Oxygen diffusion through silver cathodes for solid oxide fuel cells

herle, Jan Van; McEvoy, A. J.

doi:10.1016/0022-3697(94)90230-5

Cited by 79 publications

(79 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Generally, two different approaches were applied. Starting at the exposed sample surface, depth profiles, measuring the 16 O and 18 O intensities as a function of sputter time (corresponding to increasing depth)…”

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

“…where C(x) is the ratio of 18 O -intensity to the total intensity of ( The TOF-SIMS instrument was operated using Bi 1 + primary ions at 25 keV energy.…”

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

“…Samples were pre-annealed in dry research grade oxygen (BOC 99.996%) of natural isotopic abundance for a duration of 10 times that of the isotopic exchange time [26] to ensure oxygen equilibration. The equilibrated sample was then annealed in 18 O enriched gas at a pressure of 200 mbar for 30 minutes before being rapidly quenched to room temperature. Previously reported [13] "wet" exchange samples had been exposed to an atmosphere of H 2 18 O at the anneal temperature and subsequently slow cooled to 100 o C, leading to a key experimental difference between the data reported here and that of George et al…”

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

“…Silver has been noted as a good catalyst for the electrochemical reduction of oxygen in Ag/electrolyte systems [17,18]. The application of silver to enhance the surface oxygen exchange for diffusion in ionic conductors has already been demonstrated [19].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Liu

Chater

Hagenhoff³

et al. 2010

Solid State Ionics

View full text Add to dashboard Cite

Isotopic surface oxygen exchange and its subsequent diffusion has been measured using secondary ion mass spectrometry in the fast ionic conductor La 2 Mo 2 O 9 . A silver coating was applied to the sample surface to enhance the surface exchange process for dry oxygen.Contrary to previous studies performed using a wet atmosphere, no grain boundary diffusion tail was observed under these optimized dry exchange conditions. The activation energy for oxygen diffusion was found to be 0.66(±0.09) eV at high temperature (>570˚C), and 1.25(±0.01) eV at low temperature (<570˚C). Time-of-Flight secondary ion mass spectrometry was employed to investigate the correlation between the silver coating and the 18 O concentration on the sample surface. A close correlation between the presence of silver and oxygen incorporation on the surface was observed.

show abstract

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

“…where C(x) is the ratio of 18 O -intensity to the total intensity of ( The TOF-SIMS instrument was operated using Bi 1 + primary ions at 25 keV energy.…”

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

Section: Oxygen Isotope Exchange and Diffusion Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Liu

Chater

Hagenhoff³

et al. 2010

Solid State Ionics

View full text Add to dashboard Cite

show abstract

“…Under this condition, the electrical conduction takes place only via the electronic species (e.g., holes) at the steady state. The solubility of oxygen in solid silver is relatively high, and the bulk diffusion of oxygen in Ag is also remarkable (7)(8)(9). Therefore, the Ag electrode is not ionically blocking, which is evidenced by the relatively small electrode resistance shown in Fig.…”

mentioning

confidence: 99%

Comment on “Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO ₂ :Y ₂ O ₃ /SrTiO ₃ Heterostructures”

Guo

2009

Science

109

View full text Add to dashboard Cite

García-Barriocanal et al. (Reports, 1 August 2008, p. 676) reported colossal conductivity enhancements in yttria-stabilized zirconia (YSZ)/strontium titanate (STO) epitaxial heterostructures and claimed that the conductivity was ionic. I argue that the claimed ionic conductivity lacks experimental support and that the observed conductivity enhancement is most probably due to the p-type conductivity of STO. (1) fabricated yttria-stabilized zirconia (YSZ)/strontium titanate (SrTiO 3 or STO) epitaxial heterostructures on STO substrates, in which YSZ layers with thickness t ranging from 1 to 62 nm were sandwiched between two 10-nm-thick STO layers. They claimed a huge ionic conductivity enhancement in the heterostructures, and the enhancement was attributed to the high oxygen vacancy concentration and the high mobility at the YSZ/STO interfaces. Their major experimental evidence is that the dc conductance was orders of magnitude lower than the ac conductance. However, it should be pointed out that their dc conductance is not purely electronic.A typical cell investigated by García-Barriocanal et al.(1) is Ag/STO 10nm -YSZ 1nm -STO 10nm -STO Substrate /Ag, in which STO is an important part. Nominally undoped STO is almost always doped with acceptor-type impurities. Therefore, it is a mixed conductor of oxygen vacancies and holes. Owing to the higher mobility of holes, nominally undoped STO shows p-type conductivity (2-4). According to the defect chemistry of acceptor-doped STO (2, 3), the p-type conductivity dominates the overall conductivity when the acceptor concentration is low. Therefore, one has to consider the p-type conductivity of the 10-nm-thick STO layers and the STO substrate.The electronic (for example, p-type) partial conductivity can be experimentally deduced by means of the Hebb-Wagner polarization (5, 6). A key point of the Hebb-Wagner polarization is that an electrode should block the ionic species (e.g., oxygen vacancies). Under this condition, the electrical conduction takes place only via the electronic species (e.g., holes) at the steady state. The solubility of oxygen in solid silver is relatively high, and the bulk diffusion of oxygen in Ag is also remarkable (7-9). Therefore, the Ag electrode is not ionically blocking, which is evidenced by the relatively small electrode resistance shown in Fig. 1. In addition, the oxygen diffusion in STO is much too sluggish in the temperature range of 80 to 260°C [the temperature range in figure 3 in (1)]. Estimated from the chemical diffusion coefficient of oxygen in STO (10), it takes about 10 8 s for oxygen to diffuse a distance of only 1 mm at 170°C. Therefore, the dc conduction of the cell Ag/STO 10nm -YSZ 1nm -STO 10nm -STO Substrate /Ag can never reach the steady state within a reasonable time period. In view of the fact that the Ag electrode is not ionically blocking, and that the steady state cannot be reached within a reasonable time period, one can conclude that the dc conductance of the cell Ag/STO 10nm -YSZ 1nm -STO 10nm -STO Substrate /Ag consi...

show abstract

Stability and Performance of Silver in an SOFC Interconnect Environment

Compson

Choi

Abemathy

et al. 2009

Advances in Solid Oxide Fuel Cells III

View full text Add to dashboard Cite

Oxygen diffusion through silver cathodes for solid oxide fuel cells

Cited by 79 publications

References 16 publications

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Comment on “Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO ₂ :Y ₂ O ₃ /SrTiO ₃ Heterostructures”

Stability and Performance of Silver in an SOFC Interconnect Environment

Contact Info

Product

Resources

About

Oxygen diffusion through silver cathodes for solid oxide fuel cells

Cited by 79 publications

References 16 publications

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Comment on “Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO 2 :Y 2 O 3 /SrTiO 3 Heterostructures”

Stability and Performance of Silver in an SOFC Interconnect Environment

Contact Info

Product

Resources

About

Comment on “Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO ₂ :Y ₂ O ₃ /SrTiO ₃ Heterostructures”