Transport properties of yttrium-doped zirconia-Influence of kinetic demixing

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

doi:10.1016/j.ssi.2006.10.016

Cited by 12 publications

(6 citation statements)

References 16 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: 84%

“…The electrical conductivity was characterized by complex impedance spectroscopy [2,6] using silver as an electrode material (σ=g/R, where g=l/s). In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…To explain these results, it is important to take into account the occurrence of kinetic demixing phenomena during the sintering process [2,6]. The X-ray photoelectron spectroscopy (XPS) analyses results reported in Table 1 show the influence of the grain size, of the amount of Gd, and of the cooling rate at the end of sintering on the amount of Gd segregated at the periphery of the grains (depth close to 0.2 nm).…”

Section: Discussionmentioning

confidence: 99%

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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: 84%

“…The electrical conductivity was characterized by complex impedance spectroscopy [2,6] using silver as an electrode material (σ=g/R, where g=l/s). In Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Surblé¹,

Baldinozzi²,

Dollé³

et al. 2007

Ionics

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“…For instance, in what is considered as the standard solid oxide electrolyte, yttria stabilised zirconia (YSZ), substantial yttrium segregation is observed simply by cooling down the sample. 24, 25 Besides, according to the yttria-zirconia phase diagram, cubic YSZ should also be considered as a metastable phase at room temperature. 1 It is therefore likely that metastability and counterion segregation are current phenomena in oxide-ion conductors.…”

Section: Discussionmentioning

confidence: 99%

Thermal stability of alkali and alkaline-earth substituted LAMOX oxide-ion conductors

et al. 2010

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The high temperature demixing/recombination phenomenon previously observed in Ca-substituted La(2)Mo(2)O(9) oxide ion conductors [A. Selmi et al., Solid State Ionics, 2006, 177, 3051; Eur. J. Inorg. Chem., 2008, 1813] has been visualised using scanning electron microscopy and EDX analysis. The demixed state appears as CaMoO(4) straight solid streams erupted from pores within LAMOX grains. The thermal stability study is extended to other alkali and alkaline-earth substituted LAMOX compounds, all of which are shown, in temperature-controlled X-ray diffractograms, to present similar demixing/recombination processes. The most spectacular effect is observed in La(1.88)K(0.12)Mo(0.6)W(1.4)O(8.88) where demixing takes the form of a total decomposition, before full recombination at a higher temperature. Such a phenomenon is interpreted as originating from temperature-dependent solid solution limits with higher substitutional ranges at higher temperatures. It results in the metastabilisation of pure phases by quenching (or rapid cooling), whereas the stable state is demixed, as shown on slowly cooled samples.

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“…Both instabilities are somewhat reminiscent of what is observed in oxides with high concentration of point defects such as aliovalently substituted zirconias. 9,10 In thermodynamically stable β-LAMOX however, the evolution of conductivity upon heating exhibits, above 400-450 °C, a deviation from a conventional Arrhenius-type behavior in concordance with an increase of cell volume compared to its linear expansion at lower temperature. 8,11 Above 450 °C, the conductivity curve can be satisfactorily fitted with a Vogel-Tammann-Fulcher (VTF) model.…”

Section: Introductionmentioning

confidence: 98%

Structural Key of the Thermal Expansion and the Oxide Ionic Conduction in Derivatives of La₂Mo₂O₉: a Temperature-Controlled Neutron Diffraction Study of β-La_1.7Bi_0.3Mo₂O₉

2011

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A thorough temperature-controlled powder neutron diffraction study was carried out on a Bi-substituted LAMOX (derivatives of La2Mo2O9) oxide ion conductor β-La1.7Bi0.3Mo2O9. It allowed us to identify the subtle structural distortions at the origin of, or correlated to, the peculiarities of the ionic conduction process, which were misinterpreted in previous studies on related compounds. The main distortions concern the morphology of the anti-tetrahedral building units of the cationic framework hosting conducting anions, rather than the tilt/rotation of such units as previously postulated. An analysis of the ionic displacements and the temperature factors within these [O1(La,Bi)3Mo] units upon heating suggests that the successive expansions of [(La,Bi)3] and [(La,Bi)2Mo] triangular faces enables some O1 oxide ions to escape from their initial position toward partially occupied O2 and O3 sites, respectively. The increase of ionic conductivity/mobility observed above about 450 °C and ascribed to a transition toward a Vogel−Tammann−Fulcher (VTF)-type assisted transport regime would consequently be due to the opening up of new conduction paths rather than to an intrinsic increase in mobility of O2 and O3 ions on their low temperature conduction paths.

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Transport properties of yttrium-doped zirconia-Influence of kinetic demixing

Cited by 12 publications

References 16 publications

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Thermal stability of alkali and alkaline-earth substituted LAMOX oxide-ion conductors

Structural Key of the Thermal Expansion and the Oxide Ionic Conduction in Derivatives of La₂Mo₂O₉: a Temperature-Controlled Neutron Diffraction Study of β-La_1.7Bi_0.3Mo₂O₉

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Transport properties of yttrium-doped zirconia-Influence of kinetic demixing

Cited by 12 publications

References 16 publications

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria

Thermal stability of alkali and alkaline-earth substituted LAMOX oxide-ion conductors

Structural Key of the Thermal Expansion and the Oxide Ionic Conduction in Derivatives of La2Mo2O9: a Temperature-Controlled Neutron Diffraction Study of β-La1.7Bi0.3Mo2O9

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Structural Key of the Thermal Expansion and the Oxide Ionic Conduction in Derivatives of La₂Mo₂O₉: a Temperature-Controlled Neutron Diffraction Study of β-La_1.7Bi_0.3Mo₂O₉