Exceptional Layered Ordering of Cobalt and Iron in Perovskites

Lebedev, Oleg I.; Turner, Stuart; Caignaert, V.; Черепанов, В.А.; Raveau, B.

doi:10.1021/acs.chemmater.6b01046

Cited by 9 publications

(4 citation statements)

References 59 publications

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“…According to the above-mentioned CT and electrical conductivity data (see Figures and ), no noticeable discontinuities in a particular property can be observed for PBSCF with such an oxygen content. Therefore, the uncovered reflections can be ascribed to some sort of ordering that is typical for layered cobaltites. − Accounting for the closeness of the determined oxygen content to 0.11, it may be supposed the considered PBSCF sample has a 3 × 3 × 1 superstructural ordering with P 4/ mmm S.G. similar to that found earlier for YBaCo 2 O 6−δ . This ordering suggests the predetermined location of one oxygen atom in the O3 position surrounded by eight vacant sites; their schematical depiction has been presented in Figure (b).…”

Section: Results and Discussionsupporting

confidence: 62%

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Politov,

Shishkin,

Suntsov

2023

J. Phys. Chem. C

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In this study, PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 6−δ (PBSCF) oxide with a layered double perovskite structure was successfully synthesized and characterized using the combination of X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) methods. Oxygen content and electrical conductivity of PBSCF were measured at elevated temperatures and variable oxygen partial pressures. The corresponding experimental data were successfully analyzed using earlier proposed defect formation and transport models; the obtained results were additionally supported by magnetic experiments. The studied oxide was found to possess weak superstructural ordering at low δ values. Additionally, a noticeable chemical expansion anomaly was uncovered for PBSCF. Currently existing models of chemical deformation in nonstoichiometric oxides were shown to be inefficient for interpreting the data obtained, although a reasonable explanation was proposed on the basis of a more fundamental approach. Nevertheless, the peculiarity revealed was shown to be crucial for providing enhanced ionic mobility for oxygen anions in the PBSCF lattice, thus giving a reasonable explanation to the known superiority of PBSCF as a positrode material when compared to other layered cobaltites.

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Section: Results and Discussionsupporting

confidence: 62%

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Politov,

Shishkin,

Suntsov

2023

J. Phys. Chem. C

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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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“…This in turn causes a transition from CoO 6 octahedron to CoO 5 pyramid. Meanwhile, the oxygen atoms just above and below Y go towards Y, forming zigzag-shaped Co-O-Co rows, as marked by the corrugated line [23]. These are typical features of the A-siteordered oxygen-deficient double perovskite.…”

Section: Structure Featuresmentioning

confidence: 99%

Perpendicular magnetic anisotropy induced by La_2/3Sr_1/3MnO₃–YBaCo₂O_5+δ interlayer coupling

Han¹,

Chen²,

Wang³

et al. 2021

J. Phys. D: Appl. Phys.

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Heterostructure with a symmetry-mismatched interface provides a promising playground for the exploration of emergent phenomena. Herein, we report a systematic investigation on La2/3Sr1/3MnO3/YBaCo2O5+δ (LSMO/YBCO) grown on SrTiO3, a heterostructure formed by perovskite oxides of different symmetry. A high-resolution lattice image shows the formation of high-quality perovskite LSMO and A-site cation-ordered oxygen-deficient double perovskite YBCO, without any signatures of atomic reconfiguration at the interface. Surprisingly, the YBCO-buffered LSMO exhibits perpendicular magnetic anisotropy (PMA), though bare LSMO film is in-plane anisotropic. The PMA is robust, appearing even when the thickness of YBCO is only one unit cell. The typical anisotropy constant is ∼4 × 106 erg cm−3. X-ray absorption spectroscopy analysis reveals a preferential occupation of the d 3 z 2 − r 2 orbital compared with d x 2 − y 2 , which is confirmed by density functional theory calculations. This orbital reconstruction accounts for the PMA. The formation of a covalent bond between Mn and Co caged by different oxygen polyhedrons, an octahedron and a square pyramid, respectively, stabilizes the orbital reconstruction, resulting in anomalous spin orientation.

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Exceptional Layered Ordering of Cobalt and Iron in Perovskites

Cited by 9 publications

References 59 publications

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Deep Eutectic Solvent Synthesis of Perovskite Electrocatalysts for Water Oxidation

Perpendicular magnetic anisotropy induced by La_2/3Sr_1/3MnO₃–YBaCo₂O_5+δ interlayer coupling

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Exceptional Layered Ordering of Cobalt and Iron in Perovskites

Cited by 9 publications

References 59 publications

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa0.5Sr0.5Co1.5Fe0.5O6−δ Positrode

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa0.5Sr0.5Co1.5Fe0.5O6−δ Positrode

Deep Eutectic Solvent Synthesis of Perovskite Electrocatalysts for Water Oxidation

Perpendicular magnetic anisotropy induced by La2/3Sr1/3MnO3–YBaCo2O5+δ interlayer coupling

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Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Correlating High-Temperature Defect and Magnetic Structures with Anomalous Chemical Expansion in an Outstanding PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6−δ Positrode

Perpendicular magnetic anisotropy induced by La_2/3Sr_1/3MnO₃–YBaCo₂O_5+δ interlayer coupling