Effects of firing schedule on solubility limits and transport properties of ZrO{sub 2}-TiO{sub 2}-Y{sub 2}O{sub 3} fluorites

Journal Article · Wed Aug 15 04:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.06.016· OSTI ID:21043817

Frade, J R ^[1]; Mogensen, M ^[2]; Irvine, J T.S. ^[3]

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1. Aveiro University, Aveiro (Portugal)
2. Riso National Laboratory, Roskilde (Denmark)
3. St. Andrews University, St. Andrews, Fife, Scotland (United Kingdom)

The low Y/high Zr edge of the cubic defect fluorite solid solution in the system ZrO{sub 2}-TiO{sub 2}-Y{sub 2}O{sub 3} in air is reassessed, as it is these compositions which have been suggested to offer the highest levels of mixed conductivity. Vegard's law is obeyed for values of x which lie within the cubic defect fluorite phase in Zr{sub 1-x-y}Y{sub y}Ti{sub x}O{sub 2-{delta}} for values of y=0.2 and 0.25. Measured lattice parameters show good agreement with those calculated from the Kim relation. Deviation from Vegard's law places the limit of the solid solution at x=0.18 and 0.20 for values of y=0.2 and 0.25, respectively, at 1500 deg. C. Discrepancies in current literature data can be shown to be due to differences in firing schedule such as slight temperature fluctuations and/or different cooling rates. A high level of care of sintering temperature and cooling profile is essential to form the most promising single-phase materials which contain maximum Ti-contents with low Y-contents. Contraction of the phase limit as a result of poor synthesis control leads to erroneously high values of bulk ionic conductivity while values of electronic conductivity are shown to be less affected. - Graphical abstract: The composition dependence of lattice parameter for compositions containing 20 mol% YO{sub 1.5} as a function of Ti-content in the system ZrO{sub 2}-TiO{sub 2}-YO{sub 1.5} showing contraction of the cubic defect fluorite-phase field upon slight temperature fluctuations or slow cooling rates.

• OSTI ID: 21043817
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 8 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AIR
COOLING
CRYSTAL DEFECTS
FLUORITE
IONIC CONDUCTIVITY
LATTICE PARAMETERS
SINTERING
SOLID SOLUTIONS
SOLUBILITY
SYNTHESIS
TEMPERATURE RANGE 1000-4000 K
TITANIUM OXIDES
VEGARD LAW
YTTRIUM OXIDES
ZIRCONIUM OXIDES