Oxygen nonstoichiometry and thermo-chemical stability of La0.6Sr0.4Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8)

Hashimoto, Shinji; Fukuda, Yasuhiro; Kühn, Melanie; Sato, Kazuhisa; Yashiro, Keiji; Mizusaki, Junichiro

doi:10.1016/j.ssi.2010.09.024

Cited by 90 publications

(106 citation statements)

References 14 publications

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“…6). A similar reduction of the electrochemically active zone of LSF64 without current collecting grid could be visualized by 18 O tracer exchange experiments on polarized thin film samples, 56 where a high cathodic bias lowered the chemical potential of oxygen in LSF64, in analogy to our experiments in H 2 /H 2 O.…”

Section: Resultssupporting

confidence: 79%

“…This was also proven by additional 18 O tracer experiments using a two step approach for analyzing tracer diffusion under reducing conditions. 57 Across-plane transport of oxygen can thus hardly cause the 45…”

Section: Resultsmentioning

confidence: 82%

“…[3][4][5] Therefore, generally other compositions such as (La,Sr)(Cr,Mn)O 3 , [6][7][8][9] (La,Sr)(Cr,V)O 3 , 10,11 (La,Sr)(Cr,Ru)O 3 , 12,13 or La and Fe doped SrTiO 3 14,15 are tested under reducing conditions. 16 Although Sr-doped LaFeO 3-δ (LSF) is a typical SOFC cathode material, it is also rather stable in reducing conditions, [17][18][19] with La 0.6 Sr 0.4 FeO 3-δ decomposing below 10 −27 bar pO 2 at 600…”

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confidence: 99%

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Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Kogler

Nenning

Rupp

et al. 2015

J. Electrochem. Soc.

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Owing to its mixed ionic and electronic conductivity and high thermochemical stability, La 0.6 Sr 0.4 FeO 3-δ (LSF64) is an attractive electrode material in solid oxide fuel/electrolysis cells (SOFCs/SOECs). Well defined thin film microelectrodes are used to compare the electrochemical properties of LSF64 in oxidizing and reducing conditions. The high electronic sheet resistance in hydrogen can be overcome by the use of an additional metallic current collector. With the sheet resistance being compensated, the area specific electrode resistance is similar in humidified hydrogen and oxygen containing atmospheres. Analysis of the chemical capacitance and the electrode resistance for current collectors on top and beneath the LSF64 thin film allow mechanistic conclusions on active zones and bulk defect chemistry. Cyclic gas changes between reducing and oxidizing conditions, performed on macroscopic LSF64 thin film electrodes with top current collector, reveal a strong degradation of the surface kinetics in synthetic air with very fast recovery in reducing atmosphere. Additional in-situ high-temperature powder XRD on LSF64 demonstrates the formation of small amounts of iron oxides in humidified hydrogen at elevated temperatures. Solid oxide fuel cells (SOFCs) are in the process of gaining more and more commercial success as highly efficient power generation systems. They transform the chemically bound energy of a fuel to electrical energy. Solid oxide electrolysis cells (SOECs) are the counter parts of SOFCs as they use electrical energy, e.g. excess energy from the grid, to form fuel by electrolysis. Owing to their very high efficiencies, also SOECs are promising devices in future energy technologies. 1Currently Ni/YSZ cermet electrodes are the standard electrodes in SOF/ECs for reducing conditions, but they are known to suffer from several problems, like sulfur poisoning (in SOFC operation), sintering, redox cycle stability etc.2 To find an alternative to Ni/YSZ could therefore be favorable for both SOFCs and SOECs.Electrodes in SOE/FCs have to meet numerous requirements: thermochemical stability over a wide oxygen partial pressure range, high catalytic activity for oxygen exchange reactions, compatibility with adjacent cell components, sufficiently high electronic and ionic conductivity, etc. Perovskite-type oxides such as LaMnO 3 , LaCoO 3 and LaFeO 3 based materials are used in state-of-the-art SOF/EC electrodes in oxygen atmosphere. Often they are mixed ionic and electronic conductors (MIECs), which is advantageous in SOF/ECs as the whole electrode surface area may become active in the oxygen exchange reaction. Employing such MIECs also in reducing atmosphere could be highly attractive. However, Sr-doped LaMnO 3 and LaCoO 3 are only stable under comparatively high oxygen partial pressures and thus not suited for the use in hydrogen. Fe 4+ states can be interpreted as electron holes (h • ) and those determine the electronic conductivity at high oxygen partial pressure as they are the majority mobile charge carrie...

