High-Pressure Phase Transitions in Zirconia and Yttria-Doped Zirconia |
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Authors: | B. ALZYAB C. H. PERRY R. P. INGEL |
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Affiliation: | Physics Department. Northeastern University, Boston, Massachusetts 02115;Naval Research Laboratories, Washington, D. C. 20375 |
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Abstract: | Raman spectroscopy has been utilized to characterize the phase transformations and transition pressures in pure and doped zirconia containing 3, 4, and 5 wt% Y2O3. The pressure-induced transformations were investigated to over 6 GPa (at room temperature) using a diamond anvil pressure cell. Pure zirconia single-crystal samples transformed to a "new" tetragonal phase (different from the one obtained at high temperatures at atmospheric pressure) at about 4 GPa. The pressure transformation, like the temperature transition, was reversible and exhibited an approximately 0.45-GPa hysteresis at room temperature. The 3 and 4 wt% Y2O3 crystals underwent a monoclinic ( P 21/b) to tetragonal ( P 42 nmc) phase transition similar to that observed at high temperatures. This phase change was found to be irreversible on releasing the pressure. The 5 wt% Y2O3 at atmospheric pressure consists of a tetragonal modification in a disordered cubic matrix; a gradual, but reversible, disordering transformation of the tetragonal precipitate takes place with pressure. |
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