DAMAGE ACCUMULATION IN MgAl_2O_4 AND YTTRIA-STABILIZED ZrO_2 BY Xe-ION IRRADIATION

摘要

Magnesium-aluminate spinel (MAS) and yttria-stabilized zirconia (YSZ) are being considered for use as ceramic matrices in proliferation resistant fuels and radioactive storage systems, and may be used either as individual entities or as constituents in multicomponent ceramic systems. It is worthwhile, therefore, to compare radiation damage in these two potentially important materials when subjected to similar irradiation conditions, e.g., ion beam irradiation. To compare radiation damage properties of these two materials, single crystals of spinel and zirconia were irradiated with 340 keV Xe~(++) ions at 120 K, and subsequently investigated by Rutherford backscattering and ion channeling (RBS/C), and optical absorption spectroscopy. Results indicate that damage accumulation in both spine and zirconia follow a three stage process: 1) very slow damage accumulation over a wide range of dose; 2) rapid changes in damage over a range of doses from about 0.25 to 25 displacements per atom (dpa); 3) slower damage accumulation at very high doses and possibly saturation. Optical absorption results indicate that F-centers form in Xe ion-irradiated spinel and that the concentration of these centers saturates at high dose. Absorption bands are also formed in both spinel and zirconia that are due to point defect complexes formed upon irradiation. These bands increase in intensity with increasing Xe dose, and, in the case of zirconia, without saturation. Finally the rate of change in intensity of these bands with increasing Xe dose, mimic the changes in damage observed by RBS/C with increasing dose.