Ion irradiation-induced phase transformations in δ-γ-β phases of Sc 2O 3-ZrO 2 mixtures
Abstract
The purpose of this study is to investigate the role of stoichiometry in crystalline structure transformations in derivative fluorite compounds known as δ-γ-β phases in Sc 2O 3-ZrO 2 phase diagram. Different composition polycrystalline δ-Sc 4Zr 3O 12, γ-Sc 2Zr 5O 13 and β-Sc 2Zr 7O 17 samples were synthesized by mixing 40% Sc 2O 3 + 60% ZrO 2, 16.67% Sc 2O 3 + 83.33% ZrO 2, or 12.5% Sc 2O 3 + 87.5% ZrO 2, respectively. The pressed and polished pellets of these compounds were then irradiated under liquid nitrogen temperature with 200 keV Ne + ions at a dose rate of ∼1 × 10 12 ions/cm 2/s. An order-to-disorder (O-D) transformation was observed for all compositions, as determined using grazing incidence X-ray diffraction (GIXRD) at an incident angle of 0.25°. The O-D transformation threshold dose for δ-Sc 4Zr 3O 12 (∼0.2 dpa) was found to be noticeably higher than that for γ-Sc 2Zr 5O 13 and β-Sc 2Zr 7O 17 (∼0.04 dpa) based on both GIXRD and cross-sectional transmission electron microscopy (TEM) measurements. However, due to experimental difficulty and uncertainty, our GIXRD and TEM data were unable to conclusively confirm that the O-D transformation threshold dose for γ-Sc 2Zr 5O 13 is in fact slightly higher than that for β-Sc 2Zr 7O 17 as expected from the phase diagram of Sc 2O 3-ZrO 2 system.
- Publication:
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Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- February 2012
- DOI:
- 10.1016/j.nimb.2011.01.075
- Bibcode:
- 2012NIMPB.272..244Z