Aging behavior and ionic conductivity of ceria-based ceramics: a comparative study

Zhang, T.S; Ma, Jie; Kong, Ling Bing; Chan, Siew Hwa; Kilner, John A.

doi:10.1016/j.ssi.2004.03.003

Cited by 192 publications

(205 citation statements)

References 23 publications

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“…10,12 As a result of the domain formation, the advantage of the dopant having an optimum radius disappears with increasing the doping level. As shown in a comparative study of Gd-and Y-doped ceria, 13 conductivities in the order of GdϾ Y and GdϽ Y were observed, respectively, at doping concentrations lower and higher than 20-25 at. %.…”

Section: Introductionmentioning

confidence: 82%

“…%. Zhang et al 13 suggested that this occurs because the ionic conduction in heavily doped ceria is dominated by the formation of nanosized domains, instead of being dominated by the dopant-oxygen vacancy association.…”

Section: Introductionmentioning

confidence: 99%

“…Despite this, it has been suspected that the negative impacts of domains on ionic conduction are partly related to its ordered structure, which may involve the local ordering of oxygen vacancies. [11][12][13] In cubic stabilized zirconia, a more familiar system, the local ordering of oxygen vacancies was also speculated, which has ordered structures depending on the composition ͑e.g., the dopant type and doping concentration͒ and the heat treatment. [14][15][16] Based on the study of x-ray diffraction, Welberry et al suggested that the local ordering in yttria-stabilized zirconia has a pyrochlorelike structure, in which the 1 2 ͗111͘ pairs of oxygen vacancies across cubes of oxygen anions containing the cations are allowed.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

et al. 2008

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Studies of electron energy loss spectroscopy and selected area electron diffraction ͑SAED͒ were systematically performed on 15 and 25 at. % lanthanide ͑Ln͒-doped ceria samples ͑Ln= Sm, Gd, Dy, and Yb͒, through which the local ordering of oxygen vacancies that develops with increase in doping level was confirmed in the sequence of ͑Gd, Sm͒ Ͼ DyϾ Yb. Furthermore, a monotone correlation between the development of the ordering and the degradation of ionic conductivity with increasing the doping concentration from 15 to 25 at. % was observed. Based on the analysis of SAED patterns, a structural model for the ordering of oxygen vacancies has been constructed, in which the arrangement of oxygen vacancies is similar to that in C-type Ln 2 O 3 oxides and the 1 2 ͗110͘ pairs of the vacancies are preferred. Then, the factors that can influence the formation of the ordering are discussed.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

et al. 2008

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“…Experimental data on the bulk conductivity of Ce 0.8 Gd 0.2 O 1.9 crystals were taken from Avila-Paredes [15], Mogensen [16], Christie [17] and Zhang [18]. Grain boundaries influence on the conductivity decreases with increasing temperature, and according to Zhang [19] total conductivity (marked as "(exp) Zhang, total" in Fig.5) is approximately equal to the bulk conductivity.…”

Section: Comparison Of Calculated Diffusion Coefficients With Experimmentioning

confidence: 99%

Influence of impurity-vacancy disorder on characteristics of gadolinium-doped ceria oxide: Molecular dynamics study

Kovalenko

Kupryazhkin

2013

Journal of Nuclear Materials

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By high-speed MD method using GPU the CGO nanocrystals of about 40,000 particles during about 0.1μs, in the temperature range (2500-700)K, were simulated. The influence of different dopant distributions on the nanocrystal characteristics, for two potentials sets, was investigated. For a given potentials set Gd distribution does not affect the lattice parameter and the anion diffusion coefficients. Five types of impurity vacancies were defined, by the Gd number in the nearest neighborhood, and temperature dependences were built. The formation energies of vacancies of all types were obtained.Calculated by the MD conductivity activation energy of 0.6eV acceptable coincides with the experimental 0.7eV, just as the absolute conductivity values.The supposition that helium in CGO ceramics dissolve in vacancies, surrounded only by cerium ions, was discussed. Analysis of the MD, conductivity measurements and helium defectoscopy shows that up to the melting temperature the vacancies are mainly associated with impurity ions.2

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“…This means that a change in the defect structure and nearest environment of the ions occurs. Zhang et al [8] state that there are four possible microstructural changes, which are responsible for the decrease in conductivity of doped zirconia electrolytes caused by ageing: (1) precipitation of long range ordered phases; (2) formation and precipitation of tetragonal phase in the cubic grains; (3) segregation of dopant-rich layer near grain boundaries and triple points and (4) trapping of oxygen vacancies ( ) towards dopant cations with time due to the Coulombic force, short range ordering of oxygen vacancies. In point (2) the formation and precipitation occur as a result of "growing" of the metastable tetragonal (t or t') or cubic phase in the ZrO 2 -Y 2 O 3 system and the t'-phase in the ZrO 2 -Sc 2 O 3 system into low-dopant tetragonal and dopant-rich cubic phases [7,9,10].…”

Section: Introductionmentioning

confidence: 99%

Characterisation of conductivity of the (Ce xY0.2-x)Sc0.6 Zr3.2O8-δ (0 < x < 0.2) system and composition Ce0.04Y0.02Sc0.67Zr3.27O 7.66 as function of time

Carvalho

Irvine

2012

Cerâmica

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EXPERIMENTALThe powders were prepared by a sol-gel combustion method [12]. Scandia powders (TTE Metals, 99.9% purity) were dissolved in nitric acid (Fisher Scientific, 70%) and hydrogen peroxide (Fisher Scientific, N30% wv). Separately, cerium (III) nitrate hexahydrate (Aldrich, 99% purity), AbstractThe conductivity behaviour of the (Ce x Y 0.2-x )Sc 0.6 Zr 3.2 O 8-d (0 ≤ x ≤ 0.2) system and composition Ce 0.04 Y 0.02 Sc 0.67 Zr 3.27 O 7.66 have been investigated as function of time using impedance spectroscopy. All samples were prepared by sol-gel and combustion process, sintered at 1500 °C for 12 h and the densities obtained were between 92 and 97%. The electrical measurements were performed at 600 °C. The conductivity values were fairly stable during the first 1800 h of the experiment but after this time the conductivity decreases. For some compositions of the system a semi-circle is detected through time, with capacitance values of an order of magnitude lower, 10 -8 F/cm. This semi-circle becomes well defined with time. After the experiment, SEM pictures show that grain boundary is well defined and an increase of pore inside grains, in some cases the surface is damaged showing cracks and fissures indicating microstructure deterioration. Keywords: scandia-zirconia, ac impedance, ageing. Resumo

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Aging behavior and ionic conductivity of ceria-based ceramics: a comparative study

Cited by 192 publications

References 23 publications

Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

Influence of impurity-vacancy disorder on characteristics of gadolinium-doped ceria oxide: Molecular dynamics study

Characterisation of conductivity of the (Ce xY0.2-x)Sc0.6 Zr3.2O8-δ (0 < x < 0.2) system and composition Ce0.04Y0.02Sc0.67Zr3.27O 7.66 as function of time

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