DIFFUSION BEHAVIOR OF GOLD AND MERCURY IMPLANTED INTO MAGNESIUM

The annealing behaviour of magnesium foils of high purity (99.99%), im planted with 300-keV Au+ and Hg+ ions at 25 degrees C with various dos es ranging from 5 x 10(14) to 5 x 10(16) at./cm(2), was investigated. The samples were analysed by the Rutherford backscattering spectrometr y technique using a 2-MeV He-4(+) beam as a function of the annealing temperature. For the lowest-dose implant (1 x 10(15) Au+/cm(2)) agglom eration of Au at the surface and out-diffusion is clearly observed. Fo r high-dose implants the Au peak area decreases; however, it retains i ts shape with increasing annealing temperature. The decrease of the Au peak area occurs in two temperature stages indicating two different t rapping centers. As the second stage at higher temperature increases i n content relative to the first stage, it is speculated that the first stage is due to single Au atoms while the second one is due to Au pre cipitates, This study reveals that Hg atom diffusion is dependent on b oth the annealing temperature and the implanted dose. The Hg peak area decreases with increasing annealing temperature and reveals a shallow diffusion tail at a deeper depth. This indicates that Hg is released from a trap and is then subjected to a fast diffusion process. While f or the low-dose implant (5 x 10(14) Hg+/cm(2)) the release occurs at a nearly uniform rate, the high-dose sample (5 x 10(16) Hg+/cm(2)) exhi bits two release stages in the temperature regions between 150 degrees and 250 degrees C and between 300 degrees and 375 degrees C. The seco nd stage may be due to the dissolution of Hg precipitates.