Damage in the cation substance of α-Al2O3 irradiated in an HVEM

α-Al2O3 has been irradiated at high temperatures with 300 keV electrons at which energy only aluminium ions are displaced. Systematic examination in a 100 kV electron microscope revealed pure edge dislocations of interstitial character with b = 1/3[0001] and b = 1/3[10 1-bar 0] lying on basal and prismatic brace 10 1-bar 0 brace planes respectively. The loops are stoichiometric but faulted on the aluminium sublattice. A model is proposed by which cation displacement at high temperatures results in aluminium interstitials precipitating between basal or brace 10 1-bar 0 brace prismatic planes with simultaneous diffusion of oxygen ions between the aluminium layers producing the faulted loops. (author)