Temperature-independent resistive oxygen sensors based on SrTi1−Fe O3− solid solutions

Rothschild, Avner; Litzelman, Scott J.; Tuller, Harry L.; Menesklou, Wolfgang; Schneider, Thomas; Ivers-Tiffée, Ellen

doi:10.1016/j.snb.2004.09.044

Cited by 116 publications

(114 citation statements)

References 25 publications

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“…For higher iron content, conductivity decreases with the temperature increase. It agrees well with the previously reported results [13,14,21,22]. As a general trend, at lower doping levels the conductivities increase with an increase of the temperature, while at higher temperatures the conductivities decrease with an increase of temperature.…”

Section: Resultssupporting

confidence: 93%

“…Indeed, as shown in the literature [13], the transition in temperature behavior is observed at iron doping level of x00.35. Extensive information about these interesting properties is given in [14]. Electrical conductivities of both materials are low.…”

Section: Resultsmentioning

confidence: 99%

“…Iron doped strontium titanates, SrTi 1-x Fe x O 3±δ (STF), present promising properties for resistive-type oxygen gas sensors [13,14]. Due to their close to zero temperature coefficient of resistance (TCR) the STF materials are proposed as next generation oxygen sensors for exhaust gas monitoring in cars.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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

et al. 2012

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“…Rothschild et.al [65,66] reported that with increasing Fe dopant the UPS spectra, in the range of low binding energies (b25 eV), showed that the valence band of STF x is broader than that for SrTiO 3 and extended closer to the conduction band edge, which corresponded to the reduction in the band-gap energy of these compositions [65,66]. Table 3 presents the analyzed data and results of UPS measurement.…”

Section: Ups Studiesmentioning

confidence: 99%

Preparation, surface state and band structure studies of SrTi(1−x)Fe(x)O(3−δ) (x=0–1) perovskite-type nano structure by X-ray and ultraviolet photoelectron spectroscopy

et al. 2012

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“…STF is a well suited model material because of its high thermo-chemical stability and the good knowledge of its electrochemical properties in oxidizing atmospheres. 17,[27][28][29][30][31][32] Lithographically patterned Pt current collectors were applied beneath the STF thin films to compensate the comparatively low electronic conductivity in reducing conditions. 4,32 Pt current collectors on top were tested as well and a high electro-catalytic activity was observed at the Pt-STF-atmosphere triple phase boundary.…”

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The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

Nenning

Volgger

Miller

et al. 2017

J. Electrochem. Soc.

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Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O 3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H 2 +H 2 O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films to compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H 2 :H 2 O mixing ratio and the polarization. Acceptor-doped mixed ionic and electronic conductors are a promising class of materials for application in solid oxide fuel cell (SOFC) electrodes and they are widely investigated as SOFC cathodes due to their low polarization resistance.1-3 Some of these materials are chemically stable and mixed conducting also in humidified hydrogen atmosphere, 4 which makes them applicable in SOFC anodes. Several mixed conductors, such as acceptor doped (La,Sr)(Cr,Mn)O 3 , [5][6][7][8] donor-doped SrTiO 3 9,10 and Sr(Ti,Fe)O 3-δ -Ce 0.9 Gd 0.1 O 2-δ (STF-GDC) composites 11 were investigated in form of porous SOFC anodes. Most of these studies revealed moderately low polarization resistances. In STF-GDC composites, for example, the anode polarization resistance was <0.2 cm 2 at 800• C, and the overall performance increased with increasing Fe content. However, the usually ill-defined geometry of porous electrodes makes the analysis of specific materials parameters such as electronic and ionic conductivity or oxygen exchange activity very challenging.Thin film model electrodes have well defined and controllable geometry and comparatively simple pathways of electron and oxygen ion migration. This strongly facilitates identification of reaction pathways and quantification of the oxygen exchange activity of the material's surface. [12][13][14][15][16][17][18] Mechanistic studies using thin film model electrodes have so far been performed mainly in oxidizing atmosphere. Thorough studies of the mechanisms of electrochemical oxygen exchange in reducing atmospheres are still largely missing, not only for STF, but for most reduction stable mixed conductors, except for (Gd or Sm) doped ceria [19][20][21][22][23][24] and a study on (La,Sr)FeO 3-δ. 25 The typically low electronic conductivity of accep...

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Temperature-independent resistive oxygen sensors based on SrTi1−Fe O3− solid solutions

Cited by 116 publications

References 25 publications

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

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

Preparation, surface state and band structure studies of SrTi(1−x)Fe(x)O(3−δ) (x=0–1) perovskite-type nano structure by X-ray and ultraviolet photoelectron spectroscopy

The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells

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Temperature-independent resistive oxygen sensors based on SrTi1−Fe O3− solid solutions

Cited by 116 publications

References 25 publications

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

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

Preparation, surface state and band structure studies of SrTi(1−x)Fe(x)O(3−δ) (x=0–1) perovskite-type nano structure by X-ray and ultraviolet photoelectron spectroscopy

The Electrochemical Properties of Sr(Ti,Fe)O3-δfor Anodes in Solid Oxide Fuel Cells

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The Electrochemical Properties of Sr(Ti,Fe)O_3-δfor Anodes in Solid Oxide Fuel Cells