The temperature dependence of the critical dose for amorphization, using 0.6 MeV Bi+ ions, for A2Ti2O7 pyrochlores, in which A=Y, Sm, Gd and Lu, exhibits no significant effect of A-site ion mass or size. The room temperature dose for amorphization was found to be ~ 0.18 dpa in each case. After irradiation with 2 MeV Au2? ions glancing-incidence XRD revealed that each pyrochlore underwent an irradiation-induced structural transformation to fluorite in conjunction with amorphization. The effect of amorphization on the dissolution rates of fully dense pyrochlores, at 90oC and pH 2 (nitric acid) varied from a factor of 10-15 increase for Gd2Ti2O7 to none for Y2Ti2O7. Significant differences were observed in the A-site dissolution rates from the crystalline pyrochlores, indicating differences in the manner in which the A-site cations are incorporated into the pyrochlore structure. These indications were supported by Raman spectroscopy.
Revised: May 27, 2004 |
Published: February 5, 2001
Citation
Begg B.D., N.J. Hess, W.J. Weber, R. Devanathan, J.P. Icenhower, S. Thevuthasan, and B.P. McGrail. 2001.Heavy-Ion Irradiation Effects on Structures and Acid Dissolution of Pyrochlores.Journal of Nuclear Materials 288, no. 2-3:208-216.PNNL-SA-32958.