RADIATION-RESISTANCE OF THE OXIDE SPINEL - THE ROLE OF STOICHIOMETRY ON DAMAGE RESPONSE

Stoichiometric and non-stoichiometric magnesio-aluminate spinel single crystals (compositions MgO . Al2O3 and MgO . 3Al(2)O(3), respectively ) were irradiated with both 400 keV and 1.5 MeV Xe ions under cryogeni c and room temperature conditions, in order to compare the irradiation damage response of these isostructural compounds. Overall, stoichiome tric spinel was found to be more resistant to irradiation damage (micr ostructural alterations) than the non-stoichiometric compound. At room temperature, non-stoichiometric spinel transforms to a metastable cry stalline structure at an ion dose representing 1 to 2 displacements pe r atom (dpa), while this transformation is not observed in stoichiomet ric spinel to a dose of 10 dpa. Furthermore, under cryogenic condition s, both stoichiometric and non-stoichiometric spinel undergo a metasta ble phase transformation, followed by a transformation to an aperiodic structure, and they do so at similar ion doses.