Effect of dopants on zirconia stabilization -- an x-ray absorption study: 1, Trivalent dopants
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemistry
Local atomic structures of Zr and dopant cations in zirconia solid solutions with Fe{sub 2}O{sub 3}, Ga{sub 2}O{sub 3}, Y{sub 2}O{sub 3}, and Gd{sub 2}O{sub 3} have been determined. The Zr ions in both partially stabilized tetragonal and fully stabilized cubic zirconia have their own characteristic structures which are dopant-independent. The dopant cations substitute for Zr ions despite severe local distortions necessitated by the large difference in dopant-O distance and Zr-O distance. Dopant ionic size determines the preferred locations of oxygen vacancies. Vacancies introduced by oversized dopants (Y and Gd) are located as nearest neighbors to Zr atoms, leaving 8-fold oxygen coordination to dopant cations. Undersized dopants (Fe and Ga) compete with Zr ions for the oxygen vacancies in zirconia, resulting in 6-fold oxygen coordination and a large disturbance to the surrounding next nearest neighbors. Since oxygen vacancies associated with Zr can provide stability for tetragonal and cubic zirconia, these results suggest an explanation for the observation that oversized trivalent dopants are more effective than undersized trivalent dopants in stabilizing cubic and tetragonal phases.
- OSTI ID:
- 142241
- Journal Information:
- Journal of the American Ceramic Society, Vol. 77, Issue 1; Other Information: PBD: Jan 1994
- Country of Publication:
- United States
- Language:
- English
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