Solution of ill-posed problems in thermodynamics of phase equilibria. The Zro2 — Y2o3 system

Degtyarev, S. A.; Voronin, G. F.

doi:10.1016/0364-5916(88)90031-4

Cited by 22 publications

(11 citation statements)

References 7 publications

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“…Most experimental investigations on the t + c ↔ m + c transformation yield transition temperatures below 650°C, 47–52,54,55 independent of the purity of the materials and the preparation conditions. Calculated data on the ZrO 2 ‐rich region of the YSZ phase diagram predict a higher transition temperature above 1000°C, 56–60 but only sparse information is available to support a high transformation temperature. Two reasons are discussed to explain this discrepancy 56 : the first reason might be the low significance of the experimental data from treatments at temperatures below 1000°C because the cation diffusivity could be too low to achieve thermal equilibrium in finite time during the experiments.…”

Section: Discussionmentioning

confidence: 99%

“…Calculated data on the ZrO 2 ‐rich region of the YSZ phase diagram predict a higher transition temperature above 1000°C, 56–60 but only sparse information is available to support a high transformation temperature. Two reasons are discussed to explain this discrepancy 56 : the first reason might be the low significance of the experimental data from treatments at temperatures below 1000°C because the cation diffusivity could be too low to achieve thermal equilibrium in finite time during the experiments. The second reason could be related to the large errors caused by the extrapolation of high‐temperature thermodynamic properties of the solid solutions to the medium‐temperature region which are used in the calculations.…”

Section: Discussionmentioning

confidence: 99%

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Microstructure of Nanocrystalline Yttria‐Doped Zirconia Thin Films Obtained by Sol–Gel Processing

Butz

Störmer

Gerthsen

et al. 2008

Journal of the American Ceramic Society

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J Ernst Ruska-Centrum fu¨r Mikroskopie und Spektroskopie mit Elektronen, Forschungszentrum Ju¨lich, 52425 Ju¨lich, GermanyNano-and microcrystalline yttria-stabilized zirconia (YSZ) thin films with a dopant concentration of 8.370.3 mol% Y 2 O 3 were prepared with a variation in grain size by two orders of magnitude. A sol-gel-based method with consecutive rapid thermal annealing was applied to fabricate YSZ films, resulting in about 400 nm YSZ on sapphire substrates. The average grain sizes were varied between 5 nm and 0.5 lm by heat treatment in the temperature range of 6501-13501C for 24 h. High-resolution (HRTEM) and conventional transmission electron microscopy analyses confirmed specimens-irrespective of the thermal treatment-consisting of cubic (c-)ZrO 2 grains with nanoscaled tetragonal precipitates coherently embedded in the cubic matrix. Energy-dispersive X-ray spectroscopy and HRTEM on a large number of specimens yielded a homogeneous yttria concentration within the grains and at the grain boundaries with the absence of impurities, i.e. silica at the grain boundaries.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Microstructure of Nanocrystalline Yttria‐Doped Zirconia Thin Films Obtained by Sol–Gel Processing

Butz

Störmer

Gerthsen

et al. 2008

Journal of the American Ceramic Society

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“…For instance, Degtyarev and Voronin constructed such diagrams based on the calculated thermodynamic properties of all the phases. [38][39][40] This included the rhombohedral Zr 3 Y 4 O 12 phase, which transforms dystectoidically to cubic YSZ. Also, this diagram features an eutectoidic decomposition of tetragonal, as well as the cubic structure (into monoclinic YSZ and the ordered phase).…”

Section: Discussion Of Existing Phase Diagramsmentioning

confidence: 99%

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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“…The first thermodynamic assessment on the ZrO 2 -YO 1.5 system was conducted by Degtyarev and Voronin. [35] Their assessment was mainly based on few experimental data. Du [36] reassessed this system by using the simple substitution solution model for describing the various solid solutions and the liquid phase.…”

Section: A Binary Systemsmentioning

confidence: 99%

Thermodynamic Modeling of the ZrO2-YO1.5-TiO2 System

Wang

Dong

et al. 2010

Metall Mater Trans A

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The binary systems ZrO 2 -YO 1.5 , ZrO 2 -TiO 2 , and YO 1.5 -TiO 2 are reassessed, and a set of self-consistent thermodynamic parameters, which can be reliably extrapolated into the ZrO 2 -YO 1.5 -TiO 2 ternary system, are obtained. The substitutional solution model and the stoichiometric compound model are applied to the phase description in the ternary system, and the thermodynamic database of this ternary system is derived by the CALPHAD approach. It is noted that, except for the liquid phase, no ternary interaction parameters are introduced. The present evaluation can better describe the experimental phase diagrams reported recently at 1573 K, 1773 K, and 1873 K (1300°C, 1500°C, and 1600°C). Thus, the optimized thermodynamic parameters may be authentic and can be applied to optimizing the compositions of the novel materials based on this ternary system.

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Solution of ill-posed problems in thermodynamics of phase equilibria. The Zro2 — Y2o3 system

Cited by 22 publications

References 7 publications

Microstructure of Nanocrystalline Yttria‐Doped Zirconia Thin Films Obtained by Sol–Gel Processing

Microstructure of Nanocrystalline Yttria‐Doped Zirconia Thin Films Obtained by Sol–Gel Processing

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

Thermodynamic Modeling of the ZrO2-YO1.5-TiO2 System

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