Ageing of solid electrolytes and electrode materials in electrochemical devices

Petot-Ervas, G.; Petot, C.

doi:10.1007/bf02375875

Cited by 12 publications

(21 citation statements)

References 19 publications

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“…When the sample is placed under a temperature gradient, one can assume, in agreement with both literature data [6] and our results obtained with semiconducting oxides and doped-alumina [8][9], that the flux of charged species "i" is due mainly to the driving force of the electrochemical potential gradient (Vrl3. If one neglects the correlation effects, the flux of charged species "i" may then be written, with respect to the laboratory reference frame, as:…”

Section: General Equationssupporting

confidence: 74%

“…In stabilized zirconia the prevailing defects are oxygen vacancies. Therefore, the cationic diffusion on the minority point defect sublattice is very low but cannot be neglected, as we have shown previously in the case of yttrium-doped zirconia samples placed under an applied electric field [7,8].…”

Section: Statement Of the Problem In The Case Of Stabilized Zirconiamentioning

confidence: 86%

“…AHf dlnT r'~eDe 4RT dz (8) This equation shows that the flux of oxygen ions occurs towards the side of the higher temperature if AHr > 0, or in the opposite direction, if AHf < 0. …”

Section: Transport Processes In the Oxygenmentioning

confidence: 96%

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Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

Ruello

Rizea

Petot

et al. 2001

Ionics

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Abstract. This paper presents a formal analysis of the transport processes in yttria-doped zirconia under a temperature gradient. Due to the simultaneous diffusion and drift of the species when the material is exposed to a thermodynamical potential gradient, a kinetic demixing process appears on the cationic sublattice if the diffusion coefficients of the cations are different. Experimental results obtained with yttria-doped zirconia are discussed on the basis of this analysis. They confirm that kinetic demixing processes during cooling must be taken into account in the interpretation of the grain boundary conductivity of doped zirconia. IntroductionXPS analysis [1] shows a near surface enrichment of silicon and yttrium in yttria-doped zirconia lower in air quenched materials than in samples cooled at 25 K/h. These observations are consistent with those of Aoki et al. [2], for calcium and silicon in calcium-doped zirconia. However, while Aoki et al. suggest that these cation redistributions are likely confined to a layer near the interfaces close or lower than 5 nm, we have observed that the segregation layer thickness is higher than the depth of the space charge region and depends on the cooling rate of the sample after sintering, indicating that cation redistributions occur during cooling. The purpose of this paper is then to provide an analysis of the kinetic demixing phenomena in oxide solid electrolytes, in order to be able to control such effects in materials in which the minority defects are present on the cationic sublattice.

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Section: General Equationssupporting

confidence: 74%

Section: Statement Of the Problem In The Case Of Stabilized Zirconiamentioning

confidence: 86%

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Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

Ruello

Rizea

Petot

et al. 2001

Ionics

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“…Under working conditions, these materials are often exposed to external forces causing both reactions and transport within the materials. Prominent examples are electromigration or kinetic demixing in electric fields [1][2][3][4][5], kinetic demixing in chemical potential gradients [6][7][8][9], stress-driven segregation [10,11] or thermodiffusion ( [12][13][14][15][16][17][18][19][20], see [21,22] for reviews).…”

Section: Introductionmentioning

confidence: 99%

On the Soret effect in binary nonstoichiometric oxides—kinetic demixing of cuprite in a temperature gradient

Timm

Janek

2005

Solid State Ionics

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The Soret effect in nonstoichiometric copper(I)-oxide (cuprite, Cu 2Àd O) has been studied experimentally by means of non-isothermal solid state galvanic cells (thermocells) under different boundary conditions. At high temperatures and high oxygen activities, copper metal migrates down the temperature gradient and a gradient in the nonstoichiometry is established under stationary conditions. The heat of transport of copper metal is determined as Q* Cu c180 kJ/mol at a temperature of 1000 8C and at an oxygen activity of log a O 2 =À2.95. This result agrees with recent theoretical simulations of the heat of transport of atoms migrating via a vacancy mechanism. These predict a positive sign of the heat of transport and a considerably larger value than the activation energy for the atomic jumps. D

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“…Although, cation diffusivities are normally several orders of magnitude lower than that of oxygen ions [21], at sufficiently long times, high temperatures [22], and electric fields [23][24][25], substantial cation migration may still occur. Note that the migration of the different cations are not identical; certain elements migrate faster, others slower [26].…”

Section: Discussionmentioning

confidence: 99%

Operational Inhomogeneities in La_0.9Sr_0.1Ga_0.8Mg_0.2O_3–δ Electrolytes and La_0.8Sr_0.2Cr_0.82Ru_0.18O_3–δ–Ce_0.9Gd_0.1O_2–δ Composite Anodes for Solid Oxide Fuel Cells

et al. 2011

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The electrolyte/anode interface in solid oxide fuel cells with La0.9Sr0.1Ga0.8Mg0.2O3–δ electrolytes and composite anodes containing La0.8Sr0.2Cr0.82Ru0.18O3–δ and Ce0.9Gd0.1O2–δ (GDC) was studied using transmission electron microscope Z‐contrast imaging and energy dispersive X‐ray spectroscopy. The anode/electrolyte interface of an operated cell had numerous defective regions in the electrolyte, immediately adjacent to anode GDC particles. These areas had a different chemical composition than other electrolyte regions and were crystallographically inhomogeneous. These regions were not observed in a cell reduced in hydrogen that was not operated, suggesting that they were the result of combined electrical and chemical potential gradients present during cell operation. Ru nanoparticles were observed on the chromite surfaces of the operated.

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Ageing of solid electrolytes and electrode materials in electrochemical devices

Cited by 12 publications

References 19 publications

Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

On the Soret effect in binary nonstoichiometric oxides—kinetic demixing of cuprite in a temperature gradient

Operational Inhomogeneities in La_0.9Sr_0.1Ga_0.8Mg_0.2O_3–δ Electrolytes and La_0.8Sr_0.2Cr_0.82Ru_0.18O_3–δ–Ce_0.9Gd_0.1O_2–δ Composite Anodes for Solid Oxide Fuel Cells

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Ageing of solid electrolytes and electrode materials in electrochemical devices

Cited by 12 publications

References 19 publications

Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

Kinetic demixing in yttria-doped zirconia part II - theoretical analysis

On the Soret effect in binary nonstoichiometric oxides—kinetic demixing of cuprite in a temperature gradient

Operational Inhomogeneities in La0.9Sr0.1Ga0.8Mg0.2O3–δ Electrolytes and La0.8Sr0.2Cr0.82Ru0.18O3–δ–Ce0.9Gd0.1O2–δ Composite Anodes for Solid Oxide Fuel Cells

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Operational Inhomogeneities in La_0.9Sr_0.1Ga_0.8Mg_0.2O_3–δ Electrolytes and La_0.8Sr_0.2Cr_0.82Ru_0.18O_3–δ–Ce_0.9Gd_0.1O_2–δ Composite Anodes for Solid Oxide Fuel Cells