Stability and mixed ionic–electronic conductivity of (Sr,La)(Ti,Fe)O3−δ perovskites

Fagg, Duncan P.; Хартон, В.В.; Frade, J.R.; Ferreira, Antônio Alves

doi:10.1016/s0167-2738(02)00257-6

Cited by 80 publications

(35 citation statements)

References 26 publications

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“…symmetric atmospheres) reveal that the series resistances (R s ) do not significantly change with the Fe content and they remain stable with time under both oxidising and reducing conditions. Furthermore, the R s values are very close to the YSZ electrolyte contribution indicating a good lateral contact, which implies that the overall electronic conductivity of the material is high enough and does not contribute significantly to the overall cell ohmic drop, in agreement with the results reported in the literature in similar systems (25,26). The best results are obtained for x>5.0 in the La 4 Sr 8 Ti 12-x Fe x O 38-δ series.…”

Section: Substituted Strontium Titanatessupporting

confidence: 88%

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Potenciales materiales de electrodo para Pilas de Combustible de Óxido Sólido simétricas

Morales¹,

Vázquez²,

Lincke³

et al. 2008

Bol. Soc. Esp. Ceram. Vidr.

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Section: Substituted Strontium Titanatessupporting

confidence: 88%

“…One of the most obvious candidates is Fe to form (La,Sr) (Ti 1-x Fe x )O 3±δ . This system shows both n-type and p-type conductivity (25)(26)(27)(28) and rather promising performances under pure hydrogen (29).…”

Section: Substituted Strontium Titanatesmentioning

confidence: 97%

Potenciales materiales de electrodo para Pilas de Combustible de Óxido Sólido simétricas

Morales¹,

Vázquez²,

Lincke³

et al. 2008

Bol. Soc. Esp. Ceram. Vidr.

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“…Moreover, a~3 μm thick dense interlayer is visible between the electrolyte and cathode. This is a product of the reaction of [18]. The EDX analysis revealed that the reaction products are composed mainly of Sr and Zr, which form insulating SrZrO 3 [18].…”

Section: Resultsmentioning

confidence: 96%

“…Recently, this material was used by Jung et al [17] as a model mixed conductor dense cathode material for SOFC applications. Electrical conductivities in reducing and oxidizing atmospheres and chemical interactions with YSZ were studied before by Fagg et al [18]. However, information about their electrocatalytic (oxygen reduction reaction) properties in symmetrical cells was not reported for porous samples.…”

Section: Introductionmentioning

confidence: 99%

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

et al. 2012

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Doped strontium titanates are very versatile materials. Iron doped SrTiO 3 can be used, for example, as a material for resistive gas sensors and fuel cell electrodes. In this paper, two compositions based on Fe doped SrTiO 3 were studied as possible candidates for cathode application in SOFCs. Namely, SrTi 0.65 Fe 0.35 O 3 and SrTi 0.50 Fe 0.50 O 3 were examined. A chemical reactivity between electrode and YSZ electrolyte material was investigated, since Sr containing cathode materials in contact with YSZ electrolyte are prone to form insulating phases. Electrical conductivity of bulk samples showed relatively low total conductivities of 0.4 S cm −1 and~2 S cm −1 for STF35 and STF50 respectively. Suitability for cathode application was studied by Electrochemical Impedance Spectroscopy in a symmetrical electrode configuration. Area specific resistance (ASR) was determined in the temperature range from 600°C to 800°C. At 790°C samples show polarization ASR of approximately 0.1Ω cm 2 . It can be expected that further reduction of electrode ASR can be obtained by introduction of ceria barrier layer and tailoring of the electrode microstructure.

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“…The hardness and fracture toughness of the as-sintered and heat treated samples were estimated using Vicker's indentation method. A load of up to 10N was applied for 10 seconds and the fracture toughness of the membranes was calculated using the equations of Niihara et al [12]. The indentation crack propagation was studied using SEM and optical microscopy for identifying any possible influence in the fracture behavior due to the change in the δ.…”

Section: Electrical Conductivity and Seebeck Coefficient As A Functiomentioning

confidence: 99%

Oxygen Transport Ceramic Membranes

Bandopadhyay¹,

Nithyanantham²

2006

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Ti doping on La 1-x Sr x FeO 3-δ (LSF) tends to increase the oxygen equilibration kinetics of LSF in lower oxygen activity environment because of the high valence state of Ti. However, the addition of Ti decreases the total conductivity because the O 3-δ (LSFT, x = 0.45) have been experimentally and theoretically investigated to elucidate (1) the dependence of oxygen occupancy and electrochemical properties on temperature and oxygen activity by thermogravimetric analysis (TGA) and (2) the electrical conductivity and carrier concentration by Seebeck coefficient and electrical measurements.In the present study, dual phase (La 0.2 Sr 0.8 Fe 0.6 Ti 0.4 O 3-δ /Ce 0.9 Gd 0.1 O 2-δ ) membranes have been evaluated for structural properties such as hardness, fracture toughness and flexural strength. The effect of high temperature and slightly reducing atmosphere on the structural properties of the membranes was studied. The flexural strength of the membrane decreases upon exposure to slightly reducing conditions at 1000°C. The as-received and post-fractured membranes were characterized using XRD, SEM and TG-DTA to understand the fracture mechanisms. Changes in structural properties of the composite were sought to be correlated with the physiochemical features of the two-phases.We have reviewed the electrical conductivity data and stoichiometry data for La 0.2 Sr 0.8 Cr 0.2 Fe 0.8 O 3-δ some of which was reported previously. Electrical conductivity data for La 0.2 Sr 0.8 Cr 0.2 Fe 0.8 O 3-δ (LSCrF) were obtained in the temperature range, 752 ~ 1055 °C and in the pO 2 range, 10 -18 ~ 0.5 atm. The slope of the plot of log σ vs. log pO 2 is ~1/5 in the p-type region, pO 2 = 10 -5 ~ 10 -1 atm. The pO 2 at which the p-n transition is observed increases with increasing temperature. The activation energy for ionic conduction was estimated to be 0.86 eV from an Arrhenius plot of the minimum conductivity vs. reciprocal temperature. At temperatures below 940°C, a plateau in the conductivity isotherm suggests the presence of a two-phase region. Most likely, phase separation occurs to form a mixture of a perovskite phase and an oxygen vacancy ordered phase related to brownmillerite. Additional data for the oxygen non stoichiometry are presented.iv

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Stability and mixed ionic–electronic conductivity of (Sr,La)(Ti,Fe)O3−δ perovskites

Cited by 80 publications

References 26 publications

Potenciales materiales de electrodo para Pilas de Combustible de Óxido Sólido simétricas

Potenciales materiales de electrodo para Pilas de Combustible de Óxido Sólido simétricas

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

Oxygen Transport Ceramic Membranes

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