Damage evolution in a-phase single crystals during He+ or H2+ ion bombardment was studied in an electron microscope. The bombardment was performed using 10keV He+ ions to a flux of 1013/cm2, or 15keV H2+ ions to a flux of 1014/cm2, at temperatures ranging from ambient to 1273K. It was found that dislocation loops and bubbles became larger in specimens which had been bombarded with H ions, as compared with those which had been bombarded with He ions. At higher temperatures, bubbles formed preferentially within dislocation loops. This was observed at lower temperatures under H-ion bombardment than under He-ion bombardment. These differences were suggested to be caused by a strong trapping of He atoms at bombardment-induced vacancies, which retarded the growth of loops or bubbles. In the case of H-ion bombardment, an enhanced point defect mobility due to H ions led to the formation of large loops or bubbles.

Damage Accumulation in Al2O3 during H2+ or He+ Ion Irradiation. N.Sasajima, T.Matsui, S.Furuno, K.Hojou, H.Otsu: Nuclear Instruments and Methods in Physics Research B, 1999, 148[1-4], 745-51