Thermodynamics, defect structure, and charge transfer in doped lanthanum cobaltites: an overview

Петров, А. Н.; Черепанов, В.А.; Zuev, A. Yu.

doi:10.1007/s10008-006-0124-0

Cited by 74 publications

(59 citation statements)

References 48 publications

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“…[ 38 ] La 2 CoO 4 is also known to be formed if the perovskite-type LaCoO 3 is reduced at high temperatures. [ 39 ] wileyonlinelibrary Figure 1. Bright-fi eld images of plan-view (left column) and cross-section (right column) TEM specimens prepared from a,b) LSC700, c,d) LSC700-100, e,f) LSC800 and g,h) LSC800-100.…”

Section: Crystalline Phasesmentioning

confidence: 99%

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Dieterle

Bockstaller

Gerthsen

et al. 2011

Advanced Energy Materials

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Numerous preparation techniques for perovskite-based MIEC materials have been developed over the last years. Apart from the conventional methods of cathode preparation, including high temperature calcination, mechanical grinding of powders, screen printing and sintering of thick fi lm layers, alternative synthesis and deposition routes are available. Nanocrystalline LSC or La 1−x Sr x Co 1−y Fe y O 3− δ thin fi lms on electrolyte substrates were already fabricated by pulsed laser deposition, [6][7][8][9] DC, and RF sputtering, [ 10,11 ] spray pyrolysis, [ 12 ] and sol-gel deposition. [13][14][15][16][17] In this work the chemical and structural properties and the stability of nanoscaled La 0.6 Sr 0.4 CoO 3− δ LSC thin fi lm cathodes on polycrystalline Gd 0.1 Ce 0.9 O 1.95 (CGO) substrates were investigated thoroughly. The fabrication by a low-temperature sol-gel technique is favorable for tailoring the grain size, porosity and cathode-fi lm thickness. [ 18 ] The electrochemical properties of the nanoscaled LSC thin fi lm cathodes were already reported by Hayd et al. who presented an outstanding electrochemical performance and extraordinary low area specifi c resistances as low as ASR chem = 0.023 Ω cm 2 at an operating temperature of 600 ° C. [ 19,20 ] Interestingly enough, theoretical models predicted ASR chem values up to one order of magnitude larger than the experimental data. For obvious reasons, the excellent performance of our nanoscaled cathodes does not solely depend on microstructure (porosity, increased inner surface area) as reported in previous work, [ 21 ] but presumably on the enhanced catalytic properties of the La 0.6 Sr 0.4 CoO 3− δ . However, the outstanding electrochemical performance motivates the analysis of the microstructure and phase composition of the LSC cathodes presented in this work.The nanoscaled LSC thin-fi lm cathodes were studied by transmission and scanning transmission electron microscopy (TEM/STEM) combined with energy-dispersive X-ray spectroscopy (EDXS). Moreover, high-angle annular dark-fi eld (HAADF) STEM tomography was used to study the distribution of the pores and quantify the porosity, which was not reported for nanoscaled (La,Sr)CoO 3 -based materials in literature before. Although several techniques like μ -tomography, [ 22 ] FIB-tomography, [ 23,24 ] transmission X-ray microscope based X-ray tomography, [ 12 , 25 ] mercury intrusion, [ 22 , 26 ] nitrogen adsorption, [ 27 ] or the Archimedes method [ 22 , 28 ]

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Section: Crystalline Phasesmentioning

confidence: 99%

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Dieterle

Bockstaller

Gerthsen

et al. 2011

Advanced Energy Materials

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“…Perovskite-related cobaltites exhibit substantially better transport properties and electrochemical activity in comparison with their ferrite and manganite analogues, but possess also a lower thermodynamic stability and higher thermal and chemical expansion [4,8,27,101,111,136,138,152,156,157,159,168,179]. Due to relatively high mixed conductivity and fast exchange kinetics, significant attention is drawn to the layered cobaltites where the state of Co cations is often more stable with respect to disordered perovskite phases and the TECs are lower; important compositional families are LnBaCo 2 O 5 þ d (Ln ¼ Pr, Gd-Ho, Y), LnBaCo 4 O 7 þ d (Ln ¼ Dy-Yb,Y), and also Ruddlesden-Popper type (Ln,A) 4 Co 3 O 10Àd and (Ln,A) 2 CoO 4AEd (Ln ¼ La-Nd) existing at moderately reduced oxygen pressures (see Refs [179][180][181][182][183][184] and references cited therein).…”