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 82%

mentioning

confidence: 99%

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Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Kogler

Nenning

Rupp

et al. 2015

J. Electrochem. Soc.

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“…It has been reported that the diffusion of Sr from LSCF was triggered by a partial decomposition of LSCF at low oxygen partial pressure caused by the cathodic polarization in an SOFC mode. 20) Wang et al reported a segregation of the Zr component to form SrZrO 3 at the LSCF/GDC interface when the cells were prepared at high temperatures (1200°C). 13) In the present work, however, no such diffusion of the Zr component was observed for both the anode and the cathode, probably due to slower Zr diffusion at 900°C.…”

Section: Analyses Of the Degradation Of The Lscf-sdc Electrodesmentioning

confidence: 99%

High durability of La0.6Sr0.4Co0.2Fe0.8O3−δ/samaria-doped ceria (SDC) composite oxygen electrode with SDC interlayer for reversible solid oxide fuel cell/solid oxide electrolysis cell

Shimura

Nishino

Kakinuma

et al. 2017

J. Ceram. Soc. Japan

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We have examined the long-term durability of a La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3¹¤ (LSCF)samaria-doped ceria (SDC) composite oxygen electrode with SDC interlayer for reversible solid oxide cells (R-SOCs). A symmetrical cell with the configuration: LSCF SDC«SDC interlayer«yttria-stabilized zirconia (YSZ) electrolyte«SDC interlayer«LSCFSDC, was operated at 900°C and a constant current density of 0.5 A cm ¹2 with the top electrode as the anode (O 2 evolution). The IR-free overpotentials at both the anode and cathode were virtually constant during 5500 h of operation. The value of ohmic resistance at the anode side (R A ) increased slightly, whereas that at the cathode side (R C ) increased markedly. The IE performance of the bottom electrode (operated as the cathode), that was measured from ¹1.0 to 1.0 A cm ¹2 every 1000 h, degraded specifically at high current densities. It was found that the thickness, pore size, and porosity in both electrodes were unchanged, but the distribution of the Sr component changed markedly at both the LSCFSDC/SDC interlayer and SDC interlayer/YSZ interfaces. While the diffusion of the Sr component from the anode was limited within the SDC interlayer, the Sr component from the cathode reached the SDC interlayer/YSZ interface, which could increase the R C , likely due to the formation of SrZrO 3 . However, the diffusion rates of Sr were found to be noticeably slowed down at dense portions of the SDC interlayer. Hence, it is essential to prepare a dense, uniform SDC interlayer to improve both the durability and performance of R-SOCs.

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“…La1-xSrxCo1-yFeyO3-δ (LSCF) is widely used as a cathode for SOFCs because of its high mixed electronic-ionic conductivity and fast oxygen surface exchange [2] . Although its electrical properties, oxygen nonstoichiometry and lattice size have been intensively studied [3][4][5][6] , there are few studies about the mechanical properties of LSCF especially under SOFC operating conditions. For the above background, our group investigated the elastic modulus of LSCF at high temperatures under controlled atmospheres [7] .…”

Section: Introductionmentioning

confidence: 99%

Anelastic properties of La0.6Sr0.4Co1−Fe O3- at high temperatures

et al. 2014

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The dynamic amplitude dependence of the Young's modulus and the internal friction of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF6428) at high temperatures were evaluated by resonance measurements. At the temperatures from room temperature to 473 K and above 1073 K, the Young's modulus of LSCF6428 was independent of the dynamic amplitude, while it gradually decreased with increasing the dynamic amplitude in the temperature range from 573 to 973 K. The above dependence was successfully explained by considering the ferroelastic behavior of LSCF6428.

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Oxygen nonstoichiometry and thermo-chemical stability of La0.6Sr0.4Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8)

Cited by 90 publications

References 14 publications

Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

High durability of La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3−δ</sub>/samaria-doped ceria (SDC) composite oxygen electrode with SDC interlayer for reversible solid oxide fuel cell/solid oxide electrolysis cell

Anelastic properties of La0.6Sr0.4Co1−Fe O3- at high temperatures

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Oxygen nonstoichiometry and thermo-chemical stability of La0.6Sr0.4Co1-yFeyO3-δ (y=0.2, 0.4, 0.6, 0.8)

Cited by 90 publications

References 14 publications

Comparison of Electrochemical Properties of La0.6Sr0.4FeO3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Comparison of Electrochemical Properties of La0.6Sr0.4FeO3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

High durability of La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3&minus;&delta;</sub>/samaria-doped ceria (SDC) composite oxygen electrode with SDC interlayer for reversible solid oxide fuel cell/solid oxide electrolysis cell

Anelastic properties of La0.6Sr0.4Co1−Fe O3- at high temperatures

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Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

High durability of La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3−δ</sub>/samaria-doped ceria (SDC) composite oxygen electrode with SDC interlayer for reversible solid oxide fuel cell/solid oxide electrolysis cell