Kinetic demixing and grain boundary conductivity of yttria-doped zirconia part I - experimental observations

Rizea, A.; Petot, C.; Petot-Ervas, G.; Graham, M. J.; Sproule, G. I.

doi:10.1007/bf02375469

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…As already observed in previous studies [3][4][5][6], the kinetic demixing effects are less pronounced when the grain size decreases. It is also interesting to notice ( Table 1) that whatever the nominal amount of dopant in the sample, for a given grain size, a close Gd enrichment in the first monolayers is observed (P6, P8, P9).…”

Section: Discussionsupporting

confidence: 68%

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Surblé¹,

Baldinozzi²,

Dollé³

et al. 2007

Ionics

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Nanocrystalline CeO 2 -doped (5, 7.5, 10, and 15 mol%) Gd 2 O 3 powders, with a particle size of about 17 nm, were synthesized through the combustion of glycine/ nitrate gels. Dense nanocrystalline materials were obtained by hot uniaxial sintering. Optical microscopy, scanning electron microscopy and transmission electron microscopy examinations, as well as X-ray diffraction analyses, have allowed us to characterize these polycrystals. The grain sizes, included between ∼10 and 80 nm, depend on both the sintering temperature and the amount of dopant. A comparison of the transport properties of these nanocrystalline samples to the values obtained with coarsened grained materials of same composition shows that the ionic conductivity passes through a maximum for mean grain sizes included between 300 and 500 nm. Furthermore, an enhancement of the ionic conductivity is observed when the amount of dopant increases. This was attributed to a grain-size-dependent gadolinium segregation at the periphery of the grains confirmed by X-ray photoelectron spectroscopy characterizations.

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Section: Discussionsupporting

confidence: 68%

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Surblé¹,

Baldinozzi²,

Dollé³

et al. 2007

Ionics

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“…This type of segregation is an intrinsic material property and will lead to the enrichment of the acceptor cations at the periphery of the grains. On the other hand, nonequilibrium segregation is kinetic-dependent and is governed by the nature of the thermal treatment given to the sample. , This nonequilibrium segregation can result in the nonuniform distribution of dopant cations, which will affect the extent of local oxygen vacancy ordering and consequently the conductivity. In the present work, all of the samples were subjected to a similar sintering temperature profile.…”

Section: Resultsmentioning

confidence: 99%

Long-Term Conductivity Stability of Metastable Tetragonal Phases in 1Yb₂O₃–xSc₂O₃–(99 – x)ZrO₂ (x = 7, 8 mol %)

et al. 2020

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The present work studies the influence of 1 mol % Yb 2 O 3 codoping on the long-term conductivity stability in the metastable tetragonal phases present in 8−9 mol % Sc 2 O 3 −ZrO 2 . Dense polycrystalline samples are synthesized via conventional solid-state reaction and pressureless sintering methods. The 8 mol % dopant containing ZrO 2 compositions contain the metastable t′phase, while the t″-phase exists in the 9 mol % doped compositions. However, the grain conductivity values in all of the compositions are comparable and insensitive to the type of tetragonal phase present in the samples. The total conductivity follows a similar trend except in the 1Yb 2 O 3 −8Sc 2 O 3 −91ZrO 2 specimen, which shows a low total conductivity because of the resistive grain boundaries. Long-term thermal aging is performed on all of the tested samples at 650 °C for 2000 h in air. The in situ conductivity study suggests that the conductivity declines occur primarily in the first 650 h. The total conductivity loss at 650 °C is higher in the t′-phase (∼10−16%) compared to the t″-phase (∼3%). Even though substituting 1 mol % Yb 2 O 3 (for Sc 2 O 3 ) is beneficial in reducing the % conductivity degradation from 16 to 10% in 8Sc 2 O 3 − 92ZrO 2 , it does not affect the long-term conductivity stability in 9Sc 2 O 3 −91ZrO 2 (∼3%). Thus, the 9Sc 2 O 3 −91ZrO 2 composition exhibits excellent temporal stability of oxygen-ion conductivity with the magnitude of 20.4 mS•cm −1 after 2000 h aging at 650 °C in air.

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“…6). The electrical conductivity was characterized by complex impedance spectroscopy [6,7,10], using silver as the electrode material.…”

Section: E X P E R I M E N T a L D E S C R I P T I O Nmentioning

confidence: 99%

Role of the microstructure on the transport properties of Y-doped zirconia and Gd-doped ceria

Petot-Ervas

Petot

Raulot

et al. 2003

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Abstract. Transmission electron microscopy characterizations and XPS analyses have allowed usto show the influence of the microstructure and nanochemistry on the transport properties of Y203-(9 mol%)-stabilized zirconia (YSZ) and Gd203 (10 mol%)-doped ceria (GDC). The grain boundary electrical conductivity (~gb) and oxygen diffusion coefficient (Do) of conventional YSZ ceramics increase with the grain size, while an opposite behavior was found for GDC samples. This difference was attributed to glassy precipitates present at YSZ grain boundaries. Furthermore, it was shown that kinetic demixing processes take place during cooling, at the end of sintering. This causes important changes in the cationic species distribution at interfaces and plays an important role on the transport properties of these two materials.

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Kinetic demixing and grain boundary conductivity of yttria-doped zirconia part I - experimental observations

Cited by 5 publications

References 19 publications

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Long-Term Conductivity Stability of Metastable Tetragonal Phases in 1Yb₂O₃–xSc₂O₃–(99 – x)ZrO₂ (x = 7, 8 mol %)

Role of the microstructure on the transport properties of Y-doped zirconia and Gd-doped ceria

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Kinetic demixing and grain boundary conductivity of yttria-doped zirconia part I - experimental observations

Cited by 5 publications

References 19 publications

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Long-Term Conductivity Stability of Metastable Tetragonal Phases in 1Yb2O3–xSc2O3–(99 – x)ZrO2 (x = 7, 8 mol %)

Role of the microstructure on the transport properties of Y-doped zirconia and Gd-doped ceria

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Long-Term Conductivity Stability of Metastable Tetragonal Phases in 1Yb₂O₃–xSc₂O₃–(99 – x)ZrO₂ (x = 7, 8 mol %)