Subsolidus Phase Equilibria and Ordering in the System ZrO2‐Y2O3

Pascual, C.; Durán, P.

doi:10.1111/j.1151-2916.1983.tb09961.x

Cited by 219 publications

(68 citation statements)

References 16 publications

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“…Their version of the phase diagram also contains the peritectoidically transforming Zr 3 Y 4 O 12 phase, again at 40 mol%. In the diagram published by Pascual and Duran, 33 on the other hand, this ordered phase would transform dystectoidically into cubic YSZ at 1375…”

Section: Discussion Of Existing Phase Diagramsmentioning

confidence: 98%

From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

et al. 2016

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Yttria-stabilized zirconia (YSZ) thin films with varying composition between 3 mol% and 40 mol% have been prepared by direct-current ion beam sputtering at a substrate temperature of 300 °C, with ideal transfer of the stoichiometry from the target to the thin film and a high degree of homogeneity, as determined by X-ray photoelectron and energy-dispersive X-ray spectroscopy. The films were analyzed using transmission electron microscopy, revealing that, while the films with 8 mol% and 20 mol% yttria retain their crystal structure from the bulk compound (tetragonal and cubic, respectively), those with 3 mol% and 40 mol% Y2O3 undergo a phase transition upon sputtering (from a tetragonal/monoclinic mixture to purely tetragonal YSZ, and from a rhombohedral structure to a cubic one, respectively). Selected area electron diffraction shows a strong texturing for the three samples with lower yttria-content, while the one with 40 mol% Y2O3 is fully disordered, owing to the phase transition. Additionally, AFM topology images show somewhat similar structures up to 20 mol% yttria, while the specimen with the highest amount of dopant features a lower roughness. In order to facilitate the discussion of the phases present for each sample, a thorough review of previously published phase diagrams is presented.

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Section: Discussion Of Existing Phase Diagramsmentioning

confidence: 98%

From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

et al. 2016

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“…Lattice parameters were calculated Table I and show a slight increase for increasing dopant concentration, in accordance with literature. 6,56,57 For conductivity measurements on single crystals, Pt paste was painted onto the two sides and annealed at 1000…”

Section: Methodsmentioning

confidence: 99%

Revisiting the Temperature Dependent Ionic Conductivity of Yttria Stabilized Zirconia (YSZ)

Ahamer

Opitz

Rupp

et al. 2017

J. Electrochem. Soc.

124

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The temperature dependent conductivity of yttria stabilized zirconia (YSZ) exhibits a bending in Arrhenius' plots which is frequently discussed in terms of free and associated oxygen vacancies. However, the very high doping concentration in YSZ leads to such a strong defect interaction that the concept of free vacancies becomes highly questionable. Therefore, the temperature dependent conductivity of YSZ is reconsidered. The conductivity of YSZ with different doping concentration was measured in a broad temperature range. The data are analyzed in terms of two different barrier heights that have to be passed along an average path of an oxygen vacancy in YSZ (two barrier model). For 8-10 mol% yttria, the two barriers are in the range of 0.6 eV and 1.1-1.2 eV, respectively. The conductivity and thus the barrier heights also depend on the cooling rate after a high temperature pre-treatment. This indicates that different frozen-in distributions of dopants affect the vacancy motion by different energy landscapes. Temporarily existing defect configurations, possibly with a strong effect of repulsive oxygen vacancy interaction, are suggested as the reason of high barriers. Future dynamic ab-initio calculations may reveal whether this modified model of the YSZ conductivity is mechanistically meaningful. Yttria stabilized zirconia (YSZ) is among the most important ion conducting solids and acts as a kind of model material representing fast oxide ion conductors. Owing to this model character of YSZ, but also due to its application in solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs) and oxygen sensors, a vast amount of papers can be found dealing with its oxide ion conduction. The ionic conductivity is based on the motion of oxygen vacancies, introduced by Y 3+ ions replacing Zr 4+ . For concentrations above ca. 8 mol%, yttria doping also stabilizes the cubic structure down to room temperature. A detailed review of the science of YSZ and related materials is far beyond the scope of this paper but a few important facts regarding the ionic conductivity of zirconia-based solid electrolytes can be briefly summarized as follows:1-9 i) Doping concentrations above ca. 8 mol% Y 2 O 3 lead to a decrease of the conductivity, despite increasing oxygen vacancy concentration. ii) The conductivity not only depends on the vacancy concentration but also on the kind of dopant. For example, Sc-doped zirconia shows significantly higher conductivity than YSZ. iii) The temperature dependence of the conductivity cannot be described by a single activation energy (E act ) but shows higher E act values at lower temperatures.Numerous theoretical studies were performed in order to understand these experimental observations and to get a deeper insight into defect thermodynamics and kinetics of doped zirconia and of the closely related ceria-based ion conductors, see e.g. Refs. 10-29. Those model studies employed different simulation approaches such as molecular dynamics (MD), density functional theory (DFT) and kinetic Monte Carl...

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“…7YSZ has high tetragonal phase stability [15,50,51]. However, epitaxial growth readily occurred for tetragonal 7YSZ splats on cubic 18YSZ substrate for all deposition temperatures, as shown in Fig.…”

Section: Special Epitaxial Growthmentioning

confidence: 88%

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

Chen

Yang

2017

J Adv Ceram

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Thermally sprayed coatings are essentially layered materials and contain large numbers of lamellar pores. It is thus quite necessary to clarify the formation mechanism of lamellar pores which significantly influence coating performances. In the present study, to elaborate the formation mechanism of lamellar pores, the yttria-stabilized zirconia (ZrO 2 -7 wt% Y 2 O 3 , 7YSZ) splats, which have high fracture toughness and tetragonal phase stability, were employed. Interestingly, anomalous epitaxial growth occurred for all deposition temperatures in spite of the extremely high cooling rate, which clearly indicated chemical bonding and complete contact at splat/substrate interface before splat cooling. However, transverse spallation substantially occurred for all deposition temperatures in spite of the high fracture toughness of 7YSZ, which revealed that the lamellar pores were from transverse cracking/spallation due to the large stress during splat cooling. Additionally, fracture mechanics analysis was carried out, and it was found that the stress arose from the constraint effect of the shrinkage of the splat by locally heated substrate with the value about 1.97 GPa. This clearly demonstrated that the stress was indeed large enough to drive transverse cracking/spallation forming lamellar pores during splat cooling. All of these contribute to understanding the essential features of lamellar bonding and further tailoring the coating structures and performance.

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Subsolidus Phase Equilibria and Ordering in the System ZrO₂‐Y₂O₃

Cited by 219 publications

References 16 publications

From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

Revisiting the Temperature Dependent Ionic Conductivity of Yttria Stabilized Zirconia (YSZ)

Epitaxial growth and cracking of highly tough 7YSZ splats by thermal spray technology

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