Section: Perovskite-related Mixed Conductors: a Short Overviewmentioning

confidence: 99%

“…Due to relatively high mixed conductivity and fast exchange kinetics, significant attention is drawn to the layered cobaltites where the state of Co cations is often more stable with respect to disordered perovskite phases and the TECs are lower; important compositional families are LnBaCo 2 O 5 þ d (Ln ¼ Pr, Gd-Ho, Y), LnBaCo 4 O 7 þ d (Ln ¼ Dy-Yb,Y), and also Ruddlesden-Popper type (Ln,A) 4 Co 3 O 10Àd and (Ln,A) 2 CoO 4AEd (Ln ¼ La-Nd) existing at moderately reduced oxygen pressures (see Refs [179][180][181][182][183][184] and references cited therein). Information on the long-term performance of such materials under SOFC cathodic conditions is, however, scarce.…”

Section: Perovskite-related Mixed Conductors: a Short Overviewmentioning

confidence: 99%

Oxygen Ion‐Conducting Materials

Хартон

Marques

Kilner

et al. 2009

Solid State Electrochemistry I

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Oxygen ionic and mixed ionic-electronic conductors find important applications in solid-state electrochemical devices, including sensors, solid oxide fuel cells, hightemperature electrolyzers, and oxygen separation membranes. This chapter presents a brief overview of oxide phases with high diffusivity of O 2À anions, providing an introduction to this fascinating topic. Particular emphasis is centered on the comparative analysis of ionic and electronic conductivity variations in the major groups of solid oxide electrolytes and mixed conductors, such as perovskite-and fluorite-related compounds, apatite-type silicates, and derivatives of g-Bi 4 V 2 O 11 and b-La 2 Mo 2 O 9 . The defect chemistry mechanisms relevant to the oxygen ion migration processes are briefly discussed. IntroductionTechnologies based on the use of high-temperature electrochemical cells with oxygen anion-or mixed-conducting ceramics provide important advantages with respect to the conventional industrial processes [1][2][3][4][5][6][7][8]. In particular, solid oxide fuel cells (SOFCs) are considered as alternative electric power generation systems due to high energy-conversion efficiency, fuel flexibility, and environmental safety [1][2][3]. Dense ceramic membranes with mixed oxygen-ionic and electronic conductivity have an infinite theoretical separation factor with respect to oxygen, and can be used for gas separation and the partial oxidation of light hydrocarbons [4,5,7,8] (these and other applications are reviewed in Chapters 12 and 13). For all types of electrochemical cells, the key properties which determine the use of a material are the partial ionic and electronic conductivities. As an example, solid electrolytes for SOFCs, oxygen pumps and electrochemical sensors should exhibit a maximum oxygen ionic conductivity, while the electronic transport should be minimal. In contrast, for SOFC electrodes Solid State Electrochemistry I: Fundamentals, Materials and their Applications. Edited by Vladislav V. Kharton

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“…LSCF is a mixed ionic-electronic conductor (MIEC) belonging to the perovskite family, ABO 3 -type, in which both A and B sites can be partially or fully substituted. Partial substitution of La 3+ for Sr 2+ in LaCoO 3−δ was found to be accompanied by an increase in mean oxidation state of the cobalt ions and a significant increase in oxygen deficiency due to charge compensation [5,6]. Substituting Fe on the B site gradually decreases the degree of ionic conductivity at lower temperatures [7] but also leads to a reduced thermal expansion coefficient (TEC) and hence better thermo-mechanical compatibility with CGO electrolytes [3,6].…”

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confidence: 99%

“…Thus La 1−x Sr x Co 1−y Fe y O 3−δ (LSCF) is preferred as a material of choice for working temperatures below 700 °C having high electronic and ionic conductivity as well as good catalytic activity for oxygen reduction reaction [3][4][5][6][7]. LSCF is a mixed ionic-electronic conductor (MIEC) belonging to the perovskite family, ABO 3 -type, in which both A and B sites can be partially or fully substituted.…”

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Performance optimization of LSCF/Gd:CeO2 composite cathodes via single-step inkjet printing infiltration

et al. 2017

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Thermodynamics, defect structure, and charge transfer in doped lanthanum cobaltites: an overview

Cited by 74 publications

References 48 publications

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Oxygen Ion‐Conducting Materials

Performance optimization of LSCF/Gd:CeO2 composite cathodes via single-step inkjet printing infiltration

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Thermodynamics, defect structure, and charge transfer in doped lanthanum cobaltites: an overview

Cited by 74 publications

References 48 publications

Microstructure of Nanoscaled La0.6Sr0.4CoO3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Microstructure of Nanoscaled La0.6Sr0.4CoO3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Oxygen Ion‐Conducting Materials

Performance optimization of LSCF/Gd:CeO2 composite cathodes via single-step inkjet printing infiltration

Contact Info

Product

Resources

About

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells

Microstructure of Nanoscaled La_0.6Sr_0.4CoO_3‐δ Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells