Degradation of the electrical conductivity in stabilised zirconia systems

Haering, Christian; Roosen, Andreas; Schichl, H.

doi:10.1016/j.ssi.2004.07.038

Cited by 97 publications

(57 citation statements)

References 23 publications

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“…The stability of the conductivity is in agreement with results from Haering et al [9,11]. After 1800 h, shaded area in Fig.…”

Section: Resultssupporting

confidence: 90%

“…In addition, the increase of vacancies will create an electrostatic interaction between the oxygen vacancies and the dopant cations. This leads to an ordering of the cations during annealing causing the formation of anions microdomains, therefore causing conductivity degradation [9,11,15,16]. In Fig.7 grain boundaries are well defined and the hill and valley microstructure can be observed.…”

Section: Comparison Between Compositionsmentioning

confidence: 99%

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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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“…The stability of the conductivity is in agreement with results from Haering et al [9,11]. After 1800 h, shaded area in Fig.…”

Section: Resultssupporting

confidence: 90%

Section: Comparison Between Compositionsmentioning

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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“…At higher dopant levels, the defect associates have already reached a saturation point, so no further deleterious aging effects are noticed. 11 Appreciable increases in oxygen diffusion around 8YSZ and sharp decreases in oxygen diffusion with aging for concentrations Ͻ9 mol % yttria suggest that the diffusion rate is not a simple function of the number of available vacancies. determined to what extent it influences conduction degradation.…”

Section: Aged Yszmentioning

confidence: 99%

First-principles thermodynamic modeling of atomic ordering in yttria-stabilized zirconia

2010

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Yttria-stabilized zirconia ͑YSZ͒ is modeled using a cluster expansion statistical thermodynamics method built upon a density-functional theory database. The reliability of cluster expansions in predicting atomic ordering is explored by comparing with the extensive experimental database. The cluster expansion of YSZ is utilized in lattice Monte Carlo simulations to compute the ordering of dopant and oxygen vacancies as a function of concentration. Cation dopants show a strong tendency to aggregate and vacate significantly sized domains below 9 mol % Y 2 O 3 , which is likely important for YSZ aging processes in ionic conductivity. Evolution of vibrational and underlying electronic properties as a function of Y doping is explored.

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“…First, as shown in log Y vs log f , the CPE represents the power law dispersion, at high frequencies, with slope n, Figure 3c. Second, in plots of log C vs log f , the CPE contributes a power law dispersion of slope (n-1) at lower frequencies because C = Y /ω = Bω n−1 ; this is seen over the frequency range ∼10 4 -10 6 Hz in Figure 1d. In the analysis of high frequency data, it is essential that both CPE 1 and C 1 are included in the equivalent circuit.…”

mentioning

confidence: 91%

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

Vendrell

West

2018

J. Electrochem. Soc.

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Widely-used complex plane analysis of impedance data is insufficiently sensitive to characterize fully the bulk properties of YSZ single crystal. Instead, more extensive data analysis is needed which uses a combination of parallel, admittance-based formalisms and series, impedance-based formalisms. Bulk electrical properties are measured at higher frequencies and contain contributions from both long range conduction and local dielectric relaxation. At lower frequencies, electrode-sample contact impedances are measured and are included in full equivalent circuit analysis. The impedance of YSZ crystal of composition 8 mol% Y 2 O 3 in the (110) orientation, with Pt electrodes, was measured over the temperature range 150-750 • C and frequency range 0.01 Hz-3 MHz. Full data analysis required (i) a parallel constant phase element (CPE)-resistance (R) combination to model the electrode response, (ii) a series R-C element to represent local reorientation of defect dipoles and (iii) a R-C-CPE element to represent long range oxide-ion conduction; (ii) and (iii) together model the bulk response. The dielectric element underpins all discussions about defect structure and properties of YSZ but has not been included previously in analysis of impedance data. The new equivalent circuit that is proposed should allow better separation of bulk and grain boundary impedances of YSZ ceramics. Yttria-stabilized zirconia (YSZ) is a very well-known oxide ion conductor that is used as the solid electrolyte in solid oxide fuel cells and oxygen gas sensors.1-3 It usually takes the form of a high-density ceramic in which the bulk resistance in series with a grain boundary resistance gives the overall sample resistance. 4 In almost all cases, the grain boundary resistance is present and cannot be eliminated readily by attention to ceramic processing conditions. The nature of the grain boundary impedance is often unclear, although significant compositional differences from the bulk, associated with dopant segregation, may be involved. 5,6 In order to measure sample impedances, sample-electrode contacts are necessary and therefore, appropriate consideration of their associated impedances forms part of the overall impedance analysis. For YSZ, contact impedances include contributions from the blocking of oxide ions at the sample-electrode interface, charge transfer resistances associated with the O 2− /O 2 redox couple and the diffusion of O 2 molecules between the surrounding atmosphere and the sampleelectrode interface. Usually, electrode contact impedances are wellseparated on a frequency scale from bulk/grain boundary impedances because they have much higher associated capacitances, C: typically (1-10) × 10 −6 F for the electrode contact compared with ∼ 1 × 10 −10 F for a grain boundary capacitance and (2-3) × 10 −12 F for a bulk capacitance. Relaxation frequencies, ω, are given ideally by ωτ = 1, where τ = RC and therefore, the frequency maxima of impedance semicircles, arcs or peaks associated with bulk/grain boundary impedances are usuall...

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Degradation of the electrical conductivity in stabilised zirconia systems

Cited by 97 publications

References 23 publications

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

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

First-principles thermodynamic modeling of atomic ordering in yttria-stabilized zirconia

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

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