Thermal and chemical induced expansion of La0.3Sr0.7(Fe,Ga)O3− ceramics

Хартон, В.В.; Yaremchenko, A.A.; Патракеев, М.В.; Naumovich, E.N.; Marques, F.M.B.

doi:10.1016/s0955-2219(02)00308-4

Cited by 154 publications

(123 citation statements)

References 25 publications

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“…There is an anomalous variation appearing on the LTEC of the LSCF specimen, with a slop increase occurring near 700°C. This behavior is typical for La 1-x Sr x Co 1-y Fe y O 3-d perovskites [30,31] and can be explained by a chemically induced lattice expansion due to oxygen lose and formation of oxygen vacancies at high temperatures [33]. When adding some fraction of LNO to the LSCF composition, the LTECs became a straight line, which is similar with that of the LNO specimen.…”

Section: Electrical Conductivitysupporting

confidence: 63%

Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

et al. 2012

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The structure, electrical conduction, thermal expansion and electrochemical properties of the La0.6Sr0.4Co0.2Fe0.8O3–δ + La2NiO4+δ (LSCF‐LNO) composite cathodes were investigated with regard to the volume fraction of the LNO composition. No chemical reaction product between the two constituent phases was found for the composite cathodes sintered at 1,400 °C for 10 h within the sensitivity of the XRD. Compared to the performance of the LSCF cathode, the LNO composition in the composite cathode plays a role in deteriorating both electrical conductivity and electrochemical properties, however, improving the thermal expansion properties. The trade‐off between electrical conducting and thermal expansion classifies the composite cathode containing 30 volume percent (vol.%) LNO as the optimum composition. For characterizing cathode performance in a single cell, a slurry spin coating technique was employed to prepare a porous cathode layer as well as a YSZ/Ce0.8Sm0.2O3–δ (SDC) electrolyte. The optimum conditions for fabricating the YSZ/SDC electrolyte were investigated. The resulting single cell with 70 vol.% LSCF‐30 vol.%LNO (LSCF‐LNO30) cathode shows a power density of 497 mW cm–2 at 800 °C, which is lower than that of the cell with a LSCF cathode, but still within the limits acceptable for practical applications.

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Section: Electrical Conductivitysupporting

confidence: 63%

Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

et al. 2012

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“…Also, in many cases the ionic conductivity of heavily doped gallates is lower than that of LSGM, particularly in the intermediate-temperature range and under oxidizing conditions, when the average oxidation state of transition metal cations is higher than 3 þ (Figure 9.8). Nevertheless, optimization of the acceptor-type and variable-valence dopants content makes it possible to develop mixed-conducting membranes with a high oxygen permeability and improved dimensional stability [114][115][116][117]. The disadvantages of LaGaO 3 -based electrolytes and membrane materials include the possible reduction and volatilization of gallium oxide, the relatively high cost of gallium, and significant reactivity with electrodes and catalysts.…”

Section: Transport Properties Of Other Fluorite-related Phases: Selecmentioning

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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“…47 Line intercept grain size determinations 48 (not shown) indicated that these dense dilatometry samples had grain sizes of 1.7 ± 0.2 μm. As shown in Figure 2, no mechano-chemical coupling was detected in these large grained LSF64 samples below ∼525…”

Section: Resultsmentioning

confidence: 94%

Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

Yang

Nicholas

2014

J. Electrochem. Soc.

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Here, the chemical oxygen surface exchange coefficient and film stress of porous La 0.6 Sr 0.4 FeO 3-δ (LSF64) thick films were simultaneously measured in situ between 275-375 • C and 275-700 • C, respectively, using a bilayer curvature measurement technique. The magnitude and activation energy of the porous LSF64 thick film oxygen surface exchange coefficients were consistent with those from large grained, bulk samples. However, unlike large-grained, dilatometry-tested bulk LSF64 samples that only exhibited measurable chemical stress above 525 • C, the fine-grained, curvature-tested porous LSF64 thick films studied here exhibited measurable chemical stress over the complete temperature range from 275 to 700 • C. Further, the porous LSF64 thick films exhibited a kink in their Arrhenius chemical stress behavior ( Oxygen-exchange-capable mixed ionic electronic conducting (MIEC) materials are widely used in electrochemical devices such as solid oxide fuel cells (SOFCs), 1-5 catalysts, 6,7 and gas separation membranes. 8,9 However, debate exists on the oxygen surface exchange rates of even the most-common MIEC materials. For instance, chemical oxygen surface exchange coefficient (k) discrepancies greater than 4 orders of magnitude are reported at identical temperature and oxygen partial pressure conditions for the MIEC material La 0.6 Sr 0.4 FeO 3-δ (LSF64). [10][11][12][13] Similarly, large k discrepancies have been observed for other MIEC materials such as lanthanum strontium cobalt iron oxide [14][15][16][17] and reduced cerium oxide. [18][19][20][21] Since recent studies have shown that strain can alter k, 20,21 it is likely that some of these observed k discrepancies are due to differences in MIEC stress state. Unfortunately, simultaneous k and stress state measurements on MIEC materials are largely absent from the literature. Here, the stress and oxygen surface exchange coefficients of porous LSF64 thick films atop single crystal (Y 2 O 3 ) 0.13 (ZrO 2 ) 0.87 (YSZ) substrates were simultaneously measured in situ using a new bilayer curvature measurement technique. Theoretical BackgroundPorous thick film stress measurement.-Stresses in dense thin films (i.e. those with film to substrate thickness ratios less than 1:1000) can be rigorously extracted from bilayer curvature measurements using Stoney's Equation:whereλ St is the thickness averaged film stress predicted from Stoney's Equation, κ is the bilayer curvature, h s is the substrate thickness, h f is the film thickness, and M S is the substrate biaxial modulus defined as E S / (1 − υ S ) where E S is substrate Young's modulus and υ S is the substrate Poisson's Ratio. 22,23 Stoney's equation is convenient because the thickness averaged film stress (λ) (which is the same as the stress at each point in the film due to the film's thinness) can be extracted * Electrochemical Society Student Member.* * Electrochemical Society Active Member. z E-mail: jdn@msu.edu from bilayer curvature measurements without knowledge of the film elastic properties. In contrast, stre...

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Thermal and chemical induced expansion of La0.3Sr0.7(Fe,Ga)O3− ceramics

Cited by 154 publications

References 25 publications

Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

Oxygen Ion‐Conducting Materials

Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

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Thermal and chemical induced expansion of La0.3Sr0.7(Fe,Ga)O3− ceramics

Cited by 154 publications

References 25 publications

Characterization of La0.6Sr0.4Co0.2Fe0.8O3–δ + La2NiO4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

Characterization of La0.6Sr0.4Co0.2Fe0.8O3–δ + La2NiO4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

Oxygen Ion‐Conducting Materials

Porous Thick Film Lanthanum Strontium Ferrite Stress and Oxygen Surface Exchange Bilayer Curvature Relaxation Measurements

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Product

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Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells

Characterization of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ + La₂NiO_4+δ Composite Cathode Materials for Solid Oxide Fuel Cells