Structural changes in spinel MgO•nAl2O3 single crystals, which had been bombarded with 900keV electrons or 1MeV Ne+ ions at 873K, were studied by means of electron channelling-enhanced X-ray microanalysis. Non-irradiated MgO•Al2O3 had a tendency to form the normal spinel configuration, where Mg2+ and Al2+ ions occupied mainly the tetrahedral and octahedral sites, respectively. It was found that electron irradiation introduced simple cation disordering between the tetrahedral and octahedral sites in MgO•Al2O3. In addition to cation disordering, a slight migration of cations from tetrahedral sites to octahedral sites occurred in a peak-damaged area of MgO•Al2O3 which had been bombarded with Ne+ ions. Cation disordering was suppressed in MgO•4Al2O3 which had been irradiated with electrons. The structural vacancies, which were present in the non-stoichiometric compound, appeared to be effective in promoting irradiation damage recovery via interstitial-vacancy recombination.

Cation Disordering in Magnesium Aluminate Spinel Crystals Induced by Electron or Ion Irradiation. T.Soeda, S.Matsumura, C.Kinoshita, N.J.Zaluzec: Journal of Nuclear Materials, 2000, 283-287, 952-6