Norm-Holl~d Publishing Company ATOMIC RESOLUTION OBSERVATIONS OF THE POINT DEFEXY’I ’ STRUCI’CJRE OF DEPLETED ZONES IN ION-IRRADIATED MJ2TAI.S *

The point defect structure of individual depleted zones (DZs) created by a variety of different projectile ions, with energies in the range 1 S-90 keV, was studied employing the field-ion microscope technique [l-9]. The irradiations were performed in situ at a temperature of less than. 15 K in the case of tungsten and 40 K for platinum. The fluence was always less then 1013 ions cmw2, so that each depleted zone detected was created by a single energetic projectile ion. The following variables were studied: (1) the effect of varying the initial energy of the projectile ion at constant projectile mass; (2) the effect of varying the projectile mass at constant initial energy of the projectile ion; and (3) the non-linear effects produced by employing diier ions (W2 ’ and A &). The analyses of the depleted zones consisted of measuring and/or determiuing the following quantities: (1) the number of vacancies per DZ; (2) the spatial distribution of self-interstitial atoms around the DZs in the case of tungsten; (3) the dimensions of the DZs; Q the vacancy concentration per DZ, (5) the radial ~st~bution function of the vacancies within each DZ; (6) the radiation damage profiles due to the cumulative ffects of many DZs; and (7) the non-linear effects produced by the dimer irradiations. The results are discussed and compared with different analytical theories and compute