Crystal growth, structure, and dielectric properties of layered cobaltates La2−xSrxCoO4 (x=0.4, 0.5, and 0.6) single crystal

Dong, Song‐Tao; Sun, Ningning; Zhang, B.B.; Zhang, F.; Yao, Shu‐Hua; Zhou, Juying; Zhang, S.T.; Gu, Zheng‐Bin; Chen, Y.B.; Chen, Y.F.

doi:10.1016/j.materresbull.2014.09.065

Cited by 9 publications

(3 citation statements)

References 24 publications

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“…Previous reports also suggest that the ca . 350 and 600 cm –1 peaks are symmetry forbidden modes that arise due to defects lowering local symmetry. − Related phases such as Sr 2 CoO 4 , LaCoO 3 , and La 2– x Sr x CoO 4 show a peak near 700 cm –1 in Raman spectra, but its assignment remains uncertain. − Raman spectra therefore reveal a structural complexity that is not captured in the XRD results.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Whittingham,

Boke,

Smith

2024

ACS Appl. Mater. Interfaces

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Compositional tuning of layered perovskite oxides provides a means of systematically studying how local distortions affect fundamental aspects of electrochemical reaction pathways. Structural analysis of a family of samples La 1.2 Sr 0.8 Ni 1−y Co y O 4 shows that Ni-rich compositions have an expanded crystalline c axis, which is anisotropically compressed by systematic Co incorporation. Raman spectra reveal the strong growth of a symmetry forbidden mode, which suggests that Co acts through localized distortions. Crystallographic and spectroscopic parameters describing this structural distortion correlate to the measured Tafel slopes for the oxygen reduction reaction for all Ni-containing samples, which is attributed to the distortion of potential energy surfaces by the Jahn−Teller expansion of d 7 Ni(III) cations. Incorporation of Co not only minimizes the distortion but alters the apparent selectivity of the oxygen reduction reaction away from H 2 O 2 and toward H 2 O. Rotating ring-disk electrochemical measurements, however, indicate that the apparent change in selectivity is due to activation of a first-order chemical disproportionation of H 2 O 2 that is activated by Co in the lattice. These outcomes will support efforts to design electrocatalysts and reactors for the electrochemical synthesis of H 2 O 2 .

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Section: Resultsmentioning

confidence: 99%

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Whittingham,

Boke,

Smith

2024

ACS Appl. Mater. Interfaces

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“…Containing an equal amount of Co 2+ /Co 3+ , it is the analogous to half-hole doped La1.5Sr0.5CoO4, showing a loosely correlated checkerboard charge ordering of Co 3+ and Co 2+ ions. 16,[18][19][20][21] To this, long-range oxygen ordering may go along with complex electronic ordering, as observed for the spin structure in the homologous Nd2NiO4.10 10 , yielding to interesting correlations. 14,22 Ordering phenomena and their interplay are generally difficult to explore related to weak satellite intensities and the availability of single phases.…”

Section: Introductionmentioning

confidence: 89%

“…Among the oxygen-doped phases, La 2 CoO 4.25 showing the highest achievable oxygen stoichiometry is particularly interesting. Containing an equal amount of Co 2+ /Co 3+ , it is analogous to half-hole doped La 1.5 Sr 0.5 CoO 4 , showing a loosely correlated checkerboard charge ordering of Co 3+ and Co 2+ ions. ,− To this, long-range oxygen ordering may go along with complex electronic ordering, as observed for the spin structure in homologous Nd 2 NiO 4.10 , yielding interesting correlations. , …”

Section: Introductionmentioning

confidence: 99%

Growth and Oxygen Stoichiometry Control of High-Quality La₂CoO_4+δ Single Crystals (δ = 0.25)

Barros

Ceretti

Schmidt³

et al. 2022

Crystal Growth & Design

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La2CoO4+ is a strongly correlated oxide with exciting physical and electronic properties originating from the subtle interplay of lattice, orbital, charge, and spin degrees of freedom. In particular, the oxygen rich La2CoO4.25 is a key compound for studying oxygen and electronic ordering phenomena and their correlation. Single crystal growth of these phases has been plagued by difficulties related to its incongruent melting. In this work, we report on the 2 growth and characterization of high quality, centimeter sized La2CoO4.25 single crystals, suitable for neutron scattering experiments. La2CoO4+ single crystals were grown by the Travelling Solvent Floating Zone (TSFZ) without the addition of a solvent but continuously stabilizing the growth conditions. Post synthesis annealing at 500°C in oxygen flux yielded phase pure La2CoO4.25, which was further characterized by single crystal neutron and X-ray diffraction, as well as by electron microscopy (SEM/EDS), revealing its quality in terms of composition, homogeneity and crystalline quality. For La2CoO4.25 a complex structure with a 2D modulation vector related to oxygen ordering was revealed by single crystal X-ray and neutron powder diffraction studies. In addition, magnetic measurements coupled with preliminary single crystal elastic neutron scattering experiments exhibit antiferromagnetic ordering with a Néel temperature of TN = 36 K with a complex magnetic structure involving a doubling of all orthorhombic axes.

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Structural, transport, thermal, and electrochemical properties of (La1−xSrx)2CoO4±δ cathode in solid-oxide fuel cells

Zhao

et al. 2021

J Appl Electrochem

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Crystal growth, structure, and dielectric properties of layered cobaltates La2−xSrxCoO4 (x=0.4, 0.5, and 0.6) single crystal

Cited by 9 publications

References 24 publications

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Growth and Oxygen Stoichiometry Control of High-Quality La₂CoO_4+δ Single Crystals (δ = 0.25)

Structural, transport, thermal, and electrochemical properties of (La1−xSrx)2CoO4±δ cathode in solid-oxide fuel cells

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Crystal growth, structure, and dielectric properties of layered cobaltates La2−xSrxCoO4 (x=0.4, 0.5, and 0.6) single crystal

Cited by 9 publications

References 24 publications

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

Growth and Oxygen Stoichiometry Control of High-Quality La2CoO4+δ Single Crystals (δ = 0.25)

Structural, transport, thermal, and electrochemical properties of (La1−xSrx)2CoO4±δ cathode in solid-oxide fuel cells

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Growth and Oxygen Stoichiometry Control of High-Quality La₂CoO_4+δ Single Crystals (δ = 0.25)