤ 0.25 (sp. gr. I4/mmm) were determined by X-ray diffraction analysis of quenched samples. The structural parameters of the single-phase oxides were refined by the Rietveld profile method. The isothermal-isobaric phase diagram for the 1/2Y 2 O 3 -SrO-1/2Fe 2 O 3 system at 1373 K in air is presented. The changes of oxygen content in the solid solutions Sr 1−x Y x FeO 3−δ (0.05 ≤ x ≤ 0.25) and Sr 3−z Y z Fe 2 O 7−δ with 0 ≤ z ≤ 0.25 vs temperature in air were determined by the thermogravimetric analysis. Oxygen content was also calculated from the iodometric titration results. The gradual substitution of strontium by yttrium in Sr 1−x Y x FeO 3−δ (0.05 ≤ x ≤ 0.25) leads to a decrease in the oxygen content and the mean oxidation state of iron. The average thermal expansion coefficients for Sr 1−x Y x FeO 3−δ (0.875 ≤ x ≤ 1 and 0.05 ≤ x ≤ 0.25) and Sr 3−z Y z Fe 2 O 7−δ (0 ≤ z ≤ 0.25) were calculated within the temperature range 298-1373 K in air. K E Y W O R D S crystal structure, oxygen content, phase diagram, solid solution, thermal expansion, total electric conductivity, X-ray diffraction

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“…The measurement of the interlayer distances revealed the expansion of the La–La distance from a typical 0.38 to 0.46 nm in the V O stripe. Both the appearance of dark contrast Co–O layers and the increase in La–La distances can be attributed to V O layers, as has been previously observed in perovskite structures. − Such layers of V O change Co coordination from CoO 6 octahedral to CoO 5 square pyramidal. The formation of V O in the DES-synthesized perovskites is consistent with our previous studies, , where we used a DES route to prepare mixed-valent ternary Zn and Cu vanadates ( M 2 V 2 O 7– m and M V 2 O 6– n , M = Zn or Cu) and found annealing the reaction mixture to intrinsically introduce V O .…”

Section: Resultsmentioning

confidence: 53%

Deep Eutectic Solvent Synthesis of Perovskite Electrocatalysts for Water Oxidation

Hong

Díez

Adeyemi

et al. 2022

ACS Appl. Mater. Interfaces

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Oxide perovskites have attracted great interest as materials for energy conversion due to their stability and structural tunability. La-based perovskites of 3d-transition metals have demonstrated excellent activities as electrocatalysts in water oxidation. Herein, we report the synthesis route to La-based perovskites using an environmentally friendly deep eutectic solvent (DES) consisting of choline chloride and malonic acid. The DES route affords phase-pure crystalline materials on a gram scale and results in perovskites with high electrocatalytic activity for oxygen evolution reaction. A convenient, fast, and scalable synthesis proceeds via assisted metathesis at a lower temperature as compared to traditional solid-state methods. Among LaCoO3, LaMn0.5Ni0.5O3, and LaMnO3 perovskites prepared via the DES route, LaCoO3 was established to be the best-performing electrocatalyst for water oxidation in alkaline medium at 0.25 mg cm–2 mass loading. LaCoO3 exhibits current densities of 10, 50, and 100 mA cm–2 at respective overpotentials of approximately 390, 430, and 470 mV, respectively, and features a Tafel slope of 55.8 mV dec–1. The high activity of LaCoO3 as compared to the other prepared perovskites is attributed to the high concentration of oxygen vacancies in the LaCoO3 lattice, as observed by high-resolution transmission electron microscopy. An intrinsically high concentration of O vacancies in the LaCoO3 synthesized via the DES route is ascribed to the reducing atmosphere attained upon thermal decomposition of the DES components. These findings will contribute to the preparation of highly active perovskites for various energy applications.

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Phase equilibria, crystal structure and properties of complex oxides in the Nd 2 O 3 –SrO–CoO system

Cited by 13 publications

References 37 publications

Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system

Deep Eutectic Solvent Synthesis of Perovskite Electrocatalysts for Water Oxidation

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Phase equilibria, crystal structure and properties of complex oxides in the Nd 2 O 3 –SrO–CoO system

Cited by 13 publications

References 37 publications

Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm2O3–SrO–CoO System

Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm2O3–SrO–CoO System

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y2O3–SrO–1/2Fe2O3 system

Deep Eutectic Solvent Synthesis of Perovskite Electrocatalysts for Water Oxidation

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Product

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Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

Phase Equilibria, Crystal Structure, and Properties of Intermediate Oxides in the Sm₂O₃–SrO–CoO System

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y₂O₃–SrO–1/2Fe₂O₃ system