BSCF epitaxial thin films: Electrical transport and oxygen surface exchange

Burriel, Mónica; Niedrig, Christian; Menesklou, Wolfgang; Wagner, Stefan; Santiso, J.; Ivers-Tiffée, Ellen

doi:10.1016/j.ssi.2010.03.005

Cited by 39 publications

(37 citation statements)

References 30 publications

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“…Similar small features (less than 0.2 µm) have been observed on the surface of epitaxial BSCF5582 films grown by PLD [24]. EDX analysis did not detect any impurities in the bottom of a sputtered 8 crater on sample A or on the surfaces of sample C. The measured compositions were Ba0.52Sr0.54Co0.80Fe0.20O3- (sample A) and Ba0.49Sr0.51Co0.80Fe0.20O3-sample C.…”

Section: Resultssupporting

confidence: 77%

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

et al. 2014

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Section: Resultssupporting

confidence: 77%

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

et al. 2014

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“…30 Activation energy of k was calculated to be of about E a = 0.98 eV, much lower than that previously reported of E a = 1.6 eV. 2 The reduced k values are probably related to a large degradation of the surface hindering the oxygen adsorption and dissociation.…”

Section: 21mentioning

confidence: 77%

Chemical Strain and Oxidation-Reduction Kinetics of Epitaxial Thin Films of Mixed Ionic-Electronic Conducting Oxides Determined by X-Ray Diffraction

Moreno

Zapata

Roqueta

et al. 2014

J. Electrochem. Soc.

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In all cases the values correspond to their particular defect equilibrium and degree of charge localization. The oxygen surface exchange kinetics was also evaluated from in-situ time-resolved analyses of the cell parameter variations. LSC, LNO and GBCO films show fast oxygen reduction kinetics, k chem = 5 · 10 −6 , 3 · 10 −6 , and 2 · 10 −7 cm/s at 700 • C, respectively, in relative agreement with reported values, while BSCF films show much slower kinetics than expected, below k chem = 10 −7 cm/s at 650 • C, related to the degradation process observed in the films.

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“…[1][2][3] The surface-exchange coefficient (k) and the oxygen diffusion coefficient (D) provide key information about the oxygen transport mechanism that dominates the cathodic ORR. Many publications have assessed the D and k values of MIEC materials, most commonly by; electrical conductivity relaxation (ECR) measurements for dense bulks [4][5][6][7][8] or thin-films 9,10 (k δ , D δ ) and by oxygen tracer diffusion experiments for thin-films 11 or powder 12 (k * , D * ). The oxygen transport parameters are usually determined by ex situ experiments for model systems (i.e.…”

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confidence: 99%

Oxygen Transport Kinetics of Mixed Ionic-Electronic Conductors by Coupling Focused Ion Beam Tomography and Electrochemical Impedance Spectroscopy

Almar

Szász

Weber

et al. 2017

J. Electrochem. Soc.

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The oxygen reduction reaction of mixed ionic-electronic conducting (MIEC) cathodes Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) and La 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) is investigated by detailed electrochemical impedance spectroscopy and focused ion beam tomography. The oxygen transport parameters of these materials are usually determined for model systems, such as dense bulks or thin films. However in the present study, probable differences regarding the time and thermal history of the samples (e.g. ambient poisoning gases, grain coarsening, secondary phase or surface segregation, etc.) were avoided by the in situ sintering of electrodes with nominal stoichiometry under synthetic air. The microstructural parameters of the electrodes are obtained by 3D FIB-SEM reconstruction tomography and subsequently used in combination with the Adler-Lane-Steele analytical model to calculate a simulated cathode resistance. Large discrepancies are observed compared to the electrochemical impedance measurements. In particular, the electrochemical impedance measurements do not show a Gerischer behavior, as expected for MIEC materials controlled by a coupled surface-exchange and bulk diffusion. Analysis by distribution function of relaxation times (DRT) reveals four individual processes taking place, indicating a surface-exchange controlled behavior with a reaction zone similar to the particle size. Bulk diffusion (D) and surface-exchange (k) coefficients from literature are critically discussed and tentative surface-exchange coefficients (k) for both MIECs are given. High-temperature devices such as solid oxide fuel cells (SOFCs) and oxygen transport membranes (OTMs) are promising systems for working towards zero-emissions power generation. The selected materials require high chemical and microstructural stability, as well as high catalytic activity during the oxygen reduction reaction (ORR), under normal operational conditions (i.e. operational temperature and oxygen partial pressure). Particularly interesting are the mixed ionic-electronic conducting (MIEC) materials, based on the ABO 3 perovskite structure. Their material properties can be flexibly customized, giving solid solutions with high ionic-electronic conductivity and hence good transport properties. More specifically, La 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) has become established as the stateof-the-art SOFC cathode, while Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) has presented outstanding oxygen permeation flux in its cubic phase. 1-3The surface-exchange coefficient (k) and the oxygen diffusion coefficient (D) provide key information about the oxygen transport mechanism that dominates the cathodic ORR. Many publications have assessed the D and k values of MIEC materials, most commonly by; electrical conductivity relaxation (ECR) measurements for dense bulks [4][5][6][7][8] and temperature for LSCF cathodes. 17 Here it should be pointed out that the well-known ALS model can only be applied if the measured impedance shows a Gerischer impedance, which indicates tha...

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BSCF epitaxial thin films: Electrical transport and oxygen surface exchange

Cited by 39 publications

References 30 publications

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Chemical Strain and Oxidation-Reduction Kinetics of Epitaxial Thin Films of Mixed Ionic-Electronic Conducting Oxides Determined by X-Ray Diffraction

Oxygen Transport Kinetics of Mixed Ionic-Electronic Conductors by Coupling Focused Ion Beam Tomography and Electrochemical Impedance Spectroscopy

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