Thermodynamic Modeling of the La-Co-O System

Zhang, Weiwei; Povoden-Karadeniz, Erwin; Xu, Huixia; Chen, Ming

doi:10.1007/s11669-019-00717-z

Cited by 8 publications

(4 citation statements)

References 51 publications

(64 reference statements)

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“…According to the reported La/Co/O phase diagram (Figure ), La 2 CoO 4 (LCO) melts incongruently at around 2050 K with a eutectic temperature of 1885 K . Therefore, LCO single crystals can only be grown within this narrow temperature range, using a melt with a Co:La molar ratio approximately between 1.22:1 and 4:1, corresponding to the B–C line in the phase diagram in Figure .…”

Section: Resultssupporting

confidence: 74%

“…According to the reported La/Co/O phase diagram (Figure 2), La2CoO4 melts incongruently at around 2050 K with an eutectic temperature of 1885K. 30 Therefore, LCO single crystals can only be grown within this narrow temperature range, using a melt with a Co:La molar ratio approximately between 1.22:1 and 4:1, corresponding to the B-C line in the phase diagram in Figure 2). Generally, the few works reported in the literature on the growth of La2CoO4 single crystals have been carried out by the Travelling Solvent zone method, using an increased Co concentration for the travelling solvent.…”

Section: Crystal Growthmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 74%

Section: Crystal Growthmentioning

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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show abstract

“…[46][47][48] For the latter, previously reported calorimetric data 46,47,49 agree fairly well with each other as well as with the recent thermodynamic assessment results. 50 On the contrary, the heat capacity calculated for LaCoO 3 by Thakur et al 48 significantly exceeds the results of others 46,47 (see Fig. 7), especially taking into account that Thakur et al 48 reported C , V so C P values recalculated from their data should be even higher due to the thermal expansion of the crystal lattice.…”

mentioning

confidence: 61%

Defect-Induced Properties and Thermodynamics of La_0.5Ba_0.5CoO_3–δ

Malyshkin

Sereda

Sednev-Lugovets

et al. 2022

J. Electrochem. Soc.

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The defect structure model of La0.5Ba0.5CoO3–δ was successfully verified using a combined set of coulometric and thermogravimetric data. The results were used to model the dependences of Seebeck coefficient, measured vs T and pO2 simultaneously with the total conductivity, and chemical strain of this oxide. The partial molar enthalpy of oxygen in La0.5Ba0.5CoO3–δ was calculated from the defect structure model and used to evaluate the enthalpy increments and high-temperature heat capacity of an oxide with constant chemical composition, La0.5Ba0.5CoO2.99, from the drop calorimetric measurement results in air. The standard enthalpies of formation of cubic La0.5Ba0.5CoO2.95 and double LaBaCo2O5.90 perovskites, and the enthalpy of cation ordering in A-sublattice of La0.5Ba0.5CoO2.95, were found using the results of solution calorimetry at 298.15 K. With the data obtained, we predicted the chemical compatibility of La0.5Ba0.5CoO3–δ with solid oxide fuel cell (SOFC) electrolyte materials.

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“…The additional spinel nanoparticles are formed because the precursors in the CVS setup presented here are evaporated with a small excess of the transition metal acetylacetonate instead of perfect equimolar evaporation. The resulting formation of an additional spinel phase corresponds to the equilibrium phase diagram of the LaFeO 3 and LaCoO 3 system.…”

Section: Resultsmentioning

confidence: 97%

LaCo_1–xFe_xO₃ Nanoparticles in Cyclohexene Oxidation

et al. 2023

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The identification of structure−activity relationships is challenging for complex oxides like lanthanum-based perovskite nanoparticles. The purpose of this study is to examine the structure of LaCo 1−x Fe x O 3 nanoparticles and develop a detailed structural model to identify subtle changes of the structure after catalysis. Therefore, small nanoparticles with a significant fraction of surface atoms and varying iron content (x = 0, 0.5, 1) are synthesized in the gas phase by chemical vapor synthesis and tested in cyclohexene oxidation in the liquid phase. The crystal structure is examined by X-ray and selected area electron diffraction. Additionally, the local structure of the cations is probed by Xray absorption spectroscopy at the Co, Fe, La K, and La L 3 -edges. For a quantitative analysis of the local structure before and after catalysis, an atomistic model is refined by the available extended X-ray absorption fine structure spectra using Reverse Monte Carlo methods. The produced nanoparticles are small with a coherent diffraction domain size between 5 and 10 nm, highly crystalline, and consist mainly of the perovskite phase with a secondary spinel phase. In cyclohexene oxidation, the cobalt-containing samples exhibit significant catalytic activities. The active samples show structural changes after catalysis accompanied by reconstruction of the local structure surrounding the cations in the perovskite phase, which resembles edge-sharing cobalt octahedra.

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Thermodynamic Modeling of the La-Co-O System

Cited by 8 publications

References 51 publications

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

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

Defect-Induced Properties and Thermodynamics of La_0.5Ba_0.5CoO_3–δ

LaCo_1–xFe_xO₃ Nanoparticles in Cyclohexene Oxidation

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Thermodynamic Modeling of the La-Co-O System

Cited by 8 publications

References 51 publications

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

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

Defect-Induced Properties and Thermodynamics of La0.5Ba0.5CoO3–δ

LaCo1–xFexO3 Nanoparticles in Cyclohexene Oxidation

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

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

Defect-Induced Properties and Thermodynamics of La_0.5Ba_0.5CoO_3–δ

LaCo_1–xFe_xO₃ Nanoparticles in Cyclohexene Oxidation