Oxygen Ion Conductors

Steele, B.C.H.

doi:10.1142/9789814434294_0015

Cited by 78 publications

(32 citation statements)

References 15 publications

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“…Following the n nomenclature, 16 the O1 oxygen site (22% in the high-temperature phase) corresponds to a 4 environment whereas O2 (53%) and O3 (25%) correspond to a 3 environment. Based on the known correlation 16 (see Introduction), we therefore ascribe the D1 domain in the spectrum to 3 and the D2 and D3 range to 4 , which is also in agreement with the fact that quadrupolar splitting is weaker in the D2 and D3 [ 4 ] domains than in the D1 [ 3 ] domain. The contribution of the D2 and D3 domains obtained from our results corresponds to 18% of the overall intensity, which is close to the abundance of the O1 sites in the crystal structure.…”

Section: Discussionsupporting

confidence: 79%

17O NMR in room temperature phase of La2Mo2O9 fast oxide ionic conductor

et al. 2005

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A room temperature (17)O NMR study of La(2)Mo(2)O(9), a fast oxide ionic conductor exhibiting a phase transition at 580 degrees C between a low-temperature alpha-phase and a high-temperature beta-phase, is presented. Four partly overlapping quasi-continuous distributions of oxygen sites are evidenced from 1D magic angle spinning (MAS) and 2D triple quantum MAS NMR experiments. They can be correlated with the three oxygen sites O1, O2 and O3 of the high-temperature crystal structure. The low-temperature phase is characterized by two distributed sites of type O1, which proves that the symmetry is lower than in the cubic high-temperature phase. Two-dimensional experiments show that there is no dynamic exchange process, on the NMR time-scale, between the different oxygen sites at room temperature, which agrees well with conductivity results.

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Section: Discussionsupporting

confidence: 79%

17O NMR in room temperature phase of La2Mo2O9 fast oxide ionic conductor

et al. 2005

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“…The results are again surpassed by the result of Zha et al and especially Eguchi et al for Sm‐doped ceria. Still, the highest total conductivity is reported for Ce 0.9 Gd 0.1 O 1.95 by Steele . This behavior may be related to the influence of the grain boundary contribution on the total conductivity as shown by Steele .…”

Section: Resultsmentioning

confidence: 98%

The ionic conductivity of Sm‐doped ceria

Koettgen

Martin

2020

J Am Ceram Soc

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The oxygen ion conductivity of polycrystalline samples of Sm‐doped ceria and of Gd‐doped ceria is studied as a function of doping fraction and temperature using impedance spectroscopy allowing the separation of bulk and grain boundary conductivity. The introduction of a fine spacing for the Sm dopant fraction allows the clear identification of the dopant fraction leading to the largest bulk conductivity. At 267°C, the largest bulk conductivity is shown for Ce0.93Sm0.07O1.965. With increasing temperature, indications of an increase in the dopant fraction, which leads to the maximum in conductivity, are found. For the grain boundary conductivity, the maximum appears at larger dopant fractions compared to the bulk conductivity. The largest total conductivity for both dopants is again found for Sm‐doped ceria. In literature, different syntheses and sample preparation methods led to larger total conductivities for Gd‐doped ceria. In this work, we demonstrate that the variation of sintering conditions leads to scattering in the conductivity over one order of magnitude. Finally, we demonstrate that, in nominally pure cerium oxide, impurities dominate the ionic conductivity.

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“…The stability regime is significantly higher for doped-ceria in comparison with pure ceria, however, these systems also develop electronic conductivity at oxygen partial pressures much higher than those experienced at the fuel electrode of the solid oxide fuel cell. For more stable doped-ceria systems (Sm203 and Gd203), the lower oxygen partial pressure range is about 10 -8 atm at 1000 ~ and 10 -12 atm at 800 ~ [78,79] below which the material develops substantial electronic conductivity. Open circuit voltage measurements in fuel cells using ceria-based electrolytes produce voltages which are 20 -40 % below the theoretical values [80].…”

Section: Phase Assemblage and Stabilitymentioning

confidence: 99%

Oxygen-ion conducting electrolyte materials for solid oxide fuel cells

Badwal

Ciacchi

2000

Ionics

157

142

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Abstract. Oxygen-ion conducting solid electrolyte systems have been reviewed with specific emphasis on their use in solid oxide fuel cells. The relationships between phase assemblage, electrolyte stability and ionic conductivity have been discussed. The role of parameters such as sintering temperature and atmosphere which influence the segregation of impurities, present in the starting ceramic powders, at grain boundaries and at the external surface of the electrolyte compacts has been emphasised. The stability of various electrolyte materials in contact with other fuel cell components and in fuel environments has been discussed in detail. The ageing behaviour at fuel cell operating temperatures has been described. Data on ionic conductivity, mechanical and thermal properties have been presented for a number of electrolyte materials.

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Oxygen Ion Conductors

Cited by 78 publications

References 15 publications

17O NMR in room temperature phase of La2Mo2O9 fast oxide ionic conductor

17O NMR in room temperature phase of La2Mo2O9 fast oxide ionic conductor

The ionic conductivity of Sm‐doped ceria

Oxygen-ion conducting electrolyte materials for solid oxide fuel cells

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