Effects of the electric field on the aggregation of point defects in ion-irradiated α-Al₂O₃

We have investigated the effects of an electric field on the formation process of interstitial-type dislocation loops in α-Al₂O ₃ irradiated at 760 K with 100 keV He⁺ ions to a damage level of 0.5 displacements per atom. An electric field of 100 kV m^-1 depresses the density of dislocation loops and enhances their growth process, compared with the microstructure irradiated without an electric field. In addition, a higher fraction of interstitials escapes to surface sinks in a wedge-shaped thin-foil specimen when irradiated in the presence of an electric field. The kinetic behaviour of interstitials is discussed in terms of diffusion processes driven by the electric field and the concentration gradient. This is the first transmission electron microscopy observation to demonstrate the effects of an electric field on the aggregation of radiation-induced defects in α-Al₂O₃.